SIMULATION OF TURBULENT FLOW IN POROUS MEDIA USING A SPATIALLY PERIODIC ARRAY AND A LOW RE TWO-EQUATION CLOSURE

The present work consists of comparative evaluation of the finite-element and finite-difference methods for the solution of complex fluid flow and heat transfer problems. The test case considered here is the problem of natural convection in an annular cavity. Both closed and open ended cases are considered. It was found that the finite-difference analysis succeeds in capturing minute details of the solution at high Rayleigh number flows and the finite-element method fails to do so. However, the finite-element method enjoys the advantage of providing sufficiently accurate results even with coarse meshes. This results in significant savings in computational costs without any sacrifice in the accuracy of the solution. Hence, the finite-element method can serve as an optimum tool for most problems of practical interest.     

NUMERICAL SIMULATION OF TURBULENT FLOW IN SMALL-ANGLE DIFFUSERS AND CONTRACTIONS USING A NEW WALL TREATMENT AND A LINEAR HIGH REYNOLDS k–ε MODEL

This work presents numerical prediction for the turbulent flow field confined in a circular duct past a segment of gradually varying cross section. Both expanding and contracting sections are investigated. Equations of boundary-layer type are used and the linear k–ε model, in its high Reynolds form, is applied. A new correlation for treating the grid point closest to the wall is proposed. A marching-forward method is employed for sweeping the computational domain. Computations are first performed for developing and fully developed constant-area ducts in order to assess the reliability of the code. Results are then presented for contractions and diffusers, where comparisons with experimental data for air and water are carried out. Turbulence damping in contractions and its enhancement in diffusers are calculated correctly. Further, for contractions with angles of up to 21°, the use of a parabolic solver shows good agreement with experimental values for the mean and statistical quantities. For diffusers, adverse pressure gradient along the flow limits the quality of the predictions as the angle and length of diffuser increase past 5° and 10 duct radii, respectively.     

Antiangiogenesis,Loss of Cell Adhesion and Apoptosis Are Involved in the Antitumoral Activity of Proteases from V. cundinamarcensis (C. candamarcensis) in Murine Melanoma B16F1

The proteolytic enzymes from V. cundinamarcensis latex, (P1G10), display healing activity in animal models following various types of lesions. P1G10 or the purified isoforms act as mitogens on fibroblast and epithelial cells by stimulating angiogenesis and wound healing in gastric and cutaneous ulcers models. Based on evidence that plant proteinases act as antitumorals, we verified this effect on a murine melanoma model. The antitumoral effect analyzed mice survival and tumor development after subcutaneous administration of P1G10 into C57BL/6J mice bearing B16F1 low metastatic melanoma. Possible factors involved in the antitumoral action were assessed, i.e., cytotoxicity, cell adhesion and apoptosis in vitro, haemoglobin (Hb), vascular endothelial growth factor (VEGF), tumor growth factor-β (TGF-β), tumor necrosis factor-α (TNF-α) content and N-acetyl-glucosaminidase (NAG) activity. We observed that P1G10 inhibited angiogenesis measured by the decline of Hb and VEGF within the tumor, and TGF-β displayed a non-significant increase and TNF-α showed a minor non-significant reduction. On the other hand, there was an increase in NAG activity. In treated B16F1 cells, apoptosis was induced along with decreased cell binding to extracellular matrix components (ECM) and anchorage, without impairing viability.     

Influence of Some Fatty Acids on Oviposition by the Bruchid Beetle, Callosobruchus maculatus

The cowpea seed beetle, Callosobruchus maculatus, will lay its eggs on many potential hosts and inert surfaces. Oviposition on glass beads is stimulated by coating them with individual fatty acids. Nevertheless, female beetles reject mung seeds less frequently than beads treated with either an extract of mung seeds or, especially, an extract of mung seeds plus oleic acid. The addition of oleic acid to the extract resulted in a change in the sequence of oviposition behavior, notably an increase in a raised body position indicative of hosts of low acceptability. Fatty acids are present in the epicuticular waxes of legume seeds; wax extract of mung bean contains 32.4% fatty acid and 14 alkanes, whereas a wax extract of chickpea contains 5% fatty acid and 18 alkanes. Thus, chickpea may be a less acceptable host for oviposition than mung bean because of physical differences and/or because of chemical differences, including a reduced total level of fatty acid or the high proportion of oleic acid it is reported to contain. It is concluded that an appropriate mixture of fatty acids in the epicuticular waxes stimulates oviposition but that an elevated level of oleic acid in conjunction with others is deterrent.     

Synthesis and Characterization of a New Bifunctionalized,Fluorescent, and Amphiphilic Molecule for Recruiting SH‐Containing Molecules to Membranes

This study describes the synthesis and characterization of an amphiphilic construct intended to recruit SH‐containing molecules to membranes. The construct consists of 1) an aliphatic chain to enable anchoring within membranes, 2) a maleimide moiety to react with the sulfhydryl group of a soluble (bio)molecule, and 3) a fluorescence moiety to allow the construct to be followed by fluorescence spectroscopy and microscopy. It is shown that the construct can be incorporated into preformed membranes, thus allowing application of the approach with biological membranes. The close proximity between the fluorophore and the maleimide moiety within the construct causes fluorescence quenching. This allows monitoring of the reaction with SH‐containing molecules by measurement of increases in fluorescence intensity and lifetime. Notably, the construct distributes into laterally ordered membrane domains of lipid vesicles, which is probably triggered by the length of its membrane anchor. The advantages of the new construct can be employed for several biological, biotechnological, and medicinal applications.     

Soybean Oil and Selenium Yeast Supplementation in Quail's Diet: Productive Performance,Fatty Acid Profile,Enzyme Activity,and Oxidative Stability of Meat

The objective of this study is to evaluate the influence of different soybean oil (SO) and selenium yeast (SeY) levels in the diet of meat quails on productive performance, physicochemical, quality measurements, fatty acid profile, enzyme activity estimation, and oxidative stability of meat. A total of 288 one-day old commercial meat quails are allocated into four groups according to a completely randomized experimental design, with two levels of SO (1.5% and 3.0%) and SeY (0 and 0.15 mg kg⁻¹) in the feed. The supplementation period is 42 days. The use of up to 3% supplementation of SO in the diet improves (p < 0.05) the productive performance. The polyunsaturated acid content and thiobarbituric acid value in the meat are increased (p < 0.05) as an effect of the SO increase in the diet. The use of SeY in quail diets associates with 3% inclusion of SO and promotes improvements in the qualitative parameters of the quail meat. Therefore, the inclusion of 0.15 mg kg⁻¹ of SeY in the diets is a viable alternative for improving the oxidative stability of meat since it improves the qualitative parameters of quail meat in diets with a high inclusion of SO. Practical Applications: These results have practical applicability in the meat industry, since it is possible to change the lipid profile of this raw material, meeting the requirement of the consumer market for healthy foods, reducing the total cholesterol content, and nutritionally desirable, through enrichment with polyunsaturated fatty acids.     

Catalytically active membranes for esterification: A review

Esterification is an important process in the food industry and can be carried out via homogeneous or heterogeneous catalysis. The homogeneous catalyst, despite providing high conversion, can cause corrosion in reactors, which is not observed with the use of heterogeneous catalysts. However, some of these catalysts require a high process temperature and may lose their catalytic activity with reuse. Thus, catalytic membranes have been proposed as a promising alternative. The combination of cataly...