Direct and mediated electron transfer catalyzed by anionic tobacco peroxidase

The properties of anionic tobacco peroxidase (TOP) adsorbed on graphite electrode have been studied in direct and mediated electron transfer in a wall-jet flow injection system. The percentage of tobacco peroxidase molecules active in directelectron transfer is about 83%, which is higher than that for horeradish peroxidase (40–50%). This observation is explained in terms of the lower degree of glycosylation of TOP compared with horseradish peroxidase and, therefore, a reduced in terference from the oligosaccharide chains with direct electron transfer. Calcium ions cause an 11% drop in the reaction rate constant toward hydrogen peroxide. The detection limit of calcium chloride has been estimated as 5 m M. The results obtained by means of bioeletrochemistry, stopped-flow kinetics, and structural modeling provide evidence for the interaction between calcium cations and negatively charged residues at the distal domain (Glu-141, heme propionates, Asp-79, Asp-80) blocking the activesite. The observation that both soluble and immobilized enzyme under go conformational changes resulting in the blockade of the active site indicates that the immobilized enzyme preserves conformational flexibility. An even stronger suppressing effect of calcium ions on the rate constant for mediated electron transfer was observed. In the case of direct electron transfer, this couldmean that there is nodirect contact between the electrode and the active site of TOP. The electrons are shuttled from the active site to the surface of the electrode through electron transfer pathways in the protein globule that are sensitive to protein conformational changes.     

Nature of the first exothermic peak on the DSC curve of linear polydicyclopentadiene obtained with a special catalytic system

A DSC and TGA study of linear polydicyclopentadiene (L-PDCPD) shows that the thermal behaviour of this polymer is characterized by an endothermic and two exothermic processes. In previous work it was demonstrated that the endothermic process is a glass transition and the second exotherm represents the thermo-oxidation of the polymer. In this work the first exothermic process is shown to be a possible thermal polymerization of the double bonds in the polymer chains.     

Controllability of a Nonholonomic Macroeconomic System

This paper studies optimal control problems and sub-Riemannian geometry on a nonholonomic macroeconomic system. The main results show that a nonholonomic macroeconomic system is controllable either by trajectories of a single-time driftless control system (single-time bang–bang controls), or by nonholonomic geodesics or by sheets of a two-time driftless control system (two-time bang–bang controls). They are strongly connected to the possibility of describing a nonholonomic macroeconomic system via a Gibbs–Pfaff equation or by four associated vector fields, based on a contact structure of the state space and our isomorphism between thermodynamics and macroeconomics that praises three laws of a nonholonomic macroeconomic system.     

Biharmonic ideal hypersurfaces in Euclidean spaces

Let $x:M\to {\mathbb{E}}^m$ be an isometric immersion from a Riemannian n-manifold into a Euclidean m-space. Denote by Δ and $\overrightarrow{x}$ the Laplace operator and the position vector of M, respectively. Then M is called biharmonic if ${\mathrm{\Delta }}^2\overrightarrow{x}=0$. The following Chen?s Biharmonic Conjecture made in 1991 is well-known and stays open: The only biharmonic submanifolds of Euclidean spaces are the minimal ones. In this paper we prove that the biharmonic conjecture is true for $\delta (2)$-ideal and $\delta (3)$-ideal hypersurfaces of a Euclidean space of arbitrary dimension.     

Riemannian submersions, δ-invariants, and optimal inequality

In this study, we establish a sharp relation between δ-invariants and Riemannian submersions with totally geodesic fibers. By using this relationship, we establish an optimal inequality involving δ-invariants for submanifolds of the complex projective space CP ^m (4) via Hopf’s fibration ${\pi:S^{2m+1}\to CP^{m}(4)}$ . Moreover, we completely classify submanifolds of complex projective space which satisfy the equality case of the inequality.     

Effects of localized gate stack parasitic charge on current-voltage characteristics of double-gate MOSFETs with high-permittivity dielectrics and Ge-channel

In this paper we investigate the effects of localized gate stack parasitic charges on the current-voltage characteristics of double-gate (DG) MOSFET with metal/high-permittivity/Ge-channel using two-dimensional (2-D) numerical simulation. For this purpose a simulation code is developed, solving the Poisson equation on the entire device coupled self-consistently with the drift-diffusion transport equation. We show that the charges trapped at grain boundaries in the high-permittivity (high-κ) layer induce 2-D potential fluctuations in the structure, not only in the high-κ layer, but also in the underlying oxide and semiconductor regions. These potential fluctuations are shown to significantly degrade the subthreshold behavior of the drain current. The off-state drain current and the subthreshold slope increase with respect to the case where no charge is present in the gate stack. The influence of the location of the charged grain boundaries in the stack on the subthreshold parameters is also investigated using the 2-D numerical simulation code.     

Surfaces with constant mean curvature in Sol geometry

Among the eight geometries of Thurston, Sol₃ is the space with the smallest number of isometries, for example, there are no rotations. In this work, we classify all surfaces with constant mean curvature that either are invariant by a 1-parameter group of isometries or are the product of two planar curves.     

Constant angle surfaces in the Heisenberg group

In this article we extend the notion of constant angle surfaces in $ \mathbb{S}^2 $ \mathbb{S}^2 × ℝ and ℍ² × ℝ to general Bianchi-Cartan-Vranceanu spaces. We show that these surfaces have constant Gaussian curvature and we give a complete local classification in the Heisenberg group.     

Constant angle surfaces in ℍ<Superscript>2</Superscript> × ℝ

We classify all surfaces in ℍ² × ℝ for which the unit normal makes a constant angle with the ℝ-direction. Here ℍ² is the hyperbolic plane. The author was supported by grants CEEX ET 5883/2006-2008 and PNII ID_ 398/2007-2010 ANCS (Romania).