Technology for large space systems: A special bibliography with indexes (supplement 03)

A bibliography containing 217 abstracts addressing the technology for large space systems is presented. State of the art and advanced concepts concerning interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments are represented

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 199

This bibliography lists 82 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1979

Bacterial ion effects and their relation to salt tolerance

Previously held under moratorium from 25 June 2018 until 24 February 2022Extremophiles are organisms that are able to tolerate conditions that would otherwise inhibit or even kill non-extremophilic organisms – such extremes include acidity, high salt concentrations, high temperatures and high pressure. Specifically, halophiles are organisms that have a requirement for high concentrations of salt for growth. These organisms have been found to use either of two adaptation strategies, known as ‘salt-in’ (accumulation of inorganic ions) and ‘salt-out’ (removal of inorganic ions and accumulation of neutral molecules). In the current study, the relationship between the level of salt tolerance of an organism and its ion metabolism was investigated in order to gain insight into halo-adaptation and mechanisms of bacterial salt tolerance. This was accomplished by analysing the effects of a variety of salts (21 different combinations) on a halophile (Salinibacter ruber), non-halophile (Escherchia coli) and halotolerant (Echinicola vietnamensis) organism, which was achieved via an analysis of the effects of salts on bacterial growth, intracellular cation accumulation, enzymatic activity and and bioinformatics analysis. It was found that cation preferences were directly related to the level of salt tolerance of the organism, which is hypothesised to be a product of proteome acidity as well as the presence of specific membrane cation transporters. Specifically, the preference of S. ruber for the higher charge density Na+ over K+ may be rationalised based on the Hofmeister effect –i.e. this cation may provide better stabilisation of intracellular enzymes at the optimal salt concentrations for growth of S. ruber, but may be destabilising if accumulated at higher concentrations, and for non-salt adapted organisms. The ability of E. vietnamensis to tolerate and utilise many non-physiological ions supports this theory. Additionally, E. vietnamensis was postulated to use a ‘hybrid’ osmotic adaptation strategy – this organism may have industrial applications due to its large salt concentration tolerance range and high tolerance for non-physiological cations. Crucially, it was also found that E. vietnamensis and S. ruber contained membrane cation transporters that may be essential for their salt tolerance, giving insight into the essential nature of these proteins for the possession of salt resistance, which may have potential to be utilised for the transfer of salt- tolerance to commercially important organisms. Finally, one specific salt combination tested, equimolar LiCl + KBr proved to totally inhibit bacterial growth and may show promise as an antimicrobial agent, for which a patent application has been initiated. The results of the current study can have various applications, including those within industry, medicine and astrobiology.Extremophiles are organisms that are able to tolerate conditions that would otherwise inhibit or even kill non-extremophilic organisms – such extremes include acidity, high salt concentrations, high temperatures and high pressure. Specifically, halophiles are organisms that have a requirement for high concentrations of salt for growth. These organisms have been found to use either of two adaptation strategies, known as ‘salt-in’ (accumulation of inorganic ions) and ‘salt-out’ (removal of inorganic ions and accumulation of neutral molecules). In the current study, the relationship between the level of salt tolerance of an organism and its ion metabolism was investigated in order to gain insight into halo-adaptation and mechanisms of bacterial salt tolerance. This was accomplished by analysing the effects of a variety of salts (21 different combinations) on a halophile (Salinibacter ruber), non-halophile (Escherchia coli) and halotolerant (Echinicola vietnamensis) organism, which was achieved via an analysis of the effects of salts on bacterial growth, intracellular cation accumulation, enzymatic activity and and bioinformatics analysis. It was found that cation preferences were directly related to the level of salt tolerance of the organism, which is hypothesised to be a product of proteome acidity as well as the presence of specific membrane cation transporters. Specifically, the preference of S. ruber for the higher charge density Na+ over K+ may be rationalised based on the Hofmeister effect –i.e. this cation may provide better stabilisation of intracellular enzymes at the optimal salt concentrations for growth of S. ruber, but may be destabilising if accumulated at higher concentrations, and for non-salt adapted organisms. The ability of E. vietnamensis to tolerate and utilise many non-physiological ions supports this theory. Additionally, E. vietnamensis was postulated to use a ‘hybrid’ osmotic adaptation strategy – this organism may have industrial applications due to its large salt concentration tolerance range and high tolerance for non-physiological cations. Crucially, it was also found that E. vietnamensis and S. ruber contained membrane cation transporters that may be essential for their salt tolerance, giving insight into the essential nature of these proteins for the possession of salt resistance, which may have potential to be utilised for the transfer of salt- tolerance to commercially important organisms. Finally, one specific salt combination tested, equimolar LiCl + KBr proved to totally inhibit bacterial growth and may show promise as an antimicrobial agent, for which a patent application has been initiated. The results of the current study can have various applications, including those within industry, medicine and astrobiology

Utilization of non-conventional systems for conversion of biomass to food components

Described here is work accomplished in investigating the potential use of micro-algae in yielding useful macronutrients for closed ecological life support systems in space habitats. Analysis of the chemical composition of the blue-green alga Synechoccus 6311 was done in the present work, and was compared to values found in previous work on the green algae Scenedesmus obliquus. Similar values were obtained for proteins, and lower values for nucleic acids and lipids. A second part of the work involved fabrication of food products containing various levels of incorporated algae (S. obliquus) proteins and/or lipids. Protein isolate was incorporated into a variety of food products such as bran muffins, fettuccine (spinach noodle imitation), and chocolate chip cookies. In the sensory analysis, the greenish color of the bran muffins and cookies was not found to be objectionable. The mild spinachy flavor was less detectable in chocolate chip cookies than in bran muffins. The color and taste of the algae noodles were found to be pleasant and compared well with commercially available spinach noodles

Chemical synthesis, cloning and expression of a gene encoding systemin, a proteinase inhibitor-inducing factor

Bibliography: leaves 116-120.Wound-inducible proteinase inhibitors in plants elicit a defence mechanism by inactivating the proteinases of insects. This triggers a feedback mechanism causing overproduction of digestive enzymes together with a decrease in appetite, leading to starvation. System in, a polypeptide proteinase inhibitor-inducing factor, when applied to cut stems of young tomato plants induces the accumulation of inhibitors in a manner similar to the normal wounding response. We designed and synthesised the minus strand oligonucleotide template complementary to the system in DNA sequence using Escherichia coli codon preferences. The double stranded fragment encoding the 18 amino acid residue systemin was cloned into pUCJ 8 for amplification and subcloning into pMAL-pk for expression as a maltose binding-fusion protein. The recombinant systemin was released by enterokinase and isolated by HPLC. After further purification, the physical characteristics including amino acid composition, peptide sequence and molecular weight of r-systemin were determined. When the recombinant peptide was applied to young tomato plants, it induced the accumulation of proteinase inhibitor I messenger RNA

Empirical modelling as a new paradigm for educational technology

Educational technology has yet to deliver the benefits or successes that were expected in educational practice, especially in relation to issues other than the communication and delivery of teaching materials. Evidence suggests that these difficulties stem from the mismatch between formalised virtual learning environments and everyday sensemaking and between the rich potential for enhanced learning afforded by new technology and the constraints of old-style educational practice. In addressing this mismatch, some commentators suggest that the primary need is for a new culture of educational practice-and even that such a culture is already emerging, and others identify the need for a new paradigm for educational technology. The aim of this thesis is to explore the potential for a new paradigm for educational technology based on the principles and tools of Empirical Modelling (see http://dcs.warwick.ac.uk/modelling). The thesis builds upon previous research on Empirical Modelling as a constructionist approach to learning, and in particular Roe's doctoral thesis 'Computers for learning: an Empirical Modelling perspective'. Roe's treatment of Empirical Modelling can be viewed as generalising the use of spreadsheets for learning through applying 'programming by dependency' within the framework of existing educational practice. In contrast, this thesis is concerned at a more fundamental level with the contribution that Empirical Modelling can make to technology enhanced learning that may lead to new educational practices. In particular, it identifies eight significant characteristics of learning that are well-matched to Empirical Modelling activity, and associates these with experimental, flexible and meaningful strands in learning. The credentials of Empirical Modelling as a potential new foundation for educational technology are enhanced by demonstrating that Empirical Modelling is radically different from traditional software development and use. It provides a methodology for modelling with dependency that is more closely related to the use of spreadsheets for learning. The thesis elaborates on the relationship between Empirical Modelling and learning in a variety of different contexts, ways and applications. Three examples drawn from computer science higher education are explored to emphasise the experimental, flexible and meaningful characteristics of Empirical Modelling. This discussion of Empirical Modelling in a specific educational context is complemented by an investigation of its relevance to learning in a wider context, with reference to a broad range of subjects, to specific issues in language learning, and to the topics of lifelong learning and collaborative learning. Although the application of Empirical Modelling for learning is as yet too immature for large scale empirical studies, its potential is evaluated using informal empirical evidence arising from Empirical Modelling practice at Warwick. The sources for this evaluation are well-established teaching activities relating to Empirical Modelling in Computer Science at the University of 'Warwick, comprising an introductory module and a number of final year undergraduate projects. The thesis concludes by considering the extent to which Empirical Modelling can go beyond the support for constructionism envisaged by Roe, to address the broader agenda of supporting constructivist learning using computers. To this end, a close relationship between Empirical Modelling and a vision of constructivism recently set out by Bruno Latour in his paper 'The Promises of Constructivism' is demonstrated

Mechanism of Protein Charging and Supercharging in Electrospray Ionization: Molecular Dynamics Simulations and Experimental Investigations

Electrospray ionization mass spectrometry (ESI-MS) is a powerful technique for investigating protein structures, conformations, and interactions. Despite its widespread use, many fundamental aspects of ESI remain poorly understood. In this thesis, we use a combination of molecular dynamics (MD) simulations and experiments to gain insights into the hidden complexities of ESI-MS. Chapter 2 discusses the topic of salt-induced protein signal degradation. Salts such as NaCl, CsCl, and tetrabutyl ammonium chloride (NBu4Cl) interfere with MS data acquisition, leading to adduct formation and signal suppression. MD simulations provide an explanation for these salt interferences. Signal suppression can be broken down into two effects, i.e., i) peak splitting due to adduction, ii) “genuine” signal suppression. The results obtained may be helpful to anticipate solution conditions for improved protein analyses by ESI-MS. The two subsequent Chapters examine the mechanism of native protein supercharging, which represents a highly contentious topic. Chapter 3 uses MD simulations along with ion mobility mass spectrometry (IMS/MS). Holo-myoglobin (hMb) serves as a model protein, along with the two most common supercharging agents (SCAs), sulfolane and m-nitrobenzyl alcohol (m-NBA). Our data show that supercharging is caused by ‘charge trapping’ that arises from solvent segregation in the droplets, resulting in the formation of SCA-enriched surface layer and an aqueous core. The key factor to charge trapping is the differential solubility of charge carriers (such as Na+ or NH4+) in water compared to the exterior SCA layer. After complete water evaporation, residual SCA molecules impede charge carrier release from the droplet, and any remaining charge carriers will bind to the protein. Slow SCA evaporation eventually releases a highly charged protein into the gas phase that may undergo Coloumbic unfolding. These findings represent the first atomistic view of protein supercharging. In Chapter 4, we explore the mechanism of native protein supercharging from a different perspective using a crown ether (18C6). 18C6 selectively binds Na+/NH4+ and enhances their solubility in the SCA layer. This facilitates the release of 18C6-bound charge carriers from the droplet. As a result, 18C6 suppressed supercharging effect, as confirmed both in MD simulations and experimentally. These data support the proposed charge trapping mechanism for both proteins and dendrimers. A chain ejection model (CEM) has been proposed to account for the protein ESI behavior under such non-native conditions. The CEM envisions that unfolded proteins are driven to the droplet surface by hydrophobic and electrostatic factors, followed by gradual ejection via intermediates where droplets carry extended protein tails. Thus far it has not been possible to support the CEM through MD simulations. In Chapter 5 we overcome these difficulties and use MD simulations along with ion mobility experiments to confirm CEM as an ejection mechanism for unfolded proteins. Overall, the modeling and experimental work in this thesis provides unprecedented insights into the mechanism of protein charging and supercharging during ESI

Technology for large space systems: A bibliography with indexes (supplement 12)

A bibliography listing 516 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1, 1984 and December 31, 1984 is presented. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design in the area of Large Space System Technology. Subject matter is grouped according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

EFFECTIVE REMOVAL OF METHYLENE BLUE DYE BY A NOVEL 4-VINYLPYRIDINE-CO-METHACRYLIC ACID CRYOGEL: KINETIC, ISOTHERM, AND BREAKTHROUGH STUDIES

BACKGROUND: Industrial streams are the source of increasing amounts of textile dye pollution every year. Among the various adsorbents that have been tested for the removal of dyes, synthetic macroporous polymers are a promising choice due to their developed structure, the presence of active functional groups, and the possibility of regeneration and reuse for several cycles. In this work, a 4-vinylpyridine-co-methacrylic acid based cryogel (4-VP-MAAc) was synthesized at -12 °C by the free-radical polymerization technique, it was characterized using a set of complimentary methods, and then applied for the removal of methylene blue (MB) from water solutions. RESULTS: The adsorption of MB was enhanced at pH values higher than 7 due to the presence of anionic functional groups. The maximum equilibrium adsorption capacity achieved by 4-VP-MAAc was 703.6 mg/g at pH 8. Several kinetics, equilibrium, pH studies, and fixed-bed column experiments were completed in ultra-pure water to evaluate the performance and the mechanism of interaction of positively-charged dye with the polymer. Among the kinetic models applied, the pseudo-second order model best fit the experimental observations. The Langmuir model efficiently described the adsorption of MB onto the prepared cryogel, thus indicating monolayer adsorption. The ion exchange of the Na+ ions present in the structure of the cryogel with dye was found to be the main removal mechanism accompanied with a complexation reaction. No loss of adsorption capacity was observed in four successive adsorption/desorption cycles of 4-VP-MAAc use. CONCLUSION: This is the first time that a 4-vinylpyridine-co-methacrylic acid based cryogel has been synthesized and successfully applied to remove MB from water. © 2022 Society of Chemical Industry (SCI