Volume 7 Issue 6, June 2015

A nanosheet structure on a glass plate can transfer naked DNA into difficult-to-transfect cells (for example, stem cells) in limited time after contact (‘transfection window’) without any vector. The transfected cells express the specific proteins a week later. The gene uptake and expression are associated with the cytoskeleton arrangement on the silica nanosheets by activating the cell-membrane integrin receptor.

Applying in situ TEM techniques to GST-based vertical PCRAM cells, we directly observed the DC set switching process of real devices for the first time. The results show that the microstructure of crystalline GST matrix is an important structural parameter determining the local temperature distribution. In the case of highly crystallized GST matrix, the device failure occurred via two-step void formation due to the polarity-dependent electromigration.

We fabricated compact helical antenna operating in the industry-scientific-medical radio band. With a total length of only 5.5 mm, it is about five times smaller compared with the conventional dipole antenna. The transmission and receiving signals between helical antennas and the communication between a helical antenna and a smartphone is reported. Owing to the shape and dimensions, we successfully demonstrate the possibility to address the antenna, when embedded in a tooth, as well as to implant the antenna using standard medical syringes. These demonstrations highlight the potential of helical antennas for medical applications as components of smart system implants.

The transparent C₃N₂H₅ClO₄ ferroelectric film on ITO coated PET substrate can be bent to 3.1 mm radius without affecting its ferroelectric properties. Furthermore, its local piezoelectric response is comparable to that of Pb(Zr_0.2Ti_0.8)O₃ film.

Novel high-κ dielectric materials are identified by automated ab initio calculations on ~1800 oxides. The cubic BeO is found to possess an unprecedented material property of 10 eV for band gap and 275 for dielectric constant. Candidate high-κ oxides are suggested for microelectronic devices such as CPU, DRAM and flash memory.

Nanoporous metals made by dealloying can take the form of macroscopic bodies that exhibit a uniform and highly interconnected network of nanoscale ‘ligaments’. Our study used this material as the reinforcement phase in novel interpenetrating-phase nanocomposites. Tensile tests on our cm-sized composite samples for the first time demonstrate tensile ductility in a nanoporous-metal-based material. Whereas the strength, σ, of pure nanoporous metal scales with the phase faction, ϕ, as σ ∝ ϕ^3/2, the composite has a linear scaling relation σ ∝ ϕ that favors strengthening at small solid fraction. We find this strengthening also in quantitative agreement with the data behind the well-known ‘smaller is stronger’ of metal nanostructures. Thus, our material’s design strategy exploits the high strength of individual metal nano-objects such as nanowires for making a strong and ductile material from which macroscopic things can be formed.

3D Networked NiCo₂S₄ nanosheet array/carbon cloth composites are synthesized by a facile hydrothermal reaction and subsequent sulfurization process, and the rational material composition and structure design lead to their outstanding overall performance as an anode material in lithium-ion batteries.

Silicene is the silicon counterpart of graphene, that is, it consists of a single layer of Si atoms arranged in a hexagonal network. This new two-dimensional material, first predicted by theory, has been recently grown on different metallic surfaces.^{1, 2, 3} An obvious advantage of silicene (over graphene) for nanoelectronic applications is its better compatibility and expected integration with the existing Si nanotechnology platform. A new breakthrough on this material has been recently reported by Tao et al.,⁴ who have successfully fabricated the first silicene-based field effect transistors (FETs) operating at room temperature. Their success relies on the development of a layer transfer process, called ‘silicene-encapsulated delamination with native electrodes’ (SEDNE). This innovative process includes the following key steps: (1) epitaxial growth of silicene on Ag(111) thin films grown on mica substrates; (2) Al₂O₃ in situ encapsulation of the silicene layer, followed by its delamination transfer on a p⁺⁺Si/SiO₂ substrate; and (3) subsequent Ag source/drain contact formation by e-beam lithography. A resulting silicene-based FET, with the p⁺⁺Si substrate used as a back-gate contact, is shown in Figure 1a.

The development of scalable chemistries for the production and processing of graphene is essential if its potential in structures and devices is to be realized. This review is a chemist’s perspective on the methods developed for the production of processable graphene and graphene precursors dispersion, their integration into polymers and fabrication into a variety of structures.

This review highlights the recent developments and contributions of advanced electron microscopy studies to the research of lithium-ion battery materials. Both static, ex situ studies and newly developed in situ AEM techniques are emphasized, and future directions are also proposed.