Objective To study mathematical model and to perform computer simulation for an important subsystem in the bioregenerative life support system(BLSS),i.e.,light-algae bioreactor(LABR)forcontinuously cultivating green microalgae andsignificantly maintaining life support function of BLSS.MethodsBased on the theories of system dynamics and stoichiometry,the mathematical model and simulation model of LABR were respectively established with experimental data,and then computer experiments were conducted to simulate dynamic responses of LABR under different parameters as well as their combinations.Results It was shown that the kinetic model of LABR was valid for its real-life counterpart by a series of verification tests.It could reliably and beneficially provede technical and methodologcal helps for further investigations of LABR,such as theoretical analysis,design,control and optimization,and so on.Conclusion With computer experiments based on mathematical model and simulation model,it decreases much more in time and money consumption for investigations than with real experiment.This method can also be extended to use in other subsystems studies of BLSS.

Objective To observe the protective effects of natural antioxidant tea polyphenols(TP) on myocardial free radical metabolic disorder in mice induced by inhalation of hypobaric pure oxygen under 5500 m hypobaric condition. Method Fourty-two male Kunming mice were randomly divided into three groups(n=14 each):group A, normal control; group B, inhalation of pure oxygen(>96%) at simulated altitude of 5500 m in an animal altitude chamber;group C(TP protection group), same as group B but 100 mg/kg of TP was given orally before the exposure. The exposure time was 2 h/d,3 d/wk for a total of 8 wk, and distilled water was given to groups A and B before exposure. After experiment, the mice were decapitated on the next day and the heart was quickly removed. Malondialdehyde(MDA) concentration, superoxide dismutase(SOD) activity and nitric oxide(NO) content were measured. In addition, Cu,Zn-SOD and inducible NO synthase(iNOS) enzymatic contents in myocardial tissue were qualitatively examined by immunohistochemical assaying. Result Compared with the control, MDA concentration, SOD activity and Cu,Zn-SOD enzymatic content in group B were significantly increased(P<0.05).But in TP protection group, myocardial MDA formation was significantly decreased(P<0.01) and SOD activity and Cu,Zn-SOD expression restored to normal. On the contrary, myocardial NO generation and iNOS expression were significantly reduced after repeated inhalation of hypobaric oxygen at 5500 m.NO metabolism regained to normal after repeated administration of TP. Conclusion Natural antioxidant TP had protective effects on myocardial free radical metabolic disorder induced by inhalation of hypobaric pure oxygen under 5500 m hypobaric condition.

With the development of space medicine ,traditional Chinese me dicine a nd Chinese herbs have been widely used in counteracting motion sickness，bone loss，muscle atrophy，and circulation system disorder，improving bod y′s adaptability and protecting the effect of irradiation，hypoxia and noise.This paper summarized the application of basic theories of traditiona l Chinese medicine,Chinese herbs,acupoint treatment and Qigong in space medical research.

The limitations of the currently used exercise-based counterm easures and the scientific rationale for the gravity-based countermeasures are a ddressed.Then,an overview of the physiological effects and requirements for th e two types of artificial gravity (AG),i.e.,the continuous AG provided by full -time spinning of the entire space system/habitat and the intermittent AG by i nco rporating a short-arm centrifuge into the spacecraft,is presented.Finally,sig nificance and challenge faced in future research on biochemical problems of arti ficial gravity are discussed

Objective The aim of this study was to determine whether psychomotor performance and visual reaction time were affected by acute exposure to mild or moderate hypoxia. Method Eighteen healthy male volunteers performed finger tapping, simple reaction time(SRT) and 4-choice reaction time(CRT) tests at simulated altitude of 300 m (control),2800 m, 3600 m and 4400 m for 1 h in a hypobaric chamber. Result SaO2 decreased from 98%(control) to 90%,82% and 74% respectively at the various altitudes. All the performance parameters showed no significant change after exposure to 2800 m for 1 h relative to ground level(P>0.05). However the mean reaction time of 4-CRT under 3600 m prolonged and performance decreased as compared with baseline value(P<0.05), and the performance decreased further under 4400 m(P<0.01). No significant difference was found in finger tapping and SRT even under exposure to 4400 m for 1 h.Furthermore, no decrease in correct rate were observed at any altitude (P>0.05). Conclusion The results from this study demonstrated that there were no measurable impairment of visual reaction time and psychomotor performance under exposure to an altitude of 2800 m for 1 h. However, adverse effects on psychomotor performance were observed under 3600 m and over.

Objective To explore a space craft precooling temperature at which excessive thermal stress on the crew member could be prevented or reduced in an overheated launch or reentry module. Method Five young male volunteers wearing a space suit participated in 25 tests at sea level.The space suit was either ventilated in a volume air flow rate of 100 L/min (STPD) with ambient air at temperatures (Ta) of 15℃,10℃,and 5℃,respectively,or not ventilated. Rectal (Tr),mean skin (Tsk) and mean body (Tb) temperatures were measured. Result At Ta 15℃,Tr decreased without significance (from 37.0±0.2℃to 36.7±0.3℃) in 120-min tests,whereas Tsk and Tb decreased significantly,and subjects had local cold strain whether the space suit was ventilated or not; while at Ta 10℃,Tr decreased from 37.0±0.3℃ to 36.3±0.3℃(P<0.05),subjects had a whole body cold strain,and both Tsk and Tb dropped continuously and significantly. Conclusion Ambient temperature 15℃,at which the thermal comfort states of crew was not significantly degraded,was acceptable after precooling in a space craft.

Objective To validate near-infrared cerebral topography (NCT) as a practical toolin tracing the regional hemodynamic changes during normal ischemic stroke model of rat. Method Middle cerebral artery occlusion (MCAO) and photosensitizer induced intracranial infarction model of rat were established. The geometric shape and infarction area were measured by NCT, functional magnetic resonance imaging (fMRI), and TTC stained anatomical imaging techniques. Result In photosensitizer induced infarction model, the correlation between anatomical infarct area and NCT image area for infarct focus were r= 0.897 for 24 h group (P<0.05) and r=0.906 for 2 months group (P<0.01),respectively. The correlation between anatomical infarction area and NCT image area for infarct focus were r=0.820 for normothermia group (P<0.05) and r= 0.851 for hypothermia group (P<0.05), respectively. The correlation between fMRI and NCT image area for infarction focus were r= 0.874 for normothermia group (P<0.05) and r= 0.782 for hypothermia group (P<0.05),respectively. Conclusion Measurement with NCT for infarction focus matched well with fMRI and anatomic sample in rats. NCT technique might be a practical tool for short-term prediction of stroke and the rehabilitation after stroke in real time.

Objective To investigate the left prefrontal lobe activation during semantic and non-semantic encoding tasks with functional near-infrared imaging (fNIRI) technique. Method 22 healthy subjects were assigned semantic encoding and non-semantic encoding tasks. During semantic encoding tasks, subjects were asked to make a meaningful sentence including two unrelated Chinese word pairs, while during non-semantic encoding task they were asked to judge whether the two Chinese word pairs had the same morphological structure or not. Light intensity of two wavelengths (760 nm and 850 nm) diffused through skull and left prefrontal lobe were real-time recorded and used to reconstruct the brain activation image during the experiment. Result With the fNIRI, significant activations were observed in the left inferior prefrontal cortex (Brodmann' areas 45 and 47) during the two tasks, but the evoked activations were more significant for semantic than non-semantic task. These observations were consistent with the results reported by others with functional megnetic resonance imaging(fMRI) and positron-emission tomographyPET.Conclusion The results suggest that fNIRI provides an important, non-invasive way to map the prefrontal activation during cognitive tasks.

Objective System of pressure breathing for +Gz (PBG) has been incorporated into service in the high performance fighter aircraft,but there were significant differences among PBG pressure schedules used in different countries.The purpose of this study was to define an optimal pressure schedule in PBG system.Method Five male subjects wearing GZ-2 anti-G suit and medium-sized bladder vest,plus PBG with 1.6,2.4,and 3.2 kPa/G pressure schedules,respectively,were exposed to rapid onset (3.0 G/s) centrifuge +Gz runs.+Gz protection of PBG with each of the three pressure schedules were measured and the subjective ratings were collected.Result The +Gz protection afforded by PBG with 1.60,2.40,and 3.20 kPa/G pressure schedules were 2.00±0.31,2.54±0.32,and 2.44±0.31 G,respectively.Subjective ratings showed that the PBG with 2.40 kPa/G pressure schedule was better than the other two.Conclusion Our data suggest that a PBG pressure schedule of 2.4 kPa/G in PBG system is optimal.It not only assures the anti-G performance of PBG,but also reduces its side effects.

Objective To obtain the frequency weighting contour for seated Chinese young males in z axis.Method 10 male volunteers served as the subjects.They were exposed to standard vibration stimulus (a sinusoidal vibration of 1.0 m/s2 at 8 Hz) and 14 kinds of sinusoidal experimental vibration stimuli at frequencies from 4 Hz to 80 Hz.The magnitude of the experimental vibration stimulus was changed by the subject through a signal condition and switching device made by ourselves to obtain an equal vibration sensation to the standard vibration.The data were fitted to the same form of the frequency weighting Wk of ISO 2631-1 with the least square method and optimization of parameters.Result Compared with ISO 2631-1,the frequencies weightings of Chinese young males at 16～80 Hz are significantly higher than those of ISO 2631-1(P<0.005),but there are no significant difference between two frequency weighting contours at other frequencies. Conclusion Chinese young males are more sensitive to vibration at 16～80 Hz in Z axis.