488 research outputs found

    Observation of the thermosiphon effect in the circulation of liquid nitrogen in HTS cable cooling system

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    AbstractIt is traditionally considered that superconducting technology is just the way that will help to overcome the energy crisis and improve the environmental safety of the electricity production. However, real achievements in this field still insufficient to build commercial long power transmission lines. In particular, cooling systems constructed using expensive coolant circulation pumps have to be improved. Our previous calculations show that the use of a thermosiphon effect may reduce both the heat load and the required coolant circulation pump power and, ideally, would completely abandon the forced circulation. Direct experimental verification of this approach has been carried out at the new 200-meter HTS DC experimental facility of the Chubu University. The thermosiphon effect was clearly observed in satisfactory agreement with theory, although the change in elevation of the cryopipe was small. Our results will be used to design an effective HTS cable cooling system based on natural circulation of the coolant

    Effects of the implant design on peri-implant bone stress and abutment micromovement: Three-dimensional finite element analysis of original computer-aided design models

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    Background: Occlusal overloading causes peri-implant bone resorption. Previous studies examined stress distribution in alveolar bone around commercial implants using three-dimensional (3D) finite element analysis. However, the commercial implants contained some different designs. The purpose of this study is to reveal the effect of the target design on peri-implant bone stress and abutment micromovement. Methods: Six 3D implant models were created for different implant-abutment joints: 1) internal joint model (IM); 2) external joint model (EM); 3) straight abutment (SA) shape; 4) tapered abutment (TA) shapes; 5) platform switching (PS) in the IM; and 6) modified TA neck design (reverse conical neck [RN]). A static load of 100 N was applied to the basal ridge surface of the abutment at a 45-degree oblique angle to the long axis of the implant. Both stress distribution in peri-implant bone and abutment micromovement in the SA and TA models were analyzed. Results: Compressive stress concentrated on labial cortical bone and tensile stress on the palatal side in the EM and on the labial side in the IM. There was no difference in maximum principal stress distribution for SA and TA models. Tensile stress concentration was not apparent on labial cortical bone in the PS model (versus IM). Maximum principal stress concentrated more on peri-implant bone in the RN than in the TA model. The TA model exhibited less abutment micromovement than the SA model. Conclusion: This study reveals the effects of the design of specific components on peri-implant bone stress and abutment displacement after implant-supported single restoration in the anterior maxilla.This is the pre-peer reviewed version of the following article:Yamanishi Y., Yamaguchi S., Imazato S., et al. Effects of the implant design on peri-implant bone stress and abutment micromovement: Three-dimensional finite element analysis of original computer-aided design models. Journal of Periodontology 85, (2014), which has been published in final form at https://doi.org/10.1902/jop.2014.140107. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

    Development of a Novel Method for Immobilization of DNA Applied for DNA Chip

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    Silane coupling agent 1 containing active ester was synthesized and applied for surface modification of silicon wafer. An active ester immobilized using 1 was reacted with a nonanucleotide containing an amino group at the 5\u27-terminal labeled with a fluorescent reagent followed by observation of the surfaces using a fluorescence microscope. The result showed that the coupling agent was potential for novel compounds for immobilization of DNA

    Influences of implant neck design and implant–abutment joint type on peri-implant bone stress and abutment micromovement: Three-dimensional finite element analysis

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    Objectives: Occlusal overloading is one of the causes of peri-implant bone resorption, and many studies on stress distribution in the peri-implant bone by three-dimensional finite element analysis (3D FEA) have been performed. However, the FEA models previously reported were simplified and far from representing what occurs in clinical situations. In this study, 3D FEA was conducted with simulation of the complex structure of dental implants, and the influences of neck design and connections with an abutment on peri-implant bone stress and abutment micromovement were investigated. Methods: Three types of two-piece implant CAD models were designed: external joint with a conical tapered neck (EJ), internal joint with a straight neck (IJ), and conical joint with a reverse conical neck (CJ). 3D FEA was performed with the setting of a “contact” condition at the component interface, and stress distribution in the peri-implant bone and abutment micromovement were analyzed. Results: The shear stress was concentrated on the mesiodistal side of the cortical bone for EJ. EJ had the largest amount of abutment micromovement. While the von Mises and shear stresses around the implant neck were concentrated on the labial bone for IJ, they were distributed on the mesiodistal side of the cortical bone for CJ. CJ had the least amount of abutment micromovement. Significance: Implants with a conical joint with an abutment and reverse conical neck design may effectively control occlusal overloading on the labial bone and abutment micromovement.Yamanishi Y., Yamaguchi S., Imazato S., et al. Influences of implant neck design and implant–abutment joint type on peri-implant bone stress and abutment micromovement: Three-dimensional finite element analysis. Dental Materials 28, 1126 (2012); https://doi.org/10.1016/j.dental.2012.07.160

    Influence of implant length and diameter, bicortical anchorage, and sinus augmentation on bone stress distribution: Three-dimensional finite element analysis

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    Purpose: Clarification of the protocol for using short implants is required to enable widespread use of short implants as an available treatment option. The purpose of this study was to investigate the influences of implant length and diameter, bicortical anchorage, and sinus augmentation on peri-implant cortical bone stress by three-dimensional finite element analysis. Materials and Methods: For bone models with bone quantity A and C in the maxillary molar region, three-dimensional finite element analysis was performed using different lengths and diameters of implant computer-aided design models, and the degree of maximum principal stress distribution for each model was calculated. Results: For bone quantity A models, the degree of stress distribution of the 4-mm-diameter, 6-mm-length implant was the greatest. For bone quantity C models, the degree of stress distribution of the 5-mm-diameter, 6-mm-length implant with bicortical anchorage was much smaller than that for the 4-mm-diameter, 13-mm-length implant with sinus augmentation. Conclusion: The results of this study suggest that 6-mm-length implants should be selected in cases with bone quantity C where the bone width permits increasing implant diameter from 4 mm to 5 mm.Moriwaki H., Yamaguchi S., Nakano T., et al. Influence of implant length and diameter, bicortical anchorage, and sinus augmentation on bone stress distribution: Three-dimensional finite element analysis. International Journal of Oral and Maxillofacial Implants 31, 84 (2016); https://doi.org/10.11607/jomi.4217

    Optical impression method to measure three-dimensional position and orientation of dental implants using an optical tracker

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    Objectives: The aim of this study was to devise an optical impression method that could make impressions of dental implants accurately and rapidly. Materials and methods: Four paper markers (4 × 3 mm, 8 × 6 mm, 16 × 12 mm, and 24 × 18 mm) and one titanium marker (8 × 6 mm) were prepared to determine the measuring accuracy of the three-dimensional optical tracker. For a proposed and conventional impression taking method, we compared the reproduction accuracies of the positions and orientations of dental implants and the times to obtain impressions. Finally, we fabricated computer-aided designing (CAD)/computer-aided manufacturing (CAM) superstructure frameworks to determine the adaptation accuracy. Results: The 8 × 6-mm titanium marker was optimal among the prepared markers. Dental implants made by the proposed and conventional impression taking methods had measurement errors of 71 ± 31 μm and 32 ± 18 μm, respectively. The proposed method took a significantly shorter time to obtain an impression than did the conventional method. The connection between the CAD/CAM superstructure frameworks and four implant analogs had uplifts of 55 ± 10 μm, 94 ± 35 μm, 2 ± 1 μm, and 66 ± 3 μm. Conclusion: Our proposed method and fabricated titanium markers enabled us to measure the positions and orientations of dental implants both accurately and rapidly. We then used the reproducible measurement results for the positions and orientations of the dental implants to fabricate CAD/CAM superstructure frameworks within an acceptable accuracy range. © 2012 John Wiley & Sons A/S.This is the pre-peer reviewed version of the following article: Ono S., Yamaguchi S., Kusumoto N., et al. Optical impression method to measure three-dimensional position and orientation of dental implants using an optical tracker. Clinical Oral Implants Research 24, 1117 (2013), which has been published in final form at https://doi.org/10.1111/j.1600-0501.2012.02519.x.. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

    Interactions between IL-32 and tumor necrosis factor alpha contribute to the exacerbation of immune-inflammatory diseases

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    IL-32 is a newly described cytokine in the human found to be an in vitro inducer of tumor necrosis factor alpha (TNFα). We examined the in vivo relationship between IL-32 and TNFα, and the pathologic role of IL-32 in the TNFα-related diseases – arthritis and colitis. We demonstrated by quantitative PCR assay that IL-32 mRNA was expressed in the lymphoid tissues, and in stimulated peripheral T cells, monocytes, and B cells. Activated T cells were important for IL-32 mRNA expression in monocytes and B cells. Interestingly, TNFα reciprocally induced IL-32 mRNA expression in T cells, monocyte-derived dendritic cells, and synovial fibroblasts. Moreover, IL-32 mRNA expression was prominent in the synovial tissues of rheumatoid arthritis patients, especially in synovial-infiltrated lymphocytes by in situ hybridization. To examine the in vivo relationship of IL-32 and TNFα, we prepared an overexpression model mouse of human IL-32β (BM-hIL-32) by bone marrow transplantation. Splenocytes of BM-hIL-32 mice showed increased expression and secretion of TNFα, IL-1β, and IL-6 especially in response to lipopolysaccharide stimulation. Moreover, serum TNFα concentration showed a clear increase in BM-hIL-32 mice. Cell-sorting analysis of splenocytes showed that the expression of TNFα was increased in resting F4/80(+ )macrophages, and the expression of TNFα, IL-1β and IL-6 was increased in lipopolysaccharide-stimulated F4/80(+ )macrophages and CD11c(+ )dendritic cells. In fact, BM-hIL-32 mice showed exacerbation of collagen-antibody-induced arthritis and trinitrobenzen sulfonic acid-induced colitis. In addition, the transfer of hIL-32β-producing CD4(+ )T cells significantly exacerbated collagen-induced arthritis, and a TNFα blockade cancelled the exacerbating effects of hIL-32β. We therefore conclude that IL-32 is closely associated with TNFα, and contributes to the exacerbation of TNFα-related inflammatory arthritis and colitis

    Implementation of a new specific program for training curators at Hiroshima University

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    博物館法施行規則の改正に伴い,2012年4月から学芸員資格取得のために修得すべき科目が大幅に変更となった。学芸員資格取得の歴史においてはきわめて大きな変更である。本学では,これに対応するため,各学部の学芸員資格取得特定プログラムを統合し,全学の学生を対象とする新課程に移行した。本稿では,本学が新たに採用した4学期制(ターム制)を含め,今回の変更が受講や資格取得にどのような影響を及ぼしたのか,統計データの分析を通じて考察した。新課程移行の前後で,プログラム登録者数,資格取得者数は大幅に減少し,取得率も大きく低下した。こうした現象は特定の学部,分野の変化に基づくものではなく,旧課程においてプログラム登録の主体となってきた全ての学部に共通する。分析を通じて,大幅な必要単位数の増加,全学を対象としたプログラムへの変更,2学期制から4学期制(ターム制)への変更など,複数の要因が関連して,各学部における専門の修得と学芸員資格取得を両立させることが困難な状況が生じていることが推定された。As a result of the revision of Museum Law Enforcement Rules, the subjects that must be completed to acquire the curator qualification have changed significantly since April 2012, which constitutes a major change in the history of this qualification. To cope with this change, we integrated the curator qualification specific programs of each faculty into a new course for students of all universities. In this paper, through statistical data analysis, we examined the impact of this change on attendance trends, including the term system newly adopted by Hiroshima University. Before and after the transition to the new course, the number of program registrants and qualifications greatly decreased, and the acquisition rate has also declined significantly. These phenomena were not based on changes in specific faculties or fields, but are common to all faculties subject to program registration during the old course. Through this analysis, we presumed that several factors, such as the great increase in the required number of credits, the change to the program for the whole school, and the change from a two-semester system to the four-semester system, were all interrelated to each other, which make it difficult to achieve both specialized and curator qualifications.本稿は,2018年6月22日に香川大学で開催された第13回日本博物科学会で口頭発表した藤野次史・青木孝夫・清水則雄・菅村 亨・本多博之・山口富美夫・山崎博史・吉田将之「広島大学における新課程実施後の学芸員資格取得状況について」を元に,新たなデータを加えて考察したものである
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