Materials Literature
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Low absorption coefficients for the light polarizations along the crystallographic a, b, and c* axes of (-)2-α-(methylbenzylamino)-5-nitropyridine single crystals were measured at the wavelengths 1064 nm and 532 nm. They were found to be in the range from 0.02 cm-1 to 0.06 cm-1, i.e., of the same order of magnitude as…
Abstract Crystal structure and polymorphism induced by uniaxial drawing of a poly(aryl ether ketone) [PEDEKmK] prepared from 1,3‐bis(4‐fluorobenzoyl)benzene and biphenyl‐4,4′‐diol have been investigated by means of transmission electron microscopy (TEM), electron diffraction (ED), wide‐angle X‐ray diffraction (WAXD),…
Abstract Poly( p ‐phenylene sulfide) (PPS) oligomers were synthesized from sodium sulfide (SS) and p‐dichlorobenzene ( p ‐DCB) in hexamethylphosphoramide (HMPA) under atmospheric pressure. The effects of reaction time, temperature, and monomer ratio on end groups and molecular weight of PPS oligomers were investigated…
Lanthanide luminescence was used to examine the effects of posttranslational adenylylation on the metal binding sites of Escherichia coli glutamine synthetase (GS). These studies revealed the presence of two lanthanide ion binding sites of GS of either adenylylation extrema. Individual emission decay lifetimes were ob…
Electrochemical cyclic potentiodynamic polarization experiments were performed on several candidate waste package container materials to evaluate their susceptibility to pitting corrosion at 90 degrees C in aqueous environments relevant to the potential underground high-level nuclear waste repository. Results indicate…
Stress corrosion cracking (SCC) of single-crystal type 321 (UNS S32100) stainless steel (SS) was investigated in 42% boiling magnesium chloride (MgCl2) solution. Tests were performed under Mode II loading to study the SCC mechanism. Maximum normal stress and maximum shear stress were located at different positions on…
The genes (mdh) encoding malate dehydrogenase (MDH) from the mesophile Chlorobium vibrioforme and the moderate thermophile C. tepidum were cloned and sequenced, and the complete amino acid sequences were deduced. When the region upstream of mdh was analyzed, a sequence with high homology to an operon encoding ribosoma…
The crystal structure of [Ni(H2O)4(NA)2](NO3)2.2H2O (NA[dbnd]nicotinamide) has been determined. The complex cation has a monomeric pseudo-octahedral configuration about Ni(II). The basal plane contains four oxygen atoms of coordinated water molecules and axial positions are occupied by heterocyclic nitrogen atoms of t…
The shear modulus and mechanical loss at low frequencies (0.01, 0.3, 1 Hz) are measured by an inverted pendulum for BaTiO3 ceramic with large grain sizes. The permittivity and dielectric losses are also investigated for the same material at higher frequencies between 1 and 100 kHz as function of temperature. Those res…
We report a preliminary investigation of nonaqueous sizing and desizing where liquid carbon dioxide is the solvent. New size formulations are required for this process because traditional size materials are not directly soluble in liquid carbon dioxide. Candidate size compounds are first tested for solubility, and tho…
Formation of hydride at stress concentrations occurs in some materials as part of a stable cracking mechanism called delayed hydride cracking (DHC). As hydrogen combines with matrix material to become hydride, transformation strain is accommodated by local redistribution of stress. Since stress gradients drive hydroge…
The 2:1 mixture of LiF and BeF2 (Flibe) is a potential liquid tritium breeding material for fusion reactors, because of low electric conductivity, high chemical stability in air, etc. We have been studying tritium release behavior from Flibe by in-pile tritium release experiment in the fast neutron source reactor “YAY…
We present the design and performance of a temperature- and pressure-controlled sample cell for the small-angle x-ray diffraction analysis of lyotropic liquid crystalline materials. The particular requirements for such a system of high resolution, high intensity, and control on sample homogeneity can be particularly w…
Abstract Thermal expansion coefficients were measured for a cancrinite from Bancroft, Ontario, Canada. Measurements of cell parameters and unit-cell volumes were obtained at room temperature and at heating intervals of 50°C over the temperature range from 50 to 1400°C. The unit-cell parameters for cancrinite increase…
The first stages of the electrochemical oxidation of Zircaloy‐4 are investigated using simple electrochemical tests and modeling the passive film modifications occurring as a result of contact with the electrolyte. Variations in electrode potential (open‐circuit conditions) or current density (potentiodynamic scans) c…
Abstract Differential scanning calorimetry (DSC) was used to investigate the crystallinity of crude PVC powders and annealed PVC compounds. Crude PVC powder exhibited a broad crystallite fusion endotherm ranged from 110°C to 220°C. High degree of polymerization of PVC showed high degree of crystallinity both for powde…
The aim of this work is to understand the molecular structural properties which may justify the great observed stability of doped alkoxy polythiophenes. Infrared frequency and intensity spectroscopy and Raman spectroscopy are used as probes. Suitably synthesized oligomers with increasing chain length and preassigned c…
Abstract The dielectric properties of hexagonal lithium iodate (α‐LiIO 3 ) single crystals have been studied at frequencies 10 −2 Hz⩽ v ⩽10 9 Hz and temperatures 100K ⩽ T ⩽ 500 K. Pure and iron doped crystals were investigated. Below approximately 10 kHz, the electric response of the LiIO 3 crystals is almost entirely…
A method is presented that positions polar hydrogen atoms in protein structures by optimizing the total hydrogen bond energy. For this goal, an empirical hydrogen bond force field was derived from small molecule crystal structures. Bifurcated hydrogen bonds are taken into account. The procedure also predicts ionizatio…
Abstract The magnetic properties of a valence delocalized mixed valent Fe(II)‐Fe(III) complex have been investigated. On the basis of magnetic susceptibility measurements and NIR absorption spectroscopy the double exchange parameter was determined to B = 940cm −1 while for the isotropic exchange interaction an antifer…