Quasi real-time Raman studies on the growth of Cu-In-S thin films

In this work annealing and growth of CuInS2 thin films is investigated with quasireal-time in situ Raman spectroscopy. During the annealing a shift of the Raman A1 mode towards lower wave numbers with increasing temperature is observed. A linear temperature dependence of the phonon branch of ��2 cm��1/100 K is evaluated. The investigation of the growth process (sulfurization of metallic precursors) with high surface sensitivity reveals the occurrence of phases which are not detected with bulk sensitive methods. This allows a detailed insight in the formation of the CuInS2 phases. Independent from stoichiometry and doping of the starting precursors the CuAu ordering of CuInS2 initially forms as the dominating ordering. The transformation of the CuAu ordering into the chalcopyrite one is, in contrast, strongly dependent on the precursor composition and requires high temperatures.

Dura����o do per��odo de molhamento foliar em pomares de macieira em c��u aberto e sob tela antigranizo, em Vacaria-RS

A dura����o do per��odo de molhamento foliar (DPM) �� um importante par��metro para a determina����o do risco de doen��as da macieira, especialmente a sarna, principal doen��a da cultura. O clima regional e as caracter��sticas de implanta����o e manejo de pomares s��o fatores determinantes da ocorr��ncia do molhamento foliar. Em fun����o do microclima do dossel, �� necess��rio conhecer a posi����o com maior DPM, para dar suporte a modelos de previs��o de doen��as. Poucos trabalhos avaliaram a DPM em pomares de macieira, sendo que inexistem estudos nas condi����es de cultivo do Sul do Brasil, em particular na regi��o produtora de Vacaria, Rio Grande do Sul. Este trabalho objetivou caracterizar a varia����o espacial da DPM em doss��is de macieiras em c��u aberto e sob tela antigranizo, na regi��o de Vacaria. O experimento foi desenvolvido em pomares de macieiras 'Royal Gala', conduzidos em l��der central com apoio (espa��amento de 1m x 3m), sendo um coberto por tela antigranizo e o outro em c��u aberto. A DPM foi monitorada nos estratos superior, m��dio e inferior dos doss��is de macieira. A dura����o do molhamento foliar foi superior no estrato inferior do dossel, tanto em c��u aberto quanto sob tela antigranizo. Houve tend��ncia de mais alta DPM no pomar coberto para todos os estratos do dossel, com diferen��a significativa entre ambientes nos estratos superior e m��dio. Os valores de DPM foram mais similares entre os estratos no dossel coberto por tela antigranizo do que no dossel a c��u aberto.

Sele����o de modelos de regress��o para estimar a ��rea foliar de macieiras 'Royal gala' e 'Fuji suprema' sob tela antigranizo e em c��u aberto

O objetivo deste trabalho foi ajustar e testar modelos matem��ticos simples, precisos e acurados para estimar a ��rea foliar de macieiras 'Royal Gala' e 'Fuji Suprema' cultivadas sob tela antigranizo e em c��u aberto. O experimento foi conduzido em pomar comercial no munic��pio de Vacaria-RS, nos ciclos vegetativos de 2008/2009 e 2009/2010. Equa����es de regress��o linear e quadr��tica foram ajustadas para estimativa da ��rea foliar em fun����o das dimens��es das folhas. A sele����o dos melhores modelos baseou-se no quadrado m��dio do erro, no coeficiente de determina����o, no erro-padr��o da estimativa e na signific��ncia dos coeficientes das equa����es. A ��rea foliar estimada pelos melhores modelos foi comparada com dados obtidos de medi����o por plan��metro e estimados por fotografias digitais. A prova dos modelos baseou-se na signific��ncia do coeficiente angular, na linha 1:1 e na raiz quadrada do quadrado m��dio do erro. Modelos linear e quadr��tico que consideram o comprimento e a largura das folhas estimam com acur��cia e precis��o a ��rea foliar de macieiras 'Royal Gala' e 'Fuji Suprema', tanto sob tela antigranizo quanto em c��u aberto. A ��rea foliar de macieira estimada por modelos de regress��o que utilizam comprimento e largura de folhas �� similar �� obtida por plan��metro ou fotografia digital.

Oxidized oils and dietary zinc and alpha-tocopheryl acetate supplementation: effects on rabbit plasma, liver and meat fatty acid composition and meat Zn, Cu, Fe and Se content

The effects of the addition of heated oils to feeds (3%, w/w) and the dietary supplementation with a-tocopheryl acetate (TA; 100 mg/kg) and Zn (200 mg/kg) on rabbit tissue fatty acid (FA) composition and on the Zn, Cu, Fe and Se content in meat were assessed. Heating unre���ned sun���ower oil (SO) at 558C for 245 h increased its content in primary oxidation products and reduced its a-tocopherol content. However, this did not signi���cantly affect tissue FA composition. Heating SO at 1408C for 31 h increased its content in secondary oxidation products and in some FA isomers asc9,t11-CLA and di-trans CLA. This led to increases in di-trans CLA in liver and in t9,c12-18:2 in meat. The c9,t11-CLA was the most incorporated CLA isomer in tissues. The dietary supplementation with a-TA did not affect the FA composition of plasma, liver or meat. The cooking of vacuum-packed rabbit meat at 788C for 5 min reduced signi���cantly but slightly its polyunsaturated FA content. The dietary supplementation with Zn did not modify the content of Zn, Fe or Se in meat, but it reduced its Cu content. On the other hand, it increased the content of some FAs in meat when SO heated at 1408C for 31 h was added to feeds.

Estructura cristalina del N-isopropil-2-ciano-3(5'-nitrofuril)acrilamida

C11H11N3O4 , Mr = 249.23, triclinic, , a = 5.453(1), b = 22.873(5), c = 4.893(1) ��, a = 94.47(3), b = 96.36(3), g = 86.27(3)��, V = 603.7(8)����,Z = 2, Dx = 1.371 Mg/m-3,l(Cu Ka1) = 1.54178��, m = 0.86mm-1, room temperature. The crystal structure of N-isopropyl-2-cyano-3(5'-nitrofuryl) - acrylamide has been determined by Direct Methods and refined to R = 0.086 for 797 observed reflections. The molecules in the crystal are packed at normal van der Waals forces and by an hydrogen bond between N1-H1...02i (N1...02i: 2.910(1)��), with i=x,y,z+1).

Sulfitos duplos contendo cobre (I) e um metal de transi����o M(II) tipo Cu2SO3.M(II)SO3.2H 2O [M(II) = Cu(II), Fe(II), Mn(II) e Cd(II)]: prepara����o e seletividade na incorpora����o de M(II)

The metal-catalyzed autooxidation of S(IV) has been studied for more than a century without a consensus being obtained as to reaction rates, rate laws or mechanisms. The main objective in this work was to explore the reaction between Cu(II) and SO2 in the presence of M(II), paying special attention to the formation of double sulfites like Cu2SO3.M(II)SO3.2H 2O. The two principal aspects studied were: i) a new way to prepare double sulfites with high purity degree and the selectivity in the M(II) incorporation during the salt formation.

Decomposi����o do NO sobre Cu suportado em ze��litas

Direct decomposition of NO on copper supported on zeolite catalysts such as MCM-22 and Beta was compared with that on the thoroughly studied Cu-ZSM-5. The catalysts were prepared by ion-exchange in basic media. They were characterized by atomic absorption, surface area, nitrogen adsorption at 77K, X-ray diffraction and temperature programmed reduction. The products of the reaction were analyzed by Fourier transform infrared spectroscopy using a gas cell. Catalytic activity tests indicated that zeolite catalysts, like Beta and MCM-22, lead to NO conversion values comparable to ZSM-5.

Cu and Co exchanged ZSM-5 zeolites: activity towards no reduction and hydrocarbon oxidation

|Cu x|[Si yAl]-MFI and |Co x|[Si yAl]-MFI catalysts were prepared by ion exchange from |Na|[Si yAl]-MFI zeolites (y = 12, 25 and 45). The activity of the catalysts was evaluated in the reduction of NO to N2 in an oxidative atmosphere using propane or methane as reducing agents. The Cu catalysts were only active with propane and they presented higher activity than the Co-based catalysts, the latter being active with both hydrocarbons. H2-TPR and DRS-UV/Vis data allowed correlation between the activity towards NO reduction and the presence of cationic charge-compensating species in the zeolite. It was also verified that the hydrocarbons are preferentially oxidised by O2, a reaction that occurs simultaneously with their oxidation with NO.

Selective Ortho-Hydroxylation���Defluorination of 2-Fluorophenolates with a Bis(m-oxo)dicopper(III) Species

The bis(mu-oxo) dicopper(III) species [Cu-III 2(mu-O)(2)(m-XYLMeAN)](2+) (1) promotes the electrophilic ortho-hydroxylation-defluorination of 2-fluorophenolates to give the corresponding catechols, a reaction that is not accomplishable with a (eta(2) : eta(2)-O-2) dicopper(II) complex. Isotopic labeling studies show that the incoming oxygen atom originates from the bis(mu-oxo) unit. Ortho-hydroxylation-defluorination occurs selectively in intramolecular competition with other ortho-substituents such as chlorine or bromine

Produ����o de hidrog��nio a partir da reforma a vapor de etanol utilizando catalisadores Cu/Ni/gama-Al2o3

Cu/Ni/gamma-Al2O3 catalysts were prepared by an impregnation method with 2.5 or 5% wt of copper and 5 or 15% wt of nickel and applied in ethanol steam reforming. The catalysts were characterized by atomic absorption spectrophotometry, X-ray diffraction, temperature programmed reduction with hydrogen and nitrogen adsorption. The samples showed low crystallinity, with the presence of CuO and NiO, both as crystallites and in dispersed phase, as well as of NiO-Al2O3. The catalytic tests carried out at 400 ��C, with a 3:1 water/ethanol molar ratio, indicated the 5Cu/5Ni/Al2O3 catalyst as the most active for hydrogen production, with a hydrogen yield of 77% and ethanol conversion of 98%.

Planejamento estat��stico de experimentos como uma ferramenta para otimiza����o das condi����es de biossor����o de Cu(II) em batelada utilizando-se casca de nozes pec�� como biossorvente

In order to reduce the total number of experiments for achieving the highest amount of adsorbed Cu2+ (qmax) using pecan nutshells (Carya illinoensis) as biosorbent, a full 2(4) factorial design with two central points was carried out (mass of biosorbent- m, pH, initial metallic ion concentration- C0, time of contact- t). In order to continue the optimization of the system, a central composite surface analysis design with two factors and five central points was carried out. The maximum amount of Cu2+ taken up by the pecan nutshells was 20 mg g-1. These results were confirmed by determining a Cu2+ isotherm using the best conditions attained by the statistical design of experiments.

Determina����o voltam��trica por redissolu����o an��dica de Cu(II) em ��guas residu��rias empregando um eletrodo de pasta de carbono modificado com quitosana

The electrochemical applications of a CPE modified with chitosan for the determination of Cu(II) in wastewater samples using anodic stripping voltammetry are described. The best voltammetric response was observed for a paste containing 25% m/m of chitosan. A 0.10 mol L-1 NaNO3 solution (pH 6.5) as supporting electrolyte, a pre-concentration potential of -0.20 V, pre-concentration time of 270 s and a scan rate of 25 mV s-1 were selected. The calibration graph was linear in the Cu(II) concentration range from 2.0 x 10-7 to 7.4 x 10-6 mol L-1, with a detection limit of 8.3 x 10-8 mol L-1.

Titula����es potenciom��tricas de c��tions met��licos tendo como eletrodo indicador o sistema Cu/Cu(II)-EDTA

In potentiometric titrations of metal cations with EDTA the Hg/HgY2- system is usually used to detect the end point. However, the use of mercury has been discouraged in analytical procedures due to its toxicity. In this work the Cu/CuY2- system was used as indicator electrode for potentiometric titrations of some metal cations with EDTA. The solutions of Cu2+, Cd2+, Mn2+, Co2+ and Zn2+ were titrated with Na2EDTA solution in the presence of a small concentration of the CuY2- complex using a copper wire as indicator electrode. The potentiometric titrations with the Cu/CuY2- system showed good correlation when compared with an Hg/HgY2- system.

Aplica����o de Zr/Ti-PILC no processo de adsor����o de Cu(II), Co(II) e Ni(II) utilizando modelos f��sico-qu��micos de adsor����o e termodin��mica do processo

The aim of this investigation is to study how Zr/Ti-PILC adsorbs metals. The physico-chemical proprieties of Zr/Ti-PILC have been optimized with pillarization processes and Cu(II), Ni(II) and Co(II) adsorption from aqueous solution has been carried out, with maximum adsorption values of 8.85, 8.30 and 7.78 x10-1 mmol g-1, respectively. The Langmuir, Freundlich and Temkin adsorption isotherm models have been applied to fit the experimental data with a linear regression process. The energetic effect caused by metal interaction was determined through calorimetric titration at the solid-liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.

Caracteriza����o de escamas do peixe piau (Leporinus elongatus) e sua aplica����o na remo����o de Cu(II) de meio aquoso

Characterization of fish scales of Leporinus elongatus and their application in the removal of Cu(II) from aqueous solutions are described. It was observed that the scales are mainly formed by hydroxyapatite and type I collagen. Adsorption of Cu(II) was performed using batch experiments at 25 0C. The ANOVA statistical results have shown that the Langmuir model was successful applied to determine the maximum adsorption capacity of 2.686 x10-4 mol g-1 and the Langmuir equilibrium parameter (b) of 168.8 L mol-1. The Langmuir separation parameter, R L, has shown favorable adsorption of Cu(II) on the scales.