Nitrogen-doped carbon encapsulated in mesoporous TiO_2 nanotubes for fast capacitive sodium storage

Controllable synthesis of insertion-type anode materials with beneficial micro-and nanostructures is a promising approach for the synthesis of sodium-ion storage devices with high-reactivity and excellent electrochemical performance.In this study,we developed a sacrificial-templating route to synthesize TiO₂@N-doped carbon nanotubes(TiO₂@NC-NTs)with excellent electrochemical performance.The asprepared mesoporous TiO₂@NC-NTs with tiny nanocrystals of anatase TiO₂ wrapped in N-doped carbon layers showed a well-defined tube structure with a large specific surface area of 198 m² g^-1 and a large pore size of~5 nm.The TiO₂@NC-NTs delivered high reversible capacities of 158 m A h g^-1 at 2 C(1 C=335 m A g^-1)for 2200 cycles and 146 m A h g^-1 at 5 C for 4000 cycles,as well as an ultrahigh rate capability of up to 40 C with a capacity of 98 m A h g^-1.Even at a high current density of 10 C,a capacity of 138 m A h g^-1 could be delivered over 10,000 cycles.Thus,the synthesis of mesoporous TiO₂@NC-NTs was demonstrated to be an efficient approach for developing electrode materials with high sodium storage and long cycle life.     

Non-fragile robust output feedback control of uncertain active suspension systems with stochastic network-induced delay

Nonlinear Dynamics - The vehicle active suspension has attracted considerable attention owing to its great contributions to the vertical dynamics of vehicle. This paper investigates the non-fragile...     

Synthesis of a diazacrown ether containing polymers and formation of complexes with alkaline earth metals

We report the synthesis of a polymer that contains the diaza‐18‐crown‐6 moiety on the polymer main chain. Metal containing polymers were obtained when the respective barium or strontium complexes were used as monomers. These polymers emitted greenish blue light in solution, and the metal had little influence on absorption and emission energies. In the solid state, the position of the emission peaks was different probably due to a different degree of aggregation.     

Synthesis and liquid crystal properties of bipyridine-containing aromatic polyamides

A series of novel aromatic polyamides containing 2,2′-bipyridine moiety were synthesized by polycondensation of 2,2′-bipyridine-5,5′-dicarboxylic acid ( 2 ) with various aromatic diamines in hexamethylphosphoramide (HMPA) containing lithium chloride. The resulting polyamide solutions in 98% sulfuric acid and in HMPA-LiCl exhibited lyotropic liquid crystal phases. The phase transition behaviors were studied by polarizing microscopy and X-ray diffraction. The polyamides also formed metal complexes with cis-dichlorobis(bipyridine)ruthenium dihydrate [cis-Ru(bpy)₂Cl₂ · 2H₂O] which was supported by changes in electronic spectra.     

Novel results obtained by freezing berry pseudorotation of phosphoranes (10‐P‐5)

By freezing Berry pseudorotation of spirophosphoranes with recourse to the rigidity of the Martin bidentate ligand, we successfully prepared configurationally stable enantiomeric pairs of optically active phosphoranes, and could isolate “anti‐apicophilic” C‐apical O‐equatorial (O‐cis) phosphoranes. The effect of σ*_{P O} orbital of the O‐cis phosphorane was investigated both experimentally and theoretically. O‐cis phosphoranes were revealed to be much more electrophilic at the phosphorus atom than O‐trans isomers by experimental studies. The acidity of the α‐proton of an O‐cis benzylphosphorane was found to be higher than that of the corresponding O‐trans isomer. By the reaction of the α‐carbanion of an O‐cis benzylphosphorane with PhCHO, we succeeded in the first isolation and full structural characterization of a 12‐P‐6 phosphate bearing an oxaphosphetane ring, the intermediate in the Wittig type reaction using a 10‐P‐5 phosphorane. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:390–396, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10072