Improvements in the Grinding of Gold-Bearing Geochemical Samples and Their Sampling for Fire Assay

The effect of fine grinding of gold-bearing geochemical samples on the representative sample size and the recovery of gold and silver in fire-assay fusion was studied experimentally. A method is proposed for the improvement of grinding and sampling procedures in fire assay.     

Studying the dependence of the representative weight of geological samples of gold-containing ores on their particle size

The dependence of the representative weight of a geological sample of quartz sulfide gold-containing ores on their particle size is studied. It is shown that the weight of the furrow samples selected in the chemical assay of gold-containing ores of the first group can be reduced two-to threefold.     

Spin Wave Effects in Transport between a Ferromagnet and a Weyl Semimetal Surface

JETP Letters - We experimentally investigate spin-polarized transport between a ferromagnetic Ni electrode and a surface of Weyl semimetal, realized in a thick WTe2 single crystal. For highly...     

Tetracyclines

Summary As a result of a spectropolarimetric comparison of the phthalidecarboxylic products (IIIa) and (IIIb)of the degradation of aureomycin with specially synthesized 3S-(-)-3-methyl-3-phthalidecarboxylic acid (IV), the absolute configuration (I) was proved for tetracycline and 7-halotetracyclines and was postulated for 5-hydroxy- and 6-de-methyl- tetracyclines.For Communications 13–15 see [1-3].     

Effect of the preparation method of the cathode material LiNi<Subscript>0.33</Subscript>Mn<Subscript>0.33</Subscript>Co<Subscript>0.33</Subscript>O<Subscript>2</Subscript> on the electrochemical characteristics of a lithium ion cell

Complex metal oxides with the composition LiNi_0.33Mn_0.33Co_0.33O₂ prepared by various methods: sol–gel method, solid-phase method, and thermal destruction of metal-containing compounds in oil were studied. The results of elemental analysis, TGA/DSC, powder X-ray diffraction, SEM, TEM, as well as the results of electrochemical testing of the cathodes based on the obtained materials are presented. The complex metal oxides LiNi_0.33Mn_0.33Co_0.33O₂ prepared by sol–gel processes and thermal destruction of metal-containing compounds in oil consist of primary nanosized crystallites with an average size of 90 nm covered by a nanometer carbon layer, which improves the electrochemical characteristics of lithium ion batteries.     

Reaction of the sodium salts of some hydroxypyrimidines with α,ω-dihaloalkanes Communication 4. Synthesis of N-(ω-haloalkyl)uracils

Conclusions A method has been developed for the preparation of 1,3-bis(-haloalkyl)uracils with methylene chains of different lengths in the -haloalkyl radicals in the N¹ and N³ positions of the pyrimidine ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1173–1177, May, 1986.     

Magnetization dynamics of molecular magnets in a circular polarized electromagnetic wave of millimeter range

The appearance of magnetization in a crystal of molecular magnets under the action of a circular polarized electromagnetic wave of millimeter range is considered. The time dependence of magnetization is obtained for the case of resonance and for approximation of the single relaxation time.     

NAA for applied investigations at FLNP JINR: present and future

Experience in applying conventional and epithermal neutron activation analysis for some challenging areas of life sciences and material science is reviewed. For more than 30 years of its operation the radioanalytical complex REGATA at the IBR-2 reactor in Dubna has become a source of analytical data for the environmental studies, marine geology, biotechnology and medicine, technological process of diamond and boron nitride synthesis, archaeology, nanomaterials, etc. In spite of competing non-nuclear analytical techniques (AAS, ICP-ES, ICP-MS, etc.), the reactor neutron activation analysis (NAA) as a primary (ratio) method continues to be the most powerful multielement analytical technique providing quantification of trace elements at ultralow levels. Combined with modern statistical data treatment of large arrays of data, GIS (geographic information system) technologies, electron scanning microscopy, tomography, and others, NAA serves to obtain actual, practical results resumed in the review. The perspectives of using the upgraded reactor IBR-2M for analytical investigations are discussed.