Spectrophotometric Determination of δ4 -3-Ketosteroids Using Oxalyldihydrazide

Abstract

A novel spectrophotometric method for the assay of δ⁴ -3-Ketosteroids in formulations is presented. Oxalyldihydrazide in methanol reacts selectively with δ⁴-3-Ketosteroids at pH 2 forming stable hydrazones which exhibit intense absorption specta at 300 nm. and high molar absorpitivities ranging from 14480–18750 for most steroids studied. Methyltestosterone showed exception ally high sensitivity where its molar absorpitivity was 21630. As little as 5–30 μg steroid were determined with 99.28 ± 0.65–100.16 ± 0.94% accuracy. The method was applied successfully to the micro-determination of cortisone, hydrocortisone, hydrocortisone acetate, norethisterone, norethisterone acetate, norgestrel and methyltestosterone in substance as well as in different pharmaceutical dosage forms. The precision of assay was compareble with existing spectrometric methods for ketosteroid drugs. The method is simple, accurate mean - while selective and more sensitive than the INH-method.     

Facile transformation of glutamic acid into proline residue inside a tripeptide backbone

In this Letter we present a simple reaction pathway which allows the conversion of the glutamic acid residue of a tripeptide into a proline residue. The reaction was performed by using Boc-Val-Glu-Phe-NH₂ as a starting material and is based on a NaH-induced intraresidue alkylation under reaction conditions analogous to that adopted during the Freidinger lactams formation.     

Nonemptiness of Approximate Subdifferentials of Midpoint δ-Convex Functions

ABSTRACT

For some given positive δ, a function f:D ? X → ? is called midpoint δ-convex if it satisfies the Jensen inequality f[(x ₀ + x ₁)/2] ≤ [f(x ₀) + f(x ₁)]/2 for all x ₀, x ₁ ∈ D satisfying ‖x ₁ ? x ₀‖ ≥ δ (Hu, Klee, and Larman, SIAM J. Control Optimiz. Vol. 27, 1989). In this paper, we show that, under some assumptions, the approximate subdifferentials of midpoint δ-convex functions are nonempty.     

非化学计量组成Ba1.03Ce0.5Zr0.4La0.1O3－α的化学稳定性和离子导电性

用高温固相反应法合成了非化学计量组成的Ba_1.03Ce_0.5Zr_0.4La_0.1O_{3－α质子导体. 粉末X射线衍射(XRD)结果表明, 该材料为单一钙钛矿型BaCeO3斜方晶结构, 在高温下、CO2或水蒸气气氛中具有较高的稳定性. 扫描电子显微镜(SEM)观察分析表明, 材料经1550 ℃烧结20 h非常致密. 在500～900 ℃温度范围内, 用交流阻抗谱技术测定了材料在湿润氢气和湿润空气气氛中的电导率; 用气体浓差电池方法测定了材料在湿润氢气、湿润空气气氛中和氢-空气燃料电池条件下的离子迁移数, 研究了材料的离子导电特性, 并与化学计量组成的BaCe0.5Zr0.4La0.1O3－α材料进行了比较. 结果表明, 在500～900 ℃温度范围内、湿润氢气气氛中, Ba1.03Ce0.5Zr0.4La0.1O3－α材料的质子迁移数为1, 是一个纯质子导体. 在湿润空气气氛中, 材料的氧离子迁移数为0.688～0.170, 质子迁移数为0.218～0.017, 是一个氧离子、质子和电子空穴的混合导体. 在氢-空气燃料电池条件下, 材料的离子(氧离子＋质子)迁移数为0.990～0.796, 是一个氧离子、质子和电子的混合导体. 与化学计量组成的BaCe0.5Zr0.4La0.1O3－α材料相比较, 在相同实验条件下非化学计量组成的Ba1.03Ce0.5Zr0.4La0.1O3－α材料具有较高的电导率和离子迁移数.}     

A two-particle exchange interaction model

The magnetisation reversal of two interacting particles was investigated within a simple model describing exchange coupling of magnetically uniaxial single-domain particles. Depending on the interaction strength W, the reversal may be cooperative or non-cooperative. A non-collinear reversal mode is obtained even for two particles with parallel easy axes. The model yields different phenomena as observed in spring magnets such as recoil hysteresis in the second quadrant of the field-magnetisation-plane, caused by exchange bias, as well as the mentioned reversal-rotation mode. The Wohlfarth’s remanence analysis performed on aggregations of such pairs of interacting particles shows that the deviation δM(H_m) usually being considered as a hallmark of magnetic interaction vanishes for all maximum applied fields H_m not only at W=0, but also for sufficiently large values of W. Furthermore, this so-called δM-plot depends on whether the sample is ac-field or thermally demagnetised.     

Attainment and (sub)differentiability of the infimal convolution of a function and the square of the norm

Let X be a Banach space whose norm is simultaneously LUR and Gateaux (Fréchet) smooth. Under some assumptions, it is shown that the infimal convolution of a fairly general function on X and the square of the norm is generically strongly attained and hence is Gateaux (Fréchet) differentiable. This contains a result of S. Dutta on distance functions.     

Oxygen-permeable membranes based on partially B-site substituted BaFe1−yMyO3−δ (M=Cu or Ni)

We carried out the partial substitution of the B-site in BaFeO_3−δ perovskite with divalent cations to develop novel oxygen-permeable materials. We demonstrated that the partial substitution of Cu or Ni by more than 10% resulted in the stabilization of the cubic perovskite structure even at room temperature in a highly oxygen-permeable phase, as revealed by the X-ray diffraction (XRD) analysis. The Cu substitution was more effective for the stabilization, because the introduction of Cu in the lattice more effectively made the Goldschmidt tolerance factor (t) close to 1.0. Ni- and Cu-substituted BaFeO_3−δ membranes showed higher oxygen permeabilities than their parent BaFeO_3−δ membranes particularly at lower temperatures around 600-700 °C owing to the stabilization of the cubic phase. Among the fabricated membranes, a BaFe_0.85Cu_0.15O_3−δ membrane (1.0 mm thickness) showed the highest oxygen permeation flux (1.8 cm³ min⁻¹ cm⁻² at 930 °C) under an air/He gradient. The results indicated that Cu-substituted BaFeO_3-δ is promising as a material for Co-free membranes with high oxygen permeabilities.     

全能近似分析简介

根据无限的“无有终了”的事实，应当把无尽小数看作无穷数列简写，采用这种观点就可以得到实数的运算法则；如果用康托（Cantor，G）的“无限是现实的、完成了的、存在着的整体”的“实无限”观点就得不到这个法则．点是针对误差界的足够小，其中没有大小的点叫做理想点，有大小的点叫做近似点．理想点具有无法点出的性质．近似点的集合能够组成线段，但理想点的集合不能组成线段．绝对准确地讨论没有大小的理想瞬时上的速度没有实际意义，理想的瞬时速度依赖于近似瞬时的速度．对于点、线、面、实数、函数、导数、积分、积分变换、实数集等数学名词都需要提出近似、理想、全能近似三类技术术语，应用对立统一法则去阐述数学理论．     

Equimodular and linearity in modular spaces

In this paper, the concept of equimodular is introduced. It contains several generalizations of Mazur-Ulam's isometric theorem in modular spaces. Let X and Y be two real modular spaces and X with δ₁-midpoint shrinking whose modular ρ_X satisfies the Δ₂-condition. Assume that an operator T maps X onto Y in an δ₂-{t_i}-equimodular manner for all , where {t_i} is a null-sequence of nonnegative reals with the property that t₀=1, t₁?1/2, and t_i?t_i−1?2t_i for i?2. Then T is affine.