With the exponential growth of the data traffic in wireless communication systems, terahertz(THz) frequency band is envisioned as a promising candidate to support ultra-broadband for future beyond fifth generation(5G)...With the exponential growth of the data traffic in wireless communication systems, terahertz(THz) frequency band is envisioned as a promising candidate to support ultra-broadband for future beyond fifth generation(5G), bridging the gap between millimeter wave(mmWave) and optical frequency ranges. The purpose of this paper is to provide a comprehensive literature review on the development towards THz communications and presents some key technologies faced in THz wireless communication systems. Firstly, despite the substantial hardware problems that have to be developed in terms of the THz solid state superheterodyne receiver, high speed THz modulators and THz antennas, the practical THz channel model and the efficient THz beamforming are also described to compensate for the severe path attenuation. Moreover, two different kinds of lab-level THz communication systems are introduced minutely, named a solid state THz communication system and a spatial direct modulation THz communication system, respectively. The solid state THz system converts intermediate frequency(IF) modulated signal to THz frequency while the direct modulation THz system allows the high power THz sources to input for approving the relatively long distance communications. Finally, we discuss several potential application scenarios as well as some vital technical challenges that will be encountered in the future THz communications.展开更多
Objective To evaluate the environmental and technical efficiencies of China＇s industrial sectors and provide appropriate advice for policy makers in the context of rapid economic growth and concurrent serious environ...Objective To evaluate the environmental and technical efficiencies of China＇s industrial sectors and provide appropriate advice for policy makers in the context of rapid economic growth and concurrent serious environmental damages caused by industrial pollutants. Methods A data of envelopment analysis （DEA） framework crediting both reduction of pollution outputs and expansion of good outputs was designed as a model to compute environmental efficiency of China＇s regional industrial systems. Results As shown by the geometric mean of environmental efficiency, if other inputs were made constant and good outputs were not to be improved, the air pollution outputs would have the potential to be decreased by about 60% in the whole China. Conclusion Both environmental and technical efficiencies have the potential to be greatly improved in China, which may provide some advice for policy-makers.展开更多
The concrete-faced rockfill dam(CFRD) is an important dam type in the selection of high dams to be constructed in Western China,owing to its direct utilization of local materials,good adaptability,and distinct economi...The concrete-faced rockfill dam(CFRD) is an important dam type in the selection of high dams to be constructed in Western China,owing to its direct utilization of local materials,good adaptability,and distinct economic advantages.Over the past decades,China has gained successful experience in the construction of 200 m CFRDs,providing the necessary technical accumulation for the development of 250–300 m ultra-high CFRDs.This paper summarizes these successful experiences and analyzes the problems of a number of major 200 m CFRDs around the world.In addition,it discusses the key technologies and latest research progress regarding safety in the construction of 250–300 m ultra-high CFRDs,and suggests focuses and general ideas for future research.展开更多
Traditional Chinese medicine (TCM) is a medical system that has collected and summarized abundant clinical experience over its long history of more than 2000 years. However, the frequent occurrence of TCM-induced adve...Traditional Chinese medicine (TCM) is a medical system that has collected and summarized abundant clinical experience over its long history of more than 2000 years. However, the frequent occurrence of TCM-induced adverse reactions has hindered the modernization and internationalization of TCM, while attracting increasing attention from around the world. Unlike chemical drugs and biological agents, the difficulties involved in research on the toxicity and safety of TCM mainly include the complexity of its components and the unpredictability of drug–body interactions. Much of TCM, which has overall therapeutic effects, has the typical mechanisms of multiple components, multiple pathways, and multiple targets. While considering the gradualness and unpredictability of TCM toxicity, the ambiguity of toxicants and safe dosage, and individual differences during long-term TCM administration, we have systematically established key techniques for the toxicity assessment of TCM. These techniques mainly include TCM toxicity discovery in an early phase, based on a combination of drug toxicology genomics and metabolomics;methods to identify dose–toxicity relationships in TCM;and integrated techniques for the exploration of TCM interactions, such as fast-screening tests based on drug-metabolizing enzymes and receptor pathways. In particular, we have developed a new technical system for TCM safety evaluation using molecular toxicology, which has been validated well in research on TCM compatibility contraindication, quality control, and allergen discovery. The application of this key technical platform is introduced here in detail. This application includes model organisms, toxicant biomarkers, a magnetic suspension technique, and the application of network toxicology and computational toxicology in research on the toxicity of Fructus toosendan, Semen cassiae, Polygonum multiflorum, and Fructus psoraleae.展开更多
A number of clinical trials have demonstrated that the laparoscopic approach for colorectal cancer resection provides the same oncologic results as open surgery along with all clinical benefits of minimally invasive s...A number of clinical trials have demonstrated that the laparoscopic approach for colorectal cancer resection provides the same oncologic results as open surgery along with all clinical benefits of minimally invasive surgery. During the last years, a great effort has been made to research for minimizing parietal trauma, yet for cosmetic reasons and in order to further reduce surgery-related pain and morbidity. New techniques, such as natural orifice transluminal endoscopic surgery (NOTES) and single-incision laparoscopy (SIL) have been developed in order to reach the goal of “scarless” surgery. Although NOTES may seem not fully suitable or safe for advanced procedures, such as colectomies, SIL is currently regarded as the next major advance in the progress of minimally invasive surgical approaches to colorectal disease that is more feasible in generalized use. The small incision through the umbilicus allows surgeons to use familiar standard laparoscopic instruments and thus, perform even complex procedures which require extraction of large surgical specimens or intestinal anastomosis. The cosmetic result from SIL is also better because the only incision is made through the umbilicus which can hide the wound effectively after operation. However, SIL raises a number of specific new challenges compared with the laparoscopic conventional approach. A reduced capacity for triangulation, the repeated conflicts between the shafts of the instruments and the difficulties to achieve a correct exposure of the operative field are the most claimed issues. The use therefore of this new approach for complex colorectal procedures might understandingly be viewed as difficult to implement, especially for oncologic cases.展开更多
基金supported by the National High Technology Research and Development Program of China (863 program) of China under Grant No.2011AA010200 supported by the National Natural Science Foundation of China (NSFC) under Grant No.61771116 and No.91738102
文摘With the exponential growth of the data traffic in wireless communication systems, terahertz(THz) frequency band is envisioned as a promising candidate to support ultra-broadband for future beyond fifth generation(5G), bridging the gap between millimeter wave(mmWave) and optical frequency ranges. The purpose of this paper is to provide a comprehensive literature review on the development towards THz communications and presents some key technologies faced in THz wireless communication systems. Firstly, despite the substantial hardware problems that have to be developed in terms of the THz solid state superheterodyne receiver, high speed THz modulators and THz antennas, the practical THz channel model and the efficient THz beamforming are also described to compensate for the severe path attenuation. Moreover, two different kinds of lab-level THz communication systems are introduced minutely, named a solid state THz communication system and a spatial direct modulation THz communication system, respectively. The solid state THz system converts intermediate frequency(IF) modulated signal to THz frequency while the direct modulation THz system allows the high power THz sources to input for approving the relatively long distance communications. Finally, we discuss several potential application scenarios as well as some vital technical challenges that will be encountered in the future THz communications.
文摘Objective To evaluate the environmental and technical efficiencies of China＇s industrial sectors and provide appropriate advice for policy makers in the context of rapid economic growth and concurrent serious environmental damages caused by industrial pollutants. Methods A data of envelopment analysis （DEA） framework crediting both reduction of pollution outputs and expansion of good outputs was designed as a model to compute environmental efficiency of China＇s regional industrial systems. Results As shown by the geometric mean of environmental efficiency, if other inputs were made constant and good outputs were not to be improved, the air pollution outputs would have the potential to be decreased by about 60% in the whole China. Conclusion Both environmental and technical efficiencies have the potential to be greatly improved in China, which may provide some advice for policy-makers.
文摘The concrete-faced rockfill dam(CFRD) is an important dam type in the selection of high dams to be constructed in Western China,owing to its direct utilization of local materials,good adaptability,and distinct economic advantages.Over the past decades,China has gained successful experience in the construction of 200 m CFRDs,providing the necessary technical accumulation for the development of 250–300 m ultra-high CFRDs.This paper summarizes these successful experiences and analyzes the problems of a number of major 200 m CFRDs around the world.In addition,it discusses the key technologies and latest research progress regarding safety in the construction of 250–300 m ultra-high CFRDs,and suggests focuses and general ideas for future research.
文摘Traditional Chinese medicine (TCM) is a medical system that has collected and summarized abundant clinical experience over its long history of more than 2000 years. However, the frequent occurrence of TCM-induced adverse reactions has hindered the modernization and internationalization of TCM, while attracting increasing attention from around the world. Unlike chemical drugs and biological agents, the difficulties involved in research on the toxicity and safety of TCM mainly include the complexity of its components and the unpredictability of drug–body interactions. Much of TCM, which has overall therapeutic effects, has the typical mechanisms of multiple components, multiple pathways, and multiple targets. While considering the gradualness and unpredictability of TCM toxicity, the ambiguity of toxicants and safe dosage, and individual differences during long-term TCM administration, we have systematically established key techniques for the toxicity assessment of TCM. These techniques mainly include TCM toxicity discovery in an early phase, based on a combination of drug toxicology genomics and metabolomics;methods to identify dose–toxicity relationships in TCM;and integrated techniques for the exploration of TCM interactions, such as fast-screening tests based on drug-metabolizing enzymes and receptor pathways. In particular, we have developed a new technical system for TCM safety evaluation using molecular toxicology, which has been validated well in research on TCM compatibility contraindication, quality control, and allergen discovery. The application of this key technical platform is introduced here in detail. This application includes model organisms, toxicant biomarkers, a magnetic suspension technique, and the application of network toxicology and computational toxicology in research on the toxicity of Fructus toosendan, Semen cassiae, Polygonum multiflorum, and Fructus psoraleae.
文摘A number of clinical trials have demonstrated that the laparoscopic approach for colorectal cancer resection provides the same oncologic results as open surgery along with all clinical benefits of minimally invasive surgery. During the last years, a great effort has been made to research for minimizing parietal trauma, yet for cosmetic reasons and in order to further reduce surgery-related pain and morbidity. New techniques, such as natural orifice transluminal endoscopic surgery (NOTES) and single-incision laparoscopy (SIL) have been developed in order to reach the goal of “scarless” surgery. Although NOTES may seem not fully suitable or safe for advanced procedures, such as colectomies, SIL is currently regarded as the next major advance in the progress of minimally invasive surgical approaches to colorectal disease that is more feasible in generalized use. The small incision through the umbilicus allows surgeons to use familiar standard laparoscopic instruments and thus, perform even complex procedures which require extraction of large surgical specimens or intestinal anastomosis. The cosmetic result from SIL is also better because the only incision is made through the umbilicus which can hide the wound effectively after operation. However, SIL raises a number of specific new challenges compared with the laparoscopic conventional approach. A reduced capacity for triangulation, the repeated conflicts between the shafts of the instruments and the difficulties to achieve a correct exposure of the operative field are the most claimed issues. The use therefore of this new approach for complex colorectal procedures might understandingly be viewed as difficult to implement, especially for oncologic cases.
