Stress induced ordering due interstitials in Nb-4.7 at.%Ta

The presence of interstitial elements in metals cause strong changes in their physical, chemical or mechanical properties. These interstitial impurities interact with the metallic matrix atoms by a relaxation process known as stress induced ordering. Relaxation processes give rise to a peak in the internal friction spectrum, known as Snock effect. The presence of substitutional solutes has a strong influence on Snoek effect, particularly if the substitutional solute element is the one, which interacts with the interstitial element. Anelastic spectroscopy measurements provide information of the behavior of these impurities in the metallic matrix. In this paper, polycrystalline samples of Nb-4.7 at.%Ta alloy have been analyzed in the as-received condition. Measurements of anelastic spectroscopy were carried out using an inverted torsion pendulum, operating with frequency of 2.0-30.0 Hz and in a temperature range between 300 and 700 K. It was observed the presence of a relaxation structure that have been attributed to stress induced ordering due to interstitial atoms around atoms of the metallic matrix. The relaxation structure have been decomposed in its constituent peaks, what it allowed to identify the following relaxation processes: Ta-O, Nb-O and Nb-N. (c) 2005 Elsevier B.V. All rights reserved.

Mineralogy and forms of potassium in red yellow latosol of a guava (Psidium guajava) tree orchard

A trial was conducted during 1994-95 to study the effect of potassium fertilization on a guava (Psidium guajava L.) culture for 3 years. The control plots (without K) showed fruit production and potassium exportation that did not agree with the levels obtained by chemical analysis of the soil. Physical, chemical, mineralogic and morphologic analyses were performed on the red yellow latosol to identify minerals able to supply potassium, with emphasis on the fact that guava trees have a considerably widespread root system. The results obtained confirmed the presence of minerals in this soil that can supply potassium to the trees through weathering. Feldspars were identified in the silt fraction and micas in the clay fraction by X-ray diffractometry. The determination of total potassium revealed that the silt fraction of the soil had the largest absolute amounts of potassium, followed by clay. However, in view of its greater content, clay was the fraction that contributed most to the total amounts of potassium detected.

The use of extruded feed in fish food

In our country, the intensive culture of fish has been making progress due to the availability of extruded rations, which are characterized by the way they have been formulated to assist the nutritional demands of the tropical species and for facilitating a better practice of alimentary handling. This process checks the extruded product density and the desirable physical/chemical aspects to a diet that should be handled in the water, the critical factor of this activity. It is important to emphasize that this product stays to the surface of the water, facilitates the consumption control and the observation of the general aspects of the school of fish, as well as guaranteeing that no deterioration of the physical/chemical characteristics of the water occurs. The floating characteristic of the extruded ration is preferable for farmers because most of the tropical species feed at the surface of the water. In some cases, in the function of the alimentary habit, the thermal conditions of the water and the handling system produce granules with different densities. This is due to the humidity and the applied cooking heat, which modifies the time of hydration, and consequently the ability to float. To establish the physical presentation idea for a ration for tropical fishes, it is necessary that the pellets come in sizes, textures, humidities and densities in order to allow for the different phases of the lives of the fishes. This ration should be the result of characteristics of the species, such as the anatomophysiologics particularities, alimentary habits, digestive capacity and alimentary behavior. Only in this way is it possible to offer to those fishes a ration whose nutritious value and physical presentation facilitate the best biological and economic answers.Those aspects need to be reviewed because the tropical species that are cultivated in our country present selective behavior in relation to the size of the pellet. Generally, this has access to the digestive system without waste; the digestibility, therefore, is dependent upon the size of the particles and the physical aspects of the pellets. They should still consider that those granules could be less abrasive and softer. The extruded rations available in the national market present a qualitative reference to its proteic level, whose consequence allows us to infer that those are overestimated for the final phase of those fishes. Thus, the final cost of production is made unfeasible. In this point of view of the development of the national fish culture, and the growing adoption of the intensive system of production, it can link that such progress is a function of the availability of the rations in the extruded form. Although this technique of processing of rations has revolutionized the market in such a way that has been seen as preferable for farmers, some feel that there is a lack of products best suited for the initial phases of fingerlings production.

Influência da utilização da proteína texturizada de soja nas características sensoriais, químicas e funcionais e de processamento do fiambre de frango

This research was designed to study the effect of addition of 5, 10 e 15% of textured soy protein (TSP) on sensorial, chemical, and physical-chemical parameters of chicken loaf with ground meat. The sensorial properties were not affected by textured soy protein. The addition of textured soy protein in preparing chicken loaf increased the water absorption and holding capacity, and decreased the moisture and ether extract content, but did not increase the final product yield.

Estudo das propriedades de troca iônica e/ou adsorção da celulose e celuloses modificadas

In this work it was studied the capacity of cellulose and chemically modified celluloses (carboxymethylcellulose, cellulose phosphate and oxicellulose) to adsorb copper(II) cations of aqueous and non aqueous solutions. The influence of the principal physical chemical parameters on the adsorption process was examined using the batch adsorption method and copper(II) perchlorate solutions, the maximum adsorption capacity determined for adsorbents were as follows (mol.g(-1)): cellulose, 0.54 . 10(-5); carboxymethylcellulose, 1.28 . 10(-4); cellulose phosphate, 1.12 . 10(-4); oxicellulose, 0.38 . 10(-4).

Role of the surface state and structural feature in the thermoreversible sol-gel transition of a zirconyl aqueous precursor modified by sulfuric acid

The sols produced by admixture of ZrOCl2 acidified solutions to hot H2SO4 aqueous solutions were studied to clarify the effects of Cl- and SO42- ions on the kinetic stability of nanoparticles and to obtain some new evidence concerning the mechanism of a thermoreversible sol-gel transition observed in this system. The study of suspensions prepared with different molar ratios R-S = [Zr]/[SO42-] and R-Cl = [Zr]/[Cl-] revealed domains of composition of formation of thermoreversible gels, thermostable sols, and powder precipitation. The effects of R-S and R-Cl on the structural features of nanoparticles and on the particle solution interface were systematically analyzed for samples of thermoreversible and thermostable sol domains. Small-angle X-ray scattering measurements revealed the presence of small fractal aggregates in all samples of thermoreversible domains, while compact packing aggregates of primary particles are present in the thermostable sol. Extended X-ray absorption fine structure and elemental chemical analysis revealed that irrespective of the nominal value of R-S and R-Cl all studied samples of the thermoreversible domain are constituted by a well-defined compound possessing an inner core made of hydroxyl and oxo groups bridging together zirconium atoms surrounded on the surface by complexing sulfate ligands. zeta potentials of powders extracted by freeze-drying from the thermoreversible gel revealed a point of surface charge inversion attributed to the specific adsorption of SO42- ion. Thermoreversible gel formation is rationalized by considering the effect of the specific adsorption on the electrical double-layer repulsion together with the temperature dependency of the physical chemical properties of ions in solution.

Avaliação do óleo de soja submetido ao processo de fritura de alimentos diversos

The main objective of this study was to evaluate the degree of degradation of the soybean oil used in frying processes. The quality of the oil during the frying process was evaluated by means of physical-chemical analyses, such: conjugated dienes (%) and TBA index (mmoles g(-1)), and determination of total polar compounds (%). It was observed that the values of conjugated dienes increasing significantly with time until 1.87% after 15 hours for fry pans I and 1.76% after 22.5 hours for fry pans II. The TBA indexes reached at the end the frying process values of 0.0265 and 0.0210 mmoles g(-1) for fry pans I and II, respectively. The percentages of total polar compounds have shown an increase of six and eight times in relation to the original sample starting from 5.9% and 3.7% and reaching values of 36.8% and 29.2%, for fry pan I and II, after 15 and 22.5 hours of heating, respectively. It has been concluded that the alterations of the soybean oil increased as the time of frying increased, for both fry pans. The oil used in fry pan I showed greater alteration than the that observed in the oil used in fry pan II, in spite of the time of heating being shorter. Taking into consideration that the levels of polar compounds should be less than 25% according to the legislation of several countries, the oils used in both fry pans were already inadequate conditions at the moment of disposal.

Características físico-químicas, cozimento e produtividade de mandioca cultivar IAC 576-70 em diferentes épocas de colheita.

The instability of cassava culinary quality is a problem in the market. This work had the purpose of evaluating the interference of the productivity, rain precipitation and physical-chemical characteristics on the cooking time of the IAC 576-70 cultivar, from the 6(th) to the 12(th) month after the planting. The physical parameters evaluated were: difficulty in peeling (easy, medium, and hard), difficulty in cutting in long, thin sticks with a manual machine, being those cut in a subjective way. In the analysis of the cooked root, the percentage of water absorbed into the cassava pieces, the color, white points formed inside the pieces of cassava, gel formation around the pieces of cassava, and cooking time were evaluated. The pH, acidity, moisture, ashes, fibers, ether extract, protein, reducing sugars, and starch of the roots were also monthly evaluated. From the results obtained in the present work, it may be concluded that the cassava IAC 576-70, when planted in July, in Botucatu-SP area, must be harvested at the age of nine months, without damage to the productivity, starch level and root cooking, and the harvest could be extended up to ten months. The producers should follow the sum of precipitation index ten days before the harvest, and this value should be the smallest as it may be and the producers should not harvest when this value is more than 100 mm, in order not to hinder the cooking of the root.

Porosity measurement of solid pharmaceutical dosage forms by gamma-ray transmission

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

Use of Biopolymeric Membranes for Adsorption of Paraquat Herbicide from Water

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

Spatial and temporal variability of soil CO2 emission in a sugarcane area under green and slash-and-burn managements

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência da densidade de estocagem no desempenho produtivo do acará-bandeira (Pterophyllum scalare)

The present study aimed to evaluate the effects of three different stock densities (0.33; 0.67 e 1.00 fish L-1) on freshwater angelfish productive performance reared in aquarium. Fish were fed with commercial diets during 35 days in two diary meals. The experimental design was entirely randomized and for each density were used four replicates. Were evaluated physical-chemical water parameters: temperature, oxygen dissolved concentration and total ammonia concentration and growth performance parameters: weight gain, feed conversion, specific growth rate, final standard length, conduction factor and length uniformity. Results were submitted to variance analysis and means were compared by Tukey's test (alpha = 0.05), it was used the statistic program ESTAT 2.0. Mortality was not observed in any tested density. on physical-chemical water parameters, total ammonia level increased significantly with stock density increasing, but they did not showed clinical signs of ammonia toxicity. As there were no significant differences between treatments, stock density 1.00 fish L-1 is the most indicated because it allows higher production.

Análise físico-química e composição nutricional da matéria prima e de substratos pré e pós cultivo de Pleurotus ostreatus

The aim of the present study was to carry out the physical, chemical and nutritional analyses of the alternative substrates formulated from wood and agroindustrial residues of the Amazon for Pleurotus ostreatus (Jacq.:Fr.) Kummer cultivation. The determination of C, N, pH, humidity, soluble solids, protein, fat, total fiber ash, carbohydrates (total and available) and energy were carried out. The substrates were formulated from sawdust of Simarouba amara Aubl. (marupa), Ochroma piramidale Cav. ex. Lam. (pau de balsa) and from the stein of Bactris gasipaes Kunth (pupunheira palm tree), and from Saccharum officinarum L. (sugar cane bagasse). The results demonstrated that the nutritional composition of the substrate is variable and the improvement of the quality of the spent substrate (energy and protein increment) promoted by the metabolism of the fungus during the cultivation, contributed for a more nutritive substrate than the initial one, which could be used as a compost for Agaricus sp. cultivation, as organic fertilizer and for bioremediation for contaminated soils.

Review of Fluconazole Properties and Analytical Methods for Its Determination

Fluconazole, -(2.4-diflurofenil)--(1H-triazol-1-methyl)-1H-1,2,4-triazol-1-ethanol, is an antifungal of triazoles class. It shows activity against species of Candida sp., and it is indicated in cases of oropharyngeal candidiasis, esophageal, vaginal, and deep infection. Fluconazole is a selective inhibitor of ergosterol, a steroid exclusive of the cell membrane of fungal cells. Fluconazole is highly absorbed by the gastrointestinal tract, and it spreads easily by body fluids. The main adverse reactions related to the use of fluconazole are nausea, vomiting, headache, rash, abdominal pain, diarrhea, and alopecia in patients undergoing prolonged treatment with a dose of 400 mg/day. In the form of raw material, pharmaceutical formulations, or biological material, fluconazole can be determined by methods such as titration, spectrophotometry, and thin-layer, gas, and liquid chromatography. This article discusses the pharmacological and physical-chemical properties of fluconazole and also the methods of analysis applied to the determination of the drug.

Effect of electrolyte on the gelation and aggregation of SnO2 colloidal suspensions

Electrolytes may modify the physical-chemical characteristics of colloidal particle interfaces in suspension, which can favour gel or aggregate formation. The influence of NH4Cl loading on the aggregation and gelation of SnO2 colloidal suspensions was investigated using measurements of rheology, turbidity and infrared spectra. A rapid aggregate growth for samples with Cl- > 20 mM was observed. With increasing age, gelation was observed due to formation of interaggregate bonds. For concentration of Cl- between 20 and 9 mM, the aggregation process was slower allowing the formation of gel with a network which was not destroyed as the gel was submitted to a small rate of shear. As aging continues, the condensation reaction between OH groups gave rise to the formation of Sn-O bonds, irrespective of the electrolyte loading. © 1992 Elsevier Science Publishers B.V. All rights reserved.