Mobile Rayleigh Doppler wind lidar based on double-edge technique

<正>We describe a mobile molecular Doppler wind lidar(DWL) based on double-edge technique for wind measurement of altitudes ranging from 10 to 40 km.A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45-cm-aperture telescope and a matching azimuth-over-elevation scanner that provides full hemispherical pointing.To guarantee wind accuracy,a single servo loop is used to monitor the outgoing laser frequency to remove inaccuracies due to the frequency drift of the laser or the etalon.The standard deviation of the outgoing laser frequency drift is 6.18 MHz and the corresponding velocity error is 1.11 m/s.The wind profiles measured by the DWL are in good agreement with the results of the wind profile radar(WPR).Evaluation is achieved by comparing at altitudes from 2 to 8 km.The relative error of horizontal wind speed is from 0.8 to 1.8 m/s in the compared ranges.The wind accuracy is less than 6 m/s at 40 km and 3 m/s at 10 km.     

Preparation and characterization of the antibacterial Cu nanoparticle formed on the surface of SiO2 nanoparticles

Cu deposition on the surface of spherical SiO2 nanoparticles was studied to achieve the hybrid structure of Cu-SiO2 nanocomposite. SiO2 nanoparticles served as seeds for continuous Cu metal deposition. The chemical structure and morphology were studied with X-ray photoelectron spectroscopy (XPS), scanning electron microscope energy dispersive X-ray (SEM-EDX), and a transmission electron microscope (TEM). The antibacterial properties of the Cu-SiO2 nanocomposite were examined with disk diffusion assays. The homogeneously formed Cu nanoparticles on the surface of SiO2 nanoparticles without aggregation of Cu nanoparticles showed excellent antibacterial ability.     

Use of cyclopropanols as conformational constraints in RCM

[reaction: see text] Sequential application of the Kulinkovich cyclopropanation of carboxylic esters and RCM of the resulting cis-dialkenyl-tethered cyclopropanols provides an expedient route to functionalized medium-sized carbocycles. Subsequent elaboration of the cyclopropanol functionality, such as one-carbon ring expansion, to afford synthetically useful alpha,beta-enones is also worth noting.     

On generalized shock models for deteriorating systems

Standard assumptions in shock models are that failures of items are related either to the cumulative effect of shocks (cumulative models) or that they are caused by shocks that exceed a certain critical level (extreme shocks models). In this paper, we present useful generalizations of this setting to the case when an item is deteriorating itself, for example, when the boundary for the fatal shock magnitude is decreasing with time. Three stochastic failure models describing different impacts of shocks on items are considered. The cumulative effect of shocks is modeled in a way similar to the proportional hazards model. Explicit formulas for the corresponding survival functions are derived and several simple examples are considered. Copyright © 2012 John Wiley & Sons, Ltd.     

Collinear broadband optical parametric generation in periodically poled lithium niobate crystals by group velocity matching

Collinear broadband optical parametric generation (OPG) using periodically poled lithium niobate (PPLN) crystals were designed and experimentally demonstrated with the quasi-phase matching (QPM) periods of 21.5, 24.0, and 27.0 μm. The broad gain bandwidth was accomplished by choosing a specific set of the period and the pump wavelength that allows the group velocities of the signal and the idler to match close to the degeneracy point. OPG gain bandwidth and also the spectral region could be controlled by proper design of QPM period and pump wavelength. The total OPG gain bandwidth of 600, 900, and 1200 nm was observed for the PPLN devices with QPM periods of 21.5, 24.0, and 27.0 μm, respectively. We have also observed multiple color visible generation whenever the OPG spectrum was significantly broad. From the visible peaks of the three PPLN samples, it is found that broad gain bandwidth is crucial in the temperature-insensitive collinear simultaneous RGB generation from a single crystal.     

Microporous Hypercross-linked Conjugated Quinonoid Chromophores of Anthracene: Novel Polymers for CO2 Adsorption

Microporous hypercross-linked conjugated quinonoid chromophores represent a novel class of amorphous polymers, synthesized by the reaction of anthracene with dimethoxy methane in the presence of FeCl3 catalyst. Their N2 adsorption isotherms confirm their microporous nature. Diffuse reflectance UV-Visible(DRS UV-Vis) spectroscopy confirms their matrix built with the conjugated quinonoids by their broad light absorption characteristics extending from 1000 nm to 200 nm with the absorbance maximum close to 400 nm. The catalyst cross-linked anthracene with ―CH2― bridges and subsequently dehydrogenating them to form quinonoids. Their Fourier transform infrared(FTIR) spectra showed their characteristic quinonoid vibrations between 1600 and 1700 cm-1. The synthesis of polymers was carried out at 30, 40, 50, 60, 70 and 80 ℃, but the quinonoid content of the polymer obtained at 80 ℃ was higher than that of the others. Their scanning electron microscopy(SEM) images showed microspheres of 1 to 5 μm size built with tiny particles. Their surfaces were not smooth. The polymer synthesized at 80 ℃ showed 5.1 wt% CO2 sorption at 25 ℃ and 0.1 MPa, but when it was recross-linked, the CO2 sorption increased to 8 wt%. Hence, hypercross-linked conjugated quinonoid chromophores of anthracene are good for sorption of CO2.