Materials Literature
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Vertically aligned carbon nanotubes were grown on iron-deposited silicon oxide substrate by thermal chemical vapor deposition of acetylene. The carbon nanotubes have no encapsulated iron particles at the closed tip and a bamboo structure in which the curvature of compartment layers is directed to the tip. A base growt…
Scanning electron microscopy (SEM) is traditionally the Cinderella of electron microscopy, often seen as a playground for biologists and other disciplines remote from physics, and overshadowed by high resolution TEM, dominated by eminent scientists concerned with atomic structure and quantitative analysis. When Max Kn…
An increase of the critical resolved shear stress of Invar alloys (Invar hardening) with a lowering temperature is explained. The effect is caused by a growth of the exchange interaction between dangling $d$-electron states of dislocation cores and paramagnetic obstacles (e.g., Ni atoms in FeNi alloys) which occurs be…
We describe a new class of nanoscale structured metals wherein the effects of quantum confinement are combined with dispersive metallic electronic states to induce modifications to the fundamental low-energy microscopic properties of a three-dimensional metal: the density of states, the distribution of Fermi velocitie…
The actual mechanism of polarization switching in ferroelectrics remains a puzzle for many decades, since the usually estimated barrier for nucleation and growth is insurmountable ("paradox of the coercive field"). To analyze the mechanisms of the nucleation we consider the exactly solvable case of a ferroelectric fil…
This paper is mostly a collection of ideas already published by various authors, some of them even a long time ago. Its intention is to bring the reader to know some rather unknown papers of different fields that merit interest and to show some relations between them the author claims to have observed. In the first se…
We report on the experimental observation of multipolar plasmon excitations in lithographically designed elongated silver particles. In contrast to spheres, where the extinction bands of the respective multipolar plasmons overlap considerably to form a broad spectrum, spectrally well-separated extinction bands corresp…
Fiber reinforcement of soils can reduce displacements due to swelling and shrinking of expansive soils. Described in this paper is a series of laboratory tests performed on fiber reinforced and non-reinforced samples of expansive clay to determine the potential for using fiber reinforcement to resist swell displacemen…
Mechanistic enzymologists have long debated how enzymes catalyze the abstraction of an unactivated C−H group. Citrate synthase, due to its ability to catalyze this abstraction and its central role in the respiratory cycle, has been extensively studied both experimentally and theoretically. Despite this scrutiny, the q…
Two new 1-D compounds of Rh2(O2CCF3)4 bridged by dicyano linkers were synthesized and structurally characterized. [Rh2(O2CCF3)4(DM-DCNQI)]∞·(C6H6) (1) and [Rh2(O2CCF3)4(DCNNQI)]∞·(C7H8) (2) (DM-DCNQI = 2,5-dimethyl-N,N‘-dicyanoquinone diimine, DCNNQI = N,N‘-dicyanonaphthaquinone diimine) exhibit different chain motifs…
Adsorption of poly(amidoamine) (PAMAM) dendrimers from dilute solution onto cleaned gold has been studied in-situ by a quartz crystal microbalance technique. All experiments were carried out at 21 °C, with either anhydrous ethanol or deionized water as solvent. In ethanol, the equilibrium frequency shifts, proportiona…
Novel radical addition chemistry, involving addition of CF 3 • radicals to octafluoro[2.2]paracyclophane (AF4), leads to formation of an unprecedented new class of dimeric CF 3 -substituted AF4 derivatives. These chemically stable, but highly sterically constrained compounds undergo a clean thermal homolytic retro pro…
PET-type polymers have been prepared in the presence of a variety of potential branching agents, such as trimesic acid, and with the control of branching using an end-capping agent, benzyl alcohol. The polymers synthesized have been characterized by dilute solution viscometry, end group analysis, light scattering ( M̄…
The influence of the characteristic nanostructure of semicrystalline polymers on the segmental dynamics has been studied by dielectric spectroscopy (DS) in poly(ethylene naphthalene-2,6 dicarboxylate) (PEN) samples with different degree of crystallinity. In the investigated temperature range (from −100 to +200 °C), th…
Libraries of liquid-phase catalyst precursor solutions were printed onto iridium-coated silicon substrates and evaluated for their effectiveness in catalyzing the growth of multiwalled carbon nanotubes (MWNTs) by chemical vapor deposition (CVD). The catalyst precursor solutions were composed of inorganic salts and a r…
The epoxidation of alkenes with 30% aqueous hydrogen peroxide is catalyzed efficiently by methyltrioxorhenium (MTO) in the presence of pyridine additives. The addition of 1-10 mol % of 3-cyanopyridine increases the system's efficiency for terminal and trans-disubstituted alkenes resulting in high isolated yields of th…
Correlations between intermolecular forces and ultrafiltration measurements for a thin polysulfone film and membranes modified for increased hydrophilicity by graft polymerization of 2-hydroxyethyl methacrylate and a model protein (hen egg-white lysozyme, Lz) suggest that altering either the chemistry of the polymer s…
Lattice-matched ZnCdSe 2 concentric epilayer shells up to 50 Å in thickness have been grown on InP core quantum dots (QDs). The quality of the epitaxially grown shells was monitored by absorption and emission spectra and transmission electron microscopy (TEM). Shell growth was shown to be controllable and was consiste…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Catalytic-Assembly Solvothermal Route to Multiwall Carbon Nanotubes at a Moderate TemperatureYang Jiang, Yue Wu, Shuyuan Zhang, Cunyi Xu, Weichao Yu, Yi Xie, and Yitai QianView Author Information Department of Chemistry and Structure Research Laboratory University of…
The mixed manganite-cuprate CaCu3Mn4O12 is found, using density functional methods, to be a narrow gap (90 meV calculated) ferrimagnetic semiconductor. Cu (formally S=1/2) antialigns with Mn (formally S=3/2), and the net spin moment is 9 μ_B consistent with the formal spins. Holes have Cu d_{xy}-O p_σ (i.e. antibondin…