Quality Analysis of Five Edible Wild Vegetables in Chongqing

[Objectives]This study was conducted to analyze the quality of several kinds of wild vegetables in Yongchuan District,Chongqing City.[Methods]Five common edible wild herbs,Plantago asiatica,Taraxacum mongolicum,Pteridium aquilinum(L.)Kuhn var.latiusculum(Desv.)Underw.ex Heller,Brasenia schreberi and Houttuynia cordata in Yongchuan District,Chongqing,were tested for nitrate,amino acid,reducing sugar,and vitamin C contents.[Results]The vitamin C content was the highest in B.schreberi,reaching 1056 mg/kg,and the lowest in P.aquilinum var.latiusculum,at only 61 mg/kg.T.mongolicum had the highest reducing sugar(E value)and amino acid contents,at 1.01 and 24.3 mg/kg,respectively,and the values were the lowest in P.asiatica,at 0.15 and 9.1 mg/kg,respectively;and the nitrate contents ranked as H.cordata(2529 mg/kg)﹥B.schreberi(2188 mg/kg)﹥P.aquilinum var.latiusculum(1900 mg/kg)﹥P.asiatica(1097 mg/kg)﹥T.mongolicum(1079 mg/kg),which were at the level of medium to high pollution,but within the scope of the national acceptable daily intake(ADI).The nutritional value of wild vegetables is higher than that of vegetables grown in the field,but some wild vegetables are also toxic,which will have adverse effects on human health.[Conclusions]People need to develop and utilize wild vegetable resources scientifically and rationally according to their own needs.

Construction Path of Farmer Education and Training System in the Context of Rural Revitalization

It is very important to establish a farmer education and training system for the revitalization of rural talents.This paper analyzed the necessity and new requirements for the construction of a farmer education and training system in the new era.It pointed out the specific path for construction of farmer education and training system from accurately grasping the development direction of farmer education and training,accelerating the construction of a new pattern of farmer education and training,comprehensively promoting the high-quality development of farmer education and training,and actively creating a good atmosphere for farmer education and training,so as to promote the revitalization of rural talents.

Molecular modeling of epsilon RNA from hepatitis B virus

An initial model of the HBV epsilon RNA was built by the Biopolymer module of Insight II. While its three-dimensional structure was obtained through structure optimization based on molecular dynamics simulation, the two active sites were found. A comparison with the experimental result indicated that the active sites may be the binding sites of the epsilon RNA in the RT-epsilon interaction. The result will be helpful to further discussion about the mechanism of RT-epsilon interaction and the study of HBV genome replication.

Pollutant concentrations and pollution loads in stormwater runoff from different land uses in Chongqing

To investigate the distribution of pollutant concentrations and pollution loads in stormwater runoff in Chongqing,six typical land use types were selected and studied from August 2009 to September 2011.Statistical analysis on the distribution of pollutant concentrations in all water samples shows that pollutant concentrations fluctuate greatly in rainfall-runoff,and the concentrations of the same pollutant also vary greatly in different rainfall events.In addition,it indicates that the event mean concentrations （EMCs） of total suspended solids （TSS） and chemical oxygen demand （COD） from urban traffic roads （UTR） are significantly higher than those from residential roads （RR）,commercial areas （CA）,concrete roofs （CR）,tile roofs （TRoof）,and campus catchment areas （CCA）;and the EMCs of total phosphorus （TP） and NH3-N from UTR and CA are 2.35-5 and 3 times of the class-III standard values specified in the Environmental Quality Standards for Surface Water （GB 3838-2002）.The EMCs of Fe,Pb and Cd are also much higher than the class-III standard values.The analysis of pollution load producing coefficients （PLPC） reveals that the main pollution source of TSS,COD and TP is UTR.The analysis of correlations between rainfall factors and EMCs/PLPC indicates that rainfall duration is correlated with EMCs/PLPC of TSS for TRoof and TP for UTR,while rainfall intensity is correlated with EMCs/PLPC of TP for both CR and CCA.The results of this study provide a reference for better management of non-point source pollution in urban regions.

Preparation and upconversion luminescence of monodisperse Gd_2O_3:Ho^(3+),Yb^(3+)nanocrystals

Gd2O3：Ho^3＋,Yb^3＋ nanocrystals were synthesized via solvothermal method. X-ray diffraction （XRD）, transmission electron microscopy （TEM）, absorption and upconversion spectra were employed to characterize the synthesized nanocrystals. The results of XRD and TEM showed that obtained Gd2O3：Ho^3＋,Yb^3＋ nanocrystals were cubic in crystal structure and uniform spherical in morphology. The average crystallite size was calculated to be 7.5 nm. Green and red up-conversion emissions corresponding to （^5F4, ^5S2）→^5I8 and ^5F5→^5I8 transition were observed upon 980 nm excitation at room temperature. The results indicated that both green and red luminescence were based on the two-photon processes. Laser power and doping concentration dependence of the up- converted emissions were studied to understand the upconversion mechanisms. Excited state absorption and energy-transfer processes were discussed as the possible mechanisms for the visible emissions.

Effect of doping Gd^(3+) on crystal structure and luminescent properties of Sr_2SiO_4:Eu^(2+) phosphor

Sr1.995-1.5xGdxSiO4：0.005Eu^2＋ phosphor series with x=0-0.08 mol for near-ultraviolet white light-emitting diodes （NUV w-LEDs） were synthesized via solid-state reaction method. XRD profile pattern and refinement results demonstrated that doping Gd^3＋ ions resulted in the phase transformation （β-Sr2SiO4→α＇-Sr2SiO4）. The photoluminescenee spectrum of the sample with x=0 tool displayed two emission peaks centered at 470 and 525 nm. The two-peak spectra became one-peak spectra with the Gd^3＋ concentration increasing. Actually, the fitting results demonstrated that the one-peak spectra were still composed of two single emission spectra. The photoluminescence intensity was improved and the CIE chromaticity coordinates were adjusted via doping Gd^3＋.

Variation of mechanical properties and microstructure of hot-rolled AA2099 Al-Li alloy induced by the precipitation during preheating process

Preheating is the first step for thermal-mechanical processing of the materials. Several preheating schedules were designed based on industrial manufacturing to explore their effect on the microstructure and mechanical properties of AA2099 Al-Li alloy during the following hot rolling. The results show that the mechanical properties of as-rolled sheets are quite sensitive to preheating. Various types of secondary phases, including δ', T1 and T2 phases, were precipitated during the heating process. The difference among precipitates is the main reason to induce the variation of mechanical properties for as-rolled sheets. A rapid heating rate gave rise to the precipitation of δ' phase, which largely promoted yield stress and ultimate tensile strength in as-rolled sheets. T1 phase was more favorable in the preheating with a holding period at 150–250 °C, which caused a moderated strain hardening behavior. Precipitates formed during preheating induced different slip behaviors in the following deformation. The coexistence of T1 and δ' phase could restrict planar slip, which inhibited the formation of the shear band. The difference in the activity of non-octahedral slips and planar slips determined the strain hardening effect, which should be the reason for the variation of mechanical properties of as-rolled sheets.

A practical synthesis of bis(indolyl)methanes catalyzed by BF_3·Et_2O

Practical BF3.Et20 catalyzed reactions between indoles and a series of carbonyl compounds at room temperature are described, which afford bis（indolyl）methanes with isolated yields up to 96%,

Spectroscopic properties of Gd_2O_3:Dy^(3+)nanocrystals

Gd203：Dy3＋ nanocrystals were synthesized via solvothermal method followed by a subsequent calcination. The samples were characterized by X-ray diffraction （XRD）, transmission electron microsopy （TEM）, Electronic dispersive X-ray spectroscopy （EDX）, photoluminescence （PL） spectrum and decay curves. The effect of the annealing temperature on the crystallinity and particle size was studied; heat treatment improved the crystallinity of as-prepared nanocrystals as well as increased their particle size. The nanocryatals presented monodispersed spherical shape under TEM. Photoluminescence spectra showed that nanocrystal exhibited strong yellow emission corresponding to 4F9/2----6HI3/2 transition （573 nm） of Dy3＋ under UV light excitation, which broadened with the particle size decreased without structure changed. The theoretical mechanism of luminescence was explored and surface effect was thought to be the main reason.

Thermal degradation of BaAl_2Si_2O_8:Eu^(2+) phosphor excited by near ultraviolet light

Eu2+ doped BaAl2Si2O8 phosphor was synthesized by one-step calcination of precursors that were prepared by chemical co-precipitation.The thermal degradation properties of BaAl2Si2O8:Eu2+ were investigated by photoluminescence,lifetime and chromaticity coordinate measurements.BaAl2Si2O8:Eu2+ is efficiently excited by incident light of 250-400 nm,which matches the emission of near ultraviolet LED chips well.BaAl2Si2O8:Eu2+ exhibits broad blue emission at 470 nm because of the 4f65d1-4f7(8S7/2) transition of Eu2+ ions,and the emission band shows an unusual blue shift with bandwidth broadening and emission intensity decreasing as the annealing temperature is increased.The luminescence decay and CIE chromaticity coordinates of BaAl2Si2O8:Eu2+ were determined to investigate its application in white LEDs.

Near infrared molybdenum oxide quantum dots with high photoluminescence and photothermal performance

The synthesized near infrared molybdenum oxide quantum dots perform excellent red fluorescence imaging performance and photothermal performance,which have 600,650 and 700 nm three unique peaks excited at 540 nm,with a high quantum yield around 20%.Meanwhile,with 808 nm NIR laser excitation,10 mg/mL modified Molybdenum oxide quantum dots can increase temperature up to 72.2℃within 150 s and 77.7℃within 270 s,respectively.

p-Nitrophenyl Picolinate Cleavage by Unsymmetrical Bis-Schiff Base Manganese（Ⅲ） and Cobalt（Ⅱ） Complexes with Aza-Crown Ether or Morpholino Pendants

The unsymmetrical bis-Schiff base manganese（III） and cobalt（II） complexes with either benzo-10-aza-crown ether pendants （MnL1Cl, MnLZCl） or morpholino pendant （MnL3Cl, CoL3） have been employed as models for hy- drolase by studying the kinetics of their hydrolysis reactions with p-nitrophenyl picolinate （PNPP）. A kinetic model of PNPP cleavage catalyzed by these complexes is proposed. The effects of complex structures and reaction temperature on the rate of PNPP hydrolysis have been examined. All four complexes exhibit high catalytic activity and the rate increases with pH under 25℃. The complexes of ligands containing a crown ether group exhibit higher catalytic activities than the non-crown analogues. The catalytic activity of the complexes follows the order Mn（III） 〉 Co（II） under the same ligands.

An automatic isotropic/anisotropic hybrid grid generation technique for viscous flow simulations based on an artificial neural network

Based on the author’s previous research, a novel hybrid grid generation technique is developed by introducing an Artificial Neural Network(ANN) approach for realistic viscous flow simulations. An initial hybrid grid over a typical geometry with anisotropic quadrilaterals in the boundary layer and isotropic triangles in the off-body region is generated by the classical mesh generation method to train two ANNs on how to predict the advancing direction of the new point and to control the grid size. After inputting the initial discretized fronts, the ANN-based Advancing Layer Method(ALM) is adopted to generate the anisotropic quadrilaterals in boundary layers. When the high aspect ratio of the anisotropic grid reaches a specified value, the ANN-based Advancing Front Method(AFM) is adopted to generate isotropic triangles in the off-body computational domain.The initial isotropic triangles are smoothed to further improve the grid quality. Three typical cases are tested and compared with experimental data to validate the effectiveness of grids generated by the ANN-based hybrid grid generation method. The experimental results show that the two ANNs can predict the advancing direction and the grid size very well, and improve the adaptability of the isotropic/anisotropic hybrid grid generation for viscous flow simulations.