Materials Literature
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Abstract The high‐strength, high‐modulus Kevlar 49 fiber is widely used today because of its superior properties. In this paper, we discuss the fundamental physicochemical nature of the commercial fiber. It is an extended chain polymer, poly( p ‐phenylene terephthalamide), which is highly crystalline. Extensive analys…
Even though the average molecular direction in smectic A phases is perpendicular to the smectic planes, most molecules in these phases have rather large tilt angles because the orientational order parameter S in all smectic A phases is significantly less than unity. This molecular tilt inherent to all A phases account…
A three-sublattice analysis of ${M}^{2+}{{\mathrm{Fe}}_{2}}^{3+}{\mathrm{O}}_{4}$ ($M={{\mathrm{Li}}_{0.5}}^{+}{{\mathrm{Fe}}_{0.5}}^{3+}, {\mathrm{Mn}}^{2+}, {\mathrm{Fe}}^{2+}, {\mathrm{Co}}^{2+}, {\mathrm{Ni}}^{2+}, {\mathrm{Cu}}^{2+}$) spinel ferrites based on the molecular-field approximation has been used to obt…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRigid Backbone Polymers. 2. Polyisocyanates and Their Liquid-Crystal BehaviorShaul M. AharoniCite this: Macromolecules 1979, 12, 1, 94–103Publication Date (Print):January 1, 1979Publication History Published online1 May 2002Published inissue 1 January 1979https://doi.org/10.…
Abstract The reactive Al pool in selected Ultisols, Oxisols, and Histosols from Africa, South America, and North Carolina was estimated by extraction with 1 N CuCl 2 . The Al‐saturated clay minerals with and without interlayered hydroxy‐Al were used to compare the extractability of Al by 1 N CuCl 2 and 1 N KCl. The 1…
The two structural phase transitions in the perovskite layer structure compound (C10H21NH3)2CdCl4 at Tc1=35 °C and Tc2=39 °C have been studied by x‐ray diffractional, calorimetric and dielectric measurements, proton NMR spin–lattice relaxation and second moment investigations, 35Cl and 14N quadrupole resonance spectro…
I-Materials.- 1 Introduction.- 2 Styrenic Thermoplastic Elastomers.- 3 Thermoplastic Polyolefin Elastomers.- 4 Elastomeric Alloy Thermoplastic Vulcanizates.- 5 Single Phase Melt Processible Rubber.- 6 Copolyester Thermoplastic Elastomers.- 7 Thermoplastic Polyurethane Elastomers.- 8 Polyamide Thermoplastic Elastomers.…
OBJECTIVE: We introduce an RGD (Arg-Gly-Asp)-containing peptide of collagen IV origin that possesses potent cell adhesion and proliferation properties. MATERIALS AND METHODS: In this experimental study, the peptide was immobilized on an electrospun nanofibrous polycaprolactone/gelatin (PCL/Gel) hybrid scaffold by a ch…
The strength characteristics of annealed brittle surfaces impacted with sharp particles were studied. A theory of the degradation process is constructed in three steps: (1) A sharp particle delivers an impulsive load to the target surface via a plastic contact; (2) the contact loading initiates and propagates median c…
A system of rigid, inpenetrable, rodlike molecules subject to orientation-dependent mutual attractions is treated by extension of the theory presented in the preceding paper. This energy is formulated, for a system at constant volume, by considering interactions between pairs of segments in contact, rather than in ter…
The microscopic structure of the ${\mathrm{Fe}}^{3+}$-${V}_{\mathrm{O}}$ and ${\mathrm{Mn}}^{2+}$-${V}_{\mathrm{O}}$ pair centers has been considered using the Newman superposition model. This model yields the EPR parameter ${b}_{2}^{0}$ as a function of transition-metal-ion-oxygen distance $d$ and position. It is fou…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVanadium-catalyzed epoxidation of cyclic allylic alcohols. Stereoselectivity and stereocontrol mechanismTakashi Itoh, Koichiro Jitsukawa, Kiyotomi Kaneda, and Shiichiro TeranishiCite this: J. Am. Chem. Soc. 1979, 101, 1, 159–169Publication Date (Print):January 1, 1979Publica…
First published in 1979, this is a self-contained account of the theory of surface physics. In drawing together many results only previously reported in research papers, the authors emphasise basic disciplines such as electrodynamics and electron gas theory and demonstrate their application to simple models. Connectio…
Description Those in the fields of corrosion engineering and metallurgy will find that this publication offers and introduction for those unfamiliar to the slow strain-rate technique (SSRT) for stress corrosion cracking (SCC) in metals and relevant information the application of the technique for specific alloys of ch…
Biofilms can develop on almost any surface exposed to an aqueous environment. The biofilm systems that result can be used beneficially, as exemplified by fixed-film wastewater treatment processes (for example, trickling filters and rotating biological contactors). In addition, biofilms play a major positive role in st…
Single-crystal X-ray analysis has shown the tetrameric structure of the low melting point product obtained from the base catalysed condensation of formaldehyde and para-t-butylphenol and its ability to form a stable cage-type clathrate with toluene.
The extensive body of literature published on the physicochemical and catalytic properties of metal zeolites has been reviewed in detail by Minachev and Isakov [1]. Industrial processes in petroleum chemistry involving metal zeolite systems have been examined by Bolton [2], Quite recently Rudham and Stockwell [3] pres…
Refinement of the population and radial dependence of the spherical atomic valence shell is introduced in a general crystallographic least-squares program. The radial dependence is described by an expansion-contraction parameter κ, which, in the nine data sets tested, indicates contraction of positively and expansion…
Highly stable, flexible films of polypyrrole with p-type conductivities of 100 Ω–1 cm–1 have been prepared by electrolytic oxidation of the appropriate pyrrole monomers; similarly prepared films of mixtures of pyrrole and N-methylpyrrole have conductivities between 5 × 10–3 and 100 Ω–1 cm–1 depending upon the composit…
The thermal decomposition of the [Ru(NH3)6]3+ complex ion exchanged in a NaY zeolite followed by reduction in H2 at 623 K leads to highly dispersed Ru metal in the zeolitic pore system. X-ray diffraction techniques have been used to identify atomically dispersed Ru0 inside the sodalite cavity at the site II′. This hig…