The applicability of catalytic wet-oxidation to CELSS.

The wet-oxidation catalysis of Au, Pd, Pt, Rh or Ru on a ceramic honeycomb carrier was traced in detail by 16 to 20 repetitive batch tests each. As a result, Pt or Pd on a honeycomb carrier was shown to catalyze complete nitrogen gasification as N2. Though the catalysts which realize both complete nitrogen gasification and complete oxidation could not be found, the Ru+Rh catalyst was found to be most promising. Ru honeycomb catalyzed both nitrification and nitrogen gasification.     

Design for a bioreactor with sunlight supply and operations systems for use in the space environment.

An experiment was carried out to determine the characteristics of an operations system that can support fast cultivation of algae at high densities in the weightlessness of space. The experiment was conducted in glass bioreactor tanks, in which light was supplied by radiator rods connected to optical fiber cables. The illumination areas of the tanks were 2600 cm2, 6000 cm2, and 9200 cm2 per liter of solution. The characteristics of O2-CO2 gas exchange, concentration and separation of chlorella in the growth medium, dialysis of ionic salts in the growth medium, etc. were examined. Chloralla ellipsoidea was used in the experiment, yielding the following results: (1) By increasing the ratio of illumination area to volume, growth rates of up to approximately 0.6 g/L h could be obtained in a highly concentrated solution (one that contains 20 g/L or more of algae). (2) The most suitable proportions of carbon dioxide and oxygen gases for growing algae quickly at high concentrations were found to be 10% CO2 and 10% O2 (by volume). (3) There was a high optimum concentration for fast cultivation, and the data obtained resembled the theoretical curve postulated by P. Behrens et al. (4) It was possible to exchange carbon dioxide and oxygen using gas-permeable membrane modules. (5) It was possible to separate the chlorella from the growth medium and recycle the medium.     

Sunlight supply and gas exchange systems in the microalgal bioreactor.

The bioreactor with sunlight supply system and gas exchange systems presented here has proved feasible in ground tests and shows much promise for space use as a CELSS device. Our chief conclusions concerning the specification of total system needed for a life support system for a man in a space station are the following. (1) Sunlight supply system: compactness and low electrical consumption. (2) Bioreactor system: high density and growth rate of chlorella. (3) Gas exchange system: enough for O2 production and CO2 assimilation.     

Survey of CELSS concepts and preliminary research in Japan

Many agricultural and other experiments relating to the development of a Controlled Ecological Life Support System (CELSS) were proposed by scientists throughout Japan in the fall of 1982. To develop concrete experimental concepts from these proposals, the engineering feasibility of each proposal was investigated by a CELLS experiment concept study group under the support of the National Aerospace Laboratory. The conclusions of the group were described in two documents, /1/, /2/. Originally, the study group did not clearly define necessary missions leading to the goal of an operational CELSS for spaceflight. Therefore, the CELSS experiment concept study group met again to clarify the goals of CELSS and to determine three phases to achieve the goals. The resulting phases, or missions, and preliminary proposals and studies needed to develop a CELLS are described herein.     

Hypergravity modulates behavioral nociceptive responses in rats.

Hypergravity (2G) exposure elevated the nociceptive threshold (pain suppression) concomitantly with evoked neuronal activity in the hypothalamus. Young Wistar male rats were exposed to 2G by centrifugal rotation for 10 min. Before and after 2G exposure, the nociceptive threshold was measured as the withdrawal reflex by using the von Frey type needle at a total of 8 sites of each rat (nose, four quarters, upper and lower back, tail), and then rats were sacrificed. Fos expression was examined immunohistochemically in the hypothalamic slices of the 2G-treated rats. When rats were exposed to 2G hypergravity, the nociceptive threshold was significantly elevated to approximately 150 to 250% of the 1G baseline control levels in all the examination sites. The 2G hypergravity remarkably induced Fos expression in the paraventricular and arcuate nuclei of the hypothalamus. The analgesic effects of 2G hypergravity were attenuated by naloxone pretreatment. Data indicate that hypergravity induces analgesic effects in rats, mediated through hypothalamic neuronal activity in the endogenous opioid system and hypothalamo-pituitary-adrenal axis.     

Gravity stress elevates the nociceptive threshold level with immunohistochemical changes in the rat brain.

Young Wistar male rats were exposed to 2G hypergravity by continuous centrifugation for 15 minutes. The nociceptive threshold was measured by using the von Frey type filament on the rat skin surfaces after hypergravity exposure. Following the hypergravity exposure, rats were sacrificed with anesthesia, then perfused and fixed for immunohistochemical examination. The 2G hypergravity elevated the nociceptive threshold up to 2-fold and induced analgesic effects on rats that remained for 2 hours after termination of centrifugation. Expression of Fos-immunoreactive proteins was prominently induced by 2G hypergravity in the arcuate nucleus and the paraventricular nucleus of the hypothalamus. The 15-minute flash exposure to 2G hypergravity induced pain suppression in rats, which might be attributed to change of neuronal activity in rat hypothalamus.     

Effects of neurectomy and tenotomy on the bone mineral density and strength of tibiae.

The right hindlimbs of 5 or 6-week old Wistar male rats were sciatic/femoral neurectomized, tenotomized or sham operated. The rats were sacrificed 2 weeks after the surgery and the tibiae were removed. pQCT measurement was performed on total, cortical, and trabecular bone separately at different regions. Reduction of the bone mineral density by unloading was observed more significantly at metaphysis than at diaphysis due to histological heterogeneity between metaphysis and diaphysis; metaphysis is rich in trabecular bone and diaphysis is abundant in cortical bone. Trabecular bone might be more sensitive to unloading because the reduction rate of volumetric bone mineral density in trabecular bone was approximately 10 times and 3 times larger than that of cortical bone in both neurectomy and tenotomy rats, respectively, Unloading also reduced the cross-sectional area and stress strain index at metaphysis.