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Silica particles containing large mesopores (5–25 nm in size) and micropores (0.6–2 nm in size) have been prepared by chemical etching of spherical micro- and mesoporous silica particles in an ammonia + water + hydrogen peroxide mixture. The specific surface area and pore volume of the particles are 510 m2/g and 0.8 cm3/g, respectively. Using capillary impregnation, we have synthesized Co3O4 (2–4 wt %) in pores of the particles. The composition and structure of the resultant materials have been studied. The Co3O4/SiO2 composite particles have been shown to be stable and exhibit catalytic activity for the CO oxidation process.

The results of structural studies of GaN nanowires containing screw dislocations are presented. It is found that the length of the Burgers vector of dislocations may reach 5 nm, i.e., exceed many times the c parameter of the gallium nitride unit cell. The formation of such dislocations leads in some cases to the occurrence of an ordered sequence of basal stacking faults with a period of 1.3–3.9 nm.

20th International Seminar on High Energy Physics, Quarks 2018, Valday, Russian Federation, 27 May 2018 - 2 Jun 2018; Physics of atomic nuclei 191(3), 362 - 367 (2018). doi:10.1134/S1063778821030078, The physics motivations and advantages of the hybrid detector complex TAIGA are presented. TAIGA aims to address gamma-ray astronomy at energies from a few TeV to several PeV units, as well as cosmic-ray physics from 100 TeV to several EeV units and astroparticle physics problems. In 2021 deployment and commissioning of the one square kilometer TAIGA setup in the Tunka valley $\sim$50 km West from Lake Baikal will be finished. The first experimental results with the TAIGA are presented., Published by AIP, New York, NY

A structural study of graphene oxide complexes with detonation nanodiamonds (particle size 4–5 nm, positive surface potential) in aqueous suspensions by small-angle neutron scattering is reported. While the pure graphene oxide suspension exhibits a completely planar structure, the grafting of detonation nanodiamond particles results in a slightly curved surface of the graphene oxide flakes. The complexes “graphene oxide–detonation nanodiamonds” washed out from free detonation nanodiamonds show that the effective curvature of the graphene oxide plane is the result of binding of detonation nanodiamonds in the form of planar aggregates.

The results of experimental studies are presented and the experience of operating the power supply of a continuous gas laser, which is based on a lithium–polymer storage battery without an intermediate voltage converter, is analyzed. The long-term (more than 4-year) operation of a high-voltage battery power supply as a component of a laser system with an open-circuit voltage of 7.76 kV, a load voltage of 6.1 kV, a load current of up to 250 A, a power higher than 1.5 MVA, and a stored energy of 550 MJ is demonstrated. The response time of the switch for disconnecting the load in the case of breakdowns in the discharge chamber did not exceed 120 μs. The results of measurements of the internal resistance of the batteries and its changes during operation are presented.

GaP as well as GaAs has face-centered cubic crystal phase at standard conditions. Despite it, GaP and GaAs nanowires frequently grow in a metastable hexagonal crystal phase called wurtzite. In this work, stable growth of GaP nanowire in the metastable phase is explained by accounting the elastic strain in the nucleus of a new layer. Crystal phase switch in heterostructured Ga(As,P) nanowire caused by heterointerface was studied theoretically and experimentally. Length of wurtzite segment after the switch of crystal phase linearly increases with nanowire diameter. Such dependence can not be explained by only kinetically driven effects. We consider such dependence as an evidence of elastic strain stabilization of the metastable phase in nanowires.

The mechanism of the azeotropy phenomenon has been established at a molecular level for the first time on the example of the HCOOH–H2O system, which has an azeotropic region. The studies are based on the regularities of the formation of heteroassociates with strong hydrogen bonds in binary systems and on the assumption that both phases of a boiling azeotropic mixture are composed of the same heteroassociates. It has been established that an aqueous formic acid solution is azeotropic if the heteroassociates composing this solution at room temperature are converted under heating into the most stable of possible heteroassociates 2НСООН ∙ 2Н2О and 2НСООН ∙ Н2О, which are retained at boiling temperature. Such restructuring in the solution leads to the maximum strengthening of intermolecular interactions and occurs with minimum energy expenditures.

Unique sulfur- and carbon- doped silicon nanoparticles, as well as partially oxidized, are obtained by nanosecond laser ablation of silicon in liquid carbon disulfide. Detailed structural, chemical, and optical characterization of these particles was performed by scanning and transmission electron microscopy, IR spectroscopy, energy dispersive X-ray spectroscopy, and Raman scattering spectroscopy. It is shown that the sulfur concentration in particles is on the order of 1 at %, owing to which they demonstrate a considerable absorption in the mid-IR region.

Gallium-nitride nanorods with a diameter of 15–40 nm and length of 50–150 nm are synthesized in monodisperse spherical mesoporous silica particles (MSMSPs) by high-temperature annealing of the Ga2O3 precursor in ammonia. The template material (a-SiO2) is selectively removed by etching the composite MSMSP/GaN particles with HF to give individual GaN nanorods. It is shown that the size of the GaN nanorods substantially exceeds the pore size of the MSMSPs (diameter ~3 nm, length ~10 nm). A possible mechanism by which GaN nanorods are formed is proposed. Redistribution of the material within the composite MSMSP/GaN particles possibly occurs via the surface diffusion of gaseous molecules within mesopores and via the diffusion of Ga and N atoms in a-SiO2.

Using X-ray diffraction analysis, transmission electron microscopy, and complex thermal analysis, it was shown that brushite crystals are formed from aqueous solutions of ammonium hydrogen phosphate and calcium nitrate. The hydrothermal treatment of brushite results in the formation of quasi-one-dimensional hydroxyapatite nanoparticles, the longitudinal size of which is about 400 nm, and the transverse size is 40 nm. It was demonstrated that hydroxyapatite nanoparticles can be used as fillers of composite matrices for tissue engineering, in particular, in bone grafting.

A protectant for hypothermic preservation of human sperm based on glass-forming water–salt systems of vital metals (magnesium, zinc, and calcium) was developed for the first time. The method of sperm preservation without preliminary washing of seminal plasma is proposed, which retains the sperm viability and sperm motility parameters comparable to the values of native sperm. The proposed protectant and method of preparing human sperm for hypothermic storage at the first stage help to slow down the metabolism as evidenced by the complete loss of sperm motility and maintenance of the nearly 100% viability of the studied sperm. Once the protectant was removed, sperm motility is restored up to 90–100% compared to the indices of native sperm.

Colloidal nanocrystals of AgInS2 were synthesized in aqueous solution using L-glutathione as a ligand. Wider bandgap semiconductor ZnS shell was deposited on the nanocrystal cores in order to enhance luminescence properties and stability. Thus prepared nanocrystals generally had an asymmetric multiple band emission spectrum. Variation of cation ratio [Ag+] to [In3+] led to a variation in the spectrum so that raising indium content caused an intensity increase of longer wavelength emission band. Photoluminescence and absorption spectroscopies, transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy were used for the sample characterization.

Glass formation in the AlCl–(CH3)2SO–H2O system was detected for the first time, the boundaries of the glass formation region were determined, and glass AlCl3 · 2.9(CH3)2SO · 4.8H2O was synthesized. The IR spectra of glass-forming solutions within the boundaries of the glass formation region and the glass AlCl3 · 2.9(CH3)2SO · 4.8H2O were recorded. It was concluded that (CH3)2SO enters the first coordination sphere of the aluminum ion through the oxygen atom. The glass AlCl3 · 2.9(CH3)2SO · 4.8H2O was studied by calorimetry, and its glass transition temperature was determined to be Tg = –32.3°C.

The regularities of mechanical activation (MA) and the reactivity of an high-energy 15Al + 85Bi2O3 (wt %) system have been studied with the use of X-ray diffraction analysis, synchronous thermal analysis, and the measurement of the ignition temperature upon the contact with a hot surface. For the nonactivated system, the intercomponent interaction has not been recorded upon their heating in a DSC cell up to 760°C. When MA is carried out, the reaction partly occurs directly in the course of grinding and upon the subsequent heating. In the course of heating at a rate of 10°C/min, the intercomponent interaction proceeds to yield Bi metal and amorphous Al2O3 in a temperature range of 350–800°C, with maxima being observed at 520 and 630°C. At temperatures below 480°C, the reaction occurs in nanolayers, as is evident from the position and shape of the melting curve obtained for formed bismuth. The effects of the duration of MA on the conversion of the components, reaction kinetics upon heating in the DSC cell, the temperature of ignition upon the contact of an activated sample with a hot surface, and the rate of mixture combustion have been determined. The optimal duration of MA, at which the ignition temperature is minimum, has been found.

Monodisperse spherical nanoporous silicon (np-Si) particles of submicrometer size are fabricated with mesoporous silica particles as a template. Silicon is synthesized within the mesopores of monodisperse silica particles by the thermal decomposition of monosilane. Then, the template material (a-SiO2) is removed by wet etching. The particles obtained have a small root-mean-square size scatter (no more than 10%) and large specific surface area (250 m2 g–1) and pore volume (0.5 cm3 g–1). It is shown that np-Si particles exhibit photoluminescence in the visible and near-IR (infrared) spectral ranges.

The heterocyclic polymer network nanocomposites obtained from bisphtalonitrile and various (from 0.03 to 5 wt %) modified silicate montmorillonite (MMT) nanolayers are studied. The nanostructure together with thermal, relaxation, and elastic properties of the composites are characterized with transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDXS), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). DMA and TGA measurements were performed in air and nitrogen mediums in the temperature range from 20 to 600–900°C. There was a various degree of exfoliation of MMT in the matrix to form single nanolayers, as well as thin and “thick” packs of MMT nanolayers, depending on its amount. We showed that there are strong constraining dynamics effects of the matrix by nanoparticles and sharp dynamic heterogeneity in the glass transition. We found that there are possibilities of complete suppression of the latter and of preservation of elastic characteristics of the composites unchanged at the temperatures from 20 to 600°C. The nanocomposites exhibit uniquely high thermal properties. A glass transition temperature of 570°C and satisfactory thermal stability are achieved with preservation of integrity of the material up to ~500°C in air and up to ∼900°C in nitrogen.

The results of studies of the structural and optical properties of two-dimensional GaSe layers grown by molecular-beam epitaxy on GaAs(001) and GaAs(112) substrates using a valve cracking cell for the Se source are reported. The influence of the MBE growth parameters (the substrate temperature, Ga flux intensity, Se/Ga incident flux ratio) on the surface morphology of the layers is studied. By means of transmission electron microscopy, electron diffraction technique, and Raman spectroscopy, it is shown that the structure of the GaSe layers corresponds to the γ-GaSe polytype. From X-ray diffraction analysis, it is established that there exist α-Ga2Se3 inclusions in the GaSe layers grown under conditions of high enrichment of the growth surface with Se.

We propose a method for finding a priori undefined structures of unknown temporal fluctuations for frequency oscillators of various intensities as part of the output signals of synchronized dynamical systems. Unlike traditional approaches, the developed method is based on the continuous wavelet transform of the observed signal and is efficient in cases when frequency characteristics of the desired pattern are close to the noise characteristics of the output signal.

The new compound Аl2(SO4)3 ⋅ 8(CH3)2SO, which cannot be prepared by direct synthesis, has been synthesized from an Аl2(SO4)3 ⋅ 8(CH3)2SO ⋅ 3Н2О glass. The compound has been identified by X-ray diffraction. Based on IR spectra, it has been concluded that the Al3+ ion has mixed coordination to dimethylsulfoxide (DMSO) molecules, and the ligands are linked to each other through the S and O atoms.

Multigraphene films have been for the first time obtained on the surface of quartz glass via carbonization of polyimide Langmuir–Blodgett films. The Raman spectra of the films show bands G and D and a broad band at 2300–3200 cm–1, which are characteristic of graphite-like films. The transmission electron microscopy demonstrated that the films are constituted by “stacks” of layers spaced by 0.36 nm. The surface resistance of the 5-nm-thick films was 1.2 ± 0.2 kΩ, and the transmittance was 87% at λ = 550 nm. The transmittance was 97% in the IR part of the spectrum and 70–80% in the UV part.

Light-emitting organic field-effect transistors (LE-FETs) on the basis of composite films that consist of perovskite nanocrystals (CsPbBr3) embedded in a matrix of conjugated polymer—polyfluorene (PFO)—have been obtained, and their electrical and optical properties have been investigated. Output and transfer current-voltage characteristics (I-Vs) of FETs based on PFO : CsPbBr3 films (component ratio 1 : 1) have a slight hysteresis at temperatures of 100–300 K and are characteristic of hole transport. The hole mobility is ∼3.3 and ∼1.9 cm2/(V s) at the modes of the saturation and low fields, respectively, at 250 K and reaches ∼5 cm2/(V s) at 100 K. It has been shown that the application of pulsed voltage to LE-FETs based on PFO : CsPbBr3 can reduce the ionic conductivity and provide electroluminescence in this structure at 300 K.

Using the example of Lake Krugloye (Mordovinskaya floodplain in the Saratov Reservoir), the changes in the physiological and biochemical parameters in two abundant fish species inhabiting the same biotopes have been comparatively analyzed. The fish under study are the aboriginal crucian carp (Carassius auratus gibelio) (Bloch, 1792) and the invasive Amur sleeper (Perccottus glenii) (Dybowski, 1877). The study reveals differences between the species in the patterns of the dynamics of body weight and contents of protein, fat, water, and caloric contents upon an increase in body length during various months of the active feeding period. Potential reasons for the differences and their consequences are discussed.

Water–electrolyte systems comprising aqueous solutions of nitrates, iodates, sulfates, acetates, orthophosphates, chlorides, and fluorides of Group I–III metals, transition metals, and lanthanides were studied. Studies of glass formation in the system Al2(SO4)3–H2O serve as an example to give an idea of the original method for studying water–electrolyte glass-forming solutions and glasses developed at the Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, enabling one to predict their structures. This investigation method and analysis of experimental data have no analogues either in Russia or abroad. The results obtained were used to elucidate general glass formation trends in various water–electrolyte systems. We were the first to prove a polymeric structure of glass-forming compositions in some water–electrolyte systems. We were also the first to combine the glasses of water–electrolyte systems in a special class of glasses that are hydrogen-bonded polymeric items.

Self-catalyzed GaP nanowire and GaP/GaPAs nanowire heterostructures have been grown on Si(111) by solid-source molecular beam epitaxy. Formation of wurtzite polytype segments with thicknesses varying from the several tens up to the 500 nm depending on the growth condition has been observed. Effect of the V/III flux ratio on the growth mechanism, nanowire structure and morphology was studied by means of scanning electron microscopy and high resolution transmission electron microscopy.