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  • 1
    Online-Ressource
    Online-Ressource
    American Society of Clinical Oncology (ASCO) ; 2007
    In:  Journal of Clinical Oncology Vol. 25, No. 18_suppl ( 2007-06-20), p. 589-589
    In: Journal of Clinical Oncology, American Society of Clinical Oncology (ASCO), Vol. 25, No. 18_suppl ( 2007-06-20), p. 589-589
    Kurzfassung: 589 Background: Dynamic contrast-enhanced MRI (DCE-MRI) and positron emission tomography (PET) are two imaging modalities previously shown to be predictive of response to neoadjuvant therapy in breast cancer. As the two techniques are functionally very different, the extent of their agreement or discordance for tumor characterization is not well understood. The purpose of this study was therefore to investigate the association between quantitative DCE-MRI enhancement kinetics and 15 O-water PET/ 18 F-FDG PET blood flow and metabolic measures of breast tumors. Methods: We retrospectively evaluated exams for 20 patients with locally advanced breast cancer (LABC) who underwent both 15 O-water/ 18 F-FDG PET and DCE-MRI. PET measures included 15 O-water blood flow, 18 F-FDG transport rate constant from blood to tissue (K 1 ), and FDG metabolic rate. DCE-MRI measures included functional tumor volume, initial peak enhancement (PE), and a delayed signal enhancement ratio (SER) assessing washout. Pearson’s correlations and multivariate stepwise regression analyses were performed; p 〈 0.05 was considered significant. Results: PET 15 O-water blood flow correlated significantly with DCE-MRI peak SER (r=0.8) and tumor volume (r=0.7). PET K 1 measures correlated significantly with DCE-MRI peak PE (r=0.7), peak SER (r=0.6) and tumor volume (r=0.6). By multivariate analysis, SER was the strongest independent MRI correlate of PET blood flow, and PE the strongest MRI correlate for K 1 . No significant correlations were observed between 18 F-FDG PET metabolic rate and the DCE-MRI kinetic parameters. Also, while blood flow and K 1 were strongly correlated (r=0.9, p=0.0001), blood flow and metabolic rate were not (r=0.4, p=0.12). Conclusions: The associations between PET and MRI measures may lead to a better understanding of angiogenesis, vascular permeability, and glucose transport in LABC. A lack of correlation of metabolic rate with blood flow and DCE MRI kinetics suggests that 18 F-FDG PET provides complimentary metabolic information independent of vascular factors. The combination of MRI and PET may be helpful in understanding tumor pharmacodynamics in response to novel therapy. No significant financial relationships to disclose.
    Materialart: Online-Ressource
    ISSN: 0732-183X , 1527-7755
    RVK:
    RVK:
    Sprache: Englisch
    Verlag: American Society of Clinical Oncology (ASCO)
    Publikationsdatum: 2007
    ZDB Id: 2005181-5
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  • 2
    In: The Canadian Mineralogist, Mineralogical Association of Canada, Vol. 50, No. 6 ( 2012-12-01), p. 1823-1838
    Materialart: Online-Ressource
    ISSN: 0008-4476 , 1499-1276
    Sprache: Englisch
    Verlag: Mineralogical Association of Canada
    Publikationsdatum: 2012
    ZDB Id: 217244-6
    ZDB Id: 2046640-7
    SSG: 13
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Online-Ressource
    Online-Ressource
    Rubber Division, ACS ; 2000
    In:  Rubber Chemistry and Technology Vol. 73, No. 5 ( 2000-11-01), p. 912-925
    In: Rubber Chemistry and Technology, Rubber Division, ACS, Vol. 73, No. 5 ( 2000-11-01), p. 912-925
    Kurzfassung: The atomic force microscope (AFM) in the force mode has been used as a nanoindenter for determining the crosslink density and modulus of rubber on a fine scale. The force—distance curves obtained as the sample is moved against the tip can render information about mechanical properties of the sample. The technique for this purpose has been established. Several instrumental and technical difficulties encountered during the development of the technique have been identified and solved. The difficulties include surface roughness, thickness variation of the sample, hysteresis of the scanner, determining the stiffness of the cantilever, determining the geometry of the tip, converting the sensor output to force and determining the penetration depth of the tip. The determination of the effective tip geometry requires use of a calibration material. Force—distance measurements were made on a series of styrene-butadiene rubbers (SBR) with different crosslink densities. The modulus determined by AFM agreed with the modulus measured with dynamic mechanical analysis. The results of force/penetration depth show a linear relationship with crosslink density. The AFM results are shown to correlate with those from NMR. The effects of rubber oxidation in air were examined. The results show that both homogeneous and heterogeneous oxidation can be detected by this method.
    Materialart: Online-Ressource
    ISSN: 1943-4804 , 0035-9475
    Sprache: Englisch
    Verlag: Rubber Division, ACS
    Publikationsdatum: 2000
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  • 4
    Online-Ressource
    Online-Ressource
    Mineralogical Association of Canada ; 1993
    In:  The Canadian Mineralogist Vol. 31, No. 2 ( 1993-06-1), p. 357-369
    In: The Canadian Mineralogist, Mineralogical Association of Canada, Vol. 31, No. 2 ( 1993-06-1), p. 357-369
    Materialart: Online-Ressource
    ISSN: 1499-1276 , 0008-4476
    Sprache: Englisch
    Verlag: Mineralogical Association of Canada
    Publikationsdatum: 1993
    ZDB Id: 217244-6
    ZDB Id: 2046640-7
    SSG: 13
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Online-Ressource
    Online-Ressource
    AIP Publishing ; 1961
    In:  Journal of Applied Physics Vol. 32, No. 9 ( 1961-09-01), p. 1765-1771
    In: Journal of Applied Physics, AIP Publishing, Vol. 32, No. 9 ( 1961-09-01), p. 1765-1771
    Kurzfassung: The modulus and internal friction of polytetrafluoroethylene were measured with longitudinal waves at a frequency of 12 Mc between 248° and 548°K and the fluorine magnetic resonance was studied between 77° and 375°K. The samples covered a wide range of crystallinities and included a specimen which had not been sintered (as polymerized material which had not been heated above the melting temperature). The results resolve discrepancies which existed in the literature and introduce new information about the relaxations and first-order transitions in polytetrafluoroethylene. In the ultrasonic work it is shown that the ``19°C'' and ``30°C'' diffuse first-order crystalline transitions can be studied independently of the crystalline relaxation which occurs at 418°K at 12 Mc. The ``19°C'' transition is not observed but the ``30°C'' transition causes an appreciable decrease in the modulus. X-ray data show that this accompanies a decrease in the rotational order of the lattice. This transition is found to occur over a wider temperature range in unsintered polymer (possibly because of a distribution of the lengths of the molecular segments in the ordered regions). An NMR absorption line from the crystalline regions is resolved and its narrowing above 280°K is attributed to rotational motions associated with the first-order transitions. Comparison with published data shows that the narrowing occurs over a wider temperature range in unsintered polymer. Consideration of a distribution of relaxation times suggests that the narrowing above 190°K of an NMR absorption line from the amorphous regions results from the molecular motion which gives rise to a relaxation observed at 263°K in the ultrasonic measurements. Another amorphous relaxation is observed at 470°K in the ultrasonic measurements and the activation parameters are obtained. Examination of these parameters for the two relaxations suggests that the higher-temperature relaxation should be assigned to the larger molecular segments. For all the relaxations, the parameters follow a relation which obtains for activated processes in inorganic solids.
    Materialart: Online-Ressource
    ISSN: 0021-8979 , 1089-7550
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 1961
    ZDB Id: 220641-9
    ZDB Id: 3112-4
    ZDB Id: 1476463-5
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  • 6
    Online-Ressource
    Online-Ressource
    Rubber Division, ACS ; 2002
    In:  Rubber Chemistry and Technology Vol. 75, No. 1 ( 2002-03-01), p. 19-28
    In: Rubber Chemistry and Technology, Rubber Division, ACS, Vol. 75, No. 1 ( 2002-03-01), p. 19-28
    Kurzfassung: Finite element analysis (FEA) models were developed to study the interaction between atomic force microscope (AFM) tips and filled rubber compounds during nano-indentation. The filled systems were represented by simple models consisting of one or two discrete hard domains in a rubber matrix in order to study how such a hard domain at or near the location of an indentation measurement affected the force-distance response. Parameters studied included domain size and shape, lateral position and depth from the indentation location, effect of sample thickness, and the ability to measure modulus variation across “rubber-particle” interfaces. The analyses showed the degree to which the underlying and adjacent sample regions influenced the force-distance response at a given location. The results identified several limitations of force imaging as a characterization technique for filled systems and suggested a basis for the development of more complex FEA models.
    Materialart: Online-Ressource
    ISSN: 1943-4804 , 0035-9475
    Sprache: Englisch
    Verlag: Rubber Division, ACS
    Publikationsdatum: 2002
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  • 7
    Online-Ressource
    Online-Ressource
    Springer Science and Business Media LLC ; 1993
    In:  MRS Proceedings Vol. 305 ( 1993)
    In: MRS Proceedings, Springer Science and Business Media LLC, Vol. 305 ( 1993)
    Kurzfassung: X-ray photoelectron spectroscopy (XPS), tensiometric wetting, and atomic force microscopy (AFM) were used to investigate the surfaces of PAN based carbon fibers. Percent weighted dipole moments (%WDM) were computed from the deconvoluted core level carbon XPS peaks. Tensiometric wetting separated the polar and dispersive components of the fiber surface energies thus allowing the computation of % polar energies. AFM provided quantitative measurements of the fiber surface rugosities. Scanning electron microscopy (SEM) revealed adhesive interfacial fractures for PMR-15 (polyimide) composites of fibers with low %WDM and % polar energies; cohesive fractures for those with high %WDM and % polar energies. Increasing interlaminar shear strengths correlated with increasing %WDM and % polar energies. The fibers with higher %WDM also had rougher surfaces which probably expose more graphite basal plane dipole sites in addition to providing mechanical interlocking.
    Materialart: Online-Ressource
    ISSN: 0272-9172 , 1946-4274
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 1993
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Online-Ressource
    Online-Ressource
    AIP Publishing ; 1971
    In:  Journal of Applied Physics Vol. 42, No. 13 ( 1971-12-01), p. 5902-5903
    In: Journal of Applied Physics, AIP Publishing, Vol. 42, No. 13 ( 1971-12-01), p. 5902-5903
    Materialart: Online-Ressource
    ISSN: 0021-8979 , 1089-7550
    Sprache: Englisch
    Verlag: AIP Publishing
    Publikationsdatum: 1971
    ZDB Id: 220641-9
    ZDB Id: 3112-4
    ZDB Id: 1476463-5
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  • 9
    Online-Ressource
    Online-Ressource
    Springer Science and Business Media LLC ; 1992
    In:  MRS Proceedings Vol. 279 ( 1992)
    In: MRS Proceedings, Springer Science and Business Media LLC, Vol. 279 ( 1992)
    Kurzfassung: The temperature dependence of amorphization dose for zircon under 1.5 MeV Kr ion irradiation has been investigated using the HVEM-Tandem Facility at Argonne National Laboratory. Three regimes were observed in the amorphization dose-temperature curve. In the first regime (15 to 300 K), the critical amorphization dose increased from 3.06 to 4.5 ions/nm 2 . In the second regime (300 to 473 K), there is little change in the amorphization dose. In the third regime ( 〉 473 K), the amorphization dose increased exponentially to 8.3 ions/nm 2 at 913 K. This temperature dependence of amorphization dose can be described by two processes with different activation energies (0.018 and 0.31 eV respectively) which are attributed to close pair recombination in the cascades at low temperatures and radiation-enhanced epitaxial recrystallization at higher temperatures. The upper temperature limit for amorphization of zircon is estimated to be 1100 K. The ion-mass dependence of the amorphization dose (in dpa) has also been discussed in terms of the energy to recoils based on data obtained from He, Ne, Ar, Kr, Xe irradiations and a 238 Pu-doped sample.
    Materialart: Online-Ressource
    ISSN: 0272-9172 , 1946-4274
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 1992
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  • 10
    Online-Ressource
    Online-Ressource
    Acoustical Society of America (ASA) ; 1960
    In:  The Journal of the Acoustical Society of America Vol. 32, No. 1 ( 1960-01-01), p. 88-99
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 32, No. 1 ( 1960-01-01), p. 88-99
    Kurzfassung: To study acoustic propagation in shallow water without the idealization of conventional theory or the many unknowns in field trials, a model with known realistic parameters is used. A water layer 0.5 to 2 cm deep overlies a 2-in. slab of Hycar rubber with greater density and sound speed. With frequencies from 55 to 600 kc, a small probe in the water allows measurements of phase and group velocities, vertical pressure distributions, mode interferences, and attenuation coefficients. Theoretical predictions about the effects of compressional absorption and shear waves in the bottom, and of sloping bottoms, are supported. An analysis of the additional attenuation caused by rough surfaces is made by spreading small metal spheres on the bottom. This attenuation is proportional to area density of the spheres, the free-field scattering cross section of a sphere, and the acoustic intensity at the depth of the spheres. An additional factor is the fraction g of scattered power actually lost; g correlates empirically with the ratios water depth to sphere radius and sphere radius to acoustic wavelength. A phenomenological theory ties these results together.
    Materialart: Online-Ressource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Sprache: Englisch
    Verlag: Acoustical Society of America (ASA)
    Publikationsdatum: 1960
    ZDB Id: 1461063-2
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