Materials Literature
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Cryogenic mechanical alloying is used to incorporate a poly(methyl methacrylate- b -isoprene) (MI) diblock copolymer into blends of poly(methyl methacrylate) (PMMA) and polyisoprene (PI). Mechanical milling of the copolymer promotes a reduction in the molar mass of the M block, as discerned from glass transition tempe…
The mechanism of orotidine 5'-monophosphate decarboxylase (OMP decarboxylase, ODCase) was studied using the decarboxylation of orotic acid analogues as a model system. The rate of decarboxylation of 1,3-dimethylorotic acid and its analogues as well as the stability of their corresponding carbanion intermediates was de…
The physical structure and chemical and mineralogical composition of Mazidagı (Turkey) phosphate rock have been investigated by using chemical analysis, X-ray powder diffraction, scanning electron microscopy (SEM), thermal analysis, mercury porosimetry, and BET surface area methods. The results of X-ray powder diffrac…
Flow reactor experiments were conducted to study carbon deposit formation from decomposition of a jet fuel (JP-8) at 500 °C and 500 psig for 5 h on the surface of two superalloys, Inconel 600 and Inconel X. The deposits collected on superalloy surfaces were characterized by temperature-programmed oxidation, size exclu…
The course of dispersion polymerization of aniline using ammonium peroxodisulfate (APS) as initiator oxidant and poly(vinyl alcohol) as stabilizer in different media, viz., water (1 M HCl), water (pH = 2.41, [aniline] ≡ [HCl]), and aqueous ethanol (1 M HCl), was followed spectrophotometrically. It was found that the a…
[reaction: see text] Benzyl aryl ether dendrimers containing photosensitive, veratryl-based o-nitrobenzyl AB linkages (bold bonds) were prepared to the third generation and shown to undergo site-specific degradation when irradiated with ultraviolet light.
We have investigated different models for parameterizing the frequency-dependent molecular polarizability. The parameterization is based on an electrostatic model for interacting atoms and includes atomic polarizabilities, atom-type parameters describing the damping of the electric fields and the frequency dependence.…
We reported the synthesis and characterization of peptide complexes of low-spin iron(III) [Fe(bpb)(py)2][ClO4] (1) and Na[Fe(bpb)(CN)2] (2) [H2bpb = 1,2-bis(pyridine-2-carboxamido)benzene; py = pyridine], where iron is coordinated to four nitrogen donors in the equatorial plane with two amide nitrogen anions and two p…
Forward recoil spectrometry (FRES) has been used to monitor the extent of reaction between model end-functional polymers at a PS/PMMA interface. Bilayer samples comprising a high molecular weight polystyrene layer containing ∼8.5 wt % of amino-terminal deuterated polystyrene (dPS-NH 2 ) on an anhydride-terminal poly(m…
The photophysical properties of a series of laser−dye-labeled poly(aryl ether) dendrimers, generations 1−4, have been determined. The dendrimers act as extremely efficient light-harvesting antennae capable of transferring light energy through space from their periphery to their core. The light-harvesting ability of th…
We report on the encapsulation of enzyme (catalase) by the controlled polymer multilayer coating of biocrystals, achieved by the sequential adsorption of oppositely charged polyelectrolytes onto enzyme crystal templates. An extremely high enzyme loading in each polymer capsule is obtained, and the activity of the enca…
Molecular dynamics is used to analyze the motions of backbone and lateral groups that lead to the formation and dissociation of excimer-forming conformations in methylphenylsiloxane. Several structures are studied: two fragments of linear poly(methylphenylsiloxane) with 14 (P14) and six (P6) monomer units, the cyclic…
In the reports “Hydrogen storage in single-walled carbon nanotubes at room temperature” by C. Lui et al. (5 Nov., p. [1127][1]) and “High H2 uptake by alkali-doped carbon nanotubes under ambient pressure and moderate temperatures” by P. Chen et al. (2 July, p. [91][2]), the authors make the
The syntheses of the vinyloxycyclotriphosphazene derivatives N3P3X5OCH=CH2 (X = OMe, OCH2CF3) and the N3P3(NMe2)4(OCH=CH2)2 isomeric mixture along with improved preparations of N3P3X5OCH=CH2 (X = F, NMe2) are reported. The interactions between the vinyloxy function and the cyclophosphazene in these and the previously…
Measurements of craze stresses and impact strengths have been performed on specially designed polyestercarbonates with 1,4-cyclohexylene linkages synthesized in our laboratory. The copolymers became more craze resistant as the cyclohexylene content was increased. On the other hand, the activation volumes of these copo…
Concentrations of Al3+ were calculated in soil solutions from concentrations of the monomeric ‘reactive Al’ species ([Al3+] + [Al(OH)2+] + [Al(OH)2+] + [AlF2+]) obtained using a recently reported flow injection analysis (FIA) chelating resin technique. Soil solution samples came from 7 sites encompassing a range of Ne…
Summary The presence of formaldehyde ( 4 ) in solutions of cellulose in N -methylmorpholine- N -oxide (NMMO, 1 ) has been shown by trapping formaldehyde as dimedone adduct 8 in a two-phase system. o -Dichlorobenzene was used as an inert solvent to extract the trapping product as soon as it had formed. Morpholine is a…
Bis(2,2'-bipyridyl)(dioctadecyl-2-[2,2‘-dipyridylmethylene] malonate) ruthenium(II) dihexafluorophosphate has been synthesized and was converted to an amphiphilic distearyl ester, 2b . Light-induced charge transfer from ruthenium to the pyridyl ligands occurred preferably to the malonate-type ligand. Its reduction pot…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTGrafting Rates of Amine-Functionalized Polystyrenes onto Epoxidized Silica SurfacesL. S. Penn, T. F. Hunter, Y. Lee, and R. P. QuirkView Author Information Department of Chemical and Materials Engineering, University of Kentucky, Le…
Four dyes (2-DASPI, 4-DASPI, LDS698, and LDS722) derived from the stilbazolium skeleton have been intercalated into optically transparent Na−fluorine mica layers. X-ray diffraction data show that the long axis of DASPI dyes is aligned parallel to the layer, largely maintaining their solution phase structure. On the ot…