Three dimensional steady and unsteady asymmetric flow past wings of arbitrary planforms

The nonlinear discrete vortex method was extended to treat the problem of asymmetric flows past a wing with leading-edge separation, including steady and unsteady flows. The problem was formulated in terms of a body-fixed frame of reference, and the nonlinear discrete vortex method was modified accordingly. Only examples of flows past delta wings are presented. Comparison of these results with experimental results for a delta wing undergoing a steady rolling motion at zero angle of attack demonstrates the superiority of the present method in obtaining highly accurate loads. Numerical results for yawed wings at large angles of attack are also presented. In all cases, total load coefficients, pressure distributions and shapes of the free-vortex sheets are shown

Unsteady flow past wings having sharp-edge separation

A vortex-lattice technique is developed to model unsteady, incompressible flow past thin wings. This technique predicts the shape of the wake as a function of time; thus, it is not restricted by planform, aspect ratio, or angle of attack as long as vortex bursting does not occur and the flow does not separate from the wing surface. Moreover, the technique can be applied to wings of arbitrary curvature undergoing general motion; thus, it can treat rigid-body motion, arbitrary wing deformation, gusts in the freestream, and periodic motions. Numerical results are presented for low-aspect rectangular wings undergoing a constant-rate, rigid-body rotation about the trailing edge. The results for the unsteady motion are compared with those predicted by assuming quasi-steady motion. The present results exhibit hysteretic behavior

Effects of micronutrients on oxidative stress in HIV positive patients taking highly active antiretroviral therapy (HAART) in a tertiary health care facility in Kano, northwest Nigeria

The study examined the effects of micronutrients supplementation on oxidative stress markers in HIV positive patients on highly active antiretroviral therapy (HAART), attending Aminu Kano Teaching Hospital (AKTH) Kano-Nigeria. Fifty four (54) HIV positive individuals already taking HAART were placed on a daily dose of a multivitamin supplement for a period of three months. Another 54 HIV positive subjects who were already on HAART served as the control group for the same period of time. Prior to the multivitamin supplementation, the baseline mean serum vitamin A, C, and E, selenium, zinc, malondehaldehyde (MDA), albumin, total protein, and CD4+ count values were established. With the exception of mean serum vitamin C, the mean serum values for the studied parameters after the supplementation period increased significantly (P<0.05) in the non supplemented group compared to their baseline values. The mean serum vitamin A, C, and E, Se, total protein and CD4+ count of the supplemented group increased significantly when compared to their baseline values. Mean serum MDA was significantly decreased (P<0.05) in the multivitamin supplemented group compared to their baseline. No significant difference (P<0.05) was seen in the mean serum vitamin C and albumin of the multivitamin supplemented group as compared to their baseline. The mean serum vitamins A, C, and E and the CD4+ count of the multivitamins supplemented subjects significantly increased (P<0.05) when compared to that of the non supplemented subjects. Mean serum selenium and zinc increased significantly (P<0.05) in the non supplemented subjects but not in the supplemented subjects. The serum thiobarbituric acid reactive substances (TBARs) in the form of malondialdehyde (MDA), for the supplemented subjects was found to reduce significantly (P<0.05) compared to that of the non supplemented subjects. Statistical analysis showed no significant difference between the supplemented and the non supplemented subjects in their serum total protein and albumin. Among the supplemented Subjects, vitamin A and C increased significantly (P<0.05) in the ARV treatment naïve sub group. Vitamin E, selenium and zinc increased significantly (P<0.05) in the ARV treated sub group, while MDA decreased significantly (P<0.05) in this sub group. Micronutrient supplementation was therefore shown to reduce oxidative stress in HIV positive patients on HAART and could possibly be very helpful as an adjunct in the treatment of this disease.Key Words: Antiretroviral, micronutrients, malondialdehyde, ART naïve, reactive oxygen species, supplementation

Electronic structure and magnetic state of transuranium metals under pressure

Electronic structure of bcc Np, fcc Pu, Am, and Cm pure metals under pressure has been investigated employing the LDA+U method with spin-orbit coupling (LDA+U+SO). Magnetic state of the actinide ions was analyzed in both LS and jj coupling schemes to reveal the applicability of corresponding coupling bases. It was demonstrated that whereas Pu and Am are well described within the jj coupling scheme, Np and Cm can be described appropriately neither in {m-sigma}, nor in {jmj} basis, due to intermediate coupling scheme realizing in these metals that requires some finer treatment. The LDA+U+SO results for the considered transuranium metals reveal bands broadening and gradual 5f electron delocalization under pressure.Comment: 5 pages, 5 figure

Inclusion of Experimental Information in First Principles Modeling of Materials

We propose a novel approach to model amorphous materials using a first principles density functional method while simultaneously enforcing agreement with selected experimental data. We illustrate our method with applications to amorphous silicon and glassy GeSe$_2$. The structural, vibrational and electronic properties of the models are found to be in agreement with experimental results. The method is general and can be extended to other complex materials.Comment: 11 pages, 8 PostScript figures, submitted to J. Phys.: Condens. Matter in honor of Mike Thorpe's 60th birthda

Non-Gaussian Distributions in Extended Dynamical Systems

We propose a novel mechanism for the origin of non-Gaussian tails in the probability distribution functions (PDFs) of local variables in nonlinear, diffusive, dynamical systems including passive scalars advected by chaotic velocity fields. Intermittent fluctuations on appropriate time scales in the amplitude of the (chaotic) noise can lead to exponential tails. We provide numerical evidence for such behavior in deterministic, discrete-time passive scalar models. Different possibilities for PDFs are also outlined.Comment: 12 pages and 6 figs obtainable from the authors, LaTex file, OSU-preprint-

Application of Stabilized Silver Nanoparticles as Thin Films as Corrosion Inhibitors for Carbon Steel Alloy in 1 M Hydrochloric Acid

Nanometer scaled materials have attracted tremendous interest as corrosion protective films due to their high ability to form self-assembled films on the metal surfaces. It is well known that the silver nanoparticles have higher reactivity towards aqueous acidic solution. The present work aims to prepare coated silver nanoparticles to protect carbon steel alloys from aqueous acidic corrosive media. In this respect, Ag nanoparticles colloid solutions were produced through reducing AgNO3 separately with trisodium citrate in an aqueous solution or in the presence of stabilizer such as poly(ethylene glycol) thiol and poly(vinyl pyrrolidone). The morphology of the modified silver nanoparticles was investigated by TEM and DLS. UV-Vis absorption spectrum was used to study the effect of HCl on the stability of the dispersed silver nanoparticles. The corrosion inhibition efficiency of the poly (ethylene glycol)thiol, the self-assembled monolayers of Ag nanoparticles, was determined by polarization method and electrochemical impedance spectroscopy (EIS). Polarization curves indicated that the coated silver poly (ethylene glycol)thiol acted as a mixed type inhibitor. The data of inhibition efficiencies obtained measured by polarization measurements are in good agreement with those obtained with electrochemical impedance

Autism and Fragile X: Is There a Neurochemical Link?

BACKGROUND:Autism and Fragile X syndrome are intertwined. This study aimed at assessing Serotonin, Glutamate, and Gama Amino Butyric Acid (GABA) in autism and Fragile X syndrome patients and to detect possible neurochemical similarities between the 2 disorders that can be used as metabolic biomarkers.DESIGN AND METHODS: Eighty subjects divided into four groups, two diseased groups (20 male patients with Autism and 20 males with Fragile X syndrome) and two control groups (20 neurotypical male controls and 20 Down syndrome male patients) were included. Estimation of Serotonin, Glutamate and GABA were done using Enzyme linked Immunosorbent Assay (ELISA), Tandem Mass Spectrometry and high-pressure liquid chromatography (HPLC), respectively.RESULTS: Serotonin was, exclusively, significantly low in autistic children. GABA was significantly high in both autistic and Fragile X children only, but not in Down syndrome children. Glutamate was significantly high in children with autism, Fragile X and Down syndrome Children.CONCLUSIONS: Autism and Fragile X syndrome share some neurochemical similarities with regards of high Glutamate and GABA levels while Serotonin was significantly different in the 2 disorders and may be used a unique biomarker for autism

Reverse Monte Carlo modeling of amorphous silicon

An implementation of the Reverse Monte Carlo algorithm is presented for the study of amorphous tetrahedral semiconductors. By taking into account a number of constraints that describe the tetrahedral bonding geometry along with the radial distribution function, we construct a model of amorphous silicon using the reverse monte carlo technique. Starting from a completely random configuration, we generate a model of amorphous silicon containing 500 atoms closely reproducing the experimental static structure factor and bond angle distribution and in improved agreement with electronic properties. Comparison is made to existing Reverse Monte Carlo models, and the importance of suitable constraints beside experimental data is stressed.Comment: 6 pages, 4 PostScript figure