Materials Literature
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Two kinds of configurations involving steps on surfaces are reviewed. The first one results from an initially planar vicinal surface, i.e. slightly deviating from a high-symmetry (001) or (111) orientation. In some cases, these surfaces separate into domains of different orientations by a mechanism which is very simil…
The most popular electronic structure method, the linear muffin-tin orbital method (LMTO), in its full-potential (FP) and relativistic forms has been extended to calculate the spectroscopic properties of materials form first principles, i.e, optical spectra, x-ray magnetic circular dichroism (XMCD) and magneto-optical…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTThe Synthesis of Hybrid Polymers Using Atom Transfer Radical Polymerization: Homopolymers and Block Copolymers from Polyhedral Oligomeric Silsesquioxane MonomersJeffrey Pyun and Krzysztof MatyjaszewskiView Author Information Center for Macromolecular Engineering, Department of…
The orientation of surface-active molecules at interfaces is extremely important in determining the dynamic and equilibrium properties of such systems. Films of fatty acid salts were studied at various pH values of the solutions. It was found that there exists a pH where minimum evaporation of water, maximum foamabili…
Nanoscale electromechanical systems-nanotweezers-based on carbon nanotubes have been developed for manipulation and interrogation of nanostructures. Electrically conducting and mechanically robust carbon nanotubes were attached to independent electrodes fabricated on pulled glass micropipettes. Voltages applied to the…
A natural rubber (NR) with a conventional sulfur cure system and a ratio of sulfur/accelerator (Ω) equal to 3 was investigated. The network structure of the NR during vulcanization was analyzed using a model of rubber elasticity based on the tube concept, which was applied to the treatment of the stress–strain measure…
We investigated the magnetic properties of the following approximants of quasicrystals in the Al(Si)-Pd-Mn system: two cubic compounds, 1/1-Al 68 Pd 11 Mn 14 Si 7 and 2/1-Al 70 Pd 24 Mn 6 , and three orthorhombic compounds ´-Al 71.9 Pd 23.5 Mn 4.6 , T-Al 73.1 Pd 5.2 Mn 21.7 , and T-Al 78.5 Pd 4.9 Mn 16.6 . No magnetic…
A normalized and universally applicable calibration function for the Fourier-transformed infrared (FTIR) quantification of the glycidyl methacrylate (GMA) grafting yield in polymers of known compositions having ethylene block sequences was established. The 1H nuclear magnetic resonance (1H-NMR) spectroscopy results ac…
Dielectric measurements of an epoxy resin, N, N-diglycidyl-4-glycidyloxyaniline, have been carried out in the supercooled and glassy phase over a broad frequency range (10 2 -6 ×10 9 Hz). The measurements reveal electrical transport due to ionic impurities as well as three different dipolar relaxations - in addition t…
A series of Eu 3+ -doped silica sol−gels are prepared under various conditions: (1) pH values of the sols are controlled at 3.0, 5.5, and 7.5; (2) the counterions of dopants are selected from acetate, chloride, and nitrate of europium (III) compounds; (3) two chelating agents, namely ethylenediaminetetraacetic acid (E…
A model based on the existence of two different competing local structures in water is described. It is shown that it can explain the transition between fragile and strong behaviour that supercooled water undergoes at around 220 K. The high-temperature behaviour is similar to that observed in standard fragile glass fo…
Depletion forces in colloidal systems are known to be entirely attractive, as long as the background of macromolecules is small enough that an ideal gas approach is valid. At higher densities, however, structural correlation effects of the macromolecules which lead to additional repulsive parts in the depletion intera…
The second-order nonlinear susceptibility of some novel 7,7-diarylnorbornane compounds in chloroform solution has been measured by EFISH at a fundamental wavelength λ = 1064 nm. Values of β z for the cofacial apical molecules ( 1 − 6 ) are enhanced in comparison to those reported for the uncoupled aryl rings. Highest…
Succinyl-CoA synthetase (SCS) catalyzes the following reversible reaction via a phosphorylated histidine intermediate (His 246alpha): succinyl-CoA + P(i) + NDP <--> succinate + CoA + NTP (N denotes adenosine or guanosine). To determine the structure of the enzyme with nucleotide bound, crystals of phosphorylated Esche…
The idealized mode-coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures, MCT predicts a slowing down of the local dynamics and ergodicity-breaking transitions. The non-ergodicity transitions share many features with the colloidal…
The thermal chemistry of iodomethane, iodoethane, 1-iodopropane, 1-iodobutane, and 2-iodohexane on copper (100), (110), and (111) single-crystal surfaces was characterized in this and previous studies by temperature-programmed desorption (TPD) spectroscopy. The main decomposition pathway available to the methyl surfac…
In the Al-Pd-Ru system, a structurally ordered icosahedral phase has been successfully produced near the composition Al 73 Pd 15 Ru 12 by heat treatment at 1273 K for several hours. The x-ray diffraction patterns of the Al-Pd-Ru i-phase are very sharp, indicating that the i-phase is quite stable and that samples of hi…
As a renewable and native polymeric material, thermoplastic starch is gaining increased acceptance because of resource and environment concerns. This study reports the formulation design of native starch/polyvinyl alcohol (PVAl) compounds; the preparation technology to make them available for thermoplastic processing;…
Linear tetrapyrroles related to phytochrome (1) were prepared in enantiospecific fashion by a new strategy beginning with ring-B,C synthons of type 19 (bis-iododipyrrins). Rings A and D were elaborated by Pd(0)-mediated coupling of 19a with the appropriate alkyne acid or amide derivatives 9 and 20, followed by intramo…
During the last years, many efforts have been devoted to the elimination of alkylphenol ethoxylate surfactants from aqueous systems. In this paper, the sonochemical degradation of aqueous solutions of Triton X-100 was performed at an ultrasonic frequency of 358 kHz and an applied power of 50 W. Analysis of the reactio…