Plasticity of histamine H<Subscript>3</Subscript>receptor expression and binding in the vestibular nuclei after labyrinthectomy in rat

Background  

In rat, deafferentation of one labyrinth (unilateral labyrinthectomy) results in a characteristic syndrome of ocular and motor postural disorders (e.g., barrel rotation, circling behavior, and spontaneous nystagmus). Behavioral recovery (e.g., diminished symptoms), encompassing 1 week after unilateral labyrinthectomy, has been termed vestibular compensation. Evidence suggesting that the histamine H₃ receptor plays a key role in vestibular compensation comes from studies indicating that betahistine, a histamine-like drug that acts as both a partial histamine H₁ receptor agonist and an H₃ receptor antagonist, can accelerate the process of vestibular compensation.     

Probing the isomer,fluorination and bond effects in C<Subscript>3</Subscript>H<Subscript>6</Subscript>, cyclo-C<Subscript>3</Subscript>H<Subscript>6</Subscript> and C<Subscript>3</Subscript>F<Subscript>6</Subscript> molecules using electron impact

We have carried out experimental and theoretical studies on electron scattering from the C₃H₆ isomers and C₃F₆ molecules and we report on total, differential as well as theoretical integral elastic cross-sections for these molecules. Vibrational excitation functions are also presented for the typical vibrational peaks in C₃H₆ and cyclo-C₃H₆ for the angle of 90^○, impact energy range of 1–16 eV and loss energies of 0.12 eV and 0.13 eV, respectively. In the cross-sections, clear differences in peak positions and magnitudes between the C₃H₆ isomers can be viewed as the isomer effect. The same is observed between C₃H₆ and C₃F₆ in a clear manifestation of the fluorination effect. The resemblance of the π^* shape resonance in the cross-sections, observed at about 2.2 eV for C₃H₆ and 3.5 eV for C₃F₆, to those in C₂H₄ and C₂F₄ clearly points to the effect of the double bond in the molecular structures for these molecules. Theoretical analysis is performed to provide rationales for the scattering dynamics.     

Kinetics of low-temperature initiation of H<Subscript>2</Subscript>/O<Subscript>2</Subscript>/H<Subscript>2</Subscript>O mixture combustion upon the excitation of molecular vibrations in H<Subscript>2</Subscript>O molecules by laser radiation

The initiation of H₂/O₂/H₂O mixture combustion when asymmetric vibrations in H₂O molecules are excited by a resonant IR laser radiation is considered. It is shown that the vibrational excitation of the molecules gives rise to new efficient channels for the formation of chemically active O and H atoms and OH radicals. As a result, the chain mechanism of combustion in the mixtures is enhanced and, as a consequence, the induction time is cut and the ignition temperature is lowered. Even at a minor radiant energy flux delivered to the gas (E_in≈2.5 J/cm²), the ignition temperature of the stoichiometric H₂/O₂ mixture containing only 5% of H₂O may become as low as 300 K.     

Quasi-reversible solid-phase reaction in the superprotonic conductor Cs<Subscript>5</Subscript>H<Subscript>3</Subscript>(SO<Subscript>4</Subscript>)<Subscript>4</Subscript>·<Emphasis Type="Italic">x</Emphasis>H<Subscript>2</Subscript>O

The thermal effect and heat capacity in a single crystal of nonstoichiometric cesium sulfate hydrate were measured. It was established that superprotonic conduction in this material is caused by an isothermal solid-phase transformation in the bulk of the single crystal. The results of thermal measurements were compared with experimental data on the electrical conductivity.     

Entanglement in the linear-chain Heisenberg antiferromagnet Cu(C<Subscript>4</Subscript>H<Subscript>4</Subscript>N<Subscript>2</Subscript>)(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Quantum correlations are generally impossible to address directly in bulk systems. Quantum measures extended only to a few number of parties can be discussed in practice. In the present work we study a cluster of spins belonging to a compound whose structure is that of a quantum magnet. We reproduce at a much smaller scale the experimental outcomes and then we study the role of quantum correlations there. A macroscopic entanglement witness has been introduced in order to reveal quantum correlations at nonzero temperatures. The critical point beyond which entanglement is zero is found at T _c = 15 K.     

EPR spectra of aerosol particles formed by pyrolysis of C<Subscript>3</Subscript>H<Subscript>8</Subscript> plus Ar and C<Subscript>3</Subscript>H<Subscript>8</Subscript> plus Fe(CO)<Subscript>5</Subscript> plus Ar mixtures in a flow reactor

The paper is devoted to electron paramagnetic resonance investigation of nanoparticles and aggregates of nanoparticles formed by pyrolysis of propane as well as a mixture of propane and iron pentacarbonyl. The measurement showed that the pyrolysis of the C₃H₈ plus Ar mixture results in the formation of a carbonaceous phase (phase I), which is quite different from that formed by the C₃H₈ plus Fe(CO)₅ plus Ar mixture (phase II). In phase I there is a strong oxygen effect for as-prepared samples; 75% of spins are accessible to the environmental gas via the interconnected system of microvoids and microchannels. In phase II there was a weak oxygen effect for the as-prepared samples. However, after exposition of phase II to air for 160 h, the properties of phase II have become about the same as that of phase I. A strong oxygen effect was observed for the air-exposed phase II. The line width for phase II increases monotonically with the iron content in the sample. This increase is probably related to the dipole-dipole interactions between the radical centers and the iron atoms distributed throughout the carbon matrix.     

Quasi-one-dimensional quantum spin liquid in the Cu(C<Subscript>4</Subscript>H<Subscript>4</Subscript>N<Subscript>2</Subscript>)(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> insulator

We analyze measurements of the magnetization, differential susceptibility and specific heat of quasi-onedimensional insulator Cu(C₄H₄N₂)(NO₃)₂ (CuPzN) subjected to magnetic fields. We show that the thermodynamic properties are defined by quantum spin liquid formed with spinons, with the magnetic field tuning the insulator CuPzN towards quantum critical point related to fermion condensation quantum phase transition (FCQPT) at which the spinon effective mass diverges kinematically. We show that the FCQPT concept permits to reveal and explain the scaling behavior of thermodynamic characteristics. For the first time, we construct the schematic T–H (temperature-magnetic field) phase diagram of CuPzN that contains Landau–Fermi-liquid, crossover and non-Fermi liquid parts, thus resembling that of heavy-fermion compounds.     

Magnetic properties of the tetranitrosyl-iron complex Fe<Subscript>2</Subscript>(SC<Subscript>3</Subscript>H<Subscript>5</Subscript>N<Subscript>2</Subscript>)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>

The magnetic properties of the binuclear nitrosyl-iron complexes Fe₂(SC₃H₅N₂)₂(NO)₄ are investigated. It is demonstrated that several types of particles, such as dimers with a pair of spins 1/2, dimers with a pair of spins 5/2, and paramagnetic particles with spin 3/2, make a contribution to the magnetic properties of the complexes. A decrease in the temperature below 25 K leads to a change in the shape of the EPR spectra corresponding to these dimers, so that Lorentzian lines (homogeneous broadening) transform into Gaussian lines (inhomogeneous broadening). This is accompanied by a stepwise change in the EPR line width and g factors. The change in the line shape indicates that complexes become asymmetric at low temperatures, possibly, due to the decrease in the spin exchange frequency below the frequency of the microwave field of the spectrometer.     

H<Subscript>2</Subscript>O/CuIn<Subscript>3</Subscript>Se<Subscript>5</Subscript> photoelectrochemical cells: Fabrication and properties

Single-phase coarse-grained CuIn₃Se₅ ingots are grown by horizontal oriented crystallization from the near-stoichiometric melt. Photosensitive structures based on the interface between these crystals and an electrolyte (H₂O) are created. It is shown that the CuIn₃Se₅ ternary compound is a direct-gap semiconductor with an energy gap Eg ≃ 1.1 eV (T = 300 K). H₂O/CuIn₃Se₅ photoelectrochemical cells seem to be promising for efficient wide-band photodetectors of natural light.     

Molecular structure of tris(acetylacetonato)scandium Sc(C<Subscript>5</Subscript>H<Subscript>7</Subscript>O<Subscript>2</Subscript>)<Subscript>3</Subscript>

Molecular structure of tris(acetylacetonato)scandium, Sc(C₅H₇O₂)₃, is investigated by gas-phase electron diffractometry. The main structural parameters of the molecule are evaluated. The average intemuclear distances and angles correspond to C₃ symmetry. The chief structural motif is trigonal antiprisms of six oxygen, carbon, and hydrogen atoms with a scandium atom at the center. It is found that r_g[Sc-O) = 204.1(8) pm and r_g(C−O) = 124.7(4) pm Translated fromZhurnal Struktumoi Khimii, Vol. 39, No. 4, pp. 633–639, July–August, 1998.     

Synthesis,thermal and electrical behavior of the superprotonic conductor phase in Rb<Subscript>3</Subscript>(HSeO<Subscript>4</Subscript>)<Subscript>2.5</Subscript>(H<Subscript>2</Subscript>PO<Subscript>4</Subscript>)<Subscript>0.5</Subscript> compound

The Rb₃(HSeO₄)_2.5(H₂PO₄)_0.5 compound was prepared and its thermal behavior and electric properties were investigated. The thermogravimetry (TGA) analysis and the differential scanning calorimetric (DSC) show the presence of a structural phase transition of the title compounds at 374 K which is confirmed by the variation of fp and σ_dc as a function of temperature. The complex impedance of the Rb₃(HSeO₄)_2.5(H₂PO₄)_0.5 compound has been investigated in the temperature range of 295–453 K and in the frequency range 209 Hz–1 MHz. The impedance plots show semicircle arcs at different temperatures, and an electrical equivalent circuit has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance Rp and constant phase elements CPE₁ in series with fractal capacity CPE₂. The frequency dependence of the conductivity is interpreted in terms of Jonscher’s law. The conductivity dc follows the Arrhenius relation. The near value of activation energies obtained from the analysis of modulus, conductivity data, and circuit equivalent confirm that the transport is through the ion hopping mechanism, dominated by the motion of the H⁺ proton in the structure of the investigated materials.     

Geometry of the internal dynamics of C<Subscript>2</Subscript>H<Stack><Subscript>3</Subscript><Superscript>+</Superscript></Stack> carbocation

Using the symmetry group chain methods, the internal dynamics of the simplest carbocation, C₂H ₃ ⁺ , is analyzed under the traditional assumptions that the equilibrium structures of the carbocation are planar and that the nonrigid motion between them is in-plane. This geometry of the internal dynamics is shown to agree with the data of the microwave spectroscopy on the splittings of rotational energy levels caused by the nonrigid motion. Previously, this statement was based on the model that violated the requirement of self-adjointness of operators of physical quantities.     

Kinetics of C<Subscript>10</Subscript>H<Subscript>7</Subscript>Br Pyrolysis

The temperature and pressure-dependent rate constants for the process C₁₀H₇Br ? C₁₀H₇+Br were evaluated using the variable reaction coordinate transition state theory VRC-TST. The calculated rate constants and computational fluid dynamics (CFD) calculations were employed to estimate the pyrolysis efficiency of 2-bromonaphthalene in the resistively-heated SiC high-temperature “chemical reactor” at the temperature of about 1500 K. The observed 40% pyrolysis efficiency is reproduced by CFD calculations if the value of the calculated rate constant for the C₁₀H₇Br pyrolysis is increased by a factor of 2.     

Hyperfine structure in EPR spectra of the catalytic system TiCl<Subscript>4</Subscript> + Al(i-C<Subscript>4</Subscript>H<Subscript>9</Subscript>)<Subscript>3</Subscript>

In an EPR study of the catalytic system TiCl₄ + Al(i-C₄H₉)₃ in toluene and isopentane in TiCl₄/oligopiperylene + Al(i-C₄H₉)₃ in toluene, we have observed a dependence of the linewidth of the hyperfine structure on the mobility of the complex in solution. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 174–177, March–April, 2007.     

Synthesis,crystal structure,Hirshfeld surface analysis,and vibrational and DFT investigation of [C<Subscript>6</Subscript>H<Subscript>10</Subscript>(NH<Subscript>3</Subscript>)<Subscript>2</Subscript>]<Subscript>3</Subscript>CuBr<Subscript>4</Subscript>.3Br

Single crystal of a new organic–inorganic hybrid material [C₆H₁₀(NH₃)₂]₃CuBr₄.3Br was synthesized by the slow evaporation method at room temperature and characterized by X-ray diffraction, FTIR, Raman spectroscopy, UV–Vis, dielectric measurements, and Hirschfield surface analysis. The title compound crystallizes in trigonal system \( P\overline{3} \).The crystal packing is governed by the N-H…Br and non-classical C-H…Br hydrogen-bonding interactions between the 1, 2-diamoniumcyclohexane cations, the tetrahedral [CuBr₄]^3? anions, and the isolated ion Br^?. Theoretical calculations were performed using density functional theory (DFT) for studying the molecular structure, vibrational spectra, and optical properties of the investigated molecule in the ground state. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The optical properties were investigated by optical absorption and show two bands at 260 and 305 nm.     

Electrical characterization of the [N(CH<Subscript>3</Subscript>)<Subscript>4</Subscript>][N(C<Subscript>2</Subscript>H<Subscript>5</Subscript>)<Subscript>4</Subscript>]ZnCl<Subscript>4</Subscript> compound

The [N(CH₃)₄][N(C₂H₅)₄]ZnCl₄ compound has been synthesized by a solution-based chemical method. The X-ray diffraction study at room temperature revealed an orthorhombic system with P2₁2₁2 space group. The complex impedance has been investigated in the temperature and frequency ranges 420–520 K and 200 Hz–5 MHz, respectively. The grain interior and grain boundary contribution to the electrical response in the material have been identified. Dielectric data were analyzed using the complex electrical modulus M ^* for the sample at various temperature. The modulus plots can be characterized by full width at half height or in terms of a non-exponential decay function ϕ(t) = exp[(−t/τ) ^β ]. The detailed conductivity study indicated that the electrical conduction in the material is a thermally activated process. The variation of the AC conductivity with frequency at different temperatures obeys the Almond and West universal law.     

Retardation of polarization in mixed K<Subscript>0.88</Subscript>(NH<Subscript>4</Subscript>)<Subscript>0.12</Subscript>H<Subscript>2</Subscript>PO<Subscript>4</Subscript> crystal

The time dependences of polarization of K_0.88(NH₄)_0.12H₂PO₄ mixed crystal have been studied within the temperature range of 74–100 K. Two mechanisms of polarization relaxation were found. The first mechanism is caused by domain walls lateral motion and their interaction with point lattice defects. The second one supposedly is due to polar regions infiltration through the regions of frustrated paraelectric phase.     

Magnetic ground state and multiferroicity in BiMnO<Subscript>3</Subscript>

We argue that the centrosymmetric C2/c symmetry in BiMnO₃ is spontaneously broken by antiferromagnetic (AFM) interactions existing in the system. The true symmetry is expected to be Cc, which is compatible with the noncollinear magnetic ground state, where the ferromagnetic order along one crystallographic axis coexists with the hidden AFM order and related to it ferroelectric polarization along two other axes. The C2/c symmetry can be restored by the magnetic field B ∼ 35 T, which switches off the ferroelectric polarization. Our analysis is based on the solution of the low-energy model constructed for the 3d-bands of BiMnO₃, where all the parameters have been derived from the first-principles calculations. Test calculations for isostructural BiCrO₃ reveal an excellent agreement with experimental data. The article is published in the original.