Abordagem bayesiana multivariada para características de crescimento, fertilidade e escores visuais de rebanhos da raça Brangus

O objetivo deste trabalho foi estimar parâmetros genéticos e tendências genéticas e fenotípicas de uma população da raça Brangus. As características peso, circunferência escrotal e escores visuais de conformação, precocidade, musculatura e umbigo, padronizadas para 550 dias de idade, foram avaliadas a partir de 6.789 registros de animais nascidos de 288 touros e 5.949 vacas, entre 1991 e 2001, em 49 fazendas localizadas nas regiões Centro‑Oeste, Sudeste e Sul do Brasil. Para a estimação dos parâmetros, das correlações e das tendências genéticas, foi adotado o modelo animal linear‑limiar hexacaracterística. As estimativas de herdabilidade direta foram de 0,39 e 0,27, para peso e circunferência escrotal, respectivamente, e de 0,22, 0,20, 0,23 e 0,33 para conformação, precocidade, musculatura e umbigo, o que indica considerável variação genética aditiva e que é possível obter ganho genético por meio da seleção. As correlações genéticas entre peso e circunferência escrotal com os escores de conformação, precocidade e musculatura mostram a possibilidade de resposta correlacionada. As tendências genéticas estimadas indicam grande contribuição de fontes de variação não genéticas para todas as características no período estudado, e apontam a necessidade de melhoria das condições ambientais, para que os animais expressem todo seu potencial genético.

Associação genética de escores de conformação com características de crescimento em bovinos da raça Angus

O objetivo deste trabalho foi determinar a associação genética entre escores visuais de conformação e as características de ganho de peso médio diário e de velocidade de crescimento em bovinos da raça Angus à desmama e ao sobreano. Os componentes de covariância foram estimados por modelo animal de análise tetracaracterística, com uso do método de inferência bayesiana, tendo-se assumido o modelo linear para: ganho de peso médio diário do nascimento à desmama (GMD) e da desmama ao sobreano (GMS); e velocidade de ganho de peso do nascimento à desmama (VD) e da desmama ao sobreano (VS). Um modelo não linear (de limiar) foi utilizado para os escores de conformação à desmama (CD) e ao sobreano (CS). As médias a posteriori, para a herdabilidade direta, foram: 0,12±0,023 (CD), 0,15±0,020 (GMD), 0,15±0,024 (VD), 0,17±0,020 (CS), 0,17±0,023(GMS), e 0,17±0,023 (VS). A correlação genética variou de -0,09±0,11 a 0,60±0,06, entre os escores CD e CS e as características de ganho médio diário de peso e velocidade de ganho de peso. A correlação entre CD e CS foi 0,52±0,089. A seleção direta para escores visuais de conformação, ganho médio diário e velocidade de ganho responde de forma lenta à seleção, tanto à desmama como ao sobreano.

Parâmetros genéticos do peso desde o nascimento até 730 dias de idade na raça Indubrasil

O objetivo deste trabalho foi determinar parâmetros genéticos do peso desde o nascimento até 730 dias de idade na raça Indubrasil. Registros de peso (82.481) de 20.890 animais do nascimento aos 730 dias de idade foram utilizados. Os parâmetros genéticos foram determinados por meio de regressão aleatória. Amostras da distribuição a posteriori dos parâmetros de interesse foram obtidas com o amostrador de Gibbs. Polinômios de Legendre ou segmentados foram utilizados para modelar a trajetória média de crescimento. Os efeitos genético aditivo direto e de ambiente permanente direto foram modelados por polinômios de Legendre. Um polinômio segmentado linear-linear, com nó aos 251 dias de idade, ajustou a trajetória média. Polinômios de Legendre quadráticos e quínticos ajustaram, respectivamente, os efeitos genético aditivo e de ambiente permanente. Três classes de idade foram suficientes para modelar a heterocedasticidade residual. Na maior parte do intervalo considerado, as médias a posteriori da herdabilidade foram crescentes, com valores entre 0,10 e 0,45; a proporção da variância de ambiente permanente em relação à variância fenotípica foi constante, em torno de 0,48; e as correlações genéticas dos pesos em diferentes idades foram altas, acima de 0,60. Há variabilidade genética quanto ao peso na raça Indubrasil, e a seleção pode aumentar a média desta característica.

Método colorimétrico para determinação de dióxido de nitrogênio atmosférico com preconcentração em coluna de c-18

An alternative analytical method for nitrogen dioxide (NO2) in atmosphere was developed. The collection of NO2 is performed by a Sep-Pack C-18 cartridge impregnated with 11% (v/v) of triethanolamine plus 3,6 % (v/v) of ethylene glycol plus 25 % (v/v) of acetone combined solution. When the impregnating is used, NO2 is collected with good repeatibility (CV = 3,3 %). The NO2 absorbed in the sampler was stripped from the sorbent with a methanol 5% (v/v) aqueous solution and was determined by colorimetry as nitrite by using the Griess-Saltzman reagent. The detection limit of 1,4 ppb for 60 min sampling at 0,5 L min-1 flow rate was obtained. Preparation and conditioning procedures for TEA-C-18 cartridge, sampling flow rate, absorption capacity and interference of other species are discussed.

Amostragem passiva de poluentes atmosféricos: aplicação ao SO2

The passive sampling technique has been widely used for many years in the measurement of personal exposure to pollutantes in the workplace. In recent years the technique has been used too for measurements in ambient air. In the specific case of SO2 a variety of passive samplers have been described in the literature. The great number are diffusive samplers and some few are permeation samplers. They are basically of two types: badge and tube-type. However there are more than 10 variations in relation to the sampler dimensions, diffusion barriers and pollutant sorption medium. The technique trend to be very used in the near future with samplers able to reach very low detection limits, proposing a viable option for monitoring specific species at urban, regional and global scales.

Análises seqüenciais de agrupamentos aplicadas ao estudo de partículas atmosféricas

The present paper has as objective to apply a sequential Cluster Analysis to the atmospheric particles: Hierarchical Cluster Analysis followed by Nonhierarchical Cluster Analysis. The hierarchical cluster analysis results were used as start point for the nonhierarchical cluster analysis as an agglomerative technique. These particles were taken from two areas of the metropolitan region of Porto Alegre, Charqueadas and Sapucaia do Sul., from may /97 to may/98, using a High Volume Sampler (Hi-Vol). Around 10,000 particles were analysed by Scanning Electron Microscope with Energy-Dispersive X-Ray microanalysis (SEM-EDS). The Hierarchical Cluster Analysis allowed the identification of five groups of particles, whose amounts were differentiated according to the summer and the winter campaigns. The abundance of each type of particles inside each group according to the different sections was verified by the Nonhierarchical Cluster Analysis, resulting in information about the emissions sources. The groups of particles of Si/Al and Si and of Fe/Zn and Fe for Charqueadas were more significant in section 2 and 3 (NW and W wind directions) and in section 1 (SE wind direction), evidencing the influence of the coal power plant and steel industry, respectively located in these quadrants. In Sapucaia do Sul the data were more heterogeneous, causing a certain difficulty to identify the source as anthropogenic. Nevertheless the group of particles containing Fe was found in sectors of NW/W wind directions which shows the influence of the steel plant.

Aplicação da CLAE para determinação do ácido 10-Hidróxi-2-decenóico (10-HDA) em geléia real pura e adicionada a mel brasileiro

The aim of this paper was to determine the 10-HDA in pure royal jelly and products containing royal jelly, using HPLC methodology. 10-HDA is the natural indicator of the presence of royal jelly in products and also gives the authenticity of pure royal jelly. The chromatographic conditions used were: isocratic system, C18-H column, auto sampler, diode array UV-VIS detector (225 nm), mobile phase with methanol/water (45:55), pH= 2.5 and a-naphtol as internal standard. The results obtained using laboratory samples for pure royal jelly were 2.37%, varying from 0.15% for honey with 10% of royal jelly to 2.10% for honey with 90% of royal jelly respectivelly. For commercial products, the 10-HDA content varied from no detectable to 0.026%. The recovery test presented a minumum of 100.44% The detection limit was 45.92 ng/mL and the quantification limit was 76.53 ng/mL.

Review of the synthesis of layered double hydroxides: a thermodynamic approach

The synthesis of layered double hydroxides (LDHs) by hydrothermal-LDH reconstruction and coprecipitation methods is reviewed using a thermodynamic approach. A mixture model was used for the estimation of the thermodynamics of formation of LDHs. The synthesis and solubility of LDHs are discussed in terms of standard molar Gibbs free energy change of reaction. Data for numerous divalent and trivalent metals as well as for some monovalent and tetravalent metals that may be part of the LDH structure have been compiled. Good agreement is found between theoretical and experimental data. Diagrams and tables for the prediction of possible new LDH materials are provided.

Comparação de duas metodologias de amostragem atmosférica com ferramenta estatística não paramétrica

In atmospheric aerosol sampling, it is inevitable that the air that carries particles is in motion, as a result of both externally driven wind and the sucking action of the sampler itself. High or low air flow sampling speeds may lead to significant particle size bias. The objective of this work is the validation of measurements enabling the comparison of species concentration from both air flow sampling techniques. The presence of several outliers and increase of residuals with concentration becomes obvious, requiring non-parametric methods, recommended for the handling of data which may not be normally distributed. This way, conversion factors are obtained for each of the various species under study using Kendall regression.

Construção de amostrador passivo de baixo custo para determinação de dióxido de nitrogênio

A new passive sampling system for monitoring NO2 in air has been developed to measure gas concentrations in indoor and outdoor air. The sampler is inexpensive, and easy to construct and operate. Nitrogen dioxide forms a derivative after reaction with a filter coated with triethanolamine and ethyleneglycol. The nitrogen dioxide derivative is extracted from the filter, and the concentration is determined by colorimetry. To test the sampler for measuring ambient level nitrogen dioxide, measurements were carried out inside homes and in a range of workplace environments.

O emprego de quitosana quimicamente modificada com anidrido succínico na adsorção de azul de metileno

The adsorption capacity of alpha-chitosan and its modified form with succinic anhydride was compared with the traditional adsorbent active carbon by using the dye methylene blue, employed in the textile industry. The isotherms for both biopolymers were classified as SSA systems in the Giles model, more specifically in L class and subgroup 3. The dye concentration in the supernatant in the adsorption assay was determined through electronic spectroscopy. By calorimetric titration thermodynamic data of the interaction between methyene blue and the chemically modified chitosan at the solid/liquid interface were obtained. The enthalpy of the dye/chitosan interaction gave 2.47 ± 0.02 kJ mol-1 with an equilibrium constant of 7350 ± 10 and for the carbon/dye interaction this constant gave 5951 ± 8. The spontaneity of these adsorptions are reflected by the free Gibbs energies of -22.1 ± 0.4 and -21.5 ± 0.2 kJ mol-1, respectively, found for these systems. This new adsorbent derived from a natural polysaccharide is as efficient as activated carbon. However 97% of the bonded dye can be eluted by sodium chloride solution, while this same operation elutes only 42% from carbon. Chitosan is efficient in dye removal with the additional advantage of being cheap, non-toxic, biocompatible and biodegradable.

Diagramas de Ellingham e de Van't Hoff: algumas considerações

The main subject of this article is to show the parallelism betwen the Ellingham and Van't Hoff diagrams. The first one is a graphic representation of the changes in the standard Gibbs free energy (deltarGtheta) as a function of T and was introduced by Ellingham in 1944, in order to study metallurgic processes involving oxides and sulphides. On the other hand, the Van't Hoff diagram is a representation of the function ln K versus (1/T). The equivalence between both diagrams is easily demonstrated, making simple mathematical manipulations. In order to show the parallelism between both diagrams, they are presented briefly and two examples are discussed. The comparison of the both diagrams surely will be helpful to students and teachers in their learning and teaching activities, and will certainly enrich important aspects of chemical thermodynamics.

Desviaciones al modelo logarítmico-lineal en la solubilidad de ibuprofén y naproxén en mezclas cosolventes propilenoglicol-agua

The deviations observed in the solubility of ibuprofen (IBP) and naproxen (NAP) in propylene glycol (PG) + water (W) cosolvent mixtures with respect to the logarithmic-linear model proposed by Yalkowsky have been analyzed at 25.00 ± 0.05 ºC. Negative deviations were obtained in all cosolvent compositions for both drugs; they were greater for IBP. Another treatment, based on Gibbs free energy relationships, was also employed showing an apparent hydrophobicity chameleonic effect, because at low PG proportions NAP is more hydrophobic, whereas at high PG proportions IBP is more hydrophobic. The results are discussed in terms of solute-solvent and solvent-solvent interactions.

Adsorción física sobre sólidos: aspectos termodinámicos

A thermodynamic formalism based on the Gibbs Dividing Surface (GDS) for the description of a solid-fluid interface is presented, so that the adsorption layer is understand as a phase and the adsorption process as the transference of components between a 3-dimensional phase and a 2-dimensional one. Using a state equation derived from the Henry's Law, we shall show how the Langmuir isotherm is deduced from de Gibbs isotherm. The GDS is useful also for understanding the release of heat by a system as the adsorption occurs.

Desenvolvimento e aplicação de sistema passivo de coleta de poluentes atmosféricos para monitoramento de Cd, Cr, Pb, Cu, Fe, Mn, Zn e particulados totais

The objective of this study was to assess a new monitoring technique of particulate and trace metals in the atmosphere via the use of a passive sampler of air pollutants in the city of Goiânia. The average particulate weight and average concentrations of metals Fe, Cr, Zn, Pb, Cu, Mn, and Cd were 0.1104 g and 257.5; 23.4; 17.8; 6.7; 1.9; 0.8; 0.2 μg/m²/day, respectively. Higher Pb and Cr concentrations were obtained in areas with intense traffic. This study revealed that it is possible to monitor trace metals with passive sampling, developed at a low cost and operational facility.