Linear Conforming and Nonconforming Upwind Finite Elements for the Convection-Diffusion Equation

A conforming and a nonconforming method for the approximation of the stationary 2-D convection-diffusion equation at high Péclet number are presented. Convergence of order h is proved in a generic case and, for a particular choice of the upwind schemes, a discrete maximum principle is established under very unrestrictive conditions on the mesh. Results of numerical computations are produced to show the practical convergence of these method

Inhibition of copper corrosion by bipyrazole compound in aerated 3% NaCl

AbstractThe corrosion behaviour of copper in aerated 3% NaCl solution was investigated by rotating electrode at various rates. The reduction of O2 obeys the Levich equation. The inhibition of the copper corrosion in aerated 3% NaCl solution was studied by using potentiodynamic polarisation and linear polarisation resistance (LRP) in the presence of different concentrations of a bipyrazolic compound named N,N-bis (3-carbomethoxy-5-methylpyrazol-1-ylmethyl) cyclohexylamine (BiPyA). The presence of this compound in the solution decreases the corrosion current density and increases the linear resistance polarisation. The inhibition efficiencies obtained from cathodic Tafel plots and LRP methods are in good agreement. BiPyA compound presents an efficient inhibitor of copper corrosion, acts as a mixed-type inhibitor and adsorbs on the copper surface according to the Langmuir isotherm model

Diuretic activity of carob (Ceratonia silique L.) Honey: comparison with furosemide

Background: Honey has wide range of biological activities. It has effect on renal function, and urinary nitric oxide and prostaglandins level. The present study was conducted to evaluate diuretic potential of carob honey, collected from Morocco, in normal rats and the results were compared with use of furosemide.Materials and methods: Adult male Wister rats weighing between 230 and 278 g were used. The animals were divided into three groups; group 1 received oral administration of distilled water (10 ml/kg BW), and served as control group, group 2 received oral administration of furosemide (10 mg/kg BW), and group 3 was treated with oral administration of carob honey (100 mg/kg BW). Urine volume, and urine and plasma sodium and potassium were measured after single dose of the interventions and after daily administrations of the interventions.Results: After the single dose of carob honey, urine output was significantly increased at all time intervals (1-6 hrs and at 24 hrs after administration). The daily dose of carob honey for nine days significantly increased urine volume as compared to control group. Carob honey increased urinary levels of sodium and potassium, and did not cause hypokalemia, while furosemide increased urinary sodium and potassium and caused hypokalemia.Conclusion: Carob honey has diuretic, natriuretic and kaliuretic activity without side effects of hypokalemia that was observed with use of furosemide.Key words: Carob honey, furosemide, diuresis, sodium, potassium, creatinine clearanc

Metal corrosion inhibition by triazoles : A review

Metal corrosion and the prospects of inhibiting this process have received much interest from society and scientific research. The annual global cost of corrosion is $2.5 trillion, equivalent to roughly 3.4% of the world's gross domestic product. Implementing corrosion prevention best practices could result in global savings of 15-35% of that cost. Numerous studies were documented and dedicated on the triazole nucleus based compounds as fascinating corrosion inhibitors of various metals in hostile media. Their unique electronic structure possessing conjugated pi and unshared pairs of electrons on the nitrogen atoms facilitates their adsorption on metal surfaces. Thus, physical and chemical interactions between the active centers of triazoles and d-orbitals of metallic materials occur to form a film on the surface. The nature of inhibitor activity is disclosed through polarization studies (cathodic, anodic or mixed-type). The range of various substituents on the triazole ring offers a vast array of inhibitory effects. temperature and inhibitor concentration effects must also be regarded when evaluating the corrosion activation and adsorption parameters supported further by the quantum chemical parameters such as DFT and molecular dynamics simulations. In this review, we looked through several instances of the use of distinct substituted triazole nucleus based compounds as significant corrosion inhibitors for different metals in various aggressive media.Peer reviewe

Disappearance of Azoxystrobin and difenoconazole in green beans cultivated in Souss Massa valley (Morocco)

A study was undertaken to evaluate the degradation behavior and residue levels of azoxystrobin and difenoconazole in Belma green beans variety grown in an experimental plastic greenhouse. The measurements were made over a 3 week period in which up to two successive treatments with azoxystrobin and a 5 week period in which up to two successive treatments with difenoconazole were carried out. Residue levels of dicofol and difenoconazole were determined by Gas chromatography with electron capture detection (GC-ECD), liquid-liquid extraction (LLE), solid phase extraction (SPE) and high-performance liquid chromatography (HPLC). During the study, residue levels in the plantation ranged between 0.35 and 0.01 mg/kg for azoxystrobin and between 0.25 and 0.01 mg/kg for difenoconazole. The residual concentrations after the preharvest intervals (PHI) were below the legal limits