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.