In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of sci...In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2,including mission orbit and transfer orbit design,configuration and layout design,housekeeping and information flow design,power supply and distribution design,GNC and propulsion system design,communication links design,etc.,was accomplished through comprehensive tradeoff and evaluation on technical maturity,availability,schedule,cost,and so on.With a view to reducing development risk,both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies,modulations,data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20,2024,by means of 5 orbit maneuvers,Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations,Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions,as well as the capacity to perform scientific observations.Under the support of Queqiao-2,Chang′e-6 achieved its ambitious mission goal to collect and return samples from the moon′s mysterious far side.In the meanwhile,Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design,it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition,innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture,multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching,orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2,more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated.展开更多
Deep space exploration is the term used for the exploration of the Moon and the celestial bodies or space beyond the Moon, which is an important part of human space activities. Firstly, the development of deep space e...Deep space exploration is the term used for the exploration of the Moon and the celestial bodies or space beyond the Moon, which is an important part of human space activities. Firstly, the development of deep space exploration (not including the Moon) during the last few decades is summarized. Secondly, the development trend of different space countries and regions is analyzed. Then the experience and enlightenment of deep space exploration are briefly discussed. Some suggestions for China's future deep space exploration are given in the end.展开更多
Pectin-chitosan complex was prepared as a candidate material for colon-specific capsule.First,the effects of beating on the properties of complex films were explored.Fourier transform infrared(FT-IR)spectroscopy was u...Pectin-chitosan complex was prepared as a candidate material for colon-specific capsule.First,the effects of beating on the properties of complex films were explored.Fourier transform infrared(FT-IR)spectroscopy was used to analyze the reaction mechanics,and an in vitro simulation experiment was performed to determine the degradation performance.Second,the capsule was prepared using pectin-chitosan complex as the main raw material;its targeting effect was evaluated and analyzed.Results indicated that the film became smooth and compact by beating.FT-IR data indicated that cross-linking occurred between the hydroxyl group of pectin and the amino group of chitosan to form a network structure.In vitro experiment showed that the pectin-chitosan complex film could not be degraded in the simulated gastric and intestinal fluids.However,pectin-chitosan complex could be degraded in the simulated colonic fluid,so it could be a potential candidate for colon-specific capsule.Because the complex has no ability for forming hard capsule,the carrageenan and starch were added to increase the flexibility,gelation,transparency and mechanical properties of the film.The preferred composition suitable for preparing the capsule was a mass ratio(2:1:1)of pectin-chitosan/carrageenan/starch mixture.The capsule showed excellent features in terms of shape,water content,and brittleness.The drug release rate reached 93.33%in colonic fluid for 1 h when bovine serum albumin was the model drug.Therefore,pectin-chitosan may be considered as a new material for colon-targeted capsule.展开更多
文摘In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2,including mission orbit and transfer orbit design,configuration and layout design,housekeeping and information flow design,power supply and distribution design,GNC and propulsion system design,communication links design,etc.,was accomplished through comprehensive tradeoff and evaluation on technical maturity,availability,schedule,cost,and so on.With a view to reducing development risk,both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies,modulations,data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20,2024,by means of 5 orbit maneuvers,Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations,Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions,as well as the capacity to perform scientific observations.Under the support of Queqiao-2,Chang′e-6 achieved its ambitious mission goal to collect and return samples from the moon′s mysterious far side.In the meanwhile,Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design,it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition,innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture,multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching,orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2,more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated.
基金supported by the National Science and Technology Major Project on Lunar Exploration Program and the National High Technology Research and Development Program ("863" Program) (Grant Nos. 2010AA122206 and 2010AA7030506C)
文摘Deep space exploration is the term used for the exploration of the Moon and the celestial bodies or space beyond the Moon, which is an important part of human space activities. Firstly, the development of deep space exploration (not including the Moon) during the last few decades is summarized. Secondly, the development trend of different space countries and regions is analyzed. Then the experience and enlightenment of deep space exploration are briefly discussed. Some suggestions for China's future deep space exploration are given in the end.
基金This work was financially supported by the ShenBoTai Biological Technology Co.,LTD(Shenzhen,China).
文摘Pectin-chitosan complex was prepared as a candidate material for colon-specific capsule.First,the effects of beating on the properties of complex films were explored.Fourier transform infrared(FT-IR)spectroscopy was used to analyze the reaction mechanics,and an in vitro simulation experiment was performed to determine the degradation performance.Second,the capsule was prepared using pectin-chitosan complex as the main raw material;its targeting effect was evaluated and analyzed.Results indicated that the film became smooth and compact by beating.FT-IR data indicated that cross-linking occurred between the hydroxyl group of pectin and the amino group of chitosan to form a network structure.In vitro experiment showed that the pectin-chitosan complex film could not be degraded in the simulated gastric and intestinal fluids.However,pectin-chitosan complex could be degraded in the simulated colonic fluid,so it could be a potential candidate for colon-specific capsule.Because the complex has no ability for forming hard capsule,the carrageenan and starch were added to increase the flexibility,gelation,transparency and mechanical properties of the film.The preferred composition suitable for preparing the capsule was a mass ratio(2:1:1)of pectin-chitosan/carrageenan/starch mixture.The capsule showed excellent features in terms of shape,water content,and brittleness.The drug release rate reached 93.33%in colonic fluid for 1 h when bovine serum albumin was the model drug.Therefore,pectin-chitosan may be considered as a new material for colon-targeted capsule.
