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At least 307 records · Page 17

A Robust and Engineerable Self-Assembling Protein Template for the Synthesis and Patterning of Ordered Nanoparticle Arrays

Self-assembling biomolecules that form highly ordered structures have attracted interest as potential alternatives to conventional lithographic processes for patterning materials. Here we introduce a general technique for patterning materials on the nanoscale using genetically modified protein cage structures called chaperonins that self-assemble into crystalline templates. Constrained chemical synthesis of transition metal nanoparticles is specific to templates genetically functionalized with poly-Histidine sequences. These arrays of materials are ordered by the nanoscale structure of the crystallized protein. This system may be easily adapted to pattern a variety of materials given the rapidly growing list of peptide sequences selected by screening for specificity for inorganic materials.

McMillan, R. Andrew↗

Process modelling for space station experiments

The work performed during the first year 1 Oct. 1987 to 30 Sept. 1988 involved analyses of crystal growth from the melt and from solution. The particular melt growth technique under investigation is directional solidification by the Bridgman-Stockbarger method. Two types of solution growth systems are also being studied. One involves growth from solution in a closed container, the other concerns growth of protein crystals by the hanging drop method. Following discussions with Dr. R. J. Naumann of the Low Gravity Science Division at MSFC it was decided to tackle the analysis of crystal growth from the melt earlier than originally proposed. Rapid progress was made in this area. Work is on schedule and full calculations were underway for some time. Progress was also made in the formulation of the two solution growth models.

Rosenberger, Franz↗

Physical phenomena and the microgravity response

The living biological cell is not a sack of Newtonian fluid containing systems of chemical reactions at equilibrium. It is a kinetically driven system, not a thermodynamically driven system. While the cell as a whole might be considered isothermal, at the scale of individual macromolecular events there is heat generated, and presumably sharp thermal gradients exist at the submicron level. Basic physical phenomena to be considered when exploring the cell's response to inertial acceleration include particle sedimentation, solutal convection, motility electrokinetics, cytoskeletal work, and hydrostatic pressure. Protein crystal growth experiments, for example, illustrate the profound effects of convection currents on macromolecular assembly. Reaction kinetics in the cell vary all the way from diffusion-limited to life-time limited. Transport processes vary from free diffusion, to facilitated and active transmembrane transport, to contractile-protein-driven motility, to crystalline immobilization. At least four physical states of matter exist in the cell: aqueous, non-aqueous, immiscible-aqueous, and solid. Levels of order vary from crystalline to free solution. The relative volumes of these states profoundly influence the cell's response to inertial acceleration. Such subcellular phenomena as stretch-receptor activation, microtubule re-assembly, synaptic junction formation, chemotactic receptor activation, and statolith sedimentation were studied recently with respect to both their basic mechanisms and their responsiveness to inertial acceleration. From such studies a widespread role of cytoskeletal organization is becoming apparent.

Todd, Paul↗

A Microgravity Science and Applications Program overview

The Microgravity Science and Space Applications Program (MSSAP) is described in terms of the research it supports in fields related to physical processes and materials. Three primary fields are reviewed which include fundamental sciences such as transport phenomena, materials science, and biotechnology issues such as macromolecular crystal growth. The program strategy is to begin with MSSAP studies in ground-based facilities such as drop towers and to evolve to flight experiments as the research achieves technical maturity. Ground-based experiments in progress include the Acceleration Characterization and Analysis Project and the Solid Surface Combustion Experiment (SSCE). Several furnace experiments for materials studies are described including flight tests for the SSCE, and reference is given to a flight for the Protein-Crystal Growth Experiment.

Kicza, M. E.↗

X-Ray Diffraction and Imaging Study of Imperfections of Crystallized Lysozyme with Coherent X-Rays

Phase-sensitive x-ray diffraction imaging and high angular-resolution diffraction combined with phase contrast radiographic imaging are employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in symmetric Laue case. The fill width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal is approximately 16.7 arcseconds, and defects, which include point defects, line defects, and microscopic domains, have been clearly observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the <110> growth front, and they have been found to originate mostly at a central growth area and occasionally at outer growth regions. Individual point defects trapped at a crystal nucleus are resolved in the images of high sensitivity to defects. Slow dehydration has led to the broadening of the 4 4 0 rocking curve by a factor of approximately 2.4. A significant change of the defect structure and configuration with drying has been revealed, which suggests the dehydration induced migration and evolution of dislocations and lattice rearrangements to reduce overall strain energy. The sufficient details of the observed defects shed light upon perfection, nucleation and growth, and properties of protein crystals.

Hu, Zheng-Wei↗

Diffraction and imaging study of imperfections of crystallized lysozyme with coherent X-rays

Phase-contrast X-ray diffraction imaging and high-angular-resolution diffraction combined with phase-contrast radiographic imaging were employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in the symmetric Laue case. The full-width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal was approximately 16.7 arcsec and imperfections including line defects, inclusions and other microdefects were observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the <1 1 0> growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Inclusions of impurities or formations of foreign particles in the central growth region are resolved in the images with high sensitivity to defects. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of approximately 2.6, which was primarily attributed to the dehydration-induced microscopic effects that are clearly shown in X-ray diffraction images. The details of the observed defects and the significant change in the revealed microstructures with drying provide insight into the nature of imperfections, nucleation and growth, and the properties of protein crystals.

Muramidase/chemistry↗

Controlling Growth Rates of Protein Samples

Apparatus enables control of humidity in chamber to control rates of growth of crystalline samples of protein. Size of drop of solution from which protein is grown made larger or smaller by condensation or evaporation of water. Situated between desiccant and water source, drop of protein solution shrinks or swells, according to which valve operator opens. Growing protein crystal viewed through polarizing film. Readily adapted to automation.

Herrmann, Frederick T.↗

Processing materials in space - The history and the future

The development of materials processing in space, and some of the Soyuz, Apollo, Skylab, and Shuttle orbital materials experiments are reviewed. Consideration is given to protein crystal growth, electrophoresis, low-gravity isoelectric focusing, phase partitioning, a monodisperse latex reactor, semiconductor crystal growth, solution crystal growth, the triglycine sulfate experiment, vapor crystal growth experiments, the mercuric iodide experiment, electronic and electrooptical materials, organic thin films and crystalline solids, deep undercooling of metals and alloys, magnetic materials, immiscible materials, metal solidification research, reluctant glass-forming materials, and containerless glass formation. The space processing apparatuses and ground facilities, for materials processing are described. Future facilities for commercial research, development, and manufacturing in space are proposed.

Chassay, Roger↗

Containerless science for materials processing

Containerless materials processing in space to restrict specimen deformation from hydrostatic pressure of contact with the container is discussed. Several containerless science studies are reviewed, including the study of drop dynamics, nucleation studies, metastable solid phases experiments, glass research, biological materials research, and protein crystal growth. The development of technologies for materials research in space are examined, including acoustic containerless systems, and electrostatic and electromagnetic containerless processing.

Wang, T. G.↗

Space Station Freedom: A foothold on the future

An overview of the Space Station Freedom is given. Its modules are discussed and illustrated along with its microgravity research facilities. These facilities include the advanced protein crystal growth facility, the containerless processing facility, a furnace facility, a combustion facility, and a fluid physics/dynamics facility. The topic of living in space is also addressed.

Source record↗

Syncom 4 deploy, LDEF retrieval highlight 10-day Columbia flight

The objectives of Space Shuttle Mission STS-32 are described along with major flight activities, prelaunch and launch operations, trajectory sequence of events, and landing and post-landing operations. The primary objectives of STS-32 are the deployment of a Navy synchronous communications satellite (Syncom 4) and the retrieval of the Long Duration Exposure Facility (LDEF) launched from the Challenger in April 1984. Secondary STS-32 payloads include a protein crystal growth experiment, the Fluids Experiment Apparatus (FEA) for the investigation of microgravity materials processing, the Mesoscale Lighting Experiment, the Latitude-Longitude Locator Experiment, the Americal Flight Echocardiograph, and an experiment to investigate neurospora circadian rhythms in a microgravity environment.

Source record↗

Science and applications on the space station: A strategic vision

The central themes relating to science and applications on the Space Station for fiscal year 1989 are discussed. Materials science research is proposed in a wide variety of subfields including protein crystal growth, metallurgy, and properties of fluids. Also proposed are the U.S. Polar Platform, an Extended Duration Crew Operations Project, and a long-range Space Biology Research Project to investigate plant and animal physiology, gravitational biology, life support systems, and exobiology. The exterior of the Space Station will provide attachment points for payloads to study subjects such as the earth and its environment, the sun, other bodies in the solar system, and cosmic objects. Examples of such attached payloads are given. They include a plasma interaction monitoring system, observation of solar features and properties, studies of particle radiation from the sun, cosmic dust collection and analysis, surveys of various cosmic and solar rays, measurements of rainfall and wind and the study of global changes on earth.

Source record↗

Reduced gravity - A new biomedical research environment

Experiment programs for continuous flow electrophoresis and protein crystal growth are described to demonstrate the utility of the reduced gravity environment for scientific research. The advantages of the reduced gravity environment are outlined. The results of experiments on the Space Shuttle using the Continuous Flow Electrophoresis System and crystal growth experiments on Spacelab-1 and the Space Shuttle are examined, noting the importance of microgravity research.

Snyder, Robert S.↗

Economic consequences of commercial space operations

The potential economic benefits generated from increased industry involvement and investment in space activities and the subsequent cost implications are discussed. A historical overview of commercial industry involvement in space is given and sources of new economic growth in space are discussed. These include communications satellites, small satellites, positioning and navigation services, space transportation and infrastructure, remote sensing, and materials processing in space such as the manufacturing of protein crystals and zeolites. Macroeconomic trends and principles such as limits on technology trade, eased restrictions on international joint ventures, foreign investments in U.S. firms, and increased foreign competition are discussed. Earth observations and mapping are considered. Opportunities for private sector involvement in building space infrastructure and space transportation are highlighted.

Stone, Barbara A.↗

A materials scientist in space - 1990 MRS Fall Meeting Plenary Address

An edited version of astronaut Bonnie J. Dunbar's Plenary Address at the 1990 MRS Fall Meeting is presented. The Shuttle program is briefly reviewed with emphasis on the microgravity environment experiments conducted aboard the Columbia in January 1991. In particular, protein crystal growth experiments resulted in growing morphologically uniform crystals with sizes in the 400-500 micron range are discussed. The Long-Duration Exposure Facility intended to study the effects of atomic oxygen and the ultraviolet light environment in low earth orbit on materials has been successfully retrieved. Some research areas of future flights are noted.

Dunbar, Bonnie J.↗

Low-gravity materials experiments in the Space Station Freedom

The science and hardware programs laying the science and technology framework for experiments to be conducted aboard SSF are described. Six microgravity facilities planned for the Laboratory Module encompass the Fluid Physics/Dynamics Facility, investigating fundamental fluid behavior; the Advanced Protein Crystal Growth Facility, growing high-quality crystals for pharmaceutical, medical, chemical, and biotechnology applications; the Biotechnology Facility, investigating microgravity effects on biological processes and living organisms at the cellular level and on the purification and production of biological materials; the Space Station Furnace Facility, conducting metal and alloy solidification experiments; the Modular Containerless Processing Facility, supporting experiments through levitation techniques; and the Modular Combustion Facility, performing studies of fundumental combustion processes.

Chassay, Roger P.↗

STS-31 Space Shuttle mission report

The STS-31 Space Shuttle Program Mission Report contains a summary of the vehicle subsystem activities on this thirty-fifth flight of the Space Shuttle and the tenth flight of the Orbiter Vehicle Discovery (OV-103). In addition to the Discovery vehicle, the flight vehicle consisted of an External Tank (ET) (designated as ET-34/LWT-27), three Space Shuttle main engines (SSME's) (serial numbers 2011, 2031, and 2107), and two Solid Rocket Booster (SRB) (designated as BI-037). The primary objective of the mission was to place the Hubble Space Telescope (HST) into a 330 nmi. circular orbit having an inclination of 28.45 degrees. The secondary objectives were to perform all operations necessary to support the requirements of the Protein Crystal Growth (PCG), Investigations into Polymer Membrane Processing (IPMP), Radiation Monitoring Equipment (RME), Ascent Particle Monitor (APM), IMAX Cargo Bay Camera (ICBC), Air Force Maui Optical Site Calibration Test (AMOS), IMAX Crew Compartment Camera, and Ion Arc payloads. In addition, 12 development test objectives (DTO's) and 10 detailed supplementary objectives (DSO's) were assigned to the flight. The sequence of events for this mission is shown. The significant problems that occurred in the Space Shuttle Orbiter subsystems during the mission are summarized, and the official problem tracking list is presented. In addition, each of the Space Shuttle Orbiter problems is cited in the subsystem discussion.

Camp, David W.↗

IVA robotics for Space Station Freedom

The objective is to increase the scientific productivity of Space Station Freedom (Spacelab) during the man-tended phase and beyond. The topics are presented in viewgraph form and include: Space Station Freedom (SSF) background, man-tended phase, intra-vehicular activity (IVA) robotics, protein crystal growth experiment, thermal enclosure system equipment, and candidate mockup demonstrations.

Sharon Monica Jones↗