Materials Literature
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Linstead macrocyclization of dinitrile 1 gave [octakis(dimethylamino)porphyrazinato]magnesium(II) 2 and the seco-porphyrazine 4 from adventitious oxidation. The structure of the latter has been unequivocally established by an X-ray crystallographic study. Alternatively, compound 4 was obtained in high yield from the m…
Recent experiments suggest that thermodynamically stable, bicontinuous microemulsions can be achieved in symmetric ternary blends of two homopolymers and a diblock copolymer by formulating alloys with compositions near mean-field isotropic Lifshitz points. We argue that practical application of this design criterion m…
The stress‐rupture behavior of plain‐weave CG‐Nicalon/enhanced SiC was studied in air at 950°C. It was found that this material exhibits delayed failure and that the lives of specimens subjected to constant stress levels of 80, 100, and 120 MPa were 21.6, 9.6, and 2.7 h, respectively. The strain histories of these tes…
Polymer blends have been widely studied for the property improvement of commercial polymers. Most polymer blends, however, present coarse and unstable phase morphologies and poor adhesion at the interface, which is due to their immiscibility. Such problems have often been overcome with the addition of a proper compati…
Polyaniline (PAN) and polypyrrole (PPY) were coated on pristine and acrylic acid graft copolymerized low-density polyethylene (LDPE) films and exposed to chloroauric acid solutions. The reduction of Au(III) ions in solution was followed using ultraviolet−visible absorption spectroscopy. The structures of the PAN and P…
A finite strain analysis is presented for the pressurized spherical cavity embedded in a Drucker-Prager medium. Material behavior is modeled by a nonassociated deformation theory which accounts for arbitrary strain-hardening. The governing equations of spherically symmetric response are reduced to a single differentia…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Dissociative Mechanism for Reactions of Nitric Oxide with Water Soluble Iron(III) PorphyrinsLeroy E. Laverman, Mikio Hoshino, and Peter C. FordView Author Information Department of Chemistry, University of California, Santa Barbara, California 93106, and Institute of…
A mathematical model was proposed for determining the crack growth rate of hydrogen-induced cracking (HIC) in steel plates exposed to a sour gas. The model assumes that the extension of an embedded circular crack results from accumulation of internal hydrogen pressure that produces a rise of the stress intensity facto…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPronounced Axial Thiolate Ligand Effect on the Reactivity of High-Valent Oxo−Iron Porphyrin IntermediateYasuteru Urano, Tsunehiko Higuchi, Masaaki Hirobe, and Tetsuo NaganoView Author Information Graduate School of Pharmaceutical Sciences The University of Tokyo 7-3-1…
Quantitative x-ray-diffraction measurements in a temperature range 88--325 K were performed on porosity-free nanocrystalline (nc) elemental Se samples with a hcp structure. The nc-Se samples with different grain sizes were synthesized by crystallizing a melt-quenched amorphous-Se solid. Thermal-expansion coefficients…
In the present communication we demonstrate the synthesis of a hybrid block copolymer based on the combination of a biopolymer (amylose) with a synthetic block (polystyrene). To obtain such materials, amino-functionalized polymers were modified with maltoheptaose moieties that serve as initiators for the enzymatic pol…
Density functional calculations have been carried out on free-base porphyrin ( 1 ) and its seven possible isomers ( 2 − 8 ) with an N 4 -metal coordination core. A total of 27 structures resulting from geometrical isomerism (( E / Z )-configurations) and NH tautomerism were studied. Geometries were fully optimized wit…
Collagens contain a high amount of charged residues involved in triple-helix stability, fibril formation, and ligand binding. The contribution of charged residues to stability was analyzed utilizing a host-guest peptide system with a single Gly-X-Y triplet embedded within Ac(Gly-Pro-Hyp)3-Gly-X-Y-(Gly-Pro-Hyp)4-Gly-Gl…
Water present in a ligand binding site of a protein has been recognized to play a major role in ligand-protein interactions. To date, rational drug design techniques do not usually incorporate the effect of these water molecules into the design strategy. This work represents a new strategy for including water molecule…
A new method for analysing antiphase domains using high-resolution electron micrographs is described. A high-resolution electron microscope image taken at a zone axis is treated as the sum of many sets of interference fringes. The analysis extracts the information concerning the variations in the image periodicities a…
Ba 1− x Sr x TiO 3 (BST, x = 0 to x = 1) ferroelectric ceramics doped with 1.0 mol% MgO and 0.05 mol% MnO 2 were prepared with a rate‐controlled sintering profile. As the strontium molar fraction x increased, the average grain size decreased from 14 μm for x = 0 to 2 μm for x = 1. Temperature dependence of the dielect…
ABSTRACT Autolysis kinetics in axenic cultures of the diatom Ditylum brightwellii (West) Grunow were studied under nutrient limitation in continuous cultures and under nutrient starvation in batch‐mode cultures obtained by switching off nutrient supply in the continuous cultures. Under N limitation, the specific algal…
Außerordentlich wirksame kooperative Effekte bei der Bildung chiraler Stapel von C 3 ‐symmetrischen Molekülen in Alkanen als Lösungsmitteln wurden beobachtet (Bild rechts). Das „Sergeants‐and‐Soldiers”︁‐Prinzip sowie auch chirale Solvatation führen zur Ausbildung eines bevorzugten helicalen Drehsinns in den Säulenaggr…
The structure of poly (ε-caprolactam) (nylon 6) in the β mesomorphic form is here examined. The comparison of the diffraction intensity, calculated on modeled structures, with the experimental profiles, collected by us through an automatic diffractometer, is presented. This analysis has put into evidence the following…
Abstract Free radical polymerization of methyl methacrylate (MMA) within the uniform channels of the mesoporous zeolite MCM‐41 proceeds at 100°C to give a high molecular weight polymer (PMMA). The formation of long‐living propagating polymer‐radicals is observed by electron paramagnetic resonance (EPR). The molecular…