Oligonucleotide‐Based Luminescent Detection of Metal Ions

Metal ions are prevalent in biological systems and are critically involved in essential life processes. However, excess concentrations of metals can pose a serious danger to living organisms. Oligonucleotides represent a versatile sensing platform for the detection of various molecular entities including metal ions. This review summarizes the recent advances in the development of oligonucleotide‐based luminescent detection methods for metal ions.     

固相萃取地表水中痕量联苯胺及HPLC-MS测定

采用固相萃取及高效液相色谱-串联质谱技术,建立了地表水中痕量联苯胺的测定方法.水样经HLB固相萃取柱富集,二氯甲烷与丙酮(1:1,v/v)洗脱,氮吹后转为甲醇溶剂,以液相色谱串联质谱选择离子监测(SRM)模式定性、定量分析.在本实验条件下,加标回收率在72.0%～94.0%之间,相对标准偏差8.1%～9.8%(n=7)...     

外电场对CO分子及离子性质的调制和降解

基于密度泛函理论(DFT)的B3LYP方法,在6-311G++基组水平上,计算研究外加电场下CO分子及离子物理性质,包括总能量、键长、电荷分布、能级分布和红外光谱,并根据势能曲线研究CO外加电场下的降解。随着外电场逐渐增大(- 0.015 a. u.~0.015 a. u.),CO的性质发生明显的变化, 电场增大到一定程度时可实现CO分子降解。同样,CO⁺离子的总能量随电场的增大逐渐减小,键长变长,偶极矩逐渐变大,分子能隙在Alpha轨道中逐渐减小,在Beta轨道中逐渐增大,红外光谱的强度相应逐渐增大。电场从0.0 a. u增大到0.150 a. u.时,势能曲线的变化同样表明CO⁺离子离解能减小。电场增大到一定程度时可实现CO⁺离子降解。     

溶剂极性对1，5-二羟基蒽醌分子双质子转移过程的影响

具有激发态分子内双质子转移特性的分子在荧光传感器、激光材料、生物分子探针等领域具有广泛的应用. 羟基蒽醌作为蒽醌类化合物是自然界中广泛存在且具有质子转移特性的次级代谢物,其衍生物已被广泛研究并成功应用于染料、免疫增强和抗癌药物. 近年来,1,5-二羟基蒽醌(1,5-DHAQ)作为一种具有两个分子内氢键的羟基蒽醌衍生物受到了广泛的关注. 本文采用飞秒瞬态吸收光谱结合含时密度泛函理论方法研究了溶剂极性对1,5-DHAQ分子激发态分子内双质子转移过程的影响. 1,5-DHAQ分子在甲苯、四氢呋喃和乙腈溶剂中的稳态荧光光谱表明,溶剂极性的改变对1,5-DHAQ的荧光峰位置产生了影响. 瞬态吸收光谱表明,溶剂极性的增大加快了质子转移的速率. 超快动力学拟合结果表明,溶剂极性的增大有助于加快1,5-DHAQ分子中的激发态分子内双质子转移过程. 此外,通过理论计算得到的势能曲线分析表明质子转移的能垒随着溶剂极性的增加而逐渐减小,从而促进1,5-DHAQ分子激发态分子内双质子转移过程的发生,这进一步验证和解释了实验结果. 本工作有助于开发和合成更稳定、高效的羟基蒽醌衍生物.     

Effects of pulse energy ratios on plasma characteristics of dual-pulse fiber-optic laser-induced breakdown spectroscopy

Laser-induced plasmas of dual-pulse fiber-optic laser-induced breakdown spectroscopy with different pulse energy ratios are studied by using the optical emission spectroscopy(OES)and fast imaging.The energy of the two laser pulses is independently adjusted within 0–30 m J with the total energy fixed at 30 m J.The inter-pulse delay remains 450 ns constantly.As the energy share of the first pulse increases,a similar bimodal variation trend of line intensities is observed.The two peaks are obtained at the point where the first pulse is half or twice of the second one,and the maximum spectral enhancement is at the first peak.The bimodal variation trend is induced by the change in the dominated mechanism of dual-pulse excitation with the trough between the two peaks caused by the weak coupling between the two mechanisms.By increasing the first pulse energy,there is a transition from the ablation enhancement dominance near the first peak to the plasma reheating dominance near the second peak.The calculations of plasma temperature and electron number density are consistent with the bimodal trend,which have the values of 17024.47 K,2.75×10¹⁷cm;and 12215.93 K,1.17×10¹⁷cm;at a time delay of 550 ns.In addition,the difference between the two peaks decreases with time delay.With the increase in the first pulse energy share,the plasma morphology undergoes a transformation from hemispherical to shiny-dot and to oblate-cylinder structure during the second laser irradiation from the recorded images by using an intensified charge-coupled device(ICCD)camera.Correspondingly,the peak expansion distance of the plasma front first decreases significantly from 1.99 mm in the single-pulse case to 1.34 mm at 12/18(dominated by ablation enhancement)and then increases slightly with increasing the plasma reheating effect.The variations in plasma dynamics verify that the change of pulse energy ratios leads to a transformation in the dual-pulse excitation mechanism.     

ICP-MS法测定高纯铝中杂质不确定度的评定

利用ICP-MS测定高纯铝中杂质。用建立数学模型的方法对结果的不确定度进行评估和计算。对试料的称重、标准溶液的配制、工作曲线的拟合、测量重复性的各分量不确定度进行分析。得到了各分量不确定度和合成不确定度,最终得出更加客观的结果。     

Zinc oxide nanotubes decorated with silver nanoparticles as an ultrasensitive substrate for surface-enhanced Raman scattering

We introduce a novel voltammetric method, so-called sinusoidal envelope voltammetry, for use in electronic tongues. Fourier transformation was used to transform the data of the signal from the time domain to the frequency domain. The four taste substances, acesulfame potassium, monosodium glutamate, potassium chloride and tartaric acid, are shown to exhibit abundant frequency characteristics in the power spectrum of a Fourier transformation. This indicates that the power spectrum from sinusoidal envelope voltammetry can be used as fingerprints of samples for classification. Principal component analysis along with discrimination index and multi-frequency large amplitude pulse voltammetry as a reference technique is used to evaluate the separation ability of sinusoidal envelope voltammetry. The score plots of the method for the four taste substances and for the five brands of Jiafan rice wine show better discrimination ability than multi-frequency large amplitude pulse voltammetry. Sinusoidal envelope voltammetry is considered to be a promising technique for use in voltammetric electronic tongues.

Detection of DNA hybridization by various spectroscopic methods using the copper tetraphenylporphyrin complex as a probe

We are presenting new and highly sensitive hybridization assays. They are based on various spectroscopic methods including resonance light scattering, circular dichroism, ultraviolet spectra and fluorescence spectra, as well as atomic force microscopy, and relies on the interaction of the Cu(II), Ni(II), Mg(II), Co(II), Cd(II), and Zn(II) complexes, respectively, of tetraphenylporphyrin (TPP) with double-strand DNA (dsDNA) and single strand DNA (ssDNA). The interaction results in amplified resonance light scattering (RLS) signals and enables the detection of hybridization without the need for labeling DNA. The RLS signals are strongest in case of the Cu (II)-TPP complex which therefore was selected as the probe. The technique is simple, robust, accurate, and can be completed in less than one hour.

土卫六探测器高超声速化学非平衡特性数值计算

为了研究土卫六探测器在地球大气和土卫六大气中飞行时气动热环境的差异,采用数值模拟的方法分别对地球大气成分和土卫六大气成分下探测器前方流场内气动热环境进行了研究,得到如下结论:与地球大气条件相比,土卫六大气条件下探测器表面的热流密度较高,其峰值可达到地球大气条件的1倍以上.探测器表面的热流密度先随着高度的减小而增加,而后...     

18F-labeled pyrazolo[1,5-a]pyrimidine derivatives: synthesis from 2,4-dinitrobenzamide and tosylate precursors and comparative biological evaluation for tumor imaging with positron emission tomography

We previously reported 18F-labeled pyrazolo[1,5-a]pyrimidine derivatives: 7-(2-[18F]fluoroethylamino)-5-methylpyrazolo[1,5-a]pyrimidine-3-carbonitrile ([18F]1) and N-(2-(3-cyano-5-methylpyrazolo[1,5-a]pyrimidin-7-ylamino)ethyl)-2-[18F]fluoro-4-nitro- benzamide ([18F]2). Preliminary biodistribution experiments of both compounds showed s slow clearance rate from excretory tissues which warranted further investigation for tumor imaging with PET. Here we modified [18F]1 and [18F]2 by introducing polar groups such as ester, hydroxyl and carboxyl and developed three additional 18F-18 labeled pyrazolo[1,5-a] pyrimidine derivatives: (3-Cyano-7-(2-[18F]fluoroethylamino)pyrazolo[1,5-a]-pyrimidin-5- yl)methyl acetate ([18F]3), 7-(2-[18F]fluoroethylamino)-5-(hydroxymethyl)pyrazolo[1,5-a]- pyrimidine-3-carbonitrile ([18F]4) and (S)-6-(3-cyano-5-methylpyrazolo[1,5-a]pyrimidin-7-ylamino)-2-(2-[18F]fluoro-4-nitrobenzamido)hexanoic acid ([18F]5). The radiolabeled probes were synthesized by nucleophilic substitution of the corresponding tosylate and nitro precursors with 18F-fluoride. In Vitro studies showed higher uptake of [18F]3 and [18F]4 than that of [18F]5 by S180 tumor cells. In Vivo biodistribution studies in mice bearing S180 tumors showed that the uptake of both [18F]3 and [18F]4 in tumors displayed an increasing trend while the uptake of [18F]5 in tumor decreased through the course of the 120 min study. This significant difference in tumor uptake was also found between [18F]1 and [18F]2. Thus, we compared the biological behavior of the five tracers and reported the tumor uptake kinetic differences between 2-[18F]fluoroethylamino- and 2-[18F]fluoro-4-nitro- benzamidopyrazolo[1,5-a] pyrimidine derivatives.