Niigata University Medical and Dental Hospital
Niigata University Academic RepositoryNot a member yet
33813 research outputs found
Sort by
ナノ構造制御有機及びペロブスカイト太陽電池の表面プラズモン共鳴効果を利用した効率向上に関する研究
Get PDF新潟大学Niigata University博士（工学）Solar cells are energy harvesting technologies that capture sun light to create electron-hole pairs on the basic level to generate electricity. The specific mechanism is governed by the principle of a semiconductor pn junction diode. One of the fundamental goals in solar cell technologies is to realize optimum devices that can result in high power conversion efficiency for electricity generation in various applications. Some of this applications require light-weight thin film solar cells (in the order of nanometer to tens of micrometer) such as: stand-alone flexible electronics, semitransparent windows and many more. Such thin film solar cells are very highly transparent and usually result in most the light passing through it without full utilization to generate electricity. In this perspective, novel designs and approach in device engineering towards light manipulation for electricity generation is of significant importance in thin film solar cell applications. Such can be achieved with the incorporation of plasmonic concepts in thin film solar cells. Plasmonic concepts in solar cells make use of light and matter interactions resulting in surface plasmon resonance (SPR). Surface plasmon resonance is a phenomenon of quantized charge oscillations. These quantized charge oscillations can generate electron-hole pairs, induce polarizations in the surrounding, reradiate and couple with light to improve the overall optical properties of the entire device with the lead up towards realizing highly efficient devices. This is the focus of this dissertation. The dissertation is a culmination of studies done on controlling noble metal plasmonic nanostructures in P3HT:PC61BM, PM6:Y7 and perovskite based solar cells by utilizing surface plasmon resonance effects. The first segment in this dissertation is a study on the surface plasmon resonance synergistic coupling effects of gold nanoparticulates with silver (Ag) grating in P3HT: PC61BM-based organic solar cell. The objective was to utilize multiple plasmon coupling effects to enhance the efficiency and improve the overall performance. Gold nanrods and nanoparticles were incorporated into the active layer by varying their volume ratio concentrations to determine an optimum condition for synergistic test. The work realized an optimum efficient and stable performance device with a power conversion efficiency (PCE) of 5.43% by synergistically coupling gold nanorods in the active layer with backcontact Ag nanograting. The important findings in this study were revealing the plasmonic mechanisms behind the improvement and providing insights into the stable behavior of P3HT: PC61BM-based organic solar cell, with consideration to its glass transition temperature. The second segment of the dissertation is a study on utilizing plasmon resonance of silver nanoparticles in PM6:Y7 organic solar cell. The objective in the study was to, also, enhance the efficiency of the device. This was done by utilizing the plasmon resonance of silver nanoparticles, in the absorption deficit wavelength range of PM6:Y7 and tuning the resonance towards the absorption range of PM6:Y7. The silver nanoparticles were embedded in zinc oxide, an electron transport layer of the solar cell. The resonance tunning was done by varying the volume ratio concentration of silver nanoparticles in zinc oxide from 5% - 15%. A volume ratio concentration of 10% with silver nanoparticles demonstrated a PCE of 12.97%. Further simulations using Finite-Difference Time-Domain (FDTD) revealed localized surface plasmon resonance (LSPR) fields in the forward direction coupling well with the PM6:Y7 layer for smooth electronic charge extraction across the interface. The study provides an insight on the importance of plasmonic effects in PM6:Y7 organic solar cell. The third segment in the dissertation is a continuation of the study done on PM6:Y7 organic solar cell by optimizing the plain device. The study employed temperature-variation approach to optimize the active layer, resulting in a PCE of 17.36%. The fourth segment in the dissertation is a study on the behavior of the SPR of silver nanoparticles embedded in titanium dioxide, an electron transport layer of the standard perovskite solar cell, to further improve a plain device which demonstrated a PCE of 13.65%.新大院博(工)第564
Proposal of a Human-powered Walking Assist Mechanism and Verification of Walking Motion
Get PDF新潟大学Niigata University博士（工学）新大院博(工)第554
新潟大学医歯学総合病院においてPNAM治療を行った片側性口唇口蓋裂児における外鼻形態変化の長期的評価と治療効果に影響を与える因子について
Get PDF新潟大学Niigata University博士（歯学）新大院博(歯)第559
Aeromonas salmonicidaのCsrシステムの同定とその制御機構に関する研究
Get PDF新潟大学Niigata University博士（学術）The Csr (Carbon Storage Regulator) system is a conserved regulatory network affecting multiple cellular processes. It consists of CsrB/C small RNAs, CsrA and CsrD proteins. An RNA–binding CsrA protein is involved in post-transcriptional regulation of target transcripts. Its primary function is to bind an mRNA by GGA motif. As GGA motifs are frequently part of a ribosome binding site, CsrA attachment prevents ribosome from binding which results in downregulation of a target gene and faster mRNA degradation (Babitzke and Romeo, 2007). On the other hand, positive regulation is possible as well. Wei et. al. show that CsrA stabilizes flhDC transcript. In turn, CsrB/C small noncoding RNAs possess many GGA motifs and can bind several CsrA proteins at once (Babitzke and Romeo, 2007; Weilbacher et al., 2003). So that CsrA protein function is diminished. CsrD protein works otherwise. CsrD regulates turnover of CsrB/C sRNAs, setting free CsrA proteins (Suzuki et al., 2006). In this research, we used Aeromonas salmonicida strain SWSY-1.411 which was isolated from a freshwater lake Sakata, Niigata (Tran et al., 2018). For gene identification, primers were designed using available genome sequences of closest strains in BLAST system. All the amplified PCR products were cloned and sequenced. Csr system components of the newly identified A. salmonicida SWSY-1.411 were found and compared with Escherichia coli. The highest identity between components is found in CsrA protein and the lowest percentage of identity showed CsrD. Cloning of A. salmonicida SWSY-1.411 Csr system components in E. coli, including analysis of the expressed genes, revealed that CsrA protein and CsrB/C sRNAs perform the same functions as it was first found in E. coli. A. salmonicida CsrA inhibited glycogen accumulation and biofilm formation in E. coli. But on the contrary, A. salmonicida CsrB/C promoted glycogen accumulation and biofilm formation in E. coli. A. salmonicida CsrD inhibited glycogen accumulation and biofilm formation in E. coli (Yoshida et al., 2022). A. salmonicida SWSY-1.411 mutans, deprived of one or two of the components (csrA, csrB, csrC, csrB/C, csrD), were constructed and phenotypic analysis was performed. The effects of this system on biofilm formation, glycogen biosynthesis, protease activity, chitinase activity in solid and liquid media, motility measurement were explored. Flagella-related genes were sequenced in A. salmonicida SWSY-1.411. Csr system of A. salmonicida SWSY-1.411 had an effect on biofilm formation, motility and chitinase activity. As for glycogen accumulation and protease activity, no effects were observed. Csr system of A. salmonicida showed the greatest effect on motility, so it’s suggested that motility is a target. Further analysis included gene expression assay and RNA decay analysis carrying out RT-PCR, new mutants design and Northern Blotting. We assessed expression of flagellar genes (fliA, flrA, flrBC, motD, pomA) and chitinase genes (chiA, chiB, chiC, chiD, lpmo10A). Our results show that CsrA decreases expression of RNA-sigma factor fliA, master – regulators flrA and flrBC, chitinases chiA and chiB. Assuming that motility is a target of Csr system in A. salmonicida we designed △flrA and △flrC mutants. Motility analysis on plate showed that in the absence of flrA gene mutant shows no motility as well as csrA mutant, but deletion of flrC doesn’t have an inhibitory effect. CsrD is known for participation in CsrB and CsrC RNA decay in E. coli. The domains structure of E. coli CsrD protein includes GGDEF and EAL domains with HRSDF and ELM motifs. GGDEF- and EAL-domain containing proteins have been shown to contain GGDEF and EAL motifs respectively. As a rule, such proteins participate in synthesis (via GGDEF domain with diguanylate cyclase activity) and degradation of c-di-GMP (via EAL domain with c-di-GMP phosphodiesterase activity). But CsrD protein has been shown to regulate degradation of CsrB and CsrC small RNAs only. It was established that in the absence of csrD, half-lives of CsrB and CsrC last more than 30 minutes. In wild type E. coli these non-coding RNAs degrade in about one minute. We measured half-lives of CsrB and CsrC as well as analyzed CsrD domain structure and amino acid sequences among various bacterial strains. Our data show that half-lives of wild type CsrB and CsrC are 2.2 and 3.7 minutes correspondingly. In csrD mutant small RNAs remain stable for more than 6 minutes. A. salmonicida SWSY-1.411 CsrD shows characteristic domain structure having GGDEF and EAL domains like in E. coli. In spite of A. salmonicida SWSY-1.411 CsrD having GGDEF and EAL domains the motifs were AGQVF and DDL respectively. So we suggested that CsrD of A. salmonicida SWSY-1.411 takes part in CsrB and CsrC degradation only as in E. coli. Comparison of CsrD amino acid sequence among Enterobacteriaceae, Vibrionaceae resulted in identification of conserved amino acid residues namely L168, R171, I175, L199, R215, I220, I221, T230, N234, L242, E519 which were conserved in A. salmonicida CsrD. So, in course of this research we not only identified Csr system components of A. salmonicida SWSY-1.411, compared them to the ones in E. coli and analyzed phenotypic traits. But also checked expression of chitinase and flagellar-related genes, examined role of CsrD by measuring half-lives of CsrB/CsrC, compared CsrD domain structures and amino acid sequences.新大院博(学)第229
光コヒーレンストモグラフィ向け音響光学デバイス駆動型波数線形走査光源
Get PDF新潟大学Niigata University博士（工学）Optical coherence tomography (OCT) is a non-invasive, non-contact optical imaging modality for assessing internal microstructure of samples. Over three decades, OCT, has combined with a variety of other approaches to continuously stimulated research and development within this field. Especially, the swept source OCT (SS-OCT) employing a swept source has attracted great attention due to its large imaging depth and high imaging speed. Since the characteristics of swept sources affect performances of OCT systems, it is necessary to develop an advanced swept source, including broad spectral bandwidth, narrow instantaneous linewidth, and high scanning speed, etc. The linear-wavenumber swept source is a specifically important characteristic because it ensures that the optical interference fringe is in linearized wavenumber space before the fast Fourier transformation in an SS-OCT system. However, most swept sources follow a linearized wavelength scale. When using such a wavelength-swept source, an additional procedure of resampling and interpolating the optical interference fringe evenly in wavenumber space becomes necessary; otherwise, reconstruction errors and resolution degradation is inevitable in OCT imaging. To address this problem, this thesis developed a linear-wavenumber swept source for the OCT system. The linear-wavenumber swept source shows strong linearity in the 1.3 μm region, justified by a high goodness of fit R2 value of 0.9998. Additionally, its scanning range, output power, and linewidth are 120 nm, more than 43 mW, and approximately 0.6 nm, respectively. The sweep rate is 350 Hz after the linear wavenumber compensation of the experimental equipment. We proved the effectiveness of the linear-wavenumber swept source by applying it to measure a sample distribution without wavenumber-domain resampling before the Fourier transform. This successful implementation indicates that the linear-wavenumber swept source has practical potential for application in SS-OCT systems.新大院博(工)第553