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  • 1
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Das durch die Bestrahlungssterilisation in Knochentransplantaten induzierte stabile ESR-Signal wurde als biologisches Merkmal für die quantitative Bestimmung des zeitlichen Verlaufs der Knochenresorption benützt. Allotransplantate am KaninchenCalvaria ergaben einen linearen Abfall des Spins/mg im Zeitbereich von 0–15 Wochen.
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  • 2
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Es wird gezeigt, dass die entwickelte ERS-Technik auf Probleme der Mineralisation an Knochengewebe angewandt werden kann. Die Kinetik des Mineralisationsvorganges in Verbindung mit induzierter Knochenbildung wird beschrieben.
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  • 3
    ISSN: 1432-0649
    Keywords: 42.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
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  • 4
    ISSN: 1432-0827
    Keywords: Electron spin resonance ; Crystallinity ; Bone ; Osteons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Several groups containing 10–15 isolated osteons differing in their degree of maturity were analysed. Samples were isolated from undecalcified human and bovine bone sections. The crystallinity coefficient, defined as the ratio of the number of radiation-induced paramagnetic defects in the crystalline lattice of hydroxyapatite to the total ash content, was calculated. The results were compared with measurements performed on fragments of total cortical bone, primary periosteal bone, and inner circumferential lamellar bone. The results show a higher crystallinity of fully calcified osteons as compared with that found at the initial stage of calcification. No differences in the ash content were observed between human osteons, from different stages of calcification evaluated morphologically and by X-ray absorption. These differences were evident when bovine osteons differing in their stage of calcification were compared. Human fully calcified osteons contain 60% ash and their crystallinity coefficient is 52.1. Human osteons at the initial stage of calcification contain 57% ash and their crystallinity coefficient is 40.6. The same parameters for fully calcified bovine osteons and for bovine osteons at the initial stage of calcification are 59% ash, 62.6 crystallinity coefficient and 46% ash, 43.0 crystallinity coefficient, respectively.
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  • 5
    ISSN: 1090-6533
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study is made of a layer having an exponentially broad spectrum of local resistances, one of whose dimensions is smaller than the self-averaging dimension. An investigation is made of the hypothesis of scale invariance and the Gell-Mann-Low function for finite scaling in systems with an exponentially broad spread of resistances. A comparative analysis is made of the scale behavior of these systems and the case of strong localization.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 4 (1993), S. 233-240 
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A carbon (carbon black and/or graphite)/polyesterimide resin system has been used as a material for polymer thick-film resistors. The physical and chemical properties of this system as a function of curing temperature were evaluated by means of resistance measurements during the curing process, thermogravimetric analysis, adhesion measurements and scanning electron microscopy examinations. The temperature range between 250 and 300
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  • 7
    ISSN: 1432-0827
    Keywords: Electron spin resonance ; Resorption ; Irradiation ; Bone ; Graft
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La technique de la résonance aux électrons (ESR) a été utilisée pour étudier la résorption et la substitution progressive de greffons osseux stérilisés par irradiation (à une dose de 3.3 Mrads) chez le lapin et le chien. Le signal stable d'ESR, émis par la perte de substance structurale induite par le rayonnement au niveau du minéral osseux, est utilisé comme marqueur biologique. La concentration de résonance et le nombre total des centres paramagnétiques sont mesurés avant et après greffe. Ue décroissance progressive de la concentration de résonance et du nombre total des centres paramagnétiques est observée après des intervalles de temps variables, faisant suite à l'implantation. En considérant la stabilité inhabituelle et le manque de réactivité chimique des centres paramagnétiques intéressés, il apparait que la décroissance des intensités du signal ESR observé indique une résorption et une substitution progressive. Cette méthode parait intéressante pour des recherches sur les tissues calcifiés.
    Abstract: Zusammenfassung Zur Erforschung der Resorption und der schleichenden Substitution von radiosterilisierten (Dosis: 3,3 Mrad) Knochentransplantaten bei Kaninchen und Hunden wurde die Technik der elektronischen Drehresonanz (ESR) angewendet. Als biologische Markierung diente das stabile ESR-Signal, welches aufgrund des bestrahlungsbedingten Strukturdefektes im Knochenmineral entsteht. Die Drehkonzentration und die Gesamtzahl der paramagnetischen Zentren wurden vor und nach dem Transplantieren gemessen. In verschiedenen Zeitintervallen konnte nach der Implantierung eine allmähliche Abnahme der Drehkonzentration sowie der Gesamtzahl der paramagnetischen Zentren beobachtet werden. Aus der ungewöhnlichen Stabilität und der fehlenden chemischen Reaktionsfähigkeit der beteiligten paramagnetischen Zentren wird geschlossen, daß die beobachtete abnehmende ESR-Signalintensität ei Zeichen für die zunehmende Resorption und Substitution ist. Es scheint, daß mit der besprochenen Technik eine brauchbare Methode zur Erforschung von mineralisiertem Gewebe zur Verfügung steht.
    Notes: Abstract The electron spin resonance (ESR) technique has been applied to the investigation of the resorption and creeping substitution of radiosterilized (3.3 Mrads dose) bone grafts in rabbits and dogs. The stable ESR signal arising from the radiation-induced structural defect in bone mineral was used as a biological label. the spin concentration and the total number of paramagnetic centres were measured before and after grafting. The gradual decrement of spin concentration as well as that of total number of paramagnetic centres were observed at varioust ime intervals after implantation. On the basis of the unusual stability and lack of chemical reaction of the paramagnetic centres involved, it is concluded that the decrease of the observed ESR signal intensities indicates progressive resorption and substitution. it seems that the proposed method can be useful for research o mineralized tissues.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 21 (1996), S. 315-324 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The work focuses on the problem of stability and viscous decay of single vortex rings. A tentative classification scheme is proposed for vortex rings which is based on extensive hot-wire measurements of velocity in the ring core and wake, and flow visualization, viz. laminar, wavy, turbulence-producing, and turbulent. Prediction of vortex ring type is shown to be possible, at least approximately, based on the vortex ring Reynolds number alone. Linear growth rates of ring diameter with time are observed for all types of vortex rings, with different growth rates occurring for laminar and turbulent vortex rings. Data on the viscous decay of vortex rings are used to provide experimental confirmation of the accuracy of Saffman's equation for the velocity of propagation of a vortex ring.
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  • 9
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Optical Fourier analysis was applied for evaluation of the differences between normal and pathologically changed bone tissue. Collagen fibers were used as markers of bone structure. To prove the usefulness of this technique for objective mathematical analysis of these differences the spatial distribution of collagen fiber bundles was evaluated in normal and osteopetrotic bone. The variation in the spatial distribution of collagen fiber bundles in cross sections of femur diaphyses was evaluated quantitatively by optical diffraction in three groups of Fatty Orl-op strain rats, i.e. phenotypically normal animals, osteopetrotic (op/op) mutants and op/op-mutants cured by transplantation of normal syngenic bone marrow. The histological sections of decalcified bone were stained with Sirus-Red and then photographed under polarizing microscope. The Sirus-Red staining was used to enhance the natural birefringency of collagen fibers. Diffractograms obtained from microphotographs of selected bone section areas, i.e. outer and inner circumferential lamellae and haversian bone of normal and cured op/op animals as well as whole cortical bone and woven bone filling the medullary cavities in op/op mutants were analysed separately. Diffractograms contain summarized information on the size and relative position of histological structures. The radial distribution of light energy informs on the size and/or distances between the structures, while angular distribution gives the relative position of these structures in histological sections. The radial and angular distribution of light energy were evaluated for each diffractogram with an electronic detector. The obtained distributions were described by several sets of parameters concerning the position, level and shape of local maxima and minima. Out of these parameters five with the highest discriminant power were chosen for further mathematical analysis. This analysis was based on the calculation of the position of centroids in the multidimensional space described by the linear functions of the chosen parameters for each of the evaluated bone section areas. The centroids (mean values of discriminant scores of each group) represent the centers of gravity of the analysed groups, while the separation of the centroids tested by the F-test illustrates the differences between the respective groups of selected bone section areas. A high level of separation of centroids was found when osteopetrotic bone was compared with normal one, what means that the spatial distribution, size and interstructural distances between the collagen fiber bundles in bone tissue in these two groups of animals differ markedly. A similar situation was observed when osteopetrotic bone was compared with bone tissue obtained from op/op mutants cured by transplantation of normal syngenic bone marrow. On the other hand, the level of separation of centroids was low when bone tissue of cured op/op mutants was compared with the control one, a finding which corresponds to the less pronounced histological differences between these two groups of animals. Computer-aided classification on single microphotographs of selected bone section areas to the known a priori type of bone tissue was performed. The percentage of cases correctly classified to one of the eight groups of selected bone section areas equals 47. The probability of reaching such a result by chance was estimated as less than 10−4. The percentage of cases classified correctly to one of any two statistically different groups was higher than 90. These observations demonstrate that optical diffractometry allows to describe in numerical terms the differences between normal and pathologically changed bone tissue, and therefore might be used for automatic evaluation of histopathological sections and interlaboratory comparative studies.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 30 (1980), S. 179-182 
    ISSN: 1432-0827
    Keywords: Pineal gland ; Crystallinity of mineral ; Pineal sand ; Electron spin resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Crystallinity of mineral in human pineal calcospherulites was determined by electron spin resonance spectrometry after irradiation of the samples with gamma rays in a60Co-source. The radiation-induced stable paramagnetic centers in the crystalline lattice of hydroxyapatite crystals were used as a marker of the crystalline fraction and related to the total mineral content. The crystallinity of pineal sand is higher than that of compact bone. The numerical value of the crystallinity coefficient depends on both the average crystal size of hydroxyapatite and the percentage of the crystalline fraction in the total amount of mineral. Literature data show that the average size of hydroxyapatite crystals in pineal sand are smaller than in bone tissue. It is, therefore, concluded that the higher crystallinity of pineal acervuli is due to the lower percentage of the submicrocrystalline fraction in their mineral.
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