Synthesis and fungicidal activity of novel 2,3-disubstituted-1,3-benzoxazines

A series of new 2,3-disubstituted-3,4-dihydro-2H-1,3-benzoxazines were prepared in moderate to excellent yields by aza-acetalizations of aromatic aldehydes with 2-(N-substituted aminomethyl)phenols in the presence of TMSCl. Their structures were confirmed by IR, 1H-NMR, 13C-NMR, MS and elemental analysis. The fungicidal activities of the target compounds were preliminarily evaluated, and some compounds exhibited good activity against Rhizoctonia solani.     

A REDUCED FE FORMULATION BASED ON POD METHOD FOR HYPERBOLIC EQUATIONS

A proper orthogonal decomposition(POD) method was successfully used in the reduced-order modeling of complex systems.In this paper,we extend the applications of POD method,namely,apply POD method to a classical finite element(FE) formulation for second-order hyperbolic equations with real practical applied background,establish a reduced FE formulation with lower dimensions and high enough accuracy,and provide the error estimates between the reduced FE solutions and the classical FE solutions and the implementation of algorithm for solving reduced FE formulation so as to provide scientific theoretic basis for service applications.Some numerical examples illustrate the fact that the results of numerical computation are consistent with theoretical conclusions.Moreover,it is shown that the reduced FE formulation based on POD method is feasible and efficient for solving FE formulation for second-order hyperbolic equations.     

Periodic and subharmonic solutions for a class of non-autonomous Hamiltonian systems

Some existence theorems are obtained for periodic and subharmonic solutions of a class of non-autonomous Hamiltonian systems. Our technical approach is based on a version of the Local Linking Theorem, and the Generalized Mountain Pass Theorem.     

1.55-μm coherent lidar based on SPA sinusoidal frequency demodulation techniques

A 1.55-μm all-solid frequency-modulated continuous-wave (FMCW) coherent lidar based on the sinusoidal frequency demodulation technique for range and velocity measurement is presented. Both the nonlinearity of linear modulation waveform and the difficulty in measuring the frequency of sinusoidal modulation sys- tem are circumvented by utilizing segmental-processing-average (SPA) techniques. The results demonstrate that the resolutions of range and velocity measurement are better than 2 mm and 0.1 mm/s, respectively. The system has numerous practical and potential applications in space missions.     

A note on lower bound of centered L2-discrepancy on combined designs

This note provides a theoretical justification of optimal foldover plans in terms of uniformity. A new lower bound of the centered L ₂-discrepancy values of combined designs is obtained, which can be used as a benchmark for searching optimal foldover plans. Our numerical results show that this lower bound is sharper than existing results when more factors reverse the signs in the initial design.     

Aggregation of quaternary ammonium gemini surfactants C12-s-C12.2Br in n-heptane/n-hexanol solution: effect of the spacer chains on the critical reverse micelle concentrations

The critical reverse micelle concentrations of C(12)-s-C(12).2Br (s=2,3,4,5,6,8,12) in n-heptane/n-hexanol solutions, cmc(I)s, have been determined by absorption spectrum method using iodine as probe. The values of cmc(I)s are smaller than those of the critical micelle concentrations (cmc(aq)s) in aqueous solution and reach a maximum at s=4, which is similar to the variation of cmc(aq) with s. The variation of cmc(I) with s is attributed to the alteration in the spacer chain conformation, i.e. when the spacer is short enough, it may adopt stretch configuration and when the spacer is long, it tends to bend towards the continuous oil phase to achieve a more densely packing of the quaternary ammonium heads on the surface of the core.     

A blow-up criterion for compressible viscous heat-conductive flows

We study an initial boundary value problem for the three-dimensional Navier–Stokes equations of viscous heat-conductive fluids in a bounded smooth domain. We establish a blow-up criterion for the local strong solutions in terms of the temperature and the gradient of velocity only, similar to the Beale–Kato–Majda criterion for ideal incompressible flows.     

Ionic liquid buffers: a new class of chemicals with potential for controlling pH in non-aqueous media

Ionic liquids with buffering characteristics, synthesized by the reaction of [RMIM]OH base moieties with phthalic and tartaric acid, respectively, are potential reagents for controlling pH in non-aqueous media; remarkable [Base]/[Acid] molar ratio dependence of the catalytic activities has been observed in the hydrogenation of olefins with [RuCl2(PPh3)3] complex in DMF and [BMIM][BF4].     

A sugar-quinoline fluorescent chemosensor for selective detection of Hg2+ ion in natural water

A selective and sensitive fluorescent sensor for detection of Hg2+ in natural water was achieved by incorporating the well-known fluorophore quinoline group and a water-soluble D-glucosamine group within one molecule.