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Hydrogen peroxide monitoring in Fenton reaction by using a ruthenium oxide hexacyanoferrate/multiwalled carbon nanotubes modified electrode

Pena, Roselyn C.; Silva, Volnir O.; Quina, Frank Herbert; Bertotti, Mauro
Fonte: ELSEVIER SCIENCE SA; LAUSANNE Publicador: ELSEVIER SCIENCE SA; LAUSANNE
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.02%
A novel amperometric sensor based on the incorporation of ruthenium oxide hexacyanoferrate (RuOHCF) into multiwalled carbon nanotubes (MWCNTs) immobilized on a glassy carbon electrode is described. Cyclic voltammetry experiments indicated that the cathodic reduction of hydrogen peroxide at the RuOHCF/MWCNTs100/GC modified electrode is facilitated, occurring at 0.0 V vs. Ag/AgCl/KCl(sat). Following the optimization of the experimental conditions, the proposed sensor presented excellent analytical properties for hydrogen peroxide determination, with a low limit of detection (4.7 mu mol L-1), a large dynamic concentration range (0.1-10 mmol L-1) and a sensitivity of 1280 mu A mmol(-1) L cm(-2). The usefulness of the RuOHCF/MWCNTs100/GC electrochemical sensor was confirmed by monitoring the consumption of hydrogen peroxide during the degradation of phenol by the Fenton reaction. (C) 2012 Elsevier B.V. All rights reserved.; Fundacao de Amparo a Pesquisa de Sao Paulo (FAPESP); FAPESP (Fundacao de Amparo a Pesquisa de Sao Paulo); CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)

"Transferência de carga e ligação de hidrogênio intramolecular em derivados de 9-aminoacridina"; "Intramolecular charge and hydrogen bon transfer in 9-aminoacridine derivatives"

Pereira, Robson Valentim
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/08/2006 PT
Relevância na Pesquisa
35.88%
Neste trabalho, o corante 9-aminoacridina foi derivatizado com compostos vinílicos que possuem grupos retiradores de elétrons. A incorporação destes leva à mudanças nas propriedades fotofísicas dos derivados, tais como deslocamentos para regiões de menor energia nos espectros de absorção e emissão, sugerindo a presença de transferência de carga intramolecular (ICT). Os estudos de fluorescência resolvida no tempo confirmam este processo para os derivados. Este estado ICT possui um tempo formação na faixa de 150 – 300 ps e um tempo de vida entre 1 – 3 ns, que depende do solvente. Os derivados que apresentam pelo menos um grupo carbonila como retirador de elétron, possuem um tempo de vida longo na faixa de 8 –10 ns, atribuído à emissão do enol, formado a partir da conjugação estendida por ponte de hidrogênio. A polimerização destes derivados com o ácido metacrílico promoveram mudanças em suas propriedades fotofísicas estacionárias e resolvidas no tempo devido à quebra da conjugação  estendida. Este fato é ilustrado pelos espectros de absorção e emissão que mostram bandas estruturadas, deslocadas para a região de maior energia e um decaimento monoexponencial, semelhante ao observado com 9-aminoacridina. Anisotropia de fluorescência resolvida no tempo mostra que nos copolímeros o tempo de relaxação rotacional do corante é muito sensível à mudança conformacional do poli (ácido metacrílico) com o pH...

Estudo de síntese de catalisadores de níquel suportados em alumina-lantânia para aplicação na produção de hidrogênio a partir da reforma a vapor do etanol; Synthesis study of alumina-lanthana supported nickel catalysts for hydrogen production by ethanol steam reforming

Cordeiro, Guilherme Luís
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/02/2015 PT
Relevância na Pesquisa
36.06%
O uso do hidrogênio, como vetor energético, representa uma opção promissora a fim de se reduzir a dependência dos combustíveis fósseis e controlar a emissão de poluentes na atmosfera. Atualmente, uma das rotas mais propícias para produção de hidrogênio envolve a reação de reforma a vapor de álcoois utilizando-se catalisadores de níquel suportados em alumina. O níquel é amplamente utilizado em catálise devido ao baixo custo e à elevada atividade para ruptura da ligação C-C. A alumina, por sua vez, promove maior dispersão do metal ativo devido aos valores elevados de área superficial das estruturas cristalinas de transição, sobretudo da fase gama, característica esta diretamente relacionada às condições de síntese. A incorporação de lantânia, como aditivo, tem sido considerada por moderar a acidez da superfície do suporte e minimizar a deposição de carbono no catalisador durante a reação de reforma. Tendo em vista que a atividade dos catalisadores na reação de reforma é função das características físicas e químicas desses materiais, avaliou-se, no presente trabalho, a rota de síntese por coprecipitação de hidróxidos em associação ao uso de surfactante e tratamento solvotérmico. A rota de mistura de pós de óxido de níquel com alumina...

Hydrogen influence on gallium arsenide thin films prepared by rf-magnetron sputtering technique

Vilcarromero, J.; Bustamante, R.; da Silva, J. H. D.
Fonte: Sociedade Brasileira Fisica Publicador: Sociedade Brasileira Fisica
Tipo: Artigo de Revista Científica Formato: 1035-1037
ENG
Relevância na Pesquisa
46.18%
We investigate the effect of the hydrogen intentional incorporation on the structural properties of the amorphous gallium arsenide prepared by rf-magnetron sputtering technique. The properties of the non-hydrogenated films are: band gap of 1.4 eV (E-04), Urbach energy of 110 meV, stoichiometric composition ([As]/[Ga] = 0.50), and dark conductivity of about 3.2 x 10(-5) (Omega.cm)(-1). Hydrogen was incorporated in the films by the introduction of an electronically controlled H-2 flux during deposition, keeping constant the other deposition parameters. It was observed that small hydrogen incorporation produces a great change in the structural properties of the films. The main changes result from the formation of GaAs nanocrystals with mean sizes of about 7 nm into the amorphous network.

Analysis of agonist and antagonist effects on thyroid hormone receptor conformation by hydrogen/deuterium exchange

Figueira, A. C M; Saidemberg, D. M.; Souza, P. C T; Martínez, L.; Scanlan, T. S.; Baxter, J. D.; Skaf, M. S.; Palma, Mario Sergio; Webb, P.; Polikarpov, I.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 15-31
ENG
Relevância na Pesquisa
36.02%
Thyroid hormone receptors (TRs) are ligand-gated transcription factors with critical roles in development and metabolism. Although x-ray structures of TR ligand-binding domains (LBDs) with agonists are available, comparable structures without ligand (apo-TR) or with antagonists are not. It remains important to understand apo-LBD conformation and the way that it rearranges with ligands to develop better TR pharmaceuticals. In this study, we conducted hydrogen/deuterium exchange on TR LBDs with or without agonist (T 3) or antagonist (NH3). Both ligands reduce deuterium incorporation into LBD amide hydrogens, implying tighter overall folding of the domain. As predicted, mass spectroscopic analysis of individual proteolytic peptides after hydrogen/ deuterium exchange reveals that ligand increases the degree of solvent protection of regions close to the buried ligand-binding pocket. However, there is also extensive ligand protection of other regions, including the dimer surface at H10-H11, providing evidence for allosteric communication between the ligand-binding pocket and distant interaction surfaces. Surprisingly, Cterminal activation helix H12, which is known to alter position with ligand, remains relatively protected from solvent in all conditions suggesting that it is packed against the LBD irrespective of the presence or type of ligand. T 3...

Graphene to fluorographene and fluorographane: A theoretical study

Paupitz, R.; Autreto, P. A S; Legoas, S. B.; Srinivasan, S Goverapet; Van Duin, A. C T; Galvão, D. S.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.28%
We report here a fully reactive molecular dynamics study on the structural and dynamical aspects of the fluorination of graphene membranes (fluorographene). Our results show that fluorination tends to produce defective areas on the graphene membranes with significant distortions of carbon-carbon bonds. Depending on the amount of incorporated fluorine atoms, large membrane holes were observed due to carbon atom losses. These results may explain the broad distribution of the structural lattice parameter values experimentally observed. We have also investigated the effects of mixing hydrogen and fluorine atoms on the graphene functionalization. Our results show that, when in small amounts, the presence of hydrogen atoms produces a significant decrease in the rate of fluorine incorporation onto the membrane. On the other hand, when fluorine is the minority element, it produces a significant catalytic effect on the rate of hydrogen incorporation. We have also observed the spontaneous formation of new hybrid structures with different stable configurations (chair-like, zigzag-like and boat-like) which we named fluorographane. © 2013 IOP Publishing Ltd.

Incorporation of hydrogen production process in a sugar cane industry: Steam reforming of ethanol

Silveira, Jose Luz; Martinelli, Valdisley Jose; Vane, Lucas Fachini; Freire Junior, Jose Celso; Zanzi Vigouroux, Rolando A.; Tuna, Celso Eduardo; Lamas, Wendell de Queiroz; Silva Paulino, Regina Francielle
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 94-103
ENG
Relevância na Pesquisa
36.25%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); This work presents a technical, ecological and economic analysis of hydrogen production incorporation through ethanol steam reforming at a traditional sugarcane industry (sugar, ethanol). This proposal is reached through a reduction in the amount of fuel (bagasse) that is normally utilized to generate electricity without affecting the sugar and ethanol production processes, however. This surplus bagasse is utilized to produce steam for hydrogen production. In order to achieve this, it is calculated the available bagasse and maximum hydrogen amount and their inputs (hydrated and anhydrous ethanol). Based on the aforementioned, the investment needs are estimated, where the operation and maintenance cost, the operation period, the interest rate, and the annuity are considered. The incorporation of this new process is assessed through a comparison of this innovative plant with the traditional ones. (C) 2014 Elsevier Ltd. All rights reserved.

Sequential injection lab-on-valve system for the on-line monitoring of hydrogen peroxide in lens care solutions

Vidigal, Susana S.M.P.; Tóth, Ildikó V.; Rangel, António O.S.S.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
Relevância na Pesquisa
36.05%
A sequential injection lab-on valve (SI-LOV) method for the enzymatic determination of hydrogen peroxide was developed. The spectrophotometric assay is based on the reaction between hydrogen peroxide and ABTS (2,2′-Azino-bis(3-Ethylbenzothiazoline 6-sulfonic acid)) in the presence of the enzyme HRP (horseradish peroxidase). The produced oxidized ABTS is measured at 410 nm. The sample consumption was 15 μL/assay and the consumption of HRP and ABTS was 34.6 mg L−1 and 0.06 g L−1, respectively with a determination rate of 45 h−1. Relative deviations lower than 9.0% were found when the results were compared to those obtained by the reference procedure in the analysis of bleaches and disinfection solutions for contact lenses. With the incorporation of an in-line dilution (dialysis) process,was possible to attain a response range up to 342 mg L−1 of hydrogen peroxide. The developed methodwas applied to monitor on-line of the disinfection–neutralization process of contact lenses. The study of two different one-step systems for cleaning contact lenses demonstrated that the neutralization of the hydrogen peroxide is completed within 6 h as recommended by the manufactures. The developed flow method was proved to be a useful tool for monitoring the dynamic process of disinfection–neutralization.

Preparation and immobilization of diNOsarcobalt(III) complex in zeolite y for the catalyzed production of hydrogen peroxide

Carriazo,José G.; Montoya-González,Efraín A.; Vanoy-Villamil,Michael N.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
35.95%
A complex cation, diNOsarcobalt(III), [Co(diNOsar)]3+, (diNOsar = 1,8-dinitro-3,6,10,13,16,19-hexaazabicyclo-[6.6.6]eicosane), was synthesized and immobilized in the cavities of a Y zeolite by the reaction of precursor species in the pores of the zeolite. The encapsulated material was compared to the compound diNOsarcobalt(III) chloride, [Co(diNOsar)]Cl3. Both diNOsarcobalt(III) chloride and the zeolite-encapsulated complex, [Co(diNOsar)]3+/zeolite, were obtained in high yield and characterized by ultraviolet-visible and infrared spectroscopy. X-ray diffraction demonstrated the incorporation of the complex cation into the pores of the zeolite. The catalytic production of hydrogen peroxide from oxygenated water confirmed the successful synthesis of the complex diNOsarcobalt(III) immobilized in the zeolite.

Hydrogen influence on gallium arsenide thin films prepared by rf-magnetron sputtering technique

Vilcarromero,J.; Bustamante,R.; Silva,J.H.D. da
Fonte: Sociedade Brasileira de Física Publicador: Sociedade Brasileira de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2006 EN
Relevância na Pesquisa
46.18%
We investigate the effect of the hydrogen intentional incorporation on the structural properties of the amorphous gallium arsenide prepared by rf-magnetron sputtering technique. The properties of the non-hydrogenated films are: band gap of 1.4 eV (E04), Urbach energy of 110 meV, stoichiometric composition ([As]/[Ga] = 0.50), and dark conductivity of about 3.2 x 10-5 (omega.cm)-1. Hydrogen was incorporated in the films by the introduction of an electronically controlled H2 flux during deposition, keeping constant the other deposition parameters. It was observed that small hydrogen incorporation produces a great change in the structural properties of the films. The main changes result from the formation of GaAs nanocrystals with mean sizes of about 7 nm into the amorphous network.

Role of Hoogsteen Edge Hydrogen Bonding at Template Purines in Nucleotide Incorporation by Human DNA Polymerase ι

Johnson, Robert E.; Haracska, Lajos; Prakash, Louise; Prakash, Satya
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /09/2006 EN
Relevância na Pesquisa
26.41%
Human DNA polymerase ι (Pol ι) differs from other DNA polymerases in that it exhibits a marked template specificity, being more efficient and accurate opposite template purines than opposite pyrimidines. The crystal structures of Pol ι with template A and incoming dTTP and with template G and incoming dCTP have revealed that in the Pol ι active site, the templating purine adopts a syn conformation and forms a Hoogsteen base pair with the incoming pyrimidine which remains in the anti conformation. By using 2-aminopurine and purine as the templating residues, which retain the normal N7 position but lack the N6 of an A or the O6 of a G, here we provide evidence that whereas hydrogen bonding at N6 is dispensable for the proficient incorporation of a T opposite template A, hydrogen bonding at O6 is a prerequisite for C incorporation opposite template G. To further analyze the contributions of O6 and N7 hydrogen bonding to DNA synthesis by Pol ι, we have examined its proficiency for replicating through the 6O-methyl guanine and 8-oxoguanine lesions, which affect the O6 and N7 positions of template G, respectively. We conclude from these studies that for proficient T incorporation opposite template A, only the N7 hydrogen bonding is required...

Importance of Hydrogen Bonding for Efficiency and Specificity of the Human Mitochondrial DNA Polymerase*

Lee, Harold R.; Helquist, Sandra A.; Kool, Eric T.; Johnson, Kenneth A.
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
Publicado em 23/05/2008 EN
Relevância na Pesquisa
26.28%
To assess the contribution to discrimination afforded by base pair hydrogen bonding during DNA replication by the human mitochondrial DNA polymerase, we examined nucleoside mimics lacking hydrogen bond forming capability but retaining the overall steric shape of the natural nucleotide. We employed oligonucleotide templates containing either a deoxyadenosine shape mimic (dQ) or a deoxythymidine shape mimic (dF). Additionally, the nucleoside triphosphate analogs difluorotoluene deoxynucleoside triphosphate, 9-methyl-1-H-imidazo[(4,5)-b]pyridine deoxyribose triphosphate, and 4-methylbenzimidazole deoxyribose triphosphate (dZTP; another dATP shape mimic) were assayed. We used pre-steady state methods to determine the kinetic parameters governing nucleotide incorporation, kpol and Kd. In general, the loss of hydrogen bonding potential led to 2–3 kcal/mol reduction in ground state binding free energy, whereas effects on the maximum rate of polymerization were quite variable, ranging from negligible (dATP:dF) to nearly 4 kcal/mol (dZTP:dT). Although we observed only a 46-fold reduction in discrimination when dF was present in the template, there was a complete elimination of discrimination when dQ was present in the template. Our data with dF indicate that hydrogen bonding contributes 2.2 kcal/mol toward the efficiency of incorporation...

Adsorção e incorporação de impurezas em defeitos estendidos em folhas de grafeno

Brito, Walber Hugo de
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
POR
Relevância na Pesquisa
26.3%
Nesse trabalho, estudou-se (i) a adsorção de átomos de ouro em folhas e nanofitas de grafeno, (ii) a adsorção de átomos de hidrogênio (H) e a incorporação de boro e nitrogênio em fronteiras de grão de folhas de grafeno. O intuito do estudo foi de se determinar quais são as influências dessas impurezas nas propriedades eletrônicas e a estabilidade energética desses materiais. As nanofitas de grafeno (GNR) estudadas foram a zigzag (Z-GNR) e a armchair (AGNR), pois estas configurações além de já terem sido observadas experimentalmente, possuem uma grande variedade de fenômenos ainda não estudados. Os modelos estruturais de fronteiras de grão estudados foram todos já observados experimentalmente e também vem sendo bastante estudados atualmente. Nesse contexto, (i) verificou-se que o Au se liga quimicamente com os átomos de carbono da borda, tanto para as Z-GNRs quanto para as A-GNRs, em que as energias de adsorção eram superiores a -1.0 eV/Au. Em relação às propriedades eletrônicas, foi observado que a presença do ouro nas bordas tende a metalizar o sistema criando níveis semiocupados, que são oriundos principalmente das trilhas de ouro formadas nas bordas. Foi obtido que o ouro sobre as nanofitas de grafeno tende a se difundir predominantemente para as bordas apresentando barreiras de energia em torno de 0.08 eV sobre as A-GNRs e 0.18 eV sobre as Z-GNRs. Adicionalmente...

Hydrogen Incorporation in Ultrananocrystalline Diamond/Amorphous Carbon Films

KULISCH WILHELM; ROSSI FRANCOIS; POPOV Cyril; SIPPEL C.; GRAMBOLE D.; SASAKI T.
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Articles in Journals Formato: Printed
ENG
Relevância na Pesquisa
36.15%
The incorporation of hydrogen within ultrananocrystalline diamond/amorphous carbon composite films has been investigated by nuclear reaction analysis (NRA) and Fourier transform infrared spectroscopy (FTIR). The film bulk contains ca. 7.5-8% H (for a deposition temperature of 600 °C), while the H concentration in the surface region is considerably higher. FTIR measurements show that the hydrogen-rich surface is formed right at the beginning of the deposition process and grows outward as the film thickness increases. It can thus be concluded that surface hydrogen species play an active role in the formation of ultrananocrystalline diamond/amorphous carbon films.; JRC.I.4-Nanobiosciences

Hydrogen incorporation and crystallization of nanocrystalline silicon deposited by electron cyclotron resonance plasmas

Holgado González-Guerrero, Susana; Martínez Rodríguez, Javier; Garrido, Javier; Piqueras Piqueras, Juan
Fonte: Electrochemical Society, Inc. Publicador: Electrochemical Society, Inc.
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.02%
The archival version of this work was published in J. Electrochem. Soc.146.5, (1999): 1966-1970.; Nanocrystalline silicon layers have been deposited by electron cyclotron resonance chemical vapor deposition from silane as precursor. Although hydrogen was not deliberately introduced in the plasma it was incorporated in the grown layers as evidenced by the presence of a main infrared absorption band around 2100 cm21 with a shoulder at 2000 cm21. This suggests that most of the hydrogen is bonded to internal surfaces of microcavities instead of isolated Si–H bonds. In the first few hundreds, ,500 Å, of deposited layers, the estimated hydrogen concentration is rather low, below 5 atom %, and increases strongly for larger thicknesses. Solid phase crystallization at ,11008C occurs in thin layers close to the substrates in which the hydrogen concentration is below a certain critical value of ,5 atom %

Efeitos da interação de vapor d’água, de nitrogênio e de hidrogênio com estruturas dielétrico/SiC; Effects of the interaction of water vapor, of nitrogen and of hydrogen with dielectric/SiC structures

Corrêa, Silma Alberton
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
46.54%
No presente trabalho, foram investigados os efeitos de tratamentos térmicos em vapor d’água, em óxido nítrico e em hidrogênio nas propriedades físico-químicas e elétricas de filmes dielétricos crescidos termicamente e/ou depositadas por sputtering sobre lâminas de carbeto de silício. A caracterização foi realizada antes e após tratamentos térmicos nesses ambientes através de técnicas que utilizam feixes de íons. Em alguns casos, a caracterização elétrica também foi realizada. A investigação da incorporação e distribuição em profundidade de hidrogênio e oxigênio após tratamentos de SiO2/SiC e SiO2/Si em vapor d’água mostrou que há diferenças marcantes na interação da água com as duas estruturas. Observou-se maior incorporação de oxigênio no filme pré-existente de SiO2 sobre o SiC do que em SiO2/Si, evidenciando uma maior concentração de defeitos nos filmes sobre SiC. A incorporação de hidrogênio também foi maior nas estruturas SiO2/SiC, sendo observada em todas as regiões do filme de SiO2 crescido sobre SiC. Nos filmes crescidos sobre Si, no entanto, a incorporação deuse, principalmente, na região da superfície do filme de óxido. A interação do vapor d’água com estruturas SiO2/SiC e SiO2/Si com filmes depositados por sputtering também foi investigada. Foi constatada uma incorporação distinta da observada para essas estruturas quando seus óxidos foram crescidos termicamente. A incorporação de hidrogênio do vapor d’água em estruturas com filmes de SiO2 depositados por sputtering sobre SiC e sobre Si ocorre...

Interdependence of electroformation and hydrogen incorporation in titanium dioxide

Strungaru, M.; Cerchez, M.; Herbertz, S.; Heinzel, T.; Achhab, M. El; Schierbaum, K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.05%
It is shown that in nanoporous titanium dioxide films, sensitivity to atmospheric hydrogen exposure and electroforming can coexist and are interdependent. The devices work as conventional hydrogen sensors below a threshold electric field while above it, the well-known electroforming is observed. Offering hydrogen in this regime accelerates the electroforming process, and in addition to the usual reversible increase of the conductance in response to the hydrogen gas, an irreversible conductance decrease is superimposed. The behavior is interpreted in terms of a phenomenological model where current carrying, oxygen-deficient filaments with hydrogen-dependent conductivities form inside the titanium dioxide matrix.; Comment: 4 pages, 3 figures

Effect of hydrogen on the microstructure evolution of nanocrystalline silicon

Fugallo, Giorgia; Mattoni, Alessandro; Colombo, Luciano
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.02%
We investigated the effect of dissolved hydrogen on the microstructure evolution of nanocrystalline silicon. Through molecular dynamics simulations we characterize the local and overall structural features of several hydrogenated samples by the quantitative calculation of their crystallinity. We prove that hydrogen incorporation is detrimental for the recrystallization and accumulates at grain boundaries, thus increasing their effective area. We further observe the formation of silicon hydrogen complexes at very high hydrogen concentration.; Comment: submitted for publication

Hydrogen Incorporation in Natural Mantle Olivines

Mosenfelder, Jed L.; Sharp, Thomas G.; Rossman, George R.; Asimow, Paul D.
Fonte: American Geophysical Union Publicador: American Geophysical Union
Tipo: Book Section; PeerReviewed Formato: application/pdf
Publicado em //2006
Relevância na Pesquisa
46.3%
Constraints on water storage capacity and actual content in the mantle must be derived not only from experimental studies, but also from investigation of natural samples. Olivine is one of the best-studied, OH-bearing "nominally anhydrous" minerals, yet there remain multiple hypotheses for the incorporation mechanism of hydrogen in this phase. Moreover, there is still debate as to whether the mechanism is the same in natural samples vs. experimental studies, where concentrations can reach very high values (up to ~0.6 wt% H_2O) at high pressures and temperatures. We present new observations and review IR and TEM data from the literature that bear on this question. Hydrogen incorporation in natural olivine clearly occurs by multiple mechanisms, but in contrast to some previous assertions we find that there are strong similarities between the IR signatures of experimentally annealed olivines and most natural samples. At low pressures (lower than ~2 GPa) in both experiments and natural olivines, hydrogen incorporation might be dominated by a humite-type defect, but the nature of the defect may vary even within a single sample; possibilities include point defects, planar defects and optically detectable inclusions. IR bands between 3300 and 3400 cm^(-1)...

Hydrogen Incorporation, Diffusivity and Evolution in Bulk ZnO

Ip, K; Overberg, M E; Heo, Y W; Norton, D P; Pearton, S J; Stutz, C E; Kucheyev, Sergei; Jagadish, Chennupati; Williams, James; Luo, B; Ren, Fan; Look, David C; Zavada, J M
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.15%
Hydrogen is readily incorporated into bulk, single-crystal ZnO during exposure to plasmas at moderate (100-300°C) temperatures. Incorporation depths of >25 μm were obtained in 0.5 h at 300°C, producing a diffusivity of ∼8 × 10-10 cm2/Vs at this temp