HADES is a large acceptance spectrometer operating at SIS18, GSI, in Darmstadt, Germany 1. It is aimed at exploration of the QCD phase diagram at the ion beam energies of 1-2 AGeV in the region of ...high density baryonic matter. An unphysical behavior of particle directed flow deduced from raw experimental data obtained during experimental study of Au+Au collisions at 1.23 AGeV is observed. It is found that dependence of the directed flow on rapidity does not show the antisymmetry expected in the symmetric projectile-target system, and there is significant non-zero directed flow at midrapidity where this component has to be zero, again from the system symmetry reasons. Possible explanation of the effect is due to the final granularity of corresponding detector and hence limited resolution of close particle tracks.
In the Republic of Kazakhstan, within the framework of international initiatives on the non-proliferation of nuclear weapons, the IVG.1M research reactor is being converted to low enriched fuel. Due ...to the change in the fuel composition, it becomes necessary to assess the power density distribution in the fuel assemblies and in the core altogether. Close attention to this parameter is explained by the fact that the non-uniformity of the radial and axial power density fields determines the operating parameters of the reactor, its power, the core resource and the efficiency of fuel utilization. The purpose of this work is approbation of the activation gamma-spectrometry method for determining the power density distribution in the fuel of the IVG.1M research reactor after conversion.
Additionally, for a preliminary assessment of the experimental outcomes, the paper presents the MCNP6 calculation results for the power distribution in fuel assemblies and the peaking factors.
•The possibility of converting the IVG.1M reactor to low-enriched uranium was investigated.•A review of the main experimental methods for determining the power density fields is carried out.•The experimental method of determining the power density distribution in IVG.1M during the physical start-up is proposed.•The results of MCNP6 calculation of the radial and axial power distribution in the fuel of the IVG.1M are presented.•The comparative analysis of the axial power density distribution for HEU and LEU fuel is presented.
Synthesis of a molded adsorbent (MA) based on zinc oxide doped with oxides of transition metals (cobalt, copper, magnesium, titanium) was considered. The influence of these dopants on the physical ...properties and performance of the MA was shown. The role of the amount of the dopant in the specific surface area and porosity of the MA was evaluated, and the effect of transition metal oxide dopants on its surface morphology and strength was demonstrated. The chemisorption capacity of the oxide systems synthesized toward carbon disulfide was experimentally determined. The influence of carbon disulfide chemisorption on the surface morphology, as well as on the strength properties of the MA, was investigated. Using thiophene as a model hydrogen acceptor, the activity of the MA in the destructive reduction of organosulfur compounds was examined. The selectivity of thiophene hydrogenation to 2,3-dihydrothiophene in the temperature range from 350 to 410°C was shown. The optimal temperature of thiophene reduction was found to be 390°C, irrespective of the dopant amount. Using gas chromatography, the chemical composition of the hydrogenate was determined, and the complex dependence of its composition on the nature of the doped oxide was shown. It was demonstrated that doping with small amounts (up to 1.5 wt %) of cobalt and copper oxides provides for significant catalytic ability of the MA in the thiophene reduction reaction and that doping with 0.5 wt % titanium and magnesium oxides affords improvement of the strength properties of the MA. Use of aqueous ammonia solutions of various concentrations for the charge preparation did not noticeably affect the strength characteristics of the MA. The increments in the strength of the MA after the desulfurization process were estimated. It was shown that the MA operation has little effect on its morphology and crystallinity.
Two methods of synthesizing composite precursors for obtaining catalysts of the process of liquid-phase hydrogenation based on nickel and silica gel are considered. A comparative analysis is made of ...methods of synthesis as a function of methods of preparation is presented, and the influence of mechanoactivation on the textural properties of catalysts is also investigated. Bulk density, particle porosity, specific surface area, total pore volume, and the radial distribution of the pores were chosen as the main textural properties. X-ray phase analysis, scanning electron microscopy, and low-temperature adsorption of nitrogen were used for these purposes.
For the first time, silica gel-supported nickel hydrogenation catalyst has been synthesized via the mechanochemical method from oxides in a single stage. A set of data on the effect of the catalyst ...mechanochemical activation conditions on specific surface area, pore size distribution, crystallites size, and crystal lattice imperfection has been obtained. Activity of the obtained catalyst towards mild-conditions reduction of multiple carbon bonds in styrene, prop-2-en-1-ol, and diethyl maleate has been studied. Recommendations for establishing the optimal parameters for obtaining a nickel catalyst using mechanochemical synthesis have been elaborated.
A new species,
Sonitha lapa
sp. n. (Gabon, type locality), is described; a detailed differential diagnosis is given. A key to the species is presented for the first time.
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