Crystallization process of amorphous GaSb films studied by Raman spectroscopy

Thermal annealings of amorphous gallium antimonide films were accompanied using Raman spectroscopy, both for stoichiometric and nonstoichiometric compositions. The films were prepared by flash evaporation on silicon substrates. Structural changes were induced by the heat treatments: an increasing degree of crystallization as a function of the annealing temperature is observed. Sb clusters are found to crystallize before GaSb does, and the dependence of the corresponding Raman peak intensity with the annealing temperature (occurring in two regimes) is explained. A mechanism for the crystallization of the amorphous GaSb is proposed, based on the prior migration of the Sb excess outside the GaSb region to be crystallized. © 1995 American Institute of Physics.

Caracterização experimental de sistemas mecânicos com comportamento não-linear

Pós-graduação em Engenharia Mecânica - FEIS

Monitoramento de integridade estrutural e de sistemas utilizando dispositivos de baixo custo

Pós-graduação em Engenharia Mecânica - FEB

Estudo de microscopia eletronica de varredura e transmissão de pregas vocais de idosos

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

Abordagem alternativa para síntese de melanina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da anemia ferropriva no eletroforetrograma de hemoglobina de leitões

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Gestão das línguas no século XXI: para uma introdução à política linguística exterior

The objective of this work is to stimulate a debate about the idea of a possible foreign language policy. It seeks to do so from an overview of the structural changes of recent decades - those affecting the economy, information and communication technologies, geopolitics and identities - in order to draw attention to the renewed importance and the role that the language management issues are assuming in this new context. Considering the foreign language policy a theoretical and practical essential tool for the management of language in a globalized world, the focus of the discussion rests on four main aspects: the origins of the notion of foreign language policy; the relationship with the foreign policy of the State; its effectiveness through the intervention on corpus, status and acquisition of the language; and the possibility of their formulation by agents other than the State

A voz do idoso: características clínicas, endoscópicas, vocais e morfológicas

Pós-graduação em Bases Gerais da Cirurgia - FMB

Association and Structure of Thermosensitive Comblike Block Copolymers in Aqueous Solutions

The structures and association properties of thermosensitive block copolymers of poly(methoxyoligo( ethylene glycol) norbornenyl esters) in D2O were investigated by small angle neutron scattering (SANS). Each block is a comblike polymer with a polynorbornene (PNB) backbone and oligo ethylene glycol (OEG) side chains (one side chain per NB repeat unit). The chemical formula of the block copolymer is (OEG3NB) 79- (OEG6.6NB) 67, where subscripts represent the degree of polymerization (DP) of OEG and NB in each block. The polymer concentration was fixed at 2.0 wt % and the structural changes were investigated over a temperature range between 25 and 68°C. It was found that at room temperature polymers associate to form micelles with a spherical core formed by the block (OEG3NB) 79 and corona formed by the block (OEG6.6NB) 67 and that the shape of the polymer in the corona could be described by the form factor of rigid cylinders. At elevated temperatures, the aggregation number increased and the micelles became more compact. At temperatures around the cloud point temperature (CPT) T ) 60 °C a correlation peak started to appear and became pronounced at 68 °C due to the formation of a partially ordered structure with a correlation length ∼349 Å.

Influência da anemia ferropriva no eletroforetrograma de hemoglobina de leitões

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Gestão das línguas no século XXI: para uma introdução à política linguística exterior

The objective of this work is to stimulate a debate about the idea of a possible foreign language policy. It seeks to do so from an overview of the structural changes of recent decades - those affecting the economy, information and communication technologies, geopolitics and identities - in order to draw attention to the renewed importance and the role that the language management issues are assuming in this new context. Considering the foreign language policy a theoretical and practical essential tool for the management of language in a globalized world, the focus of the discussion rests on four main aspects: the origins of the notion of foreign language policy; the relationship with the foreign policy of the State; its effectiveness through the intervention on corpus, status and acquisition of the language; and the possibility of their formulation by agents other than the State

A voz do idoso: características clínicas, endoscópicas, vocais e morfológicas

Pós-graduação em Bases Gerais da Cirurgia - FMB

Desenvolvimento e estudo de materiais híbridos siloxano-poli(óxipropileno) para liberação prolongada do cloridrato de propranolol

Pós-graduação em Química - IQ

Effect of humidity and solvent vapor phase on cellulose esters films

In the present study the effect of relative humidity (RH) during spin-coating process on the structural characteristics of cellulose acetate (CA), cellulose acetate phthalate (C-A-P), cellulose acetate butyrate (CAB) and carboxymethyl cellulose acetate butyrate (CMCAB) films was investigated by means of atomic force microscopy (AFM), ellipsometry and contact angle measurements. All polymer solutions were prepared in tetrahydrofuran (THF), which is a good solvent for all cellulose esters, and used for spin-coating at RH of (35 +/- A 5)%, (55 +/- A 5)% or (75 +/- A 5)%. The structural features were correlated with the molecular characteristics of each cellulose ester and with the balance between surface energies of water and THF and interface energy between water and THF. CA, CAB, CMCAB and C-A-P films spin-coated at RH of (55 +/- A 5)% were exposed to THF vapor during 3, 6, 9, 60 and 720 min. The structural changes on the cellulose esters films due to THF vapor exposition were monitored by means of AFM and ellipsometry. THF vapor enabled the mobility of cellulose esters chains, causing considerable changes in the film morphology. In the case of CA films, which are thermodynamically unstable, dewetting was observed after 6 min exposure to THF vapor. On the other hand, porous structures observed for C-A-P, CAB and CMCAB turned smooth and homogeneous after only 3 min exposure to THF vapor.

Homogeneity assessment of a station climate series (1933-2005) in the Metropolitan Area of Sao Paulo: instruments change and urbanization effects

This work assessed homogeneity of the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) weather station climate series, using various statistical techniques. The record from this target station is one of the longest in Brazil, having commenced in 1933 with observations of precipitation, and temperatures and other variables later in 1936. Thus, it is one of the few stations in Brazil with enough data for long-term climate variability and climate change studies. There is, however, a possibility that its data may have been contaminated by some artifacts over time. Admittedly, there was an intervention on the observations in 1958, with the replacement of instruments, for which the size of impact has not been yet evaluated. The station transformed in the course of time from rural to urban, and this may also have influenced homogeneity of the observations and makes the station less representative for climate studies over larger spatial scales. Homogeneity of the target station was assessed applying both absolute, or single station tests, and tests relatively to regional climate, in annual scale, regarding daily precipitation, relative humidity, maximum (TMax), minimum (TMin), and wet bulb temperatures. Among these quantities, only precipitation does not exhibit any inhomogeneity. A clear signal of change of instruments in 1958 was detected in the TMax and relative humidity data, the latter certainly because of its strong dependence on temperature. This signal is not very clear in TMin, but it presents non-climatic discontinuities around 1953 and around 1970. A significant homogeneity break is found around 1990 for TMax and wet bulb temperature. The discontinuities detected after 1958 may have been caused by urbanization, as the observed warming trend in the station is considerably greater than that corresponding to regional climate.