Insights into sunlight-driven transformation of tetracycline by iron (hydr)oxides: The dominating role of self-generated hydrogen peroxide.

Iron (hydr)oxides are abundant in surface environment, and actively participate in the transformation of organic pollutants due to their large specific surface areas and redox activity. This work investigated the transformation of tetracycline (TC) in the presence of three common iron (hydr)oxides, hematite (Hem), goethite (Goe), and ferrihydrite (Fh), under simulated sunlight irradiation. These iron (hydr)oxides exhibited photoactivity and facilitated the transformation of TC with the initial phototransformation rates decreasing in the order of: Hem > Fh > Goe. The linear correlation between TC removal efficiency and the yield of HO• suggests that HO• dominated TC transformation. The HO• was produced by UV-induced decomposition of self-generated H2O2 and surface Fe2+-triggered photo-Fenton reaction. The experimental results indicate that the generation of HO• was controlled by H2O2, while surface Fe2+ was in excess. Sunlight-driven H2O2 production in the presence of the highly crystalline Hem and Goe occurred through a one-step two-electron reduction pathway, while the process was contributed by both O2-induced Fe2+ oxidation and direct reduction of O2 by electrons on the conduction band in the presence of the poorly crystalline Fh. These findings demonstrate that sunlight may significantly accelerate the degradation of organic pollutants in the presence of iron (hydr)oxides.

The Preparation of an Ultrafine Copper Powder by the Hydrogen Reduction of an Ultrafine Copper Oxide Powder and Reduction Kinetics.

Ultrafine copper powders were prepared by the air-jet milling of copper oxide (CuO) powders and a subsequent hydrogen (H2) reduction. After milling, the particle size and grain size of CuO powders decreased, while the specific surface area and structural microstrain increased, thereby improving the reaction activity. In a pure H2 atmosphere, the process of CuO reduction was conducted in one step, and followed a pseudo-first-order kinetics model. The smaller CuO powders after milling exhibited higher reduction rates and lower activation energies compared with those without milling. Based on the unreacted shrinking core model, the reduction of CuO powders via H2 was controlled by the interface reaction at the early stage, whereas the latter was limited by the diffusion of H2 through the solid product layer. Additionally, the scanning electron microscopy (SEM) indicated that copper powders after H2 reduction presented a spherical-like shape, and the sintering and agglomeration between particles occurred after 300 °C, which led to a moderate increase in particle size. The preparing parameters (at 400 °C for 180 min) were preferred to obtain ultrafine copper powders with an average particle size in the range of 5.43-6.72 µm and an oxygen content of less than 0.2 wt.%.

Severe community-acquired pneumonia caused by Leptospira interrogans: A case report and review of literature.

BACKGROUND: Leptospira is an uncommon pathogen for adult severe community-acquired pneumonia and its nonspecific manifestations and limited diagnostic tests make it difficult to identify. Although conventional penicillin remains efficacious to treat leptospirosis, failure in early diagnosis and treatment can lead to progression into a deadly syndrome with multiple organ dysfunction. Next generation sequencing is of great value to understand cases with infection of unknown cause, which could help in the diagnosis of uncertain Leptospira infection. CASE SUMMARY: We recently managed a patient with fever, cough and dyspnea on admission that progressed into persistent adult respiratory distress syndrome, hemoptysis and hematuria after admission. In this case, the rare Leptospira infection was clouded by the positive influenza tests at admission, delaying early Leptospira-targeted antibiotics administration. Next generation sequencing, a novel molecular diagnostic tool, provided a key hint to uncover the crucial pathogen, Leptospira interrogans, further supported by the possible occupational exposure history. Subsequent conventional penicillin and mechanical respiratory support were administrated to cure the patient successfully without any sequela. CONCLUSION: Clinicians must pay attention to possible exposure history and keep uncommon Leptospira in mind when managing pneumonia with unknown causes.