Materials Literature
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The surface flashover of a Macor glass-ceramic conical insulator in ultrahigh vacuum is investigated using direct current (dc), alternating current (ac at 60 Hz), standard lightning impulse (1.2/50 μs), and combinations of dc+1.2/50 μs and dc+ac. The dc and the 1.2/50-μs flashover voltages are found to be at about the…
The remanence, Br, of sintered 2:17 RE-TM permanent magnets depends on saturation magnetization, Ms, particle alignment, and packing density. Methods to estimate upper bounds for Msand energy product, (BH)max, as a function of composition are presented. As Bris limited by processing variables, (BH)maxis limited by int…
The limited transparency of high N (13.3 at.%) glasses in the system Si‐Y‐AI‐O‐N was found to be due to Si precipitates that resulted from thermal decomposition during melting. Thermodynamic analysis supported experimental findings that decomposition in N 2 at 200 kPa resulted from oxide‐nitride reactions and not from…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCompounds of pentacoordinate (10-B-5) and hexacoordinate (12-B-6) hypervalent boronDavid Y. Lee and J. C. MartinCite this: J. Am. Chem. Soc. 1984, 106, 19, 5745–5746Publication Date (Print):September 1, 1984Publication History Published online1 May 2002Published inissue 1 Se…
The magnetization processes in electrical steel sheets in rotating and alternating magnetic fields up to 1.8 T can be investigated with an instrument which is described in this paper. The components of the vectors of the magnetic induction\vec{B}and the magnetic field strength\vec{H}are measured wlth four sensors duri…
Abstract Aus NaH und metallischem Pt entsteht unter H 2 (280–310°C) rotviolettes Na 2 PtH 4 . Röntgen‐ und Neutronenbeugung (Na 2 PtD 4 ) an Pulverproben zeigen, daß Na 2 PtH 4 in einem bisher unbekannten tetragonalen Strukturtyp (a = 5,274(2), c = 6,788(3) Å; Raumgruppe I4/mmm; Z = 2) kristallisiert. Charakteristisch…
Abstract Disilanole des Typs R 2 Si(OH) 2 ( 1, 2 : R = CHMe 2 , CMe 3 ) und das Fluorsilanol (Me 3 C) 2 Si(OH)F ( 3 ) dienen in Reaktionen mit Halogensilanen als Startmaterial zum stufenweisen Aufbau von kettenförmigen Siloxanen ( 4 – 15, 16 –20 ). Auch Siloxane mit voluminösen tert ‐Butyl‐ oder Silylaminogruppen sind…
Abstract Metal dispersion has a striking influence on the activity and selectivity of Rh/SiO2 for high pressure CO hydrogenation. Decreasing dispersion, turnover frequency of CO conversion does not change significantly with dispersion up to 0.5 but increases abruptly at dispersion of 0.45. CH3OH is produced selectivel…
As a new probe of the nature of the two-dimensional melting transition, a Monte Carlo study of nearest-neighbor bond-angular susceptibility on various length scales has been performed. This probe has been used to distinguish between a hexatic phase and a two-phase region. We conclude that the melting transition of bot…
Abstract Die nichtlinearen optischen Eigenschaften organischer Verbindungen, die von ihren elektronischen Verhältnissen und ihrer Struktur im Festkörper abhängen, finden in vielen Bereichen der Optoelektronik einschließlich optischer Kommunikationstechnik, Positionierung und Steuerung von Lasern sowie integrierter Opt…
Ultrathin frozen sections are ideal substrates with which to carry out immunolabeling experiments in electron microscopy. However, the ultrastructural delineation in positively stained frozen sections has not been as detailed as in conventionally osmium-stained and plastic-embedded sections. We now describe a simple t…
This paper re-examines literature data on the charge-carrier mobility in tri-phenyl methane/polycarbonate, triphenyl amine/lexan and PVK: TNF composite systems. In all cases the dependence of μ on both temperature T and electric field E, as well as its absolute magnitude, can be interpreted consistently in terms of ho…
Abstract 2,5‐Bis(4‐aminophenyl)‐3,4‐diphenylthiophene, a polyimide‐forming monomer, was prepared in three steps starting from benzyl chloride and sulfur. Novel polyimides were synthesized from the diamine and pyromellitic dianhydride or 3,3′, 4,4′‐benzophenonetetracarboxylic dianhydride (BTDA). Polymerization was carr…
The infrared spectra (200–4000 cm −1 ) of 2-thiopyrrole-1,2-dicarboximide (TPH) in solid and solution forms have been measured as a function of temperature, and a direct correlation has been obtained between the two phases and the type and extent of hydrogen bonding. It is suggested that TPH exists as cyclic dimer in…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA model for the surface tension of molten alkali halidesKunimitsu Yajima, Hirotake Moriyama, and Jun OishiCite this: J. Phys. Chem. 1984, 88, 19, 4390–4394Publication Date (Print):September 1, 1984Publication History Published online1 May 2002Published inissue 1 September 19…
Tribological properties of five glass‐ceramics are reported. The materials were tested unlubricated against themselves. Testing was performed using a simulated inertial sample dynamometer. Sliding speeds were between 0.5 and 1.8 m /S with an applied load of 225 N. Average friction coefficients were in the range 0.07 t…
Abstract An iterative procedure for evaluation of the Mark–Houwink constants, using the GPC universal calibration principle and the extended [η]– M relationship, is described. The procedure is recommended for newly prepared polymers of unknown average molecular weights. An example is given for bisphenol C‐2 polycarbon…
Eddy current losses under large flux excitation in Mn-Zn ferrite cores and both polycrystalline and amorphous metallic cape cores of thickness 4μm to 28μm are measured in the frequency range up to 1MHz. Beyond 100kHz, the complex behaviors of magnetization in metallic cores as seen in the lower frequency range disappe…
We have devised a residue-residue potential function for low resolution protein conformational calculations. The interactions between residues near in sequence maintain correct secondary structure, while the long-range terms in the potential govern the larger packing features and overall globularity. The short-range t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-enhanced Raman scattering for redox-active adsorbents: pentaammineosmium(III)/(II) and pentaammineruthenium(II) containing nitrogen heterocycle ligandsStuart Farquharson, Kendall L. Guyer, Peter A. Lay, Roy H. Magnuson, and Michael J. WeaverCite this: J. Am. Chem. So…