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991.
Ümit Akbey Robert Graf Yuan G. Peng Peter P. Chu Hans W. Spiess 《Journal of Polymer Science.Polymer Physics》2009,47(2):138-155
NMR studies of the structure and dynamics of a system composed of the acidic polymer poly(acrylic acid) (PAA) and the basic polymer poly(4‐vinyl pyridine) (P4VP) are presented. This system aims at the application of anhydrous proton‐conducting membranes that can be used at elevated temperatures at which the proton conduction of hydrated membranes breaks down. The 1H NMR measurements have been preformed under fast magic angle spinning (MAS) conditions to achieve sufficient resolution and the applied 1H NMR methods vary from simple 1H MAS to double‐quantum filtered methods and two‐dimensional 1H double‐quantum spectroscopy. The dynamic behavior of the systems has been investigated via variable temperature 1H MAS NMR. 13C cross‐polarization MAS NMR provides additional aspects of dynamic and structural features to complete the picture. Different types of acidic protons have been identified in the studied PAA‐P4VP systems that are nonhydrogen‐bonded free acidic protons, hydrogen‐bonded dicarboxylic dimers, and protons forming hydrogen bonds between carboxylic protons and ring nitrogens. The conversion of dimer structures in dried PAA to free carboxylic acid groups is accomplished at temperatures above 380 K. However, the stability of hydrogen‐bonding strongly depends on the hydration level of the polymer systems. The effect of hydration becomes less apparent in the complexes. An inverse proportionality between hydrogen‐bonding strength and proton conduction in the PAA‐P4VP acid–base polymer blend systems was established. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 138–155, 2009 相似文献
992.
993.
994.
G. Patermarakis J. Chandrinos K. Masavetas 《Journal of Solid State Electrochemistry》2007,11(9):1191-1204
A holistic model for the kinetics of steady state growth of porous anodic alumina films in oxalic acid, H2C2O4, solution was developed not necessarily requiring the adoption of any ‘a priori’ mechanism of porous film growth. By this
model the effect of anodising conditions on the transport numbers of Al3+ cations and O2− anions across the barrier layer was revealed. The cation (anion) transport number decreased (increased) with current density,
increased (decreased) with temperature and was unaffected by the concentration of electrolyte or pH. A complementary atomistic-ionic
kinetic model was developed that fully justified these results and showed that the activation distances of Al3+ and O2− transport are comparable, but the activation energy of Al3+ transport is lower mainly due to the much smaller size of Al3+. The validity of the model was tested on the basis of SEM observations, while structural features and the rate of pore wall
dissolution were determined. 相似文献
995.
D. Watanabe H. Ohoyama M. Takahashi T. Kasai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):29-34
The total attenuation cross-section of Rg (3P2) (Rg = Ar, Kr) by
the collision with CF3Br is measured as a function of the magnetic sub
level MJ of Rg (3P2) and the collision energy. For Ar
(3P2), the attenuation process indicates a MJ dependence, in
particular, the cross-section of the MJ = 0 state is lower compared
with that for other states. On the other hand, Kr (3P2) shows no
MJ dependent attenuation. 相似文献
996.
S为1/2体系粉末或冷冻玻璃态电子自旋共振谱的模拟 总被引:1,自引:1,他引:0
本文较详细地介绍了模拟s为1/2体系粉末或冷冻玻璃态电子自旋共振谱的理论基础。给出了具体计算公式,利用这些公式完全可以在微机上进行计算机模拟电子自旋共振谱。 相似文献
997.
J. I. Abdullaev 《Theoretical and Mathematical Physics》2006,147(1):486-495
We consider the Hamiltonian of a system of two fermions on a one-dimensional integer lattice. We prove that the number of
bound states N(k) is a nondecreasing function of the total quasimomentum of the system k ∈ [0, π]. We describe the set of discontinuity points of N(k) and evaluate the jump N(k +0) − N(k) at the discontinuity points. We establish that the bound-state energy z
n
(k) increases as the total quasimomentum k ∈ [0, π] increases.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 147, No. 1, pp. 47–57, April, 2006. 相似文献
998.
Anna Ja?kiewicz Andrzej S. Nowak 《Journal of Mathematical Analysis and Applications》2006,316(2):495-509
We consider Markov control processes with Borel state space and Feller transition probabilities, satisfying some generalized geometric ergodicity conditions. We provide a new theorem on the existence of a solution to the average cost optimality equation. 相似文献
999.
Han-zhou Yu Jing Li Yan-Lin Ye Biao Yang Cheng-Jian Lin Hui-Ming Jia Jian-Ling Lou Xiao-Fei Yang T. Baba Qi-Te Li Yu-Cheng Ge Zhi-Huan Li Hui Hua Jin-Yan Xu Zai-Hong Yang Jun Feng Hong-Liang Zang Qiang Liu Wei Jiang Yang Liu Jing-Jing Li Wei Liu Shi-Wei Bai Jie Chen Jia-Xing Han Jia-Hao Chen Kai Ma Dong-Xi Wang Lei Yang Nan-Ru Ma LI-Jie Sun 《中国物理C(英文版)》2021,45(8):084002-084002-5
1000.
The analysis of the LHCb data on \begin{document}$X(6900)$\end{document} ![]()
![]()
found in the di-\begin{document}$J/\psi$\end{document} ![]()
![]()
system was performed using a momentum-dependent Flatté-like parameterization. The use of the pole counting rule and spectral density function sum rule provides consistent evidence that both confining and molecular states are possible. Alternatively, the nature of \begin{document}$X(6900)$\end{document} ![]()
![]()
cannot be distinguished if only the di-\begin{document}$J/\psi$\end{document} ![]()
![]()
experimental data with current statistics are available. Nevertheless, we found that the lowest state in the di-\begin{document}$J/\psi$\end{document} ![]()
![]()
system likely has the same quantum numbers as \begin{document}$X(6900)$\end{document} ![]()
![]()
, and \begin{document}$X(6900)$\end{document} ![]()
![]()
is probably not interpreted as a \begin{document}$J/\psi-\psi(2S)$\end{document} ![]()
![]()
molecular state. 相似文献