Syntheses and Investigation of Some New Polyarylates and Copolyarylates. Part I

By the interfacial condensation of acid chlorides I, II, and III, respectively, with bifunctional phenols (IV-X), soluble or mold-able thermostable polyarylates were obtained. Similarly, copolyarylates were prepared from a mixture of the acid chlorides I + II or I + III. With bisphenol-A (VIII), soluble polymers are usually obtained. Methylene dichloride and/or carbon tetra-chloride-water systems were the best media for interfacial condensations, and the polymers formed showed the highest reduced viscosity values.

Polyester films are useful in many industrial applications because of their broad range of mechanical, optical, and electrical properties. The aromatic polyesters‐polyarylates-dominate the field of industrial polyester films [1].

Polyarylates prepared from dihydric phenols and purely aromatic dicarboxylic acid chlorides are highly heat resistant materials [2], but they are insoluble and nonmoldable [3]. However, by the introduction of ether linkages in the aromatic dicarboxylic acid moiety, soluble and/or moldable polyamides were obtained [4].     

Finite difference scheme for variational inequalities

In this paper, we show that a class of variational inequalities related with odd-order obstacle problems can be characterized by a system of differential equations, which are solved using the finite difference scheme. The variational inequality formulation is used to discuss the uniqueness and existence of the solution of the obstacle problems.     

粉粒体两相流的电容层析成象测量

粉粒体系统中的固相浓度分布的在线测量是十分困难的问题．电容层析成象技术是一种近年来发展起来的非侵入式快速浓度场测量技术．它不干扰流场，不受流动中颗粒浓度、加速度、不透明等因素的制约．本文讨论其测量原理、应用、近期进展、存在的主要问题及其解决的对策．     

ac Conductivity of mixed spinel NiAl0.7Cr0.7Fe0.6O4

ac Conductivity measurements are carried out across the metal to insulator transition in NiAl_0.7Cr_0.7Fe_0.6O₄. The low frequency data is analyzed using Summerfield scaling theory for hopping conductivity. The exponent of the scaling behavior has significantly different values in the conducting and insulating regimes. The hopping frequency and the zero frequency conductivity are found to increase with temperature, slowly in the metallic regime and rapidly in the insulating regime.     

Synthesis,reactions, and antimicrobial activity of some novel fused thiazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-5<Emphasis Type="Italic">H</Emphasis>-indeno[1,2-<Emphasis Type="Italic">d</Emphasis>]pyrimidine derivatives

Series of novel substituted thioxopyrimidine and thiazolo[3,2-a]pyrimidine compounds that combine various heteroaryl rings have been synthesized via Biginelli one-pot three-component reaction and elucidated with chemical and spectral analysis. Several products were tested for their antimicrobial properties.     

Spectrophotometric and spectrofluorimetric methods for the determination of tranexamic acid in pharmaceutical formulation

Two simple and sensitive spectrophotometric and fluorimetric methods for the determination of tranexamic acid in tablets are developed. The methods are based on condensation the primary amino group of tranexamic acid with acetyl acetone and formaldehyde producing a yellow coloured product, which is measured spectrophotometrically at 335 nm or fluorimetrically at 480 nm the colour was stable for at least 1 h. Beer's law was valid within a concentration rang of 0.05-2.0 microg ml-1 spectrophotometrically and 0.05-0.25 microg ml-1 fluorimetrically. All the variables were studied to optimize the reaction conditions. No interference was observed in the presence of common pharmaceutical excipints. The validity of both methods was tested by analyzing tranexamic acid in its pharmaceutical preparations. Good recoveries were obtained and the results were comparable with those obtained by standard method.     

Formulation of Quaternized Aminated Chitosan Nanoparticles for Efficient Encapsulation and Slow Release of Curcumin

An effective drug nanocarrier was developed on the basis of a quaternized aminated chitosan (Q-AmCs) derivative for the efficient encapsulation and slow release of the curcumin (Cur)-drug. A simple ionic gelation method was conducted to formulate Q-AmCs nanoparticles (NPs), using different ratios of sodium tripolyphosphate (TPP) as an ionic crosslinker. Various characterization tools were employed to investigate the structure, surface morphology, and thermal properties of the formulated nanoparticles. The formulated Q-AmCs NPs displayed a smaller particle size of 162 ± 9.10 nm, and higher surface positive charges, with a maximum potential of +48.3 mV, compared to native aminated chitosan (AmCs) NPs (231 ± 7.14 nm, +32.8 mV). The Cur-drug encapsulation efficiency was greatly improved and reached a maximum value of 94.4 ± 0.91%, compared to 75.0 ± 1.13% for AmCs NPs. Moreover, the in vitro Cur-release profile was investigated under the conditions of simulated gastric fluid [SGF; pH 1.2] and simulated colon fluid [SCF; pH 7.4]. For Q-AmCs NPs, the Cur-release rate was meaningfully decreased, and recorded a cumulative release value of 54.0% at pH 7.4, compared to 73.0% for AmCs NPs. The formulated nanoparticles exhibited acceptable biocompatibility and biodegradability. These findings emphasize that Q-AmCs NPs have an outstanding potential for the delivery and slow release of anticancer drugs.     

A variant of Hardy's and Miyachi's theorems for the Bessel–Struve transform

In this paper, we establish new versions of Hardy's and Miyachi's theorems for the Bessel–Struve transform.     

Synthesis and characterization of some novel 1,3-diaryl pyrazole bearing 2-oxopyridine-3,5-dicarbonitrile derivatives

Russian Journal of General Chemistry - A series of new 1-{[1-(3-chlorophenyl)-3-(4-methoxyphenyl)-1H-pyrazol-4-yl]methyleneamino}-6-amino-1,2-dihydro-4-(substitutedphenyl)-2-oxopyridine-3,5-di...     

Krull Dimension in Power Series Ring Over an Almost Pseudo-Valuation Domain

Let R be an integral domain. We say that R is a star-domain if R has at least a height one prime ideal and if for each height one prime ideal P of R, R satisfies the acc on P-principal ideals (i.e., ideals of the form aP, a ∈ R). We prove that if R is an APVD with nonzero finite Krull dimension, then the power series ring R[[X]] has finite Krull dimension if and only if R is a residually star-domain (i.e., for each nonmaximal prime ideal P of R, R/P is a star-domain) if and only if R[[X]] is catenarian.