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Abstract  

Fast neutron activation analysis has been applied to the direct determination of oxygen in coal conversion liquids. The detection system consists of two solid 7.6 cm×7.6 cm NaI(T1) detectors connected to a summing amplifier and mounted at 180° with respect to a uniaxially rotated sample container. Differences have been observed in the gamma-ray self-absorption for the low average atomic number organic matrix in coal liquids as compared to the higher average atomic number standards such as USGS Standard Rock BCR-1 and NBS Standard Reference Mateiral 136b, K2Cr2O7, which have commonly been used for oxygen determinations in silicate rocks. In order to minimize problems associated with self-absorption and variable irradiation and counting geometries, a set of organic liquids was selected and evaluated for use as oxygen standards in the analysis of coal-derived liquids. The standard liquids were selected using criteria of high boiling point, well-defined stoichiometry, high purity, non-hygroscopic nature and simple C−H−O elemental composition. The final set of liquid standards is shown to yield an experimental oxygen—stoichiometric oxygen correlation coefficient of 0.9995 with an intercept at the origin, for liquids with oxygen contents from 3.55 to 49.94%. Dilutions of standards from the set with n-hexane permit extension of the range to lower oxygen contents.

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, I.R. Epstein , and T. Kowalska . In-Vitro Chiral Conversion, Phase Separation and Wave Propagation in Aged Profen Solutions . J. Liq. Chromatogr. Related Technol. (submitted for publication). [11

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Abstract  

A simple internal conversion electron spectroscopical method was coupled with RNAA. High energy internal conversion electrons were measured at room temperature using a surface-barrier silicon detector and MCA. By neutron irradiation of Cd and Sn,115Cd and113Sn were produced. Their daughter nuclides,115mIn and113mIn emit intemal conversion electrons of relatively high energy. They were extracted into diethyl-ether from hydrobromic acid solution, back-extracted to water and evaporated to dryness in a stainless steel dish. The dish and silicon detector were placed in a chamber so that they were facing each others. By supplying 200 V of bias to detector, intemal conversion electrons peaks of 308.3 and 363.8 keV from115mIn and113mIn can be observed even at room temperature. The present method can be applied to RNAA such as in the detemination of Cd in metallic zinc powders.

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Abstract  

Isotopic analysis of243Cm and244Cm has been tried by using a newly developed internal conversion electron spectrometer with high energy resolution. As a result, it was demonstrated that the above isotopes can be determined individually, accurately and precisely, and that the isotopic ratio is also possible to determined sensitively by measuring only the ratio of gross counting rate of internal conversion electrons to that of alpha-rays.

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Abstract  

The conversion of either the gel or the liquid crystal phase to the most stable subgel phase in dimyristoylphosphatidylethanolamine (DMPE)-water system at a water content of 25 mass% was studied by differential scanning calorimetry and isothermal calorimetry. The calorimetric experiments were performed for two samples depending on whether the thermal treatment of cooling to -60C was adopted or not. In DSC of varying heating rate, exothermic peaks due to the partial conversion were observed at either temperatures just below the gel-to-liquid crystal phase transition at 50C or temperatures where the liquid crystal phase is present as a metastable state. The enthalpies of conversion for both the gel and the liquid crystal phase were measured directly by the isothermal calorimetries at 47 and 53C, respectively, where the exothermic peaks were observed by DSC and were compared with the enthalpy difference between the gel and subgel phases and that between the liquid crystal and subgel phases.

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Abstract  

The energy resolution of -particles from241Am,222Rn,218Po and214Po and internal conversion electrons from131mXe with a liquid scintillation system has been studied at temperatures from 13 °C to –65 °C. At lower temperatures the liquid scintillation system has shown to give better energy resolutions both for -particles and internal conversion electrons compared with the values obtained at ordinary temperature. The phenomena were explained by the increase in light output of liquid scintillator at lower temperatures.

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Abstract  

The151Eu Mössbauer spectra were measured of surface-oxidized europium/II/ sulfate with the γ-ray transmission- and conversion electron technique. The comparison of such spectra demonstrated that the change in the oxidation state of trace amounts of europium induced by surface reactions could be characterized by the conversion electron Mössbauer technique. The photochemical reduction of europium/III/ oxalate to a Eu/II/species after irradiation with a low-pressure mercury lamp was demonstrated by means of this technique as well as ESR.

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Abstract  

Alpha-ray spectrometry is at present a powerful analytical tool for the identification and assay of the transuranium elements. However, the energy resolution is not necessarily excellent and a tailing toward the lower energy side in the spectrum is observed. Then, the possibility utilizing internal conversion electron spectrometry as the improved analytical tool was examined. In this paper the construction of an internal conversion electron spectrometer with excellent energy resolution using a silicon surface barrier detector and its application to analysis of a mixture of243Cm/244Cm is described.

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Abstract  

The dependence of conversion degree estimated from the (TG) curve of the mass loss on heating of temperature has been analyzed. It has been shown that dynamic TG curve can be modeled by an equation relating to the logarithm of conversion degree as a function of temperature. A coefficient in the equation developed provides information on the distance from the equilibrium, therefore, the coefficient a 2=0–50 implies equilibrium, while a 2>50 informs about some distance from the equilibrium. Further possibilities for the use of the models of lnα vs. 1/T in the analyses of thermodynamics and kinetics of thermal dissociation of solids has been shown.

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Because of the effect of photoperiod on physiological and biochemical processes in fish, this study aimed to evaluate the effect of manipulated photoperiod on growth, feed conversion and survival of wild carp, Cyprinus carpio. Fish received six photoperiod regimes (light:dark cycle) including: natural photoperiod (control), 24L:0D, 16L:8D, 12L:12D, 8L:16D and 0L:24D by the three replications. Regulated photoperiods as a 16L:8D or 12L:12D light/dark cycle significantly improved growth rate and food conversion ratio of wild carp.

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