No abstract

Background: Critically ill patients with COVID-19 are prone to develop severe acute kidney injury (AKI), defined as KDIGO (Kidney Disease Improving Global Outcomes) stages 2 or 3. However, data are limited in these patients. We aimed to report the incidence, risk factors, and prognostic impact of severe AKI in critically ill patients with COVID-19 admitted to the intensive care unit (ICU) for acute respiratory failure. Methods: A retrospective monocenter study including adult patients with laboratory-confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection admitted to the ICU for acute respiratory failure. The primary outcome was to identify the incidence and risk factors associated with severe AKI (KDIGO stages 2 or 3). Results: Overall, 110 COVID-19 patients were admitted. Among them, 77 (70%) required invasive mechanical ventilation (IMV), 66 (60%) received vasopressor support, and 9 (8.2%) needed extracorporeal membrane oxygenation (ECMO). Severe AKI occurred in 50 patients (45.4%). In multivariable logistic regression analysis, severe AKI was independently associated with age (odds ratio (OR) = 1.08 (95% CI (confidence interval): 1.03–1.14), p = 0.003), IMV (OR = 33.44 (95% CI: 2.20–507.77), p = 0.011), creatinine level on admission (OR = 1.04 (95% CI: 1.008–1.065), p = 0.012), and ECMO (OR = 11.42 (95% CI: 1.95–66.70), p = 0.007). Inflammatory (interleukin-6, C-reactive protein, and ferritin) or thrombotic (D-dimer and fibrinogen) markers were not associated with severe AKI after adjustment for potential confounders. Severe AKI was independently associated with hospital mortality (OR = 29.73 (95% CI: 4.10–215.77), p = 0.001) and longer hospital length of stay (subhazard ratio = 0.26 (95% CI: 0.14–0.51), p < 0.001). At the time of hospital discharge, 74.1% of patients with severe AKI who were discharged alive from the hospital recovered normal or baseline renal function. Conclusion: Severe AKI was common in critically ill patients with COVID-19 and was not associated with inflammatory or thrombotic markers. Severe AKI was an independent risk factor of hospital mortality and hospital length of stay, and it should be rapidly recognized during SARS-CoV-2 infection.

No abstract

No abstract

This study investigated the applicability of natural Egyptian Na-montmorillonite (Na-MMT) to remove Pb 2+ , Cd 2+ and Ni 2+ under acidic conditions that mimic industrial wastewater acidity. Cation exchange capacity of Na-MMT was found 91 meq/100 g and the specific surface area 42 m 2 g À1 . The adsorbent was characterized using X-ray fluorescence, scanning electron micrograph that showed significant morphological changes after adsorption and Fourier transform infrared spectroscopy, which confirmed that the adsorption occurred mainly in the lattice region. Removal efficiency was evaluated as a function of pH, contact time, initial concentration, and adsorbent mass. Acidic pH value was chosen for the following experiments. Langmuir and Freundlich isotherm models were applied. Freundlich model showed better fitting suggesting heterogeneous adsorption scenario. Freundlich capacity values decreased in the order of Pb 2+ (3.71 mg g À1 ) > Cd 2+ (2.45 mg g À1 ) > Ni 2+ (1.76 mg g À1 ). Kinetic data were accurately fitted to pseudo-second-order, indicating the adsorption occurrence in the interior surface of Na-MMT and the contribution of internal diffusion mechanism was significant. Intraparticle diffusion model gave multi-linear curves so more than onestep controlled the adsorption process. Under temperature range 290-328 K, thermodynamic parameters revealed that adsorption of Pb 2+ and Cd 2+ was spontaneous but Ni 2+ non-spontaneous. Adsorption was exothermic for Pb 2+ and Ni 2+ but endothermic for Cd 2+ . Arrhenius activation energy values were 5.78, 8.51 and 11.45 kJ mol À1 for Pb 2+ , Cd 2+ and Ni 2+ respectively stating the physical adsorption. Na-MMT reusability was confirmed by regeneration experiments. Application study showed excellent efficiency of Na-MMT within range (23.4-81.2%) removal for Pb 2+ , Cd 2+ and Ni 2+ from textile dyeing and tannery wastewater. *Effect of pH was studied in the pH range 2-7 while keeping other parameters constant at 't = 60 min; C o = 10 mg L À1 ; adsorbent mass = 0.25 g; agitation speed = 100 rpm and T = 298 K'.A. A. TAHA ET AL. Figure 6. Effect of adsorbent mass 'adsorbent mass (0.12-0.500) g, t = 60 min, pH = 3.8, C o = 10 mg/L, agitation speed = 100 rpm and T = 298 K'.Figure 7. Linearized isotherm models (a) Langmuir model and (b) Freundlich model. 'C o = (5-30) mg/L, t = 60 min, pH = 3.8, adsorbent mass = 0.25 g, agitation speed = 100 rpm and T = 298 K'.Figure 8. The linear plots of the pseudo-second-order model for (a) Pb +2 , (b) Cd +2 and (c) Ni +2 . 'C o = (5-20) mg/L, t = (1-60) min, pH = 3.8, adsorbent mass = 0.25 g, agitation speed = 100 rpm and T = 298 K'.Figure 9. Intraparticle diffusion plots for (a) Pb +2 , (b) Cd +2 , and (c) Ni +2 . 'C o = (5-20) mg/L, t = (1-60) min, pH = 3.8, adsorbent mass = 0.25 g, agitation speed = 100 rpm and T = 298 K'.

No abstract

No abstract

The rate of copper dissolution in the presence of phosphoric acid‐alcohol mixtures was studied by measuring the limiting current density which represents that the rate of electropolishing is decreased by increasing phosphoric acid concentration, electrode height, and mole fraction of alcohol. Thermodynamic parameters are calculated. The rotating disk electrode is being used as a tool to study the influence of organic solvent addition on the rate of electropolishing of copper. Different reaction conditions such as temperature, speed of rotation of copper disk, the physical properties of solution are studied to obtain a dimensionless correlation between all these parameters. The data can be correlated by the following equations: Sh = 1.835 (Sc)0.33 (Re)0.36 (for ethylene glycol) Sh = 1.25 (Sc)0.33 (Re)0.5 (for glycerol) It is obvious that the exponent in the two cases denotes a laminar flow mechanism.