Arsenite [As(III)] and arsenate [As(V)] are highly toxic inorganic arsenic species that represent a potential threat to the environment and human health. Iron oxides including poorly crystalline oxides, e.g., ferrihydrite, play a significant role in controlling dissolved As concentration and limit the mobility and bioavailability of As(III) and As-(V). Adsorption occurs by ligand exchange of the As species for OH 2 and OHin the coordination spheres of surface structural Fe atoms. The objective of this study was to evaluate H + /OHrelease stoichiometry and changes in surface charge properties of the adsorbent during the adsorption of arsenite and arsenate on ferrihydrite in the pH range of 4-10. This information, which is not directly accessible through spectroscopic studies, provides important clues to bonding mechanism. While arsenate adsorption resulted in the net release of OHat pH 4.6 and 9.2, arsenite adsorption resulted in net OHrelease at pH 9.2 and net H + release at pH 4.6. The amount of H + or OHrelease per mole of adsorbed As varied with the As surface coverage, indicating that different mechanisms of arsenic adsorption predominate at low versus high coverage. The experimentally observed surface charge reduction and net OHrelease stoichiometry were compared with the theoretical stoichiometry of the surface adsorption reactions that might occur. The results provide evidence that during arsenite adsorption at low pH, i.e., pH 4.6, the oxygen of the Fe-O-As bond remained partially protonated as Fe-O(H)-As. There is evidence that the monodentate bonding mechanism might play an increasing role during arsenate adsorption on ferrihydrite with increasing pH (at pH > 8). The results of this study have provided ancillary evidence to support the experimentally observed reduced adsorption of arsenite at low pH and of arsenate at high pH.

The competitive adsorption of arsenate and arsenite and the effect of phosphate and sulfate on adsorption of arsenate and arsenite by ferrihydrite were investigated in the pH range of 3 to 10 and at varying initial ligand concentrations. In dual anion systems, arsenate retention was greater at low pH compared with greater arsenite retention at high pH. In systems with arsenate and arsenite concentrations ≤2.08 molAs kg−1fer each, the effect of arsenate on arsenite sorption was more pronounced than vice versa. On the contrary, at arsenate and arsenite concentrations of 3.47 molAs kg−1fer each, arsenate did not influence arsenite sorption but arsenite substantially reduced arsenate adsorption. The different sorption behavior of arsenite at low and high arsenite concentrations might be due to surface polymerization of adsorbed arsenite at high concentrations. The presence of phosphate resulted in a significant reduction in arsenate and arsenite adsorption by ferrihydrite, with strong dependence on pH and phosphate concentration. The effect of phosphate on arsenate adsorption was greater at high pH than at low pH, whereas the opposite trend was observed for arsenite. Results indicated that arsenate and phosphate compete for the same surface sites, with a moderate preference for arsenate adsorption. There was evidence of the presence of some surface sites that exhibited much higher affinity for arsenite than phosphate. The presence of sulfate did not influence arsenate adsorption but resulted in a considerable reduction in arsenite adsorption below pH 7.0, with the largest reduction at the lowest pH.

A multicountry outbreak of the monkeypox virus has gained global attention. As of May 25, 250 confirmed human monkeypox cases have been reported globally. Monkeypox is caused by the Monkeypox virus, which belongs to the Orthopoxvirus genus and Poxviridae family. Monkeypox is often a self‐limiting infection, with symptoms lasting 2–4 weeks with the case fatality ratio around 3%–6%. Monkeypox is transmitted to humans by direct contact with an infected person or animal or contact with virus‐contaminated material. Human monkeypox infections may lead to various medical complications such as fever, rash, and lymphadenopathies. Pneumonitis, encephalitis, sight‐threatening keratitis, and subsequent bacterial infections are all possible complications of monkeypox. An antiviral agent developed to treat smallpox has also been approved for use in the treatment of monkeypox in the United States. Vaccines used in the smallpox eradication program also provided immunity to monkeypox. Newer vaccines have been developed, one of which has been approved for monkeypox prevention. In this study, we provide information about the recent outbreaks of human monkeypox, epidemiology, transmission pattern, possible diagnosis techniques, therapeutics, and available preventive strategies.

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Ventilator Associated Pneumonia (VAP), the nosocomial pneumonia developing in mechanically ventilated patients after 48 hours of mechanical ventilation, is the second most common nosocomial infection. Therefore, there is a vital need to study the etiology and risk factors associated with VAP in neonates. Neonates admitted to neonatal intensive care unit (NICU), over a period of 1 year and who required mechanical ventilation for more than 48 hours were enrolled consecutively into the study. Diagnosis of VAP was made by the guidelines given by National Nosocomial infection Surveillance System (NNIS, 1996). Semi-quantitative assay of endotracheal aspirate was used for microbiological diagnoses of VAP. 10 5 CFU/ml was taken as the cut off between evidence of pathological infection and colonization. The risk factors such as birth weight, prematurity (gestational age < 37 weeks), duration of mechanical ventilation, number of reintubations, length of hospital stay, primary diagnosis of neonate, postnatal age and small for gestational age (SGA) were studied for the development of VAP. Risk factors found significant on bivariate analysis were subjected to multiple regression analysis to determine the most important predictors of VAP. The study group comprised of 98 neonates out of which, 30 neonates developed VAP (30.6%). VAP rates were 37.2 per 1000 days of mechanical ventilation. Most common bacterial isolated from endotracheal aspirate of VAP patients was Klebsiella spp (32.8%), E.coli (23.2%) and Acinetobacter (17.8%) being the other two common organisms. Very low birth weight (<1500 grams), prematurity (gestational age < 37 week), duration of mechanical ventilation, number of reintubations and length of NICU stay were significantly associated with VAP in bivariate analysis. Multiple regression analysis revealed that duration of mechanical ventilation (OR 1.10, 95% CI 1.02, 1.21; P = 0.021) and very low birth weight (OR 3.88, 95% CI 1.05, 14.34; P = 0.042) were two single independent and statistically significant risk factors for predicting VAP. VAP developed in nearly one third of intubated neonates having gram negative organisms as predominant etiological agent.

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