Materials Literature
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Thermal diffusivity (α) of amorphous silicon carbon nitride (a-SiCxNy) thin films on crystalline silicon, prepared by ion beam sputtering, has been studied using the traveling wave technique. The variation of thermal diffusivity with carbon content in amorphous silicon carbon nitride samples are reported. Thermal diff…
Die Addition eines Coliganden bei Reaktionen von Phosphonaten mit Salzen später 3d-Metalle liefert besser lösliche und leichter verarbeitbare Materialien wie den hier gezeigten {Co13}-Käfig (Co: grün, P: violett). Die Struktur enthält zwei zentrale PhPO32−-Liganden, umhüllt von einer sechskernigen Cobalthelix, die wie…
The plane elasticity theory of two-dimensional octagonal quasicrystals is developed in this paper. The plane elasticity problem of quasicrystals is reduced to a single higher-order partial differential equation by introducing a displacement function. As an example, the exact analytic solution of a Mode I Griffith crac…
We report the first observation of the transition between interacting and noninteracting behavior in the ac conductivity spectrum sigma(omega) of a doped semiconductor in its Coulomb glass state near T = 0 K. The transition manifests itself as a crossover from approximately linear frequency dependence below approximat…
Sixth-generation PAMAM dendrimers labeled with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, shown schematically) have been synthesized and are shown to reoxidize EPR-silent hydroxylamines to EPR-active nitroxides. Therefore these dendrimers are potential TEMPO free radical life supporters for EPR imaging.
Low-field intergrain magnetoresistance (IMR) in the polycrystalline materials of double perovskite SrFe0.5Mo0.5O3 is found to be highly tunable by doping either Ca or Ba into the Sr site. The dopant exerts a chemical pressure, changing the Curie temperature and the magnetic softness. The room-temperature IMR at optima…
The results of heat capacity in the presence of an external magnetic field and resistivity measurements on the compounds ${\mathrm{CeCu}}_{x}{\mathrm{Ge}}_{2}$ and ${\mathrm{PrCu}}_{y}{\mathrm{Ge}}_{2}$ with the starting $x=0.86$ and $y=0.76$ are reported. The magnetocaloric effect in the compounds was calculated from…
Nematic fluids with polar order could be most useful new molecular materials. However, such ferroelectric liquid crystals have not been observed as yet. This paper describes the first computer simulations of a ferroelectric nematic phase made from simple tapered particles as shown in the picture and gives some hints a…
The controlled synthesis of nematic nanophase-separated materials poses an attractive synthetic challenge. The use of carbosilazane multipodes and dendrimers (such as 1) in conjunction with laterally attached mesogens allows the systematic investigation of the structure-property relationships of room-temperature nemat…
Incorporation of three metal ions (Ni or Cu) in the macrocyclic ring and the formation of hexamers following a 3+3 approach are novel features of the hemiporphyrazines (one example shown) formed by the condensation of 2,5-diamino-1,3,4-triazole with isoindolediimines. This is in contrast to the corresponding reactions…
Conducting polymer actuators generate forces that exceed those of mammalian skeletal muscle by up to two orders of magnitude for a given cross-sectional area, require only a few volts to operate, and are low in cost. However application of conducting polymer actuators is hampered by the lack of a full description of t…
A major aim for the chemical technology of the future is the avoidance of noxious and environmentally unacceptable organic solvents. In this concept article we discuss more environmentally friendly and highly selective alternatives which we have evolved for carrying out a number of important chemical conversions. Thes…
Novel chiral macrocycles consisting of two rigid oligoarylene rods and two chiral spiroindane clips have been synthesized by condensation of spiroindane diols and CF3-activated alpha-omega-difluorooligoaryls. Since a broad variety of planar aromatic macrocycles is known, our non-planar, chiral rings represent a new cl…
A multiple slip dislocation-density based crystalline formulation has been coupled to a kinematically based scheme that accounts for grain-boundary (GB) interfacial interactions with dislocation densities. Specialized finite-element formulations have been used to gain detailed understanding of the initiation and evolu…
Abstract It has been demonstrated that surfaces coated with poly(ethylene glycol) (PEG) are capable of reducing protein adsorption, bacterial attachment, and biofilm formation. In this communication cold‐plasma–enhanced processes were employed for the deposition of PEG‐like structures onto stainless steel surfaces. St…
Abstract The copolyester poly(ethylene glycol‐ co ‐cyclohexane‐1,4‐dimethanol terephthalate) (PETG) is used industrially as an uncrystallizable polymer, whereas PET is an inherently crystallizable polymer. Nevertheless, a crystalline phase could appear in the material. To create a strain‐induced crystalline phase in a…
The electrical conductivities and Seebeck coefficients of boron carbides ${\mathrm{B}}_{12+x}{\mathrm{C}}_{3\ensuremath{-}x}$ with $0.06\ensuremath{\lesssim}x\ensuremath{\lesssim}1.7$ have been measured from 8 K to as high as 1750 K. At high temperature, the temperature dependence of the conductivities is Arrhenius an…
The synthesis of a linear polymer that includes both P=N and P=S double bonds, and P-O and P-C single bonds is reported by using two different paths that involve deprotection reactions and the Staudinger reaction. The preparation of hyperbranched polymers made up of OC6H4P(Ph)2=N-P=S repeating units is also described.…
Unusual morphological features of boron nitride nanotubes produced via metal–oxide-promoted high-temperature syntheses from carbon nanotubes, boron oxide, and nitrogen were observed using high-resolution transmission electron microscopy. The tubes normally displayed open ends and preferentially two or four tubular lay…
The architecture of windmill hexameric zinc(II) -porphyrin array 1 is attractive as a light-harvesting functional unit in view of its three-dimensionally extended geometry that is favorable for a large cross-section of incident light as well as for a suitable energy gradient from the peripheral porphyrins to the meso-…