中子活化分析中煤样厚度及探测器位置的选择

利用MCNP5程序包模拟14MeV脉冲中子照射一定厚度煤样,并通过时间控制获得非弹γ能谱和俘获γ能谱,再利用计数率的高低确定γ能谱的获取位置.结果表明:当煤样厚度为20cm时,非弹γ能谱的计数率达到饱和;当煤样厚度为35cm时,俘获γ能谱的计数率达到饱和.     

Highly efficient regioselective ring openings of N-tosylaziridines to haloamines using ferric(Ⅲ) halides

FeX3（X = Cl, Br） were found to be very effective reagents and powerful catalysts for regioselective ring openings of a variety of N-tosylaziridines with them to afford the corresponding b-haloamines in good to excellent yields with high regioselectivity under mild conditions. At the same time, 13 new compounds were obtained firstly. Moreover, the b-bromoamine prepared could be transferred into b-nitroamine with NaNO2 in moderate yield.     

Microwave‐assisted extraction in combination with HPLC‐UV for quantitative analysis of six bioactive oxoisoaporphine alkaloids in Menispermum dauricum DC

A novel and reliable method based on microwave‐assisted extraction (MAE) followed by HPLC‐UV was developed and validated for the simultaneous quantification of six pharmacologically important oxoisoaporphine alkaloids in the total plants of Menispermum dauricum DC. The optimal MAE extraction condition was performed at 60°C for 11 min with ethanol–water (70:30, v/v) as the extracting solvent, and the solvent to solid ratio was 20:1. Chromatographic separation was achieved on a reversed‐phase YMC C₁₈ column (250 × 4.6 mm, i.d., 5 µm) with a gradient mobile phase consisting of A (1% aqueous formic acid) and B (acetonitrile containing 1% formic acid) at a flow rate of 1.5 mL/min. The detection wavelength was set at 422 nm. Excellent linearity over the investigated concentration ranges was observed with values of r >0.999 for all analytes. The method developed was validated with acceptable sensitivity, intra‐ and inter‐day precision and extraction recoveries. It was successfully applied to the determination of six alkaloids in Menispermum dauricum DC from different sources and different parts of Menispermum dauricum DC. The results obtained indicated that the method is suitable for the quality control of Menispermum dauricum DC. Copyright © 2015 John Wiley & Sons, Ltd.     

Review on ionization and quenching mechanisms of Trichel pulse

Trichel pulse is a kind of pulsed mode in negative DC corona discharge, which has attracted significant attention because of its considerable applications in industry. Over eighty years, plenty of effort including simulations and experiments has been spent to reveal the ionization and quenching mechanisms of Trichel pulse. By revisiting and summarizing the basic characteristics and well-accepted ionization and quenching mechanisms, this review provides a basic understanding and the current status of Trichel pulse.     

Designing nickel phthalocyanine periphery by alkyl chain via [1,3,4]-oxadiazole

Nickel phthalocyanine (NiPc, 1) periphery has been decorated by alkyl chains of varying chain length via [1,3,4]-oxadiazole moiety (NiPcs 3a–3f). All the newly synthesized compounds NiPcs 3a–3d have been completely characterized by elemental analysis, FT-IR, solid-state UV-Vis, and solid-state ¹³C NMR spectroscopy, in addition to X-ray diffraction, scanning electron microscopy, and thermal analysis. The effect of chain length in the NiPc periphery on electronic absorption and DC electrical conductivity has been investigated.     

Synthesis,characterization, corrosion inhibition of mild steel in HCl (0.5 N) solution and solid‐state electrical conductivity of new Co(II), Ni(II), Cu(II) and Zn(II) complexes

This work consists of a study of the corrosion‐inhibiting and semiconducting properties of new binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with a Schiff base, H₂L, obtained from the 2:1 M condensation of salicylaldehyde and o‐dianisidine, respectively. Elemental, spectral and thermal analyses were used to characterize these complexes. The magnetic susceptibilities of these complexes were also determined. Weight loss, potentiodynamic polarization and scanning optical microscopy were the techniques used to investigate the efficiency of these new compounds as corrosion inhibitors. The antibacterial activity of the compounds was measured against sulfate‐reducing bacteria. It was found that inhibition occurs via the chemisorption of metal complexes on the steel surface. This absorption obeys the Langmuir adsorption isotherm model.     

Benthic foraminiferal δ~(13)C minimum events in the southeastern Okhotsk Sea over the last 180 ka

A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.     

The effects of the non-breaking surface wave-induced vertical mixing on the forecast of tropical cyclone tracks

The Weather Research and Forecasting model(WRF)is configured for the region of(15°–41°N,105°–135°E),which covers the same area with the MASNUM(Key Lab.Marine ScienceNumerical Modeling,State Oceanic Administration)wave-tide-circulation coupled operational forecast system.Three numerical experiments are implemented to investigate the effects of the real-time forecasted sea surface temperature(SST)and the nonbreaking wave-induced vertical mixing(Bv)on the track forecast of all 33 tropical cyclones(TC)in the model domain area during 2008 and 2011.The first experiment employs NCEP FNL(NCEP final analysis)SST as WRF’s bottom condition as the Control run,which is also the default setup of WRF.The second and third experiments use real-time forecasted SST from the MASNUM forecast system with and without Bv,respectively.The forecasted track results are compared with Japan Meteorological Agency’s best track data.For 24-h forecast,the averaged TC position error of Experiment with Bv is reduced by 9%compared to the Control experiment,while the forecasted track error of Experiment without Bv is reduced by only2%compared to the Control experiment.For the 48-h forecast,the averaged track errors are reduced by 10%and6%with Bv and without Bv compared to the Control experiment,respectively.These results suggest that the real-time forecasted SST can improve the performance of WRF in forecasting TC track,and the Bv plays an important role in reducing the forecast error of TC track.Comparatively,Bv can improve more on the track of stronger TC.     

DC Electrical Conductivity of the Direct Electrochemically Synthesized Polythiophene Metal Complexes

Electrochemical anodic oxidation of a metal anode in an acetone solution of 2,5-diamino-3,4-dicyanothiophene gave the polythiophene metal complexes of Co, Ni, Cu, Zn, Cd, and Sn. Chemical analyses, as well as FTIR and electronic spectral data, are presented to confirm the formulation of the isolated materials. DC electrical conductivity measurements of the polymer complexes were measured in the range 300–500 K in the annealed and 5% doped forms. The products gave electrical conductivity in the semi-conducting region that increased by heat.