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.     

Distribution and morphometric studies of flagellar sensilla in Emphorini bees (Hymenoptera, Apoidea)

The tribe Emphorini is a group of pollen-collecting solitary bees with a geographical distribution restricted to the western hemisphere. Most of the Emphorini bees collect Page 10 linepollen from a few specific plant families and display specialized behaviors for constructing their nests. Insect sensilla are the basic structural and functional units of cuticle receptors, serving mainly mechano- and chemo-receptor functions. The external morphology of the antennal sensilla has been well characterized in species of different families of Apoidea, however there is scarce information about this issue in solitary bees of the family Apidae. For a better understanding of the association between the external sensory system and several types of behaviors which emerged along the evolutionary history of bees, it is important to characterize the antennal receptors in several representative species of this tribe. The distribution of the antennal sensilla on the dorsal flagella of 18 taxa was studied in insects of both sexes, using light and scanning electron microscopy. There were six types of sensilla and setae on the antennae, which were identified as sensilla placodea, trichodea, basiconica, coeloconica, coelocapitular and ampullacea. The sensilla trichodea were classified into subtypes, A, B, C-D. Sensilla subtype A were the most abundant sensilla and were distributed over the entire antennae, while sensilla placodea and sensilla trichodea type B, showed a restricted distribution on specific areas of the flagella. We have recognized four patterns of spatial distribution of setae on dorsal flagella. Species having setae on the distal part of the flagellomeres tended to contain a low density of sensilla trichodea type A. Females showed a higher number of sensilla subtypes B and C-D than males; instead sensilla trichodea A were more abundant in males. No significant difference was found in the number of sensilla placodea, ampullacea, coeloconica and coelocapitular. Sensilla basiconica were found only in females. Our results showed that gustative and tactile sensilla were more abundant in female bees, as well as, olfactory receptors predominate in the antennal system of males. The possible coevolution of flagellar sensilla in males and females of solitary bees is discussed in light of previous reports. Patterns of distribution of setae determine the relative abundance of the types of sensilla in the flagellum.     

The kinetic limitation of anti-stokes luminescence of Er3+ and Yb3+ doped infrared upconversion materials

Infrared-to-visible wave-length conversion in the Yb³⁺−Er³⁺ doped phosphors system has been described by a simple three level model based on two ions mechanism. The excitation in the range of 900–1000 nm of an IR-photon is first absorbed by Yb³⁺ ion as a sensitizer attributed to the resonant energy transition in Er³⁺ ion from ⁴ I _3/2 → ⁴ S _15/2 and ¹ F _9/2 → ⁴ I _15/2, respectively for green and red emission. The essential energy transfer processes in this system i.e. upconversion from ⁴ I _11/2 and ¹ I _13/2, cross-relaxation from ⁴ S _3/2 and ¹ F _9/2 are taken into account. The limitations of the rate-equation approach are examined with a focus on the underlying dynamics of this rare-earth system.