Vaporization thermodynamics of thorium tetrafluoride

The thermal decomposition kinetics of Pr₂(SO₄)₃ to Pr₂O₂SO₄ have been studied by isothermal weight change determination. The reaction was found to obey a linear law up to α = 0.5; beyond α = 0.5 it could be described as a phase-boundary controlled process. A dependence of the activation energy upon the sample weight was observed. The changes in surface area and density which occur during the decomposition are also given.     

Non Existence of Triangle Free Quasi-symmetric Designs

The following two results are proved. Let D be a triangle free quasi-symmetric design with k=2y−x and x≥ 1 then D is a trivial design with v=5 and k=3. There do no exist triangle free quasi-symmetric designs with x≥ 1 and λ=y or λ=y−1.Communicated by: P. Wild     

The bipolar decomposition

It is shown that every nonsingular square complex matrix Z   can be factored as Z=e^Le^iTe^iKe^S$Z=e^L{e}^{iT}{e}^{iK}{e}^S$, where S and T are real symmetric matrices, and K and L are real skew-symmetric matrices. New proofs are given for some related decomposition theorems for unitary and positive definite matrices.     

Positive Definite Functions and Operator Inequalities

We construct several examples of positive definite functions,and use the positive definite matrices arising from them toderive several inequalities for norms of operators. 1991 MathematicsSubject Classification 42A82, 47A63, 15A45, 15A60.     

Viscosity Approximation Methods for Generalized Multi-Valued Nonexpansive Mappings with Applications

Abstract

In this article, we study viscosity approximation methods for generalized multi-valued nonexpansive mappings and we present some new results related to strong convergence, variational inequality, convex optimization, split and common split feasibility problems (SFPs). Some numerical computations are also presented to illustrate our results.     

Quasi‐symmetric designs with fixed difference of block intersection numbers

The following results for proper quasi‐symmetric designs with non‐zero intersection numbers x,y and λ > 1 are proved.

• (1) Let D be a quasi‐symmetric design with z = y ? x and v ≥ 2k. If x ≥ 1 + z + z³ then λ < x + 1 + z + z³.
• (2) Let D be a quasi‐symmetric design with intersection numbers x, y and y ? x = 1. Then D is a design with parameters v = (1 + m) (2 + m)/2, b = (2 + m) (3 + m)/2, r = m + 3, k = m + 1, λ = 2, x = 1, y = 2 and m = 2,3,… or complement of one of these design or D is a design with parameters v = 5, b = 10, r = 6, k = 3, λ = 3, and x = 1, y = 2.
• (3) Let D be a triangle free quasi‐symmetric design with z = y ? x and v ≥ 2k, then x ≤ z + z².
• (4) For fixed z ≥ 1 there exist finitely many triangle free quasi‐symmetric designs non‐zero intersection numbers x, y = x + z.
• (5) There do not exist triangle free quasi‐symmetric designs with non‐zero intersection numbers x, y = x + 2.

© 2006 Wiley Periodicals, Inc. J Combin Designs 15: 49–60, 2007     

An efficient protocol for the synthesis of 2-amino-4,6-diphenylpyridine-3-carbonitrile using ionic liquid ethylammonium nitrate

Chalcones on condensation with malononitrile and ammonium acetate in the presence of ionic liquid ethylammonium nitrate affords the corresponding 2-amino-4, 6-diphenylpyridine-3-carbonitrile in excellent yield. The ionic liquid is recycled and reused several times.     

Determination of mimosine by a sensitive indirect spectrophotometric method

A simple and sensitive indirect spectrophotometric method is described for the determination of mimosine based on its reaction with diazotized sulfanilamide (DZSAM). DZSAM couples with N-(1-naphthyl)ethylenediamine (NEDA) forming a pink colored azodye, absorbing maximally at 540 nm (ε_max=27 mM⁻¹ cm⁻¹). In the present method, mimosine was first reacted with known excess of DZSAM and the unreacted DZSAM was determined by coupling with NEDA. The reaction of mimosine with DZSAM proceeded optimally at neutral pH. The decrease in absorbance of the DZSAM-NEDA-coupled product obeyed Beer’s law in the concentration range of 0.005-0.15 μg ml⁻¹ of mimosine. The present method was applied to estimate mimosine in plant extracts containing lesser than 0.05 μg ml⁻¹ with recovery at 99±0.41%. The method described is superior to other reported methods in terms of ease of adaptability and sensitivity.     

Validation of an LC/MS method for the determination of gemfibrozil in human plasma and its application to a pharmacokinetic study

Gemfibrozil, a fibric acid hypolipidemic agent, is increasingly being used in clinical drug–drug interaction studies as an inhibitor of drug metabolizing enzymes and drug transporters. The validation of a fast, accurate and precise LC/MS method is described for the quantitative determination of gemfibrozil in an EDTA‐anticoagulated human plasma matrix. Briefly, gemfibrozil was extracted from human plasma by an acetonitrile protein precipitation method. The assay was reproducible with intra‐assay precision between 1.6 and 10.7%, and inter‐assay precision ranging from 4.4 to 7.8%. The assay also showed good accuracy, with intra‐assay concentrations within 85.6–108.7% of the expected value, and inter‐assay concentrations within 89.4–104.0% of the expected value. The linear concentration range was between 0.5 and 50 µg/mL with a lower limit of quantitation of 0.5 µg/mL when 125 µL of plasma were extracted. This LC/MS method yielded a quick, simple and reliable protocol for determining gemfibrozil concentrations in plasma and is applicable to clinical pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd.