939 resultados para Anatase TiO
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Maestria en Politicas Publicas
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Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100). The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-visible diffuse spectrophotometry (UV-Vis). XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.
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Nanostructures are highly attractive for future electrical energy storage devices because they enable large surface area and short ion transport time through thin electrode layers for high power devices. Significant enhancement in power density of batteries has been achieved by nano-engineered structures, particularly anode and cathode nanostructures spatially separated far apart by a porous membrane and/or a defined electrolyte region. A self-aligned nanostructured battery fully confined within a single nanopore presents a powerful platform to determine the rate performance and cyclability limits of nanostructured storage devices. Atomic layer deposition (ALD) has enabled us to create and evaluate such structures, comprised of nanotubular electrodes and electrolyte confined within anodic aluminum oxide (AAO) nanopores. The V2O5- V2O5 symmetric nanopore battery displays exceptional power-energy performance and cyclability when tested as a massively parallel device (~2billion/cm2), each with ~1m3 volume (~1fL). Cycled between 0.2V and 1.8V, this full cell has capacity retention of 95% at 5C rate and 46% at 150C, with more than 1000 charge/discharge cycles. These results demonstrate the promise of ultrasmall, self-aligned/regular, densely packed nanobattery structures as a testbed to study ionics and electrodics at the nanoscale with various geometrical modifications and as a building block for high performance energy storage systems[1, 2]. Further increase of full cell output potential is also demonstrated in asymmetric full cell configurations with various low voltage anode materials. The asymmetric full cell nanopore batteries, comprised of V2O5 as cathode and prelithiated SnO2 or anatase phase TiO2 as anode, with integrated nanotubular metal current collectors underneath each nanotubular storage electrode, also enabled by ALD. By controlling the amount of lithium ion prelithiated into SnO2 anode, we can tune full cell output voltage in the range of 0.3V and 3V. This asymmetric nanopore battery array displays exceptional rate performance and cyclability. When cycled between 1V and 3V, it has capacity retention of approximately 73% at 200C rate compared to 1C, with only 2% capacity loss after more than 500 charge/discharge cycles. With increased full cell output potential, the asymmetric V2O5-SnO2 nanopore battery shows significantly improved energy and power density. This configuration presents a more realistic test - through its asymmetric (vs symmetric) configuration – of performance and cyclability in nanoconfined environment. This dissertation covers (1) Ultra small electrochemical storage platform design and fabrication, (2) Electron and ion transport in nanostructured electrodes inside a half cell configuration, (3) Ion transport between anode and cathode in confined nanochannels in symmetric full cells, (4) Scale up energy and power density with geometry optimization and low voltage anode materials in asymmetric full cell configurations. As a supplement, selective growth of ALD to improve graphene conductance will also be discussed[3]. References: 1. Liu, C., et al., (Invited) A Rational Design for Batteries at Nanoscale by Atomic Layer Deposition. ECS Transactions, 2015. 69(7): p. 23-30. 2. Liu, C.Y., et al., An all-in-one nanopore battery array. Nature Nanotechnology, 2014. 9(12): p. 1031-1039. 3. Liu, C., et al., Improving Graphene Conductivity through Selective Atomic Layer Deposition. ECS Transactions, 2015. 69(7): p. 133-138.
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Tese (doutorado)—Universidade de Brasília, Instituto de Geociências, Programa de Pós-Graduação em Geologia, 2015.
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Among the four commercial chestnut species the C. dentata (Marsh.) Boskh. and C. sativa P. Mill. has excellent quality but more susceptible to diseases when compared to C. mollissima Blume and C. crenata Siebold & Zucc. which has inferior quality but can be used as rootstocks. This work aimed to evaluate the behavior of chestnut varieties grafted in different rootstocks under São Bento do Sapucaí, São Paulo, Brazil condition. In 1986, eleven chestnut cultivars and hybrids - Ibuki (IB), Izumo (IZ), Kinchu (KI), KM1 (KM2), KM(2) KM(2), Moriowase (MO), Okuni (OK), Taishowase (TAI), Tamatsukuri (TAM), Tiodowase (TIO) and Senri (SEN) (only graft) ? were grafted each other resulting in hundred ten combinations. Fifteen-year later grafted trees with minimum of three plants were evaluated for tree height, trunk diameter above and below graft union and graft compatibility. Randomized blocks with three replications were submitted to analysis of variance for tree height and trunk diameter. Grouping analysis using the PROC CLUSTER ? SAS system was used to describe the pattern of variance among different combinations. Seventy eight combinations in hundred ten showed perfect grafting compatibility 6 months after grafting. Forty seven combinations showed incompatibility after transplanting and the dieback rate in each combination ranged from 25 to 100%. Among seventy eight combinations established in the field twenty six had enough plants for evaluation fifteen-year later. Tree height and trunk diameter showed highly significant difference among the combinations. The highest plant (6 m) was grafted on Moriowase and Tamatsukuri which showed the highest compatibility as rootstock. The harvesting season is from November to May where MOR, IB, TAM, OK and TAI behave as early-season-cultivar and SEN the latest one.
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Copper complexes containing inorganic ligands were loaded on a functionalized titania (F-TiO2) to obtain drug delivery systems. The as-received copper complexes and those released from titania were tested as toxic agents on different cancer cell lines. The sol–gel method was used for the synthesis and surface functionalization of the titania, as well as for loading the copper complexes, all in a single step. The resultant Cu/F-TiO2 materials were characterized by several techniques. An “in vitro” releasing test was developed using an aqueous medium. Different concentrations (15.6–1000 µg mL−1) of each copper complex, those loaded on titania (Cu/F-TiO2), functionalized titania, and cis-Pt as a reference material, were incubated on RG2, C6, U373, and B16 cancer cell lines for 24 h. The morphology of functionalized titania and the different Cu/F-TiO2 materials obtained consists of aggregated nanoparticles, which generate mesopores. The amorphous phase (in dominant proportion) and the anatase phase were the structures identified through the X-ray diffraction profiles. These results agree with high-resolution transmission electron microscopy. Theoretical studies indicate that the copper compounds were released by a Fickian diffusion mechanism. It was found that independently of the copper complex and also the cell line used, low concentrations of each copper compound were sufficient to kill almost 100 % of cancer cells. When the cancer cells were treated with increasing concentrations of the Cu/F-TiO2 materials the number of survival cells decreased. Both copper complexes alone as well as those loaded on TiO2 had higher toxic effect than cis-Pt.
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A 3D mesoporous TiO2 material with well-developed mesostructure is prepared in the form of a binder-free thin (100 nm) film and studied as potential candidate for the negative electrode in lithium microbatteries. By appropriate thermal treatments, the selected crystal structure (anatase, rutile, or amorphous), and micro-/mesostructure of the materials was obtained. The effects of voltage window and prelithiation treatment improved first cycle reversibility up to 86% and capacity retention of 90% over 100 cycles. After a prolonged intercalation of lithium ions in ordered mesoporous TiO2 appeared small particles assigned to Li2Ti2O4 with cubic structure as observed from ex-situ TEM micrographs. This study highlights the flexibility of the potential window to which the electrode can operate. Maximum capacity values over 100 cycles of 470 μA h cm−2 μm−1 and 177 μA h cm−2 μm−1 are obtained for voltage ranges of 0.1–2.6 V and 1.0–2.6 V, respectively. The observed values are between 6 and 2 times higher than those obtained for films with 600 nm (80 μA h cm−2 μm−1) and 900 nm (92 μA h cm−2 μm−1) lengths. This indicates that 100 nm thin TiO2 films with high accessibility show finite-length type diffusion which is interesting for this particular application.
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The present work seeks to investigate and discuss about the Greek Tragedy s elements at Ariano Suassuna s romance called τ Romance d A Pedra do Reino e o Principe do Sangue do Vai e Volta, connecting it directly to mythic, epic, poetic, and romances aspects at his work. The romance has as the protagonist the backcountry Pedro Dinis Quaderna. Quaderna is a character which is simultaneously popular, elitist, enigmatic, naive, and an intellectual man that has a great erudition. Quaderna is a character that seeks, by using the Literature, to reestablish a Brazilian backcountry kingdom which he s supposedly the king, always trying to empathizes the Brazilian northeast region like if it was a nation apart. By impressing a national personality to the Brazilian northeast , Quaderna tries to become an epic poet just like Homer, denoting a strong influence of the Epopee. Quaderna, just like many characters of Greek Tragedy, has at his family past time a lot of tragic circumstances. These facts that ocurred to his relativos like the your uncle Pedro Sebastião Garcia Barreto s death, the disappearement of his cousin Sinésio, and the contest between the brothers Arésio and Sinésio, and others aspects, remind us remarkable influences, beyond the Epopee, of the Greek Tragedy. By reading the romance we may notice many similarities between Quaderna s trajectory and Greek Tragedy heroes. To make an analysis about the tragic aspects at Suassuna s work, we need to dialogue with many theoreticals that have written about the tragic and comparate with many parts of Suassuna s with classics character s texts of Greek Tragedy. At the following chapters we seek to provide romance s elementaries notions, as well as tragic notions, the dialogue with mythics aspects and the tragic and epic aplicability at Suassuna s work
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Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, 2016.