Abstract Burley tobacco-leaf protein extracted by alkali and precipitated by acid was hydrolyzed enzymatically, and optimum protease and hydrolysis parameters were determined. Pepsin was best and gave the highest hydrolysis rate (15.55%). As per results of the single-factor test, optimum hydrolysis conditions were: temperature 37 °C, pH 2, and an [E]/[S] ratio of 5%. These hydrolysis conditions were optimized by an orthogonal experiment that rendered the same results as the single factor experiment. The ratio of essential to total amino acids and that of essential to non-essential amino acids contained in the burley tobacco-leaf protease hydrolysate were higher than the FAO/WHO standard values of 0.4 and 0.6, among which hydrophobic amino acid content was the highest, followed by negatively and positively charged amino acid contents. In vitro antioxidant experiments showed that the scavenging rates of DPPH, superoxide anion, and hydroxyl radicals of tobacco-leaf protein hydrolysates were higher than those before hydrolysis. Further, the hydroxyl radical-scavenging rate was the most significant, and total antioxidant capacity was improved. The nutritive value of the burley tobacco-leaf protein hydrolysate improved upon pepsin-mediated hydrolysis, and the antioxidant activity was better. These results provide a theoretical basis for further development and utilization of tobacco protein resources.

Abstract Introduction: The evaluation of extracorporeal membrane oxygenation-related nosocomial infection (ECMO-related NI) in a homogeneous cohort remains scarce. This study analyzed ECMO-related NI in adult patients who have undergone cardiac surgery. Methods: From January 2012 to December 2017, 322 adult patients who have received ECMO support after cardiac surgery were divided into the infection group (n=131) and the non-infection group (n=191). ECMO-related NI was evaluated according to demographic data, surgical procedures, and ECMO parameters. Results: The incidence of ECMO-related NI was 85.4 cases per 1000 ECMO days. Acinetobacter baumannii was the most common pathogen causing blood stream infection and respiratory tract infection. Prolonged duration of surgery (P=0.042) and cardiopulmonary bypass assist (P=0.044) increased the risk of ECMO-related NI. Body mass index (odds ratio [OR]: 1.077; 95% confidence interval [CI]: 1.004-1.156; P=0.039) and duration of ECMO support (OR: 1.006; 95% CI: 1.003-1.009; P=0.0001) were the independent risk factors for ECMO-related NI. Duration of ECMO support > 144 hours (OR: 2.460; 95% CI: 1.155-7.238; P<0.0001) and ECMO-related NI (OR: 3.726; 95% CI: 1.274-10.895; P=0.016) increased significantly the risk of in-hospital death. Conclusion: Prolonged duration of ECMO support was an independent risk factor for NI. Surgical correcting latent causes of cardiopulmonary failure and shortening duration of ECMO whenever possible would reduce susceptibility to NI.

The effect of annealing process on the microstructures and mechanical properties of Mg/Al composite plates fabricated by cast-rolling was investigated in this study. The results show that the interfacial transition zone can be divided into three regions: a Mg transition region, an Al transition region, and an intermediate region, respectively. The microhardness of the interfacial transition zone is higher than that of AZ31B and A356.When the annealing temperature is 250 ºC, the thermodynamic and kinetic conditions required for the formation of new intermetallic compounds have been met. While, for an annealing temperature at, or above, 300 ºC, the width of the interfacial transition zone, annealing temperature, and time follow model: ∆ X 2 = 2 . 07 × 10 4 exp − 60407 RT t − 11 . 54 exp 21211 RT. The shear strength reaches a maximum value of 116 MPa when the annealing temperature is 200 ºC. Cleavage fracture occurs at the side of the AZ31B alloy and quasi-cleavage fracture at the side of the A356 alloy.