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  • Chemistry  (6)
  • Electronics and Electrical Engineering  (2)
  • SPACE SCIENCES  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Translational and rotational diffusion of tobacco mosaic virus from polarized and depolarized light scattering (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 1917-1926 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The translational and rotational dynamics of tobacco mosaic virus in sodium phosphate buffer (pH =7.5) solutions has been investigated by polarized and depolarized light scattering Rayleigh linewidth studies. For concentrations ranging from 1.75 × 10-4 g ml-1 to 0.25 × 10-4 g ml-1 the translational diffusion coefficient (DT) has been found to be slightly concentration dependent and extrapolation to zero concentration gives D020°C = 0.34 ± 0.01 × 10-7 cm2S-1. A full analysis of the polarized spectra obtained at high and low scattering angles and the depolarized spectra at near zero scattering angles has enabled these techniques to be compared and the rotational diffusion constant DR to be determined. At a solution concentration of 1.75 × 10-4 g ml-1 a mean value is found to be DR20°C = 350 ± 30s-1. These values of DT and DR are in approximate agreement with calculations based on models of the tobacco mosaic virus molecule as a cylindrical rod.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120817
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Collagen fibrillogenesis in vitro: An investigation of the thermal memory effect and of the early events occurring during fibril assembly using dynamic light scattering (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 1185-1207 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dynamic light scattering has been used to characterize a variety of lathyritic rat skin collagen solutions. The technique was used to monitor the onset of fibril assembly in vitro and to investigate the thermal memory effect. Although the incorporation of thermal memory was demonstrated by reheating the sample and subsequently observing a shortened turbidimetric lag phase, no significant differences between naive solutions and ones exhibiting thermal memory could be detected using photon correlation spectroscopy. This suggests that subtle changes in the state of the collagen molecules rather than extensive changes in the degree of aggregation are responsible for the thermal memory effect. During fibrillogenesis, no large-scale changes in the distribution of monomers or aggregates occur until near the end of the lag phase.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250703
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  • 3
    Electronic Resource
    Electronic Resource
    Dialysis studies. V. The behavior of different preparations of bovine ribonuclease (1963)
    New York : Wiley-Blackwell
    Biopolymers 1 (1963), S. 231-238 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of different preparations of ribonuclease A by thin film dialysis and countercurrent distribution have shown the existence of conformational isomers. These forms are slowly interconvertible in a particular solvent environment. They show the minimum molecular weight of ribonuclease and do not differ enzymatically or by rotatory dispersion.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360010304
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  • 4
    Electronic Resource
    Electronic Resource
    Low-frequency dynamics of solid poly(L-alanine) from Raman spectroscopy (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2891-2899 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman modes from amorphous α-helical poly(L-alanine) in the low-frequency region 〈 150 cm-1 have been observed and assignments and values compared with mode-analysis calculations. The temperature dependence of the complete Raman spectrum of α-poly(L-Ala) is also reported.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231213
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  • 5
    Electronic Resource
    Electronic Resource
    Micromechanics prediction of the transverse tensilc strength of carobn fiber/epoxy composites: The influence of the matrix and interface (1993)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 14 (1993), S. 437-446 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Currently, there is great interest in understanding and improving the bond between the fibers and matrix in high performcance composite materials. In many recently developed systems, fiber surface treatments have been developed to improve poor bonding. These treatments are often evaluated by measureing their effect on a composite property sensitive to the interfacial bond strength, typically the composite shear strength. This paper presents an evaluation of the influence of the matrix and interface properties on the transverse tensile strength. These effects were quantified by compring transverse flexural experimental data with results from a finite element micromechanics model. The results indicate that the transverse tensile strength is significantly more dependent upon sizing than is the shear strength. Finally, the transvere flexure test appears to provide an additional and complementary test for evaluating interface bond characteristics.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750140511
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of RCA cleaning on the surface chemistry of glass and polysilicon films as studied by ToF-SIMS and XPS (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 270-277 
    Details
    ISSN: 0142-2421
    Keywords: RCA clean ; glass ; surface chemistry ; polysilicon ; thin film transistor ; ToF-SIMS ; XPS ; x-ray photoelectron spectroscopy ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface chemistry of an alkaline-earth boroaluminosilicate glass is changed by contact with chemical solutions. The present study shows that RCA cleaning creates a silica-rich surface on the glass. This altered surface can be removed by hydrofluoric acid etching. During the RCA cleaning process, glass components can be transferred to a polysilicon film placed in the same alkaline solution. The acidic solution in turn removes most of the contamination from the polysilicon. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
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    Lunar navigation study, sections 1 through 7 Final report, Jun. 1964 - May 1965 (1965)
    In:  CASI
    Details
    Publication Date: 2019-05-29
    Description: Lunar navigation analysis using passive nongyro, inertial navigation, and radio frequency technology
    Keywords: SPACE SCIENCES
    Type: NASA-CR-69859 , BSR-1134, SEC. 1-7
    Format: application/pdf
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  • 8
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    Lunar navigation study, sections 8 through 10 and appendices Final report, Jun. 1964 - May 1965 (1965)
    In:  CASI
    Details
    Publication Date: 2019-05-29
    Description: Component capabilities and requirements for lunar navigation concepts
    Keywords: SPACE SCIENCES
    Type: NASA-CR-68285 , BSR-1134, SEC. 8-10, APPEND.
    Format: application/pdf
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  • 9
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    MEASUREMENT OF THE NOISE IMPROVEMENT OF A 34-METER CASSEGRAIN ANTENNA RETROFITTED WITH A LOW-BACKSCATTERING STRUT (1997)
    In:  Other Sources
    Details
    Publication Date: 2018-06-05
    Description: Large axially-symmetric ground-based dual-reflector antennas are used in a variety of applications simultaneously requiring very high gain and very low noise (e.g., satellite communications, radio astronomy, deep-space communications, and radar). In these systems, reducing the noise by 10 % is equivalent to increasing the antenna gain by roughly 0.5 dB. Since the early days of radio-astronomy this fact has continuously driven efforts to reduce the noise of front-end low-noise amplifiers--a major noise contributor. As the performance of the front-end amplifiers improved, the relative importance of the noise generated by the surrounding warm ground increased, causing the antenna noise to become a major factor in the overall system sensitivity. Since large ground-based reflectors have been around for several decades, the various electrical and mechanical parameters affecting their performance have received considerable attention and are generally well understood. However, the impact of the subreflector supporting struts on the antenna noise performance remains a source of uncertainty. The reason for this stems from the usually large electrical dimensions involved, which precludes the accurate modeling of the various strut-scattering mechanisms. For the particular antennas used on NASA's Deep Space Network, which have been designed to minimize all noise sources, several studies have typically reported measured noise temperatures between 2 and 3 K (at approx. 8.45 GHz, antenna pointing at zenith), attributed to the struts and other unknown effects (see for example [1] and [2]). With this in mind, an effort has recently been conducted to determine optimal strut shapes to reduce the associated noise contribution [3].
    Keywords: Electronics and Electrical Engineering
    Type: IEEE Antennas and Propagation Society International Symposium 1997. Volume 3: Digest; 1659-1662; IEEE-Catalog-97CH36122-Vol-3
    Format: text
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  • 10
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    Cryogenic Characterization and Testing of Magnetically-Actuated Microshutter Arrays for the James Webb Space Telescope (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two-dimensional MEMS microshutter arrays (MSA) have been fabricated at the NASA Goddard Space Flight Center (GSFC) for the James Webb Space Telescope (JWST) to enable cryogenic (approximately 35 K) spectrographic astronomy measurements in the near-infrared region. Functioning as a focal plane object selection device, the MSA is a 2-D programmable aperture mask with fine resolution, high efficiency and high contrast. The MSA are close- packed silicon nitride shutters (cell size of 100 x 200 microns) patterned with a torsion flexure to allow opening to 90 degrees. A layer of magnetic material is deposited onto each shutter to permit magnetic actuation. Two electrodes are deposited, one onto each shutter and another onto the support structure side-wall, permitting electrostatic latching and 2-D addressing. New techniques were developed to test MSA under mission-similar conditions (8 K less than or equal to T less than 300K). The magnetic rotisserie has proven to be an excellent tool for rapid characterization of MSA. Tests conducted with the magnetic rotisserie method include accelerated cryogenic lifetesting of unpackaged 128 x 64 MSA and parallel measurement of the magneto-mechanical stiffness of shutters in pathfinder test samples containing multiple MSA designs. Lifetest results indicate a logarithmic failure rate out to approximately 10(exp 6) shutter actuations. These results have increased our understanding of failure mechanisms and provide a means to predict the overall reliability of MSA devices.
    Keywords: Electronics and Electrical Engineering
    Type: Solid-State Sensors, Actuators and Microsystems Workshop; Jun 06, 2004 - Jun 10, 2004; Hilton Head, SC; United States
    Format: application/pdf
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