989 resultados para H2O
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Artculo cientfico: postprint
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[EUS] Gaur egun nanozientzia zientzia eta teknologia arlo guztietara zabaldu da, gizarte garapenean eragin handia izan du. Ikerkuntza arlo guztietara zabaldu da ezinezkoak ziruditen erronkak argitu eta ezezagunak ditugun ezagutzak garatzeko asmoz. Lan honetan TiO2 nanohagatxoen sintesia burutu da metodo hidrotermala erabiliz. Sintesi baldintzek lortutako produktuaren egituran eta forman duten eragina kontuan harturik, sintesia gertatzeko ezinbestekoak diren pHa, tenperatura eta denbora aztertu dira. Ondoren, tratamendu kimiko eta termiko ezberdinen bidez konposizio eta egitura ezberdinak lor daitezkeela frogatu da. Bereziki, surfaktante eta pHaren arabera egitura ezberdinak lortzen direla ikusirik. Sintetizatutako laginen karakterizazioa burutzeko X izpien difrakzioa, transmisio bidezko mikroskopia elektronikoa, infragorri espektroskopia, eta termograbimetria teknikak erabili dira. Hauen bidez NaTi3O6(OH)x(H2O)y , (TiO2)x(H2O)y , anatasa eta rutilo faseak identifikatu dira, eta nanohagatxoen lodiera eta morfologia ezberdinak ikusi dira.
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No presente trabalho descrita a obteno de hidrazonas derivadas de isoniazida e de seus complexos de cobre(II) e glio(III) candidatos a prottipos de frmacos antituberculose e antitumoral. Para investigar o efeito da modificao qumica sobre as bioatividades do frmaco isoniazida, foram preparados cinco derivados hidraznicos: 2-piridinocarboxaldedo isonicotinoil hidrazona (HPCIH, 1), 2-acetilpiridina isonicotinoil hidrazona (HAPIH, 2), 2-benzoilpiridina isonicotinoil hidrazona (HBPIH, 3), 2-piridinoformamida isonicotinoil hidrazona (HPAmIH, 4) e 2-pirazinoformamida isonicotinoil hidrazona (HPzAmIH, 5), sendo o composto HPAmIH (4) indito. Anlises de ponto de fuso, espectroscopia de infravermelho (IV), espectrometria de massas, ressonncia magntica nuclear (RMN), anlise elementar e termogravimetria confirmaram a obteno e pureza das hidrazonas. Foi determinada ainda a estrutura de HPCIH (1) por difrao de raios X de monocristal. Essas molculas foram efetivas em inibir o crescimento de cepas de micobactrias Mycobacterium tuberculosis H37Rv (ATCC 27294) nas concentraes testadas, com exceo de HPzAmIH (5). As hidrazonas HAPIH (2) e HBPIH (3) foram os compostos orgnicos mais ativos (concentrao inibitria mnima, CIM = 0,625 g/mL), apresentando atividade antimicobacteriana apenas duas vezes inferior do frmaco isoniazida.Quanto ao contra clulas tumorais, as hidrazonas HAPIH (2) e HBPIH (3) foram as mais potentes contra as linhagens OVCAR-8 (tumor de ovrio - humano), HCT-116 (tumor de clon - humano) e SF-295 (glioblastoma humano), com inibies de 34,98 a 98,63% do crescimento celular, na concentrao de 5 g/mL, enquanto que a isoniazida no foi efetiva contra as linhagens estudadas. Para avaliar o efeito da coordenao a metais sobre a atividade farmacolgica das hidrazonas, foram sintetizados os complexos de cobre(II) e glio(III), sendo todos inditos: [Cu(HPCIH)Cl2]∙H2O (6), [Cu(HAPIH)Cl2]∙H2O (7), [Cu2(HBPIH)2Cl2]Cl2∙4H2O(8), [Cu(HPAmIH)Cl2]∙H2O (9), [Cu(HPzAmIH)Cl2]∙H2O (10), [Ga(HPCIH)2](NO3)32H2O (11), [Ga(HAPIH)(APIH)](NO3)22H2O (12), [Ga(HPAmIH)(PAmIH)](NO3)22H2O(13) e [Ga(HPzAmIH)(PzAmIH)](NO3)2H2O (14). Os complexos foram caracterizados por espectroscopia de IV, anlise elementar, condutivimetria, RMN e espectroscopia eletrnica. Em geral, os complexos tambm demonstraram ao contra M. tuberculosis, sendo que apenas para 6, 9, 10 e 14 foi verificada melhor atividade em relao s hidrazonas livres. Os complexos metlicos foram tanto quanto ou mais ativos contra as clulas tumorais OVCAR-8, HCT-116 e SF-295 do que as hidrazonas livres. Merecem destaque os complexos 79 e 12, que apresentaram inibio de crescimento celular de 72,2100%, na concentrao de 5 g/mL. Os resultados demonstram portanto que em geral os compostos 114 so menos ativos do que a isoniazida contra M. tuberculosis, enquanto que a modificao qumica do frmaco, formando-se hidrazonas com posterior complexao cobre(II) e glio(III) constituram uma estratgia interessante na obteno de compostos mais potentes contra clulas tumorais
Materiais tipo hidrotalcita contendo Cu como precursores de catalisadores para a reduo de NO pelo CO
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Dentre os xidos de nitrognio, o N2O um gs do efeito estufa altamente nocivo. Devido ao potencial contaminante que este possui, torna-se importante a implementao de processos capazes de reduzir a sua emisso, bem como a dos NOx. Tradicionalmente, tm-se empregado catalisadores baseados em metais nobres, porm estes apresentam como principal desvantagem o elevado custo. Desse modo, sempre houve o interesse pelo uso de outros tipos de catalisadores e metais neste sistema de reao. Nesse contexto, na presente dissertao procurou-se sintetizar precursores de catalisadores tipo hidrotalcita Cu-AlCO3 e avaliar o seu desempenho na reao de reduo do NO pelo CO, visando melhorar a atividade e a seletividade a N2. Foram estudados diversos parmetros de sntese e diferentes composies. Os parmetros mais influentes na sntese foram a relao molar H2O/(Al+Cu) e a temperatura de secagem do slido, cujos melhores valores foram 434 e 25C, respectivamente. Testaram-se dois slidos, o primeiro composto pela fase hidrotalcita quase pura e o segundo com uma clara mistura entre fases hidrotalcita e malaquita. As anlises trmica e qumica revelaram presena da fase malaquita em ambos os materiais com porcentagens de 14 e 40%, respectivamente. Os resultados de difrao de raios X indicaram a presena da fase CuO para os catalisadores provenientes da calcinao dos materiais tipo hidrotalcita, porm a espectroscopia Raman evidenciou a presena de Cu2O no catalisador proveniente do material com maior mistura de fases. Os ciclos redox mostraram uma melhora na redutibilidade dos catalisadores aps um ciclo de oxidao-reduo. Alm disso, foi estudado o impacto do envelhecimento trmico a 900C por 12 h no desempenho dos catalisadores. Pelos resultados de teste cataltico os melhores desempenhos foram alcanados pelos catalisadores envelhecidos, contudo o catalisador proveniente do precursor mais puro apresentou-se melhor tanto novo como envelhecido em termos de menor rendimento de N2O. Uma comparao com catalisadores base de metal nobre mostrou um bom desempenho dos catalisadores base de cobre, com a vantagem destes apresentarem menor emisso de N2O em temperaturas menores
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CP0.7 g H2O/g DW0.64 g H2O/g DW 0.43 g H2O/g DW1.02 g H2O/g DW0.69 g H2O/g DW-50 EPRTTC
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During the low temperature setting of fish paste, myosin heavy chain (MHC) is polymerized to cross-linked myosin heavy chain (CMHC), which is considered to occur by the action of endogenous transglutaminase (TGase). In this study the contribution of TGase on the setting of Alaska pollack surimi at different temperatures was studied. Alaska pollack surimi was ground with 3% NaCl, 30% h2o and with or without ethylene glycol bis (-aminoethylether) N, N, N,N- tetra acetic acid (EGTA), an inhibitor of TGase. Among the pastes without EGTA, highest TGase activity was observed at 25C but breaking force of the gel set at 25C was lower than that set at 30, 35, and 40C. Addition of EGTA (5m mol/kg) to the paste suppressed TGase activity at all setting temperatures from 20 to 40C. Gelation of the pastes and cross-linking of MHC on addition of EGTA were suppressed completely at 20 and 25C, partially at 30 and 35C, and not at all at 40C. The findings suggested that during the setting of Alaska pollack surimi TGase mediated cross-linking of MHC was strong at around 25C but the thermal aggregation of MHC by non-covalent bonds was strong at above 35C. Setting of surimi at 40C and cross-linking of its MHC did not involve TGase.
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1 2SDS-PAGE30 KD27 KD30 KD27 KDab 3681mm732 nmF732F732/F683PSIPS 4a/ba/b0.9ba 5FvFv/FoH2O DCIPPS LHCP
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() 1Mn202H2OCl(a)H20Mn202Mn;(b)2H2OMn202 2MnCaClMn2022H2O ()Tyr_zTyr_D Tyr_zTyr_D(a)Tyr_DTyr_z;(b)Tyr;(c)(H_20);(d)Tyr_D~+Tyr_z~+ () 1P_(870)(a);(b)P870C3P870+ 2IIP680a50.02.5 3N-(C4H6N2)CCL4ChlaC4H6N2CDMCD(a)CCL4Chla5ChlaChla2Mg-O(OC131C17C=O);(b)C4H6N2Chla = 0.51CDMCDChlaC4H6N2Mg-OMg-OChlaMgOP_(680) TyrZ2H2OCMn1IIMn4III;NMn2IVMn3IV;ClMB4TMCa;CaOCOO-Mn202TyrZ(D1-His190)MnO(TyrZTyrD) CaC1Mn
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D254179. 8 U SP U m g, 201. 5 U SP U m g , H2O 2 (1. 5% ) (24 h) , (85. 8% )
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Our group recently reproduced the water-assisted growth method, so-called "SuperGrowth", of millimeter-thick single-walled carbon nanotube (SWNT) forests by using C2H4/H2/H2O/Ar reactant gas and Fe/Al2O3, catalyst. In this current work, a parametric study was carried out on both reaction and catalyst conditions. Results revealed that a thin Fe catalyst layer (about 0.5 nm) yielded rapid growth of SWNTs only when supported on Al2O3, and that Al2O3 support enhanced the activity of Fe, Co, and Ni catalysts. The growth window for the rapid SWNT growth was narrow, however. Optimum amount of added H2O increased the SWNT growth rate but further addition of H2O degraded both the SWNT growth rate and quality. Addition of H2 was also essential for rapid SWNT growth, but again, further addition decreased both the SWNT growth rate and quality. Because Al2O3 catalyzes hydrocarbon reforming, Al2O3 support possibly enhances the SWNT growth rate by supplying the carbon source to the catalyst nanoparticles. The origin of the narrow window for rapid SWNT growth is also discussed.
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Chemical looping combustion (CLC) is a novel combustion technology that involves cyclic reduction and oxidation of oxygen storage materials to provide oxygen for the combustion of fuels to CO2 and H2O, whilst giving a pure stream of CO2 suitable for sequestration or utilisation. Here, we report a method for preparing of oxygen storage materials from layered double hydroxides (LDHs) precursors and demonstrate their applications in the CLC process. The LDHs precursor enables homogeneous mixing of elements at the molecular level, giving a high degree of dispersion and high-loading of active metal oxide in the support after calcination. Using a Cu-Al LDH precursor as a prototype, we demonstrate that rational design of oxygen storage materials by material chemistry significantly improved the reactivity and stability in the high temperature redox cycles. We discovered that the presence of sodium-containing species were effective in inhibiting the formation of copper aluminates (CuAl2O4 or CuAlO 2) and stabilising the copper phase in an amorphous support over multiple redox cycles. A representative nanostructured Cu-based oxygen storage material derived from the LDH precursor showed stable gaseous O2 release capacity (5 wt%), stable oxygen storage capacity (12 wt%), and stable reaction rates during reversible phase changes between CuO-Cu 2O-Cu at high temperatures (800-1000 C). We anticipate that the strategy can be extended to manufacture a variety of metal oxide composites for applications in novel high temperature looping cycles for clean energy production and CO2 capture. The Royal Society of Chemistry 2013.
Thermogravimetric study on the hydration of reactive magnesia and silica mixture at room temperature
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The synthesis of magnesium silicate hydrate (MSH), which has wide applications in both construction and environmental fields, has been studied for decades. However, it is known that the characteristics of magnesia (MgO) vary significantly depending on their calcination conditions, which is expected to affect their performance in the MgO-SiO2-H2O system. This paper investigated the effect of different MgO and silica sources on the formation of magnesium silicate hydrate (MSH) at room temperature. The hydration process was studied by mixing commercial reactive MgO and silica powders with water and curing for 1, 7 and 28 days. The hydration products were analysed with the help of X-ray diffraction (XRD) and thermogravimatric analysis (TGA). The results showed the continuous consumption of MgO and the existence of MSH and brucite and other minor phases such as magnesite and calcite. It is found that the Mg and Si sources have significant effect on the hydration process of MgO-SiO2-H2O system. The reaction degree is controlled by the availability of dissolved Mg and Si in the solution. The former is determined by the reactivity of MgO and the latter is related to the reactivity of the silica as well as the pH of the system. 2013 Elsevier B.V. All rights reserved.
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Upon heating, hydrated magnesium carbonates (HMCs) undergo a continuous sequence of decomposition reactions. This study aims to investigate the thermal decomposition of various commercially produced HMCs classified as light and heavy, highlight their differences, and provide an insight into their compositions in accordance with the results obtained from thermal analysis and microstructure studies. An understanding of the chemical compositions and microstructures, and a better knowledge of the reactions that take place during the decomposition of HMCs were achieved through the use of SEM, XRD, and TG/differential thermal analysis (DTA). The quantification of their CO 2 contents was provided by TG and dissolving the samples in HCl acid. Results show that variations exist within the microstructure and decomposition patterns of the two groups of HMCs, which do not exactly fit into the fixed stoichiometry of the known HMCs in the MgO-CO2-H2O system. The occurrence of an exothermic DTA peak was only observed for the heavy HMCs, which was attributed to their high CO2 contents and the relatively delayed decomposition pattern. 2013 Akadmiai Kiad, Budapest, Hungary.
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Gel filtration chromatography, ultra-filtration, and solid-phase extraction silica gel clean-up were evaluated for their ability to remove microcystins selectively from extracts of cyanobacteria Spirulina samples after using the reversed-phase octadecylsilyl ODS cartridge for subsequent analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The reversed-phase ODS cartridge/silica gel combination were effective and the optimal wash and elution conditions were: H2O (wash), 20% methanol in water (wash), and 90% methanol in water (elution) for the reversed-phase ODS cartridge, followed by 80% methanol in water elution in the silica gel cartridge. The presence of microcystins in 36 kinds of cyanobacteria Spirulina health food samples obtained from various retail outlets in China were detected by LC-MS/MS, and 34 samples (94%) contained microcystins ranging from 2 to 163 ng g(-1) (mean=1427 ng g(-1)), which were significantly lower than microcystins present in blue green alga products previously reported. MC-RR-which contains two molecules of arginine (R)-(in 94.4% samples) was the predominant microcystin, followed by MC-LR-where L is leucine-(30.6%) and MC-YR-where Y is tyrose-(27.8%). The possible potential health risks from chronic exposure to microcystins from contaminated cyanobacteria Spirulina health food should not be ignored, even if the toxin concentrations were low. The method presented herein is proposed to detect microcystins present in commercial cyanobacteria Spirulina samples.