THE PROTONATION OF A RETINYL SCHIFF BASE

The hydrogen bonding-protonation equilibrium for retinyl Schiff base/propionic acid or 3-chloropropionic acid systems was examined by Fourier transform infrared spectroscopy in non polar solutions at temperatures ranging from 25 degrees C to about -150 degrees C. The spectra give evidence for the gradual increase in the degree of protonation as temperature is lowered. The bearing of this on applying low temperature spectroscopic results to physiological conditions in rhodopsin research is discussed.     

Linear dynamical systems with integer constraints

We study properties of dynamic discrete-time linear systemswith the input or the state constrained to have integer components.The reachability of input-constrained systems is investigated,and consistency conditions for state-constrained systems aregiven.     

钾蒸气中的偶极禁戒双光子共振四波混频和混合激发能量转移受激辐射

本文首次报道了由钾分子-原子系统的混合激发和碰撞能量转移过程产生4F→3D受激辐射以及由钾原子的4S→4F偶极禁戒双光子共振产生4F→3D受激辐射和四波混频的研究结果。     

液氦温区两级4K脉冲管制冷机数值模拟

为模拟和动态显示工作在液氦温区的两级4K脉冲管制冷机内部工作过程和参数变化规律,发展了一种新的欧拉法-拉格朗日法数值计算模型。采用拉格朗日方法,直接跟踪脉冲管中气体微元随周期性压力波动的具体运行轨迹;采用欧拉法,直接模拟蓄冷器内部的动态参数变化。本文简单介绍该模型,并模拟了一典型两级4 K脉冲管制冷机各参数的变化情况,分析了多层磁性蓄冷材料对制冷机性能的影响情况。     

A one-dimensional microscopic model for the rate of thermal desorption of an atom. The role of multiphonon processes

A one-dimensional microscopic model is used to calculate the desorption rate and to investigate the role of multiphonon processes in desorption. If the vibrational frequency of the chemisorptive bond is larger than the Debye frequency, multiphonon processes of all orders must be included as in our one-dimensional microscopic multiphonon model.     

[H_2N(C_2H_4)_2NH_2]_4(H_3O)[PMo_2~VMo_6~(VI)V_4~(IV)O_(40)(V~(IV)O)_2]·H_2O: A New Highly Reduced, Bicapped Pseudo-Keggin Vanadylpolymolybdophosphate

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Shake-up peak positions and intensities by many-body theory methods

The valence shell X-ray photoelectron spectrum of N₂ is calculated using the equations-of-motion—Green's function method. The inclusion of shake-up basis operator configurations in the primary operator space along with the simple ionization operator configurations allows for the calculation of shake-up peak positions on an equal footing with the simple ionization energies. The important shake-up basis operator configurations are identified using configuration selection techniques similar to those which have been successfully employed in large scale configuration interaction problems, thus minimizing the size of the matrices to be diagonalized. The relative peak intensities are calculated within the plane wave approximation. The intensity equations are analyzed indicating that the relative peak intensities are more sensitive to ground state correlation effects than the peak positions. Modifications of the theory to improve the calculations of shake-up energies are discussed.     

GLOBAL ANALYSIS OF THE TIME-RESOL VED FLUORESCENCE OF α-CHYMOTRYPSINOGEN A AND α-CHYMOTRYPSIN POWDERS AS A FUNCTION OF HYDRATION

The time-resolved tryptophyl fluorescence of alpha-chymotrypsin A and alpha-chymotrypsin in the crystalline state and in buffer solution at room temperature was analyzed globally. Triple-exponential decay functions are necessary to adequately describe the tryptophyl fluorescence decay surfaces of the protein powders as a function of hydration and in solution. The fluorescence lifetimes of alpha-chymotrypsinogen A (tau 1 = 0.32, tau 2 = 1.30 ns, tau 3 = 3.98 ns) and alpha-chymotrypsin(tau 1 = 0.66 n s, tau 2 = 2.26 ns, tau 3 = 5.40 ns) are constant over the entire hydration range. The spectral positions of the decay-associated spectra of the hydrated powders do not shift as a function of hydration. This indicates that the structures of the zymogen and the active enzyme are unaffected by hydration. The lifetimes of alpha-chymotrypsinogen A in phosphate buffer pH 7.4 are tau 1 = 0.37 ns, tau 2 = 1.17 ns and tau 3 = 3.44 ns while the respective values of alpha-chymotrypsin are tau 1 = 0.47 ns, tau 2 = 1.40 and tau 1 = 3.89 ns.     

Relativistic effective valence shell Hamiltonian method: excitation and ionization energies of heavy metal atoms

The relativistic effective valence shell Hamiltonian H(v) method (through second order) is applied to the computation of the low lying excited and ion states of closed shell heavy metal atoms/ions. The resulting excitation and ionization energies are in favorable agreement with experimental data and with other theoretical calculations. The nuclear magnetic hyperfine constants A and lifetimes tau of excited states are evaluated and they are also in accord with experiment. Some of the calculated quantities have not previously been computed.