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We present a study on perpendicular magnetic tunnel junctions with W as buffer and capping layers. A tunneling magnetoresistance of 138% and an interfacial magnetic anisotropy of 1.67 erg/cm² were obtained in optimally annealed samples. However, after extended annealing at 420 °C, junctions with W layers showed extremely small resistance due to interdiffusion of W into the MgO barrier. In contrast, in Ta-based junctions, the MgO barrier remained structurally stable despite disappearance of magnetoresistance after extended annealing due to loss of perpendicular magnetic anisotropy. Compared with conventional tunnel junctions with in-plane magnetic anisotropy, the evolution of tunneling conductance suggests that the relatively low magnetoresistance in perpendicular tunnel junctions is related to the lack of highly polarized Δ1 conducting channel developed in the initial stage of annealing. [ABSTRACT FROM AUTHOR]

OBJECTIVE: HIF-1α and Runx2 expression usually increase in chondrocytes (CHs) during osteoarthritis (OA), which involves the changes in glycolytic metabolism. However, the molecular regulation of HIF-1a related to the CHs glycolytic metabolism is still unclear. In this study, we aimed to reveal the mediation of HIF-1a by Runx2 and its effect on the glycolytic metabolism of degenerative CHs. PATIENTS AND METHODS: The expression of HIF-1α, Runx2, and the degenerative markers of CHs in both natural conditions from the OA patients and IL-1β treated in vitro model was analyzed by a Western blot or real-time polymerase chain reaction (RT-PCR). The glycolytic metabolism was determined by the intracellular glucose uptake and adenosine triphosphate (ATP) generation. Transfection of siRNA coding HIF-1α or Runx2 was used to clear the function between HIF-1α and Runx2 in the glycolytic metabolism of degenerated CHs caused by IL-1β. Chromatin immunoprecipitation (ChIP) and Luciferase reporter gene assay were used to verify the Runx2 protein binds to the promoter of HIF-1α and promote its expression. RESULTS: HIF-1α and Runx2 were increased, and glucose uptake and ATP generation were decreased in the degenerative CHs from both OA and IL-1β conditions. Under the stimulation of IL-1β, Runx2 silencing rejected the upregulation of HIF-1α and further aggravated the glycolytic metabolism. When HIF-1α was silenced, the glycolytic metabolism of CHs was also suppressed. Besides, Runx2 protein could regulate HIF-1α expression in the transcriptional level by binding to its promoter. CONCLUSIONS: OHIF-1α plays a role in the self-repair of the glycolytic metabolism of degenerative CHs via the transcriptional regulation of Runx2. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate whether Teriparatide (TP) contributed to the osteogenic differentiation of human marrow mesenchymal cells (hMSCs) through the regulation of miR-375, thereby alleviating osteoporosis (OP). PATIENTS AND METHODS: The expression levels of miR-375 in the serum and hMSCs of patients with OP were determined by quantitative real time-polymerase chain reaction (qRT-PCR). hMSCs were extracted from bone marrows of OP patients and underwent osteogenic differentiation for 1 day, 3 days, 7 days and 10 days, respectively. The mRNA levels of alkaline phosphatase (ALP), osteocalcin (OCN) and runt-related transcription factor 2 (RUNX2) in TP-treated hMSCs transfected with miR-375 mimics or negative control were detected by qRT-PCR. Western blot was conducted to determine the protein expression of RUNX2 in TP-treated hMSCs transfected with miR-375 mimics or negative control. Besides, the osteogenic capacity and mineralization capacity of hMSCs were evaluated by the detection of ALP activity, ALP staining and Alizarin red staining, respectively. Dual-Luciferase reporter gene assay was performed to verify the binding between RUNX2 and miR-375. Subsequently, RUNX2 expression was detected in hMSCs transfected with miR-375 mimics or inhibitor. Rescue experiments were finally performed to determine whether miR-375 was involved in TP-induced osteogenic differentiation by targeting RUNX2. RESULTS: MiR-375 remained at high level in serum of OP patients, while gradually decreased with the prolongation of osteogenic differentiation in isolated hMSCs. TP induction increased the osteogenic and mineralization capacities of hMSCs, which were inhibited after miR-375 overexpression. Through Dual-Luciferase reporter gene assay, we confirmed the binding relationship between miR-375 and RUNX2. Besides, both mRNA and protein levels of RUNX2 were negatively regulated by miR-375. Finally, we verified that co-overexpression of miR-375 and RUNX2 in TP-induced hMSCs significantly enhanced the mineralization capacity compared to overexpression of miR-375 alone. CONCLUSIONS: Teriparatide promoted the osteogenic differentiation of hMSCs through miR-375/RUNX2 axis. [ABSTRACT FROM AUTHOR]

The low-frequency resistance noise in sputtered-deposited magnetic tunnel junctions with MgO barriers has been measured as a function of annealing time at different annealing temperatures. The noise has a 1/f spectrum and it is quantified by a Hooge-like parameter α given in units of μm2. Unannealed devices have the highest noise levels and their α parameters exhibit a pronounced dependence on the voltage bias across the junction. A significant increase in tunneling magnetoresistance (TMR) is observed for short annealing times (on the order of minutes) at high temperatures and it is correlated with a large reduction in noise and in its bias dependence. The maximum TMR and minimum noise levels are reached at a later time that depends on temperature, being shorter at higher annealing temperatures. Devices annealed at 380 and at 430 °C exhibit the same minimum noise levels, α≈2×10-10 μm2. The origin of the resistance noise, its annealing time evolution, and its bias dependence are discussed and they are attributed to vacancy defects in the MgO barriers. [ABSTRACT FROM AUTHOR]

The spark plasma sintering and conventional sintering methods were used to prepare the Sr/Mg–codoped Na0.5Bi0.48Sr0.02Ti0.96Mg0.04O2.95 (NBT-SM) compounds. By the AC impedance spectrum test, the grain and total conductivity of NBT-SM sample sintered by the spark plasma sintering method (NBT-SM-SPS) at 673 K can reach 1.23 mS/cm and 0.478 mS/cm, respectively. The grain conductivity of NBT-SM-SPS sample is around 4.2 times higher than that of NBT-SM sample prepared by the conventional sintering method (NBT-SM-CS). There is higher mobile oxygen vacancy concentration and vacancy mobility capability in the NBT-SM-SPS sample, which is the reason that there is higher oxygen ion conductivity in NBT-SM-SPS sample. The aging behavior investigation was carried out at 573 K. After 48 h aging, there is around 12.3% degradation of the grain conductivity in the NBT-SM-SPS sample. The conductivity degradation should result from the decrease of the oxygen vacancy mobility capability and mobile vacancy concentration. [ABSTRACT FROM AUTHOR]

The three different doped (Na, K and Mg) Na0.5Bi0.5TiO3 compounds were prepared. The grain conductivity of the doped Na0.5Bi0.5TiO3 compounds shows: Na-doping > K-doping > Mg-doping. Using the dielectric relaxation spectroscopy, the relaxation parameters can be obtained: ENa = 0.61 eV, EK = 0.64 eV and EMg = 0.68 eV. In the Na-doped Na0.5Bi0.5TiO3 compound, there exists the lowest activation energy, best oxygen vacancy mobility and the disorder decrease of A-site sub-lattice in the Na0.5Bi0.5TiO3 compound from the Na-doping on the A (Bi3+)-site, which are the possible reasons for the higher grain conductivity in the Na-doped Na0.5Bi0.5TiO3 compound. In the Mg-doped Na0.5Bi0.5TiO3 compound, despite the worst oxygen vacancy mobility, the concentration of mobilizable oxygen vacancies is almost highest, which can be adopted to increase the mobilizable oxygen vacancy concentration of the Na-doped Na0.5Bi0.5TiO3 compound. For the Na0.5Bi0.5TiO3 compound, the further improvement of the electrical performance can be expected for the slight amount Mg-doping on the Ti4+-sites in the Na-doped Na0.5Bi0.5TiO3 compound, which is meaningful to obtain the higher oxide ionic conductivity in the Na0.5Bi0.5TiO3 compounds. [ABSTRACT FROM AUTHOR]