SO_2和NO_2在γ-Al_2O_3(110)表面吸附的第一性原理计算

采用基于平面波基组的Vienna Ab-initio Simulations Package (VASP)程序研究了SO_2和NO_2在γ-Al_2O_3(110)表面和羟基化γ-Al_2O_3(110)表面的吸附,获得了SO_2和NO_2吸附的不同构型和结构参数.对吸附能,电荷转移,差分电荷密度和投影态密度等进行分析和讨论.对比发现,在γ-Al_2O_3(110)表面SO_2的吸附能力强于NO_2.SO_2或NO_2在非羟基化γ-Al_2O_3(110)表面吸附时O原子的2p轨道和Al原子的3s3p轨道作用形成O-Al键,且SO_2吸附时键结强度高于NO_2.NO_2吸附时费米能级以下有部分反键态,削弱了与γ-Al_2O_3(110)表面相互作用.在羟基化γ-Al_2O_3(110)表面SO_2或NO_2的吸附能力会低于非羟基化表面,但是SO_2的吸附能力依旧强于NO_2.计算结果说明SO_2与γ-Al_2O_3(110)表面的相互作用强于NO_2.以上研究,将有助于理解SO_2和NO_2在γ-Al_2O_3的反应性,为进一步研究它们的非均相转化和在灰霾形成中的促进作用奠定基础.     

(1,2-(1H-1,2,4-三唑))乙烷的一维双链Cu(Ⅱ)配合物合成与表征(英文)

利用高度柔性的双三唑配体(1,2-(1H-1,2,4-三唑))乙烷(L)和铜盐反应合成了1个新的具有一维双链结构的铜(Ⅱ)配合物{[Cu(cis-L)2Br]Br.2H2O}n(1)。单晶结构表明:配合物1的晶体属于三斜晶系,P1空间群。在配合物1中双三唑配体采用反式构型,桥联相邻的中心铜离子形成一维双链结构,晶格中游离的Br原子同配位水分子形成了四元环状的Br…O超分子环。测定了配合物1在2～300 K的变温磁化率,结果表明相邻铜离子间存在弱的反铁磁相互作用。     

磷酸超声提取大气颗粒物中砷的多种形态

以H<,3>PO<,4> 为提取剂,利用高效液相色谱与氢化物发生原子荧光光谱联用(HPLC-HG-AFS)实现了大气颗粒物中砷形态的温和提取测定,并通过标准样品的形态加标实验确定了最佳提取方法.在优化的色谱及光谱条件下,As(Ⅲ),As(Ⅴ),MMA(甲基胂酸)和DMA(二甲基胂酸)均可达基线分离,其方法检出限分别为1...     

胶质液态泡沫的萃取性能

制备了包含萃取剂的胶质液态泡沫（ＣＬＡ）,测定了包含Ｎ１９２３或ＴＢＰ的ＣＬＡ萃取醋酸的性能,以及包含Ｐ５０７的ＣＬＡ萃取稀土离子时稀土在ＣＬＡ水质滑腻壳层中的渗透系数．结果表明将萃取剂包含于ＣＬＡ中,对其粒径、粘度及稳定性等不产生明显影响,但对萃取分配及传质十分有利．     

Interaction of intense laser pulses with hydrogen atomic clusters

The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.     

加速溶剂萃取-硅胶萃取净化-气相色谱/质谱法检测地表水中有机氯农药和多氯联苯

建立了加速溶剂萃取-硅胶固相萃取净化-气相色谱/质谱同时检测地表水中15种有机氯农药(OCPs)和82种多氯联苯(PCBs)的方法.对影响OCPs和PCBs回收率的主要因素进行优化,得出最优的萃取条件:3次静态萃取循环,100℃的萃取温度,丙酮/正己烷(1∶1,V/V)为萃取液,静态萃取10 min.在最优条件下,15种OCPs和82种PCBs在加标水溶液中的回收率分别为70.9％～130％和52.5％～89.1％.日内和日间相对标准偏差分别为1.7％～16.1％和2.4％ ～33.3％.OCPs和PCBs混合标样在10～ 800 μg/L范围内线性相关系数(R2)均大于0.995.OCPs和PCBs方法检测限分别为0.13 ～0.38 ng/L和0.10 ～0.32 ng/L.相比于传统萃取方法,本方法回收率高、萃取时间短、试剂用量少.应用本方法测得北京城区地表水中OCPs和PCBs的含量范围分别为n.d.～ 3.45 ng/L和n.d.～4.88 ng/L.     

π0介子寿命的实验研究

QCD(Quantum Chromo Dynamics)手征反常理论主导了π0介子到两个 γ 光子的衰变.基于手征反常理论和手征微扰论的修正,对π0介子寿命的理论预测精度高达1％.高精度实验测量π0介子的寿命可以严格检验低能区的QCD理论和手征微扰论.本工作重点介绍了三种测量π0介子寿命的实验方法:直接测量法、双光子反...     

HPLC-HG-AFS测定大气颗粒物中砷的形态

采用高效液相色谱-氢化物发生原子荧光光谱联用测定了北京大气颗粒物中As(III),As(Ⅴ),二甲基砷酸(DMA)和一甲基砷酸(MMA)的含量。研究了仪器条件、流动相组成和梯度洗脱程序对砷形态分离的影响。实验结果显示,在优化的色谱与氢化原子荧光检测条件下,采用pH6.0,浓度为10 mmol/L和200 mmol/L NH4H2PO4为流动相A和B,在1~3 min内用60%的A和40%的B洗脱使砷的4种形态达到最佳分离效。As(III),As(Ⅴ),DMA和MMA的检出限为1.45,1.22,1.91和1.64 mg/L,回收率为90.5%~93.2%,相对标准偏差为0.38%~1.7%。方法适用于大气颗粒物中砷的形态分析研究。     

Geometry and optics calibration of WFCTA prototype telescopes using star light

The Large High Altitude Air Shower Observatory (LHAASO) project is proposed to study high energy gamma ray astronomy (40 GeV--1 PeV) and cosmic ray physics (20 TeV--1 EeV). The wide field of view Cherenkov telescope array, as a component of the LHAASO project, will be used to study the energy spectrum and composition of cosmic rays by measuring the total Cherenkov light generated by air showers and the shower maximum depth. Two prototype telescopes have been in operation since 2008. The pointing accuracy of each telescope is crucial for the direction reconstruction of the primary particles. On the other hand, the primary energy reconstruction relies on the shape of the Cherenkov image on the camera and the unrecorded photons due to the imperfect connections between the photomultiplier tubes. UV bright stars are used as point-like objects to calibrate the pointing and to study the optical properties of the camera, the spot size and the fractions of unrecorded photons in the insensitive areas of the camera.     

Dual photopatterning of rotational fingerprint superstructures

Controlling architecture of hierarchical microstructures in liquid crystals (LCs) plays a crucial role in the development of novel soft-matter-based devices. Chiral LC fingerprints are considered as a prospective candidate for various applications;however, the efficient and real-time command of fingerprint landscapes still needs to be improved. Here, we achieve elaborate rotational fingerprint superstructures via dual photopatterning semifree chiral LC films, which combine the photoalignment tec...