Materials Literature
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We investigate the conductance spectra of a normal-superconductor graphene junction using the extended Blonder-Tinkham-Klapwijk formalism, considering pairing potentials that are both conventional (isotropic $s$-wave) and unconventional (anisotropic $d$-wave). In particular, we study the full crossover from normal to…
This paper reviews the properties of aqueous foams. The current state of knowledge is summarized briefly and the interdisciplinary aspects of this field of investigation are emphasized. Many phenomena are controlled by physical laws, but they are highly dependent upon the chemicals used as foam stabilizers: surfactant…
A series of benzobis(imidazolium) (BBI) salts has been prepared and studied as a new class of versatile fluorescent materials. Using a high yielding, modular synthetic strategy, BBI salts with a range of functionality poised for investigating fundamental and applications-oriented characteristics, including emission wa…
We report on structural properties of PEO−PPO−PEO type of triblock block copolymers (Pluronics F127) with special emphasis on the effect of diblock PEO−PPO impurities on the ordered gel phase. Commercial F127 polymers contain as received roughly 20% PEO−PPO diblock and 80% PEO−PPO−PEO triblock copolymers. Aqueous solu…
Chitosan was chemically modified to produce quaternary ammonium salts in order to improve its antimicrobial activity and physicochemical properties. Quaternization of N-alkyl chitosan derivatives was carried out using alkyl iodide to elaborate water-soluble cationic polyelectrolytes ( N, N, N-trimethylchitosan, TMC).…
Collagen is the most abundant protein in animals, including humans. The prevalent (2 S,4 R )-4-hydroxyproline (Hyp) residues of collagen are known to confer great stability upon its triple-helical conformation. The basis for that stability has been attributed to hydration of the pendant hydroxyl groups. Here, that att…
We report selection and characterization of hydroxyapatite-binding heptapeptides from a peptide-phage library and demonstrate the effects of two peptides, with different binding affinities and structural properties, on the mineralization of calcium phosphate mineral. In vitro mineralization studies carried out using o…
Ag 2 S nanospheres were synthesized by a hydrothermal reaction using l -cysteine as the sulfur source and chelating reagent. The X-ray diffraction patterns and X-ray photoelectron spectra confirmed that the products were monoclinic α-Ag 2 S. The optical absorption spectra of the Ag 2 S nanospheres showed very broad ab…
We study ultrafast photoluminescence (PL) dynamics of Si nanocrystals (NCs). The early-time PL spectra (<1 ns), which show strong dependence on NC size, are attributed to emission involving NC quantized states. The PL spectra recorded for long delays (>10 ns) are almost independent of NC size and are likely due to sur…
Using density functional theory (DFT), we analyze the influence of five classes of functional groups, as exemplified by NO2, OCH3, CH3, CCl3, and I, on the transport properties of a 1,4-benzenedithiolate (BDT) and 1,4-benzenediamine (BDA) molecular junction with gold electrodes. Our analysis demonstrates how ideas fro…
We have successfully grown epitaxial La$_{1.67}$Sr$_{0.33}$NiO$_4$ films with a small crystalline mosaic using pulsed laser deposition. With synchrotron radiation, the x-ray diffraction peaks associated with charge stripes have been successfully observed for relatively thick films. Anomalies due to the charge-ordering…
There is currently much interest in materials and structures that provide coupled ferroelectric and ferromagnetic responses, with a long-term goal of developing new memories and spintronic logic elements. Within the field there is a focus on composites coupled by magnetostrictive and piezoelectric strain transmitted a…
We study the optical emission from single semiconductor quantum dots coupled to the optical modes of photonic crystal nanocavities. For dots that are both spectrally and spatially coupled, auto-correlation measurements reveal efficient single photon generation, with a drastically reduced lifetime due to the Purcell-ef…
The sputtering of hexagonal boron nitride due to low energy xenon ion bombardments occurs in various applications including fabrication of cubic boron nitride and erosion of Hall thruster channel walls. At low ion energies, accurate experimental characterization of sputter yields increases in difficulty due to the low…
The element-specific technique of x-ray magnetic circular dichroism (XMCD) is used to directly determine the magnitude and character of the valence band orbital magnetic moments in (III,Mn)As ferromagnetic semiconductors. A distinct dichroism is observed at the $\mathrm{As}\phantom{\rule{0.2em}{0ex}}K$ absorption edge…
Controlled phase changes: Thermosensitive Au nanoparticles with tunable lower critical solution temperature have been prepared by coating the nanoparticles with a thermo- and pH-responsive hyperbranched polyelectrolyte. The globular, polyfunctional structure of the hyperbranched polymers offer new options to control p…
Peptides have been an integral part of the collagen triple-helix structure story, and have continued to serve as useful models for biophysical studies and for establishing biologically important sequence-structure-function relationships. High resolution structures of triple-helical peptides have confirmed the basic Ra…
Theoretical calculations of the structure, formation, and migration of kinks on a nondissociated screw dislocation in silicon have been carried out using density functional theory calculations as well as calculations based on interatomic potential functions. The results show that the structure of a single kink is char…
We report the results of theoretical investigations of low frequency tunneling current noise spectra component (1/f^α). Localized states of individual impurity atoms play the key role in low frequency tunneling current noise formation. It is found that switching "on" and "off" of Coulomb interaction of conduction elec…
We express dynamics of domain walls in ferromagnetic nanowires in terms of collective coordinates generalizing Thiele's steady-state results. For weak external perturbations the dynamics is dominated by a few soft modes. The general approach is illustrated on the example of a vortex wall relevant to recent experiments…