Designing a reusable system based on nanodiamonds for biochemical determination of urea.

A reusable system including urease covalently bound to the surface of modified nanodiamonds (MNDs) has been developed for the multiple determination of urea. The immobilized enzyme exhibits functional activity and catalyzes the hydrolysis of urea to yield ammonia. The presence of ammonia is confirmed by the formation of a colored product after the addition of chemical reagents. It was shown that the MNDs-urease complex can function in a wide range of temperatures and pH as well as in deionized water. The complex provides a linear yield of the product at low analyte concentrations and allows the multiple determination of urea in vitro.

Self-restoration as fundamental property of CES providing their sustainability.

Sustainability is one of the most important criteria in the creation and evaluation of human life support systems intended for use during long space flights. The common feature of biological and physicochemical life support systems is that basically they are both catalytic. But there are two fundamental properties distinguishing biological systems: 1) they are auto-catalytic: their catalysts--enzymes of protein nature--are continuously reproduced when the system functions; 2) the program of every process performed by enzymes and the program of their reproduction are inherent in the biological system itself--in the totality of genomes of the species involved in the functioning of the ecosystem. Actually, one cell with the genome capable of the phenotypic realization is enough for the self-restoration of the function performed by the cells of this species in the ecosystem. The continuous microalgal culture of Chlorella vulgaris was taken to investigate quantitatively the process of self-restoration in unicellular algae population. Based on the data obtained, we proposed a mathematical model of the restoration process in a cell population that has suffered an acute radiation damage.

Volatile metabolites of higher plant crops as a photosynthesizing life support system component under temperature stress at different light intensities.

The effect of elevated temperatures of 35 and 45 degrees C (at the intensities of photosynthetically active radiation 322, 690 and 1104 micromoles m-2 s-1) on the photosynthesis, respiration, and qualitative and quantitative composition of the volatiles emitted by wheat (Triticum aestuvi L., cultivar 232) crops was investigated in growth chambers. Identification and quantification of more than 20 volatile compounds (terpenoids--alpha-pinene, delta 3 carene, limonene, benzene, alpha- and trans-caryophyllene, alpha- and gamma-terpinene, their derivatives, aromatic hydrocarbons, etc.) were conducted by gas chromatograph/mass spectrometry. Under light intensity of 1104 micromoles m-2 s-1 heat resistance of photosynthesis and respiration increased at 35 degrees C and decreased at 45 degrees C. The action of elevated temperatures brought about variations in the rate and direction of the synthesis of volatile metabolites. The emission of volatile compounds was the greatest under a reduced irradiation of 322 micromoles m-2 s-1 and the smallest under 1104 micromoles m-2 s-1 at 35 degrees C. During the repair period, the contents and proportions of volatile compounds were different from their initial values, too. The degree of disruption and the following recovery of the functional state depended on the light intensity during the exposure to elevated temperatures. The investigation of the atmosphere of the growth chamber without plants has revealed the substances that were definitely technogenic in origin: tetramethylurea, dimethylsulfide, dibutylsulfide, dibutylphthalate, and a number of components of furan and silane nature.

Bioluminescence in oceanology.

For analytical purposes bioluminescence can be used in three main ways: 1. luminescence measurement of bioluminescent system components isolated in vitro; 2. determination of luminous organisms' reaction to the in vivo test-action; 3. measurement of bioluminescence in marine ecological systems. The majority of the reports of this Symposium are dealing with the first two topics. The aim of our presentation is to draw attention to the third one. The possibilities of bioluminescent analysis are wider than its traditional scheme of applications in the laboratory, when the emitting system is withdrawn from a native source and is placed in a cuvette of the light measuring device. The reverse scheme is also possible, i.e. the device can be introduced into light emitting system such as a marine biocenosis--the community of the sea inhabitants--where we obtain a highly sensitive and rapid means of gaining the information on the vital activity of marine ecosystems, i.e. their spatial structure, rhythms, man's influence upon them, etc. The present communication will consider the possibilities of this form of bioluminescent analysis.

Long-term experiments on man's stay in biological life-support system.

We describe the experimental system having maximal possible closure of material recycling in an ecosystem, including people and plants, which was carried out in a hermetically sealed experimental complex "BIOS-3", 315 m2 in volume. The system included 2 experimentators and 3 phytotrons with plants (total sowing area of 63 m2). Plants were grown with round-the-clock lamp irradiation with 130 Wm-2 PAR intensity. The plants production was food for people. Water exchange of ecosystem, as wall as gas exchange, was fully closed excluding liquids and gas samples taken for chemical analysis outside the system. The total closure of material turnover constituted 91%. Health state of the crew was estimated before, during and after the experiment. A 5-months period did not affect their health. The experiments carried out prove that the closed ecosystem of "man-plants" is a prototype of a life-support system for long-term space expeditions.

Life support system with autonomous control employing plant photosynthesis.

This research was aimed at obtaining a closed control system. This was achieved by placing all the technological processes providing for human vital activities within the hermetically sealed space, and by transferring the entire control and guidance of these processes to people inhabiting the system. In contrast to existing biological life support systems, man has been included not only as a participant of metabolism, but as an operator who is the central figure in collecting information, making decisions and controlling all technological processes. To tackle this problem, the "BIOS-3" experimental complex was created for performing long-term experiments using different structures of biological life-support system. The experiment lasted six months and consisted of three stages. During the first stage the system was comprised of two equivalent phytotrons with the culture of wheat and an assortment of vegetable plants, and the living compartment. At the second stage, one of the phytotrons was removed while a compartment of chlorella cultivators was introduced. The third stage differed from the second, the former using wheat phytotron and the latter employing phytotron with an assortment of vegetable cultures. Three men inhabited the system simultaneously. The experiment demonstrated that a biological life support system controlled autonomously from the inside is feasible within a small confined space. However, immunological and microbiological research shows, that the medium created by the system is not fully adequate for man. In conclusion, some prospects have been outlined for further studies of biological life support systems.

Theoretical and experimental decisions in the creation of an artificial ecosystem for human life support in space.

All of man's former space flights were not real ventures into space in the biological sense, as his life was supported with unregenerated earth supplies. The coming stage of space exploration requires man's long existence in the cosmos and on the other planets. This stage of man's activity outside the earth become possible only by creating small man-made ecosystems, permitting the support of his metabolism by the recycling of substances of the terrestrial biosphere. Creation of such systems is a new scientific and technical task. Man-made ecosystems are a new product of man's activity, which have no complete analogy, either in nature, or in technology. Stochastic mechanisms, which stabilize biogeocenosis, cannot be effective in small ecosystems. A technique of parametric control over biosynthesis made it possible to calculate, and put to practice, an ecosystem for man with a cyclic regeneration of the atmosphere, water and, partially, food. The specific bio-technological properties of small man-made ecosystems are being analysed. The possibility of their application for man's excursions into space and for the settlement of other planets is being considered.

Experimental biological life support system. II. Gas exchange between man and microalgae culture in a 30-day experiment.

The experiments of a prolonged stay by man in a closed atmosphere regenerated by a biological method have been examined. In the course of the experiment, a study of isolated and compatible links of a gas-closed system of "man-microalga" was carried out. The main emphasis was placed on the study of the biological compatibility of the links of the system and primarily of the effect of gaseous metabolites built up in the system of man. The dynamics of a number of physiological parameters of the man under experiment were studied. The regular functional tests of the respiratory and cardiovascular system were carried out. An electrocardiogram was made and respiratory rate and pulse were registered. Oxyhemogram investigations and laboratory clinical examinations were also performed, as well as some psychological tests. It was possible to equalize the respiratory gas ratio by the composition of the cultural environment for algae and by the nutrition ration of man. This eliminates time limit for the life maintenance system, especially on microalga photosynthesis. The results of the experiments permit drawing a conclusion on the biological compatibility of man and microalgae in their prolonged direct gas contact. Thus the possibility of obtaining a balanced atmosphere regeneration system on the basis of counterbalanced gas exchange between man and controlled photosynthesis of algae has been proven experimentally.

Experimental biological life support system. I. Continuous cultivation of algae as a link of a closed ecosystem.

According to the opinion of many researchers, a culture of microalgae may serve as a regenerator of atmosphere in the cabin of a spaceship. To use microalgae for these objectives, it was necessary to have an automatic unit possessing a high productivity of the cultivation process. This unit, containing a minimum of equipment, enables carrying on for an unlimited time the cultivation of algae without a drop in their productivity. The unit meeting these requirements (the cultivator) was developed by the authors and will be described in the presentation. The stability of the microalga photosynthetic system is characterized by the fact that after 70% biosynthesis repression by the ultraviolet radiation, a full regeneration of the productivity level takes place within 24 hours. In our experiments the system was functioning with the stable estimated productivity for many days (up to two months without interruption). During the process, no biological inhibitions to permanent performance and further prolongation of its life were found. As to the productivity, stability and control, the described biotechnological method may appear to be useful as a link of the closed ecosystem.