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The valence states of 'hot' Np atoms arising from α-decay of Am atoms incorporated in quenched melts of alkali metal nitrates or sorbed on ion-exchange materials were studied by emission Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

The mobility of the polymer matrix and the structure of the hydration complex in the acid forms of perfluorinated ion exchange membranes MF-4SK and F-4KF depending on moisture content were studied by H, C, and F solid-state high-resolution NMR. A correlation between an increase in mobility of separate polymer matrix segments under hydration conditions and their hydrophilic properties was observed. Carboxyl groups in F-4KF membranes were shown to exist as dimers C(OOH)C, and the main hydrated complex form in MF-4SK membrane under low moisture content conditions was the hydroxonium ion HO. [ABSTRACT FROM AUTHOR]

Of the two existing radiochemical procedures for determining the isotope composition and specific activities of radionuclides in potable water (the first procedure was developed at the Center for Examining Water Quality and the second, at the Ramzaev Research Institute of Radiation Hygiene), the second procedure is more reliable. It was used for total radiochemical analysis of water from a series of underground artesian wells of north-western regions of Leningrad oblast. [ABSTRACT FROM AUTHOR]

The article presents a study which explores the radial and axial nonuniformity of plutonium isotope production in RBMK-1000 fuel.

The efficiency of zone freezing for potable water treatment to remove inorganic impurities was examined. The content of impurities in model solutions before and after zone freezing was evaluated by neutron activation analysis with the formation of 56Mn, 116 mIn, and 198Au radionuclides. The zone freezing procedure is the most efficient at low ice front velocities (no greater than 0.15 cm h−1). [ABSTRACT FROM AUTHOR]

Humates and fulvates of uranium and thorium representing a form of actinide transfer in the environment have been investigated thoroughly enough. Nevertheless, formation of humates (fulvates) of radiogenic nuclides after the preceding high-energy act of nuclear recoil is studied quite insufficiently. This is because isotope 234U assimilated by humus alongside with isotope 238U in ancient biogenic rocks, e.g. black shales, is completely decomposed, while uranium-234 present in these rocks now has formed mainly during the last 1.5-2 million years. The question is: do radiogenic uranium and also other radiogenic nuclides of the uranium-238 series preserve the chemical form of humates (fulvates) in the solid organic phase of humus? Such a question is quite natural: as a result of alpha decay radiogenic atoms (or their nearest parent nuclides) obtain kinetic energy of recoil of the order of 105 eV, which leads to full or partial destruction of both the initial molecule and the neighbouring ones in the track of the recoil atom. The possibility to maintain (or reconstruct) humate (fulvate) complexes of radiogenic atoms in the solid phase after the act of nuclear recoil is not obvious. In the present work, graptolitic argillite (Dictyonema shale) taken from the core of borehole 191-a at a deposit in North-West Estonia was investigated. The sample 2304 was taken from the bottom quarter of the layer, approximately 75 (± 15) cm above its bottom. Alpha-ray spectrometric analysis data of the sample in question show the following activity ratios (AR) in the investigated sample: 234U/238U = 1.03 ± 0.02 and 230Th/234U = 0.99 ± 0.06, the average uranium content being ∼100 µg/g. These values suggest that uranium and its decomposition products present in the shale are in the state of radioactive equilibrium or rather close to it. In the investigated sample, the total content of organic carbon (by Tjurin method) and fraction and group composition of humus (by Plotnikov-Ponomarjov method) were determined. It was established that the shale sample contains 14.4% organic carbon, but only 0.26% of this amount (i.e. 0.018% of the total organic matter of shale) is related to humic and fulvic acids, in other words to humus acids themselves. The rest of organic matter (98.2%) is presented by humins insoluble in the conditions of standard analysis, and also by individual substances oxidizing with difficulty, which represent components of kerogen organic matter. Humus acids are presented by three fractions of humic acids and four fractions of fulvic acids. In humic and fulvic acids 238U and 234U content was determined. The influence of decalcination of humates and fulvates on isotopic composition of uranium was studied. After triple extractions, more than 30% of uranium present in shale is transferred into alkaline solutions. Its distribution is as follows: 20.2% in humic acids and 10.56% in fulvic ones. This sedimentation is not attributable to adsorption, occlusion or any other mechanism of uranium capture from a solution as proved by differing isotopic composition of uranium in the separated fractions. Uranium transfer into the deposit definitely proves the formation of chemical compounds of uranium with corresponding ligands in the humus phase of Dictyonema shale. The presence of radiogenic uranium in humic acids proves that, despite of significant destruction of organic matter in the track of the recoil atom, not only the molecule of humic acid is recreated from fragments and radicals, but also strong links of uranium-234 with both humic acids and fulvic acids form.… [ABSTRACT FROM AUTHOR]

Radiochemical analysis is made of different fractions of humic and fulvic acids separated from organic matter of graptolitic argillite (dyctionemic shale) of the Baltic basin. The relation between the decalcination of humates and fulvates and the isotopic composition of U is studied. The tightness of binding to humus substances, including humin, is different for 238U and 234U, which is probably due to preferential stabilization of the radiogenic uranium in the oxidation state +4. Based on the experiments on precipitation of humates at pH 0–2, it is suggested that the thiol groups of humic acids are involved in chemical binding of 210Po. Experiments on partial decalcination of humates in 1 M HNO3 revealed stronger binding of the radiogenic Po as compared to 208,209Po. The results were interpreted in terms of the known models. [ABSTRACT FROM AUTHOR]

The article reports on the biological invasion possibility of euphausiid larvae in the ballast waters of commercial ships. This ballast water plays a significant role in anthropogenic distribution as it extends the areas of marine organisms. It is practically impossible to keep euphasiid crustaceans under culture conditions. However, euphaisiid larvae were found in a sample collected from the ballast water tanks.

The size of the eggs (alive and dead) of the euphausiid, Thysanoessa raschii (M. Sars, 1864) was studied in the various parts of the Barents Sea. There is a relationship between mortality and size in euphausiid eggs. Dead embryos dominated among eggs with both minimal or maximal diameters (embryos smaller than 300μm and bigger than 350μm; perivitelline space smaller than 25μm and bigger than 50μm). We suggest that this size-dependent mortality of euphausiid eggs is a result of stabilizing selection, thus establishing an equilibrium between egg size and number of eggs (=fecundity) in the Barents Sea population of T. raschii . [ABSTRACT FROM AUTHOR]

Studies a history of the research on Antarctic krill, expressed in the dynamics of books and articles published about the crustacean in the former Soviet Union. Periods of the dynamics of the publications devoted to the biology of Antarctic krill; Main directions of the investigations done by the All-Union Institute for Marine Fisheries and Oceanography; Distribution of the publications and the concurrent catch data of Antarctic krill over the years 1958 to 1997.

The seasonal and interannual variability of sex ratios (SR) of the Barents Sea population of the euphausiid, Thysanoessa raschii has been studied. In the winter-spring population the males dominate (SR > 1), in summer and autumn the females prevail (SR < 1). A connection was found between the SR and the water temperature two years earlier (minimal in that year and average for May, during which period zygotes are maturing, and embryogenesis and larval development take place). As a result of the increasing temperature, the share of the males in the population is reduced. The seasonal dynamics of the SR of T.raschii are discussed in connection with a general view about life cycles in euphausiids. The evolutionary processes ensuring the formation of the proper sexual structure in euphausiid populations as a whole, are considered. La variabilité saisonnière et interannuelle des sex-ratios (SR) de la population d'Euphausiacés de Thysanoessa raschii de la mer de Barentz a été étudiée. Dans la population d'hiver et de printemps, les mâles sont dominants (SR > 1); en été et en automne, les femelles sont dominantes (SR < 1). Une relation a été établie entre la SR et la température de l'eau, deux ans plus tôt (minimale cette annéelà et moyenne en mai, lors de la maturation des zygotes, de l'embryogenèse et du développement larvaire). Avec la baisse de la température, la proportion des mâles dans la population a diminué. La dynamique saisonnière de la sex-ratio (SR) de T. raschii a été discutée par rapport aux données générales concernant le cycle de vie des Euphausiacés. Des hypothèses sont émises sur les processus évolutifs responsables d'une répartition particulière des sexes dans les populations d'Euphausiacés en général. [ABSTRACT FROM AUTHOR]

The concentration dependences of the electroconductivity of membranes Nafion-117 and MF-4SK are studied in salt solutions under identical experimental conditions. The results are compared with nanostructural characteristics of Nafion-117 measured independently by the AFM and quasi-elastic neutron scattering methods. The role played by internal interfaces between hydrophobic and water-cluster microphases of Nafion during the membrane transition from the Na+ form to the form of tetraalkylammonium ions is determined. It is established that the specific adsorption of organic ions makes the water clusters disintegrate and the elasticity of side segments diminish; as a result, the polymer film's conductivity “switches off.” This morphological effect is used for interpreting the fact that the conducting and hydrophilic properties of perfluorinated membranes substantially depend on their conditioning prior to measurements. It is shown that expanding the membranes reduces the differences between the electroconductivity and structural organization of specimens of different brands with close values of the exchange capacity. [ABSTRACT FROM AUTHOR]

Combining a tracer technique with electrochemical measurements offers a unique opportunity to study the mechanism of anodic synthesis of a composite based on an electron-conducting polymer (polyaniline) and a polymeric perfluorinated sulfo cationite (Nafion, MF-4SK). The composite formation involves two steps. First, the monomer (aniline) is intercalated into the solid-cationite matrix probably with the formation of a template phase, after which postintercalation polymerization of the template occurs. [ABSTRACT FROM AUTHOR]

In this paper, the results of plankton investigations from 1952 to 2000 in the Barents and Kara seas by the Laboratory of Plankton of the Murmansk Marine Biological Institute (Kola Branch, Russian Academy of Sciences) are briefly outlined. The development of ideas on the seasonal and long-term succession of plankton communities in the Barents Sea, which were propounded by M.M. Kamshilov, the founder of the Plankton Laboratory, is shown. [ABSTRACT FROM AUTHOR]

The reaction of exo-nido-ruthenacarborane exo-nido-5,6,10-[Cl(Ph3P)2Ru]-5,6,10-(μ-H)3-10-H-7,8-C2B9H8 ( 1) with the 8-trifluoroacetoxymercury derivative of ferracarborane 3-(η5-Cp)-4-SMe2-8-CF3COOHg-3,1,2-FeC2B9H9 ( 2) was studied. It was demonstrated for the first time that metallacarborane 2 can be used as a mercurating agent. The reaction afforded 5",6",10" -exo-nido-[Cl(Ph3P)2Ru]-5",6",10"-(μ-H)3-10"-{3-(η5-Cp)-4-SMe2-3,1,2-FeC2B9H9-8-Hg}-7",8"-C2B9H8 ( 3) existing as two isomers. The structure of trans isomer 3a was established by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A statistical treatment on the data of egg size, i.e., inner (embryo) and outer (egg capsule) diameters, and thickness of the perivitelline space, has been carried out for the Barents Sea euphausiid, Thysanoessa raschii. Investigations demonstrate that (1) there is environmental adaptation (i.e., to temperature and salinity) of euphausiid egg size; (2) egg size (embryo diameter) is similar throughout the reproductive area, but reaches either lower or higher values in the expatriate zones; (3) both embryo size and female fecundity are controlled by natural selection. [ABSTRACT FROM AUTHOR]

We present a review of the Bergmann's principle and deep-water gigantism in marine crustaceans. An increase in the geographic latitude and depth of crustaceans habitat (correlating mainly with lower temperatures) leads to an increased cell size, life span of the animal, and, as a result, an increase in the body size. Since Bergmann's principle and deep-water gigantism appear to be based on the same biological mechanisms, we propose a unified principle, according to which the size of the crustacean's body increases along the temperature gradient. [ABSTRACT FROM AUTHOR]

The equilibrium (the exchange capacity, the structural resistance coefficient, and contact angles) and transport (the conductivity) characteristics of differently obtained sulfonated cation-exchange perfluoropolymeric membranes in 1 : 1 electrolyte solutions were investigated. It was shown that the transformation of membranes from the Na+form to the K+form sharply decreases their moisture content, which is accompanied by an increase in the structural resistance coefficient and the counterion concentration in membranes. Experimental data were used for calculating the electrochemical characteristics of membranes: efficiency coefficients, ion mobilities and transfer numbers of ions in the intramembrane liquid, as well as Donnan potentials. Measurements of the wettability of fluoroplastic ion-exchange membranes with water and electrolyte solutions showed that the presence of strongly acidic ionogenic groups significantly decreases contact angles as compared with that of the polytetrafluoroethylene surface. It was also established that, for the investigated systems, the contact angle is virtually independent of the composition of the liquid phase. [ABSTRACT FROM AUTHOR]

Eggs, nauplii and calyptopes of the euphausiid Thysanoessa raschii are reported from the north-eastern part of the Laptev Sea for the first time (expedition ARK XI/1, RV Polarstern, August 1995). This means that T. raschii has a complete life cycle in the Laptev Sea, including maturation and reproduction, and that there is an independent population of this species in that part of the Arctic Ocean. [ABSTRACT FROM AUTHOR]

Mercuration and bromination reactions of ferracarborane 3-(η5-Cp)-4-SMe2-3,1,2-FeC2B9H10 (1) were investigated. Mercuration of 1 under mild conditions (mercury trifluoroacetate in dichloromethane) results in 8-monosubstituted mercury derivative as the only reaction product. Depending on the reaction conditions, bromination of 1 results in 8-mono- or 7,8-disubstituted bromo derivatives. The structures of the monomercury and dibromo derivatives of 1 were established by X-ray analysis. [ABSTRACT FROM AUTHOR]

The conversion of the nation's enterprises to the new conditions of management has sharply increased the importance of fulfilling contractual obligations. This point was also emphasized at the Twenty-seventh Party Congress. However, practice shows that the target orientation of the enterprise does not always correspond to national economic interests. What does this mean? [ABSTRACT FROM AUTHOR]

This article is devoted to an investigation of the reasons for the growth in the axial vibrations of the shaft of a movable reflector of the IBR-2 research reactor, which are repeated at the start of each cycle of operation. After the passage of some time, the axial vibrations of the shaft and the housing stabilized and the device returned to its normal state of operation. The vibrational state of the shaft, the front support, and the blade of the main modulator of reactivity, which are situated near the core, was of practical interest. A finite-element model of the reflector was developed and a thermophysical calculation was performed. Based on the results, the temporal instability of temperature fields was analyzed before a stationary state arose. A dynamic strength calculation confirmed that the reflector's performance, taking into account the appearance of non-stationary temperature fields, is preserved and the requirements for cyclic strength are met. [ABSTRACT FROM AUTHOR]

Insulated pads are used on ITER blanket module connectors and the first wall; their main insulating function is to break any current loop between the shield block and vacuum vessel and/or between the first wall panel and shield block. The design of the pads consists of a cylindrical or prismatic body manufactured from NiAl-bronze, a ceramic insulating coating which is applied on interfacing surfaces of the pad body. The pads work in ultra-high vacuum conditions and at elevated temperature 100 – 300оC. Static and dynamic loads up to 2 MN can act on the insulated pads during various plasma events in ITER. The qualification program for the insulated pads consists of cyclic and impact tests. The tests are performed for two categories of loading anticipated from plasma events. The impact tests are performed on a weight drop test bench, which has been designed and manufactured in JSC "NIKIET". The description of the pad design and the impact test set-up, the results of analysis for justification of the set-up parameters, and the results of the test bench commissioning are presented in this paper. [ABSTRACT FROM AUTHOR]

Boron-containing conjugates of cholesterol were synthesized by the copper(i)-catalyzed 1,3-dipolar [3+2] cycloaddition reactions of cobalt and iron bis(dicarbollide) azide derivatives with alkynyl cholesterol. The antiproliferative activity (IC50) of the conjugates was evaluated against a series of human cell lines by the MTT assay. All conjugates were shown to be nontoxic (IC50 >200 µmol L−1) and to be applicable for the preparation of boron-containing liposomes as potential drugs for boron-neutron capture therapy (BNCT) of cancer. [ABSTRACT FROM AUTHOR]