Stratified materials are defined as materials with nano-sized stratification that have been artificially controlled and designed. They are exemplified as a thin layer or stacked layers formed on surface of semiconductors. The present research is aiming at formation of controlled and designed stratification on surface of fine particles, leading to improvement of properties of fine particles which has been difficult to accomplish through the conventional particles engineering, and to development of novel properties created by the stratification.
Here, we describe the method of the development of the nano-size CdS catalyst with stratified structure that efficiently separates electron and hole during photolysis, especially, to produce hydrogen gas from hydrogen sulfide, H₂S. Furthermore, as an approach for the development of the practical use photocatalyst, ZnS-carbon nanotube complex was also made and examined. In a way, the stratified structure is considered to enable the production of a reaction system which simulates function in biological cells. Using this catalyst in the solution mixed with various materials such as, calcium hydroxide, seawater and H₂S, we succeeded in producing about 7.5l/h m² of hydrogen gas under the sunlight.

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In order to assess Chinese gold resources, more than 1600 deposits of the primary and placer types have been statistically analyzed. The deposits are classified into three independent groups and two summarized groups: primary-main (Pm), primary-accessory (Pa), placer (S), primary (P = Pm + Pa) and all data (T = P + S). Gold metal amount shows lognormal distribution in each of the groups. Grade of each of Groups Pm and Pa shows a single population, but that of Group S two populations. The correlation coefficients among grades, metal amounts and tonnages indicate that metal amounts of deposits largely depend on tonnage and scarcely on grades. The grade-cumulative tonnage relation of every group is approximated by the combination of two or three exponential functions. The critical grades of Groups Pm, Pa, and S are 2.8, 0.20 and 0.10 g/t (or g/m³), respectively. These values suggest that the mines with low grades are operated at the critical condition.

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Japanese mining industry has experienced several major disasters caused by mine fires. One of the reasons for many fatalities in those fires is an unexpected change in airflow direction in the ventilation network which is produced by the fires. Therefore, the knowledge of the effect of mine fire on mine ventilation network is indispensable for the management of personnel escape, rescue and fire fighting activities. The simulation of mine fire is also necessary to perform effectively these activities and mine ventilation control under mine fire.
A mine fire influences airflow in a mine ventilation network mainly in two ways, that is ,"ventilation pressure created by a fire (natural draft effect)" and "throttling effect". Air temperature distributions in the network is required in order to estimate the strength of the two effects. The air temperature is changed by the mixing with the fire gas downwind of a fire. Therefore, the fire gas temperature in the network is indispensable to make reasonable mine fire simulation by a computer. However, there is not a simple and reasonable method to estimate the fire gas temperature suitable for mine fire simulation yet. This paper discusses the method to estimate the fire gas temperature based on the results obtained in the actual size mine fire experiments.
It is concluded that Eq(22) is suitable for the prediction of the fire gas temperature in a roadway. Here, the fire gas is defined as the ventilation air which passed the fire zone, a mixture of the air and produced gases.

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Probability distribution of strength under uniaxial stress was examined on the basis of published data. It was found that strength followed the Weibull distribution. Shape parameter or coefficient of variation in air-dried condition gave good agreement with that in water-saturated condition.
Probability distribution of failure time in creep testing was also examined on the basis of published data. Failure time also followed the Weibull distribution. Shape parameter of creep life was found to agree well with that of strength.
Probability distribution of strength under triaxial stress field is considered to be important, however, only a few studies have been published. In this study, a tuff and a mudstone were tested under triaxial stress. It was found that strength followed the Weibull distribution. Shape parameters of tuff by this study and andesite by Yamaguchi did not change so much with confining pressure, however, that of mudstone increased notably.
The experimental data were discussed from not only deterministic but also stochastic points of view.

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Steel fiber reinforced mortar(SFRM) or concrete(SFRC) is one of the future promising composite materials and suits, for example, today's rapid excavation by a tunnel boring machine, a boom header or a continuous miner.
It is well known that SFRM is improved in toughness and crack resistance mainly by the pullout resistance of steel fibers. Though some pullout tests have been published, fundamental data concerning pullout resistance are still insufficient.
In this study, pullout tests were conducted pulling an indent-type steel fiber out of the mortar sample at a constant displacement rate by a servo-controlled testing machine. It was found that load-displacement curves obtained experimentally were not smooth with complicated shapes especially in the post-failure region (region after the maximum pullout resistance). The curves were classified into four patterns depending on the shapes. For every pattern, the maximum pullout resistance and the total pullout energy necessary to pull the steel fiber out of the mortar sample were obtained. Finally, the correlation between the maximum pullout resistance and the tensile strength of SFRM were discussed.

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Nowadays, more than 13 million-ton plastics are produced in Japan that are used in various industrial fields. There are three main well-known methods for plastic recycling. The purpose of each method includes material recycling, chemical recycling or thermal recycling (energy recovery) of plastics waste. However, new processes are continuously being developed for recycling of plastics waste. Especially, material recycling is considered a simple process, whereas, re-pellet process for wasted plastics is too difficult and unable to reproduce plastics that have the strength and the durability characteristics similar to virgin plastic materials.
Recently, plastic alloy process, especially those that employ a mixture of liquid crystal polymer as dispersant phase for fibril phenomena, has been focused on as a new plastic producing technology in order to have better characteristics such as strength, durability and ability to be recycled.
In this study, the strength and recyclable characteristics of plastic alloy materials are investigated using polycarbonate and polypropylene as the matrix plastics, as well as three kinds of liquid crystal polymer as fibril dispersant.
The experimental results of measurement of tensile strength, charpy impact and recycle times of various plastic alloys are summarized as follows,
(1) The plastic alloy that is used with polycarbonate as matrix plastic and novaccurate as a liquid crystal polymer has a higher tensile strength compared to other alloy materials. This is due to the fact that a fibril phenomenon was observed in this plastic alloy.
(2) In case of a mixture of polycarbonate and novaccurate, the recycled plastic alloy processed by single-shaft extruding machine exhibited a higher strength and recyclables property than the one processed by double-shaft extruding machine.
(3) Strength characteristics of plastic alloy materials by polycarbonate and novaccurate decreased with recycling times, as the reagent of the solubility phase was mixed with alloys.
(4) If the injection-molding machine is directly employed for the plastic alloy without extruding machine, a higher strength of plastic alloy could be expected similar to the one of grass fiber plastic (FRP).

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Dense CaS ceramics were prepared by liquid-phase sintering with Ga₂S₃ additives (0 ∼ 1.0 mol%). A relative density of 96.2% was achieved by the sintering of CaS samples with 0.5mol% Ga₂S₃, fired at 1573K for 6h in Ar flow. Sintering process was investigated with scanning electron microscopy observations and linear shrinkage measurements. The sintering process of Ga₂S₃-doped CaS was found to be followed by 3 steps: (1) the rearrangement of CaS particles by CaS-Ga₂S₃ liquid, (2) the dissolution of CaS particles and the precipitation of CaS grains due to diffusion-controlled process and (3) the growth of precipitated CaS grains. X-ray diffraction and microstructural analyses with an energy dispersive X-ray fluorescence spectrometer revealed that sintered CaS has mainly CaS phase and CaS-Ga₂S₃ liquid segregated around grain boundaries. The thermal expansion coefficient of sintered CaS was 19.1 × 10^-6/K in the range room temperature to 1273K. It was suggested that ceramic materials with similar thermal expansion coefficients are appropriate for the substrate of CaS based thin film electroluminescence.

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Red fluorescent properties of Mn²⁺ in oxide compounds were investigated in order to improve the chromaticity of red emitting-phosphors. Mg₄Ta₂O₉ and Mg₄Nb₂O₉ with corundum-type structure were selected for the matrix of Mn²⁺ based on the ionic radius and oxygen coordination number of Mn²⁺ site. Mg₄Ta₂O₉ : Mn²⁺ with excitation of 254 nm shows a red fluorescence centered at 660 nm due to the ⁴T₁→⁶A₁ transition of Mn²⁺. On the other hand, Mn ions in Mg₄Nb₂O₉ do not show any fluorescence. The measured CIE chromaticity value of the red fluorescence of Mg₄Ta₂O₉ : Mn²⁺ is x = 0.713, y = 0.287; therefore the chromaticity of red fluorescence of Mg₄Ta₂O₉ : Mn²⁺ is better than that of commercially available Y₂O₃ : Eu³⁺ with x = 0.630, y = 0.365. However, the red fluorescence intensity of Mg₄Ta₂O₉ : Mn²⁺ is about one-third that of Y₂O₃ : Eu³⁺. The compositional dependence of fluorescent properties of Mn ions in Mg₄Ta₂O₉ and Mg₄Nb₂O₉ with corundum-type structure was discussed in terms of stability of crystal structure. The relationship between the preparation conditions and the red fluorescence intensity of Mg₄Ta₂O₉ : Mn²⁺ was also discussed based on the redox of Mn ions.

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Arsenic exists mostly as arsenite (As(III)) or arsenate (As(V)) in natural water. As(III) is more toxic than As(V), and As(V) is removed more effectively than As(III). Some hot spring waters contain As(III). The oxidation of As (III) to As (V) is necessary to achieve effective removal of arsenic. This paper describes a new bacterial strain which is able to efficiently oxidize As(III) to As(V) at 50-60 °C. The strain was isolated from a hot spring water. The oxidation rate of As(III) decreased with decrease in temperature. As(III) was oxidized in the pH range from pH7.0 to pH8.7.The bacteria gained the energy for the growth from arsenite oxidation and the growth was enhanced with yeast extract.

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Adsorption gels were prepared from orange juice residue and brown seaweed (Konbu) which contain acidic polysaccharides, pectic acid and alginic acid, respectively, by means of saponification with calcium hydroxide followed by water washing and drying (gel A) and by crosslinking with epichlorohydrin(gel B), respectively, which greatly suppressed the leakage of water soluble components contained in these gels. Free acid type adsorption gel (gel C) was also prepared from the above-mentioned gel prepared from orange juice residue by washing with dilute hydrochloric acid. Big difference was observed between the gel A and the gels B and C in the adsorption behavior for ferric ion; that is, in the case of the adsorption on the gel A, it monotonously increased with increasing pH while, in the case of those on the gels B and C, it increased with increasing pH at low pH, but, it decreased with further increasing pH at pH higher than 2.5 ∼ 3. By using the gels A and B loaded with ferric ion, adsorption tests of arsenate and arsenite were carried out at 30 °C and compared with the conventional coprecipitation method with iron salt. It was found that arsenate was quantitatively adsorbed at low pH on the gels A (pH = 2 ∼ 5) and B (pH = 2 ∼ 3) while only 90 ∼ 80 % was removed at pH = 5 ∼ 6 by means of the coprecipitation method. In addition, several % of the coprecipitated arsenic was found to be dissolved in water while no leakage was detected from the gels. On the other hand, arsenite was effectively adsorbed under weakly basic condition.
On the basis of the above-mentioned adsorption tests using model arsenic solution, a field test of adsorptive removal of arsenic was carried out from the actual mine water at Horobetsu pyrite mine using the gels A and B. The mine water contains a large amount of iron the majority of which is ferrous ion in addition 10 mg / dm³ arsenic and pH is 1.8. To the sample of the mine water, magnesium oxide was added to adjust pH together with these gels which were unloaded with ferric ion. It was found that arsenic was nearly quantitatively removed by these gels over wide range of pH 4 ∼ 10 while considerable amount of arsenic, greater than 0.1 ml / dm³, was remained in the treated water in case these gels were not added, i.e. by the conventional coprecipitation method.

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