Materials Literature
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Adamantyl-terminated poly(propylene imine) dendrimers 1–5 were dissolved in water in the presence of β-cyclodextrin through strong non-covalent interaction between the β-cyclodextrin and adamantyl groups. The solubilization of the dendrimer by β-cyclodextrin is most effective at pH = 2, because at this pH there is com…
Poly(amic acid) was synthesized with a low-temperature solution polymerization of 3,3′-dihydroxybenzidine and pyromellitic dianhydride in N,N-dimethylacetamide. The cast films were thermally treated at various temperatures. The polyimide containing the hydroxyl group was rearranged by decarboxylation, resulting in a f…
Optically isotropic thin films (0.5 μm) of an amorphous side-chain copolymer containing 10% azobenzene moieties and 90% meso-azobenzene groups (K1-10 sample) were irradiated by two interfering orthogonal (±45°) or parallel (p + p) linearly polarized laser beams; permanent holographic diffraction gratings were thus ins…
The hydrothermal chemistry of the Ni(II)/molybdate/3,3′-bipyridine system exhibits pronounced pH dependence, such that under basic conditions a 2-D material with embedded clusters [{Ni(3,3′-bpy)2}2Mo4O14] 1 is observed, while under acidic conditions the 2-D bimetallic oxide network of [Ni(3,3′-Hbpy)Mo4O13(OH)] 2 is is…
Many concrete structures may be submitted to high rate dynamic loadings (impacts, explosions, etc.). So, it is necessary to know the behaviour of this material in order to predict the response of the structure. Under dynamic loading an increase of apparent compressive strength is observed. This may be due to a rheolog…
Polyimide (PI) materials with a low coefficient of thermal expansion (CTE) while still retaining high strength and toughness are desirable in various applications. In this study a sol–gel process was used to incorporate silica into homopolyimides and copolyimides with highly rigid structures in an attempt to pursue th…
Surface-enhanced Raman scattering (SERS) of hypoxanthine (HX) molecule on silver colloid confirms that the molecule in the surface adsorbed state exists as [keto–N9 H9] form at acidic and normal pH but as [enol–O6 H1, N9 H9] form at alkaline pH. It is substantiated by the appearance of an intense carbonyl stretching m…
In this study, the formulation and process parameters that determine successful production and long-term stability of freeze-dried poly(lactic acid) (PLA) nanoparticles with "hairy-like" poly(ethylene oxide) (PEO) surfaces were investigated. Nanoparticles with grafted (covalently bound) PEO coatings were produced by t…
The pathway of cysteine biosynthesis in archaea is still unexplored. Complementation of a cysteine auxotrophic Escherichia coli strain NK3 led to the isolation of the Methanosarcina barkeri cysK gene [encoding O-acetylserine (thiol)-lyase-A], which displays great similarity to bacterial cysK genes. Adjacent to cysK is…
Polyurea microcapsules were formed by carrying out an interfacial polycondensation reaction in emulsion globules between various diisocyanates and ethylenediamine to investigate the effects of the chemical structure on various characteristics. FTIR showed that very reactive aromatic 2,4-toulene diisocyanate produced m…
The behavior of sealed and unsealed porous aluminum oxide films during aging and autosealing‐aging in various media is studied. The quality of the anodic layers and the degree of sealing and aging are assessed. The results of electrochemical impedance spectroscopy are compared with those provided by standard quality c…
Zinc(II)-5,15-diarylporphyrins have been effectively polymerized to give poly(Zn(II)-porphyrinylene) in high yields in the reaction with 1.5 equiv. AgPF6 in CHCl3 either in the presence of 0.5% N,N-dimethylacetamide or upon heating.
A monolayer dispersion of copper oxide on the surface of anatase and its effect on the anatase properties have been studied by BET surface area measurements, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and X-ray diffraction (XRD). XPS results…
Iron-filled carbon nanostructures have been synthesized via a simple catalytic process, using Fe(CO)5 as the source of both iron and carbon. The iron-containing materials can be separated from the products using a permanent magnet. The nanotubes have dimensions of several hundred nanometers in length and 10–20 nm in w…
It has been proposed recently that the lowest level of dc field, above which electrical degradation may occur, is associated with the formation of space charges in insulation. Therefore, inference of field levels above which space charge accumulates in a given material may provide fundamental information for material…
A shrinking core model is presented for the galvanostatic discharge of a metal hydride particle. A quantitative criterion for when the shrinking core can be completely neglected or approximated by a pseudosteady‐state solution is presented. The effect of shrinking of the core on the discharge behavior of a metal hydri…
Two scanning electron microscope (SEM)-based diffraction techniques, i.e. electron channelling contrast imaging (ECCI) and electron back-scatter diffraction (EBSD) are used to study lattice defect and local elastic strain distributions in Si1-xGe(x) epilayers grown on Si substrates patterned with mesas. The ECCI techn…
Free-radical melt-grafting of the dual-monomer systems glycidyl methacrylate–styrene (GMA-St) and hydroxyethyl methacrylate–styrene (HEMA-St) onto polypropylene (PP) has been studied using a single-screw extruder. For single monomer grafting systems, degradation of PP was unavoidable and deterioration of the mechanica…
A new general model of the directional permeability in homogeneous, anisotropic nonwoven structures is presented. It is based on drag-force theory and D'Arcy's Law. Structural parameters in the fabric are considered, including fibre diameter, porosity, and the fibre-orientation distribution. The governing equations of…
Novel guanidine bases supported on silicas and Micelle Templated Silicas (MTS) have been prepared, and investigated in the base catalysed epoxidation of electron deficient alkenes with excellent conversions and selectivities both with respect to the alkene and the primary oxidant. They are also efficient catalysts for…