Materials Literature
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The structure of Brønsted acid sites and the effects of the Al → Si and Si → P substitution in chabazite and AlPO 4 -34 frameworks, respectively, have been studied by ab initio plane-wave calculations on periodic models. Geometry distortions remain well localized to the nearest neighborhood of the Brønsted acid site.…
We present x-ray photoemission spectra of the vanadium oxides , and , and their analysis in terms of a simple cluster model based on the Anderson impurity Hamiltonian. The electronic structure of these materials is characterized by a strong V 3d-O 2p hybridization energy which exceeds the energy scales related to on-s…
We argue that to explain recent resonant tunneling experiments on crystals of ${\mathrm{Mn}}_{12}$ and ${\mathrm{Fe}}_{8}$, particularly in the low-T limit, one must invoke dynamic nuclear spin and dipolar interactions. The low- $T$, short-time relaxation will then have a $\sqrt{t/\ensuremath{\tau}}$ form, where $\ens…
Blends of poly(ether imide) (PEI, Ultem 1000) and an aromatic poly(ether amide) were studied. Although homogeneous or heterogeneous blends can be obtained depending on the blend preparation method, the inherent miscibility of the mixture was finally established. The so-called enthalpy relaxation method was used to det…
The self-assembly of ionically end-capped, symmetric polystyrene-polyisoprene diblock copolymers (PS-b-PI) has been studied. Structural data obtained from small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were correlated with the aggregation behavior of charged chain ends as evidenced by a…
The solid solutions of the Al 2 (WO 4 ) 3 −Sc 2 (WO 4 ) 3 −Lu 2 (WO 4 ) 3 series which hold the Sc 2 (WO 4 ) 3 -type structure were prepared and their ionic conducting characteristics were investigated. The maximum electrical conductivity was obtained for the solid solution of (Al 2 (WO 4 ) 3 ) 0.1 −((Sc 0.5 Lu 0.5 )…
Sso7d from the thermoacidophilic archaebacterium Sulfolobus solfataricus is a small globular protein with a known three-dimensional structure. Inspection of the structure reveals that Phe31 is a member of the aromatic cluster forming the protein hydrophobic core, whereas Trp23 is located on the protein surface and its…
Composite foam plates were prepared by baking a mixture of granular starch and aqueous poly(vinyl alcohol) (PVOH) solution inside a hot mold. Foam strength, flexibility, and water resistance were markedly improved by addition of 10–30% PVOH to starch batters. The improvement in strength at low humidity was greater for…
The mechanical properties of composites consisting of high-density polyethylene (HDPE) and oil palm fibrous wastes—that is, empty fruit bunch (EFB)—have been investigated. Tensile modulus showed an increase, whereas tensile strength, elongation at break, and impact strength decreased with increasing filler loading. Th…
Woodflour of Eucaliptus saligna with two different chemical treatments (mercerization and esterification with maleic anhydride) was used as filler of an unsaturated polyester matrix. Woodflour was treated to increase the interfacial adhesion with the matrix, to improve the dispersion of the particles, and to decrease…
We consider planar brushes formed by end-grafted polymers with moderate to strong excluded-volume interactions. We first rederive the mean-field theory and solve the resulting self-consistent equations numerically. In the continuum limit, the results depend sensitively on a single parameter, beta, whose square is the…
The effectiveness of alumina-supported noble metal catalysts for the destructive oxidation of organic pollutants in effluent from a softwood kraft pulp mill was evaluated in a slurry reactor at 463 K and an oxygen pressure of 1.5 MPa. The effects of catalyst preparation procedures, such as metal loading, calcination,…
A kinetic model has been developed for the heterogeneously catalyzed methacrolein oxidation, the parameters of which reflect the redox and adsorptive properties of the heteropolyacid catalysts Cs x H 3 - x + y [PMo 12 - y V y O 40 ] ( x = 0, y = 0, 1; x = 1, y = 0, 1, 2). The model based on the Mars−van Krevelen mecha…
The synthesis of host−guest composites consisting of entrapped strands of poly(methylmethacrylate) (PMMA) within the pores of inorganic hosts is described. Methyl methacrylate was adsorbed into microporous hosts including zeolite NaY, mordenite, beta, and ZSM-5 and then polymerized. Adsorption and polymerization was a…
Geometrical arrangements of minimum energy of a system of identical repelling particles in two dimensions are studied for different forms of the interaction potential. Stability conditions for the triangular structure are derived, and some potentials not satisfying them are discussed. It is shown that in addition to t…
The molecularly dispersed TiO 2 /SiO 2 supported oxides were prepared by the incipient wetness impregnation of 2-propanol solutions of titanium isopropoxide. Experimental monolayer dispersion of surface titanium oxide species on SiO 2 was reached at ∼4 Ti atoms/nm 2 with a two-step impregnation procedure. The surface…
The tetrachlorocuprate(II) ion can crystallize in two different structures with the piperazinium dication (pipzH(2)). Both structures contain discrete CuCl(4)(2-) species. A yellow compound (pipzH(2))[CuCl(4)].2H(2)O (1) is monoclinic (C2/c, Z = 4, a = 10.538(3) Å, b = 7.4312(5) Å, c = 17.281(4) Å, beta = 111.900(10)…
The significance of drop-fluid viscosity on the effective rheological properties and on the dynamics of the microstructure of mono-disperse suspensions of two-dimensional liquid drops with constant interfacial tension is investigated by means of numerical simulations at vanishing Reynolds number, using the boundary in…
Hydrolysis of N-succinyl-L,L-diaminopimelic acid by the dapE-encoded desuccinylase is required for the bacterial synthesis of lysine and meso-diaminopimelic acid. We have investigated the catalytic mechanism of the recombinant enzyme from Haemophilus influenzae. The desuccinylase was overexpressed in Escherichia coli…
The collapse of polymer chains in a good solvent due to the presence of small colloidal spheres, taken to model inert globular proteins, is discussed. It is argued that the large-scale properties of the chains in the mixture are adequately described using Edwards' type (δ function) interactions between all constituent…