Materials Literature
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Abstract Six‐membered D,L‐, L,L‐ and D,D‐lactides were polymerized by lipase over a temperature range of 80 to 130 °C to yield the polylactide with a molecular weight ( M w ) of greater than 270000. Among the lipases tested, lipase PS gave the greatest molecular weight of polylactide. The polymerization of D,L‐lactide…
Abstract Amorphous Si 37 C 32 N 31 and Si 37 C 29 N 34 ceramics were produced by pyrolysis of a polyhy-dromethylsilazane precursor. Their structure was investigated by X-ray and neutron diffraction. Wide angle diffraction showed that the Si-atoms are preferentially bonded to nitrogen atoms, but also bonding to carbon…
We have studied antiferroelectricity in twin dimers, in which two mesogens with alkyl tails are linked by an alkylene spacer. Since the conformation of dimers is confined by the spacer, the use of the spacer with an odd carbon number forces the dimer to assume a bent conformation. If a segregation between the spacer a…
The acidic and catalytic properties of the medium pore molecular sieves SAPO-11 and SAPO-31 synthesized by two different routes [from aqueous and nonaqueous (ethylene glycol) media] are compared. Samples synthesized from the nonaqueous medium possess more acidity (due to higher substitution of P 5+ by Si 4+ and conseq…
ZnO additions to BaTiO 3 have been studied in order to determine the role of this dopant on sintering and microstructure development. As a consequence of a better initial dopant distribution, samples doped with 0.1 wt% zinc stearate show homogeneous fine‐grained microstructure, while a doping level of 0.5 wt% solid Zn…
Laser processing of diamond and chemical-vapor-deposited diamond thin films are important in the microelectronics and cutting tool industries because the manufacture of diamond films with low surface roughness and complex shapes has proven to be difficult. In this paper we present a review of current laser polishing a…
Other| April 01, 1998 Reversed determination of the reaction; phlogopite+quartz = enstatite+potassium feldspar+H 2 O in the ranges 750-875 degrees C and 2-12 kbar at low H 2 O activity with concentrated KCl solutions L. Ya. Aranovich; L. Ya. Aranovich University of Chicago, Department of the Geophysical Sciences, Chic…
The models used to describe zinc oxide‐based varistors rely on diffusion and defect data obtained using techniques that have been replaced by more modern methods such as secondary ion mass spectrometry. We report values for oxygen diffusivities in undoped, single‐crystal ZnO as a function of temperature and orientatio…
Bacteria that degrade an aliphatic polycarbonate, poly(hexamethylene carbonate), were isolated from river water in Ibaraki. Prefecture, Japan, after enrichment in liquid medium containing poly(hexamethylene carbonate) suspensions as carbon source, and dilution to single cells. Four of the strains, 35L, WFF52, 61A and…
Previously manufactured oxide dispersion strengthened (ODS) ferritic steel cladding tubes had inferior internal creep rupture strength in the circumferential hoop direction. This unexpected feature of ODS cladding tubes was substantially ascribed to the needle-like grain structure aligned with the forming direction. I…
A theoretical analysis of the experimental bulk modulus Ke of both binary tellurite and binary phosphate glasses containing transition metal oxides V2O5 or MoO3 with different percentages has been done. The main parameters in the analysis were the calculated bulk modulus Kbc and Poisson's ratio σbc. The calculations h…
Abstract The rapid phase quantification method using X-ray diffraction (XRD) with a position-sensitive detector (PSD), outlined by Cressey and Schofield (1996), has been extended to facilitate mineral phase quantification of clay-bearing samples. In addition, correction factors for differences in matrix absorption eff…
Zn−Al layered double hydroxides (LDHs) have been prepared with Cl - and CO 3 2 - interlayer anions and with Zn/Al ratios of 2 and 3. The corresponding polyoxovanadate-containing LDHs were then prepared by anion exchange reaction at different pH values. The products were characterized by atomic absorption, PXRD, FT-IR…
The vibrational spectra of a new type of phosphazene polymer, [NP(O2C12H8)]n (polyspirophosphazene), are discussed. The spectra were recorded for powders dispersed in KBr pellets and for films prepared from different solvents. The IR spectra are dominated by the vibrational modes of the main chain whereas the Raman sp…
Crystalline catalysts of orthorhombic MoO 3 have been prepared via a vapor phase deposition method, and their crystallographic structure has been affirmed by XRD and FTIR investigations. A chemical etching method has been developed for restructuring these thermally processed catalysts. Using a 0.1 M NaOH etchant, {001…
Two series of linear homo- and heterotrinuclear complexes, Mn III M II Mn III and Mn IV M II Mn IV, where M II represents Mn II ( 1 and 5), Ni II ( 2 and 6), Cu II ( 3 and 7), or Zn II ( 4 and 8), containing three dimethylglyoximato dianions (dmg 2 - ) as bridging ligands and 1,4,7-trimethyl-1,4,7-triazacyclononane (L…
Following the complete sequencing of the Escherichia coli genome, it has been shown that the proposed second citrate synthase of this organism, recently described by the authors, is in fact a 2-methylcitrate synthase that possesses citrate synthase activity as a minor component. Whereas the hexameric citrate synthase…
The piezoelectric shear strain S5 of several commercial lead zirconate titanate (PZT) piezoceramics was evaluated under the nonresonant condition in a sinusoidal ac-field E1(t) applied perpendicular to the poling direction. Results obtained on donor doped (soft PZT) and acceptor doped (hard PZT) ceramics are compared.…
Atomic-resolution transmission electron microscope (TEM) images reveal that IIbb (β = 97°) Mg,Al,Fe-chlorite from Koongarra, Australia, transforms to vermiculite via a range of intermediate chemical and structural states. Semi-quantitative analysis of contrast in atomic-resolution images of layer silicates with ∼1.4 n…
The encapsulation (decoration) of Rh nanoparticles supported on a TiO 2 (110) surface was studied by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). In the case of a stoichiometric and well-ordered TiO 2 (110)-(1 × 1) surface covered by 3 monolayers (ML) of rhodium, there is no indicati…