A simple, rapid, and efficient oxidation of oximes to ketones and aldehydes with manganese dioxide catalyzed by kieselguhr under solvent-free conditions

A simple, rapid, and efficient oxidation of oximes to the corresponding ketones and aldehydes with manganese dioxide catalyzed by kieselguhr under solvent-free conditions at room temperature in the yields between 82 and 98 is described. It seems that kieselguhr in the present procedure can highly expedite the reaction rate. By comparing to other methods described previously, the main advantages of this oxidation are that the oxidations are more efficient, the reaction conditions are milder, the reaction times are shorter, and the work-up is easier. Furthermore, the amount of manganese dioxide used in this oxidation is largely decreased.     

Study on an optical system with coherent laser array source and phase optimization in turbulent atmosphere

Model of an optical system with coherent laser array source and the piston phase optimized by the stochastic parallel gradient descent algorithm is established. With this model, theory of beam propagation through the optical system in turbulent atmosphere is analyzed, and the analytical formulas of the beam average intensity along the propagation path are derived. Strehl ratio of the received beam induced by intensity disorderly distribution and power efficiency of the received beam are introduced to evaluate performance of the optical system. Under the H-V 5/7 atmospheric turbulent model, performance of an optical system with determinate parameters was calculated, and the influences of the propagation distance and the laser wavelength were numerically analyzed, respectively.     

Study on alpha cup technique for monitoring of soil radon levels

Determination of radon concentrations in soil usually requires the accumulation of many measurements over a large area. In this study, an alpha cup technique that provides a cumulative result for adsorption of radon progeny over time was investigated. In addition, the performance of measurements were evaluated. To avoid the impacts of temperature and humidity, a new arithmetic correction was explored. Finally, we also investigated the effect of burial time of the alpha cup on soil radon measurements. Experiments showed that the alpha cup technique can satisfy the demands of soil radon measurements in efficiency, accuracy, reliability, and stability.     

An intrinsic fiber ring laser based sensor with saturable absorber

A novel configuration of fiber ring laser acoustic sensor, which adopts single-mode fiber as sensing element, is proposed and demonstrated. Linewidth less than 1 kHz is achieved by introducing a segment of erbium-doped fiber in the reflecting arm as saturable absorber. A polarization independent unbalanced Michelson interrogation interferometer and phase generated carrier demodulation technique are adopted to recover signal. Experiments demonstrate that the phase sensitivity is 0.018 rad/nm in good linearity and equivalent minimum detect able length change reaches 19.1 pm.     

Cerium (IV) ammonium nitrate (CAN)-mediated regioselective synthesis and anticancer activity of 6-substituted 5,8-dimethoxy-1,4-naphthoquinone

6-Substituted 5,8-O-dimethyl-1,4-naphthoquinones (6-DMNQ), the promising anticancer scaffolds, were selectively generated by oxidative demethylation of 2-substituted 1,4,5,8-tetramethoxynaphthalenes with CAN in EtOAc/H₂O in comparatively high yields. An interesting finding was that apart from the reported electron-withdrawing effects of substituents on position 2 of naphthalene ring, regioselective synthesis of 6-DMNQ was largely dependent on the steric effects in CAN-mediated oxidation. The selective cytotoxicities of 6-DMNQ from the in vitro cell-based assays were exhibited between the cancer cells and normal cells. Moreover, most of sulfur-containing 6-DMNQ derivatives displayed better anticancer activities than the corresponding oxygen-containing ones, which could provide an available strategy for the design of 6-DMNQ derivatives as potential anticancer agents.     

Analysis and synchronization for a new fractional-order chaotic system with absolute value term

A new fractional-order chaotic system with absolute value term is introduced. Some dynamical behaviors are investigated and analyzed. Furthermore, synchronization of this system is achieved by utilizing the drive-response method and the feedback method. The suitable parameters for achieving synchronization are studied. Both the theoretical analysis and numerical simulations show the effectiveness of the two methods.     

Real-time extended-field-of-view ultrasound based on a standard PC

Extended field-of-view (EFOV) can acquire a full field of vision, which can help doctors to make more objective and accurate diagnosis. Current EFOV techniques suffer from the low computation speed due to the large amount of ultrasound data to be processed. This paper describes an efficient technique to register 2D multiframe ultrasound images and produce EFOV images with significantly reduced computation time based on a standard PC. For registration of any two adjacent images, we propose to select less image blocks which are regarded as the most valid blocks based on the importance of image content. In registration of a sequence of images, with an assumption that the moving direction and speed of the probe are nearly identical during the data collection, we estimate the moving speed of the probe at the beginning of data collection and ignore redundant image data by processing a smaller number of frames according to a frame interval. The experimental results show that the computation speed of our method is increased by 7–80 times in comparison with two traditional methods, and can accurately produce EFOV images in real-time.     

A new near-infrared fluorescent chemodosimeter for discrimination of sulfide from disulfide

Research on Chemical Intermediates - A new near-infrared fluorescent “turn-on” chemodosimeter (probe 1) based on dicyanomethylene-4H-chromene fluorophore for sulfide was developed....     

Synthesis and proton conductivity of sulfonated,multi‐phenylated poly(arylene ether)s

A series of sterically‐encumbered, sulfonated, poly(arylene ether) copolymers were synthesized and their proton conductivity examined. The series was prepared by copolymerizing a novel monomer, 2″,3″,5″,6″‐tetraphenyl‐[1,1′:4',1″:4″,1″':4″',1″″‐quinquephenyl]‐4,4″″‐diol, with 4,4'‐difluorobenzophenone and bisphenol A. Subsequent sulfonation and solution casting provided membranes possessing ion exchange capacities of 1.9 to 2.7 mmol/g and excellent mechanical properties (Young's modulus, 0.2–1.2 GPa; tensile strength, 35–70 MPa; elongation at break, 62–231%). Water uptake ranged from 34 to 98 wt% at 80 °C/100% RH. Proton conductivities ranged between 0.24 to 16 mS/cm at 80 °C/60% RH, and 3 to 167 mS/cm at 80 °C/95% RH. TEM analysis of the polymers, in the dehydrated state, revealed isolated spherical aggregates of ions, which presumably coalesce when hydrated to provide highly conductive pathways. The strategy of using highly‐encumbered polymer frameworks for the design of mechanically‐robust and dimensionally‐stable proton conducting membranes is demonstrated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2579‐2587