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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 1143-1166 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Nous prouvons par des méthodes géométriques élémentaires et dans le cadre de l'approximation de Born-Oppenheimer, que quand les noyaux d'une molécule sont dissociés en amas séparés dans l'espace, les énergies moléculaires discrètes tendent vers la somme des énergies des sous-systèmes isolés. Nos méthodes montrent aussi que les projections spectrales associées au spectre moléculaire discret tendent asymptotiquement vers des sommes directes de projections spectrales convenables pour les sous-systèmes isolés. Ces résultats s'appliquent à n'importe quel système de particules qui interagissent par des potentiels de paire s'annulant asymptotiquement. Nous prouvons que le développement en 1/R pour des courbes de potentiel moléculaires discrètes est asymptotique quand R → ∞, et nous discutons le comportement des coefficients de ce développement pour l'état fondamental de H2+.Wir beweisen durch elementare geometrische Methoden und im Rahmen der Born-Oppenheimer-Näherung, dass, wenn die Kerne eines Moleküls in räumlich separierten Clusters dissoziiert werden, die diskreten Molekülenergien Summen der Energien der isolierten Untersysteme zustreben. Unsere Methoden zeigen auch, dass die mit dem diskreten Molekularspektrum assoziierten Spektralprojektionen asymptotisch direkten Summen von geeigneten Spektralprojektionen für die isolierten Untersysteme zustreben. Diese Ergebnisse sind für irgendein System von Teilchen gültig, die durch asymptotisch verschwindende Paarpotentiale wechselwirken. Wir beweisen, dass die Entwicklung in 1/R für diskrete molekulare Potentialkurven wenn R → ∞ asymptotisch ist, und wir diskutieren das Verhalten der Koeffizienten dieser Entwicklung für den Grundzustand von H2+.
    Notes: We prove by elementary geometric methods and within the Born-Oppenheimer approximation that as the nuclei of a molecule are dissociated into spatially separated clusters, the discrete molecular energies approach sums of the energies of isolated subsystems. Our methods also show that the spectral projections associated with the discrete molecular spectrum asymptotically approach direct sums of suitable spectral projections for the isolated subsystems. These results apply to any system of particles interacting by asymptotically vanishing pair potentials. We prove that the 1/R expansion for discrete molecular potential curves is asymptotic as R → ∞, and we discuss the behavior of the coefficients of the 1/R expansion for the ground state of H2+.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 1579-1593 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal motions of the atoms in a dynamical simulation of ferrocytochrome c are geometrically decomposed into local and highly collective components, and the contributions of these components to the net motion are determined for different intervals of time. It is found that the atomic displacement magnitudes and anisotropies are governed by local motions for times 〈10-12s, but that the highly collective motions tend to be dominant at longer times. Variations in this behavior are noted among different groups of atoms. Orientational correlations between the preferred directions of atomic displacement and elements of the protein structure are analyzed as a function of time scale. Finally, several sinificant implications of these results with respect to protein structure and function are considered.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 58 (1998), S. 333-338 
    ISSN: 0006-3592
    Keywords: Catharanthus roseus ; hairy roots ; indole alkaloids ; tabersonine ; elicitation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this article, we present a review of the current state of metabolic engineering in Catharanthus roseus. A significant amount of research has contributed to characterization of several individual steps in the biosynthetic pathway of medicinally valuable alkaloids. However, knowledge of the regulation of these pathways is still sparse. Using hairy root cultures, we studied the responses of alkaloid metabolism to environmental stimulation such as light and elicitation. Through precursor feeding studies, the putative rate-limiting steps of the terpenoid pathway in hairy root cultures also have been examined. Relating this knowledge to specific events at the molecular level, and the cloning of corresponding genes are the next key steps in metabolic engineering of the C. roseus alkaloids. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:333-338, 1998.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 670-678 
    ISSN: 0006-3592
    Keywords: Catharanthus roseus ; hairy roots ; indole alkaloid ; light adaptation ; tabersonine ; lochnericine ; hörhammericine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cultures of C. roseus transgenic (“hairy”) root clones LBE-6-1 and LBE-4-2 were adapted with periodic daily illumination to investigate the effect of light on growth and nutrient utilization, and the accumulation of the indole alkaloids. Light-adapted roots appeared green and had radially thickened morphology compared with dark-grown controls. Their growth rates were higher than dark-grown controls, with 45% lower doubling times: LBE-6-1, 3.6 days; LBE-4-2, 2.8 days. Relative to dark-grown controls, light-adapted growth increased the biomass (DW) of LBE-6-1 by 25%, but had no effect on the DW of LBE-4-2. The macronutrients NH4+, NO3-, Pi, and sugars, were depleted completely by light-adapted root cultures in that order. The specific and total levels of the indole alkaloid serpentine was enhanced and of tabersonine was lowered in both root clones, while the overall trends of growth and non-growth association of tabersonine and serpentine, respectively, remained unaltered by light adaptation. Ajmalicine accumulation was enhanced in LBE-6-1, but lowered in LBE-4-2; its accumulation was growth-associated in dark-grown LBE-6-1, but appeared non-growth associated in light-adapted cultures. The accumulation of tabersonine-related compounds, lochnericine, and hörhammericine exhibited growth-associated trends, and were either negatively affected or unaffected by light adaptation of LBE-6-1. Neither vindoline nor its precursor, deacetylvindoline, was detected. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 670-678, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 1118-1120 
    ISSN: 1040-0397
    Keywords: Portable instrumentation ; Battery powered ; Flow injection ; Iodide ion-selective electrode ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A battery powered portable monitor based on flow injection potentiometry has been developed weighing 1.8 kg, constructed in a carry-case and applicable for remote site monitoring. Portability has been achieved using a light weight rechargeable Ni-Cd battery-pack (7.2 V). The flow injection manifold incorporates a low powered peristaltic pump, a wall-jet type flow cell containing a commercial iodide ion-selective electrode and a Ag/AgCl reference electrode connected to an analog-to-digital converter, also powered by the battery pack, and a RS232-serial output to a notebook computer for real-time data display and storage. The system performance has been evaluated using the iodide ion-selective electrode, including the effects of various carrier solutions on sample peak heights, peak widths and the calibration slopes and working ranges. Fast response with peak widths as low as approximately 10 s. was observed with near Nernstian response of -53.8 mV change per activity decade and a log-linear range between 5 × 10-6 and 1 × 10-2M in a 0.1 M sodium acetate carrier stream.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 13 (1939), S. 269-279 
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A tandem time-of-flight mass spectrometer Incorporating a fast atom bombardment source has been designed and constructed for the purpose of studying collision-induced decomposition spectra. A deflection of the secondary ion beam is used to form the ion packets for time-of-flight analysis. A floating collision cell that represents a potential barrier to ions transversing the time-of-fiight tube enables ionic and neutral fragments from collision-induced decomposition reactions to be separated in time from the parent ion. The instrument operating in the tandem mode is capable of performing charge exchange and collision-induced decomposition studies of both positive and negative incident ions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 14 (1990), S. 39-45 
    ISSN: 0741-0581
    Keywords: Exocrine pancreas ; Cryofixation ; Cryomicrotomy ; Freeze-drying ; Freeze-substitution ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This paper describes and compares the morphology of a relatively complex tissue, the exocrine pancreas, prepared by state-of-the-art anhydrous cryoprocedures. Cryopreparative procedures are being used increasingly for a wide range of applications, for example, electron-probe x-ray microanalysis and immunocytochemical localization of antigenic molecules, because they preserve the composition of the specimen better than procedures involving aqueous media. Some doubts have remained concerning the morphology of cryosections and the precise identification of subcellular structures.We show that thin and sufficiently large cryosections of fresh biological tissues can be produced using commercially available hardware. The freeze-dried cryosections display high intrinsic contrast, are stable under the beam, and allow identification of intracellular fine structure.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
  • 10
    Publication Date: 2017-09-07
    Description: Ant-plant protection symbioses, in which plants provide food and/or shelter for ants in exchange for protection from herbivory, are model systems for understanding the ecology of mutualism. While interactions between ants, host plants, and herbivores have been intensively studied, we know little about how plant-plant interactions influence the dynamics of these mutualisms—despite strong evidence that plants compete for resources, that hosting ants can be costly, and that host-plant provisioning to ants can therefore be constrained by resource availability. We used field experiments in a semi-arid Kenyan savanna to examine interactions between the ant-plant  Acacia drepanolobium , neighboring grasses, and two species of symbiotic acacia-ants with divergent behaviors:  Crematogaster mimosae , an aggressive symbiont that imposes high costs to host trees via consumption of extrafloral nectar, and  Tetraponera penzigi , a less-protective symbiont that imposes lower costs because it does not consume nectar. We hypothesized that by competing with acacias for resources, neighboring grasses (a) reduce hosts’ ability to support costly  C. mimosae , while having little or no effect on the ability of hosts to support low-cost  T. penzigi , and (b) reduce sapling growth rates irrespective of ant occupant. We factorially manipulated the presence/absence of grasses and the identity of ant occupants on saplings and evaluated effects on colony survivorship and sapling growth rates over 40 weeks. Contrary to prediction, the high-cost/high-reward nectar-dependent mutualist  C. mimosae  had higher colony-survival rates on saplings with grass neighbors present. Grasses appear to have indirectly facilitated the survival of C. mimosae by reducing water stress on host plants; soils under saplings shaded by grasses had higher moisture content, and these saplings produced more active nectaries than grass-removal saplings. Consistent with prediction, survival of low-cost/low-reward  T. penzigi  did not differ significantly between grass-removal treatments. Saplings occupied by low-cost/low-reward  T. penzigi  grew 100% more on average than saplings occupied by high-cost/high-reward  C. mimosae , demonstrating that mutualist-partner identity strongly and differentially influences demographic rates of young plants. In contrast, contrary to prediction, grass neighbors had no significant net impact on sapling growth rates. Our results suggest that neighboring plants can exert strong and counterintuitive effects on ant-plant protection symbioses, highlighting the need to integrate plant-plant interactions into our understanding of these mutualisms. This article is protected by copyright. All rights reserved.
    Print ISSN: 0012-9658
    Electronic ISSN: 1939-9170
    Topics: Biology
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