New chromone derivative from Evolvulus alsinoides Linn. aerial parts

Phytochemical investigation of the aerial parts of Evolvulus alsinoides Linn. (Convolvulacae) resulted in the isolation of a new chromone characterized as 6-hydroxy-5-nonadecanoxychroman-2-one (alsinoideschromone) along with hexatriacontane, octyl octadec-9-enoate, nonyl octadec-9-enoate, dodecanyl-octadec-9,12-dienoate, tetracosanyl hexadec-9-enoate, heptacosan-14-β-ol, stigmast-5, 22-dien-3β-ol and stigmata-5-en-3β-ol. The structure of all these phytoconstituents have been established on the basis of spectral data analysis and chemical reactions.     

A diagonal splitting method for solving semidiscretized parabolic partial differential equations

In this work, a diagonal splitting idea is presented for solving linear systems of ordinary differential equations. The resulting methods are specially efficient for solving systems which have arisen from semidiscretization of parabolic partial differential equations (PDEs). Unconditional stability of methods for heat equation and advection–diffusion equation is shown in maximum norm. Generalization of the methods in higher dimensions is discussed. Some illustrative examples are presented to show efficiency of the new methods.     

A facile synthesis of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl)acetamidines

<正>A series of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl) acetamidines was synthesized by reacting ethyl(1H)-N-(4-oxo-2-phenylquinazolin-3(4H)-y1)ethanimidoate(2) and suitable reactive aromatic amines.Structures' determination of the synthesized compounds was carried out using spectroscopic techniques including IR,~1H NMR,and mass spectrometry. Structural effects on reactivity were also studied.     

New ceramides from Platytaenia multicaule

Phytochemical investigation of Platytaenia multicaule resulted in the isolation of two new ceramides, N-triacontylpentadecanamide and 1,3,4-trihydroxy-2,dodecanoylamino-(24E)-unacotenene, along with two known compounds, beta-sitosterol and beta-sitosterol glycoside. The structure elucidation of the isolated compounds was based primarily on 1D and 2D NMR analyses, including COSY, NOESY, HMQC, and HMBC correlations.     

The effect of temperature and slice thickness on drying kinetics tomato in the infrared dryer

In this study thin layer drying of tomato slices were investigated in the infrared dryer. Drying rate increased with increasing temperature and reduction thickness and thus reduced the drying time. The effective diffusivity increased with increasing temperature and with increasing thickness of the samples. The effective diffusivity values changed from 1.094 × 10^?9 to 4.468 × 10^?9 m²/s and for activation energy varied from 110 to 120 kJ/mol. The best model for drying process of tomato slices was Midilli model.     

Understanding the Influence of Donor-Acceptor Diazo Compounds on the Catalyst Efficiency of B(C6F5)3 Towards Carbene Formation

Diazo compounds have been largely used as carbene precursors for carbene transfer reactions in a variety of functionalization reactions. However, the ease of carbene generation from the corresponding diazo compounds depends upon the electron donating/withdrawing substituents either side of the diazo functionality. These groups strongly impact the ease of N₂ release. Recently, tris(pentafluorophenyl)borane [B(C₆F₅)₃] has been shown to be an alternative transition metal-free catalyst for carbene transfer reactions. Herein, a density functional theory (DFT) study on the generation of carbene species from α-aryl α-diazocarbonyl compounds using catalytic amounts of B(C₆F₅)₃ is reported. The significant finding is that the efficiency of the catalyst depends directly on the nature of the substituents on both the aryl ring and the carbonyl group of the substrate. In some cases, the boron catalyst has negligible effect on the ease of the carbene formation, while in other cases there is a dramatic reduction in the activation energy of the reaction. This direct dependence is not commonly observed in catalysis and this finding opens the way for intelligent design of this and other similar catalytic reactions.     

Synthesis and reactions of functionalized spirocyclopropanes by cyclization of dilithiated β-ketosulfones, α-cyanoacetone and diethyl 2-oxopropylphosphonate with 1,1-diacetylcyclopropane

The cyclization of β-ketosulfone, β-ketonitrile and β-ketophosphonate dianions with 1,1-diacetylcyclopropane afforded 1-hydroxyspiro[5.2]cyclooct-4-en-3-ones, which were transformed, by reaction with tetrabutylammonium halides, into functionalized phenols containing a remote halide function.     

Gnapholide: a new guaiac-dimer from Pulicaria gnaphalodes (Asteraceae)

The ethyl acetate soluble part of the chloroform extract of Pulicaria gnaphalodes belonging to the family Asteraceae afforded a new sesquiterpene-dimer of guaiane class named as gnapholide and anabsinthin of the same skeleton. The structures of both the compounds were elucidated with the aid of spectroscopic techniques including 2D NMR.     

Correlation of plasma electron temperature with neutron emission ina low-energy plasma focus

Correlation of neutron emission with plasma electron temperature in a low-energy (2.3 kJ) plasma focus is investigated. To determine the plasma temperature by continuum X-ray analysis, cobalt is selected as the filter, which discriminates the line radiation from the background impurities like carbon, nitrogen, and oxygen, or the copper of which plasma focus electrodes are made. For a pressure range of high neutron emission (1-4 mbar), the neutron yield is found to correlate with the plasma temperature. The highest temperature recorded is 5 keV at 2.5 mbar, the filling pressure for the highest neutron emission in this device     

Ring-opening reactions of oxetanes: A review of methodology development and synthetic applications

Ring-opening reactions of oxetanes yield important functionalized products depending upon the nature of nucleophiles as well as substitution pattern on the oxetane ring. Ring opening of oxetanes can be carried out under a variety of reaction conditions. In this review article, an up-to-date overview of major synthetic methodologies involved in the ring opening of oxetanes as well as their synthetic applications has been presented.