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  • Chemistry  (6)
  • GEOPHYSICS  (6)
  • Autoregulation of nodulation  (1)
  • Historic landscape preservation
  • National Park management
  • 1985-1989  (8)
  • 1980-1984  (6)
  • 1950-1954
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Environmental management 4 (1980), S. 433-448 
    ISSN: 1432-1009
    Schlagwort(e): Agricultural management ; Great Smoky Mountains National Park ; Historic landscape preservation ; National Park management ; Cades Cove
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Agricultural management in Cades Cove, an historic district in Great Smoky Mountains National Park, has affected natural resources both within the district and in the adjoining natural areas. Aquatic impacts of haying and cattle grazing included increases in water temperatures, turbidity, nutrient loading, and bacterial counts and decreases in benthic macroinvertebrate density and fish biomass. Wildlife populations, including groundhogs, wild turkeys, and white-tailed deer, have increased in the open fields and around the periphery of the historic district. Intensive deer foraging has removed deciduous seedlings and saplings from woodlots, lowering species diversity and favoring coniferous reproduction. Cades Cove has limestone habitats unique in the park, and both deer browse and cattle grazing may have disturbed populations of rare plant species. Effects on water quality are detectable at a campground 15 stream km from the agricultural area, and the effects of deer foraging extend about 1 km beyond the open fields. Since “historic landscape” preservation is presently a goal of the park, managing for open vistas in Cades Cove will require some sort of continuing disturbance. Conversion of cattle pastures to hayfields would reduce aquatic impacts but the deer herd might increase as a result of reduced competition for forage. Retarding old field succession would increase populations of native plant species dependent on sunlight, but would require government-funded mowing. Other options are discussed. Completely eliminating the effects of the historic district on adjoining areas may be impossible, at least under present economic constraints.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1615-6102
    Schlagwort(e): Soybean ; Non-nodulating mutants ; Supernodulating mutant ; Sub-epidermal cell divisions ; Autoregulation of nodulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The early events in the development of nodules induced byBradyrhizobium japonicum were studied in serial sections of a wild type (cv. Bragg), a supernodulating mutant (nts 382) and four non-nodulating mutants (nod49, nod139, nod772, andrj 1) of soybean (Glycine max [L.] Merrill). Cultivar Bragg responded to inoculation in a similar manner to that described previously for cv. Williams; centres of sub-epidermal cell divisions were observed both with and without associated infection threads and most infection events were blocked before the formation of a nodule meristem. The non-nodulating mutants (nod49, nod772, andrj 1) had, at most, a few centres of sub-epidermal cell divisions. In general, these were devoid of infection threads and did not develop beyond the very early stages of nodule ontogeny. Sub-epidermal cell divisions or infection threads were never observed on mutant nodl39. This mutant is not allelic to the other non-nodulating mutants and represents a defect in a separate complementation group or gene that is required for nodulation. The supernodulating mutant nts382, which is defective in autoregulation of nodulation, had a similar number of sub-epidermal cell divisions as the wild-type Bragg, but a much greater proportion of these developed to an advanced stage of nodule ontogeny. Mutant nts382, like Bragg, possessed other infection events that were arrested at an early stage of development. The results are discussed in the context of the progression of events in nodule formation and autoregulation of nodulation in soybean.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 2067-2076 
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Alkali treatment of corn stover improves the avaliability of cellulose and hemicellulose for enzymatic attack. Treatments were carried out for 1 to 60 min at temperatures and NaOH concentrations ranging from 100 to 150°C and 0 to 2%, respectively. Solubilization of the stover and sugar production by enzymatic hydrolysis (Trichoderma viride cellulase) of the solid residue and the dissolved solids were used to measure the effect of caustic treatment. At 150°C and 2% NaOH concentration, 65% of the original stover was dissolved after 5 min and 52% saccharificatin (g sugar/g stover) of the residue and dissolved solids by enzymatic hydrolysis was achieved compared to 20% for untreated corn stover.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Fast-atom bombardment mass spectrometry of a synthetic renin substrate decapeptide (Pro-His-Pro-Phe-His-Leu-Val-Ile-His-D-Lys) indicated the presence of several of side-products, including a component 12 Da higher in mass. Low-energy collisionally activated decomposition analyses were performed using a hybrid tanden, instrument and demonstrated that the heavier side product had two components, in which the structural modification was either at the N- or the C-terminus. Additional analyses of the N-acetyl derivative indicated that for each component the strucutrual modification blcoked a site of N-acetylation. It is suggested that the formation of these side products is attributable to the generation of formaldehyde, during removal of the histidine protecting group (benzyloxymethyl), which reacts with the N-terminus of the peptide to give an imidazolidinone structure or with the D-lysine ε-amine group to yield an imine. While the precise genesis of the side-products remains speculative, it is clear that the combined strategy of derivatization and tandem mass spectrometry has allowed structural conclusions concerning individual components of an isobaric mixture.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 17 (1988), S. 239-241 
    ISSN: 0049-8246
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: The zinc contents of a series of zinc-aluminium binary alloys were determined by wavelength-dispersive x-ray fluorescence spectrometry using very small samples. The Zn Kα radiation from the alloy undergoes an apparent enhancement due to the widely different absorption coefficients of zinc and aluminium for radiation close to the short-wavelength side of the K absorption edge of zinc. This was corrected mathematically by using mass absorption coefficients from the literature. The method is comparable in accuracy to wet chemical analysis. The precision obtained is of the order of 0.25% relative at 6 atom-% of zinc. The method of fitting the measured Zn Kα intensity to a non-linear function of composition is also examined.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0570-0833
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Advances in Polymer Technology 9 (1989), S. 253-264 
    ISSN: 0730-6679
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: The effect of the constituent material on the mechanical properties and on the overall crack propagation behavior of uniaxial graphite/epoxy composites was studied using two different types of graphite fibers, i.e., PAN precursor and pitch precursor fibers in combination with an epoxy known for its toughness. The tensile properties and interlaminar shear strength (ILSS) of composites with various fiber volume fraction were studied using an Instron Universal Testing Machine. The fracture surface of composites was studied using scanning electron microscopy (SEM). The surprising result from the tensile tests is that the percent elongation of AS4/epoxy composites was much higher than that of individual components, i.e., the epoxy and the fiber. The stress-strain curves of AS4 fiber/epoxy composites show yielding. The yielding is interpreted to result from shear stress concentration due to the fiber breakage. Two causes of failure mode were observed in this study: (1) ductile plastic deformation by the PAN-based AS4/epoxy composites; (ii) brittle catastrophic failure shown by the pitch-based VSB-16/epoxy composites. The tensile strengths and moduli of the composites increased as the volume fraction of fibers increased. The principal fracture features of AS4/epoxy composites under tension were fiber pullout (bundles and single fibers) and very rough fracture surface due to the pullout of fiber bundles with epoxy, whereas VSB-16/epoxy composites under tensile and bending loads showed only tensile (or compressive) failure. The composites of epoxy/PAN (polyacrylonitrile)-based fibers (AS4) showed greater ILSS than those of the pitch-based fiber (VSB-16)/epoxy. The most characteristic features of the interlaminar shear failure surface of AS4/epoxy composites are delamination and formation of hackles.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2016-06-07
    Beschreibung: The results of a two wavelength (VHF and UHF) mesosphere experiment performed at the Arecibo Observatory on January 5, 1981 are discussed. The 46.8-MHz VHF radar (3.21 m Bragg scale) was operated to provide spectral measurements of signals scattered from refractivity fluctuations due to turbulence. Other physical parameters such as radial velocities, scattered signal power, and Doppler spread due to turbulence can be derived from signal spectra. The 430-MHz UHF radar (0.36 m Bragg scale) was used for D-region electron-density measurements using the incoherent scatter technique with a comparable height resolution. The radars were pointed symmetrically about the vertical with a beam spacing of 5.5 degree in the meridional plane. Occurrence of a type 4 solar flare during the experiment produced enhanced D-region electron-density gradients. This was a unique circumstance that provided the possibility of testing the basic premises of the turbulent gradient-mixing hypothesis.
    Schlagwort(e): GEOPHYSICS
    Materialart: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Vol. 20; 8 p
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2016-06-07
    Beschreibung: Scattering of radio waves from atmospheric refractive-index irregularities induced by turbulence was invoked almost four decades ago to explain the characteristics of signals received on VHF/UHF ionospheric and tropospheric forward-scatter links. Due to the bistatic geometry of these links a slender, horizontally extended, common volume or cell is formed in space. The principal contribution to scattering arises from refractive-index fluctuations in this volume at the Bragg wave number K approx. sub B = K approx. sub i -k approx. sub s vectors. It has been surmised that the use of more than one frequency in probing the middle-atmosphere regions should help resolve several issues pertaining to the scattering mechanism. These issues are briefly re-examined in this note. The implications of the radar equation are discussed. The problems arising due to layered structure of turbulence and the choice of frequencies most suitable for multifrequency measurements are considered.
    Schlagwort(e): GEOPHYSICS
    Materialart: International Council of Scientific Unions Middle Atmosphere Program: Handbook for MAP. Vol. 14; p 121-125
    Format: application/pdf
    Standort Signatur Erwartet Verfügbarkeit
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