Materials Literature
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Despite the significant amount of research on carbon nanotubes, the thermal conductivity of individual single-wall carbon nanotubes has not been well established. To date only a few groups have reported experimental data for these molecules. Existing molecular dynamics simulation results range from several hundred to…
We calculate the nature of magnetic interactions in transition-metal doped ZnO using the local spin density approximation and (LSDA) the $\mathrm{LSDA}+U$ (Coulomb interaction) method of density functional theory. We investigate the following four cases: (i) single-transition-metal-ion types (Cr, Mn, Fe, Co, Ni and Cu…
We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but als…
Superhydrophobic surfaces have considerable technological potential for various applications due to their extreme water-repellent properties. A number of studies have been carried out to produce artificial biomimetic roughness-induced hydrophobic surfaces. It is not clear whether microstructures or nanostructures or t…
A new model for the bending of a Bernoulli–Euler beam is developed using a modified couple stress theory. A variational formulation based on the principle of minimum total potential energy is employed. The new model contains an internal material length scale parameter and can capture the size effect, unlike the classi…
Understanding and controlling the complex environment of solid-state quantum bits is a central challenge in spintronics and quantum information science. Coherent manipulation of an individual electron spin associated with a nitrogen-vacancy center in diamond was used to gain insight into its local environment. We show…
Abstract We present two‐photon excitation luminescence experiments on carbon nanotubes which show the excitonic origin of the optical excitations. The two‐photon allowed exciton state, which has even parity under rotation about the U ‐axis, is roughly 300 meV above the one‐photon active, odd‐parity state. This indicat…
Abstract Because subtle changes in physical structure (chirality) can cause the electronic structure of carbon nanotubes to vary from metallic to semiconducting, the goal of fully controlled nanotube device fabrication has proved elusive. Using a mechanical transfer technique in parallel with optical characterization,…
We numerically analyze the statistics of the heat flow between an aging system and its thermal bath, following a method proposed and tested for a spin-glass model in a recent paper [P. Sibani and H. J. Jensen, Europhys. Lett. 69, 563 (2005)]. The present system, which lacks quenched randomness, consists of Ising spins…
Abstract Raman spectroscopy (RS) was used for the characterization of well‐aligned IrO 2 nanocrystals (NCs) grown on sapphire substrates with different orientations via reactive magnetron sputtering. Three Raman‐active modes, E g , B 2 g and A 1 g , were observed in the range 500–800 cm −1 . The intensity of certain m…
Abstract The temperature‐induced changes in Raman spectra of two BN‐based materials: a hexagonal boron nitride and soot with single‐wall BN nanotubes, have been measured in temperature range 77–600 K in course of heating in the oven/cryostat cell. A nonlinear temperature dependence of the tangential Raman mode positio…
We present a novel method for the accurate numerical determination of the phase behavior of fluid mixtures having large particle-size asymmetries. By incorporating the recently developed geometric cluster algorithm within a restricted Gibbs ensemble, we are able to probe directly the density and concentration fluctuat…
Taking advantage of the surface modification that a selective solvent can induce in a glassy polystyrene–poly(2-vinylpyridine) binary brush layer, a methodology is demonstrated for reversibly tuning the tackiness of a hydrophilic, pressure-sensitive adhesive against that surface. The significant and fully reversible a…
Calculations of the electron-acoustic phonon interaction, and Raman scattering efficiency, in matrix embedded Ge quantum dots (QDs) are presented. The work is focused on the understanding of the inelastic light scattering process excited close to resonance with the confined ${E}_{1}$ transitions. Due to the large join…
Abstract We demonstrate that single‐wall carbon nanotubes (SWCNTs) can be macroscopically aligned by means of templating in a lyotropic nematic liquid crystal (LC), a self‐assembling anisotropic fluid with orientational but no translational order. The CNTs spontaneously adopt the alignment of the host, as we verify by…
Abstract Polar II–VI semiconductors can nucleate in complex shapes ranging from nanowires to nanoribbons, nanosaws and multipods. Here we demonstrate the deterministic and fully reproducible shape‐selective growth of several morphologies of CdSe and ZnTe nanocrystals by a steady‐state vapour transport process. A simpl…
Novel, symmetrical, bent-core mesogens, namely substituted 1,3-phenylenebis{4'-[(ethoxycarbonyl)oxy]-1,1'-biphenyl}-4-carboxylates, are prepared with carbonate groups at both ends of the molecules. The mesophase properties are investigated for different electron-donating and -withdrawing substituents connected to the…
We study the photoreduction of adsorbed copper ions onto Au nanoparticles, on an indium tin oxide (ITO) electrode in an aqueous electrochemical cell, as a function of applied voltage and laser intensity. The photocurrent is a nonlinear function of laser intensity and increases sharply with cathodic voltage in the unde…
Abstract Low temperature single wall carbon nanotubes (SWCNT) synthesis is attractive as it would allow their synthesis to be compatible with microelectronics (below 500 °C) or biomolecular electronics (160 °C). We show that the presence of oxygen, introduced in the form of metal oxides, allows metals not normally ass…
MicroRNAs (miRNAs) constitute a novel, extensive class of small RNAs (approximately 21 nucleotides), and play important gene-regulation roles during growth and development in various organisms. Here we conducted a homology search to identify homologs of previously validated miRNAs from silkworm genome. We identified 2…