115 resultados para 7137-137


Relevância:

10.00% 10.00%

Publicador:

Resumo:

The characterization of a coffee gene encoding a protein similar to miraculin-like proteins, which are members of the plant Kunitz serine trypsin inhibitor (STI) family of proteinase inhibitors (PIs), is described. PIs are important proteins in plant defence against insects and in the regulation of proteolysis during plant development. This gene has high identity with the Richadella dulcifica taste-modifying protein miraculin and with the tomato protein LeMir; and was named as CoMir (Coffea miraculin). Structural protein modelling indicated that CoMir had structural similarities with the Kunitz STI proteins, but suggested specific folding structures. CoMir was up-regulated after coffee leaf miner (Leucoptera coffella) oviposition in resistant plants of a progeny derived from crosses between C. racemosa (resistant) and C. arabica (susceptible). Interestingly, this gene was down-regulated during coffee leaf miner herbivory in susceptible plants. CoMir expression was up-regulated after abscisic acid application and wounding stress and was prominent during the early stages of flower and fruit development. In situ hybridization revealed that CoMir transcripts accumulated in the anther tissues that display programmed cell death (tapetum, endothecium and stomium) and in the metaxylem vessels of the petals, stigma and leaves. In addition, the recombinant protein CoMir shows inhibitory activity against trypsin. According to the present results CoMir may act in proteolytic regulation during coffee development and in the defence against L. coffeella. The similarity of CoMir with other Kunitz STI proteins and the role of CoMir in plant development and plant stress are discussed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The most-used refrigeration system is the vapor-compression system. In this cycle, the compressor is the most complex and expensive component, especially the reciprocating semihermetic type, which is often used in food product conservation. This component is very sensitive to variations in its operating conditions. If these conditions reach unacceptable levels, failures are practically inevitable. Therefore, maintenance actions should be taken in order to maintain good performance of such compressors and to avoid undesirable stops of the system. To achieve such a goal, one has to evaluate the reliability of the system and/or the components. In this case, reliability means the probability that some equipment cannot perform their requested functions for an established time period, under defined operating conditions. One of the tools used to improve component reliability is the failure mode and effect analysis (FMEA). This paper proposes that the methodology of FMEA be used as a tool to evaluate the main failures found in semihermetic reciprocating compressors used in refrigeration systems. Based on the results, some suggestions for maintenance are addressed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Dynamic vehicle behavior is used to identify safe traffic speed limits. The proposed methodology is based on the vehicle vertical wheel contact force response excited by measured pavement irregularities on the frequency domain. A quarter-car model is used to identify vehicle dynamic behavior. The vertical elevation of an unpaved road surface has been measured. The roughness spectral density is quantified as ISO Level C. Calculations for the vehicle inertance function were derived by using the vertical contact force transfer function weighed by the pavement spectral density roughness function in the frequency domain. The statistical contact load variation is obtained from the vehicle inertance density function integration. The vehicle safety behavior concept is based on its handling ability properties. The ability to generate tangential forces on the wheel/road contact interface is the key to vehicle handling. This ability is related to tire/pavement contact forces. A contribution to establish a traffic safety speed limit is obtained from the likelihood of the loss of driveability. The results show that at speeds faster than 25 km/h the likelihood of tire contact loss is possible when traveling on the measured road type. DOI: 10.1061/(ASCE)TE.19435436.0000216. (C) 2011 American Society of Civil Engineers.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We examine the representation of judgements of stochastic independence in probabilistic logics. We focus on a relational logic where (i) judgements of stochastic independence are encoded by directed acyclic graphs, and (ii) probabilistic assessments are flexible in the sense that they are not required to specify a single probability measure. We discuss issues of knowledge representation and inference that arise from our particular combination of graphs, stochastic independence, logical formulas and probabilistic assessments. (C) 2007 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Adsorbent materials and composites are quite useful for sensor development. Therefore, the aim of this work is the surface modification of particulates and/or composite formation. The material was produced by plasma polymerization of HMDS (hexamethyldisilazane) in a single step. SEM analysis shows good surface coverage of particulates with a plasma polymerized film formed by several clusters that might increase adsorption. Particles (starch. 5 5 mu m) recovered with HMDS films show good properties for retention of medium-size Organic molecules, such as dye. Thin films formed by a mixture of particles and plasma polymerized thin film HMDS species were obtained in a single step and can be used for retention of organic compounds, in liquid or gaseous phase. (C) 2009 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Austenitic stainless steels cannot be conventionally nitrided at temperatures near 550 degrees C due to the intense precipitation of chromium nitrides in the diffusion zone. The precipitation of chro-mium nitrides increases the hardness but severely impairs corrosion resistance. Plasma nitriding allows introducing nitrogen in the steel at temperatures below 450 degrees C, forming pre-dominantly expanded austenite (gamma(N)), with a crystalline structure best represented by a special triclin-ic lattice, with a very high nitrogen atomic concentration promoting high compressive residual stresses at the surface, increasing substrate hardness from 4 GPa up to 14 GPa on the nitrided case.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The aim of this work is the production and preliminary characterization of adsorbent new materials useful for sensor development. A new plasma chamber was simulated and designed in order to obtain multiple layers and/or composites in a single step. Plasma deposited organic fluorocompound and hexamethyldisilazane (HMDS) thin films were produced and tested as adsorbent layers. Chemical characterization used ellipsometry, Raman. infrared and X-ray photoelectron spectroscopy. Hydrophobic and oleophobic character were determined by contact angle measurements. Adsorption characteristics were evaluated using quartz crystal microbalance. Not only HMDS but also the fluorocompound can polymerize but intermixing and a double layer are only obtained in very narrow conditions. The films are adsorbent and mildly hydrophobic. Films deposited on a microchromatographic column can be used on sample pretreatment to remove and/or preconcentrate volatile organic Compounds. Therefore, with this approach it is possible to obtain films with different monomers on double layer or composites, with organic/inorganic materials or particles and use them on sample pretreatment for chemical analysis. (C) 2008 Elsevier B.V. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We studied the structure of a population of Hydromedusa maximiliani associated with a stream in Parque Estadual da Serra do Mar, Nucleo Itutinga-Piloes, southeastern Brazil, between October 2004 and October 2005. Twenty-five individuals were captured, and a population size of 43.72 +/- 23.7 individuals was estimated. This value is similar to that of the population of Parque Estadual Carlos Botelho, another Atlantic forest reserve of southeastern Brazil. Males were recaptured more frequently than females, suggesting higher activity and/or greater movement of males.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

MARTINS, A. R. (Institute of Biology, State University of Campinas - UNICAMP, 13083-970, Campinas, SP, Brazil), N. PUT, (Division of Biology and Education, University of Vechta, 49377 Vechta, Germany), A. N. SOARES, A.B BOMB, and B. APPEZZATO DA GLORIA (Biological Science Department, Escola Superior de Agricultura `Luiz de Queiroz`, University of Sao Paulo, 13418-900, Piracicaba, SP, Brazil). J. Torrey Bot. Soc. 137: 220-235. 2010.-New approaches to underground systems in Brazilian Smilax species (Smilacaceae). Scientific studies show that the watery extract of the thickened underground stem and its adventitious roots of the genus Smilax can act as a therapeutic agent in immunoinflammatory disorders, such as rheumatic arthritis. Brazilians have used this genus of plants in folk medicine, however it is very hard to identify these species, since the morphology of the underground systems is very similar in this group. For better identification of those systems, we studied six species of Smilax L. (S. brasiliensis, S. campestris, S. cissoides, S. goyazana, S. oblongifolia and S. rufescens), collected in different regions of Brazil with different physiognomies and soil characteristics. The main purpose is to describe the morpho-anatomy of the underground systems and to analyze if their structure depends on environmental conditions. The underground stem (rhizophore) is of brown color and it is knotty, massive, slender (S. rufescens) or tuberous (S. brasiliensis, S. campestris, S. cissoides, S. goyazana and S. oblongifolia). The tuberization is a result of primary thickened meristem (PTM) activity. The color and thickness of the adventitious roots change during development because the epidermis and outer cortex are disposed of, so the inner cortex becomes the new covering tissue with lignified and dark color cells. There are differences in starch grain shapes in mature roots. The chemical attributes of the soil are very similar in all studied environments and, even when soil characteristics varied, all the species` underground system was distributed close to the soil surface (10 to 15 cm deep). The species exhibited clonal growth hence their underground system functions as storage structures and the axillary buds can sprout into new stems. Only Smilax rufescens, collected in sandy soil of Restinga, has vegetative dispersal due to the runners.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tetranychus evansi is an important pest of tomato in several countries. The predatory mite Phytoseiulus longipes has been found in association with it in Uruguaiana, State of Rio Grande do Sul, Brazil. The objective of this study was to evaluate the distribution of those two species in Uruguaiana region. Bi-weekly samples of plant parts were taken between January 28 and April 30, 2007 in Uruguaiana and five neighboring counties. Tetranychus evansi was found in all counties, but P. longipes was only found in Uruguaiana, mainly in the urban area. It is conceivable that such restricted distribution of P. longipes is due to its recent introduction to the region. Alternatively, unfavorable winter conditions could prevent its persistence, except in protected places. Buildings and vegetation characteristics of the urban area of Uruguaiana could moderate strong winds, intense rainfall and low temperatures that commonly occur in the area.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Rubber tree clones present different intensity of symptoms, depending on their age. This is mostly clearly seen in the presence or absence of old leaves with ascopores, corresponding to flows of new and susceptible leaves. The objective of this work was to evaluate the intensity of symptoms of south American leaf blight (SALB) in six rubber tree clones, one and eight years old, in the Vale do Ribeira region, Sao Paulo state. The results Showed that clones FX 3864, RRIM 600, IAN 873 and IAN 717 Suffered more attacks when young, and RRIM 600, IAN 717 and FX 3864 when adult. The clone IAN 873 showed the smallest amounts of disease in the adult phase, due to uniform change in the leaves and a compact flow of new leaves, which happened during a season that was unfavorable to pathogen infection, presenting the phenomenon of avoidance or evasion in time.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Highly weathered soils represent about 3 billion ha of the tropical region. Oxisols represent about 60% of the Brazilian territory (more than 5 million km 2), in areas of great agricultural importance. Soil organic carbon (SOC) can be responsible for more than 80% of the cation exchange capacity (CEC) of highly weathered soils, such as Oxisols and Ultisols. The objective of this study was to estimate the contribution of the SOC to the CEC of Brazilian soils from different orders. Surface samples (0.0 to 0.2 m) of 30 uncultivated soils (13 Oxisols, 6 Ultisols, 5 Alfisols, 3 Entisols, I Histosol, 1 Inceptisol. and I Molisol), under native forests and from reforestation sites from Sao Paulo State, Brazil, were collected in order to obtain a large variation of (electro)chemical, physical, and mineralogical soil attributes. Total content of SOC was quantified by titulometric and colorimetric methods. Effective cation exchange capacity (ECEC) was obtained by two methods: the indirect method-summation-estimated the ECECi from the sum of basic cations (Ca+ Mg+ K+ Na) and exchangeable Al; and the direct ECECd obtained by the compulsive exchange method, using unbuffered BaCl2 solution. The contribution of SOC to the soil CEC was estimated by the Bennema statistical method. The amount of SOC var ied from 6.6 g kg(-1) to 213.4 g kg(-1). while clay contents varied from 40 g kg(-1) to 716 g kg(-1). Soil organic carbon contents were strongly associated to the clay contents, suggesting that clay content was the primary variable in controling the variability of SOC contents in the samples. Cation exchange capacity varied from 7.0 mmol(c) kg(-1) to 137.8 mmol(c) kg(-1) and had a positive Correlation with SOC. The mean contribution (per grain) of the SOC (1.64 mmol(c)) for the soil CEC was more than 44 times higher than the contribution of the clay fraction (0.04 mmol(c),). A regression model that considered the SOC content as the only significant variable explained 60% of the variation in the soil total CEC. The importance of SOC was related to soil pedogenetic process, since its contribution to the soil CEC was more evident in Oxisols with predominance of Fe and Al (oxihydr)oxides in the mineral fraction or in Ultisols, that presented illuviated clay. The influence of SOC in the sign and in the magnitude of the net charge of soils reinforce the importance of agricultural management systems that preserve high levels of SOC, in order to improve their sustainability.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A study was conducted in Brazil to identify factors affecting grazing distribution of yearling Nelore cross heifers and to evaluate the efficacy of placement of a salt-mineral mix away from water to improve uniformity of grazing. Two pastures (25 ha and 42 ha) were evaluated for four 15-d sessions. Mineral mix was placed 590 m to 780 m from water during two sessions and at water for two sessions. Stubble heights were measured at the beginning and end of each session in 1-ha subunits of each pasture. Cattle locations were recorded oil clay 13 and 14 of each session by horseback observers. Heifers avoided areas with a preponderance of forbs and taller grass (P < 0.001). For the first 15 days of the study cattle avoided subunits farther from water. Thereafter, horizontal distance from water had no affect on grazing use (P > 0.10). Stubble height reduction was more uniform (P < 0.05) when the mineral mix was Lit water compared to away from water. In contrast, heifers spent less time farther from water when Mineral mix was placed at water (P = 0.02) based Oil Visual observations. Strategic placement of a salt-mineral mix away from water does not appear to be a reliable tool to improve cattle grazing distribution in humid tropical pastures from 25 ha to 45 ha in size.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Vibrio parahaemolyticus is a potentially pathogenic bacterium that occurs naturally in estuarine environments worldwide, and is often associated with gastroenteritis in humans following consumption of raw bivalve mollusks, especially raw oysters. The occurrence of total and pathogenic V. parahaemolyticus in 74 samples of raw oysters collected in restaurants, supermarkets, groceries and beach huts in Sao Paulo State, was monitored between February 2006 and January 2007. Enumeration of V. parahaemolyticus was performed according to the most probable number (MPN) procedure. Five to ten typical colonies were selected from thiosulfate-citrate-bile salts-sucrose (TCBS) agar plates for confirmation by the presence of the species-specific gene tlh and the virulence genes tdh and trh by multiplex PCR. V. parahaemolyticus was detected in 100% of samples. The densities of total V. parahaemolyticus varied from 1.78 to 6.04 logio (MPN/g), with higher densities being detected in fall and summer, and lower densities in winter (P < 0.05). There was no statistical difference among densities of V parahaemolyticus regarding the site of collection. None of the 1943 V parahaemolyticus isolates contained tdh and/or trh. These data provide information for the assessment of exposure to V. parahaemolyticus in oysters consumed in Sao Paulo, State, Brazil. (C) 2010 Elsevier Ltd. All rights reserved.