Materials Literature
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Abstract Microwave transmission, reflection, and absorption behavior and the shielding effectiveness of electrochemically synthesized polypyrrole films with dc conductivities ranging from 0.001 to 50 S/cm are presented. Results show that the electrical conductivity of the doped polypyrrole films has a significant effe…
Molecular structures can perform diverse functions . Tailored bolaamphiphiles were used to prepare vesicles containing redox‐active centers or (chiral) binding sites for guests, as well as aggregates. In addition, monomeric and polymeric bolaamphiphiles can disrupt membranes. RNA‐based bolaamphiphiles of this type may…
We report the growth of epitaxial SrxBa1−xNb2O6 (SBN) thin films by pulsed laser deposition. The films were grown on (100) MgO substrates with thicknesses in the range 200–400 nm. Rutherford backscattering analysis showed that the films have stoichiometric composition identical to the target material. X-ray diffractio…
For 30 diamond- and zincblende-structure semiconductors, the bond length d, bond polarity alpha p , bulk modulus B, elastic shear constants (c 11 -c 12 )/2 and c 44 , bond-stretching force constant alpha , bond-bending force constant beta , internal displacement parameter zeta , effective atomic charge Z*, transfer pa…
Dynamic processes in liquid propylene glycol and two of its oligomers inside the \ensuremath{\cong} 100 \AA{} pores of controlled porous glasses have been investigated as a function of temperature by dielectric spectroscopy. We find that geometrical restriction results in retardation and broadening of the inherent $\e…
We report the observation of giant magnetoresistance near room temperature in ferromagnetic films of La1−xSrxMnOz for 0.16≤x≤0.33. For B=5 T, the maximum magnetoresistance ratio [R(0)−R(B)]/R(0) of an annealed film is 60% at 260 K for x=0.2, and 35% at 330 K for x=0.33. Annealed films have higher Curie temperature (Tc…
Abstract In der Übergangsmetallchemie gibt es eine Klasse von Komplexverbindungen, bei denen eine Temperaturerniedrigung einen Wechsel im Spinzustand des Zentralatoms vom High‐Spin‐ in den Low‐Spin‐Zustand bewirkt. Dabei ändern sich die magnetischen und optischen Eigenschaften, über die der thermische Spinübergang (au…
The elastic moduli directly reflect bonding strength and structure. Usually these factors can be only slightly modified within a given material, but in amorphous carbon films large variations of Young's modulus from less than 100 up to more than 500 GPa are found. This can be attributed mainly to the varying fraction…
In addition to the well-known properties of diamond-like-carbon (DLC) coatings, the surface tension is a new criterion to characterize this kind of thin films. To influence the surface tension of DLC coatings, their structure is modified by the incorporation of different elements like fluorine or silicon into the matr…
Electron-momentum spectroscopy [binary encounter (e,2e)] experimental results are presented for the core state of an amorphous carbon allotrope. The (e,2e) cross section has two identifiable regions. One is a narrow-energy-width core-band peak that does not disperse with momentum. At higher binding energies there is a…
A kinetic and ligand binding study on maize (Zea mays) malate synthase is presented. It is concluded from kinetic measurements that the enzyme proceeds through a ternary-complex mechanism. Michaelis constants (Km,glyoxylate and Km,acetyl-CoA) were determined to be 104 microM and 20 microM respectively. C.d. measuremen…
We report results for photoluminescence studies of an impurity-related defect system in 450 \ifmmode^\circ\else\textdegree\fi{}C annealed Czochralski-grown silicon resulting in optical emission with a wavelength near 1.7 \ensuremath{\mu}m. The photoluminescence emission is found to have a significant intensity that pe…
Medium-energy ion-scattering measurements and Monte Carlo simulations have been used to study the Al(001) surface as a function of temperature. Surface melting does not occur and the surface stays well ordered up to the bulk melting point ${\mathit{T}}_{\mathit{m}}$=933.52 K. The combination of the effective-medium po…
The electronic and the optical properties of \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ are studied by means of first-principles local-density calculations. The structural properties obtained via total-energy calculations are in good agreement with the results of Liu and Cohen [Phys. Rev. B 41, 10727 (199…
Various structural possibilities for the Si2C4 and Si4C2 clusters are investigated by employing a basis set of triple-zeta plus polarization quality; electron correlation is generally accounted for by second-order Mo/ller–Plesset and, in certain instances, by higher-order perturbation (CASPT2) approaches. The building…
Molecular dynamics simulations have been performed for the nematic liquid crystal 4-n-pentyl-4′-cyanobiphenyl (5CB) using a realistic atom–atom potential as well as a pseudorealistic atom–atom potential. The latter treats the phenyl rings in the 5CB molecule as simple spheres. This method allows a considerable decreas…
Analyses of high-resolution synchrotron X-ray powder diffraction patterns of dry-synthesized MFemSi206 leucites (M = K, Rb, Cs) showed that the K-and Rbcontaining leucites (iron potassium silicate, KFeSi206, and iron rubidium silicate, RbFeSi206) each have a tetragonal 141/a structure and the Cs-containing leucite (ca…
We report Hall-effect measurements on single crystals of antiferromagnetic pyrite-type ${\mathrm{NiS}}_{2}$ (${\mathit{T}}_{\mathit{N}}$=40 K), in which the resistivity appears to show a metal-insulator transition at T\ensuremath{\approxeq}100 K. Our transport measurements demonstrate that this transition is not intri…
We have studied the electronic properties of the Cu/${\mathrm{TiO}}_{2}$(110) and Fe/${\mathrm{TiO}}_{2}$(110) interfaces using in situ ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy (IPS). The chemical interaction between these two transition metals and the substrate was monitored…
Nanometer size crystalline particles of α-Fe, γ-Fe, Ni, β-Co, and Co3C encapsulated in multiwalled carbon cages are synthesized by a standard dc arc evaporation of composite anodes containing 10–15 wt. % each of the metals or their compounds. The typical particle size is ∼10 nm. Elemental analysis is made by x-ray ene…