Materials Literature
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Monolithic ethane−silica gels with well-defined co-continuous macropores and highly ordered mesopores have been synthesized via a spontaneous route from silicon alkoxide with the aid of a structure-directing agent. While the macropores are formed by the concurrent phase separation and sol−gel transition induced by the…
Abstract FT‐Raman and surface‐enhanced Raman scattering (SERS) spectroscopy were applied in the vibrational characterization and study of the adsorption and acidity behavior of the highly fluorescent anthraquinone dye alizarin on Ag colloids prepared by chemical reduction with hydroxylamine hydrochloride. The SERS spe…
The phase structures and transition behaviors of a series of mesogen-jacketed liquid crystalline (LC) polymers, poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrenes} (PMPCS), with different molecular weights (MW) and narrow MW distributions were studied using differential scanning calorimetry, polarized light microscopy…
Gold-plated gold: NAD(P)H cofactors mediate the catalytic growth of Au nanoparticles in the presence of AuCl4− and CTAB (cetyltrimethylammonium bromide; see picture). The process allows for the optical detection of the cofactors and the analysis of NAD(P)+-dependent biocatalyzed transformations in solutions and on sur…
We study current-induced step bunching and wandering instabilities with subsequent pattern formations on vicinal surfaces. A novel two-region diffusion model is developed, where we assume that there are different diffusion rates on terraces and in a small region around a step, generally arising from local differences…
We present calculation of the high pressure crystal structures in selenium, including rational approximants to the recently reported incommensurate phases. We show how the incommensurate phases can be intuitively explained in terms of imaginary phonon frequencies arising from Kohn anomalies in the putative undistorted…
We report an ab-initio investigation of several possible Si and Ge pristine nanowires with diameters between 0.5 and 1.2 nm. We considered nanowires based on the diamond structure, high-density bulk structures, and fullerene-like structures. We find that the diamond structure nanowires are unstable for diameters small…
Coarse-grained modeling of dynamics on vicinal surfaces concentrates on the diffusion of adatoms on terraces with boundary conditions at sharp steps, as first studied by Burton, Cabrera and Frank (BCF). Recent electromigration experiments on vicinal Si surfaces suggest the need for more general boundary conditions in…
Application of Bardeen's tunneling theory to magnetic tunnel junctions having a general degree of atomic disorder reveals the close relationship between magneto-conduction and voltage-driven pseudo-torque, as well as the thickness dependence of tunnel-polarization factors. Among the results: 1) The torque generally va…
Highly stable silver nanoclusters with narrow size distribution have been prepared by heating a third-generation poly(propyleneimine) dendrimer/AgNO 3 aqueous solution without the additional step of introducing other reducing agents and protect agents. UV−vis absorption, transmission electron microscopy (TEM), X-ray p…
This article describes the structural and optical properties of a new class of hybrid nanoparticles that consists of a small gold core (∼60 nm in diameter) coated with a biocompatible hydrogel polymer shell varying from ∼20 to ∼90 nm in thickness. These nanoparticles are being developed to serve as unique drug-deliver…
We have followed the time development of the microdomain structure in symmetric diblock copolymer poly(styrene- b -methyl methacrylate), P(S- b -MMA), ultrathin films via PMMA-selective solvent vapor treatment by atomic force microscopy (AFM). After preparation on a substrate preferentially attracting the PMMA block,…
Abstract Summary: Novel regenerated cellulose fibers have been successfully spun from the cellulose dope in NaOH/urea aqueous solution, which could rapidly dissolve cellulose. The fibers possess circular cross‐sections as well as relatively high molecular weight, and a crystallinity index with cellulose II family crys…
Infrared (IR) spectra of new types of bacterial copolyester, poly(3-hydroxybutyrate- co -3-hydroxyhexanoate), P(HB- co -HHx) (HHx = 2.5, 3.4, and 12 mol %), and poly(3-hydroxybutyrate) (PHB) were measured over a temperature range of 20 °C to higher temperatures (PHB, 185 °C; HHx = 2.5 mol %, 160 °C; HHx = 3.4 mol %, 1…
Abstract Poly(acrylonitrile) (PAN) solutions in N , N ‐dimethylformamide were electrospun into webs consisting of 350 nm ultra‐fine fibers. The webs were oxidatively stabilized and followed by heat treatment in the range of 700–1000°C. Characterization of the microstructure of PAN‐based carbon nanofibers was performed…
Molecular simulations were performed to study a system consisting of protein (e.g., lysozyme) and self-assembled monolayers (SAMs) terminating with different chemical groups in the presence of explicit water molecules and ions. Mixed SAMs of oligo (ethylene glycol) [S(CH2)4(OCH2CH2)4OH, (OEG)] and hydroxyl-terminated…
Air bubbles have been formed using partially hydrophobic silica nanoparticles as the stabilizer. The particles were of primary particle size 20 nm, chemically treated to different degrees with dichlorodimethylsilane to render them partially hydrophobic. Above a certain bubble size range (typically 80-microm diameter),…
Electrospinning of nanofibers of materials that are difficult to process using conventional techniques is reported. Two fluids are electrospun (see Figure) into fibers with core/shell morphology. The “electrospinnable” shell fluid serves as a process aid to electrospin the core fluid. Three examples are illustrated: p…
Intramolecular folding events, triggered by the presence of salt, induce the self-assembly of β-hairpin peptides into hydrogel networks at physiological conditions. At pH 7.4 and low ionic strength solution conditions, dilute, homogeneous solutions of peptide (≤2 wt %) exhibit the viscosity of pure water. Circular dic…
The production of significant quantities of engineered nanomaterials will inevitably result in the introduction of these materials to the environment. Mobility in a well-defined porous medium was evaluated for eight particulate products of nanochemistry to assess their potential for migration in porous media such as g…