Lossy chaotic electromagnetic reverberation chambers: Universal statistical behavior of the vectorial field.

The effective Hamiltonian formalism is extended to vectorial electromagnetic waves in order to describe statistical properties of the field in reverberation chambers. The latter are commonly used in electromagnetic compatibility tests. As a first step, the distribution of wave intensities in chaotic systems with varying opening in the weak coupling limit for scalar quantum waves is derived by means of random matrix theory. In this limit the only parameters are the modal overlap and the number of open channels. Using the extended effective Hamiltonian, we describe the intensity statistics of the vectorial electromagnetic eigenmodes of lossy reverberation chambers. Finally, the typical quantity of interest in such chambers, namely, the distribution of the electromagnetic response, is discussed. By determining the distribution of the phase rigidity, describing the coupling to the environment, using random matrix numerical data, we find good agreement between the theoretical prediction and numerical calculations of the response.

Experimental Width Shift Distribution: A Test of Nonorthogonality for Local and Global Perturbations.

The change of resonance widths in an open system under a perturbation of its interior has been recently introduced by Fyodorov and Savin [Phys. Rev. Lett. 108, 184101 (2012)] as a sensitive indicator of the nonorthogonality of resonance states. We experimentally study universal statistics of this quantity in weakly open two-dimensional microwave cavities and reverberation chambers realizing scalar and electromagnetic vector fields, respectively. We consider global as well as local perturbations, and also extend the theory to treat the latter case. The influence of the perturbation type on the width shift distribution is more pronounced for many-channel systems. We compare the theory to experimental results for one and two attached antennas and to numerical simulations with higher channel numbers, observing a good agreement in all cases.

Some methods for human liquid and solid waste utilization in bioregenerative life-support systems.

Bioregenerative life-support systems (BLSS) are studied for developing the technology for a future biological life-support system for long-term manned space missions. Ways to utilize human liquid and solid wastes to increase the closure degree of BLSS were investigated. First, urine and faeces underwent oxidation by Kudenko's physicochemical method. The products were then used for root nutrition of wheat grown by the soil-like substrate culture method. Two means of eliminating sodium chloride, introduced into the irrigation solution together with the products of urine oxidation, were investigated. The first was based on routine electrodialysis of irrigation water at the end of wheat vegetation. Dialysis eliminated about 50% of Na from the solution. This desalinization was performed for nine vegetations. The second method was new: after wheat cultivation, the irrigation solution and the solution obtained by washing the substrate containing mineral elements not absorbed by the plants were used to grow salt-tolerant Salicornia europaea L. plants (saltwort). The above-ground biomass of this plant can be used as a food, and roots can be added to the soil-like substrate. Four consecutive wheat and Salicornia vegetations were cultivated. As a result of this wheat and Salicornia cultivation process, the soil-like substrate salinization by NaCl were considerably decreased.

Synthesis of biomass and utilization of plants wastes in a physical model of biological life-support system.

The paper considers problems of biosynthesis of higher plants' biomass and "biological incineration" of plant wastes in a working physical model of biological LSS. The plant wastes are "biologically incinerated" in a special heterotrophic block involving Californian worms, mushrooms and straw. The block processes plant wastes (straw, haulms) to produce soil-like substrate (SLS) on which plants (wheat, radish) are grown. Gas exchange in such a system consists of respiratory gas exchange of SLS and photosynthesis and respiration of plants. Specifics of gas exchange dynamics of high plants--SLS complex has been considered. Relationship between such a gas exchange and PAR irradiance and age of plants has been established. Nitrogen and iron were found to the first to limit plants' growth on SLS when process conditions are deranged. The SLS microflora has been found to have different kinds of ammonifying and denitrifying bacteria which is indicative of intensive transformation of nitrogen-containing compounds. The number of physiological groups of microorganisms in SLS was, on the whole, steady. As a result, organic substances--products of exchange of plants and microorganisms were not accumulated in the medium, but mineralized and assimilated by the biocenosis. Experiments showed that the developed model of a man-made ecosystem realized complete utilization of plant wastes and involved them into the intrasystem turnover.

Identification of a metabolic network structure representative of Arthrospira (spirulina) platensis metabolism.

A comprehensive network structure for the autotrophic growth of Arthrospira platensis is proposed. The metabolic network was built up with 121 reactions and 134 metabolites including biomass synthesis, production of a growth-associated exopolysaccharide, and energy aspects. The model supports the existence of a metabolic shunt of PEP to pyruvate through PEP carboxylase, NAD(+)-dependent malate dehydrogenase and malic enzyme to convert NADH,H(+) into NADPH,H(+). A limit in Arthrospira growth metabolism due to NADH,H(+) balancing is evidenced, explaining why the maximal light-dependent mass yield of the growth-associated exopolysaccharide was 0.51 kg EPS kg(-1) biomass, consistent with experimental results.

Mass exchange in an experimental new-generation life support system model based on biological regeneration of environment.

An experimental model of a biological life support system was used to evaluate qualitative and quantitative parameters of the internal mass exchange. The photosynthesizing unit included the higher plant component (wheat and radish), and the heterotrophic unit consisted of a soil-like substrate, California worms, mushrooms and microbial microflora. The gas mass exchange involved evolution of oxygen by the photosynthesizing component and its uptake by the heterotroph component along with the formation and maintaining of the SLS structure, growth of mushrooms and California worms, human respiration, and some other processes. Human presence in the system in the form of "virtual human" that at regular intervals took part in the respirative gas exchange during the experiment. Experimental data demonstrated good oxygen/carbon dioxide balance, and the closure of the cycles of these gases was almost complete. The water cycle was nearly 100% closed. The main components in the water mass exchange were transpiration water and the watering solution with mineral elements. Human consumption of the edible plant biomass (grains and roots) was simulated by processing these products by a unique physicochemical method of oxidizing them to inorganic mineral compounds, which were then returned into the system and fully assimilated by the plants. The oxidation was achieved by "wet combustion" of organic biomass, using hydrogen peroxide following a special procedure, which does not require high temperature and pressure. Hydrogen peroxide is produced from the water inside the system. The closure of the cycle was estimated for individual elements and compounds. Stoichiometric proportions are given for the main components included in the experimental model of the system. Approaches to the mathematical modeling of the cycling processes are discussed, using the data of the experimental model. Nitrogen, as a representative of biogenic elements, shows an almost 100% closure of the cycle inside the system. The proposed experimental model of a biological system is discussed as a candidate for potential application in the investigations aimed at creating ecosystems with largely closed cycles of the internal mass exchange. The formation and maintenance of sustainable cycling of vitally important chemical elements and compounds in biological life support systems (BLSS) is an extremely pressing problem. To attain the stable functioning of biological life support systems (BLSS) and to maintain a high degree of closure of material cycles in than, it is essential to understand the character of mass exchange processes and stoichiometnc proportions of the initial and synthesized components of the system.

Light intensity and production parameters of phytocenoses cultivated on soil-like substrate under controlled [correction of controled] environment conditions.

To increase the degree of closure of biological life support systems of a new generation, we used vermicomposting to involve inedible phytomass in the intra-system mass exchange. The resulting product was a soil-like substrate, which was quite suitable for growing plants (Manukovsky et al. 1996, 1997). However, the soil like substrate can be regarded as a candidate for inclusion in a system only after a comprehensive examination of its physical, chemical, and other characteristics. An important criterion is the ability of the soil-like substrate to supply the necessary mineral elements to the photosynthesizing component under the chosen cultivation conditions. Thus, the purpose of this work was to study the feasibility of enhancing the production activity of wheat and radish crops by varying the intensity of photosynthetically active radiation, without decreasing the harvest index. The increase of light intensity from 920 to 1150 micromoles m-2 s-1 decreased the intensity of apparent photosynthesis of the wheat crops and slightly increased the apparent photosynthesis of the radish crops The maximum total and grain productivity (kg/m2) of the wheat crops was attained at the irradiance of 920 micromoles m-2 s-1. Light intensity of 1150 micromoles m-2 s-1 decreased the productivity of wheat plants and had no significant effect on the productivity of the radish crops (kg/m2) as compared to 920 micromoles m-2 s-1. The qualitative and quantitative composition of microflora of the watering solution and substrate was determined by the condition of plants, developmental phase and light intensity. By the end of wheat growth under 1150 micromoles m-2 s-1 the numbers of bacteria of the coliform family and phytopathogenic bacteria in the watering solution and substrate were an order of magnitude larger than under other illumination conditions. The obtained data suggest that the cultivation of plants in a life support system on soil-like substrate from composts has a number of advantages over the cultivation on neutral substrates, which require continual replenishment of the plant nutrient solution from the system's store to complement the macro- and micro-elements. Yet, a number of problems arise, including those related to the controlling of the production activity of the plants by the intensity of photosynthetically active radiation. It is essential to understand why the intensity of production processes is limited at higher irradiation levels and to overcome the factors responsible for this, so that the soil-like substrate could have an even better chance in the competition for the best plant cultivation technology to be used in biological life support systems.

Recycling efficiencies of C, H, O, N, S, and P elements in a Biological Life Support System based on microorganisms and higher plants.

MELiSSA is a microorganism based artificial ecosystem conceived as a tool for understanding the behavior of ecosystems and developing the technology for future Manned Space Missions. MELiSSA is composed of four compartments colonized by the microorganisms required by the function of this ecosystem : breakdown of waste produced by men, regeneration of atmosphere and biosynthesis of edible biomass. This paper reports the mass balance description of a Biological Life Support System composed of the MELiSSA loop and of a Higher Plant Compartment working in parallel with the photosynthetic Spirulina compartment producing edible biomass. The recycling efficiencies of the system are determined and compared for various working conditions of the MELiSSA loop with or without the HPC.

Energy model and metabolic flux analysis for autotrophic nitrifiers.

The behavior of pure cultures of nitrifying microorganisms under autotrophic growth operating conditions was investigated and the relations between their energy metabolism and their anabolism analyzed by means of metabolic network computation. The description of the metabolism of the nitrifiers is extended to their energy metabolism by introducing compartmentalization (cytoplasmic and periplasmic sides) and studying coupling between the electron transport chain and the proton gradient generation. The energy model of Nitrosomonas and Nitrobacter was developed based on the oxidoreduction reactions known to be involved. The electron transport chains and the associated proton translocation for these models are described. Several possible hypotheses are analyzed and discussed concerning the thermodynamic consistency of all the oxidoreduction reactions. For Nitrosomonas, the most delicate point is the second step of hydroxylamine oxidation. For Nitrobacter a new energy model is proposed in which NO plays an important role as node in the distribution of electrons from NO(2)(-) oxidation to the membrane electron transport chain. The compartmentalization enables us to consider a proton gradient dissipation flux as the expression of the overall energy loss in metabolic analysis (the so-called maintenance phenomena). The energy model (electron transport chain, proton gradient) is associated with an overall description of the metabolism of Nitrosomonas and Nitrobacter in terms of metabolic flux calculation. This representation demonstrates that a maintenance in nitrifiers expressed as a proton leak is no higher than for other aerobes. The yields calculated from the energy models integrated with the metabolic models of nitrifiers are consistent with the experimental yields in the literature.

Special transformation processes using fungal spores and immobilized cells.

Although many microbial processes have been described which are able to produce interesting aroma compounds, the number of industrial applications are limited. Reasons for this are in most cases low final product yield, low biotransformation rates, substrates and/or end-products inhibition, toxicity towards the microorganisms themselves and difficulties of recovery from the bioreaction mixture. This means that the development of specific catalysts and processes is an important challenge for researchers in this field. This review presents two special kinds of catalysts, fungal spores and immobilized cells, with emphasis on their production and on their use in the production of aroma compounds. The production of fungal spores by solid state fermentation is described in greater detail. In the second part, this review also offers examples of development of three production processes, the production of methyl ketones of spores of Penicillium roquefortii, the hydroxylation of beta-ionone by immobilized Aspergillus niger cells, and the production of alkyl pyrazines by bacteria in liquid and solid media. For each of these processes, the analysis of limiting steps-biological and/or physico-chemical-is presented and the significant role of process conditions to increase aroma yield is discussed.

Metabolic flux distribution in Corynebacterium melassecola ATCC 17965 for various carbon sources.

The distribution of carbon in the metabolic network of a bacterial cell was estimated by a mass-balance-based intracellular flux computation method. It was applied to the growth phase of Corynebacterium melassecola, a glutamic acid producing bacterium, using experimental production yields of biomass, lactate and acetate measured during batch cultures on glucose, fructose, and various mixtures of both sugars. This flux computation method identifies the direction of the 86 reactions that ensure proper metabolic function during the growth phase of C. melassecola. Flux ratios allow comparison of calculated and relevant experimental yields. The results highlight the key influence of the biomass production yield Y(X-O(2) ) on the overall distribution of carbon; the proportion of carbon drained in the pentose-P pathway fell from a value in the range of 54% to 47% on media containing glucose (Y(X-O(2) ) = 1.75 to 1.56 g X/g O(2)) to 37% on fructose medium (Y(X-O(2) ) = 1.36 g X/g O(2)). The highest maintenance requirement was calculated on fructose medium (J(m) = 290 mol ATP/100 mol fructose) which must be connected to a lower efficiency of cell multiplication observed on this substrate. Another important result was that the significant decreases in experimental values of production yields and rates observed on fructose medium which were related to the operation of the FBPase. In particular, it was estimated that, as long as the proportion of glucose in the carbon source remains above 22% (78% fructose), the operation of the FBPase is not necessary and the bacteria exhibit behavior similar to that observed on glucose alone; this result is consistent with experimental observations.

MELISSA: a potential experiment for a precursor mission to the Moon.

MELISSA (Micro-Ecological Life Support System Alternative) has been conceived as a micro-organism based ecosystem intended as a tool for developing the technology for a future artificial ecosystem for long term space missions, as for example a lunar base. The driving element of MELISSA is the recovering of edible biomass from waste, CO2, and minerals with the use of sun light as energy source. In this publication, we focus our attention on the potential applications of MELISSA for a precursor mission to the Moon. We begin by a short review of the requirements for bioregenerative Life Support. We recall the concept of MELISSA and the theoretical and technical approaches of the study. We present the main results obtained since the beginning of this activity and taking into account the requirements of a mission to the Moon we propose a preliminary experiment based on the C cycle of the MELISSA loop.

Behavior of spores of Penicillium roquefortii during fed-batch bioconversion of octanoic acid into 2-heptanone.

The bioconversion of octanoic acid into 2-heptanone by spores of Penicillium roquefortii is performed using a fed-batch technique with pH control by addition of the liquid substrate itself. The early stage of this process takes place with a high bioconversion rate and high yield. These values then decrease as a result of germination and growth the biocatalyst. An optimization strategy for the process would thus be to improve the characteristics of this first period, i.e., increase its duration and the reaction rate. An increase in duration is evidenced in two cases: (I) under oxygen limitation: and (ii) when the spore content in the medium is less than 10(7) spores/mL. These conditions give insufficient overall bioconversion rates: better optimization should be achieved without oxygen limitation and with high spore content. Characterization of the first period by material and bioenergetic balances suggests that an increase in the ethanol content of the medium, which acts as an energy source and a permeabilizer, and the use of specific inhibitor of the Krebs cycle, may be a way to further improve the biocatalyst performance and stability.

Characterization of water distribution in cell pellets using nonlabeled sodium thiosulfate as an interstitial space marker.

A procedure for determination of the intracellular water content of cells using a single, nonlabeled solute as an interstitial space marker is proposed. Sodium thiosulfate, which can be accurately assayed by a tritrimetric method, is found to be a good compound for this purpose. Cells are recovered both by filtration and centrifugation; the two techniques gave the same value for internal water, i.e., 650 mg of H2O/g of wet matter for Corynebacterium melassecola and 390 mg of H2O/g of wet matter for Penicillium roquefortii spores. The methodology of data handling, based on a regression technique, is also described. It allows one to obtain very reliable results and should be useful for any marker.

Characterization of the growth and sporulation behavior of Penicillium roquefortii in solid substrate fermentation by material and bioenergetic balances.

When Penicillium roquefortii is grown on two kinds of buckwheat, exhibiting a low [0.85 g water/g dry matter (DM), buckwheat A] and a high [1.5 g water/g initial dry matter (IDM), buckwheat B] water content, a marked difference in the mode of development of the fungus is observed. Material balances for buckwheat A show that growth does not stop because of nutrient exhaustion. Analysis of water balance shows that active growth proceeds with a permanent limitation by the turgor potential which disappears when the water activity of the substrate is close to 0.96, thus arresting growth. This limitation causes intensive water excretion from the system due to the lowering of the water activity of the substrate. The water content of the mycelium thus decreases from 79% at the beginning of the cultivation to 74% when the growth stops. This is linked to a substantial oxidative metabolism and a high sporulation efficiency, close to 0.85. The spores obtained have a low dry weight and a reduced nitrogen content. In the case of buckwheat B, the active growth is shown to stop because of available mineral nitrogen depletion. No significant decrease in the water activity of the substrate is found during the protein synthesis, and the turgor potential remains high at the end of this period. Culture proceeds with new wall synthesis; the sporulation efficiency remains high and the spores obtained exhibit a high dry weight and a high nitrogen content. The bioenergetic balances show that the P/O ratio varies with the kind of substrate used; its value is close to 1.56 for the low water medium and to 2.21 for the high one. The ATP yield Z is always close to 1, and fungal development occurs with limitations of both anabolism and catabolism on buckwheat B and only of anabolism and catabolism on buckwheat B and only of anabolism on buckwheat A.

Batch and continuous 2-heptanone production by Ca-alginate/Eudragit RL entrapped spores of Penicillium roquefortii.

The synthesis of 2-heptanone from octanoic acid by Caalginate/Eudragit RL entrapped spores of Penicillium roquefortii is performed in batch and continuous reactions. The measurement of the HCI solution needed to overcome the pH increase during the course of a reaction allows continuous monitoring of the reaction progress of batch as well as continuous processes without any aliquot sampling. The hydration of the biocatalyst prior to a bioconversion performance is of major importance to achieve reproducible results. A continuous reaction carried out at pH 6.5 for one month demonstrates the feasibility of such a process and shows that the reaction occurs with a Michaelian behavior, with K(M) = 1.82 mmol/L and r(sm) = 0.82 mmol/L h, and no intraparticle diffusion limitation is found. The complex behavior of the spores during batch reactions makes this kind of operation unsuitable for kinetic studies.

Modelling Xanthomonas campestris batch fermentations in a bubble column.

Rate and yield expressions relating to biomass and xanthan formation and to nitrogen, glucose, and oxygen consumption were established for Xanthomonas campestris batch fermentations in a bubble column. Microbial growth was described by the logistic rate equation, characterized by a maximum specific growth rate mu(M) = 0.5 h(-1) and a maximum attainable cell concentration provided by nitrogenous compounds. With regard to carbon metabolism, the decrease with time in experimental yields and in the experimental specific rates of xanthan production and glucose assimilation demonstrated the inadequacy of the Luedeking-Piret model. These decreases were connected to the simultaneous drop in dissolved-oxygen tension observed during xanthan synthesis. The knowledge of metabolic pathways and energetic balance were used to establish the relationships between substrate utilization, ATP generation, and xanthan production. The model was structured by assuming the oxygen limitation of both the respiration rate and the efficiency of the oxidative phosphorylation mechanism (P/O ratio). Consequently, the specific rates and yield expressions became dependent on the dissolved-oxygen tension, i.e., of the volumetric oxygen transfer in the fermentor.

Measurement of effective diffusivities of ionic and non-ionic solutes through beef and pork muscles using a diffusion cell.

A diffusion cell in conjunction with a new mathematical model was used to measure the apparent diffusion coefficients of sodium chloride, potassium nitrate and glucose through beef semitendinosus and pork longissimus dorsi muscles. The apparent diffusion coefficient was obtained within less than 180 min with a coefficient of variation less than 10% in most cases. The influence of temperature can be adequately explained by the Arrhenius-type law with activation energy between 19 and 26 kJ/mol depending on the diffusant. However, these values were not significantly different. Finally, we showed that the apparent diffusion coefficient of sodium chloride is not affected by the direction of the muscle fibre to the axes of diffusion while glucose diffusion parallel to the muscle fibre can be three times greater than diffusion at a right angle to the muscle fibre.

Spore production of Penicillium roqueforti by solid state fermentation: Stoichiometry, growth and sporulation behavior.

The development of Penicillium roqueforti on buckwheat seeds proceeds roughly into four steps, involving a lag phase and three growth phases. First, it appears as a spore germination and external colonization of the grains by the mycelium. Then, mainly external sporulation and internal colonization of the seeds occur and finally internal sporulation takes place. The Stoichiometry of the growth and the sporulation is established. Kinetic experiments performed in a fixed bed reactor show that the growth of the microorganism (biomass production) may be estimated by the protein content of the medium. This growth occurs with a very low mu(max) value close to 0.030 h(-1). The chitin content of the medium is an indicator of the sporulation, just as the metabolic liquor (mainly water) produced during the course of a cultivation. The values of the observed respiratory quotient are close to those predicted by stoichiometry.