Influencia da Carga no Comportamento quanto ao Desgaste de um Aco ABNT-1020 Bifasico Revenido a 450°C

The wear rate of the dual-phase steel ABNT-1020 tempered at 450°C sliding against cemented steel ABNT-1020 in function of load value is investigated in wide load range. The alteration in behavior of this function at intermediate load level, like in the case of low hardness steel sliding against high hardness steel, is observed. The analysis by scanning electronic microscope before and after this alteration showed a change of wear mechanism from plastic displacement to embrittlement.

Análise do comportamento de rebolos convencionais na retificação de aços frágeis e dúcteis

The aim of this work war to study the behavior of the plan tangential grinding process with conventional grinding wheels, under several machining conditions and a selected dressing condition. The analysis of the grinding performance was done regarding the cutting surface wear behavior of the grinding wheel for brittle and ductile steels workpieces. The grinding input parameters, which were, cutting speed, workpiece speed and cutting feed, were chosen based on the grinding machine characteristics. The results discussion emphasized the wear mechanism of the grinding wheel cutting surface and the cutting phenomenology of the grinding process.

Comportamento fractal de tracos de fraturas na borda sul do macico granitico de itu, estado de Sao Paulo

Fractal geometry is relevant to understand and explain many natural complex geometries. Using the fractal set concept (fig. 1) many authors have shown that shorelines, landscapes and fractures follow a fractal behaviour. These authors have developed many methods, including the Cantor's Dust Method (CDM) (VELDE et al., 1992), a linear method of analysis adapted for the determination of two-dimensional phenomena. The Itu Granitic Complex (IGC) is a wide granitic body that that crops out at northwest of Cabreuva City, Sao Paulo State (fig. 2) and was affected in its south border by dextral Itu-Jundiuvira Shear Zone (IJSZ) that produced fractures and alignment of feldspars crystals. The different types of fractures (compression, distension and shear) was discriminated from the relationship between them and medium stress ellipsoid of IJSZ (fig. 3). A modified version of CDM was used to study a possible fractal behaviour of the fracture traces in the south border of IGC. The main modification was the use only one direction of analysis (NE/SW). Four parallel profiles were traced with lengths between 9.75km and 12.75km, each one them was divided into six classes of segments (x) with 375m, 500m, 750m, 1.000m, 1.250m and 1.500m. The parameter (N) is provided by he rate between profile length and choiced segment. For each x the number of intervals is counted with at least one event (fracture intersection) which supplied the parameter(n). The n/N rate provide the parameter (p) that represents the relationship between frequency of events and x. And finally the parameters p and x were plotted in a logarithmic graphics (fig. 4) that provide a line with such a declivity (1) which is related to effective dimension (De). In theory, granitics bodies are isotropics and they would have a same fractal dimension in all segments, but the logarithmic graphics (fig. 4) show that fracture traces of IGC has a fractal behaviour in a restrict interval. This fact probably occurs from the passage of a ductil-brittle deformation condition to a more brittle deformation condition of IGC.

Partilha de Recursos Alimentares em Peixes em um Riacho de Serra do Sudeste do Brasil

We studied the diet and food resources partitioning by fishes from the Itaúna stream, municipality of Itatinga, Southeastern Brazil. Eighteen species of fish were collected, being Microlepidogaster sp., Hypostomus sp., Astyanax sp., Phalloceros caudimaculatus and Heptapterus sp. the most frequent and abundant ones. Regarding diet, the majority of the species were observed to be insectivorous (61%), while insectivorous-herbivorous and periphyton feeders ranked 22 and 17%, respectively. The food overlap analysis revealed many cases of similarity between the diets. For most cases, however, a detailed analysis of food items and spatial distribution of the species showed differences between the couples under analysis which points toward a reduction in competition for food.

Comportamento de cultivares de soja quanto a qualidade fisiológica de sementes

This work was carried out in order to evaluate if there was a relationship between genotypes and the physiological soybean (Glycine max L.) seed quality. It was conducted during three years using seven cultivars each year. The seeds were harvested at: 1) yellow radicle or expanded pod stage, 2) yellow pod or physiological maturity (R7), 3) harvest maturity (R8), and 4) R8 + 21 days delay. Seed moisture content, standard germination, and vigor tests were performed. The germination and vigor evaluated by accelerated aging and electrical conductivity did not show physiological seed quality differences among genotypes as harvested at physiological maturity. Then, the evaluation of seed germination and vigor, when the environment is not a considered factor, is not an efficient method to show differences among soybean genotypes in terms of seed quality.

Acao antioxidante de extratos de alecrim (Rosmarinus officinalis L.) em files de peixes da especie pacu (Piaractus mesopotamicus Holmberg)

The antioxidant effect of plant extract has been an interesting issue for many researchers in past few years. Spices have been identified as products with large amounts of antioxidants, and rosemary is one the most studied spice. Studies have shown evidences that population with high intake of these substances have less incidence of coronary heart disease. The objective of this work was verify the antioxidant action of the commercial rosemary oleoresin Herbalox® (used to feed the pacu (Piaractus mesopotamicus) fish. The juveniles pacu were fed with isocaloric and isoproteic diets, for two groups the lipid source was soybean oil and for the another it was corn oil. For each group of the different lipid sources, rosemary extract Herbalox® (were added in one lot and on the other which was used as control. The results showed that the addition of rosemary extracts to the ration protected them against peroxidation, when compared with the control, the lipid source also have influence on these protection.

Borohidreto complexos de cobre (I) contendo difosfinas. Caracterização espectroscópica e comportamento térmico

Tetrahydroborate complexes of copper (I) with bidentate phosphines, [Cu(η 2-BH 4)(dppm)] (1), [Cu(η 2-BH 4)(dppe)] (2), [Cu(η 2-BH 4)(cis-dppet)] (3) and [Cu(η 2-BH 4)(dppb)] (4) (dppm = bis(diphenylphosphino)methane; dppe = 1,2-bis(diphenylphosphino) ethane; cis-dppet = 1,2-cis(diphenylphosphino)ethene; dppb = 1,4-bis(diphenylphosphino)butane) were prepared and characterized by elemental analysis, infrared spectroscopy, NMR and thermogravimetric analysis. The IR data for 1-4 showed bands typical of a bidentate coordination of BH 4 group to the copper atom and the 31P{ 1H} NMR spectra indicated that the phosphorous atoms are chelating the metal centre. The thermal behavior of the compounds was investigated and suggested that their thermal stability is influenced by the phosphines. Their thermal stability decreased as follows: [Cu(η 2-BH 4)(dppe)] (2) > [Cu(η 2-BH 4)(dppm)] (1) > [Cu(η 2-BH 4)(dppb)] (4) > [Cu(η 2-BH 4)(cis-dppet)] (3). According to thermal analysis and X-ray diffraction patterns all compounds decomposed giving Cu(BO 2) 2, CuO, CuO 2 and Cu as final products.

Prevalência, sazonalidade e intensidade de infecção por Diplostomum (Austrodiplostomum) compactum Lutz, 1928 (Digenea, Diplostomidae), em peixes do reservatório de Volta Grande, Estado de Minas Gerais, Brasil

The present study was conducted in the Aquaculture Station of Hydroeletric Power Station situated in Volta Grande Reservoir, MG, Brazil. Seventy freshwater corvinas, Plagiscion squamosissimus, and 66 tucunarés, Cichla ocellaris were captured bimonthly from April 2000 through April 2001 with net and hook. The helmints were identified as Diplostomun (A.) compactmn which showed the highest prevalence in the corvina's eyes in April 2000 (70%), February 2001 (80%) and April 2001 (60%), while in tucunaré occurred in April 2000 (33.3%), August 2000 (18.2%) and October 2000 (18.2%). Nevertheless, increase in the mean intensity of parasites was related in April (6.6), June (6.0), August (18.5) 2000 and February (5.7), April (4.8) 2001 for corvina and in August (16.0) and October (7.0) 2000 for tucunaré. Corvina's females showed infection during all period, while males did not show the same prevalence in June 2000 and April 2001. On the other hand, tucunare's males were infected in all months while females in August and October 2000. The highest prevalence in corvina was observed in the months which presented elevated water temperature (April, October, December 2000 and April 2001). The number of parasites collected in corvina on February 2000 was higher than the one observed in August 2000. The same was not observed for tucunaré. This work demonstrate corvina's high susceptibility to metacercariae of Diplostomum.

Metacercárias de Diplostomum (Austrodiplostomum) compactum Lutz, 1928 (Digenea, Diplostomidae) em peixes do rio Paraná, Brasil. Prevalência, sazonalidade e intensidade de infecção

This paper aims at evaluating the occurrence of Diplostommn (Anstrodiplostomum compactum (Digenea: Diplostomatidae) in the eyeball of Plagioscion sqnamosissimus (corvina) and Cichla ocellaris (tucunaré), monthly captured in Paraná river, Presidente Epitácio, state of São Paulo, Brazil. From 61 corvinas under analysis, 56 of them contained parasites (92%) with intensity rate of 42.0 host parasites. From an amount of 81 tucunarés, 45 contained parasites (55%) with intensity rate of 9.3 parasites. Corvinas showed prevalence from 71 to 100% with the highest intensity rates (103.3 and 106.9) from February to March, 2001. Comparatively, the tucunaré showed the highest prevalence from November 2000 (90%) to February 2001 (80%). The tucunaré highest intensity rates occurred on September, 2000 (12.7), December, 2000 (12.2) and February, 2001 (16.1). Metacercariae showed a hollow womb body and a posterior region of a sinuous conic protuberance, an oral sucker smaller than the acetabulae, a simple acetabulae located in the pre-equatorial region of helminto. A short pre-pharynx followed by a muscular pharynx, genital pore next to acetubulae. Corvina metacercariae presents 1.434,0 μm (880 to 1.840) long by 611.2 ± 93.4 μm (400 to 792) wide. Tucunaré metacercariae, 1.462.4 μm (960 to 2.480) by 710.8 μm (560 to 960). Authors confirmed corvina great susceptibility to Diplomastum and the relationship between the parasitism and the aquatic and climatic parameters.

Associações de espécies de peixes em ambientes lóticos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul

The aim of this paper is to describe the patterns of associations between fish species and their distribution in lotic habitats at basin level. Samples were accomplished in 27 localities of Iguatemi river basin, distributed in four environments (Iguatemi river, Jogui river, Puitã river and streams). The presence/absence data of those species which occurred in 2 or more sites were submitted at multivariate methods with the aim to describe the major species associations. The species distribution was considered determinative in these communities (C-score = 17,33; P = 0,000), with significant difference among the studied environments (ANOSIM r = 0,082; P = 0,012), with verified difference between Iguatemi river and streams (P = 0,001) and also streams and Jogui river (P = 0,014). We verified a strong segregation among species from headstreams and more discharge river stretches or even larger streams.

Influência do alecrim (Rosmarinus officinallis L.) na atividade de água e oxidação lipídica de peixes de uma espécie de tilápia (Oreochromis ssp-var. vermelha Flórida) submetidos à salga

Salting have been a very utilized fish conservation method, however only in the last years the basic mechanism involved in salting fish has been understood. The objectives of this study were determine the addition in brine salt of rosemary leaves, rosemary extracts and tocopherol, and your action in the followed parameters: water activity (Aw), moisture, ash, salt content and TBARS. The results showed that the addition of antioxidants was difficulted the salt absorption, however didn't have differences between rosemary or tocopherol use. In the salting time of 3 hours the values of Aw and salt levels, was respectively: 0.77±0.01 and 14.42±1.69. for control treatment; 0.85±0.02 and 9.09±1.39for rosemary filtrate; 0.78±0.03 and 10.63±0.69 rosemary without filtrating and 0.85±0.02 and 11.96±1.78 tocopherol, showed that didn't grow indigenous bacterias. Lipid oxidation was evaluated by TBARS and the results showed the oxidative effect of salt and the pro oxidant effects of alls antioxidants used in brine salting.

Habitat, distribuição e aspectos adaptativos de peixes da microbacia do ribeirão Grande, Estado de São Paulo, Brasil

The ichthyofauna of ribeirão Grande microbasin that runs through one of the few remaining fragments of Atlantic Forest (in Mantiqueira mountain range, Valley of Paraíba) was studied. Fish samples were obtained with an electric fishing powered by a maximum capacity generator of 155 V and 60-Hz alterning current, gill-nets and traps. In three collecting days, during July/2001, October/2001, January/2002 and April/2002, 2865 fishes were sampled. These fishes belonged to 12 families, 23 genera and 37 species. The species were more abundant between the piedmont and the plain of the Valley of Paraíba. The Characidium, Trichomycterus genera and the Imparfinis minutus species presented only one ovary or testis and no swim bladder. The ecological significance of morphological features in stream mountain fishes was used to predict the niche adaptation for those conditions, towards K-strategy.

Comportamento do cafeeiro apoatã em consórcio com culturas anuais

This study was conducted in Adamantina, region of Alta Paulista, São Paulo State, Brazil, from 1989 to 1993. Yield of Apoatã coffee (Coffea canephora Pierre ex Froehner) was evaluated during four years of intercropping with five plant species: IAC 20 - cotton (Gossypium hirsutum L.); cv. Tatu - peanut (Arachis hypogaea L.); IAC 165 - rice (Oryza sativa L.); cv. Guarani - castor bean (Ricinus communis L.) and IAC 100-B - corn (Zea mays L.). The crops were seeded 50 cm apart from coffee canopy. The treatments were arranged in randomized complete block design with five replications. Yield was significantly decreased when coffee was intercropped with castor bean, corn, cotton and peanut, but height and diameter of orthotropic branches were not affected. Linear correlation analysis showed that coffee yield was inversely correlated with the dry biomass of the intercrops.

Organização das assembléias de peixes em riachos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul

Aiming to describe the patterns of the fish assemblages organization in streams of the Iguatemi River basin we sampled streams with seine nets and sieves from November/1999 to August/2000. We collected 567 individuals distributed in 24 species. We detected statistically significant influence of the streams characteristics upon species diversity. The species composition was hardly explained by the physical and chemical characteristics of the streams. Then we detected significant influence of the fish ecomorphology in the species occurrence (Mantel r = -0.34; P = 0.04), but not in the distribution of its abundance (Mantel r = -0.21; P = 0.07). We verified through the species co-occurrence index (C-score) that its composition in the studied streams is stochastic.