The efforts of electronic companies to minimize environmental impact of their products are reviewed, considering product life, facility of disassembly, recycability of materials, reduction of halogen content, eco-packaging, and use of lead free solder. Technical developments in the reclamation of optical disks, batteries and polystyrene resins are also reported. To enhance the eco-efficiency, cooperation between electronic industry and other industries should be encouraged.

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A number of studies on electromagnetic wave emission from fractured rocks have been heretofore carried out. By many authors it was pointed out that rock fracturing or acoustic emission could be concerned with electromagnetic wave emission. However, the origin of electromagnetic wave emission is still not well understood.
In this study electromagnetic wave from rocks was measured with a radio interference measuring apparatus during uniaxial compression testing under several kinds of loading conditions.
Firstly, the uniaxial compression testing under constant strain rate of 10^-4 s^-1 was conducted for seven rocks. It was found that Inada granite, Honkomatsu andesite and Kuzuu dolomite emit electromagnetic wave. However electromagnetic wave cannot be detected for Sanjome andesite, Akiyoshi marble, Kimachi sandstone and mortar.
Secondly, electromagnetic wave emission was investigated under several experimental conditions. It was found that Inada granite emits electromagnetic wave during uniaxial compression testing under a constant strain rate of 10^-5 s^-1 and under a constant rate of (stress-strain / Young's modulus).
In most cases, electromagnetic wave emission was accompanied with sudden decrease of stress. By analysis on results of the uniaxial compression testing under constant strain rate, it was found that electromagnetic wave emission is closely related to cracking or crack extension.
The main results in this study can be summarized as follows;
1) Amplitude of electromagnetic wave is relatively large for strong rock.
2) For Inada granite, the larger the stress drop occurred in uniaxial compression test is, the larger the amplitude of electromagnetic wave.

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In order to clarify the fatigue failure process of shirahama sandstone, fatigue tests were done, and deformation characteristics and AE occurrence behavior were investigated. Then, the strength of specimens, which loading and unloading were repeatedly applied to for some times, and crack development in them were examined.
In the fatigue test, fatigue failure occurs in the comparatively short time (about 3.5 days), when upper limit stress corresponds to the stress at stage C of uniaxial compression failure process, where the volume of the rock specimen expands. The fatigue failure process are divided into three stage (I, II, III) from change in strain and AE activity. Lowering the strength of the rock specimen begins from stage II of fatigue failure process, and it is in a good correlation with the increase in lateral / axial strain ratio. The value of b obtained from the relationship between AE event frequency and AE energy of each event decreases when macroscopic cracks develop in the specimen.

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Not only axial strain but also lateral strain were measured during creep tests on Noboribetsu welded tuff under air-dried and water-saturated conditions in which the water contents of specimens were regulated about 0.3% and 17%, respectively. Creep rupture strength under water-saturated condition was smaller than that under air-dried condition. The difference in them was comparable to that in uniaxial compressive strength under both conditions. The axial and lateral strain rates decreased linearly with time in a log-log plot in the primary stage. They increased until a rupture occurs after the strain rates had reached the minimum magnitude. Creep failure time tended to increase as the "decrease rates of the strain rates" in the primary stage increased. Creep failure time and the life after the minimum strain rate increased as the minimum magnitude in the strain rates decreased. In the tertiary stage, the strain rates were inversely proportional to residual life. These relationships were represented by the same curves regardless of the water content. Therefore, the creep failure time would be successfully estimated from the behaviors of either axial or lateral strain rate regardless of the water content by using the experimental results. Thin sections of the specimens that had experienced various levels of the creep deformation were prepared and observed under a microscope. Nucleation of cracks and pores that distributed along the loading axis in the matrix were observed for specimens that had been just before the rupture.

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Specific energy of the chipping upon water jet drilling is discussed from a latticed multi-point drilling experiment, to make clear the utility of chipping as an excavation measure in hard rock. The experiment is conducted using the full-size specimen of Amakusa sandstone of the uniaxial compressive strength: S_C = 84 MPa, and Granite of S_C = 190 MPa. The optimum drilling interval is evaluated as well as the specific energy E_s, after consideration to the relation between the crater depth: h and the excavation volume: V. It is clarified that the dimension ratio of m = S_C / E_s is in a range of from 0.40 to 0.55 in the case of the driving pressure: p_I = 90 MPa. A model named the repetition model is proposed, to forecast the specific energy of the continuous chipping by the Third Power Method, and its validity is successfully verified by comparing the computation to the experimental results. Subsequently, it is discussed that the continuous chipping results in an excavation of higher efficiency than both of the pure water jet cutting and the abrasive water jet cutting.

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The formation and dissociation properties, the gas composition of gas hydrate synthesized from the mixed gas of air and carbon dioxide, were investigated to make clear the behavior and the structure. From the experiments and discussion, the following results are obtained.
The formation and dissociation condition of gas hydrates formed from CO₂-Air mixtures have close relation with the components of mixed gases, so that the temperature and pressure for the formation and dissociation can be estimated by the initial condition of mixed gases.
Based on the result that the guest components in synthesized hydrate contain much higher concentration of CO₂ than in the initial gas mixture, it was found that the hydration technique can be used for the accumulation of CO₂ component in gas phase.
From the direct observation of guest components using Raman Spectroscopy, it was shown that a lot of N2 component was trapped as guests in the structure of CO₂ gas hydrate.
The behavior and the control of CO₂ gas hydrate in the sediments would be examined to clarify the fundamentals for the storage of CO₂ gas hydrate, using a more realistic experimental apparatus simulated for the in-situ deep marine environment.

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Diatomaceous earth, which is found throughout the world, is mainly composed of diatom crusts associated with a small amount of clay and detrital rocks. The diatom crust, amorphous silica, is characterized by dissolution in caustic alkaline solution. In this study we examined the distribution of silica and trace elements leached from diatomaceous earth by 10 w / v % NaOH solution in detail. The results are as follows:
(1) 31 diatomite samples of seawater origin were collected from 4 ore deposits located in Akita Prefecture and 28 samples of freshwater origin were collected from 2 ore deposits in Okayama and Oita Prefecture. The specimens mainly consisted of a white or grayish white assemblage of diatoms in the range of μ ∼ mm order.
(2) By qualitative analysis, abundant silica and small amounts of 16 elements in dissolved solutions were detected, while the presence of 26 elements in bulk specimens were confirmed.
Taking into account the sensitivities of the AAS and ICP-AES analyses, Si, Al, K, Fe and B were quantitatively analyzed. An abundance of silica extracted from diatomite reached 86 ∼ 98 % in bulk samples, Al, K and Fe content were relatively high in the range of 25,000 ∼ 200 ppm. B was present at the less than 150 ppm. Based on similarities among the distribution patterns of each element, it was observed that Silica and B were derived from diatoms, and Al, K and Fe from detrital rocks.
(3) The need for high quality silica as a raw material has been increasing, and reserves of high purity quartz will be exhausted in the near future; thus, how to produce high quality silica from diatomaceous earth is of great importance. In particular, the B content in silica must be very low below a few ppm. At present, some solutions extracted from diatomite with a freshwater origin have lower concentrations (4.3 ∼ 13 ppm) than those of seawater origin(80 ∼ 150 ppm). From the data we suggest that diatomaceous earth should be considered as a potential source of high purity silica.

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Mg²⁺+-exchange characters have been investigated on the effects of the concentration of exchange solution, temperature, treating duration and number of exchange times. Higher exchange of Mg²⁺+ was achieved for the A-zeolite treated with the solution of lower concentration, 0.1 mol / dm³(pH = 5.5) of Mg²⁺+ rather than the concentrated solution of 2.0 mol / dm³(pH = 4.4). The maximum exchange, 89 %, by Mg²⁺+ (Mg89-A) was obtained after repeating the exchange by three times with 0.1 mol / dm³ MgCl₂-solution at 353 K for 5h. TG-measurements were effective to characterize hydration states of the products. Mg89-A showed the maximum dehydration, 30.1 %, at 1,073 K and has the largest dehydration ratio above 473 K, but the ratio is the largest for Mg44-A at the temperature around 363 ∼ 423 K. DTG-curves show distinctive nature in peak distributions: one peak at 413 K for Na-A, double peaks at around 360 ∼ 373 K and at around 421 ∼ 428 K for increasing Mg-content, and the one peak at 424 K for Mg89-A. Energetic states of water molecules in Mg²⁺+-exchanged A-zeolites are therefore not always simple with increasing amounts of Mg²⁺+. The appropriate Mg²⁺+-exchange ratio should be adaptable for the dehydration temperature used for a heat pump system.

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Aragonite-type of light calcium carbonate was synthesized by the successive reaction using calcined-hydrous scallop shells and calcined lime stones in the aqueous system with Mg²⁺ ions under the CO₂ bubbling. In order to obtain the high aspect ratios of aragonite, the reaction temperature and concentrations of Ca²⁺ ions in the 2nd step were important. The aspect ratio of aragonite increased when the reaction temperature was higher in the 2nd step than in the 1st step of the successive reaction. When the smaller amounts of calcium source were added in the 2nd step than in the 1st step, and the reaction temperature was lower in the 2nd step than in the 1st step, large particles of aragonite were produced with no smooth surfaces. The successive reaction was useful to extend the variety of morphologies in aragonite.

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With the purpose of understanding nature of abnormal electrodeposition during industrial silver electrolysis, relationship between electrolysis conditions and morphology of the deposits was investigated. SEM observation of the deposit on a silver working electrode with 4 mm² initial surface area was carried out under various silver nitrate concentrations, nitric acid concentrations and applied overpotentials. Crystallographic morphology of the deposit after passing 10 C of electric charge was acicular form when the applied overpotential was low. As the overpotential increased, dendritic deposit tended to grow. Under high overpotential condition, which caused lack of silver ion supply to the electrode, deposit with spongy form was obtained. Change of the morphology was shown to depend on silver ion concentration in the vicinity of the electrode, and fine crystals were obtained when silver nitrate concentration was decreased. Increment in nitric acid also caused fine deposition. Contribution of nitrite ion, which is thermodynamically expected to be generated during electrolysis, was not observed under the conditions employed in this study.

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