Materials Literature
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The thermal degradation of poly(methyl methacrylate) (PMMA) has been studied in both pure nitrogen and oxygen-containing atmospheres. The presence of oxygen increases the initial decomposition temperature by 70 °C. The stabilizing effect of oxygen may be explained by forming thermally stable radical species that suppr…
Time-resolved small-angle x-ray scattering was used to measure the radius of gyration of cytochrome c after initiation of folding by a pH jump. Submillisecond time resolution was obtained with a microfabricated diffusional mixer and synchrotron radiation. The results show that the protein first collapses to compact de…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTZinc Phosphate with Gigantic Pores of 24 TetrahedraGuo-Yu Yang and Slavi C. SevovView Author Information Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, Indiana 46556 Cite this: J. Am. Chem. Soc. 1999, 121, 36, 8389–8390Publication Date (…
A method for synthesizing hollow nanoscopic polypyrrole and poly( N -methylpyrrole) capsules is described. The method employs gold nanoparticles as templates for polymer nucleation and growth. Etching the gold leaves a structurally intact hollow polymer capsule with a shell thickness governed by polymerization time (c…
Vanadium oxide nanotubes were obtained as the main product in a sol−gel reaction followed by hydrothermal treatment from vanadium(V) alkoxide precursors and primary amines (C n H 2 n +1 NH 2 with 4 ≤ n ≤ 22) or α,ω-diamines (H 2 N[CH 2 ] n NH 2 with 14 ≤ n ≤ 20). The structure of the nanotubes has been characterized b…
We report that the submerged microbubbles are an efficient source of diffuse radiance and may contribute to a rapid transition to the diffuse asymptotic regime. In this asymptotic regime an average cosine is easily predictable and measurable.
We describe a new mechanism for the nucleation of carbon nanotubes which does not require an abrupt transition from pentagonal ring formation to exclusively hexagon formation. This mechanism, the spontaneous opening of double-layered graphitic patches, is quantitatively consistent with the recently discovered temperat…
Chiral bidentate ferrocenyl ligands have been ned-tuned in terms of their steric and electronic properties, and thus adapted to a variety of reactions catalyzed by transition metals. The position of the two ligating units (two different PR 2 groups, two pyrazolyl, or a combination thereof) attached to the ferrocenylet…
A procedure is introduced for deriving a coarse-grained dissipative particle dynamics from molecular dynamics. The rules of the dissipative particle dynamics are derived from the underlying molecular interactions, and a Langevin equation is obtained that describes the forces experienced by the dissipative particles an…
Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWN…
A series of [net-polystyrene]-ipn-[net-poly(methyl acrylate)] systems with gradients of poly(methyl acrylate) in a polystyrene matrix are prepared and tested mechanically. The results showed no distinct differences from that of corresponding interpenetrating polymer network (IPN) samples with similar compositions, in…
Kapton film, poly[(N,N′-oxydiphenylene)pyromellitimide], was modified by silane-coupling reactions using 3′(trimethoxysilyl)propoxy-2-hydroxypro-pyl-1,3-diazole (Si–imidazole) to improve the adhesion with copper metal. The Kapton film surface was first treated with argon plasma for 30 s, then dipped into a methanol so…
New Sm(III) μ-halo-bis(trimethylsilyl)amido complexes [Sm(μ-X) {N(SiMe3)2}2(THF)]2 (X = Cl, Br) were synthesized and their crystal structures were analyzed. These complexes were used as catalysts for the homopolymerization of ε-caprolactone and δ-valerolactone and found to initiate ring-opening polymerization (ROP) of…
A remelting–restabilization technique was applied for the recycling of postused, yellow-pigmented high-density polyethylene (HDPE) bottle crates. Multiple extrusion cycles procedure, at different reprocessing temperatures, was performed for monitoring the processing stability of the restabilized and nonrestabilized ma…
Wetting behavior of perfluoroalkylethyl acrylate (FA)/n-alkyl acrylate (AA) copolymers with the various length of side chains of the AAs is discussed from a standpoint of surface molecular mobility. The copolymerization reactivity ratio indicates that these polymers are random copolymers. The surface properties were s…
A microscopic theory for the NMR anomalies of the planar Cu and O sites in superconducting La_1.85Sr_0.15CuO_4 is presented that quantitatively explains the observations without the need to invoke anit-ferromagnetic spin fluctuations on the planar Cu sites and its significant discrepancy with the observed incommensura…
We have studied an anomalous microwave (mw) response of superconducting YBa_{2}Cu_{3}O_{7-delta} (YBCO) microstrip resonators in the presence of a weak dc magnetic field, H_{dc}. The surface resistance (R_{s}) and reactance (X_{s}) show a correlated non-monotonic behaviour as a function of H_{dc}. R_{s} and X_{s} were…
The selection and modification of atoms or functional groups underly many of the manipulations central to molecular modeling. It has become even more important to automate these tasks with the current prevalence of work with large databases of molecules. We have devised SUPER-SMILES, a conceptually simple set of exten…
Heat-induced interfacial aggregation of a whey protein isolate (WPI), previously adsorbed at the oil-water interface, was studied by interfacial dynamic characteristics coupled with microscopic observation and image analysis of the drop after heat treatment. The experiments were carried out at temperatures ranging fro…
Elemental sulfur exists in many crystalline forms, with many of these forms being composed of discrete S n cyclic molecules. Eleven experimentally determined S n crystal structures are used to define a new spherical S···S intermolecular force field of the (exp-6) type. Evidence is presented that the bonded sulfur atom…