Current trends in lead discovery: are we looking for the appropriate properties?

The new drug discovery paradigm is based on high-throughput technologies, both with respect to synthesis and screening. The progression HTS hits lead series candidate drug marketed drug appears to indicate that the probability of reaching launched status is one in a million. This has shifted the focus from good quality candidate drugs to good quality leads. We examined the current trends in lead discovery by comparing MW (molecular weight), LogP (octanol/water partition coefficient, estimated by Kowwin [17]) and LogSw (intrinsic water solubility, estimated by Wskowwin [18]) for the following categories: 62 leads and 75 drugs [11]; compounds in the development phase (I, II, III and launched), as indexed in MDDR; and compounds indexed in medicinal chemistry journals [ref. 20], categorized according to their biological activity. Comparing the distribution of the above properties, the 62 lead structures show the lowest median with respect to MW (smaller) and LogP (less hydrophobic), and the highest median with respect to LogSw (more soluble). By contrast, over 50% of the medicinal chemistry compounds with activities above 1 nanomolar have MW > 425, LogP > 4.25 and LogSw < -4.75, indicating that the reported active compounds are larger, more hydrophobic and less soluble when compared to time-tested quality leads. In the MDDR set, a progressive constraint to reduce MW and LogP, and to increase LogSw, can be observed when examining trends in the developmental sequence: phase I, II, III and launched drugs. These trends indicate that other properties besides binding affinity, e.g., solubility and hydrophobicity, need to be considered when choosing the appropriate leads.     

Reflections regarding uncertainty of measurement, on the results of a Nordic fatigue test interlaboratory comparison

This paper presents the experiences of calculation and reporting uncertainty of measurement in fatigue testing. Six Nordic laboratories performed fatigue tests on steel specimens. The laboratories also reported their results concerning uncertainty of measurement and how they calculated it. The results show large differences in the way the uncertainties of measurement were calculated and reported. No laboratory included the most significant uncertainty source, bending stress (due to misalignment of the testing machine, incorrect specimens and/or incorrectly mounted specimens), when calculating the uncertainty of measurement. Several laboratories did not calculate the uncertainty of measurement in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) [1].     

Poly(urethane-oxazolidone): Synthesis, characterisation and shape memory properties

Poly(urethane-oxazolidone) were synthesized by reacting isocyanate-terminated oxazolidone with hydroxy-telechelic poly(tetramethylene oxide) (PTMO). The molar ratios of the reactants were varied to get polymers of varying oxazolidone and urethane compositons. The polymers were characterized by DSC, FTIR, XRD, dynamic mechanical thermal analysis and chemical analyses. An increase in the concentration of urethane and oxazolidone groups caused a decrease in tensile strength and elongation of the poly(urethane-oxazolidone). The polymers possessed crystallites of PTMO whose melting transition temperature decreased on enhancing the oxazolidone concentration. The polymers exhibited thermo-responsive shape memory properties, which was confirmed and quantified by cyclic tensile tests. The influence of oxazolidone modification and the consequent soft/hard segment variation on the thermal, mechanical, dynamic-mechanical and shape recovery properties of the resultant polymers was investigated. The oxazolidone moities conferred enhanced shape recovery and shape fixity to the polyurethane.     

通用复习练习多媒体课件写作工具的开发与应用

叙述了通用复习练习多媒体课件写作工具（ＣＡＩＸ１．０）的模块结构及其相互关系、功能与应用。ＣＡＩＸ１．０的导航器和编辑器使用户很容易地生成、编辑和组织多媒体复习练习课件。ＣＡＩＸ课件可提高复习练习效率和效果,又可加强对学生学习的监控、评估和指导作用。可免费下载使用（ｈｔｔｐ：／／ｃｈｅｍｓｏｆｔ．ｙｅａｈ．ｎｅｔ）。     

抗癌药物与DNA作用的电化学研究进展

针对当前电化学研究领域中的热门课题——DNA的电化学研究，阐述了与DNA的电化学研究相关的理论基础，其中包括作用机理和作用模式等，概述了其近几年的研究进展，并在此基础上对抗癌药物与DNA的相互作用的电化学研究工作特别是该研究的潜在应用，即抗癌药物的新型筛选方法——电化学筛选方法进行了介绍。     

漆酚缩甲醛镧配合物的制备、结构及性能

利用漆酚缩甲醛(PUF)和三氯化镧在非水热溶剂中反应制得漆酚缩甲醛镧配合物(PUFLa)，IR、XPS和TG表征结果表明：三氯化镧中La^3 与漆酚缩甲醛中酚羟基上的氧形成了配位键；在La^3 的作用下，PUF上的侧链进一步交联聚合。PUFLa在亚硫酸钠水溶液中能引发催化甲基丙烯酸甲酯聚合。通过正交实验设计考察了PUFLa用量、反应温度、反应时间、单体甲基丙烯酸甲酯用量和亚硫酸钠浓度对单体转化率的影响。结果表明。反应温度和反应时间是影响单体转化率的主要因素。PUFLa还具有良好的耐热性和抗溶剂性。     

Use of Sucrose‐based Epoxy ­Formulations and Cellulosic Fibers in ­the Design,Preparation, and Screening ­of New Composite Insulation Materials

Non‐woven composite insulation materials were generated from cotton, kenaf, jute, polyester, polypropylene, sucrose‐based epoxy formulations, and aluminum foil. The needlepunched fiber batts were rendered flame resistant by use of inorganic reagents and urea. To discover suitable epoxy formulations to bind the cellulose fibers to themselves or to dissimilar surfaces and to make flexible composites, a comparison of the performance of the known epoxy allyl sucroses (EAS), epoxy crotyl sucroses (ECS), and diglycidyl ether of bisphenol‐A (DGEBA) was made. The epoxies were cured with commercial diethylenetriamine (DETA), and UNIREZs‐2142 and 2355®, to discover a formulation with the following characteristics: (a) low cure temperature; (b) low Young's moduli and glass transition temperatures of cured thermosets for flexible composites; (c) ample bond strength between the fabric and the bonded surfaces; and (d) non‐cytotoxicity and non‐mutagenicity of the epoxies. Based on results following these criteria, EAS was selected, and the formulation comprising EAS and UNIREZ‐2355® was deemed suitable to bind fiber batts to surfaces of any type and geometry. ASTM guidelines were used to construct a wooden frame cube (heat box) for the simultaneous rapid screening of cellulosic fiber batts and composites. The new materials were compared against R‐19 fiberglass insulation for their ability to resist heat flow (denoted by relative R‐values) and time taken to approach thermal equilibrium. Plain non‐woven cellulosic fiber batts showed relative R‐values of 4.0 °F ft² hr/Btu per inch thickness (0.27 K m²/W per cm), and took about 2 hr to establish equilibrium heat flow. Commercial fiberglass batts showed relative R‐values­of 2.2 per in (0.15 per cm) and took 1 hr to attain equilibrium heat flow. When 6.25 in (15.9 cm) thick batts of fiberglass were needle punched to a thickness of 1 in (2.54 cm), relative R‐values and equilibrium heat flow times were 4.0 per in (0.27 per cm) and 2 hr, respectively. This denoted that the densities and thermal resistances of non‐conducting materials are raised concurrently. Anisotropic heat flow behavior was observed in cellulosic fiber composites with aluminum foil (shiny side out) bonded on one side. It depended upon whether the aluminum foil side or the fibers side faced the heat source. In the latter orientation the aluminum acted as a heat sink, and in the former orientation the foil acted as a poor heat reflector. The poor performance of these insulation composites was related to the fact that aluminum was directly bonded to the fiber batts and was acting as a heat conductor. When cellulose fiber shims (spacers) were placed between the fiber batts and the aluminum foil, the R‐values of the composites were comparable to those of plain batts but the times taken to approach thermal equilibrium increased to >3 hr, denoting that the foil was acting more as a reflector and less as a conductor. Copyright © 2001 John Wiley & Sons, Ltd.     

Experiments with an interactive paired comparison simplex method for molp problems

In this paper, an interactive paired comparison simplex based method formultipleobjectivelinearprogramming (MOLP) problems is developed and compared to other interactive MOLP methods. Thedecisionmaker (DM)'s utility function is assumed to be unknown, but is an additive function of his known linearized objective functions. A test for utilityefficiency for MOLP problems is developed to reduce the number of efficient extreme points generated and the number of questions posed to the DM. The notion of strength ofpreference is developed for the assessment of the DM's unknown utility function where he can express his preference for a pair of extreme points as strong, weak, or almost indifferent. The problem of inconsistency of the DM is formalized and its resolution is discussed. An example of the method and detailed computational results comparing it with other interactive MOLP methods are presented. Several performance measures for comparative evaluations of interactive multiple objective programming methods are also discussed.All rights reserved. This study, or parts thereof, may not be reproduced in any form without written permission of the authors.     

纺织品中游离甲醛含量的高效液相色谱法测定

建立了纺织品中游离甲醛的高效液相色谱检测法,采用SinoChrom ODS-BP色谱柱(250×4.6 mm i.d.,5μm),流动相为甲醇-水(70∶30,V/V),流速1.0 mL/min,检测波长360 nm。通过正交试验优化了甲醛衍生条件,应用F检验和t检验证实了本方法的准确性。方法相对标准偏差(RSD)为2.53%,回收率在95.0%~102.7%范围。     

The MICE facility – a new tool to study plant–soil C cycling with a holistic approach

Plant–soil interactions are recognized to play a crucial role in the ecosystem response to climate change. We developed a facility to disentangle the complex interactions behind the plant–soil C feedback mechanisms. The MICE (‘Multi-Isotope labelling in a Controlled Environment’) facility consists of two climate chambers with independent control of the atmospheric conditions (light, CO₂, temperature, humidity) and the soil environment (temperature, moisture). Each chamber holds 15 plant–soil systems with hermetical separation of the shared above ground (shoots) from the individual belowground compartments (roots, rhizosphere, soil). Stable isotopes (e.g. ¹³C, ¹⁵N, ²H, ¹⁸O) can be added to either compartment and traced within the whole system. The soil CO₂ efflux rate is monitored, and plant material, leached soil water and gas samples are taken frequently. The facility is a powerful tool to improve our mechanistic understanding of plant–soil interactions that drive the C cycle feedback to climate change.