Deformation of a composite plate on an elastic foundation by local loads

Bending of an elastic annular composite plate with a light filler lying on an elastic foundation is considered. The plate is subjected to local loads. To describe the kinematics of the package, asymmetric across its thickness, the hypotheses of broken normal is accepted. The reaction of foundation is described based on the Winkler model. A system of equilibrium equations is constructed, and its exact solution in displacements is found. Numerical solutions for a metal-polymer sandwich plate are presented. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 1, pp. 109–120, January–February, 2007.     

Synthesis and Photophysical Characterizations of Thermal -Stable Naphthalene Benzimidazoles

Microwave-assisted synthesis, photophysical and electrochemical properties of thermal-stable naphthalene benzimidazoles and naphthalimides are studied in this paper. Microwave-assisted synthesis of naphthalene benzimidazoles provide higher yields than the conventional thermal synthesis. Comparative photophysical properties of naphthalene benzimidazoles and naphthalimides are revealed that conjugation of electron-donating group onto naphthalimide moiety increases fluorescence quantum yields. Fluorophore-solvent interactions are also investigated using Lippert-Mataga equation for naphthalimides and naphthalene benzimidazoles. Thermal stabilities of naphthalene benzimidazoles are better than naphthalimides due to increased aromaticity. The experimental E_LUMO levels of naphthalene benzimidazoles are found to be between 3.15 and 3.28 eV. Therefore, naphthalene benzimidazole derivatives consisting of anchoring groups are promising materials in organic dye sensitized solar cells.     

Extracellular β-class carbonic anhydrase of the alkaliphilic cyanobacterium Microcoleus chthonoplastes

The gene for β-class carbonic anhydrase (CA), which was designated as cahB1, was cloned from the genomic library of the alkaliphilic cyanobacterium Microcoleus chthonoplastes. The product of the cahB1 gene was expressed in Escherichia coli. The protein revealed high specific activity of CA, which was inhibited with ethoxyzolamide. The maximum activity of the recombinant CA was detected at alkaline pH (～9.0) and its minimum - at neutral pH (～7.0). Western blotting analysis with the antibodies raised against the recombinant CahB1 protein revealed its localization in cell envelopes of M. chthonoplastes. Immunocytochemical localization of the CahB1 in cells confirmed its extracellular location. The newly characterized CahB1 of Microcoleus was similar in amino acid and nucleotide sequences to well known β-CAs of Synechococcus sp. PCC 7942 (IcfA) and Synechocystis sp. PCC 6803 (CcaA), although those CAs were attributed to the carboxysomal shells of cyanobacteria. Previously we have reported β-class CA which was associated with PS II of alkaliphilic cyanobacteria. Here we first report extracellular localization of β-class CA and provide a scheme for its possible involvement in the maintenance of a balance between external sources of inorganic carbon and photosynthesis in extreme environments of soda lakes.     

On 4-transitivity in the Moufang plane

The purpose of this paper is to give a short proof of 4-transitivity in Moufang planes. This proof originated in the observation of the two first name authors that the standard Moufang identities, together with the identity (1) x^–1(y(xz)) = (x^–1(yx)z, which is asserted in [2, p. 103] to hold in Cayley-Dickson division algebras, can be applied to give a particularly simple algebraic proof of the fact that the collineation group of a Moufang plane is transitive on four-points. Unfortunately, as pointed out by H. Karzel and demonstrated here in Proposition 1, (1) does not hold in Cayley-Dickson algebras. Nevertheless, the algebraic proof of transitivity remains valid after slight modifications and is given here as Theorem 1.The authors wish to thank Professor Karzel for pointing out the error in [2] and for his suggestions in preparing the final version of this paper.Dedicated to Professor H. Karzel on the occasion of his 60th birthday.     

Solid-phase extraction of bismuth, lead and nickel from seawater using silica gel modified with 3-aminopropyltriethoxysilane filled in a syringe prior to their determination by graphite furnace atomic absorption spectrometry

In this study, the use of syringe filled with sorbent for the separation and enrichment of bismuth, lead and nickel prior to their analysis by graphite furnace atomic absorption spectrometry was described to substitute for batch and column techniques. The method proposed in this paper was compared with column technique with respect to easiness, fastness, simplicity, recovery and risk of contamination. The syringe was filled with 0.5 g of sorbent and in order to retain the analyte elements, 5 ml of sample solution (pH≥5) was drawn into the syringe to 15 s and discharged again in 15 s. Then, 2.0 M of HCl, as the eluent, was drawn into the syringe and ejected back to desorb the analyte elements. At optimum conditions, the recoveries of Bi, Pb and Ni were 95-99% with relative standard deviations (RSDs) of around ±2%. Detection limit (δ) was 0.5 μg l⁻¹ for Bi, Pb and Ni, respectively. The elements could be concentrated by drawing and discharging several portions of sample successively but eluting only one time. Bi, Pb and Ni added to a seawater sample were quantitatively recovered (>95%) with low RSD values of around ±2-3%. The risk of contamination is less than that with the column technique. In addition, it is much faster, simpler, easier, more practical and handy compared with column technique.     

Enhanced optical oxygen sensing using a newly synthesized ruthenium complex together with oxygen carriers

In this article, an emission based, simple and fast method is proposed for the determination of gaseous oxygen. A newly synthesized fluorophore, dichloro-{2,6-bis[1-(4-dimethylamino-phenylimino) ethyl]pyridine}ruthenium(II) has been used for oxygen sensing together with oxygen carrier perfluorochemicals (PFCs) in silicon matrix. It should be noted that the solubility of oxygen in fluorocarbons is about three to ten times large as that observed in the parent hydrocarbons or in water, respectively. Employed PFCs are chemically and biochemically inert, have high dissolution capacities for oxygen, and, once doped into sensing film, considerably enhance the response of sensing agent.     

Mechanical,electronic and optical properties of SeZnO3: a GGA+U study

ABSTRACT

Based on first principles computations, the structural, mechanical, electronic band structure, and optical properties of SeZnO₃ compound have been predicted. The dependence of selected observables of SeZnO₃ compound on the effective U (the Hubbard on-site Coulomb repulsion) parameter has been investigated in detail. The elastic constant, Young’s modulus, bulk modulus, shear modulus, Poisson ratio, anisotropic factor, acoustic velocity, and Debye temperature have been computed. The calculated electronic band structure and density of states indicate that SeZnO₃ is a semiconductor material and has indirect band gap. The computations of the optical spectra, as a function of the incident photon radiation in 0–35?eV energy range has also been performed and the interband transitions are examined. The results indicate that Hubbard parameter plays a crucial role in explaining mechanical, electronic, and optical properties of SeZnO₃.     

Red and near infra-red signaling: Hypothesis and perspectives

The review covers some of the proposed cellular photoreceptors responsible for the effect of red and near infra-red (NIR) light on mammalian cells, including cytochrome-c-oxidase, photoactive porphyrins, flavoproteins, and molecular oxygen. We do not discuss the clinical studies but consider animal models, especially fibroblasts. Several key hypotheses such as mitochondria signaling and free-radical conception of the effects of red light and NIR light based on the changes in redox properties of photoreceptor molecules as well as membrane conception are examined. Special attention is paid to common mechanisms of light signaling in mammalian and plant organisms.