Materials Literature
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The evolution of tetragonality with thickness has been probed in epitaxial c-axis oriented PbTiO3 films with thicknesses ranging from 500 down to 24 A. High resolution x ray pointed out a systematic decrease of the c-axis lattice parameter with decreasing film thickness below 200 A. Using a first-principles model Hami…
The effect of nanoconfinement on the glass transition temperature ( T g ) of supported polystyrene (PS) films is investigated over a broad molecular weight (MW) range of 5000−3 000 000 g/mol. Polystyrene MW is shown to have no significant impact on the film thickness dependence of T g − T g,bulk . In contrast, a small…
A method, pseudo steady-state titration, is introduced for determining the precipitation pH of nanocrystals coated by electron-donating ligands. CdSe nanocrystals coated with hydrophilic deprotonated thiol (thiolate) ligands were studied systematically. For comparison, CdTe and CdS nanocrystals coated with the same ty…
The nature of the “peculiarly strong” interaction between the poly( l -lactide) (PLLA) and poly( d -lactide) (PDLA) chains was investigated by real time infrared spectroscopy during the isothermal melt crystallization process of the PLLA/PDLA stereocomplex. A very small low-frequency shift (about 1 cm -1 ) of ν as (CH…
A novel aqueous solution method has been developed for growing well-aligned crystalline ZnO nanorods (NRs) and nanotubes (NTs) on a variety of substrates including Si wafers, poly(ethylene terephthalate) (PET), and sapphire. Atomic layer deposition (ALD) was first used to grow a uniform ZnO film on the substrate of ch…
Abstract Thermal transitions in epoxy networks prepared by reaction of α, ω‐diamino terminated poly(propylene oxide)‐ block ‐poly(ethylene oxide)‐ block ‐poly(propylene oxide) and diglycidyl ether of brominated Bisphenol A, swollen in water, were studied by differential scanning calorimetry (DSC) in a broad temperatur…
We measured the velocity of the flux front of an artificially nucleated dendritic instability in Y Ni 2 B 2 C. The required time resolution in the nanosecond regime was achieved by our magneto-optic pump–probe technique, utilizing a femtosecond laser system. The penetration velocity of the flux front is on the order o…
Abstract One of the most effective methods used in oilfield operations to prevent or limit scale formation is the use of precipitation squeeze treatments. A fundamental understanding of scale inhibitor precipitation is important in designing squeeze treatments in oilfield. Diethylentrilopentrakis (methylenephosphonic…
Abstract Conventional testing of scale inhibitors (SI) usually focuses only on the inhibition of bulk depositional processes, e.g. in jar tests of inhibition efficiency. In previous work, we have extended the study of inhibition efficiency to examine both bulk and surface depositional processes and their inhibition us…
Spin states of the iron(III) complexes of porphyrin, porphycene, hemiporphycene, and corrphycene bearing both 1-methylimidazole and azide as axial ligands were analyzed with infrared (IR) spectroscopy at 20 degrees C. The IR stretching band of coordinating azide split into two peaks around 2047 and 2017 cm(-1) reflect…
Abstract A potassium salt of N ‐chloroacetyl‐11‐aminoundecanoate was thermally polymerized to obtain the corresponding poly(glycolic acid‐ alt ‐11‐aminoundecanoic acid). A kinetic study was then performed that was based on isothermal and nonisothermal polymerizations performed in a differential scanning calorimeter. T…
Abstract The formation of mineral scale (carbonate/sulphate/sulphide) within the near well bore; production tubing and topside process equipment has presented a challenge to the oil and gas industry for over 50 years. Chemical methods to control scale have been developed including scale squeeze treatments and continua…
In this work we have investigated the electronic structure and the molecular orientation of (t-Bu)(4)PcMg (tetra-t-butyl magnesium phthalocyanine) on polycrystalline and single crystalline gold substrates using photoemission spectroscopy and x-ray absorption spectroscopy, and we compare the results to the unsubstitute…
A system's temperature can be expressed in terms of its constituents' instantaneous positions rather than their momenta. Such configurational temperature definitions offer substantial benefits for experimental studies of soft condensed matter systems, most notably their applicability to overdamped systems whose instan…
Photoinduced electron-transfer processes from the excited triplet states of zinc tetraphenylporphyrin (3ZnTPP*) or zinc tetra-tert-butylphthalocyanine (3ZnTBPc*) to oxo-acetato-bridged triruthenium clusters [Ru3(mu3-O)(mu-CH3CO2)6(L)3]+ have been confirmed by nanosecond laser flash photolysis in the visible and near-I…
Abstract Scale and corrosion continue to be serious and costly problems in oil and gas production facilities. Production engineers rely upon computer programs to predict the severity and location of scale deposition and corrosion. The core of these computer programs are algorithms to correlate a set of theoretically d…
The structure of an ordered, ultrathin theta-Al(2)O(3) film grown on a NiAl(100) single-crystal surface was studied by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and low-energy electron diffraction (LEED), and its interaction with water was investigated with temperature programmed desor…
Semicrystalline polymer/layered silicate nanocomposites exhibit a unique three-dimensional structure associated with the high-aspect ratio constituents (layered silicates and polymer crystallites), which is sensitive to shear and deformation history. Beginning from quenched biaxially extruded films of nylon-6/ montmor…
The first organically templated 3D borogermanate with a novel zeolite-type topology, (C4N3H15)[(BO2)2(GeO2)4] FJ-17, has been solvothermally synthesized and characterized by IR spectroscopy, powder X-ray diffraction (PXRD), TGA, and single-crystal X-ray diffraction. The compound crystallized in the monoclinic space gr…
One new conjugated symmetric fulvene ligand L1 and two new unsymmetric fulvene ligands L2 and L3 were synthesized. Five new supramolecular complexes, namely Ag2(L1)3(SO3CF3)3 (1) (1, monoclinic, P2(1)/c; a = 12.702(3) A, b = 26.118(7) A, c = 13.998(4) A, beta = 96.063(4) degrees, Z = 4), [Ag(L1)]ClO4 (2) (monoclinic,…