Natural minerals receive growing attention as inexpensive, green, and efficient catalysts for degradation of organic pollutants. Mechanical activation of natural chalcopyrite was conducted for improving the catalytic ...Natural minerals receive growing attention as inexpensive, green, and efficient catalysts for degradation of organic pollutants. Mechanical activation of natural chalcopyrite was conducted for improving the catalytic performance.Tetracycline degradation was evaluated in the presence of hydrogen peroxide and mechanically activated chalcopyrite.Tetracycline degradation at 100 min is 55.52%(Chp10), 68.97%(Chp30), 77.79%(Chp60), and 86.43%(Chp120),respectively, and the rate constant of pseudo-first-order kinetics is 0.0079, 0.0109, 0.0137 and 0.0192 min^(-1), respectively.Chalcopyrite samples were examined by multiple characterizations. Mechanical activation of natural chalcopyrite induces the decline of particle size and slight increase of surface area, smaller grain size, lattice strain, and partial sulfur oxidation. The relationship between catalytic activity and property change manifests that the improved catalytic ability is mainly ascribed to the increase of surface area and surface oxidation induced by mechanical activation. This work provides novel insights into the improvement of catalytic performance of natural minerals by mechanical activation.展开更多
In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the reg...In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the registered chemical insecticides. Consequently, heavy applications of chemical insecticides to control this pest become ineffective on a long-term basis and can lead to serious health and environmental problems. The use of natural enemies to control CPB is an interesting alternative to chemical means However, hand release of predators is not feasible on a large scale in the field. The main objective of this research study was to design and build a test bench to investigate the technical feasibility of mechanically releasing predators. The test bench consisted of a vertical chain conveyor mounted on two vertical shafts driven by an electric motor. Since the predators are small and fragile, they were placed in a specially designed container to preserve their physical integrity. Trials using this test bench showed that a carrier material was required, because most of the predators remained inside the container. The success of this mass predator release system will be highly valuable for the biological control of insect pests in many crops.展开更多
Fibers are used in various areas for improving the performance of different materials, commonly used are synthetic fibers and glass fibers. More and more sustainable alternatives are required to reduce energy consumpt...Fibers are used in various areas for improving the performance of different materials, commonly used are synthetic fibers and glass fibers. More and more sustainable alternatives are required to reduce energy consumption and the carbon footprint. Traditional natural fibers （like hemp or flax） very often do not fulfill requirements for construction purposes like resistance to elevated temperature or lacking purity. Also mechanical properties of natural fibers are influenced by factors like harvesting, kink bands, climate and growth conditions. Lenzing AG has put a lot of efforts into developing a sustainable fiber overcoming the above mentioned issues. The raw material for TENCEL is wood, which is transformed into a fiber of pure cellulose in an economy friendly process as been proven by a life cycle assessment. The properties of a composite material are highly dependent on parameters like mechanical fiber properties, fiber diameter, quality of fiber dispersion and fiber matrix adhesion. Keeping these properties constant throughout the whole composite part is the factor to success. The diameter as well as the mechanical properties of TENCEL fibers is kept within a very narrow range thanks to the unique manufacturing process. It was shown that the fiber dispersion of TENCEL as well as the fiber matrix adhesion is better than for natural fibers.展开更多
Propulsion of liquefied natural gas (LNG) ships is undergoing significant change. The traditional steam plant is losing favor because of its low cycle efficiency. Medium-speed diesel-electric and slow-speed diesel-mec...Propulsion of liquefied natural gas (LNG) ships is undergoing significant change. The traditional steam plant is losing favor because of its low cycle efficiency. Medium-speed diesel-electric and slow-speed diesel-mechanical drive ships are in service, and more are being built. Another attractive alternative is combined gas and steam turbine (COGAS) drive. This approach offers significant advantages over steam and diesel propulsion. This paper presents the case for the COGAS cycle.展开更多
A 3-D FEA （finite element analysis） transient and steady-state design proposal for high-speed with Nd-Fe-Br （reversible） magnets in aerospace application will be examined under design considerations of n = 12,000 ...A 3-D FEA （finite element analysis） transient and steady-state design proposal for high-speed with Nd-Fe-Br （reversible） magnets in aerospace application will be examined under design considerations of n = 12,000 rpm, short-duty, sinusoidal drive, low cogging, high efficiency at peak torque, and etc. for an ARWM （aerospace retraction wheel motor）. In construction, the PMs （permanent magnets） fixed on the rotor core which is surface-mOunted magnets retained by a carbon-fiber bandage. Redundant windings, resistant to fault propagation have accounted. Besides, an axial water-jacket housing without end-cap cooling has involved. All performed characteristic performances of the correlated ARWM will verify by comparison through 2-D and 3-D FEA results. In this paper, design process has dealing with determination of various kinds of losses such as electromagnetic and mechanical losses. In terms of both classified losses, copper, stator back iron, stator tooth, PM, rotor back iron, air-friction and sleeve losses were calculated. The 3-D end-winding effects were included in the modeled ARWM by the authors.展开更多
Objective To investigate the clinical outcomes of children with congenital heart disease （CHD） requiring extracorporeal membrane oxygenation （ECMO） and left ventricular assist device （LVAD） support after cardiac...Objective To investigate the clinical outcomes of children with congenital heart disease （CHD） requiring extracorporeal membrane oxygenation （ECMO） and left ventricular assist device （LVAD） support after cardiac surgery. Methods A total of 22 patients with CHD who required postcardiotomy mechanical circulatory support between March 2004 and March 2011 （85 months ） were analyzed retrospectively. Median age of the patients was 420 d （ 15 d - 4 years） and median weight was 3.4 kg （ 2 - 14. 5 kg ）. Eight patients were put on ECMO, while 14 patients were placed on LVAD. Results Thirteen （59%） patients died and 9 （41% ） survived to discharge. In survivals, the duration of LVAD and the duration of ECMO were both shorter than those of nonsurvivals （P 〈 O. 05）. The main complication was bleeding. Conclusion The earlier treatment and application of more advanced cardiac support devices for CHD patients are key factors for reducing complications.展开更多
基金Project(2020YFC1908802) supported by the National Key Research and Development Project of China。
文摘Natural minerals receive growing attention as inexpensive, green, and efficient catalysts for degradation of organic pollutants. Mechanical activation of natural chalcopyrite was conducted for improving the catalytic performance.Tetracycline degradation was evaluated in the presence of hydrogen peroxide and mechanically activated chalcopyrite.Tetracycline degradation at 100 min is 55.52%(Chp10), 68.97%(Chp30), 77.79%(Chp60), and 86.43%(Chp120),respectively, and the rate constant of pseudo-first-order kinetics is 0.0079, 0.0109, 0.0137 and 0.0192 min^(-1), respectively.Chalcopyrite samples were examined by multiple characterizations. Mechanical activation of natural chalcopyrite induces the decline of particle size and slight increase of surface area, smaller grain size, lattice strain, and partial sulfur oxidation. The relationship between catalytic activity and property change manifests that the improved catalytic ability is mainly ascribed to the increase of surface area and surface oxidation induced by mechanical activation. This work provides novel insights into the improvement of catalytic performance of natural minerals by mechanical activation.
文摘In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the registered chemical insecticides. Consequently, heavy applications of chemical insecticides to control this pest become ineffective on a long-term basis and can lead to serious health and environmental problems. The use of natural enemies to control CPB is an interesting alternative to chemical means However, hand release of predators is not feasible on a large scale in the field. The main objective of this research study was to design and build a test bench to investigate the technical feasibility of mechanically releasing predators. The test bench consisted of a vertical chain conveyor mounted on two vertical shafts driven by an electric motor. Since the predators are small and fragile, they were placed in a specially designed container to preserve their physical integrity. Trials using this test bench showed that a carrier material was required, because most of the predators remained inside the container. The success of this mass predator release system will be highly valuable for the biological control of insect pests in many crops.
文摘Fibers are used in various areas for improving the performance of different materials, commonly used are synthetic fibers and glass fibers. More and more sustainable alternatives are required to reduce energy consumption and the carbon footprint. Traditional natural fibers （like hemp or flax） very often do not fulfill requirements for construction purposes like resistance to elevated temperature or lacking purity. Also mechanical properties of natural fibers are influenced by factors like harvesting, kink bands, climate and growth conditions. Lenzing AG has put a lot of efforts into developing a sustainable fiber overcoming the above mentioned issues. The raw material for TENCEL is wood, which is transformed into a fiber of pure cellulose in an economy friendly process as been proven by a life cycle assessment. The properties of a composite material are highly dependent on parameters like mechanical fiber properties, fiber diameter, quality of fiber dispersion and fiber matrix adhesion. Keeping these properties constant throughout the whole composite part is the factor to success. The diameter as well as the mechanical properties of TENCEL fibers is kept within a very narrow range thanks to the unique manufacturing process. It was shown that the fiber dispersion of TENCEL as well as the fiber matrix adhesion is better than for natural fibers.
文摘Propulsion of liquefied natural gas (LNG) ships is undergoing significant change. The traditional steam plant is losing favor because of its low cycle efficiency. Medium-speed diesel-electric and slow-speed diesel-mechanical drive ships are in service, and more are being built. Another attractive alternative is combined gas and steam turbine (COGAS) drive. This approach offers significant advantages over steam and diesel propulsion. This paper presents the case for the COGAS cycle.
文摘A 3-D FEA （finite element analysis） transient and steady-state design proposal for high-speed with Nd-Fe-Br （reversible） magnets in aerospace application will be examined under design considerations of n = 12,000 rpm, short-duty, sinusoidal drive, low cogging, high efficiency at peak torque, and etc. for an ARWM （aerospace retraction wheel motor）. In construction, the PMs （permanent magnets） fixed on the rotor core which is surface-mOunted magnets retained by a carbon-fiber bandage. Redundant windings, resistant to fault propagation have accounted. Besides, an axial water-jacket housing without end-cap cooling has involved. All performed characteristic performances of the correlated ARWM will verify by comparison through 2-D and 3-D FEA results. In this paper, design process has dealing with determination of various kinds of losses such as electromagnetic and mechanical losses. In terms of both classified losses, copper, stator back iron, stator tooth, PM, rotor back iron, air-friction and sleeve losses were calculated. The 3-D end-winding effects were included in the modeled ARWM by the authors.
文摘Objective To investigate the clinical outcomes of children with congenital heart disease （CHD） requiring extracorporeal membrane oxygenation （ECMO） and left ventricular assist device （LVAD） support after cardiac surgery. Methods A total of 22 patients with CHD who required postcardiotomy mechanical circulatory support between March 2004 and March 2011 （85 months ） were analyzed retrospectively. Median age of the patients was 420 d （ 15 d - 4 years） and median weight was 3.4 kg （ 2 - 14. 5 kg ）. Eight patients were put on ECMO, while 14 patients were placed on LVAD. Results Thirteen （59%） patients died and 9 （41% ） survived to discharge. In survivals, the duration of LVAD and the duration of ECMO were both shorter than those of nonsurvivals （P 〈 O. 05）. The main complication was bleeding. Conclusion The earlier treatment and application of more advanced cardiac support devices for CHD patients are key factors for reducing complications.
