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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 3539-3554 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The quantitative analysis of the near-edge region of K-shell excitation spectra of free, chemisorbed, condensed, and polymeric molecules is undertaken using curve fitting procedures. The deconvolution of both x-ray absorption (NEXAFS) and electron impact near-edge excitation spectra is considered. Among the topics discussed are the line shape of resonances in the near-edge region, the line shape of the continuum steps, physical interpretations for the line shapes, and parameters describing core excitation spectral features, and background corrections for NEXAFS spectra. The goal of the work is to establish systematic procedures for analyzing near-edge spectra which allow peak positions to be consistently determined, and enable peak areas to be reliably obtained so that, e.g., the orientation of molecules can be determined from NEXAFS spectra. A more quantitative understanding of the features in near-edge spectra will also aid development of an understanding of the physical events underlying a near-edge spectrum.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 4076-4087 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Carbon K-shell NEXAFS (near edge x-ray absorption fine structure) spectra of oriented hydrocarbon chains in Langmuir–Blodgett (LB) monolayers were measured and used to study the orientation of these molecules. The LB monolayers were assembled from arachidic acid or cadmium or calcium arachidate on the oxidized Si(111) surface. The observed NEXAFS resonances are assigned to transitions to excited states which are localized on individual CH2 groups or C–C bonds. From a detailed analysis using curve-fitting techniques of the angular dependence of the various spectral peaks, the hydrocarbon chains of the cadmium arachidate monolayer is estimated to lie within 15° of the surface normal, the hydrocarbon chains of the calcium arachidate monolayer is estimated to be tilted by 33±5° from the surface normal, while the arachidic acid monolayer is not ordered at all. The determined chain orientations are discussed in terms of a microscopic model involving lateral interactions between the zig–zag hydrocarbon chains.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 21 (1974), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Structure, function, and development of mastigonemes (flagellar hairs) of 2 chrysophycean flagellates were examined with light and electron microscopy in whole mount and sectioned preparations. Mastigonemes of both organisms are identical, consisting of a tapered base 0.25–0.3 μm long, maximum width of 0.03 μm; a hollow shaft 0.85 μm × 23 nm; and 2 types of laterally projecting filaments. Two rows of mastigonemes are attached to the long flagellum, one on each side in the same plane as the central pair of microtubules. One row is composed of single mastigonemes while the other bears them in “tufts.” The primary mastigonemal attachment is on the flagellar membrane. Developmental sequences as supported by electron micrographs and kinetic studies demonstrate the intracellular location of promastigonemes during reflagellation, colchicine-inhibited reflagellation, and release from inhibition. The promastigonemes first appear in the peri-nuclear space in association with the outer nuclear membrane and several dozen may accumulate there. These may pinch off as bundles and move into the cytoplasm, or if mastigonemes are being utilized rapidly by the cell, the promastigonemes are channeled a few at a time from the perinuclear space into the Golgi apparatus where some structural modifications are made. The mastigonemes are then transported in Golgi-derived secretory-type vesicles to the cell surface near the base of the growing flagellum where the vesicle membrane fuses with the plasma membrane and the mastigonemes become extracellular, although the membrane association is retained. The origin of the asymmetric arrangement of mastigonemes on the flagellum is discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 18 (1971), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. A careful re-examination with refined technics of the ultrastructure of the formation of calcified scales (coccoliths) in the marine unicellular alga Hymenomonas carterae has yielded new and more detailed information about the structure and morphogenesis of these unique and complex Golgi-elaborated organelles. The coccolith rim is formed from 2 distinct, alternating, anvil-shaped elements, 13–16 each, fitted together with a “right-handed” asymmetry. The coccolith is assembled in Golgi cisternae from 2 precursors, a single, scale-like base and multiple granular elements called coccolithosomes. The association of scales and coccolithosomes and subsequent development to the mature coccolith occur in a characteristic sequential fashion within what is one of the better examples of a polarized Golgi. Morphogenesis involves a special cisternal membrane association with the base of the coccolith, the contribution of granular material by coccolithosomes to form the outer rim matrix, and the subsequent filling of the area enclosed by the matrix with an electron-dense material, presumably CaCO3. A “microenvironment” model system for species specific shape-determination of calcified elements is proposed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 14 (1967), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Colpoda elliotti n. sp., found in an enrichment culture from deer droppings, is a small (15–28 by 7.5–17 μ) member of the genus with prominent, rigid, tooth-like processes set between the kineties in the posterior 2/3 of the body. These “teeth” give it a distinctive outline even when viewed at low magnifications. The usual number of kineties is 12; the number of keel notches is 4. Multiplication occurs in reproductive cysts yielding typically 4 tomites. Thick-walled, resting cysts are also formed.The nuclear apparatus includes a single, crescentic ***micronucleus and a broadly elliptical macronucleus. The latter contains Feulgen-positive material in a few large masses, but no central nucleolus.The possibility that this species along with other members of the genas is perhaps more closely related to the Hymenostomatida than to the Trichostomatida as now defined is discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 141 (1984), S. 240-254 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Solid State Communications 54 (1985), S. 493-496 
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science Letters 141 (1984), S. A197 
    ISSN: 0167-2584
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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