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  • NDE  (21)
  • Bone  (16)
  • Springer  (37)
  • American Association of Petroleum Geologists (AAPG)
  • Nature Publishing Group
  • 1980-1984  (37)
  • 1945-1949
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  • Springer  (37)
  • American Association of Petroleum Geologists (AAPG)
  • Nature Publishing Group
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 33 (1981), S. 369-374 
    ISSN: 1432-0827
    Schlagwort(e): Histomorphometry ; Bone ; Reproducibility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary To study bone histomorphometry reproducibility in normal subjects, we performed during orthopedic surgery bone biopsies in 16 post-menopausal women. Each woman had four bone biopsies, two at the usual site in the iliac crest, one on the left and one on the right side, and two other biopsies just behind the usual site, one at each side. We performed measurements of trabecular bone volume, relative osteoid volume, osteoid surfaces, osteoclastic resorption surfaces and calcification front. The average values of the 16 patients were compared, on the one hand, two by two, by a student test, and on the other hand, by a variance analysis. By these two methods the results showed no significant difference between the average values of the 16 patients at each location for any of the histomorphometric parameters studied. However, there was a location variation which was estimated by the intra-individual variation for a given patient. On the other hand, we calculated from the variance analysis the location variance for a group of 10 to 100 patients. In any case all the parameters had a location variation which was high for osteoclastic resorption surfaces and relative osteoid volume when expressed in % of the absolute value of these parameters. The variation of the trabecular bone volume was 0–46. 15% (95% confident limit interval) in a single patient and the hypothetical value of the location variation was 41.6% for a group of 10 patients and 13.0% for a group of 100 patients.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nondestructive evaluation 3 (1982), S. 65-76 
    ISSN: 1573-4862
    Schlagwort(e): crack measurement ; ac field technique ; arbitrary skin depth ; NDE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract A general solution is given to describe the ac field around surface-breaking cracks for arbitrary values of the ratio of skin depth δ to crack depthd. This solution allows accurate interpretation of crack depth from voltage readings taken by a Crack Microgauge instrument in cases where δ andd are comparable. It is shown to agree with asymptotic formulae obtained for the cases where δ/d is very small and very large. Provided that the probe length Δ is large compared with δ, the calculations show that a very good approximation to the crack depth may be obtained, irrespective of the ratio δ/d, by using the thin-skin asymptotic formula $$d = \frac{1}{2}\Delta (V_2 - V_1 )/V_1 $$ whereV 1 andV 2 are probe voltages registered at positions just off and across the crack, respectively. The problem is solved for a crack of infinite aspect ratio which has no opening, but it can be applied with confidence at the centerline of cracks of fairly large aspect ratio.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nondestructive evaluation 4 (1984), S. 3-12 
    ISSN: 1573-4862
    Schlagwort(e): Ultrasonic ; stress measurements ; interfacial stress ; NiTi ; NDE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract In seeking to develop an NDE technique for verifying the serviceability of NiTi couplers for plumbing unions, it was found that the reflection coefficient for a normally incident ultrasonic wave correlated with the stress level at the NiTi-tubing interface. Current theory pertaining to interface reflection is not complete but, even at present status, there is semiquantitative accord between theoretical predictions and normalized data for reflection coefficient versus stress level. These results are at fixed frequency and with comparable surface roughness. Variation of either frequency or surface roughness further affects the reflection coefficient. Current studies are being pursued to define this effect.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 195-202 
    ISSN: 1573-4862
    Schlagwort(e): ac potential difference ; fatigue crack measurement ; slots ; artificial flaws ; parasitic voltages ; NDE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract The development of a successful and accurate instrument for measuring surface-breaking cracks in metals using the ac field technique has raised several interesting theoretical problems. Measurements with the instrument, known as the Crack Microgauge, do not rely on any prior calibration against an artificial flaw such as a saw-cut in a test block, but some users accustomed to such a calibration from other devices have nevertheless wished to use the instrument in that fashion and have in some instances reported erroneous results. In this paper, we develop a simple theory to explain and quantify this phenomenon. We calculate the parasitic voltages induced in the instrument probe due to the finite opening possessed by an artificial flaw, and we use these results to reinterpret the instrument readings. Controlled experimental measurements on artificial flaws of rectangular cross-section made in aluminum and in steel are found to be in good agreement with the theory. It is shown, however, that application of the theory requires additional information about the internal phase shift associated with the instrument. To enhance the accuracy of the theory, the effect of the corners of the artificial flaws was also considered, although it was not very influential in this work.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1573-4862
    Schlagwort(e): stress fields ; microstructure ; J integral ; stress intensity factor ; harness acoustic velocity ; acoustic elasticity ; NDE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract A very precise system for measuring two-dimensional velocity fields in solid samples has been used for nondestructive measurements of both externally applied and residual inhomogeneous stresses in solids,J integrals, stress intensity factors of cracks, and hardness of quenched steel. The longitudinal velocity measurement is based on precise determination of the propagation transit time through the stressed solid specimen using a small diameter, water-coupled acoutic transducer, which is scanned mechanically over the sample. Changes in velocity are then related to changes of stress in the sample by the theory of acoustoelasticity. Similar measurements show a high degree of correlation between longitudinal velocity changes and changes in microstructure in steel samples. Applications to problems of solid mechanics and material science illustrate the utility of this nondestructive measuring technique.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nondestructive evaluation 2 (1981), S. 65-74 
    ISSN: 1573-4862
    Schlagwort(e): NDE ; cast iron ; vibration analysis ; modulus ; strength
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Mathematik
    Notizen: Abstract An outline is given of the existing nondestructive vibration tests for cast irons and their drawbacks in terms of the dimensional accuracy of the components. A proposal is made for a new test based on the change of resonant frequency with vibration amplitude exhibited by cast irons. This proposal is evaluated using material data obtained from dynamic tests of a wide range of cast iron specimens. A test rig is described suitable for testing cylindrical cast bars, and typical results are presented in relation to material strength. There is also a brief description of preliminary testing on cast products.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 32 (1980), S. 189-194 
    ISSN: 1432-0827
    Schlagwort(e): Bone ; Fluoride ; Strength ; Porosity ; Mineralization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Radiographically normal vertebral bone cylinders from 80 male subjects were tested mechanically by static compression and analyzed for porosity, fluoride and ash content. As a group, they had low fluoride content, suggesting little prior intake, consonent with this geographic area. Nevertheless, increasing levels of fluoride were associated with bulkier bone, less porosity, and less mineral per unit of bone, which in direction though not degree suggested changes similar to those of osteomalacia and opposite from those of osteoporosis without apparent threshold. The higher fluoride hard tissue was weaker in static tests than that with less fluoride, but the increased bulk apparently offset this, resulting in bones of unchanged static strength. Hence, water fluoridation should not alter static bone strength. There has, however, been a recent report suggesting that increased mineralization of bone renders it more brittle and thus more likely to fracture on impact. Therefore, the possibility that fluoridation may increase impact resistance by lessening mineralization can be entertained.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    ISSN: 1432-0827
    Schlagwort(e): Bone ; Osteosarcoma ; Matrix vesicles ; Alkaline phosphatase ; Aminopeptidase ; Naphthylamidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Extracellular matrix vesicles from bovine fetal alveolar bone and from a dog osteosarcoma were isolated by differential centrifugation and then fractionated on a discontinuous sucrose density gradient. The fractions were examined by electron microscopy and were analyzed for protein, alkaline phosphatase, aminotripeptidase, and four different β-naphthylamidase activities. The low-density peak of enzyme activities was shown by electron microscopy to be much more homogeneous than the crude matrix vesicle fraction. Two major peaks of protein and enzyme activities were present, one in the high and one in the low density layers. There was good correlation between the activities of alkaline phosphatase and the various peptidases in the fractions from the sucrose density gradient. These results indicate a coexistence of peptidase and alkaline phosphatase in matrix vesicles. On the other hand, there was generally no correlation between the peptidase and alkaline phosphatase activities in vesicular specimens from bovine liver obtained in the same way. Most of the peptidase activity and about half of the alkaline phosphatase activity were solubilized from bone matrix vesicles by detergents. The extracted alkaline phosphatase and alanyl β-naphthylamidase activities were separated from each other on a DEAE-cellulose column.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 33 (1981), S. 89-99 
    ISSN: 1432-0827
    Schlagwort(e): Soluble proteoglycans ; Resistant proteoglycans ; Collagen ; Bone ; Cartilage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Soluble proteoglycans (SPG) were extracted from bovine (BCC) and human (HCC) costal cartilages by the dissociative method using 4 M guanidinium chloride (GuHCl). Proteoglycans which are resistant to extraction (RPG) were obtained following collagenase digestion or hydroxylamine treatment of the cartilage residues. Similarly, SPG were extracted from bovine metaphyseal and cortical bone using EDTA. The RPG were extracted from the bones using hydroxylamine. Density gradient fractionation under dissociative conditions of cartilage SPG and RPG followed by chromatography on Sepharose 2B revealed that A1D1 RPG are smaller than the SPG. SPG reacted with either collagenase or hydroxylamine are also smaller than the parent SPG. A1D1 fractions obtained from BCC-SPG and RPG or from mixtures of SPG and acid-soluble collagen are free of hydroxyproline. Hydroxyproline is not completely separated from HCC-RPG. Density gradient fractionation of bone proteoglycans and Sepharose chromatography of the A1 and A1D1 fractions showed that those obtained from metaphysis are larger than those from cortical bone. This was attributed to the presence of calcified cartilage in metaphyseal bone. The A1D1 fractions of the metaphyseal proteoglycans seemed to undergo self-association since this fraction is larger than the A1 fraction from which it is derived. Cortical bone proteoglycans do not behave similarly. Density gradient purification under dissociative conditions failed to separate hydroxyproline from the proteoglycans obtained from bone. It is hypothesized that in bone proteoglycans and collagen might be linked.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 30 (1980), S. 15-20 
    ISSN: 1432-0827
    Schlagwort(e): Bone ; Osteoclasts ; Macrophage ; Resorption ; Plutonium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Female rats were used to study the kinetics of plutonium transfer from the bone surfaces of the mandibular condyle to osteoclasts and macrophages. This study was made using autoradiographs prepared from plastic sections of the mineralized bones of animals which had been injected with241 Pu citrate. Measurements of the concentration of plutonium in the osteoclasts and macrophages at different times after the injection of plutonium showed that plutonium was concentrated by osteoclasts from bone surfaces and was retained with a half-time of ∼ 70 h. Subsequently, plutonium appeared to be transferred to macrophages. The results showed that plutonium was unlikely to be accumulated by macrophages as a result of their participation in bone resorption.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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