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  • 1
    Electronic Resource
    Electronic Resource
    Direct observation of local hot electron transport through Al2O3 tunnel junctions (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1076-1078 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A modified ballistic electron emission microscopy (BEEM) technique using local transport of hot electrons through a buried interface, was successfully applied to study the Al2O3 barrier in the Co/Al2O3/Ru tunnel junction. This technique enabled us to straightforwardly measure an effective barrier height of 1.7 eV and to observe the rise of the barrier height due to continuous current injection into a single point of the junction attributed to charging effects and/or degradation of the barrier structure. Scanning over an area of 510 nm×510 nm showed a spatial inhomogenity of the barrier resulting in different dependencies of the BEEM current on the energy of the injected electrons. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448160
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  • 2
    Electronic Resource
    Electronic Resource
    Lysosomal enzyme activities in different types of amniotic fluid cells measured by microchemical methods, combined with interference microscopy (1978)
    Springer
    Human genetics 〈Berlin〉 40 (1978), S. 285-292 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In primary amniotic fluid cultures, four distinct types of cells were characterized as epithelioid (E I and E II), fibroblast-like (F), and large cells. Small numbers (1–200) of freeze-dried cells were isolated from colonies of each cell type and analyzed for the activity of three lysosomal enzymes: β-N-acetylglucosaminidase, β-galactosidase, and α-glucosidase. When expressed per cell, the activities for each of the enzymes were not significantly different among the small types of cells (EI, EII, and F). However, 5 to 10-fold higher enzyme activities were found in the large cells. The dry mass of individual large cells, as measured by microinterferometry, was also 5 to 10 times higher than that of the smaller cell types. When expressed per unit of dry mass, the enzyme activities tested, appeared to be independent of the type of amniotic fluid cell. The significance of this observation for the rapid prenatal diagnosis of metabolic diseases is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272189
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  • 3
    Electronic Resource
    Electronic Resource
    Methodology of the quantitative cytochemical analysis of single or small numbers of cultured cells (1974)
    Springer
    Journal of molecular histology 6 (1974), S. 409-429 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Synopsis The possibility of obtaining from small numbers of cultured cells, or even single cells, quantitative data on the activity of enzymes involved in hereditary metabolic diseases offers perspectives in early prenatal diagnoses and in the investigation of specific cell types in a mixed cell culture. The present paper deals with the methodology of preparing human fibroblasts and amniotic fluid cells and with their microchemical analyses using (sub)microlitre volumes. Various methods of cell preparation are compared. For the investigation of a few hundred cells down to a single (hybrid) cell, microdissection from freeze-dried cultures grown on thin plastic foil proved to be a suitable procedure. In model experiments of spectrophotometric and fluorometric methods using mainly products formed by lysosomal hydrolases, the increases in sensitivity which can be obtained by reducing the incubation and final volumes were investigated. When extinction and fluorescence were measured in microlitre volumes in a glass capillary using a Leitz microscope-photometer, amounts down to 10−11 mole (spectrophotometry) and 10−14 mole (fluorometry) could be detected accurately. As the activities of many lysosomal enzymes inivolved in metabolic diseases are in the range of 10−13 to 10−15 mol/hr/cell, quantitative assays on a few hundred and in some instances on single cultured human (hybrid) cells has now become feasible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01012433
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  • 4
    Electronic Resource
    Electronic Resource
    Some computational aspects of elastic-plastic large strain analysis (1981)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 17 (1981), S. 15-41 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The governing equations for large strain analysis of elastic-plastic problems are reconsidered. An improved form of these equations is derived, which is valid for small increments of strain and large increments of rotation. Special attention is paid to the integration procedures for these equations in the deformation history. It is shown that the tangent modulus procedure for integration of the constitutive equations is conditionally stable, and that implicit methods, such as the ‘mean normal’ method, are to be preferred. A novel procedure is introduced for the treatment of nonlinear geometric effects. The performance of various element types is examined, with specific attention to effects of ‘locking’ and distortion. Several applications are discussed to illustrate the various aspects of the formulation developed ein this paper.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620170103
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