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In order to find a solution for the oil leakage problem of a large clearance shaft seal on a marine diesel engine, a series of improvement measures were proposed based on the mechanisms of centrifugal separation, reverse pumping, oil groove and staggered labyrinth. A shaft seal test system that can simulate the gas-liquid environment was built, and verification tests were conducted. Test results showed that the oil leakage didn't decrease after adding radial or inclined ribs on the oil slinger but increased significantly instead. Adding an oil groove on the oil baffle also didn't reduce any oil leakage. Fortunately, the addition of the staggered labyrinth effectively reduced the oil leakage. By combining with CFD simulation, the test results were explained, and the sealing functions of different structural features were studied. For structural design work of the non-contact shaft seal, the following design suggestions were proposed. First, the centrifugal effect on the liquid medium can be enhanced by adding ribs on the oil slinger, but the obstruction of oil return should be avoided at the same time. Second, the rotational speed should be fully considered when using the reverse pumping effect. Third, the oil guide groove should be adapted to the airflow and rotation state at its location. Finally, the staggered labyrinth has a stronger throttling effect compared with the straight-through labyrinth, which can reduce the outward transportation of oil by airflow. [ABSTRACT FROM AUTHOR]

This study optimized the fermentation conditions for producing glucanase from Burkholderia pyrrocinia B1213 using Jiuzao, a residue from Baijiu distillation, as the carbon source. The effects of Jiuzao particle size and concentration, type of nitrogen source, urea concentration, initial pH, inoculum size, loading volume, shaking speed, temperature, surfactant type and incubation time on glucanase production by B. pyrrocinia B1213 were investigated separately through single factor design. Then, five variables, Jiuzao concentration, inoculum size, initial pH, temperature and incubation time, were found to significantly affect glucanase production using the Plackett-Burman design. Following, the optimal conditions for glucanase production by B. pyrrocinia B1213 were found using the steepest ascent path and response surface methodology designs as: particle size, 40-60 mesh; Jiuzao concentration, 58.4 g/L; urea concentration, 8 g/L; initial pH, 6; loading volume, 15 mL/250 mL; inoculum size, 0.63% (v/v); temperature, 26 °C; shaking speed, 160 rpm; and incubation time, 120 h. Under these conditions, the glucanase activity of the B. pyrrcinia B1213 strain was 1336 U/mL, producing the biological enzymes needed in Baijiu making from a by-product. This study has provided experimental data and theoretical information for using B. pyrrcinia B1213 in Baijiu production. [ABSTRACT FROM AUTHOR]

The solution structure of RPP21 from the hyperthermophilic archaeon Pyrococcus furiosus (Pfu) is determined by using conventional and paramagnetic NMR techniques. The chemical shift perturbations have characterized the interaction of RPP21 with RPP29, showing that the primary contact with RPP29 is localized to the two helices of RPP21.

In this article, the fiber orientation evolution in the Csf/Mg composites with a large deformation is investigated. The principal strain-induced fiber orientation evolution mechanism, which states that the fiber orientation evolution in the Csf/Mg composites with a large deformation is determined by the principal strains, is proposed. The fiber orientation distribution factors Fi(i=1, 2and3) taking the form of the principal strains are proposed to quantitatively characterize the fiber orientation distribution in the Csf/Mg composites. The fiber orientation factors Fi s predicted by the finite element simulation based on the principal strain-induced fiber orientation evolution mechanism are compared against those Fi m measured from the micrographs of the extrusion experiments of Csf/Mg composites. The results demonstrate that the principal strain-induced fiber orientation evolution mechanism is valid and convenient to predict the fiber orientation evolution in the Csf/Mg composites with a large deformation. In the extruded Csf/Mg composites, the fibers are reoriented toward the direction of the maximum principal strain and deviated from the direction of the minimum principal strain. [ABSTRACT FROM AUTHOR]

This paper presents a new object tracking model that systematically combines region and boundary features. Besides traditional region features (intensity/color and texture), we design a new boundary-based object detector for accurate and robust tracking in low-contrast and complex scenes, which usually appear in the commonly used monochrome surveillance systems. In our model, region feature-based energy terms are characterized by probability models, and boundary feature terms include edge and frame difference. With a new weighting term, a novel energy functional is proposed to systematically combine the region and boundary-based components, and it is minimized by a level set evolution equation. For an efficient computational cost, motion information is utilized for new frame level set initialization. Compared with region feature-based models, the experimental results show that the proposed model significantly improves the performance under different circumstances, especially for objects in low-contrast and complex environments. [ABSTRACT FROM AUTHOR]

CH 3 NH 3 PbBr 3 perovskite nanocrystals (NCs) suffer from poor stability because of their high sensitivity to environmental moisture and water. To solve this problem, previous works mainly focus on embedding perovskite NCs into water-resistant matrix to form large composites (size of microns or larger). As an alternative solution without serious changing of NC size, enhancing the stability of perovskite NCs themselves by ligand engineering is rarely reported. In this work, we used hyperbranched polyamidoamine (PAMAM) dendrimers with two different generations (G0 and G4) to synthesize CH 3 NH 3 PbBr 3 perovskite NCs with high photoluminescence (PL) quantum yields (QY) above 70% and a new record stability. A novel dendrimers generation-dependent stability of perovskite NCs was observed. The water-resistance time is 18 h (27 h) for perovskite NCs capped by G0 (G4) generation of PAMAM, which is 7 times (11 times) longer than that of traditional oleic acid-capped NCs. Similar PAMAM generation-related stability is also observed in moisture-resistance tests. The stability time against moisture is 500 h (800 h) for G0 (G4) generation of PAMAM-capped perovskite NCs, which is a new record stability time against moisture for CH 3 NH 3 PbBr 3 perovskite NCs. In addition, our results also indicate that PAMAM ligands outside perovskite NCs can dramatically slow down the speed of halide exchange. Even for the mixture of perovskite NCs with two different halide composition, the original luminescence properties of PAMAM-capped perovskite NCs can retain after mixing. In view of slow halide exchange speed, excellent water and moisture stability, PAMAM dendrimers-capped perovskite NCs and their mixture are available as color conversion single layer in fabrication of light-emitting diodes (LED).