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Carcinogen-induced DNA base modification and subsequent DNA lesions are the critical events for the expression of premalignant phenotype of the cell. We have therefore investigated the chemopreventive efficacy of a vanadium salt against diethylnitrosamine (DEN)-induced early DNA and chromosomal damages in rat liver. Hepatocarcinogenesis was induced in male Sprague-Dawley rats with a single, necrogenic, intraperitoneal injection of DEN (200 mg/kg body weight). 8-Hydroxy-2′-deoxyguanosines (8-OHdGs), strand-breaks and DNA-protein crosslinks (DPCs) were measured by HPLC, comet assay and spectrofluorimetry, respectively. There was a significant and steady elevation of modified bases 8-OHdGs along with substantial increments of the extent of single-strand-breaks (SSBs), DPCs and chromosomal aberrations (CAs) following DEN exposure. Supplementation of vanadium as ammonium metavanadate (NH4VO3, +V oxidation state) at a dose of 0.5 ppm in terms of the salt weight throughout the experiment abated the formations of 8-OHdGs (P < 0.0001; 79.54%), tailed DNA (P < 0.05; 31.55%) and length:width of DNA mass (P < 0.02; 61.25%) in preneoplastic rat liver. Vanadium treatment also inhibited DPCs (P < 0.0001; 58.47%) and CAs (P < 0.001; 45.17%) studied at various time points. The results indicate that the anticlastogenic potential of vanadium in vivo might be due to the observed reductions in liver-specific 8-OHdGs, SSBs and/or DPCs by this trace metal. We conclude that, vanadium plays a significant role in limiting DEN-induced genotoxicity and clastogenicity during the early stages of hepatocarcinogenesis in rats.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20368号 / 工博第4305号 / 新制||工||1667(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 乾 晴行, 教授 邑瀬 邦明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Vanadin är en värdefull metall och kan lakas ur LD (Linz-Donawitz)-slagg med hjälp av vin. Ligander i vinet som lakar vanadin från LD-slagg studerades i denna rapport med mål att identifiera några av deras egenskaper såsom apparent molekylmassa och spektral information. Hyfenerad analys med hjälp av högupplösande vätskekromatografi-mikrovågsplasma med atomemissionspektrometer (HPLC-MP-AES) gjordes för att matcha vanadintoppen från vinet med ett apparent masspann från en gelfiltreringskolonn. Spektral analys visade att det fanns tre misstänkta vanadinligander i det analyserade vinet. Apparent molekylmassa hos liganderna var sannolikt inom spannet 24 Da – 570 Da. / Vanadium is a valuable metal and can be extracted from Linz-Donawitz (LD) converter slag using wine. Ligands in wine responsible for leaching vanadium from LD converter slag were studied in this report in an effort to identify some of their properties such as apparent molecular mass and spectral information. Hyphenated analysis using high performance liquid chromatography-microwave plasma atomic emission spectroscopy (HPLC-MP-AES) was performed to match a vanadium peak from the wine with an apparent mass span from a size exclusion chromatography (SEC) column. Spectral analysis of the vanadium peak revealed that there were three compounds suspected to be ligands to vanadium in the wine analyzed. Apparent molecular mass of the ligands wasfound to likely be between 24 Da - 570 Da.

Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) layer. Scanning electron microscopy (SEM) and electron-backscattered diffraction (EBSD) were utilized to study the morphology of the solid phase crystallization that resulted from this post-deposition annealing process. The annealing parameters ranged in temperature from 300°C up to 1000°C and in time from 5 minutes up to 12 hours. Depending on the annealing parameters, EBSD showed that this process yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. In addition to these films on SiO_2, other VO_2 thin films were deposited onto a-, c-, and r-cuts of sapphire and on TiO_2(001) heated single-crystal substrates by pulsed-laser deposition (PLD). The temperature of the substrates was kept at ~500°C during deposition. EBSD maps and orientation imaging microscopy were used to study the epitaxy and orientation of the VO_2 grains deposited on the single crystal substrates, as well as on the amorphous SiO_2 layer. The EBSD/OIM results showed that: 1) For all the sapphire substrates analyzed, there is a predominant family of crystallographic relationships wherein the rutile VO_2{001} planes tend to lie parallel to the sapphire's {10-10} and the rutile VO_2{100} planes lie parallel to the sapphire's {1-210} and {0001}. Furthermore, while this family of relationships accounts for the majority of the VO_2 grains observed, due to the sapphire substrate's geometry there were variations within these rules that changed the orientation of VO_2 grains with respect to the substrate's normal direction. 2) For the TiO_2, a substrate with a lower lattice mismatch, we observe the expected relationship where the rutile VO_2 [100], [110], and [001] crystal directions lie parallel to the TiO_2 substrate's [100], [110], and [001] crystal directions respectively. 3) For the amorphous SiO_2 layer, all VO_2 crystals that were measurable (those that grew to the thickness of the deposited film) had a preferred orientation with the the rutile VO_2[001] crystal direction tending to lie parallel to the plane of the specimen. The use of transmission electron microscopy (TEM) is presented as a tool for further characterization studies of this material and its applications. In this work TEM diffraction patterns taken from cross-sections of particles of the a- and r-cut sapphire substrates not only solidified the predominant family mentioned, but also helped lift the ambiguity present in the rutile VO_2{100} axes. Finally, a focused-ion beam technique for preparation of cross-sectional TEM samples of metallic thin films deposited on polymer substrates is demonstrated.

X-ray diffraction (XRD) patterns, electron probe microanalysis(EPMA), electron paramagnetic resonance (EPR) powder spectra (9 and 34 GHz) and the magnetic susceptibility of BaTiO3 + 0.04 BaO + 0.01 V2O5 ceramics were studied to investigate the valence states of V ions and their solubility in the BaTiO3 lattice. In samples sintered at 1400 °C in air, only about 0.1 mol% V is incorporated in the BaTiO3 lattice being in V4+ and V5+ valence state, respectively. 95% of the nominal V dopant content occurs in the secondary phase Ba3(V/Ti)2O8. All BaTiO3 samples investigated are in tetragonal phase at room temperature. In the as-sintered samples V4+ is detected at temperatures T < 20 K by its hyperfine structure (HFS) octet due to the nuclear spin 7/2 of 51V. Samples post annealed in H2/Ar atmosphere at 1200 °C exhibit a further HFS octet occurring at T > 25 K and vanishing at T > 250 K, which is caused by V2+ ions. This spectrum is characterized by a simultaneous HFS and fine structure splitting constituted by allowed and forbidden transitions. Both V4+ and V2+ ions are incorporated at Ti4+ sites of the BaTiO3 lattice

Advanced dispersants were discovered for the fabrication of homogeneous suspensions of multi-walled carbon nanotubes (MWCNT), graphene, and manganese dioxide (MnO2) in both ethanol and water. Thin films of MWCNT, graphene, MnO2, composite films of MWCNT-MnO2 and MWCNT-graphene were prepared using electrophoretic deposition (EPD) and electrolytic deposition (ELD) methods. The mechanisms of dispersion and deposition were investigated. Cathodic EPD was achieved for MWCNT and graphene using positively charged dispersants. Co-deposition of MWCNT and MnO¬2 was performed using a co-dispersant, which dispersed both MWCNT and MnO2 in ethanol. Composite films were tested for electrochemical supercapacitor (ES) purposes. Pulse ELD was used to deposit porous MnO2 coatings on Ni foam substrates from KMnO4 solutions. Cathodic deposition offered advantages, compared to anodic deposition, because the problems, related to anodic dissolution of metallic substrates, can be avoided. The pulse ON/OFF times had significant influence on the morphology and structure of MnO2 films, which further determined the capacitive performance. The influence of MnO2 film thickness on specific capacitance was investigated. Porous and conductive vanadium nitride (VN) was synthesized using melamine as a reducing agent. To further improve film conductivity and specific surface area, MWCNT were incorporated into VN matrix during synthesis. VN-MWCNT composite electrodes and VN-MWCNT/MnO2-MWCNT asymmetric supercapacitor cells were fabricated and tested. The electrodes and cells exhibited excellent electrochemical capacitive performance with good cyclic stability. The asymmetric supercapacitor device showed a voltage window up to 1.8 V, which was the combination of voltage window of VN-MWCNT (-0.9 V--0 V) and MnO2-MWCNT (0 V--0.9 V). Polypyrrole (PPy) coated MWCNT were synthesized in ethanol with ammonium peroxydisulfate solution as an oxidant. The effects of dopants to PPy morphology and conductivity was investigated. Dopants with electrochemical active groups were selected for the synthesis of PPy nanoparticles, where dopants also contributed to the capacitance of the polymer based materials. Both PPy-MWCNT/PPY-MWCNT symmetric supercapacitors and VN-MWCNT/PPY-MWCNT asymmetric supercapacitors were fabricated and tested, where the voltage windows were 0.9 V for the former and 1.3 V for the later. The increase of voltage window was ascribed to the asymmetric structure and negative voltage window of VN-MWCNT composite. / Thesis / Doctor of Philosophy (PhD)

<p> Iron-vanadium alloys were levitation melted and equilibrated at controlled temperatures with water vapour/hydrogen atmospheres of controlled composition, quenched and analysed for oxygen. The effect of vanadium on the behaviour of oxygen has been expressed in terms of first order free energy, enthalpy and entropy interaction parameters. </p> <p> The reduction of phosphorus from synthetic blast furnace slags by carbon saturated iron was studied under laboratory conditions. The rate of phosphorus transfer was determined and the results have been interpreted in terms of chemical reaction control at the slag/metal interface. </p> <p> The dephosphorisation of induction melted mild steel by synthetic basic slags was investigated. The rate of dephosphorisation was determined and the results have been interpreted in terms of mass transfer control in the slag phase. </p> / Thesis / Doctor of Philosophy (PhD)

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