A perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction.

Magnetic tunnel junctions (MTJs) with ferromagnetic electrodes possessing a perpendicular magnetic easy axis are of great interest as they have a potential for realizing next-generation high-density non-volatile memory and logic chips with high thermal stability and low critical current for current-induced magnetization switching. To attain perpendicular anisotropy, a number of material systems have been explored as electrodes, which include rare-earth/transition-metal alloys, L1(0)-ordered (Co, Fe)-Pt alloys and Co/(Pd, Pt) multilayers. However, none of them so far satisfy high thermal stability at reduced dimension, low-current current-induced magnetization switching and high tunnel magnetoresistance ratio all at the same time. Here, we use interfacial perpendicular anisotropy between the ferromagnetic electrodes and the tunnel barrier of the MTJ by employing the material combination of CoFeB-MgO, a system widely adopted to produce a giant tunnel magnetoresistance ratio in MTJs with in-plane anisotropy. This approach requires no material other than those used in conventional in-plane-anisotropy MTJs. The perpendicular MTJs consisting of Ta/CoFeB/MgO/CoFeB/Ta show a high tunnel magnetoresistance ratio, over 120%, high thermal stability at dimension as low as 40 nm diameter and a low switching current of 49 microA.

Hypernuclear fine structure in (16)(Lambda)O and the LambdaN tensor interaction.

We have observed two gamma-ray transitions in (16)(Lambda)O from the 6.6 MeV excited 1(-)(2) state to both ground-state spin-doublet members (1(-)(1),0(-)) by the (K-,pi(-)gamma) reaction. We have obtained the ground-state doublet spacing to be 26.4+/-1.6(stat)+/-0.5(syst) keV and the excitation energy of the 1(-)(2) state to be 6561.7+/-1.1(stat)+/-1.7(syst) keV. The ground-state doublet spacing provides a small but nonzero strength of the tensor interaction between a Lambda and a nucleon. This is the first experimental result on the LambdaN tensor interaction.

Induction of dental pulp stem cell differentiation into odontoblasts by electroporation-mediated gene delivery of growth/differentiation factor 11 (Gdf11).

The long-term goal of dental treatment is to preserve teeth and prolong their function. In dental caries an efficient method is to cap the exposed dental pulp and conserve the pulp tissue with reparative dentin. We examined whether growth/differentiation factor 11 (GDF11), a morphogen could enhance the healing potential of pulp tissue to induce differentiation of pulp stem cells into odontoblasts by electroporation-mediated gene delivery. Recombinant human GDF11 induced the expression of dentin sialoprotein (Dsp), a differentiation marker for odontoblasts, in mouse dental papilla mesenchyme in organ culture. The Gdf11 cDNA plasmid which was transferred into mesenchymal cells derived from mouse dental papilla by electroporation, induced the expression of Dsp. The in vivo transfer of Gdf11 by electroporation stimulated the reparative dentin formation during pulpal wound healing in canine teeth. These results provide the scientific basis and rationale for gene therapy for endodontic treatments in oral medicine and dentistry.

Investigation of early bone formation using resorbable bioactive glass in the rat mandible.

Recent advances in biomaterial technology have made alloplastic bone substitutes more predictable when used with the proper clinical methodology in carefully selected patients. In this animal study, early bone formation using a novel resorbable bioactive glass in the repair of surgically created bony defects in the rat mandible was investigated. Biopsies taken from the implanted sites after 1, 2, 3, 4, 8, and 16 weeks were examined histologically by means of standard cell-staining techniques. In addition, an electron probe microanalyzer was used to determine the presence and distribution of specific elements in samples taken after 16 weeks. Results indicated the early stage of osteoconductive bone growth after approximately 4 weeks. After 16 weeks, electron probe micro-analyzer scans indicated the formation of a calcium-phosphate shell formed in situ and the resorption of silica to background levels.

Infrahyoid spread of deep neck abscess: anatomical consideration.

The aim of this study was to determine the pathway of infrahyoid extension of the oropharyngeal abscess considering the anatomy of the fascial spaces by cross-sectional imaging. CT scans and MR images were retrospectively reviewed in ten patients with known infrahyoid extension of oropharyngeal abscesses (eight with acute tonsillitis, two with acute phlegmonous oropharyngitis). In seven of eight patients tonsillar abscesses descended along the deep cervical fascia converging on the hyoid bone and further accumulated in the anterior cervical space through which extension to the mediastinum took place in four patients. In seven patients the abscesses involved the retropharyngeal space at the infrahyoid neck. In two of these seven patients the abscesses directly extended down into the upper mediastinum through the retropharyngeal space. In one patients of the seven mediastinal spread of an abscess occurred through the posterior cervical space, not through the retropharyngeal space. Cross-sectional imaging is valuable in the evaluation of deep neck abscesses and the pathway of spread. The anterior cervical space in the infrahyoid neck is important for mediastinal extension of pharyngeal abscesses.

Osteoconductive properties and efficacy of resorbable bioactive glass as a bone-grafting material.

The height of the available bone between the alveolar ridge and the sinus is often insufficient for placing endosseous implants in the posterior maxilla. Subantral augmentation after sinus elevation can be performed using bone-grafting materials such as autogenous bone, allografts, and alloplasts. The properties and performance of a recently developed resorbable bioactive glass (BioGran) were investigated with regard to bioactivity and bone-forming capability. The bioactive glass was grafted into the sinus cavities of 25 patients and biopsies were taken after 7 months. The samples were examined by conventional histologic techniques, elemental composition and distribution assayed by an electron probe microanalyzer, and comparative biomechanical data for BioGran and bone tissue gathered. Histologic and biomechanical examination indicated bone formation in all cases, with biomechanical properties of the regenerated bone close to those of bone tissue. The results of this study suggest that BioGran exhibits osteoconductive properties and efficacy as an alloplastic bone-grafting material.

Bone remodeling with resorbable bioactive glass and hydroxyapatite.

Particulate resorbable bioactive glass and resorbable hydroxyapatite did not inhibit the growth of periodontal ligament cells and osteoblasts in cultures. Both cell types promoted the activation of alkaline phosphatase around the surface of bioactive glass particles. When bioactive glass and hydroxyapatite were cultured with peripheral blood lymphocytes/monocytes, the number of nonadherent and adherent cells was the same as observed with a control. Resorbable bioactive glass activated the cells necessary for bone formation better than hydroxyapatite and suppressed the formation of osteoclasts for bone resorption. Resorbable bioactive glass and resorbable hydroxyapatite were found to be harmless to periodontium cells and lymphocytes/monocytes.

Toluene itself as the best urinary marker of toluene exposure.

Head-space gas chromatography (GC) and high-performance liquid chromatography (HPLC) (with fluorescence detectors) methods were developed for toluene (TOL-U) and o-cresol (CR-U) in urine, respectively. In order to identify the most sensitive urinary indicator of occupational exposure to toluene vapor (TOL-A) among TOL-U, CR-U, and hippuric acid in urine (HA-U), the two methods together with an HPLC (with untraviolet detectors) method for determination of HA-U were applied in the analysis of end-of-shift urine samples from 115 solvent-exposed workers (exposed to toluene at 4 ppm as geometric mean). Regression analysis showed that TOL-U correlated with TOL-A with a significantly higher correlation coefficient than did HA-U or CR-U. With regard to the TOL-A concentrations at which the exposed subjects could be separated from the nonexposed by the analyte, TOL-U achieved separation at < 10 ppm TOL-A, whereas both HA-U and CR-U did so only when TOL-A was 30 ppm or even higher. The ratio of the analyte concentrations at 50 ppm TOL-A to those at 0 ppm TOL-A was also highest for TOL-U. Overall, the results suggest that TOL-U is a better marker of exposure to toluene vapor than HA-U or CR-U.