Insecticidal Activity of Extracts,Fractions, and Pure Molecules of Cissampelos pareira Linnaeus against Aphid,Aphis craccivora Koch

Aphis craccivora Koch is a polyphagous and major pest of leguminous crops causing significant damage by reducing the yield. Repeated application of synthetic insecticides for the control of aphids has led to development of resistance. Therefore, the present study aimed to screen the insecticidal activity of root/stem extracts/fractions, and pure molecules from Cissampelos pareira Linnaeus against A. craccivora for identification of lead(s). Among root extract/fractions, the n-hexane fraction was found most effective (LC₅₀ = 1828.19 mg/L) against A. craccivora, followed by parent extract (LC₅₀ = 2211.54 mg/L). Among stem extract/fractions, the n-hexane fraction (LC₅₀ = 1246.92 mg/L) was more effective than the water and n-butanol fractions. Based on GC and GC-MS analysis, among different compounds identified in the n-hexane fraction of root and stem, ethyl palmitate (known to possess insecticidal activity) was present in the highest concentration (24.94 to 52.95%) in both the fractions. Among pure molecules, pareirarineformate was found most effective (LC₅₀ = 1491.93 mg/L) against A. craccivora, followed by cissamine (LC₅₀ = 1556.31 mg/L). Parent extract and fractions of C. pareira possess promising activity against aphid. Further, field bio-efficacy studies are necessary to validate the current findings for the development of botanical formulation.     

Reconstructing the differentiation niche of embryonic stem cells using biomaterials

The biochemical cues and topographical architecture of the extracellular environment extensively influence ES cell fate. The microenvironment surrounding the developing embryo presents these instructive cues in a complex and interactive manner in order to guide cell fate decisions. Current stem cell research aims to reconstruct this multifaceted embryonic niche to recapitulate development in vitro. This review focuses on 2D and 3D differentiation niches created from natural and synthetic biomaterials to guide the differentiation of ES cells toward specific lineages. Biomaterials engineered to present specific physical constraints are also reviewed for their role in differentiation.     

ESR study of exchange coupled pairs in copper diethyldithiocarbamate

ESR investigations on exchange coupled pairs of Cu ions in single crystals of Cu(dtc)₂, isomorphously diluted with the corresponding diamagnetic zinc salt, are reported. The spin Hamiltonian parameters for the coupled species (S=1) are:g _‖=2.1025,g ₊=2.031,A=75.1×10⁻⁴ cm⁻¹,B=14.8×10⁻⁴,D=276.0×10⁻⁴ cm⁻¹ andE=46.7×10⁻⁴ cm⁻¹. While theg andA tensors show tetragonal symmetry, the zeor-field splitting tensor is rhombic and has principal axes different from those of theg andA tensors. Intensity measurements made down to 4.2 K indicate that the exchange is ferromagnetic with |FFF| ∼ 10 cm⁻¹. Direct dipole-dipole interaction appears to be the major contribution to the zero-field splitting. A calculation on the distributed point dipole model shows that dipolar interaction is considerably modified by the high covalency of the Cu-S bond and accounts for the rhombic nature of the tensor. The possible exchange mechanisms in Cu(dtc)₂—direct exchange and superexchange through the bridging sulphurs—are discussed.     

Unsteady Natural Convection Flow in a Square Cavity Filled with a Porous Medium Due to Impulsive Change in Wall Temperature

Unsteady natural convection flow in a two-dimensional square cavity filled with a porous material has been studied. The flow is initially steady where the left-hand vertical wall has temperature T _h and the right-hand vertical wall is maintained at temperature T _c (T _h > T _c) and the horizontal walls are insulated. At time t > 0, the left-hand vertical wall temperature is suddenly raised to which introduces unsteadiness in the flow field. The partial differential equations governing the unsteady natural convection flow have been solved numerically using a finite control volume method. The computation has been carried out until the final steady state is reached. It is found that the average Nusselt number attains a minimum during the transient period and that the time required to reach the final steady state is longer for low Rayleigh number and shorter for high Rayleigh number.     

Adsorption of51Cr(VI) on manganese dioxide from aqueous solution

Sorption of⁵¹Cr(VI) by MnO₂ has been studied as a function of pH and ionic concentration in the presence of certain added cations and anions. The findings are explained in the light of deprotonation/hydroxyl ion association reaction on oxide surface and its subsequent interaction with the tracer. Infrared spectroscopy has shown the chemical interaction of Cr(VI) on the surface of MnO₂. The influence of certain interfering ions has been shown on the sorption of⁵¹Cr(VI) on MnO₂ surface. An attempt has been made to concentrate traces of⁵¹Cr under optimum experimental conditions. The experimental observation shows that the activity sorbed under specified conditions can be recovered appreciably by leaching the pre-adsorbed carrier.     

Synthesis of Pyrazole Derivatives Possessing Anticancer Activity: Current Status

Pyrazole is a versatile lead compound to design potent bioactive molecules for drug discovery and development, particularly in cancer therapy. The aim of this review is to present the most recent deeds in the field of synthetic route made for functionalized pyrazole derivatives active against cell proliferation disease. The review article covers the synthesis of 1H-pyrazole, synthesis of N-substituted pyrazoles, synthesis of pyrazolopyrazoles, and synthesis of pyrazoles fused with a naturally occurring moiety. Some of these reported compounds have passed the preclinical or initial-phase clinical trials for their anticancer activity.     

Efficient syntheses of novel indeno[1,2-b]chromenone derivatives via hetero-Diels-Alder reactions of 2-(arylmethylene)-1H-indene-1,3(2H)-diones with enaminones

Efficient syntheses of novel 10-aryl-5a-(arylamino)-9-hydroxy-5a,6,7,8-tetrahydroindeno[1,2-b]chromen-11(10H)-one derivatives has been reported by [4+2] cycloaddition reactions of electron-deficient 2-(arylmethylene)-1H-indene-1,3(2H)-dione heterodienes with electron-rich enaminones in [bmim]BF₄ at 80?°C and in acetic acid at 80?°C. Dimedone/cyclohexane-1,3-dione enaminones have been used as dienophiles in Inverse Electron Demand hetero-Diels-Alder reactions. The products were obtained in high yields by a simple work up.     

Microwave‐Assisted Expedite Synthesis of 2‐Phenylimidazo[1,2‐a]pyridylquinoxalin‐2(1H)‐ones

An efficient methodology has been developed for the synthesis of quinoxalin‐2(1H)‐one derivatives of 2‐phenylimidazo[1,2‐a]pyridines by microwave‐irradiated Hinsberg heterocyclization between 2‐phenylimidazo[1,2‐a]pyridine‐3‐glyoxalates and o‐phenylenediamine using either montmorillonite K‐10 or Yb(OTf)₃ as catalysts. Montmorillonite K‐10 was proven to be an efficient catalyst for the heterocyclization reaction between sterically hindered glyoxalate and o‐phenylenediamine only under microwave conditions. The use of Yb(OTf)₃/tetrahydrofuran was also found to be an effective catalyst for the above chemical transformation among a series of Lewis acids screened under microwave conditions; however, comparatively lesser yields were obtained as compared with the use of montmorillonite K‐10.     

Unsteady free convection flow under the influence of a magnetic field

Summary The unsteady free convection boundary layer at the stagnation point of a two-dimensional body and an axisymmetric body with prescribed surface heat flux or temperature has been studied. The magnetic field is applied parallel to the surface and the effect of induced magnetic field has been considered. It is found that for certain powerlaw distribution of surface heat flux or temperature and magnetic field with time, the governing boundary layer equations admit a self-similar solution locally. The resulting nonlinear ordinary differential equations have been solved using a finite element method and a shooting method with Newton's corrections for missing initial conditions. The results show that the skin friction and heat transfer coefficients, andx-component of the induced magnetic field on the surface increase with the applied magnetic field. In general, the skin friction, heat transfer andx-component of the induced magnetic field for axisymmetric case are more than those of the two-dimensional case. Also they change more when the surface heat flux or temperature decreases with time than when it increases with time. The skin friction, heat transfer andx-component of the induced magnetic field are significantly affected by the magnetic Prandtl number and they increase as the magnetic Prandtl number decreases. The skin friction andx-component of the magnetic field increase with the dissipation parameter, but heat transfer decreases.

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Instationäre freie Konvektionsströmung unter dem Einfluß eines magnetischen Feldes

Übersicht Untersucht wurde die instationäre freie Konvektionsgrenzschicht am Ruhepunkt eines zweidimensionalen und achsensymmetrischen umströmten Körpers bei vorgegebenem Wärmefluß bzw. bei vorgegebener Temperatur an der Oberfläche. Das magnetische Feld wird parallel zur Oberfläche angelegt, und der Einfluß des induzierten magnetischen Feldes wurde berücksichtigt. Es stellt sich heraus, daß bei bestimmter, zeitlicher Potenzgesetzverteilung des Wärmeflusses bzw. der Temperatur und des magnetischen Feldes an der Oberfläche die geltenden Grenzschichtgleichungen örtlich eine selbstähnliche Lösung erlauben. Die sich ergebenden nichtlinearen gewöhnlichen Differentialgleichungen wurden mittels einer Finite-Element-Methode und einer Shooting-Methode mit Newtonschen Korrekturen für fehlende Anfangsbedingungen gelöst. Die Ergebnisse zeigen, daß die Oberflächenreibung und die Wärmeübergangskoeffizienten sowie diex-Komponente des induzierten magnetischen Feldes an der Oberfläche mit dem angelegten magnetischen Feld zunehmen. Im allgemeinen sind die Oberflächenreibung, der Wärmeübergang und diex-Komponente des induzierten magnetischen Feldes im achsensymmetrischen Fall größer als die entsprechenden Werte im zweidimensionalen Fall. Außerdem verändern sich diese Werte beim zeitlichen Abfallen des Wärmeflusses an der Oberfläche bzw. der Temperatur in höherem Maße als bei der zeitlichen Zunahme dieser Werte. Die Oberflächenreibung, der Wärmeübergang und diex-Komponente des induzierten magnetischen Feldes werden durch die magnetische Prandtl-Zahl erheblich beeinflußt; sie nehmen mit abfallender magnetischer Prandtl-Zahl zu. Die Oberflächenreibung und diex-Komponente des magnetischen Feldes nehmen mit dem Wärmeableitungsparameter zu, der Wärmeübergang jedoch fällt ab.

     

Simultaneous heat and mass transfer under unsteady mixed convection along a vertical slender cylinder embedded in a porous medium

Unsteady laminar mixed convection flow (combined free and forced convection flow) along a vertical slender cylinder embedded in a porous medium under the combined buoyancy effect of thermal and species diffusion has been studied. The effect of the permeability of the medium as well as the magnetic field has been included in the analysis. The partial differential equations with three independent variables governing the flow have been solved numerically using a implicit finite difference scheme in combination with the quasilinearization technique. Computations have been carried out for accelerating, decelerating and oscillatory free stream velocity distributions. The effects of the permeability of the medium, buoyancy forces, transverse curvature and magnetic field on skin friction, heat transfer and mass transfer have been studied. It is found that the effect of free stream velocity distribution is more pronounced on the skin friction than on the heat and mass transfer. The permeability and magnetic parameters increase the skin friction, but reduce the heat and mass transfer. The skin friction, heat transfer and mass transfer are enhanced due to the buoyancy forces and curvature parameter. The heat transfer is strongly dependent on the viscous dissipation parameter and the Prandtl number, and the mass transfer on the Schmidt number.