Materials Literature
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We describe the preparation of six diketones based on the frameworks of five bis-naphthoporphyrins and one perinaphthoporphyrin. All diketones derive from meso-tetraarylporphyrins having incorporated two carbonyl groups, each one connected to one beta-pyrrole carbon and one ortho carbon atom from a meso-aryl group. Th…
Abstract Reaction of α‐Na 12 (As 2 W 15 O 56 ) with Fe II in 1 M NaCl solution followed by air oxidation yields αααα‐H 2 Na 14 [(NaOH 2 ) 2 Fe III 2 (As 2 W 15 O 56 ) 2 ] (Na 2 ), the arsenic analogue of the divacant lacunary sandwich, αααα‐H 2 Na 14 [(NaOH 2 ) 2 Fe III 2 (P 2 W 15 O 56 ) 2 ] (Na 1 ). This complex (Na…
The synthesis and characterization of nanoparticle-cored dendrimers (NCDs), consisting of a metal core capped by arylpolyethers terminated with ester or carboxylate groups, are reported. These NCDs, comprising nanometer-sized gold clusters at the core and organic dendrons radially connected to the gold core by gold-su…
The three-dimensional (3D) structure of the huge quasicrystal approximant nu-AlFeCr (space group P6(3)/m, a = 40.687 and c = 12.546 A) was solved by electron crystallography. High-resolution transmission-electron-microscopy (HREM) images and selected-area electron diffraction patterns from 13 different zone axes were…
A series of tris(2-pyridylmethyl)amines including one and two asymmetric centers were synthesized in a stereo-controlled fashion as potential ligands of lanthanide cations. The reaction of chiral pyridylethyl methanesulfonates and bis(pyridylmethyl)amines occurred via an S(N)2 mechanism with complete inversion of asym…
Individual multiwalled carbon nanotubes were mounted on tungsten support tips in a scanning electron microscope equipped with a nanomanipulator. It was possible to select the diameter of the nanotube to align the nanotube with respect to the tip axis and to tune the contact length of the nanotube and the support tip.…
Self-trapped hole (STH) induced by ArF laser irradiation in silica glass $(a\ensuremath{-}{\mathrm{SiO}}_{2})$ was investigated by the electron-spin resonance method. In order to observe the relation between the yield of STH and structural disorder of the glass, samples with different fictive temperatures ${T}_{f},$ w…
This paper describes the synthesis and characterization of a new series of sterically nondemanding, dicationic porphyrins that exhibit novel DNA-binding interactions. Cationic porphyrins continue to be the focus of a great deal of effort because of the promise they have for use in photodynamic, antiviral, and anticanc…
Results from a novel approach which uses protein crystallography for the screening of a low affinity inhibitor fragment library are analyzed by comparing the X-ray structures with bound fragments to the structures with the corresponding full length inhibitors. The screen for new phospho-tyrosine mimics binding to the…
Abstract The 30–100 nm primary particles of mesoporous silica have been conveniently synthesized from a highly dilute aqueous solution of CnTAMX–sodium silicate.
We present the experimental and theoretical evidence that a new Sm X phase made of asymmetric bent-shaped molecules has a layered, nontilted, optically uniaxial and polarly ordered structure with random direction of the layer polarization. The randomness results from the sign degeneracy of the difference in polarizati…
Well-ordered mesostructured/mesoporous silica nanofibers have been synthesized in a quiescent dilute aqueous cationic surfactant/silica precursor reaction mixture under strong acidic conditions. These nanofibers have diameters ranging from 50 to 300 nm and lengths up to millimeters. Transmission electron microscopy (T…
A novel cross-linked siloxane-based solid polymer network has been synthesized by the hydrosilylation of polymethylhydrosiloxane (PMHS) partly substituted with oligo(ethylene glycol) methyl ether side groups and a α,ω-diallyl poly(ethylene glycol) cross-linking reagent. The ionic conductivities of the networks doped w…
Herein, we report on direct fabrication of silver circuit patterns on polyimide resin, the method of which relies on potassium hydroxide-induced chemical modification of the polyimide surface to introduce carboxylic acid groups and incorporation of silver ions through subsequent ion exchange followed by UV-irradiation…
We show that large amplitude, coherent acoustic phonon wavepackets can be generated and detected in In$_x$Ga$_{1-x}$N/GaN epilayers and heterostructures in femtosecond pump-probe differential reflectivity experiments. The amplitude of the coherent phonon increases with increasing Indium fraction $x$ and unlike other c…
The objective of this study was to develop biodegradable polypeptide-lipid conjugates for the design of polymer-coated long-circulating liposomes (LCL). Lipid conjugates of poly(hydroxyalkyl L-asparagine/L-glutamine) were synthesized and incorporated into 0.15 microm dipalmitoyl phosphatidylcholine (DPPC)-cholesterol…
Magnetism of layered cobaltites Na$_x$CoO$_2$ with $x$ = 0.6 and 0.9 has been investigated by a positive muon spin rotation and relaxation ($μ^+$SR) spectroscopy together with magnetic susceptibility and specific heat measurements, using single crystal samples in the temperature range between 250 and 1.8 K. Zero-field…
Ion conducting $(CaO)_x(SiO_2)_{1-x}$ glasses and melts show a threshold behaviour in dc conductivity near $x=x_t=0.50$, with conductivities increasing linearly at $x>x_t$. We show that the behaviour can be traced to a rigid ($x<0.50$) to floppy ($x>0.50$) elastic phase transition near $x=x_t$. In the floppy phase, co…
We demonstrate that weak external magnetic fields generate dissipationless spin currents in the ground state of systems with spiral magnetic order. Our conclusions are based on phenomenological considerations and on microscopic mean-field theory calculations for an illustrative toy model. We speculate on possible appl…
Classical molecular dynamics simulations are used to study the structure of densified germanium dioxide ($GeO_2$). It is found that the coordination number of germanium changes with increasing density (pressure) while pressure released systems do not exhibit a marked change in local structure as compared to the virgin…