Materials Literature
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The role of the crevice‐opening dimension, a , on the stability of crevice corrosion was investigated in the Ni/1 N H 2 SO 4 system. The electrode potential and current distributions inside the crevice were measured and calculated, respectively. Other variables, in particular the composition of the electrolyte, were c…
A modern ceramic‐matrix composite (CMC) has been extensively characterized for a high‐temperature aerospace turbine‐engine application. The CMC system has a silicon‐nitrogen‐carbon (Si‐N‐C) matrix reinforced with Nicalon fibers woven in a balanced eight‐harness satin weave fabric. Tensile tests have demonstrated that…
Fourier transform infrared spectroscopy (FT-IR) was used to study the cure reaction process of an ester-type photosensitive polyimide, PMDA/ODA films coated on silicon wafer substrates. In the in situ high-temperature FT-IR study carried out in vacuum, all the characteristic peaks of imide and the crosslinkable group…
Glasses and polycrystals in the series x Na 2 S + (1 − x )B 2 S 3 have been prepared and studied by magic angle spinning (MAS) NMR and by two-dimensional multiple-quantum (MQ) MAS NMR of 11 B and 23 Na. These techniques, when applied at various magnetic fields and combined with computer simulations of the spectra, pro…
Cocondensation of thermally generated silicon atoms with hydrogen cyanide in an argon matrix can be used as an access to compounds of the composition CHNSi and CNSi. Isolation, matrix-spectroscopic identification and photo-chemical behavior of these species are described. Structural assignments are made by the compari…
Fe films have been prepared in ultrahigh vacuum by epitaxial growth on MgO(001) substrates. Spin-resolved inverse photoemission measurements indicate that nonannealed overlayers display lower spectroscopic quality than the corresponding bulk system. Low energy electron diffraction and x-ray photoemission reveal that a…
Abstract In the present paper, we report the synthesis of free 5‐ and 10‐monophenylcorroles, 4 and 3 respectively as well as the first example of molecular oxygen oxidation of the corrole macrocycle identified as an open chain tetrapyrrole (biliverdin) structure 7 . Reaction of 1 and 2 in acetic acid leads to a mixtur…
Microstructural features and magnetic behavior of epitaxially grown SmCo thin films with very high in-plane anisotropy are presented. Transmission electron microscopy was used to characterize the microstructure while magnetic measurements were performed using dc and SQUID magnetometers. Two substrate orientations were…
The initial permeability of NiFe single layer films and single and multi-layer FeAlN films up to 500 MHz are presented. The permeability of thin (<1500 /spl Aring/) NiFe and FeAlN films were fit with calculations based on the Landau-Lifshitz/Gilbert model for phenomenological damping, using damping factors of /spl sim…
The new spin cluster [Mn II 4 Mn III 3 (teaH) 3 (tea) 3 ](ClO 4 ) 2 × 3MeOH realizes a topological structure of mixed-valence manganese clusters which is especially favorable for a high-spin ground state. The magnetic properties of the spin cluster are studied numerically by exact diagonalization of the spin Hamiltoni…
Herein we report the synthesis of highly cross-linked polymers based on divinylbenzene by heterogeneous polymerization in supercritical CO2 (scCO2). The polymers were isolated in the form of discrete microspheres (diameter = 1.5–5 μm) in good yields (≥90%), in the absence of any stabilizers. In the presence of a CO2-s…
We report on a study of transparent conducting tin‐doped indium oxide (ITO) electrodes in propylene carbonate solutions containing lithium ions. The system was studied using electrochemical methods in combination with in situ techniques: ultraviolet‐visible spectroscopy, X‐ray diffraction, and quartz crystal microbala…
Polyurethanes have unique mechanical and biologic properties that make them ideal for many implantable devices. However, certain polyurethanes are affected by some in vivo degradation mechanisms. For example, poly(ester)urethanes are subject to hydrolytic degradation and are no longer used in long-term implanted devic…
We report a parameter-free test of the theory predicting the critical solute concentration that destabilizes a planar solid-liquid interface in the high-velocity regime where nonequilibrium interface kinetics are important. Rapid solidification following pulsed laser melting was used to make metastable solid solutions…
ABSTRACT The foam stability properties of a defined mixed solution of Tween 20 and bovine serum albumin was evaluated as a function of arabinoxylan concentration. A marked increase in the foam stability was observed with low concentrations of arabinoxylan. Maximum improvement in the foam stability was obtained with 0.…
In-situ attenuated total reflection (ATR)-FTIR spectroscopy was used to monitor the consecutively alternating adsorption of polyethylenimine (PEI) and poly(acrylic acid) (PAC) onto both Si crystals (SiO) and CO2 plasma-treated polypropylene (PP) films. The vibration band vas(COO−) and v(CO) of PAC are diagnostic for…
Conjugated polymers that exhibit color changes on being switched between the conducting and insulating forms hold promise for applications in electrochromic devices. With the aim of increasing the electrochromic color contrast of polypyrrole/dodecylsulfate (PPy/DS) films and investigating a possible modulation of the…
5,5'-Bis(4-aminophenyl)-2,2'-bifuryl (PFDA) with a well-defined conjugation length was synthesized, and its soluble poly(amic acid) was prepared by polycondensation with pyromellitic dianhydride (PMDA). The PMDA-PFDA polyimide films were obtained from the poly(amic acid) solution through a conventional spin-casting, b…
Bis[ p -(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)phenyl] nitroxide ( 3 ) was synthesized via desilylation of O -protected diradical followed by autoxidation. By deoxgenation of 3, p -(1-oxyl-4,4,5,5-tetramethylimidazolin-2-yl)phenyl- p -(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)phenyl nitroxide ( 4…
The evolution of polymolecular micelles formed by two different poly(2-vinylpyridine)-polystyrene (PVP-PS) block copolymers dissolved in toluene is studied by means of transmission electron microscopy (TEM). The two PVP-PS diblock copolymers differ in composition, namely in the length of PVP block. Upon dissolution, a…