Search Results - (Author, Cooperation:T. Arai)

2013-03-30

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Absorption ; Alkynes/chemistry ; Analytic Sample Preparation Methods/*methods ; Animals ; Biological Products/chemistry ; Crystallization/*methods ; Crystallography, X-Ray/*methods ; Fatty Alcohols/chemistry ; Microchemistry/*methods ; Nanotechnology/*methods ; Porifera/chemistry ; Porosity

2014-09-13

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2014-11-08

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

0014-5793

Enzymatic synthesis ; Tryptophan synthase ; β-1-Indazole-L-alanine

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The stabilities of the electrical properties and microstructures of Pt, PtAu, NiAu, and TaTi ohmic contacts after contact formation were studied. The Pt and PtAu contacts annealed in an O2 and N2 mixed gas ambient had the specific contact resistance (ρc) of high-10−3 Ω cm2 and strong adhesion to the GaN substrates. The NiAu contact annealed in the partial O2 ambient had poor adhesion to the GaN, although the ρc value of low-10−3 Ω cm2 was obtained. The TaTi contact had the lowest ρc values of less than 10−4 Ω cm2. After contact formation, the Pt and NiAu ohmic contacts prepared by annealing in the partial O2 ambient showed the excellent electrical and microstructural stabilities during room temperature storage and current injection. However, the contact resistance of the TaTi contact prepared by annealing at 800 °C increased during room temperature storage, and the mechanical failure of the contact was also observed after injecting current as low as 4 kA/cm2. From the present experiments, it was concluded that the Pt and PtAu contacts were the most reliable ohmic contact materials for p-GaN among four contact metals. © 2001 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We demonstrated in our previous paper [Appl. Phys. Lett. 74, 275 (1999)] that TaTi contacts annealed at temperature of 800 °C provided a specific contact resistance (ρc) of around 3×10−5 Ω cm2 for p-GaN epilayers with hole concentration of 7.0×1017 cm−3. The reduction of the contact resistances was believed to be due to reactivation of Mg atoms doped in the GaN epilayer by removing H. In the present article, diffusion behavior of hydrogen atoms in the p-GaN was extensively studied by secondary-ion mass spectroscopy and correlated with the electrical properties of the TaTi contacts. It was found that formation of the low-resistance TaTi ohmic contacts was well explained by diffusion behavior of hydrogen in the p-GaN. Although the deterioration rates of the TaTi contacts during low temperature storage after ohmic contact formation were coincident with the diffusion rates of hydrogen atoms in the GaN, the deterioration mechanism could not be explained simply by hydrogen release from the TaTi contacts into the GaN. We believe that selection of a contact metal which would remove the hydrogen without inducing crystalline defects in the GaN after the metal and GaN reaction is a key to prepare highly reliable, low-resistance ohmic contacts for p-GaN. © 1999 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Although extensive efforts have continued to develop Ohmic contacts for p-type GaN, which have specific contact resistance (ρc) lower than that (ρc∼10−2 Ω cm2) of conventional Ni/Au contacts, to the best of our knowledge no breakthrough has been reported in open literature. We demonstrated that bilayered Ta/Ti contacts have a ρc value of around 3×10−5 Ω cm2 for p-type GaN with a hole concentration of 7×1017 cm−3. This contact has resistance low enough to manufacture blue laser diodes, but deterioration of the ρc value during room-temperature storage is the key issue. © 1999 American Institute of Physics.

Electronic Resource

1365-2044

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1365-2559

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Aims : Apocrine carcinoma of the breast is typically, though not always, positive for gross cystic disease fluid protein-15 (GCDFP-15). In order to clarify the clinical significance of GCDFP-15 in apocrine carcinomas, GCDFP-15 expression was examined in apocrine carcinomas of different stages and compared with clinicopathological factors. Apocrine lesions reportedly exhibit an unusual immunohistochemical status, expressing androgen receptors (AR) instead of oestrogen receptors (ER), progesterone receptors (PR), or bcl-2. Their expression was also examined.Methods and results : Fifty-two apocrine carcinomas were examined immunohistochemically. Thirty-nine (75%) and 29 (56%) were positive for GCDFP-15 and AR, respectively. GCDFP-15 positivity was significantly lower in infiltrating carcinomas than intraductal carcinomas (P = 0.0111). In infiltrating carcinomas, GCDFP-15 positivity was significantly low in tumours ≥ 15 mm (P = 0.0005) and node-positive tumours (P = 0.0004). Similar phenomena were observed for AR. Rare cases were positive for ER (3.8%), PR (5.8%), and bcl-2 (1.9%).Conclusions : GCDFP-15 positivity is transient and should not be considered a definitive marker of apocrine carcinomas. Cases which have apocrine features but lack GCDFP-15 expression should rather be considered as advanced apocrine carcinomas. ER/PR/bcl-2 negativity will sometimes be helpful to confirm the diagnosis of apocrine carcinoma, because it is more consistent than GCDFP-15/AR positivity.

Electronic Resource

1365-2044

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Two cases of common peroneal nerve palsy after coronary artery bypass grafting surgery are described and the possible causative mechanisms are discussed.

Electronic Resource

1365-2044

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1600-0765

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

We analyzed stress-strain curves in transverse sections at three different root levels of the cervical, middle, and apical regions of the distal root of the mandibular first molar in hamsters fed a high-carbohydrate (experimental group) or standard (control group) diet for 8 weeks. Each section was loaded in vitro at a rate of 5 mm/min in an extrusive direction. The rupture sites and the structures of birefringent collagen fibers in the periodontal ligament were also analyzed. The maximum shear stress, tangent modulus, and failure strain energy density of the periodontal ligament were significantly greater in the cervical region than in the middle and apical regions in both the control and experimental groups. The maximum shear stress, tangent modulus, and failure strain energy density of the periodontal ligament in the experimental group were significantly lower than those in the control group at the ervical and middle regions. The maximum shear strain was significantly greater in the experimental group than in the control group at the middle and apical regions. Histological sections showed that the periodontal ligament ruptured irregularly in both groups. The collagenous fibers of the ligament in the experimental group appeared to be thinner and less birefringent at the cervical and middle regions of the root. These results suggest that a high-carbohydrate diet differentially affects the collagen fibers in the periodontal ligament as a function of the root level, and that these effects are evident in changes in the mechanical properties of the ligament.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

The migratory history of the white-spotted charr Salvelinus leucomaenis was examined using otolith microchemical analysis. The fish migrated between freshwater and marine environments multiple times during their life history. Some white-spotted charr used an estuarine habitat prior to smolting and repeated seaward migration within a year.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Anadromy in the Dolly Varden Salvelinus malma at the southern limits of its distribution were examined by an intensive field survey and measurements of otolith Sr and Ca concentrations. Body sizes of anadromous individuals were small, only slightly larger than those of mature parr, and the degree of anadromy was extremely low.

Electronic Resource

1439-0264

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The muscles of mastication and their related skull characters in the Caspian seal (Phoca caspica) were anatomically examined and compared with those of the Baikal (Phoca sibirica) and ringed (Phoca hispida) seals. A well-developed masseter muscle was observed in the Caspian seal, whereas the temporal muscle consisted of thin bundles. The skull of the Caspian seal possessed the same thin frontal bone and the dorso-ventrally developed zygomatic arch found in the Baikal seal that are required to install the enlarged eyeball into the orbit. The temporal bone was not robust, and the digastric muscle was well-developed in the ventral space of the auditory bulla. The present results suggest that the skull form of the Caspian seal has changed morphologically from its ringed seal-like ancestors, and suggest that the evolutionary strategy of the muscles of mastication in the Caspian seal is principally consistent with that of the Baikal seal.

Electronic Resource

1460-9592

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1439-0426

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Strontium (Sr) and calcium (Ca) concentrations in the otoliths of the shirauo, Salangichthys microdon, collected from Japanese coastal waters were examined by wavelength-dispersive X-ray spectrometry on an electron microprobe. The otolith Sr : Ca ratios gradually increased from 15.7−19.7 × 10−3 around the core to 32.8−39.4 × 10−3 around the edge of otoliths, with no transition point from the low Sr : Ca ratio phase to the high phase. The fluctuation pattern of otolith Sr : Ca ratios was different from the anadromous form reported in a previous study. The evidence indicates that the fish do not necessarily migrate into freshwater during the growth phase.

Electronic Resource

1439-0426

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

The age and migratory history of the Japanese eel, Anguilla japonica Temminck & Schlegel, collected in Miyako Bay along the Sanriku coast of Japan, was examined using the otolith microstructure and analysis of strontium (Sr) and calcium (Ca) concentrations conducted with wavelength dispersive X-ray spectrometry by an electron microprobe. The line analysis of Sr : Ca ratios along the life history transect of each otolith showed a peak (ca. 15–17 × 10−3) which corresponded with the period of their leptocephalus and early glass eel stages in the ocean. The mean Sr : Ca ratios from the elver mark to the otolith edge indicated that there were eels with several general categories of migratory history, including sea eels that never entered freshwater (average Sr : Ca ratios, ≥6.0 × 10−3), and others that entered freshwater for brief periods but returned to the estuary or bay. This evidence of the occurrence of sea eels in this northern area indicates that Japanese eels of the Sanriku coast do not necessarily migrate into freshwater rivers during recruitment as do glass eels at the beginning of their growth phase; even those that do enter freshwater may later return to the marine environment. Thus, anguillid eel migrations into freshwater are clearly not an obligatory migratory pathway, but rather a facultative catadromy with seawater or estuarine residents as an ecophenotype.

Electronic Resource

1439-0426

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Electronic Resource

1365-2559

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Aims:  The pathogenesis of breast carcinoma in very elderly women is of interest, because oestrogen levels are likely to be extremely low during the development of the disease. In an effort to understand the pathogenesis of breast carcinoma in these women, this study was undertaken to compare the histological patterns and hormone receptor status of breast carcinomas arising in very elderly and younger women.Methods and results:  Thirty-seven breast carcinomas from women over the age of 85 years at the time of their operation were examined histologically and compared with those from a large group of premenopausal women. The proportions of mucinous carcinoma and apocrine carcinoma were significantly greater in older women. The expression of steroid hormone receptors was studied immunohistochemically. Androgen receptor-positive carcinomas were significantly more frequent among older women, whereas progesterone receptor-positive carcinomas were significantly less frequent. There was no statistically significant difference in oestrogen receptor-α or -β expression between the tumours from both groups.Conclusion:  Breast carcinomas in women over the age of 85 years have a different morphological spectrum from carcinomas in younger age groups and may have different pathogenesis mechanisms that may be more dependent on androgen and androgen receptor interaction. Differences from the results of the other studies are discussed.

Electronic Resource