Materials Literature
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Controlled room-temperature photoluminescence (PL) and electroluminescence (EL) from porous silicon (PSi) multilayer structures are achieved. The basic structure is composed of two PSi multilayer mirrors sandwiching a highly luminescent PSi film. This creates an active microcavity resonator, in which a significant PL…
Functionalization of hydride-terminated porous and single-crystal silicon surfaces with organic species is accomplished by electrochemical reduction of organo iodides and organo bromides (see scheme). This new method is fast and efficient, and achieves high surface coverage with functionalized and nonfunctionalized al…
We describe in greater detail the exactly solvable microscopic model we have developed for analyzing the strain-mediated interaction of vacancy lines in a pseudomorphic adsorbate system (Phys. Rev. Lett., to appear). The model is applied to Ga/Si(112) by extracting values for the microscopic parameters from total-ener…
Highly polarized and self-waveguided blue light emission was observed in oriented organic crystals of p-sexiphenyl (6P). The 6P molecules were epitaxially grown in needlelike crystals with a submillimeter length by mask-shadowing vapor deposition on the KCl (001) surface. In the crystals, the molecular axes are orient…
The temperature dependence of the Edwards-Anderson order parameter ${q}_{\mathrm{EA}}$ and the local polarization distribution function $W(\stackrel{\ensuremath{\rightarrow}}{p})$ have been determined in a PMN single crystal via 2D ${}^{93}\mathrm{Nb}$ NMR. A glasslike freezing of reorientable polar clusters occurs in…
Two distinct proteins, streptavidin and HupR, bind and form regular helical arrays on the surface of multiwalled carbon nanotubes under appropriate conditions (see picture). The decoration of the outer surface of these nanostructures with biological macromolecules was investigated by electron microscopy.
A novel bismaleimide, 2,2′-dimethyl-4,4′-bis(4-maleimidophenoxy)biphenyl, containing noncoplanar 2,2′-dimethylbiphenylene and flexible ether units in the polymer backbone was synthesized from 2,2′-dimethyl-4,4′-bis(4-aminophenoxy)biphenyl with maleic anhydride. The bismaleimide was reacted with 11 diamines using m-cre…
The degradation of polyaniline at anodic potentials was studied with in situ UV–Vis spectroscopy of polymer-coated ITO glass electrodes. Spectral changes at high potential values were observed and discussed. Degradation follows first-order kinetics, with rate constants ranging from 8.40 × 10−6 to 2.93 × 10−3 s−1 at el…
A crystalline polymer, Nylon 6, was selectively blended with various amorphous polymers containing phenolic moieties. It was found that moisture absorption by the amide group in Nylon 6 could effectively be reduced by blending with p-Cl-novolac at ratios as low as 2 phr (part per hundred resin). Blends of Nylon 6 with…
In this article, we have successfully synthesized polyurethanes (PUs) with a covalent bond of dye molecule via a coupling agent of epichlorohydrin. The structure is proven by infrared (IR) spectra, which exhibits the absorption peak of dye molecule, as we expected. The dye-grafted polyurethanes were used to evaluate t…
The dielectric properties of isotactic polypropylene/acrylonitrile–butadiene rubber blends have been investigated as a function of frequency with special reference to the effect of blend ratio. The dielectric properties measured were volume resistivity, dielectric constant (ϵ′), dissipation factor (tan δ), and loss fa…
Phase relations in the system Na−K−P−W−O have been studied for two values m = 4 and m = 6 of the relevant parameter m which characterizes the thickness of the perovskite WO 3 -type slabs within the series of the low dimensional tungsten phosphate bronzes (K x Na y )(PO 2 ) 4 (WO 3 ) 2 m . New Na y P 4 W 12 O 44 bronze…
X-band ESR powder studies have been done on the spin transition in Mn(2+)-doped [Fe(bpp)(2)][CF(3)SO(3)](2).H(2)O and [Fe(bpp)(2)][BF(4)](2) (bpp = 2,6-bis(pyrazol-3-yl) pyridine). The change in D value of Mn(2+) during the thermally induced high-spin (HS) <--> low-spin (LS) transition shows that the spin transition i…
A glass-forming, low molecular weight diaminobiphenyl compound with incorporated azo groups was synthesized. It exhibits a glass transition temperature well above room temperature (101 °C), which is explained in terms of molecular structure. Holographic birefringence gratings as well as surface gratings were produced…
Bulky substituents added to second-order nonlinear optical (NLO) chromophores inhibit intermolecular electrostatic interactions that attenuate electric poling induced macroscopic electrooptic activity. Such chromophore modification also improves chemical and photochemical stability and the processability of chromophor…
We study theoretically the adsorption of surfactant onto the interface of gas bubbles in creeping flow rising steadily in an infinite liquid phase containing surface-active agents. When a bubble rises in the fluid, surfactant adsorbs onto the surface at the leading edge, is convected by the surface flow to the trailin…
High molecular weight hyperbranched polyetherimides have been synthesized in a single-pot reaction in as little as 2.5 min from an easily synthesized and scalable AB 2 monomer using a rapid catalytic arylation method. NMR integration experiments and model compound studies revealed a degree of branching (DB) of 67% for…
We propose a genetic local search algorithm (GLSA) for the optimization design of diffractive optical elements (DOE's). This hybrid algorithm incorporates advantages of both genetic algorithm (GA) and local search techniques. It appears better able to locate the global minimum compared with a canonical GA. Sample case…
Single crystals of a novel titanium glycolate complex, Ti(OCH 2 CH 2 O) 2, have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal analysis (TG-DTA), and scanning electron microscopy (SEM). The titanium glycolate complex crystallizes in the monoclinic space…
The wetting behavior of P(S- b -I) and P(S- b -nBMA) thin films placed upon tunable P(S- r -MMA) brush surfaces is addressed. Homopolymer dewetting experiments show an increase in interfacial energy between PI and P(S- r -MMA) with increasing styrene fraction, while the interfacial energy dependence of PnBMA with brus…