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  • General Chemistry  (550)
  • Man/System Technology and Life Support  (494)
  • Biochemistry and Biotechnology  (438)
  • Lunar and Planetary Science and Exploration  (389)
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  • 1
    Electronic Resource
    Electronic Resource
    Hydrolysis of triglyceride by solid phase lipolytic enzymes of Rhizopus arrhizus in continuous reactor systems (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 1703-1719 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous hydrolysis of triglyceride in organic solvent systems using Rhizopus arrhizus mycelia as a source of insolubilized lipase has been studied in packed-bed and stirred-tank reactors. Typically a packed bed reactor containing 1 g of mycelia fed at 1 mL/min with a solution of 2.5% (w/v) olive oil in di-isopropyl ether gave a fatty acid yield of 45% at 30°C. The optimum water concentration was found to be 0.17% (w/v) except under conditions of high oil feed concentration and high yield where no optimum was established. No temperature optimum was observed over the range 20-55°C. Calculated activation energies of 13-20 kJ/mol, depending on temperature, were lower, while Km(app) values of 0.1-0.3M were higher than those for hydrolysis in conventional aqueous emulsion systems. No evidence of any significant diffusional limitation, which could account for these values, was obtained. The mycelia showed a loss of activity of 0.6-1.0%h at 30°C. The packed bed proved markedly superior to the stirred tank for this system.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260230804
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  • 2
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    All-Solid-State 2.45-to-2.78-THz Source (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Sources in the THz range are required in order for NASA to implement heterodyne instruments in this frequency range. The source that has been demonstrated here will be used for an instrument on the SOFIA platform as well as for upcoming astrophysics missions. There are currently no electronic sources in the 2 3- THz frequency range. An electronically tunable compact source in this frequency range is needed for lab spectroscopy as well as for compact space-deployable heterodyne receivers. This solution for obtaining useful power levels in the 2 3- THz range is based on utilizing power-combined multiplier stages. Utilizing power combining, the input power can be distributed between different multiplier chips and then recombined after the frequency multiplication. A continuous wave (CW) coherent source covering 2.48 2.75 THz, with greater than 10 percent instantaneous and tuning bandwidth, and having l 14 W of output power at room temperature, has been demonstrated. This source is based on a 91.8 101.8-GHz synthesizer followed by a power amplifier and three cascaded frequency triplers. It demonstrates that purely electronic solid-state sources can generate a useful amount of power in a region of the electromagnetic spectrum where lasers (solid-state or gas) were previously the only available coherent sources. The bandwidth, agility, and operability of this THz source has enabled wideband, high-resolution spectroscopic measurements of water, methanol, and carbon monoxide with a resolution and signal-to-noise ratio unmatched by other existing systems, providing new insight in the physics of these molecules. Further - more, the power and optical beam quality are high enough to observe the Lamb-dip effect in water. The source frequency has an absolute accuracy better than 1 part in 1012, and the spectrometer achieves sub-Doppler frequency resolution better than 1 part in 108. The harmonic purity is better than 25 dB. This source can serve as a local oscillator for a variety of heterodyne systems, and can be used as a method for precision control of more powerful but much less frequency-agile quantum mechanical terahertz sources.
    Keywords: Man/System Technology and Life Support
    Type: NPO-47903 , NASA Tech Briefs, December 2011; 9-10
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Life Support and Habitation and Planetary Protection Workshop (2006)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A workshop entitled "Life Support and Habitation and Planetary Protection Workshop" was held in Houston, Texas on April 27-29, 2005 to facilitate the development of planetary protection guidelines for future human Mars exploration missions and to identify the potential effects of these guidelines on the design and selection of related human life support, extravehicular activity and monitoring and control systems. This report provides a summary of the workshop organization, starting assumptions, working group results and recommendations. Specific result topics include the identification of research and technology development gaps, potential forward and back contaminants and pathways, mitigation alternatives, and planetary protection requirements definition needs. Participants concluded that planetary protection and science-based requirements potentially affect system design, technology trade options, development costs and mission architecture. Therefore early and regular coordination between the planetary protection, scientific, planning, engineering, operations and medical communities is needed to develop workable and effective designs for human exploration of Mars.
    Keywords: Man/System Technology and Life Support
    Type: NASA/TM-2006-213485 , A-06004
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Influence of Planetary Protection Guidelines on Waste Management Operations (2005)
    In:  Other Sources
    Details
    Publication Date: 2019-08-14
    Description: Newly outlined missions in the Space Exploration Initiative include extended human habitation on Mars. During these missions, large amounts of waste materials will be generated in solid, liquid and gaseous form. Returning these wastes to Earth will be extremely costly, and will therefore likely remain on Mars. Untreated, these wastes are a reservoir of live/dead organisms and molecules considered to be "biomarkers" i.e., indicators of life). If released to the planetary surface, these materials can potentially confound exobiology experiments and disrupt Martian ecology indefinitely (if existent). Waste management systems must therefore be specifically designed to control release of problematic materials both during the active phase of the mission, and for any specified post-mission duration. To effectively develop waste management requirements for Mars missions, planetary protection guidelines must first be established. While previous policies for Apollo lunar missions exist, it is anticipated that the increased probability of finding evidence of life on Mars, as well as the lengthy mission durations will initially lead to more conservative planetary protection measures. To facilitate the development of overall requirements for both waste management and planetary protection for future missions, a workshop was conducted to identify how these two areas interface, and to establish a preliminary set of planetary protection guidelines that address waste management operations. This paper provides background regarding past and current planetary protection and waste management issues, and their interactions. A summary of the recommended planetary protection guidelines, anticipated ramifications and research needs for waste management system design for both forward (Mars) and backward (Earth) contamination is also provided.
    Keywords: Man/System Technology and Life Support
    Type: 35th International Conference on Environmental Systems; Jul 11, 2005 - Jul 14, 2005; Rome; Italy
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Gale Crater and Impact Processes - Curiosity's First 364 Sols on Mars (2014)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Impact processes at all scales have been involved in the formation and subsequent evolution of Gale crater. Small impact craters in the vicinity of the Curiosity MSL landing site and rover traverse during the 364 Sols after landing have been studied both from orbit and the surface. Evidence for the effect of impacts on basement outcrops may include loose blocks of sandstone and conglomerate, and disrupted (fractured) sedimentary layers, which are not obviously displaced by erosion. Impact ejecta blankets are likely to be present, but in the absence of distinct glass or impact melt phases are difficult to distinguish from sedimentary/volcaniclastic breccia and conglomerate deposits. The occurrence of individual blocks with diverse petrological characteristics, including igneous textures, have been identified across the surface of Bradbury Rise, and some of these blocks may represent distal ejecta from larger craters in the vicinity of Gale. Distal ejecta may also occur in the form of impact spherules identified in the sediments and drift material. Possible examples of impactites in the form of shatter cones, shocked rocks, and ropy textured fragments of materials that may have been molten have been observed, but cannot be uniquely confirmed. Modification by aeolian processes of craters smaller than 40 m in diameter observed in this study, are indicated by erosion of crater rims, and infill of craters with aeolian and airfall dust deposits. Estimates for resurfacing suggest that craters less than 15 m in diameter may represent steady state between production and destruction. The smallest candidate impact crater observed is 0.6 m in diameter. The observed crater record and other data are consistent with a resurfacing rate of the order of 10 mm/Myr; considerably greater than the rate from impact cratering alone, but remarkably lower than terrestrial erosion rates.
    Keywords: Lunar and Planetary Science and Exploration
    Type: GSFC-E-DAA-TN22564 , Icarus (ISSN 0019-1035); 249; 108-128
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
    Electronic Resource
    Electronic Resource
    A continuous culture apparatus for the microbial utilization of hydrogen produced by electrolysis of water in closed-cycle space systemsPresented at the 53rd National Meeting, American Institute of Chemical Engineers, Pittsburgh, Pennsylvania, May 18, 1964.A report on studies under Contract NASr-100(03) with the National Aeronautics and Space Administration. (1964)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 6 (1964), S. 441-456 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two sources of oxygen for man in closed-cycle space system environment have been considered in previous studies: (1) photosynthesis using algae, and (2) electrolysis of water. The latter system appears to be the most promising from the standpoints of energy and weight requirements and ability to operate in a zero gravity field. The surplus hydrogen produced by the electrolysis of water may be utilized together with waste carbon dioxide, part of the oxygen, and waste urea by bacteria of the genus Hydrogenomonas to produce cellular protein which might be used as a source of food. A continuous culture system for the propagation of hydrogen-fixing bacteria consists of a baffled borosilicate glass culture vessel provided with an impeller, a reservoir vessel for the culture medium, and an overflow vessel for collecting the bacterial cells removed from the culture vessel. Complete feedback control of all parameters affecting growth can be provided by hydrogen, oxygen, and carbon dioxide sensors, and a pH electrode in the culture medium. In addition, total pressure is monitored. Cell density is controlled in the optimum range by means of a photoelectric cell which dictates the amount of fresh medium to be added and the amount of cells to be removed. Operating data indicate that some of the key parameters are the ratio of hydrogen, oxygen, and carbon dioxide in solution. The harvested bacterial substance is high in protein, which contains all the essential amino acids.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260060406
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  • 7
    Electronic Resource
    Electronic Resource
    Study on separation of conalbumin and lysozyme from high concentration fresh egg white at high flow rates by a novel ion-exchanger (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1086-1090 
    Details
    ISSN: 0006-3592
    Keywords: ion-exchanger ; conalbumin ; lysozyme ; egg-white ; separation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this report, we show that it is possible to separate valuable proteins from egg-white using a ProductivTM CM ion-exchanger column operated at flow rates significantly higher than those than can be achieved using traditional particulate adsorbents. In the approach taken, sample pretreatment is restricted to a simple dilution of the egg-white, which can then be applied to the column at superficial velocities (Vs) of up to 13.8 m/h. Under a loading of 220 mg total protein per milliliter of ion-exchanger, the resolution (Rs) between the eluted conalbumin and lysozyme fractions was found to be almost constant during nine consecutive adsorption/desorption cycles. For all nine consecutive batches, the column average adsorption capacity was greater than 30 mg/mL, with 90% recovery of adsorbed protein being achieved in each run. The overall productivity achieved was 12.6 kg/m3 h for lysozyme and 31.2 kg/m3 h for conalbumin. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420910
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  • 8
    Electronic Resource
    Electronic Resource
    The hydroxylation of biphenyl by Aspergillus toxicarius: Conditions for a bench scale fermentation process (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 434-441 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fungi of the Aspergillus sp. can hydroxyate biphenyl to 4,4′-dihydroxybiphenyl, a chemical intermediate used in the plastics industry. The authors studied various batch culture conditions for the production of 4,4′-dihydroxybiphenyl, by Aspergillus toxicarius, in 25-mL shake flasks and 2-L fermenter cultures. Conditions investigated included temperature, aeration, carbon and nitrogen sources, biomass content, and time of substrate addition. Under optimum conditions we observed a rate of 4,4′-dihydroxybiphenyl production of 15-20 mg/day/g dry wt mycelia. Such a production rate is probably too low to support a commercial process and possible reasons for the low productivity are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260260506
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  • 9
    Electronic Resource
    Electronic Resource
    Hydroxylation of biphenyl by Aspergillus parasiticus: Approaches to yield improvment in fermenter cultures (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1395-1402 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We carried out experiments designed to increase the rate of production of 4,4′-dihydroxybiphenyl (biphenol) from biphenyl by Aspergillus parasiticus. We show that 0.5 mg/ml biphenyl, the substrate for the reaction, significantly inhibits growth of the organism and that at 0.04 mg/ml, 2-hydroxybiphenyl or 4-hydroxybiphenyl (an intermediate of the reaction) strongly inhibit oxygen uptake, probably by inhibition of mitochondrial electron transport. Both factors may contribute to the low hydroxylation rates observed previously [J. H. Golbeck and J. C. Cox, Biotechnol. Bioeng., 26, 434 (1984)]. We therefore adapted the organism to the presence of 0.08 mg/ml 2- and 4-hydroxybiphenyl in the growth medium and found that cultures of adapted strains hydroxylated biphenyl at rates ca. three-fold faster than control cultures. Once the fungal mycelia were grown, they could be recycled at least twice into fresh fermentation broth. Recycled organisms were capable of hydroxylating biphenyl more rapidly than cells in the primary fermentation culture and there was no lag period between introduction of biphenyl and the onset of hydroxylation. Cell recycle thus results in a considerable saving in carbon costs and fermentation time.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260271002
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  • 10
    Electronic Resource
    Electronic Resource
    Blueprint for a lipase support: Use of hydrophobic controlled-pore glasses as model systems (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 934-938 
    Details
    ISSN: 0006-3592
    Keywords: immobilization ; nonaqueous enzymology ; esterification ; Rhizomucor miehei lipase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the commercial exploitation of lipase biocatalysis to be successful, it is essential that effective supports are selected for lipase immobilization. In this study hydrophobic controlled-pore glasses have been used as model systems for the immobilization of Rhizomucor miehei lipase. The effect of pore diameter and surface chemistry on enzyme efficiency in a typical esterification reaction under essentially nonaqueous conditions has been examined. It has been found that pore diameters of at least 35 nm are needed for the lipase to be able to utilize the internal volume of the support particles in the immobilization process. Despite the small size of the substrates in the esterification reaction, even larger pores (〉100 nm) are required for the lipase efficiency to become independent of pore diameter; below 100 nm lipase activity and efficiency are markedly reduced. It has also been shown that the chemical nature of the hydrophobic surface plays an important part in catalyst design. Although lipase will adsorb readily to a wide range of hydrophobic groups, the highest catalyst activities are obtained when the glass surface is derivatized to give long alkyl chains; the presence of unsaturated derivatives gonerally leads to a reduction in activity. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260431006
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