Resistive-switching crossbar memory based on Ni-NiO core-shell nanowires.

Resistive-switching memory (RRAM) is an emerging nanoscale device based on the localized metal-insulator transition within a few-nanometer-sized metal oxide region. RRAM is one of the most promising memory technologies for the ultimate downscaling of nonvolatile memory. However, to develop memory arrays with densities approaching 1 Tb cm(-2) , bottom-up schemes based on synthesis and assembly of metal oxide nanowires (NWs) must be demonstrated. A RRAM memory device based on core-shell Ni-NiO NWs is presented, in which the Ni core plays the role of the metallic interconnect, while the NiO shell serves as the active switching layer. A resistance change of at least two orders of magnitude is shown on electrical operation of the device, and the metal-insulator switching is unequivocally demonstrated to take place in the NiO shell at the crossing between two NWs or between a NW and a gold electrode strip. Since the fabrication of the NW crossbar device is not limited by lithography, this approach may provide a basis for high-density, low-cost crossbar memory with long-term storage stability.

The role of moderate static magnetic fields on biomineralization of osteoblasts on sulfonated polystyrene films.

We have investigated the effects of moderate static magnetic fields (SMFs) on murine MC3T3-E1 osteoblasts, and found that they enhance proliferations and promote differentiation. The increase in proliferation rates in response to SMFs was greater in cultures grown on partially sulfonated polytstyrene (SPS, degree of sulfonation: 33%) than in cultures grown on tissue culture plastic. We have previously shown that when the degree of sulfonation exceeded a critical value (12%) [1], spontaneous fibrillogenesis occured which allowed for direct observation of the ECM fibrillar organization under the influence of external fields. We found that the ECM produced in cultures grown on the SPS in the presence of the SMFs assembled into a lattice with larger dimensions than the ECM of the cultures grown in the absence of SMFs. During the early stages of the biomineralization process (day 7), the SMF exposed cultures also templated mineral deposition more rapidly than the control cultures. The rapid response is attributed to orientation of diamagnetic ECM proteins already present in the serum, which could then initiate further cellular signaling. SMFs also influenced late stage osteoblast differentiation as measured by the increased rate of osteocalcin secretion and gene expression beginning 15 days after SFM exposure. This correlated with a large increase in mineral deposition, and in cell modulus. GIXD and EDXS analysis confirmed early deposition of crystalline hydroxyapatite. Previous studies on the effects of moderate SMF had focused on cellular gene and protein expression, but did not consider the organization of the ECM fibers. Our ability to form these fibers has allowed us explore this additional effect and highlight its significance in the initiation of the biomineralization process.

Fe3O4 nanoparticle-integrated graphene sheets for high-performance half and full lithium ion cells.

We synthesized Fe(3)O(4) nanoparticle/reduced graphene oxide (RGO-Fe(3)O(4)) nanocomposites and evaluated their performance as anodes in both half and full coin cells. The nanocomposites were synthesized through a chemical co-precipitation of Fe(2+) and Fe(3+) in the presence of graphene oxides within an alkaline solution and a subsequent high-temperature reduction reaction in argon (Ar) environment. The morphology and microstructures of the fabricated RGO-Fe(3)O(4) nanocomposites were characterized using various techniques. The results indicated that the Fe(3)O(4) nanoparticles had relatively homogeneous dispersions on the RGO sheet surfaces. These as-synthesized RGO-Fe(3)O(4) nanocomposites were used as anodes for both half and full lithium-ion cells. Electrochemical measurement results exhibit a high reversible capacity which is about two and a half times higher than that of graphite-based anodes at a 0.05C rate, and an enhanced reversible capacity of about 200 mAh g(-1) even at a high charge/discharge rate of 10C (9260 mA g(-1)) in half cells. Most important of all, these fabricated novel nanostructures also show exceptional capacity retention with the assembled RGO-Fe(3)O(4)/LiNi(1/3)Mn(1/3)Co(1/3)O(2) full cell at different C rates. This outstanding electrochemical behavior can be attributed to the unique microstructure, morphology, texture, surface properties of the nanocomposites, and combinative effects from the different chemical composition in the nanocomposites.