Determinação da circunferência de rolamento de pneus agrícolas utilizando dois métodos: manual e eletrônico

A circunferência de rolamento dinâmica dos pneus agrícolas é uma medida importante para o estudo do desempenho de tratores agrícolas. Neste trabalho, compararam-se dois métodos de determinação da circunferência de rolamento dinâmica - um manual e um eletrônico (com instrumentação das rodas de tração) - sob duas velocidades de deslocamento e cinco combinações de pressão de inflação nos pneus dianteiros e traseiros. O método manual forneceu valores estatisticamente superiores aos do eletrônico, com diferença absoluta máxima de 0,24%. A pressão de inflação influenciou significativamente os valores medidos, enquanto a velocidade de deslocamento, para os valores do ensaio (3,0 e 6,0 km.h-1), não apresentou influência significativa.

Electrocardiographic evaluation of two anesthetic combinations in dogs

Este trabalho teve o objetivo de avaliar as possíveis alterações eletrocardiográficas de cães submetidos a duas condutas anestésicas, indicando aquela que produz menores alterações no eletrocardiograma (ECG). Foram utilizados 40 cães com idade igual ou superior a cinco anos, 24 machos e 16 fêmeas, com peso entre 5 e 42kg, oriundos de clínicas particulares da cidade de São Paulo e do canil da Polícia Militar do Estado de São Paulo, sem sintomas cardiovasculares e triados para tartarectomia. Todos os cães foram submetidos a dois ECG: um antes da anestesia e outro imediatamente antes de se iniciar o procedimento cirúrgico. As características eletrocardiográficas avaliadas foram: ritmo, duração da onda P, do complexo QRS e dos intervalos PR e QT, amplitude das ondas P e R e alterações do segmento ST e da onda T; avaliou-se também o índice de tono vagal (ITV). Os cães foram divididos em: grupo 1, que recebeu atropina, levomepromazina, tiopental e halotano (ALTH) e grupo 2, que recebeu atropina, tiletamina e zolazepam (ATZ). Os resultados mostraram que a associação ALTH produziu algumas alterações discretas no ECG dos cães avaliados, caracterizadas por modificações qualitativas no segmento ST, na onda T e no ritmo cardíaco, reduzindo significativamente o ITV, com tendência à bradicardia e hipóxia. Já a associação ATZ, além das alterações já citadas, produziu diminuição da duração dos intervalos PR e QT, bem como aumentou a freqüência cardíaca, com tendência à taquicardia e hipóxia.

On linear combinations of L-orthogonal polynomials associated with distributions belonging to symmetric classes

This paper deals with the classes S-3(omega, beta, b) of strong distribution functions defined on the interval [beta(2)/b, b], 0 < beta < b <= infinity, where 2 omega epsilon Z. The classification is such that the distribution function psi epsilon S-3(omega, beta, b) has a (reciprocal) symmetry, depending on omega, about the point beta. We consider properties of the L-orthogonal polynomials associated with psi epsilon S-3(omega, beta, b). Through linear combination of these polynomials we relate them to the L-orthogonal polynomials associated with some omega epsilon S-3(1/2, beta, b). (c) 2004 Elsevier B.V. All rights reserved.

Evaluation of cardiorespiratory effects of combinations of dexmedetomidine and atropine in cats

The cardiovascular effects of dexmedetomidine alone or in combination with atropine were studied in six cats. Cats underwent four treatments in a randomized crossover design as follows: DEX15, saline + dexmedetomidine 15 mu g/kg; DEX30, saline + dexmedetomidine 30 mu g/kg; ADEX15, atropine + dexmedetomidine 15 mu g/kg; ADEX30, atropine + dexmedetomidine 30 mu g/kg. Pulse rate (PR) and systolic arterial pressure (SAP) decreased in DEX15 and DEX30. Premedication with atropine was effective in preventing bradycardia (PR < 100 beats/min) and resulted in a biphasic effect in blood pressure. Hypertension was followed by a gradual decrease in SAP. Rate pressure product decreased in DEX15 and DEX30 whereas in ADEX15 and ADEX30 it remained within baseline values for at least 60 min. Although premedication with atropine in cats sedated with dexmedetomidine prevents bradycardia, it induces hypertension and increases myocardial oxygen consumption. The magnitude of cardiovascular effects produced by dexmedetomidine in cats does not seem to be dose-related. (C) 2009 ESFM and AAFP. Published by Elsevier Ltd. All rights reserved.

Variaciones del índice de cono en suelo movilizado posterior al tráfico de un tractor equipado con dos tipos de neumáticos y a cuatro velocidades de desplazamiento

The tractor is one of the machines that more traffics over the soil during the processes involving agricultural production. The interaction tractor/soil is made by the tires which, in most of the cases, are pneumatic. The tire type and the tractor travel speed, interfere directly on the pressure over the soil. One of the techniques employed to evaluate the alterations that tractor traffic causes in the soil is to measure its Cone Index. The aim of this research was to evaluate the same Cone Index alterations caused by an agricultural tractor equipped with both radial tires and bias ply tires, trafficking mobilized soil in four different travel speeds. The experiment was performed in a LATOSSOLO VERMELHO, located 22°51' S, 48°25'W and 770 m of altitude, in Botucatu-SP, Brazil. The soil mobilization was performed with a chisel plow and a disc arrow. The traction was accomplished with a John Deere tractor, model 6600, with 88 kW of power and 6,723 kg. Equipment requiring a force of 25kN was traced by the tractor draw bar. The experimental design was in randomized blocks with 4 × 2 factorial arrangements, with two distinct treatments corresponding to the types of tires (bias and radial) and the four travel speeds, with six replications. There were selected the following speeds: 3.5, 3.9, 5.1 and 5.9 km h-1. To determine the soil resistance, there was utilized MSSU - Mobile Soil Sampling Unit, with which the Cone Index was obtained in layers from 0-100, 100-200, 200-300, 300-400, 400-500 and over 500 mm deep. The Cone Index where evaluated in areas with non contact between tire and soil (ICn) and in the tire footprint track (ICp). There were calculated the Cone Index increments caused by the tractor tire (AIC) and the results showed that as the tractor travel speed increased, there were observed decrements in the medium values of cone index. The radial tire provided smaller values of the Cone Index in the superficial layer of the soil (0 to 100 mm) in relation to the bias ply tire, when the speed was approximately 6 km h-1. The increment in the Cone Index, promoted by the tractor, was more intense in the first 200 mm depth, but it also reached the layer from 200 to 300 mm.

Análise da influência dos movimentos verticais e horizontais das barras de um pulverizador na aplicação da calda

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Energetic efficiency of an agricultural tractor in function of tire inflation pressure

The tire inflation pressure, among other factors, determines the efficiency in which a tractor can exert traction. It was studied the effect of using two tire inflation pressures, 110.4 kPa in the front and rear wheels, 124.2 kPa in the front wheel and 138 kPa in the rear wheels, the energetic efficiency of an agricultural tractor of 147 kW of engine power, in the displacement speed of 6.0 km.h-1, on track with firm surface, with the tractor engine speed of 2000 rpm. For each condition of the tire pressure, the tested tractor was subjected to constant forces in the drawbar of 45 kN and 50 kN, covering 30 meters. It was used a randomized complete block with a 2x2 factorial arrangement (tire pressure and drawbar power) with four replications, totaling 16 experimental units. Data were subjected to analysis of variance, using the Tukey test at 5% probability for comparison averages. The lowest hourly and specific fuel consumption, the lowest slippage of the wheelsets and the highest efficiency in the drawbar was obtained with the tire inflation pressure of 110.4 kPa in the front and rear tires of the tractor, highlighting that lower pressures improve energetic and operational performance of the tractor.

Adhesion of substrate-adherent combinations for early composite repairs: Effect of intermediate adhesive resin application

This study evaluated the effect of intermediate adhesive resin application (IAR) on tensile bond strength (TBS) for early composite repairs in situations where substrate and repair composite bonded together were once of the same kind with the substrate (similar) and once other than the substrate material (dissimilar). Specimens from three types of composites (TPH Spectrum (TPH), Charisma (CHA) and Filtek Z250 (Z250)) were fabricated. The specimens in each composite group (n=72) were randomly divided into six subgroups (n=12). In each composite group, the similar and two dissimilar composites were bonded onto the substrates once using an IAR (Adper Single Bond Plus) and once without. After water storage for I week at 37 degrees C, substrate-adherent combinations were submitted to tensile test. Data were analyzed with three-way ANOVA and Tukey's tests (alpha=0.05). The substrate-adherent combination (p=0.0001), adherent (repair) composite (p=0.0001), and application of IAR (p=0.0001) significantly affected the results. Utilization of IAR improved the repair bond strength for all composite combinations. (C) 2013 Elsevier Ltd. All rights reserved.

Vibração incidente sobre o corpo inteiro do operador de trator agrícola ensaiado em pista de vibração com diferentes lastros, velocidades e pressões de inflação dos pneus

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Tractor perfomance as a function of speed and seeder s tire inflation pressure

O desempenho de tratores agrícolas em condições de campo resulta da interação entre pneu e rodado, influenciado pela velocidade de deslocamento. O objetivo deste trabalho foi avaliar o desempenho de um trator agrícola sob diferentes pressões de inflação dos pneus da semeadora (518, 483, and 414kPa) e em duas marchas que proporcionaram velocidades de 3,0 e 6,0km h-1. O experimento foi realizado no campus de Jaboticabal da Universidade Estadual Paulista (UNESP). O delineamento experimental utilizado foi fatorial inteiramente casualizado (3x2), com quatro repetições. A força de tração foi influenciada pela marcha e pela potência exigida; no entanto, a pressão de inflação do pneu da semeadora não alterou esses parâmetros. Além disso, o consumo de combustível foi influenciado apenas pela marcha do trator. O consumo de energia foi maior com o aumento da velocidade, ocasionada pela mudança de marcha. A velocidade de deslocamento foi maior para a pressão de 518kPa, em razão da menor patinagem da semeadora promovida por essa pressão. A patinagem do trator não foi alterada pelos fatores testados.

Maize and soybeans production in integrated system under no-tillage with different pasture combinations and animal categories

The adoption of no-till system (NTS) combined with crop-livestock integration (CLI) has been a strategy promoted in Brazil, aiming to maximize areas yield and increase agribusiness profitability. This study aimed to evaluate grains yield and phytotechnical attributes from maize and soybean culture by CLI system under NTS after winter annual pure and diversified pastures with the absence or presence of grazing animals. The experiment was installed in Castro (Parana State, Brazil) on in a dystrophic Humic Rhodic Hapludox with a clay texture, using experimental design of randomized complete blocks in 4 x 2 factorial scheme with three replications. Treatments included four pasture combinations (diversified or pure) and animal categories (light and heavy) subjected or not to grazing animals during the winter. During 2008/09 and 2009/10 summers, the area was cultivated with soybeans and maize, respectively, with yield assessment of grains and phytotechnical attributes. Treatments did not alter the yield and weight of a thousand seeds (WTS) of soybeans. In maize culture, the grazing animal during the winter increased the plant population and grains yield, but gave slight decrease in WTS. Pasture combinations (diversified or pure) and animal categories (light and heavy) did not interfere in soybean culture, but benefited the maize crop.

Effect of natural antioxidant combinations on lipid oxidation in cooked chicken meat during refrigerated storage

The effect of combinations of sage, oregano and honey on lipid oxidation in cooked chicken meat during refrigeration at 4 degrees C for 96 h was determined. Chicken samples (thigh and breast) were then separated into five groups; control; butylated hydroxytoluene; oregano + sage; oregano + sage + 5%honey and oregano + sage + 10%honey. Quantitative measurements of thiobarbituric acid reactive substances, conjugated dienes, hexanal, fatty acids, cholesterol and cholesterol oxides were used as indicators of lipid oxidation. Acceptability and preference were also evaluated. The effectiveness of the natural antioxidants for reducing the velocity of lipid oxidation in cooked chicken thigh and breast was demonstrated after 48 and 96 h of refrigeration at 4 degrees C. The treatments that presented the lowest hexanal values after 96 h of refrigeration were oregano + sage + 5%honey and oregano + sage + 10%honey. Only traces of free cholesterol oxides were found (25-OH, 7-k, 7 alpha-OH and 7 beta-OH). The natural antioxidants protected cooked chicken meat from oxidation processes and resulted in great acceptability. (C) 2012 Elsevier Ltd. All rights reserved.

Benefits of Combinations of Vitamin A, C and E Derivatives in the Stability of Cosmetic Formulations

Chemically stable ester derivatives of vitamins A, C and E have become a focus of interest for their role in the satisfactory results in skin aging treatments. Accordingly, the aim of this study was to evaluate the physical and chemical stability of a cosmetic formulation containing 1% retinyl palmitate, ascorbyl tetraisopalmitate and tocopheryl acetate, alone or in combination. In the studies of physical stability, a Brookfield rheometer was used to determine rheological behavior of formulations containing the vitamins. Chemical stability was determined by HPLC on a Shimadzu system with UV detection. Results showed that formulations had pseudoplastic behavior and that vitamins did not alter their apparent viscosity and thixotropy. In the chemical stability studies, first-order reaction equations were used for determinations of the shelf-life of vitamins derivatives considering a remaining concentration of 85%. Combined vitamins in a single formulation had a slightly lower degradation rate as compared to different preparations containing only one of the vitamins. Considering that many cosmetic formulations contain vitamin combinations it is suggested that the present study may contribute to the development of more stable formulations containing liposoluble vitamins.

Compsodactylus, a new South American genus with one new species and two new combinations (Coleoptera: Scarabaeidae: Melolonthinae)

Compsodactylus new genus and C. scabrosus new species are described and C. martinezi (Frey, 1972) new combination and C. parvulus (Frey, 1970) new combination are redescribed and transferred from Dicrania LePeletier & Audinet-Serville, 1828. The new genus is placed in Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae) and occurs in the South American Andean and Preandean regions. A key to the species, modification on the recent generic key to Macrodactylini, and distributional map are presented.