Low speed reentry guidance dispersion evaluation

Mathematical models for low speed reentry guidance of Apollo vehicle

Vacuum-UV spectroscopy of interstellar ice analogs. II. Absorption cross-sections of nonpolar ice molecules

Dust grains in cold circumstellar regions and dark-cloud interiors at 10-20 K are covered by ice mantles. A nonthermal desorption mechanism is invoked to explain the presence of gas-phase molecules in these environments, such as the photodesorption induced by irradiation of ice due to secondary ultraviolet photons. To quantify the effects of ice photoprocessing, an estimate of the photon absorption in ice mantles is required. In a recent work, we reported the vacuum-ultraviolet (VUV) absorption cross sections of nonpolar molecules in the solid phase. The aim was to estimate the VUV-absorption cross sections of nonpolar molecular ice components, including CH4, CO2, N2, and O2. The column densities of the ice samples deposited at 8 K were measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. We found that, as expected, solid N2 has the lowest VUV-absorption cross section, which about three orders of magnitude lower than that of other species such as O2, which is also homonuclear. Methane (CH4) ice presents a high absorption near Ly-alpha (121.6 nm) and does not absorb below 148 nm. Estimating the ice absorption cross sections is essential for models of ice photoprocessing and allows estimating the ice photodesorption rates as the number of photodesorbed molecules per absorbed photon in the ice.Comment: 9 pages, 6 figures, 7 table

Produção de carne bovina utilizando confinamento.

Confinamento; Ganho de peso e eficiência de conversão alimentar; Característica de carcaça

Interpretação dos resultados de análises bromatológicas de silagens e outros ingredientes para ração.

O planejamento da alimentação de bovino com forragens conservadas, tais como silagens, envolve informações sobre a disponibilidade deste volumoso e sua qualidade. O controle da qualidade, por meio de análises químico-bromatológicas do produto em laboratório especializado, e essencial, devido as dificuldades para monitorar a fermentação no silo, a semelhança de uma indústria, que esteriliza ou pasteuriza a matéria-prima antes de adicionar os inoculantes, e controlar a temperatura para obter um produto padronizado. O uso de resíduos de cultura, incluindo-se os resíduos de pré-limpeza, e de indústria, como volumosos para alimentação de bovinos também requer análise criteriosa de qualidade, em razão da enorme variabilidade encontrada (produto não-padronizado) nestes produtos.Resumo expandido

Resíduos de cultura e indústria.

Utilizacao das palhadas na alimentacao. Tratamento quimico das palhadas. Uso de soda caustica. Uso de hidroxido de calcio. Uso de Amonia Anidra(gasosa). Uso de Amonia liquida. Uso da ureia. Composicao Quimica e valor Nutritivo de Restos de cultura

Study of the spatial variation of the biodegradation rate of the herbicide bentazone with soil depth using contrasting incubation methods

Vertical and horizontal spatial variability in the biodegradation of the herbicide bentazone was compared in sandy-loam soil from an agricultural field using sieved soil and intact soil cores. An initial experiment compared degradation at five depths between 0 and 80 cm using sieved soil. Degradation was shown to follow the first-order kinetics, and time to 50% degradation (DT50), declined progressively with soil depth from 56 d at 0–10 cm to 520 d at 70–80 cm. DT50 was significantly correlated with organic matter, pH and dehydrogenase activity. In a subsequent experiment, degradation rate was compared after 127 d in sieved soil and intact cores from 0 to 10 and 50 to 60 cm depth from 10 locations across a 160 × 90 m portion of the field. Method of incubation significantly affected mean dissipation rate, although there were relatively small differences in the amount of pesticide remaining in intact cores and sieved soil, accounting for between 4.6% and 10.6% of that added. Spatial variability in degradation rate was higher in soil from 0 to 10 cm depth relative to that from 50 and 60 cm depth in both sieved soil and intact core assessments. Patterns of spatial variability measured using cores and sieved soil were similar at 50–60 cm, but not at 0–10 cm depth. This could reflect loss of environmental context following processing of sieved soil. In particular, moisture content, which was controlled in sieved soil, was found to be variable in cores, and was significantly correlated with degradation rate in intact topsoil cores from 0 to 10 cm depth