Spin dependent tunneling (SDT) wafers were deposited using dc magnetron sputtering. SDT junctions were patterned and connected with one layer of metal lines using photolithography techniques. These junctions have a typical stack structure of Si(100)CrMnPt with the antiferromagnet CrMnPt layers for pinning at the top. High-resolution transmission electron microscopy (HRTEM) reveals that the CoFeB has an amorphous structure and a smooth interface with the Al 2 O 3 tunnel barrier. Although it is difficult to pin the amorphous CoFeB directly from the top, the use of a synthetic antiferromagnet (SAF) pinned layer structure allows sufficient rigidity of the reference CoFeB layer. The tunnel junctions were annealed at 250 C for 1 h and tested for magneto-transport properties with tunnel magnetoresistive (TMR) values as high as 70.4% at room temperature, which is the highest value ever reported for such a sandwich structure. This TMR value translates to a spin polarization of 51% for CoFeB, which is likely to be higher at lower temperatures. These junctions also have a low coercivity (Hc) and a low parallel coupling field (Hcoupl). The combination of a high TMR, a low Hc, and a low Hcoupl is ideal for magnetic field sensor applications.

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Icariin had been reported as a potential agent for osteogenesis, but the dose-effect relationship needed further research to realize the clinical application of icariin. We isolated and purified human bone mesenchymal stem cells (hBMSCs) and stimulated them with different concentrations of icariin. The cytotoxicity of icariin was evaluated by the methylthiazolytetrazolium (MTT) assay method. The proliferation and osteogenic differentiation of such hBMSCs were investigated for different concentrations of icariin. We found that icariin had a dose-dependent effect on the proliferation and osteogenic differentiation of hBMSCs in a suitable concentration range from 10−9 M to 10−6 M, but at concentrations above 10−5 M, the cytotoxicity limited its use. The extremely low cost of icariin and its high abundance make it appealing for bone regeneration.

Purpose: Poly(lactic-co-glycolic acid) (PLGA) is excellent as a scaffolding matrix due to feasibility of processing and tunable biodegradability, yet the virgin scaffolds lack osteoconduction and osteoinduction. In this study, nano-hydroxyapatite (nHA) was coated on the interior surfaces of PLGA scaffolds in order to facilitate in vivo bone defect restoration using biomimetic ceramics while keeping the polyester skeleton of the scaffolds. Methods: PLGA porous scaffolds were prepared and surface modification was carried out by incubation in modified simulated body fluids. The nHA coated PLGA scaffolds were compared to the virgin PLGA scaffolds both in vitro and in vivo. Viability and proliferation rate of bone marrow stromal cells of rabbits were examined. The constructs of scaffolds and autogenous bone marrow stromal cells were implanted into the segmental bone defect in the rabbit model, and the bone regeneration effects were observed. Results: In contrast to the relative smooth pore surface of the virgin PLGA scaffold, a biomimetic hierarchical nanostructure was found on the surface of the interior pores of the nHA coated PLGA scaffolds by scanning electron microscopy. Both the viability and proliferation rate of the cells seeded in nHA coated PLGA scaffolds were higher than those in PLGA scaffolds. For bone defect repairing, the radius defects had, after 12 weeks implantation of nHA coated PLGA scaffolds, completely recuperated with significantly better bone formation than in the group of virgin PLGA scaffolds, as shown by X-ray, Micro-computerized tomography and histological examinations. Conclusion: nHA coating on the interior pore surfaces can significantly improve the bioactivity of PLGA porous scaffolds.

Pinned spin-dependent tunneling devices were fabricated and tested in a mode suited for low-field sensing. The basic structure of the devices was NiFeCo125/Al2O325/CoFe70/Ru9/CoFe70/ FeMn125 (in Å). This structure had a tunneling resistivity of 110 MΩ μm2 and exhibited a 20% magnetoresistance when a field was swept along the easy direction of the soft electrode. High sensitivity, low hysteresis operation was achieved by applying a bias field orthogonal to the easy axis. A sensitivity of 3%/Oe with negligible hysteresis was observed using this mode of operation. A sensor using this type of material was designed to achieve a minimum resolvable field in the picotesla range. The sensor consists of a bridge with four elements, each having 16 tunnel junctions in series. A signal-to-noise ratio of 1:1 at 1 pT (10−8 Oe) is possible assuming achievable values for the tunneling resistivity, device size, bias level, and sensitivity.

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The Lewis acidic sites and reducing power of a photocatalyst are critical for its performance in CO2 activation for cycloadditions. In this study, we designed and synthesized a Ti18Bi4O29Bz26 (Bz = benzoate) cluster molecule that contains Lewis acidic sites on the surface and combines Ti18O22 and Bi4O7 cluster counterparts. DFT calculations combined with synchronous illumination X-ray photoelectron spectroscopy reveal that the Ti18O22 and Bi4O7 components form an S-scheme heterojunction, significantly increasing the reducing power of photogenerated electrons and spatial separation of photogenerated charges. While Ti18Bi4O29Bz26 has some catalytic activity in the cycloaddition reaction between CO2 and epoxides at room temperature, light irradiation significantly increases both the conversion rate and the selectivity of the cyclocarbonate product. Mechanistic studies show that both electrons and holes contribute to the improved performance when exposed to light, and that the increased reducing power overcomes the cycloaddition reaction’s limiting stepCO2 reductive activation. This is not only the report on photocatalytic cycloaddition of CO2 using a Lewis acidic titanium-oxide cluster but also the example of the molecular S-scheme heterojunction to the best of our knowledge.

Icariin, a plant-derived flavonol glycoside, has been proved as an osteoinductive agent for bone regeneration. For this reason, we developed an icariin-loaded chitosan/nano-sized hydroxyapatite (IC-CS/HA) system which controls the release kinetics of icariin to enhance bone repairing. First, by Fourier transform infrared spectroscopy, we found that icariin was stable in the system developed without undergoing any chemical changes. On the other hand, X-ray diffraction, scanning electron microscopy and mechanical test revealed that the introduction of icariin did not remarkably change the phase, morphology, porosity and mechanical strength of the CS/HA composite. Then the hydrolytic degradation and drug release kinetics in vitro were investigated by incubation in phosphate buffered saline solution. The results indicated that the icariin was released in a temporally controlled manner and the release kinetics could be governed by degradation of both chitosan and hydroxyapatite matrix. Finally the in vitro bioactivity assay revealed that the loaded icariin was biologically active as evidenced by stimulation of bone marrow derived stroma cell alkaline phosphatase activity and formation of mineralized nodules. This successful IC-CS/HA system offers a new delivery method of osteoinductive agents and a useful scaffold design for bone regeneration.