The First Raid of Mongols on Russia

In the early 13 th century when Mongols invaded Middle and Near East and a part of Europe, its branch intruded into Russia for the first time. According to the generally accepted opinion the invasion occurred in 1223. However, some historians recently raise question to this point and insist that the incident must have occurred a year before, in 1222. The aim of this article is to examine, whether such a view is possible or not on the ground of historical sources.13 世紀モンゴル軍は中近東、ヨーロッパの一部を攻略したが、資料その他に基づく通説に従 えば、1223 年5 月乃至6 月、その一支隊が初めてロシアに侵冦し、チュルク系遊牧民族であるポロベツ族 と南ロシアのロシアの諸公との連合軍を、カルカ河畔の戦いにおいて完膚無き迄に撃破したとある。それ が5 月か6 月かは依然議論の存するところであるが、年については一般に認められてきた。しかし最近モ ンゴル軍がカフカス山脈を越えたとされる時期と関連して、侵冦を1222 年とする説が現れた。資料によ りその可能性があるか否かについて論じるのが小論の趣旨である

Mass Transfer and Chemical Reaction in Liquid-Liquid Agitation Systems

The objectives of the agitation of liquid-liquid mass transfer systems with or without chemical reaction may be set forth as follows in general : (1) increase in the inter facial area by promoting dispersion, (2) diminution of the mass transfer resistance in the diffusion film outside the liquid droplets, and (3) diminution of the mass transfer resistance in the inner part of liquid droplets or mixing of dispersed phase. The diameter of liquid droplets was measured to estimate the interfacial area. At the same time, the rate of reaction or the rate of mass transfer was observed for various kinds of liquid-liquid mass transfer systems which were classified according to reaction or no reaction and according to degree of difference in density. Comparison was then made between the increase in the estimated inter facial area and the increase in the rate of reaction caused by the increase in agitator speed. On the other hand, mathematical analysis were performed on these processes to clarify the effect of agitation for various kinds of fundamental and important liquid-liquid agitation systems. Thus the authors found that the effect of agitation upon the liquid-liquid mass transfer was mainly to increase the interfacial area, that the decrease of the mass transfer resistance in the diffusion film outside droplets was slight, and that the mixing of the inner part of the droplets was rather decreased by the increase in agitator speed. Part I Effect of Agitation for the Diminution of Mass Transfer Resistance in Continuous Phase

Rate of Solution of Solid Particles Followed by Chemical Reaction in Agitation Vessel

In this paper, the authors deal with the dissolution of acid anhydride in water followed by the hydrolysis reaction. Classification may be made of the types of reaction taking place depending upon the relative rates of diffusion and hydrolysis of the acid anhydride. (1) Diffusion resistance is controlling and the overall rate of reaction depends only on the rate of solution. In this case the higher the agitator speed, the larger the rate of solution. (2) Diffusion resistance and the chemical resistance to hydrolysis are comparable in magnitude. In this case the overall rate of reaction depends not only on the agitator speed, but also on the rate of hydrolysis. (3) Chemical resistance to hydrolysis is controlling and the overall rate of reaction is independent of the agitator speed. The authors derived the generalized rate equation and demonstrated the three types of reaction by the hydrolysis reaction of phthalic acid anhydride and benzoic acid anhydride suspended in water under agitation. The authors propose the idea of “the degree of transitional saturation” and “the agitation coefficient for heterogeneous reaction”. The latter is useful for the determination of the available agitation intensity for heterogeneous liquid phase reactions

Chemical Absorption of Gas into Liquid Film on Rotating Drum

With a rotating drum type gas-liquid contactor of known area, the effects of gas rate and the rotational speed of the drum on the thickness of liquid film were observed and the rate of gas absorption accompanied by a chemical reaction in the liquid phase was measured using either one of the catalysts, mannitol, Cu⁺⁺ and Co⁺⁺⁺. The analytical solution was presented for the simultaneous unsteady state absorption and (m+l)-st order reaction (m-th order with reactant A and 1st order with reactant B respectively). Experimental results were compared with theories and the five states of rate controlling were verified which had formerly been derived analytically. The five states correspond to the case where mass transfer are controlled by the resistances of ; (1) chemical reaction in the liquid, (2) both chemical reaction and diffusion in the liquid, (3) diffusion of the dissolved gas in the liquid film, (4) both diffusion and chemical reaction in the liquid film and (5) diffusion of the reactant from the liquid bulk. The rate constant of the accompanied reaction was also determined

Rate of Solution of Solid Particles in Agitated Liquids

Hixson and Baum have proposed generalized dimensionless equations for the rate of solution of solid particles in agitated liquids. The authors developed an improved equation and conducted additional experiments on the rates of solution of zinc and magnesium metals in dilute hydrochloric acid containing potassium nitrate. Experiments were also made on the rate of solution of benzoic acid in NaOH solutions and of sugar in water. The newly developed equation is as follows: (KD/Df)=α′(D²nρₗ/µ)ᵖ(µ/ρₗFf)q(δ³g/ν²)r(ρₛ-ρₗ/ρₗ)ᵗ The constant α′ and exponents p, q and s are presented in this paper. The authors arrived at the following conclusions: (1) At a definite critical Reynolds number, Rf (or agitator speed, Nf), solid particles are fluidized in an agitated liquid. (2) At this critical Reynolds number (or agitator speed), the rate of increase in solution velocity is abruptly decreased with further increase in agitator speed. (3) In the fluidized state where N>Nf, an increase in density difference between the solid and liquid phases combined with the effect of agitation velocity greatly reduces the diffusional resistance. (4) In the range of Reynolds numbers less than Rf, or agitator speed less than Nf, the apparent rate of solution of solid particles increases with the 1.0 to 1.4 power of Rₑ depending upon the conditions of agitation. This experimental effect may reach a value of even 2.9 for small particles. (5) From these experiments it is expected that the effect of agitation in liquid-liquid systems is mainly to increase the reaction surface area, and that the effect of agitation in diminishing diffusion resistance is rather small. The effect of agitation in solid-liquid systems in the range of fluidization is mainly to diminish diffusional resistance

Mass Transfer in Agitated Liquid-Solid Systems

The authors performed experiments on the solution of solid particles in agitated liquids in a series of geometrically similar agitators. A great variety of solid particles, including several kinds of spherical crystals, whose particle size, shape and density varied over a wide range were used as the solid samples. Pure water, dilute hydrogen chloride and aqueous solutions of gelatine, polyvinyl alcohol, sucrose and glycerine of various concentrations were used as the liquids. Several methods for determining the rate of solution of solid particles were considered, and the analysis of the data was performed in terms of the mass transfer coefficient. As for the experimental results on the agitation process, it was found that the physical properties of the solid particles, i.e., the difference in density between the liquid and the solid, the size and shape of the particles, as well as the viscosity and the density of the liquid were important factors controlling the rate of mass transfer. Between the agitator speeds of Nf and Nₐ all the data were correlated by the following dimensionless equations. For solid particles with an unknown surface shape factor, and for solid particles with a known surface shape factor, where These equations represent the general correlation of the variables involved in determining the magnitude of the rate of mass transfer in agitated liquid-solid systems, and are used to estimate the mass transfer rate for any liquid-solid combination in a series of geometrically similar vessels and impellers

Kinetics of Heterogeneous Liquid Phase Reaction : Simultaneous Mass Transfer and Chemical Reaction

The solution of the over-all rate of reaction for a steady state mass transfer accompanied by a (l+ｫ)-th order irreversible reaction was derived by applying an approximate concentration distribution model for the heterogeneous liquid phase reaction which might proceed in a diffusion film and homogeneous mixed bulk liquid of finite volume. The numerically calculated diagrams showing the functional relation between the over-all rate of reaction and the reaction conditions such as the resistances to diffusion and chemical reaction, liquid volume and the inter facial contact area, etc. were presented. The authors made clear the conditions for the five states of over-all reaction rate which were different in comparative magnitude in the resistances to diffusion and chemical reaction, and interpreted the various types of rate controlling step by comparing the reaction conditions and the concentration distribution of reactants both in diffusion film and bulk liquid

Photoinduced hydrogen release from hydrogen boride sheets

Hydrogen boride nanosheets (HB sheets) are facilely synthesized via ion-exchange treatment on magnesium diboride (MgB2) in an acetonitrile solution. Optical absorption and fluorescence spectra of HB sheets indicate that their bandgap energy is 2.8 eV. According to first-principles calculations, optical absorption seen at 2.8 eV is assigned to the electron transition between the sigma-bonding states of B and H orbitals. In addition, density functional theory (DFT) calculations suggest the other allowed transition from the s-bonding state of B and H orbitals to the antibonding state with the gap of 3.8 eV. Significant gaseous H-2 release is found to occur only under photoirradiation, which causes the electron transition from the s-bonding state to the antibonding state even under mild ambient conditions. The amount of H-2 released from the irradiated HB sheets is estimated to be 8 wt%, indicating that the sheets have a high H-2-storage capacity compared with previously reported metal H-2-storage materials

軸対称ノズル内の遷音速流れ(そのII)

In this paper, the transonic flow in the throat region of a axially-symmetric nozzle, which is identical with the flow treated in the previous paper, is studied. It is shown that an inner solution to the fourthorder approximation can be derived systematically by the derivation of an outer solution to the ninth-order approximation and by using the methods of matched asymptotic expansions. When comparing the inner solution obtained in this paper with Hall\u27s solution, though his solution corresponds to the present inner solution to the third-order approximation, and in reviewing his work, it was discovered that his axisymmetric solution contained errors in the third-order solution and the ratio of the mass flow. Since his work is widely used in the field, the corrected third-order axisymmetric solution is given. Numerical examples are also given for air (the ratio of specific heats γ=1.4) flowing through nozzles with some values of small parameter E