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Purpose: The Arctic territories of Russia are mostly situated on the permafrost soils, which greatly complicate the service and construction of wastewater systems in urban areas. Design: Options are proposed for the thermal and technical calculation of pipeline sections of the pressure and gravity domestic sewage system to ensure an effective energy saving while maintaining reliability of the system operation. Research findings: Diagrams are suggested to quickly and accurately determine the thermal insulation parameters and ways to maintain positive wastewater temperatures during their transportation in a cold season. Practical implications: The obtained data can be used to select the most energy-efficient and reliable design solution. Originality / value: Recommendations on the thermal analysis will help to draw the right engineering decision in designing sewerage networks in northern conditions.

Hexacarbonyltechnetium(I) cation undergoes rapid hydrolysis in aqueous solutions at pH ≥ 7 with the formation of an unidentified carbonyl compound or mixture of compounds in the form of a pale yellow precipitate. Two crystalline fractions were isolated in the course of vacuum sublimation of the precipitate and were identified by single crystal X-ray diffraction as Tc2(CO)10 and Tc3H3(CO)12. The crystal and molecular structures of these compounds were described. The mechanism of their formation in the course of hydrolysis of [Tc(CO)6]+ cation is discussed.

Technetium(I) tetracarbonyl complexes with diethyldithiocarbamate and methylxanthate ligands [TcL(CO)(4)] (L = S(2)CNEt(2) and S(2)COMe) were prepared. Conditions required for the formation of these complexes were found. The crystal and molecular structure of the xanthate complex was determined by single-crystal X-ray diffraction. [Tc(S(2)CNEt(2))(CO)(4)] undergoes decarbonylation both in solution and in the course of vacuum sublimation with the formation of a dimer [Tc(S(2)CNEt(2))(CO)(3)](2) whose structure was determined by single-crystal X-ray diffraction. In donor solvents, [Tc(S(2)CNEt(2))(CO)(4)] and [Tc(S(2)COMe)(CO)(4)] undergo decarbonylation with the formation of tricarbonyl solvates [TcL(CO)(3)(Sol)]. The crystal structure of the pyridine solvate [Tc(S(2)CNEt(2))(CO)(3)(py)], chosen as an example, was determined by single-crystal X-ray diffraction. The possibility of using bidentate S-donor acidic ligands for tethering the tetracarbonyltechnetium fragment to biomolecules was examined.

The crystal and molecular structure of cesium tris(pivaloyltrifluoroacetonato)uranylate prepared in the form of a crystal solvate Cs[UO2(Bu t COCHCOCF3)3]·1.5C6H6·H2O was studied by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system, a = 26.9099(9), b = 13.1549(4), c = 24.4586(8) A, β = 90.418(2)°, V = 8658.0(5) A3 (at 100 K), Z = 8, space group C2/c. Of the three β-diketonate ligands, two are coordinated to the uranyl ion in the bidentate fashion, and the third ligand, in the monodentate fashion, so that the equatorial coordination number of the uranyl ion is 5. The crystal structure is built of sandwich-type dimers in which two cesium cations are arranged between two tris(pivaloyltrifluoroacetonato)uranylate anions. The coordination sphere of the cesium cation is built of oxygen atoms of the β-diketone and uranyl groups, fluorine atom of the CF3 group, and π-coordinated benzene molecule. In addition, 0.5 benzene molecule and one water molecule (per formula unit) occupy structural voids.

The crystal and molecular structures of tricarbonyltechnetium acetylacetonate and its adduct with diethylamine were studied by single crystal X-ray diffraction. Tricarbonyltechnetium acetylacetonate crystallizes in the triclinic system, space group \( P\bar 1 \), a = 8.1154(1), b = 8.1961(2), c = 8.2695(1) A, α = 64.5618(9)°, β = 69.7899(8)°, γ = 83.6925(9)°, V = 465.652(14) A3 (at 100 K); Z = 2. The adduct also crystallizes in the triclinic system, space group P{ie145-2}, a = 7.9338(3), b = 8.5421(3), c = 12.1506(7) A, α = 96.961(3)°, β = 99.952(3)°, γ = 112.001(2)°, V = 736.25(6) A3 (at 100 K); Z = 2. Tricarbonyltechnetium acetylacetonate has a centrosymmetrical dimeric structure. The dimerization occurs through the formation of a bridging bond with the methine carbon atom of the acetylacetonate ligand which is thus coordinated in the tridentate chelating-bridging fashion. The adduct has a monomeric structure with chelating coordination of the acetylacetonate ligand and coordination of diethylamine to the technetium atom via N atom. In both complexes, the carbonyl groups are in the fac position. Differences between the structures of tricarbonyltechnetium acetylacetonate in the crystal and in solution are discussed.

Technetium carbonyl complexes [TcBr(CO)5], [TcI(CO)5], [TcX(CO)3]4 (X = Cl, Br, I), [TcBr(CO)3en] (en = ethylenediamine), [Tc(RCOCHCOR′)(CO)3(Et2NH)] [R = CH3 or C(CH3)3, R′ = CF3], Tc2(CO)10, and [Tc(C5H5)(CO)3] were tested as starting compounds for chemical vapor deposition of technetium coatings. The conditions of deposition of technetium coatings were determined, and the deposition yields were evaluated.

Crystal and molecular structures of adducts of uranyl pivaloyltrifluoroacetonate with hexamethylphosphoramide [UO2(PTFA)2(HMPA)] (I) and of uranyl trifluoroacetylacetonate with trimethyl phosphate [UO2(TFA)2(TMP)] (II) were determined. Compound I crystallizes in the monoclinic system, space group P21/n; a = 16.9384(3), b = 9.1090(2), c = 20.9844(4) A, β = 101.5337(10)°, V = 3172.34(11) A3 (at 100 K); Z = 4. Compound II crystallizes in the rhombic system, space group Pbca; a = 17.8214(4), b = 7.7786(2), c = 30.9176(7) A, V = 4285.97(18) A3 (at 100 K); Z = 8. In both cases, the cis isomer in which the neutral ligand is located between the trifluoromethyl groups is realized. Compound I differing from II by the stronger branching of ligand periphery is characterized by stronger structural deformations in the crystal.

The microstructure, chemical and phase composition, and corrosion resistance of coatings deposited by thermolysis of vapors of volatile technetium carbonyl compounds on a titanium support are studied. The relationship between the nature of the starting compound, conditions of the heat treatment of the coatings, and their chemical and phase composition and corrosion resistance is analyzed. Vacuum annealing at a high temperature (no less than 900°C) is the necessary condition for preparing corrosion-resistant coatings. The highest corrosion resistance is attained at low ( 15%) carbon content of the coating. Some samples are not inferior to dense technetium foil in the corrosion resistance. Ways of further improvement of the deposition process are outlined.

The crystal and molecular structure of uranyl acetylacetonate dimer was determined by single crystal X-ray diffraction. The compound crystallizes in the tetragonal system, a = 7.9420(2), c = 40.1240(13) A (at 100 K), Z = 4, space group P41212. Dimeric uranyl acetylacetonate molecules in the crystal are formed by bridging bonding of one of O atoms of the acetylacetonate ligands with U atoms, so that the coordination polyhedra of U atoms (distorted pentagonal bipyramids) share a common equatorial edge. The dimer has a nonplanar structure, being significantly bent along the conventional line connecting the bridging O atoms.

The crystal and molecular structures of [TcCl(CO)5] and [TcBr(CO)5] were determined. The compounds crystallize in the rhombic system, space group Pnma; a = 11.6757(18) and 11.9564(18) A, b = 11.7365(14) and 11.7250(18) A, c = 6.0407(7) and 6.2020(15) A, V = 827.77(19) and 869.5(3) A3, respectively; Z = 4. The structural data for pentacarbonyl halides were compared in the series Mn-Tc-Re and Cl-Br-I. Quantum-chemical calculations of the compounds [TcX(CO)5] (X = F, Cl, Br, I) and of the anion [TcCl3(CO)3]2− were made. A correlation between the geometry, electronic structure, and reactivity of the complexes is considered.

A procedure was developed for preparing Tc(CO)6ClO4 by carbonylation of a solution of technetium(I) tricarbonyltriaqua complex in 2 M HClO4 in a pressure vessel at 100–170°C and CO pressure of 150 atm. The hexacarbonyltechnetium cation in solution was characterized by IR and 99Tc NMR spectroscopy, and also by high-performance liquid chromatography (HPLC). The effect of particular acid and of synthesis conditions on the yield of the hexacarbonyltechnetium cation was examined, and the stability of this cation in aqueous solutions was evaluated. Conditions were found for preparing an aqueous solution containing 99mTc(CO)6+.

The kinetics of decarbonylation of pentacarbonyltechnetium halides TcX(CO)5 (X = Cl, Br, I) in CCl4 solution with the formation of dimers [TcX(CO)4]2 and of CO substitution in TcBr(CO)5 by the solvent molecule in CH3CN solution with the formation of the complex TcBr(CO)3(CH3CN)2 was studied. In all the systems, the reaction is first-order with respect to the starting compound. It was concluded that the limiting step of the reaction is dissociation into the intermediate complex TcX(CO)4 and CO molecule. The rate constants and activation energies of the reactions were determined.

It was demonstrated with an example of floodplain soil of the Yenisei River (Atamanovskii Isl.) that, in long-time percolation of the liquid phase through the soil, partial oxidation of the bioreduced iron with atmospheric oxygen strongly (by several times) increases the leaching of radiostrontium as compared to that under anaerobic conditions. The experiments were carried out on a laboratory setup allowing long-term controlled steady-state percolation of the liquid phase through a soil bed and collection of mobile soluble and colloid radiostrontium species at the outlet. Species coarser than 500 A were retained on a specially designed combined bilayer membrane operating in the contact ultrafiltration mode without applying external pressure. It was found that 92% of radiostrontium is leached from the soil with fine species (

Gleyzation-mediated leaching of radiostrontium from floodplain soils of the Krasnoyarsk Mining and Chemical Combine (MCC) activity zone [Atamanovskii Island (front part), Oseredysh Island (front part), and Berezovyi Island (rear part)] is studied with model systems. Leaching of radiostrontium from waterlogged soils is analyzed in terms of the model of anaerobic biosolubilization of gel films. The leaching of radiostrontium is found to correlate with that of iron, confirming the cosolubilization model. Addition of glucose (0.5%) as a stimulant for growth of iron-reducing microorganisms increases the dynamic coefficient of radiostrontium leaching, particularly in soils with lower organic matter content. The model experiments showed that the radiostrontium leaching rate from floodplain soil is higher by 2–3 orders of magnitude than that of radio-cesium, suggesting the possibility of escape of radiostrontium from the floodplain of the Yenisei River with the intrasoil runoff. This conclusion is supported by the experimental data on the 90Sr/137Cs ratio in the floodplain of the Yenisei River downstream of MCC (0.01–0.1).

Leaching of radiostrontium from soil under gleyzation is studied with a laboratory setup allowing controlled long-term percolation of the liquid phase through a soil sample and collection of mobile soluble and colloid species at the outlet. Introduction of a nutrient substrate for the growth of microorganisms promoting gleyzation enhances the leaching of radiostrontium from waterlogged soil. The results suggest joint solubilization of the macrocomponents of the clay-humus complex of the soil and associated radiostrontium under gleyzation. Data on the dynamic leaching and distribution coefficients show that, in the stagnant water regime, remobilization of strontium is less intensive than in the percolation mode. The gleyzation-mediated leaching of radiostrontium is suppressed after 2–2.5 months, which can be attributed to the inhibiting effect of Fe(II) accumulated in the system.

It is demonstrated in model experiments that in the presence of Ca ions (typomorphous cations of water of the Yenisei River) fulvic acids of floodplain soils and associated radionuclides (Am, Eu) form poorly soluble mixed Ca, Fe, Al(Am, Eu) fulvates. As a result, under the flooding conditions the migration of Am and Eu in the form of solubilized organomineral complexes is practically totally suppressed. With decreasing pH in the model system from 8 to 6 the mobility of the radionuclides noticeably increases.

The method was developed allowing quantitative extraction of fulvic acids from soil samples in the form close to native. Formation of gel-like and soluble forms of iron(III) fulvates in the systems containing equivalent amounts of iron(III) and fulvic acid was studied within pH range 1–9. The molecular structure of fulvates and the mechanism of transformation of gel to soluble forms was analyzed by IR spectroscopy. Distribution of microamounts of europium between gel-like iron fulvates and their solutions was studied. The correlation between phase distribution of europium and solubilization of iron(III) fulvates was analyzed.

Using standard low-temperature (

For the first time standard low-temperature (< 300 °C) plasma-enhanced chemical vapor deposition technology has been used to obtain a-Si(Er):H films emitting at 1.54 μm at room temperature. The fluorine-containing metalorganic compound Er(HFA)3*DME, exhibiting enhanced volatility and fairly good thermal stability, was used for the first time as the Er source. The establishment of photoconduction in the synthesized samples indicates that they are of satisfactory electronic quality and potentially useful for developing light-emitting diodes at 1.54 μm.

Synthetic and natural uranium oxides UOx (2≦×≦3) have been studied with X-ray photoelectron spectroscopy (XPS) to determine the phase composition and content of uranium ions in uraninites with a varying degree of oxidation. A strong hybridization of U6p and O2s orbitals has been found which permits a quantitative assessment of the U-O bond lengths. The values of such bonds in some substances have been found to be smaller than those in synthetic U(VI) oxide. The oxides U2O5 and U3O8 contain two types of uranium ions with a varying degree of oxidation.

Dimerization energies of trioctylammonium halides in carbon tetrachloride solution, associated as a result of dipole-dipole interaction, were calculated from the infrared absorption spectra. The values obtained were 5, 4, and 1.5 kcal/mole for the chloride, bromide, and iodide, respectively. The calculation showed that the dimers of these salts are contact dimers.