Materials Literature
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Abstract New alternating poly(amide‐ester)s derived from β‐hydroxy acids and α‐amino acids 3a,b or ϵ‐aminocaproic acid 4a‐c were prepared. Two approaches were considered: (i) polycondensation of N‐(β‐hydroxyacyl)‐amino acids 1a,b and 2b,c and (ii) ring‐opening polymerization of cyclic amide‐esters 5a‐c and 6a‐c . For…
Self-reinforced silicon nitride ceramics rely the generation of elongated grains that act as reinforcing elements to gain increases in fracture toughness. However, the size and number of the reinforcing grains must be controlled, along with the matrix grain size, to optimize the fracture toughness and strength. Furthe…
In this paper the different types of hydrogen bonds are described. The literature, concerning different kinds of mesogenic structures which were built up via intermolecular hydrogen bonds, is discussed. The role of hydrogen bonding in the liquid crystal formation is pointed out and its influence on the thermal and chi…
Diamond-like Carbon (DLC) coatings have recently proven to be suitable for a number of tribological applications. Hardness of the DCL coating is very important for such application. An in-situ, non-destructive technique to measure the film hardness would be crucial for process control and quality control of DLC coatin…
Temperature-dependent X-ray diffraction measurements are reported for ZrMo 2 O 8 in the trigonal phase from 80 to 925 K. The measurements reveal highly anisotropic thermal expansion coefficients with average values of −3.9 × 10 −6 and 52 × 10 −6 K −1 for the a and c cell parameters, respectively.
The structure of the orthorhombic room-temperature phase of Cu(8)GeS(6) (copper germanium sulfide), M(r) = 773.27, has been refined on the basis of X-ray diffraction data from a 12-fold twinned crystal applying a six-dimensional twin refinement technique. For 1804 unique reflections measured using Mo Kalpha radiation,…
Results from the postirradiation examinations of microplates irradiated in the RERTR-1 and -2 experiments in the ATR have shown several binary and ternary U-Mo alloys to be promising candidates for use in aluminum-based dispersion fuels with uranium densities up to 8 to 9 g/cm{sup 3}. Ternary alloys of uranium, niobiu…
Abstract Blueschist-facies metabasite rocks from the Tavşanlı Zone of northwest Turkey have been found to contain an abundance of lawsonite displaying oscillatory zoning. Lawsonite normally adheres to the ideal composition of CaAl 2 [Si 2 O 7 ](OH) 2 .H 2 O. In two samples from the Tavşanlı Zone, Al 3+ -Cr 3+ substitu…
The dielectric parameters (ε′, ε″) and loss (tan δ) are studied in spinel ferrites of NiFe2O4 and Ni1—xCuxAlFeO4 with x from 0.0 to 1.0, as a function of temperature in the frequency range 102 to 105 Hz. All these samples are found to exhibit dipolar relaxation effects. The variations of ε′, ε″ and tan δ with frequenc…
Systematic comparison of the absorption spectra in the amorphous state has been made between ionic compounds (CsPbX 3 , TlX and PbX 2 with X = Br and Cl) containing 6s 2 ions as a constituent. The spectra exhibit several common features including nearly the same optical energy gap observed for all the compounds with t…
The effects of interference between closely packed diffraction orders in the far field are studied for a number of different scalar-domain diffractive optical elements (DOE's). We demonstrate that there are specific order separations that minimize the observed degradation in the far-field output uniformity. Finally, a…
The promising mechanical performance of a baseline Hybrid Titanium Composite Laminate (HTCL) inspired an investigation into maximizing the strength and environmental performance of this new aerospace material. This research focused upon finding the strongest and most durably combination of three commercially-available…
MOCVD of copper(I) and copper(II) oxides has been studied in a horizontal, low-pressure reactor using the β-ketoiminate copper(II) complex of 4,4′-(1,2-ethanediyldinitrilo)bis(2-pentanone) as precursor (Cu(acen)). Film morphologies and growth kinetics are strongly influenced by the nature of the substrate. On glass, n…
We show that special structural changes (phason atomic jumps) can transform the BC8 and R8 phases, known to occur in Si and Ge, into a phase with tetrahedral coordination. These structural changes are analogous to the BC8-R8 transformation. The phase has the body-centered-tetragonal symmetry (the space group ${C}_{4h}…
Mineralogi
Three tetraketones based on the 2,2'-spirobiindan-1,1',3,3'-tetraone skeleton were prepared and investigated. All three compounds show spiroconjugation between their perpendicular pi-networks. The interaction results in lowering of the energy of the LUMO of the systems by ca. 0.2-0.3 eV as compared to non-spiroconjuga…
A multi‐Debye relaxation model that is based upon the Boltzmann superposition principle has been used to determine the frequency‐dispersion behavior of Pb(Mg 1/3 ‐Nb 2/3 )O 3 (PMN) and Pb 0.88 La 0.08 (Zr 0.65 Ti 0.35 )O 3 (PLZT 8/65/35) relaxor ferroelectrics. For PMN, relaxation times on the order of seconds contrib…
Reaction of zinc 5,15-bis(3,5-di-tert-butylphenyl)porphyrin with S-(trifluoromethyl)-3,7-dinitrobenzothiophene trifluoromethanesulfonate in tetrahydrofuran gave the 10-trifluoromethylated compound as the major product and 2-CF3- and 10,20-di-CF3-porphyrins as the minor products. The direct trifluoromethylation is effe…
Abstract Previous work on growth‐rate dispersion has shown how to calculate crystal‐size distributions when the growth‐rate distribution is known and how to calculate the growth rate distribution when the crystal‐size distribution is known. There is a significant lack of information, however, on how growth‐rate disper…
A new approach for phosphor-based temperature determination is presented. This method is based on comparison between the spectrally resolved phosphorescent emission and a database of spectra collected at a series of temperatures. Applications of two phosphor materials, Gd 2 O 2 S: Tb and Mg 4 (F)GeO 6 : Mn, possessing…