Materials Literature
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A new variation of poly(ortho ester)s prepared by the addition of diols to the diketene acetal 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane is described. In this variation, a short segment of a glycolic acid dimer is built into the polymer backbone. Such a material does not require the addition of acidic excip…
Abstract The clay fraction of a Spodosol and its parent rock in the Apennine mountains of central Italy were studied by powder X-raydiffraction (XRD) and infrared (IR) spectroscopy, to evaluate the possibility of transformation of chlorite into low-charge expandable minerals. Results indicated that the main phyllosili…
Abstract The melting behavior and the isothermal crystallization kinetics of linear and randomly branched poly(butylene terephthalate) System. name: poly(tetramethylene terephthalate). (PBT) samples were investigated by differential scanning calorimetry. The multiple endotherms typical of linear PBT were observed also…
Other| February 01, 1997 Determination of the content and distribution of fixed ammonium in illite-smectite by X-ray diffraction: Application to North Sea illite-smectite Victor A. Drits; Victor A. Drits Russian Academy of Sciences, Institute of Geology, Moscow, Russian Federation Search for other works by this author…
The problem of interaction of a drop with a solid boundary is formulated in the framework of a recently developed theory of the three-phase contact line motion and analyzed in the case of finite Bond and small capillary and Weber numbers. Evolution of the free-surface shape in a quasi-static regime of the drop spreadi…
A synthetic scheme was developed to prepare cationically polymerizable octafunctional monomers with silsesquioxane (T8) cores. Epoxy and 1-propenoxy functional groups were attached to the core by the hydrosilation of T with an appropriate precursor. The steric constraints and the requirements for the hydrosilation rea…
One-electron oxidation of nickel(II) 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrin ((CTPP)Ni II ) and nickel(II) 2-methyl-5,10,15,20-tetraaryl-2-aza-21-carbaporphyrin ((MeCTPP)Ni II ) resulted in formation of rare organonickel(III) derivatives. The half-wave potential for the first oxidation of (CTPP)Ni II and (MeCTPP)…
Crack profile measurements near the crack tip in the SEM were used to measure crack tip toughness of alumina as a function of grain size (average grain size 0.9–16 μm). For comparative tests, two crack configurations were included in the present study: straight cracks (CT specimen) loaded with an in situ device; and r…
We present two sets of rules for constructing quasiperiodic tilings that suggest a simpler structural model of quasicrystals and a more plausible explanation of why quasicrystals form. First, we show that quasiperiodic tilings can be constructed from a single prototile with matching rules which constrain the way that…
Spectroscopic evidence is presented to indicate that local screening effects are important in polymer mixtures. Essentially, a polymer segment has a locally higher concentration of like segments because of this factor. A simple modification to existing theories is presented to account for this local screening.
The effects of solid-state structures on the rate of enzymatic erosion for melt-crystallized films of bacterial poly(hydroxyalkanoic acids) (PHAs) have been studied at 37 °C and pH 7.4 in the aqueous solution of an extracellular PHB depolymerase from Alcaligenes faecalis . In this study, the following PHA homopolymer…
The metastable state silk I structures of Bombyx mori silk fibroin in the solid state were studied on the basis of 15N- and 13C-nmr chemical shifts of Ala, Ser, and Gly residues. The 15N cross-polarization magic angle spinning (CP/MAS) nmr spectra of the precipitated fraction after chymotrypsin hydrolysis of B. mori s…
In this study, the adsorption of single-stranded oligodeoxyribonucleotides (ODN) onto well-characterized polymer latex particles has been investigated. At first, the case of poly(thymidylic acid) (dT 35 ) was thoroughly examined as a function of pH and ionic strength in the presence of cationic polystyrene colloids pr…
Effective-medium theory is often helpful for understanding the behavior of subwavelength gratings with small period-to-wavelength ratios. By analytically solving Maxwell’s equations in the small-depth limit, we show that the effective properties of subwavelength gratings strongly depend on the grating depth. Moreover,…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTModel Systems for Flavoenzyme Activity. Modulation of Flavin Redox Potentials through π-Stacking InteractionsEric C. Breinlinger and Vincent M. RotelloView Author Information Department of Chemistry, University of Massachusetts Amherst, Massachusetts 01003 Cite this: J…
Polystyrene/polyisoprene (PS/PI) diblocks suspended in decane serve as a model system for the investigation of highly concentrated diblock copolymer solutions. Bulk melts of PS/PI with no solvent exhibit ordered morphologies including lamellae, close-packed cylinders, etc. that depend on the block asymmetry. These sam…
The paper presents a survey on the dielectric analysis of integrated ceramic capacitors. The thin film examples are based on high–permittivity paraelectric SrTiO3, solid–solution (Ba,Sr)TiO3, ferroelectric Pb(Zr,Ti)O3, and superparaelectric BaTiO3. The current state of knowledge concerning the temperature dependence,…
The metalloporphyrin-catalyzed oxidation of 2-methynaphthalene (1) by potassium monopersulfate produced mainly two naphthoquinones: 2-methyl-1,4-naphthoquinone (2) (menadione or vitamin K(3)) and 6-methyl-1,4-naphthoquinone (3). In aqueous solution and at room temperature in the presence of 5 mol % of the water-solubl…
The complexation of TTF 2 and cyclobis(paraquat- p -phenylene) 1 4+ has been studied by cyclic voltammetry and by spectroelectrochemistry: shifts in the redox potentials for the TTF and the 1 4+ components of 45 and 30 mV, respectively, occur upon complexation. Decomplexation of 2·1 4+ upon oxidation of the TTF unit t…
The preparation and catalytic properties of bimetallic colloids consisting of a ligand-stabilized Pt shell on Au or Pd cores supported by alumina are described. The aim of this work is to study the influence of the electronegativity of the colloidal core metals on the activity and selectivity of the surface Pt in hydr…