Materials Literature
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A synthetic pathway is described to construct "in bulk" two-dimensional (2D) polymers shaped as molecular sheets. A chiral oligomeric precursor is used that contains two reactive sites, a polymerizable group at one terminus and a reactive stereogenic center near the middle of the molecule. The bulk reaction yields bil…
The functional photoswitchable systems 1–3 and 12–15 display pronounced photochromic properties; the bis-pyridinium derivative 1 represents a prototype of a switched molecular wire which may be converted from an open unconjugated form to a closed electron-conducting state.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBorohydride reduction of cobalt ions in water. Chemistry leading to nanoscale metal, boride, or borate particlesGeorge N. Glavee, Kenneth J. Klabunde, Christopher M. Sorensen, and George C. HadjipanayisCite this: Langmuir 1993, 9, 1, 162–169Publication Date (Print):January 1…
A thermochemical kinetics analysis has been carried out for growth on the (100)-(2xl):H diamond surface using a pair of previously proposed mechanisms which operate sequentially. Half of the growth on such a surface is accounted for by insertion into dimer bonds, while the other half is accounted for by addition acros…
X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry were used to study the thermal stability of highly supersaturated nanocrystalline FexCu100−x alloys (10≤x≤95) synthesized by mechanical alloying. Alloys with x<60 exhibit single-phase fcc structure while single-phase bcc…
Physisorption measurements of nitrogen and oxygen reveal that MCM-41 has a well defined mesoporous structure and is a highly promising model adsorbent.
One of the fascinating aspects of the field of ferroelectric ceramics is its interdisciplinary nature. This aspect is also a source of difficulty for the people working in the field. In a successful t
Chemical bonding, chemical reaction, and the interfacial structure of metal/ceramic interfaces are reviewed with particular emphasis placed on Al and Ti alloys bonded to Al 2 O 3 and SiC ceramics. It is shown that a number of important properties of metal/ceramic interfaces such as the wetting behaviour and work of ad…
The biological activity of porphyrins and related tetrapyrroles in proteins may be modulated by nonplanar conformational distortions; consequently, two aspects of nonplanarity have been investigated in the highly nonplanar octaalkyltetraphenylporphyrins (OATPPs). In the first part, the effect of the central metal ion…
A systematic investigation of the IR and Raman spectra of pure and Al-, B-, Ti- and Fe-substituted silicalites in the SiO stretching region (1500–700 cm–1) is presented. As well as the characteristic stretching modes of the skeleton, silicalites containing hydroxylated nests show also broad bands at ca. 960 cm–1(IR) a…
Abstract Polymer microspheres and fibers are formed with a versatile new process, precipitation with a compressed fluid antisolvent. By spraying a 1 wt. % polystyrene in toluene solution into CO 2 through a 100‐μm nozzle, microspheres are formed with diameters from 0.1 to 20 μm as the CO 2 density decreases from 0.86…
In one fell swoop eleven building blocks— five ligands and six metal ions—self-assemble to give the discrete Cu1 complex 1 shown schematically on the right (phenyl substituents at the two central ligands and the methyl substituents at the three outer ligands have been omitted). The formation of 1 demonstrates how mole…
We present the results of our computer-simulation study on the ${\mathrm{Fe}}^{3+}$ incorporation in ${\mathrm{KTaO}}_{3}$. We find that ${\mathrm{Fe}}^{3+}$ ions enter the crystal lattice by means of a self-compensation-type reaction, i.e., by creation of ${\mathrm{Fe}}_{\mathrm{K}}^{3+}$ and ${\mathrm{Fe}}_{\mathrm{…
Abstract The Cuprammine exchanged NaX zeolite (M = 17846, cubic, space group Fd [unk] m , a = 24,915(1) Å, V = 15466 Å 3 ) is investigated for site occupancy by the cuprammonium ions. Intensity data are resolved into component hkl contributions by treating the known framework sites as conventional heavy atoms. Differe…
A study was undertaken to determine the influence of steam-pressure-refining levels on red maple (Acer rubrum L.) wood chips fabricated into medium density fiberboard (MDF) test boards using four urea-formaldehyde resin levels. Red maple chips were fiberized using a pressurized, double-disk refiner operating at six re…
Magnesium alloys have high strength/weight ratios, but poor corrosion resistance affects the viability of increased magnesium usage in aerospace and other applications. This review approaches the problem of magnesium corrosion from the standpoint of corrosion science by discussing the thermodynamics, kinetics, and mic…
A model describing the electronic structure of transition metal atoms in Hume-Rothery alloys and quasi-crystals is constructed by adding to the classical Anderson Hamiltonian a potential V B ( K ) that describes the diffraction of conduction electrons by Bragg planes near the Fermi surface. Strong deviation from the v…
Hornification is the loss of swelling of the fibre wall resulting from a drying-and-rewetting cycle: it is associated with a stiffening of the fibres which reduces their ability to form inter-fibre bonds. In this paper,factors affecting the extent of hornification are examined using the solute exclusion technique to m…
Tetrathiafulvalene behaves as a catalyst in mediating reaction cycles which feature electron transfer reactions, radical cyclisations and nucleophilic displacements.
We report the first observation of cholesteric blue phases in chiral anisotropic polymer networks. In two-component mixtures of a chiral and a non-chiral diacrylate, we observed typical textures of BPI, BPII and BPIII phases. By photopolymerization of these materials at constant temperature we obtained blue phase netw…