Materials Literature
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We study polymer reaction kinetics at interfaces. The interface of width $h$ increments the effective dimensionality by 1: Rate constants $k$ obey scaling laws as for 4-dimensional bulk reaction problems. For groups with small reactivity $Q$, $k\ensuremath{\sim}h$ and is independent of molecular weight $N$. For large…
A theory is presented for the diffusion-controlled coupling of end-functionalized $A$ and $B$ homopolymers at an $A\ensuremath{-}B$ interface. The effective reaction rate coefficient ${k}_{e}$ is shown to exhibit a surprising degree of universality associated with the small center-of-mass diffusivity of high molecular…
Synthesis of Ge nanocrystals in SiO2 films is carried out by precipitation from a supersaturated solid solution of Ge in SiO2 made by Ge ion implantation. The films exhibit strong room-temperature visible photoluminescence. The measured photoluminescence peak energy and lifetimes show poor correlations with nanocrysta…
A thorough study of the low-temperature magnetic state of polycrystalline $({\mathrm{Tb}}_{1/3}{\mathrm{La}}_{2/3}{)}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_{3}$ has been carried out. This perovskitelike compound is an insulator at low temperatures and shows an insulator-metal transition under magnetic field. All the…
We present electrical measurements of single Au and CdSe nanocrystals. The devices are fabricated using a hybrid scheme which combines electron beam lithography and wet chemistry to bind nanocrystals in tunneling contact between two closely spaced metallic leads. The current–voltage characteristics of these devices ex…
Field emission measurements using 0.3 μm thick nitrogen containing hydrogenated amorphous carbon films (a-C:H:N) on n++-Si cathodes are reported. Onset emission fields as low as 4 V μm−1 have been obtained using a flat plate anode configuration. Uniform emission is observed over the entire cathode area at current dens…
We describe a technique for creating a thin polystyrene film containing a periodic array of cylindrical holes, with a hole size of approximately 13 nm and a lattice constant of 27 nm. The starting material is a polystyrene-polybutadiene diblock copolymer, which self-assembles into a hexagonally packed array of polybut…
We present an {\it ab initio} approach for the computation of the magnetic susceptibility $χ$ of insulators. The approach is applied to compute $χ$ in diamond and in solid neon using density functional theory in the local density approximation, obtaining good agreement with experimental data. In solid neon, we predict…
Several porous material systems (e.g.. hydrogels, conducting polymers, electrorheologic fluids) make possible a control of their properties in response to an appropriate stimulus (and viceversa) and therefore. they belong to the class of intelligent materials. In the present paper we propose a first classification of…
The generalized stacking fault (GSF) energy surfaces have received considerable attention due to their close relation to the mechanical properties of solids. We present a detailed study of the GSF energy surfaces of silicon within the framework of density functional theory. We have calculated the GSF energy surfaces f…
A general approach has been developed to determine the conductivity of individual nanostructures while simultaneously recording their structure. Conventional lithography has been used to contact electrically single ends of nanomaterials, and a force microscope equipped with a conducting probe tip has been used to map…
The behavior of plasma polymer coating for Cu corrosion protection was investigated in dc cathodic polymerization, with and without anode magnetron enhancement, af magnetron glow discharge polymerization, and rf glow discharge polymerization. The combination of visual and scanning electron microscopy observations esta…
The spinnable dope containing 20 wt % of silk fibroin dissolved in the MU solvent (e.g., LiBr · H2O = 40 wt %, and EtOH : H2O = 100 : 0 in volume) was spun into a coagulant and subsequently drawn, to give the following results. 1 Methanol, ethanol, and isopropanol were a predominant coagulant for the dope, and the coa…
High-melt-strength polypropylene (PP) was achieved with irradiation by an electron beam generated from an accelerator in the presence of polyfunctional monomers (PFM). Among 16 PFMs, the relatively shorter molecular chain bifunctional monomers such as 1,4-butanediol diacrylate (BDDA) and 1,6-hexanediol diacrylate (HDD…
A series of six thermoplastic polyurethane elastomers were synthesized from a 4,4′-methylene diphenyl diisocyanate (MDI) and 1,4-butanediol (BDO) chain extender, with poly(ethyleneoxide) (PEO), poly(tetramethylene oxide) (PTMO), poly(hexamethylene oxide) (PHMO), poly(octamethylene oxide) (POMO), poly(decamethylene oxi…
Two classes of siloxane copolymers were evaluated for their resistance to the low earth orbit (LEO) environment. Poly(imide–siloxane) (PISX) copolymers were used as the resin for PISX–carbon fiber composites. These composites were exposed to the LEO environment, for 50 h, as part of the “Effect of Oxygen Interaction w…
The non-equilibrium behaviour of concentrated colloidal dispersions is studied by Stokesian Dynamics, a general molecular-dynamics-like technique for simulating particles suspended in a viscous fluid. The simulations are of a suspension of monodisperse Brownian hard spheres in simple shear flow as a function of the Pé…
The peculiar spectroscopic properties of the lanthanide metal ions (4f-block, Lnlll), and particularly Eulll and Tblll, make them suitable for the design of chemical luminescent probes and analytical sensors when Lnlll is introduced into organized molecular architectures possessing controlled and protected coordinatio…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTwo Modes of Self-Coordinating Edge-over-Edge Zn(II) Porphyrin Dimerization: A Structural and Spectroscopic Comparison†Robert T. Stibrany, Jayasree Vasudevan, Spencer Knapp, Joseph A. Potenza, Tom Emge, and Harvey J. SchugarView Author Information Department of Chemist…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTThe First Isolation and Characterization of a Palladium−Copper Heterometallic Complex Bearing μ4-Oxo Atom Derived from Molecular OxygenTakahiro Hosokawa, Minoru Takano, and Shun-Ichi MurahashiView Author Information Department of Chemistry, Faculty of Engineering Scien…