222 results on '"Hiroo Kato"'
Search Results
2. A case of reexpansion pulmonary edema and acute pulmonary thromboembolism associated with diffuse large B-cell lymphoma treated with venovenous extracorporeal membrane oxygenation
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Toyoaki Murohara, Yukari Goto, Yasuko K Bando, Takahiko Sato, Tasuku Kuwayama, Naoyuki Matsuda, Masayuki Ozaki, Daisuke Kasugai, Kenji Furusawa, Reina Ozaki, Yuma Yasuda, Toru Kondo, Yoshihito Arao, Michiko Higashi, Hideo Oishi, Hiroaki Hiraiwa, Takahiro Okumura, Shingo Kazama, Naruhiro Jingushi, Hiroo Kato, Hitoshi Kiyoi, Atsushi Numaguchi, Kazuyuki Shimada, Takanori Yamamoto, Yuki Kimura, Naoki Shibata, Genki Nakamura, Hiroaki Ogawa, Shogo Yamaguchi, and Ryota Morimoto more...
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medicine.medical_specialty ,Lung ,business.industry ,Pleural effusion ,medicine.medical_treatment ,Case Report ,030204 cardiovascular system & hematology ,medicine.disease ,Pulmonary edema ,Right pulmonary artery ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,Effusion ,Respiratory failure ,Internal medicine ,Extracorporeal membrane oxygenation ,medicine ,Cardiology ,030212 general & internal medicine ,Thrombus ,Cardiology and Cardiovascular Medicine ,business - Abstract
A 37-year-old man diagnosed with diffuse large B-cell lymphoma two weeks previously, visited our emergency department with sudden dyspnea. He had a severe respiratory failure with saturated percutaneous oxygen at 80% (room air). Chest radiography showed a large amount of left pleural effusion. After 1000 mL of the effusion was urgently drained, reexpansion pulmonary edema (RPE) occurred. Despite ventilator management, oxygenation did not improve and venovenous extracorporeal membrane oxygenation (VV-ECMO) was initiated in the intensive care unit. The next day, contrast-enhanced computed tomography showed a massive thrombus in the right pulmonary artery, at this point the presence of pulmonary thromboembolism (PTE) was revealed. Fortunately, the patient’s condition gradually improved with anticoagulant therapy and VV-ECMO support. VV-ECMO was successfully discontinued on day 4, and chemotherapy was initiated on day 8. We speculated the following mechanism in this case: blood flow to the right lung significantly reduced due to acute massive PTE, and blood flow to the left lung correspondingly increased, which could have caused RPE in the left lung. Therefore, our observations suggest that drainage of pleural effusion when contralateral blood flow is impaired due to acute PTE may increase the risk of RPE. more...
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- 2021
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3. Association between splenic volume and pulsatility index in patients with left ventricular assist devices
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Toyoaki Murohara, Akinori Sawamura, Shogo Yamaguchi, Kazuro Fujimoto, Yoshihito Arao, Hideo Oishi, Kenji Furusawa, Hiroaki Hiraiwa, Toru Kondo, Ryota Morimoto, Yuki Kimura, Naoki Shibata, Tasuku Kuwayama, Masato Mutsuga, Takahiro Okumura, Akihiko Usui, Shingo Kazama, and Hiroo Kato more...
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Male ,medicine.medical_specialty ,Biomedical Engineering ,Medicine (miscellaneous) ,Hemodynamics ,Bioengineering ,Spleen ,Blood volume ,030204 cardiovascular system & hematology ,Pulsatility index ,Severity of Illness Index ,030218 nuclear medicine & medical imaging ,Biomaterials ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Humans ,Medicine ,In patient ,Assisted Circulation ,Retrospective Studies ,Heart Failure ,Blood Volume Determination ,business.industry ,Organ Size ,General Medicine ,Cone-Beam Computed Tomography ,Middle Aged ,medicine.disease ,medicine.anatomical_structure ,Pulsatile Flow ,Heart failure ,Cardiology ,Female ,Heart-Assist Devices ,business ,Volume (compression) - Abstract
The spleen serves as a blood volume reservoir for systemic volume regulation in heart failure (HF) patients. Changes are seen in spleen size in advanced HF patients after left ventricular assist device (LVAD) implantation. The pulsatility index (PI) is an indicator of native heart contractility with hemodynamic changes in patients using LVAD. We hypothesized that the splenic volume was associated with the PI, reflecting the hemodynamics in advanced HF patients with LVADs. Herein, we investigated the relationship between splenic volume and PI in these patients. Forty-four patients with advanced HF underwent implantation of HeartMate II® (Abbott, Chicago, IL, USA) as a bridge to heart transplantation at the Nagoya University Hospital between October 2013 and June 2019. The data of 27 patients (21 men, median age 46 years) were analyzed retrospectively. All patients underwent blood tests, echocardiography, right heart catheterization, and computed tomography (CT). Spleen size was measured via CT volumetry; the splenic volume (median: 190 mL) correlated with right arterial pressure ( r = 0.431, p = 0.025) and pulmonary capillary wedge pressure ( r = 0.384, p = 0.048). On multivariate linear regression analysis, the heart rate (β = −0.452, p = 0.003), pump power (β = −0.325, p = 0.023), and splenic volume (β = 0.299, p = 0.038) were independent determinants of PI. The splenic volume was associated with PI, reflecting the cardiac preload in advanced HF patients with LVADs. Thus, spleen measurement using CT may help estimate the systemic volume status and understand the hemodynamic conditions in LVAD patients. more...
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- 2020
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4. Efficacy of Pulmonary Artery Pulsatility Index as a Measure of Right Ventricular Dysfunction in Stable Phase of Dilated Cardiomyopathy
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Yoshihito Arao, Hiroaki Hiraiwa, Ryota Morimoto, Hideo Oishi, Naoki Shibata, Shingo Kazama, Hiroo Kato, Shogo Yamaguchi, Yuki Kimura, Kenji Furusawa, Toru Kondo, Tasuku Kuwayama, Takahiro Okumura, and Toyoaki Murohara more...
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Adult ,Cardiomyopathy, Dilated ,Male ,Cardiac Catheterization ,medicine.medical_specialty ,medicine.drug_class ,Ventricular Dysfunction, Right ,Hemodynamics ,Kaplan-Meier Estimate ,Pulmonary Artery ,030204 cardiovascular system & hematology ,03 medical and health sciences ,0302 clinical medicine ,Risk Factors ,medicine.artery ,Internal medicine ,medicine ,Natriuretic peptide ,Humans ,030212 general & internal medicine ,Aged ,Retrospective Studies ,Ejection fraction ,business.industry ,Hazard ratio ,Stroke Volume ,Dilated cardiomyopathy ,General Medicine ,Middle Aged ,Prognosis ,medicine.disease ,medicine.anatomical_structure ,Echocardiography ,Pulsatile Flow ,Heart failure ,Pulmonary artery ,Ventricular Function, Right ,Cardiology ,Vascular resistance ,Female ,Cardiology and Cardiovascular Medicine ,business ,Follow-Up Studies - Abstract
BACKGROUND Right ventricular dysfunction (RVD) in the setting of left ventricular (LV) myocardial damage is a major cause of morbidity and mortality, and the pulmonary artery pulsatility index (PAPi) is a novel hemodynamic index shown to predict RVD in advanced heart failure. However, it is unknown whether PAPi can predict the long-term prognosis of dilated cardiomyopathy (DCM) even in the mild to moderate phase. This study aimed to assess the ability of PAPi to stratify DCM patients without severe symptoms.Methods and Results:Between April 2000 and March 2018, a total of 162 DCM patients with stable symptoms were evaluated, including PAPi, and followed up for a median of 4.91 years. The mean age was 50.9±12.6 years and the mean LV ejection fraction (EF) was 30.5±8.3%. When divided into 2 groups based on median value of PAPi (low, L-PAPi [ more...
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- 2020
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5. Aortic insufficiency associated with Impella that required surgical intervention upon implantation of the durable left ventricular assist device
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Ryota Morimoto, Hideo Oishi, Tasuku Kuwayama, Naoki Shibata, Masato Mutsuga, Kazuro Fujimoto, Shogo Yamaguchi, Shingo Kazama, Hiroo Kato, Yuki Kimura, Akinori Sawamura, Akihiko Usui, Takahiro Okumura, Yoshihito Arao, Hiroaki Hiraiwa, Toru Kondo, Toyoaki Murohara, and Ken-ichi Hirano more...
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Adult ,Male ,Aortic valve ,medicine.medical_specialty ,Time Factors ,Percutaneous ,medicine.medical_treatment ,Aortic Valve Insufficiency ,0206 medical engineering ,Shock, Cardiogenic ,Biomedical Engineering ,Medicine (miscellaneous) ,02 engineering and technology ,030204 cardiovascular system & hematology ,Biomaterials ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Humans ,Impella ,Heart transplantation ,business.industry ,Cardiogenic shock ,medicine.disease ,020601 biomedical engineering ,Surgery ,Cardiac surgery ,Treatment Outcome ,medicine.anatomical_structure ,Aortic Valve ,Ventricular assist device ,Heart Transplantation ,Heart-Assist Devices ,Cardiology and Cardiovascular Medicine ,Complication ,business - Abstract
The Impella is an axial-flow percutaneous ventricular assist device for cardiogenic shock. In this report, we describe two patients who developed aortic insufficiency (AI) associated with Impella and required surgical intervention upon implantation of the durable left ventricular assist device (LVAD). Both patients presented with cardiogenic shock and underwent insertion of Impella 5.0 as a bridge to decision. The cardiac function in these patients did not improve and obtaining approval for heart transplantation required time. They were managed with Impella for 91 and 98 days, respectively. In both cases, moderate AI that was not present before Impella insertion was observed when the Impella was removed. Therefore, we performed aortic valve closure to control the AI during durable LVAD implantation. In patients with durable LVAD implantation, AI may occur and progress after the operation in several cases. Aortic valve surgery is often performed to prevent deterioration of AI, especially in patients with AI before the surgery. Hence, AI is an important complication following Impella device implantation as a bridge to decision. Careful observation of AI is essential when the Impella is removed as the evaluation of AI by echocardiogram during Impella management is cumbersome because of device-generated artifacts. more...
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- 2020
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6. Pulmonary artery pressure may be a predictor of closed aortic valve in patients managed by venoarterial extracorporeal membrane oxygenation
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Toru Kondo, Tasuku Kuwayama, Hideo Oishi, Takahiro Okumura, Yoshihito Arao, Hiroaki Hiraiwa, Shogo Yamaguchi, Akinori Sawamura, Toyoaki Murohara, Hiroo Kato, Ryota Morimoto, Tomoaki Haga, and Tsuyoshi Yokoi more...
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Adult ,Male ,Aortic valve ,medicine.medical_specialty ,Time Factors ,medicine.medical_treatment ,Shock, Cardiogenic ,Biomedical Engineering ,Medicine (miscellaneous) ,Blood Pressure ,Bioengineering ,Pulmonary Artery ,030204 cardiovascular system & hematology ,Ventricular Function, Left ,Biomaterials ,Young Adult ,03 medical and health sciences ,Extracorporeal Membrane Oxygenation ,0302 clinical medicine ,medicine.artery ,Internal medicine ,medicine ,Extracorporeal membrane oxygenation ,Humans ,In patient ,030212 general & internal medicine ,Retrospective Studies ,Intra-Aortic Balloon Pumping ,business.industry ,Cardiogenic shock ,Stroke Volume ,General Medicine ,Middle Aged ,medicine.disease ,medicine.anatomical_structure ,Aortic Valve ,Heart failure ,Pulmonary artery ,Cardiology ,Female ,business - Abstract
In the management of venoarterial extracorporeal membrane oxygenation, some patients present persistently closed aortic valve. However, little is known about the variables that contribute to persistently closed aortic valve. We investigated the factors that could predict persistently closed aortic valve at the time of venoarterial extracorporeal membrane oxygenation initiation. We investigated 17 patients who presented closed aortic valve immediately after the introduction of venoarterial extracorporeal membrane oxygenation. Patients who presented closed aortic valve 24 h after introduction of venoarterial extracorporeal membrane oxygenation were defined as the Closed-AV group (n = 8), while those whose aortic valve remained opened after 24 h were defined as the Open-AV group (n = 9). All patients were managed by concomitant use of intra-aortic balloon pumping. At baseline, there were no significant differences between mean arterial blood pressure, central venous pressure, and left ventricular ejection fraction. However, Closed-AV group had significantly lower mean pulmonary artery pressure and pulmonary artery pulse pressure compared to those of Open-AV group (mean pulmonary artery pressure: 15 ± 6 mmHg vs 25 ± 8 mmHg, p = 0.01; pulmonary artery pulse pressure: 3 ± 2 mmHg vs 8 ± 3 mmHg, p more...
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- 2020
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7. Giant cell myocarditis with central diabetes insipidus: A case report
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Tasuku Kuwayama, Hiroo Kato, Yoshihito Arao, Hiroaki Hiraiwa, Akinori Sawamura, Takahiro Okumura, Masato Nakaguro, Tomoaki Haga, Toru Kondo, Tsuyoshi Yokoi, Yoshie Shimoyama, Shogo Yamaguchi, Ryota Morimoto, Hideo Oishi, and Toyoaki Murohara more...
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medicine.medical_specialty ,Myocarditis ,Hypophysitis ,business.industry ,Sinus tachycardia ,Cardiogenic shock ,030204 cardiovascular system & hematology ,medicine.disease ,Ventricular tachycardia ,Article ,03 medical and health sciences ,0302 clinical medicine ,Polyuria ,Internal medicine ,Diabetes insipidus ,cardiovascular system ,medicine ,Cardiology ,Dobutamine ,030212 general & internal medicine ,medicine.symptom ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
A 51-year-old male, previously diagnosed with central diabetes insipidus due to lymphocytic hypophysitis, presented with fever and dyspnea for 1 week. On arrival, he exhibited hypotension (85/60 mmHg) and sinus tachycardia (110 bpm). His electrocardiogram revealed mild ST elevation on V2–V4. Echocardiography indicated a near-normal (50%) left ventricular ejection fraction (LVEF), although the inferior wall of the left ventricle exhibited severe hypokinesis. Fulminant myocarditis and circulatory insufficiency were suspected, and treatment with dobutamine, 3 μg/kg/min, was started. His LVEF gradually decreased to 20%. On day 17, he developed cardiogenic shock due to ventricular tachycardia and underwent peripheral venous–arterial extracorporeal membrane oxygenation and intra-aortic balloon pumping. Although he did not exhibit polyuria, intravenous vasopressin infusion (0.5 U/h) was performed to maintain normonatremia. Endomyocardial biopsy results revealed the infiltration of scattered giant cells (GCs) and extensive lymphocytes. Despite immunosuppressive therapy (methylprednisolone and cyclosporine), his cardiac function did not recover. On day 36, he received a biventricular assist device; however, he died on day 47 due to the progression of sepsis and multiple organ failure. We speculate that a deficient expression of programmed cell death protein-1 was the cause of both GC myocarditis and lymphocytic hypophysitis. more...
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- 2020
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8. LSI-CAD Programs on Parallel Inference Machine.
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Hiroshi Date, Yukinori Matsumoto, Kouichi Kimura, Kazuo Taki, Hiroo Kato, and Masahiro Hoshi
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- 1992
9. Early Blood Pressure Reduction by Intravenous Vasodilators Is Associated With Acute Kidney Injury in Patients With Hypertensive Acute Decompensated Heart
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Tasuku Kuwayama, Shogo Yamaguchi, Tomoaki Haga, Ryota Morimoto, Tsuyoshi Yokoi, Akinori Sawamura, Masahiro Nakatochi, Hiroo Kato, Yoshihito Arao, Hiroaki Hiraiwa, Toyoaki Murohara, Hideo Oishi, Toru Kondo, and Takahiro Okumura more...
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Male ,medicine.medical_specialty ,Time Factors ,Acute decompensated heart failure ,Vasodilator Agents ,Blood Pressure ,030204 cardiovascular system & hematology ,Risk Assessment ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Japan ,Risk Factors ,Internal medicine ,Humans ,Medicine ,030212 general & internal medicine ,Antihypertensive Agents ,Aged ,Retrospective Studies ,Aged, 80 and over ,Heart Failure ,Creatinine ,business.industry ,Incidence ,Incidence (epidemiology) ,Acute kidney injury ,General Medicine ,Odds ratio ,Acute Kidney Injury ,Middle Aged ,medicine.disease ,Confidence interval ,Treatment Outcome ,Blood pressure ,chemistry ,Concomitant ,Acute Disease ,Hypertension ,Injections, Intravenous ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
BACKGROUND Intravenous vasodilators are commonly used in patients with hypertensive acute decompensated heart failure (ADHF), but little is known about their optimal use in blood pressure (BP) management to avoid acute kidney injury (AKI). The purpose of this study was to investigate the association between systolic BP (SBP) changes and the incidence of AKI in patients with hypertensive ADHF.Methods and Results:Post-hoc analysis was performed on a prospectively enrolled cohort. We investigated 245 patients with ADHF and SBP >140 mmHg on arrival (mean age, 76 years; 40% female). We defined "SBP-fall" as the maximum percent reduction in SBP 6 h after intravenous treatment. AKI was defined as serum creatinine (SCr) ≥0.3 mg/dL, or urine output more...
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- 2019
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10. Left Ventricular Relaxation Half-Time as a Predictor of Cardiac Events in Idiopathic Dilated Cardiomyopathy and Hypertrophic Cardiomyopathy With Left Ventricular Systolic and/or Diastolic Dysfunction
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Kenji Fukaya, Shogo Yamaguchi, Kenji Furusawa, Tomoaki Haga, Akihiro Hirashiki, Tsuyoshi Yokoi, Yoshihito Arao, Toyoaki Murohara, Hideo Oishi, Hiroaki Hiraiwa, Takahiro Okumura, Tasuku Kuwayama, Ryota Morimoto, Hiroo Kato, Akinori Sawamura, and Toru Kondo more...
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Cardiomyopathy, Dilated ,Male ,Cardiac Catheterization ,medicine.medical_specialty ,Systole ,medicine.medical_treatment ,Cardiomyopathy ,Diastole ,Hemodynamics ,030204 cardiovascular system & hematology ,Ventricular Dysfunction, Left ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Idiopathic dilated cardiomyopathy ,medicine ,Humans ,030212 general & internal medicine ,Cardiac catheterization ,Relaxation (psychology) ,business.industry ,Hypertrophic cardiomyopathy ,Cardiomyopathy, Hypertrophic ,Middle Aged ,Prognosis ,medicine.disease ,Echocardiography, Doppler ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
Purpose: Diastolic dysfunction preceding systolic dysfunction is considered an important interaction in cardiomyopathy with poor prognosis. The aim of this study was to compare left ventricular (LV) isovolumic relaxation with the other parameters as a potential prognostic marker for patients with idiopathic dilated cardiomyopathy (IDC) and hypertrophic cardiomyopathy (HC). Methods: A total of 145 patients with IDC and 116 with HC were evaluated for hemodynamic parameters; LV pressure was directly measured by a micromanometer catheter, and relaxation half-time (T1/2) was used to determine LV isovolumic relaxation. The median follow-up period was 4.7 years. Results: The mean ages of the patients with IDC and HC were 52.0 ± 12.0 and 57.1 ± 12.4 years, respectively. Each patient group was further divided into 2 groups based on the median value of T1/2: (1), ファイル公開:2020-08-01 more...
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- 2019
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11. Prognostic impact of transcardiac gradient of follistatin-like 1 reflecting hemodynamics in patients with dilated cardiomyopathy
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Yuki Kimura, Naoki Shibata, Shogo Yamaguchi, Yoshihito Arao, Hiroaki Hiraiwa, Ryota Morimoto, Noriyuki Ouchi, Tasuku Kuwayama, Koji Ohashi, Shingo Kazama, Hiroo Kato, Hideo Oishi, Minako Tatsumi, Mikito Takefuji, Toru Kondo, Takahiro Okumura, and Toyoaki Murohara more...
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Cardiomyopathy, Dilated ,Male ,medicine.medical_specialty ,Follistatin ,Follistatin-Related Proteins ,medicine.drug_class ,medicine.medical_treatment ,Hemodynamics ,Ventricular Function, Left ,Internal medicine ,medicine ,Natriuretic peptide ,Humans ,Pulmonary wedge pressure ,Coronary sinus ,Cardiac catheterization ,Heart Failure ,Ejection fraction ,business.industry ,Area under the curve ,Dilated cardiomyopathy ,Stroke Volume ,Middle Aged ,medicine.disease ,Prognosis ,Cardiology ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background Follistatin-like 1 (FSTL1) is a myocyte-secreted glycoprotein that could play a role in myocardial maintenance in response to harmful stimuli. We investigated the association between serum FSTL1 levels, especially focused on transcardiac gradient and the hemodynamics, to explore the prognostic impact of FSTL1 levels in patients with dilated cardiomyopathy (DCM). Methods Thirty-two ambulatory patients with DCM (23 men; mean age 59 years) were prospectively enrolled. Blood samples were simultaneously collected from the aortic root (Ao), coronary sinus (CS), as well as from the peripheral vein during cardiac catheterization in stable conditions. The transcardiac gradient of FSTL1 was calculated by the difference between serum FSTL1 levels of CS and Ao (FSTL1CS-Ao). Patients were divided into two groups based on the median of FSTL1CS-Ao: Low FSTL1CS-Ao group, Results Mean left ventricular ejection fraction and median plasma B-type natriuretic peptide levels were 30.9% and 92.3 pg/mL, respectively. FSTL1CS-Ao was negatively correlated with pulmonary capillary wedge pressure (r = -0.400, p = 0.023). Kaplan-Meier survival analysis showed that event-free survival rate was significantly lower in the Low FSTL1CS-Ao group than in the High FSTL1CS-Ao group (p = 0.013). Cox regression analyses revealed that the transcardiac gradient of FSTL1 was an independent predictor for cardiac events. Receiver operating characteristic curve analysis showed that the cut-off value of FSTL1CS-Ao for the prediction of cardiac events was -4.09 ng/mL with sensitivity of 82% and specificity of 86% (area under the curve, 0.87). Conclusions Fifty percent of patients had negative transcardiac gradient of FSTL1. Reduced transcardiac gradient of FSTL1 might be a novel prognostic predictor in DCM patients with impaired hemodynamics. more...
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- 2021
12. Abstract 15519: The Prognostic Impact of Transcardiac Gradient of Follistatin-like 1 in Patients With Non-ischemic Dilated Cardiomyopathy
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Tasuku Kuwayama, Shogo Yamaguchi, Ryota Morimoto, Naoki Shibata, Toyoaki Murohara, Koji Ohashi, Yoshihito Arao, Hiroaki Hiraiwa, Hideo Oishi, Shingo Kazama, Hiroo Kato, Noriyuki Ouchi, Yuki Kimura, Toru Kondo, and Takahiro Okumura more...
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medicine.medical_specialty ,biology ,business.industry ,Cardiomyopathy ,Dilated cardiomyopathy ,medicine.disease ,Physiology (medical) ,Internal medicine ,medicine ,biology.protein ,Cardiology ,In patient ,Non ischemic ,Cardiology and Cardiovascular Medicine ,business ,Follistatin - Abstract
Introduction: Follistatin-like 1 (FSTL1) is secreted from various tissues including myocardium and could play a cardioprotective role against harmful stimuli. It has been shown that the expression of FSTL1 protein in patients with heart failure is higher than that in healthy subjects. However, little is known about the association between serum FSTL1 levels and the cardiac prognosis. Hypothesis: We hypothesized that the transcardiac gradient of FSTL1 reflect myocardial FSTL1 and is useful for predicting prognosis in patients with non-ischemic dilated cardiomyopathy (NIDCM). Methods: Thirty-two NIDCM patients were enrolled. Blood samples were simultaneously collected from the aortic root (Ao), coronary sinus (CS) as well as peripheral vein during cardiac catheterization. The transcardiac gradient of FSTL1 was calculated by the difference between serum FSTL1 levels of CS and Ao (FSTL1 CS-Ao ). Patients were divided into two groups at the median of FSTL1 CS-Ao : Low FSTL1 CS-Ao group, CS-Ao group, > 0 ng/mL. The primary endpoint of this study was the occurrence of a cardiac event, which was defined as a composite of cardiac deaths and unexpected hospitalizations for worsening heart failure. Results: The median plasma B type natriuretic levels and mean left ventricular ejection fraction in the Low and High FSTL1 CS-Ao groups were 91.9 (21.7 - 277.5) vs. 94.1 (59.1 - 236.5) pg/mL (P = 1.000) and 31.4 ± 6.5 vs. 30.5 ± 7.3 % (P = 0.714), respectively. FSTL1 CS-Ao was negatively correlated with pulmonary capillary wedge pressure (R = -0.400, P = 0.023), mean pulmonary artery pressure (R = -0.40, P = 0.023) and right atrial pressure (R = -0.41, P = 0.019). Kaplan-Meier analysis showed that event-free survival rate was significantly lower in the Low FSTL1 CS-Ao group (p=0.0126). Conclusions: Transcardiac gradient of FSTL1 is associated with hemodynamics and low transcardiac gradient of FSTL1 might be associated with poor prognosis in NIDCM patients. more...
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- 2020
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13. Associations between hemodynamic parameters at rest and exercise capacity in patients with implantable left ventricular assist devices
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Kazuro Fujimoto, Yoshihito Arao, Hiroaki Hiraiwa, Akihiko Usui, Akinori Sawamura, Tomoaki Haga, Hiroo Kato, Tasuku Kuwayama, Masato Mutsuga, Kenji Fukaya, Takahiro Okumura, Toru Kondo, Ryota Morimoto, Toyoaki Murohara, Hideo Oishi, Tsuyoshi Yokoi, and Shogo Yamaguchi more...
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Male ,medicine.medical_specialty ,Rest ,Biomedical Engineering ,Medicine (miscellaneous) ,Hemodynamics ,Bioengineering ,030204 cardiovascular system & hematology ,Biomaterials ,Cardiac Resynchronization Therapy ,03 medical and health sciences ,Hemoglobins ,0302 clinical medicine ,Oxygen Consumption ,Internal medicine ,Medicine ,Humans ,In patient ,030212 general & internal medicine ,Rest (music) ,Retrospective Studies ,Heart Failure ,Exercise Tolerance ,business.industry ,VO2 max ,Stroke Volume ,General Medicine ,Exercise capacity ,Middle Aged ,medicine.disease ,Heart failure ,Cardiology ,Exercise Test ,Ventricular Function, Right ,Female ,Hemoglobin ,Heart-Assist Devices ,business - Abstract
Background: Hemodynamic parameters at rest are known to correlate poorly with peak oxygen uptake (VO2) in heart failure. However, we hypothesized that hemodynamic parameters at rest could predict exercise capacity in patients with left ventricular assist device (LVAD), because LVAD pump rotational speed does not respond during exercise. Therefore, we investigated the relationships between hemodynamic parameters at rest (measured with right heart catheterization) and exercise capacity (measured with cardiopulmonary exercise testing) in patients with implantable LVAD. Methods: We performed a retrospective medical record review of patients who received implantable LVAD at our institution from November 2013 to December 2017. Results: A total of 20 patients were enrolled in this study (15 males; mean age, 45.8 years; median duration of LVAD support, 356 days). The mean peak VO2 and cardiac index (CI) were 13.5 mL/kg/min and 2.6 L/min/m2, respectively. CI and hemoglobin level were significantly associated with peak VO2 (CI: r = 0.632, p = 0.003; hemoglobin: r = 0.520, p = 0.019). In addition, pulmonary capillary wedge pressure, right atrial pressure, and right ventricular stroke work index were also significantly associated with peak VO2. In multiple linear regression analysis, CI and hemoglobin level remained independent predictors of peak VO2 (CI: β = 0.559, p = 0.006; hemoglobin: β = 0.414, p = 0.049). Conclusions: CI at rest and hemoglobin level are associated with poor exercise capacity in patients with LVAD. more...
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- 2020
14. Impact of predictive value of Fibrosis-4 index in patients hospitalized for acute heart failure
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Hideo Oishi, Shingo Kazama, Hiroo Kato, Takuya Sumi, Shogo Yamaguchi, Ryota Morimoto, Naoki Shibata, Toyoaki Murohara, Akinori Sawamura, Yoshihito Arao, Hiroaki Hiraiwa, Yuki Kimura, Kiyokazu Shimizu, Takahiro Okumura, Tasuku Kuwayama, and Toru Kondo more...
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Male ,medicine.medical_specialty ,030204 cardiovascular system & hematology ,Hepatic Diseases ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Medicine ,Humans ,In patient ,030212 general & internal medicine ,Fibrosis-4 index ,Aspartate Aminotransferases ,Aged ,Retrospective Studies ,Aged, 80 and over ,Heart Failure ,medicine.diagnostic_test ,business.industry ,Alanine Transaminase ,medicine.disease ,Prognosis ,Predictive value ,Fibrosis ,Quartile ,Heart failure ,Acute Disease ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,business ,Liver function tests ,Hepatic dysfunction - Abstract
Background Abnormalities in liver function tests commonly occur in patients with acute heart failure (AHF). The Fibrosis-4 (FIB4) index, a non-invasive and easily calculated marker, has been used for hepatic diseases and reflects adverse prognosis. It is not clearly established whether the FIB4 index at admission can predict adverse outcomes in patients with AHF. Methods and results From a multicenter AHF registry, we retrospectively evaluated 1162 consecutive patients admitted due to AHF (median age 78 [69–85] years and 702 patients [60.4%] were male). The FIB4 index at admission was calculated as: age (yrs) × aspartate aminotransferase [U/L]/(platelets count [103/μL] × √alanine aminotransferase [U/L]. The median value of the FIB4 index at admission was 2.79. All-cause mortality and rehospitalization due to HF at 12 months were investigated as a composite endpoint and occurred in 142 (12.2%) patients and 232 (20%) patients, respectively. Kaplan-Meyer analysis shows a significant increase in the composite endpoint from the first to fourth quartile group of the FIB4 index values (log-rank, p Conclusions Hepatic dysfunction evaluated with the FIB4 index at admission is a predictor of the composite endpoint of all-cause mortality and rehospitalization in AHF patients. more...
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- 2020
15. Usefulness of Plasma Branched-Chain Amino Acid Analysis in Predicting Outcomes of Patients with Nonischemic Dilated Cardiomyopathy
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Hideo Oishi, Yuki Kimura, Yoshihito Arao, Hiroaki Hiraiwa, Takahiro Okumura, Tasuku Kuwayama, Shogo Yamaguchi, Toru Kondo, Naoki Shibata, Shingo Kazama, Hiroo Kato, Ryota Morimoto, and Toyoaki Murohara more...
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Cardiac function curve ,Adult ,Cardiomyopathy, Dilated ,Male ,medicine.medical_specialty ,Angiotensin receptor ,Branched-chain amino acid ,030204 cardiovascular system & hematology ,Gastroenterology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Internal medicine ,Medicine ,Humans ,030212 general & internal medicine ,Amino Acids ,Aged ,Univariate analysis ,Ejection fraction ,business.industry ,Hazard ratio ,General Medicine ,Middle Aged ,Brain natriuretic peptide ,medicine.disease ,chemistry ,Echocardiography ,Heart failure ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
The metabolism of branched-chain amino acids (BCAAs) is reported to change in heart failure (HF) and correlate with cardiac function. However, the effect of BCAAs on HF remains controversial. We investigate the prognostic value of the plasma BCAA level in nonischemic dilated cardiomyopathy (NIDCM).This study enrolled 39 NIDCM patients, who underwent plasma amino acid (AA) analysis. The ratio of BCAAs to total AAs was calculated. All patients were divided into two groups at the median of BCAA/total AA ratio; high BCAA/total AA group (≥ 0.15, n = 20) and low BCAA/total AA group (< 0.15, n = 19). A cardiac event was defined as a composite of cardiac death, hospitalization for worsening HF, and lethal arrhythmia.The mean age was 51.1 ± 12.3 years and left ventricular ejection fraction (LVEF) was 32.7 ± 10.1%. In the low BCAA/total AA group, the body mass index and the total cholesterol level were lower than in the high BCAA/total AA group. The BCAA/total AA ratio was positively correlated with LVEF (r = 0.35, P = 0.031) and negatively correlated with brain natriuretic peptide (r = -0.37, P = 0.020). The low BCAA/total AA group had a lower cardiac event-free rate (5-year: 100% versus 73%; P = 0.019). In univariate analysis, angiotensin converting enzyme inhibitor or angiotensin II receptor blocker (hazard ratio: 0.045, P = 0.0014), hemoglobin (hazard ratio: 0.49 per 1 g/dL, P = 0.0022), and BCAA/total AA ratio < 0.15 (hazard ratio: not available, P = 0.0066) were major predictors for cardiac events.The BCAA/total AA ratio might be a useful predictor for future cardiac events in patients with NIDCM. more...
- Published
- 2020
16. Predictors of residual mitral regurgitation after left ventricular assist device implantation
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Kazuro Fujimoto, Shingo Kazama, Hiroo Kato, Yoshihito Arao, Hiroaki Hiraiwa, Toyoaki Murohara, Tasuku Kuwayama, Masato Mutsuga, Ryota Morimoto, Yuki Kimura, Takahiro Okumura, Shogo Yamaguchi, Toru Kondo, Hideo Oishi, Akihiko Usui, and Naoki Shibata more...
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Male ,medicine.medical_specialty ,medicine.medical_treatment ,Heart Ventricles ,Biomedical Engineering ,Medicine (miscellaneous) ,Bioengineering ,030204 cardiovascular system & hematology ,Biomaterials ,Prosthesis Implantation ,03 medical and health sciences ,0302 clinical medicine ,Japan ,Internal medicine ,medicine ,Humans ,cardiovascular diseases ,Cardiac Surgical Procedures ,Functional mitral regurgitation ,Retrospective Studies ,Heart Failure ,Mitral regurgitation ,Vena contracta ,business.industry ,Hemodynamics ,Mitral Valve Insufficiency ,General Medicine ,Middle Aged ,medicine.disease ,Prognosis ,Treatment Outcome ,030228 respiratory system ,Echocardiography ,Heart failure ,Ventricular assist device ,cardiovascular system ,Cardiology ,Female ,Heart-Assist Devices ,business - Abstract
Patients with advanced heart failure often have functional mitral regurgitation. Left ventricular assist device implantation improves functional mitral regurgitation through left ventricular unloading. However, residual mitral regurgitation after left ventricular assist device implantation leads to adverse outcomes, and whether patients need concomitant mitral valve surgery is not fully elucidated. Therefore, this study aimed to elucidate the predictors of residual mitral regurgitation and to describe the temporal changes in residual mitral regurgitation. We retrospectively enrolled 15 patients with implantable continuous-flow left ventricular assist device, who had significant mitral regurgitation on echocardiography before left ventricular assist device implantation. Three patients had residual mitral regurgitation (mitral regurgitation color jet area/left atrial area >0.2) 1 month after left ventricular assist device implantation. We investigated factors associated with residual mitral regurgitation and compared patients with or without residual mitral regurgitation. On univariate analysis, mitral valve tethering area and mitral regurgitation vena contracta before left ventricular assist device implantation were significantly associated with residual mitral regurgitation (odds ratio, 1.03; p = 0.036 and odds ratio, 10.45; p = 0.0087). One month after left ventricular assist device implantation, the mean pulmonary capillary wedge pressure and pulmonary artery pressure were higher in patients with residual mitral regurgitation (pulmonary capillary wedge pressure: 11.3 ± 3.5 vs 6.4 ± 3.4 mmHg, p = 0.029 and pulmonary artery pressure: 21.3 ± 4.0 vs 15.9 ± 3.3 mmHg, p = 0.023). However, the mitral regurgitation grading and hemodynamics were not significantly different 6 months after left ventricular assist device implantation. The hospitalization-free survival was not significantly different between the two groups. Mitral valve tethering area and mitral regurgitation vena contracta were predictors of residual mitral regurgitation. Residual mitral regurgitation improved until 6 months after left ventricular assist device implantation and might not affect the prognosis. more...
- Published
- 2020
17. Correlation between Photocalatytic Activity and Carrier Lifetime: Acetic Acid on Single-Crystal Surfaces of Anatase and Rutile TiO2
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Naoya Terashima, Kenichi Ozawa, Iwao Matsuda, Susumu Yamamoto, Ryu Yukawa, Hiroo Kato, Kazuhiko Mase, Yuto Natsui, and Ro-Ya Liu
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Anatase ,Materials science ,Surface photovoltage ,02 engineering and technology ,Carrier lifetime ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Crystal ,General Energy ,X-ray photoelectron spectroscopy ,Rutile ,Photocatalysis ,Physical and Theoretical Chemistry ,0210 nano-technology ,Single crystal - Abstract
Photocatalytic activity and lifetime of photoexcited carriers on well-defined single-crystalline anatase and rutile TiO2 surfaces with different surface orientation have been systematically studied by photoelectron spectroscopy. Photocatalytic activity, evaluated with reference to the photocatalytic degradation of acetic acid, has a positive and linear correlation with carrier lifetime at the crystal surface, which was determined by following the time evolution of the ultraviolet-induced surface photovoltage. This indicates that the carrier lifetime is a prime factor for the photocatalytic activity so that it can be viewed as the origin of the crystal-surface-orientation dependence of the photocatalytic activity. more...
- Published
- 2018
18. Non-Evaporable Getter (NEG) Coating Using Titanium and Palladium Vacuum Sublimation
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Shinya Ohno, Kensuke Tobishima, Tetsuya Miyazawa, Takashi Kikuchi, Kazuhiko Mase, Hiroo Kato, and Masashi Kurihara
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010302 applied physics ,Materials science ,Metallurgy ,Non-Evaporable Getter ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,01 natural sciences ,Vacuum sublimation ,chemistry ,Coating ,0103 physical sciences ,engineering ,Thin film ,0210 nano-technology ,Palladium ,Titanium - Published
- 2018
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19. Spleen size improvement in advanced heart failure patients using a left ventricular assist device
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Ryota Morimoto, Tasuku Kuwayama, Toyoaki Murohara, Toru Kondo, Yuki Kimura, Shogo Yamaguchi, Yoshihito Arao, Takahiro Okumura, Hiroaki Hiraiwa, Naoki Shibata, Shingo Kazama, Hiroo Kato, Akinori Sawamura, Hideo Oishi, and Kenji Furusawa more...
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Adult ,Male ,medicine.medical_specialty ,Cardiac Catheterization ,medicine.medical_treatment ,Biomedical Engineering ,Cardiac index ,Medicine (miscellaneous) ,Hemodynamics ,Bioengineering ,Blood volume ,Severity of Illness Index ,Biomaterials ,Internal medicine ,Intravascular volume status ,medicine ,Humans ,Pulmonary wedge pressure ,Retrospective Studies ,Heart Failure ,business.industry ,General Medicine ,Organ Size ,Middle Aged ,equipment and supplies ,medicine.disease ,medicine.anatomical_structure ,Treatment Outcome ,Ventricular assist device ,Heart failure ,Cardiology ,Vascular resistance ,Female ,Vascular Resistance ,Heart-Assist Devices ,business ,Tomography, X-Ray Computed ,Spleen - Abstract
The spleen has been recognized as an important organ that holds a reserve of 20% to 30% of the total blood volume. Spleen contraction and splenic volume reduction occur in patients with hypovolemic shock. However, the change in the spleen volume and the association between spleen size and hemodynamic parameters remain unclear in patients with advanced heart failure (HF) who need left ventricular assist device (LVAD) support. This study was performed to investigate the change in spleen size and the relationship between spleen size and hemodynamic parameters before and after LVAD implantation in patients with advanced HF. We enrolled 20 patients with advanced HF on LVAD support. All patients underwent right heart catheterization and computed tomography before and after LVAD implantation. The spleen size was measured by computed tomography volumetry. We excluded patients with a mean right atrial pressure (RAP) of 2.2 L/min/m2 before LVAD implantation. The splenic volume significantly increased from 160.6 ± 46.9 mL before LVAD implantation to 224.6 ± 73.5 mL after LVAD implantation (P < .001). Before LVAD implantation, there was a significant negative correlation between spleen volume and systemic vascular resistance (SVR). After LVAD implantation, however, there were significant correlations between spleen volume and the cardiac index, RAP, and pulmonary capillary wedge pressure despite the absence of a significant correlation between spleen volume and SVR. Furthermore, one patient developed reworsening HF because of LVAD failure due to pump thrombosis. In this case, the splenic volume was 212 mL before LVAD implantation and increased to 418 mL after LVAD implantation, although it decreased to 227 mL after LVAD failure. The spleen size may change depending on hemodynamics in patients with advanced HF with LVAD support, reflecting sympathetic nerve activity and the systemic volume status. more...
- Published
- 2019
20. A survival case of a young adult patient with ST-elevated myocardial infarction with high levels of lipoprotein(a)
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Ryota Morimoto, Hideyuki Tsuboi, Akinori Sawamura, Akihito Tanaka, Shogo Yamaguchi, Yoshihito Arao, Naoki Watanabe, Hiroaki Hiraiwa, Kenji Fukaya, Tasuku Kuwayama, Itsuro Morishima, Toru Kondo, Hideo Oishi, Takahiro Okumura, Toyoaki Murohara, Takayuki Mitsuda, Hiroo Kato, Hideki Ishii, Tomoaki Haga, and Tsuyoshi Yokoi more...
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medicine.medical_specialty ,Ejection fraction ,biology ,business.industry ,Lipoprotein(a) ,Chest pain ,medicine.disease ,Article ,medicine.anatomical_structure ,medicine.artery ,Internal medicine ,Right coronary artery ,biology.protein ,Cardiology ,Medicine ,Myocardial infarction ,medicine.symptom ,Renal artery ,Cardiology and Cardiovascular Medicine ,business ,Subclavian artery ,Artery - Abstract
A 23-year-old Japanese man presented to a nearby hospital with a complaint of chest pain. In terms of the risk factors for cardiovascular events, there were no abnormal findings in past medical examinations and no smoking history. The 12-lead electrocardiogram revealed ST-elevation in V1-V6, I, and aVL, and he was diagnosed with acute myocardial infarction. Emergency coronary angiography findings revealed total occlusion of the left main trunk and collateral vessels from the right coronary artery to the left anterior descending artery. He underwent emergency percutaneous coronary intervention and placement of drug-eluting stent under the support of venoarterial-extracorporeal membrane oxygenator (VA-ECMO). On day 8 after the onset, transthoracic echocardiography revealed that cardiac function improved with left ventricular ejection fraction from 10% to 20% and VA-ECMO was successfully removed. Alternatively, laboratory findings revealed abnormally high levels of serum lipoprotein(a) [Lp(a), 74 mg/dL] despite the normal levels of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride. In addition, computed tomography angiography revealed atherosclerosis and stenosis of internal and external carotid arteries, subclavian artery, and renal artery. The abnormally high levels of serum Lp(a) could influence systemic atherosclerosis as well as the onset of myocardial infarction in our young adult patient. more...
- Published
- 2019
21. Electron-Donor Dye Molecule on ZnO(101̅0), (0001), and (0001̅) Studied by Photoelectron Spectroscopy and X-ray Absorption Spectroscopy
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Kazuyuki Edamoto, Kazuhiko Mase, Masahiro Suzuki, Yuichi Sugizaki, Ryo Tochikubo, Kenichi Ozawa, and Hiroo Kato
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X-ray absorption spectroscopy ,Materials science ,Absorption spectroscopy ,Heterojunction ,Electron donor ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,Adsorption ,X-ray photoelectron spectroscopy ,Chemical bond ,chemistry ,Excited state ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Interaction between an air-stable orange-colored dye molecule, acridine orange base (AOB), and single-crystal surfaces of ZnO(101-0), (0001), and (000-1) is examined by synchrotron-radiation-excited photoelectron spectroscopy and X-ray absorption spectroscopy. AOB adsorbs molecularly on the ZnO surfaces to form chemical bonds with the surface O atoms. AOB tends to lie flat on the surfaces, whereas a more stand-up orientation is preferred on the AOB-crowded surfaces. AOB adsorption induces downward bending of the ZnO band with the largest amount on ZnO(000-1), followed by the ZnO(10-10) and ZnO(0001) surfaces, indicating an electron donor property of AOB. The energy level alignment at the AOB/ZnO interface is determined and is found to be characterized by a type-II heterojunction, which favors the charge transfer of the excited electron from AOB to ZnO. more...
- Published
- 2016
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22. Angle-Resolved and Resonant Photoemission Study of the Valence Bands of α-La(0001) on W(110)
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Y. Sakisaka, Hiroo Kato, Osamu Morimoto, and Yoshiharu Enta
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Materials science ,Valence (chemistry) ,Inverse photoemission spectroscopy ,Fermi energy ,Angle-resolved photoemission spectroscopy ,02 engineering and technology ,Electronic structure ,Photon energy ,021001 nanoscience & nanotechnology ,01 natural sciences ,Brillouin zone ,0103 physical sciences ,Atomic physics ,010306 general physics ,0210 nano-technology ,Electronic band structure - Abstract
We report a photoelectron spectroscopic study of the valence bands of double hexagonal-close-packed (dhcp) α-La(0001) films epitaxially grown on W(110) at room temperature. The La 5d photoemission cross section in the photon energy region from 20 eV to 130 eV was obtained and the valence-band structure of α-La was determined. Except for 4f-related structures, the valence-band structures of dhcp α-La and dhcp β-Ce were found to resemble each other. From the band structure, the crystal structure of the La film was confirmed. No evidence for the existence of a 5d-like surface state near the Fermi energy at the point of the surface Brillouin zone was obtained and a 6s band bottom was identified. more...
- Published
- 2016
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23. Impella 5.0 for Cardiogenic Shock After Thrombectomy in a Patient With Intraventricular Thrombosis
- Author
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Tasuku Kuwayama, Masato Mutsuga, Takahiro Okumura, Hideo Oishi, Yuki Kimura, Toru Kondo, Ryota Morimoto, Toyoaki Murohara, Naoki Shibata, Kazuro Fujimoto, Yoshihito Arao, Hiroaki Hiraiwa, Shingo Kazama, Hiroo Kato, Shogo Yamaguchi, and Akihiko Usui more...
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medicine.medical_specialty ,Percutaneous ,business.industry ,medicine.medical_treatment ,Cardiogenic shock ,Dilated cardiomyopathy ,030204 cardiovascular system & hematology ,medicine.disease ,Thrombosis ,03 medical and health sciences ,surgical procedures, operative ,0302 clinical medicine ,medicine.anatomical_structure ,Ventricle ,Internal medicine ,medicine ,Extracorporeal membrane oxygenation ,Cardiology ,030212 general & internal medicine ,Thrombus ,Cardiology and Cardiovascular Medicine ,business ,Impella - Abstract
A 43-year-old man was admitted to a referring hospital for cardiogenic shock caused by dilated cardiomyopathy. Intra-aortic balloon pump and percutaneous venoarterial extracorporeal membrane oxygenation (VA-ECMO) were started initially; however, a thrombus was detected in the left ventricle. After transfer to our institution, we performed thrombectomy through minithoracotomy. Subsequently, an Impella 5.0 device was inserted via the left subclavian artery. His cardiac function gradually improved, and both VA-ECMO and the Impella 5.0 could be weaned off. He was discharged without any thromboembolic event. Impella insertion with thrombectomy was possible, minimally invasive, and effective for a patient with intraventricular thrombosis associated with VA-ECMO. more...
- Published
- 2020
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24. Photoelectron spectroscopy study of interaction of oxygen with the (111) surface of a Cu–Zn alloy
- Author
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Yuhei Mimori, Hiroo Kato, Saori Imanishi, Kazuyuki Edamoto, Kenichi Ozawa, and Kazuhiko Mase
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Shockley surface state ,Materials science ,oxidation ,Fermi level ,Alloy ,chemistry.chemical_element ,Surfaces and Interfaces ,engineering.material ,Condensed Matter Physics ,Alkali metal ,Oxygen ,Surfaces, Coatings and Films ,Photoelectron spectroscopy ,symbols.namesake ,Crystallography ,Adsorption ,chemistry ,X-ray photoelectron spectroscopy ,ZnO ,Materials Chemistry ,symbols ,engineering ,Work function ,alpha-brass ,Surface states - Abstract
Interaction of O atoms with the (111) surface of a Cu–Zn alloy with a face-centered cubic structure (α-brass) is investigated by photoelectron spectroscopy utilizing synchrotron radiation. The O adatoms interact mainly with the Zn atoms to form the ZnO islands, whereas the Cu O bond formation is negligible in the initial oxidation stages at room temperature. O adsorption induces a binding-energy shift of the Shockley-type surface states towards the Fermi level. Also induced is a lowering of the work function of the α-brass(111) surface. These O-induced changes resemble those on the alkali-metal-covered Cu (111) surface. Similarity between Zn on the brass surface and alkali metals adsorbed on Cu (111) in initial oxidation is discussed. more...
- Published
- 2014
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25. Shockley surface state on α-brass(111) and its response to oxygen adsorption
- Author
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Yuhei Mimori, Kenichi Ozawa, Hiroshi Sakama, Kazuyuki Edamoto, Kazuhiko Mase, Hiroo Kato, Saori Imanishi, and Masato Emori
- Subjects
Materials science ,Shockley surface state ,Alloy ,Thermodynamics ,Electron ,engineering.material ,Brass ,symbols.namesake ,Effective mass (solid-state physics) ,X-ray photoelectron spectroscopy ,Atomic orbital ,Oxidation ,Materials Chemistry ,Wave function ,Cu(111) ,Angle-resolved photoelectron spectroscopy ,Fermi level ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,visual_art ,symbols ,visual_art.visual_art_medium ,engineering ,Atomic physics ,alpha-brass - Abstract
Angle-resolved photoelectron spectroscopy has been applied to investigate the Shockley-type surface state on the (111) surface of α -brass, a Cu–Zn alloy with a face-centered cubic structure. An energy position and an effective mass of the Shockley-state band are determined, respectively, to be 0.51 eV and 0.52 m e with m e being the rest mass of an electron. A decay length of the Shockley-state wave function into the bulk is also estimated to be 0.43 nm. These parameters are compared with those of the Shockley state on Cu(111), and it is concluded that the Cu sp orbitals in α -brass have a more isolated nature than those in Cu. Also examined in this study is the response of the Shockley state to oxygen adsorption. The behavior of the Shockley state upon oxygen adsorption strongly depends on the substrate temperature. At room temperature, the Shockley state is quenched along with the binding-energy shift towards the Fermi level. Contrastingly, oxygen adsorption at low temperatures (≤ 180 K) hardly affects the energy position of the Shockley state. The conversion of the surface oxidation process at a certain temperature between 180 K and room temperature is proposed. more...
- Published
- 2014
26. Fulminant myocarditis with myositis of ocular and respiratory muscles.
- Author
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Hiroaki Hiraiwa, Kenji Furusawa, Shingo Kazama, Yuki Kimura, Naoki Shibata, Yoshihito Arao, Hideo Oishi, Hiroo Kato, Tasuku Kuwayama, Shogo Yamaguchi, Toru Kondo, Akinori Sawamura, Ryota Morimoto, Takahiro Okumura, and Toyoaki Murohara more...
- Subjects
RESPIRATORY muscles ,CORONARY angiography ,MYOCARDITIS ,CREATINE kinase ,STERNOCLEIDOMASTOID muscle ,MYOSITIS - Abstract
A 46-year-old Japanese woman visited a nearby hospital because of diplopia after flu-like symptoms. One month later, she presented with blepharoptosis and external ophthalmoplegia. Laboratory tests showed a high creatine kinase concentration (3146 U/L). She underwent intravenous immunoglobulin therapy; however, her symptoms did not improve, prompting transfer to our institute. On admission, transthoracic echocardiography revealed 30% of left ventricular ejection fraction and edema of the left ventricular wall. Coronary angiography showed no significant coronary stenosis. An endomyocardial biopsy resulted in a diagnosis of acute myocarditis. On the following day, she needed a temporary pacemaker because she had complete atrioventricular block and intra-aortic balloon pump because of cardiogenic shock. Intravenous immunoglobulin therapy was again administered and her cardiac function gradually recovered. She was successfully weaned off her temporary pacemaker and intra-aortic balloon pump on Day 5 after improvement in her complete atrioventricular block. Steroid therapy administered from Day 9 was effective in reducing her creatine kinase concentrations. However, contrast-enhanced magnetic resonance imaging revealed inflammation of the scalene, semispinalis cervicis, sternocleidomastoid, and intercostal muscles. On Day 25, her cardiac function had recovered to a left ventricular ejection fraction of 59%. Finally, she was successfully discharged on Day 45 after undergoing rehabilitation. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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27. Pathological changes of the myocardium in reworsening of anthracycline-induced cardiomyopathy after explant of a left ventricular assist device.
- Author
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Hiroaki Hiraiwa, Takahiro Okumura, Shinya Shimizu, Yoshihito Arao, Hideo Oishi, Hiroo Kato, Tasuku Kuwayama, Shogo Yamaguchi, Tomoaki Haga, Tsuyoshi Yokoi, Toru Kondo, Yuki Sugiura, Naoaki Kano, Naoki Watanabe, Kenji Fukaya, Kenji Furusawa, Akinori Sawamura, Ryota Morimoto, Kazuro Fujimoto, and Masato Mutsuga more...
- Subjects
MYOCARDIUM ,HEART assist devices ,CARDIOMYOPATHIES ,ANTHRACYCLINES ,BIOPSY ,COLLAGEN ,HEART cells - Abstract
We herein report the long-term changes in cardiac function and pathological findings after successful explantation of a left ventricular assist device in a 42-year-old patient with anthracycline-induced cardiomyopathy with reworsening heart failure. Endomyocardial biopsy samples revealed that the cardiomyocyte diameter decreased and collagen volume fraction increased just after left ventricular assist device explantation. The collagen volume fraction decreased after 6 months, despite preserved systolic function. At 5 years after left ventricular assist device explantation, the systolic function markedly decreased and cardiomyocyte diameter increased. Pathological changes of the myocardium may enable the identification of cardiac dysfunction prior to echocardiographic changes in patients with reworsening heart failure after left ventricular assist device explantation. [ABSTRACT FROM AUTHOR] more...
- Published
- 2020
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28. Rapidly progressive symptom development of pulmonary arterial hypertension: a case report of Trousseau syndrome
- Author
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Junko Miyamoto, Masaki Yamauchi, Hideto Tsukamoto, Takanori Shumiya, Hiroo Kato, Akinobu Nakano, and Kenji Okumura
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Adult ,medicine.medical_specialty ,Pathology ,Hypertension, Pulmonary ,Autopsy ,Adenocarcinoma ,Krukenberg Tumor ,Fatal Outcome ,Stomach Neoplasms ,Internal medicine ,Diagnosis ,medicine ,Humans ,Thrombophilia ,Heart Failure ,Ovarian Neoplasms ,Signet ring cell ,business.industry ,Tumor Embolism ,Mucins ,Vascular surgery ,medicine.disease ,digestive system diseases ,Mucin-Producing Adenocarcinoma ,Cardiac surgery ,Pulmonary embolism ,Cardiology ,Female ,Pulmonary Embolism ,Cardiology and Cardiovascular Medicine ,business - Abstract
Trousseau syndrome is most commonly defined as a hypercoagulability syndrome associated with mucin-producing adenocarcinoma. We report here a rare case of Trousseau syndrome presenting as pulmonary arterial hypertension. The patient complained of cough and increasing exertional dyspnea. Rapidly progressive symptom development of pulmonary arterial hypertension accompanied by right heart failure was observed, and the patient died on hospital day 2. An autopsy revealed Krukenberg tumors on both ovaries and a signet-ring cell gastric carcinoma. In the lungs there was tumor embolism with signet-ring cells to some extent, but the peripheral pulmonary arteries were occupied primarily by pulmonary embolism with platelets, fibroblasts, and fibrotic organized thrombi. more...
- Published
- 2013
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29. A System Dynamics Approach to Process Evaluation of Pen-Based Digital Media-Making Projects
- Author
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Hiroo Kato, Nishesh Chalise, and Moses Okumu
- Subjects
Knowledge management ,Multimedia ,Computer science ,business.industry ,Learning environment ,05 social sciences ,Causal loop diagram ,050301 education ,computer.software_genre ,Grounded theory ,Digital media ,System dynamics ,0502 economics and business ,Lesson study ,business ,Raw data ,0503 education ,computer ,050203 business & management ,Coding (social sciences) - Abstract
This chapter explains a systematic way of conducting process evaluation of pen-based digital media-making projects using system dynamics modeling. The study aimed to understand student and teacher experiences and changes in behavior while engaged in the digital media-making process. Data was collected at a pen-based digital media-making summer program held at Pepperdine University’s Los Angeles and Ventura County campuses. After transcribing and coding raw data using grounded theory, the authors generated causal loop maps. The study indicated that the production of videos depends on both the students’ and teachers’ engagement in the digital media-making process. Active engagement of teachers and students improved the quality of the learning environment. The use of system dynamics allowed us to see the flaws and unique aspects within the digital making process. more...
- Published
- 2016
- Full Text
- View/download PDF
30. Oxygen-free palladium/titanium coating, a novel nonevaporable getter coating with an activation temperature of 133 °C
- Author
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Yoshihiro Kato, Hiroo Kato, Tetsuya Miyazawa, Ayako Hashimoto, Takashi Kikuchi, Naoya Terashima, Shinya Ohno, Yuto Natsui, Kazuhiko Mase, and Masashi Kurihara
- Subjects
010302 applied physics ,Materials science ,Scanning electron microscope ,chemistry.chemical_element ,02 engineering and technology ,Surfaces and Interfaces ,engineering.material ,Sputter deposition ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Surfaces, Coatings and Films ,X-ray photoelectron spectroscopy ,chemistry ,Coating ,Transmission electron microscopy ,Getter ,0103 physical sciences ,engineering ,Thin film ,Composite material ,0210 nano-technology ,Titanium - Abstract
A novel nonevaporable getter (NEG) coating was developed with an activation temperature as low as 133 °C, that is, a palladium/titanium coating with extremely low oxygen concentration (oxygen-free Pd/Ti coating). The substrate was coated with Ti and then overcoated with Pd using sublimation under ultrahigh vacuum conditions. The morphology and surface elemental composition of the Pd/Ti thin film were investigated with electron microscopes and x-ray photoelectron spectroscopy, respectively. The thicknesses of Ti and Pd films were approximately 1.3 μm and 50 nm, and the Ti film was completely overcoated by the Pd film. Ti and oxygen were found to be negligible on the oxygen-free Pd/Ti surface. The oxygen-free Pd/Ti coating was applied to the formed bellows. The bellows was successively baked at 133 °C for 12 h, 176 °C for 3.5 h, and 200 °C for 3.5 h. After sealing off a turbomolecular pump from the vacuum system containing the bellows, the pressure reached values of 4.6 × 10−6, 1.7 × 10−7, and 6.1 × 10−8 Pa, respectively. The pumping speeds of the bellows were estimated to be 0.028, 0.23, and 0.23 l s−1, respectively. These results demonstrate that oxygen-free Pd/Ti deposition can be used as a new NEG coating for vacuum systems with a baking temperature of 133 °C or higher. more...
- Published
- 2018
- Full Text
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31. Controlling the surface photovoltage on WSe2 by surface chemical modification
- Author
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Kenichi Ozawa, Suguru Ito, Naoya Terashima, Wei Chuan Chen, Susumu Yamamoto, Iwao Matsuda, Tai-Chang Chiang, Baojie Feng, Ro-Ya Liu, Cheng Maw Cheng, Yuto Natsui, and Hiroo Kato
- Subjects
chemistry.chemical_classification ,Materials science ,Physics and Astronomy (miscellaneous) ,Surface photovoltage ,Electron donor ,02 engineering and technology ,Carrier lifetime ,Electron acceptor ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,chemistry.chemical_compound ,Adsorption ,Transition metal ,chemistry ,0103 physical sciences ,Surface chemical ,010306 general physics ,0210 nano-technology ,Recombination - Abstract
The surface photovoltage (SPV) effect is key to the development of opto-electronic devices such as solar-cells and photo-detectors. For the prototypical transition metal dichalcogenide WSe2, core level and valence band photoemission measurements show that the surface band bending of pristine cleaved surfaces can be readily modified by adsorption with K (an electron donor) or C60 (an electron acceptor). Time-resolved pump-probe photoemission measurements reveal that the SPV for pristine cleaved surfaces is enhanced by K adsorption, but suppressed by C60 adsorption, and yet the SPV relaxation time is substantially shortened in both cases. Evidently, adsorbate-induced electronic states act as electron-hole recombination centers that shorten the carrier lifetime. more...
- Published
- 2018
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- View/download PDF
32. Photoemission from the valence bands of Ce(111) on W(110)
- Author
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Yoshiharu Enta, Y. Sakisaka, Hiroo Kato, and O. Morimoto
- Subjects
Lanthanide ,Phase transition ,Valence (chemistry) ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Photon energy ,Condensed Matter Physics ,Epitaxy ,Surfaces, Coatings and Films ,Cerium ,chemistry ,Transition metal ,X-ray photoelectron spectroscopy ,Materials Chemistry - Abstract
We report a photoelectron spectroscopic study of the valence bands of epitaxial Ce(1 1 1) films grown on W(1 1 0) at room temperature. The evolution of γ → α → γ like phase transition of Ce is observed with increasing Ce coverage and the valence-band structures of γ -like Ce film are determined. The 4 f and 5 d photoemission cross sections in the photon energy region from 20 eV to 130 eV are presented and discussed. A 5 d -like surface state and a 6 s band bottom are identified. more...
- Published
- 2009
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33. A More Inclusive, Less Distracting, and Engaging Learning Environment Through Smartsync
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Alicia Gonzalez, Hiroo Kato, and Jose Israel Ramirez Gamez
- Subjects
Class (computer programming) ,Downtime ,Harm ,Learning environment ,Synchronization (computer science) ,ComputingMilieux_COMPUTERSANDEDUCATION ,Mathematics education ,Student engagement ,Confidentiality ,Psychology ,Motion (physics) - Abstract
This paper documents some of the initial experiences of using synchronization technology via networked tablet computers in a high school classroom setting. It addresses some of the rudimentary issues of how instructional time is lost by physical motion; how student teacher confidentiality affects student feedback; and how whole class interruptions can do more harm than good. The networked tablet computers allow students to freely communicate with teachers in a more private and personalized study environment, and can be done without the teacher having to move around the classroom. Initial findings suggest a high level of student engagement, less downtime for students, faster and more frequent teacher responses, enhanced communication between teacher and student, and better behavior. more...
- Published
- 2015
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34. Oxynitridation of Si(100) surface with thermally excited N2O gas
- Author
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Hiroo Kato, Yoshiharu Enta, S. Takeda, K. Suto, and Y. Sakisaka
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Auger electron spectroscopy ,Silicon oxynitride ,Silicon ,Thermal decomposition ,Metals and Alloys ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Substrate (electronics) ,Excitation temperature ,equipment and supplies ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Reaction rate ,chemistry.chemical_compound ,chemistry ,Excited state ,Materials Chemistry - Abstract
Silicon oxynitride films have been grown with thermally excited N2O gas, which has a low toxicity in comparison with other oxynitridation agents. Dependences of reaction rates on excitation temperature and substrate temperature have been investigated by Auger electron and photoelectron spectroscopies. These results show that the thermal excitation of N2O obviously promotes the oxynitridation of the silicon surface, especially the oxidation reaction. At higher substrate temperatures, the nitridation of the silicon surface increases and the oxidation is reduced. By mass analysis of the residual gas in the reaction chamber, it was also found that the thermal excitation of N2O causes N2O to be decomposed into N2 and O. This is consistent with the obtained effect that the thermal excitation of N2O promotes especially the oxidation reaction, because atomic oxygen (O) acts as a strong oxidant. more...
- Published
- 2006
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35. Photoemission study of the modification of the electronic structure of transition-metal overlayers on TiO2 surfaces
- Author
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Y Sakisaka, Hiroo Kato, T Okazaki, and N Nakajima
- Subjects
Materials science ,Transition metal ,Chemical physics ,Materials Chemistry ,Surfaces and Interfaces ,Electronic structure ,Condensed Matter Physics ,Surfaces, Coatings and Films - Published
- 2004
- Full Text
- View/download PDF
36. Photoemission study of the modification of the electronic structure of transition-metal overlayers on TiO2 surfaces II. Cr on TiO2(001)
- Author
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T Okazaki, Y. Sakisaka, Hiroo Kato, and N Nakajima
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Materials science ,Analytical chemistry ,Synchrotron radiation ,Surfaces and Interfaces ,Electronic structure ,Condensed Matter Physics ,Molecular electronic transition ,Surfaces, Coatings and Films ,Ion ,Metal ,X-ray photoelectron spectroscopy ,Transition metal ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Deposition (law) - Abstract
The electronic states of the Fe overlayers on TiO 2 (1 1 0) surfaces have been investigated using normal-emission and resonant photoelectron spectroscopy with synchrotron radiation. It was found that Fe grows in a Stranski–Krastanov mode. At low coverages, Fe deposition on TiO 2 (1 1 0) is supposed to create surface Ti 3+ (3d 1 ) ions leading to the same in-gap emission as that is produced by surface oxygen vacancies of TiO 2 . At high coverages, Fe-induced in-gap emission is evolved into a bulk Fe spectrum. However, at the beginning, a Fermi edge is not observed, indicating that the small Fe clusters of non-metallic nature are formed. A sharp Fermi edge is formed at higher coverages, indicating that the cluster becomes metallic as the size increases. more...
- Published
- 2004
- Full Text
- View/download PDF
37. Photoemission study of the modification of the electronic structure of transition-metal overlayers on TiO2 surfaces III. Ni on TiO2 and Cu on TiO2
- Author
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T Okazaki, Hiroo Kato, Y. Sakisaka, and N Nakajima
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Materials science ,Photoemission spectroscopy ,Band gap ,Surfaces and Interfaces ,Substrate (electronics) ,Electronic structure ,Condensed Matter Physics ,Molecular electronic transition ,Surfaces, Coatings and Films ,Crystallography ,Transition metal ,X-ray photoelectron spectroscopy ,Materials Chemistry ,Deposition (law) - Abstract
The electronic states of the Ni overlayers on TiO2(001) surface and Cu overlayers on TiO2(110) surface have been investigated using angle-resolved and resonant photoemission spectroscopy with synchrotron radiation. In the Ni/TiO2(001) system, an in-gap emission from the reduced Ti3+ 3d1 state appears at 1.2 eV below EF for the initial Ni deposition. Upon further deposition, the emission grows and is evolved to a spectrum of Ni metal, with forming no Fermi edge, suggesting the formation of small Ni clusters on TiO2(001). In the Cu/TiO2(110) system, Cu grows in a Stranski–Krastanov mode. Two in-gap emissions from the reduced Ti3+ 3d1 state and oxidized Cu+ 3d10 or Cu2+ 3d9 state are observed at 0.8 and 2.8 eV below EF, respectively, for the initial Cu deposition, giving convincing evidence that there is significant charge transfer between Cu and the substrate. Upon further deposition, the emission in the band-gap region is evolved to a spectrum of Cu metal, though delayed completion of the Fermi edge is observed. Such delay can be explained by finite cluster size effects. more...
- Published
- 2004
- Full Text
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38. Performance of the high-resolution high-flux monochromator for bending magnet beamline BL-1C at the Photon Factory
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Yoshio Watanabe, Masaki Mizuguchi, Takashi Kikuchi, Hiroo Kato, Fumihiko Maeda, Kanta Ono, Akito Kakizaki, Koji Horiba, Akira Yagishita, Masaharu Oshima, Takanori Kiyokura, and J. H. Oh
- Subjects
Physics ,Nuclear and High Energy Physics ,Photon ,business.industry ,Grating ,law.invention ,Bending magnets ,High flux ,Optics ,Beamline ,law ,Factory (object-oriented programming) ,business ,Instrumentation ,Monochromator ,Line (formation) - Abstract
A grazing incidence varied line spacing plane grating monochromator (VLS-PGM) has been designed and installed at the Photon Factory bending magnet beamline, BL-1C. The monochromator is designed to cover 20 to 250 eV with a high resolving power as well as a high photon flux and intended for a high-resolution angle-resolved photoemission study of quantum nano-structures. The resolving power of the beamline is observed to be more than 16,000 at around 65 eV and exceeds 10,000 at all the covered energy ranges of the monochromator with photon flux over 10 9 photons/s which shows that this monochromator reaches the expected design goals. more...
- Published
- 2001
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- View/download PDF
39. Cobalt(II) phosphine complexes stable in aqueous solution: spectroscopic and kinetic evidence for low-spin Co(II)P6 and Co(II)P3S3 with tripodal 1,1,1-tris(dimethylphosphinomethyl)ethane
- Author
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Satoshi Iwatsuki, Nobuyoshi Koshino, Shigenobu Funahashi, Takayoshi Suzuki, Kazuo Kashiwabara, Hiroo Kato, Kenji Obeyama, and Hideo D. Takagi
- Subjects
Nephelauxetic effect ,Aqueous solution ,Inorganic chemistry ,chemistry.chemical_element ,Electrochemistry ,Medicinal chemistry ,Redox ,law.invention ,Inorganic Chemistry ,chemistry.chemical_compound ,Electron transfer ,chemistry ,law ,Materials Chemistry ,Physical and Theoretical Chemistry ,Electron paramagnetic resonance ,Cobalt ,Phosphine - Abstract
Co(II) species produced by the controlled potential electrochemical reduction of Co(III)P 3 S 3 and Co(III)P 6 complexes with 1,4,7-trithiacyclononane and tripodal 1,1,1-tris(dimethylphosphinomethyl)ethane in aqueous solution were characterized at ambient temperature by the EPR and spectrophotometric methods: the Co(II)P 6 and Co(II)P 3 S 3 species are in the low-spin t 2g 6 e g 1 state with large Jahn–Teller distortion. Kinetic studies of the redox reactions involving these Co(III)/(II) species revealed that the electron self-exchange reactions for the Co(III)/(II) couples are very fast ( k ex ∼10 4 dm 3 mol −1 s −1 ), which is consistent with the results for other low-spin/low-spin Co(III)/(II) couples. It was concluded that the nephelauxetic effect of the P donor atom stabilizes the low-spin state in Co(II). more...
- Published
- 2000
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- View/download PDF
40. In situ observation of a high-temperature Si(001) surface during SiH2Cl2 exposure by photoelectron spectroscopy
- Author
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Yuji Takakuwa, Toyokazu Hori, Yoshiharu Enta, Hitoshi Sakamoto, Nobuo Miyamoto, and Hiroo Kato
- Subjects
Silanes ,Valence (chemistry) ,Silicon ,Metals and Alloys ,Analytical chemistry ,Dangling bond ,chemistry.chemical_element ,Surfaces and Interfaces ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Adsorption ,chemistry ,X-ray photoelectron spectroscopy ,Electron diffraction ,Desorption ,Materials Chemistry - Abstract
In situ observation by photoelectron spectroscopy using synchrotron radiation was performed to investigate the species and coverage of surface adsorbates while exposing the high-temperature Si(001) surface to SiH 2 Cl 2 atmosphere. Photoelectron spectra of valence bands made it possible to evaluate the clean surface area with dimer dangling bonds (Si db). Curve-fitting analysis of Si 2p spectra showed that the chlorine adsorption species is only monochloride (Si-Cl) in the whole temperature region from room temperature ~700 °c examined. From comparison between the surface coverages of Si-db and Si-Cl in connection with the 2 × 1 structure of the SiH 2 Cl 2 -adsorbed Si(001) surface as observed by reflection high energy electron diffraction, we assigned the hydrogen adsorption state to be dominantly monohydride (Si-H). The temperature dependencies of the surface coverages obtained for Si-Cl, Si-H and Si-db are discussed using a surface reaction model of SiH 2 Cl 2 adsorption. more...
- Published
- 1999
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- View/download PDF
41. Angle-resolved photoemission study of the wurtzite GaN (0001)
- Author
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Katsuhiro Akimoto, Sung Hwan Cho, Y. Miyajima, Hiroo Kato, and Takahiro Maruyama
- Subjects
Materials science ,Photoemission spectroscopy ,Wide-bandgap semiconductor ,Synchrotron radiation ,Electronic structure ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Electrical and Electronic Engineering ,Atomic physics ,Local-density approximation ,Electronic band structure ,Wurtzite crystal structure ,Molecular beam epitaxy - Abstract
The valence-electronic structure of the wurtzite GaN (0 0 0 1) surface grown by plasma-enhanced molecular beam epitaxy was investigated by angle-resolved photoemission spectroscopy with synchrotron radiation. The bulk bands along ΓA direction were mapped using normal-emission spectra in the 40–80 eV photon-energy range. On the whole, the experimental results agree with the calculated bands based on local density approximation within the upper valence band. On the other hand, in the higher-energy region of the valence band, it was found that the Ga 3d state is positioned at 15.7 eV below the valence band maximum, which is about 2 eV higher than those theoretically predicted. Off-normal-emission spectra were also measured along the ΓK and ΓM symmetry lines. more...
- Published
- 1999
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- View/download PDF
42. Na adsorption on the polar NbC(111) surface
- Author
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Kazuyuki Edamoto, Shigeki Otani, Hiroo Kato, Kenichi Ozawa, and S. Ishikawa
- Subjects
Photoemission spectroscopy ,Chemistry ,Fermi level ,Inverse photoemission spectroscopy ,Analytical chemistry ,Surfaces and Interfaces ,Electronic structure ,Condensed Matter Physics ,Antibonding molecular orbital ,Molecular physics ,Surfaces, Coatings and Films ,Overlayer ,symbols.namesake ,Adsorption ,Materials Chemistry ,symbols ,Work function - Abstract
Core-level photoemission spectroscopy and angle-resolved photoemission spectroscopy with synchrotron radiation have been used to study the adsorption mechanism of Na on the NbC(111) surface. Coverage-dependent measurements of the work function and the Na core-level photoemission show that Na adsorption on NbC(111) proceeds via a polarization–depolarization transition. Valence-band photoemission measurements show that the 3s orbital of adsorbed Na is hybridized with the Nb 4d-derived surface state which is characteristic of the polar (111) surfaces of transition-metal carbides. In the initial stages of adsorption, only a bonding part of the hybridized states is found in the occupied region and an antibonding part lies above the Fermi level, which corresponds to the electronic structure for the polarized adsorbed layer. The antibonding part, mainly composed of the Na 3s orbital, is observed just below the Fermi level at around the Γ point in the high-coverage region where the work function is gradually increased after the work-function minimum. The appearance of the partially filled antibonding state indicates substantial back donation of electronic charge towards the adsorbed Na atoms, and can be viewed as direct evidence of the metallization of the overlayer in the higher-coverage region. more...
- Published
- 1999
- Full Text
- View/download PDF
43. Ultraviolet Photoemission Study of Interaction between Bathocuproine and Calcium
- Author
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Katsuhiro Akimoto, Susumu Toyoshima, Hiroo Kato, Tetsuya Taima, Takeaki Sakurai, and Kazuhiro Saito
- Subjects
Physics and Astronomy (miscellaneous) ,Organic solar cell ,Photoemission spectroscopy ,Fermi level ,General Engineering ,Analytical chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Electronic structure ,Calcium ,medicine.disease_cause ,symbols.namesake ,chemistry ,OLED ,medicine ,symbols ,HOMO/LUMO ,Ultraviolet - Abstract
The electronic structure at the interface between bathocuproine (BCP) and calcium (Ca) was studied by ultraviolet photoemission spectroscopy (UPS) using two kinds of thin-films: Ca and BCP codeposited film, and BCP deposited on Ca. New peaks caused by the interaction of Ca with BCP were observed near the Fermi level. The energy position of the highest occupied molecular orbital (HOMO) of BCP measured from the Fermi level did not change with the thickness of BCP on Ca and the composition ratio of BCP to Ca. The new peaks related to the interface states shifted with the thickness of BCP on Ca and the composition ratio of BCP to Ca. It is suggested that the interface states are generated by the interaction of the Fermi level of Ca with the lowest unoccupied molecular orbital rather than the HOMO. more...
- Published
- 2008
- Full Text
- View/download PDF
44. Angle-resolved photoemission spectroscopy study of Fe(110) single crystal: Many-body interactions between quasi-particles at the Fermi level
- Author
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Hirofumi Namatame, Kenya Shimada, Yoshihiro Aiura, Y. Sakisaka, Masaki Taniguchi, Mitsuharu Higashiguchi, Moritz Hoesch, Y. Miura, Hiroo Kato, and Xiaoyu Cui
- Subjects
Physics ,Condensed matter physics ,Photoemission spectroscopy ,Fermi level ,Inverse photoemission spectroscopy ,Binding energy ,Fermi surface ,Angle-resolved photoemission spectroscopy ,Surfaces and Interfaces ,Condensed Matter Physics ,Surfaces, Coatings and Films ,symbols.namesake ,self-energy ,Fe(110) ,Self-energy ,electron-phonon interaction ,Materials Chemistry ,symbols ,Condensed Matter::Strongly Correlated Electrons ,angle-resolved photoemission spectroscopy ,electron-magnon interaction ,Single crystal - Abstract
A high-resolution angle-resolved photoemission spectroscopy (ARPES) study of Fe(110) single crystal was conducted to elucidate many-body interactions between quasi-particles at the Fermi level at low-temperature. Two kink structures were observed in the energy-band dispersion at the binding energies of similar to 40 meV and similar to 270 meV for the bulk-derived band on the majority-spin Fermi surface around the F point. Based on analyses of the experimentally obtained real parts of the self-energy, these kink structures are derived from electron-phonon and electron-magnon interactions. more...
- Published
- 2007
- Full Text
- View/download PDF
45. High-resolution angle-resolved photoemission spectroscopy of iron: A study of the self-energy
- Author
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Y. Miura, Mitsuharu Higashiguchi, Hiroo Kato, Masaki Taniguchi, Moritz Hoesch, Y. Sakisaka, Xiaoyu Cui, Yoshihiro Aiura, Saiko Negishi, Hirofumi Namatame, and Kenya Shimada
- Subjects
Physics ,Condensed matter physics ,Photoemission spectroscopy ,Magnon ,Fermi level ,Inverse photoemission spectroscopy ,Fermi surface ,Angle-resolved photoemission spectroscopy ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,symbols ,Atomic physics ,Characteristic energy ,Debye model - Abstract
A high-resolution angle-resolved photoemission spectroscopy study of an Fe (1 1 0) single crystal has been conducted to clarify the role of many-body interactions acting on the quasi-particles at the Fermi level at low temperatures. We have evaluated the real and imaginary parts of the self-energy for the bulk-derived majority-spin Fermi surface around the Γ point, and found two characteristic energy scales, at ∼40 and ∼270 meV. The former corresponds to the energy scale of the Debye temperature. As for the latter, we found that it is close to the cut-off energy of the calculated magnon density-of-states. This correspondence indicates that the energy scale is related to the magnetic excitation. more...
- Published
- 2007
- Full Text
- View/download PDF
46. Real-time core-level spectroscopy of initial thermal oxide on Si(100)
- Author
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Nobuo Miyamoto, E. Shigemasa, Y. Miyanishi, Hiroo Kato, H. Irimachi, Michio Niwano, Yoshiharu Enta, and Maki Suemitsu
- Subjects
Silicon ,Chemistry ,Silicon dioxide ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Rate equation ,Condensed Matter Physics ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Reaction rate constant ,Thermal oxide ,Spectroscopy ,Layer (electronics) ,Stoichiometry - Abstract
A Si 2p core-level spectroscopic study has been performed in real time for initial thermal oxide on Si(100) by O2 gas. Time evolutions of the intensities of chemically shifted Si 2p peaks during oxidation have been compared with those of O 2p state, as well as with a simulation from a set of rate equations assuming a simple oxidation model. From the best fits to the data, rate constants relevant to the oxidation of the first and the second silicon layers were successfully derived as a function of the oxidation temperature. In particular, the oxidation of the first layer for temperatures of 540–620 °C was found to occur through direct oxidation of silicon atoms to stoichiometric silicon dioxide, without formation of any suboxides. more...
- Published
- 1998
- Full Text
- View/download PDF
47. Electronic structure of wurtzite- and zinc blende-GaN studied by angle-resolved photoemission
- Author
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Sung Hwan Cho, Yutaka Miyajima, Hiroo Kato, Sadafumi Yoshida, Takahiro Maruyama, Hajime Okumura, Kazutaka Hata, and Katasuhiro Akimoto
- Subjects
Valence (chemistry) ,Band gap ,Chemistry ,Photoemission spectroscopy ,Binding energy ,Condensed Matter Physics ,Molecular physics ,Semimetal ,Electronic, Optical and Magnetic Materials ,Materials Chemistry ,Electrical and Electronic Engineering ,Atomic physics ,Electronic band structure ,Quasi Fermi level ,Wurtzite crystal structure - Abstract
The valence band structures of both wurtzite- and zinc blende-GaN were investigated by angle-resolved photoemission spectroscopy. It was found the k dispersions of the upper valence bands show band structures corresponding to wurtzite or zinc blende structure. In wurtzite-GaN, band width of the upper valence band is 6.7 eV in good agreement with the theoretically predicted value. However, the binding energy of Ga 3d level was found to be 15.7 eV relative to the valence band maximum, which is about 2 eV higher binding energy than those predicted by local density approximation calculations. In zinc blende-GaN, some discrepancies in the binding energy of the topmost bands around the valence band maximum was observed. We discuss the cause of these discrepancies by taking into account the strain effect. more...
- Published
- 1998
- Full Text
- View/download PDF
48. Application of resonant X-ray emissions for molecular/electronic structure analysis of boron nitrides
- Author
-
Akane Agui, Jun Kawai, H. Kouzuki, M. Motoyama, Shik Shin, Hiroo Kato, T. Kaneyoshi, and Yasuji Muramatsu
- Subjects
Materials science ,Resonance ,chemistry.chemical_element ,General Chemistry ,Electronic structure ,Photon energy ,Nitride ,Undulator ,Molecular physics ,Crystal structure of boron-rich metal borides ,chemistry ,General Materials Science ,Molecular orbital ,Atomic physics ,Boron - Abstract
–B1s-1 transitions were observed in w-BN composed of four-fold boron atoms and in h-BN composed of three-fold boron atoms, when the photon energy of the incident undulator beams coincided with the B1s–B2pπ* absorption energy. However, no resonance was observed in c-BN composed of four-fold boron atoms. The resonant X-ray emission reflects the electronic structure of unoccupied molecular orbitals which strongly depend on the conformnations of the boron atoms. These findings confirm that resonant X-ray emissions can be useful indices for molecular and electronic structure analysis of boron nitrides. more...
- Published
- 1997
- Full Text
- View/download PDF
49. In situ monitoring of gas source molecular beam epitaxy of silicon with disilane by ultraviolet photoelectron spectroscopy
- Author
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Tetsuji Yamaguchi, Nobuo Miyamoto, Toyokazu Hori, Hitoshi Sakamoto, Yuji Takakuwa, Yoshiharu Enta, Tetsuhiro Horie, and Hiroo Kato
- Subjects
Arrhenius equation ,Silicon ,Analytical chemistry ,General Physics and Astronomy ,Synchrotron radiation ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,symbols.namesake ,X-ray photoelectron spectroscopy ,chemistry ,symbols ,Work function ,Disilane ,Molecular beam epitaxy ,Ultraviolet photoelectron spectroscopy - Abstract
Ultraviolet photoelectron spectroscopy (UPS) using synchrotron radiation was applied for monitoring in situ gas source molecular beam epitaxy (GSMBE) of silicon with disilane on a Si(001)2 × 1 surface. By the in situ UPS observation, information on the hydrogen adsorption state, the hydrogen-free coverage, the work function and the growth rate could be obtained during GSMBE. From the Arrhenius plots of hydrogen-free coverage, work function and growth rate, it turned out that the H2-desorption rate-limited temperature region was divided into two regions. With lowering temperature, we observed that only monohydride remains in the first region and then dihydride appears additionally in the second region. Thus, the break in the H2-desorption rate-limited region is associated with the change in hydrogen adsorption state. more...
- Published
- 1997
- Full Text
- View/download PDF
50. Resonant X-ray scattering of boron compounds
- Author
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Akane Agui, Shik Shin, Yasuji Muramatsu, Jun Kawai, and Hiroo Kato
- Subjects
Scattering ,Chemistry ,X-ray ,Analytical chemistry ,Synchrotron radiation ,Resonance ,chemistry.chemical_element ,Undulator ,Threshold energy ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry ,K-edge ,Atomic physics ,Boron ,Instrumentation ,Spectroscopy - Abstract
The boron Kα X-ray fluorescence spectra of TiB2, BP, B6O, and CaB6 were measured using undulator radiation with change in the primary X-ray energy. Variation of the resonance peak at 185–190 eV was observed with a change in the compound or in the incident X-ray energy. The modification of the resonance peak intensity was most pronounced when the excitation energy was the K edge threshold energy. © 1997 Elsevier Science B.V. more...
- Published
- 1997
- Full Text
- View/download PDF
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