Materials Literature
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A through-space superexchange mechanism appears to be responsible for charge recombination (CR) following photoexcitation and charge separation (CS) in rotaxanes containing zinc porphyrin and C60 moieties (see picture), as suggested by the low activation energy of this process. Furthermore, the charge-separated state…
Non-tetrahedron-forming L2 ligands insert into a resolved ΔΔΔΔ-[Ga4L16]12− tetrahedral assembly of labile metal and ligand components without compromising its supramolecular structure (see scheme). Preservation of the chirality of the initial architecture verifies its structural memory.
Gentle heating of crystalline 2,5-dibromo-3,4-ethylenedioxythiophene affords a highly conducting, bromine-doped poly(3,4-ethylenedioxythiophene) (PEDOT). The conductivity of the polymer can be further increased by doping with iodine. By using this approach, thin films of PEDOT with a conductivity as high as 20 S cm−1…
Vitrification of a supercooled liquid is often characterized by the hypothetical kinetic instability point, the Vogel-Fulcher temperature T0, and the thermodynamic one, the Kauzmann temperature T(K). The widely believed relation T0 congruent with T(K) is regarded as the supporting evidence of a direct connection betwe…
Excitons in quasi-one-dimensional semiconductors may lower the optical transition energies by a substantial amount. To quantify the effect in carbon nanotubes, we apply a simple variational approach. In excitonic units, a power law with exponent \ensuremath{\sim}-0.6 is obtained for the binding energy dependence on na…
Here we report an unconventional magnetic and transport phenomenon in a layered cobalt oxide ${\mathrm{Na}}_{x}{\mathrm{CoO}}_{2}.$ Only for $x=0.75,$ a magnetic transition of the second order was clearly detected at ${T}_{m}\ensuremath{\sim}22\mathrm{K}$ where an apparent specific-heat jump, an onset of extremely sma…
The magnetic, transport, and structural properties of (Ga,Cr)As are reported. Zincblende Ga$_{1-x}$Cr$_{x}$As was grown by low-temperature molecular beam epitaxy (MBE). At low concentrations, x$\sim$0.1, the materials exhibit unusual magnetic properties associated with the random magnetism of the alloy. At low tempera…
We introduce a new linear response method to study the lattice dynamics of materials with strong correlations. It is based on a combination of dynamical mean field theory of strongly correlated electrons and the local density functional theory of electronic structure. We apply the method to study the phonon dispersion…
Monte Carlo simulations have been used to investigate the dynamic phase behavior of a classical Heisenberg spin system with a bilinear exchange anisotropy in a planar thin film geometry. Studies of the field amplitude, frequency and temperature dependence show dynamic phase transitions in films subject to a pulsed osc…
The crystallization behavior of three double crystalline diblock copolymers containing poly(ε-caprolactone) and poly( p -dioxanone) has been studied via differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray scattering (WAXS). Crystallization and melting temperatures and enth…
Combinations of a polyanion and a polycation, with different molar masses but narrow molar mass distributions, are employed to construct thin films by the polyelectrolyte multilayering technique. All polyelectrolytes are assembled in the presence of added salt. Even highly charged polymers in the 10 4 Da range of mola…
Crowning glory: The L-shaped [Ln(H2O)2(α-AsW9O33)]6− (Ln=lanthanide) building unit provides an elegant approach to develop crown-shaped structures of [{Ln(H2O)2(α-AsW9O33)}n]6n− (n=even number of ≥4) which can encapsulate a cation. The watermill-propeller structure, left, is a K+ ion encapsulated by six [α-AsW9O33]9−…
With evolution, Nature has ingeniously succeeded in giving rise to an impressive variety of inorganic structures. Every organism that synthesizes biogenic minerals does so in a form that is unique to that species. This biomineralization is apparently biologically controlled. It is thus expected that both the synthesis…
We present here the results of the room-temperature dielectric measurements and Rietveld analysis of the powder x-ray diffraction data on $(1\ensuremath{-}x)[\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}]\ensuremath{-}x{\mathrm{PbTiO}}_{3}(\mathrm{PMN}\ensuremath{-}x\mathrm{PT})$ in the compositi…
Recently, Zheng and Jiang [Phys. Rev. Lett. 88, 045503 (2002)]] have proposed that multiwalled carbon nanotubes could be the basis for a new generation of nano-oscillators in the several gigahertz range. In this Letter, we present the first molecular dynamics simulation for these systems. Different nanotube types were…
Gold nanoparticles have been conformally coated with amorphous silica (using a sol-gel method) and then an organic polymer (via surface-grafted, atom transfer radical polymerization) to form spherical colloids with a core-double-shell structure. The thickness of silica and polymer shells could be conveniently controll…
Arrays of electrical devices with each comprising multiple single-walled carbon nanotubes (SWNT) bridging metal electrodes are obtained by chemical vapor deposition (CVD) of nanotubes across prefabricated electrode arrays. The ensemble of nanotubes in such a device collectively exhibits large electrical conductance ch…
In this paper we describe all the Voronoi and Delone tiles arising in tilings of point sets Σ(Ω) (‘quasicrystals’) built by the standard projection of the root lattice of type A 4 onto a two-dimensional plane spanned by the roots of the Coxeter group H 2 (dihedral group of order 10). The acceptance window Ω for Σ(Ω) i…
Abstract To improve the solubility in organic solvent of chitosan, o ‐benzoylchitosan was synthesized by acylation with benzoyl chloride and then used in the reaction with 2‐chloro‐1,3,2‐dioxaphosphospholane (COP) to prepare phosphorylcholine‐terminated o ‐benzoylchitosan (PC‐BCS). PC‐BCS had a structure with a phosph…
Abstract This paper presents laboratory/field results and lessons learned from a North Sea field where a novel emulsified scale inhibitor was deployed via bullhead squeeze treatments in four low water cut, sand screened wells. The field is a subsea development within the UK sector of the North Sea. These were the firs…