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Reaction Zone Thickness of Turbulent Premixed Flame
Yamamoto, Kazuhiro,Nishizawa, Yasuki,Onuma, Yoshiaki The Korean Society of Combustion 2001 한국연소학회지 Vol.6 No.2
Usually, we use the flame thickness and turbulence scale to classify the flame structure on a phase diagram of turbulent combustion. The flame structure in turbulence is still in debate, and many studies have been done. Since the flame motion is rapid and its reaction zone thickness is very thin, it is difficult to estimate the flame thickness. Here, we propose a new approach to determine the reaction zone thickness based on ion current signals obtained by an electrostatic probe, which has enough time and space resolution to detect flame fluctuation. Since the signal depends on the flow condition and flame curvature, it may be difficult to analyze directly these signals and examine the flame characteristics. However, ion concentration is high only in the region where hydrocarbon-oxygen reactions occur, and we can specify the reaction zone. Based on the reaction zone existing, we estimate the reaction zone thickness. We obtain the thickness of flames both in the cyclone-jet combustor and on a Bunsen burner, compared with theoretically predicted value, the Zeldovich thickness. Results show that the experimentally obtained thickness is almost the same as the Zeldovich thickness. It is concluded that this approach can be used to obtain the local flame structure for modeling turbulent combustion.
( Sayuri Yamamoto ),( Yurika Kawamura ),( Kazuhiro Yamamoto ),( Yoshiharu Yamaguchi ),( Yasuhiro Tamura ),( Shinya Izawa ),( Hiroaki Nakagawa ),( Yoshinori Wakita ),( Yasutaka Hijikata ),( Masahide Eb 대한소화기기능성질환·운동학회 2021 Journal of Neurogastroenterology and Motility (JNM Vol.27 No.4
Background/Aims Chronic constipation and lifestyle factors can affect sleep quality. We evaluated the relationship between chronic constipation and sleep in the Japanese population. Methods This cross-sectional internet-based survey included 3000 subjects with constipation, classified according to sleep status (good/poor). Primary endpoints were Bristol stool form scale (BSFS) score and correlations between sleep disorder criteria of the Pittsburgh Sleep Quality Index (PSQI) and sleep status (good/poor sleep). Secondary endpoints included correlations between quality of life (QOL) and mood, medical, lifestyle, and sleep factors. Results The proportion of participants with BSFS category 4 (normal stool) was significantly higher in the good sleep group (P < 0.001). Sleep disturbance (P < 0.05), sleep quality, and duration, use of hypnotic medication, and daytime dysfunction of PSQI (all P < 0.001) significantly correlated with poor sleep. In the poor sleep group, QOL was significantly worse and anxiety and depression levels were significantly higher (all P < 0.001) compared with the good sleep group. Anemia and smoking (both P < 0.05), recent body weight increases, and poor eating habits (all P < 0.001) were significantly higher in the poor sleep group. Male sex, onset associated with change in frequency of stools, sensation of incomplete evacuation for at least 25% of defecations, and manual maneuvers to facilitate at least 25% of defecations correlated with poor sleep. Conclusions Subjects with constipation and poor sleep experienced severe symptoms and had poor QOL. These data support the need for a multifocal treatment approach, including lifestyle advice and pharmacotherapy. (J Neurogastroenterol Motil 2021;27:602-611)
Preoperative serum microRNAs as potential prognostic biomarkers in ovarian clear cell carcinoma
Kazuhiro Suzuki,Akira Yokoi,Kosuke Yoshida,Tomoyasu Kato,Takahiro Ochiya,Yusuke Yamamoto,Hiroaki Kajiyama 대한부인종양학회 2023 Journal of Gynecologic Oncology Vol.34 No.3
Objective: Ovarian clear cell carcinoma (OCCC) is a subtype of epithelial ovarian carcinoma with poor prognosis. However, no effective biomarkers have been established for predicting unfavorable events, including recurrence and poor prognoses. Serum microRNAs (miRNAs) have been increasingly reported to be useful in predicting a patient’s condition and have been recognized as a potentially less-invasive source for liquid biopsy in cancer. Therefore, this study aimed to evaluate serum miRNA profiles from patients with OCCC and to establish biomarker for predicting the prognoses. Methods: The GSE106817, which included preoperative serum miRNA profiles of patients with ovarian tumors, was used, and clinical information was investigated. In all, 66 patients with OCCC were included, excluding those with other histological subtypes or insufficient prognostic information. Moreover, miRNA profiles of OCCC tissues were also examined. Results: The median follow-up period was 64.3 (8.0–153.3) months. Based on multivariable Cox regression analyses and the expression of miRNAs in OCCC tissues, miR-150-3p, miR-3195, and miR-7704 were selected as miRNA candidates associated with both progression-free survival (PFS) and overall survival (OS). Then, the prognostic index was calculated based on expression values of 3 serum miRNAs. Kaplan-Meier survival analysis indicated that the prognostic index was significantly predictive of PFS and OS (p=0.004 and p=0.012, respectively). Conclusion: Preoperative serum miRNA profiles of miR-150-3p, miR-3195, and miR-7704 can be used to potentially predict the prognosis of patients with OCCC.
Yamamoto, Akira,Shin, Ryong-Woon,Hasegawa, Kazuhiro,Naki, Hironobu,Sato, Hiroyuki,Yoshimasu, Fumio,Kitamoto, Tetsuyuki 한림대학교 환경·생명과학연구소 2002 [일송 국제심포지엄] 노화와 만성퇴행성 신경질환 Vol.- No.4
Iron as well as aluminum is reported to accumulate in neurons with neurofibrillary tangles (NFTs) of Alzheimer's disease(AD) brain. Previously we demonstrated that aluminum(Ⅲ) shows phosphate-dependent binding with hyperphosphorylated τ(PHFτ), the major constituent of NFTs, thereby inducing aggregation of PHFτ. Herein we report that iron(Ⅲ) can also induce aggregation of soluble PHFτ to occur, iron in the oxidized state (Ⅲ) is essential since iron in the reduced state (Ⅲ) lacks such ability. Furthermore, iron (Ⅲ)-induced aggregation is reversed by reducing iron (Ⅲ) to iron (Ⅱ). Thus the iron-participating aggregation is mediated not only by τ phosphorylation but also by the transition of iron between reduced (Ⅱ) and oxidized (Ⅲ) states. Further incubation of insoluble PHFτ aggregates isolated from AD brain with reducing agents produced liberation of solubilized PHFτ and iron (Ⅱ), indicating that PHFτ in association with iron (Ⅲ) constitutes the insoluble pool of PHFτ. These results indicate that iron might play a role in the aggregation of PHFτ leading to the formation of NFTs in AD brain.
Masashi Yamamoto,Kazuhiro Yubai,Junji Hirai 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
The H∞ loop-shaping method is known to be an effective control method, however, it has two drawbacks. The first is that it is difficult to select appropriate loop-shaping weights, and the second is that the resulting controller is very complex. For the first drawback, Lanzon has proposed a suboptimal loop-shaping weight design method. It is formulated as a generalized eigenvalue minimization problem. This suboptimal loop-shaping weight design method provides high order weights, emphasizing the second drawback. To resolve these two drawbacks, a reduced-order loop-shaping weight and a stabilizing controller design methods are proposed in this paper. In the proposed method, the weight structure is first fixed, and the weight is decomposed into the frequency-dependent vector and the parameter matrices characterizing the loop-shaping weight. Since the open-loop constraints are represented as linear matrix inequalities with respect to the parameter matrices, the reduced-order loop-shaping weight design problem is formulated as a generalized eigenvalue minimization problem as well as the Lanzon’s suboptimal loop-shaping weight design method. Moreover, the stabilizing controller is first fixed to the initial stabilizing controller. The initial stabilizing controller is designed for the shaped plant obtained by the reduced-order weight design, by solving linear matrix inequalities. The proposed method can reduce the designer’s burden. The effectiveness of the proposed method is verified experimentally by the gain-scheduling control of a vertical-type inverted pendulum system.
Sugiura, Tsutomu,Yamamoto, Kazuhiko,Horita, Satoshi,Murakami, Kazuhiro,Tsutsumi, Sadami,Kirita, Tadaaki Korean Academy of Periodontology 2016 Journal of Periodontal & Implant Science Vol.46 No.3
Purpose: This study investigated the effects of bone density and crestal cortical bone thickness at the implant-placement site on micromotion (relative displacement between the implant and bone) and the peri-implant bone strain distribution under immediate-loading conditions. Methods: A three-dimensional finite element model of the posterior mandible with an implant was constructed. Various bone parameters were simulated, including low or high cancellous bone density, low or high crestal cortical bone density, and crestal cortical bone thicknesses ranging from 0.5 to 2.5 mm. Delayed- and immediate-loading conditions were simulated. A buccolingual oblique load of 200 N was applied to the top of the abutment. Results: The maximum extent of micromotion was approximately $100{\mu}m$ in the low-density cancellous bone models, whereas it was under $30{\mu}m$ in the high-density cancellous bone models. Crestal cortical bone thickness significantly affected the maximum micromotion in the low-density cancellous bone models. The minimum principal strain in the peri-implant cortical bone was affected by the density of the crestal cortical bone and cancellous bone to the same degree for both delayed and immediate loading. In the low-density cancellous bone models under immediate loading, the minimum principal strain in the peri-implant cortical bone decreased with an increase in crestal cortical bone thickness. Conclusions: Cancellous bone density may be a critical factor for avoiding excessive micromotion in immediately loaded implants. Crestal cortical bone thickness significantly affected the maximum extent of micromotion and peri-implant bone strain in simulations of low-density cancellous bone under immediate loading.
Sugiura, Tsutomu,Yamamoto, Kazuhiko,Horita, Satoshi,Murakami, Kazuhiro,Tsutsumi, Sadami,Kirita, Tadaaki Korean Academy of Periodontology 2017 Journal of Periodontal & Implant Science Vol.47 No.4
Purpose: The purpose of this study was to investigate the effects of implant tilting and the loading direction on the displacement and micromotion (relative displacement between the implant and bone) of immediately loaded implants by in vitro experiments and finite element analysis (FEA). Methods: Six artificial bone blocks were prepared. Six screw-type implants with a length of 10 mm and diameter of 4.3 mm were placed, with 3 positioned axially and 3 tilted. The tilted implants were $30^{\circ}$ distally inclined to the axial implants. Vertical and mesiodistal oblique ($45^{\circ}$ angle) loads of 200 N were applied to the top of the abutment, and the abutment displacement was recorded. Nonlinear finite element models simulating the in vitro experiment were constructed, and the abutment displacement and micromotion were calculated. The data on the abutment displacement from in vitro experiments and FEA were compared, and the validity of the finite element model was evaluated. Results: The abutment displacement was greater under oblique loading than under axial loading and greater for the tilted implants than for the axial implants. The in vitro and FEA results showed satisfactory consistency. The maximum micromotion was 2.8- to 4.1-fold higher under oblique loading than under vertical loading. The maximum micromotion values in the axial and tilted implants were very close under vertical loading. However, in the tilted implant model, the maximum micromotion was 38.7% less than in the axial implant model under oblique loading. The relationship between abutment displacement and micromotion varied according to the loading direction (vertical or oblique) as well as the implant insertion angle (axial or tilted). Conclusions: Tilted implants may have a lower maximum extent of micromotion than axial implants under mesiodistal oblique loading. The maximum micromotion values were strongly influenced by the loading direction. The maximum micromotion values did not reflect the abutment displacement values.
Tamaki Tanaka,Kazuhiro Takehara,Natsumi Yamashita,Mika Okazawa-Sakai,Kazuya Kuraoka,Norihiro Teramoto,Kenichi Taguchi,Katsushige Yamashiro,Hidenori Kato,Tomoya Mizunoe,Rie Suzuki,Dan Yamamoto,Arisa Ue 대한부인종양학회 2022 Journal of Gynecologic Oncology Vol.33 No.5
Objective: To clarify the frequency of deficient mismatch repair (dMMR) in Japanese ovarian cancer patients, we examined microsatellite instability (MSI) status and immunohistochemistry (IHC) subtypes, including endometrioid carcinoma (EMC), clear cell carcinoma (CCC), or a mixture of both (Mix). Methods: We registered 390 patients who were diagnosed with EMC/CCC/Mix between 2006 and 2015 and treated at seven participating facilities. For 339 patients confirmed eligible by the Central Pathological Review Board, MSI, IHC, and MutL homolog 1 methylation analyses were conducted. The tissues of patients with Lynch syndrome (LS)-related cancer histories, such as colorectal and endometrial cancer, were also investigated. Results: MSI-high (MSI-H) status was observed in 2/217 CCC (0.9%), 10/115 EMC (8.7%), and 1/4 Mix (25%). Additionally, loss of MMR protein expression (LoE-MMR) was observed in 5/219 (2.3%), 16/115 (14.0%), and 1/4 (25%) patients with CCC, EMC, and Mix, respectively. Both MSI-H and LoE-MMR were found significantly more often in EMC (p<0.001). The median (range) ages of patients with MMR expression and LoE-MMR were 54 (30–90) and 46 (22–76) (p=0.002), respectively. In the multivariate analysis, advanced stage and histological type were identified as prognostic factors. Conclusion: The dMMR rate for EMC/CCC was similar to that reported in Western countries. In Japan, it is assumed that the dMMR frequency is higher because of the increased proportion of CCC.