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  • 1
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Angeborene Herzfehler ; Fetale Autopsie ; Autopsiemethode ; Pränatale Diagnostik ; Keywords Congenital heart defects ; Fetal autopsy ; Autopsy method ; Prenatal diagnostics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract As a result of the quality of prenatal ultrasound and the expanded experience of prenatal diagnosticians, it is possible to observe congenital heart malformations in increasingly greater detail and at an ever earlier stage of gestation [4]. Since it is on the basis of ultrasound findings that decisions to terminate pregnancies are made, it is of cardinal importance that after termination monitoring and confirmation of the prenatal diagnosis be carried out. This need can only be adequately met by autopsy. There are different methods for carrying out autopsies when there is suspicion of a congenital heart defect: a) the Anderson sequential segmental analysis as modified according to the Berlin method; b) use of a special autoptic method corresponding to the ultrasound findings, based on defining a preferred sectional plane; c) stereo-microscopically; or d) microscopically after embedding and preparation of serial microscopic sections. For the pathologist the consequence is that he has to adapt his autopsy method to the ultrasound findings and the age of the fetus. This enables him to determine an optimal, case-based autopsy strategy for each type of cardiac defect, which is essential for monitoring of the prenatal diagnosis. The present paper discusses the various autoptic methods used in cases of congenital heart malformations and the consequences for the pathologist of the continuing improvements in prenatal diagnostics.
    Notes: Zusammenfassung Aufgrund der Qualität der Untersuchungsergebnisse des pränatalen Ultraschalls und der gestiegenen Erfahrungen in der Pränataldiagnostik, lassen sich angeborene Herzfehler detaillierter und in immer früheren Schwangerschaftswochen darstellen [4]. Da auf der Basis der Ultraschallbefunde Entscheidungen über die Beendigung von Schwangerschaften getroffen werden, besteht nach vollzogener Beendigung der Schwangerschaft, ein starkes Bedürfnis nach Kontrolle und Bestätigung der pränatalen Diagnostik. Dies kann erschöpfend nur durch die Sektion befriedigt werden. Angeborene Herzfehler können mit verschiedenen Methoden seziert werden: a) nach der Anderson-Segmentanalyse, modifiziert nach der Berliner-Methode, b) nach einer speziellen Sektionstechnik entsprechend der Ultraschallbefunde mit Festlegung einer pathologisch-anatomischen Vorzugsschnittebene, c) stereomikroskopisch oder d) mikroskopisch nach Einbettung und Aufarbeitung in Serienschnitten. Die Konsequenz, die sich daraus für den Pathologen ergibt ist, dass er seine Sektionstechnik in Abhängigkeit von Ultraschallbefund und Alter des Fetus anpassen und festlegen muss. Somit kann eine adäquate fallabhängige Autopsiestrategie für jeden speziellen Herzfehler festgelegt werden, die für die Qualitätskontrolle der pränatalen Diagnostik unerlässlich ist. In dem folgenden Beitrag werden verschiedene Sektionstechniken bei angeborenen Herzfehlern analysiert und die sich aus den derzeitigen Ergebnissen der pränatalen Diagnostik ableitenden Konsequenzen für Pathologen, dargestellt.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 16 (1995), S. 63-78 
    ISSN: 1572-9567
    Keywords: R134a ; dilute gas ; refrigerant ; saturation properties ; 1,1,1,2-tetrafluoroethane ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper contains a status report on an international project coordinated by the Subcommittee on Transport Properties of Commission 1.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a. The project has involved the remeasurement of the transport properties of a single sample of R134a in nine laboratories throughout the world in order to test the hypothesis that at least part of the discrepancy could be attributed to the purity of the sample. This paper provides an intercomparison of the new experimental results obtained to data in this project for the viscosity and the thermal conductivity in both gaseous and liquid phases. The agreement between the viscosity data from the laboratories contributing to the project was improved with several techniques, now producing consistent results. This suggests that the purity of the samples of R134a used in previous work was at least partly reponsible for the discrepancies observed. For the thermal conductivity in the liquid phase the results of the measurements are also more consistent than before, although not for all experimental techniques. Not all of the previous measurements suffered from significant sample impurities, so the present measurements on a consistent high-purity sample can he used to detect data sets which are outhers, possibly because of impurities. Identification of laboratories and techniques with systematic differences may require the examination of data for several fluids. The implications for future measurements of the transport properties of other refrigerants are significant.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 12 (1991), S. 999-1012 
    ISSN: 1572-9567
    Keywords: collision cross section ; ethane ; polyatomic gas ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New representations of the viscosity and thermal conductivity of ethane in the limit of zero density are provided. The correlation for the viscosity extends over the temperature range 200 to 1000 K, whereas that for thermal conductivity extends from 225 to 725 K. The behavior of each property is represented by an independent correlation of the appropriate effective collision cross section as a function of temperature. The final results are compared with experimental data as well as with earlier correlations. The accuracy of the viscosity correlation is estimated to be ±0.5 % in the temperature range 300 K⩽T⩽600 K, increasing to ±1.5 and ±2.5% at 200 and 1000 K, respectively. The uncertainty associated with the thermal conductivity correlation is ±2 % in the temperature range 300 K⩽T⩽500 K, increasing to ±3% at either end. The results of this study indicate that there is an urgent need for additional high-precision measurements of thermal conductivity especially for temperatures above 400 K.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 14 (1993), S. 805-818 
    ISSN: 1572-9567
    Keywords: phenol ; second viscosity virial coefficient ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New measurements of the vapor-phase viscosity of phenol were performed from 437 up to 624 K and for densities between 0.006 and 0.023 mol · L−1 in an all-quartz oscillating-disk viscometer with small gaps. Thus, including our own measurements reported earlier, experimental data are available in the temperature range between 376 and 639 K and in the density range from 0.001 up to 0.023 mol · L−1. The data were evaluated with a density series for the viscosity in which only a linear density contribution is included. The values of the second viscosity virial coefficient obtained for phenol as well as for benzene, toluene, and p-xylene were compared with results of the Rainwater-Friend theory and of the modified Enskog theory on the basis of the Lennard-Jones 12-6 potential. The agreement is reasonable, when the potential parameter ratios determined by Bich and Vogel are used. The influence of bound dimers seems to be already taken into account in the three-monomer contribution according to Hoffman and Curtiss.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 16 (1995), S. 1245-1255 
    ISSN: 1572-9567
    Keywords: binary gaseous mixture ; carbon dioxide ; ethane ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experimental viscosity data of ethane, carbon dioxide, and three mole fractions of the binary system carbon dioxide + ethane in the temperature range 293.15〈T⩽633.15 K and in the density range 0.01⩽ρ⩽0.05 mol·L−1 reported earlier were evaluated simultaneously to find out a useful correlation and extrapolation scheme for the viscosity of binary systems in the range of moderate densities. A procedure based on the ideas of the modified Enskog theory has been found to give the best results. Dependent on temperature, the collision diameters related to the equilibrium radial distribution function at contact are fitted to viscosity values of the pure substances and of at least one mixture. The results are compared with experimental data from the literature. A recommendation is given concerning the density range in which the first density contribution to the viscosity coefficient of the system carbon dioxide + ethane is sufficient to be included.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 16 (1995), S. 1335-1351 
    ISSN: 1572-9567
    Keywords: n-alkanes ; propane ; second viscosity virial coefficient ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results of five series of high-precision viscosity measurements on gaseous propane, each differing in density, are reported. The measurements were performed in a quartz oscillating-disk viscometer with small gaps from room temperature up to about 625 K and for densities between 0.01 and 0.05 mol · L−1. The experimental data were evaluated with a first-order expansion, in terms of density, for the viscosity. Reduced values of the second viscosity virial coefficients deduced from the zero-density and initial-density viscosity coefficients for propane and for furthern-alkanes are in close agreement with the theoretical representation of the Rainwater-Friend theory for the potential parameter ratios by Bich and Vogel. A new representation of the viscosity of propane in the limit of zero density is provided using the new experimental data and some data sets from literature. The universal correlation based on the extended principle of corresponding states extends over the temperature range 293 to 625 K with an uncertainty of ±0.5 % and deviates from earlier representations by about 1 % at the upper temperature limit.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 15 (1994), S. 33-66 
    ISSN: 1572-9567
    Keywords: ethane ; n-alkanes ; transport properties ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new representation of the thermal conductivity of ethane is presented. The representative equations are based upon a body of experimental data that have been critically assessed for internal consistency and for agreement with theory in the zero-density limit and in the critical region. The representation extends over the temperature range from 100 K to the critical temperature in the liquid phase and from 225 K to the critical temperature in the vapor phase. In the supercritical region the temperature range extends to 1000 K for pressures up to 1 MPa and to 625 K for pressures up to 70 MPa. The ascribed accuracy of the representation varies according to the thermodynamic state from ±2% for the thermal conductivity of the dilute gas near room temperature to ±5% for the thermal conductivity at high pressures and temperatures. Tables of the thermal conductivity, generated by the relevant equations, at selected temperatures and pressures and along the saturation line are also provided.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 15 (1994), S. 1-31 
    ISSN: 1572-9567
    Keywords: ethane ; n-alkanes ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new representation of the viscosity of ethane is presented. The representative equations are based upon a body of experimental data that have been critically assessed for internal consistency and for agreement with theory in the zero-density limit, vapor phase, and critical region. The representation extends over the temperature range from 100 K to the critical temperature in the liquid phase and from 200 K to the critical temperature in the vapor phase. In the supercritical region, the temperature range extends to 1000 K for pressures up to 2 MPa and to 500 K for pressures up to 60 MPa. The ascribed accuracy of the representation varies according to the thermodynamic state from ±0.5 % for the viscosity of the dilute gas near room temperature to ±3.0% for the viscosity at high pressures and temperatures. Tables of the viscosity, generated by the relevant equations, at selected temperatures and pressures and along the saturation line, are also provided.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-9567
    Keywords: R134a ; dilute gas ; refrigerant ; saturation properties ; 1,1,1,2-tetrafluoroethane ; thermal conductivity ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper reports the results of an international project coordinated by the Subcommittee on Transport Properties of Commission I.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a and culminates the effort which was initially described in 1995. The project has involved the remeasurement of the transport properties of a single sample of R134a in nine laboratories throughout the world in order to test the hypothesis that at least part of the discrepancy could be attributed to the purity of the samples. This paper provides an intercomparison of the new experimental results obtained for the viscosity and thermal conductivity in the vapor, liquid, and supercritical gas phases. The viscosity measurements were made with a variety of techniques including the vibrating wire, oscillating disk, capillary flow, and falling body. Thermal conductivity was measured using transient bare and anodized hot wires, steady-state anodized hot wires, and light scattering. Agreement between a variety of experimental techniques using the standard round-robin sample is necessary to demonstrate that some of the discrepancies in earlier results were due to sample impurities. Identification of disagreement between data using one experimental technique relative to other techniques may suggest modifications that would lead to more accurate measurements on these highly polar refrigerant materials. It is anticipated that the new data which have been measured on this IUPAC round-robin sample will aid in the identification of the reliable data sets in the literature and ultimately allow the refinement of the IUPAC reference-data correlations for the transport properties of R134a.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 19 (1998), S. 1085-1097 
    ISSN: 1572-9567
    Keywords: n-alkanes ; n-butane ; second viscosity virial coefficient ; transport properties ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New relative high-precision measurements of the viscosity η of gaseous n-butane were carried out in an oscillating-disk viscometer. Seven series of measurements were performed between 298 and 627 K. in the density range from 0.01 to 0.05 mol·L−1. Isotherms recalculated from the original experimental data were analyzed with a first-order expansion, in terms of density, for the viscosity. Reduced values of the second viscosity virial coefficient deduced from the zero-density and initial-density viscosity coefficients for n-butane are in good agreement with the representation of the Rainwater–Friend theory. The new experimental data and some data sets from the literature were used to develop a representation for the viscosity of n-butane in the limit of zero density on the basis of the extended principle of corresponding states. It has been shown that an individual correlation is needed to represent the experimental data between 293 and 627 K with an uncertainty of ±0.4%.
    Type of Medium: Electronic Resource
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