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  • 1
    Electronic Resource
    Electronic Resource
    The Oxidations of Hydrocarbons at High Pressure. (1921)
    s.l. : American Chemical Society
    Chemical reviews 21 (1921), S. 299-317 
    Details
    ISSN: 1520-6890
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cr60069a008
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  • 2
    Electronic Resource
    Electronic Resource
    Apparatus for Accurate Analysis of Small Quantities of Gas (1925)
    s.l. : American Chemical Society
    Industrial & engineering chemistry 17 (1925), S. 621-621 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie50186a028
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  • 3
    Electronic Resource
    Electronic Resource
    Experimenting at High Pressures (1953)
    [s.l.] : Nature Publishing Group
    Nature 171 (1953), S. 668-669 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] INVESTIGATIONS into the influence of pressure on the properties of matter are at present confined to limits prescribed by the mechanical properties of materials of construction. In plant designed to develop and sustain high internal pressures, two separate stress-systems have to be incorporated. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/171668a0
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  • 4
    Electronic Resource
    Electronic Resource
    Steam Tables and Steam Power (1945)
    [s.l.] : Nature Publishing Group
    Nature 156 (1945), S. 755-755 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IN a recent review of “The 1939 Callendar Steam Tables”1, Dr. H. Heywood concludes by saying that “these tables … should meet the requirements for many years of engineers concerned with the design and testing of steam power plant or of heating and ventilating systems”. In the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/156755c0
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrasound Velocity of Trabecular Cubes Reflects Mainly Bone Density and Elasticity (1999)
    Springer
    Calcified tissue international 64 (1999), S. 18-23 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Ultrasound—Velocity—Elasticity—Structure—Density.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Studies have indicated that quantitative ultrasound (QUS) variables may be influenced by the mechanical properties of bone which in turn are determined by bone's material and structural properties. However, from these studies it is unclear what role density, elasticity, and structure play in determining velocity. Eighteen defatted, 12-mm cubic trabecular bone specimens were cut from cadaveric specimens. Amplitude-dependent speed of sound (SOS) using a single point QUS system was assessed in three orthogonal axes. Magnetic resonance images were obtained, from which measures of apparent trabeuclar structure were derived. The specimens were nondestructively tested in compression along three orthogonal axes defined by the sides of the cubes. The elastic modulus (in the three directions) and the strength (in one direction) were determined. Trabecular BMD was measured by quantitative computed tomography. SOS varied significantly with direction of measurement, with the highest value in the axial direction (axial:1715 m/s, sagittal: 1662 m/second, and coronal: 1676 m/s). SOS of each of the three axes was generally associated with the various mechanical (r = 0.30–0.87), density (r = 0.81–0.93), and bone structural variables (0.3–0.8). However, after adjusting the SOS correlations by density, only the correlation with elasticity remained significant in the coronal direction. BMD alone explained 88–93% of variance in SOS whereas in the multivariate model, BMD plus elasticity and/or anisotropic variables explained 96–98% of the variance in SOS. Variability of SOS is explained mostly by density and to a small extent by elasticity or anisotropy. Since only 2–6% of the variance of the QUS measurement is not explained by density and elasticity, one could conclude that the remaining variance reflects other properties of bone or perhaps simply measurement error. Evidence that these other properties may be structure related is only found in the anisotropy of QUS parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900572
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  • 6
    Electronic Resource
    Electronic Resource
    Power Spectral Analysis of Vertebral Trabecular Bone Structure from Radiographs: Orientation Dependence and Correlation with Bone Mineral Density and Mechanical Properties (1998)
    Springer
    Calcified tissue international 63 (1998), S. 482-489 
    Details
    ISSN: 1432-0827
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Trabecular bone structure and bone density contribute to the strength of bone and are potentially important in the study of osteoporosis. Fourier transforms of the textural patterns in radiographs of trabecular bone have previously been used for the measurement of trabecular bone structure in subjects, however, the relationship between these measures and biomechanical properties of bone have not previously been established. In this study radiographs were acquired of 28 cubic specimens of spinal trabecular bone along each of the three anatomic axes: cranio-caudal or superior-inferior (SI), medial-lateral (ML), and anterior-posterior (AP). The radiographs were digitized, background corrected, and uniformly aligned. The Fast Fourier transform (FFT) was performed on a region comprised solely of trabecular bone for each image. The zero (DC), first (FMO), and second moments (SMO) of the Fourier power spectrum and the fractal dimension (FD) as determined from the Fourier power spectrum were correlated with stereology measures, with bone mineral density (BMD) as well as with measured biomechanical properties [Young's elastic modulus (YM) and ultimate strength] of the cubes. The results show that the power spectra-based measures, when compared with structural parameters determined using 3D stereology, show good correlations with bone volume fraction, trabecular spacing, thickness, and number. These power spectral measures showed fair to good correlations with BMD and the biomechanical properties. Moreover, the correlations between the power spectral measures of trabecular structure and the BMD, YM, and stereology measures of structure depend on the orientation of the radiographic image. Specifically, these were significant differences in the measured biomechanical properties and the power spectral measures of the trabecular structure between the SI and ML and the SI and AP directions. In addition, depending on the spatial frequency range for analysis, the fractal dimension showed opposite trends with changes in BMD and biomechanical properties. Multivariate regression models showed the correlation coefficients increasing with the inclusion of some of the power spectral measures, suggesting that FFT-based texture analysis may play a potential role in studies of osteoporosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900562
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  • 7
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of trabecular bone structure in the distal radius: Relationship with X-ray tomographic microscopy and biomechanics (1996)
    Springer
    Osteoporosis international 6 (1996), S. 376-385 
    Details
    ISSN: 1433-2965
    Keywords: Architecture ; Magnetic resonance ; Microscopy ; Osteoporosis ; Trabecular bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The contribution of trabecular bone structure to bone strength is of considerable interest in the study of osteoporosis and other disorders characterized by changes in the skeletal system. Magnetic resonance (MR) imaging of trabecular bone has emerged as a promising technique for assessing trabecular bone structure. In this in vitro study we compare the measures of trabecular structure obtained using MR imaging and higher-resolution X-ray tomographic microscopy (XTM) imaging of cubes from human distal radii. The XTM image resolution is similar to that obtained from histomorphometric sections (18 µm isotropic), while the MR images are obtained at a resolution comparable to that achievable in vivo (156×156×300 µm). Standard histomorphometric measures, such as trabecular bone area fraction (synonymous with BV/TV), trabecular width, trabecular spacing and trabecular number, texture-related measures and three-dimensional connectivity (first Betti number/volume) of the trabecular network have been derived from these images. The variation in these parameters as a function of resolution, and the relationship between the structural parameters, bone mineral density and the elastic modulus are also examined. In MR images, because the resolution is comparable to the trabecular dimensions, partial volume effects occur, which complicate the segmentation of the image into bone and marrow phases. Using a standardized thresholding criterion for all images we find that there is an overestimation of trabecular bone area fraction (∼3 times), trabecular width (∼3 times), fractal dimension (∼1.4 times) and first Betti number/ volume (∼10 times), and an underestimation of trabecular spacing (∼1.6 times) in the MR images compared with the 18-µm XTM images. However, even for a factor of 9 difference in spatial resolution, the differences in the morphological trabecular structure measures ranged from a factor of 1.4 to 3.0. We have found that trabecular width, area fraction, number, fractal dimension and Betti number/volume measured from the XTM and MR images increases, while trabecular spacing decreases, as the bone mineral density and elastic modulus increase. A preliminary bivariate analysis showed that in addition to bone mineral density alone, the Betti number, trabecular number and spacing contributed to the prediction of the elastic modulus. This preliminary study indicates that measures of trabecular bone structure using MR imaging may play a role in the study of osteoporosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623011
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  • 8
    Electronic Resource
    Electronic Resource
    Trabecular Bone Architecture in the Distal Radius Using Magnetic Resonance Imaging in Subjects with Fractures of the Proximal Femur (1999)
    Springer
    Osteoporosis international 10 (1999), S. 231-239 
    Details
    ISSN: 1433-2965
    Keywords: Key words:Calcaneus – High-resolution MRI – Osteoporosis – Radius – Structural analysis – Trabecular bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: To determine whether magnetic resonance (MR)-derived measures of trabecular bone architecture in the distal radius are predictive for prevalent hip fractures, 20 subjects with hip fractures and 19 age-matched postmenopausal controls were studied. Bone mineral density (BMD) measures at the hip (dual-energy X-ray absorptiometry, DXA) and the distal radius (peripheral quantitative computed tomography, pQCT) were also obtained. We compared the MR-based structural measures derived in the radius with those in the calcaneus of the same patients. In the radius, images were acquired at an in-plane resolution of 156 μm and a slice thickness of 0.5 mm. Stereologic measures such as the apparent trabecular thickness (app. Tb.Th), fractional trabecular bone volume (app. BV/TV), trabecular spacing (app. Tb.Sp) and trabecular number (app. Tb.N) were derived from the images. Measures of app. Tb.Sp and app. Tb.N in the distal radius showed significant (p〈0.05) differences between the two groups, as did hip BMD measures. However, radial trabecular BMD measures showed only a marginal difference (p= 0.05). Receiver operating curve analysis was used to determine the diagnostic efficacy of BMD, structural measures and a combination of the two. The area under the curve (AUC) for total hip BMD was 0.73, and for radial trabecular BMD was 0.69. AUC for most of the measures of trabecular bone structure at the distal radius was lower than for hip BMD measures; however, AUC for app. Tb.N at the radius was 0.69, comparable to trabecular BMD using pQCT. The AUC for combined BMD (hip) and structure measures was higher (0.87) when radius and calcaneus structure was included. Measures of trabecular architecture derived from MR images combined with BMD measures improve the discrimination between subjects with hip fractures and normal age-matched controls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001980050221
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  • 9
    Electronic Resource
    Electronic Resource
    Fractal Analysis of Proximal Femur Radiographs: Correlation with Biomechanical Properties and Bone Mineral Density (1999)
    Springer
    Osteoporosis international 9 (1999), S. 516-524 
    Details
    ISSN: 1433-2965
    Keywords: Key words:Bone mineral density – Femur – Fractal dimension – Osteoporosis – Radiography – Singh index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: Conventional radiography and fractal analysis were used to quantify trabecular texture patterns in human femur specimens and these measures were used in conjunction with bone mineral density (BMD) to predict bone strength. Radiographs were obtained from 51 human femur specimens (25 male, 26 female). The radiographs were analyzed using three different fractal geometry based techniques, namely semi-variance, surface area and Fourier analysis. Maximum compressive strength (MCS) and shear stress (MSS) were determined with a material testing machine; BMD was measured using quantitative computed tomography (QCT). MCS and MSS both correlated significantly with BMD (MCS: R= 0.49–0.54; MSS: R= 0.69–0.72). Fractal dimension also correlated significantly with both biomechanical properties (MCS: R= 0.49–0.56; MSS: R= 0.47–0.54). Using multivariate regression analysis, the fractal dimension in addition to BMD improved correlations versus biomechanical properties. Both BMD and fractal dimension showed statistically significant correlation with bone strength. The fractal dimension provided additional information beyond BMD in correlating with biomechanical properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001980050179
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanism of the Bursting of Bubbles (1954)
    [s.l.] : Nature Publishing Group
    Nature 173 (1954), S. 261-261 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We have observed, however, that two separate mechanisms are involved in the bursting of a bubble- one producing a cloud of droplets of diameter about 60 microns, and the other a few comparatively large drops of diameter about 1 mm. The various stages of the collapse are illustrated in Fig. 1, a-/. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/173261a0
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