ZnO tetrapod-like whiskers were prepared through a hydrothermal process using zinc powder as raw material.Its microstructure and morphology were characterized by X-ray diffraction (XRD) and transmission electron micro...ZnO tetrapod-like whiskers were prepared through a hydrothermal process using zinc powder as raw material.Its microstructure and morphology were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD results showed that the crystal structure of as-obtained sample can be indexed to hexagonal wurtzite ZnO.TEM results revealed that the ZnO sample took on tetrapod-like whisker shape.The gas sensors were prepared with the traditional sintering process and their gas sensitivities were detected.The test results of gas sensitivity showed that the sensors based on ZnO tetrapod-like whiskers are very sensitive to dilute ethanol vapor and H_2S.The relatively high sensitivity and selectivity of these sensors made from ZnO tetrapod-like whiskers demonstrated the potential for developing a new class of selective ethanol sensors.展开更多
Fatigue has negative impacts on the general working population as well as on seafarers. In order to study seafarers’ fatigue, a questionnaire-base survey was conducted to gain information about potential risk factors...Fatigue has negative impacts on the general working population as well as on seafarers. In order to study seafarers’ fatigue, a questionnaire-base survey was conducted to gain information about potential risk factors for fatigue and construct indexes indicating fatigue. The study applies T-test to compare strata of seafarers to analyse work and sleep patterns in global seafaring. Qualitative analysis are also employed to explore the impacts of fatigue on seafarer’s occupational health and safety.展开更多
Summary What is already known about this topic?Typhoid fever remains a major public health problem in developing countries.Waterborne typhoid fever affects an estimated 27 million people worldwide each year.Decades of...Summary What is already known about this topic?Typhoid fever remains a major public health problem in developing countries.Waterborne typhoid fever affects an estimated 27 million people worldwide each year.Decades of indiscriminate antibiotic usage has driven the emergence and spread of multidrug-resistant(MDR)and even extensively drug-resistant(XDR)Salmonella Typhi(S.Typhi)strains.展开更多
Bone drilling is a routine operation in surgeries,such as neurosurgery and orthopedics.However,the excessive drilling temperature may cause severe thermal damage to the bone tissue.Therefore,the drilling temperature d...Bone drilling is a routine operation in surgeries,such as neurosurgery and orthopedics.However,the excessive drilling temperature may cause severe thermal damage to the bone tissue.Therefore,the drilling temperature determination of bone tissue can reduce the harm caused by thermal damage.A time-varying temperature field simulation model of bone drilling was set up by ABAQUS software in this paper,based on the Johnson-Cook model.Then it was validated with experiments by drilling cortical bone of fresh bovine shaft of the femur.The relative error between the experimental values and the theoretical values within 7.67%showed a good consistency.Furthermore,the aging factor is also considered to evaluate the temperature field of bone drilling.The results showed that the drilling temperature near the bone-drill area increased significantly.The drilling temperature of cortical bone decreases sharply with the radial distance and exhibits a hysteresis lag in the axial distribution.The aging factor mainly affects the peak of drilling temperature.The peak of drilling temperature tends to increase with age.The peak drilling temperature in the elderly(70y)was up to 6.8%higher than that in the young(20y),indicating that the elderly is more prone to excessive drilling temperature.Therefore,special attention should be paid to the temperature control of elderly bone tissue.展开更多
文摘ZnO tetrapod-like whiskers were prepared through a hydrothermal process using zinc powder as raw material.Its microstructure and morphology were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD results showed that the crystal structure of as-obtained sample can be indexed to hexagonal wurtzite ZnO.TEM results revealed that the ZnO sample took on tetrapod-like whisker shape.The gas sensors were prepared with the traditional sintering process and their gas sensitivities were detected.The test results of gas sensitivity showed that the sensors based on ZnO tetrapod-like whiskers are very sensitive to dilute ethanol vapor and H_2S.The relatively high sensitivity and selectivity of these sensors made from ZnO tetrapod-like whiskers demonstrated the potential for developing a new class of selective ethanol sensors.
文摘Fatigue has negative impacts on the general working population as well as on seafarers. In order to study seafarers’ fatigue, a questionnaire-base survey was conducted to gain information about potential risk factors for fatigue and construct indexes indicating fatigue. The study applies T-test to compare strata of seafarers to analyse work and sleep patterns in global seafaring. Qualitative analysis are also employed to explore the impacts of fatigue on seafarer’s occupational health and safety.
文摘Summary What is already known about this topic?Typhoid fever remains a major public health problem in developing countries.Waterborne typhoid fever affects an estimated 27 million people worldwide each year.Decades of indiscriminate antibiotic usage has driven the emergence and spread of multidrug-resistant(MDR)and even extensively drug-resistant(XDR)Salmonella Typhi(S.Typhi)strains.
基金National Natural Science Foundation of China(grant numbers:51875008 and 52105424)R&D Program of Beijing Municipal Education Commission(KM202210005033)+3 种基金Royal Society via an International Exchange programme(Grant No:IEC\NSFC\191,253)International Research Cooperation Seed Fund of Beijing University of Technology(grant number:2021A10)BJAST Innovation Cultivation Programes(No.11000022T000000446498)BJAST Budding Talent Program(BGS202210).
文摘Bone drilling is a routine operation in surgeries,such as neurosurgery and orthopedics.However,the excessive drilling temperature may cause severe thermal damage to the bone tissue.Therefore,the drilling temperature determination of bone tissue can reduce the harm caused by thermal damage.A time-varying temperature field simulation model of bone drilling was set up by ABAQUS software in this paper,based on the Johnson-Cook model.Then it was validated with experiments by drilling cortical bone of fresh bovine shaft of the femur.The relative error between the experimental values and the theoretical values within 7.67%showed a good consistency.Furthermore,the aging factor is also considered to evaluate the temperature field of bone drilling.The results showed that the drilling temperature near the bone-drill area increased significantly.The drilling temperature of cortical bone decreases sharply with the radial distance and exhibits a hysteresis lag in the axial distribution.The aging factor mainly affects the peak of drilling temperature.The peak of drilling temperature tends to increase with age.The peak drilling temperature in the elderly(70y)was up to 6.8%higher than that in the young(20y),indicating that the elderly is more prone to excessive drilling temperature.Therefore,special attention should be paid to the temperature control of elderly bone tissue.
