Optical and electrical characterization of samaria-doped ceria

Ce(0.8)SM(0.2)O(1.9) and CeO(2) nanomaterials were prepared by a solution technique to produce an ultrafine particulate material with high sinterability. In this work, the structural characteristics, the photoluminescent behavior and the ionic conductivity of the synthesized materials are focused. The thermally decomposed material consists of less than 10 nm in diameter nanoparticles. The Raman spectrum of pure CeO(2) consists of a single triple degenerate F(2g) model characteristic of the fluorite-like structure. The full width at half maximum of this band decreases linearly with increasing calcination temperature. The photoluminescence spectra show a broadened emission band assigned to the ligand-to-metal charge-transfer states O -> Ce(4+). The emission spectra of the Ce(0.8)Sm(0.2)O(1.9) specimens present narrow bands arising from the 4G(5/2) -> (6)H(J) transitions (J = 5/2, 7/2, 9/2 and 11/2) of Sm(3+) ion due to the efficient energy transfer from the O -> Ce(4+) transitions to the emitter 4G(5/2) level. The ionic conductivity of sintered specimens shows a significant dependence on density. (C) 2009 Elsevier B.V. All rights reserved.

On the pH dependence of electroactivity of poly(methylene blue) films

The electrochemical behavior of poly(methylene blue) on different electrodes has been investigated by electrochemical quartz crystal microbalance and in situ spectrophotometric measurements coupled to cyclic voltammetry. Polymeric films were obtained potentiodynamically and the charge transport mechanism was analyzed. The electrochemical results show that polymer electroactivity depends not only on pH but also on the substrate. Charge compensation changes with both pH and the size of the anions showing a transition in the pH range of polymer pKa. It was demonstrated by spectroelectrochemical experiments that the electroactivity of the film depends on the radical/radical cation equilibrium. The potentials where the most electroactive species are formed have been determined. (C) 2009 Elsevier Ltd. All rights reserved.

Probing the dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution: use of solvatochromic indicators and thermal analysis

Although cellulose acetates, CAs, are extensively employed there is scant information about the systematic dependence of their properties on their degree of substitution, DS; this is the subject of the present work. Nine CAs samples, DS from 0.83 to 3.0 were synthesized; their films were prepared. The following solvatochromic probes have been employed in order to determine the empirical polarity, E (T)(33); ""acidity, alpha""; ""basicity, beta"", and ""dipolarity/polarizability, pi*"" of the casted films: 2,6-dichloro-4-(2,4,6-triphenyl-pyridinium-1-yl) phenolate, WB; 4-nitroaniline; 4-nitroanisole; 4-nitro-N,N-dimethylaniline; 2,6-diphenyl-4-(2,4,6-triphenyl-pyridinium-1-yl)phenolate, RB. Additionally, two systems, ethanol plus ethyl acetate (EtOH-EtAc), and cellulose plus cellulose triacetate, CTA, were employed as models for CAs of different DS. Regarding the model systems, the following was observed: (i) For EtOH-EtAc, the dependence of all solvatochromic parameters on the ""equivalent-DS"" of the binary mixture was non-linear because of preferential solvation; (ii) The dependence of E (T)(33) on equivalent DS of the cellulose-CTA films is linear, but the slope is smaller than that of the corresponding plot for CAs. This is attributed to the more efficient hydrogen bonding in the model system, a conclusion corroborated by IR measurements. The dependence of solvatochromic parameters of CAs on their DS is described by the simple equations; a consequence of the substitution of the OH by the ester group. The thermal properties of bulk CAs samples were investigated by DSC and TGA; their dependence on DS is described by simple equations. The relevance of these data to the processing and applications of CAs is briefly discussed.

3D roll-forming of hat-profile with variable depth and width

The use of roll-formed products in automotive, furniture, buildings etc. increases every year due to the low part-production cost and the complicated cross-sections that can be produced. The limitation with roll-forming until recent years is that one could only produce profiles with a constant cross-section in the longitudinal direction. About eight years ago ORTIC AB [1] developed a machine in which it was possible to produce profiles with a variable width (“3D roll-forming”) for the building industry. Experimental equipment was recently built for research and prototyping of profiles with variable cross-section in both width and depth for the automotive industry. The objective with the current study is to investigate the new tooling concept that makes it possible to roll-form hat-profiles, made of ultra high strength steel, with variable cross-section in depth and width. The result shows that it is possible to produce 3D roll-formed profiles with close tolerances.

Economia evolucionária e path dependence do investimento externo japonês: um estudo do Leste Asiático no período pré Segunda Guerra Mundial

A abertura da economia e o reinício das relações econômicas japonesas com o exterior e o processo de industrialização da economia japonesa na Era Meiji levaram o Japão a investir no exterior. Os investimentos japoneses no exterior cresceram preponderantemente no Leste Asiático, concentrando-se nessa área até o término da Segunda Guerra Mundial. A tese mostra que existem restrições de caráter institucional e histórico, que impõem limitações às empresas quanto ao leque de opções para investirem no exterior. Uma vez que as empresas japonesas fizeram a opção, impostas por aquelas restrições, de investir no Leste Asiático, feedbacks positivos, propiciados pelos eventos históricos e institucionais, geraram auto-reforços, levando a um resultado de inflexibilidade - lock-in - para sair dessa região. A tese comprova que explicar os investimentos externos japoneses pelo modelo de economia evolucionária, através do processo de path dependence, que incorpora o caráter institucional e histórico, é mais plausível do que as interpretações convencionais.

The effects of commodity dependence on the brazilian economy: a test of the dutch disease hypothesis

A doença holandesa tornou-se amplamente conhecida na década de 1960, quando a descoberta repentina de reservatórios de gás natural em território holandês, na região do mar do norte, transformou o país em uma economia rica em recursos. A desagradável consequência que proveio da recém-adquirida abundância de commodities foi o declínio da próspera indústria holandesa, que perdeu sua competitividade devido à valorização do florim holandês, como consequência do aumento do influxo de capital estrangeiro no país. Desde então este fenômeno tem sido observado em diversos países que possuem abundância de commodities. O objetivo desta tese é aplicar o modelo da doença holandesa ao Brasil, já que a maior economia da América latina poderá também ter de encarar a ameaça de se tornar prisioneira da “armadilha das commodities”, devido à sua abundância de recursos naturais. O autor revisa a bibliografia básica abordando o tema geral da doença holandesa e dá enfoque a estudos realizados anteriormente no Brasil. Além disso, os quatro maiores sintomas que caracterizam a doença holandesa são testados: (1) valorização das taxas de câmbio do real, (2) declínio do setor industrial, (3) crescimento do setor de serviços, e (4) aumento dos salários. Todos estes sintomas foram observados e podem ser comprovados através das abordagens de cointegração ou de correlação, com exceção do sintoma número dois. Ainda que estes resultados sejam significativos, há muito outros fatores determinantes que influenciam o desenvolvimento dos sintomas examinados, motivo pelo qual futuros estudos serão necessários para se obtiver conclusões definitivas sobre como o Brasil é afetado pela doença holandesa.

Mineralogy of the clay fraction of Alfisols in two slope curvatures: III - spatial variability

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