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有機物がドロマイト化の過程に及ぼす影響
Get PDF新潟大学Niigata University博士（理学）The "dolomite problem" refers to the challenge of explaining the significant variability in dolomite production throughout geological time periods, as well as the difficulty of replicating dolomite formation under ambient lab conditions despite its presence in surface environments in the past. In recent years, dolomite precipitation mediated by microbial has gained significant attention. It has been suggested that microbial activity may be the key to overcome kinetic barriers to promote dolomite precipitation. The exact mechanism by which bacteria facilitate dolomite formation is not fully understood, but it is known that bacteria have cell walls primarily composed of polysaccharides and lipids, and produce extracellular polymeric substances (EPS), which are primarily composed of exopolysaccharides. These polysaccharides may function as a catalyst to facilitate the formation of dolomite. The study aimed to investigate the catalytic potential of EPS and bacterial cell walls in dolomitization, as well as other natural polysaccharides, by testing the catalytic activity of two specific polysaccharides—carboxymethyl cellulose (CMC) and agar—which can be considered analogs of EPS and bacterial cell walls. The objective was to gain insights into the role of natural polysaccharides in the geological process of dolomitization. Hydrothermal synthesis experiments were conducted in Teflon-lined stainless-steel batch reactors at 200 ℃, where solid reactant calcium carbonate phases, synthetic calcite, geological calcite crystal and natural aragonite, were reacted with experimental solutions containing dissolved magnesium chloride hexahydrate, calcium chloride dihydrate and polysaccharide. Through the vapor diffusion method, synthesis experiments were also carried out in vial tubes placed in a desiccator at room temperature. Synthetic calcite was used as seed crystals and reacted with Mg2+ and Ca2+, along with CMC that had been heated at various temperatures, while the decomposition of ammonium bicarbonate and ammonium carbonate produces NH3 and CO2 to raise the solution pH and alkalinity to trigger carbonate precipitation. The data from the experimental synthesis of dolomite with synthetic calcite at 200 ℃ showed that 0.1 g/L agar, 0.1 g/L CMC and 0.2 g/L CMC all could extend both the induction period and replacement period of dolomitization reaction. Regression analysis demonstrates that the 0.1 g/L agar and 0.2 g/L CMC decrease the cation ordering rate of dolomite produced from synthetic calcite compared to when polysaccharides are absent. In contrast, the 0.1 g/L CMC series shows a slight increase in the cation ordering rate relative to conditions without polysaccharides. The longer reaction times for dolomitization reaction observed during the experimental synthesis of dolomite using natural aragonite also suggested the presence of an inhibitory effect at 200 ℃, whereas the difference lies in that 0.1 g/L CMC only extended the length of the induction period, while 0.1 g/L agar and 0.2g/L agar merely prolonged the length of the replacement period. Regarding the cation ordering rate, both 0.1 g/L agar and 0.2 g/L agar exhibited inhibitory effects, while 0.1 g/L CMC showed a slight promotional effect. The scanning electron microscopy (SEM) investigations of reaction products in hydrothermal synthesis experiments indicated that the inhibitory effect of the decompositions of polysaccharides could be attributed to their absorption onto calcite and aragonite surfaces, which hinders their dissolution. On the other hand, synthesis experiments conducted in desiccator at room temperature revealed that heated CMC has a promotional effect on the dolomite precipitation reaction. Moreover, CMC subjected to higher pre-treatment temperatures demonstrated stronger catalytic effects. In summary, the findings of the study suggest a notable potential impact of the decomposition products of polysaccharides on the formation of dolomite, although it is uncertain whether they inhibit cation ordering process. The inhibitory effect observed in the decomposition products of CMC and agar could also exist in the decomposition products of EPS and bacteria cell walls found in sedimentary rocks during burial diagenesis. Therefore, further research is necessary to understand the role of EPS and bacteria cell walls in dolomitization, since their impact is not always predictable.新大博(理)第70
Image-based finite element analysis of Bivalvia’s shell form for spatial structure design
Get PDF新潟大学Niigata University博士（工学）Biomimetics means that inspirations by the form, structure, function, and capabilities of living organ-isms, mimic and apply to engineering. Also, in the architectural field, we have many cases which designed and constructed by biomimetic inspirations from time immemorial. However, it is pointed out that only the design concept is from nature, not biomimetic design in the original sense. I focused on seashells, especially Bivalvia’s shells which are thought to have optimized their form during their evolution in di-verse habitats. The seashell form has been considered for potential applications in architectural structure systems. In the previous research related to seashell mechanics, these experiments were limited to simple data measurements and used mathematical models, which do not reflect the actual detailed geometry. In addition, the relationship between geometric and mechanical properties has not been quantitatively exam-ined. This study presents the geometric and mechanical properties of Bivalvia’s shell from image-based modeling and finite element analysis and discusses their relationship quantitatively. Fluvia mutica was selected as a specimen of this study. This species is one of the bivalves with large interior spaces, reminiscent of dome and spatial structures. The X-ray CT images of the specimen were input into reconstruction software and an STL model of the specimen was created. Point clouds reflected the front and back surfaces of the specimen were created from the information within the STL file format. The specimen’s geometric properties were obtained using the point clouds. Thickness distribution revealed that the specimen is a thin shell structure. Gauss curvature distribution revealed that the specimen’s umbo is the surface with large positive curvature, and the specimen’s abdomen is the surface with minimum positive curvature. Both geometric properties are in line with the distribution of the sculptures on the surface of the specimen. A finite element model of the specimen was created by splitting the STL model into tetrahedral solid elements (this study calls this model a solid model). Buckling and elastic analysis were executed using the solid model. The deformation mechanism and stress distribution of the specimen under static loading were discussed from these analysis results. Those properties were also discussed with the geometric properties of the specimen. Next, dynamic analysis which is essential for consideration of the structural capacity of buildings was executed. A finite element model of the specimen was created using a triangular shell element with a small computational load (this study calls this model a shell model), using the point clouds used in the geometric analysis. The shell models were evaluated by comparing them with the mechanic analysis results of the solid model. The creation shell model method of this study can create models reflecting each of the front, back, and neutral surface geometries. and among them, the results for the model reflected neutral surface geometry were most consistent with those of the solid model. By changing the element type of the finite element models, the time required for dynamic analysis was reduced by more than 80 %, and dynamic analysis was achieved with finite element models that retained detailed geometry. Vibration analysis and seismic analysis were executed using the shell model. A finite element model of a hemisphere concrete shell structure (this study calls this model dome model) was created as a comparison, and both models were analyzed under identical conditions. The deformation mechanism and stress distribution of the specimen under dynamic loading were discussed from these analysis results. Those properties were also discussed with the geometric properties of the specimen. In this study, the STL model created from X-ray CT images was used to measure the geometric properties of the specimen in three dimensions. The image-based finite element analysis was also performed using the same STL model to discuss the mechanical properties under static and dynamic loading conditions. By collating both results, the relationship between them was discussed. The mechanical properties of the specimens are not evaluated concerning the local geometric properties of the sculpture in this study. To solve this problem, it is necessary to express the presence or absence of sculpture in the finite element model and to create a finite element model that can evaluate only the thickness distribution, which is not easy. I believe that the introduction of a mathematical model of seashells is effective in realizing those finite element models. And I believe that shape optimization problems that consider the seashell’s properties, and the study-related mechanism of the seashell’s exoskeleton form should be pursued for the final goal of clarifying properties that can be utilized in the design of spatial structures.新大院博(工)第558
重症好酸球性喘息におけるベンラリズマブの3次元コンピュータ断層画像解析への影響
Get PDF新潟大学Niigata University博士（医学）Introduction: Benralizumab, an anti-interleukin-5 receptor chain monoclonal antibody, is used to treat severe asthma and control asthma symptoms or exacerbations. The aim of this study was to examine the changes in airway morpholo-gy using computed tomography (CT) images in accordance with clinical efficacy following the administration of benrali-zumab. Methods: The clinical efficacy of benralizumab was evaluated in 11 patients with severe asthma by analyzing the changes in parameters, such as the asthma control test, asth-ma quality of life questionnaire, pulmonary function, and ex-acerbation count. We also investigated the airway wall thick-ness of the right bronchus (B1) and the total airway count (TAC) using CT images. Results: Most patients treated with benralizumab showed improvements in asthma symptoms and exacerbations. CT imaging analyses showed a decrease in the right B1 airway wall thickness and an increase in the TAC. Correlations between blood eosinophil count and changes in CT imaging were observed. Discussion/Conclu-sion: The data suggested that benralizumab has the poten-tial to improve airway wall thickening and ventilation by al-leviating the obstruction and clearing an obstructed airway.Fumito Tsubokawa, Toshiyuki Koya, Yui Murai, Kentaro Tanaka, Yuchi Tsutsui, Shun Naramoto, Natsumi Sakai, Ami Aoki, Kenjiro Shima, Yosuke Kimura, Satoshi Watanabe, Takashi Hasegawa, Toshiaki Kikuchi; Effects of Benralizumab on Three-Dimensional Computed Tomography Analysis in Severe Eosinophilic Asthma. Int Arch Allergy Immunol 3 March 2023; 184 (3): 243–251. https://doi.org/10.1159/000525846新大院博（医）第1184
Ethyl Glucuronide Measurement by PESI-MS/MS for detection of Antemortem Alcohol Consumption
Get PDF新潟大学Niigata University博士（医学）【緒言】法医学における死亡前のアルコール (エタノール) 摂取の証明は, 死亡原因を判断する上で重要である. 体内のエタノール濃度は, アルコール摂取によらない体内でのエタノールの生成や分解の影響を受けるため, エタノール代謝物による評価が検討されている. 候補のひとつであるエチルグルクロニド (EtG)は，一般的には LC-MS により測定されている. PESI-MS/MS は,極微量の検体で簡便かつ迅速に測定が可能な装置である. 法医学的な目的から EtG 測定にPESI-MS/MS を用いた報告はない. そこで, 死亡 1 日前のアルコール摂取の証明にPESI-MS/MSによる EtG 測定を用いることが可能かどうかについて, 検証を行った. 【方法】2019 年から2022 年までに本学で解剖された 113 事例の血液と尿を用いて, エタノール濃度とEtG の測定を行った. エタノール濃度の測定には GC を用いた. EtG の測定には PESI-MS/MS を用い, 内部標準物質 EtG-d5 との比であるEtG/EtG-d5 値を算出した. 【結果】血液ではエタノール濃度とEtG/EtG-d5 値に相関が認められなかったが, 尿では正の相関が認められた. 次に、各事例の死亡前の行動歴から, アルコール摂取がある事例とない事例に分けて尿中の EtG をプロットしたところ, EtG/EtG-d5 値 0.60 をカットオフ値としたとき, 死亡 1 日前のアルコール摂取を証明しうる可能性が示唆された. 【考察】簡便かつ迅速なアルコール摂取の証明が可能となることで, その結果をより正確な死亡原因の調査に利用することが容易となる. また, より少量の検体で測定が可能となることで, これまで測定が不可能であったような事例においても測定が可能となる.新大博（医）第1202
口腔アセスメントシートOHATに食事・嚥下項目を追加した高齢者用口腔アセスメントシートの信頼性，有用性の検討
Get PDF新潟大学Niigata University博士（保健学）新大院博(保)第57
抹茶は肺炎球菌に対して殺菌作用および肺炎球菌由来の細胞膜傷害毒素ニューモリシンに対して阻害作用を示す
Get PDF新潟大学Niigata University博士（歯学）Abstract: Streptococcus pneumoniae is a causative pathogen of several human infectious diseases including community-acquired pneumonia. Pneumolysin (PLY), a pore-forming toxin, plays an important role in the pathogenesis of pneumococcal pneumonia. In recent years, the use of traditional natural substances for prevention has drawn attention because of the increasing antibacterial drug resistance of S. pneumoniae. According to some studies, green tea exhibits antibacterial and antitoxin activities. The polyphenols, namely the catechins epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC) are largely responsible for these activities. Although matcha green tea provides more polyphenols than green tea infusions, its relationship with pneumococcal pneumonia remains unclear. In this study, we found that treatment with 20 mg/mL matcha supernatant exhibited significant antibacterial activity against S. pneumoniae regardless of antimicrobial resistance. In addition, the matcha supernatant suppressed PLY-mediated hemolysis and cytolysis by inhibiting PLY oligomerization. Moreover, the matcha supernatant and catechins inhibited PLY-mediated neutrophil death and the release of neutrophil elastase. These findings suggest that matcha green tea reduces the virulence of S. pneumoniae in vitro and may be a promising agent for the treatment of pneumococcal infections.Sasagawa, K.; Domon, H.; Sakagami, R.; Hirayama, S.; Maekawa, T.; Isono, T.; Hiyoshi, T.; Tamura, H.; Takizawa, F.; Fukushima, Y.; et al. Matcha Green Tea Exhibits Bactericidal Activity against Streptococcus pneumoniae and Inhibits Functional Pneumolysin. Antibiotics 2021, 10, 1550. https://doi.org/10.3390/antibiotics10121550新大院博(歯)第554
