Boron Nitride Dispersed Nanocomposites with High Thermal Shock Resistance

Kusunose, T.,Sekino, T.,Choa, Y.H.,Nakayama, T.,Niihara, K. The Korean Powder Metallurgy Institute 2001 한국분말재료학회지 (KPMI) Vol.8 No.3

The microstructure and mechanical properties of $Si_3N_4/BN $nanocomposites synthesized by chemical processing were investigated. The nanocomposites containing 15 vol% hexagonal BN (h-BN) were fabricated by hot-pressing $\alpha-Si_3N_4$powders covered with turbostratic BN (t-BN). The t-BN coating on $\alpha-Si_3N_4$particles was prepared by heating $\alpha-Si_3N_4$ particles covered with a mixture of boric acid and urea in hydrogen gas. TEM observations of this nanocomposite revealed that nano-sized h-BN particles were homogeneously dispersed within $Si_3N_4$grains as well as at grain boundaries. The strength and thermal shock resistance were significantly improved in comparison with the $Si_3N_4/BN$ microcomposites.

Pancreatic duct lavage cytology combined with a cell-block method for patients with possible pancreatic ductal adenocarcinomas, including pancreatic carcinoma in situ

Hiroaki Kusunose,Shinsuke Koshita,Yoshihide Kanno,Takahisa Ogawa,Toshitaka Sakai,Keisuke Yonamine,Kazuaki Miyamoto,Fumisato Kozakai,Hideyuki Anan,Kazuki Endo,Haruka Okano,Masaya Oikawa,Takashi Tsuchiy 대한소화기내시경학회 2023 Clinical Endoscopy Vol.56 No.3

Background/Aims: This study aimed to clarify the efficacy and safety of pancreatic duct lavage cytology combined with a cell-block method (PLC-CB) for possible pancreatic ductal adenocarcinomas (PDACs). Methods: This study included 41 patients with suspected PDACs who underwent PLC-CB mainly because they were unfit for undergoing endoscopic ultrasonography-guided fine needle aspiration. A 6-Fr double lumen catheter was mainly used to perform PLC-CB. Final diagnoses were obtained from the findings of resected specimens or clinical outcomes during surveillance after PLC-CB. Results: Histocytological evaluations using PLC-CB were performed in 87.8% (36/41) of the patients. For 31 of the 36 patients, final diagnoses (invasive PDAC, 12; pancreatic carcinoma in situ, 5; benignancy, 14) were made, and the remaining five patients were excluded due to lack of surveillance periods after PLC-CB. For 31 patients, the sensitivity, specificity, and accuracy of PLC-CB for detecting malignancy were 94.1%, 100%, and 96.8%, respectively. In addition, they were 87.5%, 100%, and 94.1%, respectively, in 17 patients without pancreatic masses detectable using endoscopic ultrasonography. Four patients developed postprocedural pancreatitis, which improved with conservative therapy. Conclusions: PLC-CB has an excellent ability to detect malignancies in patients with possible PDACs, including pancreatic carcinoma in situ.

Relationship between Right Ventricular Longitudinal Strain, Invasive Hemodynamics, and Functional Assessment in Pulmonary Arterial Hypertension

박재형,Kenya Kusunose,Deborah H. Kwon,Margaret M. Park,Serpil C. Erzurum,James D. Thomas,Richard A. Grimm,Brian P. Griffin,Thomas H. Marwick,Zoran B. Popović 대한심장학회 2015 Korean Circulation Journal Vol.45 No.5

Background and Objectives: Right ventricular longitudinal strain (RVLS) is a new parameter of RV function. We evaluated the relationship of RVLS by speckle-tracking echocardiography with functional and invasive parameters in pulmonary arterial hypertension (PAH) patients. Subjects and Methods: Thirty four patients with World Health Organization group 1 PAH (29 females, mean age 45±13 years old). RVLS were analyzed with velocity vector imaging. Results: Patients with advanced symptoms {New York Heart Association (NYHA) functional class III/IV} had impaired RVLS in global RV (RVLSglobal, -17±5 vs. -12±3%, p<0.01) and RV free wall (RVLSFW, -19±5 vs. -14±4%, p<0.01 to NYHA class I/II). Baseline RVLSglobal and RVLSFW showed significant correlation with 6-minute walking distance (r=-0.54 and r=-0.57, p<0.01 respectively) and logarithmic transformation of brain natriuretic peptide concentration (r=0.65 and r=0.65, p<0.01, respectively). These revealed significant correlations with cardiac index (r=-0.50 and r=-0.47, p<0.01, respectively) and pulmonary vascular resistance (PVR, r=0.45 and r=0.45, p=0.01, respectively). During a median follow-up of 33 months, 25 patients (74%) had follow-up examinations. Mean pulmonary arterial pressure (mPAP, 54±13 to 46±16 mmHg, p=0.03) and PVR (11±5 to 6±2 wood units, p<0.01) were significantly decreased with pulmonary vasodilator treatment. RVLSglobal (-12±5 to -16±5%, p<0.01) and RVLSFW (-14±5 to -18±5%, p<0.01) were significantly improved. The decrease of mPAP was significantly correlated with improvement of RVLSglobal (r=0.45, p<0.01) and RVLSFW (r=0.43, p<0.01). The PVR change demonstrated significant correlation with improvement of RVLSglobal (r=0.40, p<0.01). Conclusion: RVLS correlates with functional and invasive hemodynamic parameters in PAH patients. Decrease of mPAP and PVR as a result of treatment was associated with improvement of RVLS

Multifunction Integrated Nanocomposites and Their Industrial Applications

Niihara K.,Kusunose M.,Nakayama T.,Sekino T.,Hayashi Y. 한국분말야금학회 2003 한국분말야금학회 학술대회논문집 Vol.2003 No.1

Relationship between Right Ventricular Longitudinal Strain, Invasive Hemodynamics, and Functional Assessment in Pulmonary Arterial Hypertension

박재형,Kenya Kusunose,Deborah H. Kwon,Margaret M. Park,James D. Thomas,Richard A. Grimm,Brian P. Griffin,Thomas H. Marwick,Zoran B. Popović 대한심장학회 2016 Korean Circulation Journal Vol.46 No.2

Background and Objectives Right ventricular longitudinal strain (RVLS) is a new parameter of RV function. We evaluated the relationship of RVLS by speckle-tracking echocardiography with functional and invasive parameters in pulmonary arterial hypertension (PAH) patients. Subjects and Methods Thirty four patients with World Health Organization group 1 PAH (29 females, mean age 45±13 years old). RVLS were analyzed with velocity vector imaging. Results Patients with advanced symptoms {New York Heart Association (NYHA) functional class III/IV} had impaired RVLS in global RV (RVLSglobal, -17±5 vs. -12±3%, p<0.01) and RV free wall (RVLSFW, -19±5 vs. -14±4%, p<0.01 to NYHA class I/II). Baseline RVLSglobal and RVLSFW showed significant correlation with 6-minute walking distance (r=-0.54 and r=-0.57, p<0.01 respectively) and logarithmic transformation of brain natriuretic peptide concentration (r=0.65 and r=0.65, p<0.01, respectively). These revealed significant correlations with cardiac index (r=-0.50 and r=-0.47, p<0.01, respectively) and pulmonary vascular resistance (PVR, r=0.45 and r=0.45, p=0.01, respectively). During a median follow-up of 33 months, 25 patients (74%) had follow-up examinations. Mean pulmonary arterial pressure (mPAP, 54±13 to 46±16 mmHg, p=0.03) and PVR (11±5 to 6±2 wood units, p<0.01) were significantly decreased with pulmonary vasodilator treatment. RVLSglobal (-12±5 to -16±5%, p<0.01) and RVLSFW (-14±5 to -18±5%, p<0.01) were significantly improved. The decrease of mPAP was significantly correlated with improvement of RVLSglobal (r=0.45, p<0.01) and RVLSFW (r=0.43, p<0.01). The PVR change demonstrated significant correlation with improvement of RVLSglobal (r=0.40, p<0.01). Conclusion RVLS correlates with functional and invasive hemodynamic parameters in PAH patients. Decrease of mPAP and PVR as a result of treatment was associated with improvement of RVLS.

A study of conductive elastomer composites reinforced with sulfonic acid doped polyaniline coated titanium dioxide

Youn-Gyu Han,Takafumi Kusunose,Tohru Sekino 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.2

In the present study, we report on the fabrication of hybrid composites of conductive silicone elastomer with TiO2/PANI-DBSA dispersion. The hybrid composites with conductive fillers, TiO2/PANI-DBSA, were prepared via an in-situ polymerization method with various TiO2 contents. The novel elastomer composites were prepared by dispersing TiO2/PANI-DBSA at room temperature in vulcanized silicone elastomers. The morphological, structural and electrical properties of TiO2/PANI-DBSA and their elastomer blends were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrical resistivity measurements. It was found that the electrical conductivity of the composite powder coated with about 20 wt.% PANI-DBSA was 46,000 (104) times higher than that of bare TiO2 powder. Also the electrical conductivity of the silicone elastomers composites of TiO2/PANI-DBSA were changed from 10−14 S/cm to 0.295S/cm (10 wt.% TiO2/PANI-DBSA). The novel elastomer composite had a percolation threshold between 1-3 wt.% PANI-DBSA. In the present study, we report on the fabrication of hybrid composites of conductive silicone elastomer with TiO2/PANI-DBSA dispersion. The hybrid composites with conductive fillers, TiO2/PANI-DBSA, were prepared via an in-situ polymerization method with various TiO2 contents. The novel elastomer composites were prepared by dispersing TiO2/PANI-DBSA at room temperature in vulcanized silicone elastomers. The morphological, structural and electrical properties of TiO2/PANI-DBSA and their elastomer blends were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrical resistivity measurements. It was found that the electrical conductivity of the composite powder coated with about 20 wt.% PANI-DBSA was 46,000 (104) times higher than that of bare TiO2 powder. Also the electrical conductivity of the silicone elastomers composites of TiO2/PANI-DBSA were changed from 10−14 S/cm to 0.295S/cm (10 wt.% TiO2/PANI-DBSA). The novel elastomer composite had a percolation threshold between 1-3 wt.% PANI-DBSA.

Thermoelectric properties of perovskite-type rare earth cobalt oxide solid solutions Pr1−xDyx

Hideki Hashimoto,Takafumi Kusunose,Tohru Sekino 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.3

Perovskite-type rare earth cobalt oxide Pr1−xDyxCoO3 (x = 0, 0.25, 0.5, 0.75 and 1) ceramics were fabricated by reaction sintering of the corresponding metal oxide powders, and their thermoelectric properties were evaluated up to 873 K. The electrical properties of Pr1−xDyxCoO3 varied according to a variation in the x value, whereas the thermal conductivity of the solid solutions (x = 0.25 − 0.75) tends to be lower than that of both end components (x = 0 and 1). As the results,Pr0.75Dy0.25CoO3 (x = 0.25) showed the highest figure of merit, Z = 5.72 × 10−5 K−1 at 773 K in the present Pr1−xDyxCoO3 system. This is considered due mainly to the effect of decreasing thermal conductivity caused by phonon scattering of partially substituted A-site ions. These results suggest that the fabrication of solid solutions is effective in improving the thermoelectric properties of the RCoO3 system.

ELECTRON-POSITRON PAIRS IN ACCRETION DISKS

Shin, Mine-Shige,Kusunose, Masaaki The Korean Astronomical Society 1993 天文學論叢 Vol.8 No.1

Recent X-ray observations of the accretion disks in stellar black hole candidates have revealed rather complex behavior, which cannot be fully described by the simple picture of the standard disk model. In this paper, therefore, we discuss the effects of e+e- pair creation on the structure and the stability of hot accretion disks, aiming at the thorough understanding of emission properties of X-ray binaries containing black holes.

Magnetic-field-induced Odd-frequency Superconductivity in s-Wave Superconductors

Masashige Matsumoto,Mikito Koga,Hiroaki Kusunose 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3

The wavefunction of the Cooper pair of the conventional BCS state is characterized by an evenparity(s-wave) spin-singlet state. An external magnetic field is well known to modify the wavefunctionof the Cooper pair and to break the conventional BCS superconducting state. We find thatthe wavefunction of the modified Cooper pair contains a spin-triplet component with s-wave orbitalsymmetry. While the spin-triplet s-wave Cooper pair is forbidden owing to the fermion property,it is permitted in the generalized theoretical framework containing an odd-frequency dependenceof the order parameter. We investigate this point on the basis of the self-consistent calculationin the Eliashberg theory and find that the odd-frequency order parameter coexists with the evenfrequencyone. We also report how the physical properties are affected by the induced odd-frequencysuperconducting order parameter.

Predictive Value of Localized Stenosis of the Main Pancreatic Duct for Early Detection of Pancreatic Cancer

Yoshihide Kanno,Shinsuke Koshita,Takahisa Ogawa,Hiroaki Kusunose,Kaori Masu,Toshitaka Sakai,Keisuke Yonamine,Yujiro Kawakami,Yuki Fujii,Kazuaki Miyamoto,Toji Murabayashi,Fumisato Kozakai,Jun Horaguchi 대한소화기내시경학회 2019 Clinical Endoscopy Vol.52 No.6

Background/Aims: In this study, we aimed to evaluate the predictive value of localized stenosis of the main pancreatic duct (MPD) forearly detection of pancreatic cancer. Methods: Among 689 patients who underwent endoscopic retrograde pancreatography from January 2008 to September 2018, 19patients with MPD findings were enrolled. These patients showed findings for indicating suspicious pancreatic cancer at an early stage(FiCE); FiCE was defined as a single, localized stenosis in the MPD without a detectable mass (using any other imaging methods) andwithout other pancreatic diseases, such as definite chronic pancreatitis, intraductal papillary mucinous neoplasm, and autoimmunepancreatitis. Final diagnoses were established by examining resected specimens or through follow-up examinations after an interval of>5 years. Results: Among 19 patients with FiCE, 11 underwent surgical resection and 8 were evaluated after a >5-year observation period. Thefinal diagnosis of the MPD stenosis was judged to be pancreatic cancer in 9 patients (47%), including 3 with intraepithelial cancer, andto be a non-neoplastic change in 10. The sensitivity, specificity, and accuracy of preoperative pancreatic juice cytology were 75%, 100%,and 88%, respectively. Conclusions: The predictive value of FiCE for pancreatic cancer prevalence was 47%. Histological confirmation with pancreatic juicecytology is necessary before surgical resection.