Investigation of bone mineral distribution in Japanese using dual-energy X-ray absorptiometry

To investigate bone mineral distribution in humans, the authors conducted a cross-sectional survey of, and performed bone-density measurements on, 1,310 healthy Japanese ranging in age 5 to 85 years. Eight hundred fifty-eight of the subjects were female, and 452 were male. Arm, leg, and spine bone mineral content (BMC) and bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA), and the subjects were divided into 5-year age groups. BMD showed increases with skeletal growth until reaching a peak at 15 to 19 years in females, and 25 to 29 for males. For both sexes the fastest growth to maturity in terms of bone mass values was in the late 20s. Females, though, had higher arm, leg, and spine remodeling rates than males. In premenopausal women no changes in arm, leg or spine BMC and BMD were observed. Postmenopausal women showed an overall reduction in bone mass, most noticeably in the spine. After menopause, women had about 10 years of accelerated loss (1.46%/year). Vertebral BMD values were similar for men and women (1.10 +/- 0.20g/cm2 for males vs. 1.09 +/- 0.14g/cm2 for females, p > 0.05). BMC values were significantly higher in males, and males at all times had a higher arm and leg BMD. There were no significant value differences in either sex for left and right leg BMC and BMD; however, from the age of 15, right arm values were significantly higher likely due to right handedness. For both sexes the order of BMC and BMD was leg, spine, and arm.     

Controlling data quality and reproducibility of a high-sensitivity immunoassay using isotachophoresis in a microchip

This report describes a method of controlling the sensitivity and reproducibility of a microchip-based immunoassay by using isotachophoresis to preconcentrate the antigen and antibody prior to binding. Gel electrophoresis separation is coupled to the preconcentration step to separate the immunocomplex products formed. The system employs a quartz-based LabChip that automates the metering, preconcentration, reaction, separation, and detection. The system also uses a handoff mechanism that switches the immunocomplex from the stacking mode to the separation mode. We show that the handoff timing affects the data quality and repeatability of the electropherograms, and we demonstrate an automatic handoff mechanism to precisely control the signal intensity and separation of peaks of interest. In so doing, the automatic handoff mechanism also improves the reproducibility of the assay. When applied to the homogeneous liquid-phase detection of alpha-fetoprotein, a common tumor marker, the system shows a greater than 200-fold stacking of specific analytes of interest.     

Room temperature crystallization by RF plasma

The crystallization of amorphous thin films was achieved by radiofrequency (RF) plasma treatment. Although various amorphous films are crystallized after 2 min or so, the sample temperature is lower than 150 °C without compulsory cooling even when the films are treated for 1 h. This treatment works on amorphous films of various materials, independently of the film preparation method and substrate materials. Sol-gel-derived TiO₂ films were densified and simultaneously crystallized to anatase structure by the plasma treatment and the obtained films indicate almost the same photocatalytic activities as that of thermally crystallized TiO₂ films. Plasma-crystallized sputtered indium tin oxide (ITO) films have a bixbite structure and the resistivity reached to 1.6 × 10^− 4 Ω cm while the crystallization condition was not optimized. Amorphous silicon films with a small mount of crystallites were deposited by sputtering method and were crystallized by the plasma treatment.     

Characterization of sputtered triple layer photoactive coating with a glass-like appearance

Photocatalytic activity of sputtered TiO₂ single layer was investigated. From the results on the optical constants analyses and dark- and photo-conductivity measurements, it is revealed that the photocatalytic activities of TiO₂ films depend on the defect density of the TiO₂ films; the atomic defects act as recombination sites for photo-generated carriers diffusing to the TiO₂ surface. A three-layer system with a layer construction of SnO₂/TiO₂/Si₃N₄/Glass was designed for realizing the glass-like appearance, namely almost the same transmission and reflection spectra in visible wavelength region as those of glass, and its photocatalytic activity was investigated. The experimental results indicate that the interface between TiO₂ and SnO₂ acts as a potential barrier for the carriers photo-generated in the TiO₂ and the photo-generated species pass through the SnO₂ overlayer depending on the SnO₂ film characteristics.     

Measurement of ion acceleration characteristics of a laser-electrostatic hybrid microthruster for space propulsion applications

For space propulsion applications, a fundamental study of a laser-electrostatic hybrid thruster was conducted. A new type of thruster, in which a laser-produced plasma was accelerated by an additional electrostatic field, was tested to optimize the ion acceleration process. A time-of-flight measurement by a Faraday cup showed that the average speed of ions was about 15 km/s when only 0.04 mJ of laser impulse was introduced to a copper target. When an accelerator electrode with a 6-mm-diameter hole was placed in front of the laser target, it was observed that the average speed of ions increased. The maximum velocity was 23 km/s, which corresponded to the case where the accelerator grid was biased to +100 V for the target-to-electrode gap of 2 mm. It was found that the positively biased electrode was more effective than the negatively biased electrode for ion acceleration in the thruster.     

Magnetovolume effects in manganese nitrides with antiperovskite structure

Magnetostructural correlations in antiperovskite manganese nitrides were investigated systematically for stoichiometric and solid solution Mn₃Cu_1?xA_xN (A = Co, Ni, Zn, Ga, Ge, Rh, Pd, Ag, In, Sn or Sb). This class of nitrides is attracting great attention because of their giant negative thermal expansion, which is achieved by doping Ge or Sn into the A site as a relaxant of the sharp volume contraction on heating (spontaneous volume magnetostriction ω_s) because of the magnetovolume effects. The physical background of large ω_s and mechanism of how the volume contraction becomes gradual with temperature are central concerns for the physics and applications of these nitrides. An entire dataset of thermal expansion, crystal structure and magnetization demonstrates that the cubic triangular antiferromagnetic state is crucial for large ω_s. The intimate relationship between ω_s and the magnetic structure is discussed in terms of geometrical frustration related to the Mn₆N octahedron and magnetic stress concept. The results presented herein also show that ω_s depends on the number of d electrons in the A atom, suggesting the important role of the d orbitals of the A atom. Not all the dopants in the A site, but the elements that disturb the cubic triangular antiferromagnetic state, are effective in broadening the volume change. This fact suggests that instability neighboring the phase boundary is related to the broadening. The relation between the gradual volume change and the local structure anomaly is suggested by recent microprobe studies.     

Study of the damage produced in 6H-SiC by He irradiation

Lattice damage and evolution in 6H-SiC under He⁺ ion irradiation have been investigated by the combination of Rutherford backscattering in channeling geometry (RBS/C), Raman spectroscopy, UV–visible spectroscopy and transmission electron microscopy (TEM). 6H-SiC wafers were irradiated with He ions at a fluence of 3 × 10¹⁶ He⁺cm⁻² at 600 K. Post-irradiation, the samples were annealed in vacuum at different temperatures from 873 K to 1473 K for isochronal annealing (30 min). Thermally annealed He irradiated 6H-SiC exhibited an increase in damage or reverse annealing behavior in the damage peak region. The reverse annealing effect was found due to the nucleation and growth of He bubbles. This finding was consistent with the TEM observation. The thermal annealing brought some recovery of lattice defects and therefore the intensities of Raman peaks increased and the absorption coefficient decreased with increasing annealing temperature. The intensity of Raman peak at 789 cm⁻¹ as a function of annealing temperature was fitted in terms of a thermally activated process which yielded activation energy of 0.172 ± 0.003 eV.     

Oxygen equilibrium properties of chromium (III)-iron (II) hybrid hemoglobins

Cr(III)-Fe(II) hybrid hemoglobins, alpha 2(Cr) beta 2(Fe) and alpha 2(Fe) beta 2(Cr), in which hemes in either the alpha- or beta-subunits were substituted with chromium(III) protoporphyrin IX (Cr(III)(PPIX), were prepared and characterized by oxygen equilibrium measurements. Because Cr(III)PPIX binds neither oxygen molecules nor carbon monoxide, the oxygen equilibrium properties of Fe(II) subunits within these hybrids can be analyzed by a two-step oxygen equilibrium scheme. The oxygen equilibrium constants for both hybrids at the second oxygenation step agree with those for human adult hemoglobin at the last oxygenation step (at pH 6.5-8.4 with an without inositol hexaphosphate at 25 degrees C). The similarity between the effects of the Cr(III)PPIX and each subunits' oxygeme on the oxygen equilibrium properties of the counterpart Fe(II) subunits within hemoglobin indicate the utility of Cr(III)PPIX as a model for a permanently oxygenated heme within the hemoglobin molecule. We found that Cr(III)-Fe(II) hybrid hemoglobins have several advantages over cyanomet valency hybrid hemoglobins, which have been frequently used as a model system for partially oxygenated hemoglobins. In contrast to cyanomet heme, Cr(III)PPIX within hemoglobin is not subject to reduction with dithionite or enzymatic reduction systems. Therefore, we could obtain more accurate and reasonable oxygen equilibrium curves of Cr(III)-Fe(II) hybrids in the presence of an enzymatic reduction system, and we could obtain single crystals of deoxy-alpha 2(Cr) beta 2(Fe) when grown in low salt solution in the presence of polyethylene glycol 1000 and 50 mM dithionite.