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Amount of Calcium Elution and Eroded Lesion Depth in Bovine Enamel Derived from Single Short Time Immersion in Carbonated Soft Drink <i>in Vitro</i>

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Open Journal of Stomatology 2015年第3期5卷 80-86页

作者： Koji Watanabe Toshiko Tanaka Kenshi Maki hideaki nakashima Shigeru Watanabe Division of Pediatric Dentistry Department of Development and Fostering Meikai University School of Dentistry Saitama Japan Division of Surgery Department of Health Promotion Kyushu Dental University Fukuoka Japan Division of Developmental Stomatognathic Function Science Department of Health Promotion Kyushu Dental University Fukuoka Japan

Erosion is one of serious oral health problems among Japanese children. Some dentists argue that brushing just after food/drink intake induces enamel abrasion. Objectives of this study were to evaluate amount of calcium elution from bovine enamel due to single and short immersion into carbonated soft drink, to calculate depth of the eroded lesion, and to determine when to brush teeth after carbonated soft drink intake from the view point of preventing enamel abrasion. Four enamel specimens were made from each of eight bovine teeth. The specimens were covered by quick-cure resin except for enamel surfaces. The four specimens from each bovine tooth were classified into three, six, nine, and 12 minutes immersion (IM3, IM6, IM9, and IM12) groups and immersed separately in five mL of carbonated soft drink. After the immersion, the calcium concentration of the original drink and the drink samples were evaluated using atomic absorption spectrophotometry. The dimension of each enamel specimen was calculated using a planimeter. The amount of eluted calcium per unit area of the enamel specimen into each drink sample was obtained. The depth of the demineralized lesion was obtained by dividing the amount of calcium elution per unit area by the concentration of calcium in enamel and the specific gravity of enamel. The lesion depth of the IM3 group was significantly lower than those in the IM6, IM9, and IM12 groups. The mean lesion depth in the IM12 group which showed the deepest lesion depth was 0.21 μm. As conclusions, the erosive lesion depth due to intake of carbonated soft drink was much shallower than remineralized enamel surface of a white spot lesion which can be repaired in plaque fluid in a short time, suggesting such erosion hardly causes tooth wear, hence it was suggested that brushing teeth just after the intake was recommended.

关键词： Erosion Bovine Enamel Carbonated Soft Drink Calcium

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Acid Elution of Aluminum and Calcium from Human Deciduous Enamel in Relation to Dental Caries

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Open Journal of Stomatology 2016年第2期6卷 54-63页

作者： Koji Watanabe Toshiko Tanaka Ayaka Enomoto Katsura Saeki Shigenori Kawagishi hideaki nakashima Kenshi Maki Shigeru Watanabe Division of Pediatric Dentistry Department of Human Development and Fostering Meikai University School of Dentistry Sakado Japan Division of Developmental Stomatognathic Function Science Department of Health Promotion Kyushu Dental University Kitakyushu Japan Division of Surgery Department of Health Promotion Kyushu Dental University Kitakyushu Japan Division of Multidisciplinary Studies Department of Health Promotion Kyushu Dental University Kitakyushu Japan

Although aluminum itself was reported to prevent dental caries, previous in vitro studies reported that the aluminum level in the whole saliva of children was independent of caries prevalence. Purposes of this study were to compare the elution levels of aluminum and calcium from deciduous enamel into acidic artificial saliva, and determine whether the degree of aluminum elution reflects individual caries risk. One hundred and eleven extracted human deciduous teeth were collected. Concentrations of aluminum and calcium eluted from sound regions of enamel into artificial saliva (pH 6.2 or 5.5) were determined using atomic absorption spectrophotometry. One hundred and four and 108 available data samples were obtained for aluminum and calcium evaluation, respectively, and were compared based on the sex, tooth type, caries history, and the number of the donor’s carious teeth at each pH. Calcium elution was not affected by the sex;however, more aluminum was eluted from boys’ than from girls’ teeth at pH 5.5. The aluminum release depended on the tooth type, and was significantly higher in incisors than in molars at a pH of 5.5. In relation to the caries history, aluminum (at pH 5.5) and calcium (at pH 6.2) dissolved more from sound regions of the enamel of caries-experienced teeth than from the enamel of teeth without caries experience. Moreover, aluminum markedly dissolved from enamel in artificial saliva at both pH 6.2 and 5.5 when the donor had more carious teeth, regardless of the presence or absence of caries experience in the sampled teeth. There is a possibility that the rate of aluminum elution from enamel into acidic fluid reflects individual caries sensitivity.

关键词： Aluminum Elution Deciduous Enamel Dental Caries Artificial Saliva

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Application of headed studs in steel fiber reinforced cementitious composite slab of steel beam-column connection

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Earthquake Engineering and Engineering Vibration 2012年第1期11卷 11-21页

作者： Yao Cui Masayoshi nakashima Center for Urban Earthquake Engineering Tokyo Institute of Technology Japan Disaster Prevention Research Institute Kyoto University Gokashyo Uji Kyoto Japan

Steel fiber reinforced cementitous composites （SFRCC） is a promising material with high strength in both compression and tension compared with normal concrete. The ductility is also greatly improved because of 6% volume portion of straight steel fibers. A steel beam-column connection with Steel fiber reinforced cementitous composites （SFRCC） slab diaphragms is proposed to overcome the damage caused by the weld. The push-out test results suggested that the application of SFRCC promises larger shear forces transferred through headed studs allocated in a small area in the slab. Finite element models were developed to simulate the behavior of headed studs. The failure mechanism of the grouped arrangement is fiarther discussed based on a series of parametric analysis. In the proposed connection, the SFRCC slab is designed as an exterior diaphragm to transfer the beam flange load to the column face. The headed studs are densely arranged on the beam flange to connect the SFRCC slab diaphragms and steel beams. The seismic performance and failure mechanism of the SFRCC slab diaphragm beam-column connection were investigated based on the cyclic loading test. Beam hinge mechanism was achieved at the end of the SFRCC slab diaphragm by using sufficient studs and appropriate rebars in the SFRCC slab.

关键词： multi-directional transmitting artificial boundary viscous-spring artificial boundary saturated soilfoundation Biot's equations

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Flexible substructure online hybrid test system using conventional testing devices

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Earthquake Engineering and Engineering Vibration 2013年第3期12卷 341-350页

作者： Wang Tao Masayoshi nakashima Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics China Earthquake Administration Disaster Prevention Research Institute Kyoto University

This paper presents a substructure online hybrid test system that is extensible for geographically distributed tests. This system consists of a set of devices conventionally used for cyclic tests to load the tested substructures onto the target displacement or the target force. Due to their robustness and portability, individual sets of conventional loading devices can be transported and reconfigured to realize physical loading in geographically remote laboratories. Another appealing feature is the flexible displacement-force mixed control that is particularly suitable for specimens having large disparities in stiffness during various performance stages. To conduct a substructure online hybrid test, an extensible framework is developed, which is equipped with a generalized interface to encapsulate each substructure. Multiple tested substructures and analyzed substructures using various structural program codes can be accommodated within the single framework, simply interfaced with the boundary displacements and forces. A coordinator program is developed to keep the boundaries among all substructures compatible and equilibrated. An Interuet-based data exchange scheme is also devised to transfer data among computers equipped with different software environments. A series of online hybrid tests are introduced, and the portability, flexibility, and extensibility of the online hybrid test system are demonstrated.

关键词： substructure online hybrid test conventional loading device displacement-force mixed control coordinator program Interuet-based data exchange scheme

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A tendon system to re-center steel moment frames with weak stories

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Earthquake Engineering and Engineering Vibration 2024年第4期23卷 1057-1072页

作者： Wang Tao Wang Fei Masayoshi nakashima Institute of Engineering Mechanics China Earthquake AdministrationBeijing 100190China Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Disaster Prevention Research Institute Kyoto UniversityGokashoUjiKyoto 611-0011Japan

A wide open bottom story of a frame building is often expected by owners for use as a garage or ***,this leads to weak stories due to abrupt changes in lateral stiffness and often results in unexpected story collapse as observed in many previous *** retrofit frame buildings that have experienced weak story damage,a tendon system is proposed in this study,which consists of a set of swaying columns and *** swaying columns are used to uniformly redistribute the lateral deformation along the height,while the tendons provide extra lateral stiffness and renders the entire structural system a re-centering *** avoid unnecessary forces to swaying columns,pin-connections are used at the *** are placed over the entire story to gain large elastic *** analysis reveals that the swaying column,with a stiffness of about 0.9 times that of the weak story,and the tendons attached at the roof,with a stiffness of 0.04 times that of the weak story,can provide the optimal performance with a maximum residual story drift angle of less than 0.5%.Online hybrid tests were carried out,which demonstrated that uniformly distributed story drifts and acceptable residual deformation could be achieved by the proposed tendon system.

关键词： tendon system re-centering capability residual deformation rehabilitation collapse prevention

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Differences in dinucleotide frequencies of thermophilic genes encoding water soluble and membrane proteins

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2011年第6期12卷 419-427页

作者： Hiroshi nakashima Yuka KURODA Department of Clinical Laboratory Science Graduate Course of Medical Science and TechnologySchool of Health SciencesKanazawa University

The occurrence frequencies of the dinucleotides of genes of three thermophilic and three mesophilic species from both archaea and eubacteria were investigated in this study. The genes encoding water soluble proteins were rich in the dinucleotides of purine dimers, whereas the genes encoding membrane proteins were rich in pyrimidine dimers. The dinucleotides of purine dimers are the counterparts of pyrimidine dimers in a double-stranded DNA. The purine/pyrimidine dimers were favored in the thermophiles but not in the mesophiles, based on comparisons of observed and expected frequencies. This finding is in agreement with our previous study which showed that purine/pyrimidine dimers are positive factors that increase the thermal stability of DNA. The dinucleotides AA, AG, and GA are components of the codons of charged residues of Glu, Asp, Lys, and Arg, and the dinucleotides TT, CT, and TC are components of the codons of hydrophobic residues of Leu, Ile, and Phe. This is consistent with the suitabilities of the different amino acid residues for water soluble and membrane proteins. Our analysis provides a picture of how thermophilic species produce water soluble and membrane proteins with distinctive characters: the genes encoding water soluble proteins use DNA sequences rich in purine dimers, and the genes encoding membrane proteins use DNA sequences rich in pyrimidine dimers on the opposite strand.

关键词： Water soluble and membrane proteins Purine/pyrimidine dimers Thermophilic and mesophilic species Dinucleotide frequencies

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Statistical evaluation of cluster formation of relapse in neuromyelitis optica spectrum disorder

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Neural Regeneration Research 2024年第9期19卷 1888-1889页

作者： Tetsuya Akaishi Ichiro nakashima Department of Neurology Tohoku UniversitySendaiJapan Department of Neurology Tohoku Medical and Pharmaceutical UniversitySendaiJapan

Evaluating the cluster formation of clinical attacks in chronic relapsing diseases is an important statistical issue because the presence of attack clusters may influence therapeutic strategies for relapse *** recently reported the occurrence of unevenly clustered attacks in patients with anti-aquaporin-4(AQP4)antibody-positive neuromyelitis optica spectrum disorder(NMOSD)(Akaishi et al.,2020a).

关键词： AQP4 relapse

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Semi-3D cultures using Laminin 221 as a coating material for human induced pluripotent stem cells

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Regenerative Biomaterials 2022年第1期9卷 775-793页

作者： Yoshiki nakashima Shinsuke Yoshida Masayoshi Tsukahara Kyoto University Center for iPS Cell Research and Application Foundation(CiRA Foundation) Facility for iPS Cell Therapy(FiT)Kyoto 606-8397Japan

It was previously believed that human induced pluripotent stem cells(hiPSCs)did not show adhesion to the coating material Laminin 221,which is known to have specific affinity for *** this study,we report that human mononuclear cell-derived hiPSCs,established with Sendai virus vector,form peninsular-like colonies rather than embryonic stem cell-like colonies;these peninsular-like colonies can be passaged more than 10 times after ***,initializationdeficient cells with residual Sendai virus vector adhered to the coating material Laminin 511 but not to Laminin ***,the expression of undifferentiated markers tended to be higher in hiPSCs established on Laminin 221 than on Laminin *** Laminin 221,hiPSCs15M66 showed a semi-floating colony *** expression of various markers of cell polarity was significantly lower in hiPSCs cultured on Laminin 221 than in hiPSCs cultured on Laminin ***,201B7 and 15M66 hiPSCs showed 3D cardiomyocyte differentiation on Laminin ***,the coating material Laminin 221 provides semi-floating culture conditions for the establishment,culture and induced differentiation of hiPSCs.

关键词： human induced pluripotent stem cells(hiPSCs) regenerative medicine coating material cardiomyocyte therapeutic cells

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Earthquake engineering research needs in light of lessons learned from the 2011 Tohoku earthquake

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Earthquake Engineering and Engineering Vibration 2014年第S1期13卷 141-149页

作者： Masayoshi nakashima Oren Lavan Masahiro Kurata Yunbiao Luo Disaster Prevention Research Institute (DPRI) Kyoto University Professor Disaster Prevention Research Institute (DPRI) Kyoto UniversityGokashoUjiKyotoJapan Faculty of Civil and Environmental Engineering Technion–Israel Institute of TechnologyHaifaIsrael Assistant Professor Post Doctoral Fellow

Earthquake engineering research and development have received much attention since the first half of the twentieth century. This valuable research presented a huge step forward in understanding earthquake hazard mitigation,which resulted in appreciable reduction of the effects of past earthquakes. Nevertheless,the 2011 Tohoku earthquake and the subsequent tsunami resulted in major damage. This paper presents the timeline of earthquake mitigation and recovery,as seen by the authors. Possible research directions where the authors think that many open questions still remain are identified. These are primarily based on the important lessons learned from the 2011 Tohoku earthquake.

关键词： research needs earthquake engineering quick recovery 2011 Tohoku earthquake

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Improvement of a temperature response function for divertor heat flux monitoring in fusion devices

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Plasma Science and Technology 2023年第3期25卷 217-221页

作者： Xuan Nhat Son BUI Hiroto MATSUURA Yousuke nakashima Quantum and Radiation Engineering Department Osaka Prefecture University Plasma Research Center University of Tsukuba

Temperature response functions have been developed to investigate sensor design and divertor heat flux estimation in magnetically confined plasmas. The time-dependent heat flux can be derived by fitting the response function to experimental thermocouple(TC) data. Because the TC signals have a time delay to transit events such as discharge start or confinement transition, the time delay is taken into account in a temperature response function. Such a function accurately describes the signal from each TC channel with time delay in a sensor test using a neutral beam injection. Measurement for commercial TCs shows that the time delay is caused by the finite heat capacity of TC wire and contact heat resistance between TC and target surface.

关键词： divertor temperature response function thermocouple system primary delay

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