Effects of poly(vinyl alcohol) additions on the structure of silica xerogels

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

Influence of oxygen atmosphere on crystallization and properties of LiNbO3 thin films

Thin films of lithium niobate were deposited on the Pt/Ti/SiO2 (111) substrates by spin coating from the polymeric precursor method (Pechini process). Annealing in static air and oxygen atmosphere was performed at 500 degreesC for 3 h. The films obtained were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The dielectric constant and dissipation factor were measured in frequency region from 10 Hz to 10 MHz. Electrical characterization of the films pointed to ferroelectricity via hysteresis loop. The influence of oxygen atmosphere on crystallization, morphology and properties of LiNbO3 thin films is discussed. (C) 2003 Elsevier Ltd. All rights reserved.

Estimativa de la edad y peso a la primera monta de novillas en el Pantanal brasileño

Esto trabajo tuvo como objetivo estimar la edad y peso a la primera monta de novillas de las razas Nelore (N), Pantaneira (P) y Mestizas Pantaneira x Nelore (PxN). Se utilizó un total de 98 hembras, siendo 51, 24 y 23 pertenecientes a las razas N, P y PxN, respectivamente. El análisis estadístico de los datos no reveló diferencia significativa (P = 0,3595) para el peso a la primera monta entre las razas estudiadas. El análisis de varianza no reveló diferencia significativa (P = 0,307) entre las edades a la primera monta entre razas, mostrando 3,5, 3,4 y 3,2 años para las novillas P, N y ½PxN, respectivamente.

Effect of boron and zinc fertilization on white oats grown in soil with average content of these nutrients

The objective of this study was to evaluate the effect of fertilization with zinc or boron on the growth and dry matter production, nutritional value and accumulation of nutrients in white oats. The study comprised two experiments conducted in glasshouses, the first consisting of the application of four doses of zinc (0, 0.2, 0.4 and 0.6 mg/dm³) in the form of zinc sulphate (20% Zn), and the second consisting of the application of four doses of boron (0, 0.2, 0.4 and 0.6 mg/dm³) in the form of Borax (11% B). The experimental design in each case was a randomized block design, with five replicates. Fertilization with zinc and boron increased the growth of white oats, but had no significant effect on the nutritional value of the forage. Higher levels of absorption and accumulation of nutrients in plant tissues were observed following the application of boron and zinc at rates of up to 0.60 mg/dm³ of soil.

Hair coat characteristics and sweating rate of Braford cows in Brazil

This paper deals with the effects of hair coat characteristics on the sweating rate of Brazilian Braford cows and estimation of heritabilities and genetic correlations of these traits. Data (n=1607) on hair length, coat thickness, hair diameter, number of hairs per unit area, coat reflectance and sweating rate were recorded from heifers and cows of a commercial herd managed on range under extensive system. The data were analyzed considering the following effects on the model for hair coat traits: classes of sires and contemporary groups; linear effects of month and genotype; linear and quadratic effects of age. The effect of sire was important (P<0.05) for all hair coat traits, except for number of hairs; contemporary groups affected (P<0.05) all hair coat traits; the effect of sampling month was important (P<0.05) for hair length and reflectance; genotype affected (P<0.05) hair length, diameter and coat reflectance; the quadratic effect of age was important (P<0.05) only for coat reflectance. Two models were used to analyze the sweating rate. The first model considered the following fixed effects: classes of contemporary groups and sires; linear effect of genotype, coat thickness, hair length, hair diameter, number of hairs, coat reflectance; linear and quadratic effects of time of day, age, air temperature, partial vapour pressure and radiant heat load. The second model used for the sweating rate considered the same fixed effects for the first model, except that the hair coat characteristics were adjusted for important effects used in the models to analyze hair coat traits. All meteorological factors and contemporary groups were important (P<0.05) on variation of sweating rate in both models. The Restricted Maximum. Likelihood (REML) method was used to estimate variance and covariance components under the sire model. Results included heritability estimates in narrow (h(2)) and broad (H) sense for single-trait analyzes: hair thickness (h(2)=0.16; H-2=0.26); hair length (h(2)=0.18; H-2=0.39); number of hairs (h(2)=0.08 +/- 0.07; H-2=0.08 +/- 0.07); hair diameter (h(2)=0.12 +/- 0.07; H-2=0.12 +/- 0.07); coat reflectance (h(2)=0.30; H-2=0.42); and sweating rate (h(2)=0.10 +/- 0.07; H-2=0.10 +/- 0.07). In general, the genetic correlations between the adaptive traits were favorable as for the direction to select for adaptation in tropical environment; however, they presented high standard errors. The results of this study imply that hair coat characteristics and sweating ability are important for the adaptability to heat stress and they must be better studied and further considered for selection for genetic progress of adaptation in tropical environment. (C) 2007 Elsevier B.V All rights reserved.

Droplet counter-current chromatography of indole alkaloids from Tabernaemontana hilariana

This paper reports the separation of the indole alkaloids from the benzene extract of the root barks of Tabernaemontana hilariana (Apocynaceae). The crude alkaloid fraction was fractionated by droplet counter-current chromatography using a low polarity mixture (hexane:ethyl acetate:ethanol:water). Nine indole alkaloids (3-hydroxycoronaridine, coronaridine, voacangine, 3-(2-oxopropyl) coronaridine, voacangine hydroxyindolenine, ibogamine, voacangine pseudoindoxyl, coronaridine pseudoindoxyl and tabernanthine) were identified using thin laver chromatography gas chromatography coupled with mass spectrometry and nuclear magnetic resonance spectroscopy. Copyright (C) 1999 John Wiley & Sons, Ltd.

Quantitative determination of maitenin and 22 beta-hydroxymaitenin in callus of Maytenus aquifolium (Celastraceae) by reverse phase high performance liquid chromatography

Explants of Maytenus aquifolium were induced to form callus and, subsequently, suspension cultures. The isolation of natural products from callus led to the identification of the cytotoxic triterpene quinonemethides, maitenin (1) and 22 beta-hydroxymaitenin (2), A rapid, sensitive and reliable reversed-phase high-performance liquid chromatography method was developed using a Cls column and isocratic elution for the determination of 1 and 2, the elaborated method gave well-resolved peaks for these compounds with good detection response and linearity in the range of 0.08-72.0 mu g. The quantification of 1 and 2 was performed by an external standard method. (C) 1998 John Wiley & Sons, Ltd.

Lignoids in seedlings of Virola sebifera

Quantitative analysis carried out by high performance liquid chromatography indicated the accumulation of a major secondary compound in seedlings of Virola sebifera which was isolated and identified as the lignan hydroxy-otobain. This lignan occurs only in trace amounts in the seeds, where cyclolignans (aryltetralones) are by far the major components. In addition to hydroxy-otobain, only hydroxy-aryltetralones were detected in the seedlings, indicating a selective process in the translocation of secondary compounds. Copyright (C) 2000 John Wiley & Sons, Ltd.

Transmission network expansion planning considering uncertainty in demand

This paper presents two mathematical models and one methodology to solve a transmission network expansion planning problem considering uncertainty in demand. The first model analyzed the uncertainty in the system as a whole; then, this model considers the uncertainty in the total demand of the power system. The second one analyzed the uncertainty in each load bus individually. The methodology used to solve the problem, finds the optimal transmission network expansion plan that allows the power system to operate adequately in an environment with uncertainty. The models presented are solved using a specialized genetic algorithm. The results obtained for several known systems from literature show that cheaper plans can be found satisfying the uncertainty in demand.

An adaptation of the dual-affine interior point method for the surface flatness problem

This paper presents an adaptation of the dual-affine interior point method for the surface flatness problem. In order to determine how flat a surface is, one should find two parallel planes so that the surface is between them and they are as close together as possible. This problem is equivalent to the problem of solving inconsistent linear systems in terms of Tchebyshev's norm. An algorithm is proposed and results are presented and compared with others published in the literature. (C) 2006 Elsevier B.V. All rights reserved.

Detection of cross infections by Leishmania spp. and Trypanosoma spp. in dogs using indirect immunoenzyme assay, indirect fluorescent antibody test and polymerase chain reaction

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

Causal phase in QED3

The operator S in Fock space which describes the scattering and particle production processes in an external time-dependent electromagnetic potential A can be constructed from the one-particle S-matrix up to a physical phase λ[A]. In this work we determine this phase for QED in (2 + 1) dimensions by means of causality and show that no ultraviolet divergences arise, in contrast to the usual formalism of QED3.

Application of on-line C30 RP-HPLC-NMR for the analysis of flavonoids from leaf extract of Maytenus aquifolium

The application of on-line C30-reversed-phase high-pressure liquid chromatography-nuclear magnetic resonance spectroscopy is described for the analysis of tetraglycosylated flavonoids in aqueous and hydroalcoholic extracts of the leaves of Maytenus aquifolium (Celastraceae). Triacontyl stationary phases showed adequate separation for on-line 1H-NMR measurements at 600 MHz and allowed the characterisation of these flavonoids by detection of both aromatic and anomeric proton signals. Copyright (C) 2000 John Wiley and Sons, Ltd.