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Search Results: 1 - 10 of 3143 matches for " Chiaya Yamamoto "
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Feasibility Study to Evaluate Lattice-Space Changing of a Step-Graded SiGe/Si (110) Using STEM Moiré  [PDF]
Junji Yamanaka, Mai Shirakura, Chiaya Yamamoto, Kei Sato, Takane Yamada, Kosuke O. Hara, Keisuke Arimoto, Kiyokazu Nakagawa, Akimitsu Ishizuka, Kazuo Ishizuka
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.67002
A moiré between crystal lattice planes and scanning electron beam-lines formed in a scanning transmission electron microscope includes the information of the lattice spacing. We apply these phenomena to a compositionally graded SiGe thin film deposited onto a Si substrate by molecular beam epitaxy method. The results of the experiments and image analysis show the potential of this technique to analyze a slight change of the lattice spacing according to a compositional change.
TEM and STEM Observations of a Flat Continuous Silicon-Germanium Thin Film Epitaxially Grown on Porous Silicon  [PDF]
Junji Yamanaka, Noritaka Usami, Sevak Amtablian, Alain Fave, Mustapha Lemiti, Chiaya Yamamoto, Kiyokazu Nakagawa
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.51004
Strain-relaxed SiGe is an attractive material for use as a substrate of strained Si, in which carrier mobility is higher than that of bulk Si. The concept of this study is the use of porous Si as a sponge like substrate so that a SiGe lattice can relax without introducing dislocations. We produced porous Si specimens by electrochemical anodization and annealed them under a H2 atmosphere. Then, SiGe thin films were grown by gas-source molecular beam epitaxy. We observed the microstructure of the specimens using transmission electron microscopy. The result showed that we succeeded in producing a single-crys- tal continuous Si0.73Ge0.27 film with a 10% relaxation ratio and a low dislocation density on porous Si.
Reduction of Dislocation Densities of Ge Layers Grown on Si Substrates by Using Microwave Plasma Heating and Fabrication of High Hole Mobility MOSFETs on Ge Layers  [PDF]
Hiroki Nakaie, Tetsuji Arai, Chiaya Yamamoto, Keisuke Arimoto, Junji Yamanaka, Kiyokazu Nakagawa, Toshiyuki Takamatsu
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.51006
We have developed a microwave plasma heating technique to rapidly heat the transition metal. W/SiO2 layers were deposited on Ge/Si heterostructures. By heating the W, dislocations in Ge layers originated from lattice mismatch between Ge and Si crystals were reduced drastically. We have fabricated p- MOSFETs on Ge/Si substrates and realized higher mobility of about 380 cm2/ Vs than that of Si p-MOSFET.
STEM Moiré Observation of Lattice-Relaxed Germanium Grown on Silicon  [PDF]
Junji Yamanaka, Chiaya Yamamoto, Hiroki Nakaie, Tetsuji Arai, Keisuke Arimoto, Kosuke O. Hara, Kiyokazu Nakagawa
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.51014
We deposited Ge films on Si substrates by molecular beam epitaxy (MBE) method. The specimens were annealed at around 750 C using microwave- plasma heating technique which we had reported before. After these pro- cesses, we carried out special scanning transmission electron microscopic (STEM) observation. The moiré between the crystal lattices and the scanning lines controlled by STEM was utilized to show lattice-spacing distribution. The results exhibited that we were succeeded in forming lattice-relaxed Ge thin films. It was also recognized that this STEM moiré technique is very useful to observe lattice-spacing distribution for large area with high resolution.
Surface Roughness of SiGe/Si(110) Formed by Stress-Induced Twins and the Solution to Produce Smooth Surface  [PDF]
Junji Yamanaka, Mai Shirakura, Chiaya Yamamoto, Naoto Utsuyama, Kei Sato, Takane Yamada, Kosuke O. Hara, Keisuke Arimoto, Kiyokazu Nakagawa
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.61004
Lattice-strained Si thin films grown onto SiGe(110)/Si(110) are attracting because of their potential to realize high-speed transistors. In this study we observe surface morphology of Si/SiGe/Si(110) using scanning electron microscopy and we also observe microstructure of the identical position using cross-sectional transmission electron microscopy. These results reveal that crossing of stress-induced twins causes remarkable surface roughness. We propose using vicinal substrate to avoid this phenomenon and our successive experimental results are shown in this paper.
Ohmic Contact Formation for n+4H-SiC Substrate by Selective Heating Method Using Hydrogen Radical Irradiation  [PDF]
Tetsuji Arai, Kazuki Kamimura, Chiaya Yamamoto, Mai Shirakura, Keisuke Arimoto, Junji Yamanaka, Kiyokazu Nakagawa, Toshiyuki Takamatsu, Masaaki Ogino, Masaaki Tachioka, Haruo Nakazawa
Journal of Materials Science and Chemical Engineering (MSCE) , 2017, DOI: 10.4236/msce.2017.51005
We developed an apparatus for producing high-density hydrogen plasma. We confirmed that the temperatures of transition-metal films increased to above 800?C within 5 s when they were exposed to hydrogen plasma formed using the apparatus. We applied this phenomenon to the selective heat treatment of W/Ni films deposited on n+4H-SiC wafers and formed nickel silicide electrodes. To utilize this method, we can perform the nickel silicidation process without heating the other areas such as channel regions and improve the reliability.
Dilemmas Faced by Nurses Regarding the Physical Restraint of Elderly Patients with Dementia in Japan  [PDF]
Miwa Yamamoto
International Journal of Clinical Medicine (IJCM) , 2011, DOI: 10.4236/ijcm.2011.25099
Abstract: This study aimed to clarify the dilemma of nurses working in general wards who face the ethical dilemma of restraining older people with dementia in Midwestern Japan. The study used the questionnaire method with an independently prepared questionnaire. The questionnaire was designed to ensure privacy and anonymity. The privacy and anonymity of study participants was assured. Of the 340 survey questionnaires distributed, 291 (85.6%) completed surveys were eligible number (12 additional surveys were returned without answers). An explanatory factor analysis revealed four dilemma factors among 15 items investigated (KMO value 0.84). These were: factor 1: “Execution of treatment and security,” α = 0.91; factor 2: “approach in the nursing of older people with dementia,” α = 0.93; factor 3: “A cooperative relationship in nursing of older people with dementia,” α = 0.87; and factor 4: “Priorities in nursing,” α = 0.81. The cumulative contribution ratio was 79.1%. We suggest that the program would enable nurses to cope with these dilemmas.
The effects of ethical dilemmas regarding the use of physical restraints in eldercare on female nurses who care for their relatives in Japan  [PDF]
Miwa Yamamoto
Open Journal of Nursing (OJN) , 2012, DOI: 10.4236/ojn.2012.22006
Abstract: Purpose: This study sought to clarify the relationship between a nurse’s exposure to elderly relatives and their perspective in using restraints on the elderly in health care situations. Methods: We approached nursing staff supervisors at 17 general hospital wards and explained the objectives of the study. Supervisors at 14 hospitals agreed to participate, giving us a sampling pool of 1929 nurses. We used a chi square test to compare nurses who had spent time with elderly relatives and those who had not on several variables related to using restraints on elderly patients. Results and Conclusion: This study found that nurses who live with elderly family members were significantly more likely to believe that restraints cause diseases (including chronic diseases) based on a chi square test (p < 0.05). Therefore it would be important that essential was the experiences of individuals with elderly family members when making programs of decreasing nurse’s dilemma to restraining the elderly.
GIS-Based Urbanization Prediction Model Considering Neighborhood Relationship of the Unit of the “Block” in the Outskirts of Metropolitan Area  [PDF]
Kayoko Yamamoto
Journal of Geographic Information System (JGIS) , 2014, DOI: 10.4236/jgis.2014.64030

On the outskirts of the metropolitan areas in Japan, the rapid development of urban areas and the improvement in transportation networks have brought various land use problems in their wake, including urban diffusion and the phenomenon of urban sprawl. There is a strong need for accurate predictions of land-use change and future urbanization, as well as investigation of the appropriateness of present land use controls and the land use controls that will be required in the future. This study took as its object the outskirts of the Keihanshin (Kyoto-Osaka-Kobe) Metropolitan Area, the second largest conurbation in Japan after the Tokyo Metropolitan Area, and used the digital maps and spatial analysis offered by GIS. It aimed to: 1) describe the characteristics of land use controls, land use and urbanization; 2) develop an urbanization prediction model that considers the neighboring relationship of neighboring areas on a 100 m mesh unit; 3) apply this model to the study area and verify its validity regarding the conditions of present land use; 4) compare urbanization prediction results by this model with the present land use controls; and 5) make predictions for future urbanization and propose remedial measures for future land use controls.

Donepezil rescues the medial septum cholinergic neurons via nicotinic ACh receptor stimulation in olfactory bulbectomized mice  [PDF]
Yui Yamamoto, Kohji Fukunaga
Advances in Alzheimer's Disease (AAD) , 2013, DOI: 10.4236/aad.2013.24021
Abstract: Olfactory bulbectomy (OBX) causes cognitive dysfunction by degeneration of cholinergic neurons in the medial septum. Here, we define an involvement of nicotinic acetylcholine receptor (nAChR) in neuroprotective effect of donepezil in the septum neurons of OBX mice. Neuroprotective effects on the medial septal cholinergic neurons were assessed after chronic donepezil administration in OBX mice. We also measured Akt and ERK phosphorylation to define the neuroprotective mechanism of donepezil. We found that treatment with donepezil (1 - 3 mg/kg) for 15 consecutive days completely rescued cholinergic neurons in the OBX mice with concomitant improved memory. Reduction of both protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) phosphorylation were restored by chronic donepezil administration (1 - 3 mg/kg) in OBX mouse medial septum. Both phosphorylated Akt and ERK immunoreactivities were localized in cell bodies of choline acetyltransferase (ChAT)-positive cholinergic cells in the medial septum. Enhancement of Akt and ERK phosphorylation seen following donepezil administration was totally blocked by pre-administration of mecamylamine (10 μM), a nicotinic acetylcholine receptor antagonist. Donepezil increases phosphorylation of Akt and ERK via nAChR stimulation in the medial septum cholinergic neurons. The Akt and ERK stimulation by donepezil is associated with its ability of neuroprotection in the medial septum and memory improvement.
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