>Magister Scientiae - MSc / Nanotechnology is a rapidly growing field of research. Due to major innovations brought about by developments in nanotech, several consumer products are currently available containing nanomaterials. The increase of nanomaterial production and use is accompanied by the increased potential of human, plant and animal exposure to these nanomaterials. As a relatively new nanomaterial, carbon quantum dots (CQDs) are being extensively used and researched due to its unique properties. Although many studies have assessed the toxic potential of CQDs, and found them to exhibit low toxicity, there is lack of work assessing the effects on the immune system. In the present study, RAW 264.7 murine macrophages were used as model to assess the immunomodulatory potential of CQDs. RAW cells exposed to varying concentrations of CQDs (0-500μg/ml), showed that CQDs caused a reduction at cell viability. In the absence of a mitogen CQDs, induced an inflammatory response by stimulating the release of various cytokines and chemokines such as, TNFα, MIP-1α, MIP-1β, MIP-2, IP-10, G-CSF, GM-CSF, and JE.

>Magister Scientiae - MSc / The interest in carbon-based nanomaterials, such as carbon-nanodots and graphene, has grown exponentially because these materials have unique properties and applications in the medical, electronic, clean energy and several other fields for biochemical sensing, energy conversion, photocatalysis, optoelectronics, etc. Carbon dots were discovered in 2004, yet very little research has been done on the colloidal stability thereof. Nanomaterials such as carbon dots will inescapably make their way to natural waters with an unknown environmental fate. Therefore, it is of great importance to understand the behaviour of carbon dots under the influence of certain environmental conditions such as pH, ionic strength, and in the presence of natural organic matter. / 2022

Nowadays, nanoscale zerovalent iron (nZVI) is a nanomaterial commonly used in remediation practice. Although worldwide applications of nZVI have shown its effectiveness in degradation and immobilization of a wide range of organic and inorganic pollutants, potential negative effects of nZVI on exposed organisms have not been sufficiently explored. To avoid possible environmental risks, understanding of the mechanism of nZVI toxicity and its overall effects on microbial populations indigenous to remediation sites is needed. The presented thesis summarizes current knowledge of nZVI toxicity, and, moreover, deals with the development and application of a new test for in vitro evaluation of acute toxicity caused by newly developed nZVI-based materials. Additionally, in this thesis, the risk associated with changes in the toxicity of the aforementioned materials during the aging process was examined. In the last part, the effect of several nZVI-based materials on microbial communities of a real contaminated soil was monitored and evaluated using artificial microcosms. In addition, in this part, the potential of nZVI and its derived materials in combination with a biostimulation step during nanobioremediation is outlined.

<p>  </p> <p>In this study, VO2 films were grown on conducting oxide SrRuO3 layers. Apart from applications in magnetism, SrRuO3 is a widely studied template material to create multi-functional oxide heterostructures. Here, SrRuO3 buffered SrTiO3 (111) and Si/SiO2 were selected as platforms for VO2 growth. The properties of VO2 thin films grown on SrRuO3 buffer layers, as well as thermally and electric-field induced metal-insulator transition were systematically studied. Numerous growth experiments were conducted to identify the optimal growth conditions. Utilizing the current shunting associated with the conductive underlayer, electric-field induced metal-insulator transition was investigated in both the in-plane and out-of-plane configurations. A distributed resistance network with general applicability to understanding metal-insulator transitions is proposed to predict the electrical behavior of VO2 grown on conducting layers.</p>

This work involves synthesis and characterization of isotropic and anisotropic noble metal nanoparticles for applications ranging from antimicrobial uses to anticancer applications. These nanomaterials are stabilized in genuinely benign biomaterials ranging from polymers to cross linked proteins for targeted cancer treatments. The nanoparticles are found to have tunable optical properties.

The thesis is focused on the physics of magnetic nanoparticles (NPs), starting from the solution of magnetic structure, internal alignment within the single particle and role of interactions and particle structure in magnetic response of systems of the NPs. Moreover, the macroscopic arrangement of the NPs and its effect on the properties of system containing the NPs are discussed. The work brings several new results and concepts, such as the solution of magnetic structure of the ε-Fe2O3 phase, methods of proper detection and description of magnetic metal catalyst in carbon nanotubes and role of the NP arrangement and their effect on graphene placed on the top of substrates decorated with the NPs. 1

Indiana University-Purdue University Indianapolis (IUPUI) / Electrospinning has gained immense interests in recent years due to its potential application in various fields, including energy storage application. The V2O5/GO as a layered crystal structure has been demonstrated to fabricate nanofibers with diameters within a range of ~300nm through electrospinning technique. The porous, hollow, and interconnected nanostructures were produced by electrospinning formed by polymers such as Polyvinylpyrrolidone (PVP) and Polyvinyl alcohol (PVA), separately, as solvent polymers with electrospinning technique. In this study, we investigated the synthesis of a graphene-modified nanostructured V2O5 through modified sol-gel method and electrospinning of V2O5/GO hybrid. Electrochemical characterization was performed by utilizing Arbin Battery cycler, Field Emission Scanning Electron Microscopy (FESEM), X-ray powder diffraction (XRD), Thermogravimetric analysis (TGA), Mercury Porosimetry, and BET surface area measurement. As compared to the other conventional fabrication methods, our optimized sol-gel method, followed by the electrospinning of the cathode material achieved a high initial capacity of 342 mAh/g at a high current density of 0.5C (171 mA/g) and the capacity retention of 80% after 20 cycles. Also, the prepared sol-gel method outperforms the pure V2O5 cathode material, by obtaining the capacity almost two times higher. The results of this study showed that post-synthesis treatment of cathode material plays a prominent role in electrochemical performance of the nanostructured vanadium oxides. By controlling the annealing and drying steps, and time, a small amount of pyrolysis carbon can be retained, which improves the conductivity of the V2O5 nanorods. Also, controlled post-synthesis helped us to prevent aggregation of electro-spun twisted nanostructured fibers which deteriorates the lithium diffusion process during charge/discharge of batteries.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19096号 / エネ博第320号 / 新制||エネ||65(附属図書館) / 32047 / 京都大学大学院エネルギー科学研究科エネルギー応用科学専攻 / (主査)教授 松田 一成, 教授 岸本 泰明, 教授 大垣 英明 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

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