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A coaxial air line was constructed to connect a radio-frequency impedance analyzer and a temperature-stabilized sample holder. It is suitable for dielectric measurements in the frequency range 1 MHz–1 GHz and at temperatures between 10 and 450 K. The dielectric dispersion of Fe-doped BaTiO3 and Na-doped KCN is present…
Perfluorooctylbromide: a new contrast agent for CT, sonography, and MR imagingRF MattreyAudio Available | Share
For most optical systems it is typically assumed that the transmitted wavefront has uniform for Gaussian) amplitude and constant polarization state. This is the default assumption of geometrical optics. This paper considers methods suitable for analyzing systems for which this assumption is not valid. Such methods of…
In paper I [Groma, Ungár & Wilkens (1988). J. Appl. Cryst. 21 , 47–53] a theory was developed to interpret the asymmetric X-ray line broadening of plastically deformed crystals. It was shown that the dislocation structure can be described by five distinct parameters, namely the dislocation density, the mean quadra…
Amines can be obtained from amides, nitriles, and nitroalkenes, alcohols from carboxylic acids, and sulfides from sulfoxides in good yields by use of the reducing agent LiBH4/Me3SiCl. Even α-amino acids can be easily reduced to amino alcohols with retention of optical purity. Compounds 1, 3, and 5 are examples of star…
Among the various high temperature polymers, those based on aromatic units, such as poly(2, 6-dimethylphenylene oxide) (PPO), poly(pheny1ene sulfide) (PPS), poly(ether ether ketone) (PEEK), and poly(ether sulfone) (PES), have attracted much attention in the last few years due to their good thermal and chemical resista…
The present work investigates the dynamics of the one-dimensional, unsteady flow of a spherical bubble cloud subject to harmonic far-field pressure excitation. Bubble dynamics effects and energy dissipation due to viscosity, heat transfer, liquid compressibility and relative motion of the two phases are included. The…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSuperdense carbon, C8: supercubane or analog of .gamma.-silicon?Roy L. Johnston and Roald HoffmannCite this: J. Am. Chem. Soc. 1989, 111, 3, 810–819Publication Date (Print):February 1, 1989Publication History Published online1 May 2002Published inissue 1 February 1989https:/…
Yttria‐doped zirconium oxide was prepared in the fully tetragonal, mixed tetragonal and cubic, and the fully cubic phases by varying the yttria conent. The fracture toughnesses of the materials were 11.6, 8.7, and 2.5 Mpa · m½, respectively. The wear resistance, measured in air at room temperature in slow sliding (1 m…
Indium tin oxide films have been deposited by rf sputtering an oxide target (90% In2O3+10% SnO2). Transparent conducting films have been obtained on room-temperature substrates without any post-deposition annealing. The effects of target-substrate separation on the growth characteristics and film properties have been…
High resolution 13C NMR spectroscopy of live cells has been used to show that poly-beta-hydroxybutyrate (PHB) is predominantly in a mobile state within the storage granules of Alcaligenes eutrophus, Methylobacterium extorquens, and Methylobacterium AM1. Comparison of chemical and NMR analysis of PHB indicates that abo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTManganese(II) N,N'-dipyridoxylethylenediamine-N,N'-diacetate 5,5'-bis(phosphate). Synthesis and characterization of a paramagnetic chelate for magnetic resonance imaging enhancementScott M. Rocklage, William P. Cacheris, Steven C. Quay, F. Ekkehardt Hahn, and Kenneth N. Raym…
3,6-Diphenylpyromellitic dianhydride (DPPMDA) has been synthesized from 2,5-diphenyl-3,4-bis(4-methoxyphenyl)cyclopentadiene-1-one and dimethyl acetylenedicarboxylate. The monomer was polymerized with 11 aromatic diamines in refluxing m-cresol containing isoquinoline to afford two new series of phenylated polyimides.…
A combined resistivity transmission electron microscopy (TEM) study has been done on heavily drawn Cu-20 vol % Nb alloys (so-called in situ alloys). The results show that electron scattering at Cu-Nb interfaces makes the major contribution to resistivity in heavily drawn wire. The dislocation contribution is small and…
A molecular kinetic theory for the rheology of glass is given. According to this theory, the structure of a glass consists of randomly distributed high-energy sites, which correspond to the frozen-in density fluctuations. These sites are termed as defects. The anelastic deformation associated with the \ensuremath{\bet…
Abstract Repeated ion exchange of the ZSM-5 zeolite using aqueous copper(II) acetate solution was found to bring about excess loading of copper ions above 100% of exchange level. The catalytic activities of the resulting Cu-ZSM-5 zeolites for direct decomposition of nitrogen monoxide were very high and increased with…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAttenuation lengths of photoelectrons in hydrocarbon filmsColin D. Bain and George M. WhitesidesCite this: J. Phys. Chem. 1989, 93, 4, 1670–1673Publication Date (Print):February 1, 1989Publication History Published online1 May 2002Published inissue 1 February 1989https://pub…
In situ spectroelectrochemical studies have been carried out on polyaniline films formed on a reflective platinum disk electrode in acidic media by means of near‐normal incidence reflectance spectroelectrochemical techniques. The results indicate that there are four optically different species depending on the potenti…
THE unique properties of diamond are yet to be tapped for a large number of advanced materials applications. Fascination with this king of all gemstones
Measurements of viscoelastic properties near the sol-gel transition demonstrate that viscoelastic phenomena are described by power laws. To describe these phenomena, we derive the distribution of relaxation times for branched polymers, both in the reaction bath and in the dilute solution. From this spectrum we can com…