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  • Analytical Chemistry and Spectroscopy  (12)
  • Nothofagus dombeyi  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Seasonal changes in carbohydrate content and frost resistance of leaves of Nothofagus species
    Amsterdam : Elsevier
    Phytochemistry 28 (1989), S. 759-763 
    Details
    ISSN: 0031-9422
    Keywords: Fagaceae ; Nothofagus dombeyi ; cold hardiness ; sugar accumulation.
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(89)80110-4
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Lipid changes in cold hardened leaves of Nothofagus dombeyi
    Amsterdam : Elsevier
    Phytochemistry 29 (1990), S. 2467-2471 
    Details
    ISSN: 0031-9422
    Keywords: Fagaceae ; Nothofagus dombeyi ; cold hardening. ; cold resistance ; fatty acids ; galactolipids ; leaves ; phospholipids
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(90)85168-F
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Lipid composition of chloroplasts from cold-acclimated and non-acclimated Nothofagus dombeyi
    Amsterdam : Elsevier
    Phytochemistry 30 (1991), S. 763-768 
    Details
    ISSN: 0031-9422
    Keywords: Fagaceae ; Nothofagus dombeyi ; chloroplast membranes ; cold acclimation. ; cold hardening ; cold resistance ; hardening ; membrane lipids
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0031-9422(91)85248-X
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    EDXRF procedure for quantitative analysis matching theoretically generated reference spectra to measured spectraPresented at the European Conference on EDXRS, Budapest, Hungary, 30 May-3 June 1994. (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 24 (1995), S. 277-282 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The diversity of processes that contribute to an x-ray fluorescence spectrum make it difficult to obtain an accurate estimate of the line intensities needed to determine the sample composition in XRF analysis. The radiative contributions forming the spectrum are produced by the interactions that x-ray photons undergo with the atoms of the sample. Many multiple scattering terms contribute to the continuous portions of spectrum that overlap the lines of interest. The lines themselves are formed by the overlap of many narrow (discrete) contributions and some continuous ones: one ‘primary intensity’ plus several enhancement terms. The lines can also interfere with other neighbouring lines produced in the sample. The resulting spectrum, sufficiently complicated at this stage, is still modified in a complex way by the influence of the detector response and successive digitalization by the multi-channel analyser. The difficulties that such spectral complexity introduces in the process of extracting the ‘primary fluorescence intensity’ from the experimental spectrum can be overcome by using a theoretical spectrum of reference that, in this paper, was calculated using the code SHAPE. Such a theoretical spectrum has the property that all the single contributions are well known, and therefore can be used to estimate correctly the fraction of ‘primary fluorescence intensity’ under any experimental line of interest in the real spectrum enclosed between two given energy channels. Since the theoretical spectrum can be computed only for a known composition, the calculated fraction can be initially obtained by feeding SHAPE with an arbitrary composition. The fraction estimated with the theoretical spectrum is used to correct the corresponding peak area in the experimental measured spectrum, which in turn is used to obtain a new calculated composition. This result is used to feed a new spectrum computation, defining an iterative method that converges to the unknown composition. The theoretical details of this iterative method are described and some experimental examples of EDXRF analysis using this technique are given. The advantages of the method for treating some paradigmatic cases of analysis are also illustrated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300240602
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    A theoretical procedure to determine coefficients from the Rasberry-Heinrich calibration curve in XRF spectroscopy (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 10 (1981), S. 74-77 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Relative X-ray fluorescent intensity data have been generated numerically for binary samples under mono-chromatic excitation in those cases of absorption plus enhancement that are dealt with in this work. These data were fitted to the empirical Rasberry-Heinrich equation, keeping both coefficients different from zero, since from our numerical calculations it is shown that in most cases the best fit is achieved when A ≠ 0. Furthermore, this approach shows that a third coefficient introduced into the empirical equation improves the fitting. The aforementioned results suggest that the empirical equation could be deduced from the theoretical equation of fundamental parameters under suitable approximation. The result is an equation similar to that of Rasberry and Heinrich, from which analytical approximated coefficients are obtained. It is then possible to calculate a calibration curve using fundamental parameters values.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300100208
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Thin-film thickness calculation to maximize X-ray fluorescence intensity in transmission arrangements (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 15 (1986), S. 103-105 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Equations were obtained from physical theory to express the fluorescence intensity emitted by a sample in terms of the geometrical parameters of a source-sample-detector cylindrical symmetry arrangement. These equations allow the calculation of the optimum sizes of samples in XRF. The thickness required to maximize the detected fluorescence intensity, in terms of the value of the remaining physical and geometrical parameters, was determined. A thin sample in transmission geometry was considered, where excitation is produced by an isotropic monoenergetic x-ray source. The sizes of the detector and source are such that they are considered to be dimensionless compared with the sample. These approximations do not affect the validity of the results.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300150206
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Polarization effects and photon transport in x-ray spectrometryPresented at the European Conference on EDXRS, Budapest, Hungary, 30 May-3 June 1994. (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 24 (1995), S. 283-292 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The nature of the scattering interactions in the x-ray energy regime makes the effect of polarization extremely important, mainly when the incident beam is partially or totally polarized. The effects of the source polarization on the x-ray spectrum are analysed, stressing the points of interest in each case of unpolarized, linearly polarized and circularly polarized excitation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300240603
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    1H NMR structural study of 2-phenylthiazolidine (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 17 (1981), S. 68-70 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deuteration of 2-phenylthiazolidine, and its complexation with the shift reagent tris(1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionato)europium, have been used to study the signals and conformation of the heterocyclic protons and to interpret the 1H NMR spectrum of this 2-substituted thiazolidine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270170116
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of interelement effects on x-ray fluorescence calibration curve coefficients for binary mixtures (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 11 (1982), S. 70-78 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: It has been shown that x-ray fluorescence calibration curve coefficients are closely related to matrix effects, such as absorption or absorption plus enhancement of the fluorescent radiation. In the classical paper of Rasberry and Heinrich,1 a single coefficient (named Aik) calibration curve was proposed when pure absorption is the predominant effect on the spectral line of interest. Similarly, and for practical purposes, a single coefficient (named Bik) was also considered when absorption and enhancement are present. We propose a new interpretation of calibration curve coefficients based on analytical expressions obtained recently for binary compounds under monochromatic excitation. Six distinct possible cases of calibration curves arise. Examples of binary compounds for each case are given. The data considered have been computed using the fundamental parameters method which allowed us to study a large number of possible mixtures for an arbitrary monochromatic excitation. Finally, through a different approach we discuss how this analysis could be extended to consider polychromatic excitation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300110209
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    New EDXRS exploitation of compton scattering propertiesPresented at the European Conference on EDXRS, Budapest, Hungary, 30 May-3 June 1994. (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 24 (1995), S. 167-171 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The exploitation of the information that can be obtained from the energy analysis of Compton-scattered photons is discussed. It is shown that the use of the high-energy wing part of this energy distribution adds a further tool for EDXRS analysis other than the evaluation of the total fluence area of the Compton (or incoherent) distribution and the total fluence area of the Rayleigh (or coherent) peak. Special attention is paid to those situations for which easy and unambiguous coherent peak evaluation is prevented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300240405
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