71 resultados para VOID FRACTION


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The success of manufacturing composite parts by liquid composite molding processes with RTM depends on tool designs, efficient heat system, a controlled injection pressure, a stabilized vacuum system, besides of a suitable study of the preform lay-up and the resin system choice. This paper reports how to assemble a RTM system in a laboratory scale by specifying heat, injection and vacuum system. The design and mold material were outlined by pointing out its advantages and disadvantages. Four different carbon fiber fabrics were used for testing the RTM system. The injection pressure was analyzed regarding fiber volume content, preform compression and permeability, showing how these factors can affect the process parameters. The glass transition temperature (Tg) around 203 ºC matched with the aimed temperature of the mold which ensured good distribution of the heat throughout the upper and lower mold length. The void volume fraction in a range of 2% confirmed the appropriate RTM system and parameters choice.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The interest in the use of vegetable fibers (e.g. jute, sisal and curaua) for more noble applications, such as reinforcement in polymeric composite materials, has increased over the years due to a variety of aspects, especially those related to environmental legislation and community awareness regarding the life cycle of products. In this context, the aim of this work is to develop hybrid interlaminate curaua/glass/insaturated polyester composites by hot compression molding and to analyze their mechanical properties as a function of the thickness of the laminate. The short beam strength of the thickest sample decreased due to its higher void content. Furthermore, the thinnest sample showed lower hardness, and lower impact, tensile and Iosipescu shear strength, partly attributed to its lower fiber volumetric fraction. Thus, in general, the most adequate laminate was the one comprising eight layers, four of which were of glass fiber and four of curaua fiber, but only if flexural loading is not critical.

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Objectives: Syngonanthus macrolepis, popularly known in Brazil as sempre-vivas', is a plant from the family Eriocaulaceae, it is found in the states of Minas Gerais and Bahia. The species contains a variety of constituents, including flavonoids with gastroprotective effect. In this work, a flavonoid-rich fraction (Sm-FRF) obtained from scapes of S.macrolepis was investigated for preventing gastric ulceration in mice and rats.MethodsThe activity was evaluated in models of induced gastric ulcer (absolute ethanol, stress, non-steroidal anti-inflammatory drugs and pylorus ligation). The cytoprotective mechanisms of the Sm-FRF in relation to sulfhydryl (SH) groups, nitric oxide (NO) and antioxidant enzymes were also evaluated.Key findingsThe Sm-FRF (100mg/kg, p.o.) significantly reduced gastric injury in all models, and did not alter gastric juice parameters after pylorus ligation.ConclusionsThe results indicate significant gastroprotective activity for the Sm-FRF, which probably involves the participation of both SH groups and the antioxidant system. Both are integral parts of the gastrointestinal mucosa's cytoprotective mechanisms against aggressive factors.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The idiopathic dilated cardiomyopathy (IDC) is one of the major public health problems in the western world. Patients with IDC in functional class IV (New York Health Association - NYHA), even after therapeutic optimization, have high mortality. Stem cell therapy has emerged as a potential therapeutic option for cell death-related heart diseases and several positive effects were assigned to cell therapy in cardiomyopathy. The aim of this study was identify short-term result of cell transplantation in idiopathic dilated cardiomyopathy patients (IDC) who were treated by transplantation of autologous bone marrow mononuclear cells (BMMC). Intracoronary injections of autologous BMMC were performed in eight patients with severe ventricle dysfunction (mean of left ventricle ejection fraction – LEVF=20.03%), cardiac mass muscle around 156.2 g and NYHA between III and IV grades, other 8 IDC patients received placebo. The IDCs were followed - up for one and two years, by magnetic resonance imaging (MRI). The results after one year showed significant improvement in LVEF (mean=181.4) and muscle mass increasing (mean=181.4 g), after two years the LVEF continued improving, reaching a mean of 32.69% and the cardiac muscle mass kept stable (mean=179.4 g). Excepted for one patient, all the other had improvement in the NYHA functional class. The placebo group did not show any improvement. We believe that BMMC implant may be a beneficial therapeutic option for IDC patients.

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The Spanish region of Campos de Hellin (Albacete) is characterized by a wide range of olive varieties (Arbequina, Benizal, Cornicabra, Cuquillo, Injerta, Manzanilla Local, Manzanilla de Sevilla, Negrilla, Picual), which provides different physicochemical and sensory characteristics to the oils. Thus, the knowledge of these characteristics may help develop more balanced oils. Monovarietal virgin olive oils from the different varieties grown in this area were characterized from the physicochemical and sensory points of view during four consecutive years. Clear differences among the varieties were found when principal component analysis was applied to the data from the studied parameters. The varieties were grouped according to their oleic and linoleic acid content, oxidative stability, and campesterol and total sterols content. The differences were significant with a 95% confidence level. The variety effect on the oil characteristics was stronger than the effect of the crop year. Practical applications: Chemical and sensory characteristics of monovarietal virgin olive oils play an important role in the elaboration of blends. In olive-growing regions where there is more than one variety cultivated, the characterization of monovarietal oils could increase the value of the olive oil produced due to the development of more balanced oils tailored to the preferences of consumers. This work shows that the chemical and sensory differences between varieties make possible the elaboration of a new range of virgin olive oils. This could encourage the development and marketing of quality oils, and thus increase the competitiveness of the mills in the oil market.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Anacardium humile St. Hil. is being used in traditional medicine to treat ulcer. The present work evaluated the mechanisms of action involved in the anti-ulcer properties of the aqueous fraction from leaves of A. humile (AHQ). Gastroprotection of A. humile was evaluated in ethanol and piroxicam models. Mechanisms of action such as mucus production, nitric oxide (NO), sulfhydryl compounds (SH) and the anti-secretory action were evaluated. The acetic acid-induced gastric ulcer model was used to evaluate the A. humile healing properties. Results obtained in the ethanol model showed that AHQ provided significant gastroprotection at all the tested doses (50, 100, and 200 mg/kg). Thereby, the following protocols were performed using the dose capable of producing the most effective gastroprotection, which was the AHQ 200 mg/kg (P < 0.001). Moreover, AHQ (200 mg/kg) protected the mucosa from piroxicam-induced damage. Mucus, NO, and SH did not participate on this gastroprotection. AHQ interfere in H+ secretion in gastric mucosa, thus exerting an anti-secretory activity. Our results suggest that the gastroprotection and cicatrisation process executed by AHQ occurred due to its anti-secretory activity. This study reinforces its traditional medicinal use. Considering that the current therapies are based on the use of anti-secretory agents, the A. humile arises as a promising alternative antiulcer therapy.