Influence of body composition on bone mass in postmenopausal osteoporotic women

We aimed at evaluating the relationship of lean and fat mass to bone mass in osteoporotic postmenopausal women. We invited 65 women who were being treated at the Sao Paulo Hospital osteoporosis outpatients` clinic to participate. Body composition and bone mineral density (BMD) measurements were performed using Dual-energy X-ray absorptiometry methodology (DXA). The mean age and weight were 69.7 +/- 6.4 years and 56.3 +/- 7.6 kg, respectively. Accordingly to the body mass index (BMI), 52.8% were of normal weight and 47.1% of the patients were overweight. Overweight women had significantly higher bone mass. Similarly, skeletal muscle index (SMI) showed a positive effect on BMD measurements and women with sarcopenia had significantly lower BMD measurements in total femur and femoral neck. In multiple regression analysis only lean mass and age, after adjustments to fat mass and BMI, were able to predict total body bone mineral content (BMC) (R(2) = 28%). Also lean mass adjusted to age and BMI were able to predict femoral neck BMD (R(2) = 14%). On the other hand, none of the components of the body composition (lean mass or fat mass) contributed significantly to explaining total femur BMD and neither body composition measurements were associated with spine BMD. These findings suggest that lean mass has a relevant role in BMC and BMD measurements. In addition, lower BMI and lean mass loss (sarcopenia) is associated to lower BMC and BMD of femoral neck and total femur and possible higher risk of osteoporotic fracture. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Calcium intake and its relationship with adiposity and insulin resistance in post-pubertal adolescents

Background Dietary calcium intake has been described as being a negative contributor to adiposity. In adolescents, this relationship is not well established. The objectives of the present study were to compare the calcium intake of normal-weight and obese adolescents and to evaluate its relationship with adiposity and insulin resistance. Methods A cross-sectional analysis of 96 post-pubertal adolescents; 47 normal weight and 49 obese, mean age 16.6 (SD +/- 1.3) years. Body composition was assessed by dual-energy X-ray absorptiometry. Dietary intake was evaluated using a 3-day dietary record. The biochemical evaluation comprised the measurements of serum lipids, lipoproteins, glucose and insulin. Insulin resistance was calculated using the Homeostasis Model Assessment of Insulin resistance (HOMA-IR). Results The mean calcium intake, adjusted for energy, was lower in obese adolescents, 585.2 (+/- 249.9) mg, than in normal weight adolescents, 692.1 (+/- 199.5) mg. Only 4% of adolescents had an adequate intake of calcium. Calcium intake was inversely associated with body trunk fat, insulin and HOMA-IR in the obese group. The quartile analysis of calcium intake provided evidence that girls in the highest quartile had decreased adiposity and insulin resistance. Conclusions This study showed a negative relationship between calcium intake and body fat and insulin resistance, mainly in obese girls, and demonstrates the importance of an increased dietary calcium intake.

A portable Compton spectrometer for clinical X-ray beams in the energy range 20-150 keV

Primary beam spectra were obtained for an X-ray industrial equipment (40-150 kV), and for a clinical mammography apparatus (25-35 kV) from beams scattered at angles close to 90 degrees, measured with a CdTe Compton spectrometer. Actual scattering angles were determined from the Compton energy shift of characteristic X-rays or spectra end-point energy. Evaluated contribution of coherent scattering amounts to more than 15% of fluence in mammographic beams. This technique can be used in clinical environments. (C) 2010 Elsevier Ltd. All rights reserved.

Energy-dispersive X-ray fluorescence analysis of a pre-Columbian funerary gold mask from the Museum of Sican, Peru

A funerary gold mask from the Museum of Sican, Ferranafe, Peru was analyzed in 30 different areas using a portable equipment using energy-dispersive X-ray fluorescence. It was deduced from the measurements that the main sheet of the mask and the majority of the pendants have a similar composition and are made of tumbaga, which means a poor gold alloy enriched at the surface by depletion gilding, and have a similar `equivalent` gilding thickness of about 5 mu m. The nose, also on tumbaga, has different composition and a thickness of about 8 mu m. The clamps are on gilded or on silvered copper. The red pigment dispersed on the surface of the mask is cinnabar. Copyright (C) 2009 John Wiley & Sons, Ltd.

CONSTRAINING THE NONEXTENSIVE MASS FUNCTION OF HALOS FROM BAO, CMB AND X-RAY DATA

Clusters of galaxies are the most impressive gravitationally-bound systems in the universe, and their abundance (the cluster mass function) is an important statistic to probe the matter density parameter (Omega(m)) and the amplitude of density fluctuations (sigma(8)). The cluster mass function is usually described in terms of the Press-Schecther (PS) formalism where the primordial density fluctuations are assumed to be a Gaussian random field. In previous works we have proposed a non-Gaussian analytical extension of the PS approach with basis on the q-power law distribution (PL) of the nonextensive kinetic theory. In this paper, by applying the PL distribution to fit the observational mass function data from X-ray highest flux-limited sample (HIFLUGCS), we find a strong degeneracy among the cosmic parameters, sigma(8), Omega(m) and the q parameter from the PL distribution. A joint analysis involving recent observations from baryon acoustic oscillation (BAO) peak and Cosmic Microwave Background (CMB) shift parameter is carried out in order to break these degeneracy and better constrain the physically relevant parameters. The present results suggest that the next generation of cluster surveys will be able to probe the quantities of cosmological interest (sigma(8), Omega(m)) and the underlying cluster physics quantified by the q-parameter.

Synchrotron X-ray imaging via ultra-small-angle scattering: principles of quantitative analysis and application in studying bone integration to synthetic grafting materials

Optimized experimental conditions for extracting accurate information at subpixel length scales from analyzer-based X-ray imaging were obtained and applied to investigate bone regeneration by means of synthetic beta-TCP grafting materials in a rat calvaria model. The results showed a 30% growth in the particulate size due to bone ongrowth/ingrowth within the critical size defect over a 1-month healing period.

X-ray and gamma irradiation effects on dipole defects in CaF2 : La, Yb, Al

Impurity-interstitial dipoles in calcium fluoride solutions with Al3+, Yb3+ and La3+ fluorides were studied using the thermally stimulated depolarization current (TSDC) technique. The dipolar complexes are formed by substitutional trivalent ions in Ca2+ sites and interstitial fluorine in nearest neighbor sites. The relaxations observed at 150 K are assigned to dipoles nnR(S)(3+)- F-i(-) (R-S = La or Yb). The purpose of this work is to study the processes of energy storage in the fluorides following X-ray and gamma irradiation. Computer modelling techniques are used to obtain the formation energy of dipole defects. (C) 2007 Elsevier Ltd. All rights reserved.

X-ray transmission through nanostructured and microstructured CuO materials

This study presents a comparison of the X-ray transmission through microsized and nanosized materials. For this purpose CuO nanoparticles, with 13.4 nm average grain size, and CuO microparticles, with a mean particle size of 56 mu m, were incorporated separately to beeswax in a concentration of 5%. Results show that the transmission through the above material plates with microsized and nanosized CuO was almost the same for X-ray beams generated at 60 and 102 kV tube voltages. However, for the radiation beams generated at 26 and 30 kV tube voltages the X-rays are more attenuated by the nanostructured CuO plates by a factor of at least 14%. Results suggest that the difference in the low energy range may be due to the higher number of particles/gram in the plates designed with CuO nanoparticles and due to the grain size effect on the X-ray transmission. (C) 2010 Elsevier Ltd. All rights reserved.

Root uptake and reduction of hexavalent chromium by aquatic macrophytes as assessed by high-resolution X-ray emission

Aquatic macrophytes Salvinia auriculata, Pistia stratiotes and Eichhornia crassipes were chosen to investigate the Cr(VI) reduced by root-based biosorption in a chromium uptake experiment, using a high-resolution XRF technique. These plants were grown in hydroponics medium supplied with non-toxic Cr concentrations during a 27-day metal uptake experiment. The high-resolution Cr-K beta fluorescence spectra for dried root tissues and Cr reference material (100% Cr, Cr(2)O(3), and CrO(3)) were measured using an XRF spectrometer. For all species of aquatic plant treated with Cr(VI), the energy of the Cr-K beta(2,5) line was shifted around 8 eV below the same spectral line identified for the Cr(VI) reference, but it was also near to the line identified for the Cr(III) reference. Moreover, there was a lack of the strong Cr-K beta"" line assigned to the Cr(VI) reference material within the Cr(VI)-treated plant spectra, suggesting the reduction of Cr(VI) for other less toxic oxidation states of Cr. As all Cr-K beta spectra of root tissue species were compared, the peak energies and lineshape patterns of the Cr-K beta(2,5) line are coincident for the same aquatic plant species, when they were treated with Cr(III) and Cr(VI). Based on the experimental evidence, the Cr(VI) reduction process has happened during metal biosorption by these plants. (C) 2009 Elsevier Ltd. All rights reserved.

Metal location and thickness in a multilayered sheet by measuring K alpha/K beta, L alpha/L beta and L alpha/L gamma X-ray ratios

When a multilayered material is analyzed by means of energy-dispersive X-ray fluorescence analysis, then the X-ray ratios of K alpha/K beta, or L alpha/L beta and L alpha/L gamma, for an element in the multilayered material, depend on the composition and thickness of the layer in which the element is situated, and on the composition and thickness of the superimposed layer (or layers). Multilayered samples are common in archaeometry, for example, in the case of pigment layers in paintings, or in the case of gilded or silvered alloys. The latter situation is examined in detail in the present paper, with a specific reference to pre-Columbian alloys from various museums in the north of Peru. (C) 2009 Elsevier B.V. All rights reserved.

Performance of GEANT4 in dosimetry applications: Calculation of X-ray spectra and kerma-to-dose equivalent conversion coefficients

In order to validate the Geant4 toolkit for dosimetry applications, simulations were performed to calculate conversion coefficients h(10, alpha) from air kerma free-in-air to personal dose equivalent Hp(10, a). The simulations consisted of two parts: the production of X-rays with radiation qualities of narrow and wide spectra, and the interaction of radiation with ICRU tissue-equivalent and ISO water slab phantoms. The half-value layers of the X-ray spectra obtained by simulation were compared with experimental results. Mean energy, spectral resolution, half-value layers and conversion coefficients were compared with ISO reference values. The good agreement between results from simulation and reference data shows that the Geant4 is suitable for dosimetry applications which involve photons with energies in the range of ten to a few hundreds of keV. (C) 2008 Elsevier Ltd. All rights reserved.

X-ray spectrometry: a powerful tool for the measurement of complete fusion of weakly bound nuclei

We describe how the method of detection of delayed K x-rays produced by the electron capture decay of the residual nuclei can be a powerful tool in the investigation of the effect of the breakup process on the complete fusion (CF) cross-section of weakly bound nuclei at energies close to the Coulomb barrier. This is presently one of the most interesting subjects under investigation in the field of low-energy nuclear reactions, and the difficult experimental task of separating CF from the incomplete fusion (ICF) of one of the breakup fragments can be achieved by the x-ray spectrometry method. We present results for the fusion of the (9)Be + (144)Sm system. Copyright (c) 2008 John Wiley & Sons, Ltd.

X-ray spectroscopy applied to radiation shielding calculation in mammography

The protective shielding design of a mammography facility requires the knowledge of the scattered radiation by the patient and image receptor components. The shape and intensity of secondary x-ray beams depend on the kVp applied to the x-ray tube, target/filter combination, primary x-ray field size, and scattering angle. Currently, shielding calculations for mammography facilities are performed based on scatter fraction data for Mo/Mo target/filter, even though modern mammography equipment is designed with different anode/filter combinations. In this work we present scatter fraction data evaluated based on the x-ray spectra produced by a Mo/Mo, Mo/Rh and W/Rh target/filter, for 25, 30 and 35 kV tube voltages and scattering angles between 30 and 165 degrees. Three mammography phantoms were irradiated and the scattered radiation was measured with a CdZnTe detector. The primary x-ray spectra were computed with a semiempirical model based on the air kerma and HVL measured with an ionization chamber. The results point out that the scatter fraction values are higher for W/Rh than for Mo/Mo and Mo/Rh, although the primary and scattered air kerma are lower for W/Rh than for Mo/Mo and Mo/Rh target/filter combinations. The scatter fractions computed in this work were applied in a shielding design calculation in order to evaluate shielding requirements for each of these target/filter combinations. Besides, shielding requirements have been evaluated converting the scattered air kerma from mGy/week to mSv/week adopting initially a conversion coefficient from air kerma to effective dose as 1 Sv/Gy and then a mean conversion coefficient specific for the x-ray beam considered. Results show that the thickest barrier should be provided for Mo/Mo target/filter combination. They also point out that the use of the conversion coefficient from air kerma to effective dose as 1 Sv/Gy is conservatively high in the mammography energy range and overestimate the barrier thickness. (c) 2008 American Association of Physicists in Medicine.

Temperature dependence of molecular dynamics and supramolecular aggregation in MEH-PPV films: A solid-state NMR, X-ray and fluorescence spectroscopy study

This article presents an investigation of the temperature induced modification in the microstructure and dynamics of poly[2-methoxy-5-(2`-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) cast films using Wide-Angle X-ray Scattering (WAXS), solid-state Nuclear Magnetic Resonance (NMR), and Fluorescence Spectroscopy (PL). MEH-PPV chain motions were characterized as a function of temperature by NMR. The results indicated that the solvent used to cast the films influences the activation energy of the side-chain motions. This was concluded from the comparison of the activation energy of the toluene cast film, E(a) = (54 +/- 8) kJ/mol, and chloroform cast film, E(a) = (69 +/- 5) kJ/mol, and could be attributed to the higher side-chain packing provided by chloroform, that preferentially solvates the side chain in contrast to toluene that solvates mainly the backbone. Concerning the backbone mobility, it was observed that the torsional motions in the MEH-PPV have average amplitude of similar to 10 degrees at 300 K, which was found to be independent of the solvent used to cast the films. In order to correlate the molecular dynamics processes with the changes in the microstructure of the polymer, in situ WAXS experiments as a function of temperature were performed and revealed that the interchain spacing in the MEH-PPV molecular aggregates increases as a function of temperature, particularly at temperatures where molecular relaxations occur. It was also observed that the WAXS peak associated with the bilayer spacing becomes narrower and its intensity increases whereas the peak associated with the inter-backbone planes reduces its intensity for higher temperatures. This last result Could be interpreted as a decrease in the number of aggregates and the reduction of the interchain species during the MEH-PPV relaxation processes. These WAXS results were correlated with PL spectra modifications observed upon temperature treatments. (C) 2008 Elsevier Ltd. All rights reserved.