Role of phosphoric acid on the corrosion performance of Pb-1.7%Sb gridof lead-acid batteries

The corrosion behavior of a commercial Pb-1.7% Sb gridof lead-acid batteries under open circuit conditions in 5M H 2SO4 in the presence of phosphoric acid is studiedby electrochemical impedance spectroscopy and cyclicvoltammetry. Dependence of corrodibility of the alloy onH 3PO4 concentration is weak up to 0.7M. After days ofcorrosion, the corrosion rate in the presence of H 3PO4 isslightly higher than in its absence, due to retardation of the growth of an insulating PbSO 4 layer that acts as an effective diffusion barrier of the corrosive species. The electronic and diffusion properties of the passive layer formed in the presence of H 3PO4 are substantially inferior. Cyclic voltammetry indicates a decrease in amounts of PbSO 4 and Sb 2O3 formed in the presence of H3PO4 and with increasing its concentration. Also, the amount of PbO formed beneath the PbSO 4 layer increases with increasing H3PO4 concentration on the expense of the amount of PbSO 4

Electrochemical Performance of Grids of Lead-acid Batteries made from Pb-0.8%Ca-1.1%Sn Alloys Containing Cu, As and Sb Impurities in the presence of phosphoric acid

Electrochemical performance of grids of lead-acid Batteries manufactured from Pb-0.8%Ca-1.1%Sn alloys containing Cu, As and Sb impurities at 0.1 wt% level were studied in 4.0 M H2SO4 without and with 0.4 M H3PO4. The presence of impurities in the alloy or addition of H3PO4 was found to suppress the corrosion rate. H3PO4 increased the rates of both hydrogen and oxygen evolution reactions at high overpotentials for all alloys. Except for Cu-containing alloy, H3PO4 had a slight positive effect on PbO2 formation.The self-discharge of PbO2 under polarization or opencircuitconditions increased in the presence of H3PO4 but the positive grid corrosion decreased, except for the As-containing alloy. Impurity-containing alloys showed significantly lower self-discharge rate in the presence of H3PO4 than in its absence. Impedance measurement was able to detect and quantify the formation of the highly insulating inner PbO layer beneath the outer PbSO4 layer and its transformation to the conducting PbO2, during the oxidation of alloys under constant current conditions.H3PO4 significantly enhanced the formation of PbO in thepresence of impurities, especially Sb

Serial changes in the serum levels of leptin, homocysteine, galectin-3, total phospholipids and hexosamines among patients undergoing coronary artery bypass grafting

AbstractBackgroundCoronary artery disease (CAD) is the most common cardiovascular disorder in adults. This study was performed to elucidate the role of active leptin, homocysteine, galectin-3, total phospholipids, total, bound, free hexosamines, free-to-bound hexosamines ratio in the pathogenesis of chronic myocardial ischemia and studying the effect of coronary artery bypass grafting (CABG) on their serum levels.MethodsA prospective case control study was carried out on 100 ischemic heart disease male patients undergoing elective CABG and 25 healthy males. Serum levels of total phospholipids, total and free hexosamines, were estimated using spectrophotometric methods, while, serum levels of active leptin, homocysteine and galectin-3 were estimated using ELISA assay kit.ResultsSignificant higher serum active leptin, homocysteine, galectin-3, free hexosamines and free to bound hexosamines ratio levels preoperatively when compared with the control group (p < 0.01 for all) with significant lowering of their serum levels following CABG (p < 0.01 for all) except for active leptin. Significant lower serum total phospholipids, total and bound hexosamines levels preoperatively when compared with the control group (p < 0.01 for all) with significant elevations in their serum levels following CABG (p < 0.01 for all).ConclusionsHigh active leptin, homocysteine, galectin-3, free and free to bound hexosamines ratio and low total phospholipids, total and bound hexosamines play an important role in the pathogenesis of myocardial ischemia. The serum levels of homocysteine, galectin-3, hexosamines and total phospholipids, but not active leptin are significantly lowered following CABG

Analgesic efficacy and safety of peri-operative pregabalin following radical cystectomy: A dose grading study

AbstractPurposeAdding novel drugs like pregabalin to analgesic regimens might reduce postoperative pain, total opioid consumption and side effects, this study compares multiple doses of pregabalin for postoperative analgesia following radical cystectomy.MethodsThis study is registered at www.clinicaltrials.gov at no.: NCT02724293. Sixty patients were randomized into 4 groups: Group I: control (placebo) group, Group II: received pregabalin 300mg 2h preoperatively, Group III: received pregabalin 300mg 2h preoperatively and 12h thereafter, Group IV: received pregabalin 600mg 2h preoperatively. Postoperative pain, time to first request of analgesia, and total morphine consumption were recorded.ResultsVAS was significantly reduced in groups II, III, IV in comparison with group I immediately postoperative, and after 2h (P<0.05). Sedation score was significantly higher in groups II, III, IV compared to group I immediately postoperative (P<0.05). First request of analgesia was significantly delayed in groups II, III, IV compared to control group (P=0.000). Total analgesic consumption was significantly reduced in groups II, III, IV compared to group I (P=0.000). Group IV showed a significantly higher incidence of dizziness compared to group I.ConclusionPeri-operative pregabalin at doses of 300mg and 600mg reduced postoperative opioid consumption and prolonged time to first request of analgesia in patients who underwent radical cystectomy, and a single preoperative dose of 600mg is superior in analgesia to others, without serious side effects

Effect of Triple Treatment on the Surface Structure and Hardness of 304 Austenitic Stainless Steel

Nitriding, annealing, and carbonitriding processes are conducted to modify the surface of AISI 304 austenitic stainless steel via radio frequency plasma. A ~20 μm thick nitride layer is obtained in ten minutes at a plasma power of 450 W. Hence, all nitrided samples are annealed under vacuum for one hour at 400 ̊C. The nitrided-annealed samples are carbonitrided via the identical technique at various C2H2/N2 gas pressure ratios. Numerous analytical techniques, including X-ray diffractometry, glow discharge optical spectroscopy (GDOS), Talysurf Intra Profilemeter, optical microscopy (OM), scanning electron microscopy (SEM), and Vickers microhardness tester, were employed to investigate the triple-treated specimens. Microstructure analysis of the triple-treated samples reveals the formation of N2 expanded austenite phase (γN), γʹ-Fe4N, CrN, Fe3C, and Fe7C3. The results indicate that the elemental composition, microhardness, and thickness of the triple-treated layers are all depending on the gas composition. After carbonitriding, the total thickness of the compound layer grew from ~20 to ~34.5 μm. The surface microhardness of the triple-treated samples increased as the C2H2/N2 gas composition ratio increased up to 70%, reaching 1,497±33.5 HV0.1, which is ~6.8 and ~1.42 folds higher than the untreated and prenitrided samples, respectively

Effect of Using Hybrid Nano-Particles on Physical and Mechanical Properties of Cement Mortar

This research evaluates the addition of graphene sheets and hybrid nano-materials (graphene with different nano-materials like nano-silica or nano-clay) on compressive strength, flexural strength and thermal conductivity of cement mortar. Graphene sheets were added in three percentages (0.04%, 0.05%, and 0.06%) and (0.03%, 0.04%, and 0.05%) graphene sheets with 1%nano-silica or with 5% nano-clay by weight of cementitious materials. For all specimens, w/c ratio 0.4was applied. Scanning Electron Microscope and thermal conductivity tests were also performed on the optimum specimens at age 28 days. Results indicated that the optimum dose of graphene sheets was 0.05% by weight where the compressive strength, the flexural strength were improved by 35.66%  and 33.33%  respectively, and low thermal conductivity by 6.36% at age 28 days .No significant increase in compressive and flexural strength on adding  hybrid nano-materials (graphene sheets with 1%nano- silica) to mortar. Also reduction effect in compressive and flexural strengths was achieved on adding hybrid nano-materials (graphene sheets with 5% nano-clay) to mortar.  High thermal conductivity was obtained at age 28 days with respect to control ones when hybrid nano-materials were added to cement mortar

Mycobacterial CYP121 as a target for anti-TB drug discovery

Despite the introduction of the first line treatment regimen forty years ago and the continuous trials since that time to introduce new regimens, tuberculosis (TB) is considered to be the cause of considerable mortality worldwide. Recent research highlighted the Mycobacterium tuberculosis (Mtb)CYP450s as potential drug targets. This article reviews mycobacterial CYP121 as a target for anti-TB drug discovery

Effect of Nano-Silica on The Thermo-Physical Properties of the Thermal Eutectic (Na0.6K0.4)NO3 System

Here, we investigate the effect of adding nano-silica particles on the thermo-physical properties of the (Na0.6K0.4)NO3 based thermal energy storage systems. Five different systems tagged as M00, M01, M02, M03 and M04, with different nano-silica percentage of 0, 1, 2, 3, and 4 wt%, respectively, were prepared. Various experimental techniques were employed to study the thermo-physical properties of the systems during (solid-solid) phase P1, (solid-liquid) phase P2 and (liquid-solid) phase P3, and to clarify the effect of nano-silica on the thermal energy storage efficiency during both charging and discharging processes. According to the Differential Scanning Calorimeter (DSC) thermal analysis, it was found that the system M02 whose nano-silica addition rate of 2 wt%, has the most favorable thermal characteristics (i.e., highest specific heat and lowest enthalpy change). Moreover, the addition of 2 wt% represents the optimum distribution of nano-silica inside the principal base system M00. This leads to an improvement in the porosity of the system due to the degree of homogeneity caused by the thermophoresis effect distribution, the high surface area of the nano-silica with the activity of the M00 matrix alongside the degree of the alkalinity of nano-silica. Besides, the electric conductivity measurements showed that the 2wt% percentage is the optimum one for thermal energy storage systems

Shallow subsurface structures and geotechnical characteristics of Tal El-Amarna area, middle Egypt

Abstract The shallow seismic refraction profiling was carried out at 18 sites in Tal El-Amarna, which is a flat area on the eastern bank of the Nile River, 50 km south of El Minia Governorate, middle Egypt. The collected data are used to estimate the P-wave velocity and to delineate the near-surface ground model beneath the study area. This study is supported by the National Research Institute of Astronomy and Geophysics due to the historical interest of the Tal El-Amarna area as a famous tourist place where there exist many Pharaoh temples and tombs. This area is low seismically active, but it is probably of high vulnerability due to the influence of the local geological conditions on earthquake ground motion, as well as the presence of poor constructions in the absence of various issues such as building designs, quality of building materials, etc. Another dataset at the study area is obtained by multi-channel passive source (microtremor) measurements, which have been recorded at four arrays. The frequency–wavenumber (f–k) method was used to derive the dispersion curves from the raw signals at each array. The resulted dispersion curves were inverted using the neighborhood algorithm to obtain the shear and P-wave velocity models. The concluded Vs and Vp values provide a preliminary estimation of the geotechnical parameters and site classification for the shallow soil as they are of great interest in civil engineering applications

Nano Sized Moringa oleifera an Effective Strategy for Pb(II) ions Removal from Aqueous Solution

Nano-sized  Moringa oleifera is considered an effective   biosorbent  with  high surface area from agricultural waste, low coast and environment-friendly which can be used for removal of  Pb2+ from waste water. Thus our study stem to investigate the ability of natural nano-sized biosorbents for removing  very toxic Pb2+ ions from aqueous solution. The investigated biosorbent (Moringa oleifera) was characterized by FTIR, SEM, TEM, XRD and EDX techniques. Moreover, the influence of pH, temperature, adsorbent dosage, contact time and initial metal ion concentration on adsorption process were investigated. The maximum biosorption capacities (qm) of Pb2+ ions by Moringa oleifera was 37.9 mg/g. The lowest biosorption was observed (61.4%) for Pb2+ ions at pH 2.0 while the highest one (94.36%) at pH 5. The optimum contact time for the adsorption process was found to be at 60 minutes. The amount of Pb2+ ions adsorbed increases with increasing in initial metal ion concentration. Moreover, biosorption capacity (qe) and removal efficiency of Pb2+ ions solutions increase as temperature increases. FT-IR data indicated that the adsorption of metal ions occurs on the surface of Moringa oleifera powder as the main functional groups that are responsible for metal ions binding are involved in the process. Furthermore, Thermodynamic studies confirmed that the biosorption process was endothermic and the positive value of ΔG° is quite common when an ion-exchan­­ge mechanism applies in the biosorption. The Positive value of ΔS◦ suggested an increase in randomness during the biosorption. The kinetics study of sorption indicates that the pseudo second-order model provides better correlation of the sorption data (R2=0.99) than the pseudo first-order model (R2 = 0.91), confirming the chemisorption of metal ions solutions on Moringa oleifera. The Freundlich isotherm has agood fit with the experimental data (R2 close to 1) compared to Langmuir isotherm (R2=0.99). This study shows that Moringa oleifera are available, low cost, effective and environment friendlly biosorbent for the removal of Pb2+ ions from aqueous environment. Keywords: Lead, biosorption, Thermodynamics, kinetics, removal efficiency, Moringa oleifera, isother