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[en] Ulexite is one of the boron minerals, which include a respectable amount of hydration water. It can be used as a raw material in the production of boron compounds. Some part of water in the composition of ulexite can be removed from the solid matrix applying dehydration treatment, and a porous structure can be obtained to increase the reaction rate. In the present study, the effect of dehydration temperature on dissolution kinetics of ulexite in ammonium sulfate solutions was researched in a batch reactor utilizing the parameters of solution concentration, solid-to-liquid ratio, stirring speed and reaction temperature. It was determined that the dissolution rate of calcined material increased with increasing solution concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was attained with the sample calcined at 150 °C. It was found that the dissolution rate fit to the first order pseudo-homogeneous model. The activation energy of the dissolution process was estimated to be 42 kJ·mol−1.
[es]La ulexita es uno de los minerales de boro, que incluye una cantidad considerable de agua de hidratación. Se puede usar como materia prima en la producción de compuestos de boro. Una parte del agua existente en la composición química de la ulexita puede eliminarse de la matriz sólida aplicando tratamiento de deshidratación que permite obtener una estructura porosa, que aumenta la velocidad de reacción. En el presente trabajo, se estudió el efecto de la temperatura de deshidratación sobre la cinética de disolución de ulexita en soluciones de sulfato de amonio, en un reactor discontinuo estudiando los parámetros de concentración de solución, relación sólido/líquido, velocidad de agitación y la temperatura de reacción. Se determinó que la velocidad de disolución del material calcinado aumentaba al aumentar la concentración de la solución y la temperatura de reacción y con la disminución de la relación de sólido/líquido. La velocidad de disolución más alta se alcanzó con la muestra calcinada a 150 °C. Se encontró que la velocidad de disolución se ajusta al modelo pseudohomogéneo de primer orden. La energía de activación del proceso de disolución se estimó en 42 kJ·mol−
[en] The effect of vinasse (alcohol distillery residue) on the dynamics of ammonium sulphate fertilizer (labelled with 7.95 atoms % sup(15)N) was studied. The experiment was carried out under laboratory conditions, with an oxisol, in 15 cm plastic collumns. Ammonium sulphate was applied at a rate of 69 kg N/ha, with two treatments, 0 and 120 m sup(3)/ha of vinasse. Moisture was kept constant throughout the experiment. Sampling was performed weekly until 108 days. The results showed that N immobilization was higher in the vinasse treatment. Total fertilizer N recovery was also higher for the vinasse treated soil, at the beginning of the experiment. At 90 days both treatments showed similar recovery, with a slight trend toward higher recovery in the vinasse treatment. A high percentage of the applied fertilizer was unaccounted for at the end of the experiment suggesting that volatilization and/or denitrification were highly active. (author)
[en] A 24 kDa protein was purified from the seeds of L. sativus by ammonium sulfate fractionation and ion-exchange chromatography. Crystals were obtained by the hanging-drop vapour-diffusion method. A 24 kDa protein was purified from the seeds of Lathyrus sativus by ammonium sulfate fractionation and ion-exchange chromatography. The N-terminal amino-acid sequence showed significant homology with the 2S albumin class of seed storage proteins. The protein showed 85% sequence homology with the seed albumin of Pisum sativum within the 40 N-terminal residues. Crystals were obtained by the hanging-drop vapour-diffusion method. The crystals belonged to space group P212121, with unit-cell parameters a = 43.5, b = 82.7, c = 153.4 Å
[en] Radioimmunoassays for mouse IgE antibodies, based on adherence to an antigen-coated surface, are precise and sensitive, but errors can be introduced by the presence of relatively high concentrations of non-IgE antibodies of the same specificity. Such errors are caused by competition for the limited number of antigenic determinants on the antigen-coated surface. In this paper we explore further the quantitative aspects of the 'competition effect'. An easily applied method is described, based on preferential precipitation of non-IgE antibodies by ammonium sulfate, that permits analysis of IgE antibodies in the presence of large amounts of non-IgE antibodies (that are principally IgG). For IgE anti-Ar, the maximum permissible ratio is extended from approx. 1500:1 to at least 40,000:1. We have also determined the effect of IgG antibodies or whole mouse serum on PCA reactions of mouse IgE antibodies, carried out in rats. (orig.)
[en] A pot experiment was carried out to evaluate the ability of some plant residues to meet total N demand of wheat crop in sandy soil and their performance to reduce chemical N fertilizer requirements. Residue-N sources, i.e. soybean and wheat residues were compared to ammonium sulfate as inorganic N source as well as mixtures of residue-N sources and (NH4)SO4 in ratios of (3:1), (1:1) and (1:3), respectively. The nitrogen application rate in all amended pots was kept at 100 mg N pot-1. The obtained results could be summarized as follows: 1) ry weight of straw and grains of wheat crop was significantly increased this at the addition of nitrogen sources as a result of N-uptake increased. The highest value was observed at the application treatment ratios of (1:1) and (1:3) on the basis of (residue: ammonium sulfate), which can be arranged in this order: Soybean > wheat + soybean > wheat residues. 2) he value of N derived from residues (Ndfr) and fertilizer (Ndff), as well as 15N-recovery ratios can be arranged in this order: Ammonium sulfate > soybean residue > Soybean + wheat residue > wheat residue. 3) he values indicated that 15N-labelled soybean residue in combination with ordinary, ammonium sulfate at the ratios of (*25: 75) and (*50: 50), respectively was found to be effective on 15N-recovery ratios in the straw and grains of wheat crop. 4) he present study indicates that the entire N requirements of wheat crop cannot be met by the separate application of any residue-N source examined.
[en] A sequence field experiment has been conducted for determining the capability of N2-fixation by several legume trees. The experiment was designed using a randomize design with 4 replicates. Each replicate was planted with 100 legume trees and 100 non legume trees. The isotope plot, where 15N was applied with 18 legume trees and 18 non legume trees. The planting distance was 1m x 1m. For the calculation of N2-fixation each legume and standard tree (Eucalypthus alba) was applied with 12.52g in the from of ammonium sulfate with 10.12% 15N. The 15N AS was applied in three splits 11 month earlier. Data obtained from this experiment showed that percentage of N derived from fixation (%N-dfF) of all legume trees was reasonable high. The legume trees used in this experiment were, Leucaena leucocephala, Acacia mangium, Caliandra tetragona, Flemengia congesta and Gliriciadia sepium with potential fixation from 62.31% to 90,68%. (author)
[en] A 2S albumin from L. culinaris was purified and crystallized and preliminary crystallographic studies were carried out. Lens culinaris (lentil) is a widely consumed high-protein-content leguminous crop. A 2S albumin protein (26.5 kDa) has been identified using NH2-terminal sequencing from a 90% ammonium sulfate saturation fraction of total L. culinaris seed protein extract. The NH2-terminal sequence shows very high homology to PA2, an allergy-related protein from Pisum sativum. The 2S albumin protein was purified using a combination of size-exclusion and ion-exchange chromatography. Crystals of the 2S seed albumin obtained using the hanging-drop vapour-diffusion method diffracted to 2.5 Å resolution and were indexed in space group P41 (or P43), with unit-cell parameters a = b = 78.6, c = 135.2 Å
[en] The direct radioimmunoassay procedure for the detection of human α-fetoprotein is described. The technique requires 20μl of sample for a single estimation and includes ammonium sulfate precipitation. The whole assay can be completed in 18 hours. AFP concentrations ranging from 2 ng/ml to 500 ng/ml can be quantified with reproducibility sufficient for clinical as well as experimental purposes. (author)
[en] The transformations to which nitrogen fertilizer is subject when applied in conjunction with 'vinhaca' to a soil, using tagged 15N fertilizer were studied. The soil used was a Dark Red Latossol, medium texture, and 'vinhaca' was apllied at a rate of 200 m3/ha, together with 38 Kg N/ha of ammonium sulphate labelled with 9.91 atom% 15N. Three levels of soil moisture were used: 40, 60 and 80% of the moisture retention capacity of the soil. Samples were analysed at 0, 5, 11, 15, 33, 60 and 88 days of incubation time, to determine NH+4-N, NO-3-N and organic-N, and 15N on these forms as well. Some flasks were used in order to monitor 15N2 evolution from the soil. The quantity of applied N imobilized to organic forms was about 40% for all moisture; the velocity of the imobilization however, was different for the various treatments. At the end of the incubation period, 13, 10 and 32% of the applied N could not be accounted for, at the 40, 60 and 80% moisture, respectively, thus indicating that denitrifiers were active, mainly at higher moisture. (author)
[pt]O presente trabalho teve por objetivo acompanhar as transformacoes pelas quais passa o nitrogenio mineral adicionado como complementacao a adicao de vinhaca ao solo, utilizando 15N como tracador. Foi utilizado um Latossolo Vermelho Escuro, textura media, ao qual foi aplicado 200 m3/ha de vinhaca de caldo misto, complementada com 38 Kg N/ha na forma de sulfato de amonio, marcado com 9,91% de atomos de 15N. Foram mantidos tres niveis de umidade: 40, 60 e 80% da capacidade de retencao da agua deste solo. Foram feitas amostragens aos 0, 5, 11, 15, 33, 60 e 88 dias de incubacao, analisando-se as amostras para determinacao de NH+4-N, NO-3N e N Org e tambem 15N nestas fracoes. Alguns frascos foram utilizados para monitoracao da liberacao de N2. A quantidade de N imobilizado em formas organicas foi de cerca de 40% para todas as umidades, sendo porem a velocidade do processo diferente entre os tratamentos. Ao final da incubacao, 13, 10 e 32% do nitrogenio adicionado nao foi recuperado para as umidades de 40, 60 e 80% da capacidade de retencao de agua, respectivamente, indicando a existencia de um processo denitrificante. (Autor)