Objective To select suitable vegetable for use in Controlled Ecological Life Support System for future long-term space missions. Method Five crops of lettuce(four Lactuca sativa L. var.crispa L.and one Lactuca sativa L. var.longifolia Lam), two crops of spinach(Spinacia oleracea L.), one rape(B.napus L.)and one common sowthisthe (Sonchus Oleraceus L.)were grown in a Controlled Ecological Life Support Technique Experimental System. Hydroponic nutrient solution, light, temperature and relative humidity were regulated, CO_2 levels were controlled at 500, 1 000, 1500 and 2 000 ?mol/mol, and light intensity were controlled at 100, 300, 500 and 700 ?mol/(m2?s). Canopy photosynthetic rate, transpiration rate and leaf aera were measured on day after planted (DAP) 25 and 30. Plants were harvested at maturity, and analyzed for total fresh weigh and proximate composition (crude fiber,nitrite and ?-carotene). Result Three crops of lettuce “nenlvnaiyou”, “dasusheng”,“youmaicai” ,and one common sowthisthe were selected. The favorite CO_2 concentration and light intensity 2 000 ?mol/mol, and 700 ?mol/(m2?s) respectively.Conclusion The four crops selected have high productivity, photosynthetic rates and transpiration rates, which can be considered as the basis of the vegetables to be used for future long-term space missions.

Objective A foundation for one of the biological components,Spirulina,to be applied in Controlled Ecological Life Support System(CELSS)would be laid with exploring effects of ionization radiation on the growth of Spirulina.Methods By using the ?-rays of ~(60)Co,Spirulina were irradiated.The dose of the ionization radiation covered 0,0.5,1.0,1.5,2.0,2.5,3.0 kGy.After irradiated,these Spirulina were cultured under the same conditions.The growth state,shape change,photodensity change,photosynthetic efficiency(O2 produced),and trophic physiological indexes of Spirulina or its solution,were observed,measured and analyzed.Its anti-irradiation ability was investigated.Results After irradiared with ~(60)Co ray,the growth rate,photosynthetic O2 produced efficiency,length of fila and other trophic physiological indexes were all affected in certain degree,but as compared to the higher plants,Spirulina have stronger radiation proof and self-rehabilitation capacity.Even if under high radiation condition(3.0 kGy),there was no complete death of cells,and the dose resulted in 50% death of the Spirulina was 2.0 kGy.Conclusion Spirulina has stronger ionization radiation proof and self-rehabilitation capacity,it can be considered as one of the key biological components in CELSS for future long-term space missions.

Objective To study the cultivating technique of wheat under low pressures as to establish the basis of developing hypobaric controlled ecological life support system.Methods Wheat growing experiments under normal and low pressure(101 kPa,50 kPa) were carried out with low pressure plant-cultivating facilities,and the growing indexes of wheat under low pressure,such as photosynthetic rate,transpiration rate,growing status,yield and nutrient contents in seeds were compared with those under normal pressure.Results Wheat grew normally under low pressure as compared with those grown under normal pressure,but low pressure curled leaves of the wheat and caused them to turn yellow at prophase;after 15 d treatment under hypobaric condition,the average rates of photosynthesis and transpiration increased by 9.23%and 11.54% respectively;shoot height of wheat decreased,both tiller number of each plant and the ratio of root in whole plant increased,but harvest time was delayed for about 5 d under low pressure;the biomass and the yield of wheat increased by 5.46% and 4.39% respectively,the contents of protein and total saccharide in seeds also enhanced at reduced pressure,but other nutrient contents in seeds had no significant difference between 101 kPa and 50 kPa.Conclusion Growth of wheat is promoted in certain degree by low atmospheric pressure.

Objective To develop a prototype of low pressure plant-cultivating facility, for studying the growing technique of higher plants under low pressure in manned deep space exploration, so as to lay foundations for establishing controlled ecological life support system (CELSS) in low pressure environment. Methods According to detailed demonstration of technical plan, blueprint design and machining of components, facility installment, debugging, trial operations and verification experiments were carried out. Results Two sets of low pressure plant-cultivating facilities were manufactured, both of them could be used to cultivate higher plant under low or normal pressure. They worked stably and their technical parameters such as temperature, relative humidity, air pressure, O2 partial pressure, CO2 partial pressure and water content of matrix were all monitored and controlled effectively. Conclusion Their main technical indexes meet design and experimental requirements, low pressure plant-cultivating experiments can be carried out with the facilities effectively.

Objective To investigate the characteristic of growth and development of vegetable at hypobaric environment and offer the cultivating technique of controlled ecological life support system for higher plant.Methods The means of comparative measurement was adopted to study the growth and physiological characteristic of lettuce under low and normal pressure(40.0 kPa,101.0 kPa),which was carried out with the low pressure plant-cultivating facility.Results Compared with normal pressure,germination rate of lettuce seed was eliminated by 7.62% under total pressure 40.0 kPa and oxygen partial pressure 8.4 kPa conditions;harvest time of lettuce was delayed,so biomass harvested at the same time reduced by 13.67% and content of total saccharide declined;the average rates of photosynthesis and transpiration were lower than those at normal pressure in 30 days after planting(DAP),but which reversed after that;release of C2H4 and shoot height reduced by 38.79% and 11.68%,but leaf area,ratio of root to total biomass and root vigor increased by 15.43%,2.57% and 40.53%,respectively.Conclusion Seed germination,growth and development of lettuce are affected in some degree at total pressure 40.0 kPa and oxygen partial pressure 8.4 kPa,some measures should be adopted to regulate the growth of lettuce.

Objective To investigate growing characteristics of plants grown at elevated CO2 concentrations in controlled environment and provide base for determination of biological components in future space controlled ecological life support system (CELSS).Methods Lettuce (Lactuca sativa var.Youmaicai) was cultivated at higher atmospheric CO2 concentration gradient (0.05%～2.0%).Its growing status,physiological characteristics and the content of nutrients were evaluated.Results There were some active effects of elevated CO2 (0.1% to 1.0%) on the average rates of photosynthesis and transpiration of the collective lettuce leaves and the contents of chlorophyll and carotenoid,but excessive CO2 (1.5% and 2.0%) weakened these effects,and even had some negative impacts.Lettuce could grow normally at elevated CO2 (0.1% to 2.0%),average shoot height and leaf area of lettuce plants treated at 0.1%～2.0% CO2 all increased,but the numbers of leaves eliminated gradually.The contents of nitrogen,potassium and Vc in plants decreased,phosphorus content rose and microelement contents had no obvious change in various CO2 treatments.Conclusion The lettuce can grow nearly normally at higher atmospheric CO2 concentration without serious growing inhibition or death,which indicated that the Youmaicai held stronger ability of tolerating higher concentration of CO2,so it's suitable to be determined as a candidate biological component in CELSS.

Objective To investigate the characteristics of higher plant grown in red and/or blue light and test the capability of red and/or blue light emitting diodes(LEDs) used as the artificial lights for plant growth in controlled ecological life support system(CELSS).Methods Lettuce(Lactuca sativa var.Youmaicai) was cultivated in sole white LED,sole red LED and combined red and blue LEDs,respectively.Its growing status,physiological characteristics and the content of nutrients were evaluated,which were adopted to select the best combination of red and blue LED for plant growth.Results Red light promoted the radial growth of lettuce plants,and blue light was propitious to their transverse extension and synthesis of chlorophyll and carotenoid;lettuce plants couldn't grow normally in sole red light;with the gradual increase of blue light proportion(5%~20%),there were some active effects on the growth of lettuce plants,for instance,the improvement of photosynthesis,transpiration and fluorescence(Fo,Fv/Fm and qN),the increasing of contents of chlorophyll,carotenoid and nutrients and the enhancement of total biomass;the adverse effects of blue LED on the growing of lettuce plants appeared gradually with the addition of blue light(25%~50%).Its biomass of shoot decreased significantly,which induced the increase of the ratio of root/shoot.Conclusion The combined red and blue LEDs is propitious to lettuce(var.Youmaicai) growth and the best lighting condition is the combined 90% red and 10% blue light.

Objective: To investigate the knowledge and practice levels on infectious disease among primary and middle school students, so as to provide a basis for targeted infectious disease in health education and infectious disease prevention and control in schools. Methods: The stratified cluster random sampling was used to select 25 670 primary and middle school students from 6 urban area and 10 suburban area in Beijing from October to November in 2020. A questionnaire survey on knowledge and practice of students related to infectious disease prevention and control was conducted using the questionnaire compiled by the Chinese Center for Disease Control and Prevention. Chisquare test was used for group comparison. Results: During the past two weeks, 8.64% students reported sickness absence. The awareness rates of knowledge on infectious disease were 37.64%-93.56%, and the formation rates of practice on infectious disease were between 62.22%-98.74%. The overall awareness rate of knowledge on infectious diseases was 58.58%, and the overall formation tate of practice on infectious disease prevention was 78.19%, with boys (54.14%,73.67%) lower than girls (63.25%,82.94%),urban areas (62.88%,79.12%) higher than suburbans areas (55.30%,77.48%), vocational high school studengs (43.51%,68.13%) lower than nonvocational high school students (elementary school: 56.05%, 85.19%; middle school: 61.66%, 78.63%; high school: 66.72%, 72.77% ), residential students (55.21%,71.59%) lower than nonresidential students (59.32%,79.64%), students living with parents (59.22%,79.30%) higher than those not with parents (54.60%,71.34%), and the differences were statistically significant (χ2=219.08, 148.95, 514.34, 26.44, 27.12; 323.26, 9.91, 536.11, 144.32, 114.11, P<0.05). Conclusions The levels of knowledge and practice regarding relative infectious disease among primary and middle school needs to be improved. Health education on the weak links in knowlege and practice of infectious disease prevention and control should be strengthened to reduce the incidence and transmission of infectious diseases.

Abstract Flood disasters are the common public health emergencies, mainly leading to environmental damage, water pollution, food pollution, vector breeding, infectious disease epidemic and other risk factors of sanitary and anti epidemic work. The guideline has been formulated with reference to the technical documents such as Guideline for Environmental Sanitation Disposal and Preventive Disinfection in Flooded Areas and Technical Proposal for Sanitary and Anti epidemic Measures after Flood Disasters, as well as the latest research progress at home and abroad. In order to guide the sanitary and anti epidemic measures in flooded areas, protect the health and safety of students and teachers and ensure the normal educational and teaching order, the guideline introduces the key measures that should be taken by schools, teachers and students in flood striken areas.

Objective:To analyze the epidemiological characteristics and transmission chain of an epidemic of COVID-19 in Haidian district, Beijing.Methods:Descriptive epidemiological method was used to analyze the epidemiological characteristics of the epidemic, and field investigation and big data technology were used to analyze the transmission chain of the epidemic.Results:From April 27 to May 13, 2022, an epidemic of COVID-19 occurred in Haidian district. The strains isolated from the cases were identified by whole genome sequencing as Omicron variant (BA.2.2 evolutionary branch). A total of 38 infection cases were detected, including 34 confirmed cases and 4 asymptomatic cases. Most cases were mild ones (88.2%), no severe, critical or death cases occurred. The early clinical symptoms were mainly sore throat (50.0%) and cough (29.4%). The epidemic lasted for 17 days, resulting in 7 generations of the cases and involving 3 community transmissions, 2 working place transmissions and 8 family transmissions; the main infection routes were co-residence (47.6%) and co-space exposure (31.6%). The intergenerational interval M( Q1, Q3)was 3 (1, 6) days. The overall secondary attack rate was 1.5% (37/2 482), and the family secondary attack rate was 36.7% (18/49). Conclusions:The cases in this COVID-19 epidemic caused by Omicron variant had mild clinical symptoms, but the case clustering in families and communities was obvious, the transmission was rapid, and the risk for co-space exposure was high. It is necessary to use information technology to identify close contacts in the local population for the rapid and effective blocking of the epidemic spread.