Photocatalytic decomposition of methylene blue via Fenton mechanisms by silicon wafer doped with Au and Cu: a theoretical and experimental study

In this work, we studied the photocatalytic and the structural aspects of silicon wafers doped with Au and Cu submitted to thermal treatment. The materials were obtained by deposition of metals on Si using the sputtering method followed by fast heating method. The photocatalyst materials were characterized by synchrotron-grazing incidence X-ray fluorescence, ultraviolet-visible spectroscopy, X-ray diffraction, and assays of H(2)O(2) degradation. The doping process decreases the optical band gap of materials and the doping with Au causes structural changes. The best photocatalytic activity was found for thermally treated material doped with Au. Theoretical calculations at density functional theory level are in agreement with the experimental data.

Hydrogen purification for fuel cell using CuO/CeO(2)-Al(2)O(3) catalyst

CuO/CeO(2), CuO/Al(2)O(3) and CuO/CeO(2)-Al(2)O(3) catalysts, with CuO loading varying from 1 to 5 wt.%, were prepared by the citrate method and applied to the preferential oxidation of carbon monoxide in a reaction medium containing large amounts of hydrogen (PROX-CO). The compounds were characterized ex situ by X-ray diffraction, specific surface area measurements, temperature-programmed reduction and temperature-programmed reduction of oxidized surfaces; XANES-PROX in situ experiments were also carried out to study the copper oxidation state under PROX-CO conditions. These analyses showed that in the reaction medium the Cu(0) is present as dispersed particles. On the ceria, these metallic particles are smaller and more finely dispersed, resulting in a stronger metal-support interaction than in CuO/Al(2)O(3) or CuO/CeO(2)-Al(2)O(3) catalysts, providing higher PROX-CO activity and better selectivity in the conversion of CO to CO(2) despite the greater BET area presented by samples supported on alumina. It is also shown that the lower CuO content, the higher metal dispersion and consequently the catalytic activity. The redox properties of the ceria support also contributed to catalytic performance. (C) 2010 Elsevier B.V. All rights reserved.

CuO and CuO-ZnO catalysts supported on CeO(2) and CeO(2)-LaO(3) for low temperature water-gas shift reaction

This paper describes an investigation on CuO and CuO-ZnO catalysts supported on CeO(2) and CeO(2)-La(2)O(3) oxides, which were designed for the low temperature water-gas shift reaction (WGSR). Bulk catalysts were prepared by co-precipitation of metal nitrates and characterized by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), surface area (by the BET method), X-ray photoelectron spectroscopy (XPS), and in situ X-ray absorption near edge structure (XANES). The catalysts` activities were tested in the forward WGSR, and the CuO/CeO(2) catalyst presented the best catalytic performance. The reasons for this are twofold: (1) the presence of Zn inhibits the interaction between Cu and Ce ions, and (2) lanthanum oxide forms a solid solution with cerium oxide, which will cause a decrease in the surface area of the catalysts. Also the CuO/CeO(2) catalyst presented the highest Cu content on the surface, which could influence its catalytic behavior. Additionally, the Cu and Cu(1+) species could influence the catalytic activity via a reduction-oxidation mechanism, corroborating to the best catalytic performance of the Cu/Ce catalyst. (c) 2010 Elsevier B.V. All rights reserved.

F��ljsamhet till r��d om egenv��rd hos patienter med diabetes typ 2 : En litteratur��versikt

Bakgrund: Diabetes typ 2 ��r en endokrin sjukdom och ett globalt h��lsoproblem, d��r antalet insjuknande personer ��kar kraftigt. Behandlingen vid diabetes typ 2 utg��rs till st��rsta del av egenv��rd vilket st��ller stora krav p�� patienten och p�� sjukv��rden. En bristande f��ljsamhet till r��d om egenv��rd kan leda till s��mre h��lsa f��r patienten och ��kade kostnader f��r samh��llet. Syfte: Syftet med denna litteratur��versikt var att beskriva vilka faktorer som p��verkar f��ljsamheten till r��d om egenv��rd hos patienter med diabetes typ 2. Metod: En litteratur��versikt baserad p�� 15 vetenskapliga artiklar d��r b��de kvalitativa och kvantitativa artiklar har granskats. Databaserna CINAHL och PubMed har anv��nts. Resultat: Faktorer som p��verkade f��ljsamheten till r��d om egenv��rd identifierades och resulterade i fem huvudkategorier: Information; Kunskap; Socialt st��d; Teknologiskt st��d och Livssituation. Dessa faktorer framkom som viktiga f��r en god f��ljsamhet till r��d om egenv��rd. Slutsats: Det ��r av stor betydelse att f��rs��ka identifiera varje individs olika f��ruts��ttningar, f��r att p�� s�� s��tt ha m��jlighet att anpassa b��de information, utbildning och egenv��rdsplanering utifr��n individen.

Avalia����o de metais na ��gua, no sedimento e nos peixes da lagoa Azul, formada por lavra de minera����o de carv��o a c��u aberto, Sider��polis-SC

Entre maio de 2001 e janeiro de 2002, foram realizadas coletas sazonais na lagoa Azul, Sider��polis, SC. Esta lagoa formou-se por lavra de minera����o de carv��o a c��u aberto desativada. Foram avaliadas as concentra����es de Cr, Mn, Ni, Zn e Fe na ��gua e no sedimento. Estes metais, exceto o Fe, foram tamb��m analisados no m��sculo e no f��gado das esp��cies dos peixes Oreochromis niloticus (til��pia) e Geophagus brasiliensis (acar��). O objetivo foi avaliar a qualidade da lagoa, bem como, das esp��cies de peixes predominantes, devido a preocupa����o quanto ao consumo potencial das mesmas pela popula����o do entorno. As an��lises do sedimento, quando comparada a locais n��o contaminados, indicam concentra����o elevada para Fe, Mn, Cr e Zn. No compartimento ��gua as concentra����es de Fe, Mn e Ni est��o acima do estabelecido para a classe 2 da Resolu����o CONAMA 20/86. Conforme an��lise estat��stica, em ambos os compartimentos abi��ticos ocorrem diferen��as significativas entre os 4 pontos amostrados, por��m diferen��a sazonal ocorre somente para o compartimento ��gua. O conte��do de metais em peixes n��o apresenta diferen��a significativa entre as esp��cies analisadas, todavia entre os diferentes tecidos analisados, o f��gado apresentou a maior concentra����o em ambas as esp��cies. Atrav��s das an��lises do m��sculo (parte comest��vel), foi poss��vel avaliar o risco �� sa��de humana. Segundo a estimativa da ingest��o di��ria, os peixes analisados n��o propiciam risco aparente de contamina����o �� popula����o do entorno, conforme os crit��rios adotados para o teor dos metais avaliados.

Metalog��nese do dep��sito de Cu Cerro dos Martins, RS.

Este trabalho revisa a geologia e apresenta dados in��ditos do Dep��sito de Cobre Cerro dos Martins (DCM), incluindo geocronologia Pb-Pb em zirc��o, inclus��es fluidas, is��topos est��veis (C, O e S), composi����o isot��pica do Sr e geoqu��mica de elementos maiores e tra��os das rochas vulc��nicas encaixantes. O dep��sito est�� hospedado na seq����ncia vulcano-sedimentar do Grupo Bom Jardim, da Bacia do Camaqu��, do Neoproteroz��ico do Escudo Sul Rio-grandense, e possui reservas calculadas de 1.450.000 t, com teor m��dio de 0,83% Cu. O dep��sito consiste de um conjunto de veios sulfetados que preenchem fraturas de dire����o N40��-60��W em rochas andes��ticas e sedimentares cl��sticas, com dissemina����es confinadas em n��veis de siltito, arenito, andesito e conglomerado, da Forma����o Hil��rio do Grupo Bom Jardim. Os minerais do min��rio filoneano s��o a calcosina e bornita com calcopirita, pirita, galena e esfalerita subordinadas. Digenita, covelita, malaquita cuprita e azurita ocorrem como min��rio secund��rio em ganga constitu��da de carbonatos, quartzo, minerais argilosos, barita e rara hematita. A composi����o qu��mica das vulc��nicas (elementos maiores e tra��os, incluindo ETR) indicam uma afinidade alcalina para o vulcanismo relacionado �� Forma����o Hil��rio na regi��o do Cerro dos Martins. Um corpo de quartzo-diorito, intrusivo nas rochas vulc��nicas e sedimentares, mostrou idade de 550 ��5 Ma (Pb-Pb em zirc��es) indicando um valor m��nimo para a gera����o do min��rio do DCM. Esta idade confirma a posi����o estratigr��fica desta rocha na Forma����o Acampamento Velho e tamb��m fornece uma idade m��nima para a deposi����o da seq����ncia vulcano-sedimentar encaixante do DCM. Os sulfetos do DCM mostram ��S34 CDT com valores relativamente homog��neos entre - 6.2 e + 0.9��� (n= 7). O valor de ��S34 CDT da calcopirita, levemente positivo (+0.9���), indica uma origem magm��tica para o S, mas os valores negativos encontrados nestes sulfetos, poderiam indicar o envolvimento de outras fontes com enxofre reduzido. Entretanto, a presen��a de hematita nas parag��neses minerais indica que o min��rio foi formado sob condi����es oxidantes, modificando a composi����o isot��pica original do enxofre magm��tico (��S34 CDT ~ 0���) para valores negativos. As baritas analisadas apresentam valores com ��S34 CDT entre +9.25 e +10.65��� (n=4) indicando deposi����o em condi����es oxidantes, originadas pela mistura de um fluido magm��tico-hidrotermal com ��gua mete��rica. A composi����o isot��pica do C das calcitas do DCM varia com ��C13 PDB entre - 1,90 a -4,45���, interpretada como resultante da mistura entre carbono de fonte magm��tica com m��rmores do embasamento. Inclus��es fluidas em quartzo do min��rio indicam temperaturas de deposi����o entre 157 e 273 ��C com mediana de 215 ��C (n = 45). A composi����o isot��pica do oxig��nio da ��gua em equilibrio com a calcita do fluido hidrotermal (T= 215 ��C) mostra valores de �� O18 SMOW entre 3 e 14, indicando H2O de origem magm��tica, com contribui����o de ��gua mete��rica. A raz��o Sr87/Sr86 das mesmas calcitas mostram valores entre 0,7068 ��� 0,7087, de crosta superior. Rochas plut��nicas e vulc��nicas do escudo com idades pr��ximas de 550 Ma possuem raz��es iniciais Sr87/Sr86 entre 0,704 ��� 0,710, compat��veis com aquelas encontradas nas calcitas da mineraliza����o. Os fluidos hidrotermais do magmatismo shoshon��tico-alcalino com idade de 595 Ma e Sr87/Sr86 entre 0,7041 a 0,7053, tamb��m s��o candidatos a fonte do Sr dos carbonatos hidrotermais, mas necessitariam de um componente mais radiog��nico. Assim, a fonte de C-O e Sr das calcitas do min��rio pode ter sido originada diretamente de um fluido magm��tico-hidrotermal ou de uma mistura entre este fluido e m��rmores do embasamento. Portanto, o dep��sito Cerro dos Martins �� interpretado como de origem magm��tica-hidrotermal, relacionado ao evento magm��tico alcalinoshoshon��tico, p��s-colisional da Orog��nese Dom Feliciano, com idade entre 595-550 Ma. Novos modelos explorat��rios para dep��sitos de cobre no Escudo do Rio Grande do Sul devem considerar o magmatismo alcalino na g��nese dos dep��sitos.

Direct determination of Cu, Cd, Ni and Pb in aquatic humic substances by graphite furnace atomic absorption spectrometry

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Influ��ncia dos ��ons Mg, Ca, Fe, Cu e Zn sobre a tens��o superficial est��tica de solu����es contendo surfatante

O objetivo do estudo foi avaliar a influ��ncia da presen��a de cinco ��ons em uma calda de pulveriza����o contendo o surfatante Aterbane. A tens��o superficial foi analisada por meio da medi����o da massa de um conjunto de 25 gotas, com quatro repeti����es constituindo um tratamento. O trabalho foi dividido em duas etapas. Na primeira, os tratamentos foram combinados em esquema fatorial 9x5x2, sendo nove concentra����es do surfatante Aterbane (0,01; 0,025; 0,05; 0,1; 0,2; 0,5; 1; 2; e 3%), cinco ��ons (Mg++, Ca++, Fe+++, Cu+++ e Zn+++) e duas concentra����es desses elementos (10 e 100 ppm). Na segunda etapa, os tratamentos foram combinados em esquema fatorial 5x5x1, utilizandose os mesmos cinco elementos (Mg++, Ca++, Fe+++, Cu+++ e Zn+++), em cinco concentra����es (1, 5, 20, 50 e 200 ppm), com apenas uma concentra����o do surfatante Aterbane (0,025%). Outros nove tratamentos permitiram avaliar as tens��es superficiais das concentra����es do surfatante (0,01; 0,025; 0,05; 0,1; 0,2; 0,5; 1; 2; e 3%) sem a adi����o dos ��ons. Os resultados mostraram que houve interfer��ncia dos ��ons sobre as solu����es, j�� que, com exce����o do Fe+++ (na concentra����o de 10 e 100 ppm) e do Cu+++ (na concentra����o de 100 ppm), todos os ��ons reduziram a tens��o m��nima alcan��ada e aumentaram a efici��ncia do surfatante, implicando benef��cios �� a����o do surfatante e sobre as caracter��sticas de poss��veis solu����es de aplica����o. Todos os ��ons avaliados promoveram redu����es nas tens��es superficiais de solu����es do surfatante na concentra����o de 0,025%.

Saberes de astronomia no 1�� e 2�� ano do ensino fundamental numa perspectiva de letramento e inclus��o

This work suggests a discussion about methodologies and didactic-pedagogical activities for the teaching of Astronomy in first and second cycles of the primary school, in a perspective of literacy and inclusion. The presented proposals have been developed in a group of the Public School Alceu Amoroso Lima, North of Natal city, with children since six years old, amongst which two considered as being with special needs . This research aims to demonstrate that it is possible to develop with those children the contents of Astronomy, while they participate of the process of literacy and inclusion. From this, we are searching a theoretical-practical contribution so that the Par��metros Curriculares Nacionais (Brazilian Nacional Curricular Guideness) include the referred contents in first cycle of primary school. For the accomplishment of this research, Experiential Astronomy was initially proposed. Later on, many workshops had been carried through (clay, ripping , crepon paper, plasticine, cardboard and gastro-lunar ). All the proposed activities were based on the conjunction of contents, which characterized the interdisciplinarity. Through the approach we adopted and the practices we proposed, we could evidence that not only children considered as being normal , but also that ones who carries special needs could appropriate themselves of our writing code, develop and incorporate a daily relationship close to the stuffs of the sky, learn many information about all of this, besides constructing attitudinal, procedural and conceptual contents

Study of copper complexes adsorbed on a silica gel surface chemically modified with 2-amino-1,3,4-thiadiazole

The isotherms of adsorption of CuX2 (X=Cl-, Br-, ClO4-) by silica gel chemically modified with 2-amino-1,3,4-thiadiazole were studied in acetone and ethanol solutions: at 298 K. The following equilibria constants (in 1 mol(-1)) were determined: (a) CuCl2: 3.5 x 10(3) (ac), 2.0 x 10(3) (eth); (b) CuBr2: 2.8 x 10(3) (ac), 2.0 x 10(3) (eth); (c) Cu(ClO4)(2): 1.8 x 10(3) (ac), 1.0 x 10(3) (eth); ac = acetone, eth = ethanol. The electron spin resonance spectra of the surface complexes indicated a tetragonal distorted structure in the case of lower degrees of metal loading on the chemically modified surface. The d-d electronic transition spectra showed that for the ClO4-, complex, the peak of absorption did not change for any degree of metal loading, and for Cl- and Br- complexes, the peak maxima shifted to a higher energy region with a lower metal loading. (C) 1998 Elsevier B.V. B.V. All rights reserved.

Study of copper complexes absorbed on a silica gel surface chemically modified with 5-amino-1,3,4-thiadiazole-2-thiol

The isotherms of adsorption of CuX2 (XCl-, Br-, ClO4-) by silica gel chemically modified with 5-amino-1,3,4-thiadiazole-2-thiol were studied in acetone and ethanol solutions, at 25 degrees C. The following equilibria constants (in L mol(-1)) were determined: (a) CuCl2, 3.2 x 10(3) (ac), 2.5 x 10(3) (eth); (b) CuBr2, 2.9 x 10(3) (ac), 2.3 x 10(3) (eth); (c) Cu(ClO4)(2), 1.8 x 10(3) (ac), 1.2 x 10(3) (eth); ac, acetone; eth, ethanol. The electron spin resonance spectra of the surface complexes indicated a tetragonal-distorted structure in the case of lower degrees of metal loading on the chemically modified surface. The d-d electronic transition spectra showed that for the ClO4- complex, the peak of absorption did not change for any degree of metal loading and for Cl- and Br- complexes, the peak maxima shifted to higher energy with lower metal loadings. (C) 1998 Academic Press.

Adsorption of CuX2 (X = Cl-, Br-, and ClO4-) on a silica gel surface chemically modified with thiazolidine-2-thione from acetone and ethanol solutions

The isotherms of adsorption of CuX2 (X = Cl-, Br, ClO4-,) by silica gel chemically modified with thiazolidine-2-thione were studied in acetone (ac) and ethanol (eth) solutions at 25 degrees C. The following equilibrium constants (in 1 mol(-1)) were determined: a) CuCl2, 1.9 x 10(3) (ac), 1.6 x 10(3) (eth); b) CuBr2, 1.7 x 10(3) (ac), 1.2 x 10(3) (eth); c) Cu(ClO4)(2), 1.1 x 10(3) (ac), 1.0 x 10(3) (eth). The electron spin resonance spectra of the surface complexes indicate a tetragonal distorted structure in the case of lower degrees of metal loading on the chemically modified surface. The d-d electronic transition spectra show that for the ClO4- complex, the peak of absorption did not change for any degree of metal loading, and for Cl- and Br complexes, the peak maxima shift to higher energy with lower metal loading.

Preconcentration and determination of Cu(II) in a fresh water sample using modified silica gel as a solid-phase extraction adsorbent

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Comparison of the univariate and multivariate methods in the optimization of experimental conditions for determining Cu, Pb, Ni and Cd in biodiesel by GFAAS

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Attachment of 2,2-bipyridine onto a silica gel for application as a sequestering agent for copper, cadmium and lead ions from an aqueous medium

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)