79 resultados para Switching Process


Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study aimed at evaluating the effects of ethylene on peel color and compositional changes in ‘Lane late’ orange stored under refrigerated and ambient conditions. Physiologically mature, but green-peeled, oranges were exposed to ethylene gas under room temperature and high relative humidity for 24 hours. Storage chamber was ventilated with fresh air after 12 hours to mitigate consequences derived from fruit respiration. Both nondestructive analysis, such as peel color (hue angle, chromaticity, and brightness) and weight loss, and destructive ones (soluble solids, titratable acidity, pH, soluble solids to acidity ratio, and puncture force) were performed upon harvest, after degreening, and every three days during eighteen days in storage. Experiment was carried out using an entirely randomized design with thirty replications for nondestructive and four replications for destructive analyses, in a split plot scheme. Exposure to ethylene ensured a golden yellow peel for both fruit stored under ambient and refrigerated conditions. High relative humidity, associated with low temperature prevented fruit from losing moisture. Fruit exposure to ethylene did not affect weight loss, soluble solids, titratable acidity, pH, soluble solids, acidity ratio, or puncture force.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

ABSTRACT This study aims at presenting the process of machine design and agricultural implements by means of a reference model, formulated with the purpose of explaining the development activities of new products, serving as a guideline to coach human resources and to assist in formalizing the process in small and medium-sized businesses (SMB), i.e. up to 500 employees. The methodology used included the process modeling, carried out from case studies in the SMB, and the study of reference models in literature. The modeling formalism used was based on the IDEF0 standard, which identifies the dimensions required for the model detailing: input information; activities; tasks; knowledge domains; mechanisms; controls and information produced. These dimensions were organized in spreadsheets and graphs. As a result, a reference model with 27 activities and 71 tasks was obtained, distributed over four phases of the design process. The evaluation of the model was carried out by the companies participating in the case studies and by experts, who concluded that the model explains the actions needed to develop new products in SMB.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

ABSTRACT Roasting is one of the most complex coffee processing steps due to simultaneous transfers of heat and mass. During this process, beans lose mass because of fast physical and chemical changes that will set color and flavor of the commercial coffee beverage. Therefore, we aimed at assessing the kinetics of mass loss in commercially roasted coffee beans according to heating throughout the processing. For that, we used samples of 350-g Arabica coffee processed grains with water content of 0.1217 kga kg-1, in addition to a continuous roaster with firing gas. The roaster had initial temperatures of 285, 325, 345 and 380 °C, decreasing during the process up to 255, 285, 305 and 335 °C respectively. Mass loss was calculated by the difference between grain weight before and after roasting. We observed a linear variation directly dependent on roaster temperature. For each temperature during the process was obtained a constant mass loss rate, which was reported by the Arrhenius model with r2 above 0.98. In a roaster in non-isothermal conditions, the required activation energy to start the mass loss in a commercial coffee roasting index was 52.27 kJ mol -1.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A surgical technique for the treatment of ununited anconeal process in dogs treated by osteotomy and dynamic distraction of the proximal part of the ulna using a linear external skeletal fixator was evaluated. In all cases the osteotomy was distracted 1mm each day after the surgery until desired distraction had been achieved. Eight dogs and 9 joints diagnosed with ununited anconeal process were treated. The success of the procedure was determined by comparing clinical signs of lameness and degree of arthrosis at the time of diagnosis to 6 months after the surgical intervention. Radiographic union occurred in 88.9% of the affected joints between 21 and 42 days after the surgical procedure. Clinically, six elbows were classified as good, two as satisfactory and one as unsatisfactory. Six months after surgery two elbows had no arthrosis, one had Grade 1, two Grade 2 and one Grade 3. It is concluded the combination of ulnar osteotomy and dynamic distraction of the olecranon by a linear external skeletal fixator is a feasible procedure for the treatment of ununited anconeal process in dogs.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this work was to propose, apply and evaluate a methodical approach to select welding processes in a productive environment based on market requirements of Quality and Costs. A case study was used. The welds were carried out in laboratory, simulating the joint conditions of a manufacturer and using several welding processes: SMAW, GTAW, pulsed GTAW, GMAW with CO2 and Ar based shielding gases and pulsed GMAW. For Quality analysis geometrical aspects of the beads were considered and for Cost analysis, welding parameters and consumable prices. Quantitative indices were proposed and evaluated. After that, evaluation of both Quality and Costs was done, showing to be possible to select the most suitable welding process to a specific application, taking into account the market conditions of a company.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The concept of Process Management has been used by managers and consultants that search for the improvement of both operational or managerial industrial processes. Its strength is in focusing on the external client and on the optimization of the internal process in order to fulfill their needs. By the time the needs of internal clients are being sought, a set of improvements takes place. The Taguchi method, because of its claim for knowledge share between design engineers and people engaged in the process, is a candidate for process management implementation. The objective of this paper is to propose that kind of application aiming for improvements related with reliability of results revealed by the robust design of Taguchi method.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Process planning is a very important industrial activity, since it determines how a part or a product is manufactured. Process planning decisions include machine selection, tool selection, and cutting conditions determination, and thus it is a complex activity. In the presence of unstable demand, flexibility has become a very important characteristic of today's successful industries, for which Flexible Manufacturing Systems (FMSs) have been proposed as a solution. However, we believe that FMS control software is not flexible enough to adapt to different manufacturing system conditions aiming at increasing the system's efficiency. One means to overcome this limitation is to include pre-planned alternatives in the process plan; then planning decisions are made by the control system in real time to select the most appropriate alternative according to the conditions of the shop floor. Some of the advantages of this approach reported in the literature are the reduction of the number of tool setups, and the selection of a replacement machine for executing an operation. To verify whether the presence of alternatives in process plans actually increases the efficiency of the manufacturing system, an investigation was carried out using simulation and design of experiments techniques for alternative plans on a single machine. The proposed methodology and the results are discussed within this paper.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The main goal of this work is to study the influence of cutting conditions - cutting speed, feed velocity and feed per tooth - on tool life and surface finish of the workpiece in the face milling of flat surfaces. Aiming to achieve this goal, several milling experiments were carried out with different cutting speeds, feed velocities and feeds per tooth. In the first phase of the experiments, cutting speed was varied without varying feed velocity, which caused a variation in feed per tooth. In the second phase of the experiments, cutting speed and feed velocity were varied in such a way that feed per tooth was kept constant. Tool flank wear and surface roughness of the workpiece were measured as cutting time elapsed. The main conclusions of this work are that a) cutting speed has a strong influence on tool life, regardless of whether feed velocity or feed per tooth varies and b) an increase in surface roughness of the workpiece is not closely related to an increase in wear of the primary cutting edge.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In the last two centuries, papers have been published including measurements of the germination process. High diversity of mathematical expressions has made comparisons between papers and some times the interpretation of results difficult. Thus, in this paper is included a review about measurements of the germination process, with an analysis of the several mathematical expressions included in the specific literature, recovering the history, sense, and limitations of some germination measurements. Among the measurements included in this paper are the germinability, germination time, coefficient of uniformity of germination (CUG), coefficient of variation of the germination time (CVt), germination rate (mean rate, weighted mean rate, coefficient of velocity, germination rate of George, Timson’s index, GV or Czabator’s index; Throneberry and Smith’s method and its adaptations, including Maguire’s rate; ERI or emergence rate index, germination index, and its modifications), uncertainty associated to the distribution of the relative frequency of germination (U), and synchronization index (Z). The limits of the germination measurements were included to make the interpretation and decisions during comparisons easier. Time, rate, homogeneity, and synchrony are aspects that can be measured, informing the dynamics of the germination process. These characteristics are important not only for physiologists and seed technologists, but also for ecologists because it is possible to predict the degree of successful of a species based on the capacity of their harvest seed to spread the germination through time, permitting the recruitment in the environment of some part of the seedlings formed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Lipoprotein Lp(a) is a major and independent genetic risk factor for atherosclerosis and cardiovascular disease. The essential difference between Lp(a) and low density lipoproteins (LDL) is apolipoprotein apo(a), a glycoprotein structurally similar to plasminogen, the precursor of plasmin, the fibrinolytic enzyme. This structural homology endows Lp(a) with the capacity to bind to fibrin and to membrane proteins of endothelial cells and monocytes, and thereby to inhibit plasminogen binding and plasmin generation. The inhibition of plasmin generation and the accumulation of Lp(a) on the surface of fibrin and cell membranes favor fibrin and cholesterol deposition at sites of vascular injury. Moreover, insufficient activation of TGF-ß due to low plasmin activity may result in migration and proliferation of smooth muscle cells into the vascular intima. These mechanisms may constitute the basis of the athero-thrombogenic mode of action of Lp(a). It is currently accepted that this effect of Lp(a) is linked to its concentration in plasma. An inverse relationship between Lp(a) concentration and apo(a) isoform size, which is under genetic control, has been documented. Recently, it has been shown that inhibition of plasminogen binding to fibrin by apo(a) is also inversely associated with isoform size. Specific point mutations may also affect the lysine-binding function of apo(a). These results support the existence of functional heterogeneity in apolipoprotein(a) isoforms and suggest that the predictive value of Lp(a) as a risk factor for vascular occlusive disease would depend on the relative concentration of the isoform with the highest affinity for fibrin

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In the present investigation we studied the fusogenic process developed by influenza A, B and C viruses on cell surfaces and different factors associated with virus and cell membrane structures. The biological activity of purified virus strains was evaluated in hemagglutination, sialidase and fusion assays. Hemolysis by influenza A, B and C viruses ranging from 77.4 to 97.2%, from 20.0 to 65.0%, from 0.2 to 93.7% and from 9.0 to 76.1% was observed when human, chicken, rabbit and monkey erythrocytes, respectively, were tested at pH 5.5. At this pH, low hemolysis indexes for influenza A, B and C viruses were observed if horse erythrocytes were used as target cells for the fusion process, which could be explained by an inefficient receptor binding activity of influenza on N-glycolyl sialic acids. Differences in hemagglutinin receptor binding activity due to its specificity to N-acetyl or N-glycolyl cell surface oligosaccharides, density of these cellular receptors and level of negative charges on the cell surface may possibly explain these results, showing influence on the sialidase activity and the fusogenic process. Comparative analysis showed a lack of dependence between the sialidase and fusion activities developed by influenza B viruses. Influenza A viruses at low sialidase titers (<2) also exhibited clearly low hemolysis at pH 5.5 (15.8%), while influenza B viruses with similarly low sialidase titers showed highly variable hemolysis indexes (0.2 to 78.0%). These results support the idea that different virus and cell-associated factors such as those presented above have a significant effect on the multifactorial fusion process

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this communication we review the results obtained with the confocal laser scanning microscope to characterize the interaction of epimastigote and trypomastigote forms of Trypanosoma cruzi and tachyzoites of Toxoplasma gondii with host cells. Early events of the interaction process were studied by the simultaneous localization of sites of protein phosphorylation, revealed by immunocytochemistry, and sites of actin assembly, revealed by the use of labeled phaloidin. The results obtained show that proteins localized in the interaction sites are phosphorylated. The process of formation of the parasitophorous vacuole was monitored by labeling the host cell surface with fluorescent probes for lipids (PKH26), proteins (DTAF) and sialic acid (FITC-thiosemicarbazide) before interaction with the parasites. Evidence was obtained indicating transfer of components of the host cell surface to the parasite surface in the beginning of the interaction process. We also analyzed the distribution of cytoskeletal structures (microtubules and microfilaments visualized with specific antibodies), mitochondria (visualized with rhodamine 123), the Golgi complex (visualized with C6-NBD-ceramide) and the endoplasmic reticulum (visualized with anti-reticulin antibodies and DIOC6) during the evolution of intracellular parasitism. The results obtained show that some, but not all, structures change their position during evolution of the intracellular parasitism.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Leukocyte adhesion is of pivotal functional importance. The adhesion involves several different adhesion molecules, the most important of which are the leukocyte ß2-integrins (CD11/CD18), the intercellular adhesion molecules, and the selectins. We and others have extensively studied the specificity and binding sites in the integrins and the intercellular adhesion molecules for their receptors and ligands. The integrins have to become activated to exert their functions but the possible mechanisms of activation remain poorly understood. Importantly, a few novel intercellular adhesion molecules have been recently described, which seem to function only in specific tissues. Furthermore, it is becoming increasingly apparent that changes in integrins and intercellular adhesion molecules are associated with a number of acute and chronic diseases.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Chicken embryos kept in culture medium were bombarded using a high helium gas pressure biolistic device. To optimize the factors that affect transformation efficiency, the lacZ gene under control of the human cytomegalovirus immediate early enhancer/promoter was used as a reporter gene. There was an inverse relationship between survival rate and transformation efficiency. The best conditions obtained for high embryo survival and high transformation efficiency were achieved with 800 psi helium gas pressure, 500 mmHg vacuum, gold particles, an 8 cm DNA-coated microparticle flying distance to the embryo and embryo placement 0.5 cm from the center of the particle dispersion cone. Under these conditions, transformation efficiency was 100%, survival rate 25% and the number of expression units in the embryo body cells ranged from 100 to 1,000. Expression of green fluorescent protein was also detected in embryos bombarded under optimal conditions. Based on the results obtained, the biolistic process can be considered an efficient method for the transformation of chicken embryos and therefore can be used as a model system to study transient gene expression and tissue-specific promoters.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Verbal fluency tests are used as a measure of executive functions and language, and can also be used to evaluate semantic memory. We analyzed the influence of education, gender and age on scores in a verbal fluency test using the animal category, and on number of categories, clustering and switching. We examined 257 healthy participants (152 females and 105 males) with a mean age of 49.42 years (SD = 15.75) and having a mean educational level of 5.58 (SD = 4.25) years. We asked them to name as many animals as they could. Analysis of variance was performed to determine the effect of demographic variables. No significant effect of gender was observed for any of the measures. However, age seemed to influence the number of category changes, as expected for a sensitive frontal measure, after being controlled for the effect of education. Educational level had a statistically significant effect on all measures, except for clustering. Subject performance (mean number of animals named) according to schooling was: illiterates, 12.1; 1 to 4 years, 12.3; 5 to 8 years, 14.0; 9 to 11 years, 16.7, and more than 11 years, 17.8. We observed a decrease in performance in these five educational groups over time (more items recalled during the first 15 s, followed by a progressive reduction until the fourth interval). We conclude that education had the greatest effect on the category fluency test in this Brazilian sample. Therefore, we must take care in evaluating performance in lower educational subjects.