860 resultados para 640306 Beneficiation or dressing of non-metallic minerals (incl. diamonds)
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This is the first paper in a two-part series devoted to studying the Hausdorff dimension of invariant sets of non-uniformly hyperbolic, non-conformal maps. Here we consider a general abstract model, that we call piecewise smooth maps with holes. We show that the Hausdorff dimension of the repeller is strictly less than the dimension of the ambient manifold. Our approach also provides information on escape rates and dynamical dimension of the repeller.
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Nonculture based methods for the detection of infections caused by fungal pathogens are becoming more important tools in the management of infected patients. Detection of fungal antigens and DNA appear to be the most promising in this respect for both opportunistic and endemic mycoses. In this article we present an overview of the most recent developments in nonculture based methods and examine their value in clinical practice.
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The aim of this work was the development of miniaturized structures useful for retention and/or selection of particles and viscous substances from a liquid flow. The proposed low costs structures are similar to macroscopic wastewater treatment systems, named baffles, and allow disassemble. They were simulated using FEMLAB 3.2b package and manufactured in acrylic with conventional tools. Tests for retention or selection of particles in water or air and viscous fluids in water were carried out. Either in air or water particles with 50 mu m diameter will be retained but not with 13 mu m diameter. In aqueous flow, it is also possible the retention of viscous samples, such as silicone 350 cSt. The simulated results showed good agreement with experimental measurements. These miniaturized structures can be useful in sample pretreatment for chemical analysis and microorganism manipulation. (C) 2007 Elsevier B.V. All rights reserved.
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The influence of different non-resorbable suture materials on the healing of tooth extraction wounds was examined in 120 adult male albino rats. Nylon gave the best biological results for healing of the mucosa and dental socket. Silk and cotton produced considerable delay of socket healing. Healing was only mildly delayed by polyester suture, with a short moderate inflammatory reaction at the initial stage.
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In this paper we relate the numerical invariants attached to a projective curve, called the order sequence of the curve, to the geometry of the varieties of tangent linear spaces to the curve and to the Gauss maps of the curve. © 1992 Sociedade Brasileira de Matemática.
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We discuss non-steady state electrical characteristics of a metal-insulator-metal structure. We consider an exponential distribution (in energy) of impurity states in addition to impurity states at a single energy level within the depletion region. We discuss thermal as well as isothermal characteristics and present an expression for the temperature of maximum current (Tm) and a method to calculate the density of exponentially distributed impurity states. We plot the theoretical curves for various sets of parameters and the variation of Tm, and Im (maximum current) with applied potential for various impurity distributions. The present model can explain the available experimental results. Finally we compare the non-steady state characteristics in three cases: (i) impurity states only at a single energy level, (ii) uniform energetic distribution of impurity states, and (iii) exponential energetic distribution of impurity states.
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Objective: To examine the basis for local wall motion abnormalities commonly seen in patients with ischemic heart disease, computer-controlled isolated muscle studies were carried out. Methods: Force patterns of physiologically sequenced contractions (PSCs) from rat left ventricular muscle preparations under well-oxygenated conditions and during periods of hypoxia and reoxygenation were recorded and stored in a computer. Force patterns of hypoxic-reoxygenating and oxygenated myocardium were applied to oxygenated and hypoxic-reoxygenating myocardium, respectively. Results: Observed patterns of shortening and lengthening closely resemble those obtained from ischemic and non-ischemic myocardial segments using ultrasonic crystals in intact dog hearts during coronary occlusion and reperfusion, and are similar to findings reported in angiographic studies of humans with coronary artery disease. Conclusion: The current study, demonstrating motions of oxygenated isolated muscle preparations which are similar to those in perfused segments of intact hearts with regional ischemia, supports the concept that the multiple motions of both ischemic and non-ischemic segments seen in regional myocardial disease can be explained by interactions of strongly and weakly contracting muscle during the physiologic cardiac cycle.
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Skin cancers are the most common human malignant neoplasia and their incidence is growing, chiefly in tropical countries. There is evidence that ultraviolet (UV) radiation present in sunlight is important for genetic damage. Mutations due to such damage could be responsible for alterations in oncogenes and tumor suppressor genes. Recent studies have reported remarkable differences in mutation frequency of the RAS proto-oncogene in non-melanoma skin cancers. These findings may reflect differences in the molecular epidemiology of cutaneous tumors found in geographical areas with diverse sun exposure and ethnical origins of their populations. Our study proposed to perform molecular analyses of skin tumors on patients living in southeastern Brazil, in areas with high levels of sun exposure. DNA from eight solar keratose (SK), 26 basal cell carcinomas (BCC) and 19 squamous cell carcinomas (SCC) was submitted to PCR-SSCP analysis for codons 12, 13 and 61. Contradicting other authors, we found no mutations in codons 12,13 but detected two BCCs and one SCC with a mutation in codon 61. These findings suggest that the activation of KRAS oncogene may contribute to the pathogenicity of cutaneous lesions in southeastern Brazil.
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The aim of this work is to characterize a metallic slurry (Al-4.5%Cu) flow during thixoforming of an automotive valve. The necessary globular structure was obtained by first inoculating the alloy with TIBAL (5%Ti, 1%B, Al - rest) at 750.0°C, and then reheating to a state between liquidus and solidus prior to thixoforming. Two metallic slurries, with a solid phase of approximately 86.1 and 78.2 percent, were used to generate different experimental flow patterns during the thixoforming process. The flow of the material into the die was observed for total, and partial displacement (2.7, 5.4, 7.5mm) of the punch. The first displacement shows formation of the valve rod. The patterns at each step of displacement of the punch were preserved by quenching in water, thus revealing the profile of the die fill and microstructural evolution. Degeneration of the globular phase was observed along the piece thixoextruded. Thixoextrusion forces versus time curves were generated for partial and full displacement of the punch. Porosity was visible along the billet prior to thixoforming. However, some areas show that the porosity gradually decreased to zero as the thixoextrusion pressure increased. Turbulent, transient and laminar flow are analyzed in this work.
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Samples of paint (P), reused PET (PET-R) and paint/PET-R mixtures (PPET-R) were evaluated using DSC to verify their physical-chemical properties and thermal behavior. Films from paints and PPET-R are visually similar. It was possible to establish that the maximum amount of PET-R that can be added to paint without significantly altering its filming properties is 2%. The cure process (80-203°C) was identified through DSC curves. The kinetic parameters, activation energy (E a) and Arrhenius parameters (A) for the samples containing 0.5 to 1% of PET-R, were calculated using the Flynn-Wall-Ozawa isoconversional method. It was observed that for greater amounts of PET-R added, there is a decrease in the E a values for the cure process. A Kinetic compensation effect (KCE), represented by the equation InA=-2.70+0.31E a was observed for all the samples. The most suitable kinetic model to describe this cure process is the autocatalytic Šesták-Berggreen, model applied to heterogeneous systems. © 2007 Springer Science+Business Media, LLC.
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In this paper, we present the rare case of a patient with cervical lymphadenopathy diagnosed as a T-cell-rich B-cell non-Hodgkin lymphoma that manifested Horner's syndrome due to a post-ganglionic sympathetic neuron lesion caused by the tumor. Copyright © 2012 S. Karger AG, Basel.