Uso de métodos químicos para obtener polvos cerámicos del sistema (Sn, Ti)O2

The (Sn,Ti)O2, system has a great interest due to its technological applications such as gas sensor and varistor. Although the thermodynamic properties and the kinetics of spinoidal decomposition in this system have been extensively studied, the general properties and applications of SnO2 - TiO2 binary compositions have been not investigated yet in depth. On the other hand, little work has been done to optimize the synthesis methods to obtain (Sn,Ti)O2 cerallmic powders, with pre - determinate physical and chemical characteristics. In this work the ceramic powders has been obtained by coprecipitation and polymeric precursor (Pechini) methods. The different physical chemistry phenomena that occurred during the synthesis were discussed. The (Sn,Ti)O2, ceramic powders were characterized with X- ray diffraction (XRD), thermal analysis (DTA/TG) and scanning electron microscopy (SEM). The knowledge about of steps and variables of synthesis process acquired with development of this work, we permited to obtain (Sn, Ti)O2, nanometers particles to low temperatures: to 450°C for coprecipitation method and to 600°C for Pechini method. The spinodal decomposition that ocurr to 900°C was discussed also.

Aspectos químicos, biológicos e etnofarmacológicos do gênero Cassia

Species of Cassia are widely distributed in tropical and subtropical regions throughout the world, and have been extensively investigated chemically and pharmacologically.They are known to be a rich source of phenolic derivatives, most of them with important biological and pharmacological properties. Some Asian, African and Indian tribes use these species as a laxative, purgative, antimicrobial, antipyretic, antiviral and anti-inflammatory agent. Among a number of other classes of secondary metabolites, such as anthracene derivatives, antraquinones, steroids and stilbenoids, biologically active piperidine alkaloids are an especially important bioactive class of compounds that showed to be restricted to a small group of Cassia species. In this paper we present an overview of the chemical, biological and ethnopharmacological data on Cassia piblished in the literature.

Métodos químicos para obtener varistores basados en SnO2

Synthesis of SnO2 ceramic powders was made by coprecipitation method and polymeric precursor method (Pechini) to obtain Sn-Co-Nb-Ti-Al varistor systems. The particles of the obtained ceramic powder presented nanometric size and SnO2 was the principal crystalline phase in them according to X-ray diffraction results. To determine the behavior of the synthesized samples in front of the thermal treatments, thermal analysis (DTA/TG) were made. Dilatometric studies on previously pressed samples were carried out. The optimal conditions of sintering of this raw material were determined. Microstructures and electric properties of sintered samples were studied using scanning electron microscopy (SEM) and I-V characteristics curves. The samples presented varistor behavior independent of the synthesis method used, with high nonlinearity values as 32. The presence of Al3+ favored the concentration of oxygen vacancies, and the grain growth.

Aspectos físico-químicos e microbianos do queijo maturado por mofo obtido da coagulação mista com leite de cabra congelado e coalhada congelada

Milk goats are indicated as an economic alternative for small farmers and cheese making could improve their profits. Goat's milk has a seasonal production characteristic and shows periods of abundance and others of scarcity. The use of frozen milk or frozen curd to make cheese can be used to solve the problem. The aim of this work was to evaluate the preparation of cheese made from mixed curd and ripened by Penicillium candidum mould using slow frozen milk (in a domestic freezer) or fast frozen milk (by liquid nitrogen). The slow frozen curd and fast frozen curd without whey were used. It was observed that the cheese from the slow and fast frozen milk and from the slow and fast frozen curd did not differ from the control cheese for the yield, chemicophysical characteristics, chemical composition, extention ripened rate, depth ripened rate and microbiological aspects, even when it was expressed as a dry matter content of cheeses.

Determinação da distribuição de um nível de turbidito na formação Macaé no campo de Namorado através de uso de atributos sísmicos

This study was developed on the basis of petrophysics characterization, 3D seismic interpretation, and rock-wire-log integration. The results were integrated with amplitude attribute through cross plot (rock attribute x amplitude value). 3D seismic data also allowed inteipreting the top of Lagoa Feia, Macaé, and Carapebus formations, and Outeiro Member. The analyses of the maps of structures and attributes, integrated with wire-log data, suggest that Namorado turbidite level is candidate to be mapped with stratigraphic attributes like AverageTroughAmplitude, RMS velocity and Total AbsoluteAmplitude. Lagoa Feia Formation attribute maps (Dip-Azimuth and TotalEnergy) allows to interpret a low fault density at the carbonate coquina level in the Namorado field. This level is also considered one at the best seismic reflector and an important reservoir of the Campos Basin.

Uso de regressão linear para estimar parâmetros físico-químicos relacionados à qualidade do jerked beef

Jerked beef is officially defined as salted, cured and dried beef. Water activity (Aw), moisture, ash and residual nitrite are the physicochemical parameters that define this product identity and quality standards. In this work, the behavior of these parameters during jerked beef processing was evaluated and a significant correlation among them was revealed. These results allowed the establishment of statistical equations that enable the estimation of all the physicochemical parameters from the results obtained in the measurement of just one of them.

Espécies invasoras: Conceitos, modelose atributos

The distribution of species in ecosystems is influenced by several biotic and abiotic factors, and physical barriers operate as filters to dispersion. The ancient processes of human migration and settlement, and the recent globalization trends are the main responsible factors for the transposition of geographic barriers by organisms and species introduction in regions outside their original distribution range. In order to designate introduced species, the adopted terminology may eventually lead to a lack of operational definitions, misleading the interpretation of paradigms concerning the invasion process. According to the literature, the criteria i) biogeographic, ii) population growth, and iii) spreading in the invaded region, should be taken into account as a manner to avoid subjective interpretations. Most of the presented models are inserted in the same paradigms to explain the status of the invasion process (arrival, establishment and invasion), although each model has its own concepts. Many authors consider both characteristics of the invader species and of the invaded environments to explain species success and establishment. The use of clear concepts, well established and non subjective concepts of introduced and invading species as well as its derivatives is crucial to unify the paradigms of the invasion process.

Avaliação de interpoladores estatísticos e determinísticos na estimativa de atributos do solo em agricultura de precisão

The obtaining of the correct space distribution for attributes of the soil is relevant in the agricultural planning, in what concerns to the installation and maintenance of the cultures. The objective of that work was to compare statistical interpolation methods (ordinary krigagem) and deterministic methods (inverse square distance) in the estimate of CTC and V% in a distrophic yellow-red Latossolo. The study was accomplished in the State of Experimental Hands on of the Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural (INCAPER), in an irregular grading with 109 points. The data were collected in the layer of 0 - 0,20 m in the projection of the cup of the plants, in the superior part of the slope. The performance of the interpolators was obtained and compared using the criterion of the medium mistake. The observations are dependent in space until a maximum reach of 14,1 m, considering the isotropy. IDW presented larger mistake in the estimate of the data; however its difference in relation to KRIG was small for both variables.

Avaliação comparativa da eficácia de fitoterápicos e produtos químicos carrapaticidas no controle do boophilus microplus (Canestrini, 1887) por meio do biocarrapaticidograma

The aim of this research was to evaluate the efficacy of plant extracts and chemical products for the control of Boophilus microplus. Three commercial products for the control of Boophilus microplus were in vitro evaluated, chemical compounds of cypermethrin + DDVP and organophosphate as recomended by the manufacturer, and also four plant extracts, Azadirachta indica (1%), Cymbopogon densiflorus, Lippia alba and Ipomoea asarifolia at different concentrations. The results showed that the chemical compounds tested had efficacy lower than 95% against the Boophilus microplus samples in the experiment. The extracts of all plants have shown some biological activity in the mortality of ingurgitated females and inhibition of egg crash, however the extract of Azadirachta indica presented efficacy higher than 95% in all tested concentrations, being the best sample tested in this experiment.

Protocolo para ensaios físico-químicos de estabilidade de fitocosméticos

The growing demand for stable, safe and effective cosmetics has required increasingly complex studies by the scientific community and the use of more efficient techniques to determine the stability of these products. The use of active principles from the Brazilian flora has led to the development of numerous products, in the most varied pharmaceutical forms, making it, even more difficult to standardize experimental protocols to certify the stability of cosmetic preparations. While in Brazil there is no one protocol that standardizes the tests that should be carried out to determine product stability, several studies have been conducted in academic laboratories to determine the stability of specific raw materials. The rheological properties of topical use products have to be taken into account in their manufacture, storage and application. The determination of the rheological behavior of a formulation helps in evaluating the physicochemical nature of the vehicle, allowing early signs of physical instability to be detected and thus enabling quality control of the constituents, test formulations and final products. Thermal analysis has also been used to assist in the study of cosmetic stability and differential scanning calorimetry to guide the development of new products. Other tools, such as fluorimetry and laser granulometry can be used to help the study and development of both emulsified and non-emulsified systems. The aim of the present study is to develop a protocol for the investigation of the physical and chemical stability of phytocosmetics - systems containing active compounds extracted from the Brazilian biodiversity.

Efeito da aplicação de maturadores químicos na cultura da cana de açúcar (Saccharum spp.) variedade SP81-3250

Sugarcane is one of the most important grass crops. This study evaluated the effects of chemical ripeners on the sugarcane variety SP81-3250 in terms of technological quality. The experiment was arranged in randomized blocks with split split-plots. Main treatments were: 1) Control; 2) Aminolon Maduracion, at a rate of 0.7 L of commercial product (c.p.) ha -1; 3) Aminolon Maduracion, at a rate of 1.0 liter of c.p. ha -1; 4) Aminolon Maduracion, at a rate of 1.3 liter of c.p. ha -1; 5) Trinexapac-ethyl (Moddus), at a rate of 0.8 liter of c.p. ha -1. Secondary treatments were the sampling dates: 10 days before application (- 10 d.a.a.); 11; 46; 71; 100 and 117 d.a.a. (days after application). Ripeners differently affected the technological parameters, and trinexapac-ethyl showed the best behavior, followed by Aminolon (0.7 L of c.p. ha -1). The best results were found at the 3rd and 4th sampling dates, 46 and 71 days after application, respectively.

Variação sazonal de alguns parâmetros físicos e químicos em três rios pertencentes a uma bacia de drenagem na região centro-sul do Estado do Paraná, Sul do Brasil

Three small rivers belonging to the Rio das Pedras basin, located in the mid-southern region of Paraná state, were studied in order to evaluate the seasonal variation pattern of some physical and chemical parameters. Monthly samplings were carried out from April 2004 to March 2005. The following limnological parameters were measured: water temperature, specific conductance, oxygen saturation, pH, turbidity, current velocity and depth. The waters of the Rio das Pedras basin presented very peculiar characteristics, showing typical seasonal patterns for some of the studied limnological variables. An Analysis of Variance (Anova) showed significant differences only for pH and depth among streams. A Principal Component Analysis (PCA) showed a weak tendency to form groups based on seasons instead of sampling sites. The results, in general, indicate that temporal variations of the environmental parameters analyzed were not sufficient to draw a clear seasonal pattern in the Rio das Pedras basin. Most likely, the lack of an obvious seasonal pattern has been provoked by a particular regional precipitation regime, where rains are frequent and well-distributed throughout the year.

Influência da queima e aditivos químicos e bacterianos na composição química de silagens de cana-de-açúcar

The objective of this trial was to evaluate the effect of the chemical (urea, sodium benzoate, and sodium hydroxide) and microbiological (Propionibacterium acidipropionici + Lactobacillus plantarum, and Lactobacillus buchneri) additives on the sugarcane nutritive value, ensiled crude or after burned, using a factorial scheme 2 (burned or crude sugar cane) x 6 (five additives urea, sodium benzoate, sodium hydroxide, Propionibacterium acidipropionici + Lactobacillus plantarum, and Lactobacillus buchneri plus control). It was evaluated the sugar cane chemical composition, before and after ensilage. The sugar cane NDF contents increased (51.3%, before ensilage) to 67.8% after fermentation period. The highest true digestible dry matter recovery values, 83.6 and 79.8% were observed on the burned sugar cane silage treated with NaOH or L. buchneri, respectively. The NaOH, and L. buchneri showed more efficiency in reducing nutritive looses during the fermentation phase of the crude or burned sugar cane silage.

Qualidade fisiológica e sanitária de sementes de mamona submetidas a diferentes tratamentos químicos

The use of fungicides for treating seeds has become an essential measure in the control of pathogens. However, the effectiveness of many products is not well-known to some crops. The objective of this research was to evaluate the effect of different doses of carbendazin and carboxin + thiram fungicides for controlling pathogens and their interference on the physiologic quality of castor bean seeds. The test consisted of the following treatments (g i.a./100 kg of seeds): carbendazin (15, 30, and 60), carboxin + thiram (25 + 25, 50 + 50, and 100 + 100), formol 0.15% (v/v), and control (distilled water). The physiologic quality of the seeds was determined by germination, first counting, field emergence, speed emergence index, length, fresh and dry weight of the aerial part, and electrical conductivity. There were no statistical differences for germination and fresh and dry matter index. The treatment with formol provided lower values for first counting and field emergence. Seeds treated with fungicides presented higher values for electrical conductivity, but did not differ, statistically, among themselves. The fungi Cladosporium spp.; Bipolaris spp.; Curvularia spp.; Aspergillus flavus; Aspergillus niger; Rhizopus sp.; Penicillium sp.; Rhizoctonia sp.; Verticillium sp.; Fusarium sp.;Arthrobotrys sp.; and Epicocum sp. were identified. All tested products, independently of the dose, provided efficient control for pathogens.

El desarrollo sostenible en América Latina y el Caribe: tendencias, avances y desafíos en materia de consumo y producción sostenibles, minería, transporte, productos químicos y gestión de residuos. Informe para la decimoctava sesión de la Comisión para el Desarrollo Sostenible de las Naciones Unidas

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