四极杆/静电场轨道阱高分辨质谱在青椒中农药多残留快速筛查的应用

建立了分散固相萃取法(d-SPE)萃取,高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查青椒中农药多残留的分析方法。样品采用乙腈提取,经N-丙基乙二胺(PSA)和C18分散固相萃取净化,以BEH C18色谱柱为分析柱,0.1%甲酸乙腈及含0.1%甲酸和4 mmol/L甲酸铵水溶液作为流动相进行梯度洗脱分离。采用正、负离子切换,同时对欧盟青椒定性和定量考核样品进行快速筛查,并对定量考核样品筛查到的16种农药进行定量测定。16种农药在一定浓度范围内呈良好的线性关系,相关系数(r2)大于0.995,该方法的定量下限为0.4~2.0μg/kg。在不同加标水平下的平均回收率为81.6%~116.5%,相对标准偏差为0.4%~7.5%。以欧盟青椒定量考核样品为研究对象,对其分别进行四极杆/静电场轨道阱高分辨质谱和三重四极杆质谱测定,结果表明,四极杆/静电场轨道阱高分辨质谱定量结果可与三重四极杆质谱结果相媲美。本方法简单、灵敏、准确,适用于农产品中农药多残留的快速筛查和分析测定,具有很好的实际应用价值。     

扫描电镜附EDS能谱仪的使用与维护

简单描述了扫描电镜中几种样品的制备方法以及操作中需要注意的事项,例如参数的选择、和峰和逃逸峰的处理等,并结合实例进一步简述了如何进行日常保养和维护.     

Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene – a single atomic layer of graphite – is the newest member in the family of carbon allotropes and has emerged as the “celeb” material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.     

Unwinding DNA and RNA with Synthetic Complexes: On the Way to Artificial Helicases

Synthetic helicases can be designed on the basis of ligands that bind more strongly to single‐stranded nucleic acids than to double‐stranded nucleic acids. This can be achieved with ligands containing phenyl groups, which intercalate into single strands, but due to their small size not into double strands. Moreover, two phenyl rings are combined with a distance that allows bis‐intercalation with only single strands and not double strands. In this respect, such ligands also mimic single‐strand binding (SSB) proteins. Exploration with more than 23 ligands, mostly newly synthesised, shows that the distance between the phenyl rings and between those and the linker influence the DNA unwinding efficiency, which can reach a melting point decrease of almost ΔT_m=50 °C at much lower concentrations than that with any other known artificial helicases. Conformational pre‐organisation of the ligand plays a decisive role in optimal efficiency. Substituents at the phenyl rings have a large effect, and increase, for example, in the order of H<F<Cl<Br, which illustrates the strong role of dispersive interactions in intercalation. Studies with homopolymers revealed significant selectivity: for example, with a ligand concentration of 40 μM at 35 °C, only GC double strands melt (ΔT_m=48 °C), whereas the AT strand remains untouched, and with poly(rA)–poly(rU) as an RNA model one observes unfolding at 29 °C with a concentration of only 30 μM .     

空气中激光等离子体通道的三次谐波光谱特性研究

对不同条件下强激光在空气中形成等离子体通道的三次谐波光谱特性进行了研究。单脉冲能量12 mJ,脉宽30 fs,重复频率10 Hz,中心波长795 nm的飞秒激光脉冲经0.5 m焦距的凹面镜聚焦,在空气中形成了等离子体通道, 并在前 向观测到谱线半峰全宽（FWHM）为15 nm的三次谐波。随着脉冲啁啾的变化,三次谐波的光谱出现红移或兰移,当激光脉冲附带+1.3×105fs2的二阶色散时,三次谐波谱线红移且谱峰强度增长了两倍。同时 ,通过改变可编程声光色散滤波器（AOPDF）光谱调制的位置（Hole position）,三次谐波的光谱也发生频移。     

光谱仪联合使用提高谱线的测量宽度

为了提高光谱仪测量谱线的精度,推导出计算机自动控制多光栅转动的光谱仪测试系统的角色散率、线色散率和分辨本领等参量公式,提出一种将两台光谱仪联合使用以提高谱线测量精度的测量方法.理论分析了两台光谱仪联合测激光线宽的原理,并用两台光谱仪联合使用对He-Ne激光谱线宽度进行了测量.实验结果表明,两台光谱仪联合测量He-Ne激光谱线的半峰全宽的放大倍数3.38×105,比单台光谱仪测量至少可以将谱线宽度的测量精度提高5个数量级.     

时域多分辨率分析在色散介质中的应用

将基于Daubechies尺度函数的时域多分辨率分析(Muti-Resolution Time-Domain ,MRTD)方法应用到色散介质的分析中.采用梯形递归卷积（Trapezoidal Recursive Convolution ,TRC）方法,推导出了适合Drude-Lorentz模型的差分方程.通过对一维等离子体和金属铝板反射系数的仿真分析,证明了该方法的正确性和有效性.与基于辅助方程（Auxiliary Difference Equation ,ADE）的MRTD方法相比,该方法可以有效地节约内存和计算时间,并且获得更高的计算精度.     

超声辅助离子液体分散液相微萃取-高效液相色谱法测定废水中雌激素的研究

将离子液体、分散液相微萃取与超声萃取技术结合,采用疏水性离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4 MIM][PF6])为萃取剂,建立了超声辅助离子液体分散液相微萃取-高效液相色谱法分析废水中3种雌激素物质(己烯雌酚、双烯雌酚、己烷雌酚)方法.试验采用50μL的离子液体,考察了溶液体积、溶液pH值、超声时间、静置时间、离心时间等因素对富集效果的影响.最佳的萃取条件为:溶液体积为6 mL,甲醇体积0.3 mL,溶液pH值为2.0,超声时间6min,静置时间30min,离心时间10 min.在优化的萃取条件下,3种雌激素的富集倍数可达到96.8～112.4倍;方法的线性范围为0.5-100.0μg/L;检出限为0.25～0.50μ/L.对浓度为5.0μg/L的3种物质测定6次的相对标准偏差为9.2%～10.8%.     

关于群速超光速特性的实验

实验探讨了在群速超光速的情况下信号传播速度的特点.正弦调幅信号通过失配的传输导线组时在特定的频率下能够出现群速超光速现象.验证了群速超光速在光子晶体中的速度随着导线的延长是起伏变化的,所获得的信号包络传输速度分别为1倍多光速到2倍多光速.当失配线足够长时(实验中为179.8m),甚至出现负群速.实验结果表明群速超光速与通常以光速传递情况的差异不但表现在大小方面,而且还表现在速度值的起伏方面.实验结果揭示了群速超光速传输速度特点与光和电的正常传输情况有明显的区别.     

光速调管FEL的小信号增益理论

利用自由电子激光（FEL）纵模统一理论,系统地分析了光速调管FEL的小信号增益理论,并对色散参数Nd、束流能散度和发射度的影响进行了讨论。