On the entropic perturbation and exponential penalty methods for linear programming

This note points out that the recently proposed exponential penalty approach to linear programming is identical to the well-known entropic perturbation approach. The primal and dual trajectories provided by these two approaches are shown to be equivalent.The work of the first author was supported partially by the North Carolina Supercomputing Center and 1995 Cray Research Grant.     

Trading by Quantum Rules: Quantum Anthropic Principle

This is a short review of the background and recent development in quantum game theory and its possible application in economics and finance. The intersection of science and society is discussed and Quantum Anthropic Principle is put forward. The review is addressed to nonspecialists.     

Chiral separability of boron cluster species studied by screening approaches utilizing polysaccharide‐based chiral stationary phases

In this study, the screening steps of chiral separation strategies with polysaccharide‐based chiral stationary phases were applied on boron cluster compounds in normal‐phase liquid chromatography (NPLC) and polar organic solvents chromatography (POSC). Since the screening steps were initially developed to analyze organic compounds, their applicability for boron clusters was investigated. Overall, the screening steps in NPLC were applicable for the separation of zwitterions, while for anions mostly no elution was observed. A hypothesis for the latter behavior is precipitation of anions in the nonpolar mobile phases. Ten out of 11 compounds could be partially or baseline separated on the NPLC screening systems. In POSC, all zwitterions were separated on at least one of the screening systems, with an overall lower retention as in NPLC. Anions were detected but not separated in the majority of the experiments. Also their retention on the chiral stationary phases was very limited. This study showed that the chiral discrimination potential of chemically modified polysaccharides is meaningful for chiral separations of structurally chiral boron cluster species, but needs further systematic research, in which recognition mechanisms should be further explored. In addition, some unusual peaks also indicated that conditions with a high separation efficiency must first be searched for some of the tested systems. Copyright © 2014 John Wiley & Sons, Ltd.     

Identification,control strategies,and analytical approaches for the determination of potential genotoxic impurities in pharmaceuticals: A comprehensive review

Potential genotoxic impurities in pharmaceuticals at trace levels are of increasing concern to both pharmaceutical industries and regulatory agencies due to their possibility for human carcinogenesis. Molecular functional groups that render starting materials and synthetic intermediates as reactive building blocks for small molecules may also be responsible for their genotoxicity. Determination of these genotoxic impurities at trace levels requires highly sensitive and selective analytical methodologies, which poses tremendous challenges on analytical communities in pharmaceutical research and development. Experimental guidance for the analytical determination of some important classes of genotoxic impurities is still unavailable in the literature. Therefore, the present review explores the structural alerts of commonly encountered potential genotoxic impurities, draft guidance of various regulatory authorities in order to control the level of impurities in drug substances and to assess their toxicity. This review also describes the analytical considerations for the determination of potential genotoxic impurities at trace levels and finally few case studies are also discussed for the determination of some important classes of potential genotoxic impurities. It is the authors’ intention to provide a complete strategy that helps analytical scientists for the analysis of such potential genotoxic impurities in pharmaceuticals.     

Design Strategies for High-Performance Aqueous Zn/Organic Batteries

Organic electroactive compounds are attractive to serve as the cathode materials of aqueous zinc-ion batteries (ZIBs) because of their resource renewability, environmentally friendliness and structural diversity. Up to now, various organic electrode materials have been developed and different redox mechanisms are observed in aqueous Zn/organic battery systems. In this Minireview, we present the recent developments in the energy storage mechanisms and design of the organic electrode materials of aqueous ZIBs, including carbonyl compounds, imine compounds, conductive polymers, nitronyl nitroxides, organosulfur polymers and triphenylamine derivatives. Furthermore, we highlight the design strategies to improve their electrochemical performance in the aspects of specific capacity, output voltage, cycle life and rate capability. Finally, we discuss the challenges and future perspectives of aqueous Zn/organic batteries.     

轮烷类化合物的合成方法研究进展

轮烷类互锁分子因其多样的结构和性质,多年来一直是超分子化学领域的一个热点.综述了近年来轮烷类化合物的合成及制备方法,包括用传统的模板法(引入氢键、疏水作用、静电效应、配位和离子诱导等超分子作用)制备轮烷类化合物.除此之外,还介绍了利用“Click”化学、“穿线-收缩”、“穿线-膨胀”、自排序组织和自由基识别等新的合成手段来制备这类化合物.     

西部农村初中化学实验教学现状调查——以甘肃省某县为例

选取甘肃省某县为调查对象,对目前西部农村初中化学实验教学的现状进行调查,分析实验教学中存在的问题及原因。调查显示目前西部农村初中化学实验教学中存在的问题主要有:教师教学理念"陈旧",教师化学实验教学素养较低,学生实验活动缺少合理的评价,教师责任感和教学动力缺失,教师缺乏实验教学的策略,化学实验室正常运转困难,这都会影响化学实验教学。     

Current mass spectrometry strategies for selenium speciation in dietary sources of high-selenium

This document reviews the most relevant mass spectrometry approaches to selenium (Se) speciation in high-Se food supplements in terms of qualitative and quantitative Se speciation and Se-containing species identification, with special reference to high-Se yeast, garlic, onions and Brazil nuts. Important topics such as complexity of Se speciation in these materials and the importance of combining Se-specific detection and molecule-specific determination of the particular species of this element in parallel with chromatography, to understand their nutritional role and cancer preventive properties are critically discussed throughout. The versatility and potential of mass spectrometric detection in this field are clearly demonstrated. Although great advances have been achieved, further developments are required, especially if speciatedcertified reference materials (CRMs) are to be produced for validation of measurements of target Se-containing species in Se-food supplements.     

Optimal hedging strategies for multi-period guarantees in the presence of transaction costs: A stochastic programming approach

Multi-period guarantees are often embedded in life insurance contracts. In this paper we consider the problem of hedging these multi-period guarantees in the presence of transaction costs. We derive the hedging strategies for the cheapest hedge portfolio for a multi-period guarantee that with certainty makes the insurance company able to meet the obligations from the insurance policies it has issued. We find that by imposing transaction costs, the insurance company reduces the rebalancing of the hedge portfolio. The cost of establishing the hedge portfolio also increases as the transaction cost increases. For the multi-period guarantee there is a rather large rebalancing of the hedge portfolio as we go from one period to the next. By introducing transaction costs we find the size of this rebalancing to be reduced. Transaction costs may therefore be one possible explanation for why we do not see the insurance companies performing a large rebalancing of their investment portfolio at the end of each year.     

Analyzing the sustainability of harvesting behavior and the relationship to personality traits in a simulated Lotka–Volterra biotope

For the analysis presented in this paper we use experiments to study human behavior in a simulation environment based on a simple Lotka–Volterra predator–prey ecology. The aim is to study the influence of different harvesting strategies and of certain personality traits derived from the Hamburg Personality Inventory (HPI) [Andresen, B., 2002. HPI – Hamburger Persönlichkeitsinventar. Hogrefe, Göttingen] on the outcome in terms of sustainability and economic performance.