Indian Journal of Pure & Applied Physics
Vol. 52, March 2014, pp. 155-161
Solvation effect and thermochemical study of some L-arginine salts in polar
solvent using ultrasonic velocity
E Jasmine Vasantha Rani1, *K Kannagi 2, R Padmavathy1 & N Radha1
1
2
Seethalakshmi Ramaswami College (Autonomous), Triuchirappalli 620 002, India
Bharathidasan university constituent College, Lalgudi, Triuchirappalli 621 601, India
*E-mail: [email protected]
Received 14 August 2013; revised 27 December 2013; accepted 2 January 2014
The ultrasonic velocity in non-aqueous electrolytic solutions has been measured which gives valuable information
regarding the nature and strength of various interactions and the formation of hydrogen bonding. It also shows the behaviour
of hydrogen such as molecular association and dissociation. Solvation is the association of solvent molecules with the solute
ions in a solution. In the present study, the fundamental parameters of three amino acids namely, L-arginine, L-arginine
mono hydrochloride and L-arginine methyl ester dihydrocholoride in non-aqueous solution as a function of composition in
the temperature range 278.15-328.15 K have been measured. Using these experimental value solvation number and the
acoustical parameters such as adiabatic compressibility, apparent molal volume and apparent molal compressibility have
been calculated for all the three systems. These results are analysed and eventually emphasizing the possible molecular
interactions in terms of structure-making and structure-breaking effects of the above amino acids in the solvent.
Keywords: Solvation number, Adiabatic compressibility, Ultrasonic velocity, Polar solvent, Thermochemical study
1 Introduction
Amino acids and peptides are the fundamental
structural units of proteins. Due to the complex nature
of proteins, direct study is found to be difficult.
Therefore, the useful approach is to study simpler
model compounds, such as amino acids which are the
building blocks of proteins. During the last two
decades, the hydration of proteins through volumetric
and ultrasonic measurements have been investigated.
Most of the studies on amino acids have been carried
out in pure and mixed aqueous solution. The
investigation of volumetric and thermodynamic
properties of amino acids and peptides in aqueous
solutions has been the area of interest of a number of
researchers1.
Proteins are linear, large complex molecules,
heterogeneous polymers genetically mandated with 20
different building blocks of all living organisms,
whose residues linked by covalent peptide bonds
(−Ȧ−NH−) into the polypeptide chain. Due to
physiological conditions, the two terminals of amino
acids are charged both with positive charge (amino
group NH3+) and negative charge (carboxyl group,
COO-). Therefore, the molecules have the properties2
of the Zwitterion. Zwitterionic form of amino acids
can be preferentially stabilized by increased proton
affinity. Thus, argninie has relatively high proton
affinity due to its guanidine side chain.
The effect of electrolytes on the stability of proteins
and polypeptided has already been studied in aqueous
solution3, but no report has been found in the presence
of non-aqueous solution. Hence, the physico chemical
properties of some L-arginine derivatives (L-arginine,
L-arginine mono hydrochloride, L-arginine methyl
ester dihydrochloride) in non-aqueous solution from
low temperature to high temperature with different
molalities, have been studied.
L-arginine is an essential amino acid helps to
synthesize nitric oxide, which plays a critical role in
blood circulation throughout the body4. L-arginine
stimulates HGH (Human Growth Hormone)
production by blocking the secretion of some natural
inhibits, several clinical studies have shown that Larginine can increase natural HGH production by over
300%. It lowers the blood pressure, helps to regulate
healthy immune system, heal and repair soft tissues.
L-arginine HCl is commonly used in cell culture
media and drug development. L-arginine methyl ester
dihydrochloride increases nitric oxide production and
it also acts as a vasodilator allowing more blood to
flow muscle tissue.
Due to the biological influence and wide range of
medicinal applications, L-arginine derivatives are
chosen as samples. To improve our understanding of
the ionic salt effect on the non-aqueous amino acid
solutions, the present study focused on interactions
INDIAN J PURE & APPL PHYS, VOL 52, MARCH 2014
156
between three aminoacids (L-arginine, L-arginine
hydrochloride,
L-arginine
methyl
ester
dihydrochloride) with non-aqueous solutions via the
basic parameters Fig. 1(a-c) of Table 1. Using these
data,
the
solvation
effect,
the
adiabatic
compressibility, apparent molal volume and apparent
molal compressibility have been evaluated and
discussed in terms of ion-solvent, ion-ion interactions
occurring between the solute and solvent.
2 Experimental Details
Analytical Reagent (AR) grade with minimum
assay of 99.9% of L-arginine, L-arginine mono
L-arginine
methyl
ester
hydrochloride,
dihydrochloride were obtained from Southern India
Scientific Company (SISCOM), Mumbai. Fresh
conductivity water has been used for preparing nonaqueous solution. The required amount of amino acids
for a given molality was dissolved and similar
procedure has been adopted for different molalities of
all amino acids. The solution of amino acids in the
concentrations range 0.01-0.1 mol.d.m−3 with an
accuracy of 0.0002 g is maintained.
The density of the solution is determined using
25 ml specific gravity bottle, using the thermostatic
bath with a compressor unit. A Canon Fenske
Viscomeer (10 ml) was used for the viscosity
measurements variable bath interferometer having a
frequency of 2 MHz (Mittal Enterprises, New Delhi,
Model: F-8) with overall accuracy of 0.1% was used
for velocity measurements. A digital electronically
operated constant temperature bath was used to
circulate water through the double-walled measuring
(a)
(b)
(c)
Fig. 1 — Variation of adiabatic compressibility (ȕ) with molality
of some L-arginine derivatives in non-aqueous solution at 278.15
to 328.15 K.
Table 1 — Values of adiabatic compressibility (ȕ) of L-arginine, L-arginine mono HCl and L-arginine methyl ester
dihydrocholoride in non-aqueous solution
278.15 K
288.15 K
298.15 K
308.15 K
318.15 K
328.15 K
0.001
0.005
0.01
0.025
0.05
0.001
0.005
0.01
0.05
0.1
0.001
0.01
0.05
0.1
0.2
3.18109E-11
3.27905E-11
3.22146E-11
3.24749E-11
3.16351E-11
3.19644E-11
3.12531E-11
3.27162E-11
3.09933E-11
3.20399E-11
3.32228E-11
3.32582E-11
3.30724E-11
3.34438E-11
3.27232E-11
3.404E-11
3.365E-11
3.33E-11
3.425E-11
3.341E-11
3.434E-11
3.366E-11
3.452E-11
3.382E-11
3.383E-11
3.326E-11
3.299E-11
3.326E-11
3.329E-11
3.303E-11
3.32E-11
3.43E-11
3.33E-11
3.37E-11
3.47E-11
3.41E-11
3.39E-11
3.51E-11
3.47E-11
3.44E-11
3.55E-11
3.47E-11
3.55E-11
3.53E-11
3.57E-11
3.637E-11
3.692E-11
3.52E-11
3.533E-11
3.579E-11
3.372E-11
3.481E-11
3.463E-11
3.425E-11
3.472E-11
3.498E-11
3.583E-11
3.501E-11
3.532E-11
3.57E-11
3.758E-11
3.634E-11
3.614E-11
3.657E-11
3.79E-11
3.442E-11
3.54E-11
3.639E-11
3.663E-11
3.589E-11
3.622E-11
3.63E-11
3.544E-11
3.592E-11
3.516E-11
3.89858E-11
3.73254E-11
3.74995E-11
3.73213E-11
3.75867E-11
3.71927E-11
3.75657E-11
3.66023E-11
3.76735E-11
3.66275E-11
3.75708E-11
3.73592E-11
3.76666E-11
3.69403E-11
3.71381E-11
L-arginine
Methyl Ester
diHCL
L-arginine
Mono HCL
L-arginine
Molality (m)
RANI et al.: SOLVATION EFFECT AND THERMOCHEMICAL STUDY OF L-ARGININE
cell of steel containing the experimental solution at
the desired temperature.
3 Results and Discussion
3.1 Adiabatic compressibility
Adiabatic compressibility (β) is calculated by the
function of:
ª 1 º
β = « 2 » Cm2 /dyne
¬u ρ ¼
where u is the ultrasonic velocity in cm/s, ρ is the
density of the solution in g/cc.
In the present paper, adiabatic compressibility of
L-arginine solution gradually increases, and a dip is
existing in 0.01 molality for all the temperatures. It
can be explained by the predominance of the
associated molecules5. This behaviour shows that
there may be association taking place between the
molecules in the solution. This variation represents
the existence of strong ionic bonding the solvent and
solute molecules due to the Zwitterions as a result of
electrostatic forces.
In the case of L-arginine mono hydrochloride
system, the adiabatic compressibility values rise and
fall which shows the pre-deminance of dissociation of
molecules occurring in the solution. This variation
represents the weak hydrogen bonding arising as a
result of hydrophobic interactions which occur
between the solute and solvent molecules. This weak
bond is responsible for the existence of weak
interactions in the solution of L-arginine mono
hydrochloride.
L-arginine methyl ester dihydrochloride shows a
fluctuating nature. The rise and fall of such system
supports that there is a weak solute-solvent
interaction6. This variations support a strong
dissociation taking place between the molecules of the
solution.
3.2 Apparent molal compressibility
Apparent molal compressibility (ψk) is calculated
by:
ψk =
ªβ M º
1000
( ρ0 β − ρβ0 ) + « o »
mρ 0
¬ ρ0 ¼
ȡ0 is the density of the solvent, ȕ0 the compressibility
of the solvent, ȡ the density of the solution, ȕ the
compressibility of the solution, M the molecular mass
157
of the solute and M is molecular concentration of the
solute.
Apparent molal compressibility of an amount of
solution contains one mole of the solute minus
compressibility of the solvent. The increase in
apparent molal compressibility may be attributed to
the fact that the charge density of the ions remains
practically constant, inspite of the change in ionic size
and relative surface area7. As the concentration of the
solution increases and larger portion of the solvent
molecules is electrostricted, the amount of bulk
solvent decreases causing the apparent molal
compressibility to decrease8.
The apparent molal compressibility values of
L-arginine shows the positive values at 1278.15 K
except 0.01m whereas negative values are observed
for other temperatures as shown in Fig. 2(a). The
increasing values of ϕk of L-arginine solutions reveals
the strengthening of ion-solvent interaction in the
solution. The negative values of ϕv and ϕk indicate the
ionic and hydrophilic interactions occurring in the Larginine solution. L-arginine monohydrochloride
system shows the positive values of ϕk around the
room temperature with respect to concentration while
the negative values are noted for other temperatures
as shown in Fig. 2(b).
In L-arginine methyl ester dihydrochloride, the
values are shown to be negative at higher temperature.
It is found to be positive at low temperature and
shown in Fig. 2(c) of Table 2.
The above results are obtained due to:
The negative values of φk support weak-solute
solvent interaction.The positive values of φk suggest
that there is a strong ion-solvent interaction.
Therefore, the apparent molal volume and
compressibility of solutes have proven to be very
useful tools in elucidating the structural interactions
occurring in the solution9.
3.3 Apparent molal volume
The following function is used to calculate the
apparent molal volume :
φv =
M ml
1000
( ρ0 − ρ ) + 1
c1 ρ0
ρ0 mo l
C1 is the molal concentration, M1 the molecular
weight of the solute, ȡ the density of the solution and
ȡ0 is the density of the solvent.
The concentration depends on the apparent molal
volumes of electrolytes which can be used to study
ion-ion interaction. Favre and Valson10 assumed that
INDIAN J PURE & APPL PHYS, VOL 52, MARCH 2014
158
(a)
(b)
(c)
Fig. 2 — Variation of apparent molal compressibility
(ml/mol.cm2/dyne) with molality of some L-arginine derivatives in
non-aqueous solution at 278.15 to 328.15 K
the change in volume on adding a salt to solvent was
the resultant of two opposing effects.
(1) Contraction in volume due to the absorption of
solvent on the dissolved salt, (2) The ability of the
solute to cause electrostriction.
Electrostriction is a volume reducing process,
which involves polarisation and attraction of solvent
molecules around the ionic species11,12. In the present
study, it is found that apparent molal volume shows
noticeable changes at low concentrations in both
amino acid solutions. But, in L-arginine, positive
values are noted for higher temperatures except at
278.15 K. The negative values are observed for
278.15 K and 278.15 K only at lower concentration in
Fig. 3(a).
The decrease in ϕv up to 0.01m takes place at all
temperatures reveals the strong ion-ion interaction
occurring in L-arginine solution. L-arginine
monohydrochloride exhibits the positive ϕv values at
278.15 K and higher temperatures. Around the room
temperature, some of the negative values are observed
at low concentrations. The ϕv values at 278.15 K and
278.15 K increase at low concentrations that indicate
the weak solute-solvent interaction occurring in the
solution. The higher values of ϕv support weak-solute
solvent interaction and lower values support the
strong ion-ion interaction as shown in Fig. 3(b).
The variation of φv is noticeable only at lower
concentration for L-arginine methyl ester dihydrochloride. φv remains constant at higher molalities. At
higher concentration, the φv is found to be positive at
all temperatures and shown in Fig. 3(c) of Table 3.
Table 2 — Values of apparent molal compressibility of L-arginine, L-arginine mono HCl and L-arginine methyl ester
dihydrocholoride in non-aqueous solution
278.15 K
288.15 K
298.15 K
308.15 K
318.15 K
328.15 K
0.001
0.005
0.01
0.025
0.05
0.001
0.005
0.01
0.05
0.1
0.001
0.01
0.05
0.1
0.2
−7.6256E-07
7.34043E-08
−3.2737E-08
1.4277E-09
−1.6179E-08
−5.5118E-07
−2.7484E-07
3.24182E-08
−2.9227E-08
−6.628E−10
8.7497E-07
9.3076E-08
1.99043E-08
1.76295E-08
7.43751E-09
7.105E-07
5.669E-08
−1.62E-08
3.945E-08
3.004E-09
9.759E-07
4.564E-08
1.244E-07
1.35E-08
9.125E-09
−1.56E-07
−4.24E-08
2.423E-09
3.909E-09
3.549E-09
−1.03E-06
4.2E-08
−9.03E-08
−1.86E-08
1.75E-08
−6.32E-08
−4.92E-08
1.05E-07
1.81E-08
7.85E-09
1.5E-06
6.43E-08
3.68E-08
1.86E-08
1.49E-08
9.485E-07
3.185E-07
−4.6E-08
−9.35E-09
8.291E-09
−2.15E-06
−1.97E-07
−1.09E-07
−2.6E-08
−4.89E-09
−8.46E-07
2.246E-08
−9.64E-09
2.276E-09
7.05E-09
5.489E-07
−1.8E-07
−1.12E-07
−1.93E-08
2.302E-08
−2.93E-06
−3.79E-07
−7.6E-08
−5.2E-09
−8.59E-09
−1.1E-06
−9.46E-08
−3.26E-08
−7.41E-09
−5.27E-09
8.6423E-07
−2.07153E-07
−8.34098E-08
−3.71207E-08
−8.08431E-09
−1.13999E-06
−1.42083E-07
−1.75999E-07
−7.31057E-09
−1.29247E-08
−9.40424E-07
−1.00896E-07
−8.08818E-09
−8.45754E-09
1.51187E-10
L-arginine
Methyl Ester
DiHCL
L-arginine
Mono HCL
L-arginine
Molality(m)
RANI et al.: SOLVATION EFFECT AND THERMOCHEMICAL STUDY OF L-ARGININE
159
3.4. Solvation number
(a)
The following function is used to calculate the
solvation number:
§ ns · ª
β º
¸ «1 − »
© ni ¹ ¬ β 0 ¼
ηh = ¨
(b)
(c)
Fig. 3 — Variation of apparent molal volume (ml/mol) with
molality of some L-Arginine derivatives in non-aqueous solution
at 278.15 to 328.15 K.
ηh is the primary solvation number, ni the moles of
ions, ns the moles of solvent, ȕ the adiabatic
compressibility of solution and ȕo adiabatic
compressibility of solvent.
Solvation is the attraction and association of
molecules of the solvent with molecules or ion of the
solute13. The solvation approach is used to interpret
ion-solvent interaction. Negative solvation number
with molality were reported by researchers. With the
increase in concentration, the solvation number
decreases if there is not enough solvent for all ions or
if ion-pairing occurs13,14. In low molality solutions,
there is a basic structural change in the first
co-ordination spheres occurred in a set in relation to
their solvation energies15. The solvation number of an
ion depends on the solvent.
Potential energy of the ion and solvent molecule
will be higher than that of kinetic energy of the ion
molecules at low temperatures. Positive solvation
number of solutions suggests that compressibility of
the solution at high temperature and low molalities
will be less than that of the solvent. The solvation
number can be defined as number of solvent
molecules per ion, which remains attached to a given
Table 3 — Values of apparent molal Volume of L-arginine, L-arginine mono HCl and L-arginine methyl ester
dihydrocholoride in non-aqueous solution
L-arginine
Mono HCL
L-arginine
Methyl Ester
DiHCL
0.001
0.005
0.01
0.025
0.05
0.001
0.005
0.01
0.05
0.1
0.001
0.01
0.05
0.1
0.2
L-arginine
Molality(m)
278.15K
Apparent Molal Volume (ml/mol)
288.15K
298.15K
308.15K
318.15K
328.15K
159.0200581
80.85063439
−67.5455504
53.24107641
102.3511002
1275.530023
206.4125418
169.2155088
158.9574202
137.8811319
793.8386698
123.8109091
191.5511419
195.7287578
184.4953061
−34.87289
63.120003
−104.3276
34.270499
91.685128
−2519.623
−366.7509
−64.8301
121.9435
127.65236
502.16474
168.78188
177.68189
158.03663
174.47753
249.59019
−325.3054
−174.5997
102.48548
128.87993
1222.0166
−44.36835
58.148848
138.80029
134.51694
−3557.763
−174.493
123.19558
159.25918
159.65072
2571.331274
204.7810443
126.209782
162.030417
203.0537074
2170.642122
519.3958991
313.7603079
172.1732029
153.1438192
-3678.376578
74.78860594
155.7928441
179.0611113
178.209253
89.4251
32.48268
−4.509327
82.86657
132.6896
−833.0203
−12.7783
48.05363
128.8298
136.3196
−1054.197
62.15322
157.7067
168.0404
175.5926
3548.0362
799.16596
92.947746
127.56691
135.47451
184.73663
146.16367
118.01778
151.24875
155.51595
−3109.617
32.489173
127.4898
165.36693
187.01561
INDIAN J PURE & APPL PHYS, VOL 52, MARCH 2014
160
ion, long enough to experience its translational
movement when solution is formed16.
Negative values of solvation number emphasize the
solution is more compressible than the solvent. Many
researchers in literature17,18 report the negative
solvation number. Zero value of solvation number
only indicates that no change occurs in the
compressibility of the solvent when the solution is
formed19. Positive solvation number of solutions
suggests that compressibility of the solution at high
temperature and at all molalities will be less than that
of the solvent20,21.
The compressibility measurements are used for
computing the solvation number for the systems
studied. It is observed that L-arginine solution exhibits
positive solvation number for the temperatures
278.15, 278.15 and 278.15 K almost for all molalities.
But, around the room temperature it shows negative
solvation number with respect to temperature not for
all molalities are shown in Fig. 4(a).
In the case of L-arginine monohydrochloride
system, positive values are observed at higher
temperatures also at 278.15 K except at 0.01 m. For
288.15 and 298.15 K, the system shows the negative
solvation number values,almost for all molalities are
shown in Fig. 4(b). The positive solvation number
indicates an appreciable solvation of solutes. The
negative values indicate solvation effect in L-arginine
monohydrochloride solution which is less than that of
L-arginine solution.
In L-arginine methyl ester dihydrochloride, the
solvation number is found to be negative at 278.15
(a)
(b)
(c)
Fig. 4 — Variation of solvation number (ƾ) with molality of some
L-Arginine derivatives in non-aqueous solution at 278.15 to
328.15 K.
Table 4 — Values of solvation number of L-arginine, L-arginine mono HCl and L-arginine methyl ester
dihydrocholoride in non-aqueous solution
L-arginine
Mono HCL
L-arginine
Methyl Ester
DiHCL
0.001
0.005
0.01
0.025
0.05
0.001
0.005
0.01
0.05
0.1
0.001
0.01
0.05
0.1
0.2
L-arginine
Molality (m)
278.15 K
288.15 K
455.0390143
−41.9351423
18.10956646
0.178433758
11.48704439
350.903348
166.7101014
−15.9282916
20.19646238
2.996861989
−503.032494
−52.7035129
−8.01931374
−6.53020005
−0.81994524
−412.7297
−31.64226
7.3909732
−22.17793
0.0344144
−616.1261
−33.62177
−73.41812
−5.42548
−2.774045
100.07696
27.793557
2.0156489
0.7798564
1.2686081
Solvation Number
298.15 K
591.4687
−23.3552
51.49183
12.21854
−7.345099
19.87955
27.8565
−58.72576
−7.759796
−1.794449
−876.9122
−35.49337
−17.7504
−7.20456
−4.897827
308.15 K
318.15 K
328.15 K
−451.7847
−159.2988
27.178982
7.6311308
−1.894771
1187.3732
101.61017
62.464211
17.154172
5.6473132
406.25428
−11.73554
7.7569178
1.9548023
−0.203656
−287.9183
89.827992
56.516609
12.273943
−9.661078
1587.3941
201.52617
41.676797
5.4750124
7.1333206
519.92336
47.06598
19.675614
6.9739031
5.7489738
−397.2711599
111.6795795
45.82087254
22.43003689
8.159741166
634.7710487
84.01555201
97.45641544
7.160771072
9.600820341
417.1490546
53.894506
7.240162556
7.800321509
3.331069114
RANI et al.: SOLVATION EFFECT AND THERMOCHEMICAL STUDY OF L-ARGININE
and 298.15 K. At 288.15, 318.15 and 328.15 K, the
solvation number is observed as positive and shown
in Fig. 4 (c) of Table 4.
4 Conclusions
L-arginine, the thermodynamic results support the
occurrence of hydropholic interactions between the
Zwitterionic centre of L-arginine and carbonyl group
of solvent. The acoustic study shows that there is an
association
between
the
molecules.
The
thermochemical parameters such as apparent molal
volume and apparent molal compressibility values
suggest the nature of interactions is hydrophilic. The
salvation number analysis exhibits the effect of
salvation is higher.
L-arginined
mono hydrochloride from the
thermodynamic study, the charge solvated form of
L-arginine mono hydrochloride show the weak
interaction with solvent. Acoustic study of L-arginine
monohydrochloride shows weak hydrogen bonding.
Hydrophobic interaction is identified from thermo
chemical parameters.
In L-arginine methyl ester dihydrochloride solutions,
the analysis of acoustic and thermo chemical
parameters support the structure breaking nature of
the solute in the solvent. The detailed study of the
salvation number suggests that the weak solutesolvent interaction occurring in the solutions.
References
1 Chimankar O P, Ranjeeta Shriwas S & Tabhane V A,
J Chem Pharm, Res. 3(3) (2011) 587.
2 Thirumaran A & Inban P, Indian J of Pure & Appl Phys, 49
(2011) 451.
3 Palani R, Balakrishnan S & Arumugam G, Journal of Phys
Sci, 22(1) (2011) 131.
161
4 Kapotao J, Lemaire Maiitre P, Ohanissian G, J Am Chem
Soc, 126 (2004) 1836.
5 Banipal T S, Damanjit Kaura P K, Banipal Gagandeep
Singha, Indian J Chem, 43 (A) (2004) 1156.
6 Lark B S, Patyar P & Banipal T S, J. Chem Thermody, 39
(2007) 344.
7 Dhanalakshmi & Jasmine Vasantha Rani E, J Pure Appl
Ultrasonics, 21 (1999) 79.
8 Jahagirdhar D V & Shamkarwar A G, Indian J Pure & Appl
Phys, 38 (2000) 645.
9 Lemoff A S, Bush M F, O’Brien E R & William J T, J Phys
Chem A, 110 (2006) 8433.
10 Suhashini
Ernest,
Acoustic,
Thermodynamic,
Thermochemical, Spectroscopic and Electrochemical study
of Calcium Salts of some Organic Acids, PhD thesis,
Bharathidasan Universiy, 2009.
11 Kannappan A N & Palani R, Indian J Chem, 46A (2007) 54.
12 Jasmine Vasantha Rani E, Padmavathi R & Kannagi K,
Paper presented in the National Conference on EXFOVIS,
Nagarcoil 1st & 2nd September (2011) 34.
13 Jasmine Vasantha Rani E, Padmavathi R & Kannagi K,
Paper presented in the National Conference, NSA,
Bhandelkand University, Jhansi (UP), 17th-19th November
Acoustic Waves, (2011) 153.
14 Kannappan V & Jaya Shanthi R, Indian J of Pure & Appl
Phys, 43 (2005) 167.
15 Jayakumar, Karunanidhi N & Kannappan V, J Pure Appl
Ultrasonic, 20 (1998) 79.
16 Rajagopalan S & Sharma S J, J Pure Appl Ultrasonic, 27
(2005) 105.
17 Palaniappan L & Velusamy V, Indian J of Pure & Appl
Phys, 42 (2004) 593.
18 Jasmine Vasantha Rani E, Padmavathy R & Kannagi K,
Paper presented in the National Conference NSA,
Bhandelkand University, Jhansi (UP), 17th – 19th November
Appl Ultrasonics, (2011) 411.
19 Pooja Adroja P, Gami S P, Patel J P & Parsanai P H, J Ind
Chem Soc, 87 (2010) 655.
20 Michel Bruneau, Fundamentals of Acoustics, U.S.A ISTE
Ltd (2006) 16.
21 Ishwara Bhat & Shree Varaprasad N S, Indian J Pure & Appl
Phys, 42 (2004) 96.