Materials Literature
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Oxidation of a series of TTF vinylogues has been investigated in acetonitrile and dichloromethane. Depending on the substituent and the solvent, two single-electron transfers or one two-electron process was observed. Density functional modeling calculations and detailed analysis of the electrochemical behavior show th…
We use a density-functional based tight-binding method to study diamond growth steps by depositing dicarbon species onto a hydrogen-free diamond (110) surface. Subsequent C_2 molecules are deposited on an initially clean surface, in the vicinity of a growing adsorbate cluster, and finally, near vacancies just before c…
The adequate interpretation of scanning tunneling microscopy (STM) images of the clean Si(001) surface is presented. We have performed both STM observations and {\it ab initio} simulations of STM images for buckled dimers on the clean Si(001) surface. By comparing experimental results with theoretical ones, it is reve…
The distinction between absolute and convective instabilities is well known in the context of hydrodynamics and plasma physics. In this Letter, we examine an epitaxial crystal growth model from this point of view and show that a strain-induced step bunching instability can be convective. Using analytic stability theor…
It has been proposed recently that localized excitations and recombinations in the silanone Si O bond is the source for the red photoluminescence (PL) observed for oxygen-exposed porous silicon (PS). One concern with this proposal is the expected low chemical stability of the Si O bond. By using quantum chemistry calc…
Hexagonal (MCM-41) mesoporous materials were synthesized at 23 °C using hexadecyltrimethylammonium bromide (HDTMA) and tetramethyl-orthosilicate (TMOS) or Na-silicate. Products with (as-synthesized and dried at 23 or 70 °C) HDTMA removed significant amounts of trichlorethylene and tetrachloroethylene from water, simil…
Poly(ethylene succinate) (PES) ultrathin films with an initial thickness of approximately 100 nm were prepared by the solution cast method on either cover glass or freshly cleaved mica as the substrate. The ultrathin films were then melt-crystallized at a given temperature for a certain period of time. The surface mor…
Genetically engineered spider dragline silk protein was modified to incorporate methionines flanking the beta-sheet forming polyalanine regions. The methionines could be selectively chemically oxidized and reduced. This chemical change altered the bulkiness and charge of the sulfhydryl groups, and in turn, the beta-sh…
Crystal growth rates of melt-crystallized poly(ethylene succinate) (PES) with a number-average molecular weight Mn of 21,100 and polydispersity of 1.86, respectively, were studied in an extensive temperature range. On the basis of secondary nucleation theory, only one transition between regime III and regime II was fo…
Theoretical investigations of surface-state electron dynamics in noble metals are reported. The dynamically screened interaction is computed, within many-body theory, by going beyond a free-electron description of the metal surface. Calculations of the inelastic linewidth of Shockley surface-state electrons and holes…
The injection of spin polarized electrons from ferromagnetic metals (Fe and Co) into gallium nitride (GaN) via scanning tunneling microscopy (STM) is demonstrated. Electrons from STM tips are injected into the semiconductor. Net circular polarization of the emitted light is observed, which changes sign on reversal of…
<div class="htmlview paragraph">This paper describes the results of the computational analysis of UltraLight Steel Auto Body (ULSAB) crash simulations that were performed using advanced material modeling techniques. The effects of strain-rate sensitivity on a high strength steel intensive vehicle was analyzed. F…
A ultra-high sensitivity holographic Ultimate emulsion (10nm grains) has been produced, which allows the realization with short exposure times of bright, large sized, with wide view angle and full color holograms of fragile still subjects of monochromatic pulsed reflection holograms of alived subjects. The high transp…
A general synthetic approach leading to well-defined, water-soluble gold nanoparticles is described that involves a simple, interfacial ligand exchange reaction between a 1.4 nm phosphine-passivated precursor and an anionic or cationic thiol-containing ligand. We demonstrate the utility of this route by synthesizing w…
Blends of poly(vinyl chloride) (PVC) with different ratios of chlorinated polyethylene (CPE) were degradated by the thermogravimetric method under dynamic conditions (50–600°C) in an inert atmosphere. The effect of the miscibility and composition of the PVC/CPE blends on the thermal stability were investigated. DSC cu…
We propose a method to simulate a-Si and a-Si:H using an ab initio approach based on the Harris functional and thermally amorphisized periodically continued cells with at least 64 atoms, and calculate their radial distribution functions. Hydrogen incorporation was achieved via diffusive random addition. The electronic…
High-quality crystalline Si0.75Ge0.25 alloy crystals were implanted with 70 keV Er+ ions at 550 °C to a fluence of 1019 m−2. In situ Rutherford backscattering/channeling spectrometry with a 500 keV He2+ beam revealed Er atoms located on regular lattice sites of the host matrix. Angular scans taken around the 〈100〉, 〈1…
The emergence of complex form in living and nonliving systems remains a deep question for scientists attempting to understand the origins and development of shape and structure. In recent years, biologists and physicists have made significant advances in explaining fundamental problems in fields such as morphogenesis…
Nanokomposite auf Metalloxidbasis – diese neuartigen supramolekularen Einheiten wurden in einer Eintopfreaktion hergestellt und sogar quervernetzt. Die supramolekulare Einheit (siehe Bild) besteht aus einer paramagnetischen, ikosaedrischen Kapsel des Typs {MoFe} als Wirtstruktur, die einen Elektronen speichernden, nic…
In Konzentrationen bis hinab zu 0.3 Gew.-% bildet eine neuartige Familie von Bisharnstoffdicarbonsäuren ein Hydrogel (siehe Bild). Der Aggregationszustand (Vesikel, Gel oder Faser) hängt ab vom pH-Wert, von der Ionenstärke und vom Molekulargewicht des Gelbildners. Somit lassen sich die Eigenschaften des Gels durch Des…