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The palladium-catalyzed allylation of norbornadiene is a unique method for the C-C bond formation involving allyl derivatives. This reaction proceeds in solution. However, the selection of the solvent is so far an empirical procedure, and the role of the solvent in this process is poorly understood. The effect of the solvent on the reaction pattern is considered in terms of polarity, polarizability, and coordinating ability of the solvent. These properties were shown to be the key factors in selecting the proper solvent. Based on investigation of the mechanism of individual catalytic cycle stages, the features of the interaction between the solvent, the catalyst, and reagents were analyzed.

For the model chemiluminescent reaction of N-octylluminol, a hydrophobic analogue of luminol and a surfactant, a scheme was established and parameters of the formal kinetic equation were calculated. The formation of intrinsic micelles of the substrate promotes a triple increaese in the rate of the first step of the luminogenous reaction and a multiple increase in the detected maximum and integrated signal intensities compared to results obtained in the classical chemiluminescent system based on luminol. The reversible conversion of N-octylluminol to a non-luminescent form was revealed, and the equilibrium is strongly shifted to the latter, which distorts the shape of the detected kinetic curve and decreases the analytical signal with time. This shift can be prevented by using the systems with controlled mixing of reagents.

This paper describes the results of an investigation into a microstructure formation on a wire-feed electron beam additive manufactured “steel–copper” bimetallic sample. The peculiarities of a gradient zone structure with a smooth change of components’ concentration are revealed. The heterogeneity of copper and steel distribution in the gradient zone is provided by copper solidification and precipitation mechanisms. Both solidification of coarse copper inclusions in the interdendrite areas or along the dendrite boundaries and precipitation of fine Cu-based particles at the cooling stage from the solid solution of Cu in γ-Fe are the main factors of structure formation during the double wire gradient zone deposition. The presence of such fine copper precipitates from the supersaturated solid solution was revealed by means of transmission electron microscopy. The shape of copper particles in the gradient zone varies from spherical to oblong and irregular. The shape of steel particles and/or grains is mainly determined by the peculiarities of the crystallization zone and is characterized by the primary crystallization of γ-iron dendrites from the liquid melt. A physical scheme describing a variation in phase composition and microstructure in gradient zone of the bimetallic specimen was proposed.

A billet of an AISI 304-type austenitic stainless steel has been built using a wire-feed electron beam additive manufacturing (EBAM) in a layer-by-layer strategy. A microstructure, grain boundary assemble, phase composition and tensile properties of steel billet have been investigated in as-built specimens and after post-built solid-solution treatment. As-built austenitic stainless steel is a highly anisotropic heterophase material with high fraction of interphase boundaries (austenite/ferrite) and intergranular boundaries (austenite/austenite). A macroscopically inhomogeneous (layered) structure with columnar austenitic grain growth has been produced during EBAM processing. The coarse-grained austenitic structure contains δ-ferrite of dendritic morphology in as-built specimens. Ductility and strength properties of the additively manufactured steel show substantial anisotropy, which is strongly correlated with macro- and microstructural peculiarities of the as-built billet. Post-built solid-solution treatment decreases a volume fraction of ferrite in the microstructure, changes the morphology of ferrite phase and, therefore, varies the distribution of interphase boundaries (ferrite/austenite). The effect of post-built solid-solution treatment on tensile properties of the EBAM manufactured steel is discussed taking into account a change in microstructure and phase composition, grain and phase boundary distribution in the specimens.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) with an autoimmune mechanism of development. Currently, one of the most promising directions in the study of MS pathogenesis are the neuroimmune interactions. Dopamine is one of the key neurotransmitters in CNS. Furthermore, dopamine is a direct mediator of interactions between the immune and nervous systems and can influence MS pathogenesis by modulating immune cells activity and cytokine production. Recent studies have shown that dopamine can enhance or inhibit the functions of innate and adaptive immune system, depending on the activation of different dopaminergic receptors, and can therefore influence the course of experimental autoimmune encephalomyelitis (EAE) and MS. In this review, we discuss putative dopaminergic therapeutics in EAE and MS with focus on Th17-cells, which are thought to play crucial role in MS pathogenesis. We suggest that targeting dopaminergic receptors could be explored as a new kind of disease-modifying treatment of MS. Graphical Abstract.

Using combined deformation processing, including preliminary mechanical activation followed by consolidation via high-pressure torsion, a multi-layer nanocomposite based on nickel and aluminum is manufactured. The influence of the duration of mechanical activation on its microstructure parameters is investigated by the X-ray diffraction analysis and scanning and transmission electron microscopy. It is found out that nanostructuring of the multi-layer nanocomposite during its manufacture ensures the formation of a high density of phase and grain boundaries. It is shown that this structural transformation is accompanied by an intense strengthening effect.

Objective. To study the possibly associations between the clinical features of multiple sclerosis(MS) and quantitative and the qualitative properties of Th17 cells and the dopamine (DA) and serum noradrenaline (NA) concentrations in patients with MS. Materials and methods. Complex neurological and immunological investigations were carried out on 43 patients with remitting MS. All patients were underwent neurological investigations including assessment of levels of disability on the EDSS scale. Serum DA and NA concentrations were determined by immunoenzyme analysis. The proportions of circulating Th-17 cells were assessed by multicolor flow cytometry. The functional activity of Th17- and Th-1 cells was assessed in terms of IL-17 and γ-interferon production by peripheral blood mononuclear cells stimulated with magnetic particles coated with anti-CD3/anti-CD28 antibodies. Results. The proportion of Th-17 cells and cytokine production in the group of MS patients in exacerbation were significantly greater than in remission and in the control group, while the DA level was lower. NA levels in MS patients were identical in exacerbation and remission but were significantly lower than in the control group. Conclusions. These data suggest that catecholamines have an inhibitory effect on Th17 cells in MS.

Using the methods of X-ray diffraction analysis and scanning and transmission electron microscopy, an investigation of the influence of duration of mechanical activation on morphology and structure of titanium powder is performed. In the course of processing the following stages of material transformation are revealed: fragmentation of the initial powder, conglomeration, and ovalization of the conglomerates. It is found that when the duration of mechanical activation increases, the characteristic size of coherent scattering regions is significantly decreased, which is accompanied by an increase in the value of microdistortions and intensive fragmentation of the crystal lattice inside powder particles followed by the formation of highly defective nanostructured states. The transformation of microstructure is accompanied by a considerable increase in microhardness.

We prove that N = 2 theories that arise by taking n free hypermultiplets and gauging a subgroup of Sp(n), the non-R global symmetry of the free theory, have a remaining global symmetry which is a direct sum of unitary, symplectic, and special orthogonal factors. This implies that theories that have SU(N) but not U(N) global symmetries, such as Gaiotto's TN theories, are not likely to arise as IR xed points of RG ows from weakly coupled N = 2 gauge theories.

Results of a theoretical study of the interaction of interstitial molecular hydrogen with vacancies and the effect of generated defects on the structural and energy characteristics of the H2–Si system are considered. Within the framework of a 5D model it has been demonstrated that the decrease of system symmetry under transition to the crystal defect structure and the increase of the rotational barrier due to the strong interaction of the molecule with a vacancy lead to the significant restructuring of H2 energy spectrum. However, when the molecule is stable its rotational degrees of freedom remain active and H2 low-lying energy levels correspond to the definite values of the angular momentum.

The interaction of coumarin-6 and eosin-Y with particles of protonated potassium polytitanate (PPPT) was studied by luminescence spectral methods. It was established that the anisotropy of the fluorescence of coumarin-6 and eosin-Y in a suspension of PPPT is higher than in ethanol. This can be explained by bonding of the dyes with PPPT particles. The extinction coefficients of coumarin-6 (λ = 460 nm) e = 25,000 M−1·cm−1 and eosin-Y (525 nm) e = 36,000 M−1·cm−1 were determined from the absorption spectra of the dyes. It was shown that coumarin-6 and eosin-Y can be used for sensitization of PPPT.

The concepts of the project ATOMSK are outlined. The project aims at developing a general approach to the theoretical study of free and localized polyatomic systems including the development of appropriate computational tools. Basic physical principles and general scheme of the approach are stated. Calculation of the energy states of molecular hydrogen in single-crystal silicon was considered as an example.

We study the moduli space of A/2 half-twisted gauged linear sigma models for NEF Fano toric varieties. Focusing on toric deformations of the tangent bundle, we describe the vacuum structure of many (0,2) theories, in particular identifying loci in parameter space with spontaneous supersymmetry breaking or divergent ground ring correlators. We find that the parameter space of such an A/2 theory and its ground ring is in general a moduli stack, and we show in examples that with suitable stability conditions it is possible to obtain a simple compactification of the moduli space of smooth A/2 theories., 44 pages, xy-pic figures

Results of a theoretical study of the atomic and electronic structure of the hydrogen molecule in the crystalline silicon matrix are presented. An analytical expression for the rotational potential energy function of the interstitial hydrogen molecule in the crystal at the tetrahedral position is derived. The rotational terms and the corresponding wavefunctions as well as the ortho-para splitting of the Raman spectral lines are calculated. It is shown that the interstitial hydrogen states with l < 2 can be treated within the framework of the free molecule approach; however, a noticeable splitting of the rotational terms with l ≥ 2 indicates a substantial influence of the semiconductor matrix on the properties of the system.

This paper presents a prediction method using a parallel---hierarchical (PH) network and hyperbolic smoothing of empirical data. The average prediction error is 0.55% for the developed method and 1.62% for neural networks; therefore, this method is more efficient as applied to real-time systems than traditional neural networks due to the use of the PH network and hyperbolic smoothing in implementing the operation of predicting the positions of energy centers of laser beam spot images for optical communication systems.

Fluorescence and phosphorescence quenching processes of polar and non-polar luminescent probes associated with human serum albumin (HSA) in phosphate buffer at pH 7.4 were studied. Stern–Volmer quenching constants of anthracene and pyrene fluorescence and eosin phosphorescence and rate constants for quenching of eosin triplet states were determined. The polarity index of pyrene bound to HSA was obtained as a function of thallium nitrate concentration. The influences of structural changes in the proteins that were stimulated by heavy-metal salts and of screening of protein charges by salt ions on quenching processes of singlet and triplet states of the probes were found.

Opisthorchiasis is a parasitic disease which usually presents in countries where opisthorchis felineus is widespread due to the consumption of raw fish. Owing to population movements, this clinical entity can pose a challenge for the physician worldwide. We report the case of a 56-year-old patient with a recent history of opisthorchiasis, who presented with obstructive jaundice and cholangitis. Treatment with percutaneous transhepatic biliary drainage and anti-helminthic drugs resulted in improvement of the patient’s clinical picture. Further investigation prompted by persistent anaemia revealed right colon cancer. The patient underwent right hemicolectomy and surgical drainage of the extrahepatic biliary system. The postoperative course was uneventful. The epidemiology, biology, clinical presentation, diagnostic workup and treatment of opisthorchiasis are reviewed.

Results are reported from thermal tests of power generating units No. 1 – 4 of the Konakovo State Regional Electric Power Plant (Konakovo GRES) following modernization with new technical solutions for the turbines. Tests of the first, in Russia, high pressure cylinders with reactive blading and low pressure cylinders with sable nozzle blades are also reported. The thermal efficiencies of the turbine and power generating units before and after modernization are compared. Recommendations are made regarding the possible use of the proposed technical solutions in power plants with similar power generating units.

This paper considers provisions necessary for developing parallel-hierarchical network learning methods underlain by the idea of population coding in an artificial neural network and its approximation to natural neural networks. Mathematical parallel-hierarchical network learning models and a combined parallel-hierarchical network learning method are developed for recognizing static and dynamic patterns.

Theoretical investigations of adsorption of 3d-metals from Ti to Cu on the α-Al2O3 (0001) surface are presented. The influence of adsorbates on the atomic and electronic structure of the aluminum oxide surface is considered. Values of the adsorption energy are calculated, and the equilibrium adatom positions on the surface are determined. A comparative analysis of the properties and mechanisms of 3d-metal interaction with atoms of the substrate is performed.

An explicit formula of a multivariate B-spline, some useful investigations in the field of linear transformations of independent exponentially distributed random variables, representation of theirs density functions with the help of multivariate exponential spline functions, and their usage are considered. The consideration is illustrated by an appropriate example.

The temperature dependences of the EPR spectrum of the 2-trifluoromethylnitrobenzene radical anion in DMF:H2O mixtures, caused by the dynamic modulation of the fluorine isotropic hyperfine interaction by the hindered internal rotation of the CF3 group, have been measured and reconstructed numerically. The activation energy of rotation (EF) and the dynamic mode depended on the water content in the mixture. For mixtures with a molar fraction of water χ = 0, 0.186, 0.315, 0.409, 0.534, 0.650, 0.810, and 0.910, EF = 34.70 kJ/mol, 41.31 kJ/mol, 42.30 kJ/mol, 38.41 kJ/mol, 37.01 kJ/mol, 34.51 kJ/mol, 24.10 kJ/mol, and 21.78 kJ/mol, respectively. For χ = 0.186 in the temperature ranges accessible for measurements, the dynamic exchange is slow; for χ = 0.315, 0.409, 0.534, and 0.650, transitions from slow to intermediate and fast exchange take place; for χ = 0.810 and 0.910 in the temperature ranges under study T ∈ [252, 309]; [254, 297] (K), the exchange is fast. In the range 0.6 < χ < 0.9, EF decreased drastically, and the activation energy of rotational diffusion (Er) of the radical anion became maximum, which corresponds to the range of the compositions of DMF:H2O with maximum deviations from the ideal state.

We have studied the interaction between polycyclic aromatic hydrocarbons (pyrene and anthracene) with human serum albumin (HSA) and human blood plasma. We have shown that the increase in the fluorescence intensity and the decrease in the polarity index of pyrene on going from an aqueous solution to a pH 7.4 buffer solution of HSA suggests that polycyclic aromatic hydrocarbons are localized in the hydrophobic microphase of the proteins. The increase in the fluorescence intensity for anthracene and pyrene, and also the decrease in the polarity index of pyrene on going from HSA to blood plasma is connected with the fact that polycyclic aromatic hydrocarbons can bind both to plasma proteins and to plasma lipids. When sodium dodecyl sulfate (SDS) is added to the blood plasma in a concentration greater than the critical micelle concentration, we observe an increase in the fluorescence intensity and the polarity index of pyrene. We hypothesize that this is connected with localization of pyrene near the interface between the hydrophobic and hydrophilic phases of the protein-SDS system. We have established that SDS leads to a change in the structure of blood plasma proteins and promotes escape of polycyclic aromatic hydrocarbons from the protein globules.

The experiment LSO (Lightning and Sprite Observations), on board of the International Space Station, was the first experiment dedicated to nadir observations of sprites from space. Such observations are innovative as sprites are generally observed at the horizon. At the nadir, sprites are superimposed with lightning flashes and the observation concept is based on a spectral differentiation of sprites and lightning by using an adapted filter. The experiment is composed of two micro-cameras, fixed on a station window. One camera is equipped with a filter and measures the sprites in the N2 1P most intense sprite emission line, which coincides also to the atmospheric absorption band of the molecular oxygen. The second microcamera provides observations of lightning flashes in the visible. Measurements were performed during four ESA missions: Andromede, Odissea, Cervantes and Delta. During 19h of effective observations, 180 flashes were analyzed and several possible sprites were identified, demonstrating the interest of this differentiation method. In addition during sunset and sunrise conditions when the lower atmosphere is in the dark, LSO observed the airglow of the secondary ozone maximum at about 90 km modulated by gravity wave activity.

We have performed measurements and numerical reconstruction of the temperature dependence of the EPR spectrum of the 2-nitro-1,4-bis(trifluoromethyl)benzene radical anion in anhydrous acetonitrile, caused by dynamic modulation of the fluorine isotropic hyperfine interaction by hindered internal rotation of the CF3 group ortho to the nitro group. The activation energy of rotation is 34.2±0.76 kJ·mol−1.

Temperature dependence of the EPR spectrum of 2-trifluoromethylnitrobenzene radical anion in anhydrous acetonitrile in the temperature range 217 K ≤ T ≤ 296 K was studied and simulated. Temperature-dependent dynamic modulation of the fluorine isotropic hyperfine structure is caused by slow hindered rotation of CF3 group with an activation energy of E F* = 36.5±0.5 kJ mol−1, which is the highest value for motions in π-type free radicals studied to date.

The influence of the human serum albumin (HSA) denaturation by a surface-active substance (sodium dodecyl sulfate (SDS)) on the phosphorescence of a luminescent probe (eosin) has been investigated. The dependences of the eosin-phosphorescence intensity on the SDS concentration were determined at different pH levels of an HSA solution. It has been shown that at SDS concentrations lower than the critical concentration necessary for micelle formation, the hydrophobic interactions of eosin with the protein influence the deactivation of the eosin triplet states.

We provide a physical analysis of the charging and detection of the first few electrons in a laterally-coupled GaAs/AlGaAs quantum dot (LCQD) circuit with integrated quantum point contact (QPC) read-out. Our analysis is based on the numerical solution of the Kohn-Sham equation incorporated into a three-dimensional self-consistent scheme for simulating the quantum device. Electronic states and eigenenergy spectra reflecting the particular LCQD confinement shape are obtained as a function of external gate voltages. We also derive the stability diagram for the first few electrons in the device, and obtain excellent agreement with experimental data.

We study four-dimensional heterotic flux vacua with N=2 spacetime supersymmetry. A worldsheet perspective is used to clarify quantization conditions associated to the fluxes and the constraints these place on the moduli spaces of resulting compactifications. We propose that these vacua fit naturally in the context of heterotic/IIA duality as heterotic duals to compactifications on K3-fibered but not elliptically fibered Calabi-Yau three-folds. We present some examples of such potential dual pairs., Comment: 46 pages; corrected a quantization mistake in section 4.1 as well as a few typos; removed section 4.3 (due to further quantization errors)

Period-doubling bifurcations of the synchronous spin-orbit resonance in the motion of a nonspherical natural planetary satellite along the elliptic orbit are studied. The satellite spin axis is assumed to coincide with the axis of its largest principal moment of inertia and is perpendicular to the orbital plane. The period-doubling bifurcations take place when the value of satellite's dynamical asymmetry parameter falls in the parametric resonance domain. Theoretical dependences of the amplitude of the bifurcation oscillations of a satellite at the pericenter of its orbit upon the eccentricity and dynamical asymmetry parameter are investigated. Three different methods of calculating the amplitude of bifurcation oscillations are presented and compared. These theoretical estimates can be used to predict the opportunity to observe the bifurcation regime. The possibility of the occurrence of the bifurcation regime in the motion of natural planetary satellites is studied. It is concluded that the bifurcation regime is possible in the motion of Deimos, Epimetheus, Helen, Pandora, and Phobos. Phobos is the most probable candidate for finding the bifurcation regime of a synchronous rotation. The identification of such a regime would allow one to impose stringent constraints on the values of the inertial parameters of the satellite observed.

The naturally occurring compounds of thorium ThSiO4, ThSiO4· nH2O, and (Th, Fe)SiO4 and uranium USiO4· nH2O have been studied by X-ray photoelectron spectroscopy in the range of electron binding energies from 0 to 1200 eV. The oxidation state of Th in the natural compounds is close to that in Th(OH)4; for uranium, it is similar to that in UO2. Based on the structure of the low-energy electron spectra it is assumed that the electrons of the filled Th6p- and O2s-atomic orbitals take an active part in chemical bonding. Fine structure was observed in the Th(U)6s-, 5d-, 5p-, 4f-, 4d-, and 4p 3/2 electron spectra of all substances under study. Mechanisms of fine structure formation are discussed and the fine structure parameters are correlated with the physicochemical properties of the compounds.

We enumerate massless E6 singlets for (0,2)-compactifications of the heterotic string on a Calabi-Yau threefold with the "standard embedding" in three distinct ways. In the large radius limit of the threefold, these singlets count deformations of the Calabi-Yau together with its tangent bundle. In the "small-radius" limit we apply Landau-Ginzburg methods. In the orbifold limit we use a combination of geometry and free field methods. In general these counts differ. We show how to identify states between these phases and how certain states vanish from the massless spectrum as one deforms the complex structure or Kaehler form away from the Gepner point. The appearance of extra singlets for particular values of complex structure is explored in all three pictures, and our results suggest that this does not depend on the Kaehler moduli., Comment: 51 pages, oversimplification in spectral sequence fixed

We study (0,2) deformations of a (2,2) supersymmetric gauged linear sigma model for a Calabi-Yau hypersurface in a Fano toric variety. In the non-linear sigma model these correspond to some of the holomorphic deformations of the tangent bundle on the hypersurface. Combinatorial formulas are given for the number of these deformations, and we show that these numbers are exchanged by mirror symmetry in a subclass of the models., Comment: 35 pages; uses xy-fig; typos fixed, acknowledgments added

The structure of Ln2Ti2O7 thin films prepared by pulsed-laser evaporation was studied using X-ray diffraction and transmission electron microscopy. The dependence of structure upon substrate temperature and ionic radius of the rare-earth elements was investigated. The variation of the crystal structure with substrate suggests that the condensation mechanism proceeded within the framework of the vapour-liquid-crystal scheme.

We study the topological heterotic ring in (0,2) Landau-Ginzburg models without a (2,2) locus. The ring elements correspond to elements of the Koszul cohomology groups associated to a zero-dimensional ideal in a polynomial ring, and the computation of half-twisted genus zero correlators reduces to a map from the first non-trivial Koszul cohomology group to complex numbers. This map is a generalization of the local Grothendieck residue. The results may be applied to computations of Yukawa couplings in a heterotic compactification at a Landau-Ginzburg point., Comment: 25 pages; typos fixed; published version

We compute correlators of chiral operators in (0,2) supersymmetric Landau-Ginzburg theories. The class of theories and the correlators we study are relevant for extending and testing mirror symmetry away from the (2,2) locus. More generally, these methods provide alpha'-exact results about certain superpotential couplings in compactifications of the heterotic string., 20 pages; typos corrected; reference added; published version

We compute correlators of non-local observables in a large class of A-twisted massive Landau-Ginzburg and gauged linear sigma models by localization to the discrete vacua. As an application, we present two topological field theories with identical chiral rings and correlators of local observables, which nevertheless differ in the correlators of non-local observables., Comment: 24 pages, JHEP format

We compute the contribution of discrete Coulomb vacua to A-Model correlators in toric Gauged Linear Sigma Models. For models corresponding to a compact variety, this determines the correlators at arbitrary genus. For non-compact examples, our results imply the surprising conclusion that the quantum cohomology relations break down for a subset of the correlators., Comment: 27 pages, 1 xy-pic figure

Synthetic and natural uranium oxides UOx (2≦×≦3) have been studied with X-ray photoelectron spectroscopy (XPS) to determine the phase composition and content of uranium ions in uraninites with a varying degree of oxidation. A strong hybridization of U6p and O2s orbitals has been found which permits a quantitative assessment of the U-O bond lengths. The values of such bonds in some substances have been found to be smaller than those in synthetic U(VI) oxide. The oxides U2O5 and U3O8 contain two types of uranium ions with a varying degree of oxidation.