Effect of laser source nonlinearity on optical heterodyne interferometry

In this paper, an optical heterodyne interferometric detection model with a frequency-ramped laser diode (LD) has been analyzed. The effect of the nonlinearity of the LD source on the optical heterodyne interferometry has been investigated in two different ways, which are the power-distortion Fourier series analysis and the harmonic distortion analysis. The general formulation between the tangent of the tested phase and the interference fringe have been presented with the analysis of the beat signal in the frequency domain by each methodology. The numerical results of these formulations have been presented.     

Mössbauer Spectroscopic Studies of an Oxidized Ordinary Chondrite Fallen at Itawa-Bhopji,India

Mössbauer studies of the Itawa-Bhopji meteorite fallen on May 30, 2000 in Rajasthan, India, show that the main iron minerals in it are Fe–Ni (kamacite/taenite), troilite, olivine and pyroxene. These provide characteristic signatures of an ordinary chondrite. Mössbauer absorption areas corresponding to different phases favour its classification as L/LL-type ordinary chondrite. The iron in the olivine is unusually high and the metallic iron is quite low, showing that it has faced oxidizing conditions prior to fall.     

High-Pressure Mössbauer Measurements on Nanocrystalline Perovskite (La,Sr)(Mn,Fe)O3

We report here the Mössbauer measurements on nanocrystalline perovskite structured manganite La_0.8Sr_0.2Mn_0.8Fe_0.19 ⁵⁷Fe_0.01O₃ as a function of pressure up to 10 GPa at room temperature. The nanocrystalline sample, prepared by sol–gel technique found to have crystallite sizes of ∼138 ± 10 Å. Zero-field electrical resistivity measurements with temperature support the nanocrystalline nature. At ambient pressure, Fe³⁺ as well as Fe⁴⁺ ions are distributed in two different environments – Fe³⁺ in low symmetric site surrounded by Mn³⁺ ions only while Fe⁴⁺ in high symmetric site with at least one Mn³⁺ ion. Pressure seems to affect the higher symmetric site. A sudden increase in isomer shift at 0.52 GPa indicates the first order phase transition representing the transformation of Fe⁴⁺ to Fe³⁺. Another transition at 3.7 GPa, represents the presence of Fe³⁺ in single kind of environment. Pressure dependence of electrical resistivity measurements verifies the transitions attributing the first order transition to the cross over of localized-electron to band magnetism.     

TLC Determination of Strychnine and Brucine of Strychnos nux vomica in Ayurveda and Homeopathy Drugs

Strychnos nux vomica is an important plant source for drugs of ayurvedic and homeopathic system of medicine. In this paper a thin layer chromatographic (TLC) method has been developed for the quantitative estimation of the two major alkaloids strychnine and brucine in the plant fruit and in ayurvedic and homeopathic drugs. Chloroform–ethyl acetate–diethyl amine (0.5:8.5:1) as mobile phase gave clear separation with no interference between the bioactive markers. The R _f values for strychnine and brucine were 0.55 and 0.42. The TLC method was found to be precise, rugged, robust and accurate with recovery of strychnine in the range 93.11–99.82% and brucine 96.95–99.48%. The limit of detection (LOD) and limit of quantification (LOQ) for strychnine were 1.9 and 8.25 ng and for brucine 2.2 and 9.2 ng respectively.     

High-Performance Thin-Layer Chromatographic Analysis for the Simultaneous quantification of Gallic Acid,Vanillic Acid,Protocatechuic Acid,and Quercetin in the Methanolic Fraction of Limonia acidissima L. Fruits

JPC – Journal of Planar Chromatography – Modern TLC - A high-performance thin-layer chromatography (HPTLC) method for the simultaneous quantitative determination of gallic acid,...     

Intra-Specific Variation of Precocene I in the Wild Population of Ageratum conyzoides L. from the Western Himalayas

JPC – Journal of Planar Chromatography – Modern TLC -     

2D Zeolite Coatings: Langmuir–Schaefer Deposition of 3 nm Thick MFI Zeolite Nanosheets

Stable suspensions of zeolite nanosheets (3 nm thick MFI layers) were prepared in ethanol following acid treatment, which partially removed the associated organic structure‐directing agent. Nanosheets from these suspensions could then be dispersed at the air–water interface and transferred to silicon wafers using Langmuir–Schaefer deposition. Using layer‐by‐layer deposition, control on coating thickness was demonstrated. In‐plane X‐ray diffraction (XRD) revealed that the deposited nanosheets contract upon calcination similar to bulk MFI crystals. Different methods for secondary growth resulted in preferentially oriented thin films of MFI, which had sub‐12‐nm thickness in certain cases. Upon calcination, there was no contraction detectable by in‐plane XRD, indicating well‐intergrown MFI films that are strongly attached to the substrate.     

Linkage Isomerism Leading to Contrasting Carboboration Chemistry: Access to Three Constitutional Isomers of a Borylated Phosphaalkene

We describe the reactivity of two linkage isomers of a boryl-phosphaethynolate, [B]OCP and [B]PCO (where [B]=N,N’-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl), towards tris- (pentafluorophenyl)borane (BCF). These reactions afforded three constitutional isomers all of which contain a phosphaalkene core. [B]OCP reacts with BCF through a 1,2 carboboration reaction to afford a novel phosphaalkene, E-[B]O{(C₆F₅)₂B}C=P(C₆F₅), which subsequently undergoes a rearrangement process involving migration of both the boryloxy and pentafluorophenyl substituents to afford Z-{(C₆F₅)₂B}(C₆F₅)C=PO[B]. By contrast, [B]PCO undergoes a 1,3-carboboration process accompanied by migration of the N,N’-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaboryl to the carbon centre.     

Synthesis and Mesomorphic Characterisation of Chiral Homologues

Abstract

Chiral liquid crystals have attracted considerable interest as they exhibit a good variety of modulated phases. We have synthesised a homologous series viz., 4-(4^!-n-alkoxy benzoyloxy) benzylidene-4^!!?1-(s)-methyl propoxy anilines, incorporating a terminal chiral centre, inorder to obtain better understanding of the relationship between molecular structure and appearance of SmC* phase in the molecules. It is observed that, in the present series the lower members upto butyl are pure nematogens, while pentyl to hexadecyl derivatives exhibit classical smectic as well as nematic mesophases. An additional smectic C* phase is observed in the middle octyl to dodecyl homologues. The homologues have been characterised by IR, NMR and DSC. Their mesomorphic properties have been compared with structurally related homologous series.