Materials Literature
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Mixed perovskites (AA‘)(BB‘)O 3, where A = La or Nd, A‘ = Sr, B = Al or Ga, and B‘ = Ta or Nb, were investigated by X-ray photoelectron spectroscopy (XPS). The interpretation of XPS O(1s) signals in mixed oxides is discussed. The nonsingular O(1s) peak that occurs in the mixed oxides is due to the polarization of the…
We present a new and general mechanism for inter-conversion of carbon structures via a catalytic exchange process, which operates under conditions of Frenkel pair generation. The mechanism typically lowers reaction barriers by a factor of four compared to equivilent uncatalysed reactions. We examine the relevance of t…
We describe a method for creating atomic-scale electric contacts. A metal source is deposited on two insulating substrates separated by a 70 nm gap. Electric conductance across the gap is monitored, while protrusions from the bulk extend into the gap and reach corresponding protrusions on the other side of the gap. Wh…
The variational approach to weakly nonlocal thermodynamic theories is critically revisited in the light of modern nonequilibrium thermodynamics. The example of Ginzburg-Landau equation is investigated in detail.
The spontaneous polarization and the piezoelectric constants of ZnO and BeO are calculated at an ab initio quantum-mechanical level by using two alternative strategies, namely, through the Berry phase scheme applied to delocalized crystalline orbitals, and through the definition of well-localized Wannier functions. Th…
Abstract Poly(3‐hydroxybutyrate) (PHB)/poly(glycidyl methacrylate) (PGMA) blends were prepared by a solution‐precipitation procedure. The compatibility and thermal decomposition behavior of the PHB/PGMA blends was studied with differential scanning calorimetry, thermogravimetric analysis, and differential thermal anal…
Abstract Supertough nylon 11 is prepared by using a plasticizer. The influence of plasticizers on the impact property and tensile properties of plasticized nylon 11 were investigated. The results show that the impact strength is improved remarkably by methylbenzene sulfonamide, and the tensile strength is almost the s…
Abstract A novel synthetic procedure for the preparation of poly(oxadiazole)s was developed with nucleophilic substitution of α,ω‐alkanediols with oxadiazole‐activated bisfluoride. Seven poly(oxadiazole)s were successfully prepared by the solution polymerization of 2,5‐bis(4‐fluorophenyl)‐1,3,4‐oxadiazole and various…
Abstract A series of new thermotropic main‐chain liquid crystalline copolyesters were prepared by polycondensation of 2,6‐naphthalenedicarbonyl chloride, 4,4′‐thiodiphenol, and α,ω‐alkanediols ( n = 4–10) in diphenyl ether at 200°C. Thermal transition behaviors of these copolyesters were investigated by differential s…
The graft copolymerization of methyl methacrylate onto mercaptochitin and some properties of the resulting graft copolymers have been studied. Methyl methacrylate was efficiently graft copolymerized onto mercaptochitin in dimethyl sulfoxide, and the grafting percentage reached 1300% under appropriate conditions. Altho…
Methacrylate derivatives bearing β-D-glucopyranoside and β-D-galactopyranoside residues are synthesised by glycosylation of 2-hydroxyethyl methacrylate (HEMA) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide, respectively. β-Selectivity in the glycosylation…
Reduction of an excess of arsenic with a solution of sodium in liquid ammonia yields the thermally unstable title compound [Na(NH3)5]2As(4).3NH3, which contains isolated square-planar As4(2-) ions with a mean As-As bond length of 2,345 A.
Coordination to a Zn(II) center of chelating π-delocalized nitrogen donor ligands such as 5-X-1,10-phenanthrolines (X = OMe, NMe 2, trans- CH CHC 6 H 4 - 4‘ - NMe 2, trans,trans -(CH CH) 2 C 6 H 4 - 4‘ - NMe 2 ) produces a significant enhancement of their quadratic hyperpolarizability measured either by the EFISH tech…
Abstract Interpenetrating networks (IPNs) of polybutadiene‐based polyurethane (PU) and poly(methyl methacrylate) (PMMA) were synthesized. The effect of the incorporation of 2% glycidyl methacrylate (GMA) and 2‐hydroxyethyl methacrylate (2‐HEMA) on the thermal, mechanical, and morphological properties of IPNs was inves…
Abstract Blends of polycarbonate (PC) and poly(acrylonitrile‐ co ‐butadiene‐ co ‐styrene) (ABS) with different compositions are characterized by means of dynamic mechanical measurements. The samples show phase separation. The shift in the temperatures of the main dynamic mechanical relaxation shown by the blend with r…
γ orthorhombic isotactic polypropylene transcrystallinity nucleated on aramid fibers under high pressure was investigated by synchrotron X-ray diffraction and by scanning electron microscopy. It was determined that the c axes of the lamellae (the growth axes) are distributed radially about the fiber and that the lamel…
We use molecular dynamics simulations to model realistic silica-based sol−gel solutions containing water, the simplest alcohols (MeOH and EtOH), the simplest silica alkoxides (Si(OMe) 4 and Si(OEt) 4 ), and small silica clusters (Si(OH) 4, Si 2 O(OH) 6, and Si 3 O 3 (OH) 6 ), at ambient conditions. This work builds on…
A simple and reproducible single phase preparation of 2.5 nm silver nanoclusters is described using silver benzoate along with triethylamine (TEA) and dodecanethiol (DDT); these spontaneously self-assemble to a two-dimensional array whereas in the absence of thiol only polydispersed nanoclusters are obtained.
The cluster compound Au55(PPh3)12Cl6 has been reanalyzed by photoelectron spectroscopy giving direct evidence for a nonmetallic behavior of the individual Au clusters as long as their ligand shell remains intact. The exposure to x-rays during the measurements is found to partly decompose the shell by removal of the ch…
The thermal recovery behavior of fluorinated single-walled carbon nanotubes has been systematically examined by UV−vis−near-IR absorption spectroscopy, IR absorption spectroscopy and electric resistance measurements under different annealing temperatures. The decrease in the IR intensity of C−F stretch bands centered…