Computerized modeling of adenosine triphosphate, adenosine triarsenate and adenosine trivanadate

Computerized molecular models of adenosine triphosphate, adenosine tri-arsenate and adenosine trivanadate have been generated using the molecular mechanics technique. The analysis of structural parameters indicated that, at least theoretically, adenosine triarsenate is a realistic candidate for replacement of adenosine triphosphate in biochemical pathways. On the contrary, the structural arrangement of the inorganic segment of adenosine trivanadate does not seem to be capable of withstanding a swift hydrolytical splitting in aqueous milieu. It was shown that the universal force field as implemented in Gaussian software packages is an appropriate tool for the optimization of less-common bioactive compositions.     

Characterizing the fluorescence intermittency and photobleaching kinetics of dye molecules immobilized on a glass surface

The blinking behavior of single Atto565 molecules on a glass surface is studied under air or nitrogen atmospheres using confocal microscopy. The broad distributions for both on- and off-time durations obey power law kinetics that are rationalized using a charge tunneling model. In this case, a charge is transferred from the Atto565 molecule to localized states found on the glass surface. Subsequent charge recombination by back charge tunneling from trap to Atto565 cation (i.e., dark state) restores the fluorescence. The off-time distribution is independent of excitation intensity (I), whereas the on-time distribution exhibits a power law exponent that varies with I. Two pathways have been identified to lead to the formation of the radical dark state. The first involves direct charge tunneling from the excited singlet S1 state to charge traps in the surrounding matrix, and the second requires charge ejection from the triplet T1 state after intersystem crossing from S1. Monte Carlo simulation studies complement the two-pathway model. Photobleaching curves of both single and ensemble molecules do not exhibit monoexponential decays suggesting complex bleaching dynamics arising from triplet and radical states.     

Adsorption preconcentration in the luminescence determination of polycyclic aromatic hydrocarbons

The adsorption of polycyclic aromatic hydrocarbons (PAHs)—pyrene, anthracene, phenanthrene, and fluorene—by a cellulose matrix of micellar media containing sodium dodecyl sulfate and a nonionogenic polymer, namely, polyethylene glycol is studied. Procedures are proposed for the luminescence determination of PAHs in the adsorbent phase.     

Updating a software package for the simulation of diffraction patterns and the computation of the parameters of the twinning and self-accommodation of martensite crystals

An updated software package for the simulation of point diffraction pictures and the computation of several crystallographic characteristics of martensite crystals in alloys with the shape-memory effect is presented. Optimization was carried out for the procedure of the analysis of the orientation relationships between the lattices of austenite and martensite from the viewpoint of the possibility of the formation of self-accommodation complexes.     

Adhesion at the interfaces between BCC metals and α-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Ab initio calculations of the atomic and electronic structures of Me(111)/α-Al₂O₃(0001) interfaces (Me = V, Cr, Nb, Mo, Ta, W) in the framework of density functional theory are reported. The energies of separation of metal films from oxide surfaces have been calculated. The structural and electronic factors responsible for the strong adhesion of bcc metal films on the oxygen termination of the surface of aluminum oxide have been analyzed.     

Edge-minimization of non-deterministic finite automata

In this paper we consider non-deterministic finite Rabin-Scott’s automata. We use a special structure to describe all the possible edges of non-deterministic finite automaton defining the given regular language. Such structure can be used for solving various problems of finite automata theory. One of these problems is edge-minimization of non-deterministic automata. As we have not touched this problem before, we obtain here two versions of the algorithm for solving this problem to continue previous series of articles.     

The Influence of Phase Composition and Phase Distribution on Crack Formation and Fracture Mechanisms of Cr–Ni Steels Produced by the Method of 3D Electron-Beam Printing

Russian Physics Journal - The features of crack formation near the fracture region and the fracture micromechanism are investigated during uniaxial tension of specimens of Ni–Cr stainless...     

Transport Models for Plasma Heating with Second Harmonic of Electron-Cyclotron Frequency

Physics of Atomic Nuclei - The optical thickness of plasma is often insufficient to absorb completely electromagnetic waves when heated at the second harmonic of the electron-cyclotron frequency....