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21.
Zbigniew Koza 《Physica A》1997,240(3-4):622-634
We examine the long-time behaviour of A + B(static) → 0 reaction-diffusion systems with initially separated species A and B. All of our analysis is carried out for arbitrary (positive) values of the diffusion constant DA of particles A and initial concentrations a0 and b0 of A's and B's. We derive general formulae for the location of the reaction zone centre, the total reaction rate, and the concentration profile of species A outside the reaction zone. The general properties of the reaction zone are studied with a help of the scaling ansatz. Using the mean-field approximation we find the functional forms of ‘tails’ of the reaction rate R and the dependence of the width of the reaction zone on the external parameters of the system. We also study the change in the kinetics of the system with DB > 0 in the limit DB → 0. Our results are supported by numerical solutions of the mean-field reaction-diffusion equation. 相似文献
22.
Zbigniew Koza 《Journal of statistical physics》1996,85(1-2):179-191
We examine the long-time behavior of A+B0 reaction-diffusion systems with initially segregated species A and B. All of our analysis is carried out for arbitrary (positive) values of the diffusion constantsD
A andD
B and initial concentrationsa
0 andb
0 of A's and B's. We divide the domain of the partial differential equations describing the problem into several regions in which they can be reduced to simpler, solvable equations, and we merge the solutions. Thus we derive general formulas for the concentration profiles outside the reaction zone, the location of the reaction zone center, and the total reaction rate. An asymptotic condition for the reaction front to be stationary is also derived. The properties of the reaction layer are studied in the mean-field approximation, and we show that not only the scaling exponents, but also the scaling functions are independent ofD
A,D
B,a
0 andb
0. 相似文献
23.
ÜMMÜHAN OCAK HALIT KANTEKIN YAŞAR GÖK H. BASIR ŞENTÜRK 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(1-2):87-91
The selective liquid–liquid extraction of various transition metal cations from the aqueous phase to the organic phase was carried out using a 14-membered N2O2S2-macrobicycle. Metal picrates such as Pb2+, Co2+, Zn2+, Ni2+,Cu2+ and Cd2+ were used in this extraction studies. It was found that the ligand showed moderate selectivity towards Pb2+ only among the other metals. The extraction constant (log K
ex) was determined to be 13.8 for Pb2+ complex. 相似文献
24.
25.
26.
27.
I. V. Kalinin M. Koza H. Lauter V. V. Lauter-Pasyuk A. V. Puchkov 《Crystallography Reports》2007,52(3):466-470
The structural dynamic factor S(Q, ω) of liquid 4He has been measured by inelastic neutron scattering in films of different thickness at temperatures from 0.6 to 0.05 K. The measurements were performed on an IN6 spectrometer (Institut Laue-Langevin, France). Analysis of the obtained experimental data on S(Q, ω) made it possible to establish the main parameters of surface excitations arising in a helium film and their dependences on the film temperature and thickness. The measurements showed that surface excitations arise in a helium film at a thickness of about two to three atomic layers, and the film thickness plays a decisive role in the formation of surface excitations. 相似文献
28.
Jakub Adam Koza Sascha Mühlenhoff Margitta Uhlemann Kerstin Eckert Annett Gebert Ludwig Schultz 《Electrochemistry communications》2009,11(2):425-429
The effect of a magnetic field in the perpendicular-to-electrode configuration on the hydrogen evolution reaction (HER) was investigated during the deposition of Co. An enhanced desorption of hydrogen in the form of numerous small bubbles was found by combining potentiostatic investigations, coupled with an electrochemical quartz crystal microbalance (EQCM), and simultaneous microscopic observations of the electrode surface. The results are consistent with the recently proposed qualitative model [J.A. Koza, M. Uhlemann, A. Gebert, L. Schultz, Electrochem. Commun. 10 (2008) 1330]. 相似文献
29.
K. Schmalzl D. Wallacher M. M. Koza M. Rheinstädter D. Strauch K. Knorr 《The European physical journal. Special topics》2007,141(1):117-120
The role of geometrical confinement on the dynamics of
argon is studied. We have investigated 36Argon adsorbed
in nanoporous Gelsil glass by inelastic neutron scattering.
By fractional filling the `dimensionality' of the system is tuned
from a two-dimensional towards the bulk state. Ab-initio
calculations of plane sheets of Ar atoms and of bulk Ar are
compared to the experimental results. A shift of various phonon
modes to lower energies with decreasing dimensionality is observed
in the results of both methods. 相似文献
30.
Experimental results on the nuclear spin-lattice and nuclear spin-spin relaxation times in the ferromagnetic EuB6 at temperatures below 4·2 K are presented using the external magnetic field,H
ext, in the range of 0 ⩽H
ext ⩽ 10 kG. Nuclear spin-spin relaxation time computed on the basis of the Suhl-Nakamura process turns out to be 3·2μs, which compares well with the experimental value 11·1μs obtained with the 10 kG magnetic field at 1·7 K. It is found that in the ferromagnetic EuB6,T
1 is approximately 5 × 103 times larger thanT
2 at 1·7 K with the 10 kG magnetic field. Thus the effect ofT
1 onT
2 can be neglected. From the experimental value ofT
2, the value of the homogeneous line broadening is found to be 14 kHz. The corresponding value obtained from the cw method
is 175 kHz. This evidently shows the presence of the inhomogeneous line broadening in the cw NMR. 相似文献