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Fuel cell performance was studied with regard to alcohols electro-oxidation on modified platinum under different conditions such as temperature and modification time. This research is aimed to estimate each of cell voltages and power densities as a function of current densities and the other cell parameters. The electrochemical cells operated on the electro-oxidation of methanol and ethanol in both HClO4 as an acidic medium and KOH as an alkaline medium. Applying the definition of electromotive force combined with Ohm’s law on the oxidation reaction, power density curves are constructed. Optimum parameters for cell voltage and power density had been determined.

Background In the last few decades the rate of peritrochanteric fractures has increased because of increased rate of high velocity trauma accident and bone rarefaction due to osteoporosis in old age. DHS and PFN are the gold standard treatments used in treatment of these fractures. Nineteen studies were identified for analysis from 2007 to 2017 that meet our points of comparison. Aim of the Work Assessing of efficacy and complications of treatmeant of preitrochantric fracture by DHS versus PFN. Materials and Methods Outcomes from included trials will be combined using the systematic review manger software and manually screened for eligibility to be included. PRISMA flowchart will be produced based on the search results and the inclusion /exclusion criteria. After pooling of the collected data from the desired search studies, the relative risk of each of intended outcome measures of interest will be calculated and compared between each of the two main methods of peritrochanteric bone fixation treatment to reach a satisfactory conclusion. Evidence of publication bias will be sought using the funnel plot method. Results PFN is better for treating unstable peritrochanteric fractures as it has less complications and better efficacy than DHS. Conclusion The present study supports the treatment of peritrochanteric fractures with PFN, as it has less failure of fixation, decreased wound infection, less duration of surgery and less non-union complication than DHS.

Background Obesity continues to be a leading public health concern associated with many comorbidities and major hindering effect on the daily lifestyle of many people around the world. Surgical treatment for obesity has proved that it is the best and most effective, durable means of preventing the life-threatening complications and serious problems associated with morbid obesity. Objective This study aims at identifying the effect of LSG on UGI symptoms after a mean of 6 months of follow up. Patients and Methods Our study was conducted on 25 morbidly obese patients undergoing LSG for weight reduction. Thorough history, clinical examination and investigations were applied including the validated Rome III Diagnostic questionnaire and UGI endoscopy on cases with sever symptoms. Patients were examined before surgery and had no primary complications as bleeding or leakage in the early post-operative period. Patients were followed up for a mean of 6 months regarding UGI symptoms specially GERD using the same validated Rome III Diagnostic questionnaire. Results GERD prevalence didn’t significantly change although a significant number of patients recovered from GERD which support the theory that the mechanism of upper GI symptoms after LSG is mainly due to altered motility patterns rather than acid-related disorders. Conclusion Our results show that LSG represents a safe and effective procedure to achieve significant weight loss. GERD which was considered to be a main troublesome impact of LSG showed no significant change in prevalence, on the contrary appear to abolish the symptom in a significant number of patients who complained of GERD.

Several jet pumps with swirling components in the driving jet flow are investigated experimentally for using them in aeration systems. Experimental measurements were carried out for the mixing system model using atmospheric air to increase the dissolved oxygen in tap water under different operating conditions and with four different swirl components. The effects of water temperature, jet pump pressure ratio, and jet pump number are then investigated. The mixing performance is remarkably improved by using a swirling flow compared with the non-swirling cases. This improvement is noticed when the required saturation time is decreased and the gas transfer efficiency is increased. Moreover, the improvement is shown to increased in relation to the swirl intensity used.

Type 304L stainless steel alloy is a main constructional material in many factories for the production of several salts from the hyper saline water. In this water, such that of Lake Quaroun in Fayioum, Egypt, the sole surviving micro-organism is almost the unicellular alga Dunaliella Salina which secretes relatively massive amount of β-carotene. The present investigation deals with the role of this alga as well as its secreted β-carotene on the corrosion and passivation behavior of the 304L steel alloy in hyper saline water and sulphate solutions. The tested β-carotene was extracted from a culture alga solution. Standard biochemical, chemical and electrochemical methods were applied. The results reveal that this compound does not affect the mechanism of the corrosion process but merely decrease its rate by making a physical barrier, indicating that β-carotene acts as an adsorption inhibitor. Various electrochemical measurements were used including open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Analysis of the EIS results based on the dispersion formula approach, allowed estimation of the electrical parameters of the proposed equivalent circuit used to simulate the alloy/passive film/solution system. From the increase of the surface film resistance, the degree of surface coverage has been calculated as a function of the added β-carotene concentration, hence specifying the appropriate adsorption isotherm. The data were found to obey the Temkin adsorption equation.

In jet pumps, energy exchange between the jet and the secondary flow strongly determines its overall efficiency. In this article, the effects of introducing inlet swirling flow in the main jet of liquid jet gas pumps were investigated experimentally. Four different swirl components with degree of swirl covering the weak, moderate, and strong ranges were used. Experimental measurements were carried out on the transparent jet pump model with variable throat length and nozzle spacing under constant jet pump number n. Experimental results are provided concerning the effect of inlet swirl on jet break-up length and compared with the previous results. Good agreement is found between experimental results and theoretical predictions of one-dimensional model.

The open circuit potential, capacitance and resistance techniques were used to investigate the behaviour of two types of surface zirconium oxides in pure 0.5 N H2SO4 and in the presence of additives of K2CrO4, KI, FeSO4 and HCOOH. The air-formed preimmersion oxide film grows in all solutions following a logarithmic rate law. Depending on the nature of the additive the oxide grows directly by oxidation of the surface by the oxidizing additive (K2CrO4) or indirectly by mediating the oxidation by atmospheric oxygen in the presence of reducing additives. Anodically formed zirconium oxide films dissolve in all solutions. The results of impedance measurements indicate that adsorption of HCOOH activates the oxide surface owing, possibly, to its hydrophilic nature while iodide adsorption diminishes the reactivity of active sites (probably oxygen vacanies) where the dissolution process is initiated.

The results of open-circuit potential and impedance measurements show that the dissolution rate of the anodic oxide film on bismuth is dependent on the nature of the dissolving medium. The dissolution rate of the oxide film is found to increase with increasing chromate concentration, particularly the outer layer of the oxide film. The outer layer is more defective than the inner layer because of its contamination by SO 2- 4 anions during anodization in H 2 SO 4 solution. The increase in the dissolution rate with increasing chromate concentration may be attributed to the oxidative type of dissolution of bismuth oxide in chromate solution. Dissolution of bismuth oxide film in solutions containing other electroactive species such as Fe 2+ , HCOOH and I - is also studied. It is found that the dissolution rate of the oxide film decreases in the order CrO 2- 4 (high) > Fe 2+ > HCOOH > I - (low). The dissolution mechanism of the duplex-nature bismuth oxide film follows a zero-order mechanism in all the test solutions.

Study of the chemical stripping of anodic oxide films on hafnium, zirconium, tungsten and aluminium has led to the deduction of the morphology of the respective oxides. Away from the boundary region hafnium oxide is a compact, smooth, homogenous and crystalline oxide. Zirconium oxide has a superficial disorder layer which constitutes about 17% of the entire film. Tungsten oxide deposits are composed of two defective partial layers the outer one being more disordered. Aluminium oxide is a porous film. A schematic representation of each film had been presented.

Lead is corroded by dilute ( 0.4 M) solution, corrosion is inhibited by the formation of ...

A kinetic study on passivation of lead in phosphate media was made by potential and impedance measurements. In pH's > 2.01, the potential gets nobler with time, indicating passivation of the lead electrode. This was confirmed from measurements of the relative change in the thickness of the passive layer which was found to increase with time following a direct logarithmic law. The magnitude of the rate of growth of the layer as well as the discontinuity in this rate were correlated with the mechanism of film growth. Layers grown in the pH range 2.01–4.60 are adherent and thin, whereas those formed in pH's >4.6 are thicker and porous.

An anodic oxide film on tungsten was formed galvanostatically in different acetic acid solutions, current densities, and temperatures. The formation rate of the anodic oxide film was found...

The anodic dissolution of antimony in alkaline phosphate solutions has been investigated by using a galvanostatic technique. The rate of anodic dissolution was found to depend on pH and showed a Tafel slope of 195 mV/decade. The reaction order with respect to OH− was found to approximately equal to one. The dissolution rate of antimony at constant pH value is increased with solution stirring and dissolution temperature. The activation energy ΔH* for the anodic dissolution process was found to be 20.3 kcal ·mol−1·°K− 1. The anion nature affected the anodic dissolution at pH 7.0, while at pH 12 the same anions have no effect. The dissolution rate of antimony is increased with increasing the phosphate ion concentration up to 1.0 N; higher concentration than this value decreased the dissolution.

A kinetic study on passivation of lead in phosphate media was made by potential and impedance measurements. In pH's > 2.01, the potential gets nobler with time, indicating passivation of the lead electrode. This was confirmed from measurements of the relative change in the thickness of the passive layer which was found to increase with time following a direct logarithmic law. The magnitude of the rate of growth of the layer as well as the discontinuity in this rate were correlated with the mechanism of film growth. Layers grown in the pH range 2.01–4.60 are adherent and thin, whereas those formed in pH's >4.6 are thicker and porous.

The open-circuit behaviour of the anodic oxide film on titanium was studied in sulphuric acid and sodium hydroxide solutions by impedance and potential measurements. It was found that the film dissolves in sodium hydroxide and to a lesser extent in sulphuric acid. In both cases the measured capacitance, Cm, increases with time, t, according to Cm−1 = α – βt½ where α and β are coefficients dependent on the test solution. Thefilm was found to be duplex in nature. The outer layer is more defective than the inner one and therefore it is more susceptible to dissolution in both H2SO4 and NaOH.

The passivation behavior of zinc in oxalic/oxalate solutions was studied using impedance and polarization measurements. A passive layer containing zinc oxalate is formed in these oxalate m...

This paper discusses systematically the potential and impedance behavior of the tungsten electrode in buffer solutions. The open circuit corrosion potential of the tungsten electrode decreases by 59 mV/unit increase of pH. Impedance measurements of the corroding tungsten show that the reaction film on the metal deteriorates in acidic buffers, whereas in alkaline ones, the surface gets is polished.

From studies of the chemical dissolution of anodic oxide films on several valve metals, the relative concentration profiles of atomic defects across the films have been deduced. Oxides that are characterized by low energies of defect formation contain relatively high concentrations of defects, this concentration increasing as the oxide grows. Films that are characterized by intermediate energies of defect formation contain lower concentrations of defects, which decrease as the oxide grows, while those oxides that are characterized by high energies of defect formation contain low concentrations of defects, which decrease only insignificantly as the oxide grows. Respective examples of each type are tungsten oxide, titanium oxide, and hafnium oxide.

The corrosion inhibition of zinc in HCl solutions by several pyrazole derivatives—namely, 3(5) amino, 5(3) phenylpyrazole; 3(5) amino, 5(3) [4′—methylphenyl] pyrazole; 3(5) amino, 5(3) [4′...

The currentless dissolution behavior of the anodic oxide films formed on antimony in 0.1N H3PO4 was studied as a function of formation voltages and formation current densities. The dissolution rate of the oxide film was examined as a function of the electrolyte composition of the formation medium. Kinetics curves for the dissolution of the oxide film in most media show a two stage process that seems to be related to the dual nature of the oxide film. The validity of the first order mechanism for the dissolution process is illustrated with the kinetics curves of dissolution following the equation: This equation is used for each of the two stages of the dissolution process, with two different values of K. The rate of the dissolution process was found to be a function of electrolyte composition of the formation medium, while no effect was observed for the initial current density of the oxide formation. The role of anion type on the dissolution rate was more pronounced in acidic solutions than in neutral ones.

The growth of thin oxide films on hafnium immersed in a 0.5N solution of H2SO4, NaOH, and Na2SO4 is studied without permitting an external current to flow. The results indicate the dependence of oxide capacitance on the pH of the electrolyte and surface treatments. Galvanostatic oxide film growth on hafnium has been studied in 0.5N H2SO4. The simple theory of anodization is applied, and data are given for electric field, reciprocal capacity, and prepolarization thickness.

The dissolution behaviour of the anodic oxide film on antimony in phosphate solutions has been studied by impedance and potential measurements. The dissolution rate of the oxide film was found to increase with increase in the pH of the dissolution medium. A plot of the steady state potential values vs pH gave a straight line with a slope of approximately −55 mV/pH. In phosphate solutions of concentrations up to 1 N, the oxide film is completely dissolved with a rate proportional to the phosphate concentration. But in concentrated phosphate solutions (> 1 N), rapid dissolution followed by formation of an oxide film and/or blocking of the dissolving one was observed and finally complete dissolution occurred. The influence of chloride ions on the rate of dissolution of the oxide film in phosphate solution was found to depend on the solution pH. At pH 2 the dissolution rate increased with increasing the Cl− ion concentration whereas at pH 7 the rate decreased.

The corrosion of the anodically formed oxide film on titanium has been studied in HCl solutions after the flow of the forming current ceases. Reciprocal capacitance, resistance, and the op...

A study is made to account for the corrodability of each of the naturally developed and anodically formed oxide films on hafnium in HCl solutions. The behaviour of these oxide films was investigated by capacitance and potential measurements. The naturally developed oxide film grows spontaneously according to a direct logarithmic law. In diluted HCl (

Open-circuit potential and galvanostatic polarisation measurements were made on tungsten in alkaline phosphate solutions. The rate of anodic dissolution of tungsten strongly depended on pH and showed a Tafel slope of 60 mV/decade. The reaction order with respect to OH− was found to be 1. An increase of temperature at constant pH increased the dissolution rate of tungsten, and the activation energy. ∆H*,for the dissolution process wasfound to be 125 kJ/mol.

The open circuit behavior of hafnium at different surface film thicknesses, immersed in 0.5N H2SO4 has been investigated using potential and impedance measurements. When the anodic current is interrupted, a decrease in oxide film thickness (thinning) was attributed mainly to chemical dissolution of the barrier film. A full inertness of the surface is attained when the polarization potential reaches around 25 V (NHE) where the surface film becomes insoluble in the surrounding electrolyte. It was found also that with gradual accumulation of the oxide layer, a pronounced increase of the open circuit potential was observed. At the thickness corresponding to the polarization potential 25 V (NHE), the rate of increase of open circuit potential after cessation of the current becomes very much reduced and thus a perfect, compact, and continuous oxide film was assumed to be formed on the metal surface.

The growth of thin oxide films (2·0–8·0 nm) on hafnium immersed in aqueous buffer solutions of pH 1–12 has been followed by means of capacitance and potential measurements. Capacitance measurements show that the corrosion reaction film exerts an action on the behaviour of the metal, in that it determines the magnitude of the open-circuit corrosion potential.In the early stages of oxide film growth, the potential of the hafnium electrode was found to decrease by 59 mV/unit increase in pH, whereas in the final stages the potential decreased by 20–30 mV/unit increase in pH. The reason for the deviation from the 59 mV/unit increase in pH in the final stages of oxide film growth may be connected lvith non-uniform oxygen supply, or with variation of the conducting properties of the oxidefilm with its thickness.

The behaviour of mechanically polished iridium surfaces was studied in oxygenated aqueous sulphuric acid solutions at 30°C by the open circuit potential technique. The conclusions derived from these measurements were confirmed by determining the dc characteristics of the system. In sulphuric acid solutions more concentrated than 0·5M the pre immersion oxide film grows to become multilayered. The resultant oxide film behaves as a compact film and does not exhibit a reduction peak. In more dilute solutions the preimmersion oxide film appears to hydrate and dissolve. The order of this hydration-dissolution reaction is ~ 1 with respect to the hydroxyl ion.