Intermediate coupling model description of55Fe and57Fe

The properties of the negative parity states of⁵⁵Fe and⁵⁷Fe are investigated in the framework of the intermediate coupling model. In the model, a neutron or a quasineutron is coupled to anharmonic vibrations of the core. Anharmonicities of the vibrations are estimated through the observed properties of the core. Energy levels, spectroscopic factors and electromagnetic properties have been calculated. The results of the present calculations are also compared with available experimental results and other theoretical results. The model reasonably accounts for many of the properties of the low-lying states.     

Effect of radiative cooling on collapsing charged grains

The effect of the radiative cooling of electrons on the gravitational collapse of cold dust grains with fluctuating electric charge is investigated. We find that the radiative cooling as well as the charge fluctuations, both, enhance the growth rate of the Jeans instability. However, the Jeans length, which is zero for cold grains and nonradiative plasma, becomes finite in the presence of radiative cooling of electrons and is further enhanced due to charge fluctuations of grains resulting in an increased threshold of the spatial scale for the Jeans instability.     

Automatic Structure Determination of Organic Molecules： Principle and Implementation of the LSD Program

The LSD (Logic for Structure Determination) program gener-ates organic molecular structures from 1D and 2D NMR data without resorting to chemical shift databases. Its use in the res-olution of natural product structure determination problems has been already reported in the literature. This paper describes how data and structures are internally represented and pro-cessed by LSD to build solution structures.     

APPLICATION OF GENETIC ALGORITHM IN PARTICLE SIZE ANALYSIS BY MULTISPECTRAL EXTINCTION MEASUREMENTS

Both dependent and independent model algorithms are designed with genetic algorithm (GA) to retrieve aerosol size data from multispectral extinction measurements. Compared with the traditional dependent model algorithm, e.g., simplex, GA can locate the global optimized solution instead of local ones. As an independent model algonthm, when combined with B-splines, GA gives consistent results with Chahine and Phillip-Twomey-NNLS algorithms. Numerical simulations also show that GA has high stability and good resistance to relatively higher error levels. For a population size of 50 in the present paper, the feasible ranges for genetic operators Pc and pm are found to be [0.01, 0.5] and [0.01, 0.15], respectively, and the generation number Gen_Max should be larger than 250.     

Proton shielding function for hydrogen chloride

For a diatomic molecule the nuclear shielding constant σ(ξ) of either nucleus can be expanded as a power series in the relative displacement from equilibrium ξ. Thus the nuclear shielding function is

where ξ=(r-r _e)/r _e with r the actual bond length and r _e the equilibrium bond length. The σ_e ⁽ⁱ⁾ are molecular parameters. By experimental observation of the temperature dependence of the proton magnetic shielding of hydrogen chloride gas it is possible, after allowing for intermolecular effects, to obtain the values σ_e ⁽⁰⁾=32·48 (±0·33) p.p.m. and σ_e ⁽¹⁾=-100 (±24) p.p.m. for the coefficients of the proton shielding function. Using this data it is possible to show that the isotope shift between H³⁷Cl and H³⁵Cl is about 0·001 p.p.m. By a comparison with earlier results for molecular hydrogen it would appear that in some instances differences in vibrational and rotational averaging may alter chemical shifts between different compounds by amounts considerably larger than the experimental error in chemical shift measurement.