Effect of pressure on the Curie temperature of annealed Fe-Ni-Cr-Mo-Si-B amorphous alloys

Effect of high pressure on the Curie temperature of annealed Fe₃₀Ni3₆Cr₁₂Mo₂Si₅B₁₅ amorphous alloys has been investigated. It has been shown that the annealed samples e hibit a smaller pressure dependence ofT _c than as-quenched one.Dedicated to Dr. S. Krupika on the occasion of his 65th birthday.We would like to thank Dr. P. Duhaj (Institute of Physics, Slovak Academy of Sciences, Bratislava) for the preparation of amorphous samples and Mrs. H. Kuchárska for technical assistance.     

Finite projective spaces and intersecting hypergraphs

Let ? be a family ofk-subsets on ann-setX andc be a real number 0 <c<1. Suppose that anyt members of ? have a common element (t ≧ 2) and every element ofX is contained in at mostc|?| members of ?. One of the results in this paper is (Theorem 2.9): If $$c = {{(q^{t - 1} + ... + q + 1)} \mathord{\left/ {\vphantom {{(q^{t - 1} + ... + q + 1)} {(q^t + ... + q + 1)}}} \right. \kern-\nulldelimiterspace} {(q^t + ... + q + 1)}}$$ . whereq is a prime power andn is sufficiently large, (n >n (k, c)) then The corresponding lower bound is given by the following construction. LetY be a (q ^t + ... +q + 1)-subset ofX andH ₁,H ₂, ...,H _|Y| the hyperplanes of thet-dimensional projective space of orderq onY. Let ? consist of thosek-subsets which intersectY in a hyperplane, i.e., ?={F∈( _k ^X ): there exists ani, 1≦i≦|Y|, such thatY∩F=H _i }.     

Effect of ionic additives on the elution of sodium aryl sulfonates in supercritical fluid chromatography

Addition of a small amount of polar solvent (i.e., modifier) to CO2 in packed column supercritical fluid chromatography (SFC) has shown major improvements in both polar analyte solubility and interaction of the polar analyte with the stationary phase. Recently, the addition of an ionic component (i.e., additive) to the primary modifier by one of us has been shown to extend even further the application of SFC to polar analytes. In this work, the effect of various ionic additives on the elution of ionic compounds, such as sodium 4-dodecylbenzene sulfonate and sodium 4-octylbenene sulfonate, has been studied. The additives were lithium acetate, ammonium acetate, tetramethylammonium acetate, tetrabutylammonium acetate, and ammonium chloride dissolved in methanol. Three stationary phases with different degrees of deactivation were considered: conventional cyanopropyl, deltabond cyanopropyl, and bare silica. The effect of additive concentration and additive functionality on analyte retention was investigated. Sodium 4-dodecylbenzene sulfonate was successfully eluted using all the additives with good peak shape under isocratic/isobaric/isothermal conditions. Different additives, however, yielded different retention times and in some cases different peak shapes.     

Spektralphotometrische Bestimmung des Molekulargewichts von Dextran

Ohne Zusammenfassung

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Spectrophotometric determination of the molecular weight of Dextran

     

Die sechsgliedrigen Ringsysteme PIIISi2N2O, [PVSi2N2O]⊕ und PVSi2N2O

Compounds I-X of the sixmembered ring system PSi₂N₂O with phosphorus in different oxidation and bond numbers, collected in Schema 1, have been prepared for the first time and confirmed in their structure by elemental analysis as well as by infrared and¹H- and³¹P-spectroscopy.

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Mit Auszügen aus der DissertationK. P. Giesen, Techn. Univ. Braunschweig 1972.     

用高效液相色谱手性固定相法拆分芳香仲醇及芳香乙二 醇类手性化合物

在ChiralcelOD和ChiralcelOJ两支多糖类手性固定相上，以各种不同配比的正己烷-异丙醇为洗脱剂对38种带有不同取代基的芳香仲醇及芳香乙二醇类手性化合物的对映体进行拆分，考察了这些外消旋体在这两支手性柱上的色谱行为。结果表明，扬长避短一柱对这些化合物的拆分能力与化合物取代基的性质和位置有关，这些化合物与手性固定相之间的氢键作用和π-π作用是影响手性拆分的重要原因。拆分方法已应用于潜手性酮不对称还原产物的光学纯度的鉴定，并取得了很好的效果。     

钯催化下有机锡化合物的偶联反应在碳-碳键形成过程中的应用

本文述评了最近几年来钯催化的有机锡化合物与有机亲电试剂的交叉偶联反应在有机合成中用于碳-碳键形成的主要研究成果。主要讨论了直接交叉偶联反应,CO或烯键插入的交叉偶联反应和机理。     

Interpretation of the Metabolic Enthalpy Change, ΔHmet,Calculated for Microbial Growth Reactions in Soils

The microcalorimetric method was used to calculate the metabolic enthalpy change per mol of glucose degraded by soil microorganisms, ΔH _met. This parameter has been calculated by microcalorimetry for many organic, inorganic and biochemical reactions, but there is only some information about its quantification for microbial growth reactions in soils. Values of ΔH _met were calculated for different soil samples collected in Galicia (Spain) and Campinas (Săo Paolo, Brazil). Exponential microbial growth was stimulated in all soil samples by the addition of glucose and power-time curves were recorded. Results showed changes in the values of ΔH _met calculated for all the soil samples, suggesting a dependence of this value with the microbial growth rate constant, with the percentage of growth, with the initial number of microorganisms of soil samples, with the quantity of glucose added and with the strain of bacteria growing in soil. The interpretation of variations of ΔH _met provides important qualitative and quantitative information. It reports data that allow to interpret from a qualitative point of view, the increase in biomass as a consequence of the degradation of the organic matter in soil, to understand changes in the percentages of soil organic matter and to know if the microbial population growing in differential soil samples is homogeneous. Therefore, to report that value would be very important in ecological studies, but beforehand, it is necessary to solve some problems that can appear in the experiments done to make the quantification . This revised version was published online in August 2006 with corrections to the Cover Date.     

^1H弛豫研究具有表面活性的探针: 2-氯-N-十二烷基吡啶盐碘化 物(CDPI)在不 同集合体内的动态行为

本文报道具有表面活性的探针---2-氯-N-十二烷基吡啶盐碘化物(CDPI)的疏水碳氢链在几种包结体(胶束、包结在环糊精(β-CD)中以及包结在甲基直链淀粉(MA))中的^1H核磁弛豫时间。通过比较CDPI中碳氢链的CH~3、(CH~2)~9的T~1及T~1(CH~3)/T~1(CH~2)~9的变化,发现CDPI的运动自由度按下列次序降低:游离态、包结在β-CD中、胶束状态、包结在MA中,顺磁离子Mn^2^+对CDPI内各种质子的T~1的影响随其所处之包结体不同而变化。在胶束和甲基直链淀粉体系中,烷链的T~1几乎均不受Mn^2^+的影响,说明水合Mn^2^+不能进入CDPI胶束或甲基直链淀粉的螺旋内穴。