Electronic modulation of microwave-excited electrodeless discharge lamps for use in atomic-fluorescence spectrometry

Electronic modulation of electrodeless discharge lamps has been investigated with respect to frequency of operation and modulation waveform. The optimal frequency of operation was found to be ca. 20,000 Hz, using a square waveform, and modulation was best achieved by adding the modulation waveform to the reference of the stabilizing element in the microwave power supply. Optimal operating conditions have been established for d.c. and a.c. modes of operation for several sources.     

Studies in atomic-fluorescence spectroscopy--VIII. Atomic fluorescence and atomic absorption of thallium and mercury with electrodeless discharge tubes as sources

Atomic-fluorescence measurements, with microwave-excited electrodeless discharge tubes as sources of excitation, are described for thallium and mercury. The limits of detection by atomic fluorescence are 0.12 ppm for thallium and 0.08 ppm for mercury; the corresponding limits by atomic absorption (using the same instrument and source) are 6 and 10 times as great. The preparation, operation and spectral characteristics of thallium and mercury discharge tubes are described and comparisons are made with a thallium hollow cathode lamp and thallium and mercury spectral discharge lamps.     

Inorganic polarography in organic solvents-IV: polarography of metal oxinate complexes in various solvents

The polarography of 24 metal oxinate complexes extracted into chloroform, IBMK, and ethyl acetate has been investigated, a methanolic solution of lithium chloride being used as base electrolyte. Only 15 complexes gave rise to reduction waves, and interference-free determinations have been developed for indium and thallium(III) in chloroform, and for bismuth, molybdenum and uranium in IBMK. The use of ethyl acetate offered no special advantages, and was the least selective of the three solvents used.     

FT-IR study of the effect of zinc exposure on the biochemical contents of the muscle of Labeo rohita

Heavy metal pollution is a major environmental problem in the modern world due to increasing human activities. Zinc is an essential element involved in a wide variety of cellular processes. However, it becomes toxic when elevated concentrations are introduced into the environment. The goal of the present study is to investigate the effect of zinc exposure on the biochemical contents of the muscle tissues of freshwater species Labeo rohita using Fourier transform infrared (FT-IR) spectroscopy. Since the muscle constitutes the greatest mass of the fish that is consumed, the present study has paid particular attention to muscle component. The result reveals that the zinc exposure causes significant changes in the biochemical contents of the L. rohita muscle tissues. In addition, it causes an alteration in the protein secondary structures by decreasing the α-helix and increasing the β-sheet contents of muscle tissues. Further, it has been observed that the administration of chelating agent D-penicillamine improves the protein and lipid contents in the muscle tissues compared to zinc exposed tissues. This result shows that D-penicillamine is the effective chelator of zinc in reducing the body burden of L. rohita fingerlings.     

The observation of a superdeformed structure in82Y

The⁵⁸Ni(³⁰Si,αpn)⁸²Y reaction at a beam energy of 134 MeV was used to populate the odd-odd nucleus⁸²Y and coincidentγ rays depopulating high spin states in the evaporation residues were detected with the EUROGAM Phase 2 array. A superdeformed structure has been observed with an intensity of 1.5±0.5%. The cascade of 9 coincidentγ rays has consecutive energy spacing of ～160 keV. This corresponds to a dynamic moment of inertia which is almost constant at approx mately 25h ² MeV^?1. The band is interpreted as a signature=0, negative parity SD band with aπ5¹ V5² intrinsic intruder configuration.     

Some Detection Limits in Atomic Fluorescence Spectroscopy with Micro Wave Excited Elsctrodeless Discharge Tubes as Excitation Sources

Abstract

For a given population of atoms in any atom-reservoir of low background, the sensitivity of atomic fluorescence measurements is inherently greater than that of atomic absorption because of the benefits which accrue from signal amplification and from the proportional relationship which exists between signal strength and the intensity of the source of excitation in fluorescence studies.     

The Application of Photon Counting as a Detection System in Atomic Fluorescence and Emission Spectrometry

Despite the profusion of literature associated with analytical atomic spectrometric techniques, very little has been reported concerning the development of detector systems. This is particularly surprising in view of the current trend in atomic spectrometry towards the use of non-flame atom reservoirs. These devices frequently produce weak transient signals and dc level detector systems designed for steady state measurements are in consequence often unsatisfactory. High speed recorders may be used with success providing the total response time of the various electronic components is comparable with or preferably less than that of the signal duration and only in such instances will precise measurement of the signal be achieved (1,2). The use of absolute integration techniques are obvious for this type of measurement, although their application has not been particularly forthcoming to date. Photon counting would seem to have many advantages for such purposes, although with the exception of the more general studies of Morton (3) and Malmstadt and co-workers (4) it has received so far little consideration. Indeed its use as a detection system in analytical atomic fluorescence and emission spectrometry has yet to be reported.     

Synthesis of gold nanoparticles using herbal Acorus calamus rhizome extract and coating on cotton fabric for antibacterial and UV blocking applications

Gold nanoparticles (AuNPs) have been synthesized by greener method using chloroauric acid as precursor and extract of Acorus calamus rhizome as reducing agent. Formation of AuNP was confirmed by the presence of Surface Plasmon Resonance (SPR) peak in UV–Visible spectral analysis. XRD and FT-IR spectral analyses were performed for characterization. SEM images show spherical morphology and HR-TEM images reveal nanosize of AuNPs. The AuNPs were then coated on cotton fabric by pad-dry-cure method and characterized by SEM with EDAX technique. The results reveal the deposition of AuNPs on the surface of cotton fabric. Uncoated cotton, neat extract coated cotton and extract containing AuNPs coated cotton fabrics were then tested for antibacterial activity against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacterial strains by AATCC 100 test method. It showed that the extract containing AuNPs coated cotton fabric had higher antibacterial activity than other test samples against E. coli. UV-DRS analysis performed on extract containing AuNPs coated cotton fabric showed improved UV-blocking property than uncoated cotton fabric and neat extract coated cotton fabric.     

Bayesian stratified random sampling using auxiliary information

Summary Smith (1976,J. R. Statist. Soc., A,139, 183–204) has argued that survey statisticians should attempt to model finite population structures in the same way that statisticians in other disciplines have to provide models of finite or infinite populations. Following this argument, we suggest in this paper that an obvious model for a stratified population when auxiliary information regarding variate values is available, is the one way analysis of covariance model with unequal variances and we consider the problem of estimating the finite population mean. Finally a possible extension of this result is discussed.