Wyniki wyszukiwania - BazTech

1

Naturally occurring radionuclides and rare earth elements in weathered Japanese soil samples

Sahoo S., Hosoda M., Prasad G., Takahashi H., Sorimachi A., Ishikawa T., Tokonami S., Uchida S.

Acta Geophysica

|

2013

|

Vol. 61, no. 4

876--885

EN

The activity concentrations of 226Ra and 228Ac in weathered Japanese soils from two selected prefectures have been measured using a γ-ray spectroscopy system with high purity germanium detector. The uranium, thorium, and rare earth elements (REEs) concentrations were determined from the same soil samples using inductively coupled plasma mass spectrometry (ICP-MS). For example, granitic rocks contain higher amounts of U, Th, and light REEs compared to other igneous rocks such as basalt and andesites. Therefore, it is necessary to understand the interaction between REEs and nature of soils since soils are complex heterogeneous mixture of organic and inorganic solids, water, and gases. In this paper, we will discuss about distribution pattern of 238U and 232Th along with REEs in soil samples of weathered acid rock (granite) collected from two prefectures of Japan: Hiroshima and Miyagi.

2

Use of fine particle quartz sand for AAC production: model study by in situ X-ray diffraction and NMR

Kikuma J., Tsunashima M., Ishikawa T., Matsuno S., Ogawa A., Matsui K.

Cement Wapno Beton

|

2011

|

nr spec.

12-15

EN

In order to clarify important factors which govern the tobermorite formation in hydrothermal reaction, the effects of quartz particle size and water content were investigated for simplified model systems by in-situ XRD and Si-NMR. Although the reaction time was largely dependent on the quartz particle size, the average Ca/Si in non-crystalline C-S-H at the time that either tobermorite or semi-crystalline C-S-H start to be formed (TO) was nearly identical for all samples. The importance of molar ratio Ca/Si as well as the silicate chain length in non-crystalline C-S-H was suggested. Tobermorite can be synthesized even in the systems with large w/s and fine quartz. It was suggested that lower calcium and/or silicate ion concentration in the solution phase is important for tobermorite formation.

3

Influence of addition of AI compound and gypsum on tobermorite formation in autoclaved aerated concrete studied by in situ X-ray diffraction

Matsui K., Ogawa A., Kikuma J., Tsunashima M., Ishikawa T., Matsuno S.

Cement Wapno Beton

|

2011

|

nr spec.

3-6

EN

The hydrothermal formation of tobermorite during the processing of autoclaved aerated concrete was investigated by in situ XRD analysis. The XRD measurement is carried out using high-energy X-rays from a synchrotron radiation source. The effects of AI and gypsum addition on tobermorite formation were studied. Acceleration of tobermorite formation by AI and gypsum addition was clearly observed. The tobermorite formation mechanisms were discussed in these systems.

4

Strong photo-catalytic fiber and its wide application

Ishikawa T.

Physicochemical Problems of Mineral Processing

|

2010

|

Vol. 45

57-71

EN

In order to avoid large problems regarding peeling of the titania layer coated on the substrate, we developed an epoch-making "strong titania fiber" consisting of photoactive surface layer with a nanometer-scale compositional gradient, which can effectively oxidize any kind of organic materials. An effective water-purification system using this fiber has been also developed. The basis of this technology is to incorporate a selected low-molecular-mass additive (Ti(OC4H9)4) into a precursor polymer from which the ceramic forms. After melt-spinning the resulting precursor polymer, thermal treatment of the spun fiber leads to controlled phase separation ("bleed-out") of the additive; subsequent calcination stabilizes the compositionally changed surface region, generating a functional surface layer. This fiber consists of the silica-based core-structure and the gradient-like surface titania layer, which are strongly sintered. We also developed a water-purifier using this fiber (felt material). Any bacteria (common bacterium, legionera pneumophila, colon bacillus, heterotrophic bacteria, and so forth) and organic chemicals (dioxin, PCB, and so forth) were effectively decomposed into CO2 and H2O passing through the above purifier.

5

Low-cost 320 x 240 uncooled IRFPA using conventional silicon IC process

Ishikawa T., Ueno M., Endo K., Nakaki Y., Hata H., Sone T., Kimata M.

Opto-Electronics Review

|

1999

|

Vol. 7, No. 4

297-303

EN

A 320 x 240 uncooled infrared focal plane array (IRFPA) with series PN junction diodes fabricated on a silicon-on-insulator (SOI) wafer has been developed. Resistive bolometers, pyroelectric detectors and thermopile detectors have been reported for large scale uncooled IRFPAs, while the detector developed uses the temperature dependence of forward-biased voltage of the diode. The diode has low 1/f noise because it is fabricated on the monocrystalline SOI film which has few defects. The diode is supported by buried silicon dioxide (BOX) film of the SOI wafer, which becomes a part of a thermal isolated structure by using bulk silicon micromachining technique. The detector constains an absorbing membrane with a high fill factor of 90% to achieve high IR absorption, and the readout circuit of the FPA constains a gate modulation integrator to suppress the noise. Low cost IRFPA can be supplied because the whole structure of the FPA is fabricated on commercial SOI wafers using a conventional silicon IC process.