Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSANS and Cryo-TEM Study of Self-Assembled Diblock Copolypeptide Hydrogels with Rich Nano- through Microscale MorphologyDarrin J. Pochan, Lisa Pakstis, Bulent Ozbas, Andrew P. Nowak, and Timothy J. DemingView Author Information Mater…
Experimental control of block copolymer segregation is ideally achieved by varying temperature, but in practice, the range of segregation is very restricted. A far greater range can be accessed by diluting the block copolymer melt with a solvent, assuming the mixture obeys the so-called dilution approximation. We exam…
UV excitation of ${\mathrm{Ce}}^{3+}$-doped ${\mathrm{Ca}}_{2}{\mathrm{Al}}_{2}{\mathrm{SiO}}_{7}$ melilite crystals produces long-lasting phosphorescence $(1\ensuremath{-}{10}^{3} \mathrm{s})$ from ${\mathrm{Ce}}^{3+}$ ions in addition to the intrinsic ${\mathrm{Ce}}^{3+}$ luminescence with a lifetime of 40 ns. The d…
Polymers containing coumarin and Ru(BpyMe 2 ) 3 2+ chromophores were synthesized using a grafting approach and also a copolymerization approach. It was found that the solubility of polymers made from Ru-containing monomers was higher than that observed for comparable polymers obtained by grafting of Ru complexes onto…
Surface-tethered triblock copolymers composed of poly(methyl acrylate), poly(methyl methacrylate), and poly(2-hydroxyethyl methacrylate) were grown from gold substrates by a series of atom transfer radical polymerizations at ambient temperature. GPC determinations of the molecular weights of desorbed triblock homopoly…
Covalently bonded layered silicates/polyimide (BTDA-ODA) nanocomposites have been synthesized from γ-(aminopropyl)triethoxysilane (APTS) grafted kenyaite and poly(amic acid). The existence of covalent bonds between APTS and silicates and between APTS and the dianhydride end groups of the polymer have been confirmed by…
Two novel B 3 monomers, tri(phthalic anhydride) and tri(phthalic acid methyl ester), were synthesized. Hyperbranched polyimides were prepared by A 2 + B 3 polymerizations of (a) 1,4-phenylenediamine (A 2 ) and tri(phthalic anhydride) (B 3 ) (method A) and (b) 1,4-phenylenediamine (A 2 ) and tri(phthalic acid methyl es…
We have studied the thin film morphologies of polystyrene- b -poly(2-vinylpyridine) diblock copolymers and polystyrene- b -poly(2-vinylpyridine)- b -poly( tert -butyl methacrylate) triblock copolymers after “annealing” in the vapor of different solvents. We find distinct differences in the resulting thin film morpholo…
In this paper we report on the optical spectroscopy and upconversion studies of Ho 3+ -doped nanocrystalline and bulk Y 2 O 3, as a function of holmium concentration (0.1, 0.5, 1, 2, 5, and 10 mol %). Emission in the blue, green, red, and NIR portions of the spectrum is recorded after 457.9-nm excitation. Red (646 nm)…
High-field electron-spin-resonance (ESR) experiments have been carried out in single crystals of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ in the concentration range $0<~x<~0.175.$ Different quasioptical arrangements have been utilized for frequencies $40<~\ensuremath{\nu}<~700…
A new model of crystal growth is presented that describes the phenomena on atomic length and diffusive time scales. The former incorporates elastic and plastic deformation in a natural manner, and the latter enables access to time scales much larger than conventional atomic methods. The model is shown to be consistent…
We describe measurements of the stiffness and Young’s modulus, Y of single crystals of molybdenum-based compounds. Atomic force microscopy is used first to image, and then to perform stiffness measurements on crystals which are growing up out of a substrate. Y is extracted by comparing the measured stiffness with that…
Von schwach blau zu intensiv blaugrün: Diese Veränderung der Emission ist die Folge der Reaktion von [RuCl2(POC4Pyr-P,O)2] mit Kohlenmonoxid. Der Grund ist die Bildung des gezeigten Dicarbonylkomplexes, in dem CO das labile Koordinationszentrum des hemilabilen Liganden POC4Pyr verdrängt hat. Die höhere Flexibilität de…
In the present work we report on the detailed structural features of the chiral N21- and N22-substituted benzyl and picolyl derivatives of tris(pentafluorophenyl)corrole [H3(tpfc)]. The main difference between the isomers is that substitution on N22 creates a much more crowded environment, reflected in higher deformat…
Abstract Highly oriented poly(trimethylene terephthalate) (PTT) fiber has a low birefringence that is unexpected for an aromatic polyester with a high refractive index. To explain this observation, the intrinsic birefringence Δ n of PTT crystal was calculated from its bond polarizabilities to be 0.029. This Δ n is alm…
Response properties of photoinduced gratings were studied in planar cells of liquid crystal doped with multiwalled carbon nanotubes. The grating formation time deduced from beam-coupling measurements was obtained to be ~30 ms. Absorption spectroscopy implies that the permanent gratings are associated with periodically…
The mechanism of stoichiometric enantioselective alkene epoxidations by the D4- and D2-symmetric homochiral trans-dioxoruthenium(VI) porphyrins, [RuVI(D4-Por*)O2] (1) and [RuVI(D2-Por*)O2] (2a), in the presence of pyrazole (Hpz) was studied by UV/Vis spectrophotometry and analysis of the organic products. The enantios…
Polycrystalline boron carbon nitride (BCN) films are synthesized by plasma-assisted chemical vapor deposition. The dielectric constant is estimated from the accumulation region of capacitance–voltage characteristics of Cu/BCN/p-Si samples. It is found that the dielectric constant of the BCN film is reduced by annealin…
Well-aligned boron nanowire arrays were grown vertically on silicon substrates over areas up to several tens of square centimeters using radio-frequency magnetron sputtering of highly pure boron. During growth and self-assembly of boron nanowire arrays, no template or catalyst was needed. The morphology, structure, an…
Edle Partikel: Durch einfaches Mischen bei Raumtemperatur von Ag-, Au-, Pd- oder Pt-Salzen mit reduzierten Polyoxometallaten, die als Photokatalysatoren und Stabilisatoren dienen, ließen sich ultrafeine Metall-Nanopartikel erhalten (siehe Reaktionszyklus).