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  • 1
    Electronic Resource
    Electronic Resource
    Tuning of X-ray phase retarder for magnetic EXAFS spectroscopy in helicity modulation mode (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 357-359 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A technique for polarization tuning over a wide energy range has been developed for magnetic EXAFS spectroscopies using a diamond x-ray phase retarder in helicity modulation mode. A quick rocking scan using a piezo stage enabled us to tune the angle of retarder crystal with the precision of ±2 arcsecond within 1 s. Available energy range of circular dichroism measurements has been extended to 6-16 keV by adopting not only undulator gap scan but also the present tuning technique. This technique has been applied to magnetic EXAFS measurements in pure iron at the Fe K-edge. Higher signal-to-noise ratio was obtained in reduced data acquisition time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500017799
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  • 2
    Electronic Resource
    Electronic Resource
    Variation of XMCD spectrum with temperature at R L2,3-edges in R3Fe5O12 (R = Gd and Er) (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 425-427 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The variation of X-ray magnetic circular dichroism (XMCD) with temperature has been measured at R L2,3-edges in R3Fe5O12 (R = Gd and Er). A drastic change in the spectral profile has been observed at low temperatures. The variation of XMCD peak intensity, corrected by the contribution of Fe with temperature, is in agreement with the magnetization of R sublattice. The results suggest that Fe 3d polarization plays an important role to produce the R L2,3-edges XMCD spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500018379
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  • 3
    Electronic Resource
    Electronic Resource
    Generation of an X-ray microbeam for spectromicroscopy at SPring-8 BL39XU (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 328-330 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: A pair of elliptical mirrors (KB mirror) was designed and fabricated to realize an energy tunable x-ray microbeam for spectro-microscopy at SPring-8 BL39XU. As is commonly recognized, the obtainable beam size with the aspherical total reflection mirrors is strongly affected with the slope error of the mirror. Considering that the extremely high brilliance of the undulator radiation from the SPring-8, the small mirror size and the small mirror-to-focus distance were employed to minimize effects of the slope error. Preliminary evaluation of the KB mirror was carried out using 10 keV monochromatized undulator radiation. Alignment of the mirror was assisted by the beam monitor system composed of a scintillator and a CCD, and the beam size less than 5 mm can be easily achieved even when the source was fully used. The beam size obtained with this experiment was 2 × 4 µm2 with the photon flux of 1 × 1010 photons/s. Smaller beam size may be expected with the use of intermediate slits. Characterization of trace elements with the spatial resolution will be carried out by using x-ray fluorescence (XRF) analysis and x-ray absorption fine structure (XAFS) measurements with XRF yield method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500018446
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  • 4
    Electronic Resource
    Electronic Resource
    Mn K-edge XMCD in Mn3MC (M = Zn and Ga) perovskite (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 449-451 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Mn3MC (M = Zn and Ga) perovskite has attracted interest because of a variety of magnetic phase transitions. In this work, we measure temperature and magnetic field dependence of X-ray magnetic circular dichroism (XMCD) at Mn K-edge and discuss effect of second constituent metal on the magnetic states of Mn atoms. The spectrum in Mn3ZnC is characterized by a dispersion-type profile. In Mn3GaC, intensity of the positive peak at the edge is drastically reduced. The difference originates in charge transfer from Zn or Ga to Mn atoms. Temperature and magnetic field variations of the Mn K-edge XMCD spectrum suggest that orbital magnetic moments are closely related to the magnetic phase transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500016885
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  • 5
    Electronic Resource
    Electronic Resource
    Multielectron excitations probed by helicity-modulation XMCD at K-edge in 3d transition metal compounds (2001)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 8 (2001), S. 410-412 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Multielectron excitations (MEE) have been investigated using X-ray magnetic circular dichroism (XMCD) at the K-edge in 3d transition metal compounds. In the range of 50-70 eV above the absorption edge, a dichroic signal that is associated with MEE was identified. This phenomenon is thought to occur due to the super Coster-Kronig transition described as the final states (1s)1(3p)5(3d)n+2 resulting from the 3p --〉 3d transitions. In order to verify this interpretation, XMCD measurements using the helicity-modulation method and calculations of the dichroic spectrum were performed based on this super Coster-Kronig transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049500016769
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  • 6
    Electronic Resource
    Electronic Resource
    Fabrication of Silicon Crystals for a Pin-Post Water-Cooling System at SPring-8 (1998)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 5 (1998), S. 1211-1214 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: An internally cooled crystal with pin-post structure was fabricated using sand-blasting methods and Au-diffusive bonding techniques. Test operation at an undulator beamline of SPring-8 showed that the crystal possessed sufficient cooling capability for radiation from the SPring-8 standard in-vacuum undulator. The remaining problem was how to suppress the strain on the surface induced by bonding and water pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049598000399
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  • 7
    Electronic Resource
    Electronic Resource
    Reduction of bone mineral density in rheumatoid arthritis: A longitudinal study (1997)
    Springer
    Journal of bone and mineral metabolism 15 (1997), S. 30-33 
    Details
    ISSN: 1435-5604
    Keywords: rheumatoid arthritis (RA) ; dual-energy X-ray absorptiometry (DXA) ; osteoporosis ; bone mineral density (BMD)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the last decade, more accurate quantitative methods to assess bone mass in vivo have become available. We have applied these techniques to assess periodic changes of bone loss in rheumatoid arthritis (RA) patients. In this longitudinal study, 132 female RA patients were divided into two groups. The first group of 90 patients were postmenopausal, with a mean age of 60.2 years (PM group), whereas the second group of 42 patients were premenopausal, with a mean age of 42.7 years (M group). The clinical courses of these patients were followed for an average of 3 years. Bone mineral density (BMD) in the lumbar spine (L2–L4), and the femoral neck were measured by dual-energy X-ray absorptiometry (DXA), and second metacarpal bone mineral density was measured by using densitometric techniques periodically. Reduction of BMD in the lumbar spine was significant in both groups (P〈0.01–0.05), but there was no statistical difference between the two groups. The BMD of the femoral neck had a tendency to decrease but this was not significant. The predictors for periodic bone loss in the PM group were aging and nutritional factors, whereas for the M group they were indices of rheumatoid arthritis disease activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439452
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  • 8
    Electronic Resource
    Electronic Resource
    Hip fracture patients without vertebral fracture have a preferential osteopenia in the proximal femur (1998)
    Springer
    Journal of bone and mineral metabolism 16 (1998), S. 259-263 
    Details
    ISSN: 1435-5604
    Keywords: Key words: osteoporosis ; bone mineral density ; hip fracture ; vertebral fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract: In 84 recent hip fracture patients, lateral spinal radiographs were examined for the presence of vertebral fracture. Sixty-three patients (75%) had the complication of vertebral fracture and 21 patients did not. Furthermore, we classified those hip fracture patients according to the presence or absence of vertebral fracture and investigated the characteristics on the extent of osteopenia in axial and peripheral bones. The bone mineral density (BMD) of the lumbar spine, proximal femur, and distal radius were lower in the hip fracture patients with vertebral fracture (HX with VX) than in the hip fracture patients without vertebral fracture (HX without VX), indicating that hip fracture patients can be further divided into subgroups. In making a comparison with age-matched controls, we found that the BMD of all examined sites in the HX with VX were significantly low. Yet, it was only in the BMD of the proximal femur that we could find a significant difference between the HX without VX and age-matched controls. We concluded that hip fracture patients without vertebral fracture have a preferential deficit bone density in the proximal femur and a similar density in the lumbar spine and distal radius when compared with normal women of their age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007740050053
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  • 9
    Electronic Resource
    Electronic Resource
    The effects of nandrolone decanoate on bone mass and metabolism in ovariectomized rats with osteopenia (2000)
    Springer
    Journal of bone and mineral metabolism 18 (2000), S. 258-263 
    Details
    ISSN: 1435-5604
    Keywords: Key words Anabolic steroid ; Biochemical markers ; Bone mineral density ; Osteocalcin ; Pyridinium cross-links
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of nandrolone decanoate (ND) treatment on bone mass and metabolism were studied in ovariectomized (OVX) rats with osteopenia. The 6-month-old rats were divided into Sham (n = 12) and OVX (n = 24). The OVX rats were allowed to lose bone for 6 weeks. At 6 weeks post ovariectomy, the OVX rats were divided into two groups: (1) OVX + Vehicle and (2) OVX + ND. The effects of ND on bone mineral density (BMD), bone mineral content (BMC), and bone metabolism were studied by dual-energy X-ray absorptiometry (DXA) and biochemical markers including urinary pyridinoline (Pyr), deoxypyridinoline (Dpyr), and serum osteocalcin. After 24 weeks of treatment, histomorphometry of the right tibiae and the wet weight of the gastrocnemius and soleus skeletal muscles were also examined. Ovariectomy resulted in a significant increase in biochemical markers and a significant decrease in spine BMD (0.221 ± 0.016 g/cm2 in OVX group vs 0.239 ± 0.008 g/cm2 in Sham group) and BMC (0.550 ± 0.055 g in OVX group vs 0.605 ± 0.042 g in Sham group) at 6 weeks post ovariectomy. Spine BMD (0.227 ± 0.017 g/cm2), femoral BMD (0.263 ± 0.012 g/cm2), and bone density of femur (1.035 ± 0.036 g/cm3) in the OVX + ND group were significantly greater than those in the OVX + Vehicle group (0.204 ± 0.013 g/cm2 for spine BMD, 0.243 ± 0.009 g/cm2 for femoral BMD, 0.938 ± 0.06 g/cm3 for bone density of femur) after 24 weeks of treatment. ND treatment decreased urinary Pyr and Dpyr significantly in OVX rats. Histomorphometric findings indicated that ND-treated rats had greater cancellous bone volume, greater trabecular number, greater trabecular thickness, and less trabecular separation than vehicle-treated OVX rats. OVX rats had greater wet weight of the gastrocnemius and soleus muscles than rats treated with ND. The data suggest that the effect of ND on bone mass is not influenced by the condition of the muscles in OVX rats. Our findings indicate that ND blocks further bone loss by inhibition of bone resorption in OVX rats with osteopenia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010639
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