181 research outputs found

    Microgravity Science and Applications. Program Tasks and Bibliography for FY 1993

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    An annual report published by the Microgravity Science and Applications Division (MSAD) of NASA is presented. It represents a compilation of the Division's currently-funded ground, flight and Advanced Technology Development tasks. An overview and progress report for these tasks, including progress reports by principal investigators selected from the academic, industry and government communities, are provided. The document includes a listing of new bibliographic data provided by the principal investigators to reflect the dissemination of research data during FY 1993 via publications and presentations. The document also includes division research metrics and an index of the funded investigators. The document contains three sections and three appendices: Section 1 includes an introduction and metrics data, Section 2 is a compilation of the task reports in an order representative of its ground, flight or ATD status and the science discipline it represents, and Section 3 is the bibliography. The three appendices, in the order of presentation, are: Appendix A - a microgravity science acronym list, Appendix B - a list of guest investigators associated with a biotechnology task, and Appendix C - an index of the currently funded principal investigators

    Microgravity: A Teacher's Guide With Activities in Science, Mathematics, and Technology

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    The purpose of this curriculum supplement guide is to define and explain microgravity and show how microgravity can help us learn about the phenomena of our world. The front section of the guide is designed to provide teachers of science, mathematics, and technology at many levels with a foundation in microgravity science and applications. It begins with background information for the teacher on what microgravity is and how it is created. This is followed with information on the domains of microgravity science research; biotechnology, combustion science, fluid physics, fundamental physics, materials science, and microgravity research geared toward exploration. The background section concludes with a history of microgravity research and the expectations microgravity scientists have for research on the International Space Station. Finally, the guide concludes with a suggested reading list, NASA educational resources including electronic resources, and an evaluation questionnaire

    Structure determination of membrane-located complexes: Aquaporin 8 and YscC secretin

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    A biological membrane is key to the life of a cell. In all living cells a biological membrane separates a inner life and an outer environment. Plasma membrane has many functions such as responding to external signals and transmitting them into the cell, providing a barrier to the water soluble molecules, transporting molecules via channels, cell-to-cell communication, separating cellular reactions by compartments and creating ion gradients between them, which are used for converting an energy and signal transduction. Most of the membrane functions are performed by embedded proteins, which are constantly in motion. The homeostasis of water, the most abundant molecule in living organisms, is crucial for physiology of all cells. The main interest in structure determination of the water channel aquaporin 8 (AQP8) is connected with its unique position within the aquaporin family. The human AQP8 cDNA has been cloned in 1998 and since then the intensive studies concerning its intravesicular localization and activity have been preformed. Expressed in the inner mitochondrial membrane of several mammalian tissues, found in liver, gastrointestinal tract, testis, airways and kidney cells, the ammonia-permeable AQP8 could be essential for the organism metabolism. By sequence alignment it is evident that AQP8 creates a separate subfamily, which is apart from all the other mammalian aquaporins. The special constriction region of the pore, which determines the solute permeability, is unique in AQP8 and makes it permeable to both ammonia and hydrogen peroxide in addition to water. For mammalian aquaporins, the structures solved up to now, all belong to the water-permeable subfamily. To better understand AQP8 selectivity and gating mechanism the high-resolution structure is necessary. To assess the structure, human AQP8 was overexpressed in methylotrophic yeast Pichia pastoris as a His-tagged protein. A wide screen of different detergents and detergent-lipid combinations for optimal protein purification and 2D crystallization was essential to obtain well-ordered AQP8 crystal arrays. Removal of amino acids constituting affinity tags was necessary to achieve highly ordered crystals diffracting up to 3 Å. Atomic force microscopy, electron microscopy and gold labeling experiments revealed the double-layered nature of 2D crystals, with tetrameric organization of AQP8, which had termini exposed outwards of the 2D crystal. In parallel, alignments to AQP4 revealed a similar, extraordinary long N-terminal of AQP8. In analogy to AQP4, where only the short isoform is able to crystallize, 2D crystallization of the shorter AQP8 construct, with removed N-terminus, was initiated. The translocation of proteins across the biological membrane is an essential part of cellular life. The type III secretion system (T3SS) is a major factor for the virulence or symbiosis of many Gram-negative bacteria that infect plants and animals. Bacterial effector proteins are delivered via T3SS injectisome from the pathogen cytoplasm into the eukaryotic host cells, in which they modulate the host innate immune response. The outer membrane-localized YscC oligomer belongs to the secretin family and is one of the main components of the injectisome. In this study, the YscC complex was expressed in the avirulent strain of Yesinia enterocolitica and purified in order to construct a 3D model from cryo Electron Microscopy single particle images. The 12 Å-resolution 3D structure of the closed YscC complex was calculated from 30000 projections of vitrified YscC. Various approaches like rotary metal shadowing of trypsin digested oligomers, mass spectrometry and Scanning Transmission Electron Microscopy were used for oligomer symmetry evaluation. The generated 3D structure of the YscC complex disclosed the N-terminal flexible domain, which forms the part of a large chamber between the bacterial outer and inner membranes, the conical shape periplasmic domain, and two differently sized ring-shaped domains linked by fine density connectors corresponding to the outer membrane spanning regions. The sample trypsinization revealed the protease-resistant core of the protein. Comparison of the sequence and structure of YscC to other, close or more distant related secretins made it possible to define homology regions located both on the N- and C-termini of the protein

    Microgravity Science and Applications: Program Tasks and Bibliography for Fiscal Year 1996

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    NASA's Microgravity Science and Applications Division (MSAD) sponsors a program that expands the use of space as a laboratory for the study of important physical, chemical, and biochemical processes. The primary objective of the program is to broaden the value and capabilities of human presence in space by exploiting the unique characteristics of the space environment for research. However, since flight opportunities are rare and flight research development is expensive, a vigorous ground-based research program, from which only the best experiments evolve, is critical to the continuing strength of the program. The microgravity environment affords unique characteristics that allow the investigation of phenomena and processes that are difficult or impossible to study an Earth. The ability to control gravitational effects such as buoyancy driven convection, sedimentation, and hydrostatic pressures make it possible to isolate phenomena and make measurements that have significantly greater accuracy than can be achieved in normal gravity. Space flight gives scientists the opportunity to study the fundamental states of physical matter-solids, liquids and gasses-and the forces that affect those states. Because the orbital environment allows the treatment of gravity as a variable, research in microgravity leads to a greater fundamental understanding of the influence of gravity on the world around us. With appropriate emphasis, the results of space experiments lead to both knowledge and technological advances that have direct applications on Earth. Microgravity research also provides the practical knowledge essential to the development of future space systems. The Office of Life and Microgravity Sciences and Applications (OLMSA) is responsible for planning and executing research stimulated by the Agency's broad scientific goals. OLMSA's Microgravity Science and Applications Division (MSAD) is responsible for guiding and focusing a comprehensive program, and currently manages its research and development tasks through five major scientific areas: biotechnology, combustion science, fluid physics, fundamental physics, and materials science. FY 1996 was an important year for MSAD. NASA continued to build a solid research community for the coming space station era. During FY 1996, the NASA Microgravity Research Program continued investigations selected from the 1994 combustion science, fluid physics, and materials science NRAS. MSAD also released a NASA Research Announcement in microgravity biotechnology, with more than 130 proposals received in response. Selection of research for funding is expected in early 1997. The principal investigators chosen from these NRAs will form the core of the MSAD research program at the beginning of the space station era. The third United States Microgravity Payload (USMP-3) and the Life and Microgravity Spacelab (LMS) missions yielded a wealth of microgravity data in FY 1996. The USMP-3 mission included a fluids facility and three solidification furnaces, each designed to examine a different type of crystal growth

    NASA Tech Briefs, April 1997

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    Topics covered include: Video and Imaging; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Life Sciences; Books and Reports

    Investigating the formation of functional and smart materials by nanospinning and other spinning techniques

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    Functional, smart fibres and fibres with different morphologies have been produced from different materials using different spinning methods. The effect of processing parameters on different nano fibre morphologies was studied by SEM. The spinning solution properties such as viscosity, surface tension, conductivity, UV-visible spectra were studied. The fibres were characterised by DSC, FTIR, XRD, strength test. Antibacterial, hygroscopic, humectant Manuka honey (MH) functional nanofibres have been produced successfully by single needle electrospinning (SNE) using polyethylene oxide (PEO) as matrix. Electrospinning parameters such as higher feed rate, higher proportion of MH, lower applied voltage, lower needle to collector distance produced merged, thicker, flat 15% (wt/wt) MHPEO nanofibres and vice versa. 15%MHPEO fibres of diameters from 0.198μm to 0.924μm were produced using different parameters. The 50% and 65% (wt) MHPEO mats showed antibacterial property. DSC result showed reduction in melting temperature as the MH proportion increased. FTIR results showed respective peaks for MH and PEO. MHPEO nanofibres can be used for medical end use such as wound healing. Ethyl cellulose (EC) nanofibres have been successfully electrospun using different combination of toluene and ethanol (0:100, 40:60, 50:50, 60:40,100:0) as solvent by SNE. Round and elongated bead on string to smooth bead-less 15% (wt/wt)EC fibres produced as proportion of toluene increased in the solvent mixture. Thin, bead-less fibres were obtained by 60:40 (toluene: ethanol) with average fibre diameters ranging from 0.483μm to 0.631μm. EC nanofibres have been also produced by high output bubble electrospinning (BE) method. EC fibres of diameters from 0.188μm to 0.41μm were produced by BE. Comparison between effect of electorspinning parameters on fibre revealed that the fibre morphologies followed different trends in SNE and BE. The beaded structure can be used for loading drugs in advanced medical textiles and smooth bead-less fibrous mat can be used for application such as filtration. In order to develop thermochromic (smart) nanofibres by meltelectrospinning, thermochromic polypropylene fibres have been developed by meltspinning. The pure polypropylene and thermochromic. DSC and FTIR results showed separate peaks for the thermochromic effect and for the polypropylene. SEM images verified the presence of thermochromic pigments. Thermochromic filaments can be used in garment fashion, or as sensors in yarn or fabric form

    Microgravity science & applications. Program tasks and bibliography for FY 1995

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    This annual report includes research projects funded by the Office of Life and Microgravity Sciences and Applications, Microgravity Science and Applications Division, during FY 1994. It is a compilation of program tasks (objective, description, significance, progress, students funded under research, and bibliographic citations) for flight research and ground based research in five major scientific disciplines: benchmark science, biotechnology, combustion science, fluid physics, and materials science. Advanced technology development (ATD) program task descriptions are also included. The bibliography cites the related principle investigator (PI) publications and presentations for these program tasks in FY 1994. Three appendices include a Table of Acronyms, a Guest Investigator index and a Principle Investigator index

    Materials science on parabolic aircraft: The FY 1987-1989 KC-135 microgravity test program

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    This document covers research results from the KC-135 Materials Science Program managed by MSFC for the period FY87 through FY89. It follows the previous NASA Technical Memorandum for FY84-86 published in August 1988. This volume contains over 30 reports grouped into eight subject areas covering acceleration levels, space flight hardware, transport and interfacial studies, thermodynamics, containerless processing, welding, melt/crucible interactions, and directional solidification. The KC-135 materials science experiments during FY87-89 accomplished direct science, preparation for space flight experiments, and justification for new experiments in orbit

    Development and Production of Cellulose Nanocrystal Fillers, PVA Fibers and Composite PVA/CNC Fibers with Electro-Spray/Spinning for Application in Thermoplastic Reinforcement

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    The work within this dissertation involved the production and utilization of cellulose nanomaterials within the context of electrospraying and electrospinning. The production of nano-dimension cellulose nanocrystal (CNC) powders was a novel contribution to the multi-decade efforts surrounding the drying of CNC suspensions, and the powders were produced by electrospraying reduced surface tension suspensions at room temperature. The CNC powders were used as a control for comparison with electrospun fibers in thermoplastic composites. Nano-diameter (submicron) fibers generated most of the work outlined in this dissertation and were produced using a water-soluble, sustainably derived, poly (vinyl alcohol) (PVA). The CNC suspension was added to the PVA and water as the polymer dissolved to create a composite electrospinning solution. The addition of 50 wt.% CNC suspension to the PVA solution increased the viscosity and ultimately decreased the fiber production capacity. However, by slightly reducing the CNC content to 40 wt.%, electrospun fibers could be consistently produced. The fiber diameters were measured and analyzed by a 3x3 factorial experimental iii design involving the addition of 0, 20 and 40 wt.% CNC in PVA solutions and altering the machine settings to produce varied samples. The measurement sampling methodology created the most variation in fiber diameter, rather than the machine settings. While obtaining information about the fiber production characteristics, spun mats were collected and post processed for application as a fiber reinforcement in a thermoplastic poly (lactic acid) (PLA) matrix. The PLA polymer was chosen because it has chemical compatibility with both PVA and CNC as well as sustainable attributes. By reinforcing PLA with 15% composite nanofiber (cNF) composed of 20 wt.% CNC loaded PVA fibers via melt compounding, improvements in the mechanical and thermal properties were observed. The neat PLA tensile modulus increased 30% from 3.64 ± 0.76 to 4.74 ± 0.34 GPa and the tensile strength increased 21% from 56.4 ± 13.6 to 68.3 ± 1.2 MPa. Impact strength showed significant improvement, increasing 54% from 3.15 ± 0.26 to 4.85 ± 0.86 MJ/cm3. The flexural modulus showed a 6% improvement from 3.68 ± 0.09 to 3.91 ± 0.21 GPa and the flexural strength increased 1% from 99.65 ± 6.4 to 100.4 ± 0.6 GPa. The fiber reinforcement contributed to improvements in tensile properties without sacrificing flexural properties or impact strength as normally observed in composites containing microscale CNC powders. This improvement can contribute to additional applications for thermoplastic PLA and the electrospun fiber reinforcement methodology shows applicability to other polymer systems

    Microgravity: Teacher's guide with activities for physical science

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    This guide is an educational tool for teachers of grades 5 through 12. It is an introduction to microgravity and its application to spaceborne laboratory experiments. Specific payloads and missions are mentioned with limited detail, including Spacelab, the International Microgravity Laboratory, and the United States Microgravity Laboratory. Activities for students demonstrate chemistry, mathematics, and physics applications of microgravity. Activity objectives include: modeling how satellites orbit Earth; demonstrating that free fall eliminates the local effects of gravity; measuring the acceleration environments created by different motions; using a plasma sheet to observe acceleration forces that are experienced on board a space vehicle; demonstrating how mass can be measured in microgravity; feeling how inertia affects acceleration; observing the gravity-driven fluid flow that is caused by differences in solution density; studying surface tension and the fluid flows caused by differences in surface tension; illustrating the effects of gravity on the burning rate of candles; observing candle flame properties in free fall; measuring the contact angle of a fluid; illustrating the effects of gravity and surface tension on fiber pulling; observing crystal growth phenomena in a 1-g environment; investigating temperature effects on crystal growth; and observing crystal nucleation and growth rate during directional solidification. Each activity includes a background section, procedure, and follow-up questions
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