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  • 1
    Electronic Resource
    Electronic Resource
    On the properties of the 1s-forms of TaSe"2 and TaS"2
    Amsterdam : Elsevier
    Solid State Communications 10 (1972), S. 75-78 
    Details
    ISSN: 0038-1098
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0038-1098(72)90351-1
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  • 2
    Electronic Resource
    Electronic Resource
    The crystal structures of niobium(III) selenide and tantalum(III) selenide (1968)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 24 (1968), S. 1102-1106 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567740868003754
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  • 3
    Electronic Resource
    Electronic Resource
    Development and optimization of pharmaceutical formulations using a simplex lattice design (1984)
    Springer
    Pharmacy world & science 6 (1984), S. 185-194 
    Details
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The composition of pharmaceutical formulations is often subject to trial and error. This approach is time consuming and unreliable in finding the best formulation. Optimization by means of an experimental design might be helpful in shortening experimenting time. Such a design with the concomitant mathematical models, reveals effects and interactions of the variables. The independent variables are the different compositions of the mixtures of the chosen ingredients [drug(s) and excipients]. The dependent variables are the properties (responses) of the formulation. When all responses of interest have been expressed in models that describe the response as a function of the composition of the mixture, the models can be combined graphically or mathematically to find a composition satisfying all demands. In this paper an introduction to the use of mixture designs will be given by means of a theoretical part and an example: optimizing a tablet formulation consisting of excipients only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01999941
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of models used to calculate left ventricular wall force (1980)
    Springer
    Medical & biological engineering & computing 18 (1980), S. 133-144 
    Details
    ISSN: 1741-0444
    Keywords: Ellipsoidal models ; Laplace's law ; Left ventricular wall force ; Myocardial wall stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Myocardial wall force per area (=stress) is a major determinant of muscle function and oxygen consumption. It cannot be measured accurately but has to be derived from a mathematical model. Many models have been presented in the literature but a comparison between models has not been available. In this study angiographic data from the literature are used to calculate left ventricular wall force for normal and diseased hearts using a thin-walled spherical model, a thick-walled spherical model and six ellipsoidal models, and the results are compared. There appeared to be large differences between the stresses yielded by the models for the same cardiac geometry. The thick-walled sphere yields circumferential stresses that are approximately 25% lower than the stresses yielded by most of the ellipsoidal models. Of the ellipsoidal models the one suggested by Streeter el al. gives circumferential stresses that are 25% higher than those of the other ellipsoids. Similar differences are found for left ventricular wall stress in the longitudinal direction. However, all models correspond closely in the prediction of the deviation from normal stress in the various pathological states studied. Some of the models give information about the stress distribution over the thickness of the wall as well. We found substantial differences in this predicted stress distribution for models that employ similar assumptions. These differences plus the uncertainties with regard to the properties of the myocardial wall material, that change during the cardiac cycle, call for some scepticism concerning the calculated stress distribution over the wall. The ellipsoidal model suggested by Falsetti et al. is very simple and yields approximately the same mean wall stress values as the more complicated models that we studied. This model therefore appears to be the best choice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443288
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of winding speed, drawing and heating on the crystalline structure of nylon 6 yarns (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 713-732 
    Details
    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: Nylon 6 yarns were wound at speeds varying from 700 to 5500 mpm. The effect of the winding speed on both α- and γ-type crystals in these undrawn yarns was studied. Also the effects of dry heat, tension, and heating in saturated steam were included in this investigation, since they provide useful information for drawing and heat-setting processes. The emphasis was put on the characterization of the crystalline part of the yarns. By applying recently developed techniques, relative amounts of the two crystalline components, as well as their orientation factors, could be determined. Concerning the undrawn, conditioned yarns, it was found that the amount of γ type increases with the winding speed. The γ crystals are much better oriented than the α crystals, and the crystal dimensions of the γ structure largely depend on the winding speed in contrast to those of the α crystals. Indications were found that γ crystals are mainly generated from orientation-induced nuclei at speeds higher than 2500 mpm and that α crystals grow slowly at relatively low temperatures after moisture pickup during conditioning. Drawing at high ratios causes a transition from γ to α, while the thermal stability of the γ crystals appears to be slightly below that of the α crystals, resulting in γ crystal to α crystal transitions at extremely high temperatures or under usual autoclaving conditions.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260229
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of spinning speed and drawing temperature on structure and properties of poly(ethylene terephthalate) yarns (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 595-616 
    Details
    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: From an industrial point of view, it is effective to have a relation between process conditions and resulting product properties. In practice there are many possible process conditions, whereas properties are generally interrelated in a complex way. Thus, there is a strong need for a physical understanding of the product properties in terms of process settings. This comprehension should also allow one to predict possible consequences for the properties when new process conditions become available. To obtain that physical understanding for the development of production processes of PET yarns, use has been made of a simple two-phase model of crystalline and amorphous regions. As process parameters the spinning speed and the drawing temperature were chosen. As the drawing temperatures are only known as machine-setting values, they are simply referred to as “low” and “high.” As mechanical properties the shrinkage, modulus, tenacity, and dynamic mechanical behavior are discussed.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370302
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of winding speed on the physical structure of as-spun poly(ethylene terephthalate) fibers, including orientation-induced crystallization (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 2229-2243 
    Details
    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: As-spun fibers of poly(ethylene terephthalate), PET, made at winding speeds ranging from 2000 to 6000 m/min exhibit quite different physical structures. Yarns wound at relatively low speeds are amorphous, whereas those spun at high speeds contain well-developed crystals of closely packed molecules. In this study the structures have been characterized by means of various techniques such as differential scanning calorimetry, x-ray diffraction, density, and pulse propagation measurements. Based on the results obtained, an arrangement of the molecules in the various yarns is proposed. It is shown that these arrangements can account for the extreme wide variety in contraction behavior found experimentally. Finally, the results obtained are compared with those of other investigations into orientation-induced crystallization.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1978.070220815
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  • 8
    Electronic Resource
    Electronic Resource
    Infrared spectra of poly(ethylene terephthalate) yarns. Fitting of spectra, evaluation of parameters, and applications (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 3069-3093 
    Details
    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: A quantitative model for fitting infrared spectra of polyethyleneterephthalate samples over the region from 1100 to 720 cm-1 has been evaluated. The absorbance was described as the sum of a linear base line and a set of symmetrical bell-shaped Pearson VII curves. Using this model, experimental transmission spectra of yarns, measured with the electric vector parallel and perpendicular to the fiber axis, were fitted. It was found that each of the trans bands near 972 and 845 cm-1 consists of two components, a narrow and a broad one. These two components represent the crystalline and amorphous phases respectively. The band due to the out of plane benzene ring C—H deformation vibration at about 875 cm-1 appeared also to be composed of two contributions. In this case, the narrow component was found to be due to molecules having interactions with direct neighbors. So this narrow component not only contains the molecules in the crystalline phase but also those forming part of bundles which are too small to be detected by x-ray diffraction. For a detailed insight into the molecular arrangement of the amorphous regions, the infrared detection of trans-guache transitions, fold content, detection of bundlelike structures, and molecular stress on tie molecules turned out to be of great practical importance. The structural details, which can be revealed by the infrared technique, cannot be obtained by other means. The potential of the method is illustrated with some practical examples.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300728
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  • 9
    Electronic Resource
    Electronic Resource
    A quantitative description of the effect of process conditions on the physical structure of poly(ethylene terephthalate) yarns with an application to dyeing behavior (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 943-965 
    Details
    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 intrinsic properties of a yarn are brought about by its physical structure. This structure in its turn is controlled by the process conditions applied. A quantitative description is given of the effect of temperature, time, and tension during annealing on the structure of poly(ethylene terephthalate) yarns. Annealing of a yarn at elevated temperature leads to improvement of packing of the molecules within the crystals. Consequently, the crystalline density is not a constant but is largely dependent on the conditions under which crystallization has taken place. The growth of the PET crystals is not an isotropic process; the strongest growth is observed in the direction of the dipole interactions. The effects of tension and annealing time are also discussed. A prolonged annealing time causes an increase in crystallinity, while time and tension influence the growth of the crystals to some extent. However, for the experimental conditions used in this investigation, temperature is by far the most important factor. Generally speaking, PET fibers annealed at low temperature show low crystallinity built up of many small crystals. Yarn annealed at a high temperature, on the other hand, is composed of fewer big crystals together with large adjacent amorphous regions and relatively high overall crystallinity. Finally, the effect of this observed structural morphology on the dyeing behavior of PET yarns is discussed in a qualitative way. Two main effects controlling the dye uptake of PET yarn are proposed, viz., the total amount of amorphous regions and the accessibility of these regions.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1978.070220407
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  • 10
    Electronic Resource
    Electronic Resource
    Quantitative information from x-ray diffraction of nylon-6 yarns. II. Physical aspects of some quantitative parameters (1976)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 14 (1976), S. 941-954 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A mathematical model developed in an earlier paper describes the experimental x-ray profiles of equatorial nylon-6 reflections in terms of Pearson VII functions. The present paper deals with the physical aspects and interpretations of the interrelations of the parameters obtained and the relation between these parameters and the results of other types of measurements. It was found that the growth of the crystallites perpendicular to the chain axis is not isotropic, the strongest growth being in the direction of the hydrogen bonds. Growth and perfection of the crystallites are found to be highly correlated. Large crystals are related to short distances between the planes containing the hydrogen bonds and so to densely packed, i.e., perfect unit cells. This correlation forms the basis for the observed similarity between our quantification technique and the method of the crystal perfection index introduced by Statton. Curve resolution, however, makes the method better applicable for poorly crystallized samples. Comparison of the results with those of small-angle x-ray scattering gave a high degree of consistency with respect to the determined crystal size. In the literature mention is made of a relation between the dimensions and the melting point of the crystals; this relation is confirmed by comparing the appropriate x-ray parameters with DTA results of methoxymethylated nylon 6-yarns.Information about the γ-phase can be obtained from equatorial and meridional reflections. The expected relationship between the relevant peak areas was established. This reported evidence shows the physical validity of the parameters obtained using the Pearson VII model for the analytical description of x-ray reflections of nylon-6 yarns.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1976.180140515
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