Materials Literature
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A slab of negatively refracting material is known to focus light and if 1 n = the focussing will be perfect, producing an image which is an exact replica of the object. Magnifying the image requires a new design concept in which the surface of the negatively refracting lens is curved. Here we show how a hollow cylinde…
We analyze the transmission properties of double negative metamaterials (DNM). Numerical simulations, based on the transfer matrix algorithm, show that some portion of the electromagnetic wave changes its polarization inside the DNM structure. As the transmission properties depend strongly on the polarization, this co…
The interactions of pulsed and continuous wave (CW) Gaussian beams with double negative (DNG) metatmaterials are considered. Subwavelength focusing of a diverging, normally incident pulsed Gaussian beam with a planar DNG slab is demonstrated. The negative angle of refraction behavior associated with the negative index…
Two distinct models account for the microwave residual surface resistance of superconducting cavities with equally good agreement with the measured temperature and frequency dependence. In presenting his phonon-generation model, Passow claimed that Rabinowitz' fluxoid power-loss model of residual resistance does not f…
Results of low temperature dielectric measurements on the mixed (Ca_(1-x)Pb_(x))TiO_(3) system are presented to show that a dielectric anomaly appears for x \geq 0.10. The observed dielectric peak is shown to be due to a thermodynamic phase transition and not due to a relaxor or dipole glass type transition. Curie-Wei…
The structural and magnetic transitions in the Pr 0.5 Sr 0.5 - x Ba x MnO 3 series have been investigated by neutron diffraction and electron microscopy, in connection with the transport and magnetic properties, allowing a new phase diagram ( T, x, or < r A >) to be drawn. Two important points emerge from this study.…
Polyacrylate-capped Pt nanocrystallites of 2.5 ± 0.6 nm diameter were synthesized by reduction of Pt(IV) with citrate in the presence of polyacrylate and were self-assembled layer-by-layer in poly(diallyldimethylammonium chloride) by virtue of the Coulombic attraction between the negatively charged capping agent and t…
We have investigated the solid-state photobehavior of a broad set of pyridine-3-carboxaldehydes 1-5. The introduction of a heteroatom into mesitaldehydes as in aldehydes 1 raises the question of conformational preference in the solid state. The preferred conformations have been unequivocally established from X-ray cry…
Flax fibers composed mainly of cellulose were subjected to heterogeneous valerylation reaction. The progress of the chemical modification was assessed by transmission FTIR. The heterogeneous esterification reaction followed first-order kinetics, and a plateau was reached already after 30 min. The intensity of the FTIR…
This paper focuses on the preparation and characterization of a titanium−tin mixed oxide (Ti,Sn)O 2 with anatase structure. The preparation method is based on a sol−gel technique using titanium tetra-isopropoxide and tin tetrachloride as precursors. The obtained TiO 2 and titanium−tin mixed oxide xerogels and their he…
Mode coupling theory (MCT) is used to model gel formation in mixtures of colloidal particles and nonadsorbing polymer. The polymer induces an effective, short-range attraction among the colloids, which is modeled by a depletion attraction of the Asakura−Oosawa form. This enables the MCT to be solved analytically for d…
Block copolymers, easily tailor-made by growing poly(ethylene oxide) from a commercial hydroxyl-terminated poly(ethylene- co -butylene) (Kraton liquid), can self-assemble over a wide range of concentrations into mesophases constructed from spherical micelles with small polydispersity. These phases are analyzed in deta…
The paper deals with the interpretation of the Mn 2+ EPR spectra in the high-temperature phase of MgSiF 6 ·6H 2 O. Two models are presented: the continuous and the discrete antiphase domain walls. Just above the ferroelastic phase transition, for each resonance transition two EPR lines are observed: the broad one and…
Eine eiserne Konstitution: Dunkle superparamagnetische Eisenoxid-Nanopartikel befinden sich innerhalb der Wände eines hexagonalen mesoporösen Alumosilicats (siehe zugehörige Hellfeld-TEM-Abbildung). Der einfache Eintopfansatz, der auf der Selbstorganisation von Blockcopolymeren beruht, hat das Potenzial für Anwendunge…
The doublet anionic states of TCNQ-F4 (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) have been studied at the Hartree−Fock and the Møller−Plesset (MP) perturbation theory levels (up to fourth order) with aug(sp)-pVDZ basis sets. Our results indicate that TCNQ-F4 forms a stable anion of B 2g symmetry whose vert…
Arabinoxylans (AXs) are byproducts of the cereal milling industry. To obtain high-value products, AXs have been used as a film-forming agent. Hence, AX-based films are poor water vapor barriers. The objectives of this study were to graft omega-3 (omega3) fatty acids onto AX polymeric chains by using two new technologi…
Dielectric constants $({\ensuremath{\epsilon}}^{\ensuremath{'}},$ ${\ensuremath{\epsilon}}^{\ensuremath{''}})$ and switching current transients of $\mathrm{Pb}({\mathrm{Zr}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}){\mathrm{O}}_{3}$ thin films are measured for mixing concentrations of $x=0.46,$ 0.48, and 0.49 in the morpho…
The removal of a key residue (Arg 90) from the chorismate mutase enzyme destroys the balance of the interactions in the active site required for stabilizing the conformation of the transition state in the Claisen rearrangement of chorismate to prephenate (see picture).
Novel dendritic mixed-valence dinuclear ruthenium complexes were prepared and chemically cross-linked to form thin films on ITO electrodes. The cross-linked films exhibited an excellent electrochromism in the near-infrared (NIR) region and optical attenuation of 5.4 dB/μm in thickness at 1550 nm with a switching time…
Die Konfiguration der 1,2-Cyclohexandiol-Zwischenstufe spielt eine entscheidende Rolle hinsichtlich der Geschwindigkeit und der Selektivität der Bildung von Adipinsäure aus Cyclohexen in einer lösungsmittelfreien Synthese. Ein Titan-haltiges Aluminophosphat-Molekularsieb (TAPO-5) erwies sich als effizienter heterogene…