A study on interstitial heat transfer in consolidated and unconsolidated porous media

The Nusselt number expressions are presented for the interstitial heat transfer coefficients for both consolidated and unconsolidated porous media. A boundary layer consideration is made for unconsolidated porous media to derive a general Nusselt number correlation, which shows its square root dependence of the Reynolds number, and matches fairly well with existing experimental data and correlations. As for low density consolidated porous media, rigorous mathematical arguments based on the volume averaging theory are provided, so as to explain the reason why the Reynolds number exponent of the Nusselt number expression for the case of low density consolidated porous media is much greater than that of unconsolidated porous media. The resulting expressions are compared against available experimental data and empirical correlations, and found to be in good accord with them.     

扭矩转化器（T／C）内部叶片流道流场的二维PIV实验研究

本文利用二维ＰＩＶ技术研究了汽车无级调连装置中扭矩转化器内部叶片流道流场的复杂流动,实验结果表明泵和透平在不同转速下,静子叶片流道中的流场体现出不同的流动特征,文中还对实验误差进行了分析,提出了减少误差的措施,通过叶栅流动理论分析说明了本文结果的可靠性。     

New members of a family of layered bismuth compounds

Two new compounds, Bi₃Ti₂O₈F and PbBi₃Ti₃O₁₁F, were prepared and identified by X-ray diffraction analysis. These compounds are members of the family called layered bismuth compounds. Thermal properties of the new compounds were also studied. Besides the preparation and identification of these new compounds, a new method for preparing already known members, Bi₂NbO₅F and Bi₂TiO₄F₂, was reported. Moreover, the possibility of the existence of other new members belonging to the family was discussed.     

Is multiple production in proton-proton collisions similar to that ine + e − annihilation?

A model is constructed to simulate recent experimental finding that distributions of hadrons produced in proton-proton collisions are similar to those ine ⁺ e ^? annihilation if the leading proton effects are subtracted properly in the former process. It is found that the predicted multiplicity distribution in proton-proton collisions is too narrow compared to experimental data. As an alternative, we propose a simple quark model that produces correctly the observed multiplicity distribution including the approximate KNO scaling in proton-proton collisions.     

Alkylation of toluene with methanol over a zeolite disc synthesized through solid state reactions

Outstandingpara-xylene selectivity in the alkylation of toluene with methanol was observed for a new, disc-shaped ZSM-5 zeolite catalyst synthesized by solid state reactions.     

Steady laminar flow of a power-law fluid in a curved pipe of circular cross-section with varying curvature

The steady laminar flow of power-law fluid through pipes of circular cross-section, whose center-line curvature varies locally, is analyzed theoretically. The flows, in three kinds of pipes whose center-lines are specified by

as examples of once, twice, and periodically-curved pipes, respectively, are discussed in comparison with Newtonian flow. The analysis is valid for any other two-dimensionally curved pipes, when the center-line curvature is small.     

New salts of graphite,C12+HF2− & C24+SiF5− and the treshold for the oxidative intercalation of graphite

Third row transition metal hexafluorides (MF₆) for which the electron affinity exceeds 130 kcal/mole (M = Os, Ir, Pt) have been found to intercalate graphite with electron oxidation of the host lattice, whereas those with inferior electron affinities (M = W, Re) do not intercalate¹. This behavior can be rationalized on kinetic or thermodynamic grounds; arguing for the latter, a simple Born-Haber cycle may be used which suggests an electron affinity threshold of 120–130 kcal/mole for the MF₆ intercalation reaction. For the general case of intercalation reactions by metal fluorides (with or without added fluorine), wherein the graphite lattice is oxidized, the threshold is determined by the free energy of the half-reaction which produces the intercalating fluoro-anion. The lattice energy of the graphite salt must also be taken into account when comparing free energy thresholds for large (e.g., MF₆) and small (e.g. HF₂^?) intercalating species.We have evaluated the free energy of formation of a number of fluoro-anions from the heats of formation and lattice energies of salts which contain them. These studies indicate a threshold free energy of ca. 110 kcal/mole for graphite intercalation. Two ‘borderline’ second stage compounds, C₂₄⁺SiF₅^? and C₁₂⁺HF₂^?, have been synthesized.     

Thermodynamics of Structural Changes in Liquid Ge–Te Alloys Around the Eutectic Composition: Specific Heat Measurements and Thermodynamic Stability

Summary. We have obtained the specific heat, C_p, of liquid Ge–Te alloys around the eutectic composition (15 at.% Ge) and alloys up to 50 at.% Ge by combining the data obtained by modulation and adiabatic calorimetries. The results cover a wide temperature range from deeply undercooled state to 800°C. A very pronounced peak of C_p was observed for Te and alloys up to 20 at.% Ge. The peak position of C_p takes a maximum around the eutectic composition where the peak width becomes narrowest. Using a new thermodynamic relation, we clarify a correlation between the thermodynamic stability and structural changes in the liquid Ge–Te system.     

Artificial hydrolase using modified dimethyl-β-cyclodextrin

The first successful method for modification of dimethyl--cyclodextrin (-DMCD) was demonstrated by the synthesis of a new artificial hydrolase (2) and the enzymatic activities of 2 were investigated.2 caused an 1100-fold increase in the rate of hydrolysis ofp-nitrophenyl acetate at pH 7.2, whereas unmodified-DMCD depressed the reaction. The kinetic pK _a of2 was 7.2, and theK _m of2 was independent of pH values.2 hadpara-selectivity for the hydrolysis of nitrophenyl acetate isomers.     

Reaction between ethanol and silicon–hydrogen of poly(p-vinylphenyldimethylsilane)

A kinetic approach to the polymer reaction, with KOH as catalyst, between ethanol and poly(p-vinylphenyldimethylsilane) containing silicon–hydrogen as a functional group on the side chain was carried out. The rate equation was obtained by measuring the initial rate of the model reaction as v = k[KOH] [SiH] [EtOH] in benzene and v = k[KOH] [SiH] in methyl ethyl ketone. It was observed that the rate of reaction was affected by the polarity of the solvents. In the polymer reaction the rate constant decreased markedly with increasing ethanol concentration. A change of viscosity of the polymer in various solvents was observed to have a good correlation with the decrease in reaction rate in corresponding solvents. In mixed solvents, consisting of both good and poor solvents for the polymers, the reaction rate depended upon two factors, the entanglement of the polymer chain and the polarity of the solvents. The equivalent globular model of the polymer chain is suggested for study of the polymer reaction. A schematic local-distribution curve of the reaction species is proposed.