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The MC-ICP-MS technique was used to study Ag isotope systematics in various silver and gold deposits. Owing to the correction of measured Ag/Ag values in samples for the mass discrimination effect on the basis of the Pd/Pd reference ratio, a precision of ±0.4ɛ (±2SD) was achieved. The Ag/Ag ratio was determined in native silver and gold samples from ten well-known noble-metal deposits of varying age (from the Archean to Miocene) in Europe (Kongsberg, Banska Hodrusa, Kremnica, Maiskoe, and Karabash); northeastern, central, and southern Asia (Sukhoi Log, Dukat, Aktepe, and Kolar); and North America (Kidd Creek). The Ag/Ag values of the samples studied range from +0.9 to −5.0 $$\varepsilon _{107_{Ag} }$$. The observed range is similar to that (6.4 $$\varepsilon _{107_{Ag} }$$) reported previously (Hauri et al., 2000) for oceanic basalts and Ag ores. The Ag/Ag ratio shows no correlation with the age of deposits and the composition of their ores and host rocks. The most probable reasons for the observed variations in Ag isotope composition are the isotope geochemical heterogeneity of Ag sources in mineral deposits and Ag isotope fractionation in ore-forming processes. [ABSTRACT FROM AUTHOR]

Heart rate variability during the head-up tilt test (HUT) was investigated using an automated setup of dynamic positioning in the gravity field. The wavelet theory was applied to find the dynamics of changes in the spectral properties of rhythmograms during the transitional steps of HUT. Quantitative parameters (spectral integrals, instantaneous maximal frequencies, nonstationarity factors) that describe the transients of such nonstationary HUT were calculated. [ABSTRACT FROM AUTHOR]

The paper analyzes the asymptotic behavior of disperse systems with coagulation and fragmentation of particles. The possible types of self-similarity regimes have been analyzed and conditions required for their existence have been set. The generalized approximation method (GA-method) numerical simulation is used to determine the actual behavior of moments Lα (t ). The examples of GA-method application show its suitability for use in research problems. In general, the obtained results showthat binary breakage coagulation is a wide and non-trivial scope for investigation. A number of regimes are represented such as steady state, coagulation winning, gelation, collapsing selfsimilarity and spectrum singularity. The existence of collapsing (accumulating in zero) self-similar spectra is illustrated in terms of a particular example of the coagulation kernel K(g, n) = gn and breakage rate f (g, n) = a. [ABSTRACT FROM AUTHOR]

An isotopic geochronological study of dispersed uranium mineralization was performed in the granitic rocks of the Urtui pluton in the framework of the Strel'tsovka uranium ore field and in the Yamsky site of the Urov-Uryumkan granite-gneiss arch. Two stages of such mineralization-783 ± 26 Ma in the Urtui granitic pluton and 138.6 ± 2.3 Ma in the Yamsky site-have been established. The emplacement of granite pertaining to the Unda Complex disturbed the U-Pb isotopic system in uraninite from the Urtui granitic pluton and resulted in redeposition of uranium phase dated at 262 ± 34 Ma. The young, probably, recent process gave rise to the redistribution of radiogenic lead in the U-bearing phases developing after uraninite. [ABSTRACT FROM AUTHOR]

We analyze nonlinear distortions of a useful signal in an input amplifier of the receiver under the influence of strong interference which switches the input active circuits of the receiver to a nonlinear operation mode. The method of signal reception under the conditions of strong interference is proposed. This method is based on crosstalk correction. The results of experimental testing of this method are presented. [ABSTRACT FROM AUTHOR]

The extended Saryarka and Shyngyz-North Tien Shan volcanic belts that underwent secondary deformation are traced in the Caledonides of Kazakhstan and the North Tien Shan. These belts are composed of igneous rocks pertaining to Early Paleozoic island-arc systems of various types and the conjugated basins with oceanic crust. The Saryarka volcanic belt has a complex fold-nappe structure formed in the middle Arenigian-middle Llanvirnian as a result of the tectonic juxtaposition of Early-Middle Cambrian and Late Cambrian-Early Ordovician complexes of ensimatic island arcs and basins with oceanic crust. The Shyngyz-North Tien Shan volcanic belt is characterized by a rather simple fold structure and consists of Middle-Late Ordovician volcanic and plutonic associations of ensialic island arcs developing on heterogeneous basement, which is composed of complexes belonging to the Saryarka belt and Precambrian sialic massifs. The structure and isotopic composition of the Paleozoic igneous complexes provide evidence for the heterogeneous structure of the continental crust in various segments of the Kazakh Caledonides. The upper crust of the Shyngyz segment consists of Early Paleozoic island-arc complexes and basins with oceanic crust related to the Saryarka and Shyngyz-North Tien Shan volcanic belts in combination with Middle and Late Paleozoic continental igneous rocks. The deep crustal units of this segment are dominated by mafic rocks of Early Paleozoic suprasubduction complexes. The upper continental crust of the Stepnyak segment is composed of Middle-Late Ordovician island-arc complexes of the Shyngyz-North Tien Shan volcanic belt and Early Ordovician rift-related volcanics. The middle crustal units are composed of Riphean, Paleoproterozoic, and probably Archean sialic rocks, whereas the lower crustal units are composed of Neoproterozoic mafic rocks. [ABSTRACT FROM AUTHOR]

technique for the compensation of the third order intermodulation components in the 'low-noise amplifier-double balanced diode mixer' circuit has been considered. This technique is based on the optimization of theLNAtransfer ratio and the power of mixer heterodyne. The proposed technique makes it possible to obtain the gain in terms of intermodulation of about 26-31 dB. [ABSTRACT FROM AUTHOR]

The two-factor variance analysis revealed the statistically significant influence of the conditions of habitat and weather in the year of study on the majority of morphometric parameters of vegetative and generative sphere of four natural cenopopulations of Hylotelephium stepposum (Boriss.) Tzvel. and three cenopopulations of H. triphyllum (Haw.) Holub. [ABSTRACT FROM AUTHOR]

Complexes with metal ions and nanostructures of pectin from Yalongoch lemon were prepared by precipitation. The structural organization and characteristics of the resulting nanostructures were studied by electron microscopy, rheology, and potentiometric titration. A growth-stimulating effect on cotton seeds was found for pectin nanostructures containing biogenic cations. [ABSTRACT FROM AUTHOR]

It is established that the existence of weakly divergent beams in an oceanic waveguides leads, in a certain time interval and depth range, to the formation of a characteristic triplet structure of wavefronts. It is explained that a weakly diverging beam of rays represents an Airy wave in the spatiotemporal structure of the acoustic signal field in an oceanic waveguide. [ABSTRACT FROM AUTHOR]

Amodel of phylogenetic development of life forms of herbaceous plants is proposed on the basis of a multidisciplinary study of physiological and morphological characters of complete species composition of two herbaceous cenoses (meadow and steppe). The physiological mechanism of their formation in the context of changing water supply consists in the optimization of water deficiency and production capacities of their leafs, the emergence of most efficient species-level sprout forms (non-rosette, semi-rosette and rosette), and finally in the establishment of a definite proportion between these forms within the composition of a given herbaceous cenosis. [ABSTRACT FROM AUTHOR]

The Strel’tsovka and Antei uranium deposits located in the Strel’tsovka caldera are unique in ore resources. According to the considered mathematical model, the uranium source of these deposits was related to the middle-lower crustal silicic magma chambers or had mantle origin. Boundary conditions of the model are based on modern views of physicochemical conditions of hydrothermal process in the Strel’tsovka ore field and factors governing ore deposition therein. Modeling results are consistent with morphology of orebodies and ultimate uranium resources of the deposits and thus confirm indirectly that the physicochemical parameters of the ore-forming system are coherent. The maximal duration of uranium ore deposition is estimated at 500 ka. [ABSTRACT FROM AUTHOR]

Data on the seasonal rhythms of development of the representatives of Lamiaceae ( Ballota nigra L., Dracocephalum ruyschiana L., Hyssopus officinalis L., Scutellaria baicalensis Georgi) and Asteraceae ( Eupatorium cannabinum L.) are presented. The cytoembryological study of these species was carried out, focused on the phases of flower development, morphological features, and fertility of pollen grains. [ABSTRACT FROM AUTHOR]

Necessary and sufficient conditions for the dependence of the cycle length of the Brilloin waves or rays of geometrical acoustics on the ray parameter that is inversely proportional to their phase velocity are formulated. The formulated conditions determine the existence of weakly diverging acoustic bundles in vertically stratified oceanic waveguides, even with a point sound source. [ABSTRACT FROM AUTHOR]

Isotopic content of the snow and firn thickness is assumed to be altered significantly due to the post-depositional (PD) mass- and isotope exchange with the atmospheric water vapor. If so, these effects should be accounted for in the ice core-based isotope-temperature paleo-reconstructions. In order to study the intensity of the PD processes we set up a series of laboratory experiments. In this paper we describe in detail the experimental technique and briefly overview preliminary results. It is shown that the PD modifications in the upper layer of snow thickness are noticeably strong even under such a low temperature as -35°C (the value typical for the Central Antarctic summer). It is demonstrated that the PD isotopic changes in snow can be approximated as a linear function of the relative mass loss due to snow sublimation. Possible applications for improving the isotope-temperature paleo-reconstructions are shortly discussed. [ABSTRACT FROM AUTHOR]

A comparative analysis of the Late Cretaceous-Paleocene volcanism was conducted for four areas of Kamchatka: the Pravyi Tolbachik-Levaya Shchapina-Adrianovka interlfuve (the northern part of the Tumrok Range), the area south of the Ipuin River and Mt. Khrebtovaya (the northern Valaginsky Range), the area of Mt. Savul’ch (the upper reaches of the Kitil’gina River, northern Valaginsky Range), and the Kirganik-Levaya Kolpakova interfluve (the Sredinny Range). New petrochemical, geochemical, and isotopic data on the volcanic rocks from these areas are reported. The examination of this material, together with already published data on volcanic and plutonic rocks of similar composition and age, made it possible to establish the following: (1) the considered basaltoids are ascribed to the subalkali basalt-trachyandesite series with transition toward a meymechite-picrite rock association; (2) the alkali content in the rocks of the Valaginsky-Tumrok-Sredinny ranges increases simultaneously with the increase of the Rb content, while the contents of HFSE and radioactive elements decrease and then again increase. Two trends are identified in the Ybn-Cen diagram: a positive trend spanning most of the volcanic and plutonic rocks and a negative trend defined by the data points of the meymechite-picrite association. The first trend reflects the rock evolution during crystallization differentiation, while the second trend was produced by different degrees of melting of initial protolith. The possible geodynamic reconstructions of this volcanism are discussed as well. [ABSTRACT FROM AUTHOR]

The crystal structure of a new calcium thorium phosphate has been refined by the full-profile Rietveld method using X-ray powder diffraction data. The sample has been synthesized by the sol-gel technique. The phosphate has been identified by X-ray powder diffraction and IR spectroscopy. The refined composition is represented by the formula Ca10.26Th0.12(PO4)7. The CaO n and PO4 polyhedra are distorted compared to the corresponding polyhedra in the basic compound β-Ca3(PO4)2. [ABSTRACT FROM AUTHOR]

The isotopic-geochronological studies of zircons from granites of the Borovoe, Makinsk, and Zhukei massifs located in the eastern part of the Precambrian Kokchetav median massif revealed that they were formed during the relatively brief period from 431 to 423 Ma ago, which allowed them to be united into the Early Silurian Borovoe Complex. [ABSTRACT FROM AUTHOR]

U-Pb systems were examined in samples (ranging from 4 to 10 cm3 in volume) of ore material taken from along a 3.5-m profile across a zone of U mineralization exposed in an underground mine at the Strel’tsovskoe U deposit in eastern Transbaikalia. The behaviors of two isotopic U-Pb systems (238U-206Pb and 235U-207Pb) are principally different in all samples from our profile. While the individual samples are characterized by a vast scatter of their T(206Pb/238U) age values (from 112 to 717 Ma), the corresponding T(207Pb/235U) values vary much less significantly (from 127 to 142 Ma) and are generally close to the true age of the U mineralization. The main reason for the distortion of the U-Pb system is the long-lasting (for tens of million years) migration of intermediate decay products in the 238U-206Pb(RD238U) in the samples. This process resulted in the loss of RD238U from domains with high U concentrations and the subsequent accommodation of RD238U at sites with low U concentrations. The long-term effect of these opposite processes resulted in a deficit or excess of 206Pb as the final product of 238U decay. The loss or migration of RD238U are explained by the occurrence of pitchblende in association with U oxides that have higher Si and OH concentrations than those in the pitchblende and a higher +6U/+4U ratio. The finely dispersed character of the mineralization and the loose or metamict texture of the material are the principal prerequisites for RD238U loss and an excess of 206Pb in adjacent domains with low U concentrations. Domains with low U contents in the zone with U mineralization serve as geochemical barriers (because of sulfides contained in them) at which long-lived RD238U(226Ra, 210Po, 210Bi, and 210Pb) were accommodated and subsequently caused an excess of 206Pb. The 235U-207Pb system remained closed because of the much briefer lifetime of the 235U decay products. This may account for the significant discrepancies between the T(206Pb/238U) and T(207Pb/235U) age values. RD238U was most probably lost via the migration of radioisotopes at the middle part and end of the 238U family (starting with 226Ra). The heavy Th, Pa, and U radioisotopes (234Th, 234Pa, 234U, and 230Th) that occur closer to the beginning of 238U decay, before 226Ra, only relatively insignificantly participated in the process. Our results show that the loss and migration of RD238U are, under certain conditions, the main (or even the only) process responsible for the distortion of the U-Pb system. [ABSTRACT FROM AUTHOR]

We present the results of experiments on measuring the characteristics of a wideband low frequency (10–200 Hz) acoustic field in an inhomogeneous shallow-water waveguide in the Barents Sea area. Correlation functions of the signals received by hydrophones of autonomous bottom stations with independent reception, which are horizontally spaced 18 and 112 km apart, are measured. A pneumoacoustic radiator with an overpressure of 10.5 MPa and a volume of 7.5 l was used as a sound source. During the measurements, the signal source was shifted from the line of receivers to distances 10–225 km. The dependences of the correlation coefficient of the received signals on the radiation frequency and the interferometer-baseline length and orientation are studied. It is shown that pronounced local minima in the interval 10–40 Hz due to the difference of the inhomogeneities in the propagation channels and, therefore, the frequency characteristics of the medium are present in the frequency dependences of the correlation coefficient against the background of a monotonic decrease with increasing frequency. [ABSTRACT FROM AUTHOR]

The structure and tectonics of the Aga Zone are considered. It is shown that this zone is a system of tectonic nappes thrust over the Argun microcontinent. The zone is composed of two rock complexes related to the Variscan and Kimmerian structural stages. The Variscan stage (Silurian(?)-Early Carboniferous) comprises structural elements that correspond to the continental slope; the oceanic basin proper; the active continental margin, including an accretionary wedge; and an island arc and backarc basin. The Devonian age of the ophiolites of the Shilka Belt is specified. The formation of this set of tectonic units is related to the Middle Paleozoic pulse of the opening of the Mongolia-Okhotsk paleobasin. The Kimmerian stage (Middle Carboniferous-Early Jurassic) is characterized by a different style of structural evolution. A system of separate troughs filled with flyschoid sequences was formed on the Variscan basement. The unstable setting related to shortening and closure of the paleobasin brought about the spatial migration of sedimentation zones and the development of intraformational breaks in sedimentation, as well as unconformities. This stage was completed in the Lias by the general uplift of the territory and the formation of Jurassic and Cretaceous mollase along its periphery. The Aga allochthonous mass was ultimately formed in the Middle Jurassic. This event is recorded in emplacement of Middle-Late Jurassic granitic plutons that blocked the nappes. The granitic-metamorphic layer was formed in the Paleozoic and Early Mesozoic at the margin of the Aga Zone upon its conjugation with the adjacent continental masses; this layer is related to crustal anatexis. The bulk of the granitic rocks of the Aga Zone were generated in the Middle and Late Jurassic due to the collision of the North Asian continent with the Argun microcontinent. [ABSTRACT FROM AUTHOR]

Based on the study of local volumes of minerals, including their microsampling and subsequent analysis of Pb/Pb and U/Pb isotope ratios with the classic methods of isotopic dilution and thermoionization mass spectrometry (TIMS), U-Pb and Pb-Pb isotopic datings of minerals were carried out in uranium ores from deposits in the Akitkan and Nechera-Nichatka ore districts (North Baikal region). Reliable evidence in favor of the Middle Devonian (384 ± 8 Ma) remobilization of Paleoproterozoic primary uranium concentrations and the redeposition of uranium as pitchblende 2 has been obtained for the first time for ores of the Akitkan district. The Paleoproterozoic (1832 ± 13 Ma) age of uraninite mineralization and the timing of the latest (377 ± 5 Ma) transformation of uranium ores at the Chepok deposit (Nechera-Nichatka district) are substantiated. [ABSTRACT FROM AUTHOR]

The estimation of the long-term stability of crystalline rock massifs with respect to natural and technogenic loads in the course of long-term storage of spent nuclear fuel (SNF) is a special area of surveys at underground research laboratories (URLs). In parallel with these surveys, data on uranium deposits—natural analogues of repositories of SNF consisting of 95% UO2—are used for obtaining insight into the dynamics of radionuclide migration and validating barrier properties of host rocks. Examples of URLs located in granitic massifs of Sweden (Äspö), Canada (Whiteshell), Switzerland (Grimsel), Japan (Mizunami), and Finland (ONKALO), as well as the El Berrocal (Spain), Palmottu (Finland), Sanerliu (China), and Kamaishi (Japan) deposits, are considered in the paper. The objects listed above are distinct in tectonic settings, geology, control of ore mineralization, redox conditions of uranium migration, and character and intensity of filtration and transportation, which predetermine the direction and specific features of research conducted therein. A variant in which a URL and a natural analogue are combined in one object is especially promising for validation of safe long-term isolation of SNF. The Antei vein-stockwork uranium deposit in the southeastern Transbaikal region, localized in Paleozoic granite at a depth of 400–1000 m and opened by mine workings at six levels, is such an object. Its geological features, stress-strain state, and infrastructure of mine workings offer an opportunity to study the entire spectrum of processes proceeding in near-and far-field of an SNF repository. The structural geology, mineralogy and petrography, and petrophysical and tectonophysical features of the deposit at its three lower levels are considered. The sequence of metasomatic alteration of rocks and the dynamics of formation of ore-bearing faults that crosscut prototectonic elements, as well as relationships of physicomechanical properties of rocks as a function of the intensity of their metasomatic alteration and the distance from master fault planes, have been established. A 3D geological model of the deposit in combination with estimated parameters of the present-day stress field and physicomechanical properties of particular rock blocks serves as the basis for prediction of the geomechanical behavior of the massif. The practical implications of the results obtained for assessment of the long-term safety of SNF repositories in granites are discussed. [ABSTRACT FROM AUTHOR]

The transfer process of ecotoxic agents through a membrane is studied by the example of pesticides widely used in agriculture (lontrel, zenkor, bazagran, roundup, kuzagard, and setoksidim) and of lontrel complexes with cobalt and copper. All the compounds examined penetrate through the phosphatidylcholine membranes of liposomes. The kinetics of this process is studied by monitoring the rate of fluorescence quenching of ε-adenosine triphosphoric acid inside liposomes. On the basis of data obtained, a mathematical model of the process is proposed and the constants of mass transfer are calculated. [ABSTRACT FROM AUTHOR]

The paper presents the first data obtained on topaz granites from dikes in columbite-bearing granites of the Kokchetav block, northern Kazakhstan. The columbite-bearing granites (398 ± 3 Ma, Rb-Sr method) compose large massifs and ubiquitously contain columbite as an accessory mineral in amounts from a few to a few dozen grams per ton. The topaz granites make up dikes up to 70–100 m long and 0.4–1.5 m thick, which have sharp contacts with the host granites. The composition of the topaz granites is as follows: albite ∼50%, potassic feldspar ∼24–26%, quartz ∼20%, topaz 3–5%, biotite and muscovite ∼1%. Topaz occurs in inner contact zones in the form of large (3–4 cm) crystals, which grew inward from dike contacts and is ubiquitous in the fine-grained groundmass as small (no larger than 0.05 mm) crystals. The ore minerals in the topaz granites (zircon, thorite, bastnaesite, Y-cerite, monazite, Y-fluorite, W-ixiolite, tantalite, columbite, and uraninite) developed as very small grains, which can be identified only under a microprobe and electron microscope. W-ixiolite was found only in topaz crystals. The topaz granites are rich in albite, contain Na > K and F concentrations from 0.2 to 0.97 wt %. Compared to the host columbite-bearing granites, the topaz granites are 10–15 times richer in Ta and Li, 3-8 times richer in Rb, Cs, Nb, Sn, F, and Be but 1.2–2 times poorer in U, Th, and REE. The columbite-bearing granites have Ta/Nb = 1: 20, while this ratio in the topaz granites is 1: 3, a fact highlighting the enrichment of the granites in Ta and their geochemical autonomy with respect to columbite-bearing granites. [ABSTRACT FROM AUTHOR]

The hydrothermal Mo-U deposits of the Strel’tsovka ore field, unique in reserves, are localized in the Late Mesozoic caldera of the same name. The consideration of geochemical processes that controlled uranium transfer by ore-bearing fluids and its precipitation in orebodies has shown that a nonstationary temperature distribution could have exerted a substantial effect on ore formation. The temperature field in the Strel’tsovka caldera, which was caused by a shallow-seated magma chamber that existed beneath the caldera by the onset of the ore stage, was simulated by mathematical modeling. A one-dimensional nonstationary model of conductive heat transfer taking into account the latent heat of magmatic melt crystallization was used. The problem was solved with the finite difference method. It has been established that, at optimal parameters of the model, the magma chamber would have completely crystallized in 56 ka; the maximum estimate is 133 ka. Three million years after emplacement of the granitic intrusion, the related thermal anomaly in the upper crust should have disappeared. The results obtained indicate that granitic melt of this chamber could not have been a source of uranium-bearing solutions that formed deposits 5 Ma after the cessation of magmatic activity. [ABSTRACT FROM AUTHOR]

The principal aspects of reconstruction of conditions and paths of fluid migration in massifs of crystalline rocks are considered. The spatiotemporal relationships between stress fields, brittle failure, and migration of radionuclides are discussed. The main attention is focused on the staged character of tectonic events, fluid circulation conditions, and the sequence of uranium mineral formation as determined with structural, geological, tectonophysical, petrophysical, petrographic, mineralogical and geochemical, microstructural, microthermometric, and radiographic methods. As is exemplified in uranium deposits and massifs of silicic igneous rocks, the comprehensive consideration of the tectonodynamics of fluid-conducting structural elements and radionuclide migration is necessary for providing insights into the localization and redistribution of uranium, the PT conditions of uranium ore formation, and the forecast for long-term safety of disposal of radioactive wastes in crystalline rocks. [ABSTRACT FROM AUTHOR]

The experimental data on the generation of metal and semiconductor nanoparticles during their laser ablation in liquids is reviewed. The dependence of the morphology of noble metal nanoparticles on the liquid type and laser parameters is discussed. The data on the kinetics of the formation of alloyed Au-Ag nanoparticles under laser irradiation of a mixture of colloid solutions of individual nanoparticles are presented. The effect of femtosecond laser beam self-action during metal ablation in liquids via the second harmonic generation at Ag nanoclusters is discussed. The data on the generation of core-shell nanoparticles during laser ablation of alloys and in the presence of the chemical interaction of formed nanoparticles with surrounding liquid are presented. It was shown that laser ablation of CdS and ZnSe crystals leads to the formation of quantum dots of these semiconductors in solution. The parameters controlling the properties of nanoparticles during ablation in liquids and possible applications of the method are discussed. [ABSTRACT FROM AUTHOR]

Based on extensive voluminous literary data, a comparison of the Harpacticoida faunas of the Black Sea; the Sea of Azov; and the Caspian, Baltic, Barents, White, Kara, Laptev, and East Siberian seas, as well as of the Spitsbergen and Franz Josef Land areas, was performed. The degree of community and specificity of the faunas of different regions was estimated and the general patterns of the latitudinal variability in the species compositions were revealed. It is shown that the Harpacticoida faunas of geographically separated areas and even those isolated from each other such as those of the Black Sea, the Sea of Azov, and the Caspian Sea are rather similar; an hypothesis is put forward that this is caused by the common history of the seas’ formation. In contrast, the faunas of the Arctic seas (Barents, White, Kara, Laptev, and East Siberian), whose water areas are closely connected, are considerably different, being related to their different temperature conditions. [ABSTRACT FROM AUTHOR]

During the exploration of the K2O-Bi2O3-As2O5 system, single crystals of a new arsenate of trivalent bismuth, K3Bi5(AsO4) 6, were isolated by solid state reaction at 600°C. The title compound crystallizes in the monoclinic system, space group C2/c (N°15) with a = 18.257(2) Å, b = 7.260(1) Å, c = 20.130(4) Å, β = 119.86(1)°, and Z = 4. Its structure consists of a three-dimensional framework made up of AsO4 tetrahedra and BiO6 and BiO7 polyhedra sharing edges and corners, delimiting cavities wherein K+ ions reside. This compound exhibits a potassium ion conductivity but with rather low conductivity value. [ABSTRACT FROM AUTHOR]

The ambiguity of genetic interpretations of uranium ore formation at Mo-U deposits of the Strel’tsovka ore field led us to perform additional geochemical, mineralogical, and thermobarogeochemical studies. As a result, it has been established that closely related U and F were progressively gained in the Late Mesozoic volcanic rocks from the older basic volcanics (170 Ma) to the younger silicic igneous rocks (140 Ma). The Early Cretaceous postmagmatic hydrothermal epoch (140–125 Ma) is subdivided into preore, uranium ore, and first and second postore stages. The primary brannerite-pitchblende ore was formed in association with fluorite. At the first postore stage, this assemblage was replaced by a U-Si metagel, which was previously identified as coffinite. The metagel shows a wide compositional variation; its fine structure has been studied. The preore metasomatic alteration and related veined mineralization were formed under the effect of sodium (bicarbonate)-chloride solution at a temperature of 250–200°C. The uranium ore formation began with albitization and hematitization of rocks affected by supercritical fluid at 530–500°C; brannerite and pitchblende precipitated at 350–300°C. The chondrite-normalized REE patterns of pitchblende hosted in trachybasalt, trachydacite, and granite demonstrate a pronounced Sm-Nd discontinuity and a statistically significant tetrad effect of W type. These attributes were not established in REE patterns of rhyolites derived from the upper crustal magma chamber. This circumstance and a chronological gap of 5 Ma between silicic volcanism and ore formation do not allow us to suggest that uranium was derived from this magma chamber. According to the proposed model, the evolved silicic Li-F magma was a source of uranium. U4+, together with REE, was fractionated into the fluid phase as complex fluoride compounds. The uranium mineralization was deposited at a temperature barrier. It is suggested that hydromica alteration and the formation of molybdenum mineralization were genetically unrelated to the uranium ore formation. [ABSTRACT FROM AUTHOR]

First U-Pb zircon isotopic dates were obtained for rocks from the Devonian volcanic belt in Kazakhstan. The granodiorites of the Zhabden Massif (Karamendinskii Complex) were dated at 391 ± 1 Ma. The Sm-Nd isotopic system of a whole-rock granodiorite sample (ɛNd = 2.5) suggests a high percentage of mantle material in the initial granite melt, which is in good agreement with known data on granitoids in neighboring territories in Kazakhstan. With regard for the isotopic dates obtained for the granodiorites, the material of their source was separated from the mantle at 946 Ma. [ABSTRACT FROM AUTHOR]

Eu3+-doped (1–12 mol%) calcium hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) powders were synthesized by a precipitation method and their photoluminescence (PL) properties were investigated. Eu has a limited solubility in HA and Eu2O3 was detected by X-ray diffraction above 3% doping, whereas a nearly single β-phase was obtained up to 6% doping in TCP but EuPO4 appeared in the 12% Eu-doped specimen. Electron spin resonance measurement confirmed that europium ions exist as Eu3+ in both samples. Eu3+-doped HA exhibited a strong emission at 575 nm with several minor peaks at 610–640 nm and Eu3+-doped TCP had an intense emission at 613 nm with secondary peaks at 590–600 nm, which were consistent with the earlier reports determined at low temperatures. In Eu-doped TCP, the PL intensity increased with increasing calcination temperature without phase transformation. The more the Eu added, the higher the PL intensity obtained in both cases. [ABSTRACT FROM AUTHOR]

It is found that the weakly divergent beam formed around the reference ray with minimal cycle length does not stand out in intensity against the background of the total field. It is shown that, under the same conditions, another beam stands out in intensity: it is the caustic beam composed of the system of caustic lines, which are the envelopes of the family of rays forming the weakly divergent beam. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new method allowing us to calculate the signal-to-noise and signal-to-interference ratios at the output of a nonlinear inertialess element in the specified frequency band when frequency-separated narrow-band signal and interference mixed with narrow-band Gaussian noise are applied to its input. The influence of out-of-band interference on the output signal-to-noise ratio of the radio receiver operated in blocking mode is analyzed for the case of pulsed signal and interference. [ABSTRACT FROM AUTHOR]

Data on the synthesis, complexing ability, practical applications, and biological activity of dibenzotetraazamacroheterocycles of the azacrown ether, amide, and azomethinedibenzotetraazacycloalkane types and also dibenzotetraazamacroheterocycles containing amide and azomethine fragments are classified and analyzed. [ABSTRACT FROM AUTHOR]

Research results published in 1990-2002 on acid hydrolysis of apple protopectin and sunflower calathides were reviewed. Decomposition products and the biological activity of the resulting pectinic substances were identified. [ABSTRACT FROM AUTHOR]

The viral particles (about 30 nm in diameter) that contain dsRNAs (2.0 and 6.3 kbp) encapsidated by a coat of protein were detected in a mycocin-secreting strain of Cystofilobasidium infirmominiatum isolated from plants in an oak forest (Moscow region). The mycocin with a molecular mass above 15 kDa is fungicidal (maximum activity at pH 4.5) and active mainly against some species of the Cystofilobasidiales and Filobasidiales (‘Cryptococcus aerius’ clade). Curing by incubation at elevated temperature resulted in the concomitant loss of dsRNAs and mycocinogenic activity, and cured derivatives became sensitive to the mycocin produced by the parent strain. [Copyright &y& Elsevier]

Results of measurements of the temperature dependence of the absorption spectra of YBa[SUB2]Cu[SUB3]O[SUB6+x] films in the antiferromagnetic and metallic (superconducting, T[SUBc] = 88 K) phases are presented. The temperature evolution of the absorption bands, which are diagnostic for the electron and spin correlations and the degree of metallization (oxygen-copper hybridization), is investigated in the energy region 1.3-2.6 eV. It is shown that in the metallic phase in the pseudogap state below T∗ = 120 ± 10 K there is a sharp rise of these absorption bands characteristic of the antiferromagnetic (AF) phase, including the electron-two-magnon (A + J) band, which reflects the development of strong AF correlations. In contrast to the insulator, here the (A + J) band has a fine structure due to the creation of both interacting and noninteracting magnons, and it coexists with the bands due to the strong metallization. The results demonstrate phase separation ar T[SUBc] < T < T∗, with the formation of a stripe superstructure consisting of metallic and insulating (with short-range antiferromagnetic ordering) regions. This superstructure is preserved in the superconducting state, and an additional enhancement of the AF correlations occurs at the superconducting transition. Taken together, the results provide independent optical evidence of the undoubted participation of AF correlations in the superconductivity. [ABSTRACT FROM AUTHOR]

Mycocin production was demonstrated in Trichosporon pullulans, which is a dominant member of the yeast community in tree exudates released in the early spring (spring sap). Mycocin synthesis was associated with dsRNA-containing virus-like particles. Natural strains of Tr. pullulans free of dsRNA have a sensitive phenotype, and a mycocinogenic strain cured of small dsRNA becomes sensitive to its own mycocin. The mycocin studied was active against isolates from tree exudations only but not against Tr. pullulans strains isolated from other habitats. No activity was found against any other yeast species. The competitive advantage of mycocin production at the population level was exemplified by the predominance of mycocinogenic strains both in laboratory model communities and in natural populations. [Copyright &y& Elsevier]

Dynamics of the spectral intensity oscillations that occur in the vertical plane because of the time variability of the medium along the propagation path is described. The errors arising in measuring the frequency shifts of the interference structure are considered. For low-frequency broadband signals received on a stationary propagation path, experimental data on the shifts of their frequency spectra due to the variation of the reception depth are presented. The number of interfering modes and their arrival directions in the vertical plane are estimated from the measured frequency shifts of the spectral intensity oscillation. [ABSTRACT FROM AUTHOR]