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Numerical Study of Slow-wave Instabilities in an Oversized Coaxial Slow-wave Structure
Kazuo Ogura,Shingo Abe,Hiroki Kimura,Kazumasa Yamamoto,Kiyoyuki Yambe,Ruhul Amin 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.61
In this paper, slow-wave instabilities in oversized coaxial SWSs are numerically analyzed. An infinitesimally thin annular beam with transverse perturbations and guided by a finite axial magnetic field is considered as the energy source for creating the instabilities. The coaxial SWSs consist of an outer oversized hollow waveguide and a central conductor and have sinusoidal corrugations. An electromagnetic slow-wave is generated by the inner corrugation and is called inner surface wave (ISW). The ISW is a cylindrical surface wave and can exist even if the outer conductor is removed. The higher-order modes are produced by the outer waveguide. The annular beam interacts with the ISW and higher-order modes. Slow cyclotron instability occurs due to the transversely modulated beam boundary, in addition to the conventional Cherenkov instability. The slow-wave instabilities are able to be controlled by the beam radius and the relative position of inner and outer corrugations.
Magnetic resonance enterography for the evaluation of the deep small intestine in Crohn`s disease
( Kazuo Ohtsuka ),( Kento Takenaka ),( Yoshio Kitazume ),( Toshimitsu Fujii ),( Katsuyoshi Matsuoka ),( Masakazu Nagahori ),( Maiko Kimura ),( Takashi Nagaishi ),( Mamoru Watanabe ) 대한장연구학회 2016 Intestinal Research Vol.14 No.2
For the control of Crohn`s disease (CD) a thorough assessment of the small intestine is essential; several modalities may be utilized, with cross-sectional imaging being important. Magnetic resonance (MR) enterography, i.e., MRE is recommended as a modality with the highest accuracy for CD lesions. MRE and MR enteroclysis are the two methods performed following distension of the small intestine. MRE has sensitivity and specificity comparable to computed tomography enterography (CTE); although images obtained using MRE are less clear compared with CTE, MRE does not expose the patient to radiation and is superior for soft-tissue contrast. Furthermore, it can assess not only static but also dynamic and functional imaging and reveals signs of CD, such as abscess, comb sign, fat edema, fistula, lymph node enhancement, less motility, mucosal lesions, stricture, and wall enhancement. Several indices of inflammatory changes and intestinal damage have been proposed for objective evaluation. Recently, diffusion-weighted imaging has been proposed, which does not need bowel preparation and contrast enhancement. Comprehension of the characteristics of MRE and other modalities is important for better management of CD. (Intest Res 2016;14:120-126)
Anaerobic Bacterial Degradation for the Effective Utilization of Biomass
Ohmiya, Kunio,Sakka, Kazuo,Kimura, Tetsuya The Korean Society for Biotechnology and Bioengine 2005 Biotechnology and Bioprocess Engineering Vol.10 No.6
Biomass is originally photosynthesized from inorgainic compounds such as $CO_2$, minerals, water and solar energy. Recent studies have shown that anaerobic bacteria have the ability to convert recalcitrant biomass such as cellullosic or chitinoic materials to useful compounds. The biomass containing agricultural waste, unutilized wood and other garbage is expected to utilize as feed, food and fuel by microbial degradation and other metabolic functions. In this study we isolated several anaerobic, cellulolytic and chitinolytic bacteria from rumen fluid, compost and soil to study their related enzymes and genes. The anaerobic and cellulolytic bacteria, Clostridium thermocellum, Clostridium stercorarium, and Clostridium josui, were isolated from compost and the chitinolytic Clostridium paraputrificum from beach soil and Ruminococcus albus was isolated from cow rumen. After isolation, novel cellulase and xylanase genes from these anaerobes were cloned and expressed in Escherichia coli. The properties of the cloned enzymes showed that some of them were the components of the enzyme (cellulase) complex, i.e., cellulosome, which is known to form complexes by binding cohesin domains on the cellulase integrating protein (Cip: or core protein) and dockerin domains on the enzymes. Several dockerin and cohesin polypeptides were independently produced by E. coli and their binding properties were specified with BIAcore by measuring surface plasmon resonance. Three pairs of cohesin-dockerin with differing binding specificities were selected. Two of their genes encoding their respective cohesin polypeptides were combined to one gene and expressed in E. coli as a chimeric core protein, on which two dockerin-dehydrogenase chimeras, the dockerin-formaldehyde dehydrogenase and the dockerin-NADH dehydrogenase are planning to bind for catalyzing $CO_2$ reduction to formic acid by feeding NADH. This reaction may represent a novel strategy for the reduction of the green house gases. Enzymes from the anaerobes were also expressed in tobacco and rice plants. The activity of a xylanase from C. stercorarium was detected in leaves, stems, and rice grain under the control of CaMV35S promoter. The digestibility of transgenic rice leaves in goat rumen was slightly accelerated. C. paraputrificum was found to solubilize shrimp shells and chitin to generate hydrogen gas. Hydrogen productivity (1.7 mol $H_2/mol$ glucos) of the organism was improved up to 1.8 times by additional expression of the own hydrogenase gene in C. paraputrficum using a modified vector of Clostridiu, perfringens. The hydrygen producing microflora from soil, garbage and dried pelletted garbage, known as refuse derived fuel(RDF), were also found to be effective in converting biomass waste to hydrogen gas.
( Piyangkun Lueangjaroenkit ),( Churapa Teerapatsakul ),( Kazuo Sakka ),( Makiko Sakka ),( Tetsuya Kimura ),( Emi Kunitake ),( Lerluck Chitradon ) 한국균학회 2019 Mycobiology Vol.47 No.2
Two manganese peroxidases (MnPs), MnP1 and MnP2, and a laccase, Lac1, were purified from Trametes polyzona KU-RNW027. Both MnPs showed high stability in organic solvents which triggered their activities. Metal ions activated both MnPs at certain concentrations. The two MnPs and Lac1, played important roles in dye degradation and pharmaceutical products deactivation in a redox mediator-free system. They completely degraded Remazol brilliant blue (25 mg/L) in 10-30 min and showed high degradation activities to Remazol navy blue and Remazol brilliant yellow, while Lac1 could remove 75% of Remazol red. These three purified enzymes effectively deactivated tetracycline, doxycycline, amoxicillin, and ciprofloxacin. Optimal reaction conditions were 50 ℃ and pH 4.5. The two MnPs were activated by organic solvents and metal ions, indicating the efficacy of using T. polyzona KURNW027 for bioremediation of aromatic compounds in environments polluted with organic solvents and metal ions with no need for redox mediator supplements.
Motoyasu Kan,Yusuke Hashimoto,Taro Shibuki,Gen Kimura,Kumiko Umemoto,Kazuo Watanabe,Mitsuhito Sasaki,Hideaki Takahashi,Hiroshi Imaoka,Izumi Ohno,Shuichi Mitsunaga,Masafumi Ikeda 소화기인터벤션의학회 2019 International journal of gastrointestinal interven Vol.8 No.2
Background: In patients with distal malignant biliary obstruction, it is a challenge to manage acute cholecystitis secondary to cystic duct obstruc-tion associated with tumor progression or stent compression. Percutaneous transhepatic gallbladder drainage (PTGBD) has been used as the treatment option of choice, because of its ease of performance and safety, but because of the use of an external drainage tube, some patients experience a de-creased quality of life. We report the technical success and clinical success of conversion from PTGBD to endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) for the treatment of acute cholecystitis in patients with unresectable malignant biliary obstruction.Methods: We included the patients with cholecystitis secondary to unresectable malignant biliary obstruction who underwent conversion from PT-GBD to EUS-GBD in the study. After PTGBD for the treatment of acute cholecystitis, we performed EUS-GBD and a plastic stent or a self-expandable metal stent (SEMS) was placed for fistulostomy.Results: Fourteen patients (median age, 69 years; 9 males and 5 females) underwent conversion to EUS-GBD after clinical improvement of cholecys-titis by PTGBD. The technical success rate of the conversion from PTGBD to EUS-GBD was 100% (14/14). EUS-GBD was performed in a median of 9.5 days (range, 3–51 days) after PTGBD procedure, using mainly a plastic stent (13 patients) and a covered SEMS in one patient. The early (within 24 hours) adverse events rate was 14.3% (2/14), and the late (after 24 hours) adverse events rate was 7.1% (1/14). The rate of recurrence of cholecystitis was 28.6% (4/14). These patients underwent endoscopic re-intervention and there were no cases of further recurrence of cholecystitis. Conclusion: Conversion of PTGBD to EUS-GBD demonstrated a feasible and safe technique for acute cholecystitis in non-surgical candidates with malignant biliary obstruction.
Motoyasu Kan,Yusuke Hashimoto,Taro Shibuki,Gen Kimura,Kumiko Umemoto,Kazuo Watanabe,Mitsuhito Sasaki,Hideaki Takahashi,Hiroshi Imaoka,Izumi Ohno,Shuichi Mitsunaga,Masafumi Ikeda 소화기인터벤션의학회 2019 Gastrointestinal Intervention Vol.8 No.2
Background: In patients with distal malignant biliary obstruction, it is a challenge to manage acute cholecystitis secondary to cystic duct obstruc-tion associated with tumor progression or stent compression. Percutaneous transhepatic gallbladder drainage (PTGBD) has been used as the treatment option of choice, because of its ease of performance and safety, but because of the use of an external drainage tube, some patients experience a de-creased quality of life. We report the technical success and clinical success of conversion from PTGBD to endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) for the treatment of acute cholecystitis in patients with unresectable malignant biliary obstruction.Methods: We included the patients with cholecystitis secondary to unresectable malignant biliary obstruction who underwent conversion from PT-GBD to EUS-GBD in the study. After PTGBD for the treatment of acute cholecystitis, we performed EUS-GBD and a plastic stent or a self-expandable metal stent (SEMS) was placed for fistulostomy.Results: Fourteen patients (median age, 69 years; 9 males and 5 females) underwent conversion to EUS-GBD after clinical improvement of cholecys-titis by PTGBD. The technical success rate of the conversion from PTGBD to EUS-GBD was 100% (14/14). EUS-GBD was performed in a median of 9.5 days (range, 3–51 days) after PTGBD procedure, using mainly a plastic stent (13 patients) and a covered SEMS in one patient. The early (within 24 hours) adverse events rate was 14.3% (2/14), and the late (after 24 hours) adverse events rate was 7.1% (1/14). The rate of recurrence of cholecystitis was 28.6% (4/14). These patients underwent endoscopic re-intervention and there were no cases of further recurrence of cholecystitis. Conclusion: Conversion of PTGBD to EUS-GBD demonstrated a feasible and safe technique for acute cholecystitis in non-surgical candidates with malignant biliary obstruction.
Multi-step Metamagnetic Processes of PrPd2Si2 Single Crystal
Toru Shigeoka,Tetsuya Fujiwara,Keiichi Koyama,Shojiro Kimura,Kazuo Watanabe 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
Magnetic studies were performed on PrPd2Si2 single crystals which crystallize in the tetragonalThCr2Si2-type structure. The temperature dependence of the magnetic susceptibility indicates thatthe compound orders antiferromagnetically at temperatures below TN = 3.2 K. The transition wasconfirmed by specific heat measurements. Magnetization measurements at fields up to 18 T showthat the easy magnetization direction is the [100] direction in the basal plane. In the magnetizationprocess, five or four metamagnetic transitions appear; the process is a five (four)-step metamagneticone. The [110] magnetization process is a three-step one. A strong magnetic anisotropy betweenthe [100] and [110] directions is observed within the basal plane for high magnetic fields. Alongthe hard magnetization direction of the c-axis, a metamagnetic transition appears. The B[100] − Tphase diagram was constructed. A magnetic anisotropy between the [100] and [001] directions isalso strong. These behaviors are discussed based on an analysis of crystalline field effects.