Non-Isothermal Crystallization of Cordierite Glasses

A study is reported of the crystallization behaviour of some glass compositions which belong in the system MgO-Al₂O₃-SiO₂ and which lead to vitreous ceramics with α-cordierite as a main phase. DTA, X-ray diffraction and dilatometric analysis were used to investigate the influence of the type and concentration of the nucleation agents. The activation energies of crystallization were calculated and the crystalline phases were identified. This revised version was published online in August 2006 with corrections to the Cover Date.     

溴化四丁基铵-碘化钾-水体系中Bi(Ⅲ)与Zr(Ⅳ)、Ce(Ⅲ)、U(Ⅵ)和Mg(Ⅱ)的浮选分离

在水溶液中,Bi(Ⅲ)与溴化四丁基铵和KI形成不溶于水的三元缔合物BiI-4·TBAB+,此三元缔合物沉淀浮于盐水相上层形成界面清晰的液-固两相。当溶液中溴化四丁基铵和KI的浓度分别为5.0×10-4mol/L和3.0×10-3mol/L,pH=3时,Bi(Ⅲ)可与Zr(Ⅳ)、Ce(Ⅲ)、U(Ⅵ)和Mg(Ⅱ)定量分离,Bi(Ⅲ)的浮选率达到100%。对合成水样中Bi(Ⅲ)的分离和测定,效果良好。该方法具有选择性高,操作简便和不污染环境等特点,在微量铋的分离和富集分析中有一定的实用价值。     

Distant collaboration in drug discovery: the LINK3D project

The work describes the development of novel software supporting synchronous distant collaboration between scientists involved in drug discovery and development projects. The program allows to visualize and share data as well as to interact in real time using standard intranets and Internet resources. Direct visualization of 2D and 3D molecular structures is supported and original tools for facilitating remote discussion have been integrated. The software is multiplatform (MS-Windows, SGI-IRIX, Linux), allowing for a seamless integration of heterogeneous working environments. The project aims to support collaboration both within and between academic and industrial institutions. Since confidentiality is very important in some scenarios, special attention has been paid to security aspects. The article presents the research carried out to gather the requirements of collaborative software in the field of drug discovery and development and describes the features of the first fully functional prototype obtained. Real-world testing activities carried out on this prototype in order to guarantee its adequacy in diverse environments are also described and discussed.In addition to the mentioned institutions the LINK3D Consortium is constituted by     

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

The new drug discovery paradigm is based on high-throughputtechnologies, both with respect to synthesis and screening. Theprogression HTS hits lead series candidatedrug marketed drugappears to indicate that the probability of reaching launched status isone in a million. This has shifted the focus from good qualitycandidate drugs to good quality leads. We examined the current trendsin 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), asindexed 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 leadstructures show the lowest median with respect to MW (smaller) and LogP(less hydrophobic), and the highest median with respect to LogSw (moresoluble). By contrast, over 50% of the medicinal chemistry compoundswith activities above 1 nanomolar have MW > 425, LogP > 4.25 andLogSw < -4.75, indicating that the reported active compounds arelarger, more hydrophobic and less soluble when compared to time-testedquality leads. In the MDDR set, a progressive constraint to reduce MWand LogP, and to increase LogSw, can be observed when examining trendsin 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 whenchoosing the appropriate leads.     

Spectroellipsometric Characterization of Multilayer Sol-Gel Fe2O3 Films

Multilayer Fe₂O₃ films were deposited by the sol-gel method on glass substrates using three successive deposition procedures. The films were thermally treated for 1 h at 300°C.The optical and microstructural properties of these films were investigated by spectroscopic ellipsometry (SE) in the 500–1000 nm range. The optical gap was found by fitting the dispersion of the film refractive index (n) with the Wemple-DiDomenico (WDD) formula.The ellipsometric measurements showed also that the Fe₂O₃ films are anisotropic. The birefringence values (n) of the sol-gel films (0.05–0.08) are smaller than the large values of the Fe₂O₃ (which are around 0.28) but increase with the crystalization of the films. AFM mesurements showed that the films treated at 300°C start to crystallize.     

Koszul–Sullivan Models and the Cohomology of Certain Solvmanifolds

In this paper we develop a technique of working with graded differential algebra models of solvmanifolds, overcoming the main difficulty arising from the non-nilpotency of the corresponding Mostow fibrations. A graded differential model for solvmanifolds of the form G/ with G=RN is presented (N is a nilpotent Lie group, G is a semi-direct product). As an application, we prove the Benson–Gordon conjecture in dimension four.     

Reactivity of acrylic monomers

Summary The copolymerization of N,N-diethylacrylamide (M_l) with methyl acrylate (M₂) was investigated and reactivity ratiosr ₁= 0.41 andr ₂ = 0.52 obtained. Also the distribution of diad fractions was calculated and the results were interpreted in terms of the product of reactivity ratios. The tendency of the two monomers to alternate was explained on the basis of differences in polatities between the double bonds, this explanation being supported both by the values ofe parameter and NMR spectroscopy data. A copolymerization mechanism was suggested.With 5 figures and 2 tables     

“神光”装置的激光能量测量

本文叙述了在神光装置中测量激光能量的体吸收能量计的特点,给出了其工作参数。实测了神光装置中激光系统末级输出能量、激光系统前部和中部定点发射能量及激光系统放大的自发辐射能量。并作了分析和讨论。