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  • 1990-1994  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Change in electrophoretic mobility of HL-60RG cells by apoptosis (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 487-492 
    Details
    ISSN: 1435-1536
    Keywords: Electrophoretic mobility ; apoptosis ; HL-60RG cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We measured the electrophoretic mobilities of HL-60RG cells and their apoptotic cells triggered by Actinomycin D as a function of the ionic strength of the suspending medium at pH 7.4. Both types of cells showed negative mobilities. The apoptotic HL-60RG cells exhibited larger mobility values in magnitude than intact HL-60RG cells in the whole range of the electrolyte concentration measured. The obtained data were analyzed via a mobility expression for “soft particles’, that is, colloidal particles with ionpenetrable surface layers. The observed mobility difference between the intact and apoptotic HL-60RG cells was found to be due mainly to the difference in friction exerted by the cell surface layers on the liquid flow around the cells between these two types of cells rather than the difference in charge density in their surface layers. A possible explanation for this mobility change by apoptosis is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659462
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of correction accuracy of several schemes for AES matrix effect correctionsPaper presented at ECASIA 89, Antibes, France, 23-27 October 1989. (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 466-472 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A matrix effect correction is required to improve the accuracy of quantitative AES analysis. The correction includes terms involving the atomic density (n), electron back-scattering factor (R) and electron escape depth (L). Many schemes have been proposed by various people for corrections of the R and L terms. However, up to now, there have been no systematic investigations of the correction accuracy of the proposed schemes. We have evaluated the correction accuracy, based on measured intensity data for Au—Cu alloys of different compositions. Comparison was made between the observed intensity ratio K (=Iunk/Istd) and the calculated intensity, ratio K′ (= C(nunk/nstd)(Runk/Rstd)(Lunk/Lstd)), where C and I represent the concentration and intensity, respectively. The superscripts ‘unk’ and ‘std’ denote that the parameters are for unknown and standard specimens, here the pure elements. If the correction works well, the error Er (= K′ — K)/(K) will become smaller. Evaluations were carried out on three schemes for the R correction and on seven schemes for the L correction using the Au 239 eV, Au 2024 eV and Cu 920 eV transitions. The root mean square (RMS) of the calculated errors showed several per cent for the best case and 20-30% for the worst case. The RMS error varied a few per cent between schemes for the R correction but it varied ∼30% for the L correction.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740150805
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Calculations of electron inelastic mean free paths. III. Data for 15 inorganic compounds over the 50-2000 eV range (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 927-939 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We report calculations of electron inelastic mean free aths (IMEPs) of 50-2000 eV electrons in a group of 15 inorganic compounds (Al2O3, GaAs, GaP, InAs, InP, InSb, KCl, LiF, NaCl, PbTe, SiC, Si3N4, SiO2 and ZnS). As was found in similar calculations for a group of 27 elements, there are substantial differences in the shapes of the IMFP versus energy curves from compound to compound for energies below 200 eV; these differences are associated with the different inelastic electron scattering characteristics of each material. Comparisons are made of the calculated IMFPs and the values calculated from the predictive IMFP formula TPP-2 developed from the IMFP calculations for the elements. Deviations in this comparison are found, which correlated with uncertainties of the optical data from which the IMFPs were calculated. The TPP-2 IMFP formula is therefore believed to be a more reliable means for determining IMFPs for these compounds than the direct calculations.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740171305
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Calculations of electron inelastic mean free paths. V. Data for 14 organic compounds over the 50-2000 eV range (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 21 (1994), S. 165-176 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We report calculations of electron inelastic mean free paths (IMFPs) of 50-2000 eV electrons for a group of 14 organic compounds: 26-n-paraffin, adenine, β-carotene, bovine plasma albumin, deoxyribonucleic acid, diphenylhexatriene, guanine, kapton, polyacetylene, poly(butene-1-sulfone), polyethylene, polymethylmethacrylate, polystyrene and poly(2-vinylpyridine). The computed IMFPs for these compounds showed greater similarities in magnitude and in the dependences on electron energy than was found in our previous calculations for groups of elements and inorganic compounds (Papers II and III in this series). Comparison of the IMFPs for the organic compounds with values obtained from our predictive IMFP formula TPP-2 showed systematic differences of ∼40%. These differences are due to the extrapolation of TPP-2 from the regime of mainly high-density elements (from which it had been developed and tested) to the low-density materials such as the organic compounds. We analyzed the IMFP data for the groups of elements and organic compounds together and derived a modified empirical expression for one of the parameters in our predictive IMFP equation. The modified equation, denoted TPP-2M, is believed to be satisfactory for estimating IMFPs in elements, inorganic compounds and organic compounds.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740210302
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Calculations of electron inelastic mean free paths (IMFPS). IV. Evaluation of calculated IMFPs and of the predictive IMFP formula TPP-2 for electron energies between 50 and 2000 eV (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 77-89 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We have made additional evaluations of the electron inelastic mean free paths (IMFPs) and of the predictive IMFP formula TPP-2 presented in papers II and III of this series. Comparisons have been made with other formulae for the IMFPs and electron attenuation lengths (ALs). We find substantial differences between our IMFP results for 27 elements and 15 inorganic compounds and the AL formulae of Seah and Dench; these differences include different dependences on electron energy and on material parameters. We present IMFP calculations for Al2O3 and GaAs from TPP-2 in which each parameter of the formula is varied in some physically reasonable range about the true value for each compound; these results show the sensitivity of the computed IMFPs to the choices of parameter values. Finally, we give a summary of sources of uncertainty in the IMFP algorithm, in the experimental optical data from which IMFPs are calculated, and of the TPP-2 formula. We conclude that TPP-2 is robust and useful for predicting IMFPs for electron energies and material parameter values in ranges for which the formula was developed and tested.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740200112
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  • 6
    Electronic Resource
    Electronic Resource
    Calculations of electorn inelastic mean free paths. II. Data for 27 elements over the 50-2000 eV range (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 911-926 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We report calculations of electron inelastic mean free paths (IMFPs) for 50-2000 eV electrons in a group of 27 elements (C, Mg, Al, Si, Ti, V, Cr, Fe, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Re, Os, Ir, Pt, Au and Bi). This work extends our previous calculations (Surf. Interface Anal. 11, 57 (1988)) for the 200-2000 eV range. Substantial variations were found in the shapes of the IMFP versus energy curves from element to element over the 50-2000 eV range and we attribute these variations to the different inelastic scattering properties of each material. Our calculated IMFPs wee fitted to a modified form of the Bethe equation for inelastic electron scattering in matter; this equation has four parameters. These four parameters could be empirically related to several material parameters for our group of elements (atomic weight, bulk density and number of valence electron per atom). IMFPs and those initially calculated was 13%. The modified Bethe equation and our expressions for the four parameters can therefore be used to estimate IMFPs in other materials. The uncertainties in the algorithm used for our IMFP calculation are difficult to estimate but are believed to be largely systematic. Since the same algorithm has been used for calculating IMFPs, our predictive IMFP formula is considered to be particularly useful for predicting the IMFP dependence on energy in the 50-2000 eV range and the material dependence for a given energy.
    Additional Material: 33 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740171304
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