Transition metal complexes show beautiful colors in solid and in solutions. Their colors are changed reversibly by the changes of surrounding chemical or physical conditions such as solvent, temperature, pressure, electric power, or light, which we call chromotropism. In this review, at first, color origins of these complexes are explained, i. e., d-d transition, CT transition (metal to ligand and ligand to metal), inter-valence transition (in mixed valence compounds), etc. Secondly, some examples of chromotropisms are explained:(1) In solution;(a) CoC1₂ which shows solvatochromism, thermochromism, and piezochromism, (b) Mn (II, III)-complexon type complexes which show a typical electrochromism, (c) Cu (II) and Ni (II) mixed ligand complexes showing solvatochromism and thermochromism as the color indicator of solvent polarity.(2) At solid state;(a) Cu (II) and Ni (II) diamine complexes as interesting examples of thermochromism, (b) Fe (II) spin-crossover complexes which show thermochromic behavior and have photochromic switching functions at low temperature.

View full abstract

In this paper, we present experimental results on the behavior of underground fires loaded with low fuel density and discuss the prevention of flame propagation along timbered roadways. A series of fullscale fire experiment has been carried out, using a 400 meter long test gallery and timber linings as a fuel installed in the gallery. The performances of fire resistant zones were tested under the condition that the quantity of combustible materials was reduced up to critical values, necessary to suppress flame propagation along timber lining. As a result, it was found that the quantity of fuel largely influenced the properties of underground fires, i. e., flame spread rate, fire zone length and fire temperature. A critical combustion condition was appeared in which any flames did not propagate on the leeward of ignition source, if the quantity of fuel became relatively low such as less than 7.5 or 10kg per unit gallery volume (m³). The effect of ventilation air velocity on the critical fuel quantity was also clarified in the experiment. Thus, we could provide fundamentals to make clear requirements for fire resistant zones in underground roadways.

View full abstract

In order to investigate the effect of moisture on the effective thermal conductivity of porous rocks, eighteen rocks conditioned at dried, moist and water-saturated conditions were used for measuring the thermal conductivity by a transient hot wire comparison method developed by Deguchi, et.
The moist rocks were conditioned in the atmosphere of 20°C and 60% relative humidity. This condition was adopted on the base of X-ray analysis of montmorillonite to simulate the natural dry condition, at which montmorillonite contained two layers of water in its interlayers.
The results showed that the effective thermal conductivities of all rocks increased with increase of water in the pore. The conductivity of zeolite rocks is most affected by the degree of saturation of water. The thermal conductivity of water-saturated rocks is 1.2 to 2.5 times higher than that of the dry rocks.

View full abstract

The time-dependent behaviour of rock has an important significance on the long term stability of underground structures. Much effort has been paid to clarify this behaviour. But, most studies are conducted only in uniaxial condition, and very little knowledge is available concerning the behaviour under triaxial condition. In this study, at first, compression tests were carried out in uniaxial and triaxial compression under the four loading-rates. Creep tests were also carried out where special care was taken to obtain complete creep curves.
In compression tests, it is found that square of peak stress is well correlated with confining pressure. Strength increases with loading-rate and can be approximated by (σ_1max-σσ₃)∝C^1/(n+1). This tendency is similar to that in uniaxial compression. Also, it is found that time-dependency decreases with confining pressure.
In creep tests, the following results are obtained in triaxial compression. Creep strain rate decreases following the logarithmic law in primary creep and increases in inverse proportion to residual life (T) in tertiary creep. Life is inversely proportional to minimum creep strain rate. The above mentioned tendencies are quite similar to those in uniaxial compression. With increase of confining pressure, however, creep strain to failure and life at the same stress level increase considerably. Also, life varies largely with little change of stress level.

View full abstract

An evaporating and treating system of liquid wastes produced from many fields of industries by using a jet burner was proposed. In order to obtain the data showing the capacity of heat exchange of this system, the fundamental experiments were carried out. This treating system were consisted of a jet burner operated by gasoline and compressed air, an atomizer installed at the nozzle exit, a treating tank in which the liquid particles and the jet were injected and a duct for the exhaust gas. Water was used for representing the liquid wastes. The liquid was atomized at first by atomizer and the atomized particles were evaporated with flowing in the jet stream.
The ratio of weight of water treated and the gasoline fed into jet burner, temperature of exhausted gas and the diameter of atomizer were varied in the experiments. The volume of the tank needed to evaporate the liquids was obtained from the experiments. The coefficient of heat capacity calculated from the obtained data was 1-8× 10³ (kcal/m³h°C)

View full abstract

As a fundamental study of a new zinc smelting process using liquid copper for a smelting medium recover zinc in a liquid Cu-Zn base alloy, distribution ratios of zinc, L^S_Z/^C_N, between liquid Cu-Zn-Fe (ironsaturation) alloys and CaO-Si0₂-FeO_X slags were determined at 1, 473 and 1, 523 K, under varying content in the alloy from about 0.5 to about 30 mass% and varying Q (Q=%CaO/(%CaO+%SiO₂)) of the slag from 0 to 1.
L^S_Z/^C_N for the alloy with alow zinc content about 0.5% is alrnost constant against% FeO_x in the slag and decreases with increasing Q. The activity coefficient of ZnO in the slag, (γz_no>), which was calculated from the measured L^S_Z/^C_N, increases with increasing Q and is about 3 at Q=0.42.
L^S_Z/^C_N for the alloy with a high zinc content more than 1% increases monotonously with the zinc content.The calculated (γz_no) is almost constant against the zinc content. This suggests that ZnO in the CaOSiO₂-FeO_x-ZnO slag approximately obeys a Henry's law up to the relatively high concentration of ZnO.(γZnO) inCreases with increasing Q and is about 5 atQ=1.
Based on the obtained L^S_Z/^C_N, the fractional distribution of zinc between the alloy, slag and gas phases was calculated for the newly proposed process to recover zinc by means of the smelting medium of liquid copper.

View full abstract

Silicon carbide is an important industrial material as used for high-temperature ceramics. In the present study silicon carbide powders were synthesized at different temperature (1, 250-1, 400°C) by reaction of a mixed power of shirasu and coked rice hulls or coked bamboos. The results are summarized as follows;
(1) Two kinds of shirasu are used as the source of Si0₂, one mainly consists of volcanic glass and the other includes volcanic glass and crystalline materials, such as feldspar and quartz. Coked rice hulls contain large amounts of unburnt component, but coked bamboos include a very small amount of one.
(2) Pure powders of silicon carbide are synthesized from shirasu and coked bamboos under relatively low temperature as compared with synthetic conditions of β- silicon carbide on the market.
(3) The structural and quantitative analyses of the synthesized silicon carbide were carried out using the X-ray powder diffraction refinement method on the basis of the cubic and hexagonal close packed models. The profile calculated on the basis of Paterson model shows that the peak of (102) reflection moves toward the lower angle with increasing the amount of stacking faults, however, in the case of Wilson model the peak position of (102) reflection does not move any more with increasing the stacking faults. The content of the stacking faults in the present synthesized silicon carbide is very small as compared with that of silicon carbide on the sail.

View full abstract

In the iron-reduction distillation process for zinc extraction, iron oxide is preferentially reduced to metallic iron at the first reduction stage, then zinc oxide is reduced to zinc vapor by the reduced metallic iron at the second reduction stage. Therefore, the sample experiences such as reaction path, heat and atmosphere during the first reduction stage might influence the reduction rate of zinc oxide with metallic iron. From this point of view, kinetic experiments were carried out to clarify the effect of preheating on the reduction rate of zinc oxide with metallic iron, and the experimental data were then analyzed by applying shrinking unreacted-core model. The results indicated that preheating resulted in acceleration of the reduction rate. This is significantly advantageous in the process

View full abstract

Electrodialyses of a model solution, oxalic acid-iron (II) oxalate mixture, and a real leaching solution were investigated focusing on the removal of iron from the solution for effective recovery of oxalic acid from oxalic acid leaching of diatomaceous earth. Two types of dialyzers, having 5 compartments, were used: with a desalting compartment (the center one) divided with both of a cation-exchange membrane and an anion-exchange membrane (A-C type), and with the same compartment arrays divided with only cation-exchange membranes (C-C type). The fluxes of various ionic species through the membranes were examined in the both types of dialyzers varying the concentrations of iron and oxalic acid. Iron was effectively removed as iron-dioxalate ion and as ferrous ion through the anion-exchange membrane and cation-exchange membrane, respectively. In the A-C type dialyzer, the removal rate through the former was considerably higher than that through the latter. The total removal rate of iron attained about 90% at 24hr; however, 30% of oxalic acid was lost through the anion-exchange membrane. In the C-C type dialyzer, oxalic acid loss was negligibly small, whereas the iron removal rate was lower than that in the A-C type dialyzer. A real leaching solution showed almost the same permea-, tion characteristics in dialysis as that of the model solution. No poisonous effect was observed for membranes during the dialysis. The dialysis characteristics described above were explained through the ionic species concentration-profiles calculated by the dissociation equilibria for oxalic acid and iron (II)-oxalate.

View full abstract