EMHD free-convection boundary-layer flow from a Riga-plate

The electro-magnetohydrodynamic (EMHD) free-convection flow of a weakly conducting fluid (e.g. seawater) from an electromagnetic actuator is considered. The actuator is a so called Riga-plate which consists of a spanwise aligned array of alternating electrodes and permanent magnets mounted on a plane surface. This array generates a surface-parallel Lorentz force which decreases exponentially in the direction normal to the (horizontal) plate. The free-convection boundary-layer flow induced by this body force is investigated numerically and analytically. It is shown that a certain length and velocity scale exists on which the flow characteristics are independent of the material properties of the fluid, as well as of the structural and functional parameters of the actuator. These universal velocity profiles are calculated numerically at different distances x from the leading edge and are discussed in some detail, both for the impermeable and the permeable Riga-plate when; in the latter case, a uniform lateral suction or injection of the fluid is applied. For the flow characteristics analytical approximations are reported. The asymptotic suction profiles approached for large values of x are given in exact analytical form. From a mathematical point of view the basic equations of the present boundary-value problem resemble those of the classical Blasius problem with an inhomogeneous forcing instead of an external flow and, accordingly, a homogeneous asymptotic condition.     

Variation of the physicochemical properties diesel-biodiesel blends – range 0–100%

Recently biodiesel has become more attractive because it is made from renewable resources. In this study we demonstrate how the proportion of diesel/biodiesel blends determines the qualitative parameters and energy efficiency of the final product. The use of biodiesel in blends with conventional diesel is becoming more and more valuable, based on European directive for use up to 20% biodiesel by 2020. We came to the conclusion that mixtures up 30% Biodiesel gives product within diesel specification limits which is suitable for commercial use. This methodology can be a manual for the production line of mixtures for commercial use.     

Atorvastatin Decreases Triacylglycerol-Associated Risk of Vascular Events in Coronary Heart Disease Patients

High triacylglycerol (TAG) levels may predict vascular risk. The effect of a statin-induced reduction in TAG levels, irrespective of HDL-C increase, on clinical outcome has not yet been addressed by an endpoint study in patients with coronary heart disease (CHD). The GREACE study compared usual with structured care aimed at achieving LDL-C = 100 mg/dL (2.6 mmol/L) by dose titration with atorvastatin. All patients had CHD and were followed for 3 years. This post hoc analysis of GREACE examines the effect of statins on TAG levels and their relation with cardiovascular disease (CVD) events in all patients and in the subgroup of patients with metabolic syndrome (MetS). Baseline TAG levels >150 mg/dL (1.7 mmol/L) were predictive of subsequent CVD events [cardiac mortality, non-fatal myocardial infarction (MI), unstable angina (UA), revascularisation, congestive heart failure (CHF), and stroke] only in statin untreated patients. Stepwise regression analysis showed that with every 20% statin-related TAG reduction there was a decrease in CVD risk by 12% (HR 0.88, 95% CI 0.75–0.95, P = 0.007) in the structured care group vs. the usual care group, by 8% (HR 0.92, 95% CI 0.81–0.97, P = 0.02) in all statin treated patients vs. the untreated ones and by 15% (HR 0.85, 95% CI 0.65–0.94, P = 0.005) in those with MetS treated with a statin vs. those untreated. Using the same analysis but only taking into consideration vascular events (cardiac mortality, non-fatal MI, UA, revascularisation, and stroke) there was a 18% (HR = 0.82, 95% CI 0.57–0.96, P = 0.03) decrease in risk in the MetS (+) patients treated with a statin vs. those not on a statin, and a decrease in risk by 16% (HR = 0.84, 95% CI 0.53–1.07, P = 0.08), when only hard vascular endpoints (cardiac mortality, non-fatal MI, and stroke) were considered. TAG levels are predictive of subsequent CVD events in statin untreated CHD patients. Statin (mainly atorvastatin)-induced decrease in TAG levels was related to a significant reduction in subsequent CVD events. This benefit was more pronounced in CHD MetS (+) patients.     

Further results on non-Newtonian power-law flows past a two-dimensional flat plate with finite length

The flow of a non-Newtonian, power-law fluid directed either tangentially or normally to a flat plate of finite length and infinite width (two-dimensional flow) is considered. The problem is investigated numerically using the code ANSYS FLUENT. This problem has been investigated in the past but only for shear-thinning fluids (n < 1). We extend the investigation for the case of shear-thinning, Newtonian and shear-thickening fluids, covering a wide range of Reynolds numbers (from very low to very high). For low Reynolds numbers and low power-law index (n < 0.6) the drag coefficient obeys the relationship c _D = A/Re, both for tangential and normal flow. Equations for the quantity A have been derived as functions of the power-law index. For normal flow, the drag coefficient tends to become independent of the power-law index, both for shear-thinning and shear-thickening fluids at high Reynolds numbers.     

The forced convection flow over a flat plate with finite length with a constant convective boundary condition

The flow of a fluid past a flat plate of finite length and infinite width (two-dimensional flow) is considered. The plate is heated by convection from a fluid with constant temperature T _f with a constant heat transfer coefficient h _f . In all previous works, the problem was considered using boundary layer theory whereas, in the present work, the solution is based on the full Navier-Stokes equations. The problem is investigated numerically with a finite volume method using the commercial code ANSYS FLUENT. The governing parameters are the Reynolds number, the new heat transfer parameter, and the Prandtl number. In addition, the influence of these three parameters on the temperature field is investigated. It is found that high Reynolds and high Prandtl numbers the wall temperature increases along the plate. They reach a maximum near the trailing edge then decrease. The same occurs as the heat transfer parameter increases. When the Reynolds and Prandtl numbers are low, the plate temperature tends to become symmetric, with a maximum at the middle of the plate. The temperature profiles become thicker as the Reynolds number and the Prandtl number is reduced while the temperature profiles become thicker as the heat transfer parameter increases.     

Vertical Penetration of Double-Diffusive Water Plumes Discharged Vertically Downward

Previously, it was shown that, in Turner’s formula which predicts the penetration depth of negatively buoyant jets, the classical initial densimetric Froude number should be replaced by an initial effective Froude number if the formula is applied to a heated water jet discharged downward. In the present paper, this conclusion is extended to double-diffusive plumes with two buoyancy components (heat and salt) which both oppose the downward flow. A new effective Froude number is introduced for double-diffusive plumes. For the calculation of the penetration depth a modified version of the integral Fan–Brooks model has been used. The same model is used to calculate the vertical penetration in the strongly nonlinear regions around the density maxima that appear in water at some special values of temperature and salinity. It is found that the penetration depth becomes very large if the existing ambient temperature and salinity are close to density extremum values and becomes infinite if the existing ambient temperature and salinity coincide with the maximum density values.     

Acquired reactive perforating collagenosis and pseudoporphyric bullous dermatosis in a hemodialysis patient

Hemodialysis patients present with a broad spectrum of specific and nonspecific skin disorders, which rarely coexist. We report an exceptional case of a hemodialysis patient that developed acquired reactive perforating collagenosis and pseudoporphyric bullous dermatosis on the basis of common skin disorders which include hyperpigmentation, pruritus, xerosis cutis, and Linsday's nails. Interestingly, our patient presented with two unusual but distinctive cutaneous dermopathies on the background of other commonly seen skin alterations. The patient was successfully treated with allopurinol and N‐acetylcysteine. Avoidance of potentially triggering factors such as alcohol, sunlight exposure and certain medication was recommended. Thus, increasing clinical awareness, assiduous investigation and early treatment of skin disorders are required to improve the prognosis and quality of life in this patient population.     

Physical and mechanical characteristics of TEOS-modified nanocomposites

Journal of Polymer Research - Sodium 2,2′-methylene-bis(4,6-di-tertbutylphenyl)-phosphate (NA11) is an α-type nucleating agent for improving the mechanical and crystallization...     

Convection in the Rayleigh-Bénard flow with all fluid properties variable

In the present paper,the effect of variable fluid properties(density,viscosity,thermal conductivity and specific heat) on the convection in the classical Rayleigh-Bénard problem is investigated.The investigation concerns water,air,and engine oil by taking into account the variation of fluid properties with temperature.The results are obtained by numerically solving the governing equations,using the SIMPLE algorithm and covering large temperature differences.It is found that the critical Rayleigh number increases as the temperature difference increases considering all fluid properties variable.However,when the fluid properties are kept constant,calculated at the mean temperature,and only density is considered variable,the critical Rayleigh number either decreases or remains constant.