SEM‐EDX and microftir studies on evaluation of protection capacity of some thin phosphate layers

This article presents the SEM‐EDX and microFTIR study and the corrosion behavior of new five types of phosphated coatings obtained by coprecipitation in acid aqueous medium of some metal cations, pursuing the influence of the addition of other cations and a moderator of precipitation, on the uniformity and compactness of the layers and on the morphology of dendritic structure of Zn(II) and Fe(II) phosphates. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Unconventional method used in synthesis of polyphosphoesters

Polyphosphonates, polyphosphates, polyarylazophosphonates and polyarylazophosphates were synthesized by a new alternative to the classical phase transfer catalysis, respectively, the modified inverse phase transfer catalysis (IPTC) polycondensation of various phenylphosphonic (phosphoric) dichlorides (phenylphosphonic dichloride, phenylphosphoric dichloride, p-chlorophenylphosphoric dichloride) with bisphenols: bisphenol A, tetrabromobisphenol A, bis-(4-hydroxyphenyl)methane (bisphenol F), 4,4′-dihydroxyazobenzene. The polymers were characterized by infrared spectroscopy and magnetic resonance (¹H-NMR, ³¹P-NMR, ¹³C-NMR) spectroscopy. Yields in the range of 63.5–85% and molecular weights (M _w) of ~2,000–8,200 g mol^?1 were obtained. Polyphosphonates were stable up 210–270 °C and polyphosphates up 190–220 °C in air atmosphere. For a correct estimation of the thermal behavior of similar compounds, a kinetic analysis using a modified version of Non Parametric Kinetic method for representative polyphosphonate and polyphosphate was realized. The studies made on the hydrolytic degradation of the synthesized polyphosphates show that the most stable polymer under alkali-catalyzed degradation is the polyphosphate obtained by IPTC of phenylphosphoric dichloride and bisphenol A.     

An empirical evaluation of P system testing techniques

This paper presents the existing techniques for P system testing and performs an empirical evaluation of their fault-detection efficiency. The comparison is performed using mutation testing and, based on the results obtained, some improved testing methodologies are proposed.     

Onset of convection in a horizontal porous layer driven by catalytic surface reaction on the lower wall

The onset of convection in a horizontal layer filled with a fluid-saturated porous medium is studied in this paper. On the lower wall there is an exothermic surface reaction, described by the Arrhenius kinetics, while the upper wall is subjected to uniform temperature and concentration. The problem, cast in dimensionless form, is governed by three dimensionless parameters pertaining to the exothermic reaction and the Lewis number. Once the basic state is solved, a linearized stability analysis is then performed and the resulting eigenvalue problem is solved using a conventional shooting method. One determines numerically the critical Rayleigh and wave numbers at the onset of convection, for various values of the problem parameters.     

Organic–inorganic hybrids obtained by in situ polymerization of aniline in silica/phosphonate matrix

A method for preparing organic–inorganic hybrids containing organophosphorus compounds, silica, and polyaniline (PANI) was developed using sol–gel technique. This method allows the in situ synthesis of organic–inorganic hybrids by reacting tetraethoxysilane (TEOS), aniline, initiator, organophosphorus compound in formic acid. The formic acid has multiple functions: as solvent and acidic media for polymerization of aniline and reagent for sol–gel process. The use of an organophosphorus compound as coupling agent and the introduction of a conductive polymer in silica matrix was investigated.     

The power of communication: P systems with symport/antiport

In the attempt to have a framework where the computation is done by communication only, we consider the biological phenomenon of trans-membrane transport of couples of chemicals (one say symport when two chemicals pass together through a membrane, in the same direction, and antiport when two chemicals pass simultaneously through a membrane, in opposite directions). Surprisingly enough, membrane systems without changing (evolving) the used objects and with the communication based on rules of this type are computationally complete, and this result is achieved even for pairs of communicated objects (as encountered in biology). Five membranes are used; the number of membranes is reduced to two if more than two chemicals may collaborate when passing through membranes. Andrei Paun: He graduated the Faculty of Mathematics of Bucharest University in 1998, received his M.Sc. degree from The University of Western Ontario in 1999, and since then he is a PhD student in the Computer Science Department of University of Western Ontario, London, Canada (under the guidance of prof. Sheng Yu). The topic of his thesis is Molecular Computing (especially, DNA and Membrane Computing), but his research interests also include neural networks, implementing automata, combinatorics on words. Gheorghe Paun: (the proud father of two sons, including the first author of this paper) He is a member of the Romanian Academy, working as a senior researcher in the Institute of Mathematics of the Romanian Academy, Bucharest, and as a Ramon y Cajal researcher in Rovira i Virgili University of Tarragona, Spain. He is one of the most active authors in (the theory of) DNA Computing, (co)author of many papers in this area, (co)author and (co)editor of several books. In 1998 he has initiated the area of Membrane Computing. Other research interests: regulated rewriting, grammar systems, contextual grammars, combinatorics on words, computational linguistics.     

Chemical transformation of PVC by phase transfer catalysis

Summary Suspension type PVC was reacted with sodium phenoxide in presence of different quaternary ammonium halides in THF or THF/water mixtures. The competition elimination vs. substitution of chlorine atoms depends on the homogeneity of the system, i.e. the more homogeneous the reaction mixture the less substituted the polymer.Dedicated to the 60th anniversary of Prof. Otto Vogl     

Studies on the electronic transport properties of some organic semiconductors in thin films

The investigated compounds are some derivatives of orthotolidin-N,N-bis (4-aminobenzene-2-sulphonic) acid. The temperature dependences of the electrical conductivity and Seebeck coefficient are studied on the thin films deposited from dimethylformamide solution onto glass substrates. It is known that the investigated compounds have typical semiconducting properties. The values of some important parameters of the films (thermal activation energy of electrical conduction, concentrations and mobilities of charge carriers) have been determined. The correlations between some of these parameters and molecular structure of the respective compounds are discussed.