水产品中11种海洋生物毒素的高效液相色谱-四极杆/静电场轨道阱高分辨质谱检测方法研究

建立了水产品中11种海洋生物毒素的高效液相色谱-四极杆/静电场轨道阱高分辨质谱(HPLC-Q-Orbitrap HRMS)检测方法。该方法采用分级提取原理,结合分散固相萃取技术(dSPE)和载体辅助液液萃取技术(SLLE),建立了对亲水性及亲脂性海洋生物毒素的"一站式"提取净化体系。在优化条件下,11种毒素在一定质量浓度范围内具有良好的线性关系,相关系数(r)均大于0.99。该方法对11种毒素的检出限为1～10μg/kg,定量下限为2～20μg/kg,加标回收率为55.6%～122%,相对标准偏差为5.4%～16%。方法快速高效,可操作性强,解决了不同理化性质的海洋生物毒素的通用性检测问题,可满足水产品中海洋生物毒素的快速筛查要求。     

A−H…σ Hydrogen Bonds: Dihydrogen and Cycloalkanes as Proton Acceptors

ωB97XD/aug-cc-pVTZ calculations were performed for complexes of dihydrogen, cyclopropane, cyclobutane and cyclopentane, with simple proton donating species such as hydrogen fluoride, hydrogen chloride, water, hydrogen cyanide and acetylene. Numerous dependencies between geometrical, energetic and topological parameters of complexes considered were found, since various theoretical approaches were applied: Quantum Theory of ‘Atoms in Molecules’ (QTAIM), Natural Bond Orbital (NBO) method and energy decomposition analysis (EDA). It was confirmed that complexes of dihydrogen and cyclopropane are linked through the A−H…σ interactions that may be classified as hydrogen bonds. In the case of complexes of cyclobutane such hydrogen bonds are rather weak. Other type and also weak A−H…C hydrogen bonds are formed for complexes with cyclopentane.     

Comparison between Hydrogen and Halogen Bonds in Complexes of 6-OX-Fulvene with Pnicogen and Chalcogen Electron Donors

Quantum chemical calculations are applied to complexes of 6-OX-fulvene (X=H, Cl, Br, I) with ZH₃/H₂Y (Z=N, P, As, Sb; Y=O, S, Se, Te) to study the competition between the hydrogen bond and the halogen bond. The H-bond weakens as the base atom grows in size and the associated negative electrostatic potential on the Lewis base atom diminishes. The pattern for the halogen bonds is more complicated. In most cases, the halogen bond is stronger for the heavier halogen atom, and pnicogen electron donors are more strongly bound than chalcogen. Halogen bonds to chalcogen atoms strengthen in the order O<S<Se<Te, whereas the pattern is murkier for the pnicogen donors. In terms of competition, most halogen bonds to pnicogen donors are stronger than their H-bond analogues, but there is no clear pattern with respect to chalcogen donors. O prefers a H-bond, while halogen bonds are favored by Te. For S and Se, I-bonds are strongest, followed Br, H, and Cl-bonds in that order.     

基于核酸和蛋白的生物大分子热致液晶研究进展

生物固体大分子诸如核酸、蛋白和病毒颗粒,因其尺寸超出了分子间作用力的范围,升温之后会导致它们降解而无法形成生物大分子的液体形态。 因此,发展新型的合成和制备策略,实现无溶剂包覆的生物大分子的流体态及其应用,是一个崭新的研究领域。 结合我们前期工作,简要介绍了核酸、蛋白流体(液晶态和液体态)材料的制备及性质。 借助静电力自组装,上述生物大分子能够与带有相反电荷的表面活性剂结合,形成热致液晶材料,其热致液晶性质使得生物分子具有长程有序性和流动性,在此基础上,可以探索生物大分子在无水环境下的技术应用。     

食品中99种兽药的一步式提取净化体系

建立了99种禁限用兽药的一步式提取净化体系,并通过高效液相色谱-四极杆/静电场轨道阱高分辨质谱（UHPLC-Q-Orbitrap HRMS）对其效果进行了评价。该提取净化体系基于载体辅助液液萃取技术,通过一次性前处理,完成常见的理化性质差异很大的8大类共计99种兽药残留的提取、净化工作,同时结合四极杆静电场轨道阱高分辨质谱实现了99种兽药残留的一步式多残留筛查。采用此体系对样品禁限用兽药进行测定分析,结果表明,该方法对液态乳、猪肉、鱼类等食品基质具有较强的适用性,检测的99种兽药线性范围为0.001~0.1 μg/mL,定量限为0.5~20.0 μg/kg,加标回收率为60%~120%,相对标准偏差小于15%。该方法的前处理和仪器分析过程对不同理化性质的化合物的兼容性强,检测效率高,可操作性强,检出限能满足所有受试的目标物,并且大大降低了检测成本。     

反相悬浮聚合法制备硫氰酸根阴离子印迹微球及其离子识别性质

利用反相悬浮聚合法, 成功制备了微米级硫氰酸根(SCN^-)阴离子印迹微球。 以溶有分散剂Span-60的环已烷为分散介质, 以溶有模板阴离子SCN^-、阳离子单体丙烯酰氧乙基三甲基氯化铵(DAC)及交联剂N, N'-亚甲基双丙烯酰胺(MBA)的水溶液为分散相, 构成反相悬浮聚合体系, 在水相液滴中使DAC发生交联聚合, 成功制备了粒径约为200 μm的离子印迹微球(IIPMs)。 以同为一价阴离子的NO₃^-和I^-为对比离子, 深入考察研究了该离子印迹微球的离子识别与结合特性。 研究结果表明, 凭借强静电相互作用, 在水相液滴中, 阳离子单体DAC与模板阴离子SCN^-紧密相结合, 故在DAC交联聚合的同时, 实现了阴离子SCN^-的印迹。 所制备的阴离子印迹微球IIPMs对模板阴离子SCN^-具有很高的结合能力(结合容量为3.3 mmol/g(192 mg/g))和特异的识别选择性。 该印迹微球可选择性地识别与结合离子混合溶液中的SCN^-离子, 相对于NO₃^-和I^-阴离子, IIPMs对SCN^-阴离子的选择性系数分别为3.24和6.78。 该印迹微球还具有优良的重复使用性能。     

Suppression of chaos in a MEMS resonator by delayed position feedback

A delayed position feedback control is applied on DC voltage source for suppressing chaos of a typical MEMS resonator actuated by electrostatic forces. A theoretical necessary condition for chaotic oscillation of the controlled system is presented. Numerical results and the analytical prediction reveal the evolution of dynamical behavior of the system with AC voltage amplitude and the control effect of delayed feedback on reducing chaos of the system. It shows that the delayed feedback control is effective on suppressing chaos of the micro mechanical resonator.     

Direct Metallization of Gold Nanoparticles on a Polystyrene Bead Surface using Cationic Gold Ligands

Gold nanoparticles are formed to cover the surface of sulfonated‐polystyrene (PS) beads by the in‐situ ion‐exchange and chemical reduction of a stable cationic gold ligand, which makes it different from the physical adsorption or multiple electroless metallization methods. PS beads are synthesized by dispersion polymerization with a diameter of 2.7 µm, and their surface is modified by introducing sulfonic acid groups (SO) to give an ion exchange capacity of up to 2.25 mequiv. · g⁻¹, which provides 1.289 × 10¹⁰ SO per bead. Subsequently, the anionic surface of the PS beads is incorporated with a cationic gold ligand, dichlorophenanthrolinegold(III) chloride ([AuCl₂(phen)]Cl), through an electrostatic interaction in the liquid phase to give gold nanoparticles (ca. 1–4 nm in diameter) formed on the PS surface. Assuming that approximately three SO groups interact with one [AuCl₂(phen)]⁺ ion in the ion‐exchange process, the gold coverage on a PS bead is estimated as 12.0 wt.‐%, which compares well with the 16.8 wt.‐% of gold loading measured by inductively coupled plasma–mass spectrometry. Because of the adjustable IEC values of the polymer surface and the in‐situ metallization of Au in the presence of S atoms, both of which are of a soft nature, the developed methodology could provide a simple and controllable route to synthesize a robust metal coating on the polymer bead surface.

     

大分子体系的量子化学分块方法

碎片化方法为量子化学方法的发展以及在大分子体系的应用开辟了新的道路。在过去的十年里,我们见证了该领域的诸多成果,并且我们相信该方法的发展仍将持续下去。这篇文章简单回顾了近期碎片化方法在大分子电子结构计算领域的进展,重点突出中国学者在该领域的贡献。     

Influence of Generalized (r, q) Distribution Function on Electrostatic Waves

Non-Maxwellian particle distribution functions possessing high energy tail and shoulder in the profile of distribution function considerably change the damping characteristics of the waves. In the present paper Landau damping of electron plasma (Langmuir) waves and ion-acoustic waves in a hot, isotropic, unmagnetized plasma is studied with the generalized (r,q) distribution function. The results show that for the Langmuir oscillations Landau damping becomes severe as the spectral index r or q reduces. However, for the ion-acoustic waves Landau damping is more sensitive to the ion temperature than the spectral indices.