246 resultados para NI2
Resumo:
Transparent Ni2+-doped MgO-Al2O3-SiO2 glass ceramics without and with Ga2O3 were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga2O3 addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni2+-doped glass ceramics was largely enhanced by Ga2O3 addition which could mainly be caused by increasing of Ni2+ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga2O3 content was all more than 200 nm. The emission lifetime increased with the Ga2O3 content and the longest lifetime is about 250 mu s. The Ni2+-doped transparent glass ceramics with Ga2O3 addition have potential application as broadband optical amplifier and laser materials. (C) 2007 Elsevier Ltd. All rights reserved.
Resumo:
Transparent Ni2+-doped MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics were fabricated. The precipitated nanocrystal phase in the glass ceramics was identified by X-ray diffraction and transmission electron microscope. Broadband near-infrared emission centered at 1220 nm with full width at half maximum of about 240 nm and lifetime of about 250 mu s was observed with 980 nm excitation. The longer wavelength emission compared with Ni2+-doped MgAl2O4 crystal was attributed to the low crystal field occupied by Ni2+ in the glass ceramics. The present Ni2+-doped transparent glass ceramics may have potential applications in broadband optical amplifiers. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
Polycrystalline Zn1-xNixO diluted magnetic semiconductors have been successfully synthesized by an auto-combustion method. X-ray diffraction measurements indicated that the 5 at% Ni-cloped ZnO had the pure wurtzite structure. Refinements of cell parameters from powder diffraction data revealed that the cell parameters of Zn0.95Ni0.05O were a little bit larger than ZnO. Transmission electron microscopy observation showed that the as-synthesized powders were of the size similar to 60 nm. Magnetic investigations showed that the nanocystalline Zn0.95Ni0.05O possessed room temperature ferromagnetisin with the saturation magnetic moment of 0.1 emu/g (0.29 mu(B)/Ni2+). (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
Nanocrystalline Zn0.95 - xNi0.05AlxO (x = 0.01, 0.02, 0.05 and 0.10) diluted magnetic semiconductors have been synthesized by an auto-combustion method. X-ray diffraction measurements indicate that all Al-doped Zn0.95Ni0.05O samples have the pure wurtzite structure. Transmission electron microscope analyses show that the as-synthesized powders are of the size 40 - 45 nm. High-resolution transmission electron microscope, energy dispersive spectrometer and X-ray photoemission spectroscope analyses indicate that Ni2+ and Al3+ uniformly substitute Zn2+ in the wurtzite structure without forming any secondary phases. The Al doping concentration dependences of cell parameters (a and c), resistance and the ratio of green emission to UV emission have the similar trends. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
Artculo cientfico: postprint
Resumo:
Esta Dissertao teve como objetivo,a sntese de hidrogis base de alginato e nanopartculas magnticas (maghemita) preparadas in situ. Os hidrogis foram preparados em diferentes concentraes de alginato de sdio (2 e 3% m/v), FeSO4 (0,3 e 0,5 mol L-1) e CaCl2 (0,1 e 0,3 mol L-1). As propriedades fsico-qumicas dos hidrogis foram analisadas e, posteriormente, foram avaliados quanto capacidade de remoo de ons Ni2+ e Mn2+ de solues aquosas. Para caracterizao das amostras foram utilizadas diversas tcnicas de anlises, tais como, anlise granulomtrica, microscopia ptica (OM), microscopia eletrnica de varredura (SEM), microscopia eletrnica de transmisso (TEM), magnetometria de amostra vibrante (VSM), espectroscopia na regio do infravermelho por transformada de Fourier (FTIR), difratometria de raios-X (XRD), espectroscopia Mssbauer, e anlise termogravimtrica (TGA). Foram preparados hidrogis com morfologia predominantemente esfrica e dimenses micromtricas (500 a 850 m), com tomos de Fe e Ca dispersos uniformemente em sua estrutura. Os hidrogis apresentaram boa resistncia trmica e comportamento superparamagntico. As amostras foram intumescidas em gua deionizada durante um intervalo de tempo a fim de avaliar o grau de intumescimento (Q) para determinar a amostra com a melhor resposta para posterior aplicao em soluo aquosa contendo ons metlicos (Ni2+ e Mn2+). Os resultados revelaram que a amostra cuja concentrao de 3% m/v de alginato de sdio, 0,3 mol L-1 de FeSO4 e 0,3 mol L-1 de CaCl2 obteve maior Q (50%). Em consequncia deste resultado, optou-se por utilizar estaamostra, na remoo de metais pesados presentes em solues aquosas e em efluentes industriais. Vrios parmetros,tais como: tempo de contato,pH, concentrao inicial do on e massa de hidrogel foram estudados.Os resultados, para efluente sinttico, revelaram que o tempo de equilbrio foi de 60 minutos; a capacidade de remoo dos metais melhora com o aumento de pH (3 a 9), sendo mxima em pH 7;quanto menor a concentrao inicial da soluo inica (50 a 500 mg L-1), maior a capacidade de remoo, 52% de Ni2+ e 49% de Mn2+ (concentrao inicial de 50 mg L-1). No efluente industrial, a remoo foi de 61% de Ni2+ e 57% de Mn2+(300 mg de hidrogel). Os resultados encontrados revelaram que os hidrogis magnticos produzidos base de alginato tm potencial uso no tratamento de efluentes industriais contaminados com metais pesados
Resumo:
A Resoluo CONAMA N 430/2011 exige a utilizao de dois bioensaios (dois nveis trficos) para avaliao ecotoxicolgica de efluentes, mas a seleo ao acaso de bioensaios pode permitir lanamentos txicos. A sensibilidade dos bioindicadores ir depender da substncia txica avaliada. Assim, baterias de bioensaios sensveis devem ser estabelecidas s classes de contaminantes. Na literatura no h estudos que indiquem uma bateria de bioensaios ecotoxicolgicos sensveis para avaliao de efluentes contendo principalmente metais. Esse trabalho teve como objetivo selecionar uma bateria de bioensaios ecotoxicolgicos que conjuntamente detectem toxicidade ao maior nmero de metais isolados e em misturas e que sejam realizados no menor tempo indicado pelas normas de padronizao. Foram avaliadas as sensibilidades de seis bioensaios, incluindo trs nveis trficos (produtores, algas: Pseudokirchneriella subcapitata e Chlorella vulgaris; consumidores primrios, cladceros: Daphnia similis e Ceriodaphnia dubia; consumidores secundrios, peixes: Poecilia reticulata e Danio rerio), a 10 espcies metlicas individuais (Ag+, Cd2+, Cu+, Cu2+, Cr3+, Cr6+, Pb2+, Ni2+, Zn2+ e Hg2+) e a efluentes reais (siderrgicos) e simulados em laboratoriais (baseado nos limites mximos permitidos para descarte). Os bioensaios com peixes foram os menos sensveis, D. rerio no detectou toxicidade em nenhum dos efluentes testados. P. subcapitata foi um bom bioindicador de toxicidade de Cr3+ e D. similis foi o organismo mais sensvel a Hg2+. O uso combinado do bioensaio crnico de 72h com C. vulgaris e do bioensaio agudo de 48h com C. dubia garantiu a deteco das menores concentraes dos metais tanto individualmente quanto em efluentes reais e simulados. Apesar de P. subcapitata ser um bom bioindicador da toxicidade de Cr3+, a interao dos metais em misturas tornou C. vulgaris igualmente sensvel. Da mesma forma, apesar de D. similis ter sido mais sensvel ao Hg2+, o efeito da toxicidade dos efluentes com maiores teores de Hg2+ foi detectado por C. dubia
Resumo:
Na reao de desidrogenao oxidativa de propano (ODHP), propano reage com oxignio da superfcie de metais de transio para produzir propeno e gua, em temperaturas de 300-700C. Porm, o propeno pode facilmente oxidar, formando CO e CO2. Assim, busca-se catalisadores que promovam a seletividade do propeno. Compostos tipo hidrotalcitas esto sendo apontados como catalisadores de grande potencial para a reao. Portanto, o principal objetivo desse trabalho foi sintetizar precursores tipo hidrotalcitas (contendo ons Ni2+, Mg2+ e Al3+ e tereftalato, heptamolibdato e decavanadato como nions de compensao) para serem testados na reao de desidrogenao oxidativa de propano. Esses precursores foram sintetizados com uma razo Al/(Al+Ni+Mg)=0,5, variando a razo de Ni/Mg. Alm disso, realizou-se a troca inica do tereftalato (TA) por heptamolibdato (Mo7O24) e decavanadato (V10O28). Esses compostos foram calcinados, obtendo-se assim, xidos mistos de NiMgAl, NiMgAlMo e NiMgAlV que foram testados como catalisadores na reao de ODHP. Para a determinao das propriedades dos catalisadores foram usadas as tcnicas de caracterizao: DRX, TGA, volumetria de N2, TPR, Raman e FTIR e ICP. Os resultados indicaram que os materiais tipo hidrotalcita foram obtidos com sucesso. No caso dos precursores preparados por troca inica a cristalinidade foi menor que os da srie NiMgAl-TA. Estes mesmos precursores quando calcinados apresentaram reas muito altas. Nas trs sries, os precursores calcinados so constitudos por xidos mistos como NiO, NiMoO4, Ni2V2O7 cristalinos e espcies de alumnio e magnsio no detectados na DRX. No teste cataltico de ODHP, observou-se que com o aumento da converso diminua a seletividade de propeno, para os xidos mistos que no continham molibdnio. Os catalisadores da srie molibdnio foram os que obtiveram melhor desempenho com altas seletividades, mesmo em altas converses e a srie de cujo precursor foi o tereftalato foi a que exibiu maiores converses, mas com seletividades menores que da srie de Mo
Resumo:
IIYZ(D1-Y161)IIII(OEC) PSII LaCl3TbCl3Co2Ni2PSII 1. PSII , -PSII; 2. PSII , CaCl2Ca2+Mn3(III)>Mn(III)Mn(III)> Mn(III)Mn(IV) 3. LaCl3 TbCl3 IILa3+Tb3+IICa2+Ca2+ 10 mmol/L Ca2+50%50%PSII10 4Ni2Co2IINi2Co2II17 kDa23 kDaIICaCl25 mmol/L17 kDa10 mmol/L17 kDa 23 kDaMnCa
Resumo:
Granular reactive materials have higher permeability and are therefore desirable for in situ groundwater pollution control. Three granular bentonites were prepared: an Al-pillared bentonite (PBg), an organo-bentonite (OBg) using a quaternary ammonium cation (QAC), and an inorgano-organo-bentonite (IOBg), using both the pillaring agent and the QAC. Powdered IOB (IOBp) was also prepared to test the effect of particle size. The modified bentonites were characterised with X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA) and uniaxial compression tests. The d-spacing increased only with QAC intercalation. The Young's modulus of IOBg was twice as high as OBg. Batch adsorption tests were performed with aqueous multimetal solutions of Pb2+, Cu2+, Cd2+, Zn2+ and Ni2+ ions, with liquid dodecane and with aqueous dodecane solutions. Metal adsorption fit the Langmuir isotherm. Adsorption occurred within 30min for PBg, while the granular organo-bentonite needed at least 12h to reach equilibrium. IOBp had the maximum adsorption capacity at higher metal concentration and lower adsorbent content (Cu2+: 2.2, Ni2+: 1.7, Zn2+: 1.4, Cd2+: 0.9 and Pb2+: 0.7 all in mmolg-1). The dual pillaring of the QAC and Al hydroxide increased the adsorption. The adsorption of liquid dodecane was in the order IOBg>OBg>PBg (3.2>2.7>1.7mmolg-1). Therefore IOBg has potential for the removal of toxic compounds found in soil, groundwater, storm water and wastewater. 2012 Elsevier B.V.
Resumo:
eIF2αHRI/,,eIF2αPoHRIHRIPCRPoHRI1-200cDNA,pET32aIPTG,Ni2+-NTA,PoHRI,PoHRIPoHRI
Resumo:
Ni2 + , RR -1 5 5V , 1 5 08 0 0mg L , , 0 998, 0 0 7mg L , , ; , ,
Resumo:
Palm oil has been the world's main source of oil and fats since 2004, producing over 45 million tonnes in 2009. Malaysia alone has over 45 million hectares planted with oil palm and, based on common practice, ~300 palm fronds are pruned per hectare per year. This agricultural waste is currently either being used as roughage feed or, more frequently, being left between rows of palm trees to prevent soil erosion, or for nutrient recycling purposes. This paper proposes an alternative use for palm frond as a source of biochar. A traditional method commonly use by gardeners in Malaysia to improve soil fertility was used to produce the biochar. A shallow earth pit was dug in the ground for the carbonisation process. The process is described and the impact of carbonisation on the earth wall is analysed and presented. The process was later re-assessed by using TGA-FTIR. Most of the hemicelluloses had fully disintegrated, but the depolymerisation of the cellulose was still incomplete at the carbonisation temperature. Most of the lignin aromatic structure was still present in the biochar. The carbonisation process was repeated in the laboratory and biochar was characterised by using BET, SEM and FTIR. An adsorption isotherm study was conducted and the experimental data were fitted to the Langmuir model. The model predicted Pb2+ adsorption rates of 833 mg/g, Cu2+ 414 mg/g, Ni2+ 130 mg/g and Zn2+ 197 mg/g. Copyright The Royal Society of Edinburgh 2012.
Resumo:
Eu~3Sm~3Mn~2Fe~3Co~2Ni~2ZnOcccc10Onm15357-366nmEu3+Sm3Mn2+Fe3Co2Ni2Zn2+O2- Eu3+ZnO363nm368nmEg=3.423.40evEu3Zn1-xEux0.005x0.15Zn1-xTMxO356nm-369nm3.34-3.46eVCo2d-dZn1-xCoxO60Zn1-xEuxO90Zn1-xEuxO613nmEu37F5D378nmZnO394nmEu3+5D07FJJ1234zno378nmEu3+5D07F2znoE4-400KZn0.9Eu0.1OznogCooIO23oK200KM-HBr021emgHc327OeZn0.9Mn0.1OZn0.9Ni0.1OZn0.9Co0.1O80KZn0.9Eu0.1OZT110K14.53Zn1-xTMxOCoFeNiMnZn1-xTMxO80Co2DMSsol-gelZnoTMMCM-41AAOZnO:TMMCM-41MCM-41AAoloonmMCM-41Zn0.9Co0.1O80K-30OKMnFeNiZnoAAOZnO:TM(TM=MnFeCoNiSOK-30OKZnO:AABuSmcoZnlxCoxOPH5ZnORERE=EuSmZn0.98Co0.02O80KZnOREREEuSm80K
Resumo:
ABBLaSr2Mn2O7CrTiNiFeMnBCr3Mn4Cr3crNi2Fe3MnLaS2Mn2O7MnMnMnFex0.2MR28OK74LasrZMn2O7Bi3+Sr2+x0.2Bi3Bi3TcoGdn=3Laca4kMn3O10La3-3xCa13xMn3O100.5x1.0La3x0.50.7x=0.8-1.0La3Mn3Mn3+Mn4+LaxCa4-xMn3O10x0-0.9Mn4x0.2x0.2xG-AFMx0.9C-AFM
