Symmetry breaking in a localized interacting binary Bose-Einstein condensate in a bichromatic optical lattice

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

RELATIONSHIPS BETWEEN THE PLASMA ENVIRONMENT AND THE COMPOSITION AND OPTICAL-PROPERTIES OF PLASMA-POLYMERIZED THIN-FILMS PRODUCED IN RF DISCHARGES OF C2H2-SF6 MIXTURES

Polymer films were grown in rf discharges containing different proportions of C2H2 and SF6. Quantitative optical emission spectrometry (actinometry) was used to follow the trends in the plasma concentrations of the species H and F, and more tentatively, of CH, CF, and CF2, as a function of the feed composition. Infrared spectroscopy revealed the density of CH and CF bonds in the deposited material. As the partial pressure of SF6 in the feed was increased, the degree of fluorination of the polymer also rose. The form of the dependency of the deposition rate on the proportion of SF6 in the feed was in good qualitative agreement with the activated growth model. From transmission ultraviolet visible spectroscopy data the refractive index and the absorption coefficient of the polymers were calculated as a function of the deposition parameters. Since the optical gap depended to some extent upon the degree of fluorination, it could, within limits, be determined by a suitable choice of the proportion of SF6 in the feed. A qualitative explanation of this relationship is given.

Effect of Different Solvent Ratios (Water/Ethylene Glycol) on the Growth Process of CaMoO4 Crystals and Their Optical Properties

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

Optical and electrical diagnostics of a spark-plug discharge in air

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

An intercomparison of bio-optical techniques for detecting dominant phytoplankton size class from satellite remote sensing

Satellite remote sensing of ocean colour is the only method currently available for synoptically measuring wide-area properties of ocean ecosystems, such as phytoplankton chlorophyll biomass. Recently, a variety of bio-optical and ecological methods have been established that use satellite data to identify and differentiate between either phytoplankton functional types (PFTs) or phytoplankton size classes (PSCs). In this study, several of these techniques were evaluated against in situ observations to determine their ability to detect dominant phytoplankton size classes (micro-, nano- and picoplankton). The techniques are applied to a 10-year ocean-colour data series from the SeaWiFS satellite sensor and compared with in situ data (6504 samples) from a variety of locations in the global ocean. Results show that spectral-response, ecological and abundance-based approaches can all perform with similar accuracy. Detection of microplankton and picoplankton were generally better than detection of nanoplankton. Abundance-based approaches were shown to provide better spatial retrieval of PSCs. Individual model performance varied according to PSC, input satellite data sources and in situ validation data types. Uncertainty in the comparison procedure and data sources was considered. Improved availability of in situ observations would aid ongoing research in this field. (C) 2010 Elsevier B.V. All rights reserved.

Evaluation of the microvascular density in astrocytomas in adults correlated using SPECT-MIBI

Microvascular density (MVD) may be an additional prognostic marker for astrocytomas, but the heterogeneity of these tumors limits its use. Thus, imaging examinations such as SPECT-MIBI (2-methoxyisobutyl isonitrile) may take on an indirect role in astrocytoma evaluation. The aim of this study was to evaluate MVD in astrocytomas using immunohistochemistry with anti-CD34 monoclonal antibodies. The relationship between the immunohistochemical data and the parameters obtained from SPECT-MIBI was evaluated. This cross-sectional study evaluated 48 patients with brain tumors including low-grade astrocytomas (LGAs), anaplastic astrocytomas (AAs) and glioblastoma multiformes (GBMs). Patients had been admitted to the Hospital de Cancer de Barretos - Fundação Pio XII, and underwent brain SPECT-MIBI prior to any treatment. MVD was determined under an optical microscope by counting microvessels on slides from each case. SPECT-MIBI images were analyzed visually and semiquantitatively. GBMs, AAs and LGAs represented 50, 16.7 and 33.3% of the total sample, respectively. There were 13 normal and 35 abnormal SPECT-MIBI images. Significant differences in MVD were found between AA and LGA cases (p=0.040), but not between normal and abnormal SPECT-MIBI. The mean counts from SPECT-MIBI were not correlated with MVD. Among the GBM cases, there were no significant findings, except for an increased likelihood of abnormal histological test results. MVD was related to histological grade (in AA and LGA cases) but was not correlated with SPECT-MIBI.

Charge density alterations in human hair fibers: An investigation using electrostatic force microscopy

A new method for high-resolution analyses of hair surface charge density under ambient conditions is presented in this paper. Electrostatic force microscopy (EFM) is used here to analyze changes in surface charge density in virgin hair, bleached hair, and hair treated with a cationic polymer. The atomic force microscopy technique is used concomitantly to analyze morphological changes in hair roughness and thickness. The EFM images depict exactly how the polymer is distributed on the surface of the hair fiber. The EFM's powerful analytical tools enabled us to evaluate the varying degrees of interaction between the hair fiber surface charge density and the cationic polymer. The surface charge density and the polymer's distribution in the hair fibers are presented in the light of EFM measurements. © 2006 Society of Cosmetic Scientists and the Socièété Française de Cosmétologie.

A combined theoretical and experimental study of electronic structure and optical properties of β-ZnMoO4 microcrystals

In this paper, a combined theoretical and experimental study on the electronic structure and photoluminescence (PL) properties of beta zinc molybdate (β-ZnMoO4) microcrystals synthesized by the hydrothermal method has been employed. These crystals were structurally characterized by X-ray diffraction (XRD), Rietveld refinement, Fourier transform Raman (FT-Raman) and Fourier transform infrared (FT-IR) spectroscopies. Their optical properties were investigated by ultraviolet-visible (UV-Vis) absorption spectroscopy and PL measurements. First-principles quantum mechanical calculations based on the density functional theory at the B3LYP level have been carried out. XRD patterns, Rietveld refinement, FT-Raman and FT-IR spectra showed that these crystals have a wolframite-type monoclinic structure. The Raman and IR frequencies experimental results are in reasonable agreement with theoretically calculated results. UV-Vis absorption measurements shows an optical band gap value of 3.17 eV, while the calculated band structure has a value of 3.22 eV. The density of states indicate that the main orbitals involved in the electronic structure of β-ZnMoO4 crystals are (O 2p-valence band and Mo 4d-conduction band). Finally, PL properties of β-ZnMoO4 crystals are explained by means of distortions effects in octahedral [ZnO6] and [MoO6] clusters and inhomogeneous electronic distribution into the lattice with the electron density map. © 2013 Elsevier Ltd. All rights reserved.

Local electronic structure, optical bandgap and photoluminescence (PL) properties of Ba(Zr0.75Ti0.25)O3 powders

Ba(Zr0.75Ti0.25)O3 (BZT-75/25) powders were synthesized by the polymeric precursor method. Samples were structurally characterized by X-ray diffraction (XRD), Rietveld refinement, X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques. Their electronic structures were evaluated by first-principle quantum mechanical calculations based on density functional theory at the B3LYP level. Their optical properties were investigated by ultraviolet-visible (UV-Vis) spectroscopy and photoluminescence (PL) measurements at room temperature. XRD patterns and Rietveld refinement data indicate that the samples have a cubic structure. XANES spectra confirm the presence of pyramidal [TiO5] clusters and octahedral [TiO6] clusters in the disordered BZT-75/25 powders. EXAFS spectra indicate distortion of Ti-O and Ti-O-Ti bonds the first and second coordination shells, respectively. UV-Vis absorption spectra confirm the presence of different optical bandgap values and the band structure indicates an indirect bandgap for this material. The density of states demonstrates that intermediate energy levels occur between the valence band (VB) and the conduction band (CB). These electronic levels are due to the predominance of 4d orbitals of Zr atoms in relation to 3d orbitals of Ti atoms in the CB, while the VB is dominated by 2p orbitals related to O atoms. There was good correlation between the experimental and theoretical optical bandgap values. When excited at 482 nm at room temperature, BZT-75/25 powder treated at 500 C for 2 h exhibited broad and intense PL emission with a maximum at 578 nm in the yellow region. © 2013 Elsevier Ltd. All rights reserved.

Structural, electronic and optical properties of Fe(III) complex with pyridine-2,6-dicarboxylic acid: A combined experimental and theoretical study

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

Structural and optical properties of Cu2O crystalline electrodeposited films

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Optical spectrum of bottom-up graphene nanoribbons: towards efficient atom-thick excitonic solar cells

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

Correlation between structural and electronic order-disorder effects and optical properties in ZnO nanocrystals

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

Biodegradation of films of low density polyethylene (LDPE), poly(hydroxibutyrate-co-valerate) (PHBV), and LDPE/PHBV (70/30) blend with Paecilomyces variotii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Elucidating the optical properties of novel heterolayered materials based on MoTe2-InN for photovoltaic applications

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