Environmental assessment of coal ash ponds of thermal power plants in the south of the Russian Far East

The results of environmental assessment of ash ponds of thermal power plants in Vladivostok and Khabarovsk are given. High radioactivity of coal in the Russian Far East is responsible for the accumulation of radionuclides in the fly and bottom ashes, which leads to pollution of atmosphere, lithosphere, biosphere, and hydrosphere with toxic and radioactive elements. Runoff carries these elements to the Ussuri Bay of the Sea of Japan. Harmful effect of these wastes on human health is noted, and possible ways of their utilization have been recommended.     

Ensuring of environmental safety in the reclamation of anthropogenic placer gold deposits in the North of Khabarovsk Krai

The results of studying mercury pollution of ecosystem in the zone affected by anthropogenic placer gold deposits are given. A major hazard to the environment and human health results from minerals processing wastes polluted with mercury and dumped in the placer gold-concentrating sites (PGCS) near mining villages, which have transformed into unequipped authorized landfills. The recent tendency to their reclamation should favor extensive mercury pollution. Actions have been proposed to ensure environmental safety of mineral processing wastes and reclamation of anthropogenic placer gold deposits.     

Composites Based on Succinic Acid and Fumed Amorphous Silicas

Theoretical and Experimental Chemistry - It was found that composite systems with succinic acid, in which a significant part of the acid is in the voids between the particles of silica while the...     

The effects of sample preparation methods on the variability of the electrospray ionization response for model drug compounds

A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright 1999 John Wiley & Sons, Ltd.     

Mineral nanoparticles in dispersed soils

The chemical-mineral composition and morphological features of mineral nanoparticles of clay soils have been studied. In the clay soils of the Moscow moraine, nanoparticles are found to be localized in the surface microcavities of sand and silt grains covered with clay films. They have predominantly anisometric configurations and comprise mainly mixed-layered clay minerals and ferric oxides. The distinctive features of mineral nanoparticles are the high levels of specific surface and cation exchange capacity.     

The Sorption of Radionuclides on Clay Minerals—the Components of Engineering Safety Barriers

Moscow University Chemistry Bulletin - The sorption properties of various clay minerals and materials based on them in relation to Cs(I), Sr(II), U(VI), Eu(III), and Pu(IV,V,VI) are compared. To...     

Prospects for Development of an Eco-Friendly Nanocarbon Matrix for Combined Immobilized Microbial Preparations

A new method for graphene preparation by self-propagating high-temperature synthesis process was proposed. The effect of the resulting material on various microorganisms and the process of graphene nanoparticles conjugation with microbial cells were discussed.

     

Investigation of the leaching behavior of components of the magnesium potassium phosphate matrix after high salt radioactive waste immobilization

The samples of the magnesium potassium phosphate (MPP) matrix have been synthesized during solidification of the simulator of acid intermediate level waste. The main phase of the obtained samples corresponds to MgK_1?x(NH₄)_xPO₄ × 6H₂O. The behavior of the matrix components during leaching with bidistilled water according to the semi-dynamic test GOST R 52126-2003 has been studied. The high hydrolytic stability of the MPP matrix to leaching of ¹³⁷Cs, ⁹⁰Sr, ²³⁹Pu and ²⁴¹Am exceeding the stability of the cement matrix has been shown. It has been found that the components leaching process is controlled by various mechanisms due to the formation of the salts with different solubility.     

Interplay of Magnetic Exchange Interactions and Ni?S?Ni Bond Angles in Polynuclear Nickel(II) Complexes

The ability of bridging thiophenolate groups (RS^?) to transmit magnetic exchange interactions between paramagnetic Ni^II ions is examined. Specific attention is paid to complexes with large Ni? SR? Ni angles. For this purpose, dinuclear [Ni₂L¹(μ‐OAc)?I₂][I₅] ( 2 ) and trinuclear [Ni₃L²(OAc)₂][BPh₄]₂ ( 3 ), where H₂L¹ and H₂L² represent 24‐membered macrocyclic amino‐thiophenol ligands, are prepared and fully characterized by IR‐ and UV/Vis spectroscopy, X‐ray crystallography, static magnetization M measurements and high‐field electron spin resonance (HF‐ESR). The dinuclear complex 2 has a central N₃Ni₂(μ‐S)₂(μ‐OAc)Ni₂N₃ core with a mean Ni? S? Ni angle of 92°. The macrocycle L² supports a trinuclear complex 3 , with distorted octahedral N₂O₂S₂ and N₂O₃S coordination environments for one central and two terminal Ni^II ions, respectively. The Ni? S? Ni angles are at 132.8° and 133.5°. We find that the variation of the bond angles has a very strong impact on the magnetic properties of the Ni complexes. In the case of the Ni₂‐complex, temperature T and magnetic field B dependencies of M reveal a ferromagnetic coupling J=?29 cm^?1 between two Ni^II ions (H=JS₁S₂). HF‐ESR measurements yield a negative axial magnetic anisotropy (D<0) which implies a bistable (easy axis) magnetic ground state. In contrast, for the Ni₃‐complex we find an appreciable antiferromagnetic coupling J′=97 cm^?1 between the Ni^II ions and a positive axial magnetic anisotropy (D>0) which implies an easy plane situation.