Membrane potential is involved in regulation of photosynthetic reactions in the marine diatom Thalassiosira weissflogii

High-intensity Chl fluorescence transients (OJIP transients) and light-induced kinetics of the delayed light emission were measured in diatom microalga Thalassiosira weissflogii in the presence of various uncouplers and photosynthetic inhibitors. The I step in the OJIP transients in T. weissflogii was essentially reduced or completely absent but was restored in the presence of uncouplers valinomycin, FCCP, and nigericin. Moreover, valinomycin enhanced ΔpH-dependent non-photochemical fluorescence quenching following the OJIP rise. In the presence of valinomycin, the transthylakoid membrane potential was significantly inhibited as evaluated by measurements of the delayed light emission. The results suggest a membrane potential control of the fluorescence yield in T. weissflogii. Possible mechanisms underlying the observed effects of uncouplers are discussed.     

On topological Clifford semigroups embeddable into products of cones over topological groups

In this paper we give characterizations of topological Clifford semigroups which are embeddable into Tychonoff products of topological semilattices and cones over topological groups. Also we characterize topological Clifford semigroups which embed into compact topological Clifford semigroups.     

Distribution of light alkanes in the reaction of graphite hydrogenation at pressure of 0.1–7.8 GPa and temperatures of 1000–1350°C

ABSTRACT

We studied the effect of pressure and temperature on the hydrocarbon (HC) chain length distribution and total amount of HCs in the reaction of direct graphite hydrogenation at pressures of 0.1–7.8?GPa and temperatures of 1000–1350°C. An increase in pressure was found to lead both to an increase in the absolute yield of HCs due to direct graphite hydrogenation and to chain elongation of HC products. Light alkanes predominate among HCs in the entire studied range of P–T parameters. However, their concentration in quenched fluids increases as pressure is elevated, from less than 10?rel.% at 0.1?GPa to more than 40–50?rel.% at P?≥?3.8?GPa. Methane is actually the only light alkane among reaction products at 0.1?GPa and 1000°C, while it is a minor component at 7.8?GPa and 1350°C. The most stable alkane at pressures above 3.8?GPa is ethane (C₂H₆).     

A spectral characterization of skeletal maps

We prove that a map between two realcompact spaces is skeletal if and only if it is homeomorphic to the limit map of a skeletal morphism between ω-spectra with surjective limit projections.     

Lift zonoid and barycentric representation on a Banach space with a cylinder measure

We show that the lift zonoid concept for a probability measure on $ {{\mathbb{R}}^d} $ , introduced in [G.A. Koshevoy and K. Mosler, Zonoid trimming for multivariate distributions, Ann. Stat., 25(5):1998–2017, 1997], naturally leads to a oneto-one representation of any interior point of the convex hull of the support of a continuous measure as the barycenter w.r.t. this measure of either a half-space or the whole space. We prove an infinite-dimensional generalization of this representation, which is based on the extension of the concept of lift zonoid for a cylindrical probability measure.     

Representation of a Monotone Curve by a Contour with Regular Change in Curvature

The problem of modelling a smooth contour with a regular change in curvature representing a monotone curve with specified accuracy is solved in this article. The contour was formed within the area of the possible location of a convex curve, which can interpolate a point series. The assumption that if a sequence of points can be interpolated by a monotone curve, then the reference curve on which these points have been assigned is monotone, provides the opportunity to implement the proposed approach to estimate the interpolation error of a point series of arbitrary configuration. The proposed methods for forming a convex regular contour by arcs of ellipses and B-spline ensure the interpolation of any point series in parts that can be interpolated by a monotone curve. At the same time, the deflection of the contour from the boundaries of the area of the possible location of the monotone curve can be controlled. The possibilities of the developed methods are tested while solving problems of the interpolation of a point series belonging to monotone curves. The problems are solved in the CAD system of SolidWorks with the use of software application created based on the methods developed in the research work.     

Dynamics of Alternating Spin Chains

We consider the dimerised spin- isotropic XY chain in a transverse field and study the xx and zz dynamic structure factors for different values of the Hamiltonian parameters and temperature.     

Neutron alignment at high spin in 156Dy

Utilizing the transient magnetic field interaction for nuclear recoils passing through an iron or a gadolinium foil, we have measured the precessions for discrete γ-ray transitions in the reaction ²⁴Mg(¹³⁶Xe,4n)¹⁵⁶Dy at 600 and 620 MeV incident beam energy. The average nuclear g-factors deduced at spins between 19 and 23? are in accord with one previous measurement and in contradiction with another. The present results imply the predominant population of neutron-aligned bands near the backbend in ¹⁵⁶Dy.     

Measurement of g-factors in 170Yb, 172Yb and 174Yb by transient field interaction at high recoil velocities

A beam of ⁴⁰Ca ions at 168 MeV has been used to Coulomb excite high-spin states in ¹⁶⁹Tm and ^{170, 172, 174}Yb which recoiled through thin polarized iron at ν/c ≈ 3.5%. An enhanced transient field ≈ 6 times larger than the Lindhard-Winther prediction was observed and calibrated against the known g-factors in ¹⁶⁹Tm. Individual g-factors could not be extracted because of strong feeding; nevertheless, deviations from rotational behaviour (constant g-factors) would be detectable. Empirical fits to microscopic calculations of the rotational g-factors below spin 12⁺ suggest that if deviations from the simple rotational formula occur, they should be of the form g(J) = g₀(1 + αJ²). We find the following values in ^{170, 172, 174}Yb: α × 10³ = ?0.5±1.5, +1.0±1.5. The uncertainties are the level at which deviations from rotational behaviour are expected to occur. The results are discussed in terms of Coriolis anti-pairing effects.     

First-principles calculation of nuclear resonance vibrational spectra

We present a ‘first-principles’ methodology for the calculation of the parameters that are required for the simulation of nuclear resonance vibrational spectra (NRVS) of molecular systems. Formulae are given for the intensities of vibrational transitions corresponding to the so-called single- and double-phonon contributions to the NRVS signal. The method is also valid for those vibrations that are not in the high-frequency/low-temperature limit. We have rigorously treated the issue of orientational averaging of the Lamb–Mössbauer factor and the effect of the neglect of its anisotropy on the calculated NRVS pattern. Normal mode composition factors are determined in a compact form as appropriate components of an orthogonal matrix that diagonalizes the Hessian matrix. The method is illustrated by simulating the NRVS spectra and the partial vibrational density of states of [FeO(H₂O)5]²⁺ on the basis of vibrational frequencies and normal mode composition factors obtained from density functional theory (DFT) calculations.