Materials Literature
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A planar lens made of gradient index metamaterials can transform cylindrical waves to plane waves, and the beam direction of plane waves is controlled by adjusting the refractive-index distributions of the lens. Based on such properties, we present high-performance beam-scanning antennas experimentally using the gradi…
An interesting property of zigzag graphene nanoribbons is the presence of edge states, extended along its borders but localized in the transverse direction. Here we show that because of this property, electron transport through an externally induced potential well displays two-path-interference oscillations when subje…
A Ge/Si heterojunction light emitting diode with a p+-Ge/i-Ge/N+–Si structure was fabricated using the ultrahigh vacuum chemical vapor deposition technology on N+–Si substrate. The device had a good I-V rectifying behavior. Under forward bias voltage ranging from 1.1 to 2.5 V, electroluminescence around 1565 nm was ob…
Large-scale molecular dynamics simulations were performed to demonstrate the synergistic effects of twin boundaries and free surfaces on dislocation emission in gold nanowires under tensile loading. It is revealed that the addition of nanoscale twins to crystalline nanowires can act to either increase or decrease thei…
Exciton-exciton interaction in dot/rod CdSe/CdS nanocrystals has proved to be very sensitive to the shape of nanocrystals, due to the unique band alignment between CdSe and CdS. Repulsive exciton-exciton interaction is demonstrated, which makes CdSe/CdS dot/rods promising gain media for solution-processable lasers, wi…
The effect of magnetostrictive layer thickness on the magnetoelectric (ME) response and field sensitivity of Pb(Zr,Ti)O3-metglas based sandwiched ME heterostructures has been studied. Such structures hold promise for sensor applications. The increase in metglas thickness results in a significant increase in the ME res…
Titanium tough! Novel proline-derived C1-symmetric titanium(salan) complexes have been used to catalyze the epoxidation of styrene derivatives with aqueous hydrogen peroxide as the oxidant (see scheme). High enantiomeric excesses ranging from 96 to 98 % were obtained.
Complex cobalt oxides known as cobaltites are reviewed, including LnCoO3-based perovskite-structured rare-earth cobaltites (where Ln is lanthanum or a lanthanide), quasi-two-dimensional and quasi-one-dimensional cobaltites of the types LnCo2O5+?, La2CoO4, and Ca3Co2O8, and NaxCoO2 ? yH2O superconducting compounds. Key…
Quantum-mechanical molecular-dynamics simulations are carried out to explore possible precursor states of nano-polycrystalline diamond, a novel ultra-hard material produced directly from graphite. Large-scale simulation with 10^5 atoms is realized by using the ' order-N' simulation code 'ELSES' (http://www.elses.jp).…
Molecular dynamics simulations of frictional sliding in an Atomic Force Microscope (AFM) show a clear dependence of superlubricity between incommensurate surfaces on tip compliance and applied normal force. While the kinetic friction vanishes for rigid tips and low normal force, superlubric behavior breaks down for so…
In contrast to the normal state of conventional metals for which phonon renormalizations drop out of the electronic density of states, we demonstrate that they remain in the case of graphene and their signature is large and measurable. Furthermore, the electron-phonon interaction, which is fixed in conventional metals…
The magnetic properties of Co (=15 nm, =130nm) nanowires are reported. In oxidized wires, we measure large exchange bias fields of the order of 0.1 T below T ~ 100 K. The onset of the exchange bias, between the ferromagnetic core and the anti-ferromagnetic CoO shell, is accompanied by a coercivity drop of 0.2 T which…
Cu 2 O / TiO 2 nanotube heterojunction arrays have been prepared by photoreduction depositing Cu2O nanoparticles on TiO2 nanotube arrays. The heterojunction arrays show uniformly distributed Cu2O nanoparticles, and high crystallinity of anatase and cubic from the TiO2 and Cu2O, respectively. The asymmetry of the curre…
A novel one-step method has been developed to synthesize organically modified layered double hydroxide under ambient condition and without requirement of carbonate-free condition. This method has been found to be effective in the presence of several competitive anions and provides modified products with improved homog…
Electrospinning using natural proteins and synthetic polymers offers an attractive technique for producing fibrous scaffolds with potential for tissue regeneration and repair. Nanofibrous scaffolds of silk fibroin (SF) and poly(L-lactic acid-co-epsilon-caprolactone) (P(LLA-CL)) blends were fabricated using 1,1,1,3,3,3…
Growth of vertically aligned carbon nanotube (CNT) carpets on metallic substrates at low temperatures was achieved by controlled thermal treatment of ethylene and hydrogen at a temperature higher than the substrate temperature. High-resolution transmission electron microscopy showed that nanotubes were crystalline for…
Abstract Nanocrystals of NaYF 4 doped with Yb 3+ and Er 3+ are synthesized in oleylamine using Y 2 (CO 3 ) 3 , Yb 2 (CO 3 ) 3 , Er 2 (CO 3 ) 3 , Na 2 CO 3 , and NH 4 F as precursors. In contrast to other starting materials normally used for such syntheses, these precursors react even at room temperature to form hexago…
In this feature article, gold nanoparticle conjugates loaded with phthalocyanine-based PDT drugs are prepared and tested for delivery efficiency and PDT efficacy on HeLa cancer cells. It could be shown that the delivery and PDT outcome are strongly affected by the bond that links the drug load to the nanoparticle surf…
We study the dipole layer formed at metal-organic interfaces by means of first-principles calculations. Interface dipoles are monitored by calculating the work function change of Au, Ag, Al, Mg and Ca surfaces upon adsorption of a monolayer of PTCDA (3,4,9,10-perylene-tetra-carboxylic-di-anhydride), perylene or benzen…
The pressure-induced structural phase transition from diamond to beta-tin in silicon is an excellent test for theoretical total energy methods. The transition pressure provides a sensitive measure of small relative energy changes between the two phases (one a semiconductor and the other a semimetal). Experimentally, t…