Red shift and higher photoluminescence emission of CCTO thin films undergoing pressure treatment

CCTO thin films were deposited on Pt(1 1 1)/Ti/SiO2/Si substrates using a chemical (polymeric precursor) and pressure method. Pressure effects on CCTO thin films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and optical properties which revealed that a pressure film (PF) is denser and more homogeneous than a chemical film (CF). Pressure also causes a decrease in the band gap and an increase in the photoluminescence (PL) emission of CCTO films which suggests that the pressure facilitates the displacement of Ti in the titanate clusters and the charge transference from TiO6 to [TiO5V0z], [TiO5V0z] to [CaO11V0z] and [TiO5V0z] to [CuO4]x. © 2013 Elsevier B.V. All rights reserved.

Alterações de fluxos sanguíneos cerebrais regionais (FSCr) avaliados através de SPECT (Single Photon Emission Computed Tomography) em pacientes com câncer de mama submetidas à quimioterapia adjuvante

Pós-graduação em Pesquisa e Desenvolvimento (Biotecnologia Médica) - FMB

Comparison between known propagation models using least squares tuning algorithm on 5.8 GHz in Amazon region cities

ABSTRACT: This paper presents a performance comparison between known propagation Models through least squares tuning algorithm for 5.8 GHz frequency band. The studied environment is based on the 12 cities located in Amazon Region. After adjustments and simulations, SUI Model showed the smaller RMS error and standard deviation when compared with COST231-Hata and ECC-33 models.

Characterization of Buriti (Mauritia flexuosa L.) oil by absorption and emission spectroscopies

Amostras de óleo obtido do fruto do Buriti (Mauritia flexuosa L.) foram caracterizadas por espectroscopia de absorção e emissão. O espectro de absorção foi obtido no intervalo de 300 a 2000 nm, enquanto o espectro de emissão foi analisado entre 400 e 800 nm, onde observamos várias bandas. Para melhor entender a complexidade destes espectros, também obtivemos os espectros de absorção e emissão dos componentes majoritários do óleo de Buriti. Correlacionando estes dados, apresentamos uma discussão sobre a origem das bandas observadas.

Analysis of modified bowtie nanoantennas in the excitation and emission regimes

In this work, we analyze modified bowtie nanoantennas with polynomial sides in the excitation and emission regimes. In the excitation regime, the antennas are illuminated by an incident plane wave, and in the emission regime, the excitation is fulfilled by infinitesimal electric dipole positioned in the gap of the nanoantennas. Several antennas with different sizes and polynomial order were numerically analyzed by method of moments. The results show that these novel antennas possess a controllable resonance by the polynomial order and good characteristics of near field enhancement and confinement for applications in enhancement of spontaneous emission of a single molecule.

Iron oxides as proxies for characterizing anisotropy in soil CO2 emission in sugarcane areas under green harvest

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

Fine-tuning of a nanostructure, swelling, and drug delivery profile by blending ureasil-PEO and ureasil-PPO hybrids

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Role of the reactive atmosphere during the sol-gel synthesis on the enhancing of the emission quantum yield of urea cross-linked tripodal siloxane-based hybrids

Transparent monoliths and films of urea cross-linked tripodal siloxane-based hybrids (named tri-ureasils) were prepared by the sol-gel process, under controlled atmosphere (inside a glove box) and ambient conditions and their structure and optical features were compared. X-ray diffraction data point out that all the materials are essentially amorphous and Si-29 NMR reveal an increase in the condensation degree (0.97) for the hybrids prepared under controlled atmosphere relatively to that found for those prepared under ambient conditions (0.84-0.91). The tri-ureasils are white light emitters under UV/Visible excitation (from 250 to 453 nm) being observed for the composites prepared inside the glove box a significant enhancement (60-80 %) of the absorption coefficient and higher emission quantum yield values (similar to 0.27 and similar to 0.20 for monoliths and films, respectively) relatively to those synthesized under ambient condition.

Laser emission of a Nd-doped mixed tellurite and zinc oxide glass

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Er3+-doped Y2O3 obtained by polymeric precursor: Synthesis, structure and upconversion emission properties

The relentless pursuit for materials containing rare earth ions with photoluminescent properties has led to several studies with applications in the development of new technologies. The main focus of this work is the preparation of Er3+-doped polycrystalline Y2O3 with photoluminescent properties using PEG as an organic precursor and heat-treated at different temperatures. The methodology used in this synthesis is highly attractive due to its high feasibility for improved technology and low cost for preparing materials. The behavior of the viscous resin has been evaluated and the final compounds exhibited the formation of a cubic polycrystalline phase, which is able to support variations in Er3+ doping concentrations up to 10 mol%, without significant changes in the polycrystalline parameters. The values of the nanocrystallite size calculated by Scherrer's equation showed direct dependence on the heat-treatment temperature as well as the Er3+ concentration. Intense emission in the visible region under excitation at 980 nm was attributed to an upconversion phenomenon assigned to the intraconfigurational f-f transitions of Er3+ ions. The upconversion mechanism was investigated and it was demonstrated that the higher intense emission in the red region in comparison to the emission in the green region is related to the crystallite size. The studies about the intensity showed the dependence of upconversion emission of power source, indicating that two-photon are responsible for the green and red photoluminescence. These polycrystalline materials exhibit properties that make them promising for use in solar energy systems, C-telecom band or solid-state laser devices. (C) 2014 Elsevier B.V. All rights reserved.

String-averaging expectation-maximization for maximum likelihood estimation in emission tomography

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

Study of K beta X-ray emission spectroscopy applied to Mn((2-x))V((1+x))O4 (x=0 and 1/3) oxyspinel and comparison with XANES

Oxidation state and coordination of transition metal cations seems to be hard to assess when considering multiple cations, each one with different possible oxidation states. In fact, this is the case of the spineltype double oxides family. High resolution K beta X-ray fluorescence spectra were measured in Mn(2-x)V(1+4)O4 (x=0 and 1/3) spinels-type double oxides in order to determine the oxidation state and coordination of V and Mn cations. The relative intensity of radiative Auger effect KM2,3M4,5 to the total intensity and the integral absolute difference value were used as reference parameters for the characterization of Mn oxidation states. The coordination of Mn ions was inferred by the intensity of the K beta(5) line. In the case of V compounds, it was used as the intensity of the line K beta' relative to the total area of K beta region. The obtained results were further compared with X-ray absorption spectra analysis, showing good agreements regarding the oxidation state characterization. However, there were found some discrepancies in coordination, due to customary oversimplifications in the K beta(5) line origin. The obtained results might represent valuable and useful data for chemical scopes of characterizing spineltype oxides family. (C) 2013 Elsevier Ltd. All rights reserved.

Tropical tanniniferous legumes used as an option to mitigate sheep enteric methane emission

This study presents the first results from Brazil using SF6 tracer technique adapted from cattle to evaluate the capability of condensed tannin (CT) present in three tropical legume forages, Leucaena leucocephala (LEU), Styzolobium aterrimum (STA), and Mimosa caesalpiniaefolia Benth (MIM) to reduce enteric CH4 production in Santa Ins sheep. Twelve male lambs [27.88 +/- 2.85 kg body weight (BW)] were allocated in individual metabolic cages for 20-day adaptation followed by 6 days for measuring dry matter intake (DMI) and CH4 emission. All lambs received water, mineral supplement, and Cynodon dactylon v. coast-cross hay ad libitum. The treatments consisted of soybean meal (710 g/kg) and ground corn (290 g/kg) [control (CON)]; soybean meal (150 g/kg), ground corn (30 g/kg), and Leucaena hay (820 g/kg) (LEU); soybean meal (160 g/kg), ground corn (150 g/kg), and Mucuna hay (690 g/kg) (STA); and soybean meal (280 g/kg), ground corn (190 g/kg), and Mimosa hay (530 g/kg) (MIM); all calculated to provide 40 g/kg CT (except for CON). DMI (in grams of DMI per kilogram BW per day) was lower for LEU (22.0) than CON (29.3), STA (31.2), and MIM (31.6). The LEU group showed emission of 7.8 g CH4/day, significantly lower than CON (10.5 g CH4/day), STA (10.4 g CH4/day), and MIM (11.3 g CH4/day). However, when the CH4 emission per DMI was considered, there were no significant differences among treatments (0.37, 0.36, 0.33, and 0.35 g CH4/g DMI/kg BW/day, respectively, for CON, LEU, STA, and MIM). The sheep receiving STA had shown a tendency (p = 0.15) to reduce methane emission when compared to the CON group. Therefore, it is suggested that tropical tanniniferous legumes may have potential to reduce CH4 emission in sheep, but more research is warranted to confirm these results.

Photoluminescence emission at room temperature in zinc oxide nano-columns

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Spatial variability structure of soil CO2 emission and soil attributes in a sugarcane area

Soil CO2 emission (F-CO2) is influenced by chemical, physical and biological factors that affect the production of CO2 in the soil and its transport to the atmosphere. F-CO2 varies in time and space depending on environmental conditions, including the management of the agricultural area. The aim of this study was to investigate the spatial variability structure of F-CO2 and soil attributes in a mechanically harvested sugarcane area (green harvest) using fractal dimension (D-F) derived from isotropic variograms at different scales (fractograms). F-CO2 showed an overall average of 1.51 mu mol CO2 m(-2) s(-1) and correlated significantly (P < 0.05) with soil physical attributes, such as soil bulk density, air-filled pore space, macroporosity and microporosity. Topologically significant DF values were obtained from the characterization of F-CO2 at medium and large scales (above 20 m), with values of 2.92 and 2.90, respectively. The variations in D-F with scales indicate that the spatial variability structure of F-CO2 was similar to that observed for soil temperature and total pore volume and was the inverse of that observed for other soil attributes, such as soil moisture, soil bulk density, microporosity, air-filled pore space, silt and clay content, pH, available phosphorus and the sum of bases. Thus, the spatial variability structure of F-CO2 presented a significant relationship with the spatial variability structure for most soil attributes, indicating the possibility of using fractograms as a tool to better describe the spatial dependence of variables along the scale. (C) 2014 Elsevier B.V. All rights reserved.