Selective oxidative dehydrogenation of propane to propene using boron nitride catalysts.

The exothermic oxidative dehydrogenation of propane reaction to generate propene has the potential to be a game-changing technology in the chemical industry. However, even after decades of research, selectivity to propene remains too low to be commercially attractive because of overoxidation of propene to thermodynamically favored CO2 Here, we report that hexagonal boron nitride and boron nitride nanotubes exhibit unique and hitherto unanticipated catalytic properties, resulting in great selectivity to olefins. As an example, at 14% propane conversion, we obtain selectivity of 79% propene and 12% ethene, another desired alkene. Based on catalytic experiments, spectroscopic insights, and ab initio modeling, we put forward a mechanistic hypothesis in which oxygen-terminated armchair boron nitride edges are proposed to be the catalytic active sites.

Evaluation of the Chemstrip 9 as a screening test for urinalysis and urine culture in men.

The Chemstrip 9 (Biodynamics, Inc., Indianapolis, IN) was evaluated as a rapid screening method for urinalysis and quantitative urine culture. Of 469 urine specimens, 224 had an abnormal microscopic examination compared to 211 with an abnormal Chemstrip 9 (i.e., leukocyte esterase, nitrite, protein, or blood). The sensitivity and specificity of the dipstick test were 94.2% and 65.7%, respectively, while the predictive values of a positive and negative test were 71.5% and 92.5%, respectively. A total of 459 urine specimens were quantitatively cultured and tested by the Chemstrip 9. Either one or more tests (i.e., leukocyte esterase, nitrite, protein, or blood) were positive in 91.3% of the 115 specimens with greater than or equal to 10(5) CFU/mL. The specificity was 43.6% and the predictive values of a positive and negative test were 35.1% and 93.8%, respectively. When the criterion for a positive test was greater than or equal to 10(4) CFU/mL, the sensitivity and specificity were 86.8% and 45.5%, respectively. In contrast, the gram-stained smear of unspun urine was positive in 107 (93.0%) of specimens containing greater than or equal to 10(5) CFU/mL and in 115 (76.2%) of specimens with greater than or equal to 10(4) CFU/mL. Only 9 (2.9%) of 308 specimens with less than or equal to 10(3) CFU/mL had a positive Gram smear.