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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Human serum albumin crystals and method of preparation

Human serum albumin (HSA) crystals are provided in the form of tetragonal plates having the space groups P42(sub 1)2, the crystals being grown to sizes in excess of 0.5 mm in two dimensions and a thickness of 0.1 mm. Growth of the crystals is carried out by a hanging drop method wherein a precipitant solution containing polyethylene glycol (PEG) and a phosphate buffer is mixed with an HSA solution, and a droplet of mixed solution is suspended over a well of precipitant solution. Crystals grow to the desired size in 3 to 7 days. Concentration of reagents, pH and other parameters are controlled within prescribed limits. The resulting crystals exhibit a size and quality such as to allow performance of x ray diffraction studies and enable the conduct of drug binding studies as well as genetic engineering studies.

Carter, Daniel C.↗
NASA NTRS1990

The connector space reduction mechanism

The Connector Space Reduction Mechanism (CSRM) is a simple device that can reduce the number of electromechanical devices on the Payload Interface Adapter/Station Interface Adapter (PIA/SIA) from 4 to 1. The device uses simplicity to attack the heart of the connector mating problem for large interfaces. The CSRM allows blind mate connector mating with minimal alignment required over short distances. This eliminates potential interface binding problems and connector damage. The CSRM is compatible with G and H connectors and Moog Rotary Shutoff fluid couplings. The CSRM can be used also with less forgiving connectors, as was demonstrated in the lab. The CSRM is NASA-Goddard exclusive design with patent applied for. The CSRM is the correct mechanism for the PIA/SIA interface as well as other similar berthing interfaces.

Milam, M. Bruce↗
NASA NTRS1990

Catalyst for carbon monoxide oxidation

A catalyst is disclosed for the combination of CO and O2 to form CO2, which includes a platinum group metal (e.g., platinum); a reducable metal oxide having multiple valence states (e.g., SnO2); and a compound which can bind water to its structure (e.g., silica gel). This catalyst is ideally suited for application to high-powered pulsed, CO2 lasers operating in a sealed or closed-cycle condition.

Upchurch, Billy T.↗
NASA NTRS1989

Three-dimensional structure of human serum albumin

The three-dimensional structure of human serum albumin has been solved at 6.0 A resolution by the method of multiple isomorphous replacement. Crystals were grown from solutions of polyethylene glycol in the infrequently observed space group P42(1)2 and diffracted X-rays to lattice d-spacings of less than 2.9 A. The electron density maps are of high quality and revealed the structure as a predominantly alpha-helical globin protein in which the course of the polypeptide can be traced. The binding loci of several organic compounds have been determined.

Carter, Daniel C.↗
NASA NTRS1989

Universal aspects of brittle fracture, adhesion, and atomic force microscopy

This universal relation between binding energy and interatomic separation was originally discovered for adhesion at bimetallic interfaces involving the simple metals Al, Zn, Mg, and Na. It is shown here that the same universal relation extends to adhesion at transition-metal interfaces. Adhesive energies have been computed for the low-index interfaces of Al, Ni, Cu, Ag, Fe, and W, using the equivalent-crystal theory (ECT) and keeping the atoms in each semiinfinite slab fixed rigidly in their equilibrium positions. These adhesive energy curves can be scaled onto each other and onto the universal adhesion curve. The effect of tip shape on the adhesive forces in the atomic-force microscope (AFM) is studied by computing energies and forces using the ECT. While the details of the energy-distance and force-distance curves are sensitive to tip shape, all of these curves can be scaled onto the universal adhesion curve.

Banerjea, Amitava↗
NASA NTRS1989

A high-level ab initio study of the anionic hydrogen-bonded complexes FH-CN(-), FH-NC(-), H2O-CN(-), and H2O-NC(-)

HF, H2O, CN- and their hydrogen-bonded complexes were studied using state-of-the-art ab initio quantum mechanical methods. A large Gaussian one particle basis set consisting of triple zeta plus double polarization plus diffuse s and p functions (TZ2P + diffuse) was used. The theoretical methods employed include self consistent field, second order Moller-Plesset perturbation theory, singles and doubles configuration interaction theory and the singles and doubles coupled cluster approach. The FH-CN- and FH-NC- and H2O-CN-, H2O-NC- pairs of complexes are found to be essentially isoenergetic. The first pair of complexes are predicted to be bound by approx. 24 kcal/mole and the latter pair bound by approximately 15 kcal/mole. The ab initio binding energies are in good agreement with the experimental values. The two being shorter than the analogous C-N hydrogen bond. The infrared (IR) spectra of the two pairs of complexes are also very similar, though a severe perturbation of the potential energy surface by proton exchange means that the accurate prediction of the band center of the most intense IR mode requires a high level of electronic structure theory as well as a complete treatment of anharmonic effects. The bonding of anionic hydrogen-bonded complexes is discussed and contrasted with that of neutral hydrogen-bonded complexes.

Lee, Timothy J.↗
NASA NTRS1990

Explosive nucleosynthesis in SN 1987A. II - Composition, radioactivities, and the neutron star mass

The 20 solar mass model of Nomoto and Hashimoto (1988) is utilized with a 6 solar mass. He core is used to perform explosive nucleosynthesis calculations. The employed explosion energy of 10 to the 51st ergs lies within the uncertainty range inferred from the bolometric light curve. The nucleosynthesis processes and their burning products are discussed in detail. The results are compared with abundances from IR observations of SN 1987A and the average nucleosynthesis expected for Type II supernovae in Galactic chemical evolution. The abundances of long-lived radioactive nuclei and their importance for the late light curve and gamma-ray observations are predicted. The position of the mass cut between the neutron star and the ejecta is deduced from the total amount of ejected Ni-56. This requires a neutron star with a baryonic mass of 1.6 + or - 0.045 solar mass, which corresponds to a gravitational mass of 1.43 + or - 0.05 solar mass after subtracting the binding energy of a nonrotating neutron star.

Thielemann, Friedrich-Karl↗
NASA NTRS1989

Effects of simulated weightlessness on rat osteocalcin and bone calcium

The effect of weightlessness on the serum content of the mineral-binding protein osteocalcin (OC), bone OC, and bone Ca were investigated in rats subjected for periods from 2 to 28 days to a hindlimb unweighting procedure simulating weightlessness. It was found that serum OC decreased by 25 percent (consistent with a decreased rate of bone growth), during the first week of hindlimb suspension, but returned to normal levels after 15 days. The third lumbar vertebra (L3) and femur (analyzed in this study) lost 20 percent of weight after 10-28 days of suspension. Analysis of OC and Ca concentrations and content in L3 and femur suggest a temporal divergence of the metabolism of these two bone components. The OC and Ca concentrations were found to vary not only with respect to the duration of unweighting but also to differ from each other in the magnitude of their response. The data showed that unweighting affects the formation and deposition of OC and Ca differently, depending on the bone location and the duration of unweighting.

Patterson-Buckendhal, Patricia↗
NASA NTRS1989

Oligomerization reactions of deoxyribonucleotides on montmorillonite clay - The effect of mononucleotide structure on phosphodiester bond formation

The formation of oligomers from deoxynucleotides, catalyzed by Na(+)-montmorillonite, was investigated with special attention given to the effect of the monomer structure on the phosphodiester bond formation. It was found that adenine deoxynucleotides bind more strongly to montmorillonite than do the corresponding ribonucleotides and thymidine nucleotides. Tetramers of 2-prime-dpA were detected in the reaction of 2-prime-d-5-prime-AMP with a water-soluble carbodiimide EDAC in the presence of Na(+)-montmorillonite, illustrating the possible role of minerals in the formation of biopolymers on the primitive earth.

Ferris, James P.↗
NASA NTRS1990

The physical and infrared spectral properties of CO2 in astrophysical ice analogs

Results of measurements of the infrared spectroscopic and condensation-vaporization properties of CO2 in pure and mixed ices are presented. Detailed examination of five infrared CO2 bands, 2.20, 2.78, 4.27, 15.2, and 4.39 microns, shows that the peak position, FWHM, and profile of the bands provide important information about the composition, formation, and subsequent thermal history of the ices. Absorption coefficients and their temperature dependence for all five CO2 bands are determined. The temperature dependence variation is found to be less than 15 percent from 10 to 150 K, i.e., the temperature at which H2O ice sublimes. The number of parameters associated with the physical behavior of CO2 in CO2- and H2O-rich ices, including surface binding energies, and condensation and sublimation temperatures, are determined under experimental conditions. The implications of the data obtained for cometary models are considered.

Sandford, S. A.↗
NASA NTRS1989

Cross-fertilization between connectionist networks and highly parallel architectures

The theoretical and practical connections between connectionist schemes such as neural-network computers and traditional symbolic processing architectures involving a high degree of parallelism are explored, reviewing the results of recent investigations. Topics addressed include data flow, data structure, and control flow; conventional pointers; associative addressing; hashing and reduced representations; the problem of binding values to variables; and levels of parallelism. It is concluded that connectionism is more closely related to traditional computer science and technology than is generally admitted; more cooperation between followers of the two approaches is recommended.

Barnden, John↗
NASA NTRS1989

Neutrinos from SN 1987A - Implications for cooling of the nascent neutron star and the mass of the electron antineutrino

Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.

Loredo, Thomas J.↗
NASA NTRS1990

X-ray photoelectron spectroscopy peak assignment for perfluoropolyether oils

Perfluoroalkylpolyether (PFPE) oils are increasingly being used as vacuum pump oils and as lubricants for magnetic recording media and instrumentation for satellites. In this paper, the relative binding energies of three PFPE oils are determined. When sample oils are continuously irradiated during X-ray spectroscopy (XPS) measurements, the relative peak intensity of the spectra is altered significantly, indicating that gaseous products form from the oils during XPS measurements. Thus, attention should be paid to chemical changes when XPE is used to characterize fluorinated carbons such as PFPE oils.

Mori, Shigeyuki↗
NASA NTRS1990

Definition study for temperature control in advanced protein crystal growth

Some of the technical requirements for an expedient application of temperature control to advanced protein crystal growth activities are defined. Lysozome was used to study the effects of temperature ramping and temperature gradients for nucleation/dissolution and consecutive growth of sizable crystals and, to determine a prototype temperature program. The solubility study was conducted using equine serum albumin (ESA) which is an extremely stable, clinically important protein due to its capability to bind and transport many different small ions and molecules.

Nyce, Thomas A.↗
NASA NTRS1990

Comparison of the quadratic configuration interaction and coupled cluster approaches to electron correlation including the effect of triple excitations

The recently proposed quadratic configuration interaction (QCI) method is compared with the more rigorous coupled cluster (CC) approach for a variety of chemical systems. Some of these systems are well represented by a single-determinant reference function and others are not. The finite order singles and doubles correlation energy, the perturbational triples correlation energy, and a recently devised diagnostic for estimating the importance of multireference effects are considered. The spectroscopic constants of CuH, the equilibrium structure of cis-(NO)2 and the binding energies of Be3, Be4, Mg3, and Mg4 were calculated using both approaches. The diagnostic for estimating multireference character clearly demonstrates that the QCI method becomes less satisfactory than the CC approach as non-dynamical correlation becomes more important, in agreement with a perturbational analysis of the two methods and the numerical estimates of the triple excitation energies they yield. The results for CuH show that the differences between the two methods become more apparent as the chemical systems under investigation becomes more multireference in nature and the QCI results consequently become less reliable. Nonetheless, when the system of interest is dominated by a single reference determinant both QCI and CC give very similar results.

Taylor, Peter R.↗
NASA NTRS1990

Advanced software integration: The case for ITV facilities

The array of technologies and methodologies involved in the development and integration of avionics software has moved almost as rapidly as computer technology itself. Future avionics systems involve major advances and risks in the following areas: (1) Complexity; (2) Connectivity; (3) Security; (4) Duration; and (5) Software engineering. From an architectural standpoint, the systems will be much more distributed, involve session-based user interfaces, and have the layered architectures typified in the layers of abstraction concepts popular in networking. Typified in the NASA Space Station Freedom will be the highly distributed nature of software development itself. Systems composed of independent components developed in parallel must be bound by rigid standards and interfaces, the clean requirements and specifications. Avionics software provides a challenge in that it can not be flight tested until the first time it literally flies. It is the binding of requirements for such an integration environment into the advances and risks of future avionics systems that form the basis of the presented concept and the basic Integration, Test, and Verification concept within the development and integration life cycle of Space Station Mission and Avionics systems.

Garman, John R.↗
NASA NTRS1991

Catalyst for carbon monoxide oxidation

A catalyst for the combination of CO and O2 to form CO2 which includes a platinum group metal, e.g., platinum; a reducible metal oxide having mulitple valence states, e.g., SnO2; and a compound which can bind water to its structure, e.g., silica gel. This catalyst is ideally suited for application to high powered, pulsed, CO2 lasers operating in a sealed or closed cycle condition.

Upchurch, Billy T.↗
NASA NTRS1991

Modeling the coma of 2060 Chiron

Observations of comet-like activity and a resolved coma have established that 2060 Chiron is a comet. Determinations of its radius range from 65 to 200 km. This unusually large size for a comet suggests that the atmosphere of Chiron is intermediate to the tightly bound, thin atmospheres typical of planets and satellite and the greatly extended atmospheres in free expansion typical of cometary comae. Under certain conditions it may gravitationally bind an atmosphere that is thick compared to its size, while a significant amount of gas escapes to an extensive exosphere. These attributes coupled with reports of sporadic outbursts at large heliocentric distances and the identification of CN in the coma make Chiron a challenging object to model. Simple models of gas production and the dusty coma were recently presented but a general concensus on many basic features has not emerged. Development was begun on a more complete coma model of Chiron. The objectives are to report progress on this model and give the preliminary results for understanding Chiron.

Boice, D. C.↗