On a class of quasilinear eigenvalue problems on unbounded domains

We prove several existence and non-existence results for a quasilinear eigenvalue problem with nonlinear boundary condition on unbounded domain. Our paper extends previous results obtained in Chabrowski [1] and Pflüger [4].     

Towards a general theory of formallyp-adic fields

The work is devoted to develop a general framework for the theory of formallyp-adic fields and to prove in this context some analogues of certain results of the theory of formallyp-adic fields in the sense of Kochen-Roquette. The general theory is illustrated by examples.     

Relationship between vegetable metal and soil-extractable metal contents by the BCR sequential extraction procedure: chemometrical interpretation of the data

The contents of heavy metals in soil and vegetable samples collected from an urban garden in Kayseri, Turkey, were investigated. Both wet- and dry-ashing methods were used for dissolving vegetable samples. A sequential extraction procedure proposed by the Commission of the European Communities, Community Bureau of Reference (now superseded by the Standards, Measurement and Testing Programme, SM&T) was applied to the soil samples to extract the metals which are present in exchangeable and acid soluble (i.e. bound to carbonates), reducible (bound to Fe/Mn oxides), and oxidisable forms (bound to organic matter and sulphides) in the soil samples. Trace metals in the soil and vegetable samples were determined using flame atomic absorption spectrometry (FAAS). The total metal contents acquired by summing of metal levels in all the sequential extraction steps were compared with pseudo-total metal levels obtained with aqua regia for all the soil samples. The recovery values obtained by proportioning the results obtained by the BCR procedure to those of the pseudo-total digestion were found to be satisfactory. The limits of detection for the elements investigated were in the range of 0.04 to 0.59?µg?mL^?1 for all the extraction stages of the BCR procedure. Similarities among the variables were identified by correlation analysis, principal component analysis and hierarchical cluster analysis. The relationship between the vegetable metal and soil-extractable metal concentrations was examined in order to evaluate the bioavailability of metals.     

Graft Copolymerization of Acrylamide on Swollen poly (Ethylene Terephthalate) Fibers Using Cerium Ammonium Nitrate Initiator

Abstract

In this study the graft copolymerization of acrylamide (AAm) on swollen poly(ethylene terephthalate) (PET) fibers using cerium ammonium nitrate (CeAN) initiator was investigated. Five organic solvents, dimethylsulfoxide (DMSO), morpholine, acetic acid (HAc), n-butanol, and 1,2-dichloroethane (DCE), were used as swelling agents. DMSO was found to be the most suitable swelling agent. Solvent diffusion into the fibers was observed to increase with treatment time and temperature. The optimum graft yield was obtained when fibers were grafted after having been swollen in DMSO for a period of 1 hour at 140°C. Variation of graft yield with polymerization time and temperature, and monomer, initiator, and acid concentrations were investigated. Graft yields were observed to increase initially with polymerization time, then to level off, and were found to increase up to a certain monomer and Ce⁴⁺ concentration, then to decrease slightly. The effect of grafting on such fiber properties as diameter, viscosity, and moisture gain were also investigated.     

Thermal behavior of some polyurethanes reticulated by aminated maltose

Polymeric materials by polyaddition reaction between aminated maltose and methylene diisocyanate, in different molar ratio, were synthesized. Aminated maltose was obtained by functionalization at the reductive end with methylene dianiline, under soft reductive conditions. The addition reaction was certified by comparative FTIR and Raman spectra of reactants and obtained materials. The thermooxidative stability of these materials was established under non-isothermal conditions. The thermal stability decreases by increasing the isocyanate/aminated maltose molar ratio.     

About some transport phenomena in Pb1−xCdxS solid solutions

The paper presents some experimental data concerning Hall effect, Seebeck effect and electrical conductivity in bulk samples of Pb_1?xCd_xS solid solutions, in the temperature range 100–360 K. The results are discussed employing a theoretical model with isotropic isoenergetic surfaces and nonpuadratic dispersion law. At x = 0.06 the dominant mechanism for scattering the charge carriers involves optical phonons below Debye temperature and the state density effective mass is not essentially changed relative to pure lead sulphide.     

Dehydration kinetics of ulexite from thermogravimetric data

In the present study, the kinetic parameters of the thermal decomposition of ulexite were investigated by using TGA data. For the kinetic analysis, the Suzuki and Coats-Redfern methods were applied. It was determined that the process fits a first-order kinetic model, and the value of the activation energies and frequency factors decreased with decreasing particle size, which can be attributed to the increasing particle internal resistance to the escape of water as the grain size increases. The activation energy values were found to be 47.34–60.01 kJ mol^–1 for region I and 0.225–1.796 kJ mol^–1 for region II for the range of particle size fraction used. The frequency factors were calculated to be 9821.8–524.9 s^–1 for region I and 3.05×10^–44–2.807×10^–5 for region II for the same conditions.     

Production of enantiopure chiral aryl heteroaryl carbinols using whole‐cell Lactobacillus paracasei biotransformation

Abstract

Aryl and heteroaryl chiral carbinols are useful precursors in the synthesis of drugs. Lactobacillus paracasei BD87E6, which is obtained from a cereal based fermented beverage, was investigated as whole cell biocatalyst for the bioreduction of different ketones (including aromatic, hetero-aromatic and fused bicyclic ketone) into chiral carbinols, which can be used as a pharmaceutical intermediate. The study shows that bioreduction of aryl, heteroaryl and fused bicyclic ketone (1-5) to their corresponding chiral carbinols (1a-5a) in excellent enantioselectivity (>99%) with high yields. This study gave the first example for an enantiopure production of (S)-6-chlorochroman-4-ol (3a), which has many antioxidant activity, by a biological method. For asymmetric bioreduction of other prochiral ketones, these results open way to use of L. paracasei BD87E6 as biocatalysts. Also, the present process shows a hopeful and alternative green synthesis for the production of enantiopure carbinols in a mild, inexpensive and environmentally friendly process.