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Search Results: 1 - 10 of 3800 matches for " Yusuke Kobayashi "
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Effect of Acidic Catalyst on Properties of Novel Conductive Copolymer Films Made of Pyrrole and Formyl Pyrrole  [PDF]
Yusuke Hoshina, Takaomi Kobayashi
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.43018
Abstract: Effect of acidic catalysis having carboxylic acid group was studied on properties of conductive copolymer films made of pyrrole (Py) and 2-formyl pyrrole (FPy). It was noted that trifluoroacetic acid (TFA) and trichloroacetic acid (TCA) were suitable for the preparation of copolymer films, which showed good properties in its strength and electrical conductivity of the copolymer films. When the concentration of TFA or TCA was increased in the monomer feed, the copolymerization yield became higher and the obtained films showed electrical conductivity in the range of 10–4 - 10–3 S/cm. FT-IR and UV-Vis spectra confirmed the formation of conjugate chemical structure in the copolymer film.
Fence patrolling by mobile agents with distinct speeds
Akitoshi Kawamura,Yusuke Kobayashi
Computer Science , 2014, DOI: 10.1007/s00446-014-0226-3
Abstract: Suppose we want to patrol a fence (line segment) using k mobile agents with given speeds v_1, ..., v_k so that every point on the fence is visited by an agent at least once in every unit time period. Czyzowicz et al. conjectured that the maximum length of the fence that can be patrolled is (v_1 + ... + v_k)/2, which is achieved by the simple strategy where each agent i moves back and forth in a segment of length v_i/2. We disprove this conjecture by a counterexample involving k = 6 agents. We also show that the conjecture is true for k = 2, 3.
Modified Ross Procedure for a Young Woman with a Root Abscess on a Bicuspid Aortic Valve: Report of a Case  [PDF]
Yusuke Misumi, Tomoyuki Fujita, Yusuke Shimahara, Hiroki Hata, Soichiro Kitamura, Junjiro Kobayashi
World Journal of Cardiovascular Diseases (WJCD) , 2015, DOI: 10.4236/wjcd.2015.58022
Abstract: A 19-year-old woman with a bicuspid aortic valve was admitted because of active infective endocarditis with a root abscess. Four weeks of antibiotic therapy achieved negative blood cultures and normalized inflammatory signs; however, echocardiography revealed severe aortic regurgitation through an abscess cavity located at the root. The modified Ross procedure, in which the pulmonary autograft was reinforced with a prosthetic graft to prevent postoperative annular dilation, was successfully performed. The postoperative clinical course was uneventful, and echocardiography performed at 1 year showed trivial aortic regurgitation. Selection of homograft may benefit young woman who wishes to bear children, and covering pulmonary autograft by a prosthetic graft in order to prevent annular dilatation of autograft in patient with bicuspid aortic valve, may be allowed only under negative infection sign.
Influence of the period between onset of IgA nephropathy and medical intervention on renal prognosis  [PDF]
Keiko Okazaki,, Yusuke Suzuki, Takashi Kobayashi, Fumiko Kodama, Satoshi Horikoshi, Yasuhiko Tomino
Health (Health) , 2011, DOI: 10.4236/health.2011.38086
Abstract: Background. The clinical course of IgA nephropathy (IgAN) is highly variable. In order to verify the necessity of early medical intervention in IgAN patients, the present study investigated the clinical impact of the duration between disease onset and first medical intervention on renal prognosis. Methods. We enrolled 57 patients diagnosed with IgAN on the basis of biopsy performed at our hospital. The medical records of these patients were traceable to the last 10 years, during which they had not undergone dialysis or treatment at any other hospital. On the basis of histological assessment of prognosis, these patients were classified according to the Japanese guidelines into the following groups: groups I, good prognosis; group II, relatively good prognosis; group III, relatively poor prognosis; and group IV, poor prognosis. We investigated the correlation between the duration of disease onset and the first consultation with a nephrologist and the rate of increase in serum creatinine over a 10 year period. In addition to the abovementioned patients, 6 patients with IgAN who underwent dialysis within the 10 years were separately evaluated. These patients came under the poor prognosis category; i.e., they belonged to group IV. Results. The duration between disease onset and medical consultation was significantly longer in younger patients or in those with asymptomatic proteinuria at onset when compared to that in older patients or in those with other urinary abnormalities. There was a significant correla tion between this duration and renal prognosis, particularly in group III patients. Although the duration between onset and consultation was not correlated to the serum creatinine level at the time of first medical intervention, urinary protein level among group IV patients at the time of first consultation was significantly higher in patients with dialysis than that in those without dialysis. Conclusions. Early medical intervention may lead to a better renal prognosis, particularly in group III patients, who form a major portion of the IgAN population. It therefore appears that early diagnostic screening and subsequent intervention are important for a good prognosis in IgAN patients.
Gynecological tumors in patients with Peutz-Jeghers syndrome (PJS)  [PDF]
Arisa Ueki, Iori Kisu, Kouji Banno, Megumi Yanokura, Kennta Masuda, Yusuke Kobayashi, Akira Hirasawa, Daisuke Aoki
Open Journal of Genetics (OJGen) , 2011, DOI: 10.4236/ojgen.2011.13012
Abstract: Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder characterized by the development of hamartomatous polyposis in the gastrointestinal tract and melanin-pigmented macules on the skin mucosa. The responsible gene is a tumor suppressor, STK11/LKB1, on chromosome 19p13.3. PJS complicates with benign and malignant tumors in various organs. In gynecology, there has been a particular focus on complications of PJS with sex cord tumor with annular tubules (SCTAT) and minimal deviation adenocarcinoma (MDA), which are rare diseases. Approximately 36% of patients with SCTAT are complicated with PJS and these patients are characterized by multifocal, bilateral, small and benign lesions that develop into tumors with mucinous to serous ratios of 8:1. In addition, 10% of cases of MDA are complicated with PJS and mutation of STK11, the gene responsible for PJS, has a major effect on onset and prognosis. The disease concept of lobular endocervical glandular hyper-plasia (LEGH) has recently been proposed and LEGH is thought to be a potential premalignant lesion of MDA, however, the relationship between PJS and LEGH remains unclear. Several case reports of PJS patients complicated with gynecological tumors have been published and further studies are needed to determine the underlying causes
Investigation of VEGF and PDGF signals in vascular formation by 3D culture models using mouse ES cells  [PDF]
Hitomi Hosoe, Yuri Yamamoto, Yusuke Tanaka, Mami Kobayashi, Nana Ninagawa, Shigeko Torihashi
Stem Cell Discovery (SCD) , 2012, DOI: 10.4236/scd.2012.22011
Abstract: Vascular formation in vivo involves several processes and signal cascades subsequently occurring in the embryo. Several models by ES cells have been reported for analysis in vitro. We show here a 3D culture system using collagen gel (AteloCell) as a simple and useful system for investigating vascular formations and analyzing the roles of factors in vivo. Although VEGF and PDGF are growth factors with multi-potentials for vascular formation, their sequential roles have not been elucidated. We investigated the effects of VEGF and PDGF B signals for vascular formation by a 3D culture system that embedded embryoid bodies (EBs) from ES cells into a collagen gel. After embedding EBs in the collagen gel with a medium containing VEGF, EBs gave off CD105 immunopositive vessels as the initial step of vasculogenesis. When the factor in the culture medium for EBs was switched from VEGF to PDGF B after 5 days of culture, the morphological features of vessels varied, suggesting the occurrence of vascular-type differentiation. After 11 days of 3D culture, vessels in both groups cultured with VEGF alone and switching to VEGF B at day 5 showed Flk-1 immunoreactivity. Some blood vessels cultured with PDGF B after day 5 expressed either EphrinB2 (arteriole marker) or Flt-4 (lymphatic marker) immunoreactivity, but vessels cultured with VEGF alone exhibited neither of them. Vessels cultured with these two factors could not differentiate into a venous type. The present study indicates that VEGF is the initial signal for vasculogenesis, and that PDGF B is probably involved in vascular diversification.
N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters
Takuya Uno,Yusuke Kobayashi,Yoshiji Takemoto
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.169
Abstract: An efficient catalytic synthesis of α-amino-β-keto esters has been newly developed. Cross-coupling of various aldehydes with α-imino ester, catalyzed by N-heterocyclic carbene, leads chemoselectively to α-amino-β-keto esters in moderate to good yields with high atom efficiency. The reaction mechanism is discussed, and it is proposed that the α-amino-β-keto esters are formed under thermodynamic control.
ALMA imaging study of methyl formate (HCOOCH$_{3}$) in the torsionally excited states towards Orion KL
Yusuke Sakai,Kaori Kobayashi,Tomoya Hirota
Physics , 2015, DOI: 10.1088/0004-637X/803/2/97
Abstract: We recently reported the first identification of rotational transitions of methyl formate (HCOOCH$_{3}$) in the second torsionally excited state toward Orion Kleinmann-Low (KL) observed with the Nobeyama 45 m telescope. In combination with the identified transitions of methyl formate in the ground state and the first torsional excited state, it was found that there is a difference in rotational temperature and vibrational temperature, where the latter is higher. In this study, high spatial resolution analysis by using Atacama Large Millimeter/Submillimeter Array (ALMA) science verification data was carried out to verify and understand this difference. Toward the Compact Ridge, two different velocity components at 7.3 and 9.1 km s$^{-1}$ were confirmed, while a single component at 7.3 km s$^{-1}$ was identified towards the Hot Core. The intensity maps in the ground, first, and second torsional excited states have quite similar distributions. Using extensive ALMA data, we determined the rotational and vibrational temperatures for the Compact Ridge and Hot Core by the conventional rotation diagram method. The rotational temperature and vibrational temperatures agree for the Hot Core and for one component of the Compact Ridge. At the 7.3 km s$^{-1}$ velocity component for the Compact Ridge, the rotational temperature was found to be higher than the vibrational temperature. This is different from what we obtained from the results by using the single-dish observation. The difference might be explained by the beam dilution effect of the single-dish data and/or the smaller number of observed transitions within the limited range of energy levels ($\leq$30 K) of $E_u$ in the previous study.
Role of charge fluctuation in Q1D organic superconductor (TMTSF)2ClO4
Yusuke Mizuno,Akito Kobayashi,Yoshikazu Suzumura
Physics , 2010, DOI: 10.1016/j.physc.2010.11.008
Abstract: We have theoretically investigated the spin and charge fluctuations in the quasi-one dimensional organic superconductor (TMTSF)2ClO4. Using the extended multi-site Hubbard model, which contains four sites in a unit cell and the transfer energies obtained by the extended H\"uckel method, we calculate the linearized gap equation with the random phase approximation, to find novel order parameters of superconductivity due to several kinds of charge fluctuations induced by the anisotropic intersite repulsive interactions. For the singlet state, the order parameter with line nodes appears in the case of the strong charge fluctuation, while the order parameter with anisotropic gap suggested by Shimahara is reproduced in the spin fluctuation. The triplet state is also obtained for the wide parameter range of repulsive interactions due to a cooperation between charge and spin fluctuations.
Morphology Observation of Novel 3, 4-Bis-Alkyloxycarbonyl-Hexanedioic Acid Monolayer on Water Surface by Dropping Method  [PDF]
Yusuke Kobayashi, Rina Hirai, Daiki Ito, Yasushi Yamamoto, Keijiro Taga, Zameer Shervani
Journal of Biophysical Chemistry (JBPC) , 2016, DOI: 10.4236/jbpc.2016.72004
Abstract: We have investigated the morphology of novel 3, 4-bis-alkyloxycarbonyl-hexanedioic acid monolayer (alkyl chain number n = 12, 14, and 16) formed on the water surface by dropping method using Surface Tension measurement (STm) and Brewster Angle Microscopy (BAM). Surfactant of 3, 4-bis-alkyloxycarbonyl-hexanedioic acid has a gemini type structure. π-A isotherm curves (STm) of two gemini surfactants of n = 12 and 14 showed gradual increase in surface pressure, while that of n = 16 showed gradual increase, a stagnant range and finally steep increase. BAM observation showed each image corresponding to the result of STm measurement. From STm and BAM results of surfactants, it is found that surfactant of n = 12 and 14 form Liquid-Expand (LE) type monolayer, while that of n = 16 formed Liquid-Condensed (LC) type monolayer including LE-LC phase transition.
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