Structural and optical properties of rare earth-doped (Ba(0.77)Ca(0.23))(1-x)(Sm, Nd, Pr, Yb)(x)TiO(3)

The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba(0.77) Ca(0.23)TiO(3) (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 degrees C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electron microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO(6) octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb(3+) doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm(-1), which is in agreement with lattice dynamics calculations. (c) 2011 American Institute of Physics. [doi:10.1063/1.3594710]

Third-order nonlinear spectra and optical limiting of lead oxifluoroborate glasses

We have determined two-photon absorption and nonlinear refraction spectra of the 50BO(1.5) - (50-x)PbF(2) - xPbO glasses (with x = 25, 35, 50 cationic %) at the range of the 470 and 1550 nm. The replacement of fluor atoms by oxygen leads to an increase in the third-order susceptibility, due to the formation of non-bridging oxygens (NBO). The nonlinear index of refraction is one order of magnitude higher than the one for fused silica, and it increases almost twice for the sample with x = 50. This sample has also shown promising features for all-optical switching as well as for optical limiting. (C) 2011 Optical Society of America

Structural and optical analysis of GaAsP/GaP core-shell nanowires

The structural and optical properties of GaAsP/GaP core-shell nanowires grown by gas source molecular beam epitaxy were investigated by transmission electron microscopy, Raman spectroscopy, photoluminescence (PL), and magneto-PL. The effects of surface depletion and compositional variations in the ternary alloy manifested as a redshift in GaAsP PL upon surface passivation, and a decrease in redshift in PL in the presence of a magnetic field due to spatial confinement of carriers.

Structural, dielectric, and optical properties of yttrium calcium borate glasses

Structural and optical properties of stable glasses in the Y(2)O(3)-CaO-B(2)O(3) system, containing the same Y/Ca ratio as the YCa(4)O(BO(3))(3) (YCOB) crystal, were determined from Raman and reflectance infrared spectroscopy. Changes in optical functions with composition are associated with an increase in the number of non-bridging oxygen and to calcium/yttrium oxides content. Refractive indexes values (from 1.597 to 1.627 at lambda=2 mu m) are in good agreement with those of the YCOB crystal, an indication that these glasses are potential candidates for optical applications due to their ease of shaping as large bulk samples or fibers.

Luminescent and thermo-optical properties of Nd(3+)-doped yttrium aluminoborate laser glasses

In this work we performed a thorough spectroscopic and thermo-optical investigation of yttrium aluminoborate glasses doped with neodymium ions. A set of samples, prepared by the conventional melt-quenching technique and with Nd(2)O(3) concentrations varying from 0.1 to 0.75 mol %, were characterized by ground state absorption, photoluminescence, excited state lifetime measurements, and thermal lens technique. For the neodymium emission at 1064 nm ((4)F(3/2) -> (4)I(11/2) transition), no significant luminescence concentration quenching was observed and the experimental lifetime values ranged around 70 mu s. The obtained values of thermal conductivity and diffusivity of approximately 10.3 x 10(-3) W / cm K and 4.0 x 10(-3) cm(2) / s, respectively, are comparable to those of commercial laser glasses. Moreover, the fluorescence quantum efficiency of the glasses, calculated using the Judd-Ofelt formalism and luminescence decay, lies in the range from 0.28 to 0.32, larger than the typical values obtained for Nd(3+) doped YAl(3)(BO(3))(4) crystals. (c) 2009 American Institute of Physics. [DOI: 10.1063/1.3176503]

Estimation of the thickness and the optical parameters of several stacked thin films using optimization

The reverse engineering problem addressed in the present research consists of estimating the thicknesses and the optical constants of two thin films deposited on a transparent substrate using only transmittance data through the whole stack. No functional dispersion relation assumptions are made on the complex refractive index. Instead, minimal physical constraints are employed, as in previous works of some of the authors where only one film was considered in the retrieval algorithm. To our knowledge this is the first report on the retrieval of the optical constants and the thickness of multiple film structures using only transmittance data that does not make use of dispersion relations. The same methodology may be used if the available data correspond to normal reflectance. The software used in this work is freely available through the PUMA Project web page (http://www.ime.usp.br/similar to egbirgin/puma/). (C) 2008 Optical Society of America

Anthelmintic effects of condensed tannins on Trichostrongylus colubriformis in experimentally infected sheep

Recent surveys have identified anthelmintic effects from many bioactive substances particularly from condensed tannin (CT) sources. The aims of the present study were to investigate the potential anthelmintic effects of condensed tannins (CT) on Trichostrongylus colubriformis in experimentally infected sheep and the nutritional consequences on animals. Twenty helminth-free lambs were divided into five groups of four animals. Groups I to IV were artificially infected with 6,000 third stage larvae (L3) of T. colubriformis. Group I was the infected control and group V was the uninfected control. Twenty-eight days post-infection (p.i.) lambs from GII were supplemented with tanniniferous sorghum (350 g/animal/day, during seven days); GIII were drenched with Acacia mearnsii extract (15% CT) for just one day and GIV during two days (1.6 g extract/kg BW). At day 36 p.i., animals from infected group (GI to GIV) were slaughtered. Faecal egg counts (FEC) values present a reduction on GII when compared with GI at day 29 p.i. (P < 0.05) and between GIII and GI at day 35 and 36 p.i. (P < 0.05). The values of egg hatchability and number of L3 recovered from the faeces were not statistical analyzed (there was no duplicate data), however there was a considerable reduction between the values from treated and control group. The use of CT on diet did not cause significant difference on blood parameters, body-weight and carcass-weight (P > 0.05). No difference was related on total worm burden between treatments; however, GIV presented lower number of females than GI (P < 0.05). The use of CT could be a promising alternative source to reduce the pasture contamination and to control T. colubriformis infection in sheep.

Sources of particulate matter: emission profile of biomass burning

Biomass burning is an important source of atmospheric Particulate Matter (PM) in Brazil: the burning of forests in the northwest and of sugar cane plantations in the southeast are important examples. The objective of this work is the measurement of the PM emission profile of burning of sugar cane and other characteristic vegetative burning in the region of Sao Carlos-SP/Brazil. Samples of PM(10) and PM(2.5) were collected in different conditions, including small laboratory controlled burnings and real ones. The samples were analysed by X-Ray Fluorescence (XRF) and 14 chemical elements quantified. t-Student tests were performed to compare the obtained profiles, using as a reference a vegetative burn profile taken from the USEPA data bank SPECIATE. All measured profiles presented significant amounts of Cl and K, which are confirmed as tracers of sugar cane foliage burning.

Thermal, structural and optical properties of Al(2)CoO(4)-Crocoite composite nanoparticles used as pigments

Al(2)CoO(4)-PbCrO(4) and Al(2)CoO(4)-Pb(2)CrO(5) crystalline powders in different proportions were obtained by the polymeric precursor method. Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis. The TG and DSC results revealed a series of overlapping decomposition reactions due to different exothermal events, which were identified as H(2)O and NO(x) elimination and polymer pyrolysis. The X-ray diffraction patterns of the xAl(2)CoO(4)-(1 - x)PbCrO(4) and xAl(2)CoO(4)-(1 - x)Pb(2)CrO(5) mixed compounds, with x = 1, 0.75, 0.5, 0.25 and 0, were obtained in the crystalline form with their respective phases, and proved consistent with the nominal compositions. The synthesis of these two systems yielded nine different colors and shades.

An upflow fixed-bed anaerobic-aerobic reactor for removal of organic matter and nitrogen from L-lysine plant wastewater

This paper reports on the design of a new reactor configuration - an upflow fixed-bed combined anaerobic-aerobic reactor - can operate as a single treatment unit for the removal of nitrogen (approximate to 150 mg N/L) and organic matter (approximate to 1300 mg COD/L) from Lysine plant wastewater. L-Lysine, an essential amino acid for animal nutrition, is produced by fermentation from natural raw materials of agricultural origin, thus generating wastewater with high contents of organic matter and nitrogen. The best operational condition of the reactor was obtained with a hydraulic retention time of 35 h (21 h in the anaerobic zone and 14 h in the aerobic zone) and a recycling ratio (R) of 3.5. In this condition, the COD, total Kjeldahl nitrogen (TKN), and total nitrogen (TN) removal efficiencies were 97%, 96%, and 77%, respectively, with average effluent concentrations of 10 +/- 36 mg COD/L, 2 +/- 1 mg NH(4)(+)-N/L, 8 +/- 3 mg Org-N/L, 1 +/- 1 mg NH(2)(-)-N/L, and 26 +/- 23 mg NH(3)(-)-N/L.

Ozone oxidation of pulp and paper wastewater and its impact on molecular weight distribution of organic matter

The impact of ozone oxidation on removing high molecular weight (HMW) organics in order to improve the biodegradability of alkaline bleach plant effluent was investigated using a semi-batch reactor under different initial pH (12 and 7). After the ozonation process, the ratio of BOD5/COD increased from 0.07 to 0.16 and 0.22 for initial pH 12 and 7, respectively. Also, the effluent color decreased by 48% and 61% at initial pH 12 and pH 7, respectively. These changes were primarily driven by reductions of the HMW fractions of the effluent during ozonation.

Backside contact effect on the morphological and optical features of porous silicon photonic crystals

The present work reports on the effect of the type of backside contact used in the electrochemical process and their relation with the structural features and optical responses of the one-dimensional photonic crystal (PC) anodized in simple and double electrochemical cell. The PC, obtained in the single cell, showed to have thicker layers than of the PC obtained in double electrochemical cell. Additionally, the PC obtained in double cell showed highest reflectance in the band gap region than of the PCs obtained in single cell. These results suggest that the interface roughness between adjacent layers in the PC devices obtained in double electrochemical cell is minimized. (C) 2008 Elsevier Ltd. All rights reserved.

Solvent Effects in Optical Spectra of ortho-Aminobenzoic Acid Derivatives

We investigated three amino derivatives of ortho-aminobenzoic or anthranilic acid (o-Abz): a) 2-Amino-benzamide (AbzNH(2)); b) 2-Amino-N-methyl-benzamide (AbzNHCH(3)) and c) 2-Amino-N-N`-dimethyl-bezamide (AbzNH(CH(3))(2)), see Scheme 1. We describe the results of ab-initio calculations on the structural characteristics of the compounds and experimental studies about solvent effects in their absorption and steady-state and time-resolved emission properties. Ab-initio calculations showed higher stability for the rotameric conformation in which the oxygen of carbonyl is near to the nitrogen of ortho-amino group. The derivatives present decrease in the delocalization of pi electron, and absorption bands are blue shifted compared to the parent compound absorption, the extent of the effect increasing from to Abz-NH(2) to Abz-NHCH(3) Abz-NH(CH(3))(2). Measurements performed in several solvents have shown that the the dependence of Stokes shift of the derivatives with the orientational polarizability follows the Onsager-Lippert model for general effects of solvent. However deviation occurred in solvents with properties of Bronsted acids, or electron acceptor characteristics, so that hydrogen bonds formed with protic solvents predominates over intramolecular hydrogen bond. In most solvents the fluorescence decay of AbzNH(2) and AbzNHCH(3) was fitted to a single exponential with lifetimes around 7.0 ns and no correlation with polarity of the solvent was observed. The fluorescence decay of AbzN(CH(3))(2) showed lifetimes around 2.0 ns, consistent with low quantum yield of the compound. The spectroscopic properties of the monoamino derivative AbzNHCH(3) are representative of the properties presented by Abz labelled peptides and fatty acids previously studied.

Increased rates of white matter hyperintensities in late-onset bipolar disorder

Objectives: Magnetic resonance imaging (MRI) studies have reported an increased frequency of white matter hyperintensities (WMH) in association with late-onset (LO) depression, and this has supported the notion that vascular-related mechanisms may be implicated in the pathophysiology of LO mood disorders. Recent clinical studies have also suggested a link between LO bipolar disorder (LO-BD) and cerebrovascular risk factors, but this has been little investigated with neuroimaging techniques. In order to ascertain whether there could be a specific association between WMH and LO-BD, we directly compared WMH rates between LO-BD subjects (illness onset 60 years), early-onset BD subjects (EO-BD, illness onset < 60 years), and elderly healthy volunteers. Methods: T2-weighted MRI data were acquired in LO-BD subjects (n = 10, age = 73.60 +/- 4.09), EO-BD patients (n = 49, age = 67.78 +/- 4.44), and healthy subjects (n = 24, age = 69.00 +/- 7.22). WMH rates were assessed using the Scheltens scale. Results: There was a greater prevalence of WMH in LO-BD patients relative to the two other groups in the deep parietal region (p = 0.018) and basal ganglia (p < 0.045). When between-group comparisons of mean WMH scores were conducted taking account of age differences (ANCOVA), there were more severe scores in LO-BD patients relative to the two other groups in deep frontal and parietal regions, as well as in the putamen (p < 0.05). Conclusions: Our results provide empirical support to the proposed link between vascular risk factors and LO-BD. If extended in future studies with larger samples, these. findings may help to clarify the pathophysiological distinctions between bipolar disorder emerging at early and late stages of life.

Comparative analysis of two immunohistochemical methods for antigen retrieval in the optical lobe of the honeybee Apis mellifera: Myosin-v assay

The present study compared two heating methods currently used for antigen retrieval (AR) immunostaining: the microwave oven and the steam cooker. Myosin-V, a molecular motor involved in vesicle transport, was used as a neuronal marker in honeybee Apis mellifera brains fixed in formalin. Overall, the steam cooker showed the most satisfactory AR results. At 100 degrees C, tissue morphology was maintained and revealed epitope recovery, while evaporation of the AR solution was markedly reduced; this is important for stabilizing the sodium citrate molarity of the AR buffer and reducing background effects. Standardization of heat-mediated AR of formalin-fixed and paraffin-embedded tissue sections results in more reliable immunostaining of the honeybee brain.