Motohiro Uo

Synthesis and spectroscopy of tpps-doped silica gels by the sol-gel process

Tetraphenylporphinetetrasulfonic acid (TPPS), which is well known as a photochemical hole-burning (PHB) dye, was incorporated in silica gels obtained by the sol-gel process from tetramethoxysilane (TMOS). The form of TPPS must be free base (H2P), which exists in basic condition, to be active in PHB. To obtain transparent and higher density silica gels doped with free-base TPPS, two-step hydrolysis processes using solutions containing NaOH were developed, and the gels having bulk density of about 1.5 g/cm3 were synthesized. The form of TPPS in the gels was investigated by measuring the absorption and luminescence spectra, and it was found that in the silica gels almost all the TPPS retained free-base form at the molar ratio of NaOH/TMOS above 10−3.

Synthesis and spectroscopy of TPP derivative-doped silica gels prepared by the sol-gel process

Abstract Tetrakis (4-sulfonatophenyl) porphyrin (TSPP) and terakis (N-methyl-4-pyridyl) porphyrin 4+ (TMPyP) which are well known as photochemical hole burning (PHB) dyes, were incorporated in silica gels obtained by the sol-gel process from tetramethoxysilane (TMOS). The hole-burning experiment was performed at 4.2 K. The hole-burning efficiency was quite lower for TSPP than for TMPyP. This result suggests the existence of PHB inactive or ineffective state for TSPP in the silica gel.

Copper accumulation in the sequestrum of medication-related osteonecrosis of the jaw

Bisphosphonates (BPs) have been widely, efficiently, and safely used for the treatment of various bone-related diseases such as osteoporosis. However, concerns about jaw osteonecrosis associated with oral treatment (medication-related osteonecrosis of the jaw [MRONJ]) have been increasing. Although many risk factors for MRONJ have been elucidated, its precise etiology and methods of prevention remain unknown. In this study, we have applied various elemental analysis methods for MRONJ specimens (e.g., X-ray fluorescence with synchrotron radiation [SR-XRF], particle-induced X-ray emission [PIXE], X-ray absorption fine structure [XAFS]) in order to reveal the accumulation and chemical state of trace bone minerals. In four MRONJ sequestra, the characteristic localization of copper (Cu) was observed by SR-XRF. Using micro-PIXE analysis, Cu looked to be localized near the edge of the trabecular bone. The chemical state of the accumulated Cu was estimated using XAFS and the possibility of a Cu–BP complex formation was assumed. Thus, in this study we argue for the feasibility of the trace element analysis to evaluate the potential pathophysiological mechanism of MRONJ.

Preparation and optical properties of amorphous silica doped with porphines and quinizarin by the sol-gel process

Amorphous siliceous materials with molecular dispersions of organic molecules, TPPS, TMPyP and DAQ were prepared by a sol-gel process in which Si(OC2H5)4 was hydrolyzed in weak acid solution. Effect of ultrasonic irradiation on the sol-gel process was studied for the TPPS/a-SiO2 system in order to attain the further molecular dispersions and shorten the sol-gel reactions. Optical properties of TMPyP doped sol-gel thin films were observed. An amorphous silica thin film which was doped with TMPyP on the order of 1 X 10-3 mol/mol SiO2 showed photochemical hole burning at 20 K. the TMPyP/a-SiO2 was heat-treated at various temperatures and the changes of optical spectrum were observed as a function of temperature. It was found that the sample was comparatively stable up to 200 degree(s)C. Apparent quantum yields of PHB of porphines and quinizarin in polymer or sol-gel film and bulk were discussed.

The effect of rare-earth oxides on the crystallization of CaO–Al2O3–SiO2 glasses

CaO–Al2O3–SiO2 –La2O3–Nd2O3 glass was prepared and their physical properties, such as density, glass transition temperature and crystallization temperature, were measured. The heat treatment of these glasses precipitated Ca2La8(SiO4)6O2 oxyapatite (CLS) crystal for 20CaO–10Al2O3–60SiO2–10La2O3 (mol%) glass and Ca2Nd8(SiO4)6O2 oxyapatite (CNS) crystal was precipitated with Nd2O3 substitution. Crystallization of these glasses was observed at the surface and internally within the samples. The spherical and stick-like crystals were observed throughout the bulk of the glasses and the surface crystal layer of oxyapatite crystals were strongly oriented along the c-axis. The apparent activation energies of crystal growth were estimated as 360 kJ mol−1.

Preparation and optical properties of amorphous silica doped with porphins of free-base by the two-step sol-gel process

Tetraphenylporphinetetrasulfonic acid (TPPS), which is known as a photo-chemical holeburning (PHB) dye, was incorporated in silica gels obtained by the sol-gel process from tetraethoxysilane (TEOS). The form of TPPS must be free-base (H 2P), which exists in basic condition, to be active in PHB. In this study to obtain transparent and dense silica gels doped with free-base TPPS, a two-step hydrolysis process using solutions containing NaOH or using ammonia were developed. In the first step we used acidic catalyst to get denser and transparent gels and in the second step basic catalyst was adopted to obtain free-base TPPS. Monolithic silica gels can be obtained by this two-step process from the hydrolysis of TEOS. By the spectroscopic analysis of TPPS incorporated in the gels, it is found that the free base form of TPPS is retained at the molar ratio of NaOH/TEOS above 10-3. The spectra of monocation are observed at the molar ratio of NaOH/TEOS below 10-3. And the dimerization of TPPS incorporated in the TEOS gels does not occur at higher NaOH concentration than that in the TMOS gels.

Synthesis and spectroscopy of organic dye-doped silica gels by sol-gel process

Tetraphenylporphinetetrasulfonic acid (TPPS), which is well known as a photochemical hole burning (PHB) dye, was incorporated in silica gels obtained by the sol-gel process from tetraethoxysilane (TEOS). The form of TPPS must be free base (H 2 P), which exists in basic condition, to be active in PHB. To obtain transparent silica gels doped with free-base TPPS, two-step hydrolysis processes using solutions containing NaOH were developed, by the spectroscopic investigation, it was found that in the silica gels almost all the TPPS retained free-base form at the molar ratio of NaOH/TEOS above 10 −3 , and that the dimerization of TPPS incorporated in the TEOS gels did not occur higher NaOH concentration than that in the TMOS gels.

Improved expert system for materials design of glasses

Improved expert system for materials design of glass which uses AI softwares ESHELL or KBMS has been studied to support to develop new glasses.In this system glass composition which has desired properties can be speculated by the calculation and selection from data base, knowledge base and table of 60 oxides, and one can also speculate glass compositions of desired properties from desired kinds of oxides which are commonly used for glass melting or for adjusting various kinds of properties.One can change the coefficients or parameters for the calculation of properties to adjust the speculated properties. Knowledge base on glass formation ranges tells us the possibility of vitrification of the designed glass composition.