Search

The combination of the method for measuring of the number of active centers by quenching of polymerization by radioactive carbon monoxide with fractionation of polymers obtained by TREF method (temperature rising elution fractionation) to the separate fractions with different isotacticity has been used for determination of the number of active centers with different isospecificity (C Pi) responsible for the formation of Fi fractions as well as for calculation of propagation rate constants (kPi) for these centers. Data on the effect of catalyst composition on the CPi and kPi values have been obtained for the first time for polymerization with three types of titanium-magnesium catalysts with different internal stereoregulating donors (di-n-butyl phthalate – TMC-D, 2,3-di-iso-butyl-diethyl succinate – TMC-S, 9,9-bis(methoxymethyl)-fluorene – TMC-F) and for catalytic system TMC-D with external stereoregulating donor – cyclohexylmethyl(dimethoxy)silane. The possible structures of active centers with different isospecificity are discussed on the base of experimental data obtained on the CPi and kPi values.

Chlorine-containing plasma and its mixtures with molecular and inert gases, as well as plasmas of complex polyatomic gases, such as freons, are often used to form the topology on the surface of semiconductors. This article examines the surface quality (based on the roughness data) of the semiconductor structure of GaAs after plasma-chemical etching in the plasma of mixtures of HCl/Ar, HCl/Cl2, and HCl/H2, as well as R-12 freon and its mixture with argon. Freon R-12 is often used for etching Si, Ge, and a number of other materials (GaAs, GaP, InP), providing technologically acceptable interaction rates, and also meets the requirements for anisotropy and selectivity. Also, mixtures of active gases with inert (He, Ar) gases have become widespread, which can act both as simply diluent gases and as sources of ions for the ion bombardment of the sample for the further ionic stimulation of the desorption of the interaction products, which improves the functional properties surface, with a slight decrease in the speed of interaction. Nevertheless, controlling the surface quality of samples remains an urgent task in modern electronics.

Multilayer microcapsules with the encapsulated model drug (acetylsalicylic acid) are formed by the layer-by-layer adsorption of natural polysaccharides, chitosan and sodium carboxymethyl cellulose, onto microparticles of calcium carbonate. Three encapsulation methods are considered: physical adsorption of acetylsalicylic acid in the pores of calcium carbonate microparticles, coprecipitation of an acid with an inorganic template material during its preparation, and incorporation of an acid into hollow capsules by varying the permeability of their shells. To vary the shell permeability, it is proposed to change the polarity of the solvent by introducing 50 vol% ethanol into an aqueous solution. The method has the highest efficiency in encapsulation of acetylsalicylic acid and does not allow the release of acid from the capsules in acidic environments.

The formation of polyelectrolyte complexes between natural polysaccharides, chitosan and carboxymethyl cellulose sodium salt, in water–ethanol media was studied. It was found that, with an increase in the content of ethanol in the solvent to 50 vol %, the intensity of the Coulomb interactions between oppositely charged groups of polyelectrolytes gradually weakens and, as a consequence, the complexing ability of polymers decreases. The layer-by-layer adsorption of polyelectrolytes onto calcium carbonate microparticles yielded microcapsules with a different number of layers. An approach is proposed to control the permeability of polyelectrolyte microcapsule walls by changing the solvent polarity upon addition of 50 vol % ethanol to an aqueous solution. Microcapsules with a high efficiency of inclusion of a model drug substance, acetylsalicylic acid, were obtained using this approach.

The complexation of chitosan and anionic surfactant, sodium dodecyl sulfate (DDS), in aqueous-alcohol media with a variable content of an organic cosolvent (methanol, ethanol, and propan-1-ol) was studied. A complicated effect of the composition of mixed solvents on the binding parameters of DDS by chitosan was observed. The introduction of 10–20 vol.% ethanol and propan-1-ol is accompanied by an increase in the degree of cooperative binding of DDS compared to that found in an aqueous solution, which leads to a decrease in the critical concentration of association and an increase in the cooperativity parameters.

The possibility of additional hardening of foam aluminum by metal borides, hardening phases, which create an additional hardening frame in the matrix of cast aluminum, is shown. The increase in the strength of the aluminum frame and the entire composite material as a whole with the introduction of the boride component increases by 1.4 times.

Using the inhibition of polymerization by radioactive carbon monoxide 14СО, the effect of hydrogen (chain transfer agent) on the number of active centers and propagation rate constant in ethylene polymerization over modern highly active titanium–magnesium catalysts with different composition is studied. It is found that a decrease in the rate of ethylene polymerization in the presence of hydrogen is associated primarily with reduction in the number of active centers and these changes are reversible at the introduction/removal of hydrogen. The scheme of reversible temporary deactivation of active center precursors is advanced to explain the experimental results. According to the data on the effect of hydrogen concentration on the molecular weight of polyethylene and the values of propagation rate constants, the rate constant of polymer chain transfer by hydrogen is calculated for catalysts with different composition.

By cyclic gas treatment in ammonia and in air, a composite surface layer with controlled structure may be formed on die steel. Thanks to the catalytic properties of the oxide film that appears, an extended multilayer region of chemical compounds is formed at its surface. That improves the erosion and crack resistance of the die steel, with corresponding increase in the life of hot-working dies by a factor of 2–2.5.

The influence of supported titanium-magnesium catalysts with various internal and external donors on the propylene polymerization in the liquid monomer medium and the characteristics of the polypropylene formed were studied. The following internal donors were used: dibutyl phthalate, diisobutyl phthalate, 9,9′-bis(methoxymethyl) fluorene, and diethyl 2,3-diisopropylsuccinate. The catalysts studied allow synthesis of polypropylene with high isotacticity (>96%) and different molecular-mass distribution (Mw/Mn from 3.3 to 6.3). The influence of external donors (alicyclic, amine) in combination with phthalate and nonphthalate electron-donor compounds on the stereospecificity and activity of the catalysts and on their sensitivity to hydrogen was studied. The optimum catalytic systems for preparing polypropylene for various purposes can be found by varying pairs of internal and external donors.

Because of a high energy of the neutrinoless double-beta decay (0ν2β) of the isotope 150Nd and a high value of the daughter-nucleus charge Zf, 150Nd is one of the most promising isotopes for 0ν2β-decay searches. A 150Nd-containing detector on the basis of a liquid organic scintillator permits employing large isotope masses. Requirements on the radiation purity of the neodymium sample used are determined. The possible design of a large-scale detector of this type and expected results are considered.

The effect of polymerization conditions (temperature, polymerization time, monomer and hydrogen concentrations) on propylene polymerization in the liquid monomer in the presence of a TiCl4/DBP/MgCl2 + TEA/cyclohexylmethyldimethoxysilane catalyst system is studied . It is shown that the variation of the propylene polymerization conditions in the studied ranges leads to a change in the characteristics of the resulting polypropylene. The kinetic parameters of propylene polymerization in the liquid monomer for the studied catalyst system are determined. Polymerization conditions providing the formation of polypropylene with high polymer yield, isotacticity, and bulk density values are found. The process parameters that make it possible to effectively control the molecular and rheological characteristics of polypropylene are identified.

We present data on the number of active centers (CP) and the propagation rate constant (kP) upon copolymerization of ethylene and 1-hexene over supported titanium–magnesium catalysts of different compositions obtained by polymerization quenching with radioactive carbon monoxide (14CO). The rise in ethylene/1-hexene copolymerization rate as compared to the rate of homopolymerization (the comonomer effect) is found to be related to the increase in the calculated propagation rate constant. Meanwhile, the increased 1-hexene concentration results in a higher calculated kP value. Addition of 1-hexene during ethylene polymerization also increases the polymerization rate by raising the calculated kP value. These findings demonstrate that the comonomer effect is caused by the increase in monomer concentration in the copolymer layer that is formed on a catalyst particle and is characterized by reduced crystallinity as compared to that of homopolymer. The decline in the copolymerization rate with time is caused by reduction of the number of active centers.

The formation of polymer-colloid complexes of chitosan and anionic surfactant—sodium dodecyl sulfate—in water–alcohol mixtures is studied by potentiometry using ion-selective electrodes. The influence of the nature and content of organic cosolvent (methanol, ethanol, and 2-propanol) on the parameters of binding of surfactant with chitosan and the stability of complexes is discussed. The obtained data are analyzed in terms of the model of cooperative binding and pseudophase model. It is shown that addition of 10–20 vol % of ethanol and 2-propanol to aqueous solution intensifies cooperative binding of sodium dodecyl sulfate with chitosan, which leads to the decrease in the critical association concentration and increase in the parameters of cooperativity and stability of complexes.

The GERmanium Detector Array (GERDA) collaboration searched for neutrinoless double-$\beta$ decay in $^{76}$Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at Q$_{\beta\beta}$ = 2039.061(7)keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double-$\beta$ decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular $^{228}$Th calibrations. In this work, we describe the calibration process and associated data analysis of the full GERDA dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years., Comment: 12 pages, 7 figures

Neutrinoless double-$\beta$ decay of $^{76}$Ge is searched for with germanium detectors where source and detector of the decay are identical. For the success of future experiments it is important to increase the mass of the detectors. We report here on the characterization and testing of five prototype detectors manufactured in inverted coaxial (IC) geometry from material enriched to 88% in $^{76}$Ge. IC detectors combine the large mass of the traditional semi-coaxial Ge detectors with the superior resolution and pulse shape discrimination power of point contact detectors which exhibited so far much lower mass. Their performance has been found to be satisfactory both when operated in vacuum cryostat and bare in liquid argon within the GERDA setup. The measured resolutions at the Q-value for double-$\beta$ decay of $^{76}$Ge (Q$_{\beta\beta}$ = 2039 keV) are about 2.1 keV full width at half maximum in vacuum cryostat. After 18 months of operation within the ultra-low background environment of the GERmanium Detector Array (GERDA) experiment and an accumulated exposure of 8.5 kg$\cdot$yr, the background index after analysis cuts is measured to be $4.9^{+7.3}_{-3.4}\times 10^{-4}$ counts /(keV$\cdot$kg$\cdot$yr) around Q$_{\beta\beta}$. This work confirms the feasibility of IC detectors for the next-generation experiment LEGEND., Comment: 13 pages, 12 figures, submitted to EPJC

The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay of $^{76}$Ge, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched in $^{76}$Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of $5.2\times10^{-4}$ counts/(keV$\cdot$kg$\cdot$yr) in the signal region and met the design goal to collect an exposure of 100 kg$\cdot$yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg$\cdot$yr of total exposure. A limit on the half-life of $0\nu\beta\beta$ decay in $^{76}$Ge is set at $T_{1/2}>1.8\times10^{26}$ yr at 90% C.L., which coincides with the sensitivity assuming no signal., Comment: 7 pages, 3 figures, submitted to Physical Review Letters

The microreview considers the biological activity and methods of obtaining natural melanin pigments and their biosynthetic precursor 5,6-dihydroxyindole-2-carboxylic acid. The key methods for the synthesis of 5,6-dihydroxyindole-2-carboxylic acid, published over the past 8 years (2012–2020), are presented.

We present the first search for bosonic superweakly interacting massive particles (super-WIMPs) as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-s decay experiment which operates high-purity germanium detectors enriched in ^{76}Ge in an ultralow background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c^{2} to 1 MeV/c^{2}. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c^{2} have been set. As an example, at a mass of 150 keV/c^{2} the most stringent direct limits on the dimensionless couplings of axionlike particles and dark photons to electrons of g_{ae}

Fluorination of a mixture of fluorinated amines, which has the fozhalin brand name, with fluorine in a gas–fluid system in a reactor with high-speed stirrer mounted in the circulation contour was studied.

The association of chitosan in aqueous-alcohol solutions is studied via probe fluorescence spectroscopy and dynamic light scattering. It is shown that, if a certain critical concentration is reached, the associates of macromolecules 12–38 nm in size are formed in chitosan solutions. The addition of 5–60 vol % ethanol to the solvent leads to reduction in the critical association concentration. The tendency of chitosan macromolecules toward association is the most pronounced at 34 vol % alcohol.

The effect of hydrogen on the number of active centers (СР) and the propagation rate constant (kP) at ethylene polymerization over titanium–magnesium catalysts is studied using quenching by radioactive carbon monoxide (14СО). The polymerization rate drops after hydrogen was added to the polymerization medium mainly due to the decrease in the calculated kP value. The changes in the polymerization rate and the experimental kP value observed after hydrogen was added or removed are found to be reversible. The data on the effect of the [H2]/[C2H4] molar ratio in the gas phase within the range of 0.125–1 on polymerization rate and the СР and kP values are obtained. Reduction of the kP value and a small decrease in the number of active centers are observed at the H2/C2H4 molar ratio ≥ 0.5. These findings were used to propose a scheme interpreting the effect of hydrogen on the СР and kP values. The scheme suggests that the decrease in the calculated kP value observed in the presence of hydrogen is related to the reversible formation of temporarily inactive dormant sites containing the titanium–polymer bond.

The influence of the forming conditions on the structure and properties of Aquivion® perfluorinated proton-conducting membranes prepared by casting from a dimethylformamide solution was studied. At properly chosen and controlled conditions of solvent evaporation and subsequent heat treatment, membranes with more ordered morphology and structure, high level of mechanical properties, and high proton conductivity can be obtained. These results are attributed to the structural self-organization of the polymer base of the membranes in the course of nanofilm formation. The properties of Aquivion® type membranes prepared by casting and pressing were compared. The possibility of improving the strength properties of the membranes to the level close to that of the membranes prepared by extrusion was demonstrated.

The study is aimed to investigate the impact of silver nanoparticles on germination of Pisum sativum pea seeds. The influence of synthesized silver nanoparticles on root length and percentage of germinated seeds was revealed. It was found that nanosilver treatment agents do not affect the germination of pea seeds negatively at low concentrations. Also, the treatment of pea seeds with silver nanoparticles provide a significant positive effect on the root length of pea seeds.

We describe and analyze simultaneous sublimation activity of the main-belt primitive asteroids during their perihelion passages, which was detected by spectral methods. This phenomenon was observed for the first time in September 2012 for asteroids (145) Adeona, (704) Interamnia, (779) Nina, and Mars-crosser (1474) Beira ( Busarev et al., 2015 , Busarev et al., 2016 , Busarev et al., 2018 , Busarev et al., 2019a ). By our recent observations of (704) Interamnia, (24) Themis, and (449) Hamburga performed in March–April 2019, we confirmed the existence of this effect. (24) Themis and (449) Hamburga was detected as active for the first time. Never before, two or more asteroids have been observed active simultaneously. Activity on asteroids reveals itself by unusual spectral features (the maxima at approximately 0.40–0.50 and/or 0.60–0.70 μm), which appear in the reflectance spectra of the bodies when they approach perihelion. We explain them as manifestations of sublimation of ice materials and development of a subtle exosphere around the asteroids. Moreover, from numerical simulations of the light scattering in a medium containing ice and silicate/organic dust particles of complex structure, we found that some of these models fit well the reflectance spectra of active asteroids, which confirms the presence of a rarefied exosphere around these bodies. Our results show that the main conditions providing formation of a temporal sublimation-driven exosphere around primitive main-belt asteroids are: (1) the considerably higher content of H2O in their material than that previously believed from accounting for only the content of bound water in composition of carbonaceous chondrites, as possible components of asteroids; (2) frequent collisions of main-belt asteroids with smaller bodies and/or exposure to meteorite fluxes, which leads to excavation of ices and their subsequent sublimation; (3) the recurrent rise of the subsolar temperature on the surface of asteroids under proper orbital or dynamical parameters and the sublimation of subsurface ices (if present); and (4) the strengthening of solar activity (and the accompanying factors), which results in desiccation, destruction and/or dispersion of hydrated silicates and/or radiation damage of organic films isolating stocks of volatiles on or under the asteroid surface. According to our analysis, none of these factors produces a noticeable effect alone and can be marked as stronger or more frequent, but two or three of them working simultaneously may be effective.

The CH-cyclization of alkynyl-9,10-anthraquinones 1 into thienoanthraquinones 2 is shown to be initiated by the neutral S 2 molecule and not by the sulfide anion as it is assumed in the existing model of CH-cyclization with the nucleophiolic substitution of H. The formation of S 2 takes place in the reaction medium due to the partial reduction of the substrate 1 by Na 2 S into the corresponding anthrahydroquinone, which is inactive in the main reaction. We present a new cyclization mechanism with the key stage involving the electrophilic displacement of H, which results in the formation of the reaction product 2 and elimination of S. In the reaction medium atomic sulfur is transformed into S 2 , which initiates the next cyclization act. This determines the chain nature of cyclization with the participation of S 2 . Within this model, the route to increase the yield of target thienoanthraquinones is proposed through the introduction of a neutral quinone able to generate S 2 by means of easy reduction.

A setup for measuring natural-radioactivity backgrounds and ultralow concentrations of the isotope 14C in samples of a liquid organic scintillator was created at the low-background laboratory of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) at a depth of 4900 mwe. The concentration of the radiocarbon 14C in a sample of a scintillator based on domestically produced linear alkylbenzene was measured, and it was found that 14C/12C (3.3 ± 0.5) × 10−17.

The advantages of aqueous emulsion method are demonstrated for producing copolymers as a material for Nafion®- and Aquivion®-type proton exchange membranes. The features of copolymerization of tetrafluoroethylene (TFE) with sulfonyl fluoride monomers in microdroplets of monomer in emulsion are discussed. For the first time, the copolymerization constants were found for TFE reaction with perfluoro (3,6-dioxa-4-methyl-7-octene) sulfonyl fluoride (FS-141) or perfluoro-3-oxapentenesulfonyl fluoride (FS-81) monomers in the aqueous emulsion medium. The producing of long- and short-side chain copolymers realizes by different mechanisms, depending on the way of copolymer accumulation in the system – either by persisting in monomer microdroplets or by segregation in latex particles. Aqueous emulsion copolymerization allows regulate the copolymer composition, keeping it constant till high degrees of monomer conversion, thus obtaining the membrane copolymer precursors with improved properties.

The effect of additions of sodium tetradecyl sulfate as an anionic surfactant on the association of chitosan macromolecules in aqueous-glycerol solutions was studied by fluorescence probe spectroscopy and dynamic light scattering. Associates of 40–170 nm size are formed on reaching a certain critical concentration of chitosan in solutions. The critical association concentration of chitosan in solutions containing 10–30 vol % glycerol is higher than in aqueous solutions. Formation of chitosan–surfactant complexes enhances the tendency of chitosan macromolecules to association in water–glycerol mixed solvents.

The light yield in samples of a Nd-loaded scintillator was measured. The scintillator composition differed in the solvent (pseudocumene (PC) and a mixture of PC with linear alkyl benzene), the scintillating dye type (РРО or ВРО), and the Nd concentration. The light yield in the PC (PPO, 1.5 g/L), which was approximately 11500 photons/MeV, was assumed to be the standard. The ionizing-radiation sources were 137Cs, 241Am, and 109Cd radionuclides. It was shown that the light yield in the scintillator with a Nd concentration as high 30 g/L (~3%) in PC made it possible to attain energy resolution at a level of 3% at an energy of 3 MeV (neutrinoless 2β decay of 150Nd).

A technique for the formation of diffusion layers based on zinc on the surface of low-carbon low-alloy steels for their corrosion protection is considered. The possibility of the formation of dense corrosion-resistant coatings with a smooth hardness gradient through depth by diffusion zinc-plating combined with gas nitriding is studied.

The efficiency of removing U and Th from a liquid organic scintillator based on linear alkylbenzene (LAB) by stripping with a 0.02 M aqueous solution of aminomethylenediphosphonic acid and by sorption on aluminum oxide and silica gel was studied. A procedure was developed for purification of scintillation additives (2,5-diphenyloxazole, 2-biphenyl-5-phenyloxazole, p-terphenyl) to remove 40K.

The challenge of obtaining high-quality concretes rests on the specificity of hydration hardening of a cement binder, during which the introduction of even a small amount of this or that component or a change in the hardening conditions may lead to drastic changes in the structure and properties of cement materials. In order to reveal the nature of the influence of plasticizing additives and their introduction procedure, a set of research efforts targeting microstructure and basic mechanical properties was deployed, including the study of changes of cement stone’s structural and mechanical parameters over a long period of hardening (up to 18 years) and the composition of cement stone’s hydration products. The main variable factors dealt with are: the dosage of SP S-3 and the modifier’s introduction procedure during mixing of cement with water. The paper imparts findings on the kinetics of changes in the content of alite, belite and other hydrosilicates in cement stone, as well as portlandite against the duration of samples’ hardening. It was found that for almost all compositions with S-3, there is a decrease in the intensity of calcite reflections (3.029 Å) compared to the control sample, which speaks of a slight decrease in carbonation processes in the presence of a superplasticizer. When the temperature and humidity conditions of hardening change, especially over a long period, structural changes associated, for example, with the destabilization of hydroaluminate phases, decompression caused by the formation of secondary crystalline hydrates of various densities, and the release of hydrate water can be one of the reasons for changing the strength of cement systems over time. These phenomena were analysed throughout its hardening time lasting up to 18 years.

This paper presents data on the number of active centers (CPi) with different stereospecificity and the values of propagation rate constant (kPi) for these centers in the propylene polymerization over supported titanium-magnesium catalyst in the presence or absence of hydrogen. The indicated data were obtained by quenching the polymerization with radioactive carbon monoxide (14CO) with subsequent fractionation of the produced polymers by the TREF method into separate fractions differing in stereospecificity and estimation of the CPi and kPi values, which determine the formation of these fractions. The propagation rate constants calculated for active centers with different stereospecificity increase in the following order: kP(aspecific) ≈ kP(low isospecific)

The effect of the particle size of an IK-8-21 domestic titanium-magnesium catalyst on the properties of polypropylene (PP) produced during the polymerization of propylene in a liquid monomer is studied. Catalysts with particle sizes of 20 to 64 μm are shown to have high activity and identical sensitivity to hydrogen and allow PP to be obtained with a narrow distribution of particles over size, high isotacticity, and close values of crystallinity, melting temperature, and physicomechanical properties. A slight decrease in the activity and bulk density of PP powder is observed when the average size of catalyst particles is increased from 20 to 43 μm. A more notable reduction in the activity and bulk density of PP powder is observed for catalyst with particle sizes of 62 to 64 μm. IK-8-21 catalyst is not inferior to its foreign analogues with respect to the properties of the resulting PP.

The complexing of protonated chitosan with dodecyl sulfate ions in water solutions is studied using IR spectroscopy data and quantum-chemical calculations. It is established that the electrostatic interaction between the protonated amino groups of chitosan and dodecyl sulfate ions is apparent in the IR spectrum as a band at 833 cm−1. The need to consider the effect the solvent has on the formation of hydrogen-bound ion pairs [CTS+ ⋅ C12H25O3-] is shown via a quantum-chemical simulation of the equilibrium geometry and the energy characteristics of complexing and hydration.

The oil and gas potential of the Kuma Formation of the Bakhchisarai region (southwestern Crimea) was substantiated on the basis of a lithological and micropaleontological study of the rocks of the section of the formation and geochemical (luminescent-bituminous, gas-liquid chromatographic, pyrolytic, and isotope) studies of the organic matter of the rocks. New regions for study that are favorable for the origination of the oil system in this formation were identified.

In the framework of the spin-fermion model, it is shown that accounting for the strong spin-charge fluctuations between holes of copper and oxygen ions in cuprate High-T c superconductors leads to the formation of the Fermi spin-polaron quasiparticles. It is demonstrated that the large value of the binding energy of such quasiparticle is determined by the processes in which hopping intensity of the oxygen holes depends significantly on the spin configuration of holes on the copper and oxygen ions. It was found that the ensemble of such quasiparticles manifests Cooper instability and the concentration dependence of the critical temperature is in good agreement with the experimental data.

The electron paramagnetic resonance (EPR) method was used to investigate the formation of alkylated Ti(III) species in superactive titanium–magnesium catalysts with a low titanium content during their interaction with an organoaluminum activator (AlMe3), as well as the interaction of alkylated Ti(III) surface species with carbon monoxide. EPR data on the content of alkylated Ti(III) species in these catalysts agree well with the number of Ti–R bonds that are determined after the interaction of radioactive carbon monoxide (14CO) with catalyst activated by triethylaluminum in the absence of monomer. Parameters of EPR spectra of the Ti(III) species having different structure and composition on the surface of titanium–magnesium catalysts were calculated by quantum-chemical simulations. The calculated g-values are consistent with the g-values observed in EPR spectra of the catalysts. Analysis of the literature data and results of our study made it possible to propose the parameters of EPR spectra characterizin...

2-(Trifluoroacetyl)chromones react with indoles at 90 °C under solvent-free conditions to produce the target (chromon-2-yl) (indol-3-yl) (trifluoromethyl)carbinols in 69–90% yields. In a similar manner, their reactions with pyrroles under the same conditions gave (chromon-2-yl) (pyrrol-2-yl) (trifluoromethyl)carbinols in 52–95% yields. These chromone derivatives react with 60% hydrazine hydrate in refluxing ethanol to give the corresponding pyrazoles.

A procedure was developed for removing uranium, thorium, and potassium from a liquid organic scintillator based on linear alkylbenzene (LAB) by stripping with water. The volume ratio of the scintillator and water in the process should be no less than 1: 5. The attenuation length (L 420) of LAB after treatment with water does not change and is as high as 13.0 ± 1.8 m. The solubility of water in LAB and of LAB in water was determined to be 46 and 5.1 ppm, respectively.

The effects of addition of ethanol and propan-1-ol on sodium tetradecyl sulfate micelle formation in an aqueous solution are studied via microprobe fluorescence microscopy and conductometry. The critical micelle concentration, quantitative characteristics of micelles, and thermodynamic parameters of micelle formation are determined. Addition of 5–15 vol % of ethanol or 5–10 vol % of propan-1-ol is shown to result in a lower critical micelle concentration than in the aqueous solution, and in the formation of mixed spherical micelles whose sizes and aggregation numbers are less than those for the systems without alcohol. The contribution from the enthalpy factor to the free energy of sodium tetradecyl sulfate micelle formation is found to dominate in mixed solvents, in contrast to aqueous solutions.

The kinetics of ethylene polymerization at varied polymerization temperature over two modifications of titanium–magnesium catalysts that differ in their compositions and the molecular weight of the resulting polymers were studied by polymerization quenching by radioactive carbon monoxide. An increase in polymerization temperature in the range of 40–80 °C was found to significantly increase the number of active centers (CP), which contributes to the polymerization rate more significantly than an increase in the propagation rate constant (kP) does. The rise in the number of active centers with increasing polymerization temperature is shown to result in effective activation energy (Eeff) determined from the temperature dependence of polymerization rate being significantly higher than the activation energy of propagation reaction (EP) determined from the temperature dependence of the kP value. It was shown too the changes of the number of active centers and polymerization rate at variation of temperature in the single experiment have the reversible nature. The data on the number of active centers and the propagation rate constants at ethylene polymerization in the presence of hydrogen as a chain transfer agent are obtained. Introduction of hydrogen reduces the number of active centers at elevated polymerization temperatures (60–80 °C) and has virtually no effect on the CP value at lower temperatures; it also reduces the kP value at 40–80 °C. The findings on the effect of polymerization temperature on the number of active centers were used to propose a kinetic scheme including the reaction of reversible transformation of the precursors of active centers (alkyl derivatives of titanium) into an inactive state due to adsorption of a co-catalyst (triethylaluminum). The transformation of these complexes into active centers depends on polymerization temperature, presence of hydrogen, concentrations of monomer and organoaluminum activator.

The GERDA experiment searches for the lepton-number-violating neutrinoless double-β decay of ^{76}Ge (^{76}Ge→^{76}Se+2e^{-}) operating bare Ge diodes with an enriched ^{76}Ge fraction in liquid argon. The exposure for broad-energy germanium type (BEGe) detectors is increased threefold with respect to our previous data release. The BEGe detectors feature an excellent background suppression from the analysis of the time profile of the detector signals. In the analysis window a background level of 1.0_{-0.4}^{+0.6}×10^{-3} counts/(keV kg yr) has been achieved; if normalized to the energy resolution this is the lowest ever achieved in any 0νββ experiment. No signal is observed and a new 90% C.L. lower limit for the half-life of 8.0×10^{25} yr is placed when combining with our previous data. The expected median sensitivity assuming no signal is 5.8×10^{25} yr.

Claisen condensation of 3-acetyl-4,6-dimethyl-2-pyridone with methyl 2-methoxytetrafluoropropionate in the presence of LiH in refluxing dioxane gave the corresponding 1,3-diketone, further converted by treatment with conc. H2SO4 to 5,7-dimethyl-2-(1-methoxytetrafluoroethyl)-8-azachromone and 5,7-dimethyl-2-trifluoroacetyl-8-azachromone, which was isolated as hydrate. The first of these azachromones reacted with dinucleophiles at the С-2 atom and the pyrone carbonyl group, while the second reacted at the С-2 atom and trifluoroacetyl group. Based on these compounds, we obtained new trifluoromethylated heterocyclic systems containing a 2-pyridone ring, as well as (8-azachromon-2-yl)(indol-3-yl)carbinols.

It was found that the observed order of the polymerization rate with respect to ethylene concentration at ethylene polymerization over two titanium-magnesium catalysts of different compositions is significantly higher than 1 (1.6–2.1). The data on the effect of ethylene concentration on the number of active centers ( C P ) and the propagation rate constant ( k P ) at ethylene polymerization over these catalysts were obtained by method of polymerization quenching with 14 CO. An increase in ethylene concentration was found to increase the number of active centers. In some cases the increase of ethylene concentration proceeds to the narrowing of the molecular weight distribution of the resulting polyethylene and an increase in the calculated value of propagation rate constant. These effects were shown to be most pronounced at low ethylene pressure and increased concentration of an activator (AlEt 3 ). Based on the experimental data, we proposed a scheme of reactions to explain the effects of ethylene and AlR 3 concentrations on the number of active centers, the average values of propagation rate constant and molecular weight distribution of polymers produced over these multi-site catalysts.

Reaction of substituted 3-azido 1,4-benzodiazepine with tricyclohexylphosphine is not the Staudinger reaction and unexpectedly results in P-ylide of 1,4-benzodiazepine. This is the first example of organic azides exhibiting the pseudo halide properties in the reactions of trivalent phosphorus compounds.

The influence of the length of the hydrocarbon radical in sodium alkyl sulfates and of the solvent composition on the formation of polymer-colloid complexes with chitosan in aqueous-ethanol solution was studied. The critical association constants, binding cooperativity parameters, and dissociation constants of the complexes were determined. An increase in the length of the alkyl radical leads to enhancement of the association of sodium alkyl sulfates with chitosan at an ethanol concentration in solution of up to 30 vol %. In solutions with higher ethanol concentrations, the solvent composition becomes the decisive factor of the complex formation of chitosan with sodium alkyl sulfate.

The GERmanium Detector Array (GERDA) experiment, located at the Gran Sasso underground laboratory in Italy, is built for the search of $0\nu\beta\beta$ decay in $^{76}$Ge. GERDA operates bare high purity germanium detectors submersed in liquid Argon (LAr). Phase I of the experiment was completed reaching an exposure of about 21 kg$\cdot$yr with a background level of $10^{-2}$ cts/(ke V $\cdot$ kg $\cdot$ yr). GERDA Phase I set a limit on the $0\nu\beta\beta$ decay of $^{76}$Ge of $T_{1/2}^{0\nu} > 2.1 \cdot 10^{25}$ yr. In Phase II 35 kg of germanium detectors enriched in $^{76}$Ge are operated to reach an exposure of 100 kg$\cdot$yr. The design goal is to reduce the background by one order of magnitude to reach the sensitivity for $T_{1/2}^{0\nu} = \mathcal{O} (10^{26} )$ yr. The Phase II setup comprises thirty newly produced Broad Energy Germanium (BEGe) detectors. They contribute to the background reduction with better energy resolution and enhanced pulse shape discrimination. To achieve the necessary background reduction, the setup was complemented with LAr veto. The hardware upgrade for Phase II was finished and all detectors were deployed in December 2015. We present the first results of Phase II with 10.8 kg$\cdot$yr exposure reached in June 2016.