A filter-trust-region method for <Emphasis Type="Italic">LC</Emphasis><Superscript>1</Superscript> unconstrained optimization and its global convergence

In this paper we present a filter-trust-region algorithm for solving LC1 unconstrained optimization problems which uses the second Dini upper directional derivative.We establish the global convergence of the algorithm under reasonable assumptions.     

Daily requirements of Fe,Co and Se during infancy

The daily intakes of trace elements by infants showing optimal pattern of growth are used as the basis to estimate the requirements of Fe, Co and Se during infancy. Since milk is the only food and source of nutrition in the first few months of life, the requirements of these elements are calculated from their average concentrations in human milk and the volume of milk required to supply sufficient amount of energy for maintenance and healthy growth of infants. The concentrations of the three elements in human milk were determined, using the technique of neutron activation followed by radiochemical separation.     

MR十年收录中国数学文献的学科分布及其反映出的数学进展状况

本文以国际性评论、文摘刊物《ＭａｔｈｅｍａｔｉｃｓＲｅｖｉｅｗｓ》（美国数学会出版）在１９８４－１９９３年间摘录文南总量和摘录中国数学研究文献量为统计样本，从分支学科文献量分布的角度，比较了中外数学研究的现状．特别结合国家自然科学基金“七五”、“八五”数学重大项目的研究成果，探讨了目前数学研究的发展趋势．     

Solvolytic Ring-opening of Alkoxychlorofluorocyclopropanes: A Ready Access to Fluorinated α,β-Unsaturated Aldehydes and Ketones

Alkoxychlorofluorocyclopropanes are easily prepared by chlorofluorocarbene addition to en-ethers in a two-phase system and converted by simple heating in an aqueous solvent mixture to 2-fluoro-2-alkenals which can be reduced to the corresponding alcohols.     

Luminescence decay of distant donor-acceptor pairs in phosphorous-doped ZnTe

Luminescence decay of isolated donor-acceptor pairs has been measured over the range of pair distance R ～ 180 Å in phosphorous-doped ZnTe. Analysis of the recombination rate as a function of the pair distance suggests an asymptotic behaviour of the acceptor envelope function of the type exp(-r/a_A), with $\text{a}{}_{\mathrm{A}}\text{= 40 ± 10}\text{A}\text{?}$. This effective Bohr radius would correspond to an hydrogenic mass $\text{m}{}^1\text{= (0.13 ± 0.03)}\text{m}{}_{\mathrm{o}}$, which is close to the light hole mass as measured from cyclotron resonance experiments, $\text{m}{}^1\text{= (0.154 ± 0.005)}\text{m}{}_{\mathrm{o}}$. A discussion on the validity of the isolated donor-acceptor pair model is also given.     

Relevance of ICRP metabolic model of Th in bio-assay monitoring

This paper compares the urinary excretion levels of Th obtained in bio-assay monitoring using the neutron activation technique with those predicted by applying the ICRP metabolic model to the measured Th activity in chest and total body of a group of Thorium plant workers. The results indicated much lower urinary Th excretion as compared to what was expected on the basis of the ICRP model. Lower urinary excretion in occupational subjects is explained in terms of negligible contribution of skeleton and soft tissue to the activity excreted in urine. It is suggested that the existing model should be modified to enable it to be applicable to the bio-assay monitoring of occupational workers.     

Ionic conductivity of conjugated water-soluble rigid-rod polymers

Poly[(1,7-dihydrobenzo[1,2-d:4,5-d′] diimidazole-2,6-diyl)-2-(2-sulfo)-p-phenylene], a conjugated rigid-rod polymer, was derivatized with pendants of propane-sulfonated ionomers. The derivatized rigid-rod polymer was soluble in aprotic solvents as well as in water for isotropic solutions that were processed into isotropic films. Direct-current electrical conductivity σ of the films was measured using the four-probe technique. Room-temperature σ as high as 2.9 × 10^?4S/cm was achieved on pristine isotropic films without using dopants. When the rigid-rod polymer concentration exceeded 25 wt %, the isotropic solution could be transformed into a liquid-crystalline solution that allowed deformations to be applied to produce anisotropic films. Significant increase in σ was obtained in a sheared film along both the parallel direction (∥) and the transverse direction (⊥) with a σ_∥/σ_⊥ = 5. Additionally, enhanced σ was realized in films heat-treated at about 100°C, in the derivatized polymer with higher molecular weight from dialysis, and in substituting the sulfonated ion Na⁺ by H⁺ in the pendants of the polymers. Constant-voltage measurements were applied to the polymers to monitor the σ stability for ascertaining the nature of the conductivity. No electronic contribution in σ was detected. Instead, a monotonically decreasing σ was consistently observed indicative of ionic conductivity. © 1993 John Wiley & Sons, Inc.