Luminescence enhancement of the Tb(III) ion with the thenoyltrifluoroacetonate ligand acting as an efficient sensitizer

The synthesis, structural investigation, and photophysical properties of the complex [Tb(TTA)(2)(NO(3)) (TPPO)(2)] are reported. Unlike the analog tris-diketonate complex [Tb(TTA)(3)(TPPO)(2)], the new complex presents abnormally high luminescence intensity centered on the terbium ion. Our results clearly suggest a higher energy transfer efficiency from the TEA antenna ligand to the Tb(III) ion in the bis-diketonate complex compared with that in the tris-diketonate complex. A mechanism involving the increasing of triplet state energy when one TTA ligand is replaced by the NO(3)(-) group in the first coordination sphere is suggested and experimentally investigated to explain the anomalous luminescence properties of the new complex [Tb(TTA)(2)(NO(3))(TPPO)(2)]. (C) 2010 Elsevier B.V. All rights reserved.

Automated two-dimensional separation flow system with electrochemical preconcentration, stripping, capillary electrophoresis and contactless conductivity detection for trace metal ion analysis

This paper describes the automation of a fully electrochemical system for preconcentration, cleanup, separation and detection, comprising the hyphenation of a thin layer electrochemical flow cell with CE coupled with contactless conductivity detection (CE-C(4)D). Traces of heavy metal ions were extracted from the pulsed-flowing sample and accumulated on a glassy carbon working electrode by electroreduction for some minutes. Anodic stripping of the accumulated metals was synchronized with hydrodynamic injection into the capillary. The effect of the angle of the slant polished tip of the CE capillary and its orientation against the working electrode in the electrochemical preconcentration (EPC) flow cell and of the accumulation time were studied, aiming at maximum CE-C(4)D signal enhancement. After 6 min of EPC, enhancement factors close to 50 times were obtained for thallium, lead, cadmium and copper ions, and about 16 for zinc ions. Limits of detection below 25 nmol/L were estimated for all target analytes but zinc. A second separation dimension was added to the CE separation capabilities by staircase scanning of the potentiostatic deposition and/or stripping potentials of metal ions, as implemented with the EPC-CE-C(4)D flow system. A matrix exchange between the deposition and stripping steps, highly valuable for sample cleanup, can be straightforwardly programmed with the multi-pumping flow management system. The automated simultaneous determination of the traces of five accumulable heavy metals together with four non-accumulated alkaline and alkaline earth metals in a single run was demonstrated, to highlight the potentiality of the system.

Temperature and common-ion effect on magnesium oxide (MgO) hydration

MgO based refractory castables draw wide technological interest because they have the versatility and installation advantages of monolithic refractories with intrinsic MgO properties, such as high refractoriness and resistance to basic slag corrosion. Nevertheless, MgO easily reacts with water to produce Mg(OH)(2), which is followed by a large volumetric expansion, limiting its application in refractory castables. In order to develop solutions to minimize this effect, a better understanding of the main variables involved in this reaction is required. In this work, the influence of temperature, as well as the impact of the chemical equilibrium shifting (known as the common-ion effect), on MgO hydration was evaluated. Ionic conductivity measurements at different temperatures showed that the MgO hydration reaction is accelerated with increasing temperature. Additionally, different compounds were added to evaluate their influence on the reaction rate. Among them, CaCl(2) delayed the reaction, whereas KOH showed an opposite behavior. MgCl(2) and MgSO(4) presented similar results and two other distinct effects, reaction delay and acceleration, which depended on their concentration in the suspensions. The results were evaluated by considering the kinetics and the thermodynamics of the reaction, and the mechanical damages in the samples that was caused by the hydration reaction. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Syntheses of Cross-Linking Agents, Molecular Modeling of Oligonucleotides and Polypeptide-Ion Complexes

Each section of this thesis will be subdivided into three parts encompassing all of the research in which I have been involved during the past three years. These will be referred to under the headings "Syntheses:' "Molecular Modeling," and "Cross-linking Efficiencies." Each of these subdivisions may have divisions within them when necessary in order to fully detail the research.

A politica fiscal no Brasil : limites e contradições : o caso do Estado do Espirito Santo

o estudo pretende contribuir para a análise da realidade brasileira, através do caso do Estado do Espírito Santo, no período compreendido entre 1946 a 1980, tentando demonstrar a dependência financeira dos governos estaduais refletida na perda de receitas próprias e da necessária autonomia para a sua utilização. Numa visão retrospect.iva observa-se uma excessiva tendência à centralização manifestada pelo federalismo brasileiro, principalmente, depois da Reforma Tribut.ária de 1967, que estabeleceu um rigoroso controle da União sobre as receitas tributárias e sobre a ação dos Estados- membros, reduzindo sua autonomia em matéria de legislação tributária. A centralização financeira e política fez com que os go- . , . vernos estaduais perdessem 8S prerrogativasanteriorrnente adquiridas e tivessem limitada sua autonomia em;matéria de politica fiscal. Tentou-se compensar a acentuada redução das receitas tributárias estaduais lnstituindo- se o mecanismo das transferências que, a despeito de suas funç5es redIstributi vas, impõe uma série de exig§ncias e determinações para a sua aplicação. A partir dessa constataç50 passa-se a analisar a política fiscal no Estado do Espírito Santo observando-se as administrações estaduais nesse período. Cheg~-se à conclusão de que as sucessivas crises financeiras ocorridas limitaram a formulação de uma política fiscal estadual. Com isso, constat3-se que os estados passaram a ser rneros agentes administrativos reproduzindo as decis5es maiores formuladas pelo governo federal. Em linhas gerais, tentou-se comprovar a dependência fi--

O uso gerencial das informações contábeis tratadas por métodos que reconhecem os efeitos das flutuações de preços sobre o patrimônio e resultado empresarial: uma verificação empírica

O objetivo central desta pesquisa foi o de explorar, descrever e discutir de que forma e em que extensão as empresas se utilizam das informações contábeis tratadas por mecanismos que considerem os reflexos das variações no poder aquisitivo da moeda (Inflação) e das flutuações específicas de preços sobre os resultado e patrimônio empresarial, nos seus sistemas de controles internos e, consequentemente, em seus processos de tomada de decisão, avaliação de desempenho e fixação de tendências para o empreendimento. Em função dos objetivos propostos, a operacionalização desta pesquisa foi desenvolvida em duas etapas. A primeira fase, de caráter qualitativo, constituiu-se no levantamento dos dados básicos necessários ao atingimento dos objetivos desejados, através da aplicação de questionários em 12 (doze) empresas. Através dos dados levantados, foi possível inferir-se que o sistema contábil configura-se na base primária dos relatórios gerenciais das empresas pesquisadas. o modelo da Correção Integral teve sua validade conceitual confirmada, não obstante algumas simpliflcações metodológicas adotadas e o problema da lnadequacidade do padrão monetário utilizado principalmente em 1990. Em que pese ter havido consenso na indicação das distorções provocadas pelo problema do indexador, apenas duas empresas adotaram mecanismos tendentes a anular seus efeitos. Uma importante constatação também, foi o fato de que nas empresas em que se utilizavam sistemas contábeis baseados na metodologia da Lei Societária, como fonte primária, para geração de relatórios gerenciais, as suas adminlstrações não utilizavam tais relatórios como suporte aos seus processos de tomada de decisão, como por exemplo, no processo de estabelecimento de preços. Ressalte-se, também, que o pouco conhecimento da filosofia conceitual e vantagens informativas do modelo da Contabilidade a Custo Corrente Corrigido, tem impedido a sua implantação de forma mais ampla. Saliente-se que 60% das empresas da amostra já se utilizam de mecanismos de avaliação de ativos não monetários, com base em valores correntes (captaçao dos efeitos das flutuações especificas de preços), só que restritos aos itens circulantes (estoques) . Este é, certamente, o caminho para a aplicação plena do modelo, principalmente no âmbito gerencial. A segunda fase, cujo enfoque direcionou-se aos aspectos quantitativos, através do cálculo de indicadores econômicos-financeiros extraídos das demonstrações contábeis das empresas pesquisadas, relativos ao exercício de 1990, e elaborados em consonân ia com as metodologias da Correção Integral e da Lei Societária, buscou-se , mediante análise comparativa, avaliar as pricipais distorções encolvidas, que corroboram, de certa forma, os comentários feitos no parágrafo anterior. A natureza exploratória deste assunto, com deslocamento da ênfase da análise quantitativa, e com enfoque estritamente gerencial, é que o diferencia dos demais desenvolvidos em tempos recentes. Além disso, apresenta como caraterística acessória a busca por informações sugestivas para o desenvolvimento de pesquisas futuras.

Long-term facial artery catheter implantation for serial arterial blood sampling and invasive arterial blood pressure measurement in horses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Quality of TEC Estimated with Mod Ion Using GPS and GLONASS Data

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of ion concentration of ionomer in electron injection layer of polymer light-emitting devices

Polymer light-emitting devices (PLEDs) with poly(2-methoxy-5-hexyloxy)-p-phenylenevinylene (OC1OC6-PPV) as the emissive layer were studied with an electron injection layer of ionomers consisting of copolymers of styrene and methylmethacrylate (PS/PMMA) with 3, 6 and 8 mol% degree of sulfonation. The ionomers were able to form very thin films over the emissive layer, with less than 30 nm. Additionally, the presence of ion pairs of ionomer suppresses the tendency toward dewetting of the thin film of ionomer (similar to 10 nm) which can cause malfunction of the device. The effect of the ionomers was investigated as a function of the ion content. The devices performance, characterized by their current density and luminance intensity versus voltage, showed a remarkable increase with the ionomer layer up to 6 mol% of ionic groups, decreasing after that for the 8 mol% ionomer device. The study of the impedance spectroscopy in the frequency range from 0.1 to 10(6) Hz showed that the injection phenomena dominate over the transport in the electroluminescent polymer bulk. (c) 2006 Elsevier B.V. All rights reserved.

Projected length annealing of etched Sm-152 ion tracks in apatite

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anisotropy of track revelation in epidote: Results of a step etching experiment with Kr-86 ion tracks

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Study of the potentiometric response of the doped spinel Li1.05Al0.02Mn1.98O4 for the optimization of a selective lithium ion sensor

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Photoluminescence of Eu(3+) ion in SnO(2) obtained by sol-gel

Photoluminescence data of Eu-doped SnO(2) xerogels are presented, yielding information on the symmetry of Eu(3+) luminescent centers, which can be related to their location in the matrix: at lattice sites, substituting to Sn(4+), or segregated at particles surface. Influence of doping concentration and/or particle size on the photoluminescence spectra obtained by energy transfer from the matrix to Eu(3+) sites is investigated. Results show that a better efficiency in the energy transfer processes is obtained for high symmetry Eu(3+) sites and low doping levels. Emission intensity from (5)D(0) -> (7)F(1) transition increases as the temperature is raised from 10 to 240 K, under excitation at 266 nm laser line, because in this transition the multiphonon emission becomes significant only above 240 K. As an extension of this result, we predict high effectiveness for room temperature operation of Eu-based optical communication devices. X-ray diffraction data show that the impurity excess inhibits particle growth, which may influence the asymmetry ratio of luminescence spectra.

Ab initio study and NMR analysis of the complexion of citric acid with ion lithium

Quantum mechanics calculations at the ab initio HF/3-21G* level were carried out with Nuclear Magnetic Resonance (NMR) measurements to characterize citric acid and lithium interactions. The results indicate the formation of a tridentate organometallic compound with one lithium and one citric acid molecule and a tridentate and bidentate compound of two lithium atoms and one citric acid molecule. The results are in agreement with the experimental and theoretical data. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Best practices for the implantation of ISO 14001 norms: a study of change management in two industrial companies in the Midwest region of the state of São Paulo - Brazil

Among the difficulties found in the implementation of ISO 14001 systems, resistance to change can always be found. It is mainly a consequence of the hurry to change, loss of focus, concentration of decision making at the level of top management, arbitrary imposition of objectives and results, faulty communication, and the absence of motivational and financial incentive for change.Therefore, the main objective of this paper is to present best practices with respect to the management of organizational change due to the implementation of ISO 14001 norms in two industrial companies in the Midwest region of the State of São Paulo - Brazil. (C) 2008 Elsevier Ltd. All rights reserved.