Time Positron Diagnostics of Metal β-Diketonates

The effects of the nature of the metal atom and -substituents in aluminum(III), chromium(III), cobalt(III), and iron(III) acetylacetonates on the lifetime and intensity of a long-lived component in positron and positronium annihilation were studied by the method of positron diagnostics. An addition of a positron to the -system of a chelate ring is supposed, which makes it possible to qualitatively estimate the basicities of the complexes. Annihilation of positrons and halogen-containing positronium -diketonates is accompanied by the formation of a protonated complex; for -organylthioacetylacetonates, annihilation follows the inhibition mechanism.     

Chemical modification of natural clays

Natural clay samples and calcined clay varieties treated with hydrochloric acid of various strengths were characterized by X-ray diffraction, positron annihilation spectroscopy, and IR spectroscopy. The specific surfaces and pore sizes were determined by nitrogen adsorption. The constituent phases of the clay were found to be nontronite, muscovite, quartz, and hematite; after calcination, quartz, muscovite, hematite, and an amorphous phase remained in the samples. The Brilliant Green adsorption properties and tribotechnical properties of the modified clays were studied. The natural clay was surface-modified chemically by means of consecutive exposure to 36.5% hydrochloric acid and an alkaline hydrolyzate of rice hulls. Calcination at 700°С destroyed the amorphous phase to a greater extent; exposure to acid provided a greater recovery of aluminum and iron ions from the surface of calcined samples. Native clay composites with an alkaline hydrolyzate of rice hulls were shown to have enhanced tribotechnical characteristics.     

X-ray determination of the volume fraction of the B19′ martensite in nickel-titanium alloys

An X-ray method has been considered for determining the volume fraction of the B19′ martensite in semi-product NiTi alloys, which is based on comparing the total integrated intensity of its strongest reflections with the total integrated intensity of reflections from the matrix B2 phase. It has been shown that the method enables one to determine the volume fraction of martensite with an error of about 1% both in textured and textureless samples.     

Studies of natural kaolinite and its modified forms

Modified forms of the natural and annealed at 700°C kaolinite have been fabricated by treatment using hydrochloric acid of different concentrations. The resulting samples were investigated using X-ray fluorescence spectroscopy, X-ray diffraction analysis, IR spectroscopy, and positron annihilation spectroscopy, scanning electron microscopy, etc. The dependencies of elements contents, dye adsorption, specific surface area, and specific internal volume on the concentration of hydrochloric acid have been determined. It has been demonstrated that the changes in the structure of annealed kaolinite were significantly increased by the increase of the concentration of acid, and also there were proportional changes in the values of specific surface area, internal volume, and dye adsorption. Changes in the structural parameters of natural kaolinite depend on the acid concentration in a less degree. Modification with acid results in obtaining solutions that contain metal chlorides. Precipitation of these metals in the form of oxides on the surface of kaolinite particles results in fabrication of new sorbents, whose yield is close to the quantitative one, whereas the kaolinite sorption characteristics become improved. Further kaolinite modification by cellulose under similar conditions results in fabrication of a new, more efficient sorbent. It has been demonstrated that natural kaolinite treated with 12% hydrochloric acid had lower friction coefficient than the annealed one.     

Thermally initiated disproportionation of manganese(II) bis(1-hydroxyethylidene)diphosphonate. Formation and properties of the lepidoid structure of manganese(II) (1-hydroxyethylidene)diphosphonate-2-hydroxyethaneaminium whiskers. Agronomical efficiency of the manganese(II) complex with (1-hydroxyethylidene)diphosphonic acid

Russian Chemical Bulletin - The reaction of poorly soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tetrahydrate (Mn(H3L)2?4H2O) with 2-aminoethanol (H2NCH2CH2OH) in an aqueous...     

Kinetics of radiation damage and martensitic transformations in TiNi alloys irradiated with neutrons

The variation of the temperatures of martensitic transformations and the rate of radiation damage in TiNi alloys were studied upon irradiation with reactor neutrons. The irradiation was performed at temperatures of 120 and 335 K. In the process of irradiation, electrical resistance of the alloys was measured continuously and thermal cycling through the temperature range of martensitic transformations was carried out. The transformation temperatures were shown to decrease at different rates with increasing irradiation fluence. The electrical resistance increases linearly with increasing neutron fluence to 6.7×10¹⁸ cm^?2 irrespective of the irradiation temperature. Deviation from a linear dependence is only observed when the irradiation leads to a change in the phase state of the alloy. The rate of the resistance increase only slightly depends on the irradiation temperature. In martensite, it is greater by a factor of 2–4 than that in austenite. Mechanisms of irradiation-induced modification of the structure of TiNi alloys that explain the experimental data obtained are discussed.     

Crystallization of Complexes of Nitrilotriacetic Acid with Organic Amines. Molecular Structure of Hexamethylene-1,6-Diammonium Nitrilotriacetate

Crystallography Reports - Methods are described for the synthesis and purification by recrystallization of amine nitrilotriacetate salts N(CH2COOH)3: bis(propionic acid 2-ammonium)...     

Emission Properties of the Plasma in Mixtures of Helium with Diethylzinc and Hydrogen Selenide Vapors

The emission properties in the range 200-600 nm of the low-temperature plasma in mixtures of He with Et₂Zn and H₂Se vapors were studied. The spectrum of emission accompanying decomposition of Et₂Zn includes 26 identified lines of Zn atoms and strong emission of electronically excited CH* radicals, and in the case of decomposition of H₂Se two emission lines of Se atoms and an emission band of SeH* radicals are observed. The rate constants of quenching of the levels He 4d ³ D _2,1 and 3p ¹ P ₁ on introduction into the He plasma of Et₂Zn and H₂Se vapors were determined; Et₂Zn is a stronger quenching agent than H₂Se. Analytical lines allowing monitoring of ZnSe film deposition were selected. Direct plasmochemical decomposition of mixtures of Et₂Zn with H₂Se results in growth of textured ZnSe(cub) layers with substantial inclusions of the hexagonal phase and with carbon-containing inclusions. The photoluminescence spectra of the films obtained exhibit a strong edge band at 460 nm, overlapping with a strong self-activated band centered at 540 nm.     

钛镍形状记忆合金冲击变形后形状记忆效应的研究

采用SHPB技术和可控速率循环加温条件下变形恢复量测定装置研究了冲击及静载变形后的TiNi形状记忆合金的单程及双程形状记忆特性。发现马氏体状态下的TiNi合金的力学特性显示出明显的应变率强化效应 ,并且高应变率压缩应力应变曲线呈现流动平台。应变率对形状记忆效应的影响具有双重性 ,当外加应力或残余应变较小 ,可逆非弹性变形机制起主导作用时 ,提高应变率可以增加其单程形状记忆效应 ;而随外加应力或残余应变增大 ,当基于位错机制的不可逆非弹性变形机制起主导作用时 ,应变率提高却抑制了其单程形状记忆效应。应变率对TiNi合金双程形状记忆效应的影响视塑性变形的大小而异 ,高应变率动载后的双程形状记忆效应在较小塑性应变时 ,比静载后的要强 ;但在较大塑性应变时两者差别不大。     

Preparation of organomodified aluminosilicates for purification of biological solutions

Organomodified aluminosilicates for purification of biological solutions were prepared from a natural zeolite. The synthesis was performed by chemical deposition of chitosan on the zeolite surface followed by successive treatment with a solution of copper sulfate and a solution of potassium ferricyanide. The composition of sorbents was determined by elemental analysis. The physicochemical properties of the starting and modified zeolites were studied by the positron annihilation spectroscopy, IR spectroscopy, powder X-ray diffraction, and scanning electron microscopy, while the adsorption properties were examined by sorption of brilliant green. The adsorption behavior of the zeolites toward endotoxins was assessed. The sorbent containing the ferricyanide-chitosan complex was found to have the highest sorption capacity for lipopolyssacharides (endotoxins).