Abstract Stroke incidence and cognitive decline are related to progression of arteriosclerosis in intracranial DWLs. However, the relationships between DWLs and factors associated with their ...progression, including CKD, have not been fully elucidated using longitudinal MRI. Of 291 individuals (184 males, 107 females; age 66.9 ± 6.1 years) who had voluntarily participated in a hospital-based health check-up and underwent repeated brain MRI scans in 2003 and 2008, 273 were evaluated in this study. The DWL group included those having DWL without progression, and the DWL progression (DWLP) group included those having an increase in grade number according to the Fazekas classification. Unimpaired age-matched subjects with no brain MRI abnormalities constituted Group C. The Mini-Mental State Examination (MMSE) and verbal fluency tasks were used for objective cognitive evaluations according to the MR evaluation schedule in 2008. Associations between DWLs and vascular risk factors were examined. DWLP occurred in 9.2% of subjects. Compared to Group C subjects, DWL and DWLP group subjects had high odds ratios (ORs) for hypertension (HT) (2.23 and 2.92, respectively) and CKD (1.40 and 2.41, respectively). After adjustment for potential confounders, the ORs of CKD for DWLs remained significant (1.13 and 1.43, p < 0.05). DWLs and DWLP were associated with low cognitive scale scores and increased CKD. In conclusion, CKD was associated with DWLs and DWLP as an independent risk factor and a lower level of cognitive function 5 years after CKD was identified. Successful CKD therapy may be expected to prevent DWLP.
Structures and their stability of FeCo ultrathin films grown on MgO(100) were investigated. Atomic force microscopy observations revealed dramatic structural changes from a continuous ultrathin layer ...to coarse islands by low temperature annealing. The results suggest that the thin layered structures of Fe based alloys as grown on MgO(100) are not so stable as expected from the relatively small lattice mismatch between Fe based alloys and MgO. This possibly explains annealing temperature dependence of tunnel magnetoresistance observed in a Fe/MgO/Fe(100) junction.
We have investigated the particle size distributions in Co–Al–O insulating granular films with various Co concentrations (
x
Co) by analyzing the superparamagnetic behavior of magnetization. The ...comparison between the particle size distributions estimated from the magnetization analysis and the TEM observation has made it possible to distinguish between the topological size and the magnetic size of particles. It is suggested that some Co particles couple ferromagnetically to form larger magnetic clusters as
x
Co increases. The magnetoresistance (MR) ratio decreases slightly with
x
Co for
x
Co>36 at%, which is different from the result for metallic granular systems where the MR ratio decreases drastically with the coarsening of magnetic clusters.
The rapid development of spin electronics has emphasized the importance of spin accumulation to transport properties and spin manipulation for quantum computing. The latter requires sufficiently long ...spin-relaxation times, that may be achieved in nanometric particles. Spin accumulation is then expected to take place and strongly affect the transport properties of the particles. The main transport phenomena occurring in nanoparticles will be reviewed, as well as their interplay with spin accumulation. Recent experimental results confirming the theoretical predictions will also be presented. They show clear evidence of the enhancement of the spin-relaxation time in nanometric particles and are promising for the development of spin-electronics devices.
We studied giant magnetoresistance (GMR) and the related properties in Co-Al-O insulating granular films prepared by reactive sputtering. Microstructural observation revealed that the films were ...composed of Co base metallic granules and Al
2O
3 base insulating network-like boundaries. The GMR varied as a function of oxygen content (or Co/Al
2O
3 ratio) and it took a maximum of 8% at room temperature and 17% at 4.2 K for a Co
52Al
20O
28 film, accompanying huge specific electrical resistivities of the order of 10
5–10
6 μΩ cm. It has been considered that the observed GMRs are attributed to a spin-dependent tunneling and that the spin diffusion of electrons during tunneling plays an important role of the composition dependence of GMR. In addition, it has been noted that the temperature dependence of GMR is smaller than the
T
−1 dependence predicted theoretically by Helman et al. but rather close to the theory by Inoue et al.
Localization and expression of connective tissue growth factor/hypertrophic chondrocyte-specific gene product 24 (CTGF/Hcs24) during fracture healing in mouse ribs were investigated. In situ ...hybridization demonstrated that CTGF/Hcs24 mRNA was remarkably expressed, especially in hypertrophic chondrocytes and proliferating chondrocytes, in the regions of regenerating cartilage on days 8 and 14 after fracture. CTGF/Hcs24 mRNA was also expressed in proliferating periosteal cells in the vicinity of the fracture sites on days 2 and 8, and in cells in fibrous tissue around the callus on day 8. Northern blot analysis showed that expression of CTGF/Hcs24 mRNA was 3.9 times higher on day 2 of fracture healing than that on day 0. On day 8, it reached a peak of 8.6 times higher than that on day 0. It then declined to a lower level. Immunostaining showed that CTGF/Hcs24 was localized in hypertrophic chondrocytes and proliferating chondrocytes in the regions of regenerating cartilage, and in active osteoblasts in the regions of intramembranous ossification. Although CTGF/Hcs24 was abundant in the proliferating and differentiating cells (on days 8 and 14), immunostaining decreased as the cells differentiated to form bone (on day 20). CTGF/Hcs24 was also detected in cells in fibrous tissue, vascular endothelial cells in the callus, and periosteal cells around the fracture sites. These results suggest that CTGF/Hcs24 plays some role in fracture healing.
MgO-barrier-based magnetic double tunnel junctions including Au or Cr nanoparticles were prepared by molecular beam epitaxy, and their magnetotransport properties were investigated. A double junction ...sample including Au nanoparticles showed the Coulomb blockade effect and clear magnetoresistive hysteresis loops. The observed bias voltage dependence of the resistance and magnetoresistance (MR) suggested that the MR effects of 1-2% at high bias voltages were caused by spin accumulation in the Au nanoparticles. In the case of Cr nanoparticles, a double junction with relatively low sample resistance was obtained, showing a clear Coulomb threshold.
Magnetic properties of a heavy-ion irradiated single crystalline iron film were investigated. A high quality Fe (001) film with a thickness of 250 nm was fabricated on MgO (001) using the molecular ...beam epitaxy technique. The film was irradiated by 3.2 MeV Ni ions at room temperature using a tandem accelerator. Formation of dislocation loops with nanometer size was observed by TEM observation, and that of sub-nanometer size vacancy clusters was confirmed indirectly from a resistivity increase. However, M-H hysteresis curves and magnetic domain structure did not change significantly. These results indicate the formation of irradiation defects of pure iron in nanometer scale range has little influence on the magnetization process of the iron.
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