Materials Literature
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The reaction between the propargyl radical (C 3 H 3 ) and NO has been investigated as a function of temperature (195−473 K) and pressure (3−100 Torr) by using color center laser infrared kinetic spectroscopy. At room temperature and below, the reaction rate was found to depend strongly on the helium buffer gas pressur…
The organized molecular structure of collagen is related to its dimensional stability. The dimensional stability of collagen arises from the interplay of various intermolecular forces such as covalent, hydrogen bonding, electrostatic interactions, hydrophobic interactions, London or van der Waals forces, and weak inte…
The grafting of hydroxy telechelic polybutadienes (HTPBD) by 2-mercaptoethanol to saturate 1,2-double bonds which enabled an increase of the OH functionality of HTPBD is presented. The functionalities of the virgin and grafted HTPBD were characterized both by 1H-NMR after silylation of the hydroxy end groups and the…
Perfluorinated polymer colloids with low refraction index are prepared via emulsion polymerization. The characterization is done using small-angle X-ray scattering and dynamic light scattering. The independently obtained particle size distributions are in remarkable mutual agreement and give evidence for the monodispe…
In an effort to design cyclic anhydride copolymers that have biodegradable characteristics and are derived from renewable resources, the copolymerization of itaconic anhydride and methacrylate-terminated poly-(L-lactic acid) (PLLA) was studied. Polymers with anhydride concentrations from 85 to 15 mol% have been synthe…
Sodium-covered silica films formed on silicon substrates are examined by X-ray photoemission spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (EXAFS) in ultrahigh vacuum conditions. The presence of sodium, which diffuses within the silica matrix at 300 K results in a shift of the O 1s core level tow…
Two grades of nuclear graphite, an isotropic graphite (GCMB) and an anisotropic graphite (PGA), were thermally oxidized to high weight losses. Average values of the coefficient of thermal expansion (CTE) in the temperature range 20-600 °C for GCMB and PGA in the parallel direction were unaffected by thermal oxidation…
A microcalorimetric method is proposed to determine the contact angle of a nonwetting liquid within a mesoporous solid. It is based on the simultaneous measurement of the heat and work of wetting, as the pressure is raised. The method simply requires a previous determination of the surface area to be wetted. It allows…
Hydroxy telechelic poly( l -lactide)s of different molecular weight have been synthesized by controlled ring-opening polymerization using cyclic tin alkoxides. NMR analysis showed that the propagation proceeded through an insertion mechanism. No free hydroxyl or carboxyl end groups were detected in the polymerization…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCatalyzed Growth of a Metastable InS Crystal Structure as Colloidal CrystalsJennifer A. Hollingsworth, Damadora M. Poojary, Abraham Clearfield, and William E. BuhroView Author Information Department of Chemistry, Washington University St. Louis, Missouri 63130-4899 Sym…
Dehydrogenation of ethylbenzene to styrene under excess carbon dioxide flow was carried out over activated carbon-supported metal oxide catalysts (Cr, Mn, Co, Ni, Mo, Ru, La, and Ce) at 823 K and W / F = 35 g of catalyst·h/mol. The highest yield of styrene (about 40%) with selectivity of above 80% was obtained using a…
Luminescence sensitivity changes in natural quartz induced by high temperature annealing: a high frequency EPR and OSL study, N R J Poolton, G M Smith, P C Riedi, E Bulur, L Bøtter-Jensen, A S Murray, M Adrian
Four different forms of jute fibers, namely untreated jute filament (UJF), sliver jute filament (SJF), bleached jute filament (BJF), and mercerized jute filament (MJF), have been subjected to tensile strength analysis following Weibull's theory. The MJF and BJF were obtained by the chemical modification of the UJF. A…
The time-evolution of a three-dimensional (3D), bicontinuous interface of a phase-separated polymer mixture in the late stage spinodal decomposition (SD) process has been studied by laser scanning confocal microscopy (LSCM) and time-resolved light scattering. The time evolution of the interface between two coexisting…
Results are presented of friction and wear measurements during diamond polishing using new instrumentation designed and built in our laboratory. The wear rates are found to be highly anisotropic, depending both on the crystallographic plane and on the direction along which sliding occurs. Friction measurements perform…
Two enantiomeric triblock ABA copolymers composed of poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) (PLLA–PEG–PLLA) and poly(D-lactide)–poly(ethylene glycol)–poly(D-lactide) (PDLA–PEG–PDLA) were synthesized with two different middle-block PEG chain lengths by ring-opening polymerization of L-lactide and D-lacti…
Chemical modification of cellulose powder is performed by successive reactions with acrylonitrile in an alkaline medium followed by aqueous hydroxylamine to prepare amidoximated cellulose. Due to complexation, the amidoxime groups immobilize heavy cations from buffered solutions at various pH values. The capacity of a…
The glass transition temperature ( T g ) in the thin poly(α-methyl styrene) and polysufone films that are coated on the surface of a Si wafer is investigated in this paper. A novel equation was suggested to estimate the thickness dependence of T g in thin films. Ellipsometry has been used to measure T g of various thi…
Higher generations of poly(propylene imine) dendrimers functionalized with aliphatic chains form large micrometer-sized spherical objects in aqueous solution below pH 8. These spheres are giant vesicles with a multilaminar onion-like structure. The size distribution and the structure of the vesicles depend on the pH o…
The charge density distribution of a protein has been refined experimentally. Diffraction data for a crambin crystal were measured to ultra-high resolution (0.54 A) at low temperature by using short-wavelength synchrotron radiation. The crystal structure was refined with a model for charged, nonspherical, multipolar a…