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Search Results: 1 - 10 of 1918 matches for " Yuki Sakamoto "
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Performance of Thermal Energy Storage Unit Using Solid Ammoniated Salt (CaCl2-NH3 System)  [PDF]
Yuki Sakamoto, Hideki Yamamoto
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.58031
The exothermic chemical reaction of CaCl2 (calcium chloride) with NH3 (ammonia) can be utilized as an energy storage system. Since this reaction is a typical gas-solid reaction, the reaction rate is controlled by the heat transfer rate. In order to improve the low heat transfer rate of the ammoniation and the deammoniation of CaCl2, the influence of a heat transfer media (Ti: titanium) on the heat transfer rate of the solid ammoniated salt (CaCl2.mNH3) was studied and tested experimentally. The performance tests were carried out under the conditions of various weight ratios of Ti. No decrease of the activation of chemical reaction and no corrosion of experimental apparatus were observed on the repeated runs (≥30 times each). The heat transfer rate of ammoniated salt was greatly improved by adding Ti under the constant pressure (0.5 MPa). The reaction time required for the ammoniation of CaCl2 mixed with Ti was approximately 16% - 54% shorter than that of CaCl2 alone, and the reaction time required for the deammoniation was also approximately 19% - 59% shorter than that of CaCl2 alone.
Measurement of Thermophysical Property of Energy Storage System (CaCl2.NH3 System)  [PDF]
Yuki Sakamoto, Hideki Yamamoto
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.512060
Abstract: In order to measure the thermophysical properties of ammoniated salt (CaCl2.mNH3: m = 4, 8) as an energy storage system utilizing natural resources, the measurement unit was developed, and the thermophysical properties (effective thermal conductivity and thermal diffusivity) of CaCl2.mNH3 and CaCl2.mNH3 with heat transfer media (Ti: titanium) were measured by the any heating method. The effective thermal conductivities of CaCl2.4NH3 + Ti and CaCl2.8NH3 + Ti were 0.14 - 0.17 and 0.18 - 0.20 W/(m.K) in the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.5 - 2.2 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The effective thermal diffusivities were 0.22 - 0.24 × 10-6 and 0.18 - 0.19 × 10-6 m2/sin the measuring temperature range of 290 - 350 K, respectively, and these values were approximately 1.3 - 1.5 times larger than those of CaCl2.4NH3 and CaCl2.8NH3. The obtained results show that the thermophysical properties have a dependence on the bulk densities and specific heats of CaCl2.mNH3 and
Carbon Footprint of Recycling Service in Waste Treatment: Used Beverage Cans and Waste Papers  [PDF]
Yuki Sakamoto, Zenzo Ishii, Shinichi Sato, Eiichi Yoshida
Natural Resources (NR) , 2017, DOI: 10.4236/nr.2017.89037
Abstract: There are very few studies of the Carbon Footprint of Products (CFPs) in the service sector (e.g. transport and waste treatment) in comparison with those of industrial products and farm products. In this study, the CFPs of the recycling services of used beverage cans (aluminum and steel) and waste papers (cardboard, magazine and newspaper) in waste treatment were estimated as a first trial model of the service sector. Regarding the CFPs of whole life cycle of the recycling services, the amounts of CO2-equivalent (CO2e) greenhouse gas (GHG) emissions from the collection and transportation process were the largest in all recycling cases. The reason that the collection and transportation process emits the largest amounts of GHG emissions is that the collection vehicles (trucks) consume the large amounts of diesel fuel. Regarding the CFPs of the capital equipment, the amounts of GHG emissions from the capital equipment were the second largest in all recycling cases. It was found that the percentages of amounts of GHG emissions from the capital equipment in the recycling services were larger than those of industrial products and farm products.
A Pregnant Patient with Aortic Regurgitation and Symptoms of Acute Heart Failure Caused by Peripartum Cardiomyopathy: A Case Report  [PDF]
Keisuke Mori, Jun Shimizu, Yuki Takahashi, Tatsuro Otsuki, Yuko Furuichi, Atsuhiro Sakamoto
Open Journal of Anesthesiology (OJAnes) , 2017, DOI: 10.4236/ojanes.2017.76016
Abstract: Introduction: Knowledge of the risks of pregnancy with heart disease is important because the maternal mortality is much higher than the average. Peripartum cardiomyopathy (PPCM) is rare but it is one of major causes of maternal death. We experienced a pregnant patient with severe aortic regurgitation (AR) presented symptoms of acute heart failure. Her heart failure was not better after an emergency cesarean section and aortic valve replacement (AVR) therefore we think that PPCM caused her heart failure. Case presentation: A 35-year-old woman diagnosed as having severe AR became pregnant. No changes in the AR were apparent during pregnancy. However, the patient developed symptoms of acute heart failure at 37 weeks of gestation, and an emergency cesarean section was performed under general anesthesia. Her hemodynamic status worsened after the cesarean section, and AVR was performed. She was supported with percutaneous cardiopulmonary support (PCPS) after the operation. As recovery seemed to take longer than usual, we decided to implant a ventricular assist device (VAD). Her condition improved after VAD placement, but then she died from a cerebral infarction. In this case, the heart failure was an acute-onset even though AR was stable before and after the pregnancy, and the heart failure did not improve after AVR. Therefore, we concluded that PPCM, rather than AR caused her heart failure. Conclusions: We encountered a case of a pregnant patient with severe AR who presented with symptoms of acute heart failure caused by PPCM. The effect of AR to her heart failure could not be easily denied. This delayed the diagnosis of PPCM, which in turn delayed our decision to use a VAD. Therefore, PPCM should be considered when pregnant patients with heart disease present symptoms of heart failure.
Quantitative Assessment of Air Trapping Using Inspiratory and Expiratory Low-Dose Computed Tomography  [PDF]
Yuki Saito, Shin Matsuoka, Tsuneo Yamashiro, Shoichiro Matsushita, Akiyuki Kotoku, Kunihiro Yagihashi, Hayato Tomita, Shingo Sakamoto, Shinji Saruya, Yasuo Nakajima
Open Journal of Medical Imaging (OJMI) , 2015, DOI: 10.4236/ojmi.2015.54025
Abstract: Objective: The purpose of this study was to evaluate the effect of radiation dose reduction on the quantification of air trapping on expiratory CT. Materials and methods: This study was conducted as a retrospective evaluation of inspiratory and expiratory CT studies performed in routine clinical practice before and after alteration of the scanning protocol for expiratory CT at our institute. Eighty-six patients who had a clinical diagnosis of chronic obstructive pulmonary disease (COPD) and underwent inspiratory and expiratory CT and pulmonary function testing (PFT) were included. For the quantitative analysis, CT scans were obtained at six evenly spaced levels from the lung apices to the bases. The area of segmented lung without emphysema between -500 to -950 HU was obtained from the summation of six slices. The relative area between -900 and -950 HU for the area of the segmented lung (RA900-950) was calculated on both the inspiratory and expiratory scans. Comparisons of the RA-change between the standard-dose group (200 mA) and the low-dose group (80 mA) were performed by Mann-Whitney U test. Results: There was no significant difference between the standard-dose group and the low-dose group in the mean RA-change, and RA-change in both the standard-dose and low-dose groups correlated significantly with the results of PFT. In addition, there were no prominent differences in the correlation coefficients between the two groups. Conclusions: Low-dose CT could evaluate air trapping objectively and was not inferior to standard-dose CT for this purpose.
Detection of Type A Trichothecene Di-Glucosides Produced in Corn by High-Resolution Liquid Chromatography-Orbitrap Mass Spectrometry
Hiroyuki Nakagawa,Shigeru Sakamoto,Yuki Sago,Hitoshi Nagashima
Toxins , 2013, DOI: 10.3390/toxins5030590
Abstract: The existence of di-glucosylated derivative of T-2 toxin in plant (corn powder) was confirmed for the first time in addition to that of HT-2 toxin. These masked mycotoxins (mycotoxin glucosides) were identified as T-2 toxin-di-glucoside (T2GlcGlc) and HT-2 toxin-di-glucoside (HT2GlcGlc) based on accurate mass measurements of characteristic ions and fragmentation patterns using high-resolution liquid chromatography-Orbitrap mass spectrometric (LC-Orbitrap MS) analysis. Although the absolute structure of T2GlcGlc was not clarified, two glucose molecules were suggested to be conjugated at 3-OH position in tandem when considering the structure of T-2 toxin. On the other hand, the specification of the structure seems to be more complicated in the case of HT2GlcGlc, since HT-2 toxin has two possible positions (at 3-OH and 4-OH) to be glusocylated. In addition, 15-monoacetoxyscirpenol-glucoside (MASGlc) was also detected in the identical sample.
Optimal Minimum Number of CT Slices Required to Measure Cross Sectional Areas of Small Pulmonary Vessels  [PDF]
Shingo Sakamoto, Shoichiro Matsushita, Akiyuki Kotoku, Hayato Tomita, Yuki Saito, Shinji Saruya, Shin Matsuoka, Tsuneo Yamashiro, Atsuko Fujikawa, Kunihiro Yagihashi, Yasuo Nakajima
Open Journal of Medical Imaging (OJMI) , 2015, DOI: 10.4236/ojmi.2015.52011
Abstract: The cross-sectional area (CSA) of small pulmonary vessels can be quantified by CT, which is a reliable method of evaluating vascular alterations in such vessels. However, the optimal number of slices required for accurate quantitation remains unknown. We evaluated relationships among all slices at 10-mm interval and all slices at 3-cm interval, 6-cm interval, and 3-slices and found the closest correlation (0.939) between all slices at 10-mm intervals and 3-cm intervals. Thus, all slices at 3-cm intervals are suitable for accurately measuring CSA.
Highly Sensitive Determination of Hydrogen Peroxide and Glucose by Fluorescence Correlation Spectroscopy
Satoshi Watabe,Yuki Sakamoto,Mika Morikawa,Ryuichi Okada,Toshiaki Miura,Etsuro Ito
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0022955
Abstract: Because H2O2 is generated by various oxidase-catalyzed reactions, a highly sensitive determination method of H2O2 is applicable to measurements of low levels of various oxidases and their substrates such as glucose, lactate, glutamate, urate, xanthine, choline, cholesterol and NADPH. We propose herein a new, highly sensitive method for the measurement of H2O2 and glucose using fluorescence correlation spectroscopy (FCS).
Long-Term Results of Cell-Free Biodegradable Scaffolds for In Situ Tissue-Engineering Vasculature: In a Canine Inferior Vena Cava Model
Goki Matsumura, Naotaka Nitta, Shojiro Matsuda, Yuki Sakamoto, Noriko Isayama, Kenji Yamazaki, Yoshito Ikada
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0035760
Abstract: We have developed a new biodegradable scaffold that does not require any cell seeding to create an in-situ tissue-engineering vasculature (iTEV). Animal experiments were conducted to test its characteristics and long-term efficacy. An 8-mm tubular biodegradable scaffold, consisting of polyglycolide knitted fibers and an L-lactide and ε-caprolactone copolymer sponge with outer glycolide and ε-caprolactone copolymer monofilament reinforcement, was implanted into the inferior vena cava (IVC) of 13 canines. All the animals remained alive without any major complications until euthanasia. The utility of the iTEV was evaluated from 1 to 24 months postoperatively. The elastic modulus of the iTEV determined by an intravascular ultrasound imaging system was about 90% of the native IVC after 1 month. Angiography of the iTEV after 2 years showed a well-formed vasculature without marked stenosis or thrombosis with a mean pressure gradient of 0.51±0.19 mmHg. The length of the iTEV at 2 years had increased by 0.48±0.15 cm compared with the length of the original scaffold (2–3 cm). Histological examinations revealed a well-formed vessel-like vasculature without calcification. Biochemical analyses showed no significant differences in the hydroxyproline, elastin, and calcium contents compared with the native IVC. We concluded that the findings shown above provide direct evidence that the new scaffold can be useful for cell-free tissue-engineering of vasculature. The long-term results revealed that the iTEV was of good quality and had adapted its shape to the needs of the living body. Therefore, this scaffold would be applicable for pediatric cardiovascular surgery involving biocompatible materials.
A calmodulin inhibitor, W-7 influences the effect of cyclic adenosine 3', 5'-monophosphate signaling on ligninolytic enzyme gene expression in Phanerochaete chrysosporium
Takaiku Sakamoto, Yuki Yao, Yoshifumi Hida, Yoichi Honda, Takashi Watanabe, Wataru Hashigaya, Kazumi Suzuki, Toshikazu Irie
AMB Express , 2012, DOI: 10.1186/2191-0855-2-7
Abstract: White-rot fungi are known to have a powerful ligninolytic system that can completely degrade wood lignin (Kirk and Farrell 1987; Kirk et al. 1975) as well as persistent organic pollutants such as dioxin (Bumpus et al. 1985). This ability may be applicable to the construction of a novel potent bioreactor system to convert wood to potent materials and energy sources with low environmental load and to bioremediate polluted environments. However, the ligninolytic property of these fungi is attributable to many known and unknown enzyme genes, expression of which is inductive, and the factors that determine this expression are not completely understood. The lack of knowledge regarding the ligninolytic property of these fungi is an impediment to the development of a highly effective lignin-degrading fungal strain for the construction of an efficient bioreactor system (Cullen and Kersten 2004). The identification of a master regulator that regulates the entire ligninolytic system in white-rot fungi could be used as a target for breeding a high lignin-degrading strain and for furthering our understanding of the lignin-degradation system in these fungi.Phanerochaete chrysosporium, which is the most widely researched white-rot fungus in the world, has 2 families of lignin-degrading peroxidases designated lignin peroxidase (LiP) and manganese peroxidase (MnP) (Heinzkill and Messner 1997). LiP and MnP are thought to play an important role in initiating the lignin degrading reaction of the fungus, because they can cleave lignin structures extracellularly in the first step of lignin mineralization (Cullen and Kersten 2004; Gold et al. 1984; Tien and Kirk 1984). Moreover, LiP and MnP themselves also have potential applications in treating textile effluent (Sedighi et al. 2009; Singh et al. 2010). However, their expression is inductive, related to unknown factors, and known to be unstable, as is the entire ligninolytic system. Information concerning the LiP and MnP expression system
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