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  • METEOROLOGY AND CLIMATOLOGY  (14)
  • Chemistry  (5)
  • 2010-2014
  • 1985-1989  (19)
  • 1
    Electronic Resource
    Electronic Resource
    Polarized raman scattering from oriented single microcrystals of d(A5T5)2 and d(pTpT) (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 493-507 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarized Raman spectra have been obtained from single microcrystals of the duplex of the decamer d(A5T5)2 using a Raman microscope. This is the first report of Raman spectra from a crystal of a deoxyoligomer that contains only long, nonalternating sequences of adenine and thymine. Sequences containing d(A)n and d(T)n are of interest in view of recent suggestions that they induce bends in DNA and that they might exist in a nonstandard B-conformation. Polarized Raman spectra of a crystal of d(pTpT) have also been obtained. Both crystals display Raman bands whose intensities are very sensitive to the orientation of the crystal with respect to the direction of polarization of the incident laser beam. These spectra indicate that the helical axes of the oligonucleotides are parallel to the long axes of the crystals and that the d(A5T5)2 is not appreciably bent in the crystal. The Raman spectrum from the d(pTpT) crystal indicates that all of the furanose ring puckers are in a C2′-endo configuration since only the C2′-endo marker band at 835 ± 5 cm-1 is present. Crystals of d(A5T5)2 show measurable Raman intensities in both the 838- and 816-cm-1 bands. This indicates the presence of both the C2′-endo and C3′-endo, or possibly other non-C2′-endo, furanose conformations. The 816-cm-1 band is weak so that only a small fraction of the residues are estimated to be in the non-C2′-endo conformation. In both the d(pTpT) and d(A5T5)2 crystals the intensity of the bands due to vibrations of the backbone show only a small dependence on orientation of the crystals. This result is explained by the low symmetry of the puckered sugar rings. It is concluded that Raman spectra obtained from oligonucleotide crystals in which the orientation of the crystal axes to the laser polarization is not carefully controlled may contain intensity artifacts that are due to polarization effects.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270310
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A temperature-dependent Z to B to single-strand transition in d(CGCG) (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1625-1636 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A thermally induced left- to right-handed helical interconversion for the self-complementary tetradeoxynucleotide d(CGCG) has been observed in the presence of NaCl at concentrations from 1.5 to 2.25M. Analysis of the Raman spectrum of d(CGCG) in aqueous solution as a function of temperature indicates that at low temperature a left-handed Z-helical form is the predominant species. An increase in temperature results in a decrease in the population of the left-handed form and an increase in the population of the right-handed form. Further elevation in temperature results in extensive disruption of base stacking and a loss of secondary structure. This unstacking presumably represents dissociation to a single-stranded structure. The data suggest that a temperature-dependent Z to B to single-strand transition occurs under the conditions employed. A direct Z to single-strand conversion was not identified. In contrast to previous examples, the thermally induced left- to right-handed helical conversion for d(CGCG) can occur in the absence of chemically modified nucleic acid bases, alcohol solutions, or divalent ions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360280911
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Electron impact mass spectrometry of BHT and its alteration products (1989)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 207-217 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact (EI) mass spectra of 2,6-di-tert-butyl-4-methylphenol (BHT) and certain of its alteration products are described in detail. Accurate mass measurements confirm the elemental compositions of important fragment ions in the EI spectra. Collisionally activated mass spectra are also used to study fragmentation and suggest common ion structures. The reference spectra provide the basis for identifying various alteration products of BHT by capillary gas chromatography/mass spectrometry (GC/MS) without the necessity of isolating individual components. Application of GC/MS is made to three studies: (i) pyrolysis of hydroperoxy-BHT as a potential pathway to alteration products in food; (ii) GC/MS pyrolysis of hydroperoxy-BHT as a model study; and (iii) alteration of BHT in ethanol/water as a food-simulating solvent.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200180310
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  • 4
    Electronic Resource
    Electronic Resource
    Surface Analysis of Pulverised Fuel Ash by Secondary Ion Mass Spectrometry and X-ray Photoelectron Spectroscopy (1986)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 3 (1986), S. 89-95 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Samples of pulverised fuel ash (PFA) obtained both from power stations and from laboratory combustion experiments have been examined by SIMS (secondary ion mass spectrometry) and XPS (x-ray photo-electron spectroscopy).The elemental analysis is at present semi-quantitative and indicates presence of sulphur mainly as sulphate ion in the outer surface layer (5-10 nm) of some samples. Other elements, notably Mg, Fe, K and Ti appear at higher concentrations, up to ∼ 10% once the outer 10-20 nm surface layers have been removed by ion etching.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19860030208
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  • 5
    Electronic Resource
    Electronic Resource
    Ultraviolet resonance Raman bands of guanosine and adenosine residues useful for the determination of nucleic acid conformation (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 221-227 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ultraviolet resonance Raman (UVRR) bands of several guanine- and adenine-containing mononucleotides were measured, and were compared with the classical and UVRR spectra of 9-ethylguanine, which contains no furanose ring, in order to assess the effect of sugar conformation on the UVRR spectrum. For several guanine mononucleotides containing different furanose rings some differences were found in the Raman bands normally attributed to the purine vibrations. A similar effect exists with different adenosine mononucleotides. The fact that these vibrations are allowed in the rigorous resonance Raman effect indicates that they are coupled to the electronic transitions of the base. Differences which are seen between cyclic nucleotides, ribonucleotides and deoxyribonucleotides probably arise from differences in the conformation of the attached furanose rings. This provides a method for the identification of conformationally sensitive vibrations of purine rings in nucleic acids.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250180314
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  • 6
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    Numerical simulations of a transverse indirect circulation and low-level jet in the exit region of an upper-level jet (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A numerical study was performed of a severe weather event (tornado) which occurred on May 10, 1973 in the Ohio region. The situation was modeled with a primitive equation mesoscale dynamic formulation. Account was taken of precipitation, the planetary boundary layer parameters as bulk quantities, the vertical pressure gradient, and lateral boundary conditions based on radiosonde data. Two 12-hr simulations, adiabatic and nondivergent, respectively, were analyzed for relationships between upper and lower level jets. In the adiabatic formulation, a transverse circulation with a low level jet formed at the exit region of the upper level jet. The nondivergent situation led to similar, but weaker, phenomena. Both forms suggest that indirect circulation in the exit zone of an upper level jet is strongly influenced by the initial structure of the jet.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 42; 1306-132
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    The error associated with use of various forms of the divergence equation to diagnose geopotential and temperature (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An experimental study was made of errors arising from diagnosing the geopotential and temperature for numerical weather prediction models by means of an inviscid divergence equation (DE). The experiment consisted of a simulation of a snow storm which occurred in 1979, with observational data being input for every point of the model grid and for the geopotential boundary condition, thereby eliminating errors in the horizontal and vertical analysis. The DE terms were recorded at each grid point, and were found to include synoptic-scale geopotential height errors up to 23 m and rms temperature errors exceeding 26 C in the PBL. The errors were minimal above 800 mb. The various unsuccessful attempts to reduce or eliminate the errors are described.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Format: text
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  • 8
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    Dynamic and static initialization of a mesoscale model using VAS satellite data (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Various mesoscale weather forecast model initialization procedures were tested in seven simulation forecasts for a 12 hr period in July 1981. Attention was given to the impacts of using as input radiosonde data, VISSR Atmospheric Sounder (VAS) data and a combination of VAS and data from a smoothed global analysis. The data were assimilated with successive correction objective analysis procedures. The model had a 60 km horizontal grid-length resolution, 14 layers in the vertical, and accounted for short- and long-wave energy in the surface energy budget but not in the atmosphere. Conventional data were used for the mass and moisture fields. The trials showed that VAS data enhanced the predictions of the temperature and mass variables, while winds were least accurately predicted when VAS data were entered in the initializations. Finally, statically initialized precipitation forecasts from radiosonde and/or VAS data exhibited equal skill.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    The impact of data density and data error on the evolution of mesoscale forecast error (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The effects of data density and data errors on the accuracy of mesoscale weather forecasts were assessed by simulations of a period in February 1979 when a snowstorm occurred along the U.S. eastern seaboard. The simulations were initiated every 12 hr and the growth of the rms error was tracked as a function of time and varying data densities. A uniform grid of instrumentation separation and perfect boundary conditions were assumed for all the simulations. A bias error representation was defined to account for systematic measurement errors. A brief summary of features of the somewhat complex storm is provided, together with the parameters of the 11 different simulations with high, medium and low data densities. The accuracy of the forecasts were proportional to the data density, although the error decreased for all the simulations over a 24 hr period. The density of the vertical data had a significant impact on the accuracy of the forecast, whereas the horizontal data density did not. Finally, pathways by which errors were transferred among variables were identified.
    Keywords: METEOROLOGY AND CLIMATOLOGY
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    NASA TECHNICAL REPORTS
  • 10
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    Verification of mesoscale objective analyses of VAS and rawinsonde data using the March 1982 AVE/VAS special network data (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Various combinations of VAS (Visible and Infrared Spin Scan Radiometer Atmospheric Sounder) data, conventional rawinsonde data, and gridded data from the National Weather Service's (NWS) global analysis, were used in successive-correction and variational objective-analysis procedures. Analyses are produced for 0000 GMT 7 March 1982, when the VAS sounding distribution was not greatly limited by the existence of cloud cover. The successive-correction (SC) procedure was used with VAS data alone, rawinsonde data alone, and both VAS and rawinsonde data. Variational techniques were applied in three ways. Each of these techniques was discussed.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: NASA-CR-179988 , NAS 1.26:179988
    Format: application/pdf
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