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Search Results: 1 - 10 of 829 matches for " Tetsuji Arai "
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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
Abstract:
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
Abstract:
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.
Formation of Poly-Si Films on Glass Substrates by Using Microwave Plasma Heating and Fabrication of TFT’s on the Films  [PDF]
Hiroki Nakaie, Tetsuji Arai, Keisuke Arimoto, Junji Yamanaka, Kiyokazu Nakagawa, Kazuki Kamimura, Toshiyuki Takamatsu
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.61003
Abstract:
We have developed an apparatus for producing high-density hydrogen plasma. The atomic hydrogen density was 3.0 × 1021 m?3 at a pressure of 30 Pa, a microwave power of 1000 W, and a hydrogen gas flow rate of 5 sccm. We confirmed that the temperatures of tungsten films increased to above 1000?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 tungsten films deposited on amorphous silicon films on glass substrates and formed polycrystalline silicon films. To utilize this method, we can perform the crystalline process only on device regions. TFTs were fabricated on the polycrystalline silicon films and the electron mobilities of 60 cm2/Vs were obtained.
Synthesis and Molecular Structure of Chiral (2S, 5S)-tert-Butyl 3-Oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate
Tetsuji Moriguchi,Suvratha Krishnamurthy,Toru Arai,Akihiko Tsuge
Journal of Crystallography , 2014, DOI: 10.1155/2014/150796
Abstract: The title compound (2S, 5S)-tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate was synthesized as a chiral cyclic amino acid ester from the corresponding cis- and trans-5-hydroxypipecolic acid ethyl esters via an intramolecular lactonization reaction without using chiral catalyst or enzyme and without separation by chiral column chromatography. The chiral compound was characterized using 1H NMR spectroscopy and high-resolution mass spectrometry. Its exact structure was then determined via single crystal X-ray diffraction analysis of a single crystal obtained after recrystallization of the compound from ethyl acetate/diethyl ether. The crystal was found to be of the orthorhombic space group P212121 (No. 19, noncentrosymmetric, chiral) with ??, ??, ??, 4?g/cm3, and a Flack parameter of 0.0(5) at 90?K. The compound has a bicyclo[2.2.2]octane structure comprised of lactone and piperidine groups. 1. Introduction Hydroxypipecolic acid (5-hydroxy-2-piperidinecarboxylic acid) is a six-membered homologue of 4-hydroxyproline found in some natural plants, such as date and acacia trees, whereas 4-hydroxyproline is found in animals (collagen) [1, 2]. Several hydroxypipecolic acid derivatives have been synthesized via intramolecular reactions of precursors functionalized with epoxide groups [3–5]. However, a diastereomeric mixture of cis- and trans-5-hydroxymethylpipecolic acids has generally been obtained, and in some cases, the formation of undesired 5-hydroxymethylprolines has also been noted [4–6]. Because the intramolecular reaction of epoxide precursors suffers from the formation of stereo- and regioisomers, a straightforward method for the preparation, isolation, and characterization of the pure single enantiomers of hydroxypipecolic acid and derivatives of this rare amino acid is required. Previously, we synthesized a 4-hydroxyproline derivative from an amino acid bearing an epoxide [7]. During this study, we observed that the cis isomer underwent intramolecular lactonization. In addition, we reported the crystal structure of “racemic” tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.1]heptane-5-carboxylate prepared using an alternative synthetic pathway [8]. Based on these previous results, it was expected that cis-5-hydroxypipecolic acids would also undergo intramolecular lactonization, while the corresponding trans isomers would not. Indeed, when a mixture of a cis- and trans-5-hydroxypipecolic acid derivative was reacted under acidic conditions, the cis isomer was successfully converted to the lactone (2S, 5S)-tert-butyl
Selective Heating of Transition Metal Usings Hydrogen Plasma and Its Application to Formation of Nickel Silicide Electrodes for Silicon Ultralarge-Scale Integration Devices  [PDF]
Tetsuji Arai, Hiroki Nakaie, Kazuki Kamimura, Hiroyuki Nakamura, Satoshi Ariizumi, Satoki Ashizawa, Keisuke Arimoto, Junji Yamanaka, Tetsuya Sato, Kiyokazu Nakagawa, Toshiyuki Takamatsu
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.41006
Abstract:

We developed an apparatus for producing high-density hydrogen plasma. The atomic hydrogen density was 3.1 × 1021 m?3 at a pressure of 30 Pa, a microwave power of 1000 W, and a hydrogen gas flow rate of 10 sccm. We confirmed that the temperatures of transition-metal films increased to above 800C within 5 s when they were exposed to hydrogen plasma formed using the apparatus. We applied this phenomenon to the selective heat treatment of nickel films deposited on silicon wafers and formed nickel silicide electrodes. We found that this heat phenomenon automatically stopped after the nickel slicidation reaction finished. To utilize this method, we can perform the nickel silicidation process without heating the other areas such as channel regions and improve the reliability of silicon ultralarge-scale integration devices.

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
Abstract:
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.
Studies on mitochondrial macromolecular syntheses in various organs of aging animals labeled with 3H-precursors as revealed by electron microscopic radioautography  [PDF]
Tetsuji Nagata
Advances in Bioscience and Biotechnology (ABB) , 2010, DOI: 10.4236/abb.2010.14034
Abstract: In order to study the aging changes of intramitochondrial macromolecular synthesis in various organs of aging animals during the development and aging, 10 groups of developing and aging mice, each consisting of 3 individuals, total 30, from fetal day 19 to postnatal newborn at day 1, 3, 9, 14 and adult at month 1, 2, 6, 12 to 24 were injected with 3H-thymidine a DNA precurson, another 10 groups consisting of 3 individuals, total 30, were injected with 3H-uridine a RNA precursor, and another 10 groups of 30 individuals were injected with 3H-leucine a protein precursor, total 90 individuals. Then, all the animals were sacrificed 1 hr after the injections and the liver tissues, the lung tissues, the kidney tissues, the testis and ovary tissues, the adrenal tissues were taken out, fixed and processed for electron microscopic radioautography. On electron microscopic radioautograms obtained from each animal, ten photographs in respective groups, numbers of mitochondria per cell profile area, numbers of labeled mitochondria per cell and the mitochondrial labeling index (LI) labeled with 3H-thymidine showing DNA synthesis, LI labeled with 3H-uridine showing RNA synthesis, and LI labeled with 3H-leucine showing protein synthesis, in various organs, were counted and the results in various organs in respective aging groups were compared, respectively. From the results, it was demonstrated that the numbers of mitochondria in hepatocytes as well as in 3 zones of the adrenal cortex, the zona glomerulosa, fasciculata and reticularis of mice at various ages increased from fetal day 19 to postnatal month 1 due to development and aging of animals. On the other hand, the numbers of labeled mitochondria and the labeling indices of intramitochondrial DNA syntheses incorporating 3H-thymidine in hepatocytes and 3 zones of cortical cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. The numbers of labeled mitochondria and the labeling indices of intramitochondrial RNA syntheses incorporating 3H-uridine in hepatocytes and 3 zones of cortical cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. The numbers of labeled mitochondria and the labeling indices of intramitochondrial RNA syntheses incorporating 3H-uridine in hepatocytes and 3 ones of cortical cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. Moreover, some other organs such as the lung and the testis were also review and discussed. From the results, it was shown that the activity of intramitochnodrial DNA synthesis, RNA synthesis,
Electron microscopic radioautographic study on mitochondrial RNA synthesis in adrenal cortical and medullary cells of aging mice  [PDF]
Tetsuji Nagata
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.43031
Abstract: In order to study the aging changes of intramito-chondrial RNA synthesis of mouse adrenal cells, 10 groups of developing and aging mice, each consisting of 3 individuals, total 30, from fetal day 19 to postna-tal newborn at day 1, 3, 9, 14, adult at month 1, 2, 6 and senescent animals at month 12 (year 1) and 24 (year 2) were injected with 3H-uridine, an RNA pre-cursor, sacrificed 1 hr later and the adrenal tissues were fixed and processed for electron microscopic radioautography. On electron microscopic radio-autograms obtained from each animal, the number of mitochondria per cell, the number of labeled mito-chondria with 3H-uridine showing RNA synthesis per cell and the mitochondrial labeling index in each adreno-cortical cells, in 3 zones, as well as in each adreno-medullary cells, 2 types of cells in the medulla, the adrenalin cells and the noradrenalin cells, were calculated and the results in respective aging groups were compared with each others. The results demon-strated that the number of mitochondria in adreno-cortical cells in 3 zones, the zona glomerulosa, fasciculata and reticularis of respective mice at vari-ous ages increased from fetal day 19 to postnatal month 1 reaching the plateau from month 1 to 24 due to development and aging of animals, respectively, while the number of labeled mitochondria per cell and the labeling index of intramitochondrial RNA synthesis incorporating 3H-uridine increased from fetal day 19 to postnatal month 2, reaching the maxima and decreased slightly from month 6 to month 24. On the other hand, the number of mito-chondria per cell in the medulla increased from fetal day 19 to postnatal month 1 reaching the plateau from month 1 to 24, while the number of labeled mi-tochondria per cell and the labeling index of in-tramitochondrial RNA synthesis increased from fetal day 19 to postnatal day 14, reaching the maxima and decreased from month 1 to 24. From the results, it was demonstrated that the activity of intramitochno-drial RNA synthesis in both the cortical and me-dullary cells in developing and aging mice adrenals changed due to aging of individual animals.
Synthesis and Molecular Structure of tert-Butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate
Tetsuji Moriguchi,Suvratha Krishnamurthy,Toru Arai,Taisuke Matsumoto,Koji Araki,Akihiko Tsuge,Norikazu Nishino
Journal of Crystallography , 2014, DOI: 10.1155/2014/645079
Abstract: The compound tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate was synthesized as a cyclic amino acid ester from the corresponding ethyl 2-amino-4-(2-oxiranyl)butanoate HCl salt via an intramolecular lactonization reaction and was characterized by using 1H NMR spectroscopy and high-resolution mass spectrometry. The product was then recrystallized from dichloromethane/diethyl ether and its structure was determined via single crystal X-ray diffraction analysis. The crystal was found to be of the monoclinic space group P21/c (no. 14) with ??, ??, ??, β = 114.186(13)°, and = 1.350?g/cm3 at 123?K. The compound has bicyclo[2.2.2]octane structure including a lactone moiety and a piperidine ring, and the two diastereomers of the molecules are present in a 1?:?1 ratio in the crystal. 1. Introduction The compound hydroxypipecolic acid (5-hydroxy-2-piperidinecarboxylic acid) is a six-membered homologue of 4-hydroxyproline. Hydroxypipecolic acid is found in some natural plants such as date and acacia trees, whereas 4-hydroxyproline is found in animals (collagen) [1, 2]. Several hydroxypipecolic acid derivatives have been synthesized via the intramolecular reactions of precursors functionalized with epoxide groups [3–5]. Generally, a diastereomeric mixture of cis- and trans-5-hydroxymethylpipecolic acids has been obtained. The formation of 5-hydroxymethylprolines along with the desired 5-hydroxypipecolic acids has also been noted [4–6]. The intramolecular reaction from epoxide precursor suffers the formation of both stereoisomers (cis and trans) and regioisomers (pipecolic acid and proline). The synthetic reports so far seem to be confused because of the formation of many products. The straightforward method to isolate this rare amino acid, hydroxypipecolic acid, is still desired with a clear compound characterization. Previously, we synthesized a 4-hydroxyproline derivative from an amino acid bearing epoxide [7]. During this study, we observed that the cis isomer underwent intramolecular lactonization. Then, the product lactone, tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.1]heptane-5-carboxylate, was isolated from the trans ester with ease. It was expected that cis-5-hydroxypipecolic acids would also undergo intramolecular lactonization, whereas the trans isomers would not. Indeed, when a mixture of cis- and trans-5-hydroxypipecolic acids derivatives reacted under acidic conditions, the cis isomer was successfully converted to the lactone, tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate, which was readily separated from the remaining
Comparative Analysis of the Heptahelical Transmembrane Bundles of G Protein-Coupled Receptors
Tetsuji Okada
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035802
Abstract: Background G protein-coupled receptors represent a large family of eukaryotic membrane proteins, and are involved in almost all physiological processes in humans. Recent advances in the crystallographic study of these receptors enable a detailed comparative analysis of the commonly shared heptahelical transmembrane bundle. Systematic comparison of the bundles from a variety of receptors is indispensable for understanding not only of the structural diversification optimized for the binding of respective ligands but also of the structural conservation required for the common mechanism of activation accompanying the interaction changes among the seven helices. Methodology/Principal Findings We have examined the bundles of 94 polypeptide chains from almost all available structures of 11 receptors, which we classified into either inactivated chain or activated chain, based on the type of bound ligand. For the inactivated chains, superposition of 200 residue bundles by secondary structure matching demonstrated that the bound ligands share a laterally limited cavity in the extracellular section of the bundle. Furthermore, a distinct feature was found for helix III of bovine rhodopsin, which might have evolved to lower its activity in the presence of 11-cis-retinal, to a level that other receptors could hardly achieve with any currently available ligands. Conclusions/Significance Systematic analysis described here would be valuable for understanding of the rearrangement of seven helices which depends on the ligand specificity and activation state of the receptors.
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