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Monitoring of the level of different flammable liquids is examined, including that of petroleum products in high capacity tanks, as well as during pumping, at oil storage depots. The operating characteristics of most level measurement devices do not meet customer specifications in practice. Commercial accounting for petroleum products requires more precise measurements and more stable operation of the liquid level gauges set up for factory conditions and spark-explosion safe operation. The development of a spark-explosion-safe device with a hydrostatic fiber-optic liquid level sensor and a position-sensitive detector is validated. For continuous monitoring of liquid level, it is proposed that measurements be made of the displacement of the bottom of a bellows under the influence of the hydrostatic pressure created by a column of the liquid with automatic compensation of the change in the density of the liquid. Compensation is carried out with a small buoy with an optical triangulation sensor for small displacements installed in it with a position-sensitive detector. The use of a bellows for suspension of the buoy is justified theoretically. The operating principle of the fiber-optic liquid level sensor is described. The calculated absolute measurement error for the level of a petroleum product is less than ±1 mm. The spark-explosion hazard of the device is reduced because there are no wires in the measurement zone, so the proposed device can be used in different fi re-hazardous media with a corresponding spark safety level confirmed by certification. more...

The dephosphorization of a manganese oxide concentrate with an increased phosphorus content is experimentally studied by blowing a manganese-containing melt with carbon monoxide in the temperature range 1400–1560°C. The reaction of gaseous carbon monoxide with phosphorus oxide dissolved in a manganese-containing melt begins to develop. The dephosphorization leads to a substantial decrease in the phosphorus content in a manganese-containing melt. A new method for the dephosphorization of manganese-containing products is developed. The method has no analogs and makes it possible to involve domestic manganese ores in production. more...

Results are provided a study of the structure, physical properties, mechanical properties, and long-term strength of a new heat-resistant, low-nickel, nitrogen-containing steel 40Kh25N12G4SABL and its modifications. Compared with those used currently in this field the new steel has a nickel content reduced by 40%, improved mechanical properties at room and elevated temperatures, and increased values for creep strength and heat resistance. more...

This article presents the rationale and methodology for developing an intrinsically safe device, namely, a hydrostatic fiber optic sensor with a position-sensitive detector for monitoring the level of oil products in large-capacity tanks at oil depots and during pumping in a raw material warehouses. This device suitable for continuous monitoring of the liquid level, based on the measurement of a hydrostatic column of liquid with automatic offset of changes in the density of the liquid. Offset is carried out by means of a displacer (a fully submerged float), inside which a housing with a position-sensitive detector (PSD) is integrated. Theoretical validation of the bellows suspension usage for a displacer is given. During filling a container with a liquid whose level is measured, liquid bellows, the movement of which is recorded by an optical triangulation sensor using the reflected infrared ray incident on the bottom of the bellows. The principle of the triangulation sensor operation is based on the geometric properties of the triangles. The pulses of infrared radiation come through a fiber optic cable. In order to measure the movement of the surface (the bottom of the bellows) by measuring the movement of the reflected beam, a position-sensitive detector is used, which is located in a remote controller. In this device for the intrinsic safety problem solution, optical inputs of a fiber optic flat cable are located in the active zone of the sensor, which is connected to the optical inputs of a position-sensitive detector, operated on the principles of photoelectric effect. The light spot moving along the sensitive zone and converted by the detector into a one-dimensional signal proportional to the distance to the object. hydrostatically applies pressure over the entire effective area of the measuring more...

Aqueous solutions of guanylurea hydrogen phosphite (GUHP) have been synthesized. The temperature dependence of equilibrium GUHP concentration in water was obtained. The change in the density of aqueous GUHP solutions with a change in their concentration was investigated. The influence of the solution pH on the GUHP solubility in water in the temperature range of +25–45°C was analyzed. The crystallization range of monoclinic GUHP crystals, belonging to the sp. gr. Cc, was determined. GUHP crystals were grown using different methods, based on cooling or maintaining a constant temperature, with mixing aqueous solutions or without mixing. The properties of the grown crystals in the optical and THz ranges were investigated. more...

The monoclinic crystal of guanylurea(1+) hydrogen phosphite (GUHP) is a novel efficient nonlinear-optical medium having high χ(3) and χ(2) values. We used THz-TDS with high polarization contrast to study the absorption coefficient and the refractive index of the crystal in the range of 0.2—1.5 THz. We found that the dielectric frame xyz at 1 THz is rotated 16 degrees from the visible range. Absorption spectra show peaks at 0.93, 1.02, and 1.45 THz representing high-Q resonances. The last two modes show very high Raman activity that can be associated with the interlayer collective movement of the crystal. We assume that GUHP has the potential to be a basis for active and passive terahertz devices manufacturing. more...

We report on the creation and investigation of a new class of crystals for nonlinear optical applications in the NIR-THz range, requiring non-critical phase matching. A narrowband two-frequency THz radiation source is demonstrated. The spectral properties of THz radiation emitted via optical nonlinear rectification in a semiorganic molecular crystal guanylurea hydrogen phosphite (GUHP) are described in relation to the crystal axis orientation. more...

Polymer-based magnetoelectric composite materials have attracted a lot of attention due to their high potential in various types of applications as magnetic field sensors, energy harvesting, and biomedical devices. Current researches are focused on the increase in the efficiency of magnetoelectric transformation. In this work, a new strategy of arrangement of clusters of magnetic nanoparticles by an external magnetic field in PVDF and PFVD-TrFE matrixes is proposed to increase the voltage coefficient (αME) of the magnetoelectric effect. Another strategy is the use of 3-component composites through the inclusion of piezoelectric BaTiO3 particles. Developed strategies allow us to increase the αME value from ~5 mV/cm·Oe for the composite of randomly distributed CoFe2O4 nanoparticles in PVDF matrix to ~18.5 mV/cm·Oe for a composite of magnetic particles in PVDF-TrFE matrix with 5%wt of piezoelectric particles. The applicability of such materials as bioactive surface is demonstrated on neural crest stem cell cultures. more...

The monoclinic organic crystal of guanylurea hydrogen phosphite (GUHP) was considered. The absorption and refractive properties of an optically negative biaxial crystal were investigated. The terahertz time-domain spectroscopy under cryogenic conditions was carried out for observation of the temperature dependence of the phonon structure of GUHP crystal. more...

Highly concentrated dispersions of few-layer graphene stabilized by amphiphilic block copolymer Pluronic F-108 are obtained. According to transmission electron and atomic force microscopy, the thickness of the graphene particles is on average from one to ten layers and their lateral sizes vary from 150 nm to 1 μm. Using these dispersions, new chitosan-based film composites with the filler content up to 5 wt % are obtained; the electrical conductivity of these composites reaches 4.3 × 10–1 S/cm. more...

The article discusses the current state of research concerning transition metal polysulfides of groups 4–6. We review the data on the preparation of nanoscale polychalcogenides from elements or molecular precursors and by exfoliating bulk samples. Particular attention is paid to the ultrasound liquid-phase exfoliation of typical polysulfides such as NbS3, TaS3, VS4. The main feature of this class of compounds is the presence of disulfide groups (S–S)2– which determine most important structural, physical, and chemical properties of these compounds to make them effective catalysts and electrodes in electrochemical cells. more...

Hydrated lanthanum fluoride powders, both undoped, and doped with erbium and ytterbium fluorides (to a total content of 6–28 mol %), of the general formula RF3 · nH2O (n = 0.30 ± 0.01), crystallizing in the hexagonal system, were obtained by coprecipitation from aqueous solutions of the corresponding nitrates by the interaction with hydrofluoric acid. The dehydration is completed at 380°C. At 600°C, the concentrated solid solution decomposes to precipitate a phase with the structure of orthorhombic YF3. The efficiency of the upconversion luminescence of the powders, excited at a wavelength of 974 nm, is low. more...

Optimal combination of stem cells and biocompatible support material is a promising strategy for successful tissue engineering. The required differentiation of stem cells is crucial for functionality of engineered tissues and can be regulated by chemical and physical cues. Here we examined how boundary cap neural crest stem cells (bNCSCs) are affected when cultured in the same medium, but on collagen- or laminin-polyacrylamide (PAA) scaffolds of different stiffness (0.5, 1, or similar to 7 kPa). bNCSCs displayed marked differences in their ability to attach, maintain a large cell population and differentiate, depending on scaffold stiffness. These findings show that the design of physical cues is an important parameter to achieve optimal stem cell properties for tissue repair and engineering. more...

Highly concentrated dispersions of polyvinylpyrrolidone-stabilized graphene were prepared. Using transmission electron microscopy, it was found that the graphene particles consisted, on average, of one to four layers, with the lateral size of 50–400 nm. From these dispersions, new film composites of chitosan with the filler content up to 4 wt % characteristic of electrical conductivity as high as 1.9 × 10–2 S/cm were formed. more...

In the past few years, a lot of attention has been directed to the synthesis of nanosized transition metal chalcogenides and their composites with noble metal nanoparticles. Materials of this type demonstrate enhanced properties in energy storage, catalysis and surface enhanced Raman spectroscopy devices. Although layered transition metal dichalcogenides are well studied, some other chalcogenides, namely layered niobium trisulfide (NbS3) and quasi-onedimensional vanadium tetrasulfide (VS4), have received less attention by comparison. In this work, we synthesized nanocomposites based on 2D niobium trisulfide and 1D vanadium tetrasulfide with gold nanoparticles and investigated their morphology and phase composition by transmission electron microscopy and X-Ray diffraction. more...

The Mo–S phase diagram exhibits two stable compounds: well-recognized layered molybdenum disulfide MoS2 and less studied molybdenum sesquisulfide Mo2S3. Here, we build a theoretical framework for the exfoliation of Mo2S3 based on density functional theory calculations and further experimentally prove its dispersibility under ultrasonic treatment and demonstrate its potential for use in gas detectors. First, we report computational studies of both Mo2S3 exfoliation and molecular adsorption on the Mo2S3 surface. The calculations reveal the preferential direction for the fragmentation of the Mo2S3 crystal along the (01) plane and, likely, chemisorptive interaction of solvent molecules, such as H2O or DMSO, with the (01) Mo2S3 surface. Next, we experimentally study the sonication of bulk Mo2S3 samples in organic solvents and show that, indeed, they may be converted to colloidal nanosized sheets. Solid particles in the dispersions retain the initial Mo2S3 crystal structure and have the shape of plates with typical thicknesses of 5–30 nm and lateral sizes of 100–400 nm. Finally, we investigate the gas sensing properties of the Mo2S3 films deposited from the dispersions towards moisture gas and several representative volatile organic compounds. more...

The electronic structure and lattice parameters of several quasi-one-dimensional compounds–known VS4, NbCl4, and NbS3 and hypothetical NbS4 and VS3–are obtained using density functional theory. Comparative analysis of chemical bonding and charge distribution in all these compounds reveals the possible origin of the structural instability of NbS4 and VS3. more...

Semiconductor based CuS-rGO nanocomposite materials have drawn a considerable attention towards photodegradation of organic dye molecules due to the low band gap (∼2.5 eV) of CuS nanoparticles. Presence of reduced graphene oxide (rGO) in CuS-rGO nanocomposite induced synergistic effect between CuS and rGO sheets which led towards better photocatalytic degradation efficiency as compared to CuS nanoparticles (without rGO support) and rGO alone. In this study CuS-rGO nanocomposite was synthesized by a simple microwave irradiation technique and characterized by High resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Photoluminescence (PL) spectroscopy studies. The synthesized nanocomposite behaved as efficient photocatalyst towards diazo Congo Red (CR) dye molecule under natural sunlight irradiation with a maximum degradation efficiency of 98.76%. Effect of initial dye concentration, catalyst loading, pH of the reaction medium and role of different inorganic ions as well as the amount of graphene content in the photocatalyst on photocatalytic degradation of CR dye molecule was investigated in this study. The present study also focussed on the effect of different inorganic ions on the surface potential of the photocatalyst and their effect on the degradation process. more...

The paper presents the results of studies on the growth of Rb2NiC14-2H2Ocrystals and the study of their properties. The conditions for the reproducible production of Rb2NiC14-2H2Osingle crystals by the method of controlled decrease of solubility are determined. The optical and thermal properties of crystals obtained in this way were studied. more...

Low-dimensional transition metal polysulfides are an interesting family of compounds, which have in common the presence of disulfide groups S-S. This feature dictates their unusual chemistry and electrochemistry. We have optimized synthetic procedures and systematically studied sulfides of IV-VI groups, such as TiS 3 , ZrS 3 , VS 4 , NbS 3 , CrS 3 etc. in their bulk and nanosized forms. The nanosized samples were prepared by liquid-phase exfoliation of the bulk counterparts. Our preliminary studies show the promise of such materials for a variety of applications, including transistors, Li-ion batteries, and photocatalysis. more...

Possible application of tungsten dichalcogenides as gas-sensing elements is discussed in this paper. The experimental results on sensitivity of pristine and niobium doped WS2 and WSe2 to acetone and ethanol gases are presented. Polycrystalline powder specimens were obtained by high temperature solid-state synthesis from the stoichiometric mixture of pure elements. Two types of samples were studied: 1) tablets pressed at 1.5 GPa to form bulk samples and 2) thin films prepared from 35% ethanol-water colloidal dispersions by their filtration onto membrane filters (pore diameter is 20 nm). The electrical resistances of the samples were shown to be increased in the presence of ethanol and acetone gases at room temperature, thereby revealing positive response to reducing gases. more...

In the presence of a strong electromagnetic field, the spectrum of charge carriers in a Dirac material is changed. The interaction of a linearly polarized field with electrons in the Dirac material leads to anisotropy. The anisotropy axis coincides with the direction of the electric field in the linearly polarized wave. We show that the major contribution to the interaction of electrons with an electromagnetic field comes from elastic scattering processes, whereas taking into account inelastic processes leads to an error of about 2%. more...

A ceramic with dense nanosize structure was obtained by conventional sintering of samples formed from nanosize Si3N4 powder with Al2O3 and Y2O3 additives by cold isostatic pressing. The microstructure and density of the ceramic obtained were investigated. The technological conditions for obtaining silicon nitride ceramic that give the optimal combination of fine-grain submicron structure and high density were determined. more...

We study low-mobility 2D electron gas in GaAs quantum well in tilted magnetic field up to 45 T. Analyzing the behavior of the Shubnikov-de Haas (SdH) oscillations we obtain the value of g-factor, | g | = 0.9 ± 0.1 , which is noticeably larger than that predicted theoretically and obtained from optical experiments. Possible reasons of the discrepancy are discussed. more...

The effect of NTPS inhibitor on the corrosion behavior of magnesium alloys with various contents of alloying components is studied. NTPS is found to be an effective corrosion inhibitor in the absence of energizing, but under the anodic polarization, it does not produce any noticeable effect on the self-dissolution process. Comparative analysis of the processes proceeding at the anodic dissolution of magnesium and electron-microscopic studies of the specimens showed that the dissolution is accelerated due to the active-surface development. A supposition that, under the effect of a constant anodic current, the development and formation of the magnesium surface relief takes place at the initial polarization stage is put forward. more...

The monitoring of poly(di-n-hexylgermane) (PDHG) optical spectra in a variety of structures ranging from a polymer film to nanosize polymer filled porous media was performed by optical spectroscopy in the temperature range from 5 to 250 K. The PDHG nanocomposites were fabricated by insertion of PDHG polymers into SBA-15 mesoporous silica and SiO2 porous films. Temperature dependence of the PDHG film fluorescence spectra shows that the polymer generally has disordered conformation while the random ordered segments behave as defects. The spectra of the composites correspond to the polymer chains with even less ordered segments and the aggregates of such chains. This is confirmed by the absence of the thermochromic transition in the composites contrary to the film. The difference between the optical spectra of the film and the composites is due to a decrease of both the intermolecular and exciton-phonon interactions in the composites. It was shown that the polymer chains in the SiO2 pores are more ordered. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) more...

We present a study of fluorescence (5–250)K and FTIR spectra of poly(di-n-hexylsilane) incorporated into nanoporous silicas (MCM-41 and SBA-15 types) and SiO2 aerosil. It is shown that the essential local conformation change of the polymer chain occurs only for the polymer embedded into and oriented in small-diameter pores with a large number of Si–OH groups on the surface of the walls. The competition between the polymer-surface and the polymer-polymer interactions leads to the restructuring of a polymer incorporated into the large pores of SBA-15 where the separarate polymer chain having trans- and gauche-conformations as well as the aggregates can be found. The presence of the gauche-conformation is confirmed by the shift of CHa2 and CHs2 stretching vibrations and, additionally, by the redistrubution of their intensity with increasing the pore diameter. more...

The monitoring of poly(di-n-hexylgermane) (PDHG) optical spectra in a variety of structures ranging from a bulk film to a nanosize polymer confined into a nanopore of SBA-15 was performed using the fluorescence and fluorescence excitation spectra in the temperature range from 5 to 240 K as well as the absorption and FTIR spectra at room temperature. The observed data were compared with those obtained for poly(di-n-hexylsilane). It was shown that PDHG film absorption and fluorescence spectra strongly depend on the polymer thickness and consist of a number of bands which were assigned to centers with different amount of trans- and gauche- conformers of the polymer chains. Conformations of the polymer chains found in a thin film and in a 10 nm pore are similar while differing from the conformations of a thick film. Optical spectra of the confined PDHG are blue-shifted relative to those of a thin film. The PDHG polymer chain conformation becomes disordered with the decrease of the polymer film thickness and the nanopore size from 10 to 6 nm. more...

Photoluminescence and photoluminescence excitation spectra of nanosize poly(di-n-hexylsilane) embedded in the SBA-15 with 6 nm diameter pore were investigated in the temperature range of 10–290 K. We clearly demonstrate the thermochromic transition at 265 K between trans- and gauche- conformations of an isolated polymer chains embedded in the nanoporous material. Existence of the polymer chain having trans-conformation in a separate pore of 6 nm diameter was prooved. The location and packing of the polymer chains in this pore was simulated using the quantum chemistry calculations in the cluster approximation. The investigation of the polarized luminescence dynamics of the nanosize polymer with pore diameters of 6 and 10 nm has shown that the polymer chains are aligned by embedding. more...

A thin-film YBa2Cu3O7−δ sample has been investigated with regard to its irreversibility field at low temperatures. For these investigations, the magnetic-field dependence of the electrical resistance R(H) was measured at various temperatures in pulsed magnetic fields up to 50 T. These curves show an unusual, very rapid increase of R even at low fields. We describe a method of extracting Hirr that is comparable to measurements in static magnetic fields. The irreversibility line shows the same, nearly linear behaviour at low temperatures as bulk YBa2Cu3O7−δ samples and a power-law dependence at higher temperatures. These two regions are also clearly visible in pinning force plots. more...

In single crystals of A-site disordered perovskite manganites R1−xAExMnO3 (R = Sm, Gd, Eu, AE = Ba, Sr, x = 0.5, 0.45), we have observed the spin-glass behaviour. Applying pulsed high magnetic fields, a metamagnetic phase transition was observed in some samples, whereas in other samples, the magnetisation was just a smoothly varying function of magnetic field up to the saturation. The difference between the two types of behaviour seems to arise from the difference in the average ionic radius of the A-site ions and the disorder in the A-site layers. In the metamagnetic transition, magnetisation hysteresis was found to be smaller as the field sweep rate is faster, which is contrary to the ordinary spin relaxation phenomena. more...

We discuss further developments in the application of Finite Element Analysis (FEA) to the design of pulsed magnets on the basis of our latest coil design. Two areas are addressed. Firstly, we present results concerning the current distribution in the conductor during the discharge. Eddy current heating leads to thermal gradients across the layers and in the conductor; the results are compared with well established analytical codes. Significantly higher stresses result due to temperature gradients and nonuniform current distribution, which can be partly offset by pre-stressing reinforcement fibers. Secondly, we report progress in designs that facilitate much more rapid cool-downs for pulsed magnets, which can sometimes take in the order of hours between pulses.. We show that cool-down times of 20 minutes or less are achievable using copper discs (designed using FEA) that will not support eddy currents. more...

Fluorescence and excitation spectra (T=5–290K) of nanosized silicon-organic polymers poly(di-n-hexylsilane) and poly(methyl(phenyl)silane) incorporated into porous silica materials MCM-41 and SBA-15 have been studied with varying pore diameter from 2.8to10nm. The controlled variation of the pore diameter in a wide range (2.8–10nm) permitted us, for the first time, to investigate the optical properties of the polymers on their transition from isolated macromolecules to a film. It is found that this transition depends on polymer type and occurs via the formation of new spatially independent structures of the polymers not observed in the spectra of the film, namely, via the formation of disordered and (or) ordered conformations of polymer chains and clusters. more...

The magnetoresistance (MR) of La 0.7 Sr 0.3 MnO 3 and La 0.7 Ca 0.3 MnO 3 epitaxial films and of a La 0.75 Sr 0.25 MnO 3 single crystal were measured in pulsed magnetic fields up to 50 T over a wide temperature range. MR data have been analysed utilizing the recently suggested Brillouin scaling model. The model applies well in the paramagnetic state, where results prove the presence of superparamagnetic clusters. Near the ferromagnetic ordering temperature, systematic deviations in particular in larger fields indicate that the simple model fails there. The temperature-dependent cluster size parameter is similar for our samples, but differs essentially from that obtained earlier for half-doped manganites. more...

Alloyed ( Mn 1 - x Fe x ) Au 2 ribbons ( x = 0 –0.075) show a complex dependence of magnetization and magnetoresistivity on composition, magnetic field, and temperature. This is associated with the helimagnetism of MnAu 2 and the field-driven transition from helix to fan spin-structure. The threshold field H thr for this metamagnetic transition strongly depends on x. Neutron diffraction shows that the periodicity length of the helix increases with increasing iron contents x 0.075 . For x = 0.05 a transition from the helical ground-state to a collinear ferromagnetic structure takes place at 150 K; for x = 0.075 only a ferromagnetic order is found. more...

Resistance data of a non-textured polycrystalline La 0.7 Sr 0.3 MnO 3 thin film have been measured in magnetic fields up to 47 T between 4.2 and 300 K. The observed linear field dependence of the magnetoconductance at temperatures T⩽100 K and magnetic fields above 1 T is consistent with the transport model of second-order tunneling through grain boundaries [Phys. Rev. Lett. 82 (1999) 4508]. The lack of saturation up to 47 T and the estimated temperature dependence of the grain boundary susceptibility (derived from the conductance slopes d G /d H ) indicate strong antiferromagnetic coupling of the grain boundary spins. more...

Similarly to transition metal dichalcogenides akin to MoS2, transition metal polysulfides like tri- and tetrachalcogenide materials are nowadays incorporated into catalysts and composites used for energy conversion and storage, etc. However, polysulfide structures feature SS units, which make them strikingly different from the widely known MoS2 and other dichalcogenides. At the same time, their surface chemistry and its relation to properties are very little studied. Reported here is one of the first observations on the oxidizing properties of disulfide bridges (SS)2− forming surfaces in polysulfide crystals. Upon interaction with silver salts or silver nanoparticles, MoS2 acts as most supports, that is, it stabilizes metallic Ag at its surface; in contrast, curiously, patronite VS4 and NbS3 stabilize Ag2S nanoparticles under identical reducing conditions. The Ag/MoS2, Ag2S/NbS3, and Ag2S/VS4 samples are characterized with X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Apparently, the unexpected formation of Ag2S is due to complex redox processes involving disulfide fragments –S–S– of nanorods VS4 or nanoribbons NbS3, which are absent in MoS2 nanosheets. This result is important for fundamental understanding of the properties of sulfur-rich surfaces and also for contributing to the number of available synthetic paths toward Ag2S nanoparticles. more...

Magnetisation and longitudinal magnetoresistance of single-crystal samples of two compositions: stoichiometric compound U3P4 and its solid solution U3(P,As)4 (with As:P ratio close to 1) were measured in pulsed magnetic fields with strength up to 47 T, and in temperatures from 4 K up to few tens of kelvins above the Curie temperatures (135 K and 181 K for both compositions, respectively). Field was always applied along a hard magnetic direction [100]. Magnetisation experiments showed no sign of expected magnetic-moment-reorientation transition and data look quantitatively similar for both compositions. On the other hand, longitudinal magnetoresistance (MR) is remarkably different for each composition. Onset of the above mentioned transition can be held responsible for broad maxima observed in MR(B) curves for U3(P,As)4. Values of magnetic field strength corresponding to these maxima follow a linear dependence on temperature. We assume that these features of MR(B) curves are due to progressive deformation of magnetic structure of U3(P,As)4 in high magnetic fields. more...

The possibility of using slip technology in production of highly porous cellular materials from alumino-borosilicate glass was demonstrated. The factors that affect the rheology and stability of the slip system and the structural and strength characteristics of the finished material were identified. The materials obtained can be used as substrates in chromatography, for treatment of liquids and gases in filtration, etc. more...

We outline a method for measuring the porosity of macroporous materials. The main advantage of this method compared with familiar methods is the significant increase in the number of materials which can be studied. This means industrial use of the method on production lines is feasible. Furthermore, the method can be used to determine parameters indirectly characterizing a porous structure (the specific surface area of materials and the adsorption-desorption isotherms). more...

White chromium cast irons are used as wear-resistant materials operating under conditions of intense abrasive and impact-abrasive wear. The high wear resistance of white chromium cast irons is determined primarily by the presence of a large amount (30% or more) of solid chromium carbides of the M7C3 type. At the same time, an important effect on their operating characteristics is exerted by the state of the metallic base, which can have various structures depending on the alloying conditions and the heat treatment. more...

The resistance relaxation of a polycrystalline ferromagnetic La0.7Sr0.3MnO3 thin film has been studied. Time-dependent resistance data R(t), recorded after field pulses of 7 and 47 T, respectively, show a pronounced relaxation of approximately logarithmic type for 10 ms more...

In this paper, the electronic transport of La(0.7)(Sr,Ca)(0.3)MnO(3) films grown by pulsed laser deposition on a LaAlO(3)(001) substrate with deep parallel structured steps and a 30° symmetric bicrystal SrTiO(3)(001) substrate have been discussed. The electronic transport properties have been related to the well-known extrinsic transport of bulk manganite compounds. The spin-glass-like behavior with a characteristic peak at 20 K and domain formation at the grain boundary is observed. Further, it has been quantified from the resonant tunneling model that mixed magnetic interactions play a significant role in the manganite films deposited on step edges. more...

On etudie les bases physicochimiques du processus de compactage et du renforcement mecanique des briques du melange vitrifiable compacte en fonction du degre hygrometrique des melanges de poudre initiaux et de la pression de pressage. On considere le mecanisme de formation des nouvelles phases cristallines dans le melange vitrifiable d'un verre E d'aluminoborosilicate sans alcalin quand il est compacte dans une presse avec des meules de diametre 520mm more...

The resistance of cold worked Cu-x wt.%Ag alloys (x = 7 and x = 24) is measured in dependence of magnetic field and temperature. The magnetoresistance (MR) in the field range 0 T ≤ B ≤ 50 T is positive and increases with magnetic field. If the magnetic field B is applied perpendicular to the transport current I, the magnetoresistance increases in the temperature range from 77 K to 300 K. The highest value of 14% for the MR is measured at 77 K and 50 T. For I {norm of matrix} B it was found that the MR is independent of the temperature in the investigated range from 77 K to 199 K. The MR is attributed to the microstructure of the alloys and appears to be independent of the Ag content of the alloys under investigation. © 2006 Elsevier Ltd. All rights reserved. more...

Results of tests of steel 30KhMA for stress relaxation and strain aging are presented. It is shown that treatment by a pulse magnetic field affects the relaxation of stresses and strain aging and can be used for changing the mechanical characteristics and raising the size stability of metalware. more...

The fluorescence and fluorescence excitation spectra, as well as the absorption spectra of a poly(di-n-hexylgermane) film and a nano-sized polymer confined into nanopores of SBA-15 with pore diameters of 6 and 10 nm, were measured in the temperature range from 5 to 250 K. The observed data were compared with those obtained for poly(di-n-hexylsilane). The optical spectra of nano-sized poly(di-n-hexylgermane) differ significantly from those of a bulk film and depend on the pore diameters. These spectra correspond to the polymer chains with even less ordered segments and interchain aggregates. This is confirmed by the absence of the thermochromic transition in the composites contrary to the film. The poly(di-n-hexylgermane) polymer chain conformation in the restricted pore volume becomes disordered with a decrease of the nanopore size from 10 to 6 nm. more...