22 resultados para cyclic oxidation – Ti3SiC2-base material – scale spallation – adherence

em Repositório Científico do Instituto Politécnico de Lisboa - Portugal


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In order to correctly assess the biaxial fatigue material properties one must experimentally test different load conditions and stress levels. With the rise of new in-plane biaxial fatigue testing machines, using smaller and more efficient electrical motors, instead of the conventional hydraulic machines, it is necessary to reduce the specimen size and to ensure that the specimen geometry is appropriated for the load capacity installed. At the present time there are no standard specimens geometries and the indications on literature how to design an efficient test specimen are insufficient. The main goal of this paper is to present the methodology on how to obtain an optimal cruciform specimen geometry, with thickness reduction in the gauge area, appropriated for fatigue crack initiation, as a function of the base material sheet thickness used to build the specimen. The geometry is optimized for maximum stress using several parameters, ensuring that in the gauge area the stress is uniform and maximum with two limit phase shift loading conditions. Therefore the fatigue damage will always initiate on the center of the specimen, avoiding failure outside this region. Using the Renard Series of preferred numbers for the base material sheet thickness as a reference, the reaming geometry parameters are optimized using a derivative-free methodology, called direct multi search (DMS) method. The final optimal geometry as a function of the base material sheet thickness is proposed, as a guide line for cruciform specimens design, and as a possible contribution for a future standard on in-plane biaxial fatigue tests. 2014, Gruppo Italiano Frattura. All rights reserved.

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In order to correctly assess the biaxial fatigue material properties one must experimentally test different load conditions and stress levels. With the rise of new in-plane biaxial fatigue testing machines, using smaller and more efficient electrical motors, instead of the conventional hydraulic machines, it is necessary to reduce the specimen size and to ensure that the specimen geometry is appropriate for the load capacity installed. At the present time there are no standard specimen's geometries and the indications on literature how to design an efficient test specimen are insufficient. The main goal of this paper is to present the methodology on how to obtain an optimal cruciform specimen geometry, with thickness reduction in the gauge area, appropriate for fatigue crack initiation, as a function of the base material sheet thickness used to build the specimen. The geometry is optimized for maximum stress using several parameters, ensuring that in the gauge area the stress distributions on the loading directions are uniform and maximum with two limit phase shift loading conditions (delta = 0 degrees and (delta = 180 degrees). Therefore the fatigue damage will always initiate on the center of the specimen, avoiding failure outside this region. Using the Renard Series of preferred numbers for the base material sheet thickness as a reference, the reaming geometry parameters are optimized using a derivative-free methodology, called direct multi search (DMS) method. The final optimal geometry as a function of the base material sheet thickness is proposed, as a guide line for cruciform specimens design, and as a possible contribution for a future standard on in-plane biaxial fatigue tests

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New rhenium(VII or III) complexes [ReO3(PTA)(2)][ReO4] (1) (PTA = 1,3,5-triaza-7-phosphaadamantane), [ReO3(mPTA)][ReO4] (2) (mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation), [ReO3(HMT)(2)] [ReO4] (3) (HMT = hexamethylenetetramine), [ReO3(eta(2)-Tpm)(PTA)][ReO4] (4) [Tpm = hydrotris(pyrazol-1-yl)methane, HC(pz)(3), pz = pyrazolyl), [ReO3(Hpz)(HMT)][ReO4] (5) (Hpz = pyrazole), [ReO(Tpms)(HMT)] (6) [Tpms = tris(pyrazol-1-yl)methanesulfonate, O3SC(pz)(3)(-)] and [ReCl2{N2C(O)Ph} (PTA)(3)] (7) have been prepared from the Re(VII) oxide Re2O2 (1-6) or, in the case of 7, by ligand exchange from the benzoyldiazenido complex [ReCl2(N2C-(O)Ph}(Hpz)(PPh3)(2)], and characterized by IR and NMR spectroscopies, elemental analysis and electrochemical properties. Theoretical calculations at the density functional theory (DFT) level of theory indicated that the coordination of PTA to both Re(III) and Re(VII) centers by the P atom is preferable compared to the coordination by the N atom. This is interpreted in terms of the Re-PTA bond energy and hard-soft acid-base theory. The oxo-rhenium complexes 1-6 act as selective catalysts for the Baeyer-Villiger oxidation of cyclic and linear ketones (e.g., 2-methylcyclohexanone, 2-methylcyclopentanone, cyclohexanone, cyclopentanone, cyclobutanone, and 3,3-dimethyl-2-butanone or pinacolone) to the corresponding lactones or esters, in the presence of aqueous H2O2. The effects of a variety of factors are studied toward the optimization of the process.

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The reaction of 2,6-diformyl-4-methylphenol with 1,3-bis(3-aminopropyl)tetramethyldisiloxane in the presence of MnCl2 in a 1:1:2 molar ratio in methanol afforded a dinuclear -chlorido-bridged manganese(II) complex of the macrocyclic [2+2] condensation product (H2L), namely, [Mn2Cl2(H2L)(HL)]Cl center dot 3H(2)O (1). The latter afforded a new compound, namely, [Mn2Cl2(H2L)(2)][MnCl4]center dot 4CH(3)CN center dot 0.5CHCl(3 center dot)0.4H(2)O (2), after recrystallisation from 1:1 CHCl3/CH3CN. The co-existence of the free and complexed azomethine groups, phenolato donors, mu-chlorido bridges, and the disiloxane unit were well evidenced by ESI mass spectrometry and FTIR spectroscopy and confirmed by X-ray crystallography. The magnetic measurements revealed an antiferromagnetic interaction between the two high-spin (S = 5/2, g = 2) manganese(II) ions through the mu-chlorido bridging ligands. The electrochemical behaviour of 1 and 2 has been studied, and details of their redox properties are reported. Both compounds act as catalysts or catalyst precursors in the solvent-free low-power microwave-assisted oxidation of selected secondary alcohols, for example, 1-phenylethanol, cyclohexanol, 2- and 3-octanol, to the corresponding ketones in the absence of solvent. The highest yield of 72% was achieved for 1-phenylethanol by using a maximum of 1% molar ratio of catalyst relative to substrate.

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The reaction of 2,6-diformyl-4-methylphenol with 1,3-bis(3-aminopropyl)tetramethyldisiloxane in the presence of MnCl2 in a 1:1:2 molar ratio in methanol afforded a dinuclear -chlorido-bridged manganese(II) complex of the macrocyclic [2+2] condensation product (H2L), namely, [Mn2Cl2(H2L)(HL)]Cl center dot 3H(2)O (1). The latter afforded a new compound, namely, [Mn2Cl2(H2L)(2)][MnCl4]center dot 4CH(3)CN center dot 0.5CHCl(3 center dot)0.4H(2)O (2), after recrystallisation from 1:1 CHCl3/CH3CN. The co-existence of the free and complexed azomethine groups, phenolato donors, mu-chlorido bridges, and the disiloxane unit were well evidenced by ESI mass spectrometry and FTIR spectroscopy and confirmed by X-ray crystallography. The magnetic measurements revealed an antiferromagnetic interaction between the two high-spin (S = 5/2, g = 2) manganese(II) ions through the mu-chlorido bridging ligands. The electrochemical behaviour of 1 and 2 has been studied, and details of their redox properties are reported. Both compounds act as catalysts or catalyst precursors in the solvent-free low-power microwave-assisted oxidation of selected secondary alcohols, for example, 1-phenylethanol, cyclohexanol, 2- and 3-octanol, to the corresponding ketones in the absence of solvent. The highest yield of 72% was achieved for 1-phenylethanol by using a maximum of 1% molar ratio of catalyst relative to substrate.

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The reaction between 2-aminobenzenesulfonic acid and 2-hydroxy-3-methoxybenzaldehyde produces the acyclic Schiff base 2-[(2-hydroxy-3-methoxyphenyl) methylideneamino] benzenesulfonic acid (H2L center dot 3H(2)O) (1). In situ reactions of this compound with Cu(II) salts and, eventually, in the presence of pyridine (py) or 2,2'-bipyridine (2,2'-bipy) lead to the formation of the mononuclear complexes [CuL(H2O)(2)] (2) and [CuL(2,2'-bipy)]center dot DMF center dot H2O (3) and the diphenoxo-bridged dicopper compounds [CuL(py)](2) (4) and [CuL(EtOH)](2)center dot 2H(2)O (5). In 2-5 the L-2-ligand acts as a tridentate chelating species by means of one of the O-sulfonate atoms, the O-phenoxo and the N-atoms. The remaining coordination sites are then occupied by H2O (in 2), 2,2'-bipyridine (in 3), pyridine (in 4) or EtOH (in 5). Hydrogen bond interactions resulted in R-2(2) (14) and in R-4(4)(12) graph sets leading to dimeric species (in 2 and 3, respectively), 1D chain associations (in 2 and 5) or a 2D network (1). Complexes 2-5 are applied as selective catalysts for the homogeneous peroxidative (with tert-butylhydroperoxide, TBHP) oxidation of primary and secondary alcohols, under solvent-and additive-free conditions and under low power microwave (MW) irradiation. A quantitative yield of acetophenone was obtained by oxidation of 1-phenylethanol with compound 4 [TOFs up to 7.6 x 10(3) h(-1)] after 20 min of MW irradiation, whereas the oxidation of benzyl alcohol to benzaldehyde is less effective (TOF 992 h(-1)). The selectivity of 4 to oxidize the alcohol relative to the ene function is demonstrated when using cinnamyl alcohol as substrate.

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The dioxovanadium(V) complexes [VO2(3,5-Me(2)Hpz)(3)][BF4] (1) (pz = pyrazolyl), [VO2{SO3C(pz)(3)}] (2), [VO2{HB(3,5-Me(2)pz)(3)}] (3) and [VO2{HC(pz)(3)}][BF4] (4), bearing pyrazole or scorpionate ligands, were obtained by reaction of triethyl vanadate [VO(OEt)(3)] with hydrotris(3,5-dimethyl-1-pyrazolyl)methane [HC(3,5-Me(2)pz)(3)] or 3,5-dimethylpyrazole (3,5-Me(2)Hpz; 1), lithium tris(1-pyrazolyl)methanesulfonate {Li[SO3C(pz)(3)], 2}, potassium hydrotris(3,5-dimethyl-1-pyrazolyl)borate {K[HB(3,5-Me(2)pz)(3)], 3} and hydrotris(1-pyrazolyl)methane [HC(pz)(3), 4], respectively. Treatment of [VO(OEt)(3)] with potassium hydrotris(1-pyrazolyl)borate {K[HB(pz)(3)]} led to the mixed eta(3)-tris(pyrazolyl)borate and eta(2)-bis(pyrazolyl)borate oxovanadium(IV) complex [VO{HB(pz)(3)}{H2B(pz)(2)}, 5]. The compounds were characterized by elemental analyses, IR, NMR and EPR spectroscopy, FAB and ESI mass spectrometry, cyclic voltammetry and, for 5, also by single crystal X-ray diffraction analysis. All complexes exhibit catalytic activity in the single-pot carboxylation [in trifluoroacetic acid/potassium peroxodisulfate (CF3COOH/K2S2O8)] of gaseous alkanes (methane and ethane) to carboxylic acids (yields up to 40%. TONs up to 157) and in the peroxidative oxidation [in water/acetonitrile (H2O/NCMe)] of liquid alkanes (cyclohexane and cyclopentane) to the corresponding alcohols and ketones (yields up to 24%, TONs up to 117), under mild conditions.

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In-plane deformation of foams was studied experimentally by subjecting bidisperse foams to cycles of traction and compression at a prescribed rate. Each foam contained bubbles of two sizes with given area ratio and one of three initial arrangements: sorted perpendicular to the axis of deformation (iso-strain), sorted parallel to the axis of deformation (iso-stress), or randomly mixed. Image analysis was used to measure the characteristics of the foams, including the number of edges separating small from large bubbles N-sl, the perimeter (surface energy), the distribution of the number of sides of the bubbles, and the topological disorder mu(2)(N). Foams that were initially mixed were found to remain mixed after the deformation. The response of sorted foams, however, depended on the initial geometry, including the area fraction of small bubbles and the total number of bubbles. For a given experiment we found that (i) the perimeter of a sorted foam varied little; (ii) each foam tended towards a mixed state, measured through the saturation of N-sl; and (iii) the topological disorder mu(2)(N) increased up to an "equilibrium" value. The results of different experiments showed that (i) the change in disorder, Delta mu(2)(N), decreased with the area fraction of small bubbles under iso-strain, but was independent of it under iso-stress; and (ii) Delta mu(2)(N) increased with Delta N-sl under iso-strain, but was again independent of it under iso-stress. We offer explanations for these effects in terms of elementary topological processes induced by the deformations that occur at the bubble scale.

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Este documento foi escrito para retratar o trabalho desenvolvido como tese de mestrado Desenvolvimento de um Programa/Base de dados para o controlo automtico da Engenharia/Manuteno Aeronutica. O programa criado tem como objectivo de gerir a aeronavegabilidade de uma frota de aeronaves, traduzindo todos os requisitos da autoridade que rege a aeronutica na Europa. O mesmo fundamenta-se no desenvolvimento de um software aplicado a uma empresa que faz a gesto contnua da aeronavegabilidade de um operador areo. A sua realizao implica conhecer todas as tarefas na gesto contnua de aeronavegabilidade dentro de uma empresa certificada Part M. Para esse conhecimento foi preciso um estudo sobre todas as entidades, manuais e definies envolventes a essa funo. A base da construo do programa foi o anexo II, requisitos exigidos pelo INAC para aprovar um programa desse gnero. Para uma melhor abordagem foi preciso uma reviso de conceitos da manuteno industrial resultantes da Manuteno Aeronutica e demais. Num incio, comeca-se por definir atravs de vrios pontos de vista a manuteno, planeamento da manuteno, noes de fiabilidade e teorias fiabilisticas que esto na base do desenvolvimento de programas de manuteno, seguido de uma explicao sucinta do que uma empresa que gere aeronavegabilidade de um operador areo. fei3 ta uma explicao de todas as tarefas para manter todo o material de voo aeronavegvel segundo o INAC . No captulo III temos uma explicao de todas as teorias usadas na manuteno aeronutica na evoluo de programas de manuteno de aeronaves passando pelo MSG1 at filosofia actual usada no desenvolvimento de programas de manuteno na aeronutica, MSG3. O captulo IV descreve todos os documentos tcnicos envolvidos na gesto de aeronavegabilidade, desde os manuais emitidos pelo fabricante, passando pelos documentos emitidos pelas autoridades aeronuticas e documentos tcnicos produzidos pelo prprio operador areo. No captulo V descrita uma organizao Part M, subpart G, as tarefas mais importantes na gesto contnua de aeronavegabilidade e as responsabilidades da mesma perante a autoridade aeronutica nacional e tambem define todo o tipo de manuteno exigida a um operador areo para manter o seu material de voo aeronavegvel sempre atendendo segurana. Este captulo define todo o tipo de trabalho a realizar, desde as manutenes mais leves realizadas na placa com o avio em trnsito at s grandes manutenes realizadas num Hangar e apoiodas por oficinas de especialidade. O captulo VI descrever o que foi feito. Este captulo descreve sucintamente tudo o que foi feito, as razes da criao das tabelas, consultas, formulrios e relatrios e importncia desses na dinmica da gesto de aeronavegabilidade. Depois de explicar a razo da criao de todas as tabelas, consultas e formulrios segue-se um subcaptulo com dados de manuteno fornecidos gentilmente por uma empresa no ramo de forma a poder demostrar como o programa funciona. O ltimo subcaptulo tem algumas consideraes finais sobre aquilo que foi feito e aquilo que deveria ser feito com o objectivo de desempenhar de forma automtica todoss os requisitos de gesto de aeronavegabilidade. O captulo VIII tem algumas recomendaes futuras a algum que quiser dar uma continuidade a esse projecto que pode tornar-se muito interessante para uma empresa Part M.

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Quando aplicada no mbito da Anatomia Patolgica, a imuno-histoqumica tem constitudo um poderoso meio de identificao/caracterizao de vrias estruturas histolgicas, permitindo delinear prognstico e teraputica para vrias patologias. Tendo em conta que as amostras histolgicas analisadas podem ser conservadas ao longo de vrios anos, interessa avaliar a manuteno da antigenicidade ao longo do tempo, de forma a garantir a qualidade final da tcnica quando aplicada em material de arquivo. Assim, o principal objetivo deste trabalho foi comparar a imunorreatividade do material histolgico arquivado durante um, quatro e sete anos. Foi utilizado material histolgico de prstata, pulmo e mama, no qual se procedeu imunomarcao de citoqueratinas (Clones AE1/AE3), CD34 e protena p63, por mtodo de multmero/HRP no sistema Ventana BenchMark Ultra. Foi realizado um ensaio com recuperao antignica por alta temperatura (RAAT) e outro sem esta etapa. As imunomarcaes (n=162) foram classificadas por trs avaliadores independentes num escore quantitativo final (escala 0-100). O par mdia/desvio-padro do escore final para os casos com sete anos foi de 69,06/19,05, para os casos com quatro anos foi de 66,47/20,73 e para os casos com um ano foi de 69,08/19,35, no se tendo encontrado diferenas estatisticamente significativas. Os casos sem RAAT obtiveram um par mdia/desvio-padro de 54,90/17,00, enquanto os casos com RAAT obtiveram 81,50/11,60, o que revelou diferenas estatisticamente significativas (p=0,000). Para os casos em estudo conclui-se que o fator tempo de arquivo no est associado a alteraes da imunorreatividade. A importncia da RAAT na obteno de imunomarcao de qualidade sai fortemente realada. ABSTRACT - When applied within the framework of Pathology, immunohistochemistry has been a powerful means of identification/characterization of various histological structures, allowing to outline prognosis and therapy for various diseases. Given that the analyzed histological samples can be preserved for several years, it is interesting to assess the retention of antigenicity over time in order to ensure the quality of the final technique, when applied to stored material. Thus, the main objective of this study was to compare the immunoreactivity of the histological material archived for one, four and seven years. It was used histological material from prostate, lung and breast, in which it was performed the immunostaining of cytokeratins (clones AE1/AE3), CD34 and p63 protein by the method of multimer/HRP system on a Ventana BenchMark Ultra. It was conducted a test with heat induced epitope retrieval (HIER) and another one without this step. The stained slides (n=162) were classified by three independent assessors using a quantitative score (scale 0-100). The pair mean/standard deviation of the score for cases with seven years was 69,06/19,05, for cases with four years was 66,47/20,73 and for cases with one year was 69,08/19,35, which did not revealed any statistically significant differences. The cases without HIER had a couple mean/standard deviation of 54.90/17.00 while the cases with HIER obtained 81.50/11.60, which revealed statistically significant differences (p=0.000). For this case study it was concluded that the factor archive period is not associated with changes in immunoreactivity. The importance of HIER in obtaining high quality immunostaining comes out strongly highlighted.

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Gold(III) complexes of type [AuCl2{eta(2)-RC(R'pz)(3)}]Cl [R = R' = H (1), R = CH2OH, R' = H (2) and R = H, R' = 3,5-Me-2(3), pz = pyrazol-1-yl] were supported on carbon materials (activated carbon, carbon xerogel and carbon nanotubes) and used for the oxidation of cyclohexane to cyclohexanol and cyclohexanone, with aqueous H2O2, under mild conditions.

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A Organizao Mundial da Sade define a literacia em sade como o conjunto de competncias cognitivas e sociais e a capacidade dos indivduos para compreenderem e usarem informao para a promoo e manuteno da sade. A transmisso de informao sobre sade mais eficaz quando os seus contedos so especificamente desenhados para uma pessoa ou para um grupo populacional e quando a mensagem bem delimitada, realando os benefcios (ganhos) e os custos (perdas) associados aos comportamentos e s tomadas de deciso. Analisa-se, neste estudo, o conceito de literacia em sade e a associao da baixa literacia em sade aos comportamentos em sade e aos gastos em sade. Apresenta-se uma anlise da literatura cientfica publicada sobre a baixa literacia em sade e a sua implicao nos custos na sade usando, para este objectivo, uma base de dados das cincias da sade (MEDLINE/PubMed) e quatro plataformas cientficas (DOAJ, SCOPUS, SciELO e Web of Science). A literatura cientfica analisada evidencia que pessoas com baixa literacia em sade apresentam uma menor capacidade de compreenso dos contedos de material informativo sobre alimentos, doenas crnicas ou sobre o uso de medicamentos, por exemplo, bem como maior dificuldade em pesquisar, seleccionar, ler e assimilar a informao em sade disponvel na Internet. A baixa literacia em sade relaciona-se, ento. com a dificuldade na preveno e na gesto de problemas de sade, bem como com comportamentos ineficazes de sade, i.e., com o uso inadequado de medicamentos, com o recurso excessivo aos servios de sade (em especial, os de urgncias) ou com a ineficcia em lidar com situaes de emergncia. A baixa literacia est tambm associada a taxas de hospitalizao mais altas, mas tambm mais longas no tempo (o que implica mais custos associados a internamento prolongado, mais exames de diagnstico e fraca adeso teraputica medicamentosa), a uma diminuio da utilizao de medidas preventivas e a uma fraca adeso prescrio teraputica. A baixa literacia acaba por afectar igualmente a comunicao (e a relao) mdico-doente. Apresentam-se, como complemento, sugestes de melhoria da literacia em sade e da comunicao mdico-doente para efeitos da promoo da sade.

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Dissertao para obteno do grau de Mestre em Engenharia Qumica

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[CoCl(-Cl)(Hpz(Ph))(3)](2) (1) and [CoCl2(Hpz(Ph))(4)] (2) were obtained by reaction of CoCl2 with HC(pz(Ph))(3) and Hpz(Ph), respectively (Hpz(Ph)=3-phenylpyrazole). The compounds were isolated as air-stable solids and fully characterized by IR and far-IR spectroscopy, MS(ESI+/-), elemental analysis, cyclic voltammetry (CV), controlled potential electrolysis, and single-crystal X-ray diffraction. Electrochemical studies showed that 1 and 2 undergo single-electron irreversible (CoCoIII)-Co-II oxidations and (CoCoI)-Co-II reductions at potentials measured by CV, which also allowed, in the case of dinuclear complex 1, the detection of electronic communication between the Co centers through the chloride bridging ligands. The electrochemical behavior of models of 1 and 2 were also investigated by density functional theory (DFT) methods, which indicated that the vertical oxidation of 1 and 2 (that before structural relaxation) affects mostly the chloride and pyrazolyl ligands, whereas adiabatic oxidation (that after the geometry relaxation) and reduction are mostly metal centered. Compounds 1 and 2 and, for comparative purposes, other related scorpionate and pyrazole cobalt complexes, exhibit catalytic activity for the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions (room temperature, aqueous H2O2). Insitu X-ray absorption spectroscopy studies indicated that the species derived from complexes 1 and 2 during the oxidation of cyclohexane (i.e., Ox-1 and Ox-2, respectively) are analogous and contain a Co-III site. Complex 2 showed low invitro cytotoxicity toward the HCT116 colorectal carcinoma and MCF7 breast adenocarcinoma cell lines.