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Abstract
It is shown that every separable k'-space with a point-countable k-system has a countable k-system, which gives an affirmative answer to Y. Tanaka's Question posed in 1982.
Abstract
A number of generalized metric spaces have been defined or characterized in terms of g-functions. Symmetric g-functions are discussed by C. Good, D. Jennings and A. M. Mohamad. In this paper, some questions about symmetric g-functions are answered, particularly it is shown that every sym-wg-space is expandable.
Abstract
In this paper the relations among k-covers, cs *-covers and k-systems are discussed. The following question is partially answered: Does every separable k'-space with a point-countable k-system have a countable k-system?
Abstract
Preventing accidental explosions of flammable liquid/gas mixtures is very important. As far as flammability characteristics are concerned, we simulated the effects of inert liquid/gas, which was filled with reactors, vessels, or closed space, employed in the chemical process industries. The inert liquid/gas (H2O) weakened the oxygen concentration and reduced solvent vapor concentration in a 20-L-Apparatus. This study investigated the flammability characteristics of acetone/water solutions (100/0, 75/25, 50/50, and 25/75 vol.%) that are controlled at a temperature of 150°C and pressures of 101/202 kPa, respectively. The flammability parameters included flammability limits (LEL and UEL), maximum explosion pressure (P max), maximum explosion pressure rise ((dP dt −1)max), and vapor deflagration index (K g). The results of a series of experimental tests showed that UEL, P max, and K g all decreased with steam rising under the experimental conditions. The results can be applied to process safety design/operation for identifying whether the inert liquid/gas (H2O) content has any substantial effects in reducing the fire and explosion hazard of the solution of interest.
Abstract
The polymerization mechanisms of styrene and various derivatives by α-methylstyrene (AMS) and trans-β-methylstyrene (TBMS) were evaluated. Experiments were carried out for dimerization identification and thermal polymerization estimation by differential scanning calorimetry (DSC), thermal activity monitor (TAM) and Fourier transform infrared absorption spectrophotometer (FTIR). The results show that, under temperature ranges of 60–190 and 50–170°C, AMS and TBMS performed dimerization by benzene ring and ethylene double bond, respectively. AMS and TBMS would form unsaturated dimers, saturated dimers and trimers, etc., during the period of thermal polymerization. Through this study, one can estimate possible intermediates of the polymerization process for the monomer of interest in the petrochemical industry.
Abstract
Effects of nano-metal powders (aluminum and nickel) addition on the thermooxidative degradation of binder PEG in air atmosphere from 20 to 350°C were studied by TG/DTA and in-situ FTIR. TG/DTA results showed that the addition of nano-Al slowed down the degradation process of PEG in the early period but accelerated the process in the late period; the addition of nano-Ni made the PEG degradation process begin as soon as melted. The in-situ FTIR results showed that nano-Ni promoted the thermooxidative degradation of PEG in air, and made the degradation process of PEG complete much earlier.
Abstract
The analysis of tin in biological materials is rarely reported. In this study, instrumental neutron activation analysis was used to determine the tin together with some other trace elements in various organs of rats treated with trialkyltin-methacrylic copolymer. No appreciable accumulation of tin and variation of distribution of trace elements (Cr, Fe, Zn and Co) in various organs are found. The pathological changes in the liver sections cannot be observed either. This therefore indicates that the toxicity of trialkyltin-methacrylic copolymer is low, if any.
Abstract
In recent years chances of using rhenium-186 and rhenium-188 as radioactive isotopes in diagnostic and therapeutic applications are increased very much due to the characteristic radiochemical and chemical properties of these two radioisotopes. In particular, chemical similarities between99Tc and99mTc pair and186Re and188Re pair make it easier to correlate the two groups of compounds. Rhenium-188 is generated from the beta-decay of tungsten-188 which was produced by double neutron capture on enriched tungsten-186 oxide. It is of great interest to examine the impurities in the eluate by radiochemical neutron activation. For this purpose, the preconcentration of the impurities in samples were necessary, and it was achieved by adsorption on hydrated magnesium oxide.
Abstract
In this paper, we establish some new refinements for the celebrated Fejér’s and Hermite-Hadamard’s integral inequalities for convex functions.
