Position Of Maximum Research Articles

The Neural Correlates of Face-Voice-Integration in Social Anxiety Disorder.

Faces and voices are very important sources of threat in social anxiety disorder (SAD), a common psychiatric disorder where core elements are fears of social exclusion and negative evaluation. Previous research in social anxiety evidenced increased cerebral responses to negative facial or vocal expressions and also generally increased hemodynamic responses to voices and faces. But it is unclear if also the cerebral process of face-voice-integration is altered in SAD. Applying functional magnetic resonance imaging, we investigated the correlates of the audiovisual integration of dynamic faces and voices in SAD as compared to healthy individuals. In the bilateral midsections of the superior temporal sulcus (STS) increased integration effects in SAD were observed driven by greater activation increases during audiovisual stimulation as compared to auditory stimulation. This effect was accompanied by increased functional connectivity with the visual association cortex and a more anterior position of the individual integration maxima along the STS in SAD. These findings demonstrate that the audiovisual integration of facial and vocal cues in SAD is not only systematically altered with regard to intensity and connectivity but also the individual location of the integration areas within the STS. These combined findings offer a novel perspective on the neuronal representation of social signal processing in individuals suffering from SAD.

Intriguing branching of the maximum position of the absorption cross section in Mie theory explained.

A potential control over the position of maxima of scattering and absorption cross sections can be exploited to better tailor nanoparticles for specific light-matter interaction applications. Here we explain in detail the mechanism of an appreciable blue shift of the absorption cross-section peak relative to a metal spherical particle localized surface plasmon resonance (LSPR) defined as the maximum of the extinction (and scattering) cross section. Such a branching of cross sections' maxima requires a certain threshold value of size parameter (x≈0.7 for dipole channel) and is a prerequisite for obtaining high fluorescence enhancements, because the spectral region of high radiative rate enhancement becomes separated from the spectral region of high non-radiative rate enhancement. A consequence is that the maximum of the absorption cross section cannot be used as the definition of the LSPR position for x≳0.7.

1H spin-lattice NMR relaxation in the presence of residual dipolar interactions – Dipolar relaxation enhancement

A model of spin-lattice relaxation for spin-1/2 nuclei in the presence of a residual dipole-dipole coupling has been presented. For slow dynamics the model predicts a bi-exponential relaxation at low frequencies, when the residual dipole-dipole interaction dominates the Zeeman coupling. Moreover, according to the model a frequency-specific relaxation enhancement, referred to as Dipolar Relaxation Enhancement (DRE) in analogy to the Quadrupole Relaxation Enhancement (QRE) is expected. The frequency position of the relaxation maximum is determined by the amplitude of the residual dipole-dipole interaction. Experimental examples of relaxation properties that might be attributed to the DRE are presented. The DRE effect has the potential to be exploited, in analogy to QRE, as a unique source of information about molecular dynamics and structure.

Calculation of the Structure and Properties of Optical Nonlinear Fluorine-Containing Chromophores

Possible modifications of chromophore structures with nonlinear optical properties by bonding F atoms and F-containing groups to the acceptor site of the molecules are considered. Quantum chemical calculations of dipole moments and first hyperpolarizability were performed for several nonlinear chromophores based on N-ethyl- N-(2-hydroxyethyl)-4-phenylazoaniline and modified by the addition of F atoms and F-containing groups to the acceptor site. Positions of maxima in the electronic absorption spectrum and the Mulliken charges on the atoms are found. It is shown that addition of F atoms and F-containing groups to the chromophore acceptor site changes (increases) the efficiency parameter, defined as the product of the dipole moment and the first hyperpolarizability. The main parameters of a waveguide modulator made of an electro-optical polymer composite with F-containing chromophores embedded in it are estimated.

Experimental Study of Space Charge Structure and Expansion Dynamics of Laser Ablation Plasma

Using the method of spectrally selective photorecording in a nanosecond temporal resolution, the distribution of neutral atoms and single- and double-charged gallium ions in a plasma plume is investigated under the conditions of laser ablation of a gallium-indium target and so is the expansion dynamics of both components and the plume as a whole. The expansion velocity of a neutral atomic component of the plume is found. The expansion velocity of the glow boundary and the shift velocity of the glow intensity maximum are found to be close to 8.5∙103 and 6∙103 m/s, respectively. The kinetic energy range, corresponding to these values for the gallium atoms (13–26 eV) is quite consistent with the position of local maximum measured earlier from the energy distribution of single-charged gallium ions.

Luminescent Properties of Mixed-Ligand Neodymium β-Diketonates Obtained in Supercritical Carbon Dioxide in Polymer Matrices of Various Nature

Diverse-ligand phosphor complexes of neodymium acetylacetonate with phenanthroline have been synthesized in polymer matrices (oligourethanmethacrylate, fluoroplast, and polycarbonate) in the medium of supercritical carbon dioxide, while the role of one of the ligands in such complexes is performed by the polymer matrix fragments. The luminescence spectra of the obtained triple systems have been described and it has been shown that the position of the luminescence maxima is bathochromically shifted relative to the Nd(Acac)3/polymer double systems obtained in a similar way and the shift magnitude depends on the polymer matrix nature. It has been shown that when these components are introduced into polymers from a solution, such phosphor diverse-ligand neodymium complexes are not formed. The formation of new Nd(Acac)3/1,10-phenanthroline/polymer structures at the impregnation of oligourethane methacrylate by neodymium β-diketonate and phenanthroline in the supercritical CO2, which are not formed by the introduction of these components from solution, has been confirmed by differential thermal analysis.

Isoquinoline Coumarin Derivatives as Chemiluminescence Activators in Reactions of Lipid Peroxidation

This study deals with participation of isoquinoline derivatives of coumarin in the peroxidase reaction catalyzed by the cytochrome c–cardiolipin complex. We have studied coumarin derivatives called coumarin-314 (C-314), coumarin-334 (C-334) and coumarin-525 (C-525). These substances are considered as specific physical activators of chemiluminescence, which accompanies the lipid peroxidation reaction. In the course of the scientific research, a spectrophotometric study of the effect of methanol on the structure of cytochrome c was performed, the optical properties of these substances were studied in the medium of a phosphate buffer, and a spectrophotometric study was performed with parallel registration of the chemiluminescence of a mixture in which cytochrome c catalyzed by a complex with cardiolipin lipoperoxidase reaction in the presence of isoquinolysin derivatives of coumarin. The conclusions of this work contain identification of the reversibility of the action of methanol on the structure of cytochrome c, which proves the possibility of using this alcohol in the study of this protein, the positions of absorption maxima and corresponding values of molar absorption coefficients in the medium of 20 mM phosphate buffer (pH = 7.4) for C-314 (λmax = 447.5 nm; e = 32360.4 L/(mol cm)), C-334 (λmax = 460 nm; e = 44 012 L/(mol cm)), and C-525 (λmax = 460 nm; e = 32 703.56 L/(mol cm)). We also demonstrated that the said substances are substrates of cytochrome c/cardiolipin complex-catalyzed peroxidase reaction. Mass flow of these substances during an average statistical experiment in measurement of chemiluminescence (322 s) for C-314, C-334 and C-525 amounted to 31.89, 37.61 and 25.94%, respectively.

Moisture regime of enclosing structures with different thickness of insulation layer

Construction industry has different problems including the moisture regime of enclosing structures. If we want to protect an enclosing structure from the negative impact of moisture, we need to evaluate a moisture balance transfer. We used well-known graphical method to calculate the maximum wetting plane positions in three enclosing structures, which are represented the composite insulating systems with external plaster layers, aerated concrete bases and mineral wool insulations. These researching encloses differ only by thicknesses of insulation layers. It was found that the maximum wetting plane is located between the insulation layer and the external plaster layer. Moreover, when the indoor climate parameters change, the position of the maximum wetting plane does not change. However, it is determined that with a significant increase in the thickness of the insulation, the second maximum wetting plane appears inside the aerated concrete layer. This phenomenon was called as «overheating effect». To assess the position of the second maximum wetting plane we developed the criterion “relative displacement coordinate of maximum wetting plane” and obtained the graphic dependence of the introduced criterion and the thickness of the insulation.

Parameters of the Ion Flow of the Pulsed Vacuum Flashover Discharge

The plasma flow parameters of nanosecond vacuum flashover were examined in detail. It was found that high-velocity ion flow could be obtained using significantly more compact and cheap equipment than that used earlier. These new results will be useful to the design of new type compact plasma thrusters. It was proven that the plasma charge composition is formed at the low-voltage phase of vacuum discharge. After the analysis of experimental data, there was not found any clear dependence of the ion spectra and the degree of ionization on the flashover amplitude. The ion flow propagates in wide solid angle (up to 60°) and the ion-energy spectra contain several local maxima. The maxima positions coincide for different charge states of ions. The coincidence can be explained by the formation of plasma waves in the ion flow. The strong dependence of maximum and average ion energies on an ion charge was found. When the short interelectrode gap was used in the vacuum arc, discharge occurred at high-current discharge mode (>200 A), leading to a metal electrode consumption. A plasma acceleration model based on the occurrence of ion-acoustic shock waves was proposed.

Facile Synthesis of Zn Doped g-C3N4 for Enhanced Visible Light Driven Photocatalytic Hydrogen Production

The present work reports a facile strategy to develop L-arginine mediated Zn doped graphitic carbon nitride (g-C3N4) and its enhanced photocatalytic activity. The physicochemical properties of Zn-doped g-C3N4 were studied extensively by XPS, UV–Vis, XRD, SEM and BET analysis. The studied properties of the photocatalyst were then correlated with its photocatalytic hydrogen production rates. Zn doping was evidenced by the presence of Zn-N peak from high-resolution core level XPS spectral analysis. Photocatalytic hydrogen evolution experiments revealed that, upon Zn doping, the hydrogen production rate of g-C3N4 was increased from 34.6 to 78.7 µmol/g.h, i.e. 2.3 times more. The enhancement in the photocatalytic properties after Zn doping was addressed by estimating changes in the positions of conduction band minimum and valence band maximum through XPS valence band spectral analysis.

Tocopheryl Succinate-Induced Structural Changes in DPPC Liposomes: DSC and ANS Fluorescence Studies.

Recent studies show that alpha-tocopheryl succinate (TS) exhibits selective toxicity against cancer cells. In this study, we investigated the effect of TS’s presence on the physico-chemical and structural properties of DPPC liposomes using fluorescence parameters (intensity, lifetime, and position of emission maximum) of 1-anilino-8-naphtalene sulphonate (ANS), differential scanning calorimetry (DSC) and zeta potential methods. Increasing the TS presence in the DPPC gel phase produced ANS fluorescence enhancement with a hypsochromic shift of the maximum. The zeta potential measurements show an increase in the negative surface charge and confirmed that this process is connected with the hydrophobic properties of dye, which becomes located deeper into the interphase region with a progressing membrane disorder. Temperature dependence studies showed that an increase in temperature increases the ANS fluorescence and shifts the ANS maximum emission from 464 to 475 nm indicating a shift from hydrophobic to a more aqueous environment. In the liquid crystalline phase, the quenching of ANS fluorescence occurs due to the increased accessibility of water to the ANS located in the glycerol region. The DSC results revealed that increasing the presence of TS led to the formation of multicomponent DSC traces, indicating the formation of intermediate structures during melting. The present results confirmed that TS embedded into the DPPC membrane led to its disruption due to destabilisation of its structure, which confirmed the measured biophysical parameters of the membrane.

Noninteracting trapped fermions in double-well potentials: Inverted-parabola kernel

We study a system of $N$ noninteracting spinless fermions in a confining, double-well potential in one dimension. When the Fermi energy is close to the value of the potential at its local maximum we show that physical properties, such as the average density and the fermion position correlation functions, display a universal behavior that depends only on the local properties of the potential near its maximum. This behavior describes the merging of two Fermi gases, which are disjoint at sufficiently low Fermi energies. We describe this behavior in terms of a new correlation kernel that we compute analytically and we call it the inverted parabola kernel". As an application, we calculate the mean and variance of the number of particles in an interval of size $2L$ centered around the position of the local maximum, for sufficiently small $L$. Finally, we discuss the possibility of observing our results in experiments, as well as the extensions to nonzero temperature and to higher space dimensions.

INDICI DE APRECIERE A EFICIENŢEI PROCESULUI DE SEPARARE PE O SITĂ CU SUPRAFAȚA DE SEPARARE CONICĂ

The objective of this paper is to present the efficiency of the separation process on a sieve with a conical separation surface, with a vertical shaft and having vibrational motion. Separation intensity curves of rape seeds through circular sieve apertures were drawn by regression analysis of the quantities of material separated at different distances from the central axis of the sieve, using the Gaussian distribution law. The coefficients of the regression equation and the correlation coefficient of the distribution function with experimental data show a high degree of correlation between them. The movement of the material on the sieve and the separation process, in general, was assessed by the position of the distribution curve maximum, depending on the material flow rate.

Surface reconstruction and band alignment of nonmetallic A(II)B(IV)O3 perovskites

Understanding the band alignment at oxide surfaces is of great importance for designing oxide-surface-based electronic, catalytic, and photocatalytic applications. We systematically investigate the band alignment of (001) surfaces of $A(\mathrm{II})B(\mathrm{IV}){\mathrm{O}}_{3}$ perovskites ($A=\mathrm{Ca}$, Sr, Ba, Pb; $B=\mathrm{Ti}$, Zr, Hf, Ge, Sn) through first-principles calculations using semilocal and hybrid functionals. The results are discussed with an emphasis on the effects of surface reconstruction on the band alignment. Reconstructed stoichiometric surfaces are generated by an evolutionary algorithm with surface energy minimization for various surface periodicity units by taking the orthorhombic phase of $\mathrm{CaTi}{\mathrm{O}}_{3}$, the tetragonal phase of $\mathrm{SrTi}{\mathrm{O}}_{3}$, and the cubic phases of $\mathrm{SrTi}{\mathrm{O}}_{3}$ and $\mathrm{BaSn}{\mathrm{O}}_{3}$ as representatives. Two types of reconstruction patterns are obtained as energetically favorable configurations common to these phases, which are composed of half-$A\mathrm{O}$ and -$B{\mathrm{O}}_{2}$ topmost layers, respectively. These reconstructed stoichiometric surfaces have energies comparable to those of nonstoichiometric surfaces, with full $A\mathrm{O}$ or $B{\mathrm{O}}_{2}$ termination under specific chemical potential conditions in $\mathrm{CaTi}{\mathrm{O}}_{3}$ and $\mathrm{SrTi}{\mathrm{O}}_{3}$. We systematically calculate the positions of the valence-band maxima and the conduction-band minima with respect to the vacuum level, namely, the ionization potentials and the electron affinities, for the reconstructed stoichiometric and the nonstoichiometric surfaces of $A(\mathrm{II})B(\mathrm{IV}){\mathrm{O}}_{3}$ perovskites. The ionization potentials and electron affinities at the reconstructed surfaces well describe the termination-plane dependencies of experimentally reported values. The surface band positions are found to show an approximately linear trend against the Goldschmidt tolerance factor, with the sign of slopes opposite to each other for the two types of reconstruction patterns. This tendency is explained by the tolerance-factor dependency of surface rumpling that significantly modifies the surface dipole, although the band positions of $A=\mathrm{Pb}$ systems exhibit a larger deviation from an expected trend due to Pb lone-pair states.

Synthesis of zinc germanium oxynitride nanotube as a visible-light driven photocatalyst for NOx decomposition through ordered morphological transformation from Zn2GeO4 nanorod obtained by hydrothermal reaction

Oxynitrides with narrow band gap are promising materials as visible-light sensitive photocatalysts, because introduction of nitrogen ions can negatively shift the position of valence band maximum of the corresponding oxides to negative side. (Zn1+xGe)(N2Ox) with wurtzite structure is one of the oxynitride materials. (Zn1+xGe)(N2Ox) with nanotube morphology was synthesized by nitridation of Zn2GeO4 nanorods at 800 °C for 6 h. During the nitridation process, the nanorod with smooth surface was transformed into nanotube with rough surface in spite of no template for formation of tube structure. The nanotube formation can be caused by ordered morphological transformation from Zn2GeO4 nanorod during the nitridation. (Zn1+xGe)(N2Ox) nanotube exhibited a large specific surface area due to its nanotube morphology and the ability to be responsive to visible light because of the narrow band gap of 2.76 eV. Compared to (Zn1+xGe)(N2Ox) synthesized by conventional solid state reaction, the optimized (Zn1+xGe)(N2Ox) nanotube possessed enhanced photocatalytic NOx decomposition activity under both ultraviolet and visible light irradiation.

The effect of fluorine–hydrogen treatment on the photoluminescent properties of multilayer (nc-Si–SiOx–SiOy)n nanostructures with porous barrier layers

In this work, the investigations of spectral characteristics and kinetics of photoluminescence (PL) of light-emitting multilayer (nc-Si–SiOx–SiOy)n structures were performed. Such superlattices were formed on c-Si substrates by thermal deposition in vacuum of n = 30–40 pairs of solid SiOx nanolayers and barrier porous SiOy nanolayers (x < y ≤ 2) and subsequent high-temperature annealing and passivation in HF vapor. In this structure, the solid SiOx layers are active, and during annealing, the light-emitting nc-Si silicon nanoparticles are formed in them. It was found that for such samples, the position of PL maximum and its intensity depend on two factors: thickness of the active layers and time of passivation in HF vapor. This makes it possible to control the spectral composition and intensity of PL radiation, changing both the thickness of the initial layers of the superlattices and time of passivation.

Donor–Pyrene–Acceptor Distance-Dependent Intramolecular Charge-Transfer Process: A State-Specific Solvation Preferred to the Linear-Response Approach

Photoinduced intramolecular charge-transfer (ICT) molecules are important in various applications such as a probe for single-molecule spectroscopy, cell imaging, laser dyes, biomarkers, solar cells, in photosynthesis, etc. Here, we report a new set of substituted pyrene dye molecules, N,N-dimethylamino nitrilo pyrene and its higher analogues, containing pull–push donor (D)–chromophore (π)–acceptor (A) functional groups with enhanced photophysical characteristics like oscillator strength, light-harvesting, and ICT properties. The excited-state ICT process has been established by quantum chemical calculations using the density functional theory method in vacuo and in solvents of different polarity and hydrogen-bonding ability using linear-response (LR) and state-specific (SS) solvation approaches with gradually increasing the D–A distance. The studied molecules show solvent polarity-dependent larger Stokes’ shifts (3609–9016 cm–1, in acetonitrile), higher excited-state dipole moments (11.7–16.8 Debye, in acetonitrile), higher possibilities of highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) electronic transitions, etc., which support the occurrence of the excited-state ICT process. Here, we demonstrate how to increase the efficiency of the ICT process and also tune the ICT fluorescence maximum. We find that with a variation of the D–A distance, studied molecules show a noticeable effect on the spectroscopic and molecular properties such as the position of absorption and fluorescence band maxima, Stokes’ shift, dipole moment, light-harvesting, and ICT properties. We also show that the SS solvation approach is more supportive than the LR method to the ICT process.

The formation of porous silicon by irradiation with low-energy ions

The paper presents experimental data on the formation of porous layers in silicon by high-dose (>1015 ions/cm2) implantation of low-energy ions (≤30 keV). The pore diameter in the plane of the parallel surface is almost two orders of magnitude larger than their size in the plane perpendicular to the surface. Pores are formed as a result of the formation of local melts in the surface layer from “overheated” thermal spikes. Pores are formed in the process of solidification of the melts due to the difference in the volume of solid and liquid phases. The combination of “nano-pores” in the process of subsequent ion irradiation and (or) post implantation annealing leads to the formation of “micro-pores”. During ion sputtering, pores can “come out” to the surface, creating a surface relief such as pits. In the case of very dense targets and heavy (or cluster) ions, conditions arise for the formation of a sponge-like surface. Porous Si layers are characterized by luminescence with a spectrum close to white light. The position of the spectrum maximum depends on the irradiation and annealing regimes. Silicon nanocrystals forming the pore surface, as well as a thin oxide film on the surface of nanocrystals, are responsible for the observed luminescence.

Low-Temperature Luminescent Studies of Emissive Guanine Substitute for the Detection of Biopolymers

The optical absorption at 300 K and the fluorescence and phosphorescence at 78 K of the emissive guanine substitute, deoxythienoguanosine, (dthG) were investigated in aqueous and TRIS-HCl-buffer solutions. Two optical absorption and fluorescence centers at room temperature were attributed to two keto-enol tautomers of dthG, which confirms previously obtained results. In contrast to room temperature, only one emission band was observed at 78 K in fluorescence spectra that was close to the long-wave fluorescence band at room temperature and could be associated with the tautomer with long-wave absorption. This phenomenon can be explained by the energy transfer by excitations in a frozen solution between two types of the optical centers mentioned above. The similar conclusion is drawn for the phosphorescence: only one tautomer phosphorescence band is observed. The spectral positions of this band maximum are essentially different for aqueous and buffer solutions (∼50 nm).

How far poleward can the seasonal precipitation maxima over land extend under high obliquity?

The seasonal response of the poleward extent of continental precipitation maxima to high obliquity and its controlling mechanisms are examined using the NCAR-CESM and Budyko-Sellers energy balance model. In CESM, the latitude of the poleward-most continental precipitation maximum (denoted as $${\phi }_{mp})$$ migrates poleward with increased obliquity, but is limited to equatorward of the latitude of maximum daily insolation. Some insight is gained on the controlling mechanism of the migration of $${\phi }_{mp}$$ in the Budyko–Sellers model, assuming $${\phi }_{mp}$$ coinciding with the position of maximum surface moist static energy (denoted as $${\Theta }_{mp}$$) as in the present-day observation and CESM pre-industrial simulation. Heat capacity exerts a primary control on $${\phi }_{mp}$$ such that $${\phi }_{mp}$$ is determined by the position of maxima of accumulated insolation over the radiative relaxation time and therefore lies equatorward of the maximum daily insolation. Variations of surface albedo and horizontal heat transport, as secondary effects, further shift the $${\phi }_{mp}$$. This understanding from the Budyko-Sellers model, however, fails in CESM in the case of high obliquity of 40°, with $${\phi }_{mp}$$ now lying equatorward of $${\Theta }_{mp}$$. This separation between $${\phi }_{mp}$$ and $${\Theta }_{mp}$$ is explained by the constraint of rotation on the latitudinal range of weak temperature gradients, which is the prerequisite for the prediction of $${\phi }_{mp}$$ from $${\Theta }_{mp}$$. When the rotation rate is reduced, the latitudinal range of weak temperature gradients expands poleward roughly following the change of the equatorial Rossby radius, allowing $${\phi }_{mp}$$ moving close to $${\Theta }_{mp}$$.