Kinetic modelling assisted balancing of organic pollutant removal and bromate formation during peroxone treatment of bromide-containing waters.

The peroxone process (O3/H2O2) is reported to be a more effective process than the ozonation process due to an increased rate of generation of hydroxyl radicals (•OH) and inhibition of bromate (BrO3-) formation which is otherwise formed on ozonation of bromide containing waters. However, the trade-off between the H2O2 dosage required for minimization of BrO3- formation and effective pollutant removal has not been clearly delineated. In this study, employing experimental investigations as well as chemical modelling, we show that the concentration of H2O2 required to achieve maximum pollutant removal may not be the same as that required for minimization of BrO3- formation. At the H2O2 dosage required to minimize BrO3- formation (<10 µg/L), only pollutants with high to moderate reactivity towards O3 and •OH are effectively removed. For pollutants with low reactivity towards O3/•OH, high O3 (O3:DOC>>1 g/g) and high H2O2 dosages (O3:H2O2 ∼1 (g/g)) are required for minimizing BrO3- formation along with effective pollutant removal which may result in a very high residual of H2O2 in the effluent, causing secondary pollution. On balance, we conclude that the peroxone process is not effective for the removal of low reactivity micropollutants if minimization of BrO3- formation is also required.

Heterogenous Iron Oxide Assemblages for Use in Catalytic Ozonation: Reactivity, Kinetics, and Reaction Mechanism.

Heterogeneous catalytic ozonation (HCO) has gained increasing attention as an effective process to remove refractory organic pollutants from industrial effluents. However, widespread application of HCO is still limited due to the typically low efficacy of catalysts used and matrix passivation effects. To this end, we prepared an Al2O3-supported Fe catalyst with high reactivity via a facile urea-based heterogeneous precipitation method. Due to the nonsintering nature of the preparation method, a heterogeneous catalytic layer comprised of γ-FeOOH and α-Fe2O3 is formed on the Al2O3 support (termed NS-Fe-Al2O3). On treatment of a real industrial effluent by HCO, the presence of NS-Fe-Al2O3 increased the removal of organics by ∼100% compared to that achieved with a control catalyst (i.e., α-Fe2O3/Al2O3 or γ-FeOOH/Al2O3) that was prepared by a conventional impregnation and calcination method. Furthermore, our results confirmed that the novel NS-Fe-Al2O3 catalyst demonstrated resistance to the inhibitory effect of high concentration of chloride and sulfate ions usually present in industrial effluent. A mathematical kinetic model was developed that adequately describes the mechanism of HCO process in the presence of NS-Fe-Al2O3. Overall, the results presented here provide valuable guidance for the synthesis of effective and robust catalysts that will facilitate the wider industrial application of HCO.

Helicobacter pylori acquisition rates and the associated risk factors amongst newlywed couples; a prospective cohort study in Tehran, Iran.

BACKGROUND: The rates and routes of Helicobacter pylori transmission, in a high-prevalent country like Iran, with gastric cancer as the leading cause of male cancer mortality, are of great essence. Here, we have studied the H. pylori-associated risk factors and the likelihood of interspousal transmission. METHODS: In a cohort of 686 young prewed couples, questionnaires were self-administered and serum samples were collected, for assessment of risk factors and H. pylori serostatus, at baseline and follow-up. Of the 475 H. pylori single- or double-seronegative couples, 201 returned for follow-up. The average follow-up duration was 2.2 (SD 0.6) years, with a total of 560.1 person-years. Logistic regression and Cox regression models were used to estimate the odds ratios (ORs) and hazard ratios (HRs). RESULTS: The risk of infection was higher in men than women (OR: 1.3, 95% CI: 1.0-1.8) and among metropolitan than rural residents (OR = 1.4, 95% CI: 1.1-1.9). It was also significantly higher among those with three (OR = 1.6, 95% CI: 1.1-2.2), and four or more siblings (OR = 1.4, 95% CI: 1.0-1.9), in reference to those with one or no siblings. Adult H. pylori acquisition occurred in 10.9% (27/247) of the seronegative participants. The risk of the acquisition was significantly associated with age (P value for trend=0,000). It was also significantly lower among participants who had various degrees of education as compared to illiterate subjects (HR = 0.2, 95% CI: 0.1-0.9). Nevertheless, our analysis did not find any evidence for interspousal transmission (HR = 1.0, 95% CI: 0.4-2.2). CONCLUSION: Whilst H. pylori acquisition was detected in the young adult Iranian population, our findings did not support interspousal transmission, as a mode of acquisition.

A Promising Modified Procedure for Upper Eyelid Retraction-Associated Graves' Ophthalmopathy: Transconjunctival Lateral Levator Aponeurectomy.

Upper eyelid retraction is a characteristic feature of thyroid eye disease, including Graves' orbitopathy. In this study, a new surgical technique for correction of lid retraction secondary to Graves' orbitopathy is described. Sixteen eyelids of patients older than 18 years old underwent surgical correction for moderate to severe lid retraction secondary to Graves' orbitopathy. In this procedure, levator aponeurectomy was performed via a transconjunctival approach. Upper marginal reflex distance (MRD1) was measured before the surgery and at 1 week, 3 months, and 6 months after the surgery. MRD1 was reduced significantly from preoperatively (mean: 7.84 mm) to 1 week after the surgery (mean: 3.59 mm) (P < 0.001). Three and six months after surgery, mean MRD1 was 5.09 mm and 5.10 mm, respectively, showing that lid retraction was improved significantly (P < 0.001). Lateral levator aponeurectomy via the transconjunctival approach is a simple, scar-less, quick procedure that has optimal stable outcome.