San Luis Potosı́, SLP, Mexico
.
1st International Workshop
on Matter Out of
Equilibrium
Instituto de Fı́sica, UASLP
Book of abstracts
.
8-12 December 2014
Contents
..
1
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2
Important Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3
Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4
Overview Lectures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
An overview of linear irreversible thermodynamics
Mariano López de Haro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Time dependent Forces in Polymer-Colloid Systems
P. Pincus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Inference in microscopy and biophysics
Philip Nelson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Colloidal gelation
Emanuela Zaccarelli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Nonlinear Glassy Rheology
Thomas Voigtmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
The Casimir Force in soft-matter physics
Robijn Bruinsma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Describing Non-equilibrium: Onsager and the Existence of Dynamically Arrested States.
Magdaleno Medina-Noyola . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Electrostatic self-assembly of biomolecules
Monica Olvera de la Cruz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Does entropy control the relaxation time?
Jeppe C. Dyre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Investigating the structure and dynamics of soft and biological materials using neutron scattering techniques
Yun Liu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
The SLAMs, BAMs, and Jams: every day is Black Friday in Biological Active Matter
Thomas Angelini
5
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Oral Presentations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Very soft-matter physics: the maximally fragile capsids of HIV.
Robijn Bruinsma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
iv
CONTENTS
Nonlinear glassy rheology: combining microscopic theory with macroscopic simulation.
Thomas Voigtmann . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Anomalous diffusion in binary glasses
Marco Laurati . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Two-dimensional phase behaviour of colloidal hard spheres with tuneable interactions
Anna Kozina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Heterogeneous Dynamics in Model Colloid-Polymer Mixtures on Crossing Kinetic Transitions
Pedro Dı́az-Leyva . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Assessment of the role of quantum corrections to the phase diagrams of confined fluids.
Alejandro Gil-Villegas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Magnetorheological fluids under time-dependent magnetic fields
Fernando Donado Pérez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Dynamical arrest in adhesive hard-sphere dispersions driven by rigidity percolation.
Ramón Castañeda-Priego . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Excess viscous response of protein solutions with glass-like dynamics due to competing potential features
Yun Liu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
On the jamming packing fraction of polydisperse hard-sphere mixtures.
Mariano López de Haro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Effective temperatures in short- and long time rheological properties of suspensions of solid
particles.
Ivan Santamará Holek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Random motility of Escherichia coli in a quasi-two-dimensional porous medium.
Jesús Santana Solano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Structural relaxation of stiff and long hard rods in suspension
Olegario Alarcón-Waess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Is there a glass transition in polydisperse hard spheres?
Emanuela Zaccarelli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
The influence of the corneal epithelial glycocalyx on the physicochemical surface properties
of the eye.
Bernardo Yañez Soto . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Flow mechanism in simple liquids and glasses
Takeshi Egami . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Explaining why simple liquids are quasi-universal
Jeppe C. Dyre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Thermal transport in composites with complex structure
José Luis Carrillo-Estrada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Tissue in motion: collective fluctuations in cell density and single cell volume oscillation
Thomas E. Angelini . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
The Viscosity of Salty Water.
Philip Pincus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Arrested States of Liquid Mixtures
Magdaleno Medina Noyola . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Static and dynamic equivalences in the hard-sphere dynamic universality class
Leticia López Flores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
CONTENTS
v
Equilibration and aging on repulsive glass-forming liquids
Pedro E. Ramı́rez Gonzalez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Low frequency modes anomalies and relaxation : from glasses to scientific citation networks
Gerardo G. Naumis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Statistical-Mechanical Theory of Nonlinear Density Fluctuations near the Glass Transition.
Michio Tokuyama . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Computer and experimental frustration of a freezing mechanism for Hard Disk
Adrián Huerta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Direct Extraction of Depletion Forces from Simulations
Gabriel Pérez Angel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Diffusion in charge stabilized colloidal suspensions: from short- to long-time regime.
Adolfo Javier Banchio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Colloidal structuring under confinement.
José Luis Arauz Lara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Equilibrium and non-equilibrium dynamics of liquids of non spherical particles: Self-consistent
theory of dynamical arrest in molecular Brownian fluids.
Luis Fernando Elizondo-Aguilera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Two techniques to tackle dynamics of spin glasses on random graphs
Isaac Pérez Castillo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Transient behavior vs. anomalous diffusion.
Leonardo Dagdug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Phase transitions in polyelectrolyte blends and networks driven by ionic correlations
Jos Zwanikken . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
The geometry and assembly of the rough endoplasmic reticulum
Jemal Guven . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Formation, structure, and dynamics of colloidal halos
J. M. Méndez-Alcaraz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
6
Poster Presentations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Geometrical model of the rough endoplasmic Reticulum
Dulce Maria Valencia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Analysis by Atomic Force Microscopy of biological activity of Castela texana in Porphyromonas
gingivalis.
Jorge Luis Menchaca Arredondo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Sequence length effects on the hysteresis phenomenon during DNA denaturation.
Luz Adriana Nicasio Collazo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Brownian motion of a single particle: the role of solvent.
Alexis Torres-Carbajal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Quasi-universal short-time dynamics in quasi-two-dimensional anisotropic colloidal mixtures.
José Ramón Villanueva-Valencia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Theory of free masonry
Gregorio Manrique Rodrı́guez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Montecarlo simulations of the mechanismo of acid coagulation of milk caseins
Marco Antonio Chávez-Rojo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
vi
CONTENTS
Transport properties for electrolytes using the MSA with a Yukawa closure
J. Noé F. Herrera Pacheco . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Investigating the roles of adhesion and cytoskeletal tension in mRNA localization
Susan M. Hamilla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Non-equilibrium scenarios in a model of colloid-polymer mixture
Edilio Lázaro Lázaro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Equilibration and aging of liquids of non-spherically interacting particles.
Ernesto Carlos cortes Morales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Macrophages Respond to Substrate Elasticity.
Katrina Adlerz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Corresponding States in the glass transition.
Adriana Andraca Gómez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Effect on Hydrocarbon tail length in phosphatidylcholines.
Alberto Sánchez Luviano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Interaction of anisotropic colloids with laser-induced external fields.
Erick Sarmiento-Gómez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
On the potential of mean force of a sterically stabilized dispersion
Rafael Catarino-Centeno . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Quantitative non-equilibrium molecular theory of the glass transition.
Patricia Mendoza-Méndez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Generalization of the SCGLE theory for mixtures of non-spherical interacting particles.
Pablo Fernando Zubieta Rico . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Dynamically arrested spinodal decomposition: a subtle interplay between thermodynamics
and kinetics.
José Manuel Olais Govea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Worm-like micelles in water solutions of 1,4 poly (1,3-butadiene)-polyethylene oxide diblock
copolymer
Brisa Arenas Gómez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Microrheology with DWS in absorbing media
Antonio Tavera Vazquez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Understanding Carbon nanotubes translocation into gigant vesicles
Carlos Moreno Aguilar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Design and Synthesis of a Nanovector for the Experimental Treatment of the Chagas Disease.
Karely Anaya Garza . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Giant Vesicles as a Cellular Model in the Internalization of Carbon Nanotubes
Veronica Pérez Luna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Complexity of the structure formed in magnetorheological fluids under an oscillating magnetic
field
Rosario E. Moctezuma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Ultrasoft systems and the hard-sphere dynamic universality class.
Sol Marı́a Hernández-Hernández . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Study of the interaction of nanostructured surfaces with cells using microfluidic systems
Leonardo Nuñez Magos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
CONTENTS
vii
Comparison between HNC/MSA theory for the electric double layer spherical and URMGC
theory: the reversal and amplification of charge
Evelyn Angélica Barrios-Contreras
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Importance of the GTPase Gpn3 in the nuclear accumulation of RNA polymerase II in breast
cells with increasing degrees of malignancy.
Bárbara Lara Chacón . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Effective charges and virial pressure of concentrated macroion solutions
Guillermo Ivan Guerrero Garcı́a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Numerical simulations of electrified oil/water interfaces: a coarse-grained approach.
Guillermo Ivan Guerrero Garcı́a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Folding of the apolipoprotein A1 driven by the salt concentration as a possible mechanism to
improve cholesterol trapping
Miguel Angel Balderas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Correlation between two particles in a confined system
Manuel de Jesús Sánchez Miranda . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Transport cycle importance nucleus cytoplasmic Gpn1 GTPase in the sub cellular localization
of RPAP2 and RNAPII
Esmeralda Nolasea Cruz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Brownian Repulsive and Attractive Correspondence in the Hard-sphere system
Leticia Lópes Flores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
7
Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Organizing Institutions
Organizing Committee
Sponsors
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.
Scope
Nowadays, most aspects of the physics of systems in equilibrium are well understood, thanks to a powerful
mathematical and physical framework given by statistical thermodynamics. The situation for systems
out of equilibrium, however, is less cheerful, and in some instances, there is a lack of any fundamental
understanding. As the number and relevance of issues involving non-equilibrium conditions become more
and more apparent in many research areas, particularly in soft condensed matter, there is an urgent
demand to bring forward new tools and concepts to fully tackle them. In order to face the fundamental
challenges of the study of out-of-equilibrium systems we will attempt to focus our efforts in understanding
two of the most paradigmatic: glasses and cells.
Glasses can be defined as amorphous solids formed by cooling a glass-forming liquid below its glass
transition temperature. Despite the abundant literature with experimental and theoretical work aimed
at explaining the properties of these systems, there is still not a fundamental interpretation that is
generally accepted. On the other hand, cells, the basic unit of life, are intrinsically and permanently
out-of-equilibrium, and due to the large amount of components and the diversity of temporal and spatial
scales, are very challenging to study. As such, glasses and cells are systems that offer a playground for the
convergence of several disciplines of research, such as non-linear science, soft matter physics, statistical
mechanics, chemistry and biology.
1.
Important Instructions
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For the poster presenters:
Please set up your poster during the registration period on Monday, December 8th (between 8:30 and
9:00 am). The posters will be in display throughout the workshop. The poster frames will be installed in
the Sky Room, located at the Penthouse of the hotel. On Tuesday, December 8th, following the poster
presentation, the posters will be moved to the Diplomatic Room, located at the mezzanine of the hotel.
On Friday, December 12th, the posters need to be removed by 4:00 pm.
Please support the organizers to comply with an important commitment with the sponsors of the Workshop to compile a list of possible/potential collaborations identified in the workshop. For this, before you
leave at the end of the workshop, please send us a brief description of at least two potential collaborations,
particularly those involving students and/or young researchers. You may use the format below.
2.
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1st INTERNATIONAL WORKSHOP ON MATTER OUT OF EQUILIBRIUM
NETWORKING
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POTENTIAL COLLABORATION 1
POTENTIAL COLLABORATION 2
Name
Name
Institution
Institution
Briefly describe tentative or definitive agreements
and the nature of the collaboration
Briefly describe tentative or definitive agreements
and the nature of the collaboration
3.
Program
.
.
In order to establish a common platform, the Workshop will have 40-minute overview lectures highlighting
systems whose non-equilibrium nature constitutes an essential barrier for its fundamental understanding.
The program also contains 25-munute lectures and two poster sessions on the specific work of our invited
speakers, organizers and additional participants (including students and postdocs).
4.
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Monday 8th
8:30-9:00
9:00-9:10
9:10-9:20
9:20-9:30
9:30-9:40
9:40-9:50
9:50-10:00
10:00-10:10
10:10-10:20
10:20-10:30
10:30-10:40
10:40-10:50
10:50-11:00
11:00-11:10
11:10-11:20
11:20-11:30
11:30-11:40
11:40-11:50
11:50-12:00
12:00-12:10
12:10-12:20
12:20-12:30
12:30-12:40
12:40-12:50
12:50-13:00
13:00-13:10
13:20-13:30
13:30-13:40
13:50-14:00
14:00-14:10
14:10-14:20
14:20-14:30
14:30-14:40
14:40-15:50
14:50-15:00
15:00-15:10
15:10-15:20
15:20-15:30
15:30-15:40
15:40-15:50
15:50-16:00
16:00-16:10
16:10-16:20
16:20-16:30
16:30-16:40
16:40-16:50
16:50-17:00
17:00-17:10
17:10-17:20
17:20-17:30
17:30-17:40
17:40-17:50
17:50-18:00
Tuesday 9th
..
Wednesday 10th
Thursday 11th
Friday 12th
Registration
Mariano
López de
Haro
Yun Liu
Tom
Angelini
Magdaleno
Medina
Phil Pincus
Monica
Olvera
Pedro
Ramı́rez
Philip
Nelson
Tom
Angelini
Emanuela
Zaccarelli
Luis
Fernando
Rojas
Iván
Santamarı́a
Holek
Isaac Pérez
Jos
Zwanikken
Coffee Break
Gerardo
Garcı́a
Naumis
Alejandro
Gil Villegas
José
Mendez
Alcaraz
Jeppe Dyre
Coffee Break
Coffee Break
Jeppe
Dyre
Robijn
Bruinsma
Thomas
Voigtmann
Emanuela
Zacarelli
Luis
Fernando
Elizondo
Robijn
Bruinsma
Olegario
Alarcón
Ramón
Castañeda
José Luis
Arauz
Adolfo
Banchio
Mariano
López de
Haro
Helim
Aranda
Gabriel
Pérez
Lunch
Lunch
José Luis
Carrillo
Pedro Dı́az
Leyva
Yun Liu
Poster
Session
Anna
Kozina
Takeshi
Egami
Bernardo
Yañes Soto
Magdaleno
Medina
Philip
Nelson
Luis E.
Sánchez
Michio
Tokuyama
Jesus
Santana
Adrian
Huerta
Coffee Break
Poster
Session
Leticia
López
Flores
Thomas
Voigtmann
Jemal
Guven
Leonardo
Dagdug
Fernando
Donado
Philip
Phincus
Marco
Laurati
Said
Aranda
Amir
Maldonado
5.
Overview Lectures
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Overview Lecture 1
An overview of linear irreversible thermodynamics
Mariano López de Haro
Instituto de Energas Renovables
Universidad Nacional Autónoma de México, Temixco, Mor. 62580 (MÉXICO)
The theory of linear irreversible thermodynamics was fully developed in the first half of the 20th
century. An overview will be provided of the assumptions underlying this theory, its microscopic foundations, and some of its great successes in the description and prediction of experimental results. Some
limitations and one attempt to extend it to the nonlinear regime will also be pointed out.
Overview Lecture 2
Time dependent Forces in Polymer-Colloid Systems
P. Pincus
Physics and Materials Departments
University of California, Santa Barbara
Colloidal particles suspended in a solvent are often decorated with physisorbed polymers in order to
provide stability against aggregation driven by ubiquitous attractive forces such as those engendered by
dispersion forces.
The elastic polymers act as bumpers that prevent the particles
from approaching one another sufficiently close to be mutually
bound in their Van de Waals wells. This, however, requires that
the polymers be irreversibly bound. This is not an issue for macroscopic surfaces but may be delicate when the polymer and colloid
dimensions are comparable. We will discuss the fundamental science of this problem and show that scientific questions are raised
which have yet to be adequately addressed.
Overview Lecture 3
Inference in microscopy and biophysics
Philip Nelson
University of Pennsylvania
I’ll discuss two situations in which knowing a little bit about probability goes a long way in helping
us to extract the meaning from experiments. The first involves superresolution microscopy. The second
involves changepoint detection in single-molecule studies of molecular motors.
7.
. The Casimir Force in soft-matter physics .
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Overview Lecture 4
Colloidal gelation
Emanuela Zaccarelli
CNR ISC and Sapienza University, Italy
In this lecture I will focus on different routes to colloidal gelation. Gels are low-density, disordered
arrested states that may have different origin. For colloidal particles intracting with isotropic attraction
on top of the hard-core repulsion, gelation results from an arrested phase separation and hence, it is a
non-equilibrium process. Instead, when interactions between particles are anisotropic, one can drive the
formation of gels in equilibrium. Some results from simple models will be discussed and their connection
with experimental systems.
Overview Lecture 5
Nonlinear Glassy Rheology
Thomas Voigtmann
DLR and University of Düsseldorf
Dense colloidal suspensions as well as non-colloidal glass-forming fluids driven out of equilibrium by
mechanical forces, show pronounced nonlinear flow effects. These are caused by a competition of slow
internal relaxation and the external driving. The microscopic processes that govern the macroscopic
material behavior are nonlocal both in time and space, encoding the divergence of viscosity in the fluid,
and the rigidity of the amorphous solid that forms at the glass transition. I will give an overview of
current theoretical approaches that approach the problem from either extreme, the homogeneous fluid
and the spatially heterogeneous amorphous solid.
Overview Lecture 6
The Casimir Force in soft-matter physics
Robijn Bruinsma
University of California Los Angeles.
An overview will be given of different versions of the Casimir Force encountered in soft-matter physics.
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Overview Lecture 7
Describing Non-equilibrium: Onsager and the Existence of Dynamically Arrested States.
Magdaleno Medina-Noyola
Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
The thermodynamic properties of equilibrium systems can be determined from ?first principles? (i.e.,
in terms of intermolecular forces) by the methods of statistical thermodynamics, whose great diversity
derives from a single fundamental physical principle: the principle of maximum entropy. In contrast, the
determination of the dynamic and transport properties (such as time-dependent correlation functions,
transport coefficients, etc.) is based on an array of approaches, including kinetic theory, fluctuating hydrodynamics, projection operators, mode-coupling theory, etc., with no apparent unifying general principle.
In this talk I discuss the proposal that Onsager?s theory of linear irreversible thermodynamics and of
time-dependent thermal fluctuations around the equilibrium state provides the most general and fundamental framework for the description of non-equilibrium phenomena. We then review a recent extension
of Onsager’s theory, to non-equilibrium non-stationary conditions. This extended theory reveals the existence of two fundamentally different classes of stationary states of a liquid: the first corresponds to the
ordinary thermodynamic equilibrium states and the second to kinetically arrested states, characterized
by the condition that the long-time asymptotic limit of (the eigenvalues of) the kinetic matrix vanishes
without requiring the thermodynamic equilibrium conditions to be fulfilled. We discuss the application
of these concepts to the description of the non-equilibrium diffusive and structural relaxation of a colloidal liquid under the influence of external fields, such as gravitational forces acting in the process of
sedimentation, but which may in the process be trapped in meta-stable or dynamically arrested states.
Electrostatic self-assembly of biomolecules
Overview Lecture 8
Monica Olvera de la Cruz1 *
University, United States
*Corresponding author: [email protected]
1 Northwestern
Biomolecules organize into supramolecular assemblies in environments containing many components
with ionizable groups. In this talk we discuss the assembly of charged heterogeneous molecules into
biomimetic structures including DNA-protein assemblies, amphiphiles assembled into biocompatible
fibers, and polyhedral shells that resemble organelles. In particular, we describe buckled polyhedral
vesicles by co-assembling amphiphiles with oppositely charged head groups (+3 and -1) into crystalline
bilayers. These membranes undergo highly specific molecular packing changes in response to changes in
the solution pH, resulting in different mesoscale morphologies and properties. These transformations allow the design of microcompartments that can open in response to external pH variations. The mesoscale
morphology is correlated to the intermolecular packing induced by altering the pH; switching from faceted
vesicles with hexagonal tail packing, to long bilayer ribbons or flat sheets for less symmetric tail packing.
We find re-entrant transitions in crystalline packing of the tails upon increasing the pH, with varying
symmetries and packing densities that depend upon the length of the carbon tails. Moreover, mixtures
of monovalent anionic and cationic surfactants generate micron-sized icosahedral vesicles. It has been
shown that segregation of the excess anionic component to the vertices, leads to 25-60 nm-diameter pore
9.
. Investigating the structure and dynamics of soft and biological
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materials using neutron scattering techniques .
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formation. We describe the relative importance of electrostatics and bending energy in the process. We
note that holes also arise in molecular ionic mixtures, generating perforated structures. We discuss the
relevance of these studies to materials science, biotechnology and medicine.
Overview Lecture 9
Does entropy control the relaxation time?
Jeppe C. Dyre
DNRF Center ?Glass and Time?, Roskilde University, Denmark.
We discuss the role of entropy for the relaxation time in supercooled glass-forming liquids as well as
in less-viscous ?ordinary? liquids. The talk is personal and subjective, starting from the fact that I for
many years was unable to understand why entropy could possibly have any relation to dynamics. After
all, a system doesn?t ?know? its entropy at any given time, because entropy is an ensemble quantity,
so how can entropy then control anything? The paper starts by summarizes briefly the early works by
Bestul and Chang and by Adam and Gibbs, followed by Rosenfeld’s fundamental entropy discovery from
the 1970’s [1] and by Dzugutov’s (independent) 1996 Nature paper [2]. If time permits the experimental
situation of today will be summarized. We then jump to developments of the last five years that have
elucidated entropy’s role via the study of a fairly large class of systems, the so-called Roskilde-simple
(Rs) systems comprising most or all van der Waals liquids and metallic liquids, as well as the weakly
ionic and/or dipolar liquids. For these liquids one may argue that it may be misleading to state that
?entropy controls the relaxation time? ? one might just as well say that ?the relaxation time controls the
entropy?! The argument is based on the existence of isomorphs in the thermodynamic phase diagram of
Rs systems, as reviewed in Ref. [3]. A very recent paper redefined Roskilde-simple liquids slightly [4];
here the isomorphs are defined to be the configurational adiabats, i.e., the curves in the phase diagram
of constant excess entropy.
References:
1. Y. Rosenfeld, Phys. Rev. A 15, 2545 (1977).
2. M. Dzugutov, Nature 381, 137 (1996).
3. J. C. Dyre, J. Phys. Chem. B 118, 10007 (2014).
4. T. B. Schrder and J. C. Dyre, J. Chem. Phys. 141, 204502 (2014).
Overview Lecture 10
Investigating the structure and dynamics of soft and biological materials using neutron scattering techniques
Yun Liu
Center for Neutron Research, National Institute of Standards and Technology, USA Department of
Chemical & Biomolecular Engineering, University of Delaware, USA
The fast development of novel materials and the necessity of understanding advanced systems in a
wide range of length scales require developing a fundamental understanding of the relationship between
structure/dynamics and physical properties of materials. Neutron scattering methods are very powerful
tools for these purposes, and are available for researchers worldwide in both small and large national
facilities. In this talk, I will present my personal view of the current status of applying neutron scattering
techniques to resolve important scientific problems with a focus on soft matter and biological materials.
The capabilities of different neutron scattering instruments will be mentioned within the discussions of
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research examples including shear banding of wormlike micelles, time-resolved liquid crystal formation of
micellar solutions under large amplitude oscillatory shearing forces, the structural evolution mechanisms
of micelle at non-equilibrium conditions, microstructure origins of anomalously high viscosity of cancer
treatment drugs. I will also discuss the gelation of colloidal systems, whose size ranges from a few
micrometer to a few nanometer, with examples including the bridging attraction induced gelation, the
implication of the percolation on structural arrest transitions, and possible glass-like transition of protein
systems.
Overview Lecture 11
The SLAMs, BAMs, and Jams: every day is Black Friday in Biological
Active Matter
Thomas Angelini
University of Florida, United States
Each year in the US, the holiday shopping season begins with a violent bang on the last Friday of
November, known as Black Friday. On Black Friday, shoppers gather in large, dense hoards at retail stores
across the country, colliding with one another while forming dense, collectively moving flocks, swarms,
and streaming flows, with each individual self-driven by a goal: find a bargain. The field of active matter
has grown out of studying this type of motion. Generally, scientists have not been interested in studying
collective motion in shopping hoards, but in other biological systems where dense groups of self-driven
objects often behave collectively: birds, bacteria, and tissue cells, for example. In this talk I will review
the history of the active matter perspective in biological systems, highlighting key theoretical foundations
and experimental breakthroughs. I will also review recent developments in biological active matter, where
jammed or glass-like behavior adds a second level to the out-of-equilibrium nature of these living, active
systems.
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Oral Presentations
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Very soft-matter physics: the maximally fragile capsids of HIV.
Oral Presentation 1
Robijn Bruinsma1 *
of California Los Angeles.
*Corresponding author: [email protected]
1 University
The protein capsid that surrounds the genome of a virus protects the viral genome against degrading
enzymes and also resist mechanical force. The capsid of the HIV is a remarkable exception: it is extraordinarily fragile. The talk will discuss why very fragile shells could play a key role in the life cycle of
retroviruses.
Nonlinear glassy rheology: combining microscopic theory with macroscopic simulation.
Oral Presentation 2
Thomas Voigtmann1 *
1 DLR and University of Düsseldorf
*Corresponding author: [email protected]
Glass-forming fluids show pronounced nonlinear out-of-equilibrium behavior when driven by mechanical forces. Their flow and deformation behavior shows aspects both of amorphous-solid-like plasticity
characterized by spatial heterogeneities, and of fluid-like rheology that is characterized by pronounced
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temporal-history effects that lead to process-dependent material properties. I discuss recent theoretical progress in understanding the resulting nonlinear response of dense fluids and glasses. Using new
continuum-mechanics simulation methods combined with microscopic theory and mesoscopic modeling,
we address the coupling of length and time scales in these systems far from thermodynamic equilibrium
and far from the linear-response regime.
Anomalous diffusion in binary glasses
Oral Presentation 3
Marco Laurati 1 *, T. Sentjabrskaja1 ,S. U. Egelhaaf1
1 Heinrich-Heine University, Düsseldorf
*Corresponding author: [email protected]
We present a confocal differential dynamic microscopy (con-DDM) study of the dynamics of a small
fraction of sub-resolution small spheres dispersed in concentrated suspensions of large spheres with different volume fractions. Increasing the degree of crowding of the large spheres host suspension, the small
particles dynamics slow down and progressively deviate from diffusive behavior, with the mean squared
displacements of the small spheres becoming sub-diffusive when the volume fraction of large spheres exceeds the glass transition critical value. For a size-ratio between small and large spheres approximately
equal to 1:3.5, the wave-vector dependent density-density correlators reveal the presence, in a specific
wave vector range, of a logarithmic decay, which indicates the vicinity of a transition between different
localisation mechanisms: Caging for size disparities smaller than 1:3.5, confinement for larger size disparities. The characteristic localisation length of the dynamics of small particles can be extracted from the
wave vector dependence of the correlators. This study indicates the potential of con-DDM for the spaceresolved investigation of anomalous diffusion of fluorescently labeled particles in complex environments.
Two-dimensional phase behaviour of colloidal hard spheres with
tuneable interactions
Oral Presentation 4
Anna Kozina1 *, Salvador Ramos2 , Pedro Dı́az-Leyva3 and Rolando Castillo4
1 IQ-UNAM, Mexico
2 Instituto de Fı́sica UNAM, Mexico
3 Departamento de Fı́sica UAM-I, Mexico
4 Instituto de Fı́sica UNAM,Mexico
*Corresponding author: [email protected]
The melting of three dimensional solid occurs via transition from the ordered phase to the liquid with
long-range positional order. Unlike 3D solid, two dimensional solids melt via successive dislocation
and disclination unbinding transitions as predicted by the Kosterlitz-Thouless-Halperin-Nelson-Young
(KTHNY) theory. The first transition is from the solid to a phase with a short-range positional order
and quasi-long-range orientational order, which is called hexatic phase. The second transition transforms
the hexatic phase to the liquid phase in which both positional and bond orientational orders have short
range. However, the experimental reality is often not that perfect, since the crystalline materials tent to
have grain boundaries and other defects that reduce their long-range order and modify their properties
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as compared to a single crystal. The number of crystal defects affects the grain size and as a result may
modify the mechanical and optical material properties. It is logical to presume that crystal defects may
originate from the type of the interactions present between the particles. Thus, we studied the crystallization behaviour in quasi 2D for nearly hard sphere colloidal particles where the interaction potential
was tuned by the particle surface modification. Three types of potential were used: purely repulsive (hydrophilic silica), attractive (sticky hard spheres, hydrophobic silica) and anisotropic (amphiphilic Janus).
The results of these studies will be discussed in the contribution.
Heterogeneous Dynamics in Model Colloid-Polymer Mixtures on
Crossing Kinetic Transitions
Oral Presentation 5
Pedro Dı́az-Leyva1 *, Anna Kozina2 , Eckhard Bartsch3 , Albert-Ludwigs4
1 Departamento de Fı́sica, UAM Iztapalapa, México
2 Instituto de Quı́mica-UNAM, México
3 Institut für Physikalische Chemie, Institut für Makromolekulare Chemie
4 Universität Freiburg
*Corresponding author: [email protected]
Dynamical heterogeneities are known to be a characteristic feature of the systems with slow relaxation
such as glasses and gels and are represented by the distribution of particle velocities or system relaxation
times. Often colloidal glasses and gels are spatially heterogeneous, which also results in heterogeneous
dynamics. The processes such as crystallization or gelation occur with such a system restructuring that it
usually gives origin to heterogeneous dynamics. In this contribution we will present the study of a model
colloid-polymer mixture where the gelation and phase separation are sufficiently slow to be tracked by
light scattering. We show that the dynamics evolve in time as the phase separation proceeds. The degree
of heterogeneity depends on the depth of the attraction potential defined by the polymer concentration
and on the restructuring processes occurring in each case.
Assessment of the role of quantum corrections to the phase diagrams of confined fluids.
Oral Presentation 6
César Serna1 ,Victor Manuel Trejos1 and Alejandro Gil-Villegas1 *
of Physical Engineering, University of Guanajuato, México
*Corresponding author: [email protected]
1 Department
Using a combined approach of Quantum Monte Carlo Simulations and perturbation theories, we have
studied the role of quantum corrections in the phase diagrams of confined fluids. We have found that
the determination of the range of values of thermodynamic degrees of freedom and molecular parameters
where quantum effects are important becomes very relevant in the study of adsorption of hydrogen on
different carbon-based substrates, like graphene.
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Magnetorheological fluids under time-dependent magnetic fields
Oral Presentation 7
Fernando Donado Pérez1 *, Rosario Moctezuma Martignon2 , José Luis Arauz Lara2
1 Universidad Autónoma del Estado de Hidalgo, Mexico
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
*Corresponding author: [email protected]
A magnetorheological fluid is a dispersion of magnetic particles in a nonmagnetic fluid, under a magnetic field, important structural and physical properties changes are observed. The aggregation process
is composed of various stages with characteristics that depend mainly on particle concentration and the
magnetic field strength. The addition of a perpendicular alternating magnetic field induces additional
changes which depend on frequency and strength of this second magnetic field. We have characterized
the structure formed by the particles in wide range of particle concentration. The multifractal analysis
seems a very useful tool to characterize the structure at high particle concentration. We discussed the
rheological behavior in terms of the structural changes.
Dynamical arrest in adhesive hard-sphere dispersions driven by
rigidity percolation.
Oral Presentation 8
3
Néstor E. Valadez-Pérez2 , Yun Liu2 , Aaron P. R. Eberle3 , Norman J. Wagner3 and Ramón
Castañeda-Priego1 *
1 Division of Science and Engineering, University of Guanajuatoo, Mexico
2 National Institute of Standards and Technology/University of Delaware, USA
Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD
20899, USA
*Corresponding author: [email protected]
One major goal in condensed matter is identifying the physical mechanisms that lead to arrested states
of matter, especially gels and glasses. The complex nature and microscopic details of each particular
system are relevant. However, from both scientific and technological viewpoints, a general, consistent
and unified definition is of paramount importance. Through Monte Carlo computer simulations of states
identified in experiments, we demonstrate that dynamical arrest in adhesive hard-sphere dispersions is
the result of rigidity percolation with coordination number, ⟨nb ⟩, equals to 2.4. This corresponds to
an established mechanism leading to mechanical transitions in network-forming materials [Phys. Rev.
Lett. 54, 2107 (1985)]. Our findings connect the concept of critical gel formation in colloidal suspensions
with short-range attractive interactions to the universal concept of rigidity percolation. Furthermore, the
bond, angular and local distribute ions along the gelation line are explicitly studied in order to determine
the topology of the structure at the critical gel state.
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Excess viscous response of protein solutions with glass-like dynamics due to competing potential features
Oral Presentation 9
P. Douglas Godfrin 1 , Steven D. Hudson2 , Kunlun Hong3 Lionel Porcar4 , Norman J. Wagner5 and Yun
Liu 1,5 *
1 Center for Neutron Science, Dept. of Chemical and Biomolecular Engineering, University of
Delaware, Newark, DE 19716, USA
2 NIST Polymers and Complex Fluids Group, National Institute of Standards and Technology,
Gaithersburg, MD 20899, USA
3 Center for Nanophase Materials and Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831,
USA
4 Institute Laue-Langevin, 38042 Grenoble Cedex 9, France
5 Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD
20899, USA
*Corresponding author: [email protected]
Colloidal systems with both a short-range attraction and long-range repulsion have attracted significant
research interests recently due to its relevance to many potential applications, such as the spontaneous
formation of structured patterns, understanding clustering effects with finite sizes in both globular protein
solutions and pharmaceutics, and investigating the effect of repulsion on glass transition and gelation.
However, the solution properties of this type of model systems have not been fully understood despite
many recent progresses in the field, especially in protein systems. In this talk, we report our recent
research efforts on both theoretical and experimental studies of lysozyme protein solutions. The cluster
formation phase diagram of lysozyme solutions at low salt conditions is investigated. The mean square
displacement of highly concentrated protein solutions is studied. We observed that the motions of proteins
can be highly localized at relatively long time scale and behaves similar to that of large colloidal systems
in glassy or gelled states even though the macroscopic properties of these protein samples show liquid-like
behavior characterized by a mico-capillary rheometer.
On the jamming packing fraction of polydisperse hard-sphere mixtures.
Oral Presentation 10
2
A. Santos and S. B. Yuste1 , Mariano López de Haro2 *, G. Odriozola3 , V. Ogarko4
1 Departamento de Fsica, Universidad de Extremadura, Badajoz, E-06071, Spain.
Instituto de Energas Renovables, Universidad Nacional Autnoma de Mxico, Temixco, Morelos 62580,
Mexico.
3 Programa de Ingeniera Molecular, Instituto Mexicano del Petrleo, Mxico, D. F. 07730, Mexico
4 Multi Scale Mechanics (MSM), CTW, MESA+, University of Twente, PO Box 217, 7500 AE
Enschede, The Netherlands
*Corresponding author: [email protected]
Jamming in real physical systems is an interesting and so far unsolved problem with important
practical applications. A prototype model to gain insight into this problem is a system of hard spheres.
In a recent proposal, the equation of state of a polydisperse hard-sphere mixture has been mapped onto
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that of the one-component fluid. Here this proposal is extrapolated beyond the freezing point to estimate
the jamming packing fraction ϕJ of the polydisperse system as a simple function of a scaling parameter
involving the first three moments of the size distribution. An analysis of experimental and simulation
data of ϕJ for a large number of different mixtures shows a remarkable general agreement with the
theoretical estimate. To give extra support to the procedure, simulation data for seventeen mixtures
in the high-density region are used to infer the equation of state of the pure hard-sphere system in the
metastable region. An excellent collapse of the ! inferred curves up to the glass transition and a significant
narrowing of the different out-of-equilibrium glass branches all the way to jamming are observed. Thus,
the present approach provides an extremely simple criterion to unify in a common framework and to give
coherence to data coming from very different polydisperse hard-sphere mixtures. A possible extension of
the approach to d-dimensional hard-spheres will also be pointed out.
Effective temperatures in short- and long time rheological properties of suspensions of solid particles.
Oral Presentation 11
Carlos I. Mendoza1 and Ivan Santamará Holek 1 *
1 UMDI-Facultad de Cieincias, UNAM, Mexico
*Corresponding author: [email protected]
We discuss recent advances in the description of the rheological properties of suspensions of solid
particles at arbitrary concentrations. In particular, we show that confining forces, incorporated in simple
theoretical descriptions via excluded volume effects, can be considered as the leading factor for determining the dependence on the volume fraction of the viscosity and the diffusion coefficients. Under this
perspective, an universal scaling behavior is found for the viscosity, and two different mechanisms are
found to be behind the short and long time behavior of the diffusion coefficient. The existence and role
of effective temperatures is briefly discussed in these systems and in the context of active microrheology
in glasses. Comparison of our models with experimental data is excellent in all cases.
Random motility of Escherichia coli in a quasi-two-dimensional porous
medium.
Oral Presentation 12
1 Centro
Juan Eduardo Sosa Hernández1 and Jesús Santana Solano1 *
de Investigacin y de Estudios Avanzados del Instituto Politectecnico Nacional Unidad
Monterrey, Mexico
*Corresponding author: [email protected]
Bacterial migration in confined spaces is critical for many practical problems ranging from biofilm
formation to bacterial transport in soils. In this work, we measured the single-cell motility parameters
such as cell velocity, mean squared displacement and turn angle for Escherichia coli MG1655 confined in
a bidimensional matrix of obstacles. The porous medium is built with uniform polystyrene particles of
2.9 microns trapped by two glass plates in a disordered configuration. Phase contrast microscopy is used
to measure the migration of bacteria as a function of particle concentration. The setup allows measuring
both the influence of walls as well as the interaction with the obstacles in the cell motility. It was
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found that the mean speed of the cells decreases linearly with the particle density and that the bacteria
are capable of swimming through even small cavities except when the spheres are in a close-packing
configuration.
Structural relaxation of stiff and long hard rods in suspension
Oral Presentation 13
Olegario Alarcón-Waess1 *
de las Amricas Puebla, San Andres Cholula, Mexico
*Corresponding author: [email protected]
1 Universidad
Some of the novel challenges are the understanding and the prediction of non-equilibrium phenomena
in non-spherical colloids. In this direction, we focus on the structural relaxation from a fully aligned
configuration to its corresponding isotropic or ordered phase, which can be monitored by means of time
resolved small angle depolarized dynamic light scattering. Assuming that the position coordinates are
always in equilibrium during reorientation of the rods the dynamic structure factor is computed and
provided its physical meaning. By using the Landau-de Gennes extended thermodynamic approach the
relationship between the equilibrium structure factor and the collective fluctuations of the second order
parameter is given. The structural properties in and out equilibrium is provided by the Smoluchowski
formalism and the rods interaction is modeled with the Maier-Saupe effective potential. In equilibrium
our results are in qualitative agreement with those of Onsager. The extended thermodynamic description
provides us with novel observables out of equilibrium related with the alignment of rods, the isothermal
orientational compressibility and the osmotic orientational pressure.
Is there a glass transition in polydisperse hard spheres?
Oral Presentation 14
Emanuela Zaccarelli1 *, Siobhan Liddle1 and Wilson Poon1
1 CNR ISC and Sapienza University, Italy
*Corresponding author: [email protected]
In the last years, significant discussion in the scientific community has taken place concerning the
glass transition of hard sphere (HS) colloidal particles following the experimental results by Brambilla and
coworkers, appeared in Phys. Rev. Lett. In 2010. This work on colloidal HS pushed the observation time
to unprecedented range and found that the glass transition, expected at packing fraction ϕ ∼ 0.58 − 0.59
was avoided. Rather a dynamical singularity was suggested by an exponential (rather than power-law)
dependence of the relaxation close to random close packing. This work claimed thus that activated
processes preempted the occurrence of a glass transition in hard spheres, in clear contradiction with the
predictions of the widely used Mode Coupling Theory.
Taking into account the polydispersity of the measured samples, which amounts to more than 10%, we
perform event-driven numerical simulations of polydisperse hard spheres with particle size distributions
(PSD) of several shapes, including (for the first time) a PSD measured experimentally by transmission
electron microscopy (TEM) for polydisperse PMMA colloids very similar to those used by Brambilla
and coworkers. We present results for the diffusion coefficient and relaxation time and find that the
average diffusion coefficient (or equivalently relaxation time) is independent of the shape of the PSD, but
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only depends on the variance, and confirm the experimental findings that no arrest occurs for packing
fractions up to ≈ 0.60. However, when we focus our attention on subpopulations of particles, we observe a
dramatic dependence of dynamics on the PSD. For the experimental PSD we find that the large particles
undergo an ideal glass transition, compatible with MCT predictions, at a packing fraction close to 0.59
while the small particles remain mobile. A difference of almost two orders of magnitude in the diffusion
coefficient makes the polydisperse system behave effectively like a multi-component mixture, suggesting a
localisation transition of a fraction of the particles previously found only in asymmetric binary mixtures.
Moreover, for ϕ ∼ 0.59 we also observe an unusual ‘partial aging’, i.e. A clear dependence on the waiting
time elapsed before the measurement, which is more marked for the largest particles. Our results show
how a significant degree of polydispersity in the particles smears out the glass transition. To check our
conclusions, we also simulated a system with somewhat lower polydispersity, and recovered the ’standard’
glass transition predicted by MCT. Thus, in our view, the hard-sphere glass transition remains intact,
and the observed residual ergodicity at ϕ ∼ 0.6 is not evidence for activated dynamics but an effect of
polydispersity.
The influence of the corneal epithelial glycocalyx on the physicochemical surface properties of the eye.
Oral Presentation 15
Bernardo Yañez Soto1 *, Brian Leonard2 , VijayKrishna Raghunathan3 , Nicholas Abbott4 and
Christopher Murphy5
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
2 William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University
of California, Davis, USA
3 Department of Surgical and Radiological Sciences, University of California, Davis, USA
1 Chemical and Biological Engineering, University of Wisconsin, Madison, USA
1 Department of Surgical and Radiological Sciences, University of California, Davis, USA
*Corresponding author: [email protected]
Dry eye syndrome (DES) is a heterogeneous group of ocular surface disorders that are characterized
by deficiency of the aqueous component of tears, excessive evaporation and/or insufficient wettability
of the epithelial surface. The high wettability of the ocular surface has traditionally been attributed to
the existence of a thick glycocalyx covering the cell surface, composed mainly of membrane-associated
mucins and other glycosylated proteins. In this word, we investigate the influence of the glycocalyx
on the wettability of the ocular epithelium. The expression of mucins on the apical surface of human
hTERT immortalized corneal epithelial cells (hTCEpi) is induced by culturing with stratification medium
(DMEM/F12 supplemented with 10 ng/mL EGF and 10% FBS) for up to 7 days. The surface properties (wettability, surface energy, contact angle hysteresis) are determined by measuring the sessile drop
contact angle using a two fluid method, with PBS as the medium and perfluorocarbon (perfluorodecalin,
perfluorooctane or tetradecafluorohexane) as the drop. Our findings indicate that the differences in surface properties are mainly due to the patterned expression of mucins; and these may be related to the
stability of the tear film.
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Flow mechanism in simple liquids and glasses
Oral Presentation 16
1 University
Takeshi Egami1 *
of Tennessee, 208 South College 1413 Circle Drive Knoxville, TN 37996-1508
*Corresponding author: [email protected]
The atomistic mechanisms of flow in simple liquids and glasses are discussed. Even though viscosity is
one of the most fundamental properties of a liquid its atomistic mechanism has been poorly understood.
Through simulation we found that in high-temperature liquid the atomic bond cutting and forming are
the elementary excitations which quantitatively explain viscosity. In glasses the bond excitations are
coupled, but critical actions are always quite localized. For instance mechanical deformation is triggered
by a cluster of a small number (∼5) of atoms which initiates avalanche. Through these results we argue
that the most important structural descriptor of liquids and glasses is not the actual atomic position,
but the topology of atomic connectivity. The application of this idea to soft colloid is discussed.
Explaining why simple liquids are quasi-universal
Oral Presentation 17
Andreas K. Bacher1 , Thomas B. Schrøder1 and Jeppe C. Dyre1 *
1 DNRF Centre ‘Glass and Time’, IMFUFA, Department of Sciences, Roskilde University, Postbox 260,
DK-4000 Roskilde, Denmark
*Corresponding author: [email protected]
The motivation of this paper is that in order to understand out-of-equilibrium matter and other
complex situations and systems, it makes sense to start by studying simple matter in thermal equilibrium,
in particular when there is still something to be learnt in this field. Thus it has been known for a long
time that many simple liquids have surprisingly similar structure as quantified, for example, by the radial
distribution function. A much more recent realization is that the dynamics are also very similar for a
number of systems with quite different pair potentials. Systems with such non-trivial similarities are
generally referred to as ”quasi-universal”.
From the fact that the exponentially repulsive pair potential has strong virial potential-energy correlations in the low-temperature part of its thermodynamic phase diagram, we here show that a liquid
is quasi-universal if its pair potential can be written approximately as a sum of exponential terms with
numerically large prefactors. Based on evidence from the literature we moreover conjecture the converse,
that is, that quasi-universality only applies for systems with this property.
Reference: A. K. Bacher et al., Nat. Commun. 5, 5452 (2014) - doi: 10.1038/ncomms6424 (2014).
[Will appear November 14]
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Thermal transport in composites with complex structure
Oral Presentation 18
J J Reyes-Salgado1 , V Dossetti1 , B. Bonilla1 and José Luis Carrillo-Estrada1 *
Universidad Autónoma de Puebla, Apartado Postal 1152, 72000 Puebla, PUE., México
*Corresponding author: [email protected]
1 Benemérita
In this work, we discuss on the thermal transport properties of plate-like composite samples made
of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy and thermal relaxation, the thermal diffusivity, conductivity and heat capacity of the samples were experimentally
measured. The volume fraction of inclusions was systematically varied in order to study the changes
in the effective thermal conductivity of the composites. In some samples, a static magnetic field was
applied during the polymerization process resulting in anisotropic inclusion distributions. Our results
show a decrease in the thermal conductivity of some of the anisotropic samples compared to the isotropic
randomly distributed ones. We discuss these results by correlating the complexity measures of the inclusion structure with the observed thermal response by a multifractal analysis, and on this basis we
propose an effective media approach. Additionally we explore the modulation of the thermal diffusivity
of composite two-layer systems [1].
[1] F. Cervantes, J. J. Reyes, V. Dossetti, and J. L. Carrillo, J. Phys. D: Appl. Phys. 47 235303 (2014);
J J Reyes-Salgado, V Dossetti, B. Bonilla, and J. L. Carrillo, J. Phys. D: Appl. Phys. (2014).
Tissue in motion: collective fluctuations in cell density and single
cell volume oscillation
Oral Presentation 19
Steven M. Zehnder1 , Tapomoy Bhattacharjee1 and Thomas E. Angelini1 *
1 University of Florida, US
*Corresponding author: [email protected]
Many analogies between living tissue cells and inanimate condensed matter have been identified recently.
The glass transition, jamming behavior, nucleation and growth of clusters, and nematic ordering – just
to name a few – have been discovered and investigated in multi-cellular systems. Our understanding of
these collective behaviors is built upon knowledge of cell-cell interactions and single cell properties. In
recent work on collective cell behavior in monolayers, we have found that single cell motion and cell-cell
coupling possess an unexpected property: cell volumes fluctuate, and cells are physically coupled through
fluid channels that connect neighbors. In this talk I will describe these cell volume fluctuations at the
single cell level, explore transfer of fluid between neighbors, and link fluid transport to collective motion
at the multi-cellular scale.
The Viscosity of Salty Water.
Oral Presentation 20
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Philip Pincus1 *
and Materials Departments University of California, Santa Barbara
*Corresponding author: [email protected]
Dynamics in aqueous media depends on the fluid viscosity. This suggests that understanding water
dynamics in the presence of various additives provides the basic required science. The viscosity of water
with added salts and other solutes has been measured for nearly 100 years. Nevertheless an understanding
of the role of added electrolytes beyond the most rudimentary level has remained elusive. We will discuss
this puzzle in the context of dilute salt solutions with some suggestions for possible ways forward.
Arrested States of Liquid Mixtures
Oral Presentation 21
1 Instituto
Magdaleno Medina Noyola1 *
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
The concept of effective pair potentials (Asakura-Oosawa for depletion forces, DLVO for screened Coulomb
interactions) constitute a useful tool for understanding equilibrium and dynamical properties of many
soft materials. Under some circumstances, however, the limitations of these concepts arise, such as when
the polymer depletant or the electrolyte concentration are too large. Under these conditions one may
have to describe these systems as what they actually are, i.e., a liquid mixture (of colloid and polymer
in the first example, or of colloid and ions in the second). This may be particularly important under
conditions in which the dynamics of one or both of the two species becomes dynamically arrested. In
this work we describe the possible dynamic arrest scenarios predicted to arise in simple models of liquid
mixtures. These involve attractive and (hard-sphere and Wigner) repulsive glasses, electrostatic and
colloid-polymer gels obtained by arrested spinodal decomposition, etc.
Static and dynamic equivalences in the hard-sphere dynamic universality class
Oral Presentation 22
1 Instituto
Leticia López Flores1 *, Martı́n Chavez Páez1 and Magdaleno Medina Noyola1
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
We perform systematic simulation experiments on model systems with soft-sphere repulsive interactions
and attractive interactions to test the predicted dynamic equivalence between soft-sphere liquids with
similar static structure. For this we compare the simulated dynamics (mean squared displacement,
intermediate scattering function, ?-relaxation time, etc.) of different soft-sphere and attractive systems,
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between them and with the hard-sphere liquid. We then show that the referred dynamic equivalence does
not depend on the (Newtonian or Brownian) nature of the microscopic laws of motion of the constituent
particles, and hence, applies independently to colloidal and to atomic simple liquids. Finally, we verify
another more recently proposed dynamic equivalence, this time between the long-time dynamics of an
atomic liquid and its corresponding Brownian fluid (i.e., the Brownian system with the same interaction
potential).
Equilibration and aging on repulsive glass-forming liquids
Oral Presentation 23
Pedro E. Ramı́rez Gonzalez1 *, Luis Enrique Sánchez-Dı́az2 and Magdaleno Medina-Noyola3
CONACyT, Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San
Luis Potosı́, Álvaro Obregón 64, 78000 San Luis Potosı́, SLP, México.
2 Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831,
USA.
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
1 Catedrático
The recently developed non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE)
theory is applied to the description of the irreversible process of equilibration and aging of a glass-forming
soft-sphere liquid that follows a sudden temperature quench. This theory describes the non-equilibrium
evolution of the static structure factor S(k; t) and of the dynamic properties, such as the self-intermediate
scattering function FS (k,τ ; t), where τ is the correlation time and t is the waiting time after the quench.
Specific predictions are presented for the deepest quench (to zero temperature). The predicted evolution
of the α-relaxation time τα (t) as a function of t allows us to define the equilibration time teq (ϕ), as the
time after which τα (t) has attained its equilibrium value ταeq (ϕ). It is predicted that both, teq (ϕ) and
ταeq (ϕ), diverge as ϕ → ϕA , where ϕA is the hard-sphere dynamic-arrest volume fraction (≈0.582). The
theory also predicts that for fixed finite waiting times t, the plot of ταeq (t; ϕ) as a function of ϕ exhibits two
regimes, corresponding to samples that have fully equilibrated within this waiting time, and to samples
for which equilibration is not yet complete. The crossover volume fraction ϕC (t) increases with t but
saturates to the value ϕA .
Low frequency modes anomalies and relaxation : from glasses to
scientific citation networks
Oral Presentation 24
Gerardo G. Naumis 1 * and J.C. Phillips2
1 Depto. De Fsica-Qumica, Instituto de Fsica, UNAM Mxico, D.F.
2 Rutgers University, Piscataway, N.J., USA
*Corresponding author: [email protected]
Glasses, granular media, colloids and other disordered systems present excess of low frequency vibrational
modes, like the floppy modes or the Boson peak. The origin of these modes are explained by rigidity
theory, in which bonds are treated as mechanical constraints. Using these ideas, we will show how to
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explain the variation of glass transition temperature with chemical composition, glass forming ability
and thermodynamical properties. Also, these ideas can be extended to describe relaxation in glasses, in
which the exponents of the stretched exponential take two universal magic values, as has been confirmed
in very recent experiments. Then we will show that the network of scientific citations follows the same
law, with a transition between the two magic numbers in 1960. Finally, a simple non-linear model for
glass relaxation, based in the Fermi-Pasta-Ulam, is presented. This model displays energy relaxation
as in turbulence, where low frequency modes are responsible of energy disipation. This model can be
mapped to the protein folding problem.
Statistical-Mechanical Theory of Nonlinear Density Fluctuations
near the Glass Transition.
Oral Presentation 25
Michio Tokuyama1 *
University, Japan.
*Corresponding author: [email protected]
1 Tohoku
The Tokuyama-Mori type projection-operator method is employed to study the dynamics of nonlinear
density fluctuations near the glass transition. A linear non-Markov time-convolutionless equation for
the scaled scattering function f (q, t) is first derived from the Newton equation, leading to a formal
solution f (q, t) = Exp[−K(q, t)]. Within the mode-coupling theory (MCT) approximations, the linear
non-Markov equation for the cumulant function K(q, t) is then obtained, where the nonlinear memory
function is the same as that obtained in ideal MCT. The Debye-Waller factor and a two-step relaxation
process are discussed analytically and are compared with those of MCT. The full numerical solutions are
also compared with those of MCT based on the Percus-Yevick model for hard spheres as a preliminary
test. The critical volume fraction (0.5817) is then shown to be much higher than that of MCT (0.516).
Thus, it is emphasized that the present theory may overcome at least one of difficulties discussed in the
ideal MCT.
Computer and experimental frustration of a freezing mechanism for
Hard Disk
Oral Presentation 26
1
Adrián Huerta1 *
Facultad de Fı́sica e I.A., Universidad Veracruzana, México.
*Corresponding author: [email protected]
In this talk we discuss the structure and thermodynamic properties of different models of fluids that
shows frustration of a freezing mechanism proposed originally for hard disk system. We also compare
with some experimental models.
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Direct Extraction of Depletion Forces from Simulations
Oral Presentation 27
Gabriel Pérez-Angel,1 *, Ramón Castañeda-Priego2 and José Méndez-Alcaraz3
de Fı́sica Aplicada, CINVESTAV del IPN, Unidad Merida, Merida, Yuc. MEXICO
2 Division de Ciencias e Ingenierı́a, Universidad de Guanajuato, León, Gto. MEXICO
3 Departamento de Fı́sica, CINVESTAV del IPN, Mexico DF, MEXICO.
*Corresponding author: [email protected]
1 Departamento
We show a consistent way of evaluating depletion forces in a binary colloidal dispersion for any
values of the densities of the components. The method works without confining the kinematics of the
system, and therefore obtains the depletion forces in equilibrium. The forces obtained are approximated
only in that they are considered as pair interactions, and incorporate three- and many-body effects as
averaged corrections. We compare the results obtained with those from a straightforward extension of the
projection method used in infinitelly diluted systems (just one pair of particles), and show the existence
of consistent deviations between the two approaches. In fact, the extension of the projection method to
dense systems generates the mean force, instead of the depletion force.
Diffusion in charge stabilized colloidal suspensions: from short- to
long-time regime.
Oral Presentation 28
A. J. Banchio1 *, M. Heinen, P. Holmqvist and G. Nägele
y FaMAF, Universidad Nacional de Córdoba
*Corresponding author: [email protected]
1 IFEG-CONICET
Collective and self-difusion in concentrated suspensions of charge-stabilized colloidal spheres are extensively studied. Theoretical calculations, from mode-coupling theory and simulations are confronted
with experimental results. Correlation times ranging from colloidal short-time to long-time regime are
considered. The intermediate, and self-intermediate scattering functions, the mean square displacement,
and other dynamic quantities, are calculated by accelerated Stokesian Dynamics (ASD) simulations where
many-body hydrodynamic interactions (HIs) are included, and additionally Brownian Dynamics (BD)
simulations and mode-coupling theory (MCT) calculations without HIs included. On the basis of this
results, the influence of HIs on the dynamics, and the accuracy of the MCT method are analized. In theory and simulation, the spheres are assumed to interact directly by a hard-core plus screened Coulomb
effective pair potential. The system size corrected dynamic scattering functions obtained in the ASD
simulations are in decent accord with our dynamic light scattering (DLS) data for a concentration series
of charged silica spheres in an organic solvent mixture, within the experimentally accessed time window.
We hereby provide a full overview on diffusion processes in charge-stabilized suspensions.
Colloidal structuring under confinement.
Oral Presentation 29
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M. Sanchez-Miranda1 , A. Ramirez-Saito1 and J. L. Arauz-Lara1 *
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
*Corresponding author: [email protected]
The correlation between a pair of colloidal particles confined in a spherical cell is determined by
optical microscopy. We study pairs of 1 micron size spherical particles confined in water droplets in the
range of 4 microns to 10 microns in diameter. The three-dimensional trajectories of both particles are
determined by the analysis of their corresponding point spread functions, and the distribution of distances
obtained from the trajectories. We found that the pair produces well defined averaged structures. In
addition, we also measure dynamic properties of the pair such as the relative mean squared displacement.
Equilibrium and non-equilibrium dynamics of liquids of non spherical particles: Self-consistent theory of dynamical arrest in molecular Brownian fluids.
Oral Presentation 30
3 Facultad
Luis Fernando Elizondo-Aguilera1 *
de Ciencias Fı́sico-Matemáticas, Benemérita Universidad Autónoma de Puebla. Apartado
Postal 1152, 72000 Puebla, PUE, México
*Corresponding author: [email protected]
A self-consistent generalized Langevin equation (SCGLE) theory is proposed to describe the self and
collective dynamics of a liquid of linear Brownian interacting particles. The equations of motion for the
spherical harmonics projections of the collective and self intermediate scattering functions, Flm,lm (k, τ )
S
and Flm,lm
(k, τ ), are derived as a contraction of the description involving the stochastic equations of
the corresponding tensorial density nlm (k, τ ) and the translational (α=T) and rotational (α=R) current
densities jαlm (k, τ ). These dynamic equations require as an external input the equilibrium structural
properties of the system contained in the projections of the static structure factor, Slm,lm (k). Complementing these exact equations with simple (Vineyard-like) approximate relations for the collective and
the self-memory kernels, we propose a closed self-consistent set of equations for the dynamic properties
involved. In the long-time asymptotic limit, these equations become the so-called bifurcation equations,
whose solutions (the nonergodicity parameters) can be written in terms of one translational and one
orientational scalar dynamic order parameters, γT and γR , which characterize the possible dynamical
arrest transitions of the system. As an addtional bonus, we also employ this theory to develop the
non-spherical version of the non-equilibrium SCGLE of equilibration and aging, in order to describe a
suddenly-quenched colloidal liquid of particles interacting through non spherically-symmetric pairwise
interactions. As a concrete application, we show that the resulting self-consistent equations may provide
a simple description of the rotational dynamics of a classical Heisenberg spin liquid and of its spin glass
transition when applied to a liquid of dipolar hard spheres with quenched positional disorder.
Two techniques to tackle dynamics of spin glasses on random graphs
Oral Presentation 31
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Isaac Pérez Castillo1 *
Instituto de Fı́sica, UNAM, P.O. Box 20-364, 01000 México, D.F. , México
*Corresponding author: [email protected]
Considering the very rich out-of-equilibrium properties one encounters in spin glasses, one would
like to have powerful mathematical tools to analyse them. In this talk I will briefly present the main
approaches to study dynamics of mean-field type spin glass models and how these must be adapted for
systems on random graphs.
Based on work:
1. J.P.L. Hatchett, B. Wemmenhove, I. Perez Castillo, T. Nikoletopoulos, N.S. Skantzos and A.C.C.
Coolen, Parallel dynamics of disordered Ising spin systems on finitely connected random graphs, J. Phys.
A 37 (2004), 6201-6220.
2. J. P. L. Hatchett, I. Perez Castillo, A. C. C. Coolen, N. S. Skantzos, Dynamical replica analysis of
disordered Ising spin systems on finitely connected random graphs, Phys. Rev. Lett. 95 (2005), 117204.
Transient behavior vs. anomalous diffusion.
Oral Presentation 32
Leonardo Dagdug1 *, A. Berezhkovskii and S. Bezrukov
1 Universidad Autónoma Metropolitana, México
*Corresponding author: [email protected]
In this talk we will discuss the main aspects of diffusion when the Brownian motion of point-like
particles take place under the influence of confinement and/or obstacles. It will be understood under
which circumstances one can observe transient behavior of the effective diffusion coefficient and where
anomalous diffusion is obtained. This discussion is crucial to understand the experimental results and
the data got from numerical simulations. This discussion has been generated important debates in the
last year in the community dedicated to measure transport properties, with great impact especially in
biological systems.
Phase transitions in polyelectrolyte blends and networks driven by
ionic correlations
Oral Presentation 33
Jos Zwanikken1 * and Monica Olvera de la Cruz1
1 Northwestern University, USA
*Corresponding author: [email protected]
Developments in ‘smart’ materials and devices for energy storage rely heavily on the versatile properties of charged polymers. Charged copolymers can self-assemble into membranes with nanoscopic phases
that can support (ion-specific) current and provide mechanical stability at the same time. With statistical
thermodynamic analysis, we investigate the ionic structure in polyelectrolyte materials, and its effect on
larger scale thermodynamic properties. We evaluate the ionic correlations with liquid-state methods, and
predict opposite trends that depend on the properties of the ions. The phase diagrams can be shifted in
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multiple directions by tuning the size and charge of the ionic components. From our analysis we distill
ion-driven mechanisms that tune the properties of polyelectrolyte materials.
The geometry and assembly of the rough endoplasmic reticulum
Oral Presentation 34
Jemal Guven1 *
1 Instituto de Ciencias Nucleares, UNAM, México
*Corresponding author: [email protected]
We present a model describing the geometry as well as the assembly of the rough endoplasmic reticulum (RER), a vitally important intracellular membrane because of its function as the site of protein
synthesis. In this model, the membrane stacks within the RER organize around ’Terasaki ramps’, the
recently discovered helicoidal connections linking adjacent sheets within the stacks. The fundamental
unit is a localized symmetric double-ramped ’parking garage’ formed by two separated gently-pitched,
approximately helicoidal, ramps of opposite chiralities (a dipole). The sheets connected by these ramps
are flat outside the dipole core, consistent with the laminar geometry. The geometry is stabilized by
a short-range repulsive interaction between ramps associated with bending energy which opposes the
long-range attraction associated with tension. Each sheet consists of a pair of lipid bilayers enclosing a
lumen; the concentration of membrane-shaping proteins along inner boundaries in turn stabilizes individual ramps against collapse. We propose a mechanism for parking garage self-assembly via the nucleation
of dipoles at the center of the tubular three-way junctions within the neighboring smooth ER.
Jemal Guven, Greg Huber, and Dulce Mara Valencia, Phys. Rev. Lett. 113, 188101 (2014).
Formation, structure, and dynamics of colloidal halos
Oral Presentation 35
1 Department
J. M. Méndez-Alcaraz1 *
of Physics, Cinvestav, Av. IPN 2508, Col. San Pedro Zacatenco, 07360 México, D. F.,
Mexico.
*Corresponding author: [email protected]¿
By means of computer simulations a neutral spherical substrate is placed in the bulk of a suspension
of colloidal particles interacting with a long-ranged repulsive potential. Some of the particles are then
observed to adsorb on the surface of the substrate, building colloidal halos. We obtain the conditions for
the halos formation and find out that the number of adsorbed particles follows scaling laws as function of
the microscopic variables of the system. We also study the angular distribution of the adsorbed particles
along the spherical surface of the substrate, finding it to jump alternately between fluid- and crystal-like
structures for some magic numbers of adsorbed particles. Regarding the dynamics of the halos, they
display two new time regimes in addition to the short- and long-time ones usually found in open colloidal
systems.
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Poster Presentations
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Geometrical model of the rough endoplasmic Reticulum
Poster Presentation 1
Jemal Guven1 and Dulce Maria Valencia1 *
1 ICN-Cinvestav IPN, Mexico
*Corresponding author: [email protected]
We present a model describing the morphology as well as the assembly of Terasaki ramps, the recently
discovered helicoidal connections linking adja- cent sheets of the rough endoplasmic reticulum (ER). The
fundamental unit is a localized symmetric double-ramped ?parking garage? formed by two sep- arated
gently pitched, approximately helicoidal, ramps of opposite chiralities. This geometry is stabilized by
a short-range repulsive interaction between ramps associated with bending energy which opposes the
long-range attraction asso- ciated with tension. The ramp inner boundaries are themselves stabilized by
the condensation of membrane-shaping proteins along their length. A mecha- nism for parking garage
self-assembly is proposed involving the nucleation of dipoles at the center of tubular three-way junctions
within the smooth ER. Our predictions are compared with the experimental data.
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Analysis by Atomic Force Microscopy of biological activity of Castela
texana in Porphyromonas gingivalis.
Poster Presentation 2
F.E. Melendez Anzures1 , M.P.a Barrn Gonzlez1 , L.R. Ovalle Flores 1 , A. Elizondo Herrera1 and J.L.
Menchaca Arredondo,1 *
1 Universidad Autónoma de Nuevo León., Mexico
*Corresponding author: [email protected]
The use of medicinal plants is one of the oldest human activities for the treatment of diseases. It has been
reported that C. texana have compounds with antimicrobial activity. According to WHO, periodontal
disease is the second most common oral pathology affecting 5% -20% of adults between 30 and 60 years
around the world. P. gingivalis is a microorganism with a diameter of 0.5-0.8 m and 1.0-3.5 m of length,
involved in the initiation and progression of chronic and aggressive periodontal disease and is considered
as the main etiological agent. The AFM allows the study of the surface microtopography generating highresolution three-dimensional images and detecting the mechanical properties such as adhesion, hardness,
elasticity and resistance without altering or damaging the surface of the sample. Its introduction in
microbiological studies, allowed to use this device for the analysis of bacterial morphology. In this
study was evaluated the biological activity of methanolic extract of C. texana in P. gingivalis and its
nanomechanical morphological analysis by AFM. The results indicate that the methanolic extract of C.
texana present inhibitory activity on the in vitro growth of P. gingivalis and modified its mechanical
properties such as: elasticity, adhesion and hardness.
Sequence length effects on the hysteresis phenomenon during DNA
denaturation.
Poster Presentation 3
Luz Adriana Nicasio Collazo1 *
1 Universidad de Guanajuato, México
*Corresponding author: adriana− [email protected]
When hysteresis is present during the DNA denaturation, a DNA damage connection could be established.
We thus study selectively to what extent cellular stress may occur by analyzing the thermodynamic
behavior and the presence of hysteresis in pressure-driven DNA denaturation; large presence of hysteresis
in the denaturation/renaturation curves may point out from a thermal susceptibility to DNA damage.
We will focus our interest in a particular set of genes associated with Diffuse Large B-Cell Lymphoma.
As a result of this study we will emphasize the importance of the sequence length on the hysteresis
phenomenon.
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Brownian motion of a single particle: the role of solvent.
Poster Presentation 4
Alexis Torres-Carbajal1 *
1 Universidad de Guanajuato, México
*Corresponding author: [email protected]
We study the dynamical behavior of a nano-colloid immersed in an explicit solvent by means of the
molecular dynamics simulations. The generalized Langevin equation is rewritten in the framework of the
theory of Mori, where we use the lineal momentum of the Brownian particle as the relevant observable
to describe the Brownian motion. We analyze the way in which the nature of the solvent, namely,
pure repulsive and an attractive one, affects the dynamics of the colloid at short-times. We particularly
observe that the dynamics correlation functions of both solvents have a similar behavior, but the analysis
of the memory kernel, the function associated with the fluid response to the movement of the colloid,
shows a clear differenceof the action of the solvent on the colloid particle. We also study the behavior
of the dynamics correlationfunction of the random force with the lineal momentum of the nano-colloid.
In conclusion, the nature of the solvent affects the dynamical behavior of nano-colloid in the short-time
scale, a fact that is usually ignored in the classical Langevin description.
Quasi-universal short-time dynamics in quasi-two-dimensional anisotropic
colloidal mixtures.
Poster Presentation 5
José Ramón Villanueva-Valencia1 *, Erick Sarmiento-Gómez2 , Salvador Herrera-Velarde1 , José Luis
Arauz-Lara2 , Ramón Castañeda-Priego1
1 Universidad de Guanajuato, Mexico
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
*Corresponding author: [email protected]
In this work, we report on the short-time dynamics of colloidal particles in a suspension made up of
monomers and dimers confined between two glass-plates. The short-time diffusion coefficient is studied
by means of video-microscopy experiments, molecular dynamics simulations with explicit solvent, and
a theoretical framework based on the Navier-Stokes equation that allows us to theoretically explain the
diffusion coefficient of dimers at very low particle concentrations. In order to quantify the diffusion in all
the relevant directions, the mean-square displacement is decomposed in both parallel and perpendicular
directions respect to the main axis of the dimer. Additionally, we also measure the mean-square displacement of the center-of-mass of particles. Our observations show that the ratio of the short-time diffusion
coefficient of the sphere respect to the dimer remains practically independent of the total packing fraction. This means that the hydrodynamics interactions are factorable in the same way in both species and
are the responsible for the decreasing of the collision rate between particles when the concentration is
increased, which leads to a universal particle dynamical behavior even at high concentrations. Our findings are explicitly corroborated with molecular dynamics simulations that introduce the hydrodynamic
interactions through the explicit incorporation of the solvent molecules in our calculations.
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Theory of free masonry
Poster Presentation 6
Jemal Janer Guven Seery1 and Gregorio Manrique Rodrı́guez1 *
1 Instituto de Ciencias Nucleares, UNAM, Mexico
*Corresponding author: [email protected]
We present a theoretical framework to describe how membranes and other surfaces bend subject to
local geometric constraints and external forces. We show how this framework can be applied to throw
light on a classical problem from a soft-matter perspective: The equilibrium and stability of thin-wall
architectural structures. The equilibrium shapes minimizing gravitational potential energy consistent
with a constraint on the metric satisfy the following – deceptively simple – shape equations
∇a σ ab = 0,
σ ab Kab = ρ(hK − n̂ · k̂).
where σab is the stress tensor associated with the constraint, Kab is the extrinsic curvature tensor with
trace K and n̂ is a normal vector.
These equations are solved for simple historically significant geometries: catenary arches and spherical
domes. The distribution of stress established within these structures is discussed. To assess the stability
of a given shape, we introduce an anisotropic bending energy
∫
∑
1
dA
(Ci − Ci )2
HB [X] =
2
i
where Ci are the principal curvatures in the target geometry. Penalizing deviations in the curvature about
its equilibrium values.
We derive the linear partial differential operator controlling these deformations. As an application we
examine the spectrum of this operator for a catenary arch and comment on its stability.
Montecarlo simulations of the mechanismo of acid coagulation of
milk caseins
Poster Presentation 7
Tonatiuh Sosme-Sánchez1 , Néstor Gutiérrez-Méndez1 , Luz Marı́a Rodrguez-Valdez1 , José Manuel
Nápoles-Duarte1 , Marı́a Elena Fuentes-Montero1 and Marco Antonio Chávez-Rojo1 *
1 Universidad Autnoma de Chihuahua, Mexico
*Corresponding author: [email protected]
In this work we present a computer simulation study, based on parameters obtained from experimental
methods, of the mechanism of acid coagulation of milk caseins. The model considers the colloidal interactions among casein micels, specifically, electrostatic, steric and Van der Waals forces; in order to
determine the aggregation (coagulation) as a function of the thermodynamic properties of the system.
Casein micels were modeled as charged spheres with a size distribution ranging from 50 to 500 nm. By
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means of Montecarlo simulations, it was possible to plot an aggregation diagram in terms of pH, concentration and temperature. The parameters required to construct the interaction potential were obtained
from rheology and calorimetry experiments of a casein suspension.
Transport properties for electrolytes using the MSA with a Yukawa
closure
Poster Presentation 8
J. Noé F. Herrera Pacheco1 *, Juan Montes-Pérez1 and Eduardo González Jiménez1
de Ciencias Fı́sico-Matemáticas, Benemérita Universidad Autónoma de Puebla. Apartado
Postal 165, Col. Centro, Puebla, Pue., México, C. P. 72000.
*Corresponding author: [email protected]
1 Facultad
In a linear response theory in which Onsager?s continuity equations are combined with the Mean
Spherical Approximation (MSA) equilibrium correlation functions and using Green?s response functions
formalism, we find the transport properties of an electrolyte. We use an intermolecular potential between
ions of Yukawa type, which satisfies the electroneutrality condition. This model contains a parameter
z, which can be adjusted to consider solvent effects. The dominant forces that determine the transport
processes in an ionic solution are the relaxation and electrophoretic forces. These contributions are
calculated using the Fouss-Onsager theory for transport properties computed by linear response, from
which we get the conductance and the self-diffusion coefficients for a family of electrolytes. The theoretical
predictions can be adjusted to experimental results using the parameter z. The electrophoretic effect is
due to hydrodynamic interaction between the ions, and is calculated using the Rotne-Prager tensor. The
theoretical and experimental results for 1:1 electrolytes are in good agreement even for high densities.
Investigating the roles of adhesion and cytoskeletal tension in mRNA
localization
Poster Presentation 9
Susan M. Hamilla,1,2 *, Stavroula Mili2 and Helim Aranda-Espinoza1
1 University of Maryland, Fischell Department of Engineering, College Park, MD USA
2 National Institutes of Health, Bethesda, MD USA
*Corresponding author: [email protected]
Cells create protrusions to aid in migration and guidance. These protrusions require specific proteins
that might need to be synthesized locally. mRNAs play an important role in cellular migration and
localize to protrusions during migration to aid in local protein synthesis. RNAs accumulate at sites
of new integrin engagement, at lamellipodia, and at sites of early or persistent protrusion formation.
In one pathway, the tumor suppressor protein, adenomatous polyposis coli (APC) targets RNAs to
cell protrusions. APC associates with many RNAs in protrusive areas, including Ddr2, Rab13, and
Pkp4. Most studies investigating mRNA localization have been performed on very rigid glass substrates.
However, cells modify their spreading and migration behavior based on the extracellular matrix stiffness.
Additionally, ECM stiffness varies throughout the body based on tissue type and location. Therefore,
it is important to take into account the role of extracellular matrix stiffness and it is affect on mRNA
localization.
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The goal of this project is to determine how APC-associated mRNA localization changes on substrates
of varying stiffnesss and dissect the mechanism of localization on the substrates. Using fluorescence insitu hybridization (FISH) and polyacrylamide gels of varying stiffness, we were able to observe mRNA
localization in fibroblasts. Using a method called the ‘edge ratio’ method, we were able to quantify
mRNA localization. The edge ratio is a measure of the fraction of RNA in the periphery of the cell
compared to the fraction of area in the cell periphery. This value is then compared to a control, or diffuse
RNA. We observed that cells plated on stiff substrates (280kPa) had increased Ddr2 mRNA localization
compared to soft (1kPa) substrates.
To dissect the mechanism of Dd2 localization, we hypothesized it was related to cytoskeletal tension
and adhesion within the cell. Previous studies have shown that mechanical tension recruits mRNA to
integrins. The identity or mechanism of this recruitment has not been studied. Immunostaining of
actin, paxillin, tubulin, and de-tyrosinated tubulin was performed on the substrates of varying stiffness
in addition to FISH. It was found that mRNAs were located at the tips of de-tyrosinated tubulin on
stiffer substrates and expression of de-tyrosinated tubulin was reduced on soft substrates. Futhermore,
localized mRNAs were found in proximity of focal adhesions.
In conclusion, this study investigates mRNA localization as a function of substrate stiffness. Cells
alter their mRNA localization based on substrate stiffness, and this is related to cytoskeletal tension and
adhesion.
Non-equilibrium scenarios in a model of colloid-polymer mixture
Poster Presentation 10
1 Instituto
Edilio Lázaro Lázaro,1 * and Magdaleno Medina Noyola1
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
*Corresponding author: [email protected]
Colloid-polymer mixtures may experience many equilibrium and non-equilibrium phases. This depends, largely, on the polymer concentration and the polymer-colloid size ratio. In this work, we present
a study of the scenarios of dynamic arrest in a model of colloid-polymer mixture. We have used the multicomponent Non-equilibrium Self Consistent Generalized Langevin Equation theory (NE-SCGLE theory)
and the Asakura-Oosawa binary mixture model as our theoretical description of the colloid-polymer mixture. We show theoretical results about the non-equilibrium dynamics as the waiting-time dependence
of the self intermediate scattering function, diffusion coefficients of both particles and the dynamic arrest
lines for mild- to long-range polymer-colloid size ratio.
Equilibration and aging of liquids of non-spherically interacting particles.
Poster Presentation 11
Ernesto Carlos Cortes Morales1 *, Luis Fernando Elizondo Aguilera2 and Magdaleno Medina Noyola1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
2 Facultad de Ciencias Fı́sico-Matemáticas, Benemérita Universidad Autónoma de Puebla. Apartado
Postal 1152, 72000 Puebla, PUE, México
*Corresponding author: [email protected]
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In this work we present an extension of the non-equilibrium self-consistent generalized Langevin equation theory (NE-SCGLE) to describe the irreversible evolution of the static and dynamic properties of a
Brownian liquid of particles with non radially-symmetrical interactions, in search for a new thermodynamic equilibrium state after, for example, a sudden and deep temperature quench. As a concrete and
illustrative application for our formalism, we consider a classical dipolar Heisenberg with positional disorder near to glass transition (known as spin-glass transition) modeled as a liquid of dipolar hard spheres
with quenched positional disorder within the constraint that the local mean particle density remains
uniform and constant.
Macrophages Respond to Substrate Elasticity.
Poster Presentation 12
1 Fischell
Katrina Adlerz1 *,Heather N. Hayenga2 and Helim Aranda-Espinoza1
Department of Bioengineering, University of Maryland, College Park, MD 2 Department of
Bioengineering, University of Texas, Dallas, TX
*Corresponding author: [email protected]
Many studies have shown atherosclerotic plaques are heterogeneous in stiffness. What still remains
unclear, however, is how this heterogeneous environment affects the evolution of the plaque and its
cellular components. We hypothesized that macrophages are sensing and responding to the changing
stiffness. To investigate this, macrophages were plated on polyacrylamide gels varying in stiffness from
soft (1, 3, and 5 kPa) to stiff (280 kpa). Timelapse microscopy captured images over 20hrs and ImageJ
was used to track cells. Macrophages on the stiff gel traveled at 12.5 um/hr, significantly faster than
the average 6.6 um/hr for cells on the soft substrates. Cells were also plated on 400um circles, stamped
with fibronectin, to observe cell proliferation over 72 hours. Macrophages on the stiff substrates had a
significantly smaller doubling time than those plated on soft substrates. Furthermore, f-actin content in
macrophages also depends on substrate stiffness. On soft substrates actin is spread uniformly throughout
the cytoplasm, whereas on 280 kPa substrates, actin is organized into stress fibers. Finally, macrophages
had an 8-fold larger area on stiff polyacrylamide gels compared to soft gels. Therefore, our results suggest
that macrophages are mechanosensitive and respond to changes in stiffness by modifying their area and
function. These results are important in understanding how macrophages respond in complex mechanical
environments such as an atherosclerotic plaque.
Corresponding States in the glass transition.
Poster Presentation 13
Adriana Andraca Gómez1 *, Patricia Goldstein Menache1 and Luis Felipe del Castillo Dávila2
1 Facultad de Ciencias UNAM, Mexico
2 IIM UNAM, Mexico
*Corresponding author: [email protected]
We study the dependence of logarithmic shift factor (LSF) with the temperature during the supercooled liquid regime for several fragile glass formers. For temperatures above Tc (Tc ∼ 1.2Tg ) we find
that the LSF obeys the Williams-Landel-Ferry equation expressed in a linear form. From this fact we
find that the viscosities of the studied liquids present a corresponding state behavior through a master
plot in terms of an adimensional temperature.The viscosity behavior with temperature below Tc , is fitted
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with a proposed empirical equation in order to find the corresponding states and a master plot in this
range.
Effect on Hydrocarbon tail length in phosphatidylcholines.
Poster Presentation 14
Alberto Sánchez Luviano1 *, José Luis Méndez Montes de Oca1 and Gabriel Espinoza Pérez1
1 Instituto de Fı́sica y Matemáticas UMSNH, México
*Corresponding author: [email protected]
Phosphatidylcholine (PC) are a major constituent of cell membrane, and is more commonly found in
the exoplasmic or outer leaflet, it is a neutral lipid, but it carries an electric dipole of about 10D. We analyze the isotherms of Langmuir monolayers at 20o C of four phosphatidylcholines among which we have 1,2dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC),
1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
(POPC), these are one of the principals components in eukariotik cell membranes, the principal difference
between these lipids is the length of its hydrocarbon tail and this change affect its fusion point provoking
a increase or decrease in the fluidity of the membrane. Another difference between one of these lipids is
a double bond in one of the hydrocarbon tails which lowers the fusion point.
Interaction of anisotropic colloids with laser-induced external fields.
Poster Presentation 15
Erick Sarmiento-Gómez1 * and José Luis Arauz-Lara1
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
*Corresponding author: [email protected]
In this work we present preliminary results of the interaction of anisotropic colloids with periodic
laser-induced external fields. Shape anisotropy of colloids and spatial anisotropy of the external field
induce preferred colloidal dynamics depending on potential periodicity and strength, and on the spatial
characteristics of the anisotropic colloids. Additionally, an experimental insight of the response of a
perfect colloidal crystal to deformation is given.
On the potential of mean force of a sterically stabilized dispersion
Poster Presentation 16
Rafael Catarino-Centeno1 *, Elas Pérez-Lpez1 and Armando Gama-Goicochea1
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
*Corresponding author: [email protected]
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The potential of mean force (PMF) of a colloidal dispersion under various circumstances of current
interest, such as varying solvent quality, polymer coating thickness, and addition of electrostatic interaction is obtained from radial distribution functions available from the literature. They are based on an
implicit solvent, molecular dynamics simulation study of a model TiO2 dispersion that takes into account
three major components to the interaction between colloidal particles, namely van der Waals attraction,
repulsion between polymer coating layers, and a hard core particle repulsion. Additionally, a screened
form of the electrostatic interaction was included also. It is argued that optimal conditions for dispersion
stability can be derived from a comparative analysis of the PMF under the different situations studied.
This thermodynamics based analysis is believed to be more accessible to specialists working on the development of improved TiO2 formulations! than that based on the more abstract, radial distribution
functions.
Quantitative non-equilibrium molecular theory of the glass transition.
Poster Presentation 17
Patricia Mendoza-Méndez1 *, M. A. Ojeda-López1 , L. E. Sánchez-Dı́az2 and M. Medina-Noyola1
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831,
USA.
*Corresponding author: [email protected]
1 Instituto
2
We demonstrate that the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE)
theory of irreversible processes, derived from a non-stationary, atomic-scaled extension of Onsager’s theory of thermal fluctuations and irreversible processes, provides the first non-equilibrium quantitative
molecular theory of the glass transition and of the structural relaxation of glass-forming liquids. This
theory predicts the existence of two kinetically distinct and fundamentally different categories of stationary states of matter. The first corresponds to ordinary thermodynamic equilibrium states, kinetically
approached within a finite equilibration time teq . The second refers to non-ergodic, dynamically arrested states, such as glasses and gels, which are predicted to age forever toward their final asymptotic
non-equilibrium stationary state, approached in a far slower fashion. The equilibration time teq and
the corresponding equilibrium α-relaxation time of thermodynamic equilibrium states are predicted to
diverge when the boundary between the regions corresponding to these two kinds of states is approached.
To test some of these predictions we perform non-equilibrium simulations in which a soft-sphere glassforming liquid, initially at an ergodic equilibrium state, is suddenly quenched to a lower final temperature
that lies either (a) also in the ergodic domain, or (b) in the region of kinetically arrested states. We find
that within their finite waiting-time window, the simulations quantitatively confirm the general trends
predicted by the theory.
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Generalization of the SCGLE theory for mixtures of non-spherical
interacting particles.
Poster Presentation 18
Pablo Fernando Zubieta Rico1 *, Luis Fernando Elizondo Aguilera2 and Magdaleno Medina Noyola3
1 CINVESTAV Unidad Querétaro, MEXICO
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México
3 Facultad de Ciencias Fı́sico-Matemáticas, Benemérita Universidad Autónoma de Puebla. Apartado
Postal 1152, 72000 Puebla, PUE, México
*Corresponding author: [email protected]
A self-consistent generalized Langevin-equation theory is proposed to describe the self and collective
dynamics of a mixture of linear Brownian particles. The equations of motion for the spherical harmonics
projections of the collective and self-intermediate-scattering functions, are derived as a contraction of
the description involving the stochastic equations of each of the tensorial single-species densities and
their respectives translational and rotational densities. Similar to the spherical case, these dynamic
equations require as an external input the equilibrium structural properties of the system contained
in the projections of the static structure factor. Complementing these exact equations with simple
(Vineyard-like) approximate relations for the collective and the self-memory functions we propose a
closed self-consistent set of equations for the dynamic properties involved. In the long-time asymptotic
limit, these equations become the so-called bifurcation equations, whose solutions (the nonergodicity
parameters) can be written, extending the spherical case, in terms translational and orientational scalar
dynamic order parameters, which characterize the possible dynamical arrest transitions of the system.
Dynamically arrested spinodal decomposition: a subtle interplay
between thermodynamics and kinetics.
Poster Presentation 19
José Manuel Olais Govea1 *, Leticia López-Flores1 , Pedro Ramı́rez-González1 and Magdaleno Medina
Noyola1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
Using the non-equilibrium self-consistent generalized Langevin equation (NE-SCGLE) theory [Phys. Rev.
E 82, 061503 (2010)], we perform a systematic analysis of the irreversible relaxation of the static and
dynamic properties of a simple liquid suddenly quenched from supercritical conditions to its gas-liquid
coexistence. According to the resulting scenario, the spinodal line, besides being the threshold of thermodynamic instability of homogeneous states, also turns out to be an ergodic–non-ergodic transition
line. This scenario derives from the NE-SCGLE predicted behavior of the non-stationary structure and
dynamics of the system as a function of the waiting time tw after the instantaneous quench to final density and temperature (n, T ) inside the spinodal. We monitor specifically two dynamic order parameters,
namely, the particles mobility b(tw ; n, T ) and the square localization length γ(tw ; n, T ). First, the analysis of the asymptotic limits ba (n, T ) ≡ limtw →∞ b(tw ; n, T ) and γa (n, T ) ≡ limtw →∞ γa (tw ; n, T ) reveals
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that, for shallow quenches ((n, T ) inside but close to the spinodal line) one should expect loosely-arrested
states with very large γa , unable to interfere with the process of classical spinodal decomposition. For
deeper quenches (e.g., lower final temperature T ) γa (n, T ) exhibits a sharp discontinuity to much smaller
values, typical of hard-sphere glasses. This discontinuity defines a “loose glass - tight glass” transition,
which is in fact the continuation to low densities and low temperatures inside the spinodal, of the highdensity high-temperature liquid-to-glass transition. This predicted long-time asymptotic scenario is, by
definition, unobservable within experimental waiting times. The NE-SCGLE theory, however, also describes the full non-equilibrium evolution of b(tw ; n, T ) and γ(tw ; n, T ), thus predicting the scenario that
one should observe at arbitrary finite waiting times. According to such predictions, the sharp dynamic
arrest lines characteristic of the long-time asymptotic scenario will appear as soft crossovers in any actual
finite-time experimental measurement or simulation.
Worm-like micelles in water solutions of 1,4 poly (1,3-butadiene)polyethylene oxide diblock copolymer
Poster Presentation 20
Brisa Arenas Gómez1 *, Marko Vincekovic, Antonio Tavera-Vázquez, Cristina Garza, and Rolando
Castillo1
1 Instituto de Fı́sica UNAM, México.
*Corresponding author: [email protected]
The main purpose of this study is to determine for the first time the structure of the self-assembled
aggregates in the system made of 1,4 poly(1,3-butadiene)-polyethylene oxide diblock copolymer (IUPAC
name: poly(but-2-ene-1,4-diyl)-block-polyoxyethylene) and water, and the rheological behavior of the
solution. The degree of polymerization of the polybutadiene and polyethylene oxide blocks is 37 and 45,
respectively. The diblock copolymer concentration was limited to be 2.5 wt% to avoid phase separation.
Small X-ray scattering revealed that the diblock copolymer self-assembles in worm-like micelles with a
diameter of 12 nm. This system does not closely follow the rheological behavior of worm-like micelle
solutions made of typical surfactants. The system steadily shear thins reaching very low viscosity values
at large shear rates, however there are not shear-thickening peaks. In thixotropic loops, the micellar
solution does not present hysteresis. The viscoelastic spectra do not follow the Maxwell model at low
and intermediate frequencies. This uncommon behavior for a worm-like micellar system is explained by
the slow dynamics of the self-assembly. The extremely high hydrophobicity of the polybutadiene block
does not allow any micellar rearrangement.
At concentrations above 1 wt% flow curves show a stress plateau region where the wormlike micelle
fluid is inhomogeneous, here the fluid is divided into two macroscopic regions. One region shows a strong
birefringence related to micellar orientation and high shear rate flow. The second region is isotropic and
it flows at low shear rate. We present preliminary results of shear banding studies in this system by using
transparent Couette rheometer. Also we present optical characterization of this system using the Inverse
Adding Doubling technique.
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Microrheology with DWS in absorbing media
Poster Presentation 21
Antonio Tavera-Vazquez1 *, Erick Sarmiento-Gomez2 , Brisa L. Arenas-Gomez1 and Rolando Castillo1
1 Institute of Physics UNAM, México.
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
The technique of diffusive wave spectroscopy (DWS) is a technique of dynamic light scattering used as
a method of microrheology based on the theory developed by Mason in order to get the viscoelastic
spectrum of complex fluids. Inherent to the diffusion approximation of the light propagation in a turbid
medium used in DWS, there is a limitation in the kind of fluids that are allowed to be under study: these
must be transparent to the wavelength of the light during the experiment. A theory of DWS that takes
into account the effects of absorption of light in the medium was recently developed which involves a term
la, called absorption mean free path, included in the diffusion approximation, that corrects the theory of
DWS to be used in turbid absorbing media generalizing its use to a wider range of complex fluids. In this
work we show some preliminary experimental results for the calculation of the absorption mean free path
and the transport mean free path of light, l*, that have to be measured independently of each other. For
this purpose we applied the method of inverse adding doubling (IAD) developed by Prahl, to a system
of block copolymers (polybutadiene ? polyethylene oxide or PBPEO), to get la and l*. We also tried
to apply the method to aqueous samples at different concentrations of single walled carbon nanotubes
(SWNT) with not enough success because of the huge darkness of the substance. Before that, we use
a known system of colloidal microspheres with a diameter of 800nm to corroborate the experimental
setup and to compare the results with the current theory. Finally we present the experimental setup
implemented in the complex fluids laboratory at the Institute of Physics at UNAM.
Understanding Carbon nanotubes translocation into gigant vesicles
Poster Presentation 22
Carlos Moreno Aguilar1 *, Veronica Pérez Luna1 , José Luis Arauz-Lara1 , Said Aranda-Espinoza1 , José
Alfredo Mendez1 and Mildred Quintana1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
The development of carbon nanotube materials for drug delivery is an area of research that holds great
promise. Understanding the mechanisms responsible for CNTs internalization into live cells is considered
critical both from a fundamental point of view and for further engineering of CNT-based delivery systems.
In this work we present a study of the internalization of CNT into giant vesicles as a simple representation
of the basic structure of the cellular membrane. We observed that the s-MWNT were always able to
penetrate into the GUVs and were localized mostly on the surface of the vesicles. Measurements of FRET
efficiency can be used to determine if two fluorophores are within a certain distance of each other, we
will use this phenomenon to confirm the localization of s-MWNTs in the hydrophobic region of the lipid
bilayer. We can use the chromophore Rodamine B to dye the hydrophobic part of the GUVs and using
s-MWNTs functionalized with Quantum Dots (QDs) with an emission maxima near 585 nm to see if
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theres an interaction between the hydrophobic part of the Egg-PC lipid of the GUVs and the s-MWNTs.
This strategy allows a simpler experimental manipulation of the system permitting us to follow the CNT
internalization process by optical and confocal microscopy.
Design and Synthesis of a Nanovector for the Experimental Treatment of the Chagas Disease.
Poster Presentation 23
Karely Anaya Garza1 * Isaac Mata Cruz1 , Vanesa Olivares Illana1 and Mildred Quintana1
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
1 Instituto
A nanovector is a chemical entity used as carrier of molecular drugs directed to a specific target. Generally, these contain: 1) a carrier nanostructure, 2) a drug, 3) a labeling agent that allows its location, 4)
a recognition agent that guides it to the target and 5) a biocompatibility agent to reduce its toxicity.
In this work we show the design, synthesis and characterization of a nanovector for controlled release
of the 6, 6’- bisbenzothiazol-2, 2’diamine (V7), a specific drug for the treatment of the Chagas disease1 .
The nanovector was synthesized using Multi-walled Carbon Nanotubes (MWCNTs), since it has been
experimentally shown that they are able to internalize cell membranes without damaging them. The
MWCNTs were previously oxidized (ox-MWCNTs) and functionalized covalently with the biocompatibility agent 1, 11-Diamino-3, 6, 9-trioxaundecan2 . This facilitates the dispersion in water, thus increasing
biocompatibility. Later, V7 was non-covalently attached through supramolecular interactions of type π-π
stacking to the ox-MWCNT, to obtain V7-ox-MWCNTs3 .
[1] Olivares-Illiana, V.; Prez Comonfort, R. Biochemistry 2006, 45, 2556-2560.
[2] Quintana M.; Prato M. Chem. Commun., 2009, 6005?6007 — 6005.
[3] Yusof, A.M.; Buang, N.A.; Yean, L.S.; Ibrahim, M.L. AIP Conference Proceedings. 2009, 1136,
390-394.
Acknowledgment. To CONACYT, through the scholarship 391048.
Giant Vesicles as a Cellular Model in the Internalization of Carbon
Nanotubes
Poster Presentation 24
Veronica Pérez Luna1 *, Carlos Moreno Aguilar1 , José Luis Arauz-Lara1 , Said Aranda-Espinoza1 and
Mildred Quintana1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
Carbon nanotubes (CNTs) implementation as nanovectors in controlled drug delivery is an idea gaining
strength, ought to the ability of the CNTs to penetrate the membrane of mammalian cells without
causing any damage. The CNTs internalization is a controversial topic because it has been reported to
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occur by two different mechanisms: 1) An energy dependent mechanism, where CNTs enter the cell via
endocytosis and 2) A simple diffusion process, similar to nanoneedles. Nevertheless, very little is known
about the physical and chemical interactions leading these two processes. We have taken the task to
analyze these interactions using giant unilamelar vesicles (GUVs) as a representative model of the basic
structure of the cell. We study the change in the mechanical properties of the membrane, in the presence
and absence of CNTs, determining the effect that this nanoestructuras have in the membrane. The
technique implemented here is the electrodeformation, which allows us to measure the bending constant
of the membranes in the different conditions of interest.
Complexity of the structure formed in magnetorheological fluids
under an oscillating magnetic field
Poster Presentation 25
Rosario E. Moctezuma1 *, José Luis Arauz-Lara1 and F. Donado2
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
2 Instituto de Ciencias Básicas e Ingeniera de la Universidad Autónoma del Estado de Hidalgo-AAMF,
Pachuca 42184, Pachuca, México
*Corresponding author: [email protected]
1 Instituto
We present the analysis of the complexity of the structure formed by magnetic particles in a dilute
magnetorheological fluid. We analyzed the multifractal characteristics of the whole structure through
the singularity spectrum f(?), and the generalized dimension D(q). We vary different parameters such
as: particle concentration, magnetic field intensities and liquid viscosity. We also obtained the fractal
dimension Dg, calculated from the radius of gyration of the chains, to describe the internal distribution of
the particles. We present a thermodynamic interpretation of the multifractal analysis, and based on this,
we discussed the characteristics of the structure formed by the particles and its relation with previous
studies of the average chain length. We found that combining the multifractal analysis for the whole
structure and the analysis through the radius of gyration for the distribution of the particles within each
structure, we obtain a complete description of the complex structures formed by the particles.
Ultrasoft systems and the hard-sphere dynamic universality class.
Poster Presentation 26
Sol Marı́a Hernández-Hernández1 *, Martı́n Chávez-Páez1 and Magdaleno Medina Noyola1
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected],uaslp.mx
1 Instituto
The structural equivalence established by Andersen, Weeks, and Chandler, between soft-sphere fluids
and the hard-sphere liquid, complemented by its recently-proposed dynamic extension, define the class
of soft-sphere systems whose dynamic parameters, such as the alpha-relaxation time and the long-time
self-diffusion coefficient, depend on the density n, the temperature T , and the softness (characterized by
some softness parameter nu) only through an effective hard-sphere volume fraction ϕHS = ϕHS (n, T, ν).
This so-called hard-sphere dynamic universality class was discussed in the context of systems formed by
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particles interacting with short- and long-ranged, but purely repulsive pair potentials u(r) that diverge
at r = 0. Such analysis did not involve fluid systems formed by ultrasoft particles that allow full overlap
between particles, and are thus the conceptual opposite of the hard sphere liquid. An open question is
then to what extent liquids of ultrasoft particles might or might not exhibit the structural and dynamic
behavior characteristic of the hard-sphere dynamic universality class. In this work we show that at
least for a simple repulsive ultrasoft interaction model, namely, the Gaussian core model, its dynamic
equivalence with the hard-sphere liquid can be stablished for a wide range of state points in density and
temperature. Such conclusion is based on the analysis of theoretical results and exact dynamic simulation
data to identify the equivalent hard sphere systems.
Study of the interaction of nanostructured surfaces with cells using
microfluidic systems
Poster Presentation 27
Leonardo Nuñez-Magos1 *, A. Ramı́rez-Saı́to1 , Said Aranda-Espinoza1 , Mildred Quintana1 and José
Luis Arauz-Lara1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
Very little is known about the recognition, trajectory and the mechanism that regulates the internalization of nano-structured systems in cells and how cell-substrate interface influences the cell development.
Knowledge about cellular responses to microenvironments would improve the understanding of cell reactions to physical and chemical changes. This understanding could be used to develop artificial organs,
biomaterials and nano-drugs delivering systems. In this work, we designed and developed micro-channel
chips for microfluidic systems with dimensions comparable to those of an average cell size. The chips
are made in PDMS, printing photosensitive resin by photolithography. Additionally, the manufacture of
simpler flowing-cells in glass is presented. These chips will be used to study the interaction of lipidica
giant vesicles with nanostructured surfaces.
Comparison between HNC/MSA theory for the electric double layer
spherical and URMGC theory: the reversal and amplification of
charge
Poster Presentation 28
Evelyn Angélica Barrios-Contreras1 *, Enrique González-Tovar1 and Guillermo Iván Garcı́a-Guerrero.2
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
1 Departament of Materials Science and Engineering, Northwestern University, Evanston, USA.
*Corresponding author: [email protected]
The electrical double layer is present in colloidal systems as a distribution of ions around a charged colloid.
Under certain conditions, the phenomena of charge reversal and surface charge amplification may occur.
In the former, the net charge of a colloid plus their surrounding ions is locally inverted. In the latter, the
net colloidal charge enclosed up to a certain distance is larger than the original bare charge of the colloid.
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In this work, we present a theoretical study based on the Ornstein-Zernike equation complemented with
the HNC/MSA closures in order to study the above phenomena. In particular, the double layer of sizeand valence-asymmetric electrolytes in the primitive model is compared to that obtained via a mean-field
theory involving size-asymmetric semi-punctual ions.
Importance of the GTPase Gpn3 in the nuclear accumulation of
RNA polymerase II in breast cells with increasing degrees of malignancy.
Poster Presentation 29
Bárbara Lara Chacón1 *, Mónica R. Calera1 and Roberto Sánchez Olea2
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
1 Departament of Materials Science and Engineering, Northwestern University, Evanston, USA.
*Corresponding author: [email protected]
1 Instituto
Gpn3 is a GTPase that, along with Gpn1 and Gpn2, belongs to the GPN protein family. These three
proteins are essential for life, their sequence is highly conserved in all eukaryotes, and they all contain a
conserved sequence of glycine (G)-proline (P)-asparagine (N) that originates their name. Gpn3 interacts
with RNA polymerase II (RNAPII), the enzyme that transcribes all protein coding genes, as well as many
other small nuclear RNA genes. In our laboratory we demonstrated previously that Gpn3 is necessary
for the nuclear localization of RNAPII in the non-tumorogenic MCF-12A breast cells. Interestingly, in
four different breast tumorogenic cell lines Gpn3 is not longer necessary for Rpb1 nuclear accumulation.
This may imply that the tumorogenic cells have developed a molecular mechanism independent of Gpn3
for the RNAPII nuclear accumulation. In this work, we determined if there is a relationship between the
degree of cell transformation and the importance of Gpn3 for RNAPII nuclear targeting. To this end,
we employed progressively more malignant derivatives of the originally non-tumorigenic MCF10 breast
cells. These derivatives include the MCF10AneoT, MCF10AT1, MCF10ATK1.cl2, MCF10CA1d.cl1 and
MCF10CA1a.cl1 cells. We suppressed Gpn3 expression employing a specific shRNA, and evaluated the
subcellular localization of Rpb1, the largest subunit of RNAPII. Gpn3 silencing was verified by Western
blot, and the subcellular localization of Rpb1 was analyzed by immunofluorescence. We will present and
discuss the results of our investigation at the meeting.
This work was supported by Fondo Sectorial de Investigacin en Salud y Seguridad Social-Conacyt grant
number 180825, by Fondo de Apoyo a la Investigacin-UASLP grant number C13-FAI-03-39.39 to RSO,
and C14-FAI-04-15.15 to MRC.
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Effective charges and virial pressure of concentrated macroion solutions
Poster Presentation 30
G. I. Guerrero-Garcia1 * and M. Olvera de la Cruz2
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
1 Departament of Materials Science and Engineering, Northwestern University, Evanston, USA.
21 Northwestern University, United States
*Corresponding author: [email protected]
1 Instituto
Structural and thermodynamic properties of macroions in solution are signicantly affected by distortions
of the ionic double layers at signicant macroion volume fractions. This many-body e ffect limits theoretical descriptions based on the classical two-body Derjaguin-Landau-Verwey-Overbeek (DLVO) approach
to dilute suspensions. We introduce a method to obtain eff ective point charges for macroions from cell
theory, thereby naturally accounting for high volume fractions in both salt-free and added-salt conditions. By simulating systems containing macroions interacting via hard-core plus screened-Coulomb pair
potentials using such effective point charges, we reproduce macroion-macroion spatial correlations and
the virial pressure of primitive-model systems in which macroions and monovalent microions interact via
Coulombic potentials at the same level. An analytical expression for the eff ective pair potential for
smaller macroion charges is provided, thereby extending the accuracy of DLVO theory far beyond the
dilute regime.
Numerical simulations of electrified oil/water interfaces: a coarsegrained approach.
Poster Presentation 31
G. I. Guerrero-Garcia1 * and M. Olvera de la Cruz2
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
1 Departament of Materials Science and Engineering, Northwestern University, Evanston, USA.
21 Northwestern University, United States
*Corresponding author: [email protected]
1 Instituto
The ionic cloud near the interface between two immiscible electrolytes in the presence of an applied
electric field has been a topic of intense research in recent years. Technological applications relying
on the microscopic ionic structure of these electrified liquid interfaces include amperometric sensors,
electro-assisted solvent extraction, label-free detection of biomolecules, trap-release mechanisms, and
pharmacokinetics of drugs. In this poster, we would like to present simulation results of a coarsegrained model that goes beyond classical mean field descriptions including polarization effects, due the
the existence of regions with different dielectric properties, ion correlations, and ionic excluded volume
effects. This approach also allows a microscopic description that cannot be performed by more detailed
molecular explicit solvent simulations due to the astronomic number of particles required under typical
experimental conditions.
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Folding of the apolipoprotein A1 driven by the salt concentration
as a possible mechanism to improve cholesterol trapping
Poster Presentation 32
M. A. Balderas Altamirano1 *, A. Gama Goicochea1 and E. Pérez2
1 UAM, México.
2 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
The folding of the cholesterol trapping apolipoprotein A1 in aqueous solution at increasing ionic
strength is studied using atomically detailed molecular dynamics simulations. We calculate various
structural properties to characterize the conformation of the protein, such as the radius of gyration,
the radial distribution function and the end to end distance. Additionally we report information using
tools specifically tailored for the characterization of proteins, such as the mean smallest distance matrix
and the Ramachandran plot. We find that two qualitatively different configurations of this protein are
preferred: one where the protein extended, and one where it forms loops or closed structures. It is argued
that the latter promote the association of the protein with cholesterol and other fatty acids.
Correlation between two particles in a confined system
Poster Presentation 33
Manuel de Jesús Sánchez Miranda1 * and José Luis Arauz Lara1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
We address the problem of Hydrodynamic Interactions between two particles under confinement
via video-microscopy technique. Three-dimensional trajectories of two confined particles in a drop of
methanol/water/SDS of micron sized are followed by a long enough time, such that, the particles have
enough time to sweep all the volume of the sphere that contain them. The Hydrodynamic Interactions
between the particles inside the droplet and the walls produce a dependence on the droplet size in the
diffusion of the particles at short times. We split the diffusion of the particles into two components,
radial and tangential. In this work we show the behavior of the diffusion coefficients of two particles in
a spherical cell. The colloidal particles used are two latex particles of 1 micron in diameter.
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Transport cycle importance nucleus cytoplasmic Gpn1 GTPase in
the sub cellular localization of RPAP2 and RNAPII
Poster Presentation 34
Esmeralda Nolasea Cruz1 *, Mayra Martı́nez Snchez1 , Monica R. Calera Medina1 and Roberto Sánchez
Olea 1
1 Instituto de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
Gpn1 is a GTPase that is physically associated with RNA polymerase II and is essential for nuclear
accumulation of this enzyme. Gpn1 is normally located in the cytoplasm but accumulates in the nucleus
when mutated nuclear export sequence [3]. In this study the nuclear export of Gpn1 was inactivated
through mutation of hydrophobic amino acids 3 and 4 of the nuclear export signal to alanine (V302A
/ L304A) to evaluate the functionality of the NES, besides measuring the interaction between Gpn1
and RPAP2, a. NES mutation showed an effect on the localization of the RPBI, the largest subunit of
RNA polymerase II (RNAPII), and RPAP2 a cytoplasmic protein that binds RNAPII. These findings we
can corroborate the hypothesis that the nucleocytoplasmic transport cycle Gpn1 is required for nuclear
accumulation of RNA polymerase II and specifically to nuclear export sequence present in Gpn1 is
essential for export RPAP2 to the cytoplasm.
Brownian Repulsive and Attractive Correspondence in the Hardsphere system
Poster Presentation 35
1 Instituto
Leticia López Flores1 *, Martı́n Chávez Páez1 and Magdaleno Medina Noyola1
de Fı́sica ‘Manuel Sandoval Vallarta’, Universidad Autónoma de San Luis Potosı́, Álvaro
Obregón 64, 78000 San Luis Potosı́, SLP, México.
*Corresponding author: [email protected]
In this work we investigate the structure and dynamics equivalence between model systems with
repulsive and attractive interactions and hard-sphere fluids. For this we perform systematic Brownian
dynamics simulation experiments on fluids whose attractive particle-particle interaction is given by the
the well stablished Lennard-Jones potential and compare the simulated dynamics and long-time dynamic
properties (mean squared displacement, intermediate scattering function, long-time diffusion coefficient,
and ?-relaxation time) for a wide range of conditions with the corresponding properties of hard-sphere
liquids. We find that repulsive potential systems and the Lennard-Jones liquids exhibit the same dynamics
equivalence known to exists between soft-sphere liquids with similar static structure.
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Organization
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7.2
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7.3
Organizing Institutions
Universidad Nacional Autónoma de México
Universidad de Guanajuato
Universidad Autónoma de San Luis Potosı́
Mesoamerican Center for Theoretical Physics
American Physical Society
Organizing Committee
Helim Aranda Espinoza
Isaac Pérez Catillo
Ramón Castañeda Priego
Said Aranda Espinoza
Magdaleno Medina Noyola
Pedro E. Ramı́rez González
Bernardo Yañez
Leticia López Flores
Sponsors
This workshop is sponsored by mexican sources: Consejo Nacional de Ciencia y Tecnologa, Universidad
Autnoma de San Luis Potos, Universidad de Guanajuato y Universidad Nacional Autnoma de Mxico,
with complementary support from the Mesoamerican Center for Theoretical Physics and the American
Physical Society.
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.. 7.3. Sponsors
.. 7.3. Sponsors
SPONSORS
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‘1st International Workshop
on Matter Out of
Equilibrium’
ISBN 978-80-85955-35-4
9 788085 955354
Leticia López Flores • José Manuel Olais Govea
http://www.ifisica.uaslp.mx/-medina/indexp1.html