Materials Literature
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We measure the dielectric dispersion of CdSe nanocrystal colloids and show the existence of large dipole moments of 25 and 47 debye for 34 and 46 \AA{} diameter nanocrystals, respectively. The magnitude is consistent with the expected spontaneous polarization of the bulk wurtzite CdSe lattice and implies a potential d…
For Heck reactions and hydroformylations dendrimers loaded with palladium (for example 1) or rhodium are suitable catalysts. A dendrimer with 16 outer bis(diphenylphosphinomethyl)amino end groups has been synthesized in one step by phosphinomethylation of a commercially available polyamino-dendrimer and converted into…
The desorption kinetics of molecular beam deposited ultrathin films of CC${\mathrm{l}}_{4}$ and amorphous solid water (ASW) are studied. Overlayers of ASW impede CC${\mathrm{l}}_{4}$ desorption until the onset of crystallization, whereupon the CC${\mathrm{l}}_{4}$ desorbs abruptly. The abrupt desorption occurs through…
High molecular weight block copolymers can be viewed as macromolecular surfactants when blended with thermodynamically incompatible homopolymers. This Letter describes the formation of polymeric bicontinuous microemulsions in mixtures containing a model diblock copolymer and two homopolymers. Although we attribute dev…
A relative molar mass of 40 000 and diameter of 4 nm are the remarkable dimensions of the title anion, which is, together with its LaIII analogues, the most massive inorganic water-soluble cluster so far observed (see picture on the right). These polyanions with 164 metal atoms are easily synthesized in fair yield. Th…
Abstract The design and performance of a new instrument, based on improved Penning ion guns [1] for etching and coating samples for SEM and LM in a single vacuum chamber, are described. The instrument is based on an existing high resolution ion beam coating system, which is capable of producing high quality ultra-thin…
Abstract Cu2O is a semiconductor with a band gap of 2.17eV, and its crystal structure is simple cubic. Oxygen atoms form a bcc structure and each oxygen atom is tetrahedrally coordinated by copper atoms, which makes copper linearly coordinated by two oxygen atoms. The structure of cuprite is interesting because the ch…
We report on a study of mixtures of octylcyanobiphenyl (8CB) and equal amounts of two chiral agents (CE2 and CB15) as a function of chiral pitch (concentration). Bulk studies reveal a widening cholesteric temperature range with increasing chirality. The first order cholesteric-isotropic (Ch-I) transition shifts margin…
Diffuse reflectance infrared spectroscopy and static secondary ion mass spectrometry (SIMS) were employed to study the surface species formed during the adsorption and reaction of propylene on a copper-exchanged ZSM-5 catalyst. Propylene showed characteristics of chemisorption on Cu-ZSM-5 at room temperature and total…
A new effect of illumination on ionic conductivity and activation energy of migration of mobile Ag + cations in RbAg 4 I 5 superionic crystals has been detected and studied. Reversible changes in the ionic conductivity due to illumination of superionic crystals are caused by reversible changes in the structure of elec…
We propose a model describing the destruction of metals under ultrashort intense laser pulses when heated electrons affect the lattice through the direct electron-phonon interaction. The metal consists of hot electrons and a cool lattice. The lattice deformation is estimated immediately after the laser pulse up to the…
Abstract A new family of main‐chain liquid crystal polymers containing azomethine units have been synthesized and characterized. Our attention has been focused on their strong tendency to generate macrocyclic dimers (AB) 2 constituted with two mesogenic rods and siloxane spacers. In favourable conditions (diluted solu…
The racemic mixture of cholesteryl chloride(ChCI) and cholesteryl myristate(ChMy) exhibit a compensated nematic phase at critical concentration and temperature. The mixtures of concentration from 1 to 10% ChCl and 88% to 100% of ChCl exhibit smectic phase and cholesteric phase respectively. The middle concentrations a…
The data on the dynamic (spall) strength for more than 30 steels are reported. These data were interpreted in terms of the fracture mechanics. The experimental data are interpreted in terms of the energy-based spall theory which predicts the dependence of the spall strength on the strain rate in the spall plane. Even…
The stabilization of the LaNi 5 H 6 hydride was performed by poisoning the surface with CO or SO 2, in gaseous or liquid phase. The enhancement of the retention time of hydrogen in the hydride was confirmed for the SO 2 treatment, if employed in a liquid phase, compared to the performance of the CO surface treatment.…
Abstract The understanding of damage initiation and evolution mechanisms is essential to model projectile penetration into ceramics. Two original test configurations have been developed to visualize, in real time, the initiation and propagation of damage. Results obtained are adaptable to a more conventional a m o u r…
Porous Silicon was formed on mono- and poly-crystalline Si substrates by stain etching in aqueous HF/HNO3 solutions. Optical properties of the resulting films have been investigated by reflectance spectroscopy and have been related to process parameters, e.g. HF, HNO3 concentration and etching time. Film morphology ha…
A poly(vinyl alcohol)−alumina hydrate composite film prepared by using a sol−gel process was transparent in the visible region. The composite film was insoluble in water after being heated at about 100 °C but exhibited hydrophilicity. These characteristics are suitable for the deposition of Fe 2 O 3 · n H 2 O in the f…
We report in this paper the first theoretical treatment of kinetic and equilibrium chemical processes of the atmospheric corrosion of nickel performed with the multiregime GILDES model. The formulation for exposure of nickel to sulfur dioxide in humidified air involves 67 reactions for 35 species and includes a repres…
Conference Article| August 01 1997 PRINCIPLES OF PROTEIN STRUCTURE Clare Sansom; Clare Sansom 1Department of Crystallography, Birkbeck College, Malet St., London WC1E 7HX +44 (171) 631-68002Venus Internet Ltd., 24 Denmark St. London WC2H 8NJ +44 (171) 240 5858 Search for other works by this author on: This Site PubMed…