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  • Chemistry  (46)
  • Noctuidae  (3)
  • Wiley-Blackwell  (46)
  • Springer  (3)
  • American Institute of Physics (AIP)
  • 2020-2022
  • 1995-1999  (32)
  • 1975-1979  (11)
  • 1960-1964  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 185 (1999), S. 131-141 
    ISSN: 1432-1351
    Keywords: Key wordsHelicoverpa zea ; Noctuidae ; Lepidoptera ; Sex pheromone ; Antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The limits of a male moth's ability to resolve closely spaced odor filaments have been investigated. Male Helicoverpa zea normally respond to their conspecific sex pheromone blend by exhibiting an upwind flight, which culminates in source contact by at least 50% of the bioassayed individuals. When loaded onto the same filter paper source containing this hitherto attractive pheromone blend, or onto a separate filter paper and co-emitted from the same pipette source with pheromone, (Z)-11-hexadecenyl acetate severely reduced upwind flight and source contact by male H. zea. A similar level of upwind flight inhibition was recorded when the antagonist (Z)-11-hexadecenyl acetate was emitted from its own point source placed 1 mm upwind of the pheromone point source, both plumes being simultaneously emitted in a continuous mode to form a confluent strand. However, (Z)-11-hexadecenyl acetate was less effective in reducing upwind flight and source contact when it was isolated and pulsed from its own source, placed 1 mm either upwind, downwind or cross-wind of a pipette source from which pheromone was simultaneously being pulsed, such that both filaments were separated in time by 0.001–0. 003 s. These results suggest that male H. zea are able to distinguish between odor sources separated by as little as 1 mm in space and 0.001 s in time.
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  • 2
    ISSN: 1432-1351
    Keywords: Heliothis ; Noctuidae ; Lepidoptera ; Plume structure ; Behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1) Male Heliothis virescens moths flew upwind to pulsed pheromone plumes. Upon truncation of the pulsed plume males flew into clean air, turning their tracks crosswind (〉 60° relative to directly upwind direction at 0°) within an average of 0.27 s, and were casting, perpendicular to the wind-line (90°), within 0.43 s. 2) The characteristic casting flight in clean air consisted of left-right crosswind reversals, continuing for many seconds without further pheromonal stimulation. Males intercepting a single strand of pheromone during casting flight responded by surging upwind (track angles 〈 60°). The phasic surge lasted only 0.38 s before reverting to crosswind flight (〉 60°). 3) Average templates of responses in two and three dimensions were created. Males controlled their vertical deviations very tightly when in contact with pheromone but upon entering clean air, lateral and vertical excursions became much greater. 4) Males failed to sustain upwind flight to repetitively pulsed plumes generated at 〈 4 filaments/s. At the threshold frequency of 4 pulses/s we show that upwind flights were composed of reiterated surges followed by crosswind casting. As the pulse frequency increased, the tracks became straighter and the single filament cast-surge-cast template could be viewed only sporadically when, for example, a male apparently failed to intercept filaments.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 182 (1998), S. 585-594 
    ISSN: 1432-1351
    Keywords: Key wordsHelicoverpa zea ; Noctuidae ; Lepidoptera ; Single-cell recordings ; Antennal neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Responses of single receptor neurons in the antennae of male Helicoverpa zea to sex pheromone components and to behavioral antagonists were recorded using a cut-sensillum extracellular recording technique. Three types of sensilla were identified from sampling 325 male-specific sensilla trichodea located at the lateral edge of antennomeres. The majority of these sensilla (71%) contained a receptor neuron tuned to the principal sex pheromone component (Z)-11-hexadecenal. A second sensillar type (10%) contained a receptor neuron that responded only to (Z)-9-tetradecenal. A third sensillar type (19%) contained a large-spiking neuron tuned to the secondary pheromone component (Z)-9-hexadecenal, but this neuron also could be stimulated to equivalent spike frequencies by the same emitted amounts of (Z)-9-tetradecenal. A smaller-spiking neuron in this sensillar type responded to two compounds known to act only as behavioral antagonists, (Z)-11-hexadecen-1-ol and (Z)-11-hexadecenyl acetate, and to (Z)-9-tetradecenal. Cross-adaptation studies confirmed the presence of one large- and one small-spiking neuron in the third sensillar type. Dose-response studies correlated to collected stimuli amounts showed that the large-spiking neuron in the third sensillar type was equally tuned to (Z)-9-hexadecenal and (Z)-9-tetradecenal, whereas the smaller-spiking neuron was far more sensitive to (Z)-11-hexadecen-1-ol and to (Z)-11-hexadecenyl acetate than to (Z)-9-tetradecenal.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 1361-1372 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical properties of the 1,N6 - etheno derivative of ApA (εApεA) have been studied. Absorbance and CD measurements suggest that (1) neutral salts tend to unstack this molecule and (2) the stacking interaction is weaker than in ApA. εApεA is found to be quenched strongly with respect to the monomer. (εAMP); this quenching is solvent dependent (1M NaCl 〉 5M NaClo4〉40%glycerol) and increases with the ratio of temperature to viscosity (T/η) in each case. Fluorescence lifetime measurements also reveal a temperature- and solvent-dependent decay which is nonlinear on a semilog plot. In the presence of 95% glycerol, this decay return to linearity. These data have been considered from two points of view: (1) two-state pictures which are based on thermodynamic least-squares fit to quatum yield and CD curves, together with two exponential fits to the decay curves and (2) a dynamical model in which relatives fluorophore motion leads to deexcitation via intramolecular collision. A simple model of type (2) gives qualitative agreement with the observed behavior.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 975-987 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The scope and limitations of the potassium bromide disc technique for the infra-red determination of chain branching in small samples of polyethylene in powder form have been assessed. Many of the samples encountered have an average particle size, prior to grinding with potassium bromide, of about 100 μm and very satisfactory results have been obtained, but the presence of larger particles leads to poor quality discs and inferior results. The well established double beam technique proves suitable for removing the interfering methylene absorption and compensation with polymethylene in the form of a film rather than as a pressed disc is preferable. Difficulties were encountered in preparing branching standards in a uniform and fine powder form, to avoid variation of the absorption coefficient of the 1 378 cm-1 methyl band with particle size. Such powders are best obtained by precipitation from solution rather than by low temperature milling. Despite these problems chain branching measurements may be made with a precision of between 5 and 10% and an accuracy of about 15%.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 437-448 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Probleme, die bei Anwendung der Kompensationsmethode auf IR-spektroskopische Bestimmungen von niedrigen Verzweigungsgraden in Polyäthylenen hoher Dichte auftreten, werden systematisch untersucht. Die erzielbare Genauigkeit wird bestimmt und es wird gezeigt, daß, wenn möglich, eine Korrektur für die Methyl-Endgruppen angewendet werden sollte. Diese ist bei einigen Polymertypen leicht möglich, bei anderen hingegen schwieriger. Als Kompensationskeil im Referenzstrahl des Spektrometers verwendet man besser Polymethylen als hochmolekulares Polyäthylen. Die äußerste Empfindlichkeit, die mit der manuellen Kompensationsmethode erreicht werden kann, liegt bei einem Methylzweig pro 2000 C-Atome. Wenn diese Methode jedoch ergänzt wird durch Computer-Kurvendämpfung und Computer Mittelung über zahlreiche Momentspektren (“C.A.T.”), kann noch eine deutliche Verbesserung im Signal-Rausch-Verhältnis erzielt werden. Damit wird es möglich noch Verzweigungsgrade bis herunter zu 0,1 Methylgruppen pro 1000 C-Atome zu messen.
    Notes: The problems encountered in the infrared spectroscopic estimation of the low levels of chain branching present in high density polyethylene, using the compensation method, are discussed systematically. The precision to be expected has been determined and it is shown that, if possible, a correction should be applied for methyl groups present at the chain ends. This is feasible with some types of polymer but more difficult with others. The compensating wedge in the reference beam of the spectrometer should be made of polymethylene rather than a high molecular weight polyethylene. The ultimate sensitivity of the manual compensation method is about one methyl branch per two thousand carbon atoms. However, when this is supplemented by computer smoothing and off-line computation of average transients (C.A.T.), a significant improvement is obtained in the signal to noise ratio, and branching levels down to 0,1 methyl groups per thousand carbon atoms are readily measured.
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2375-2392 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The techniques of Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) have been used to study the locus of failure of epoxy resin joints. The effects of a long water immersion and the application of a silane-based primer have also been studied. Results indicated that for dry joints fracture occurred near an epoxy resin/metal interface while with water-soaked unprimed joints, fracture occurred interfacially between the adhesive and iron oxide. The application of the primer to the metal surface prior to bonding prevented the formation of a water-formed oxide although fracture was then found to occur through the primer.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 749-762 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In processing full-fat soy flour to an acid-precipitated lipid protein concentrate a byproduct whey fraction results which, because of its high biological oxygen demand, represents a serious disposal problem. Processing of food waste streams by reverse osmosis has received considerable attention because of its low theoretical energy requirement since no phase change is involved. In a previous study at this Center a mathematical model was developed for the diffusive transport of soy lipid protein concentrate whey across cellulose acetate membranes. In this study, pumping energy and power costs combined with membrane life and replacement costs were incorporated into the original model to provide a basis for optimization from an energy cost standpoint. Computer-simulated runs were compared with experimental pilot-plant runs, and the agreement between predicted and actual results was quite good. Water flux rates were in the range of 3 to 7 gal/ft2/day. Computer runs were used to optimize the processing of 100,000 gal/day of soy whey at 8000 ppm biological oxygen demand (BOD). Costs were at a minimum with a six-stage tapered flow primary reverse osmosis treatment over a porous cellulose acetate membrane, followed by a six-stage tapered flow reverse osmosis over a tighter membrane. BOD reduction was 94% at a cost of $5.45/1000 gal.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 633-642 
    ISSN: 0887-624X
    Keywords: free radicals ; grafting ; kinetics ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of grafting a basic monomer, 2-(dimethylamino)-ethyl methacrylate (DMAEMA) to hydrocarbon substrates have been investigated. These systems were chosen as models for the grafting of a homopolymerizable monomer to polyolefins such as polyethylene. The reactions with squalane and n-eicosane were initiated by an organic peroxide, 2,5-dimethyl 2,5 dit-butylperoxy)-3-hexyne; grafting yields become significant at high reaction temperatures and low monomer concentrations. In squalane, the order of reaction with respect to monomer increased from about 1.1 for 0.22-0.44M DMAEMA to almost 2 at 0.69M DMAEMA; the order with respect to initiator was 0.56. The overall activation energy in the 130-160°C temperature range was, however, surprisingly low, 42±5 kJ mol-1. When analytical data were used to separate the overall rate into those for grafting and homopolymerization, different kinetic paths were observed for the competing reactions. These results are interpreted in terms of two different mechanisms; intramolecular chain transfer plays an important role in grafting, while depropagation becomes a major factor in homopolymerization at temperatures above 150°C. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3517-3525 
    ISSN: 0887-624X
    Keywords: peroxide ; vinylsilane ; grafting ; polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The peroxide-initiated grafting of vinyltrimethoxysilane (VTMS) onto dodecane has been examined as a model for grafting onto polyethylene. At 160°C, 2% v/v VTMS and 0.08% v/v initiator, the monomer was grafted onto dodecane with a 59% conversion and an average of 2.37 VTMS grafts per dodecane. These values were obtained by separation of the grafted material through reduced pressure distillation then characterization with FTIR and NMR spectroscopy, mass spectrometry, and gel permeation chromatography. NMR studies strongly indicate that the multiple grafts consist predominantly of multiple single grafts rather than homopolymer grafts. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3517-3525, 1997
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