Materials Literature
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Poly(butylene terephthalate) (PBT) was depolymerized in refluxing o -dichlorobenzene using stannoxane catalysts to produce good yields of cyclic oligomers. We have studied how the ring size distribution varies as a function of the starting concentration of monomer units. Over a concentration range of 0.05 to 0.2 M, th…
Kinetics and mechanism for the bimolecular decomposition of HONO have been studied by ab initio molecular orbital (G2M) and transition-state theory calculations. The reaction can take place by the interaction of a cis and a trans isomer or two cis or two trans isomers, via four-, five-, and six-member ring transition…
The dynamics of micrometer-size polystyrene latex particles confined in thinning foam films was investigated by microscopic interferometric observation. The behavior of the entrapped particles depends on the mobility of the film surfaces, the particle concentration, hydrophobicity, and rate of film formation. When the…
Ch 1 - Historical Introduction. Ch 2 - Radioactivity. Ch 3 - The Discovery of the nucleus. Ch 4 - Particle accelerators and neutron sources. Ch 5 - Particle detectors. Ch 6 - Basic Forces. Ch 7 - The Leptons. Ch 8 - The Hadrons. Ch 9 - The Quarks. Ch 10 - Laws of Invasriance. Ch 11 - Boson Field Theory and Phenomenolo…
Maricite and sodium iron hydroxyphosphate (SIHP) are recently discovered iron(II) and iron(III) compounds that play a major role in phosphate “hideout” and corrosion in high-pressure boilers. This paper reports a novel method for synthesizing maricite by thermally decomposing the complex of aqueous iron(III) nitrilotr…
The catalytic mechanism of glucose 6-phosphate dehydrogenase from Leuconostoc mesenteroides was investigated by replacing three amino acids, His-240, Asp-177, and His 178, with asparagine, using site-directed mutagenesis. Each of the mutant enzymes was purified to homogeneity and characterized by substrate binding stu…
Linear optical and SHG coefficients of a number of “push−pull” porphyrins are analyzed using the semiempirical INDO/S Hamiltonian and singles-only CI. The NLO response properties are computed at a nonresonant excitation energy of 0.1 eV using the correction vector formalism, and the calculations are carried out in bot…
We describe a technique for extracting topographic information using a scanning near-field microwave microscope. By monitoring the shift of the system's resonant frequency, we obtain quantitative topographic images of uniformly conducting metal surfaces. At a frequency of 9.572 GHz, our technique allows for a height d…
Three series of zeroth to second generation chiral dendrimers, 7 − 9, 10 − 12, and 13 − 15, were prepared by convergent methods using chiral, nonracemic AB 2 monomers 1, 2, and 3, respectively. Chiroptical data revealed a significant change in molar rotation per subunit ([Φ] D / n ) as dendrimer generation increased f…
A model based on the Cahn−Hilliard formalism is used to simulate structure formation in thermally quenched polymer solutions in the vicinity of a glass transition. Simulation results for the system poly(methyl methacrylate)/cyclohexanol are correlated with light scattering and microscopy measurements recently reported…
Unlike most simple, monomeric cobalt porphyrins, the cobalt tetramethylporphyrin identified in the title catalyzes the electroreduction of O 2 to H 2 O instead of H 2 O 2 . On graphite electrodes, coatings of the porphyrin prepared by irreversible adsorption from chloroform solutions catalyze the electroreduction of O…
A property, unique to the treelike structure of dendrimers, is predicted. We show that for ideal dendrimers, with a superimposed energy funnel descending from the periphery to the center, one should be able to control the preferred location of the excitation by monitoring the temperature relative to the energy funnel.…
Recent probing of H2O-D2O mixtures by various means (neutron deep-inelastic scattering, Raman absorption, electrical H+/D+ conductivity) revealed an unexpected dependence of the relevant physical quantities on the isotopic composition of the mixture. We show that these observation can find their physical rationale in…
Lanthanide and actinide sandwich complexes exhibit fundamental differences in their electronic structure which may be explained by taking into account the effects of shell structure, relativity and electron correlations (depicted schematically on the right). The results of recent theoretical as well as experimental in…
We present a numerical study of steady convection in a two-dimensional mushy layer during the directional solidification of a binary mixture. The calculations reveal the internal structure of strongly nonlinear states featuring upflow which has been focused into solid-free regions known as chimneys. The mushy layer is…
The unique properties of a new family of peroxocopper(II) complexes are discussed. They are stable at room temperature and contain the µ4-peroxo structural unit (right). Their synthesis, structure, and spectroscopic and magnetic properties are described.
Reaction of Nd(BH 4 ) 3 (THF) 3 with K 2 COT (COT = η-C 8 H 8 ) in tetrahydrofuran (THF) gave the first (cyclooctatetraene)lanthanide borohydride, (COT)Nd(BH 4 )(THF) 2 ( 1 ). By treatment with NHEt 3 BPh 4, 1 was transformed into [(COT)Nd(THF) 4 ][BPh 4 ] ( 3 ), a unique example of a (cyclooctatetraene)lanthanide cat…
Monte Carlo and molecular dynamics simulations of interlayer molecular structure in the one-, two-, and (hypothetical) three-layer hydrates of K-montmorillonite were performed concurrently in order to elucidate counterion speciation and water structure in the electrical double layer of this clay mineral. Calculated la…
The heat capacities of glassy and liquid toluene and ethylbenzene were measured with an adiabatic calorimeter. Both samples were doped with about 10% of benzene to suppress crystallization. The effects of the doping were corrected for by assuming the additivity of the heat capacities of toluene (or ethylbenzene) and b…
A monolayer of a phosphonated triarylamine adsorbed on nanocrystalline TiO2, ZrO2, or Al2O3 film deposited on conducting glass displays reversible electrochemical and electrochromic behavior although the redox potential of the electroactive molecules (0.80 V vs NHE) lies in the forbidden band of the semiconducting or…