Materials Literature
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Length-dependent charge redistribution in dangling-bond (DB) linear chains fabricated on a hydrogen-terminated $\mathrm{Si}(100)\ensuremath{-}(2\ifmmode\times\else\texttimes\fi{}1)$ surface is analyzed by using scanning tunneling microscopy and first-principles calculations. The second-layer Si atoms are displaced alt…
Die lösungsmittel- und katalysatorfreie Kondensation von Pyrrol und Aldehyden bietet einen äußerst einfachen Zugang zu neuartigen Corrolen [Gl. (1); Ar = C6F5, 2,6-F2C6H3, 2,6-Cl2C6H3]. Das Pentafluorphenyl-substituierte Produkt (Ar = C6F5) ist eine exzellente Vorstufe für andere Derivate, einschließlich eines ionisch…
A three-dimensional network with one-dimensional channels (see picture) has been self-assembled from the nickel(II) complex of cyclam and 1,3,5-benzenetricarboxylate in water through hydrogen-bond formation. The channels have an appropriate diameter (10.3 Å) to include D-glucose with a formation constant of Kf=(1.38±0…
Addition of Nd, Tb, or Dy to amorphous Ti–O thin films is found to improve the dielectric properties of the films. Specifically, substitution of 10–30 at. % of the dopant for Ti is found to dramatically decrease the leakage current, increase the breakdown voltage, and yet retain the relatively high dielectric constant…
It is completely plausible that unmodified materials of natural origin, such as the native macromolecules cellulose or starch, are biodegradable. If these materials are modified then degradation may, depending on the degree of modification, be more difficult or even impossible. In the same manner synthesized macromole…
The thermal stability and relaxation processes in hydrogen free diamond-like-carbon films with different sp3 fractions (40%, 60%, and 80%) are comparatively studied for the first time by visible Raman spectroscopy. The 80% sp3 film is very stable under annealing in the entire temperature region investigated (300–1270…
The formation of boron nitride (BN) nanotubes via a solid-state process is demonstrated. The nanotubes are produced by first ball-milling hexagonal BN powder to generate highly disordered or amorphous nanostructures, followed by annealing at temperatures up to 1300 °C. The annealing leads to the nucleation and growth…
Porous alumina membranes with ordered pore arrays were prepared electrochemically from Al metal in C2H2O4 or H2SO4. Photoluminescence (PL) measurements show that a blue PL band occurs in the wavelength range of 400–600 nm. This band originates from singly ionized oxygen vacancies (F+ centers) in porous alumina membran…
Hydrogen bonds between urea units allow self-organization of π systems in mono- and bithiophenes into fibers as shown schematically. In these fibers there is a surprisingly high mobility of charge carriers as determined by pulse-radiolysis time-resolved microwave conductivity measurements.
Electromigration in 0.15–10 μm wide and 0.3 μm thick Cu lines deposited by physical vapor deposition has been investigated using both resistance and edge displacement techniques in the sample temperature range 255–405 °C. For wide polycrystalline lines (>1 μm), the dominant diffusion mechanism is a mixture of g…
By the attachment of interacting laser dyes to the chain ends and focal point of a dendritic macromolecule it is possible to funnel energy harvested by the large peripheral antenna of the dendrimer (see picture on the left) efficiently and directly to the central fluorescent core (picture in the middle) by a process t…
To understand the near-interface magnetism in manganites, ultrathin films of La0.67Sr0.33MnO3 were grown epitaxially on single-crystal (001) LaAlO3 and (110) NdGaO3 substrates. The temperature and magnetic field-dependent film resistance is used to probe the film’s structural and magnetic properties. A surface and/or…
Thin films of quantum size ZnO particles were fabricated by electrophoretic deposition from stable colloidal suspensions. The average particle size and hence the optical properties can be tailored by controlling the aging time and temperature of the suspensions. Thin films prepared by electrophoretic deposition exhibi…
The solvent-free, catalyst-free condensation of pyrrole and aldehydes provides an extremely facile synthetic pathway to novel corroles [Eq. (1); Ar=C6F5, 2,6-F2C6H3, 2,6-Cl2C6H3]. The product containing pentafluorophenyl groups is an excellent precursor of other derivatives, including an ionic, water-soluble corrole.
Although progress has been made in the ab initio simulation of lattice dynamics in semiconducting crystals, information about the relaxation of nonequilibrium lattice vibrations remains incomplete. This work studies the relaxation times of room-temperature thermal phonons through measurements of thermal conduction alo…
Optical birefringence measurements are used to characterize how the molecular order of spider (Nephila clavipes) major ampullate silk is affected by linear spinning rate, by the extent of post-spin drawing, and by post-spin drawing rate. Results are interpreted qualitatively in terms of a simple microstructural model,…
An aliphatic/aromatic polyester blend has been dealt with in this study. As an aliphatic polyester, poly(butylene succinate) (PBS) was used, which is thought to possess biodegradability, but it is relatively expensive. It has been blended with poly(butylene terephthalate) (PBT) in order to obtain a biodegradable blend…
The interactions between soluble collagen (C) from calf skin and poly(acrylic acid) (PAA) were studied. Mixing aqueous solutions of collagen and PAA, at various pH values (2.5–4), leads to the formation of complexes that precipitate in the form of insoluble aggregates. The effects of mixture composition, pH, and ionic…
Using first principles density functional calculations, gold monatomic wires are found to exhibit a zigzag shape which remains under tension, becoming linear just before breaking. At room temperature they are found to spin, what explains the extremely long apparent interatomic distances shown by electron microscopy.Th…
The temperature dependence of the elastic stiffness constant c 55 in [N(CH 3 ) 4 ] 2 ZnBr 4 single crystals has been measured using Brillouin scattering and the ultrasonic pulse echo overlap technique. The elastic constant c 55 was found to soften strongly in both the paraelastic and ferroelastic phases. Despite the f…