Materials Literature
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We report on the growth mechanism, structure, and luminescence properties of ZnO hexagonal columns grown from Zn vapor and air plasma. Single-crystal ZnO columns grow in the [0001] direction through repeated nucleation and growth of epitaxial hexagonal pyramids on the c-planes. Homoepitaxial nucleation of three-dimens…
On the basis of our concept that the introduction of heteroatoms and shape-persistency into the pi-macrocycles should bring forth striking functions or properties, heteroarenecyclynes (such as oxaarenecyclynes and thiaarenecyclynes) with semi-shape-persistent structure, and arene-azaarenecyclynes with shape-persistent…
A range of pseudo-random silver structures, where there is a choice of clustered spheres or pillars or tori, have been fabricated on silicon using the method of island lithography combined with electroless plating. Pyridine has been adsorbed on these structures and the surface-enhanced Raman scattering spectrum (SERS)…
Although the miscibility of silicates, including clay minerals, with organics and polymers has been known since the early 1950s, an industrial report of a nylon-6/montmorillonite (mmt) material from Toyota1 has recently revitalized the field. Those materials were synthesized by polymerization of the monomer in the pre…
We report a design for carbon nanotube field-effect transistors which tests the nanotube depletion length. In this design, the metal contacts and adjacent nanotubes were coated with impermeable silicon oxide, while the central region of nanotubes was exposed. We tested the devices by measuring sensitivity to NH3 and p…
The present study was focused on permanent grafting of poly(ethylene glycol) (PEG) layers (brushes) from the melt to adsorbed reactive macromolecules. A poly(glycidyl methacrylate) (PGMA) was used to form the reactive primary adsorbed layer. It was found that a thin (1.5 nm) PGMA layer had a high grafting efficiency,…
We present a simple but powerful method to determine the thicknesses of the accumulation and depletion layers and the distribution curve of injected carriers in organic field effect transistors. The conductivity of organic semiconductors in thin film transistors was measured in-situ and continuously with a bottom cont…
Manipulating fluids at the nanoscale within networks of channels or chemical lanes is a crucial challenge in developing small scale devices to be used in microreactors or chemical sensors. In this context, ultra-thin (i.e., monolayer) films, experimentally observed in spreading of nano-droplets or upon extraction from…
We consider generalizations of the Kardar--Parisi--Zhang equation that accomodate spatial anisotropies and the coupled evolution of several fields, and focus on their symmetries and non-perturbative properties. In particular, we derive generalized fluctuation--dissipation conditions on the form of the (non-linear) equ…
We systematically investigate, using ab initio density-functional theory calculations, the properties of interstitial and substitutional Mn in both Si and Ge, as well as in the Si(1-x)Gex alloy. We show that volume effects are not the main reason Mn prefers to be a subsitutional impurity in pure Ge, and chemical effec…
By means of linear theory of elastoplasticity, solutions are given for screw and edge dislocations situated in an isotropic solid. The force stresses, strain fields, displacements, distortions, dislocation densities and moment stresses are calculated. The force stresses, strain fields, displacements and distortions ar…
Dislocation waves in magnetic crystals in the vicinity of orientation phase transition (OPT) temperatures are considered in a frame of the field theory of the defects. The singularities of the dislocation flows, elastic deformations and magnetization occur if the magnetic subsystem is inhomogeneous and the dispersion…
We fabricate and electrically characterize electrospun nanofibers of doped polyaniline/polyethylene oxide (PAn/PEO) blend with sub-30 nm diameter. Fiber diameters near 5 nm are obtained for optimized process parameters. Scanning conductance microscopy (SCM) shows that fibers with diameter below 15 nm are electrically…
The concurrent self-assembly of new 1,3,5-trisamide-cyclohexane-based low molecular weight hydrogelators and various surfactants in water leads to the formation of self-assembled fibrillar networks with encapsulated micelles. This prototype system presents an example of orthogonal self-assembly, that is, the independe…
The process of electrospinning, which produces fibers in the nanometer to micron range under the influence of high voltages, has been widely studied to produce polymer and textile fibers. Mesoporous molecular sieve fibers have been produced in our lab, and this technique was extended to produce an interwoven mesh of p…
In order to reduce the number of ineffective configurations in a priori generated configuration spaces, a direct configuration interaction method has been developed which limits the electron occupations of orbital groups making up a total active space. A wave function is specified by first partitioning an active space…
When a liquid is cooled below its melting temperature, it usually crystallizes. However, if the quenching rate is fast enough, the system may remain in a disordered state, progressively losing its fluidity upon further cooling. When the time needed for the rearrangement of the local atomic structure reaches approximat…
Properties and potential applications of carbon nanotubes are summarized by emphasizing the aspects of nanoelectronics and nanoelectromechanical systems (NEMS). The main technologies for the assembly of nanodevices through nanomanipulations with scanning probe microscopes and nanorobotic manipulators are overviewed, f…
Surface-coated nanoparticles of LaF 3 and LaPO 4 doped with the luminescent trivalent lanthanide ions Eu 3+, Nd 3+, Er 3+, Pr 3+, Ho 3+, and Yb 3+ have been prepared. These ions emit in the visible and in the near-infrared part of the electromagnetic spectrum. The ions Nd 3+, Er 3+, Pr 3+, and Ho 3+ are the main focus…
The accumulation of reports on the puzzling behavior of guanidinium-rich oligo/polymers in bilayer membranes, reaching from HIV-Tat-like (HIV Tat is the human immunodeficiency virus transactivator of transcription) translocation to selectivity and voltage-gating of ion channels, prompted us to investigate possible con…