Controlled Ring‐Opening Polymerization of Lactide and Glycolide
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Fabrication and near-infrared photothermal conversion characteristics of Au nanoshells
In this letter, gold nanoshells with a size of ∼20nm were prepared by a wet-chemical synthesis method and the surface plasmon absorption band of gold was tuned from visible to near-infrared. The gold nanoshell hydrosol demonstrated excellent photothermal conversion property. The temperature of the hydrosol was increas…
On potential applications of metamaterials for the design of broadband phase shifters
Abstract The possible design of phase shifters with reduced frequency dispersion using combined sections of forward‐wave (FW) and backward‐wave (BW) transmission lines is discussed. It is shown that inclusion of backward‐wave sections into a transmission line always increases the total dispersion. On the other hand, w…
Multivalency in Supramolecular Chemistry and Nanofabrication
Abstract For Abstract see ChemInform Abstract in Full Text.
Macroscopic energy transport in ZnO monitored by spatiotemporally resolved luminescence
We report on an experimental study of macroscopic energy transfer in ZnO bulk crystals. We observe the ultraviolet photoluminescence (PL) emission from the near band edge (3.4eV at room temperature), a green emission band from a deep center transition, and an orange emission band. Unusually, the orange PL is not only…
New Borate Precursors for Boron Nitride Powder Synthesis
The thermal decomposition of guanidinium tetraborate, pentaborate, and nonaborate has been characterized under nitrogen and ammonia atmospheres, and conditions have been defined for bulk powder and aqueous aerosol transformations of these precursors to boron nitride (BN). The bulk pyrolyses under ammonia (600−1400 °C)…
Synthesis and Characterization of p-Phenylenediamine Derivatives Bearing an Electron-Acceptor Unit
[reaction: see text] Two series of aniline oligomers bearing fused heterocycles as an electron-acceptor unit were synthesized. They consist of aniline or its derivatives as an electron donor and benzothiadiazole (BT) or quinoxaline (QX) as an electron-acceptor unit. Benzothiadiazoles 1-3 were synthesized by palladium-…
Organic-Functionalized Pure-Silica-Zeolite MFI Low-k Films
For all of the inorganic porous spin-on low- k films being developed today, a post-spin-on hydrophobic treatment is needed to reduce their moisture sensitivity. In the present work, we demonstrate that, for pure-silica-zeolite MFI spin-on low- k films, this extra hydrophobic treatment step can be potentially eliminate…
Controlled growth of Zn-polar ZnO epitaxial film by nitridation of sapphire substrate
Surface nitridation is used to eliminate O-polar inversion domains and control the growth of single-domain Zn-polar ZnO film on sapphire (0001) substrate by rf-plasma-assisted molecular-beam epitaxy. It is found that the nitridation temperature is crucial for achieving quality AlN buffer layers and ZnO films with cati…
Field electron emission from sputter-induced carbon nanofibers grown at room temperature
Graphite, carbon-coated silicon, and carbon-coated nickel surfaces were bombarded with obliquely incident Ar+ ions at room temperature. The sputtered surfaces were covered with conical protrusions, ∼2.5×105mm−2 or higher in numerical density, and partially aligned single carbon nanofibers (CNFs), ∼20nm in diameter and…
Superconductivity in the(Ba1−xSrx)8Si46clathrates(x⩽0.75): Experimental andab initioinvestigation
Si clathrates ${({\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x})}_{8}{\mathrm{Si}}_{46}$ with $x\ensuremath{\leqslant}0.75$ have been successfully synthesized and their superconductivity studied both experimentally and by ab initio calculations. The linear decrease of the cubic lattice parameter with the Sr content…
NO oxidation properties of Pt(111) revealed byab initiokinetic simulations
As a well-known oxidation catalyst, platinum is currently being used to convert NO to $\mathrm{N}{\mathrm{O}}_{2}$ for absorption in so-called $\mathrm{N}{\mathrm{O}}_{x}$ traps under excess oxygen conditions, where direct conversion of NO to nitrogen gas is prohibitive. By performing kinetic Monte Carlo simulations w…
Plane waves with negative phase velocity in isotropic chiral mediums
Abstract The propagation of plane waves in an isotropic chiral medium (ICM) is investigated. Simple conditions are derived—in terms of the constitutive parameters of the ICM—for the phase velocity to be directed opposite to the direction of power flow. It is demonstrated that phase velocity and power flow may be oppos…
Spatially Anisotropic Etching of Graphite by Hyperthermal Atomic Oxygen
The spatially anisotropic kinetics involved in the chemical reaction between highly ordered pyrolytic graphite (HOPG) and a beam containing hyperthermal (approximately 8 km s(-1)) O((3)P) atomic oxygen and molecular oxygen yields unique surface morphologies. Upon exposure at moderate sample temperatures (298-423 K), n…
Shell Distribution on Colloidal CdSe/ZnS Quantum Dots
Scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) was used to determine the chemical distribution of semiconductor shell material around colloidal core-shell CdSe/ZnS quantum dots (QDs). EELS signals from positions around the QD indicate a well-defined shell of ZnS…
Highly rectifying Pr0.7Ca0.3MnO3∕SrTi0.9998Nb0.0002O3 p-n junction
We have fabricated epitaxial Pr0.7Ca0.3MnO3∕SrTi0.9998Nb0.0002O3 (PCMO∕Nb:STO) junctions and characterized the interface electronic properties. The PCMO∕Nb:STO junctions show highly rectifying current density–voltage (J–V) characteristics without an apparent breakdown in the reverse bias up to 100V at room temperature…
M[TCNQ]y-Based Magnets (M = Mn, Fe, Co, Ni; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane)
A family of molecule-based magnets of general formula M[TCNQ] y (M = Mn, Fe, Co, Ni; TCNQ = 7,7,8,8-tetracyano- p -quinodimethane) has been synthesized and characterized. The materials have been synthesized from both M a (CO) b and [M(NCMe) 6 ][SbF 6 ] 2 starting materials, complementing previous studies utilizing [M(…
Macromolecular crystallization in microgravity
Density difference fluid flows and sedimentation of growing crystals are greatly reduced when crystallization takes place in a reduced gravity environment. In the case of macromolecular crystallography a crystal of a biological macromolecule is used for diffraction experiments (x-ray or neutron) so as to determine the…
Defect and Dopant Properties of the SrCeO3-Based Proton Conductor
Atomic-scale studies using advanced simulation techniques have investigated the energetics of defects, oxygen migration, and dopant incorporation in the proton-conducting SrCeO 3 system. The interatomic potential model first reproduces the observed distorted perovskite structure of SrCeO 3 . Substitution with trivalen…
Design and Synthesis of Fluorescence “Turn-on” Chemosensors Based on Photoinduced Electron Transfer in Conjugated Polymers
A new approach to fluorescence “turn-on” chemosensors based on a photoinduced electron transfer (PET) strategy involving conjugated polymers has been developed. Two new conjugated polymers dea-PPETE and tmeda-PPETE were synthesized and characterized. These two polymers use diethylamino and N, N, N ‘-trimethylethylened…