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  • LASERS AND MASERS  (4)
  • sol-gel  (4)
  • J31
  • 1
    Electronic Resource
    Electronic Resource
    Encapsulation of the ferritin protein in sol-gel derived silica glasses (1996)
    Springer
    Journal of sol gel science and technology 7 (1996), S. 109-116 
    Details
    ISSN: 1573-4846
    Keywords: ferritin ; sol-gel ; magnetism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A significant recent development in sol-gel science has been the encapsulation of biomolecules such as proteins and enzymes in optically transparent silica glasses. This paper reports on the encapsulation of an iron (Fe) storage protein, ferritin, to develop a magnetic silica glass. Native ferritin, which has a nanometer-sized microcrystalline Fe oxide core, was encapsulated in optically transparent silica glasses using the sol-gel process. Fe could be released from ferritin but could not be reconstituted into apoferritin when the protein was trapped in the pores of the glass. Transmission electron microscopy of ferritin-doped aged silica gels indicated that crystallinity of the Fe oxide core was retained upon sol-gel encapsulation. Magnetic measurements on ferritin-doped silica gels indicated the material to be paramagnetic, but not superparamagnetic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401890
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Spectroscopic determination of cholinesterase activity and inhibition in sol-gel media (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 1067-1070 
    Details
    ISSN: 1573-4846
    Keywords: cholinesterase ; sol-gel ; pesticide ; THA ; enzyme activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Biological activity of cholinesterases can be determined by optically monitoring the enzymatic reaction with indophenyl acetate, (N-4′-acetoxyphenyl)-4-quinone imine. At pH 8.0 cholinesterases hydrolyze this yellow dye to yield a blue reaction product. Cholinesterase inhibitors reduce the rate of this hydrolysis. Thus, by monitoring absorbance of the hydrolysis product at its maximum (630 nm) as a function of time, reaction rates of both cholinesterase activity and cholinesterase inhibition may be quantified spectroscopically. Using this technique, we measured the enzymatic activity of butyrylcholinesterase (BuChE) molecules encapsulated in tetramethyl orthosilicate (TMOS) silicate gel-glass prepared by hydrolysis and condensation. This activity is reduced, in a concentration-dependent manner, by the reversible cholinesterase inhibitors 1,5-bis(4-allyldimethyl-ammoniumphenyl) pentan 3-one dibromide (BADAPP) and 9-amino-1,2,3,4-tetrahydroacridine (THA; tacrine, Cognex). The gel-glasses are rigid, and compact, transparent and porous enough to allow reagents to diffuse in and out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436985
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Allosteric Regulation of Enzymatic Reactions in a Transparent Inorganic Sol-Gel Material (1999)
    Springer
    Journal of sol gel science and technology 15 (1999), S. 57-62 
    Details
    ISSN: 1573-4846
    Keywords: glutamate dehydrogenase ; allosteric regulators ; sol-gel ; enzyme activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Glutamate dehydrogenase is encapsulated in a transparent porous silicate matrix by using sol-gel techniques. The inorganic polymer is formed around the enzyme (MW 〉 300,000 D). The enzyme is active in the material, catalyzes the reaction of L-glutamate to 2-oxoglutarate and follows Michaelis-Menten kinetics. The allosteric regulators ADP and GTP inhibit or activate the reaction; at pH 6, GTP acts as a strong activator and ADP acts as an inhibitor. This system involves a complex series of interactions; the co-enzyme NAD+ is required for catalysis, large-scale conformational changes accompany the binding of the substrate and coenzyme to the enzyme, the activators/inhibitors must bind to the enzyme to regulate the reactions, and the substrates and products must diffuse through the matrix to and from the binding site. The influence of the unique matrix on the complex enzymatic system is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008713014152
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  • 4
    Electronic Resource
    Electronic Resource
    Spectroscopic Determination of Cholinesterase Activity and Inhibition in Sol-Gel Media (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 1067-1070 
    Details
    ISSN: 1573-4846
    Keywords: cholinesterase ; sol-gel ; pesticide ; THA ; enzyme activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Biological activity of cholinesterases can be determined by optically monitoring the enzymatic reaction with indophenyl acetate, (N-4′-acetoxyphenyl)-4-quinone imine. At pH 8.0 cholinesterases hydrolyze this yellow dye to yield a blue reaction product. Cholinesterase inhibitors reduce the rate of this hydrolysis. Thus, by monitoring absorbance of the hydrolysis product at its maximum (630 nm) as a function of time, reaction rates of both cholinesterase activity and cholinesterase inhibition may be quantified spectroscopically. Using this technique, we measured the enzymatic activity of butyrylcholinesterase (BuChE) molecules encapsulated in tetramethyl orthosilicate (TMOS) silicate gel-glass prepared by hydrolysis and condensation. This activity is reduced, in a concentration-dependent manner, by the reversible cholinesterase inhibitors 1,5-bis(4-allyldimethyl-ammoniumphenyl) pentan- 3-one dibromide (BADAPP) and 9-amino-1,2,3,4-tetrahydroacridine (THA; tacrine, Cognex). The gel-glasses are rigid and compact, transparent, and porous enough to allow reagents to diffuse in and out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018350828807
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  • 5
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    NO2 heterodyne frequency measurements with a tunable diode laser, a CO laser transfer oscillator and CO2 laser standards (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Heterodyne frequency measurements have been made on selected groups of nitrogen dioxide rovibronic transitions between 1580.8 and 1650.7/cm. The groups are separated by 7 to 10/cm, and the intent is to provide a limited (and interim) calibration table for the region. In addition to a table of measured frequencies in the region, figures of spectra in the vicinity of the measured lines are included to provide a map for identifying the transitions measured.
    Keywords: LASERS AND MASERS
    Type: NASA-CR-182393 , NAS 1.26:182393 , PB88-110051 , NBS/TN-1308
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Far infrared laser frequencies of CH3OD and N2H4 (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The frequencies of 26 laser lines with wavelengths between 57 and 534 microns are measured in the optically pumped laser gases CH3OD and N2H4. A pair of 12CO2 lasers are employed as a frequency standard for the heterodyne frequency measurements. As the measurements are oriented toward spectroscopic applications of FIR lasers where dense, broad, frequency coverage is essential, every strong pump absorption of the two molecules for new lines that might be made to lase by varying the laser gas pressure and the tuning of the pump laser are investigated.
    Keywords: LASERS AND MASERS
    Type: International Journal of Infrared and Millimeter Waves (ISSN 0195-9271); 12; 1161-116
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Accurate frequency of the 119 micron methanol laser from tunable far-infrared absorption spectroscopy (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: High-accuracy absorption spectroscopy of CH3OH in the far infrared is discussed. In addition to 22 transitions in the ground state, the frequency of the (n, tau, J, K), (0, 1, 16, 8) to (0, 2, 15, 7) transition in the nu5 excited vibrational level, which is responsible for the laser emission at 119 microns, was measured. The measured frequency is 2,522,782.57(10) MHz at zero pressure, with a pressure shift of 6.1(32) kHz/Pa (0.805/420/ MHz/torr). An accurate remeasurement of the laser emission frequency has also been performed, and the results are in good agreement.
    Keywords: LASERS AND MASERS
    Type: IEEE Journal of Quantum Electronics (ISSN 0018-9197); 26; 575-579
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Sub-Doppler tunable far-infrared spectroscopy (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The first experimental observations of sub-Doppler linewidths in a cell made using tunable far-infrared radiation are reported. A double-resonance scheme has been used, combining CO2-laser infrared radiation with tunable far-infrared radiation to observe a sub-Doppler line shape in an excited vibrational state of CH3OH.
    Keywords: LASERS AND MASERS
    Type: Optics Letters (ISSN 0146-9592); 12; 867-869
    Format: text
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    NASA TECHNICAL REPORTS
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