Nucleation and crystallization of titania nanoparticles in silica titania planar waveguides: A study by low frequency Raman scattering

SiO2 (1-x) - TiO2 (x) waveguides, with the mole fraction x in the range 0.07 - 0.20 and thickness of about 0.4 μm, were deposited on silica substrates by a dip-coating technique. The thermal treatments at 700-900°C, used to fully densify the xerogels, produce nucleation of TiO2 nanocrystals even for the lowest TiO2 content. The nucleation of TiO2 nanocrystals and their growth by thermal annealing up to 1300°C were studied by waveguide Raman spectroscopy, for the SiO2 (0.8) - TiO2 (0.2) composition. By increasing the annealing temperature, the Raman spectrum evolves from that typical of the silica-titania glass to that of anatase, but brookite phase is dominant at intermediate temperatures. In the low. frequency region (5-50 cm-1) of the Raman spectra, acoustic vibrations of the nanocrystals are observed. From the measured line shapes, we can deduce the size distribution of the particles. The results are compared with those obtained from the line widths in the X-ray diffraction patterns. Nanocrystals with a mean size in the range 4-20 nm are obtained, by thermal annealing in a corresponding range of 800-1300°C.

Efeito de resíduos vegetais de milheto (Pennisetum americanum) e da calagem em algumas propriedades físicas e químicas de um nitossolo vermelho em sistema de semeadura direta

This work studied alterations of physical properties of a distroferric red nitosol due to millet (Pennisetum americanum) covering, with or without liming, in a no-tillage system during the agricultural years of 1999/2000 and 2000/2001, using soybean and corn as culture succession. 6m×10m plots, with and without millet as vegetal covering, received only one initial superficial application of limestone, 3.1 t ha-1 in the first half of each plot in order to obtain 70% base saturation (V), after the desiccation of the millet. Some physical properties as soil density, aggregate stability, > 2 mm aggregate proportion, macro and micro porosity were analyzed whereas the chemical analysis determined Ca and Mg macro nutrients, organic matter, soil pH and H+Al. Millet vegetal residues and surface liming did not alter soil density nor the average weight diameter (AWD), > 2 mm aggregate, soil macro porosity and organic matter content, twenty-four months after the no-tillage system implantation for studied experimental conditions. Soil micro porosity was significantly affected in layers deeper than 0.20 m, in treatment with millet and limestone. Calcium, magnesium and H + Al contents and the soil pH values suffered significant alterations in superficial layer, between 0-0.05 m.

Fração de excreção de sódio, osmolaridade e densidade urinária em recém-nascidos prematuros alimentados com leite humano de banco adicionado de suplemento

Objective: This research was performed with the objective of investigating the renal effects on premature newborn infants of fortifying banked donor human milk. Methods: Clinical intervention trial, of the before-and-after type, involving 28 premature newborn infants split into two groups by postconceptional age at the start of the study: GI < 34 weeks (n = 14) and GII ≥ 34 weeks (n = 14), and assessed at three sample points: S1, on unfortified donor human milk, S2, after 3 days, and S3, after 10-13 days on fortified donor human milk. Nutrient intake, weight gain, fractional sodium excretion, urinary osmolality and specific density were compared with two-way ANOVA for repeated measures. Results: Fluids, energy and sodium intakes were similar for both groups, and weight gain was satisfactory. Among the preterms with < 34 weeks postconceptional age, serum sodium was lower at the end of the study and the fractional sodium excretion was elevated at the start and at the end of the study (S1 = 2.11±1.05; S2 = 1.25±0.64; S3 = 1.62±0.88), with a significant difference in relation to GII (S1 = 1.34±0.94; S2 = 0.90±0.54; S3 = 0.91±0.82). Osmolality and urinary specific density were normal, with no differences between groups or collection dates. Conclusions: No adverse effects on the renal function of these preterms were detected as a result of being fed fortified donor human milk. Copyright © 2006 by Sociedade Brasileira de Pediatria.

Corn root length density and root diameter as affected by soil compaction and soil water content

Negative effects of soil compaction have been recognized as one of the problems restricting the root system and consequently impairing yields, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in green house studies are necessary for the development of mechanism which alleviates soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. The experiment was conducted to assess the root length density and root diameter of the corn (Zea mays L.) crop as a function of bulk density and water stress, characterized by the soil density (1.2; 1.4, and 1.6 g cm -3), and two levels of the water content, approximately (70 and 90% field capacity). The statistical design adopted was completely randomized design, with four replicates in a factorial pattern of (3 × 2). The PVC tubes were superimposed with an internal diameter of 20 cm with a height of 40 cm (the upper tube 20 cm, compacted and inferior tube 10 cm), the hardpan with different levels of soil compaction were located between 20 and 30 cm of the depth of the pot. Results showed that: the main effects of subsoil mechanical impedance were observed on the top layer indicating that the plants had to penetrate beyond the favorable soil conditions before root growth was affected from 3.16; 2.41 to 1.37 cm cm -3 (P<0.005). There was a significant difference at the hardpan layer for the two levels of water and 90% field capacity reduced the root growth from 0.91 to 0.60 cm cm -3 (P<0.005). The root length density and root diameter were affected by increasing soil bulk density from 1.2 to 1.6 g cm -3 which caused penetration resistance to increase to 1.4 MPa. Soil water content of 70% field capacity furnished better root growth in all the layers studied. The increase in root length density resulted in increased root volume. It can also be concluded that the effect of soil compaction impaired the root diameter mostly at the hardpan layer. Soil temperature had detrimental effect on the root growth mostly with higher bulk densities.

Avaliação da distribuição da densidade em MDF a partir da técnica da onda de ultra-som

The goal of this research was to determine the density distribution in medium density fiberboard (MDF), manufactured with polyurethane derived from castor oil using, ultrasonic wave technique. The equipment used in this test is Steinkamp BP7 with plan and exponential transducers, both with 45 kHz frequencies, located in several zones on the plate in order to determine wave ultrasonic velocity. The Pinus caribaea and Eucalyptus grandis fiberboard were manufactured in the quality control and products development laboratory of Duratex with 500 mm long, 500 mm large, 8 and 15 mm of thickness. Three MDF for each fiber specimen and thickness were fabricated, totalizing twelve plates tested. The MDF were produced with 5% polyurethane addition, in temperature of 160°C, tension press of 53 bars and addition of moisture content of 12%. For determination of fiberboard density, samples were extracted from the same zones where the wave ultrasonic velocity was determined. In this case, DAX-Ray equipment was used. Statistical analysis shows good agreement with wave ultrasonic velocity and the density profile, validating the application of non-destructive technique in order to determine the density profile of MDF's.

Compactação do solo e intervalo hídrico ótimo no crescimento da parte aérea e produtividade da cultura do milho

The aim of this work was to evaluate the effect of soil compaction caused by tractor wheel traffic on the limiting water range (LLWR), shoot growth and levels of compaction and four replications in a completely randomized experimental design. Soil samples with preserved structure were collected in the layers: 0.02-0.05; 0.08-0.11; 0.15-0.18 and 0.22-0.25m to determine macroporosity, microporosity, total porosity, bulk density, resistance to penetration and LLWR. The evaluated corn parameters were: plant and first spike height, steam diameter, number of spikes per plant, plant dry matter, dry matter of 1000 seeds and seed productivity. The soil compaction restricted all corn parameters except the number of spikes per plant and dry matter of 1000 seeds. The LLWR was reduced by the soil resistance to penetration, even in the tilled soil with bulk density of 1.12 Mg m-3. Only the treatment with 11 Mg tractor, repeated four times on the area, demonstrated bulk density above critical bulk density in the LLWR that was 1.37 Mg m-3, where the seed productivity was significantly smaller.

α-SiAION: Development and machining test on gray cast iron

The α-SiAlON ceramic cutting tool insert is developed. Silicon nitride and additives powders are pressed and sintered in the form of cutting tool inserts at temperature of 1900 °C. The physics and mechanical properties of the inserts like green density, weight loss, relative density, hardness and fracture toughness are evaluated. Machining studies are conducted on grey cast iron workpiece to evaluate the performance of α-SiAlON ceramic cutting tool. In the paper the cutting tool used in higher speed showed an improvement in the tribological interaction between the cutting tools and the grey cast iron workpiece resulted in a significant reduction of flank wear and roughness, because of better accommodation and the presence of the graphite in gray cast iron. The above results are discussed in terms of their affect at machining parameters on gray cast iron.

Oxidative stress, superoxide production, and apoptosis of neutrophils in dogs with chronic kidney disease

Oxidative stress is a key component in the immunosuppression of chronic kidney disease (CKD), and neutrophil function may be impaired by oxidative stress. To test the hypothesis that in uremic dogs with CKD, oxidative stress is increased and neutrophils become less viable and functional, 18 adult dogs with CKD were compared with 15 healthy adult dogs. Blood count and urinalysis were done, and the serum biochemical profile and plasma lipid peroxidation (measurement of thiobarbituric acid reactive substances) were determined with the use of commercial reagents. Plasma total antioxidant capacity (TAC) was measured with a spectrophotometer and commercial reagents, superoxide production with a hydroethidine probe, and the viability and apoptosis of neutrophils with capillary flow cytometry and the annexin V-PE system. The plasma concentrations of cholesterol (P = 0.0415), creatinine (P < 0.0001), and urea (P < 0.0001) were significantly greater in the uremic dogs than in the control dogs. The hematocrit (P = 0.0004), urine specific gravity (P = 0.015), and plasma lipid peroxidation (P < 0.0001) were significantly lower in the dogs that were in late stages of CKD than in the control group. Compared with those isolated from the control group, neutrophils isolated from the CKD group showed a higher rate of spontaneous (0.10 ± 0.05 versus 0.49 ± 0.09; P = 0.0033; median ± standard error of mean) and camptothecin-induced (18.53 ± 4.06 versus 44.67 ± 4.85; P = 0.0066) apoptosis and lower levels of superoxide production in the presence (1278.8 ± 372.8 versus 75.65 ± 86.6; P = 0.0022) and absence (135.29 ± 51.74 versus 41.29 ± 8.38; P = 0.0138) of phorbol-12-myristate-13-acetate stimulation. Thus, oxidative stress and acceleration of apoptosis occurs in dogs with CKD, the apoptosis diminishing the number of viable neutrophils and neutrophil superoxide production.

Avaliação da técnica de dopplerfluxometria e índice de resistividade das artérias renais em cadelas com piometra

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

Características epidemiológicas, clínicas e laboratoriais de gatos com sinais de trato urinário inferior

Pós-graduação em Medicina Veterinária - FCAV

Comparação entre três critérios de amostragem para a avaliação da densidade básica da madeira de florestas implantadas de eucaliptos

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Desempenho do stellite como material de ferramenta no serramento da madeira

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estresse oxidativo, produção de superóxido e a apoptose de neutrófilos de cães com insuficiência renal crônica

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

Avaliação de microminerais orgânicos no desempenho reprodutivo de matrizes pesadas e respostas da progênie

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Suplementação de ração de codornas com selênio, zinco e manganês de fonte orgânica

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