Materials Literature
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Abstract The determination of microfibril angle (MFA), cellulose crystallite width and microdensity by SilviScan-2 at CSIRO confirmed that several dark bands in the heartwood of an Acacia species were associated with tension wood (TW) fibres. The straight log was taken from a tree of about 30 years of age that had bee…
Abstract This investigation studied the solution polymerization of ethylene in Isopar E in a semibatch reactor using CGC‐Ti as catalyst and methylalumoxane (MAO) and tris(pentaflourophenyl)borane [B(C 6 F 5 ) 3 ] as cocatalysts. The effects of cocatalyst type and amount on the chain microstructure were investigated. 1…
Abstract New polymers for second‐order nonlinear optical (NLO) applications were synthesized and characterized. They were distinguished by the presence of chromophore groups, with various molecular hyperpolarizability values, used as pendants on substantially rigid backbones. The polymers were prepared through the rea…
Abstract During the last two decades, growing interest in the field of material chemistry has been focused on the synthetic design of organic high‐spin molecules for use as novel magnetic materials. Conjugated radicals based on the bis(pyrazolyl)pyridine core are very attractive in principle, since they per se combine…
Abstract It is recently conceptualized that nano-scale machining might be achieved by coupling electron emission with radiation transfer. A laser may be used to heat a workpiece to a threshold temperature, and a nano-probe might then transfer additional energy via electron emission to remove a minute amount of materia…
Abstract Summary: We prepared surface‐grafted polystyrene (PS) beads with comb‐like poly(ethylene glycol) (PEG) chains. To accomplish this, conventional gel‐type PS beads (35–75 μm) were treated with ozone gas to introduce hydroperoxide groups onto the surface. Using these hydroperoxide groups, poly(methyl methacrylat…
Abstract The effect of refining on the fiber wall was studied for bleached kraft pulp fractions from pine first thinnings and pine sawmill chips. Hydrocyclone fractionation of both pulps produced fractions enriched in earlywood and latewood fibers. Some external fibrillation but no changes in fiber wall thickness were…
Abstract The aim of the study was to evaluate the effect of refining on the ultrastructure of spruce pulp fibres. Pulps with different molar masses of cellulose (estimated as intrinsic viscosity) were studied after PFI-refining. The molar masses of the polymers were decreased by increases in alkali concentration durin…
[reaction: see text] Irradiation of 5,12-didecyloxytetracene (1) leads to photodimers P(1) (planosymmetric) and P(2) (centrosymmetric). P(1) is characterized by naphthalene excimer fluorescence, whereas P(2) emits naphthalene monomer fluorescence.
New dielectric spectroscopy results are reported for propylene carbonate (PC), glycerol, and threitol, measured at very high (1.8 GPa) pressure. These glass formers all exhibit an excess wing in their dielectric spectrum above T(g). We show that the shape of the alpha peak and excess wing of PC are invariant to pressu…
We report on the impulsive generation of coherent optical phonons in ${\mathrm{CdTe}}_{0.68}{\mathrm{Se}}_{0.32}$ nanocrystallites embedded in a glass matrix. Pump-probe experiments using femtosecond laser pulses were performed by tuning the laser central energy to resonate with the absorption edge of the nanocrystals…
In the last couple of years, there has been increasing debate as to the presence and role of intermediate states on the folding pathways of several small proteins, including the 76-residue protein ubiquitin. Here, we present detailed kinetic studies to establish whether an intermediate state is ever populated during t…
Abstract Iodine staining has been used to study the orientation of cellulose microfibrils in wood using light microscopy. The aim of this work was to understand the exact nature of the staining reaction with iodine and to provide insight into the properties and organisation of the wood cell wall. Based on transmission…
Brownian dynamics simulations of trifunctional hyperbranched polymers (HP) of different molecular weight ( N ), degree of branching (DB), and Wiener index ( W ) have been performed under the influence of uniaxial elongational flow. Perfect trifuctional dendrimers with a trifunctional core up to the sixth generation we…
Die langsame Relaxation der Magnetisierung belegt, dass [Mn2(saltmen)2(ReO4)2] (saltmen2−=N,N′-(1,1,2,2-Tetramethylethylen)bis(salicylideniminat), ein einfacher, dimerer Out-of-plane-MnIII-Komplex mit einem [MnIII(μ-O)2MnIII]-Kern (siehe Bild, Mn braun, O rot, N blau, Re pink), ein Einzelmolekülmagnet ist. Die beiden…
Baeyer−Villiger oxidation of poly[( S )-2-methyl-1-oxopropane-1,3-diyl] ( 1 ) with m -chloroperbenzoic acid provided poly(ketone/ester) ( 2 ) in a ratio of ketone/ester = 82/18 in 73% isolated yield. Methanolysis of 2 ( M n = 8600) gave only a trace amount of methyl 3-hydroxybutyrate ( 5 ) which resulted from neighbor…
Consecutive vaporization cycles for the preparation of heterogeneous catalysts: Active Cu- and ZnO-containing methanol-synthesis catalysts were obtained by vaporizing suitable organometallic precursors into mesoporous silicates, followed by thermal treatment (see scheme). The catalytically active components in the fin…
Abstract Hyperbranched aromatic and aliphatic poly(urea‐urethane)s were prepared by the one‐pot method using 2,4‐toluylene diisocyanate (TDI), isophorone diisocyanate, and 2(3‐isocyanatopropyl)cyclohexyl isocyanate as AA* monomers and diethanol amine and diisopropanol amine as B 2 B* monomers. The characteristics of t…
The synthesis and multinuclear NMR characterization of mixed molybdenum-vanadium-tungsten polyoxometalates [P(2)Mo(x)V(y)W(18-(x+y))O(62)](n-) (x + y < or = 8) related to the Dawson structure are reported. The mixed species are obtained from the hexavacant anion [H(2)P(2)W(12)O(56)](12-) by successive condensation and…
Wheat gluten films were prepared by thermo-pressing, and their mechanical properties were compared to those of cast films. The stress-strain relationship was established for films with various amounts of glycerol. Both relationships were quite different, revealing a different network organization. Thermo-pressed films…