Materials Literature
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The effect of crystallinity on the photoreduction of cerium oxide (Ce 4+ to Ce 3+ ) during X-ray photoelectron spectroscopy (XPS) analysis of CeO 2 and Ce/Al 2 O 3 catalysts has been determined. Cerium oxide samples were prepared by calcining cerium(IV) methoxyethoxide in air at different temperatures. The structure o…
FT-IR spectroscopy, synchrotron SAXS, and dynamic rheometry have been employed to monitor, in-situ, structure development during the reactive processing of model flexible polyurethane foam systems. The following combinations of components were investigated: (I) diisocyanate, polyether polyol, and water and (II) diisoc…
The coordination chemistry of 2,2'-dipyridyl diselenide (PySeSePy) (2) (C(10)H(8)N(2)Se(2)) has been investigated and its crystal structure has been determined (monoclinic, P2(1)/c, a = 10.129(2) Å, b = 5.7332(12) Å, c = 19.173(3) Å, beta = 101.493(8) degrees, Z = 4). In metal complexes the ligand was found to coordin…
Unsymmetrical phthalocyanine analogues with three 15-crown-5 ether voids at the 3,4-positions (MtNIL, MtBZ, MtNAP) (Mt = Zn, Cu) have been synthesized and characterized. Their dimerization is induced by addition of some cations, particularly Rb 2+ and K + . Cofacial dimer formation in the presence of these cations pro…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSelf-Ordering of Diblock Copolymers from SolutionZ. Li, W. Zhao, Y. Liu, M. H. Rafailovich, J. Sokolov, K. Khougaz, A. Eisenberg, R. B. Lennox, and G. KrauschView Author Information Department of Materials Science and Engineering State University of New York at Stony B…
The electrochemical and chemical oxidation of the defect perovskite SrCoO 2.5 to the cubic perovskite SrCoO 3 at ambient temperature in alkaline electrolyte are shown to be reversible processes with the appearance of intermediate compounds; the phase diagram can be described by two line phases SrCoO 2.5 and SrCoO 2.75…
The aim of this study was to gain information on the influence of the core moiety on the kinetics of the synthesis of hyperbranched polyesters based on 2,2-bis(methylol)propionic acid (bis-MPA). Bis-MPA was esterified in the melt using sulfuric acid as a catalyst, yielding a highly polydisperse polyester. Bis-MPA was…
Electrically switchable volume holograms lead to the possiblity of real-time electro-optical control of diffractive optic components. We report here on the development of a novel photopolymer-liquid crystal composite material system for writing in a fast single step, high diffraction efficiency volume holograms, capab…
A short review of beneficial effects of nitrogen in steel is given including mechanical and corrosion properties, and the data of interatomic interactions and distribution of solute atoms in solid solutions are discussed with the aim of explanation of the physical nature of nitrogen steels. The concept is presented ac…
D. Gatteschi, A. Caneschi, R. Sessoli and A. Cornia, Chem. Soc. Rev., 1996, 25, 101 DOI: 10.1039/CS9962500101
Pulsed-gradient spin−echo (PGSE) 1 H NMR experiments were carried out on swollen poly( N, N -dimethylacrylamide) (PDMAA) gels with various degrees of swelling ( Q ) under a state of equilibrium with deuterated water (D 2 O) as solvent and poly(ethylene glycol) (PEG) as a probe polymer, of which the molecular weight ra…
Two activated carbons from different sources were oxidized with nitric acid and hydrogen peroxide and the effects of this on their porous structure and sorption of water and methanol were studied. The microstructural properties were derived from analysis of N 2 isotherms. The surface acidity was assessed using Boehm t…
Studies on the effect of the structural and compositional properties of layered double hydroxides (LDHs) and their decomposition products on the ethanolysis of propylene oxide to form glycol ethers are reported. The reaction, supported by results of indicator titrations, is used as a tool for elucidating the identity…
The kinetics of acetylene hydrogenation in the presence of a large excess of ethylene was studied in a laboratory flow reactor. Experiments were carried out using a Pd/α-Al 2 O 3 commercial catalyst and a simulated cracker gas mixture (H 2 /C 2 H 2 = 50; 60% C 2 H 4; 30% H 2, and traces of CO), at varying temperature…
The role of metal–metal bonding interactions is reviewed in the context not only of cluster chemistry, but also in linear gold(I) compounds. The latter, although much weaker than the former, can lead to interesting infinite and catenane structures which arise from supramolecular interactions.
4-Urazoylbenzoic acid groups are attached to the chain ends of polyisobutylene. The cooperative assembling process of these polar groups is studied by DSC and dielectric and dynamic mechanical spectroscopy. The melting of the ordered clusters occurs in the temperature range 380−390 K. Distortions within the U4A cluste…
The first observation of a ligand-driven light-induced spin-state change (LD-LISC effect) in a transition-metal complex is reported. The compounds under investigation are of the type Fe(II)L(4)X(2), where L is a cis/trans photoisomerizable ligand. For an iron(II) spin-state change to result from ligand cis <--> trans…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPolyhydroxybutyrate Synthase: Evidence for Covalent CatalysisJ. Wodzinska, K. D. Snell, A. Rhomberg, A. J. Sinskey, K. Biemann, and J. StubbeView Author Information Departments of Chemistry and Biology Massachusetts Institute of Technology Cambridge, Massachusetts 0213…
A new series of liquid-crystalline Schiff base lanthanide compounds of the general formula (L‘‘H) 2 L‘‘MX 2 was prepared (L‘‘H = H 2 n +1 C n OC 6 H 3 (OH)CHNC m H 2 m +1; n = 7, 12; m = 14, 18; M = La, Tb, Dy, Er, Nd, Ho, Eu, Pr, and Gd; X = NO 3 or Cl). The thermal behavior of these complexes was examined by polariz…
A thermodynamic model is given for phase separation induced by the increase of network elasticity during free-radical cross-linking polymerization. The importance of network elasticity in the field of polymer dispersed liquid crystals is stressed. The concept of a conversion−phase diagram is introduced as an attractiv…