82 results on '"Yuki Usui"'
Search Results
2. Residual deformity after femoral neck fracture affects the location of osteonecrosis of the femoral head
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Masanori Nishi, Takashi Atsumi, Yasushi Yoshikawa, Ichiro Okano, Ryosuke Nakanishi, Minoru Watanabe, Yuki Usui, and Yoshifumi Kudo
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femoral head ,osteonecrosis of the femoral head ,femoral neck fracture ,femoral neck fractures ,osteonecrosis of the femoral head (onfh) ,deformities ,hips ,radiographs ,prognosis ,osteonecrosis ,femoral neck ,osteotomy ,Orthopedic surgery ,RD701-811 - Abstract
Aims: The localization of necrotic areas has been reported to impact the prognosis and treatment strategy for osteonecrosis of the femoral head (ONFH). Anteroposterior localization of the necrotic area after a femoral neck fracture (FNF) has not been properly investigated. We hypothesize that the change of the weight loading direction on the femoral head due to residual posterior tilt caused by malunited FNF may affect the location of ONFH. We investigate the relationship between the posterior tilt angle (PTA) and anteroposterior localization of osteonecrosis using lateral hip radiographs. Methods: Patients aged younger than 55 years diagnosed with ONFH after FNF were retrospectively reviewed. Overall, 65 hips (38 males and 27 females; mean age 32.6 years (SD 12.2)) met the inclusion criteria. Patients with stage 1 or 4 ONFH, as per the Association Research Circulation Osseous classification, were excluded. The ratios of anterior and posterior viable areas and necrotic areas of the femoral head to the articular surface were calculated by setting the femoral head centre as the reference point. The PTA was measured using Palm’s method. The association between the PTA and viable or necrotic areas of the femoral head was assessed using Spearman’s rank correlation analysis (median PTA 6.0° (interquartile range 3 to 11.5)). Results: We identified a negative correlation between PTA and anterior viable areas (rho −0.477; p = 0.001), and no correlation between PTA and necrotic (rho 0.229; p = 0.067) or posterior viable areas (rho 0.204; p = 0.132). Conclusion: Our results suggest that residual posterior tilt after FNF could affect the anteroposterior localization of necrosis. Cite this article: Bone Jt Open 2024;5(5):394–400. more...
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- 2024
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3. Pathological Complete Response to Neoadjuvant Chemotherapy in a Patient with HER2-Positive Squamous Cell Carcinoma of the Breast
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Yuki Usui, Ryoichi Matsunuma, Kei Yamaguchi, Ryosuke Hayami, Aya Muramatsu, Makoto Suzuki, and Michiko Tsuneizumi
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pathological complete response ,breast cancer ,squamous cell carcinoma ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Squamous cell carcinoma (SCC) of the breast is a rare malignancy that usually has a triple-negative phenotype and poor clinical outcomes. Because HER2-positive SCC of the breast is extremely rare, its clinicopathologic features are understudied, and the effects of neoadjuvant chemotherapy including anti-HER2-targeted therapy on the tumor are unclear, although treatment resistance was described in some reports. In this study, we reported a case of HER2-positive SCC of the breast in which a pathological complete response to neoadjuvant chemotherapy was observed. more...
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- 2021
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4. Relationship Between Acetabular Hounsfield Unit Values and Periprosthetic Fractures in Cementless Total Hip Arthroplasty: A Matched Case-Control Study
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Masanori Nishi, MD, Ichiro Okano, MD, Yasushi Yoshikawa, MD, PhD, Hidenori Tochio, MD, Yuki Usui, MD, PhD, and Katsunori Inagaki, MD, PhD
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Total hip arthroplasty ,Acetabulum ,Periprosthetic fracture ,Hounsfield unit ,Occult fracture ,Orthopedic surgery ,RD701-811 - Abstract
Background: The association between regional bone status around the acetabulum and the incidence of intraoperative acetabulum fractures has not been extensively studied. We investigated the association of Hounsfield unit (HU) values on computed tomography in the regions of the acetabulum with periprosthetic fractures. Methods: We retrospectively reviewed records of 301 consecutive patients who underwent cementless total hip arthroplasty between October 2016 and December 2020. Using preoperative computed tomography taken in the 4 weeks preceding total hip arthroplasty, we measured HU values in 4 different acetabulum regions (anterior, medial, posterior, and superior). After identifying fracture cases, we identified a control group—matched in terms of sex, age, and preoperative diagnosis—selected in a 1:3 ratio among nonfracture patients treated in the same inclusive period. As the average HU values differed by region, we used the standardized value to compare fracture-site HUs. We ranked the standardized HU values for each acetabular site and compared the fracture site rank between the groups. Results: Intraoperative acetabular fractures were observed in 10 hips (3.2%), occurring most frequently in the superior region (40%). The standardized HU values of the fracture site were statistically lower in the fracture group (P = .039). We compared the ranks of the standardized HUs of the fractured parts with those of the corresponding parts in the control group; the fracture site had a significantly lower standardized HU rank, indicating that fractures tended to occur in the relatively “weaker-than-expected” parts. Conclusions: Periprosthetic fractures tended to occur at relatively weak parts of the acetabulum. more...
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- 2022
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5. Chronic dysphagia caused by Laryngo-vertebral Synostosis after anterior fusion for cervical spine trauma: a case report
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Ichiro Okano, Joe Omata, Yushi Hoshino, Yuki Usui, Tomoaki Toyone, and Katsunori Inagaki
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Synostosis ,Dysphagia ,Cricoid cartilage ,Cervical spine trauma ,Anterior fusion ,Omohyoid muscle flap ,Diseases of the musculoskeletal system ,RC925-935 - Abstract
Abstract Background Anterior cervical spine surgery is often associated with postoperative dysphagia, but chronic dysphagia caused by laryngo-vertebral synostosis is extremely rare. We report a case of chronic dysphagia caused by synostosis between the cricoid cartilage and cervical spine after anterior surgery for cervical spine trauma. Case presentations We present a case of a 39-year-old man who had sustained complex spine trauma at C5–6 associated with complete spinal cord injury at the age of 22; the patient presented with a 5-year history of chronic dysphagia. Computed tomography demonstrated posterior shift of the esophagus as well as calcification of the cricoid cartilage and its fusion to the right anterior tubercle of the C5 vertebra. A barium swallow study demonstrated significant barium aspiration into the airway and no laryngeal elevation. The patient underwent resection of the bony bridge and omohyoid muscle flap insertion. His symptoms ameliorated after surgery. Conclusion Synostosis between the cricoid cartilage and cervical spine may occur associated with cervical spine trauma and causes chronic dysphagia. Resection of the fused part can improve dysphagia caused by this rare condition and omohyoid muscle flap might be a good option to prevent recurrence. more...
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- 2020
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6. Biokinetic Evaluation of Contrast Media Loaded Carbon Nanotubes Using a Radiographic Device
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Mieko Takasaka, Shinsuke Kobayashi, Yuki Usui, Hisao Haniu, Shuji Tsuruoka, Kaoru Aoki, and Naoto Saito
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carbon nanotube ,peapod ,biokinetics ,biodistribution ,Chemical technology ,TP1-1185 - Abstract
Considerable progress has been made in various fields of applied research on the use of carbon nanotubes (CNTs). Because CNTs are fibrous nanomaterials, biosafety of CNTs has been discussed. The biokinetic data of CNTs, such as using the radioisotope of carbon and surface labeling of CNTs, have been reported. However, the use of radioisotopes requires a special facility. In addition, there are problems in the surface labeling of CNTs, including changes in surface properties and labels eliminating over time. In order to solve these problems and properly evaluate the biokinetics of CNTs, the authors synthesize peapods with platinum (Pt) encapsulated within the hollow region of Double-Walled CNTs (DWCNTs) and develop a new system to evaluate biokinetics using widely available imaging equipment. In the cell assay, no significant difference is observed with and without Pt in CNTs. In animal studies, radiography of the lungs of rats that inhaled Pt-peapods show the detectability of Pt inside the CNTs. This new method using Pt-peapods enables image evaluation with a standard radiographic imaging device without changing the surface property of the CNTs and is effective for biokinetics evaluation of CNTs. more...
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- 2021
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7. A three-dimensional block structure consisting exclusively of carbon nanotubes serving as bone regeneration scaffold and as bone defect filler.
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Manabu Tanaka, Yoshinori Sato, Hisao Haniu, Hiroki Nomura, Shinsuke Kobayashi, Seiji Takanashi, Masanori Okamoto, Takashi Takizawa, Kaoru Aoki, Yuki Usui, Ayumu Oishi, Hiroyuki Kato, and Naoto Saito
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Medicine ,Science - Abstract
Many recent studies have been conducted to assess the ability of composite materials containing carbon nanotubes (CNTs) with high bone affinity to serve as scaffolds in bone regenerative medicine. These studies have demonstrated that CNTs can effectively induce bone formation. However, no studies have investigated the usefulness of scaffolds consisting exclusively of CNTs in bone regenerative medicine. We built a three-dimensional block entity with maximized mechanical strength from multi-walled CNTs (MWCNT blocks) and evaluated their efficacy as scaffold material for bone repair. When MWCNT blocks containing recombinant human bone morphogenetic protein-2 (rhBMP-2) were implanted in mouse muscle, ectopic bone was formed in direct contact with the blocks. Their bone marrow densities were comparable to those of PET-reinforced collagen sheets with rhBMP-2. On day 1 and day 3, MC3T3-E1 preosteoblasts were attached to the scaffold surface of MWCNT blocks than that of PET-reinforced collagen sheets. They also showed a maximum compression strength comparable to that of cortical bone. Our MWCNT blocks are expected to serve as bone defect filler and scaffold material for bone regeneration. more...
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- 2017
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8. Manufacturing Strategy for Multiwalled Carbon Nanotubes as a Biocompatible and Innovative Material
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Hisao Haniu, Naoto Saito, Yoshikazu Matsuda, Yuki Usui, Kaoru Aoki, Masayuki Shimizu, Nobuhide Ogihara, Kazuo Hara, Seiji Takanashi, Masanori Okamoto, Koichi Nakamura, Norio Ishigaki, Tamotsu Tsukahara, and Hiroyuki Kato more...
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Technology (General) ,T1-995 - Abstract
We investigated the relationship between differences in multiwalled carbon nanotubes (MWCNTs) and the biological responses they elicit in order to develop biocompatible MWCNTs. We exposed human bronchial epithelial (BEAS-2B) cells to two sizes and six grades of MWCNTs and measured the resulting cell viability, total reactive oxygen and/or nitrogen species (tROS/RNS) production, and cytokine secretion. Although differences in cellular tROS production were associated with differences in grades of MWCNTs, the graphitization temperature of MWCNTs apparently did not influence tROS production. However, cell viability was affected by MWCNT graphitization temperature and diameter. Moreover, cytokine secretion was apparently affected by treatment temperature, but not MWCNT diameter. We concluded that the highest temperature resulted in the most biocompatibility because impurities and carbon defects were removed from the MWCNTs. However, other mechanisms are possible. Therefore, it is important to optimize each type of MWCNT by monitoring biological responses that type elicits during the manufacturing stage for applications involving biology and medicine. more...
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- 2012
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9. Accelerated Dewatering of Thick All-Cellulose Nanofiber Mats by Air Pressure Application.
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Nakagaito, Antonio N., Hitoshi Takagi, and Yuki Usui
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AIR pressure ,FILTER paper ,CELLULOSE ,CELLULOSE fibers - Abstract
Even though making thin sheets of cellulose nanofiber by a papermakinglike process is straightforward, obtaining thicker papers or plates is extremely time consuming. Dewatering is exceedingly slow as the nanocellulose is deposited on the filter paper during filtration, hindering water flow. This study proposes a simple device that speeds up dewatering through the application of air pressure on the aqueous suspension being filtered. A relative pressure of 0.5 MPa reduced the dewatering time of 72 h for a conventional vacuum filtration to 16 h without compromising the mechanical properties of the final molded material. [ABSTRACT FROM AUTHOR] more...
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- 2025
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10. Symmetric equilibrium of multi-agent reinforcement learning in repeated prisoner's dilemma.
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Yuki Usui and Masahiko Ueda
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- 2021
11. High-Degree Valgus Osteotomy for Severe Femoral Head Osteonecrosis After Femoral Neck Fracture with Nonunion
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Masanori Nishi, Takashi Atsumi, Yasushi Yoshikawa, Ryosuke Nakanishi, Tsubasa Ishikawa, Yuki Usui, and Katsunori Inagaki
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Orthopedics and Sports Medicine ,Surgery - Published
- 2023
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12. Multiwall Carbon Nanotube Composites as Artificial Joint Materials
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Hiroyuki Kato, Takako Osawa, Yuki Usui, Manabu Tanaka, Ken Ichi Sako, Kaoru Aoki, Takumi Okihara, Naoyuki Nishimura, Kazutaka Miyamae, Hisao Haniu, Shigeaki Moriyama, Atsushi Sobajima, and Naoto Saito more...
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Materials science ,Friction ,Arthroplasty, Replacement, Hip ,0206 medical engineering ,Composite number ,Biomedical Engineering ,Biocompatible Materials ,02 engineering and technology ,Carbon nanotube ,law.invention ,Biomaterials ,Mice ,chemistry.chemical_compound ,law ,Materials Testing ,Animals ,Composite material ,Joint (geology) ,Nanotubes, Carbon ,Biomaterial ,Polyethylene ,021001 nanoscience & nanotechnology ,020601 biomedical engineering ,Rats ,Wear resistance ,chemistry ,Artificial joints ,0210 nano-technology ,Total hip arthroplasty - Abstract
Because ultrahigh-molecular-weight polyethylene (UHMWPE) is susceptible to frictional wear when used in sliding members of artificial joints, it is common practice to use cross-linked UHMWPE instead. However, cross-linked UHMWPE has low impact resistance; implant breakage has been reported in some cases. Hence, sliding members of artificial joints pose a major trade-off between wear resistance and impact resistance, which has not been resolved by any UHMWPE. On the other hand, multiwall carbon nanotubes (MWCNTs) are used in industrial products for reinforcement of polymeric materials but not used as biomaterials because of their unclear safety. In the present study, we attempted to solve this trade-off issue by complexing UHMWPE with MWCNTs. In addition, we assessed the safety of these composites for use in sliding members of artificial joints. The results showed the equivalence of MWCNT/UHMWPE composites to cross-linked UHMWPE in terms of wear resistance and to non-cross-linked UHMWPE in terms of impact resistance. In addition, all MWCNT/UHMWPE composites examined complied with the requirements of biosafety testing in accordance with the ISO10993-series specifications for implantable medical devices. Furthermore, because MWCNTs can occur alone in wear dust, MWCNTs in an amount of about 1.5 times that contained in the dust produced from 50 years of wear (in the worst case) were injected into rat knees, which were monitored for 26 weeks. Although mild inflammatory reactions occurred in the joints, the reactions soon became quiescent. In addition, the MWCNTs did not migrate to other organs. Furthermore, MWCNTs did not exhibit carcinogenicity when injected into the knees of mice genetically modified to spontaneously develop cancer. The MWCNT/UHMWPE composite is a new biomaterial expected to be safe for clinical applications in both total hip arthroplasty and total knee arthroplasty as the first sliding member of artificial joints to have both high wear resistance and high impact resistance. more...
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- 2020
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13. Comparative study of scintillation properties of Ga2O3 single crystals and ceramics
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Yuki Usui, Noriaki Kawaguchi, Takayuki Yanagida, Go Okada, Naoki Kawano, and Takumi Kato
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010302 applied physics ,Scintillation ,Photoluminescence ,Materials science ,Biophysics ,Analytical chemistry ,Spark plasma sintering ,Sintering ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Biochemistry ,Atomic and Molecular Physics, and Optics ,0103 physical sciences ,Exponential decay ,0210 nano-technology ,Absorption (electromagnetic radiation) ,Luminescence ,Single crystal - Abstract
A series of bulk Ga2O3 were prepared by four different methods (Floating Zone (FZ), Edge-defined Film-fed Grown (EFG), spark plasma sintering (SPS) and conventional sintering in air) to obtain in single crystal and ceramic forms. In photoluminescence (PL), all the samples showed defect-related luminescence due to recombination between donors and acceptors; however, the peak position was different in each sample. The PL and scintillation decay curves were approximated by a sum of two exponential decay functions, and emission origins were attributed to to recombination between donors and acceptors. Pulse height spectrum of 241Am α-ray irradiation was demonstrated by using the present samples, and we confirmed that the one prepared by the EFG method indicated a clear full energy absorption peak, and the estimated light yield was 3200 ± 320 ph/5.5 MeV-α. more...
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- 2018
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14. Scintillation and optical properties of Sn-doped Ga2O3 single crystals
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Noriaki Kawaguchi, Daisuke Nakauchi, Yuki Usui, Go Okada, Naoki Kawano, and Takayuki Yanagida
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010302 applied physics ,Scintillation ,Photoluminescence ,Materials science ,Doping ,Analytical chemistry ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Acceptor ,Yield (chemistry) ,0103 physical sciences ,General Materials Science ,Irradiation ,Exponential decay ,0210 nano-technology ,Luminescence - Abstract
Sn-doped Ga2O3 single crystals were synthesized by the Floating Zone (FZ) method. In photoluminescence (PL) under the excitation wavelength of 280 nm, we observed two types of luminescence: (1) defect luminescence due to recombination of the donor/acceptor pairs which appears at 430 nm and (2) the nsnp-ns2 transitions of Sn2+ which appear at 530 nm. The PL and scintillation decay time curves of the Sn-doped samples were approximated by a sum of exponential decay functions. The faster two components were ascribed to the defect luminescence, and the slowest component was owing to the nsnp-ns2 transitions. In the pulse height spectrum measurements under 241Am α-rays irradiation, all the Sn-doped Ga2O3 samples were confirmed to show a full energy absorption peak but the undoped one. Among the present samples, the 1% Sn-doped sample exhibited the highest scintillation light yield (1,500 ± 150 ph/5.5 MeV-α). more...
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- 2018
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15. Effects of long-term intake of a yogurt fermented with Lactobacillus delbrueckii subsp. bulgaricus 2038 and Streptococcus thermophilus 1131 on mice
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Hiroko Ohmiya, Seiya Imoto, Satoshi Uematsu, Naoki Takemura, Yasuo Ouchi, Hiromi Suzuki, Satoko Hagiwara, Yukio Asami, Satomi Koyama, Kosuke Fujimoto, Yasumasa Kimura, Hirotoshi Tanaka, Kyosuke Kobayashi, Yuki Usui, Takeshi Satoh, and Gérard Eberl more...
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Male ,0301 basic medicine ,Streptococcus thermophilus ,Firmicutes ,030106 microbiology ,Immunology ,Antimicrobial peptides ,Butyrate ,Mice ,03 medical and health sciences ,Lactobacillus ,Animals ,Immunology and Allergy ,Food science ,Lactobacillus delbrueckii ,Mice, Inbred ICR ,biology ,Probiotics ,food and beverages ,Bacteroidetes ,General Medicine ,Yogurt ,biology.organism_classification ,Intestines ,030104 developmental biology ,Fermentation ,Lactobacillus delbrueckii subsp. bulgaricus - Abstract
The gut is an extremely complicated ecosystem where micro-organisms, nutrients and host cells interact vigorously. Although the function of the intestine and its barrier system weakens with age, some probiotics can potentially prevent age-related intestinal dysfunction. Lactobacillus delbrueckii subsp. bulgaricus 2038 and Streptococcus thermophilus 1131, which are the constituents of LB81 yogurt, are representative probiotics. However, it is unclear whether their long-term intake has a beneficial influence on systemic function. Here, we examined the gut microbiome, fecal metabolites and gene expression profiles of various organs in mice. Although age-related alterations were apparent in them, long-term LB81 yogurt intake led to an increased Bacteroidetes to Firmicutes ratio and elevated abundance of the bacterial family S24-7 (Bacteroidetes), which is known to be associated with butyrate and propanoate production. According to our fecal metabolite analysis to detect enrichment, long-term LB81 yogurt intake altered the intestinal metabolic pathways associated with propanoate and butanoate in the mice. Gene ontology analysis also revealed that long-term LB81 yogurt intake influenced many physiological functions related to the defense response. The profiles of various genes associated with antimicrobial peptides-, tight junctions-, adherens junctions- and mucus-associated intestinal barrier functions were also drastically altered in the LB81 yogurt-fed mice. Thus, long-term intake of LB81 yogurt has the potential to maintain systemic homeostasis, such as the gut barrier function, by controlling the intestinal microbiome and its metabolites. more...
- Published
- 2018
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16. Scintillation properties of YAlO3 doped with Lu and Nd perovskite single crystals
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Takayuki Yanagida, Go Okada, Daisuke Nakauchi, Naoki Kawano, Yuki Usui, Masaki Akatsuka, Noriaki Kawaguchi, and Takumi Kato
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010302 applied physics ,Scintillation ,Range (particle radiation) ,Materials science ,Organic Chemistry ,Near-infrared spectroscopy ,Doping ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Inorganic Chemistry ,Decay time ,Lattice defects ,0103 physical sciences ,Irradiation ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,Spectroscopy ,Perovskite (structure) - Abstract
YAlO3 (YAP) single crystals doped with Lu and Nd were grown by the Floating Zone (FZ) method to evaluate their scintillation properties particularly emissions in the near-infrared (NIR) range. The Nd concentration was fixed to 0 or 1 mol% while the Lu concentration was varied from 0 to 30%. When X-ray was irradiated, the scintillation of Nd-doped samples was observed predominantly at 1064 nm due to 4F3/2 → 4I11/2 transition of Nd3+. In contrast, a weak emission around 700 nm appeared in the samples doped with only Lu, and the emission origin was attributed to defect centers. In the Nd3+-doped samples, the decay time was 94–157 μs due to the 4f-4f transitions of Nd3+ whereas the Lu-doped samples showed signal with the decay time of 1.45–1.54 ms. The emission origin of the latter signal was attributed to the perovskite lattice defect. more...
- Published
- 2018
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17. Symmetric equilibrium of multi-agent reinforcement learning in repeated prisoner's dilemma
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Masahiko Ueda and Yuki Usui
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FOS: Computer and information sciences ,Computer Science::Machine Learning ,0209 industrial biotechnology ,Computer Science::Computer Science and Game Theory ,Physics - Physics and Society ,Computer science ,Applied Mathematics ,Symmetric equilibrium ,Process (computing) ,FOS: Physical sciences ,020206 networking & telecommunications ,02 engineering and technology ,Prisoner's dilemma ,Physics and Society (physics.soc-ph) ,Dilemma ,Computational Mathematics ,020901 industrial engineering & automation ,Repeated prisoner’s dilemma game ,Computer Science - Computer Science and Game Theory ,Reinforcement learning ,0202 electrical engineering, electronic engineering, information engineering ,Mathematical economics ,Computer Science and Game Theory (cs.GT) - Abstract
We investigate the repeated prisoner's dilemma game where both players alternately use reinforcement learning to obtain their optimal memory-one strategies. We theoretically solve the simultaneous Bellman optimality equations of reinforcement learning. We find that the Win-stay Lose-shift strategy, the Grim strategy, and the strategy which always defects can form symmetric equilibrium of the mutual reinforcement learning process amongst all deterministic memory-one strategies., 29 pages, 6 figures more...
- Published
- 2021
18. Ce-doped Ga2O3 single crystalline semiconductor showing scintillation features
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Tomohisa Oya, Noriaki Kawaguchi, Yuki Usui, Go Okada, and Takayuki Yanagida
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010302 applied physics ,Scintillation ,Photoluminescence ,Materials science ,business.industry ,Doping ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Spectral line ,Electronic, Optical and Magnetic Materials ,Optics ,0103 physical sciences ,Irradiation ,Electrical and Electronic Engineering ,Exponential decay ,0210 nano-technology ,business ,Luminescence ,Single crystal - Abstract
We synthesized Ga2O3 crystals doped with 0.04, 0.61, 0.87 and 1.9% of Ce by the Floating Zone (FZ) method and measured the optical and scintillation properties systematically. All the Ce-doped Ga2O3 samples showed emission peaking around 420 nm in the X-ray induced scintillation as well as photoluminescence spectra under 280 nm excitation, and the origin of this emission was attributed to the 5d-4f transitions of Ce3+. The scintillation decay curves were approximated by a sum of three exponential decay functions, and the decay time constants ranged tens of nanoseconds, corresponding to the emission by Ce3+, and a few or hundreds nanoseconds, corresponding to the Ga2O3 host. The Ce-doped Ga2O3 samples also showed thermally-stimulated luminescence (TSL) after 10 Gy X-ray irradiation with the glow peak around 140 °C, and the TSL intensity increased with increasing the doping concentration of Ce. more...
- Published
- 2017
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19. Comparative study of scintillation and optical properties of Ga2O3 doped with ns2 ions
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Go Okada, Yuki Usui, Noriaki Kawaguchi, Tomohisa Oya, and Takayuki Yanagida
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010302 applied physics ,Physics ,Scintillation ,Photoluminescence ,Physics::Instrumentation and Detectors ,Mechanical Engineering ,Doping ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Ion ,Microsecond ,Mechanics of Materials ,0103 physical sciences ,General Materials Science ,Irradiation ,Exponential decay ,Atomic physics ,0210 nano-technology ,Excitation - Abstract
Ga2O3 crystals doped with nominally 1% ns2 ions (In, Tl, Sn, Pb, Sb and Bi) were synthesized by the Floating Zone (FZ) method, and we systematically evaluated the optical and scintillation properties. The peak emission was observed around 2.8 eV in photoluminescence (PL) under the excitation energy of 4.68 eV and around 3.0 eV in scintillation under X-ray irradiation. The PL and scintillation decay times were approximated by a sum of three exponential decay functions; and the derived decay times ranged several tens of nanoseconds, hundreds of nanoseconds and several microseconds. The slowest component was ascribed to the nsnp-ns2 transitions while the fastest and intermediate components were blamed for the defect-related emission. Among the present samples, Sn-doped Ga2O3 showed the highest scintillation light yield. more...
- Published
- 2017
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20. Metagenome Data on Intestinal Phage-Bacteria Associations Aids the Development of Phage Therapy against Pathobionts
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Satoru Miyano, Peter B. Ernst, Takeshi Satoh, Masanori Kakuta, Kosuke Fujimoto, Yuki Usui, Yoichi Furukawa, Yoshikazu Yuki, Rui Yamaguchi, Hiroshi Kiyono, Yasumasa Kimura, Kiyoshi Yamaguchi, Koji Kashima, Yoshiko Nakano, Seiya Imoto, Miho Uematsu, Satoshi Uematsu, Shintaro Sato, Georg Tremmel, Tetsuya Hayashi, Sheila E. Crowe, Yutaka Akiyama, Masaki Shimohigoshi, and Yunosuke Kawaguchi more...
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Phage therapy ,viruses ,medicine.medical_treatment ,Prophages ,Virulence ,Genome, Viral ,Microbiology ,Bacteriophage ,03 medical and health sciences ,Feces ,Mice ,Viral Proteins ,0302 clinical medicine ,Virology ,Endopeptidases ,medicine ,CRISPR ,Animals ,Humans ,Human virome ,Bacteriophages ,Microbiome ,Phage Therapy ,Prophage ,030304 developmental biology ,0303 health sciences ,biology ,Clostridioides difficile ,Bacteriome ,Sequence Analysis, DNA ,biology.organism_classification ,Anti-Bacterial Agents ,Gastrointestinal Microbiome ,Specific Pathogen-Free Organisms ,Mice, Inbred C57BL ,Disease Models, Animal ,Clostridium Infections ,Metagenome ,Parasitology ,Female ,030217 neurology & neurosurgery ,Genome, Bacterial - Abstract
Summary The application of bacteriophages (phages) is proposed as a highly specific therapy for intestinal pathobiont elimination. However, the infectious associations between phages and bacteria in the human intestine, which is essential information for the development of phage therapies, have yet to be fully elucidated. Here, we report the intestinal viral microbiomes (viromes), together with bacterial microbiomes (bacteriomes), in 101 healthy Japanese individuals. Based on the genomic sequences of bacteriomes and viromes from the same fecal samples, the host bacteria-phage associations are illustrated for both temperate and virulent phages. To verify the usefulness of the comprehensive host bacteria-phage information, we screened Clostridioides difficile-specific phages and identified antibacterial enzymes whose activity is confirmed both in vitro and in vivo. These comprehensive metagenome analyses reveal not only host bacteria-phage associations in the human intestine but also provide vital information for the development of phage therapies against intestinal pathobionts. more...
- Published
- 2020
21. Chronic dysphagia caused by Laryngo-vertebral Synostosis after anterior fusion for cervical spine trauma: a case report
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Joe Omata, Tomoaki Toyone, Katsunori Inagaki, Ichiro Okano, Yushi Hoshino, and Yuki Usui
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Adult ,Male ,medicine.medical_specialty ,lcsh:Diseases of the musculoskeletal system ,Case Report ,Omohyoid muscle flap ,Omohyoid muscle ,Cricoid Cartilage ,03 medical and health sciences ,0302 clinical medicine ,Postoperative Complications ,Rheumatology ,Cricoid cartilage ,medicine ,otorhinolaryngologic diseases ,Humans ,Orthopedics and Sports Medicine ,Cervical spine trauma ,Esophagus ,030223 otorhinolaryngology ,Spinal cord injury ,030222 orthopedics ,business.industry ,Dysphagia ,Synostosis ,medicine.disease ,Anterior fusion ,Surgery ,Vertebra ,medicine.anatomical_structure ,Spinal Fusion ,Spinal Injuries ,Orthopedic surgery ,Chronic Disease ,Cervical Vertebrae ,lcsh:RC925-935 ,medicine.symptom ,business ,Deglutition Disorders - Abstract
Background Anterior cervical spine surgery is often associated with postoperative dysphagia, but chronic dysphagia caused by laryngo-vertebral synostosis is extremely rare. We report a case of chronic dysphagia caused by synostosis between the cricoid cartilage and cervical spine after anterior surgery for cervical spine trauma. Case presentations We present a case of a 39-year-old man who had sustained complex spine trauma at C5–6 associated with complete spinal cord injury at the age of 22; the patient presented with a 5-year history of chronic dysphagia. Computed tomography demonstrated posterior shift of the esophagus as well as calcification of the cricoid cartilage and its fusion to the right anterior tubercle of the C5 vertebra. A barium swallow study demonstrated significant barium aspiration into the airway and no laryngeal elevation. The patient underwent resection of the bony bridge and omohyoid muscle flap insertion. His symptoms ameliorated after surgery. Conclusion Synostosis between the cricoid cartilage and cervical spine may occur associated with cervical spine trauma and causes chronic dysphagia. Resection of the fused part can improve dysphagia caused by this rare condition and omohyoid muscle flap might be a good option to prevent recurrence. more...
- Published
- 2019
22. Factors inducing falling in schizophrenia patients
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Fumio Hirao, Yoko Tsuji, Yuki Usui, Kohei Mori, Yoshimi Yuri, Hitomi Katsumura, Yoshiteru Akezaki, Yoritaka Fujino, Takuo Nomura, and Tomihiro Hara
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Balance ,medicine.medical_specialty ,Sialorrhea ,business.industry ,Global Assessment of Functioning ,Physical Therapy, Sports Therapy and Rehabilitation ,medicine.disease ,03 medical and health sciences ,0302 clinical medicine ,Schizophrenia ,Physical therapy ,medicine ,Muscle strength ,Original Article ,Falls ,030212 general & internal medicine ,Antipsychotic drug ,business ,Falling (sensation) ,Eyes open ,030217 neurology & neurosurgery ,Balance (ability) - Abstract
[Purpose] The purpose of this study is to investigate the factors causing falling among patients with schizophrenia hospitalized in psychiatric hospitals. [Subjects and Methods] The study subjects were divided into either those having experienced a fall within the past one year (Fall group, 12 patients) and those not having experienced a fall (Non-fall group, 7 patients), and we examined differences between the two groups. Assessment items measured included muscle strength, balance ability, flexibility, body composition assessment, Global Assessment of Functioning scale (GAF), the antipsychotic drug intake, and Drug Induced Extra-Pyramidal Symptoms Scale (DIEPSS). [Results] As a result, significant differences were observed in regard to One leg standing time with eyes open, Time Up and Go Test (TUGT), and DIEPSS Sialorrhea between the Fall group and the Non-fall group. [Conclusion] These results suggest that a decrease in balance ability was significantly correlated with falling in schizophrenia patients. more...
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- 2017
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23. Gradation of proteins and cells attached to the surface of bio-inert zwitterionic polymer brush
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Hiromi Kitano, Kohji Ohno, Lifu Li, Takahiro Kishioka, Tadashi Nakaji-Hirabayashi, and Yuki Usui
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Polymers ,Surface Properties ,Ultraviolet Rays ,Biocompatible Materials ,02 engineering and technology ,010402 general chemistry ,Polymer brush ,Photochemistry ,01 natural sciences ,Fluorescence ,Polymerization ,chemistry.chemical_compound ,Mice ,Adsorption ,Colloid and Surface Chemistry ,Monolayer ,Polymer chemistry ,Cell Adhesion ,Animals ,Physical and Theoretical Chemistry ,Atom-transfer radical-polymerization ,Photoelectron Spectroscopy ,Substrate (chemistry) ,Serum Albumin, Bovine ,General Medicine ,Surfaces and Interfaces ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Betaine ,Monomer ,chemistry ,NIH 3T3 Cells ,Cattle ,0210 nano-technology ,Protein adsorption ,Biotechnology - Abstract
A self-assembled monolayer (SAM) of a 2-bromoisobutyryl end group-carrying initiator for atom transfer radical polymerization (ATRP) was constructed on the surface of silicon wafer or glass substrates via a silane-coupling reaction. When the initiator SAM was irradiated with UV light at 254nm, the surface density of bromine atoms was reduced by the scission of CBr bonds as observed by XPS. With the surface-initiated ATRP of the zwitterionic vinyl monomer, carboxymethyl betaine (CMB), the surface density of PCMB brushes could be easily varied by changing the irradiation period of UV light prior to the polymerization. Furthermore, by using a UV-cut shutter sliding above the initiator SAM-modified substrate at a constant speed, the degree of bromine atom removal could be linearly varied along the direction of movement of the shutter. Consequently, the amount of both proteins adsorbed and cells adhered to the PCMB brush-covered substrate could easily be controlled by the gradation of the surface density of PCMB brushes, which suppressed protein adsorption and cell adhesion. Such a technique is very simple and useful for the regulation of the surface density of adsorbed proteins and adhered cells on an originally bio-inert surface. more...
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- 2016
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24. Proton pump inhibitors enhance intestinal permeability via dysbiosis of gut microbiota under stressed conditions in mice
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Tetsuya Tanigawa, Shuhei Hosomi, Noriko Kamata, Yunosuke Kawaguchi, Koji Otani, Koichi Taira, Yuji Nadatani, Yasuhiro Fujiwara, Fumio Tanaka, Toshio Watanabe, Kosuke Fujimoto, Yasuaki Nagami, Shingo Takashima, Seiya Imoto, Satoshi Uematsu, and Yuki Usui more...
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0301 basic medicine ,プロトンポンプ阻害薬 ,Physiology ,Vasoactive intestinal peptide ,肥満細胞 ,mast cells ,Gut flora ,Pharmacology ,03 medical and health sciences ,0302 clinical medicine ,糞便移植 ,In vivo ,血管作動性腸管ペプチド ,medicine ,psychological stress ,vasoactive intestinal peptide ,Intestinal permeability ,biology ,Ussing chamber ,Endocrine and Autonomic Systems ,Chemistry ,Gastroenterology ,fecal microbiota transplantation ,dysbiosis ,biology.organism_classification ,medicine.disease ,透過性 ,030104 developmental biology ,Paracellular transport ,腸内毒素症 ,030211 gastroenterology & hepatology ,permeability ,proton pump inhibitors ,Dysbiosis ,Ex vivo - Abstract
Background Intestinal permeability and psychological stress are considered the key mechanism(s) in functional dyspepsia (FD). Although proton pump inhibitors (PPIs) are commonly used for the treatment of FD, the effect of PPIs on intestinal permeability has not been elucidated. This study investigated the effect of PPI on intestinal permeability under stressed conditions. Methods C57BL/6J mice were subjected to water avoidance stress (WAS) and administered rabeprazole (40 mg/kg) or vehicle treatment (VT). We then evaluated intestinal permeability both in vivo and ex vivo using plasma fluorescein isothiocyanate-dextran and by assessing the paracellular permeability and transepithelial electrical resistance (TEER) in an Ussing chamber, respectively. Furthermore, we evaluated the effect of PPI-treated fecal microbiota transplant (FMT) on intestinal permeability in vivo. Microbiota profiles of donor feces were assessed by 16S rRNA gene analysis using MiSeq and QIIME2. Key results In the WAS treatment, PPI significantly enhanced intestinal permeability in vivo compared to that in VT. Moreover, PPI significantly increased paracellular permeability and decreased TEER in the duodenum and jejunum, respectively, compared to those in VT under stressed conditions. Moreover, both vasoactive intestinal peptide (VIP) receptor antagonist and ketotifen significantly reversed the effect of PPI on intestinal permeability. Furthermore, PPI-treated FMT significantly increased the intestinal permeability in vivo compared to that in vehicle-treated FMT. Proton pump inhibitors treatment altered the gut microbiota composition, indicating that PPI induced dysbiosis. Conclusions and inferences Under stressed conditions, PPI enhances intestinal permeability via dysbiosis of gut microbiota. Vasoactive intestinal peptide and mast cells are also implicated in the underlying mechanisms. more...
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- 2020
25. Antigen-Specific Mucosal Immunity Regulates Development of Intestinal Bacteria-Mediated Diseases
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Yoshiyuki Gotoh, Ken Ishii, Joon Haeng Rhee, Sheila E. Crowe, Yoshikazu Yuki, Yoshiko Nakano, Peter B. Ernst, Takuya Yamamoto, Masaki Shimohigoshi, Tetsuya Hayashi, Yuki Usui, Satoshi Uematsu, Kosuke Fujimoto, Miho Uematsu, Hiroshi Kiyono, Yukihiro Akeda, Yunosuke Kawaguchi, and Yasumasa Kimura more...
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0301 basic medicine ,Diarrhea ,Male ,Cholera Toxin ,CpG Oligodeoxynucleotide ,medicine.disease_cause ,Severity of Illness Index ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Immune system ,Antigen ,Adjuvants, Immunologic ,Bacterial Proteins ,medicine ,Animals ,Germ-Free Life ,Humans ,Intestinal Mucosa ,Immunity, Mucosal ,Clostridium ramosum ,Hepatology ,biology ,business.industry ,Cholera toxin ,Gastroenterology ,Pneumonia ,biology.organism_classification ,Gastrointestinal Microbiome ,Ovalbumin ,Disease Models, Animal ,030104 developmental biology ,Immunization ,Immunology ,biology.protein ,Dysbiosis ,030211 gastroenterology & hepatology ,Female ,Antibody ,business - Abstract
Background & Aims Dysregulation of the microbiome has been associated with development of complex diseases, such as obesity and diabetes. However, no method has been developed to control disease-associated commensal microbes. We investigated whether immunization with microbial antigens, using CpG oligodeoxynucleotides and/or curdlan as adjuvants, induces systemic antigen-specific IgA and IgG production and affects development of diseases in mice. Methods C57BL/6 mice were given intramuscular injections of antigens (ovalbumin, cholera toxin B-subunit, or pneumococcal surface protein A) combined with CpG oligodeoxynucleotides and/or curdlan. Blood and fecal samples were collected weekly and antigen-specific IgG and IgA titers were measured. Lymph nodes and spleens were collected and analyzed by enzyme-linked immunosorbent assay for antigen-specific splenic T-helper 1 cells, T-helper 17 cells, and memory B cells. Six weeks after primary immunization, mice were given a oral, nasal, or vaginal boost of ovalbumin; intestinal lamina propria, bronchial lavage, and vaginal swab samples were collected and antibodies and cytokines were measured. Some mice were also given oral cholera toxin or intranasal Streptococcus pneumoniae and the severity of diarrhea or pneumonia was analyzed. Gnotobiotic mice were gavaged with fecal material from obese individuals, which had a high abundance of Clostridium ramosum (a commensal microbe associated with obesity and diabetes), and were placed on a high-fat diet 2 weeks after immunization with C ramosum. Intestinal tissues were collected and analyzed by quantitative real-time polymerase chain reaction. Results Serum and fecal samples from mice given injections of antigens in combination with CpG oligodeoxynucleotides and curdlan for 3 weeks contained antigen-specific IgA and IgG, and splenocytes produced interferon-gamma and interleukin 17A. Lamina propria, bronchial, and vaginal samples contained antigen-specific IgA after the ovalbumin boost. This immunization regimen prevented development of diarrhea after injection of cholera toxin, and inhibited lung colonization by S pneumoniae. In gnotobiotic mice colonized with C ramosum and placed on a high-fat diet, the mice that had been immunized with C ramosum became less obese than the nonimmunized mice. Conclusions Injection of mice with microbial antigens and adjuvant induces antigen-specific mucosal and systemic immune responses. Immunization with S pneumoniae antigen prevented lung infection by this bacteria, and immunization with C ramosum reduced obesity in mice colonized with this microbe and placed on a high-fat diet. This immunization approach might be used to protect against microbe-associated disorders of intestine. more...
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- 2019
26. High-aspect-ratio Sub-2-μm Vias Using Thermal Imprint with Build-up Resin
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Tamura Mamoru, Takuya Ohashi, Hiroyuki Kuwae, Yuki Usui, Jun Mizuno, Takahiro Kishioka, Takumi Kamibayashi, and Shuichi Shoji
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010302 applied physics ,Plasma etching ,Fabrication ,Materials science ,Silicon ,chemistry.chemical_element ,Thermosetting polymer ,020206 networking & telecommunications ,02 engineering and technology ,01 natural sciences ,law.invention ,chemistry ,law ,Etching (microfabrication) ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Deep reactive-ion etching ,Photolithography ,Composite material ,Electroplating - Abstract
We developed a fabrication method of high-aspect-ratio fine vias with a build-up resin. The build-up resin composed of a thermosetting resin and silica fillers has low coefficient of thermal expansion and low dielectric constant. Thermal imprint was performed to form the high-aspect-ratio fine via holes on the build-up resin. The imprint mold with high-aspect-ratio fine pillar patterns was fabricated by photolithography and deep reactive ion etching. The residual layer consisted of the thermosetting resin and the silica filler was removed by O 2 /CHF 3 plasma etching. The via of 1.2 µm in diameter with aspect ratio of 5.5, and 5.0 µm in pitch was successfully fabricated followed by Au electroplating. The proposed fabrication method is applicable for high-density 3-dimensional and 2.5-dimensional integration technologies. more...
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- 2018
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27. Effects of Number of Graphite Nodules on Fatigue Limit and Fracture Origins in Heavy Section Spheroidal Graphite Cast Iron
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Yuki Usui, Toshitake Kanno, and Naoto Shiraki
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Materials science ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Fatigue limit ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Mechanics of Materials ,Section (archaeology) ,engineering ,Fracture (geology) ,General Materials Science ,Graphite ,Defect size ,Cast iron ,Composite material ,0210 nano-technology - Published
- 2016
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28. X-ray induced luminescence properties of Ce-doped Ca3Sc2Si3O12 single crystal
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Yuki Usui, Takayuki Yanagida, Go Okada, Noriaki Kawaguchi, and Takumi Kato
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Physics ,Crystal ,Nuclear and High Energy Physics ,Scintillation ,Photoluminescence ,Analytical chemistry ,X-ray ,Irradiation ,Scintillator ,Luminescence ,Instrumentation ,Single crystal - Abstract
Scintillation and photoluminescence (PL) properties of undoped and Ce-doped Ca 3 Sc 2 Si 3 O 12 (CSSG) single crystals were investigated. The crystal samples were synthesized by the floating zone (FZ) method. The Ce-doped CSSG samples showed PL spectrum with a broad feature peaking around 510 nm. From decay constants of the corresponding PL emission, it was confirmed that the origin was due to the 5d-4f transitions of Ce 3 + ions. In addition, the Ce-doped CSSG samples showed scintillation induced by X-rays with a spectrum, peaking around 510 nm as similarly seen in PL. All the samples exhibited a photoabsorption peak in the pulse height spectra measured under 241Am γ -ray irradiation. The absolute scintillation light yield (LY) was the highest for the 0.1% Ce-doped CSSG sample, and the value was 3,300 ph/MeV. more...
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- 2020
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29. Safe Clinical Use of Carbon Nanotubes as Innovative Biomaterials
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Naoyuki Nishimura, Masanori Okamoto, Morinobu Endo, Seiji Takanashi, Shinsuke Kobayashi, Yuki Usui, Kaoru Aoki, Masayuki Shimizu, Hiroki Nomura, Kazuo Hara, Nobuyo Narita, Seiichi Taruta, Hisao Haniu, Naoto Saito, and Hiroyuki Kato more...
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Battery (electricity) ,Nanotubes, Carbon ,Graphene ,Chemistry ,Photovoltaic system ,New energy ,Biocompatible Materials ,Nanotechnology ,Review ,General Chemistry ,Carbon nanotube ,Nanomaterials ,law.invention ,Electricity generation ,law ,Toxicity Tests ,Animals ,Humans ,Electric power ,Safety - Abstract
Carbon nanotubes (CNTs) are structurally described as sheets of six-membered carbon atom rings (i.e., graphene) rolled up into cylinders. CNTs with only one layer are known as single-walled CNTs (SWCNTs), and those with two or more layers are known as multiwalled CNTs (MWCNTs). Cup-stacked carbon nanotubes and carbon nanohorns are also sometimes called CNTs.1−3 Currently, these very attractive carbon materials and nanomaterials are a subject of vigorous product development in a broad range of fields.4−11 The reasons are that CNTs have useful electrical, thermal, and mechanical characteristics, and their base material performance can be improved by combination with other materials.12−23 A recent industrial application of CNTs as an electrode additive to lithium-ion batteries is based on their excellent electrical characteristics. Addition of CNTs prevents battery deterioration and substantially lengthens time to recharging. It is doubtless that the demand for high-performance batteries will grow increasingly with multifunctionalization of personal computers and mobile phones, development of new mobile terminals, spread of electric vehicles, and other factors.24−30 Composite materials with the excellent mechanical characteristics of CNTs have already been used in sporting goods such as golf clubs, tennis rackets, and bicycles. CNTs are also expected to have applications that reduce the weight of aircraft and automobiles.10,14,31−35 A wide variety of advantages are gained from the use CNTs in precision parts as well. CNTs are also used in transistors and memory devices, and enhance their efficiency. The use of CNTs in various displays and TV screens continues to increase in rate. CNTs are also widely used in products designed to prevent static electricity, to shield electromagnetic waves, to store electricity, and for other purposes.36−45 Furthermore, Japan is now facing nuclear energy issues stemming from the accident at Tokyo Electric Power Company’s Fukushima No. 1 nuclear power plant. As a result, CNTs are expected to play a major role in developing new energy sources such as solar photovoltaic power generation and wind power generation.46−52 In the medical field, extensive research activities are underway to develop new CNTs biomaterials for use in the treatment and diagnosis of disease. For example, application of CNTs to cancer treatment and diagnosis, such as in drug delivery systems (DDSs) for treatment of cancer, hyperthermia, and in vivo imaging, has been investigated.53−57 In a study that aimed at applying CNTs to regenerative medicine, CNTs were found to work excellently as scaffold materials for nerve and bone tissue regeneration.58−63 Furthermore, R&D activities are underway to improve the mechanical strength and durability of implants by combining CNTs with existing biomaterials.64−67 Besides, numerous ideas have been put forth about how CNTs can be used in the treatment of a variety of diseases. Figure Figure11 shows the trend in the number of articles found in the PubMed database (http://www.ncbi.nlm.nih.gov/pubmed/) (accessed 20 March 2014) by searches using “carbon nanotubes” and “biomaterials” as keywords. The number has been soaring since 2005, suggesting that CNTs research has become a highly competitive field worldwide over the past few years. Of course, numerous articles on the biological applications of CNTs do exist that cannot be captured with these two simple keywords, and the graphic representation of this trend is no more than an indicator of the increase in this research over time. Figure 1 Time trends for the number of articles found in the PubMed database (http://www.ncbi.nlm.nih.gov/pubmed/) (accessed 20 March 2014) by search using “carbon nanotubes” and “biomaterials” as keywords. Recent years have seen ... more...
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- 2014
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30. Neuroprotective effects of propofol on ER stress-mediated apoptosis in neuroblastoma SH-SY5Y cells
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Manami Inagaki, Mayumi Tsuji, Ai Nakajima, Yuki Usui, Akifumi Niiya, Yurie Tamura, Masumi Kato, and Katsuji Oguchi
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Thapsigargin ,SH-SY5Y ,Eukaryotic Initiation Factor-2 ,Intracellular Space ,Apoptosis ,Pharmacology ,Neuroprotection ,Neuroblastoma ,chemistry.chemical_compound ,Cell Line, Tumor ,Humans ,Medicine ,Phosphorylation ,Propofol ,biology ,Calpain ,business.industry ,Endoplasmic reticulum ,Endoplasmic Reticulum Stress ,medicine.disease ,Caspases, Initiator ,Neuroprotective Agents ,Gene Expression Regulation ,chemistry ,Unfolded protein response ,biology.protein ,Calcium ,business ,Reperfusion injury - Abstract
Anesthetic treatment has been associated with widespread apoptotic neurodegeneration in the neonatal rodent brain. It has recently been suggested that propofol, a short-acting intravenous anesthetic agent, may have a potential as a neuroprotective agent. An apoptotic pathway mediated through endoplasmic reticulum (ER) stress has been attracting attention. ER stress is associated with accumulation of unfolded or misfolded proteins in ER, and ER stress-induced apoptosis is implicated in a wide range of diseases, including ischemia/reperfusion injury, neurodegeneration, and diabetes. We investigated whether thapsigargin-induced ER stress is prevented by propofol in human neuroblastoma SH-SY5Y cells. SH-SY5Y cells were pretreated with various concentrations of propofol (1-10 μM) for 3h before co-treatment with 0.5 μM thapsigargin and propofol for 20 h. Levels of ssDNA, specific evidence of apoptosis, and biomarkers of ER stress (mRNA expression of Chop and sXbp-1) were determined. We also assayed calpain and caspase-4 activities and intracellular Ca(2+) ([Ca(2+)]i) levels. Thapsigargin-induced increases in ssDNA levels, expressions of ER stress biomarkers, activities of caspase-4 and calpain, and level of [Ca(2+)]i were suppressed by co-incubation with propofol. Our data indicate the possibility that propofol inhibits the Ca(2+) release from ER at clinically employed dose levels. These results demonstrate that propofol suppresses the ER stress-induced apoptosis in this cell system, and may have the neuroprotective potency. It may also be a promising agent for preventing damage from cerebral ischemia or edema. more...
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- 2014
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31. Influence of CNF content on microstructure and fracture toughness of CNF/alumina composites
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Tomohiko Yamakami, Kaoru Aoki, Tomohiro Yamaguchi, Naoki Ueda, Yuki Usui, Naoto Saito, Morinobu Endo, and Seiichi Taruta
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Materials science ,Carbon nanofiber ,Alumina ,Composite number ,Composite ,General Chemistry ,Fracture toughness ,Condensed Matter Physics ,Microstructure ,Carbon nanofibers ,Materials Chemistry ,Ceramics and Composites ,Composite material - Abstract
Dense 0.4–5.0 wt % carbon nanofiber (CNF)/alumina composites were fabricated by plasma activated sintering. The microstructure—particularly the CNFs distribution—of composites containing different amounts of CNFs was observed in detail, and the influence of the additive amounts of CNF on the microstructure and the fracture toughness of the composites were investigated. The ratio of CNFs distributed individually in the composites decreased with an increase in the addition of CNFs, and the other CNFs formed bundles; notably three-quarters of the CNFs formed bundles in the 5.0 wt % CNF/alumina composite. The alumina grain size distribution of the composites became narrower to smaller grain size side and the average alumina grain size of the composites decreased with an increase in the addition of CNFs from 0.4 to 1.6 wt %. However, the average alumina grain size of the composites did not vary greatly with an increase in the addition of CNFs from 1.6 to 5.0 wt %, because the CNF bundles formed in the 2.5 and 5.0 wt % CNF/alumina composites lowered the grain growth retardation effect of the CNFs. The 1.6 wt % CNF/alumina composite exhibited the highest fracture toughness, because three-fifths of the CNFs distributed individually and uniformly in alumina grain boundaries., Article, J. Ceram. Soc. Jpn. 122(1424):292-299(2014) more...
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- 2014
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32. Highly purified, multi-wall carbon nanotubes induce light-chain 3B expression in human lung cells
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Tamotsu Tsukahara, Yoshikazu Matsuda, Yuki Usui, and Hisao Haniu
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Autophagosome ,Programmed cell death ,DNA damage ,medicine.medical_treatment ,Biophysics ,Inflammation ,Biochemistry ,Carbon nanotube ,Cell Line ,Carbon Fiber ,Bronchial epithelial cells ,medicine ,Autophagy ,Humans ,LC3B ,Molecular Biology ,Lung ,Chemistry ,Cell growth ,Nanotubes, Carbon ,Cell Biology ,Carbon ,Cell biology ,Cytokine ,Apoptosis ,medicine.symptom ,Microtubule-Associated Proteins - Abstract
Bronchial epithelial cells are targets of inhalation and play a critical role in the maintenance of mucosal integrity as mechanical barriers against various particles. Our previous result suggest that vapor-grown carbon fiber, HTT2800, which is one of the most highly purified multi-wall carbon nanotubes (MWCNT) showed cellular uptake of the carbon nanotube, increased cell death, enhanced DNA damage, and induced cytokine release. Increasing evidence suggests that autophagy may critically influence vital cellular processes such as apoptosis, cell proliferation and inflammation and thereby may play a critical role in pulmonary diseases. Autophagy was recently recognized as a critical cell death pathway, and autophagosome accumulation has been found to be associated with the exposure of various nanoparticles. In this study, the authors focus on the autophagic responses of HTT2800 exposure. The HTT2800-exposed cells induced LC3B expression and induced cell growth inhibition., Article, BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS.440(2):348-353(2013) more...
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- 2013
33. Culture medium type affects endocytosis of multi-walled carbon nanotubes in BEAS-2B cells and subsequent biological response
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Shinsuke Kobayashi, Kaoru Aoki, Yoshikazu Matsuda, Yuki Usui, Hiroyuki Kato, Hisao Haniu, Seiji Takanashi, Masanori Okamoto, Naoto Saito, Kayo Maruyama, Tamotsu Tsukahara, Masayuki Shimizu, and Hiroki Nomura more...
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Serum ,Cell Survival ,Cytotoxicity ,Cell Culture Techniques ,Bronchi ,Endocytosis ,Toxicology ,Flow cytometry ,Cell Line ,chemistry.chemical_compound ,BEAS-2B cells ,Fluorescence microscope ,medicine ,Humans ,Cells, Cultured ,Growth medium ,medicine.diagnostic_test ,Chemistry ,Nanotubes, Carbon ,Epithelial Cells ,General Medicine ,Molecular biology ,Multi-walled carbon nanotube ,Culture Media ,Biochemistry ,Differential interference contrast microscopy ,Cytoplasm ,Normal human bronchial epithelial cells ,Cytokines ,Cytokine secretion - Abstract
We examined the cytotoxicity of multi-walled carbon nanotubes (MWCNTs) and the resulting cytokine secretion in BEAS-2B cells or normal human bronchial epithelial cells (HBEpCs) in two types of culture media (Ham’s F12 containing 10% FBS [Ham’s F12] and serum-free growth medium [SFGM]). Cellular uptake of MWCNT was observed by fluorescent microscopy and analyzed using flow cytometry. Moreover, we evaluated whether MWCNT uptake was suppressed by 2 types of endocytosis inhibitors. We found that BEAS-2B cells cultured in Ham’s F12 and HBEpCs cultured in SFGM showed similar biological responses, but BEAS-2B cells cultured in SFGM did not internalize MWCNTs, and the 50% inhibitory concentration value, i.e., the cytotoxicity, was increased by more than 10-fold. MWCNT uptake was suppressed by a clathrin-mediated endocytosis inhibitor and a caveolae-mediated endocytosis inhibitor in BEAS-2B cells cultured in Ham’s F12 and HBEpCs cultured in SFGM. In conclusion, we suggest that BEAS-2B cells cultured in a medium containing serum should be used for the safety evaluation of nanomaterials as a model of normal human bronchial epithelial cells. However, the culture medium composition may affect the proteins that are expressed on the cytoplasmic membrane, which may influence the biological response to MWCNTs., Article, Toxicology in Vitro. 27(6):1679-1685 (2013) more...
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- 2013
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34. Novel gap filling BARC with high chemical resistance
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Tamura Mamoru, Ogata Hiroto, Yuki Usui, Yasushi Sakaida, Hashimoto Yuto, Tomoya Ohashi, and Takahiro Kishioka
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Chemical resistance ,Materials science ,business.industry ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Planarity testing ,010309 optics ,Outgassing ,chemistry ,Etching (microfabrication) ,0103 physical sciences ,Optoelectronics ,Adhesive ,0210 nano-technology ,business ,Tin ,Lithography ,Shrinkage - Abstract
In the recent of the semiconductor manufacturing process, variety of properties (narrow gap-filling and planarity etc.) are required to organic BARC in addition to the conventional requirements. Moreover, SC-1 resistance is also needed because BARC is often used as a wet etching mask when TiN processing. But conventional BARC which include crosslinker doesn’t have enough SC-1 resistance, and we found that it is also difficult to obtain good gap-filling and good planarity because of outgassing and film shrinkage derived from the crosslinker. In this study, we have developed the new self-crosslinking BARC. The new crosslinking system shows low outgassing and film shrinkage because of not including crosslinker. So, novel BARC has better gap filling property and planarity and over 3 times higher SC-1 resistance than that of conventional BARC. Moreover, by adding the low molecular weight additive which has high adhesive unit to TiN surface, the novel BARC has over 10 times higher SC-1 resistance than that of conventional BARC. And this novel BARC can be applied both ArF and KrF lithography process because of broad absorbance, high etching rate, chemical resistance (SC-1, SC-2, DHF, and others) and good film thickness uniformity. In this paper, we will discuss the detail of new self-crosslinking BARC in excellent total performance and our approach to achieve high chemical resistance. more...
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- 2017
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35. A three-dimensional block structure consisting exclusively of carbon nanotubes serving as bone regeneration scaffold and as bone defect filler
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Shinsuke Kobayashi, Masanori Okamoto, Kaoru Aoki, Manabu Tanaka, Yuki Usui, Takashi Takizawa, Hiroki Nomura, Hiroyuki Kato, Ayumu Oishi, Seiji Takanashi, Yoshinori Sato, Hisao Haniu, and Naoto Saito
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Male ,Scaffold ,Bone Regeneration ,Bone density ,Compressive Strength ,Organogenesis ,lcsh:Medicine ,Bone Morphogenetic Protein 2 ,02 engineering and technology ,01 natural sciences ,Biochemistry ,Diagnostic Radiology ,Mice ,Tissue engineering ,Bone Density ,Osteogenesis ,Neurobiology of Disease and Regeneration ,Medicine and Health Sciences ,Group-Specific Staining ,Nanotechnology ,lcsh:Science ,Tomography ,Staining ,Multidisciplinary ,Tissue Scaffolds ,Radiology and Imaging ,Serum Albumin, Bovine ,021001 nanoscience & nanotechnology ,Bone Imaging ,Recombinant Proteins ,medicine.anatomical_structure ,Neurology ,Connective Tissue ,Engineering and Technology ,Carbon Nanotubes ,Anatomy ,0210 nano-technology ,Porosity ,Research Article ,Materials science ,Imaging Techniques ,Neuroimaging ,Bone healing ,Choristoma ,010402 general chemistry ,Research and Analysis Methods ,Bone morphogenetic protein 2 ,Bone and Bones ,Diagnostic Medicine ,medicine ,Animals ,Humans ,Rats, Wistar ,Bone regeneration ,Bone ,Muscle, Skeletal ,Bone Development ,Osteoblasts ,Tissue Engineering ,Nanotubes, Carbon ,lcsh:R ,Hematoxylin Staining ,Biology and Life Sciences ,Proteins ,Bone fracture ,medicine.disease ,0104 chemical sciences ,Computed Axial Tomography ,Rats ,Biological Tissue ,Specimen Preparation and Treatment ,lcsh:Q ,Cortical bone ,Collagens ,Organism Development ,Biomedical engineering ,Developmental Biology ,Neuroscience - Abstract
Many recent studies have been conducted to assess the ability of composite materials containing carbon nanotubes (CNTs) with high bone affinity to serve as scaffolds in bone regenerative medicine. These studies have demonstrated that CNTs can effectively induce bone formation. However, no studies have investigated the usefulness of scaffolds consisting exclusively of CNTs in bone regenerative medicine. We built a three-dimensional block entity with maximized mechanical strength from multi-walled CNTs (MWCNT blocks) and evaluated their efficacy as scaffold material for bone repair. When MWCNT blocks containing recombinant human bone morphogenetic protein-2 (rhBMP-2) were implanted in mouse muscle, ectopic bone was formed in direct contact with the blocks. Their bone marrow densities were comparable to those of PET-reinforced collagen sheets with rhBMP-2. On day 1 and day 3, MC3T3-E1 preosteoblasts were attached to the scaffold surface of MWCNT blocks than that of PET-reinforced collagen sheets. They also showed a maximum compression strength comparable to that of cortical bone. Our MWCNT blocks are expected to serve as bone defect filler and scaffold material for bone regeneration., Article, PLOS ONE.12(2):e0172601(2017) more...
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- 2017
36. Helium ion microscopy (HIM) for imaging fine line features patterned organic film with less damage
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Tomoya Ohashi, Shigeki Oyama, Shinichi Ogawa, and Yuki Usui
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010302 applied physics ,Materials science ,Scanning electron microscope ,Physics::Medical Physics ,Analytical chemistry ,chemistry.chemical_element ,Electron ,Penetration (firestop) ,01 natural sciences ,Physics::Geophysics ,Ion ,Organic film ,Condensed Matter::Materials Science ,chemistry ,Condensed Matter::Superconductivity ,0103 physical sciences ,Irradiation ,Composite material ,Ion microscopy ,Helium - Abstract
Helium ion microscopy (HIM) was applied to image an organic film filled into narrow trenches. The film was characterized to examine structural changes after the HIM helium ion irradiation comparing with a SEM electron beam irradiation. In the HIM case, the change was seen in a deep region of the film, while it occurred at the surface in the SEM case. This depends on penetration properties of helium ions and electrons to the material, and surface imaging of the film looks more realistic by the HIM than the SEM. more...
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- 2017
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37. Microstructure development and fracture toughness of acid-treated carbon nanofibers/alumina composites
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Morinobu Endo, Yuki Usui, Kaoru Aoki, Naoki Ueda, Tomohiro Yamaguchi, Tomohiko Yamakami, Kunio Kitajima, Seiichi Taruta, and Naoto Saito
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Materials science ,Carbon nanofiber ,Composite number ,Alumina ,technology, industry, and agriculture ,Composite ,General Chemistry ,Fracture toughness ,Condensed Matter Physics ,Microstructure ,equipment and supplies ,Carbon nanofibers ,Materials Chemistry ,Ceramics and Composites ,Composite material ,Microstructure development - Abstract
In this study, carbon nanofibers (CNFs) having different amounts of defect were prepared by acid-treating for 0.5, 1 and 5 h and were combined with alumina. Then, the influence of the amount of defect on the CNFs on microstructure development of the CNFs/alumina composites and relationship between the fracture toughness and the average alumina grain size was investigated. The intensity ratio of D-band to G-band (D/G) in Raman spectra of the CNFs increased from 0.34 for pristine CNFs to 0.95 for the CNFs acid-treated for 5 h with the acid-treatment time, which indicates that the amount of defect on the CNFs increased with the acid-treatment time. The alumina grain growth in the dense composites sintered at 1200-1300 degrees C was not influenced by the amount of defect on the CNFs, however, the composite containing CNFs having the moderate amount of defect (D/G = 0.56) showed the slowest alumina grain growth rate at 1350-1450 degrees C. The fracture toughness of the composites containing the CNFs acid-treated for 0.5 h increased with a decrease in average alumina grain size and reached 5.6 MPa.m(0.5) at the average alumina grain size of 0.84 mu m, which was 60% higher value compared to monolithic alumina (3.5 MPa.m(0.5)). However, fracture toughness of the composites containing CNFs acid-treated for 1 and 5 h increased with a decrease in average alumina grain size, showed the maximum values of 5.0 and 4.5 MPa.m(0.5) at average alumina grain sizes of 1.3 and 1.6 mu m, respectively, and decreased as the average alumina grain size decreased further. The maximum fracture toughness of the composite containing the CNFs acid-treated for 5 h was lower than that of the composite containing the CNFs acid-treated for 1 h. (C)2012 The Ceramic Society of Japan All rights reserved., Article, JOURNAL OF THE CERAMIC SOCIETY OF JAPAN. 120(1408):560-568 (2012) more...
- Published
- 2012
38. Biocompatibility and bone tissue compatibility of alumina ceramics reinforced with carbon nanotubes
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Nobuhide Ogihara, Kaoru Aoki, Masayuki Shimizu, Hiroyuki Kato, Seiji Takanashi, Nobuyo Narita, Yuki Usui, Seiichi Taruta, Kazuo Hara, Masanori Okamoto, Koichi Nakamura, Naoko Ogiwara, Norio Ishigaki, Noboru Nakayama, Hisao Haniu, and Naoto Saito more...
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Male ,Ceramics ,Materials science ,Biocompatibility ,composite ,safety ,Composite number ,Biomedical Engineering ,Medicine (miscellaneous) ,bone tissue ,Bioengineering ,Carbon nanotube ,Development ,Bone tissue ,law.invention ,Cell Line ,Mice ,biocompatibility ,law ,Materials Testing ,medicine ,Aluminum Oxide ,Cell Adhesion ,Animals ,Humans ,General Materials Science ,Femur ,Composite material ,carbon nanotube ,Cells, Cultured ,Osteoblasts ,Nanotubes, Carbon ,technology, industry, and agriculture ,Gene Expression Regulation, Developmental ,cell attachment ,Prostheses and Implants ,equipment and supplies ,Alumina composite ,Alkaline Phosphatase ,medicine.anatomical_structure ,Alumina ceramic ,Compatibility (mechanics) ,Bone Substitutes ,alumina ceramic ,Subcutaneous implantation ,Calcium ,Rabbits - Abstract
信州大学博士(医学)・学位論文・平成23年3月31日授与(甲第906号)・荻原伸英, The addition of carbon nanotubes (CNTs) remarkably improves the mechanical characteristics of base materials. CNT/alumina ceramic composites are expected to be highly functional biomaterials useful in a variety of medical fields. Biocompatibility and bone tissue compatibility were studied for the application of CNT/alumina composites as biomaterials. Methods & results: Inflammation reactions in response to the composite were as mild as those of alumina ceramic alone in a subcutaneous implantation study. In bone implantation testing, the composite showed good bone tissue compatibility and connected directly to new bone. An in vitro cell attachment test was performed for osteoblasts, chondrocytes, fibroblasts and smooth muscle cells, and CNT/alumina composite showed cell attachment similar to that of alumina ceramic. Discussion & conclusion: Owing to proven good biocompatibility and bone tissue compatibility, the application of CNT/alumina composites as biomaterials that contact bone, such as prostheses in arthroplasty and devices for bone repair, are expected., Article, NANOMEDICINE. 7(7):981-993 (2012) more...
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- 2012
39. Elucidation mechanism of different biological responses to multi-walled carbon nanotubes using four cell lines
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Nobuhide Ogihara, Seiji Takanashi, Yoong Ahm Kim, Yuki Usui, Tamotsu Tsukahara, Yoshikazu Matsuda, Kaoru Aoki, Koichi Nakamura, Masanori Okamoto, Hiroyuki Kato, Hisao Haniu, Naoto Saito, Masayuki Shimizu, Ki Chul Park, Kazuo Hara, and Norio Ishigaki more...
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Cell type ,Materials science ,cytokine secretion ,Membrane permeability ,Cell Survival ,Biophysics ,Pharmaceutical Science ,Bioengineering ,Carbon nanotube ,Endocytosis ,law.invention ,Biomaterials ,International Journal of Nanomedicine ,law ,Cell Line, Tumor ,Drug Discovery ,Humans ,endocytosis ,Cytotoxicity ,Original Research ,Cell Line, Transformed ,chemistry.chemical_classification ,reactive oxygen species ,Reactive oxygen species ,Nanotubes, Carbon ,Organic Chemistry ,ulti-walled carbon nanotubes ,multi-walled carbon nanotubes ,General Medicine ,Cell biology ,chemistry ,Cell culture ,Cytokines ,cytotoxicity ,Cytokine secretion - Abstract
We examined differences in cellular responses to multi-walled carbon nanotubes (MWCNTs) using malignant pleural mesothelioma cells (MESO-1), bronchial epithelial cells (BEAS-2B), neuroblastoma cells (IMR-32), and monoblastic cells (THP-1), before and after differentiation. MESO-1, BEAS-2B and differentiated THP-1 cells actively endocytosed MWCNTs, resulting in cytotoxicity with lysosomal injury. However, cytotoxicity did not occur in IMR-32 or undifferentiated THP-1 cells. Both differentiated and undifferentiated THP-1 cells exhibited an inflammatory response. Carbon blacks were endocytosed by the same cell types without lysosomal damage and caused cytokine secretion, but they did not cause cytotoxicity. These results indicate that the cytotoxicity of MWCNTs requires not only cellular uptake but also lysosomal injury. Furthermore, it seems that membrane permeability or cytokine secretion without cytotoxicity results from several active mechanisms. Clarification of the cellular recognition mechanism for MWCNTs is important for developing safer MWCNTs., Article, International Journal of Nanomedicine. 6(1):3487-3497 (2011) more...
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- 2011
40. Toxicoproteomic evaluation of carbon nanomaterials in vitro
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Kazuo Hara, Norio Ishigaki, Yuki Usui, Masayuki Shimizu, Nobuhide Ogihara, Hiroyuki Kato, Kaoru Aoki, Seiji Takanashi, Koichi Nakamura, Hisao Haniu, Masanori Okamoto, Yoshikazu Matsuda, and Naoto Saito more...
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Proteomics ,Toxicoproteomics ,Time Factors ,Proteomics methods ,Nanotubes, Carbon ,Computer science ,Carbon nanotubes ,Drug Evaluation, Preclinical ,Biophysics ,in vitro ,Asbestos ,Nanotechnology ,Carbon nanotube ,Biochemistry ,Nanomaterials ,law.invention ,Chronic toxicity ,law ,Carcinogens ,Animals ,Humans ,Particle Size ,Medical science ,Carbon nanomaterials - Abstract
Carbon nanotubes (CNTs) have already been successfully implemented in various fields, and they are anticipated to have innovative applications in medical science. However, CNTs have asbestos-like properties, such as their nanoscale size and high aspect ratio (> 100). Moreover, CNTs may persist in the body for a long time. These properties are thought to cause malignant mesothelioma and lung cancer. However, based on conventional toxicity assessment systems, the carcinogenicity of asbestos and CNTs is unclear. The reason for late countermeasures against asbestos is that reliable, long-term safety assessments have not yet been developed by toxicologists. Therefore, a new type of long-term safety assessment, different from the existing methods, is needed for carbon nanomaterials. Recently, we applied a proteomic approach to the safety assessment of carbon nanomaterials. In this review, we discuss the basic concept of our approach, the results, the problems, and the possibility of a long-term safety assessment for carbon nanomaterials using the toxicoproteomic approach., Article, Journal of Proteomics. 74(12):2703-2712 (2011) more...
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- 2011
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41. Evaluation of CNT toxicity by comparison to tattoo ink
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Kazuo Hara, Masayuki Shimizu, Hiroyuki Kato, Yoong Ahm Kim, Nobuyo Narita, Yuki Usui, Kenji Sano, Naoyuki Nishimura, Nobuhide Ogihara, Kaoru Aoki, Seiichi Taruta, Koichi Nakamura, Norio Ishigaki, Hisao Haniu, and Naoto Saito more...
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Materials science ,Materials Science(all) ,Mechanics of Materials ,law ,Mechanical Engineering ,General Materials Science ,Nanotechnology ,Carbon nanotube ,Carbon black ,History of use ,Condensed Matter Physics ,Tattoo ink ,law.invention - Abstract
Article, Materials Today. 14(9): 434-440 (2011)
- Published
- 2011
42. Scintillation Properties of (Lu,Y)AlO3 Doped with Nd
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Daisuke Nakauchi, Go Okada, Yuki Usui, Masaki Akatsuka, Takayuki Yanagida, and Noriaki Kawaguchi
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010302 applied physics ,Scintillation ,Materials science ,0103 physical sciences ,Doping ,Analytical chemistry ,General Materials Science ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,Instrumentation - Published
- 2018
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43. Fabrication and mechanical properties of high-dispersion-treated carbon nanofiber/alumina composites
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Tomohiko Yamakami, Seiichi Taruta, Kaoru Aoki, Naoki Ueda, Kunio Kitajima, Takefumi Nakanishi, Fumiaki Miyaji, Morinobu Endo, Naoto Saito, Tomohiro Yamaguchi, and Yuki Usui
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Materials science ,Fabrication ,Carbon nanofiber ,Alumina ,Sintering ,Mechanical properties ,General Chemistry ,Carbon nanotube ,Condensed Matter Physics ,law.invention ,Fracture toughness ,Flexural strength ,law ,Hot isostatic pressing ,Materials Chemistry ,Ceramics and Composites ,Relative density ,Microstructure development ,Composite material ,Composites - Abstract
High-dispersion-treated carbon nanofibers (CNFs) were used to fabricate uniformly-dispersed CNFs-alumina composites with enhanced mechanical properties. The treatment was effective in obtaining dense and uniform composites. The composites containing 0.4-0.8 wt CNFs were densified to a relative density of more than 99% by vacuum sintering and subsequent hot isostatic pressing, and those containing 1.6-2.5 wt % CNFs were densified to full density by plasma activated sintering. The maximum bending strength of the composites (1050 MPa) was approximately the same as the bending strength of monolithic alumina (1079 MPa). The maximum fracture toughness of the composites was 5.9 MPa.m(0.5), which was a 69% increase compared with the fracture toughness of monolithic alumina (3.5 MPa.m(0.5)). Fracture toughness (Kid increased rapidly with a decrease in alumina grain size (G), and we found that the relationship could be expressed by the following equation: K-IC = (k(1)/G(2)) k(2) (where k(1), and k(2) are constants)., Article, Journal of the Ceramic Society of Japan. 118(1381):847-854 (2010) more...
- Published
- 2010
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44. Carbon Nanotubes with High Bone-Tissue Compatibility and Bone-Formation Acceleration Effects
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Yuki Usui, Koichi Nakamura, Hiroshi Horiuchi, Yoong Ahm Kim, Nobuyo Narita, Narumichi Murakami, Hiroyuki Kato, Kaoru Aoki, Seiichi Taruta, Hiroshi Yamazaki, Naoto Saito, Morinobu Endo, Norio Ishigaki, and Isao Nakamura more...
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Male ,Scaffold ,Bone Regeneration ,Materials science ,Surface Properties ,Bone Morphogenetic Protein 2 ,Biocompatible Materials ,Nanotechnology ,Bone healing ,Bone morphogenetic protein ,Bone tissue ,Bone morphogenetic protein 2 ,Osseointegration ,Biomaterials ,Mice ,X-Ray Diffraction ,Osteogenesis ,Transforming Growth Factor beta ,Materials Testing ,Fracture fixation ,medicine ,Animals ,Humans ,General Materials Science ,Bone regeneration ,Nanotubes, Carbon ,Prostheses and Implants ,General Chemistry ,Recombinant Proteins ,Durapatite ,medicine.anatomical_structure ,Bone Morphogenetic Proteins ,Microscopy, Electron, Scanning ,Graphite ,Biotechnology - Abstract
Carbon nanotubes (CNTs) have been used in various fields as composites with other substances or alone to develop highly functional materials. CNTs hold great interest with respect to biomaterials, particularly those to be positioned in contact with bone such as prostheses for arthroplasty, plates or screws for fracture fixation, drug delivery systems, and scaffolding for bone regeneration. Accordingly, bone-tissue compatibility of CNTs and CNT influence on bone formation are important issues, but the effects of CNTs on bone have not been delineated. Here, it is found that multi-walled CNTs adjoining bone induce little local inflammatory reaction, show high bone-tissue compatibility, permit bone repair, become integrated into new bone, and accelerate bone formation stimulated by recombinant human bone morphogenetic protein-2 (rhBMP-2). This study provides an initial investigational basis for CNTs in biomaterials that are used adjacent to bone, including uses to promote bone regeneration. These findings should encourage development of clinical treatment modalities involving CNTs. more...
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- 2008
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45. Specific biological responses of the synovial membrane to carbon nanotubes
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Hiroyuki Kato, Ayumu Oishi, Yuki Usui, Hiroki Nomura, Shinsuke Kobayashi, Kaoru Aoki, Hisao Haniu, Takashi Takizawa, Naoto Saito, Seiji Takanashi, Masanori Okamoto, and Manabu Tanaka
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Male ,medicine.medical_specialty ,Inflammation ,Carbon nanotube ,Article ,law.invention ,Cell Line ,Mice ,law ,medicine ,Animals ,Humans ,Bone regeneration ,Cytotoxicity ,Multidisciplinary ,Chemistry ,Nanotubes, Carbon ,Macrophages ,Synovial Membrane ,Granulation tissue ,Fibroblasts ,Surgery ,Rats ,Membrane ,medicine.anatomical_structure ,Drug delivery ,Biophysics ,Cytokines ,Synovial membrane ,medicine.symptom - Abstract
Biological evaluation of carbon nanotubes (CNTs) is typically performed in the lung or abdominal cavity; however, biological reactions to CNTs are predicted to be markedly different in other tissues. In applications of CNTs as reinforcement for artificial joints and drug delivery systems, including their use in bone regeneration, the intra-articular synovial membrane makes contact with the CNTs. Herein, we analyzed the reaction of the synovial membrane with multiwalled CNTs (MWCNTs). Injection of MWCNTs into rat knee joints revealed their dose-dependent incorporation into deep synovial membranes and the formation of granulation tissue, without long-term inflammation. MWCNTs were incorporated into human fibroblast-like synoviocytes (HFLSs), with less cytotoxicity than that observed in macrophages (RAW264 cells). Moreover, MWCNTs inhibited the release of cytokines and chemokines from HFLSs. The reaction of the synovial membrane with MWCNTs differed from that observed in other tissues; thus, detailed biological evaluation at each target site is necessary for clinical applications. more...
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- 2015
46. Scintillation and optical properties of TiO2–ZnO–Al2O3–B2O3 glasses and glass-ceramics
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Noriaki Kawaguchi, Takayuki Yanagida, Go Okada, Yuki Usui, and Hirokazu Masai
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010302 applied physics ,Aluminium oxides ,Scintillation ,Amorphous metal ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Transition temperature ,General Engineering ,General Physics and Astronomy ,Phosphor ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Particle detector ,visual_art ,0103 physical sciences ,X-ray crystallography ,visual_art.visual_art_medium ,Optoelectronics ,Ceramic ,0210 nano-technology ,business - Published
- 2018
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47. Synthesis and growth mechanism of GeO2 particles in AOT reversed micelles
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Takeshi Kawai, Kijiro Kon-No, and Yuki Usui
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Hydrolysis ,Colloid and Surface Chemistry ,chemistry ,Solubilization ,Excess water ,Sodium ,Analytical chemistry ,chemistry.chemical_element ,Organic chemistry ,Microemulsion ,Germanium ,Micelle ,Water content - Abstract
GeO 2 particles with a narrow size distribution were synthesized using hydrolyzing germanium tetraethoxide (GTE) in a 2,2,4-trimethylpentane solution of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as a function of water content ( R w =[H 2 O]/[AOT]). Their shape was observed to be polyhedral in the absence of excess water, whereas it was cubic in the presence of bulk-like water. The size and shape varied with R w such that the solubilized state of water in effect determined the growth process. In addition, by examining the time-dependent growth of GeO 2 particles in a W/O microemulsion ( R w =20), we clarified that water condensation of hydrolyzed GTE is the rate-limiting step in particle growth. more...
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- 1999
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48. Correction: Corrigendum: Carcinogenicity evaluation for the application of carbon nanotubes as biomaterials in rasH2 mice
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Hisao Haniu, Kenji Sano, Naoto Saito, Masayuki Shimizu, Naoyuki Nishimura, Koichi Nakamura, Kazuo Hara, Masanori Okamoto, Norio Ishigaki, Kazuhiko Machida, Nobuhide Ogihara, Hideki Tsutsumi, Seiji Takanashi, Yuki Usui, Hiroyuki Kato, Shinsuke Kobayashi, and Kaoru Aoki more...
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Multidisciplinary ,law ,business.industry ,Medicine ,Nanotechnology ,Carbon nanotube ,business ,Corrigenda ,Carcinogen ,law.invention - Abstract
CORRIGENDUM: Carcinogenicity evaluation for the application of carbon nanotubes as biomaterials in rasH2 mice
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- 2013
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49. ROS evaluation for a series of CNTs and their derivatives using an ESR method with DMPO
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Dale W. Porter, Kenji Takeuchi, K. Koyama, F Tristan, T Noguchi, Morinobu Endo, Hidetoshi Matsumoto, Mauricio Terrones, Naoto Saito, Shuji Tsuruoka, Vince Castranova, and Yuki Usui
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History ,Quenching (fluorescence) ,Nanotechnology ,Carbon nanotube ,Photochemistry ,Article ,Computer Science Applications ,Education ,law.invention ,Ros scavenging ,chemistry.chemical_compound ,Electron transfer ,chemistry ,law ,Manufacturing methods ,Hydrogen peroxide ,Scavenging - Abstract
Carbon nanotubes (CNTs) are important materials in advanced industries. It is a concern that pulmonary exposure to CNTs may induce carcinogenic responses. It has been recently reported that CNTs scavenge ROS though non-carbon fibers generate ROS. A comprehensive evaluation of ROS scavenging using various kinds of CNTs has not been demonstrated well. The present work specifically investigates ROS scavenging capabilities with a series of CNTs and their derivatives that were physically treated, and with the number of commercially available CNTs. CNT concentrations were controlled at 0.2 through 0.6 wt%. The ROS scavenging rate was measured by ESR with DMPO. Interestingly, the ROS scavenging rate was not only influenced by physical treatments, but was also dependent on individual manufacturing methods. Ratio of CNTs to DMPO/ hydrogen peroxide is a key parameter to obtain appropriate ROS quenching results for comparison of CNTs. The present results suggest that dangling bonds are not a sole factor for scavenging, and electron transfer on the CNT surface is not clearly determined to be the sole mechanism to explain ROS scavenging. more...
- Published
- 2013
50. Scintillation Properties of (Lu,Y)AlO3 Doped with Nd.
- Author
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Masaki Akatsuka, Yuki Usui, Daisuke Nakauchi, Go Okada, Noriaki Kawaguchi, and Takayuki Yanagida
- Subjects
SCINTILLATION spectrometry ,SCINTILLATORS ,NEODYMIUM spectra ,NEAR infrared radiation ,EXPONENTIAL decay law - Abstract
(Lu,Y)AlO
3 crystals doped with different concentrations of Nd were synthesized by the floating-zone (FZ) method to evaluate their scintillation properties, particularly in the near-infrared (NIR) range. Under X-ray irradiation, scintillation due to the4 F3/2 →4 I11/2 transition of Nd3+ was observed at 1064 nm. The scintillation decay time profile was approximated by an exponential decay function, and the obtained value varied from 2-3 to 150 μs depending on the concentration of Nd3+ . [ABSTRACT FROM AUTHOR] more...- Published
- 2018
- Full Text
- View/download PDF
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