Results 1 - 10 of 542
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[en] Concerning with applied nitrogen fertilizer, the uptake as well as loss of nitrogen is mainly related to soil water content. The effects of soil water condition in wheat field on the uptake, leach and loss of nitrogen fertilizer were studied using 15N tracing technique. The results showed that within certain range of soil water supply, from 180 to 360 mm of available water storage, the loss of nitrogen was in direct proportion to the amount of fertilizer application and the nitrogen use efficiency decreased with the increase of nitrogen application. In other words, the nitrogen use efficiency descended with the nitrogen application increased in an order of 75 kgN/ha, 150 kgN/ha, 225 kgN/ha. One interesting result was that the nitrogen use efficiencies ranged from 17.0% to 30.5% for the treatments receiving the same application rate of 75 kgN/ha
[en] Steel is a very versatile metallic material and widely used in modern life. Unfortunately, this material is prone to the phenomenon of corrosion and over time, can contribute to the failure of the product. In order to minimize this process, different types of coatings are used, due to their efficiency, economy and ease of application. The degradation of the film applied to steel by atmospheric agents is the result of the combination of various environmental factors, due to the highly destructive cyclic variations. The present work intends to determine the existence of significant statistical differences in the thickness distribution of coating in duplex systems (Fe/Zn/Paint), before and after conducting the humidity and temperature test with condensation in a constant atmosphere, from different tests carried out in the Stat graphics Centurion software. The influence of the preset conditions on the coating thickness before and after the test was demonstrated was demonstrated. These values were found in a suitable interval to guarantee the resistance to corrosion, not showing visible deterioration in the surface of the analyzed specimens.
[es]El acero es un material metálico muy versátil y ampliamente utilizado en la vida moderna. Desafortunadamente, este material está propenso al fenómeno de la corrosión y el pasar del tiempo, puede contribuir a la falla del producto. Para lograr minimizar este proceso se utilizan diferentes tipos de recubrimientos, debido a su eficacia, economía y facilidad de aplicación. La degradación de la película aplicada sobre el acero por los agentes atmosféricos es resultado de la combinación de diversos factores ambientales, debido a las variaciones cíclicas altamente destructivas. El presente trabajo pretende determinar la existencia de diferencias estadísticas significativas en las distribuciones del espesor de recubrimiento en sistemas dúplex (Fe/Zn/Pintura), antes y después de realizado el ensayo de humedad y temperatura con condensación en atmósfera constante, a partir de diferentes pruebas realizadas en el software Statgraphics Centurion. Se demostró la influencia de las condiciones prefijadas sobre el espesor de recubrimiento antes y después de realizado el ensayo. Dichos valores se encontraron en un intervalo adecuado para garantizar la resistencia a la corrosión, no evidenciándose deterioro visible en la superficie de las probetas analizadas.
[en] As a promising chemiresistor for gas sensing, the single-walled carbon nanotube (SWCNT) network has not yet been fully utilized for humidity detection. In this work, it is found that as humidity increases from 10% to 85%, the resistance of as-grown SWCNT networks first decreases and then increases. This non-monotonic resistive response to humidity limits their sensing capabilities. The competition between SWCNT resistance and inter-tube junction resistance changes is then found to be responsible for the non-monotonic resistive humidity responses. Moreover, creating sp"3 scattering centers on the SWCNT sidewall by monovalent functionalization of four-bromobenzene diazonium tetrafluoroborate is shown to be capable of eliminating the influence from the inter-tube junctions, resulting in a continuous resistance drop as humidity increases from 10% to 85%. Our results revealed the competing resistive humidity sensing process in as-grown SWCNT networks, which could also be helpful in designing and optimizing as-grown SWCNT networks for humidity sensors and other gas sensors. (paper)
[en] The temperature and the relative humidity influence in the stability of thermoluminescent response of LiF: Mg,Ti(TLD-100), LiF: Mg,Ti(TLD-700), CaSO4: Dy+Teflon(D-CaSO4: Dy-0,4), CaF2: Dy(TLD-200) e Li2B4O7: Mn,Si, during 30 days were studied. The responses behaviours of this materials irradiated before and after the storage period were also compared. (C.G.C.)
[pt]Foi estudado a influencia da temperatura e da umidade relativa na estabilidade da resposta termoluminescente do LiF: Mg,Ti(TLD-100), LiF: Mg,Ti(TLD-700), CaSO4: Dy+Teflon (D-CaSO4: Dy-0,4),CaF2: Dy(TLD-200) e Li2B4O7:Mn,Si, no periodo maximo de 30 dias. Foram comparados os comportamentos das respostas destes materiais irradiados antes e apos o periodo de estocagem. (autor)
[en] The study of the sorption curve representing the development of water content versus relative humidity, in barley seeds (CV. Thibaut), shows that water is present in three different states: Constitutive water at less than 8.1%, absorption water between 8.1 and 10.9%, and free water at more than 10.9%. Along with these states, radiosensitivity is respectively high, low, and high. The seeds detached from the rachis have less radioresistance than the attached ones. However, this difference in behaviour is reduced when the water content is high (presence of free water). We also observed that growth was stimulated by weak doses of irradiation (20 Gy), whatever the water content was. (author). 35 refs., 4 figs., 1 tab
[en] On a field plot of about one hectare of Terra Roxa Estruturada (Alfisol) it was verified that soil spatial variability is an important factor for the calibration of neutron probes, to the extent that this methodology is not suitable for precise and absolute values of soil water content. Data from a 25 access tube transect showed however, that the methodology is consistent and can be used with success in cases of measurements of temporal changes of soil water content or soil water storage. (author)
[en] Dry shrimp obtained from the market were packed in polyethylene pouches. Each pouch contained the same weight of the sample. They were subdivided into two groups of atmospheric and vacuum pack. The sample packages were then exposed to radiation doses of 1, 2 and 3 kGy. All irradiated samples together with the untreated ones were stored at room temperature for the investigation of the changes on microbiological and chemical properties. The results indicated that a microbial load of approximately 107 colonies/g was found in nonirradiated shrimp. The count was decreased to 104, 103 and 10 colonies/g by the irradiation dose of 1, 2 and 3 kGy respectively. The microbiological analysis revealed that the dose of 3 kGy permitted the longest extended shelf life for additional 40-75 days. No difference in the results obtained between vacuum and atmospheric pack in polyethylene pouch under the experimental conditions. The low TBA values of 6.5 - 10.4 in all tested samples showed that irradiation caused only little change on fat composition. Polyethylene pouch could prevent the loss of moisture content from the dry shrimp
[en] In this article the advantages, disadvantages, principles and calibration of the neutron moisture meter are shortly discussed, as well as the effect of soil density and type on the calibration curve of the neutron moisture meter
[en] The results of hard-coal moisture-content measurements, performed with the aid of the ZAM-WILMER microwave meter are presented. Over 80 ground coal samples, weighing 1.5 kg (approx.) each, were examined. The moisture content values ranged from 0 to 15 wt%, with the mean standard error being equal to 0.8 wt%. 5 refs., 2 figs., 1 tab. (author)
[en] The effect of four levels content (i.e. gravel-free, 0-20, 20-40, 40-60%) by weight on the calibration of neutron moisture gauge was investigated. If the calibration relation is not corrected for gravel content then it underestimates field water content. The slope of the calibration curve generally decreases with increasing gravel content. The gravel-free calibration is significantly different from those for gravel of 40 and 60%. The regression equation for 20% gravel content is not significantly different from that for gravel-free content. It seems that there may be a threshold value of gravel content at which the neutron ratio is influenced significantly. (author). 7 refs., 2 tabs., 4 figs