134 results on '"Kenji Kodama"'
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2. Development of a Three-Layer Fabric Mechanism for a Passive-Type Assistive Suit.
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Chi Lok Wan, Toshifumi Ishioka, Chiaki Kanda, Keisuke Osawa, Kenji Kodama, and Eiichiro Tanaka
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- 2022
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3. Development and Evaluation of a Close-Fitting Assistive Suit for Back and Arm Muscle - e.z.UP®-.
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Yun-Ting Liao, Toshifumi Ishioka, Kazuko Mishima, Chiaki Kanda, Kenji Kodama, and Eiichiro Tanaka
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- 2020
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4. Development and Evaluation of a Worker-Wear Assistance Suit with the Adjustable and Concealable Elastic Structure for the Manual Handling Workers.
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Yun-Ting Liao, Kenji Kodama, Toshifumi Ishioka, Hee-Hyol Lee, and Eiichiro Tanaka
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- 2018
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5. Clopidogrel Use in CYP2C19 Loss-of-Function Carriers With High Bleeding Risk After Percutaneous Coronary Intervention
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Yuichi Sawayama, Yukinori Tomita, Soji Kohyama, Yosuke Higo, Kenji Kodama, Kohei Asada, Noriaki Yagi, Megumi Fukuyama, Atsushi Hayashi, Wataru Shioyama, Hiroshi Sakai, Tomoya Ozawa, Tetsuichiro Isono, Daiki Hira, Takashi Yamamoto, Shin-ya Morita, and Yoshihisa Nakagawa
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General Medicine ,Cardiology and Cardiovascular Medicine - Published
- 2023
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6. Impact of High Lipoprotein(a) Levels on Clinical Outcomes Following Peripheral Endovascular Therapy
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Yusuke Tomoi, Mitsuyoshi Takahara, Yoshimitsu Soga, Kenji Kodama, Kazuaki Imada, Seiichi Hiramori, and Kenji Ando
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Lipoproteins, LDL ,Stroke ,Peripheral Arterial Disease ,Cholesterol ,Treatment Outcome ,Risk Factors ,Endovascular Procedures ,Myocardial Infarction ,Humans ,Hydroxymethylglutaryl-CoA Reductase Inhibitors ,Cardiology and Cardiovascular Medicine ,Biomarkers ,Lipoprotein(a) - Abstract
Elevated lipoprotein(a) (Lp[a]) levels are an independent risk factor for the development of atherosclerotic diseases, including peripheral artery disease (PAD). However, their prognostic impact in patients with PAD remains unknown.The aim of this study was to examine the prognostic impact of elevated Lp(a) levels in patients with PAD undergoing endovascular therapy (EVT).In total, 1,169 patients who underwent successful EVT for symptomatic PAD between September 2016 and August 2021 were included in this study. High Lp(a) levels were defined as30 mg/dL. The associations of high Lp(a) levels with incident major adverse cardiovascular events (MACE) (all-cause death, myocardial infarction, and stroke) and major adverse limb events (MALE) (repeat revascularization for target limb and major amputation) were analyzed.During a median follow-up period of 1.7 years (IQR: 0.6-3.0 years), 230 MACE (210 deaths, 15 myocardial infarctions, and 22 strokes) and 263 MALE (219 reinterventions and 36 major amputations) were observed. The cumulative incidence rate of MACE (48.1% vs 27.3%) and MALE (67.9% vs 27.2%) was significantly higher in patients with high Lp(a) levels (P 0.001 for both). The adjusted HR were 1.93 (95% CI: 1.44-2.59; P 0.001) for MACE and 4.15 (95% CI: 3.14-5.50; P 0.001) for MALE. These associations were not influenced by low-density lipoprotein cholesterol levels or statin administration (P for interaction0.05 for all).Elevated Lp(a) levels were independently associated with incident MACE and MALE in patients with PAD treated with revascularization irrespective of low-density lipoprotein cholesterol level and statin administration.
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- 2022
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7. Validation of the Academic Research Consortium High Bleeding Risk (ARC-HBR) criteria in patients undergoing peripheral endovascular interventions
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Yusuke Tomoi, Shoichi Kuramitsu, Tomohiro Shinozaki, Yoshimitsu Soga, Kenji Kodama, Kazuaki Imada, Seiichi Hiramori, and Kenji Ando
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Cardiology and Cardiovascular Medicine - Abstract
It remains unclear whether the Academic Research Consortium for High Bleeding Risk (ARC-HBR) criteria could apply to peripheral artery disease (PAD) patients undergoing endovascular therapy (EVT).We sought to evaluate the application of the ARC-HBR criteria to PAD patients undergoing EVT with contemporary drug-coated devices (DCD) for femoropopliteal artery lesions.Between May 2012 and December 2019, 542 consecutive patients undergoing EVT with DCD for femoropopliteal artery lesions were retrospectively analysed. The primary study endpoint was major bleeding events, defined as Bleeding Academic Research Consortium type 3 or 5.Of 542 patients, 435 (80.3%) were stratified into the HBR group. The cumulative 5-year incidence of major bleeding events was significantly higher in the HBR group than in the no-HBR group (31.9% vs 2.3%; p0.001). The 5-year major bleeding event rate gradually increased with the number of ARC-HBR criteria (≥2 major criteria: 48.6%, 1 major: 33.1%, ≥2 minor: 12.9%, and non-HBR: 2.3%; p0.001). Major bleeding events were associated with a 5.4-fold increased risk of mortality (adjusted hazard ratio: 5.42, 95% confidence interval: 2.91-10.1; p0.001). Severe chronic kidney disease, heart failure, and severe anaemia were predictors of major bleeding events.80.3% of PAD patients undergoing EVT for femoropopliteal artery lesions with contemporary drug-coated devices met the ARC-HBR criteria. Given that major bleeding events remarkably increased the risk of mortality after EVT, the ARC-HBR criteria might be helpful for the risk stratification of PAD patients who undergo EVT with contemporary DCD.
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- 2022
8. Design and implementation of a ubiquitous optical device controlled with a projector.
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Mami Nakata, Yoshinari Takegawa, Kenji Kodama, Tsutomu Terada, Naotaka Fujita, Masahiko Tsukamoto, Shinichi Hosomi, and Shojiro Nishio
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- 2008
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9. A rule-based acceleration data processing engine for small sensor node.
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Kenji Kodama, Naotaka Fujita, Yutaka Yanagisawa, Tsutomu Terada, and Masahiko Tsukamoto
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- 2008
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10. Two-dimensional observation of excited atoms and ions and excitation temperature in inductively coupled plasma using newly developed four channel spectrovideo camera.
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Zhe Cui, Kenji Kodama, Hiroyuki Oyama, and Kuniyuki Kitagawa
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- 2010
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11. Measurement of two-dimensional distribution profile of lead in a flame by planar laser-induced fluorescence spectroscopy.
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Kenji Kodama and Kuniyuki Kitagawa
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- 2010
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12. Development and Evaluation of a Close-Fitting Assistive Suit for Back and Arm Muscle – e.z.UP®–
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Kenji Kodama, Chiaki Kanda, Eiichiro Tanaka, Kazuko Mishima, Yun Ting Liao, and Toshifumi Ishioka
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0209 industrial biotechnology ,medicine.medical_specialty ,General Computer Science ,Computer science ,030503 health policy & services ,02 engineering and technology ,03 medical and health sciences ,020901 industrial engineering & automation ,Physical medicine and rehabilitation ,Arm muscle ,medicine ,Electrical and Electronic Engineering ,0305 other medical science ,Assistive suit - Abstract
This paper proposes a close-fitting assistive suit, called e.z.UP®, with a passive actuation mechanism composed of an adjustable structure. The suit can adequately assist the back and arm muscles of a user with the proposed layout of an arm assistive belt and a two-layer structure, respectively. With its lightweight characteristic (i.e., weighing 0.75 kg only), the proposed suit is portable and easy to wear without additional burden. By using the averaged Japanese body data, a simulation was conducted based on a human body model wearing our proposed suit to evaluate the layout of the arm assistive belt. The simulation results prove that the proposed suit can adequately assist the user’s arm muscles based on the user’s motion. An experiment involving the measurement of muscle activities is also implemented with seven young subjects and seven middle-aged subjects to evaluate the arm assistive belt and the two-layer structure. The experimental results reveal that the proposed suit can successfully and appropriately assist both the arm and back muscles simultaneously.
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- 2020
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13. Brachiocephalic and Subclavian Artery Aneurysm Treated With Covered Stent
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Yoshimitsu Soga, Kenji Kodama, and Kenji Ando
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Cardiology and Cardiovascular Medicine - Abstract
Endovascular repair for brachiocephalic artery aneurysms (BAAs) and subclavian artery aneurysms (SAAs) is often unclear. We treated 2 such cases percutaneously with covered stents. It may be an alternative to surgical repair for patients with isolated BAA or SAA. (
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- 2022
14. Direct analysis of saturated hydrocarbons using glow discharge plasma ionization source for mass spectrometry
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Kazuaki Wagatsuma, Ichiro Naruse, Ryo Yoshiie, Kenji Kodama, Yasuaki Ueki, and Yoko Nunome
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Detection limit ,Chemistry ,Hydride ,010401 analytical chemistry ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Mass spectrometry ,01 natural sciences ,Redox ,0104 chemical sciences ,Analytical Chemistry ,Ion ,Fragmentation (mass spectrometry) ,Deuterium ,Ionization ,0210 nano-technology - Abstract
The ionization source based on glow discharge plasma using ambient air is driven by a pulsed direct-current voltage for soft plasma ionization (SPI). The novelty of this work is that molecular ions [M+13]+ related to the analyte species (M), which may be formed by numerous oxidation, can be dominantly detected as a base peak with little or no fragmentation of them in an air plasma at a pressure of several kPa. The unique ion [M+13]+ was assigned to the oxidation product, [M+O-3H]+, which was confirmed as a deuterated ion [M+O-3D]+ ([M+10]+) by using a deuterated solvent. The ionization reactions were suggested that the product ion [M+O-3H]+ may arise from hydride abstraction reaction of M with O2+•, dehydrogenation reaction of [M-H]+• and subsequently oxidation reaction of [M-3H]+ with O3. n-Alkane mixtures was also measured to evaluate the intermolecular interaction in this system. The limits of detection (LOD) were in the range of 0.126-1.68 ppmv and the relative standard deviation (RSD) for repeatability was approximately 10.0% at the lowest concentration. To our knowledge, this is the first report demonstrating that the spectrum pattern of saturated hydrocarbons could be directly determined without any complicated fragmentation.
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- 2019
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15. Glow Discharge Plasma Ionization Mass Spectrometry for Direct Detection of Oxygenated Organic Compounds in the Gas-phase
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Kazuaki Wagatsuma, Yoko Nunome, and Kenji Kodama
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Solvent ,Fragmentation (mass spectrometry) ,Chemistry ,Ionization ,Polyatomic ion ,Analytical chemistry ,Proton affinity ,Protonation ,Mass spectrometry ,Analytical Chemistry ,Ion - Abstract
This study describes a direct analysis of oxygenated organic compounds, such as ketones, esters and ethers, rapidly and easily using a soft plasma ionization (SPI) source combined with a Q-mass spectrometer. A related molecular ion, [2M+H]+, in which a sample molecule (M) can undergo protonation via water clusters, such as [(H2O)n+H]+ and [N2(H2O)n+H]+, in an ambient air glow discharge plasma, can be dominantly detected as a base peak with little or no fragmentation at a pressure of several kPa. Oxygenated organic compounds with high proton affinity were found to generate their dimers through the hydrogen bonding interaction at higher pressures. A deuterated solvent was used to examine whether or not the adduct ion of analyte was derived from the solvent. The formation of [2M+H]+ strongly depended on the time. A two-dimensional spectrometer was used to obtain the distribution of several excited species and then to confirm the ionization reactions of the analyte in the SPI source. The sample molecule would be readily ionized through Penning-type collisions with excited N2, which causes fragmentation for oxygenated compounds due to the lower pressures (approx. 1.0 kPa) while it is ionized by an attachment with protons from water clusters at higher pressures (several kPa). The SPI source can be a new and powerful tool for soft ionization in direct analysis of volatile organic compounds (VOCs).
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- 2019
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16. Ventricular fibrillation associated with vasospastic angina pectoris in Fabry disease: a case report
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Kenichi Dochi, Tomoya Ozawa, Yoshiki Ueno, and Kenji Kodama
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medicine.medical_specialty ,Sinus bradycardia ,Case Reports ,030204 cardiovascular system & hematology ,Left ventricular hypertrophy ,01 natural sciences ,Sick sinus syndrome ,03 medical and health sciences ,0302 clinical medicine ,Cardiac magnetic resonance imaging ,Internal medicine ,Case report ,medicine ,cardiovascular diseases ,Ventricular fibrillation ,ST depression ,Fabry disease ,medicine.diagnostic_test ,business.industry ,ST elevation ,Vasospastic angina pectoris ,medicine.disease ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Cardiology ,cardiovascular system ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,Electrocardiography - Abstract
Background Fabry disease (FD) is an X-linked lysosomal storage disorder resulting from a deficiency in alpha-galactosidase A. The major causes of death due to cardiac complications include life-threatening arrhythmias. In addition, life-threatening arrhythmias may be related to myocardial fibrosis assessed by late gadolinium enhancement (LGE). Case summary A 43-year-old man with sinus bradycardia and left ventricular hypertrophy was referred to our cardiology department. Family history includes unexplained hypertrophy and sick sinus syndrome in mother. Additionally, his plasma alpha-galactosidase A activity was low. He was subsequently diagnosed with FD. Enzyme replacement therapy using 1.0 mg/kg agalsidase-β was initiated. During the fifth administration, he developed ventricular fibrillation (VF). Electrocardiography conducted immediately before VF revealed ST elevation in the inferior leads with reciprocated ST depression. Cardiac magnetic resonance imaging showed no LGE in the myocardium. Coronary angiography showed no organic stenosis; moreover, coronary spasms were induced by an intracoronary acetylcholine injection. Ventricular fibrillation was not observed as the patient received calcium antagonists. Discussion This report suggests that vasospastic angina pectoris is associated with life-threatening arrhythmias in patient with FD without LGE.
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- 2019
17. Recycling endosomal CD133 functions as an inhibitor of autophagy at the pericentrosomal region
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Akira Nakagawara, Takehiko Kamijo, Michio Yasunami, Hisashi Matsunaga, Masami Shibaki, Yuanyuan Li, Takao Mae, Kenji Kodama, Hideki Izumi, Seiji Sato, Yasuhiko Kaneko, and Daisuke Mori
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0301 basic medicine ,Endosome ,GABARAP ,Cellular differentiation ,media_common.quotation_subject ,Autophagic Cell Death ,Dynein ,lcsh:Medicine ,Endosomes ,Article ,03 medical and health sciences ,0302 clinical medicine ,fluids and secretions ,Cancer stem cell ,Autophagy-Related Protein-1 Homolog ,Humans ,AC133 Antigen ,Internalization ,lcsh:Science ,neoplasms ,media_common ,Centrosome ,Multidisciplinary ,Chemistry ,Autophagy ,lcsh:R ,Intracellular Signaling Peptides and Proteins ,ULK1 ,Cell biology ,carbohydrates (lipids) ,030104 developmental biology ,HEK293 Cells ,embryonic structures ,cardiovascular system ,lcsh:Q ,Caco-2 Cells ,Apoptosis Regulatory Proteins ,Microtubule-Associated Proteins ,030217 neurology & neurosurgery - Abstract
CD133 is a transmembranous protein that mainly localises to the plasma membrane in haematopoietic and neural stem cells as well as cancer stem cells. Although CD133 also localises to the cytoplasm, the mechanism of action and function of cytoplasmic CD133 currently remain unknown. We herein demonstrated that when Src family kinase activity is weak, CD133 interacts with HDAC6 and is transported to the pericentrosomal region after internalization and endosome formation via the dynein-based traffic system. Pericentrosomal CD133 is then recycled to the plasma membrane via recycling endosomes. At the pericentrosomal region, endosomal CD133 captures GABARAP, an initiator of autophagy, and inhibits GABARAP-mediated ULK1 activation and the subsequent initiation of autophagy. Furthermore, pericentrosomal CD133 suppresses cell differentiation, such as primary cilium formation and neurite outgrowth, by inhibiting autophagy. Thus, the present results provide evidence to suggest that pericentrosomal CD133 has the unique property of maintaining the undifferentiated status of cells by inhibiting autophagy.
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- 2019
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18. Diverse phenotypic expression associated with the same genetic variant in female heterozygote patients of Anderson–Fabry disease: a case series
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Yoshihisa Nakagawa, Kenji Kodama, Kenichi Dochi, Hiroaki Takahashi, Tomoya Ozawa, Daisuke Tomioka, Yoshiki Ueno, and Koichi Kato
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Vasospasms ,medicine.medical_specialty ,Provocation test ,Globotriaosylceramide ,030204 cardiovascular system & hematology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,medicine ,Case Series ,AcademicSubjects/MED00200 ,X-linked recessive inheritance ,Anderson–Fabry disease ,medicine.diagnostic_test ,business.industry ,Enzyme replacement therapy ,medicine.disease ,Fabry disease ,Coronary arteries ,Cardiac hypertrophy ,medicine.anatomical_structure ,chemistry ,Ventricular fibrillation ,Cardiology ,Cardiology and Cardiovascular Medicine ,business ,Electrocardiography ,030217 neurology & neurosurgery - Abstract
Background Anderson–Fabry disease (AFD) is an X-linked lysosomal storage disorder resulting from a mutation of alpha-galactosidase A gene (GLA), causing deficiency in alpha-galactosidase activity. The enzyme deficit can lead to storage of globotriaosylceramide in various organs including heart. Studies suggest that vasospastic angina (VSA) is associated with AFD. Case summary This clinical case series aimed to present two female patients with AFD, including progressive cardiac involvement: a 50-year-old woman (patient number 1) and a 39-year-old woman (patient number 2) who are siblings with a male AFD patient harbouring p. Arg342Glu missense variant in alpha-galactosidase A gene (GLA), who suffered VSA and subsequent ventricular fibrillation. Enzymatic tests and genetic analysis confirmed AFD in both female patients and histological tests revealed globotriaosylceramide deposits in their hearts. In patient number 1, a 12-lead electrocardiography and transthoracic echocardiography revealed cardiac hypertrophy. Coronary angiography revealed no organic coronary artery stenosis and vasospasms was induced by spasm provocation test. In patient number 2, no signs of cardiac hypertrophy were found, and coronary arteries had no organic stenosis with negative spasm provocation test. Both patients received enalapril therapy and enzyme replacement therapy (ERT). Discussion Different phenotype of AFD was occurred even with the same genetic variant in female heterozygote patients. The duration of exposing accumulation of Gb3 might affect cardiac hypertrophy and vasospasms. Coronary angiography with acetylcholine provocation test should be considered in female AFD patient, especially in case with cardiac hypertrophy.
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- 2021
19. A rule engine to process acceleration data on small sensor nodes.
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Kenji Kodama, Naotaka Fujita, Yutaka Yanagisawa, Masahiko Tsukamoto, and Tomoki Yoshihisa
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- 2008
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20. Transient response of the emission signal controlled by pulsated bias current in pulsed radio-frequency glow discharge optical emission spectrometry
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Kenji Kodama, Kazuaki Wagatsuma, Yoko Nunome, and Kikuyasu Sasaki
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Materials science ,business.industry ,010401 analytical chemistry ,RF power amplifier ,Biasing ,02 engineering and technology ,Plasma ,021001 nanoscience & nanotechnology ,01 natural sciences ,Signal ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Analytical Chemistry ,Amplitude ,Physics::Plasma Physics ,Optoelectronics ,Transient response ,Transient (oscillation) ,0210 nano-technology ,business ,Instrumentation ,Spectroscopy ,Voltage - Abstract
The objective of this paper is to suggest a new method for controlling temporal response of the emission signal from a pulsed radio-frequency (RF) glow discharge plasma for optical emission spectrometry. It is a noticeable feature that the emission profile accompanies a transient stage in the pulsed operation, appearing as a pre-peak which sometimes becomes 10–20 times as large as the plateau-stage intensity. Therefore, it is worth studying how the spike-like transient signal can be modified to a smooth response following the square-wave timing signal by using any experimental procedure. For this purpose, a phenomenon regarding self-bias voltage in RF plasma was focused on. The self-bias voltage is induced near the RF-loaded electrode, and then, a bias current can be introduced through an electric circuit including the plasma body by connecting an external electric device with the glow discharge plasma source. The bias current could be also pulsated, while it was synchronized with the pulsed RF plasma. Larger pulses of the bias current could change the characteristics of the plasma for atomic emission spectrometry, extending the size of the RF plasma as well as enhancing the emission intensity, which enabled the plateau stage to become more prominent in the pulsed emission profile. Several experimental parameters, such as an amplitude of the bias current, duty ratios of both the RF power and the bias current, and a phase shift between them, were investigated to obtain a plateau-like transient response of the emission signal. It was found that the phase-shift angle should be regulated between timing pulses of the RF voltage and the bias current.
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- 2018
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21. Development of soft ionization using direct current pulse glow discharge plasma source in mass spectrometry for volatile organic compounds analysis
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Ichiro Naruse, Ryo Yoshiie, Kazuaki Wagatsuma, Yasuaki Ueki, Kenji Kodama, and Yoko Nunome
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Chemical ionization ,Chemistry ,010401 analytical chemistry ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Ion source ,0104 chemical sciences ,Analytical Chemistry ,Atmospheric-pressure laser ionization ,Pulsed discharge ionization detector ,Ionization ,0210 nano-technology ,Discharge ionization detector ,Instrumentation ,Spectroscopy ,Electron ionization ,Ambient ionization - Abstract
This study describes an ionization source for mass analysis, consisting of glow discharge plasma driven by a pulsed direct-current voltage for soft plasma ionization, to detect toxic volatile organic compounds (VOCs) rapidly and easily. The novelty of this work is that a molecular adduct ion, in which the parent molecule attaches with an NO + radical, [M + NO] + , can be dominantly detected as a base peak with little or no fragmentation of them in an ambient air plasma at a pressure of several kPa. Use of ambient air as the discharge plasma gas is suitable for practical applications. The higher pressure in an ambient air discharge provided a stable glow discharge plasma, contributing to the soft ionization of organic molecules. Typical mass spectra of VOCs toluene, benzene, o -xylene, chlorobenzene and n -hexane were observed as [M + NO] + adduct ion whose peaks were detected at m / z 122, 108, 136, 142 and 116, respectively. The NO generation was also confirmed by emission bands of NO γ-system. The ionization reactions were suggested, such that NO + radical formed in an ambient air discharge could attach with the analyte molecule.
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- 2018
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22. Investigation of admixed gas effect on plasma nitriding of AISI316L austenitic stainless steel
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Naofumi Ohtsu, Mitsuhiro Hirano, Kenji Kodama, and Koyo Miura
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Austenite ,education.field_of_study ,Materials science ,Metallurgy ,Population ,Plasma ,engineering.material ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Phase (matter) ,engineering ,Surface layer ,Gas composition ,Austenitic stainless steel ,education ,Instrumentation ,Nitriding - Abstract
The influence of discharge gas composition on the plasma nitriding of AISI316L austenitic stainless steel was investigated using a laboratory-made apparatus consisting of a DC diode and a plasma monitoring system. H2-N2 and Ar-N2 gas mixtures with various mixture ratios were introduced in the apparatus, and nitriding was performed without auxiliary substrate heating. A >4 μm-thick surface layer, consisting of an expended austenitic phase, γN, was formed on the AISI316L substrate when the optimized H2-N2 plasma was used. The thickness and maximum nitrogen content of the surface layer increased with an increase in the population of N2+ species in the plasma; the N2+ population in the plasma is considered an underlying parameter for the optimization. Conversely, the penetration of nitrogen into the AISI316L surface was scarce when Ar-N2 plasma was used, irrespective of the gas mixture ratio. Such a phenomenon indicates that Ar-N2 plasma is ineffective for nitriding. However, the effects of H2-N2 plasma, which are not limited to the surface reaction, are beneficial to facilitate nitriding.
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- 2021
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23. Lesion characteristics and procedural outcomes of re-attempted percutaneous coronary interventions for chronic total occlusion
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Kohei Asada, Takeo Kunitomo, Kenji Kodama, and Masaki Tanabe
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Male ,Reoperation ,medicine.medical_specialty ,Time Factors ,Percutaneous ,medicine.medical_treatment ,030204 cardiovascular system & hematology ,Coronary Angiography ,Revascularization ,Lesion ,03 medical and health sciences ,Percutaneous Coronary Intervention ,0302 clinical medicine ,Risk Factors ,Humans ,Medicine ,Registries ,030212 general & internal medicine ,Aged ,business.industry ,Percutaneous coronary intervention ,Vascular surgery ,Discontinuation ,Cardiac surgery ,Surgery ,Treatment Outcome ,Coronary Occlusion ,Fluoroscopy ,Chronic Disease ,Conventional PCI ,Female ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,Follow-Up Studies - Abstract
This study was performed to investigate lesion characteristics and procedural outcomes of re-attempted percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). Prior failure of percutaneous revascularization of CTO has been identified as an independent predictor of failure at subsequent attempts. However, procedural outcomes of re-attempted PCI for CTO have not been elucidated. We evaluated lesion characteristics and procedural outcomes in 310 consecutive patients undergoing CTO-PCI, and compared the results between re-attempted (n = 59) and initial procedures (n = 251). Overall, 266 CTO lesions (85.8%) were treated successfully. In addition, the technical success rate in the re-attempted CTO lesions was 69.5% (41 of 59), although this was lower than for initially attempted lesions (89.6%, 225 of 251; P = 0.0021). In the details of reasons of previous failures, treatment devices failed to cross even after guidewire cross and procedure discontinuation due to management of complications achieved higher rates of technical success compared to those with the inability of guidewire crossing in re-attempted CTO-PCI (87.5 and 85.7 vs. 65.9%, respectively). CTO lesions in which PCI was re-attempted had more complex features, including calcification, tortuous morphology, and long lesion length, whereas patient demographics were similar. Re-attempted CTO lesions required complex procedures, including the retrograde approach (55.9 vs. 13.9%, P
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- 2017
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24. Use of Proprotein Converse Subtilisin/Kexin Type 9 Inhibitor to Treat Cholesterol Crystal Embolisms after Catheterization: A Report of Three Cases.
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Yusuke Tomoi, Yoshimitsu Soga, Kazuaki Imada, Kenji Kodama, Tomonori Katsuki, Seiichi Hiramori, and Kenji Ando
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- 2022
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25. Development of a Close-Fitting Assistive Suit with Adjustable Structure for Arm and Back as Needed - e.z.UP®
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Chiaki Kanda, Kazuko Mishima, Eiichiro Tanaka, Yun Ting Liao, Toshifumi Ishioka, and Kenji Kodama
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0209 industrial biotechnology ,medicine.medical_specialty ,Manual handling ,medicine.diagnostic_test ,Computer science ,Heavy load ,02 engineering and technology ,Electromyography ,Back muscles ,03 medical and health sciences ,020901 industrial engineering & automation ,0302 clinical medicine ,Physical medicine and rehabilitation ,Arm muscle ,medicine ,030212 general & internal medicine ,Assistive suit - Abstract
The muscle injuries of manual handling workers, caused by the repeated motion and heavy load in the daily tasks, strongly influence their quality of life. To prevent muscle injuries in many occupations, a close-fitting assistive suit weighing 0.75 [kg] with the passive actuation mechanism and adjustable structures is proposed to assist not only the back muscle but the arm muscle of manual handling workers according to the user intention. An experiment with electromyography for measuring the muscle activities is conducted with six subjects to practically confirm the effectiveness of the suit. The experimental results revealed and proved that the proposed suit can successfully and appropriately assist not only the arm but also the back muscle with a lifting-up motion, simultaneously.
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- 2019
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26. Development of force-adjustable type of a lifting up assistive suit with magneto-rheological elastomer
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Eiichiro TANAKA, Kai ITO, Toshifumi ISHIOKA, Rie UEHARA, Chiaki KANDA, Takeo MIYAKE, and Kenji KODAMA
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- 2021
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27. Hydrogen analysis in diamond-like carbon by glow discharge optical emission spectroscopy
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Hikari Takahara, Ryoya Ishigami, Kenji Kodama, Atsushi Kojyo, Yoshihiro Oka, and Tatsuya Nakamura
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Materials science ,Hydrogen ,Silicon ,Diamond-like carbon ,010401 analytical chemistry ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Elastic recoil detection ,chemistry ,Sputtering ,Emission spectrum ,0210 nano-technology ,Carbon ,Spectroscopy ,Deposition (law) - Abstract
Glow discharge-optical emission spectroscopy (GD-OES) was evaluated for hydrogen analysis in diamond-like carbon (DLC) films. DLC film samples were prepared using the plasma-based ion-implantation and deposition method (PBIID). Their hydrogen contents were determined using elastic recoil detection analysis (ERDA). The hydrogen intensity obtained by GD-OES increased gradually concomitantly with increasing hydrogen contents at the lower hydrogen content region. However, the intensity increased drastically at the higher hydrogen content region of more than about 30 at%. When the hydrogen contents increased, the correlation between GD-OES hydrogen intensity and ERDA hydrogen contents was deviated from the linear relation obtained for hydrogen-implanted silicon samples as reference materials. The sputtering rate of the DLC sample was found to vary at the high H content region. A linear relationship was obtained between the hydrogen contents and GD-OES intensities corrected with the sputtering rate of samples.
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- 2016
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28. Magnetic Hyperthermia Using Self-Controlled Heating Elements Consisting of Fe-Al Milling Alloy Induces Cancer Cell Apoptosis while Preserving Skeletal Muscle
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Takuya Mori, Isao Kawahara, Kenji Kodama, Hirokazu Tanaka, Yukinori Taniguchi, Hiroyuki Kodama, Rina Fujiwara-Tani, Yi Luo, Yoshihiro Miyagawa, Kei Goto, Nobuyoshi Hosoito, and Hiroki Kuniyasu
- Subjects
Hyperthermia ,Male ,Necrosis ,Iron ,Apoptosis ,Pathology and Forensic Medicine ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Myosin ,medicine ,Alloys ,Autophagy ,Animals ,Muscle, Skeletal ,Molecular Biology ,Mice, Inbred BALB C ,Chemistry ,Magnetic Phenomena ,technology, industry, and agriculture ,Skeletal muscle ,Cell Biology ,General Medicine ,Hyperthermia, Induced ,equipment and supplies ,medicine.disease ,Muscle atrophy ,Muscular Atrophy ,medicine.anatomical_structure ,Magnetic hyperthermia ,030220 oncology & carcinogenesis ,Biophysics ,medicine.symptom ,030215 immunology ,Aluminum - Abstract
Necrosis-inducing anticancer drugs enhance high-mobility group box 1 (HMGB1) release during cell necrosis, and HMGB1-induced autophagy in skeletal muscle induces muscle atrophy. We evaluated the efficacy of magnetic hyperthermia therapy (MHT) using a low-energy magnetic field and self-controlled heating elements in tumor treatment. MHT-induced apoptosis by heating mouse subcutaneous tumors at 43°C using a heat-controlling iron-aluminum (Fe-Al) milling alloy. In contrast, MHT using Fe line-induced necrosis by heating to approximately 100°C. Furthermore, MHT with Fe-Al milling alloy reduced stemness. In hyperthermia using age line or Fe-Al milling alloy, both of them provided histological degeneration in skeletal muscle; however, qualitative differences were observed. MHT using Fe-line induced pronounced autophagy, decrease of myosin heavy chain content, and increase in serum HMGB1. In contrast, MHT using Fe-Al milling alloy induced heat shock protein 90 but no autophagy and decreased serum HMGB1. Therefore, MHT using Fe-Al milling alloy might be a good method for local treatment of tumors to reduce skeletal muscle atrophy.
- Published
- 2018
29. Development and Evaluation of a Worker-Wear Assistance Suit with the Adjustable and Concealable Elastic Structure for the Manual Handling Workers
- Author
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Toshifumi Ishioka, Yun-Ting Liao, Hee-Hyol Lee, Eiichiro Tanaka, and Kenji Kodama
- Subjects
medicine.medical_specialty ,Manual handling ,Shoulders ,Computer science ,05 social sciences ,Elbow ,030210 environmental & occupational health ,03 medical and health sciences ,0302 clinical medicine ,Physical medicine and rehabilitation ,medicine.anatomical_structure ,Lower back injury ,Arm muscle ,medicine ,0501 psychology and cognitive sciences ,human activities ,050107 human factors - Abstract
Due to worker injuries in industries such as nursing and construction, we have developed a tunable and concealable worker-wear assistance suit that consists of elastic belts to prevent arm muscle fatigue and injury in workers whose arms repeatedly perform motions upon their shoulders. According to the layout and the material of the belts, the suits may assist the user's arm without any electrical resources. To verify the feasibility and functionality of the layout and the structure of our proposed suits, simulations and experiments were employed. The simulation was conducted based on the average body dimensions of young Japanese people, and its results showed that the proposed suits may effectively assist the user's arm muscles. By measuring the muscles activities of six subjects wearing these suits and lifting a load of 10 kg, practically and concretely verifying the functionality of the suits, the results showed a 45% improvement ratio for their arm muscles. The proposed assistance suit can not only directly support and assist the elbow and shoulder j oint but also indirectly prevent lower back injury.
- Published
- 2018
- Full Text
- View/download PDF
30. Sulfur Chemical State and Chemical Composition of Insoluble Substance in Soft Rime, Hard Rime, and Snow Collected in Remote and Rural Areas in Japan Using Wavelength-dispersive X-ray Fluorescence
- Author
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Yuhei Yamamoto, Yoichi Kikuchi, Takashi Yamamoto, Kenji Kodama, Jun Nishimoto, and Shoji Imai
- Subjects
Hard rime ,aerosol ,Chemistry ,Speciation ,Soft rime ,010401 analytical chemistry ,X-ray fluorescence ,Fractionation ,snow ,010501 environmental sciences ,chemical shift ,Snow ,01 natural sciences ,WDXRF ,0104 chemical sciences ,Analytical Chemistry ,Aerosol ,Chemical state ,remote area ,sulfur ,Environmental chemistry ,wet deposition ,Chemical composition ,rime ,0105 earth and related environmental sciences - Abstract
Using a commercially available wavelength-dispersive X-ray fluorescence (WDXRF) spectrometer, the chemical composition and S-Kα spectrum of rime and snow samples collected in remote and rural areas of Japan were measured with a membrane filter sample technique to investigate the long-range transport of aerosol from the East Asian continent. Insoluble substances are derived into three categories: 1) conventional mineral origin (crustal substance), 2) urban dust origin (Fe-Zn-Ca) and 3) coal origin (S-As). Assuming that (i) S(VI) was found as a plaster-like substance in hard rime, depending on [Ca], and that (ii) S(-II) was found as non-crustal sulfur compounds, fractions of S(VI) and S(-II) in rime could be calculated as 35 ± 6 and 66 ± 7% by [Ca], which is in agreement with 32 ± 8 and 68 ± 8%, respectively, by the chemical shift of the S-Kα line. During a one-day meteorological event that included the accumulation of both rime and snow, differences to the snow-like content corresponded to characteristics typical of rime since the chemical compositions of rime also includes the composition of the snow. The fractions of 22 ± 12% of S(VI) and 76 ± 12% of S(-II), respectively, were found in rime. The fraction of S(-II) decreased from the Chugoku district towards the Shikoku district. Along the coast of the Japan Sea, the fraction of S(-II) decreased from Chugoku district toward the Northeast Japan. It can be proposed that other analytical techniques of S, Al, and Ca in that are favorable to this fractionation.
- Published
- 2018
31. Use of Soft Plasma Ionization Source at Evacuated Air Atmospheres in Time-of-Flight Mass Spectrometry to Suppress Fragmentation of Volatile Organic Compounds
- Author
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Hyunkook Park, Ryo Yoshiie, Kenji Kodama, Ichiro Naruse, Yoko Nunome, Yasuaki Ueki, Kuniyuki Kitagawa, Sang C. Lee, and Kazuaki Wagatsuma
- Subjects
Chemical ionization ,Chemistry ,Analytical chemistry ,Direct electron ionization liquid chromatography–mass spectrometry interface ,Mass spectrometry ,Inductively coupled plasma mass spectrometry ,Spectroscopy ,Atomic and Molecular Physics, and Optics ,Ion source ,Electron ionization ,Analytical Chemistry ,Atmospheric-pressure laser ionization ,Ambient ionization - Abstract
This study describes a measuring system for mass spectrometry, consisting of a glow discharge ionization source for soft plasma ionization and a time-of-flight mass spectrometer, to detect toxic volatile organic compounds rapidly and easily. It is the most important to determine how the complicated fragmentation of such compounds can be suppressed to occur so as to recognize the mass spectra of the volatile organic compounds as their fingerprints. The novelty of this work is that the optimal discharge condition for the soft plasma ionization–time-of-flight mass spectrometer system could be selected, so that the parent mass peak of analyte molecules could be observed both with high sensitivity and with little or no fragmentation of them. Use of air gas at a pressure of 1000 Pa provided the most favorable result for these criteria, whereas, in a previous report, the soft plasma ionization source operating with argon at a pressure of 346 Pa had yielded additional mass peaks of the fragmented species...
- Published
- 2015
- Full Text
- View/download PDF
32. Depth profiling of graphite electrode in lithium ion battery using glow discharge optical emission spectroscopy with small quantities of hydrogen or oxygen addition to argon
- Author
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Atsushi Kojyo, Hironori Kobayashi, Kumi Shono, Yo Kobayashi, Kenji Kodama, Masahiro Shikano, Tatsuya Nakamura, and Hikari Takahara
- Subjects
Ion implantation ,Argon ,chemistry ,Hydrogen ,X-ray photoelectron spectroscopy ,Sputtering ,Analytical chemistry ,chemistry.chemical_element ,Oxygen ,Isotropic etching ,Spectroscopy ,Lithium-ion battery ,Analytical Chemistry - Abstract
Depth profiling and quantification using glow discharge optical emission spectroscopy (GD-OES) were applied to a graphite electrode in a lithium ion battery. To improve the measurement time and reliability beyond conventional argon discharge plasma, reactive sputtering with the respective addition of oxygen (0.50% v/v O2 in Ar) and hydrogen (1.00% v/v H2 in Ar) was investigated. Samples contained dispersed 0–5 wt% LiF or 0–0.5 wt% Li3PO4 in graphite electrodes. Adding oxygen to argon plasma increased the sputtering rate and the sensitivity in quantitative analysis of lithium drastically. That unexpected depth profile was obtained for graphite electrode samples possibly because chemical etching by oxygen was inhomogeneous. In contrast, adding hydrogen to argon plasma exhibited benefits both for depth profiling and for quantifying Li for graphite electrode samples with a shorter measurement time and higher sensitivity than that of conventional pure argon discharge. Molecular spectra showed strong C–H and C–C bands, suggesting that formation of volatile material fragments of CH and CC increased with hydrogen addition during measurements. Surface analysis results with SEM and XPS showed that redeposition of sputtered materials and Ar+ ion implantation that occurred in pure argon plasma were also suppressed.
- Published
- 2014
- Full Text
- View/download PDF
33. Development of the lift up assistance suit e.z.UP® by collaborating academic-industry
- Author
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Toshifumi Ishioka, Eiichiro Tanaka, Yun-Ting Liao, Chiaki Kanda, Kazuko Mishima, and Kenji Kodama
- Subjects
Engineering ,Aeronautics ,business.industry ,Lift (soaring) ,Muscle activity ,business - Published
- 2019
- Full Text
- View/download PDF
34. Effect of electrolytes on anodic oxidation of titanium for fabricating titanium dioxide photocatalyst
- Author
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Shinji Komiya, Naofumi Ohtsu, and Kenji Kodama
- Subjects
Materials science ,Anodizing ,Inorganic chemistry ,Metals and Alloys ,Oxide ,chemistry.chemical_element ,Surfaces and Interfaces ,Electrolyte ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,chemistry.chemical_compound ,Crystallinity ,chemistry ,law ,Titanium dioxide ,Materials Chemistry ,Photocatalysis ,Crystallization ,Titanium - Abstract
Anodic oxidation has recently been investigated for fabricating photocatalytic TiO2 layers on Ti substrates. However, the most effective electrolyte for obtaining a high-performance photocatalyst has not yet been determined. In this work, TiO2 layers were produced by anodizing a Ti substrate in electrolytes consisting of (NH4)2SO4, (NH4)3PO4, or (NH4)2O · 5B2O3, and their characteristics and photocatalytic activities were analyzed in detail. The choice of the electrolyte affected both the surface morphology and the crystallinity of the fabricated oxide layer. The incorporation of S, B, and P from the electrolytes into the oxide layers was identified, which was linked to the degree of crystallization. A methylene blue degradation test revealed that all the oxide layers fabricated in the present study could act as photocatalysts; however, their performances were different depending on the electrolyte used. This can be explained in terms of the difference in the crystallinity due to the influence of the incorporation of the various elements.
- Published
- 2013
- Full Text
- View/download PDF
35. Two-dimensional visualization of excitation temperature and chemical species in divertor plasmas: Trace CD molecules by chemical sputtering of fusion plasma reactor wall
- Author
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Shin Kajita, Noriyasu Ohno, Zhe Cui, Kuniyuki Kitagawa, Kenji Kodama, Mitsuaki Yoshimi, Masanori Yamamoto, and Qingchun Shen
- Subjects
Chemistry ,Divertor ,Analytical chemistry ,Atomic emission spectroscopy ,Balmer series ,Plasma ,Excitation temperature ,Analytical Chemistry ,Chemical species ,symbols.namesake ,Deuterium ,symbols ,Nuclear fusion ,Atomic physics ,Spectroscopy - Abstract
The divertor region is among the most important section of nuclear fusion reactors. In order to investigate the behavior of deuterium in divertor plasmas, emission profiles of the Balmer series lines of deuterium atoms, molecular bands of D 2 and CD intensities have been two-dimensionally visualized with a CCD camera fitted with a bandpass filter, using a test system, the Nagoya Divertor Simulator II (NAGDIS-II). It has been clarified that profiles of emission from deuterium atoms and excitation temperature varied significantly with changes of the discharge current. From profiles of the ratio of the atomic emission intensity to the deuterium molecular emission, the increase in the dissociation fraction of deuterium molecule with the increase of the discharge current has been confirmed. Two dimensional visualization of the divertor plasma is a promising method for studies in nuclear fusion science.
- Published
- 2013
- Full Text
- View/download PDF
36. Novel Gas Barrier SiOC Coating to PET Bottles through a Hot Wire CVD Method
- Author
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Atsushi Hotta, Shigeo Yasuhara, Kenji Kodama, and Masaki Nakaya
- Subjects
010302 applied physics ,Materials science ,Ethylene ,Article Subject ,Tantalum ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,Permeation ,021001 nanoscience & nanotechnology ,01 natural sciences ,Silane ,chemistry.chemical_compound ,chemistry ,Coating ,Gas barrier ,0103 physical sciences ,engineering ,Thin film ,Composite material ,0210 nano-technology - Abstract
In an attempt to enhance the gas barrier enhancement of plastic containers such as poly(ethylene terephthalate) bottles, a novel method was found using a hot wire CVD technique, where tantalum wire is heated and exposed to a gas flow of vinyl silane. The resultant SiOC thin film was confirmed to characteristically contain Si-Si bonds in its surface and demonstrate a remarkably and highly practical decrease of the permeation of various gas through poly(ethylene terephthalate) bottles.
- Published
- 2016
- Full Text
- View/download PDF
37. Surface-nitriding treatment of steels using microwave-induced nitrogen plasma at atmospheric pressure
- Author
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Atsushi Kojyo, Naofumi Ohtsu, Yamashita Noboru, Yukio Okamoto, Shigeo Sato, Kazuaki Wagatsuma, Kenji Kodama, and Yuuki Arai
- Subjects
Austenite ,education.field_of_study ,Materials science ,Atmospheric pressure ,Population ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Plasma ,Nitride ,Condensed Matter Physics ,Nitrogen ,Surfaces, Coatings and Films ,chemistry ,X-ray photoelectron spectroscopy ,education ,Nitriding - Abstract
A rapid surface-nitriding system using microwave-induced nitrogen plasma at atmospheric pressure was developed for modifying iron and steel surfaces. Since the conventional plasma nitriding technique requires a low-pressure atmosphere in the treatment chamber, the population of excited nitrogen molecules in the plasma is limited. Accordingly, several hours are required for nitriding treatment. By contrast, the developed nitriding system can use atmospheric-pressure plasma through application of the Okamoto cavity for excitation of nitrogen plasma. The high population of excited nitrogen molecules induced by the atmospheric-pressure plasma allowed the formation of a nitriding layer that was several micrometers thick within 1 min and produced an expanded austenite iron phase with a high nitrogen concentration close to the solubility limit on the iron substrate. In addition, the nitriding treatment on high-chromium steel was performed by introducing a reducing gas such as NH 3 and H 2 into the treatment chamber. While the nitriding reaction did not proceed in a simple N 2 atmosphere due to surface oxidation, the surface reduction induced by the NH 3 or H 2 gas promoted the nitriding reaction at the surface. These nitriding phenomena characteristics of the atmospheric-pressure plasma are discussed in this paper based on the effects of the specimen temperature and plasma atmosphere on the thickness, the chemical states, and the nitride compounds of the nitrided layer as investigated by X-ray diffraction, glow-discharge optical emission spectroscopy, and X-ray photoelectron spectroscopy.
- Published
- 2012
- Full Text
- View/download PDF
38. In-Situ Monitoring of Toxic Heavy Metals from RDF Combustion by Two-Dimensional Atomic Absorption Spectrometry
- Author
-
Akinori Yamamoto, Yuri Kunie, Kenji Kodama, Nelfa Desmira, and Kuniyuki Kitagawa
- Subjects
Cadmium ,General Chemical Engineering ,Analytical chemistry ,General Physics and Astronomy ,Energy Engineering and Power Technology ,chemistry.chemical_element ,General Chemistry ,Combustion ,law.invention ,Mercury (element) ,Adiabatic flame temperature ,Fuel Technology ,chemistry ,law ,Standard addition ,Vaporization ,Atomic absorption spectroscopy ,Refuse-derived fuel - Abstract
The method to visualize two-dimensional (2D) distributions of heavy metals in refuse-derived fuel (RDF) combustion flame by using 2D atomic absorption spectrometry (2D-AAS) was studied. In-situ monitoring of the heavy metal vaporization was performed to gather useful information on the reduction of their emissions. The RDF sample was burned on a burner with an O2/N2 gas mixture being supplied from the bottom. Easily vaporized metals such as mercury (Hg) and cadmium (Cd) present in the RDF flame were measured by 2D-AAS. In order to measure the atomic absorption of lead (Pb), a sub-burner supplying O2 was placed in the RDF flame. O2 reacts with unburned gases in the RDF flame, increasing the flame temperature locally. Consequently, atomic absorption of Pb became measurable, and its 2D profiles were obtained by mapping. In addition, quantitative analyses of Hg and Cd contained in the RDF were made using the standard addition method without any pretreatments.
- Published
- 2011
- Full Text
- View/download PDF
39. 25 Tesla pulsed-high-magnetic-field system for soft X-ray spectroscopy
- Author
-
Hiroyuki Nojiri, Koichi Kindo, Toyohiko Kinoshita, Misaki Hayashi, Tetsuya Nakamura, T. Hirono, Yasuo Narumi, and Kenji Kodama
- Subjects
Physics ,Soft x ray ,Radiation ,Field (physics) ,Condensed matter physics ,Magnetic circular dichroism ,Magnetism ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Paramagnetism ,Condensed Matter::Strongly Correlated Electrons ,Vacuum chamber ,Physical and Theoretical Chemistry ,Spectroscopy ,High magnetic field - Abstract
We have developed a 25 T pulsed high magnetic field system for soft X-ray Magnetic Circular Dichroism: XMCD. The ultra-high vacuum chamber with a pulse magnet coil is installed. By using a newly developed bipolar capacitor bank, the XMCD of paramagnetic Gd2O3 at the M5 and the M4 edges was clearly observed at low temperatures. The present system is capable of measuring XMCD of field induced moments in various compounds including paramagnets and antiferromagnets.
- Published
- 2011
- Full Text
- View/download PDF
40. Surface hardening of titanium by pulsed Nd:YAG laser irradiation at 1064- and 532-nm wavelengths in nitrogen atmosphere
- Author
-
Kenji Kodama, Naofumi Ohtsu, Kazuaki Wagatsuma, and Misao Yamane
- Subjects
Materials science ,business.industry ,General Physics and Astronomy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Nitride ,Condensed Matter Physics ,Laser ,Titanium nitride ,Hardness ,Surfaces, Coatings and Films ,law.invention ,chemistry.chemical_compound ,Optics ,chemistry ,law ,Nd:YAG laser ,Irradiation ,Laser power scaling ,Composite material ,business ,Titanium - Abstract
The surface hardness of titanium modified by laser irradiation at different wavelengths in nitrogen atmosphere was investigated. Further, surface characteristics such as morphology, chemical state, and chemical composition in the depth direction were also studied. The size and depth of the craters observed in the laser-irradiated spots increased monotonically with an increase in the laser power. Furthermore, the crater formed by the 532-nm laser was deeper than that formed by the 1064-nm laser for the same laser power. Laser power beyond a certain threshold value was required to obtain a titanium nitride layer. When the laser power exceeds the threshold value, a titanium nitride layer of a few tens of nanometers in thickness was formed on the substrate, whereas a titanium oxide layer containing small amounts of nitrogen was formed when the laser power is below the threshold value. Thus, it was shown that laser irradiation using appropriate laser parameters can successfully harden a titanium substrate, and the actual hardness of the titanium nitride layer, measured by nanoindentation, was approximately five times that of an untreated titanium surface.
- Published
- 2010
- Full Text
- View/download PDF
41. 2D Measurement of Edge Plasma Dynamics by Using High-Speed Camera Based on HeI Line Intensity Ratio Method
- Author
-
Shin Kajita, K. Miyamoto, Kenji Kodama, Kuniyuki Kitagawa, and Noriyasu Ohno
- Subjects
Electron density ,Tokamak ,Materials science ,High-speed camera ,business.industry ,Plasma ,Condensed Matter Physics ,law.invention ,Optics ,law ,Radiative transfer ,Electron temperature ,Emission spectrum ,business ,Radiant intensity - Abstract
In order to investigate dynamic plasma behaviors in scrape-off layer (SOL) regions, such as ELMs and plasma blobs, we have developed a 4-channel high-speed camera equipped with four interference filters to obtain 2D successive images of spectral intensity of He I emission lines at 667.8 nm, 706.5 nm and 728.1 nm in addition to HeII at 656.0 nm. By using calculated results based on a Collisional Radiative (CR) model for He, the intensity ratios of the He I lines (728.1/706.5 and 667.8/706.5), provides 2D distributions of the electron temperature and density. The 2D profiles of electron density and temperature reconstructed from 2D images of He I emission lines taken in a small tokamak, HYBTOK-II were compared with those measured with the triple probe in order to evaluate the accuracy of this diagnostics. Electron density and temperature measured with the 4-channel high-speed camera are in good agreement with those obtained with the triple probe (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
- Published
- 2010
- Full Text
- View/download PDF
42. Comparison of surface films formed on titanium by pulsed Nd:YAG laser irradiation at different powers and wavelengths in nitrogen atmosphere
- Author
-
Kazuaki Wagatsuma, Kuniyuki Kitagawa, Naofumi Ohtsu, and Kenji Kodama
- Subjects
Materials science ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Laser pumping ,Condensed Matter Physics ,Laser ,Titanium nitride ,Surfaces, Coatings and Films ,law.invention ,Titanium oxide ,chemistry.chemical_compound ,chemistry ,law ,Nd:YAG laser ,Laser power scaling ,Surface layer ,Titanium - Abstract
The nitridation of titanium (Ti) caused by a Q-switched Nd:YAG laser under nitrogen gas atmosphere was investigated in situ using X-ray photoelectron spectroscopy (XPS). A laser having a wavelength of 1064 nm and 532 nm (SHG mode) was irradiated on a titanium substrate in an atmosphere-controlled chamber, and the substrate was then transported to an XPS analysis chamber without exposing it to air. The characteristics of the surface layer strongly depend on the laser power. When the power is relatively low, a titanium dioxide layer containing a small amount of nitrogen is formed on the substrate. Laser irradiation beyond a certain laser power is required to obtain a stoichiometric titanium nitride (TiN) layer. A TiN layer and an oxynitride layer with a TiO x N y -like structure are formed as the topmost and the lower surface layer, respectively, when the laser power exceeds this threshold value. The threshold laser power strongly depends on the wavelength of the laser, and this threshold value for the 532-nm laser is quite lower than that for the 1064-nm laser.
- Published
- 2010
- Full Text
- View/download PDF
43. Development of a Worker-Wear Assistance Suit with Tunable and Concealable Elastic Structure
- Author
-
Toshifumi Ishioka, Yun-Ting Liao, Eiichiro Tanaka, Hee-Hyol Lee, and Kenji Kodama
- Subjects
Engineering ,business.industry ,Structure (category theory) ,Mechanical engineering ,Development (differential geometry) ,business - Published
- 2018
- Full Text
- View/download PDF
44. Two-dimensional observation of excited atoms and ions and excitation temperature in inductively coupled plasma using newly developed four channel spectrovideo camera
- Author
-
Kuniyuki Kitagawa, Zhe Cui, Hiroyuki Oyama, and Kenji Kodama
- Subjects
Argon ,Materials science ,chemistry.chemical_element ,Excitation temperature ,Condensed Matter Physics ,law.invention ,Ion ,chemistry ,Physics::Plasma Physics ,law ,Excited state ,Inductively coupled plasma atomic emission spectroscopy ,Physics::Atomic and Molecular Clusters ,Electrical and Electronic Engineering ,Atomic physics ,Inductively coupled plasma ,Inductively coupled plasma mass spectrometry ,Monochromator - Abstract
A four-channel spectrovideo camera was developed and applied to the measurement of spatially and spectrally resolved profiles of atomic and ionic emission in an inductively coupled plasma (ICP). Spatial distributions of argon and chromium atoms and iron ions in ICP were visualized successfully. The excitation temperature profiles of argon, chromium, and iron in ICP were also successfully constructed on the basis of the two-line method. The excitation temperature profiles obtained with a monochromator and the spectrovideo camera were in fairly good agreement.
- Published
- 2010
- Full Text
- View/download PDF
45. Measurement of two-dimensional distribution profile of lead in a flame by planar laser-induced fluorescence spectroscopy
- Author
-
Kuniyuki Kitagawa and Kenji Kodama
- Subjects
Materials science ,Number density ,Waste management ,Planar laser-induced fluorescence ,Oxidizing agent ,Analytical chemistry ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Spectroscopy ,Combustion ,Refuse-derived fuel ,Fluorescence spectroscopy ,Adiabatic flame temperature - Abstract
Producing refuse-derived fuel (RDF) is one of the most effective measures of refuse treatment. However, RDF often consists of high level of lead. To reduce lead emission during combustion, understanding of lead behaviors in flames is required. In this study, we have applied planar laser-induced fluorescence spectroscopy to detect lead not only in a non-luminous methane–air flame, but also in a luminous RDF flame. In a methane–air flame, the number density of Pb atoms does not depend on the flame temperature, but also on the combustion environments. In RDF flames, because of acceleration of oxidizing process of Pb, Pb fluorescence profile obtained at 25% O2 became weaker than that at 20% O2.
- Published
- 2009
- Full Text
- View/download PDF
46. X-ray photoelectron spectroscopic study on surface reaction on titanium by laser irradiation in nitrogen atmosphere
- Author
-
Kuniyuki Kitagawa, Naofumi Ohtsu, Kazuaki Wagatsuma, and Kenji Kodama
- Subjects
Materials science ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Substrate (electronics) ,Condensed Matter Physics ,Laser ,Titanium nitride ,Surfaces, Coatings and Films ,law.invention ,Titanium oxide ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,chemistry ,law ,Surface layer ,Layer (electronics) ,Titanium - Abstract
The surface reaction on titanium due to pulsed Nd:YAG laser irradiation in a nitrogen atmosphere was investigated using X-ray photoelectron spectroscopy (XPS). The laser, with a wavelength of 532 nm (SHG mode), was irradiated on a titanium substrate in an atmosphere-controlled chamber, and then the substrate was transported to an XPS analysis chamber without exposure to air. This in situ XPS technique makes it possible to clearly observe the intrinsic surface reaction. The characteristics of the surface layer strongly depend on the nitrogen gas pressure. When the pressure is 133 kPa, an oxynitride and a stoichiometric titanium nitride form the topmost and lower surface layers on the titanium substrate, respectively. However, only a nonstoichiometric titanium oxide layer containing a small amount of nitrogen is formed when the pressure is lower than 13.3 kPa. Repetition of laser shots promotes the formation of the oxide layer, but the formation is completed within a few laser shots. After the initial structure is formed, the chemical state of the surface layer is less influenced by the repetition of laser shots.
- Published
- 2009
- Full Text
- View/download PDF
47. Spectrochemical Analysis in Flames
- Author
-
Kenji Kodama and Kuniyuki Kitagawa
- Subjects
Materials science - Published
- 2008
- Full Text
- View/download PDF
48. Distribution of the magnetic scattering amplitudes in the Fe/Cu multilayer investigated by resonant magnetic diffraction with circularly polarized hard X-rays
- Author
-
Takuo Ohkochi, Kenji Kodama, Nobuyoshi Hosoito, Yuichi Hayasaki, and Koichi Ishibashi
- Subjects
Diffraction ,Quantitative Biology::Neurons and Cognition ,Chemistry ,General Chemistry ,Condensed Matter Physics ,Epitaxy ,Molecular physics ,Scattering amplitude ,Crystallography ,Distribution (mathematics) ,X-ray magnetic circular dichroism ,Moment (physics) ,Proximity effect (audio) ,General Materials Science ,Layer (electronics) - Abstract
Resonant X-ray magnetic diffraction profiles were measured for an epitaxial Fe/Cu multilayer using circularly polarized X-rays near the Fe and Cu K-edges. Diffraction intensities were compared with those obtained from the theoretical and empirical models. It is found that the interface Fe moment is reduced to 70% of the inner-layer moment. Concerning the Cu layer, the observed energy dependence of the magnetic diffraction intensities is consistent with that derived from the first-principle band calculation, indicating that magnetic proximity effect in the Cu layer is confined within a few atomic layers near the interface.
- Published
- 2007
- Full Text
- View/download PDF
49. Rotation of a Gd Moment Vector in an Fe/FeGd/Fe Trilayer Observed by Hysteresis Measurements of the Resonant X-ray Magnetic Reflectivity
- Author
-
Kenji Kodama and Nobuyoshi Hosoito
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Field (physics) ,Scattering ,Magnetic circular dichroism ,General Engineering ,General Physics and Astronomy ,Magnetic field ,Condensed Matter::Materials Science ,Magnetization ,Hysteresis ,Perpendicular ,Specular reflection - Abstract
We have developed an experimental technique to measure element-specific hysteresis loops of films consisting of a few layers on the thick substrate by resonant X-ray magnetic scattering. The hysteresis loops of Gd in the Fe/FeGd/Fe trilayer are obtained by measuring magnetic field dependence of the magnetic specular scattering intensity at a fixed scattering angle. The Gd magnetization is obtained as a vector from the measurements in two experimental geometries with applied field parallel and perpendicular to the X-ray propagation. This technique can be applied more widely than the usual hysteresis measurements by X-ray magnetic circular dichroism because it requires no X-ray transmission through the sample.
- Published
- 2007
- Full Text
- View/download PDF
50. Development of the Three-Electrode Hollow Cathode Glow Discharge Lamp and Its Emission Characteristics
- Author
-
Kenji Kodama and Kazuaki Wagatsuma
- Subjects
Glow discharge ,Materials science ,law ,Electrode ,Analytical chemistry ,Cathode ,Analytical Chemistry ,Atomic emission spectrometry ,law.invention - Abstract
グロー放電発光分析法において,通常では不可能な試料のスパッタリング過程とプラズマ中での励起過程を独立して制御することを目的として,新しいグロー放電管の試作を行い,その分光特性について検討を行った.プラズマの点灯,試料のスパッタリング双方に異なる周波数で変調法を適用し,高速フーリエ変換器を用いて発光信号の周波数分離を行った.スパッタリング時に印加する電圧を適正に調整し,かつスパッタリング時の周波数に着目して信号を取り出すことにより,プラズマガス成分はほとんど検出されない発光信号を取り出すことに成功した.本手法はプラズマガス中の不純物元素に影響されない,新たな発光分析法として有望であると考えられる.
- Published
- 2006
- Full Text
- View/download PDF
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