Science in China Series B: Chemistry
© 2007
Science in China Press
Springer-Verlag
Changes of decay rates of radioactive
induced by mechanic motion
111
In and
32
P
HE YuJian1†, QI Fei2 & QI ShengChu3†
1
College of Chemistry and Chemical Engineering, Graduate University of Chinese Academy of Sciences, Beijing 100049, China;
No. 1, Gravenhurst Court, Gaithersburg, Md 20878, USA;
3
Department of Applied Chemistry, Peking University, Beijing 100871, China
2
The changes of decay rates of radionuclide 111In (electron capture) and 32P (β decay) induced by external mechanic motion are studied. The results indicate that, in the external circular rotation in clockwise
and anticlockwise centrifuge on Northern Hemisphere (radius 8 cm, 2000 r/min), the half life of 111In
compared with the referred (2.83 d) is decreased at 2.83% and increased at 1.77%, respectively; the half
life of 32P compared with the referred (14.29 d) is decreased at 3.78% and increased at 1.75%, respectively. When the clockwise and anticlockwise rotations increase to 4000 r/min, the half life of 111In is
decreased at 11.31% and increased at 6.36%, respectively; the half life of 32P is decreased at 10.08% and
increased at 4.34%, respectively. When the circular rotation is removed, the decay rates of 111In and 32P
return back to the referred, respectively. It is found that the external circular rotations in clockwise and
anticlockwise centrifuge selectively increased and decreased the decay rates of 111In and 32P, respectively, and the effects are strongly dependent on the strength of circular rotation. It is suggested that
these effects may be caused by the chiral interaction.
circular rotation, helical motion,
111
32
In, P, decay rate, chirality
As we know well, the radioactive decay was found to
follow a statistical law, the fundamental assumption is
that the probability for decay is constant, that is, it does
not depend on time or on the number of radioactive
atoms present, as well as the external physical and
chemical factors[1]. However, there are deep interests in
if the external factor can affect the radioactive decay
rate[2].
In 1947, Segre et al. first suggested that radioactive
decay rate of electron-capture (EC) depended on atomic
electron density around atomic nucleus[2], some external
factors, such as chemical form, may change the overlap
between electron and nucleus to affect EC decay rate[2].
The data published indicated that the EC half-time of
radioactive Be-7 in different metals was longer than the
referred (53.10 d); for example, it was 0.4% increase in
metal Au[2].
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Interestingly, Ohtsuki et al. recently reported that the
half-life of Be-7 encapsulated in C60 and Be-7 in Be
metal is found to be 52.68 and 53.12 d, respectively, and
there was a −0.83% difference[2]. This further indicated
that external factors were able to increase or decrease
the radioactive decay rate (half life). However, we do
not know how the change of radioactive decay rate depends on the external factor. Thus, it is a challenge if we
are able to find some controllable factors to selectively
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This paper was recommended for publication by Prof. Lemin Li, a member of the
Editorial Board of Science in China, Series B: Chemistry
Received August 4, 2006; accepted December 25, 2006
doi: 10.1007/s11426-007-0030-z
†
Corresponding author (email: [email protected] or [email protected])
This work was partially supported by the National Natural Science Foundation of
China (Grant No. 20571085), Grant of the President of the Chinese Academy of
Sciences (0521021T04), Chinese Academy of Sciences (KJCX3.SYW.N12),
2005/2006 USA Li’s Foundation Merit Prize grant, Ministry of Education of China
(0519061A90), and Graduate University of Chinese Academy of Sciences (GUCAS)
Grant (R 1003)
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Sci China Ser B-Chem | April 2007 | vol. 50 | no. 2 | 170-174
change the radioactive decay rates (half life). Interestingly, in this paper, it was indicated that the decay rates
of 111In (EC decay) and 32P (β decay) were able to be
changed by the external mechanic motion, and the effects were strongly dependent on the strength and direction of circular rotation.
spectively. The radioactivity was determined at an interval (e.g., 5 h), and each sample was determined at 4
times (10 s per time). Then, the sample was still kept in
rotation or natural condition, and repeated until the experiment was finished.
1 Materials and methods
These radioactive samples (111In and 32P) that had been
employed in the above rotation experiments were kept in
natural condition without artificial rotation to continue
radioactive activity measure to see if their half life return
back to normal.
1.1 Radioactive samples
111
InCl3, [γ-32P]-ATP and Na125I, were purchased from
PerkinElmer (MA, USA), nuclear purity was ≥ 99.9%.
EC half life of 111In is 2.83 d, and γ decay occurs at
0.245 (94%) and 0.171 MeV (90%). Half life of 32P β
decay is 14.29 d, and that of 125I (EC decay) is 59.60 d.
1.2 Production of external mechanic motions
The external circular rotations in clockwise (L-rotation)
and anticlockwise (R-rotation) centrifuge (facing to
viewer) at Washington DC/Beijing (on Northern Hemisphere) were employed to obtained two types of circular
mechanic rotations (radius 8 cm, 0－4000 r/min). The
rotation speed (r/min) was used to control the strength of
mechanic rotations.
1.3 Pretreatment of samples
To avoid and decrease experimental errors (e.g., the
evaporation effect), three of 10 μL fresh stock radioactive 111InCl3 or [γ-32P]-ATP solutions in 0.5 mL plastic
centrifugal tube were evaporated completely to dryness
with vacuum evaporator at low temperature (< 0.001 psi,
< −15℃, 4000 r/min, 2－3 h), then capped. During the
sample shipping and pretreatment (> 48 h), the radioactive impurity with short half life (if any) would be almost removed because of decay.
1.4 Radioactive activity measure
The BioScan/QC2000 (BioScan, Inc., Washington DC,
USA) was employed to determine decay rate under stable experimental conditions (e.g., temperature, pressure,
the sample position, etc.). In this paper, the relative
measure error 1/ n (n is the number of decay within
measure time) was < 0.1%.
After the radioactive samples were dried and capped,
their radioactivity was determined, and this time was as
the starting point (t = 0). Then, three samples were put in
clockwise rotation (L-rotation), in anticlockwise rotation
(R-rotation) and in natural condition (as a control), re-
1.5 Effect of the removal of external circular rotation on the radioactive decay rate
1.6 Radioactive background determination of experimental environment and instruments
During the experiment, the total radioactive activity of
the background was ~600 cpm. In comparison with the
average sample activity, it was <0.06%.
1.7 Calculation of radioactive half life
Two methods were used, (i) The A-t decay curve was
plotted by radioactivity A (unit: cpm) versus time, then
the exponential equation of decay, A = A0exp(−λt), was
obtained using the exponential trendline function of Microsoft Excel and the radioactive half life is T1/2 = ln2/λ,
where λ is the decay rate constant[1,2]; (ii) The exponential decay curves lnA-t were plotted by exponential lnA
of radioactive activity A (cpm) versus time, and the radioactive half life (or decay rate ) was obtained from the
slope of lnA-t curve.
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2 Results
2.1 Effect of external circular rotation on decay rates
(half life) of 111In and 32P
Figure 1 is the decay curves of 111In in L- or R-rotation
(2000 r/min). The lnA-t exponential decay curves in
Figure 1(b) are correspondingly obtained from A-t in
Figure 1(a). lnA-t curves are straight, which indicated
there was no impurity with short half life radionuclide,
and there was no chemical/nuclide evaporation problem,
etc. In Figures 1(a), (b), the middle curve is the control
decay curve of 111In in natural condition, and its half life
is 2.83 ± 0.03 d as the referred 2.83 d; the upper curve is
the decay curve of 111In in clockwise rotation, and its
half life is 2.75 ± 0.03 d, decreased 2.83% than the referred; the lower curve is the decay curve of 111In in anticlockwise rotation, and its half life is 2.88 ± 0.03 d,
HE YuJian et al. Sci China Ser B-Chem | April 2007 | vol. 50 | no. 2 | 170-174
171
Figure 1 Decay curves of A-t (a) and lnA-t (b) of 111In in different circular rotations.
111
increased 1.77% than the referred.
The results indicated that the external circular rotations selectively increased and decreased the EC decay
rate of 111In depending on the clockwise and anticlockwise rotation direction, respectively. There was also
similar effect of external circular rotation on EC decay
of 125I, and this indicated the effect is not special in 111In
only.
Figure 2 is the decay curves of 32P in L- or R-rotation
(2000 r/min). The middle curve is the control decay
curve of 32P in natural condition, and its half life is 14.29
± 0.03 d as the referred 14.29 d; the upper curve is the
decay curve of 32P in clockwise rotation, and its half life
is 13.75 ± 0.03 d, decreased 3.78% than the referred; the
lower curve is the decay curve of 32P in anticlockwise
rotation, and its half life is 14.54 ± 0.03 d, increased
1.75% than the referred.
The results also indicated the external circular rotations selectively increased and decreased the β decay
rate of 32P depending on the clockwise and anticlockwise rotation direction, respectively.
In and both strength and direction of the external circular rotation. When the clockwise rotation speed
changed from 2000 to 4000 r/min, the half life of 111In
changed to 2.51 ± 0.03 d with a decrease of 11.31%
(lower curve) than the control (2.83 d, middle curve);
when the anticlockwise rotation speed changed from
2000 to 4000 r/min, the half life of 111In changed to 3.01
± 0.03 d with an increase of 6.36% (upper curve) than
the control (2.83 d).
Figure 4 showed the relationship between the half life
of 32P and both strength and direction of the external
circular rotation. When the clockwise rotation speed
changed from 2000 to 4000 r/min, the half life of 32P
changed to 12.85±0.03 d with a decrease of 10.08%
(lower curve) than the control (14.29 d, middle curve);
when the anticlockwise rotation speed changed from
2000 to 4000 r/min, the half life of 32P changed to
14.91±0.03 d with an increase of 4.34% (upper curve)
than the control (14.29 d).
2.2 Effect of the strength and direction of external
circular rotation on the half life of 111In and 32P
In order to confirm the changes of radioactive decay rate
induced by external artificial circular rotations, the 111In
and 32P in Figures 1 and 2 that had been acted on by
Figure 3 showed the relationship between the half life of
2.3 Effect of the removal of external circular rotation on the radioactive decay rate
Figure 2 Decay curves of A-t (a) and lnA-t (b) of 32P in different circular rotations.
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HE YuJian et al. Sci China Ser B-Chem | April 2007 | vol. 50 | no. 2 | 170-174
Figure 3 The effect of the strength and direction of circular rotation on
the half life of 111In.
Figure 5 lnA-t decay curves of
artificial circular rotations.
Figure 4 The effect of the strength and direction of circular rotation on
the half life of 32P.
clockwise and anticlockwise circular rotations were kept
in natural condition to continue their natural decay, then
their decay curves were determined again to see whether
there were changes in the decay rate (half life) or not.
Interestingly, the results indicated that the decay rates of
111
In and 32P changed back to their natural ones after the
removal of external circular rotation, and the half lives
of 111In and 32P were still 2.83 and 14.29 d, respectively
(Figures 5(a) and (b)). This strongly demonstrated the
experimental facts in Figures 1 and 2 that the external
clockwise and anticlockwise circular rotation can influence the radioactive decay rate.
111
In (a) and
32
P (b) after removal of
molecules[3 8].
As we know well, the helix is chiral. The chirality of
helix is defined in physical terms: if a spinning rotation
(axial vector) is moving along its spin axis (polar vector),
parallel and anti-parallel combination of a polar and axial vector produces right- and left-handed helix, respectively[9,10]. In the solar system, the combination of the
Earth’s spinning and revolution (axial vector) and
Earth’s motion forward to Vega (polar vector) forms the
right-handed superhelical motion with daily, seasonal,
－
and annual periods in space-time (Figure 6)[3 5,11].
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3 Discussion
The data in this paper indicated that the clockwise and
anticlockwise circular rotations, depending on the speed,
increased and decreased the decay rates of 111In and 32P,
respectively. This is similar to the effect of the circular
rotation on the right-handed helical DNA and protein
Figure 6 Scheme of the Earth’s chiral right-handed helical motions. (a)
Earth’s spinning; (b) Earth’s revolution.
HE YuJian et al. Sci China Ser B-Chem | April 2007 | vol. 50 | no. 2 | 170-174
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The chiral interaction may be able to understand and
explain the changes of radioactive decay rates of 111In
and 32P selectively induced by the circular rotation. By
the helix definition, if relative to the Vega, the circular
rotation produced by the centrifuges at Washington DC/
Beijing on the Northern Hemisphere would make axial
vector, and the Earth’s moving along the Sun’s orbit
would make a natural polar vector (≠0). Thus, in fact,
the clockwise and anticlockwise circular rotations would
produce the artificial chiral left- and right-handed helical
motions, respectively[3,4]. An atom consists of protons,
neutrons, and electrons. The spinning particle (axial
vector) combing its moving along its axis (polar vector)
is chiral helical[9,10], and the chiral weak force affects the
way electrons orbit the nucleus and so causes atoms in
general to become right-handed[10]. Thus, similar to the
－
right-handed helical DNA and protein molecules[3 5],
chiral left- and right-handed helical motions (a chiral
gravitational field in physics[12]) may be able to make
the right-handed chiral atoms unstable and stable to result in the increase and decrease of decay rate, respec12H
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tively. Therefore, it should be predictable that the natural
Earth’s helical motion with periods (daily, seasonal, annual, etc.) would transfer its chirality and rhythms to the
chiral molecules and particles. The preliminary theoretical and experimental results strongly support the
－
prediction[3 8].
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4 Conclusions
In summary, it is found that the radioactive decay rates
of 111In and 32P can be selectively and obviously
changed by the circular rotation depending on its
strength and direction. In comparison with previous
work[2], the circular rotation caused larger effects with
selectivity. Of course, it is interesting to further explore
the physical mechanism to understand these novel effects.
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2
The authors are thankful to Profs. Lemin Li, Guangxian Xu, and Demin
Wang of Peking University for their critical reading of the manuscript and
their invaluable support, as well as to Drs. RD Neumann and IG Panyutin
for their support of the pilot experiments in Department of Nuclear Medicine, Clinical Center, National Institutes of Health (NIH), USA.
Ren S R. Technology of Radionuclide in Biology (in Chinese). Bei-
particles and unification of chiral asymmetries in life on different
jing: Peking University Press, 1997. 30－35, 37, 38
levels. Med Hypotheses, 2000, 54(5): 783－785[DOI]
Ohtsuki T, Yuki H, Muto M, Kasagi J, Ohno K. Enhanced elec-
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7
He Y J, Qi F, Qi S C. Earth’s orbital chirality and driving force of
8
biomolecular evolution. Med Hypotheses, 2001, 56(4): 493－496[DOI]
He Y J, Qi F, Qi S C. The natural Earth’s orbital chirality force field
tron-capture decay rate of 7Be encapsulated in C60 cages. Phys Rev
Lett, 2004, 93(11): 112501－112504[DOI]
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3
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He Y J, Qi S C. Origin and unification of symmetry breaking and
and its role in the origin of life and chemical evolution. Origins Life
Evol B, 2005, 36: 288－289
biological rhythms. In: Li X X ed. 100 Scientific Puzzles in Century
21 (in Chinese). Beijing: Science Press, 2005. 474－480
4
He Y J, Qi F, Qi S C. Effect of chiral helical force on molecular helical
10
Garay A S. Why is chirality so important? Bio Systems, 1987, 20: 1－6
Hegstrom R A, Kondepudi D K. The handedness of the universe. Sci
11
Am, 1990, 262(1): 108－115
Rudaux L, Vaucouleurs G D, Astronomy, 2nd ed. Kent: Prometheus
12
Press, 1962. 52－54
Dougherty R C. Chemical geometrodynamics: gravitational fields can
9
enantiomers and possible origin of biomolecular homochirality. Med
Hypotheses, 1998, 51(2): 125－128[DOI]
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5
He Y J, Qi F, Qi S C. Periodicity of Earth’s orbital chirality and possible mechanism of biological rhythms. Med Hypotheses, 2000, 55(3):
253－256[DOI]
He Y J, Qi F, Qi S C. Effect of Earth’s orbital chirality on elementary
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6
174
influence the course of prochiral chemical reaction. J Am Chem Soc,
1980, 102(1): 380－381[DOI]
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