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Considering the wide application of crystalline Mn–Zn ferrites microparticles, understanding synthesis routes that allow the achievement of such materials is a constant need. In this work, Mn–Zn ferrites, Mn (1− x ) Zn x Fe 2 O 4 (0.15≤ x ≤0.30), were synthesized by the polymeric precursor method in well-controlled steps and the mechanisms of phase formation under different thermal treatments were studied. Such investigation was performed by means of thermal analysis (TG/DTA), synchrotron X-ray powder diffraction (SXPD) (including in-situ and anomalous scattering experiments) and scanning electron microscopy (SEM). The ferrite precursor powders present the spinel as single crystalline phases whose cell parameters increase as Mn is substituted by Zn, indicating possible Fe deficiencies into the structure. The crystallization degree of these samples is also affected by the Mn substitution and reaches a maximum for x =0.25. Further thermal treatments in air at 700 °C and 1100 °C lead to additional events also related to the Zn content, such as carbonates elimination and crystallization of the contaminant phase hematite. Thermal treatments under N 2 atmosphere at 700 °C allow the achievement of powders with only the spinel phase, especially for x =0.25 for which highly crystalline and homogeneous ferrite is obtained despite the Fe deficiency determined by anomalous scattering SXPD. Finally, thermal treatments at 1100 °C under N 2 atmosphere jeopardize the stability of the spinel structure and lead to hematite precipitation.

Made available in DSpace on 2018-12-11T17:27:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-07-01 This paper discusses the applicability of an electronic tongue (e-tongue) based on capacitance measurements to determine the water content in ethanol. The e-tongue consisted of an array of interdigitated electrodes coated with ultrathin films of gallium nitrate and titanium dioxide, which were robust against attack by ethanol. Principal Component Analysis (PCA) was used to treat the capacitance data for discriminating ethanol/water mixtures even in cases with very small water contents. Discrimination is easier if the water added to ethanol contains ions, as is the case of tap water or if NaCl is added to the mixtures. With this e-tongue we were able to quantify the water content through a linear relationship between the first principal component (PC1) and the added water to the biofuel. Therefore, we have proven to be possible to measure the water content precisely, which is one of the major problems in ethanol biofuel adulteration nowadays. Universidade Estadual de Mato Grosso Do sul UEMS Instituto de Biociências UNESP Faculdade de Ciências UNESP Instituto de Física Gleb Wataghin UNICAMP Faculdade de Ciências e Tecnologia UNESP Instituto de Física de São Carlos USP Instituto de Biociências UNESP Faculdade de Ciências UNESP Faculdade de Ciências e Tecnologia UNESP

The effects of silver insertion on the TiO2 photocatalytic activity for the degradation of diclofenac potassium were reported here. Techniques such as X-ray diffraction, scanning electron microscopy and UV–Vis spectroscopy were used to comprehend the relation between structure and properties of the silver-modified TiO2 thin films obtained by the sol–gel method. The lattice parameters and the crystallinity of TiO2 anatase phase were affected by inserted silver, and the film thickness increased about 4 nm for each 1 wt.% of silver inserted. The degradation of diclofenac potassium and by-products reached an efficiency of 4.6 mgC W− 1 when the material was modified with silver. Although the first step of degradation involves only the photochemical process related to the loss of the chlorine and hydrogen atoms. This cyclization reaction leads to the formation of intermediate, which degradation is facilitated by the modified material.

An investigation was made into the photocatalytic activity of in situ synthesized TiO2 chemically modified by Pd(II) 2-aminothiazole complex for phenol degradation at different pH values. At longer reaction times, the bare titania presented far poorer photoactivity than the modified catalysts in the entire range of pH studied. The catalyst complexed with Pd(II) was more efficient than the metal-free Pd, irrespective of pH and reaction time, suggesting that metal plays an important role. A cooperative mechanism is proposed, involving the possible photoactivation of both TiO2 and sensitizer.

This work describes the synthesis and characterization of 2-aminothiazole modified silica gel (SiAT) and the studies of adsorption and pre-concentration (in batch and using a flow-injection system coupled with optical emission spectrometer) of Cd(II), Cu(II) and Ni(II) in aqueous medium. The adsorption capacity for each metal ions in mmol g−1 was: Cu(II) = 1.18, Ni(II) = 1.15 and Cd(II) = 1.10. The results obtained in the flow experiments showed about 100% of recovering of the metal ions adsorbed in a mini-column packed with 100 mg of SiAT, using 100 µL of 2.0 mol L−1 HCl solution as eluent. The quantitative sorption–desorption of the metal ions made possible the application of a flow-injection system in the pre-concentration and quantification by ICP-OES of metal ions at trace level in natural water samples.

Pure and scandium doped-TiO2 thin films were prepared by the sol-gel process and coated by dip coating. The effects of scandium on the phase formation, optical properties and photoactivity of the TiO2 thin films were investigated. The lattice parameters and the crystallinity of the anatase phase, characterized by the Rietveld method, demonstrated that scandium doping affected the structural parameters and crystallinity of the films, modifying the absorption edge. A direct correlation was found between band gap energy and photodegradation efficiency, with lower values of band gap energy augmenting this efficiency. Moreover, a significant improvement in the catalyst’s photodegradation efficiency was attained with a scandium concentration of 5.0 mol%.

This paper describes the preparation of thin titanium films via sol–gel route and their subsequent chemical modification by anchoring with 2-aminothiazole ligand and Pd(II) ion sorption, aiming to maximize the photocatalytic activity. The material was characterized by diffuse reflectance infrared Fourier transform spectroscopy, ultraviolet and visible spectrometry, X-ray diffractometry, and scanning electronic microscopy. The amount of palladium adsorbed on the film's surface, determined by graphite furnace atomic absorption spectrometry, showed a value of 2.69 × 1016 atoms cm− 2. The photocatalytic tests indicated that the functionalization with 2-aminothiazole and the adsorption of palladium (II) were determinants in the semiconductor's enhanced photocatalytic activity.

An investigation was made on the adsorption and kinetics of photodegradation of potassium hydrogenphthalate in an aqueous suspension of TiO(2). Two models, Langmuir and Freundlich, were used to describe the adsorption process and the model proposed by Langmuir-Hinshelwood (L-H) was employed to describe the kinetics of the photodecomposition reactions of hydrogenphthalate. The results of the adsorptions were fitted to the models proposed by Langmuir and Freundlich. Adsorption was found to be a function of the temperature, with adsorption capacity increasing from 2.4 to 4.5 mg/g when the temperature rose from 20 to 30 degrees C. The kinetic model indicates that the rate constant, k, of the first order reaction, is high in the 10.0 to 100 mg/l interval, which is coherent with the low value of the adsorption constant, K. The results fitted to the L-H model led to an equation that, within the range of concentrations studied here, theoretically allows one to evaluate the photodegradation rate.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:49:16Z No. of bitstreams: 1 S0100-46702005000300004.pdf: 675127 bytes, checksum: c99fb0ffa0e9bb3205952e7ef58c83ed (MD5) Made available in DSpace on 2013-08-22T18:49:16Z (GMT). No. of bitstreams: 1 S0100-46702005000300004.pdf: 675127 bytes, checksum: c99fb0ffa0e9bb3205952e7ef58c83ed (MD5) Previous issue date: 2005-09-01 Made available in DSpace on 2013-09-30T19:39:32Z (GMT). No. of bitstreams: 2 S0100-46702005000300004.pdf: 675127 bytes, checksum: c99fb0ffa0e9bb3205952e7ef58c83ed (MD5) S0100-46702005000300004.pdf.txt: 18744 bytes, checksum: 01023101c927cb95c7336799b54ed6f1 (MD5) Previous issue date: 2005-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:18:12Z No. of bitstreams: 2 S0100-46702005000300004.pdf: 675127 bytes, checksum: c99fb0ffa0e9bb3205952e7ef58c83ed (MD5) S0100-46702005000300004.pdf.txt: 18744 bytes, checksum: 01023101c927cb95c7336799b54ed6f1 (MD5) Made available in DSpace on 2014-05-20T14:18:12Z (GMT). No. of bitstreams: 2 S0100-46702005000300004.pdf: 675127 bytes, checksum: c99fb0ffa0e9bb3205952e7ef58c83ed (MD5) S0100-46702005000300004.pdf.txt: 18744 bytes, checksum: 01023101c927cb95c7336799b54ed6f1 (MD5) Previous issue date: 2005-09-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A hidroxiapatita [Ca10(PO4)6(OH)2, HA] foi sintetizada utilizando-se a rota sol-gel partindo-se de ácido fosfórico e nitrato de cálcio como precursores de cálcio e fósforo, respectivamente e como solvente utilizou-se o metanol na preparação do sol que posteriormente será utilizado na obtenção de recobrimentos de hidroxiapatita sobre substratos de ligas de titânio. O sol permaneceu estável e não ocorreu gelatinização em temperatura ambiente durante sete dias. O sol transformou-se em um gel branco somente após a remoção do solvente a 100ºC. O produto assim obtido foi calcinado em 300°C, 500°C e 700°C e caracterizou-se por DRX, FT-IR, MEV/EDS e TGA/DSC. As fases de HA sintetizada tornaram-se estáveis sem sub-produtos a 700°C. A difração de raios X mostrou que a estrutura apatita é aparente em 300°C. O tamanho do cristal e o teor de HA aumentaram com o aumento da temperatura de calcinação. A análise por MEV mostrou a presença de poros que são importantes para aplicações biomédicas, favorecendo a adesão entre o tecido ósseo neoformado e a apatita sintética, ou seja, osseointegração. Hydroxyapatite [Ca10(PO4)6(OH)2, HA] was synthesized using sol-gel route were used phosphoric acid and calcium nitrate as calcium and phosphorous precursors, respectively and as solvent was using the methanol in the preparation of the sol that later will be used in the obtention apatites coatings on titanium alloys substrates. The sol remained stable and no gelling occurred in ambient environment for over 7 days. The sol became a white gel only after the removal of the solvent at 100ºC. The product was calcined in 300°C, 500°C and 700°C and had been characterized by DRX, FT-IR, SEM/EDS and TGA/DSC. The synthesized HA became stable 700°C without any another product. X ray diffraction showed that structure apatite initially appeared at 300°C. The crystal size and the HA content increase with increasing calcination temperature. SEM analysis indicated the presence of pores that are important for biomedical applications, improving to the adhesion between neoformed bone tissue and synthesized apatite, i.e, osseointegration. Universidade Estadual Paulista Instituto de Química de Araraquara Universidade Estadual Paulista Instituto de Biociências de Botucatu Universidade Estadual Paulista Faculdade de Ciências Universidade Estadual Paulista Instituto de Química de Araraquara Universidade Estadual Paulista Instituto de Biociências de Botucatu Universidade Estadual Paulista Faculdade de Ciências

A hidroxiapatita [Ca10(PO4)6(OH)2, HA] foi sintetizada utilizando-se a rota sol-gel partindo-se de ácido fosfórico e nitrato de cálcio como precursores de cálcio e fósforo, respectivamente e como solvente utilizou-se o metanol na preparação do sol que posteriormente será utilizado na obtenção de recobrimentos de hidroxiapatita sobre substratos de ligas de titânio. O sol permaneceu estável e não ocorreu gelatinização em temperatura ambiente durante sete dias. O sol transformou-se em um gel branco somente após a remoção do solvente a 100ºC. O produto assim obtido foi calcinado em 300°C, 500°C e 700°C e caracterizou-se por DRX, FT-IR, MEV/EDS e TGA/DSC. As fases de HA sintetizada tornaram-se estáveis sem sub-produtos a 700°C. A difração de raios X mostrou que a estrutura apatita é aparente em 300°C. O tamanho do cristal e o teor de HA aumentaram com o aumento da temperatura de calcinação. A análise por MEV mostrou a presença de poros que são importantes para aplicações biomédicas, favorecendo a adesão entre o tecido ósseo neoformado e a apatita sintética, ou seja, osseointegração.Hydroxyapatite [Ca10(PO4)6(OH)2, HA] was synthesized using sol-gel route were used phosphoric acid and calcium nitrate as calcium and phosphorous precursors, respectively and as solvent was using the methanol in the preparation of the sol that later will be used in the obtention apatites coatings on titanium alloys substrates. The sol remained stable and no gelling occurred in ambient environment for over 7 days. The sol became a white gel only after the removal of the solvent at 100ºC. The product was calcined in 300°C, 500°C and 700°C and had been characterized by DRX, FT-IR, SEM/EDS and TGA/DSC. The synthesized HA became stable 700°C without any another product. X ray diffraction showed that structure apatite initially appeared at 300°C. The crystal size and the HA content increase with increasing calcination temperature. SEM analysis indicated the presence of pores that are important for biomedical applications, improving to the adhesion between neoformed bone tissue and synthesized apatite, i.e, osseointegration.

This paper discusses a rapid and sensitive method developed to determine trace levels of mercury in natural water samples by cold vapor atomic absorption spectrometry using a preconcentration system composed by mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT) coupled on-line with the spectrometer's cold vapor generator system. The optimum preconcentration conditions are also described here. The preconcentrated Hg(II) ions were eluted directly from the column to the spectrometer's cold vapor generator system using 100 µL of 2 mol L-1 hydrochloric acid and the retention efficiency achieved exceeded 95%. The enrichment factors determined were 29, 38 and 46 using 3, 4 and 5 mL of preconcentrated aqueous solutions containing 400 ng L-1 of Hg. The detection limit calculated was 5 ng L-1. The preconcentration procedure was applied to determine trace level mercury in spiked river water samples.O presente trabalho descreve o desenvolvimento de um método rápido e sensível para determinar traços de mercúrio em amostras de águas naturais por espectrometria de absorção atômica com geração de vapor a frio, utilizando-se um sistema de preconcentração composto por uma mini-coluna empacotada com 100 mg de sílica gel modificada com o ligante 2-aminotiazol e acoplado em linha com o sistema de geração de vapor a frio do espectrômetro de absorção atômica. As condições ótimas de preconcentração são descritas. Os íons Hg(II) preconcentrados foram eluídos diretamente da mini-coluna para o sistema de geração de vapor a frio utilizando-se 100 µL de solução 2 mol L-1 de ácido clorídrico, com uma eficiência de 95%. Os fatores de enriquecimento determinados foram 29, 38 e 46 percolando-se 3, 4 e 5 mL de solução aquosa contendo 400 ng L-1 de Hg(II). O limite de detecção calculado foi de 5 ng L-1. O procedimento de preconcentração foi aplicado na determinação de traços de mercúrio adicionados em amostras de águas de rio.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:49:16Z No. of bitstreams: 1 S0100-46702005000300006.pdf: 335371 bytes, checksum: 911f0121001e80fbe1609de232be0a88 (MD5) Made available in DSpace on 2013-08-22T18:49:16Z (GMT). No. of bitstreams: 1 S0100-46702005000300006.pdf: 335371 bytes, checksum: 911f0121001e80fbe1609de232be0a88 (MD5) Previous issue date: 2005-09-01 Made available in DSpace on 2013-09-30T19:09:23Z (GMT). No. of bitstreams: 2 S0100-46702005000300006.pdf: 335371 bytes, checksum: 911f0121001e80fbe1609de232be0a88 (MD5) S0100-46702005000300006.pdf.txt: 22554 bytes, checksum: a7165d37477b899b3e7a6ccfe26c7e68 (MD5) Previous issue date: 2005-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:19:42Z No. of bitstreams: 2 S0100-46702005000300006.pdf: 335371 bytes, checksum: 911f0121001e80fbe1609de232be0a88 (MD5) S0100-46702005000300006.pdf.txt: 22554 bytes, checksum: a7165d37477b899b3e7a6ccfe26c7e68 (MD5) Made available in DSpace on 2014-05-20T14:19:42Z (GMT). No. of bitstreams: 2 S0100-46702005000300006.pdf: 335371 bytes, checksum: 911f0121001e80fbe1609de232be0a88 (MD5) S0100-46702005000300006.pdf.txt: 22554 bytes, checksum: a7165d37477b899b3e7a6ccfe26c7e68 (MD5) Previous issue date: 2005-09-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) O presente trabalho descreve o desenvolvimento de um método rápido e sensível para determinar traços de mercúrio em amostras de águas naturais por espectrometria de absorção atômica com geração de vapor a frio, utilizando-se um sistema de preconcentração composto por uma mini-coluna empacotada com 100 mg de sílica gel modificada com o ligante 2-aminotiazol e acoplado em linha com o sistema de geração de vapor a frio do espectrômetro de absorção atômica. As condições ótimas de preconcentração são descritas. Os íons Hg(II) preconcentrados foram eluídos diretamente da mini-coluna para o sistema de geração de vapor a frio utilizando-se 100 µL de solução 2 mol L-1 de ácido clorídrico, com uma eficiência de 95%. Os fatores de enriquecimento determinados foram 29, 38 e 46 percolando-se 3, 4 e 5 mL de solução aquosa contendo 400 ng L-1 de Hg(II). O limite de detecção calculado foi de 5 ng L-1. O procedimento de preconcentração foi aplicado na determinação de traços de mercúrio adicionados em amostras de águas de rio. This paper discusses a rapid and sensitive method developed to determine trace levels of mercury in natural water samples by cold vapor atomic absorption spectrometry using a preconcentration system composed by mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT) coupled on-line with the spectrometer's cold vapor generator system. The optimum preconcentration conditions are also described here. The preconcentrated Hg(II) ions were eluted directly from the column to the spectrometer's cold vapor generator system using 100 µL of 2 mol L-1 hydrochloric acid and the retention efficiency achieved exceeded 95%. The enrichment factors determined were 29, 38 and 46 using 3, 4 and 5 mL of preconcentrated aqueous solutions containing 400 ng L-1 of Hg. The detection limit calculated was 5 ng L-1. The preconcentration procedure was applied to determine trace level mercury in spiked river water samples. UNESP Departamento de Química e Bioquímica Instituto de Biociências UNESP Departamento de Química Analítica Instituto de Química UNESP Departamento de Física e Biofísica Instituto de Biociências UNESP Departamento de Química e Bioquímica Instituto de Biociências UNESP Departamento de Química Analítica Instituto de Química UNESP Departamento de Física e Biofísica Instituto de Biociências

Univ Estadual Paulista Julio Mesquita Filho, Dept Quim & Bioquim, Inst Biociencias, BR-18618000 Botucatu, SP, Brazil

The lability of Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) complexed by humic substances (HSs) was investigated by means of ion exchange on cellulose modified with p-aminobenzoic groups (Cell-PAB), using a batch procedure. The HSs were extracted from water samples using adsorption in a column packed with XAD 8 resin. The metal-HS complexes were prepared by adding solutions containing all the aforementioned metal ions ( Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) ). The results indicated that the distribution coefficients (Kd) of Cell-PAB decreased with the presence of HSs, and that the lability of metal fractions complexed by HSs decreases in pH values > 4.0, complexation time > 10 h and HS concentration > 500 mg L-1. The metal exchange between HSs and Cell-PAB exhibited the following order of metal ion lability: Cd < Pb < Mn @ Cr < Cu.A labilidade de Cd, Cr, Cu, Mn e Pb complexados por substâncias húmicas aquáticas (HSs) foi investigada por estudos de troca iônica em batelada, utilizando-se celulose modificada com grupos p-aminobenzóico (Cell-PAB). As SHs foram extraídas de amostras de água por adsorção sobre coluna empacotada com resina XAD 8. Os complexos metal-HS foram preparados misturando-se soluções contendo SHs com soluções padrões mista dos íons metálicos (Cd, Cr, Cu, Mn e Pb). Os resultados obtidos indicaram que houve um decréscimo nos valores dos coeficientes de distribuição (Kd) da Cell-PAB com a adição das SHs nas soluções dos íons metálicos, e que a labilidade das frações metálicas complexadas pelas SHs é menor em valores de pH < 4,0, tempo de complexação > 10 h e concentração de SHs > 500 mg L-1 . A troca iônica entre a Cell-PAB e os complexos metal-SHs obedecem as seguintes ordens de labilidade: Cd < Pb < Mn @ Cr < Cu.

Este trabalho descreve um método de modificação do TiO2 obtido pelo processo sol-gel, através da adição de óxido de cério no momento da síntese. O material foi caracterizado por adsorção de N2 a 77K. A adição de CeO2 aumenta a área específica do catalisador em 135% e reduz o diâmetro de poros. A atividade catalítica desses materiais foi verificada frente à reação de foto-decomposição do hidrogenoftalato de potássio e comparada ao TiO2 comercial P25 da Degussa.This work describes the modification of the TiO2, obtained by sol-gel process, with the cerium oxide addition. The material was characterized by N2 adsorption at 77K. The addition of CeO2 increases the specific area in 135% and reduces the pores diameter of the catalyst. The catalytic activity was verified by reaction of decomposition of the potassium hidrogenphthalate. The results were compared to the TiO2 P25 (Degussa).

Made available in DSpace on 2021-07-14T10:47:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-06. Added 1 bitstream(s) on 2021-07-14T11:38:26Z : No. of bitstreams: 1 S1516-14392004000200018.pdf: 573761 bytes, checksum: 42242962d0d66c3568f27dcb139d2df1 (MD5) This paper describes the synthesis and characterization of p-aminobenzoic modified cellulose (Cell-PAB), as well as the separation and preconcentration of Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) ions from an aqueous medium using a Cell-PAB bath and the column technique. The quantity of p-aminobenzoic groups attached to the cellulose surface, i.e., 1.81±0.04 mmol/g, was determined by elemental analysis. The FT-IR spectra of Cell-PAB revealed characteristic bands of p-aminobenzoic groups, indicating the desired functionalization of the cellulose surface. The adsorptive capacities for the metals (Ns) Cd, Cu, Ni, Pb and Zn (Ns) were, respectively, 1.72 ± 0.02, 1.96 ± 0.02, 1.88 ± 0.04, 2.01 ± 0.03 and 1.93 ± 0.03 mmol/g. Metal separations performed in flow experiments using a column packed with 1 g of Cell-PAB and 5 mL of 1.5 mol/L HCl solution as eluent achieved an almost 100% metal ions recovery rate. Universidade Estadual Paulista, Dept. of Chemistry and Biochemistry Universidade Estadual Paulista, Dept. of Analytical Chemistry Universidade Estadual Paulista, Dept. of Chemistry and Biochemistry Universidade Estadual Paulista, Dept. of Analytical Chemistry

This work describes a modified sol-gel method for the preparation of V2O5/TiO2 catalysts. The samples have been characterized by N2 adsorption at 77K, x-ray diffractometry (XRD) and Fourier Transform Infrared (FT-IR). The surface area increases with the vanadia loading from 24 m² g-1, for pure TiO2, to 87 m² g-1 for 9wt.% of V2O5. The rutile form is predominant for pure TiO2 but became enriched with anatase phase when vanadia loading is increased. No crystalline V2O5 phase was observed in the catalysts diffractograms. Two species of surface vanadium observed by FT-IR spectroscopy a monomeric vanadyl and polymeric vanadates, the vanadyl/vanadate ratio remains practically constant.

A structural study of CuO supported on a CeO2–TiO2 system was undertaken using X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) techniques. The results of XRD revealed the presence of only two phases, TiO2 anatase and CeO2 cerianite. A trend towards smaller TiO2 crystallites was observed when cerium content increased. When the amount of cerium increased, Ti K-edge XANES analysis showed an increasing distortion of Ti sites. The results of Ce LIII-edge EXAFS showed that Ce atoms are coordinated by eight oxygen atoms at 2.32 A. For the sample containing a small amount of cerium, the EXAFS analysis indicated that the local structure around Ce atoms was highly distorted. The catalysts presented quite different Cu K-edge XANES spectra compared to the spectra of the CuO and Cu2O reference compounds. The Cu–O mean bond length was close to that of the CuO and the Cu atoms in the catalysts are surrounded by approximately four oxygen atoms in their first shell. Copper supported on the ceria-modified titania support catalysts displayed a better performance in the methanol dehydrogenation when compared to copper supported only on titania or on ceria.

Univ Estadual Paulista Julio Mesquita Filho, Dept Quim & Bioquim, BR-18618000 Botucatu, SP, Brazil

Raman spectroscopy and Electron Paramagnetic Resonance (EPR) studies were performed on a series of V2O5/TiO2 catalysts prepared by a modified sol-gel method in order to identify the vanadium species. Two species of surface vanadium were identified by Raman measurements, monomeric vanadyls and polymeric vanadates. Monomeric vanadyls are characterized by a narrow Raman band at 1030 cm−1 and polymeric vanadates by two broad bands in the region from 900 to 960 cm−1 and 770 to 850 cm−1. The Raman spectra do not exhibit characteristic peaks of crystalline V2O5. These results are in agreement with those of X-ray Diffractometry (XRD) and Fourier Transform Infrared (FT-IR) previously reported (C.B. Rodella et al., J. Sol-Gel Sci. Techn., submitted). At least three families of V4+ ions were identified by EPR investigations. The analysis of the EPR spectra suggests that isolated V4+ ions are located in sites with octahedral symmetry substituting for Ti4+ ions in the rutile structure. Magnetically interacting V4+ ions are also present as pairs or clusters giving rise to a broad and structureless EPR line. At higher concentration of V2O5, a partial oxidation of V4+ to V5+ is apparent from the EPR results.

The K to 12 curriculum has already been implemented and part and parcel of it is the MTB-MLE program in which the mother tongue of the learner is used as a medium of instruction and also taken as a subject. As this program advocates the instilling of cultural heritage in the learner, this study explores on integrating local literature (Cordilleran) in the teaching of English. This is done by looking at several factors affecting the choices of teachers, determining the weaknesses of the learners particularly in English grammar awareness, and creating a sample appropriate activity to address the identified weak areas. Data were collected primarily via survey, inter-rater and summative tests and treated through descriptive statistics. Results show that values laden, motivational, in line with the subject matter, substantial, and culturally relevant literary pieces top the line of preferred literature. Also, results of the test in determining weak areas show a big percentage of learners finding the test on identified competencies easy. However, percentage of those who find it difficult is still at an alarming level. Resulting to this is the making of a sample activity created with special emphasis on illustrative activities. The local literature is selectively integrated in the prototype lesson guide issued to the teachers in line with the objectives and the theme embracing each of the given activities.

Structural and textural studies of a CuO/TiO2 system modified by cerium oxide were conducted using Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N2 absorption (BET specific surface area). The introduction of a minor amount of CeO2 (Ce0.09Ti0.82O1.91Cu0.09 sample) resulted in a material with the maximum surface area value. The results of Raman spectroscopy revealed the presence of only two crystalline phases, TiO2 anatase and CeO2 cerianite, with well-dispersed copper species. TEM micrographs showed a trend toward smaller TiO2 crystallites when the cerium oxide content was increased. The XPS analysis indicated the rise of a second peak in Ti 2p spectra with the increasing amount of CeO2 located at higher binding energies than that due to the Ti4+ in a tetragonal symmetry. The CuO/TiO2 system modified by CeO2 displayed a superior performance for methanol dehydrogenation than the copper catalyst supported only on TiO2 or CeO2.

Samples of the V 2 O 5 /TiO 2 system were prepared by the sol-gel method and calcined at different temperatures. Surface species of vanadium, their dispersion, as well as the structural evolution of the system were analysed by XRD, Raman, EPR. and XPS techniques. The results of XRD showed the evolution of TiO 2 from anatase phase to rutile phase. The Raman spectra for calcination temperatures up to 500 °C showed a good dispersion of vanadium over titania in the form of monomeric vanadyl groups (V 4+ ) and polymeric vanadates (V 5+ ). At least three families of V 4+ ions were identified by EPR investigations. Two kinds of isolated V 4+ species are placed in sites of octahedral symmetry, substituting Ti 4+ in the rutile phase. The third is formed by pairs of V 4+ species on the surface of titania. Above 500 °C part of superficial V 4+ is inserted into the matrix of titania and part is oxidized to V 5+ . The XPS results showed that the V/Ti ratio rises with increasing calcination temperature, indicating a smaller dispersion of vanadium.

Univ Sao Paulo, Inst Fis Sao Carlos, Dept Fis & Ciencia Mat, BR-13560970 Sao Carlos, SP, Brazil

Electrical conductivity and 1 H Nuclear Magnetic Resonance (NMR) techniques were used to investigate the ion-exchanged layered lead-niobate perovskite HPb 2 Nb 3 O 10 · n H 2 O, over the temperature range 90–350 K. Compounds were synthesized by the sol–gel method and calcinated at 650°C. Analysis of the NMR data gives activation energies for the proton motion in the range 0.14–0.40 eV, which are dependent on the water content. The frequency and temperature dependencies of the proton spin–lattice relaxation times show that the character of the motion of the water molecules is essentially two-dimensional, reflecting the layered structure of the material. The 1 H line-narrowing transition and the single spin–lattice relaxation rate maximum, observed in the hydrated compounds, are consistent with a Grotthuss-like mechanism for the proton diffusion.

The hydrogen evolution reaction (HER) was studied on Ni–LaNi 5 and Ni–MmNi 3.4 Co 0.8 Al 0.8 electrode materials in 1 mol dm −3 NaOH solution. The steady-state polarization curves and electrochemical impedance spectroscopy experimental data showed a pronounced improvement in HER kinetics when these electrode materials were used. The electrochemical results are in accordance with the Volmer–Heyrovsky mechanism. The kinetic results indicate a more effective improvement in the Heyrovsky step, suggesting an electrocatalytic synergistic effect of the hyper-electronic character of the Ni and the hypo-electronic character of the rare-earth element on the electrode surface.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:02:42Z No. of bitstreams: 1 S0366-69132007000200016.pdf: 577996 bytes, checksum: bd8beb5093475f4a60fee787b269113b (MD5) Made available in DSpace on 2013-08-22T19:02:42Z (GMT). No. of bitstreams: 1 S0366-69132007000200016.pdf: 577996 bytes, checksum: bd8beb5093475f4a60fee787b269113b (MD5) Previous issue date: 2007-06-01 Made available in DSpace on 2013-09-30T20:03:55Z (GMT). No. of bitstreams: 2 S0366-69132007000200016.pdf: 577996 bytes, checksum: bd8beb5093475f4a60fee787b269113b (MD5) S0366-69132007000200016.pdf.txt: 26399 bytes, checksum: dcf448b637af8ff69ad1c4f7ea89dd91 (MD5) Previous issue date: 2007-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:16:24Z No. of bitstreams: 2 S0366-69132007000200016.pdf: 577996 bytes, checksum: bd8beb5093475f4a60fee787b269113b (MD5) S0366-69132007000200016.pdf.txt: 26399 bytes, checksum: dcf448b637af8ff69ad1c4f7ea89dd91 (MD5) Made available in DSpace on 2014-05-20T15:16:24Z (GMT). No. of bitstreams: 2 S0366-69132007000200016.pdf: 577996 bytes, checksum: bd8beb5093475f4a60fee787b269113b (MD5) S0366-69132007000200016.pdf.txt: 26399 bytes, checksum: dcf448b637af8ff69ad1c4f7ea89dd91 (MD5) Previous issue date: 2007-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) O método precursor polimérico foi aplicado para a síntese de pós de Ti x(Sm0,2Ce0,8)1 xO2-delta, com 0 < x < 0,5, com tratamento nas temperaturas de 400 ºC, 700 ºC e 1000 ºC. A caracterização foi feita por difração de raios X e o refinamento estrutural pelo método de Rietveld. A inserção do titânio tende a aumentar a deformação da rede da estrutura cristalina, que não é eliminada até a temperatura de 700 ºC. Nestas condições as amostras ainda se mostraram monofásicas como cerianita. Para as amostras tratadas a 1000 ºC, a deformação provocada pela introdução do titânio é suprimida e a solubilidade do titânio na cerianita se limita a valores de x < 0,05. O excedente precipita-se como única fase secundária de titanato de samário para valores de 0,5 < x < 0,20. Quando x excede este valor, observa-se também a precipitação da fase rutila. Paralelamente, há uma diminuição da fase titanato de samário e a re-incorporação do samário pela cerianita, sendo que esta é comprovada pelo aumento dos parâmetros de rede da cerianita. Powders of Ti x(Sm0.2Ce0.8)1-xO 2-delta, 0 < x < 0.5, were synthesized by the polymeric precursor method. The treatment temperature ranged between 400 and 1000 ºC. The characterization was carried out by X-ray diffraction and the structural refinement study by the Rietveld method. The titanium addition tends to increase the lattice deformation of the crystalline structure, which is not eliminated until the treatment at 700 ºC. Under these conditions, the samples are single phase, cerianite. In the samples treated at 1000 ºC the lattice deformation was suppressed segregating titanium as samarium titanate and rutile, depending on x. The solubility of titanium is limited to x < 0.05. When titanium contents exceed x = 0.05, only samarium titanate precipitates as secondary phase up to x = 0.20. For higher titanium contents (x > 0.20) the rutile phase precipitates. At the same time the samarium titanate content decreases and samarium migrates into the cerianite phase. These phenomena can be proved by the increase in lattice parameters. UNESP Faculdade de Ciências Departamento de Química UNESP Instituto de Biociências UNESP Faculdade de Ciências Departamento de Química UNESP Instituto de Biociências

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:21:56Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:33:22Z : No. of bitstreams: 1 2-s2.0-33746714342.pdf: 155785 bytes, checksum: 7a2733b8a2fb9dcdc89faf3f39d01814 (MD5) Made available in DSpace on 2014-05-27T11:21:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-09 This paper describes results of the photo-degradation of three types of soluble and emulsive cutting fluids in an aqueous medium, using TiO2 as catalyst in suspension and UV radiation. The TiO2 proved to be an effective catalyst for the degradation of the cutting fluids investigated. The degradation rate depends on pH and nature of the fluids. The best performance of catalyst was observed at pH 8.0 for all the fluids when most of 70% of the organic load was decomposed. ©2006 Sociedade Brasileira de Química. Departamento de Química IB Universidade Estadual Paulista, CP 510, 18618-000 Botucatu-SP Instituto de Química Universidade Estadual Paulista, CP 355, 14800-900 Araraquara-SP Departamento de Química Centro Federal de Educação Tecnológica do Maranhão CEFET, Av. Getúlio Vargas, 04, 65025001 São Luís-MA Centro de Recursos Hídricos e Ecologia Aplicada EESC Universidade de São Paulo, CP 359, 13566-590 São Carlos-SP Departamento de Química IB Universidade Estadual Paulista, CP 510, 18618-000 Botucatu-SP Instituto de Química Universidade Estadual Paulista, CP 355, 14800-900 Araraquara-SP

This work describes the synthesis and characterization of 2-aminothiazole-modified titania and its application on Hg (II) photoreduction in aqueous medium. Infrared spectroscopy confirmed the chemical modification of the titania matrix. The number of 2-aminothiazole groups attached to the titania was determined by Kjeldahl's method. The photocatalytic experiments were carried out in a cylindrical photoreactor thermostatted at 298 K. The resulting modified photocatalyst 2-aminothiazole titania (TiAT) revealed an enhance in the Hg (II) photoreduction capacity at studied pH values (3, 7 and 9). In addition, sorption studies showed that the photocatalyst TiAT presented a lower equilibrium time and a higher sorption capacity of Hg(II) ion, demonstrating that sorption plays a fundamental role in the photoreduction mechanism. Este trabalho descreve a síntese e caracterização da titânia modificada pelo ligante 2-aminotiazol e sua aplicação na foto-redução de íons Hg (II) em meio aquoso. Espectros obtidos na região do infravermelho confirmaram a modificação química da matriz de titânia. A quantidade de grupos 2-aminotiazol ligados à superfície da titânia foi determinada por meio da análise de nitrogênio, utilizando-se o método de Kjeldahl. Todos os experimentos de foto-redução foram feitos em um foto-reator cilíndrico termostatizado a 298 K. O catalisador modificado, 2-aminotiazol titânia (TiAT), apresentou maior capacidade de foto-redução dos íons Hg(II) nos valores de pH estudados (3, 7 e 9). Além disso, os estudos de sorção mostraram que o TiAT apresentou um menor tempo de equilíbrio e uma maior capacidade de sorção dos íons Hg(II), demonstrando que o processo de sorção desempenha um papel fundamental no mecanismo de foto-redução.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:49:16Z No. of bitstreams: 1 S0100-46702005000400001.pdf: 284119 bytes, checksum: 63bef5de0acef8e019bdf2105b44297f (MD5) Made available in DSpace on 2013-08-22T18:49:16Z (GMT). No. of bitstreams: 1 S0100-46702005000400001.pdf: 284119 bytes, checksum: 63bef5de0acef8e019bdf2105b44297f (MD5) Previous issue date: 2005-01-01 Made available in DSpace on 2013-09-30T19:39:33Z (GMT). No. of bitstreams: 2 S0100-46702005000400001.pdf: 284119 bytes, checksum: 63bef5de0acef8e019bdf2105b44297f (MD5) S0100-46702005000400001.pdf.txt: 22774 bytes, checksum: fb59efd7cb997333eab29f1d5c46666b (MD5) Previous issue date: 2005-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:53:25Z No. of bitstreams: 2 S0100-46702005000400001.pdf: 284119 bytes, checksum: 63bef5de0acef8e019bdf2105b44297f (MD5) S0100-46702005000400001.pdf.txt: 22774 bytes, checksum: fb59efd7cb997333eab29f1d5c46666b (MD5) Made available in DSpace on 2014-05-20T13:53:25Z (GMT). No. of bitstreams: 2 S0100-46702005000400001.pdf: 284119 bytes, checksum: 63bef5de0acef8e019bdf2105b44297f (MD5) S0100-46702005000400001.pdf.txt: 22774 bytes, checksum: fb59efd7cb997333eab29f1d5c46666b (MD5) Previous issue date: 2005-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Este trabalho descreve um método de modificação do TiO2 obtido pelo processo sol-gel, através da adição de óxido de cério no momento da síntese. O material foi caracterizado por adsorção de N2 a 77K. A adição de CeO2 aumenta a área específica do catalisador em 135% e reduz o diâmetro de poros. A atividade catalítica desses materiais foi verificada frente à reação de foto-decomposição do hidrogenoftalato de potássio e comparada ao TiO2 comercial P25 da Degussa. This work describes the modification of the TiO2, obtained by sol-gel process, with the cerium oxide addition. The material was characterized by N2 adsorption at 77K. The addition of CeO2 increases the specific area in 135% and reduces the pores diameter of the catalyst. The catalytic activity was verified by reaction of decomposition of the potassium hidrogenphthalate. The results were compared to the TiO2 P25 (Degussa). UNESP Departamento de Química e Bioquímica UNESP Instituto de Química UFMS Departamento de Física UNESP Departamento de Química e Bioquímica UNESP Instituto de Química

This work describes the synthesis and characterization of 2-aminothiazole modified silica gel (SiAT), and the results of a study of the adsorption and pre-concentration (in batch and using a flow-injection system coupled to an absorption atomic spectrometer) of Cu(II), Ni(II) and Pb(II) in aqueous medium. The adsorption capacities for each metal ions in mmol g-1 were: Cu(II)= 1.18, Ni(II)= 1.15 and Pb(II)= 1.10. The results obtained in the flow experiments showed a recovery of practically 100% of the metal ions adsorbed in a mini-column packed with 100 mg of SiAT, using 100 µL of 2.0 mol L-1 HCl solution as eluent. The sorption-desorption of the metal ions made possible the application of a flow-injection system for the pre-concentration and quantification by FAAS of metal ions at trace level in natural water samples digested and not digest by an oxidizing UV photolysis. Este trabalho descreve a síntese e caracterização da sílica gel modificada com grupos 2-aminotiazol (SiAT), e os resultados de um estudo de adsorção e pré-concentração (em batelada e em fluxo, utilizando-se um sistema por injeção em fluxo acoplado com um espectrômetro de absorção atômica) de Cu(II), Ni(II) e Pb(II) em meio aquoso. A capacidade máxima de adsorção da SiAT determinada para os íons metálicos estudados em mmol g-1 foram: Cu(II)= 1,18, Ni(II)= 1,15 and Pb(II)= 1,10. Os resultados obtidos nos experimentos em fluxo, mostraram uma recuperação de praticamente 100% dos íons metálicos adsorvidos em uma mini-coluna empacotada com 100 mg de SiAT, utilizando-se 100 µL de HCl 2 mol L-1 como eluente. A sorção-desorção quantitativa dos íons Cu(II), Ni(II) e Pb(II), permitiu a aplicação do sistema em fluxo na pré-concentração e posterior quantificação desses íons metálicos em amostras de águas naturais digeridas e não digeridas por oxidação com radiação UV.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:49:10Z No. of bitstreams: 0 Made available in DSpace on 2013-08-22T18:49:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-01-01 Made available in DSpace on 2013-09-30T19:39:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:53:23Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T13:53:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Este trabalho teve por objetivo utilizar o hidrogenoftalato de potássio como molécula modelo para estudos de adsorção em TiO2. Os resultados de adsorção do hidrogeneoftalato sobre TiO2 se ajustaram aos modelos de adsorção propostos por Langmuir e Freundlich, sendo que o modelo de Freundlich descreveu melhor o fenômeno. A adsorção foi função da temperatura e a capacidade de adsorção aumentou de 2,4 para 4,5 mg.g-1 quando se elevou a temperatura de 20 para 30ºC. The aim of the work was to use the potassium hYdrogenphthalate as molecule model for adsorption studies on TiO2. The results of adsorption of the hydrogenphthalate on TiO2 were fitted to the models proposed by Langmuir and Freundlich, but the model of Freundlich described better the phenomenon. The adsorption was a function of the temperature and the capacity of adsorption increased from 2,4 to 4,5 mg.g-1 when the temperature was increased from 20 to 30 ºC. UNESP IB Departamento de Química e Bioquímica UNESP IB Departamento de Química e Bioquímica

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:20:25Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:45:02Z : No. of bitstreams: 1 2-s2.0-0036519768.pdf: 449177 bytes, checksum: 3de6fa7e337698b4ce898c89a15644bb (MD5) Made available in DSpace on 2014-05-27T11:20:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2002-03-01 This work describes a modified sol-gel method for the preparation of V 2O 5/TiO 2 catalysts. The samples have been characterized by N 2 adsorption at 77K, x-ray diffractometry (XRD) and Fourier Transform Infrared (FT-IR). The surface area increases with the vanadia loading from 24 m 2 g -1, for pure TiO 2, to 87 m 2 g -1 for 9wt.% of V 2O 5. The rutile form is predominant for pure TiO 2 but became enriched with anatase phase when vanadia loading is increased. No crystalline V 2O 5 phase was observed in the catalysts diffractograms. Two species of surface vanadium observed by FT-IR spectroscopy a monomeric vanadyl and polymeric vanadates, the vanadyl/vanadate ratio remains practically constant. Instituto de Física de São Carlos Universidade de São Paulo, CP 369, 13560-970 São Carlos - SP Departamento de Química Faculdade de Ciências Universidade Estadual Paulista Júlio de Mesquita Filho, CP 473, 17001-970 Bauru - SP Departamento de Química e Bioquímica Instituto de Bioquímica Universidade Estadual Paulista Júlio de Mesquita Filho, CP 510, 18618-000 Botucatu - SP Departamento de Química Faculdade de Ciências Universidade Estadual Paulista Júlio de Mesquita Filho, CP 473, 17001-970 Bauru - SP Departamento de Química e Bioquímica Instituto de Bioquímica Universidade Estadual Paulista Júlio de Mesquita Filho, CP 510, 18618-000 Botucatu - SP

X-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and x-ray absorption spectroscopy (XAS) techniques have been applied to characterize the surface composition and structure of a series of CuO–TiO2–CeO2 catalysts. For a small loading of cerium, ceria was mainly dispersed on the titania surface and a minor amount of CeO2 crystallite appeared. At higher loading of cerium, the CeO2 phase increased and the atomic Ce/Ti ratio values were smaller than the nominal composition, as a consequence of cerium agglomeration. This result suggests that only a fraction of cerium can be spread on the titania surface. For titanium-based mixed oxide, we observed that cerium is found as Ce3+ uniquely on the surface. The atomic Cu/(Ce+Ti) ratio values showed no influence from cerium concentration on the dispersion of copper, although the copper on the surface was shown to be dependent on the cerium species. For samples with a high amount of cerium, XPS analysis indicated the raise of second titanium species due c...

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:48:21Z No. of bitstreams: 1 S0100-40421997000100003.pdf: 470100 bytes, checksum: 4f58a7353ddf79ad0bfb9db27d7c3d1f (MD5) Made available in DSpace on 2013-08-22T18:48:21Z (GMT). No. of bitstreams: 1 S0100-40421997000100003.pdf: 470100 bytes, checksum: 4f58a7353ddf79ad0bfb9db27d7c3d1f (MD5) Previous issue date: 1997-02-01 Made available in DSpace on 2013-09-30T19:38:11Z (GMT). No. of bitstreams: 2 S0100-40421997000100003.pdf: 470100 bytes, checksum: 4f58a7353ddf79ad0bfb9db27d7c3d1f (MD5) S0100-40421997000100003.pdf.txt: 18287 bytes, checksum: 2e99f87942e0aed6c3ce47e55ceec18a (MD5) Previous issue date: 1997-02-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:10:15Z No. of bitstreams: 2 S0100-40421997000100003.pdf: 470100 bytes, checksum: 4f58a7353ddf79ad0bfb9db27d7c3d1f (MD5) S0100-40421997000100003.pdf.txt: 18287 bytes, checksum: 2e99f87942e0aed6c3ce47e55ceec18a (MD5) Made available in DSpace on 2014-05-20T15:10:15Z (GMT). No. of bitstreams: 2 S0100-40421997000100003.pdf: 470100 bytes, checksum: 4f58a7353ddf79ad0bfb9db27d7c3d1f (MD5) S0100-40421997000100003.pdf.txt: 18287 bytes, checksum: 2e99f87942e0aed6c3ce47e55ceec18a (MD5) Previous issue date: 1997-02-01 HZSM5 zeolite was modified by exchanging proton by niobium (V). Several samples were obtained with various degrees of exchange. Pore volumes and acidity were measured to characterize these exchanged zeolites. Catalytic properties were evaluated with two reaction tests: m-xylene transformation and n-heptane cracking. The introduction of niobium on HZSM5 zeolite decreases the diffusion coefficient of 2-methyl-pentane and increases the zeolite acidity. The sample containing niobium are initially more active in cracking of n-heptane and m-xylene isomerization than HZSM5 alone. Universidade Estadual Paulista Departamento de Química URA CNRS 350 Catalyse en Chimie Organique Universidade Estadual Paulista Departamento de Química

Nb2O5 prepared by a sol-gel process in the form of coatings are new materials which have outstanding properties: (1) The coatings present electrochromic properties and exhibit a blue coloration under Li+ insertion with 100% reversible variation of the optical transmission in the visible and near infrared range between 80% and 20% and have a high chemical stability (tested up to 2000 cycles). (2) They are semiconductors and present a photoelectric effect when illuminating in the UV region ((lambda) < 360 nm). These films are therefore very promising for use in electrochromic devices and as electrodes for photoelectrochemical purposes and the development of nanocrystalline solar cells.

Nb2O5 prepared by a sol-gel process in form of coatings and aerogels are new materials which present interesting properties: (a) the coatings present electrochromic properties and exhibit a blue coloration under Li+ insertion with 100% reversible variation of the optical transmission in the visible and near infrared range between 80% and 20% and have a high chemical stability (tested up to 2000 cycles), (b) they are semiconductor and present a photoelectric effect when illuminating in the UV region ((lambda) < 360 nm). These films are therefore very promising to be used in electrochromic devices, as electrodes for photoelectrochemical purpose and the development of nanocrystalline solar cell, and (c) when prepared in aerogel form, the high BET surface area of the powders is a promising asset to use these new materials for catalytic purposes.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:49:15Z No. of bitstreams: 1 S0100-46702005000200006.pdf: 278497 bytes, checksum: 042ca956321d13239095abe08d108071 (MD5) Made available in DSpace on 2013-08-22T18:49:15Z (GMT). No. of bitstreams: 1 S0100-46702005000200006.pdf: 278497 bytes, checksum: 042ca956321d13239095abe08d108071 (MD5) Previous issue date: 2005-01-01 Made available in DSpace on 2013-09-30T19:09:23Z (GMT). No. of bitstreams: 2 S0100-46702005000200006.pdf: 278497 bytes, checksum: 042ca956321d13239095abe08d108071 (MD5) S0100-46702005000200006.pdf.txt: 19923 bytes, checksum: 8e2c0e4c743e60e36ffb5ae3f9d8d08f (MD5) Previous issue date: 2005-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T14:19:42Z No. of bitstreams: 2 S0100-46702005000200006.pdf: 278497 bytes, checksum: 042ca956321d13239095abe08d108071 (MD5) S0100-46702005000200006.pdf.txt: 19923 bytes, checksum: 8e2c0e4c743e60e36ffb5ae3f9d8d08f (MD5) Made available in DSpace on 2014-05-20T14:19:42Z (GMT). No. of bitstreams: 2 S0100-46702005000200006.pdf: 278497 bytes, checksum: 042ca956321d13239095abe08d108071 (MD5) S0100-46702005000200006.pdf.txt: 19923 bytes, checksum: 8e2c0e4c743e60e36ffb5ae3f9d8d08f (MD5) Previous issue date: 2005-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A labilidade de Cd, Cr, Cu, Mn e Pb complexados por substâncias húmicas aquáticas (HSs) foi investigada por estudos de troca iônica em batelada, utilizando-se celulose modificada com grupos p-aminobenzóico (Cell-PAB). As SHs foram extraídas de amostras de água por adsorção sobre coluna empacotada com resina XAD 8. Os complexos metal-HS foram preparados misturando-se soluções contendo SHs com soluções padrões mista dos íons metálicos (Cd, Cr, Cu, Mn e Pb). Os resultados obtidos indicaram que houve um decréscimo nos valores dos coeficientes de distribuição (Kd) da Cell-PAB com a adição das SHs nas soluções dos íons metálicos, e que a labilidade das frações metálicas complexadas pelas SHs é menor em valores de pH < 4,0, tempo de complexação > 10 h e concentração de SHs > 500 mg L-1 . A troca iônica entre a Cell-PAB e os complexos metal-SHs obedecem as seguintes ordens de labilidade: Cd < Pb < Mn @ Cr < Cu. The lability of Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) complexed by humic substances (HSs) was investigated by means of ion exchange on cellulose modified with p-aminobenzoic groups (Cell-PAB), using a batch procedure. The HSs were extracted from water samples using adsorption in a column packed with XAD 8 resin. The metal-HS complexes were prepared by adding solutions containing all the aforementioned metal ions ( Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) ). The results indicated that the distribution coefficients (Kd) of Cell-PAB decreased with the presence of HSs, and that the lability of metal fractions complexed by HSs decreases in pH values > 4.0, complexation time > 10 h and HS concentration > 500 mg L-1. The metal exchange between HSs and Cell-PAB exhibited the following order of metal ion lability: Cd < Pb < Mn @ Cr < Cu. UNESP Instituto de Química Departamento de Química Analítica UNESP Intitutto de Biociências Departamento de Física e Biofísica UNESP Instituto de Biociência Departamento de Química e Bioquímica UNESP Instituto de Química Departamento de Química Analítica UNESP Intitutto de Biociências Departamento de Física e Biofísica UNESP Instituto de Biociência Departamento de Química e Bioquímica

A case of hyperinfection with Strongyloides stercoralis in a young Sri-Lankan girl is described. The patient had received prednisolone at 60–90 mg/day for 1 year for nephrotic syndrome and this prolonged corticosteroid treatment probably induced the heavy parasitic infection. Following administration of the anthelmintic, mebendazole, the patient’s general condition showed rapid improvement. The importance of screening patients for Strongyloides before commencing immunosuppressive therapy is emphasized.