Materials Literature
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The electronic properties of bis(2,6-bis(pyrazol-3-yl)pyridine)iron(II) triflate depend markedly on the extent of hydration. The trihydrate is low spin while the monohydrate is high spin at room temperature but undergoes a discontinuous transition to low spin at low temperatures. In the anhydrous complex magnetic and…
The two-dimensional silicon backbone structure of planar polysilane and W\"ohler siloxene is responsible for their exciting luminescing properties. We have prepared single crystals of siloxene by a topotactic reaction from crystalline CaSi${}_{2}$. The chemical composition was determined as [Si${}_{6}$H${}_{3}$(OH)${}…
N-vinyl-n-butyramide (NVBA), N-vinylisovaleramide (NVIVA), and N-vinyl-n-valeramide (NVVA), which are N-vinylalkylamides with different alkyl groups were synthesized and their solution behavior in a polymeric form was examined. Copolymers of N-vinylisobutyramide (NVIBA) with N-vinylacetamide (NVA), NVIBA with NVVA, an…
Oligonucleotide dendrimers were synthesized using a novel phosphoramidite synthon, tris-2,2,2-[3-(4,4'-dimethoxytrityloxy) propyloxymethyl]ethyl- N , N -diisopropylaminocyanethoxy phosphoramidite. Label, incorporated using [gamma-32P]ATP and polynucleotide kinase, was increased in proportion to the number of 5'-ends.…
The nonexponential response of propylene carbonate and glycerol near their glass transitions could be selectively altered using nonresonant spectral hole burning (NSHB) experiments. This observation provides evidence of the existence of a distribution of relaxation times in these supercooled liquids. NSHB is based on…
The surface structure of ${\mathrm{TiO}}_{2}(110)$ has been reexamined using scanning tunneling microscopy (STM), especially in terms of its temperature dependency. A dramatic topographic change was observed around 725 K, which is most likely due to the oxygen desorption into the gas phase and the simultaneous diffusi…
Using a low-temperature molecular-beam epitaxy growth procedure, ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ --- a III-V diluted magnetic semiconductor --- is obtained with Mn concentrations up to $x\ensuremath{\sim}9%.$ At a critical temperature ${T}_{c}$ (${T}_{c}\ensuremath{\approx}50\mathrm{K}$…
A multiple scattering formulation for the electromigration wind force on atoms in dilute alloys is developed. The theory describes electromigration via a vacancy mechanism. The method is used to calculate the wind valence for electromigration in various host metals having a close-packed lattice structure, namely alumi…
Structural optimization is performed for LaMnO${}_{3}$ with the first-principles pseudopotential method based on the local density approximation (LDA), the generalized gradient approximation, and the LDA+U approximation. The Jahn-Teller distortion is reproduced even by LDA but the magnitude of the distortion for all t…
The phase diagram of doped manganate compounds La_{1-x}A_xMnO_3 (with divalent A) is studied. We analyze an extension of the double exchange model using the Schwinger boson formalism. Earlier work by de Gennes on the existence of a canted phase is reproduced, although this phase is shown to be unstable towards phase s…
The controllability of conductivity and the ease of manufacturing/coating of conducting polymers enable tailor- made dielectric loss components for radar absorbing materials (RAM). Different polypyrrole (PPy) based RAM, e.g. paint/rubber containing PPy powder and PPy coated structural phenolic foams with a gradient of…
The flow behavior and the effect of the spinning conditions on the fiber properties and structure of the copolyesters, i.e., samples of copoly(p-hydroxybenzoate-bisphenol A terephthalate), were investigated. The experimental results indicated that the apparent viscosity was affected significantly by shear rate, melt t…
Highly fluorescent Eu-polymer complexes were synthesized through copolymerization of EuPhen(Nap)2AA with methyl methacrylate or styrene and their luminescent properties were investigated. The Eu-polymer luminophores showed intense red emission under UV excitation, and the emission intensities were much stronger than t…
Die Art des Köders bestimmt die Beute : In einem Teich mit Triethanolamin‐Liganden und Eisen(III)‐Ionen gelingt es, sechs‐ und achtgliedrige Eisencoronate 1 bzw. 2 zu fangen, je nachdem, ob man Natrium‐ oder Caesiumionen als Köder verwendet. Dies ist besonders im Zusammenhang mit der Möglichkeit kombinatorischer Ansät…
In this work, the surface treatment of poly(ethylene terephtalate) (PET) films in a low frequency (70 kHz) discharge in helium-oxygen mixtures is investigated. Optical emission spectroscopy and mass spectrometry are used to analyze the gas phase. Surface properties are analyzed via the X-ray photoelectron spectroscopy…
Angular distributions of valence photoelectrons showing effects due to higher-multipole photon interactions have been measured for the first time. Neon 2s and 2p photoemission exhibits effects beyond the dipole approximation throughout the 250 - 1200 eV photon-energy range studied. The results suggest that any photoem…
Methacrylic acid (MA) was graft polymerized onto starch using Ce4+ initiator in aqueous medium. The dependence of grafting on the reaction variables, such as monomer and initiator concentration and time and temperature, was studied in detail. Acid hydrolysis and infrared (IR) spectroscopy were used for the confirmatio…
Polyurethane elastomers based on polyols such as polycaprolactone diol of molar mass 2000 and polytetramethylene glycol of molar mass 2000; diisocyanantes such as diphenyl methane 4,4′ diisocyanate and dicyclohexyl methane 4,4′ diisocyanate; and chain extenders such as bisphenol-A, bisphenol-S,bisphenol-AF, and their…
We perform a comprehensive study of the formation of three dimensional (pyramidal) structures in a large range of conditions, including the possible evaporation of adatoms from the surface and the presence of surface defects. We compare our computer simulations to theoretical calculations of the growth and find good a…
Thin films are usually obtained by depositing atoms with a continuous flux. We show that using a chopped flux changes the growth and the morphology of the film. A simple scaling analysis predicts how the island densities change as a function of the frequency of the chopped flux in simple cases where aggregation is irr…