Materials Literature
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Abstract The effect of the starting polymer on the reaction of sulfonation of polysulfones was investigated. When concentrated sulfuric acid is used as the sulfonation reagent in an organic solvent‐free reaction, a polymer degradation equally occurs, leading to a decrease in the yield of product recovery. Poly(ether s…
The objective of this study was to gain insight into the electronic structure of silver-silver chloride cluster composites and especially into the metal-semiconductor interface. For this purpose a theoretical study of (AgCl)(n) (n=4, 32, 108, 192, and 256), of Ag(m) (m=1-9, 30, 115, 276, and 409), and of the cluster c…
Perfekt in Position gebracht für die [2+2]-Photodimerisierung werden Olefine in selbstorganisierten Koordinationskäfigen aus sechs Metallionen und vier dreizähnigen Liganden. In diesen gefäßartigen Nanokäfigen ließ sich die Dimerisierung von Acenaphthylenen und Naphthochinonen quantitativ, schnell und mit sehr hoher R…
A back-to-front synthesis of azuliporphyrins from an azulitripyrrane (1) has been developed. This methodology has allowed the first rational synthesis of the dicarbaporphyrinoid system 2.
The effect of particle size on the transport properties (resistivity and thermopower) of La0.5Pb0.5MnO3 has been investigated both in the presence and in the absence of magnetic field B=0.0–1.5 T (maximum). Grain size, dc conductivity; and the metal–insulator transition temperature Tp of the sample increase with incre…
In this paper we report the development of a family of polymerizable urea derivatives that are gelators for organic solvents. The design involves amino-acid-based urea derivatives containing methacrylate functional groups. Several of the bis-ureas show excellent gelation properties in a variety of organic solvents at…
Abstract Measurements of the thermal expansion coefficients (TECs) of cellulose crystals in the lateral direction are reported. Oriented films of highly crystalline cellulose I β and III I were prepared and then investigated with X‐ray diffraction at specific temperatures from room temperature to 250 °C during the hea…
Abstract The structural characterization and transport properties of blends of a commercial high molecular weight poly(ϵ‐caprolactone) with different amounts of a montmorillonite‐poly(ϵ‐caprolactone) nanocomposite containing 30 wt % clay were studied. Two different vapors were used for the sorption and diffusion analy…
The adjustable photoluminescence (PL) and field electron emission (FEE) properties of boron carbonitride (B–C–N) nanotubes grown under well-controlled conditions are studied systematically. Large-scale highly aligned B–C–N nanotubes are synthesized directly on Ni substrates by the bias-assisted hot filament chemical v…
Analysis of kinetics processes involved in carbon nanotube (NT) forest growth during chemical vapor deposition suggests that: (i) carbon species are unable to penetrate to the forest bottom whenever the mean free path in gas is much larger than the typical distance between NTs; instead they collide with NT surfaces, c…
Abstract The nucleation activity of the sorbitol derivatives 1,2,3,4‐bis(3,4‐dimethylbenzylidene sorbitol) and methyldibenzylidene sorbitol are compared with that of talc, a conventional nucleating agent for the monoclinic crystalline phase of isotactic polypropylene. The thermal parameters associated with the dynamic…
Two solid catalysts in which a chiral copper(II) bisoxazoline has been covalently anchored on silica and MCM-41 have been prepared; the solids are enantioselective catalysts (up to 92% ee) for the Friedel-Crafts hydroxyalkylation of 1,3-dimethoxybenzene with 3,3,3-trifluoropyruvate.
Polarized Raman spectra of oriented finely twinned ${\mathrm{CaMnO}}_{3}$ thin films and nonpolarized Raman spectra of ${\mathrm{CaMnO}}_{3}$ ceramics were studied at room temperature using several excitation laser wavelengths. The selection rules for the polarized Raman spectra, obtained from samples consisting of fi…
The experimentally measured coercive electric fields for domain reversal in ferroelectrics are typically many orders of magnitude lower than the estimates from phenomenological free-energy theory. This letter specifically investigates the influence of polarization gradients at pre-existing 180° domain walls in ferroel…
We studied the relation between the electronic structure and the phsyiscal properties of ${\mathrm{SrFe}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{O}}_{3}.$ The main technique used in the study was Fe $2p,$ Co $2p,$ and O $1s$ x-ray absorption spectroscopy. The experimental spectra were analyzed in terms of the con…
We have studied the temperature (T) and field (H) dependence of the magnetocaloric effect in a bulk amorphous Pd40Ni22.5Fe17.5P20 alloy. With decreasing T, and depending on H, the alloy exhibits superparamagnetic, field-induced ferromagnetic, and spin-glass behavior. The temperature-dependence of the magnetic entropy…
Combination of nanolithography and electrochemistry allows the chemical modification of individual single-walled carbon nanotubes (SWCNTs) by attachment of functional groups. This approach allows both the reductive as well as oxidative coupling of substituted phenyl groups, presumably to defect sites in the tubes. The…
The cluster ions Aun(CO)m(O2)u− (n = 2,3; m = 1, u = 1,2) are successfully synthesized via coadsorption of oxygen and carbon monoxide onto mass-selected gold clusters inside a temperature controlled ion trap at 100 K. The investigated gold clusters Au1–3− show a significant size dependence in the reactivity toward oxy…
Formation and evolution of fragmentation instabilities in fractal islands, obtained by deposition of silver clusters on graphite, are studied. The fragmentation dynamics and subsequent relaxation to the equilibrium shapes are controlled by the deposition conditions and cluster composition. Sharing common features with…
We formulate a lattice Boltzmann algorithm which solves the hydrodynamic equations of motion for nematic liquid crystals. The applicability of the approach is demonstrated by presenting results for two liquid crystal devices where flow has an important role to play in the switching.