Novel synthesis of sensor for selective detection of Fe+3 ions under various solvents

Naked-eye colored chemo dosimeter based on vanilline based conjugated sensor was synthesized and characterized. The main point of this paper is that the solvent also affects on selectivity of metals. Vanilline based conjugate sensor exhibited high selectivity and sensitivity for detection of Ferric ions (Fe⁺³) in all (both polar and nonpolar) solvents according to absorbance which can be observed by naked eye. The selectivity was more prominent in nonpolar or less polar solvent due to solubility factor of ions and sensor but not for polar. The detection of limit of the synthesized probes was shown up to 0.84 ppm. The dielectric constant of solvents affected on the complex formation of ligand with transition metal ions. A filter paper strip system was used for rapid monitoring of detection by color variation.     

基于视觉辐条图案识别方法的蓝宝石引晶机制研究

工业生产蓝宝石晶体过程中,引晶步骤有着至关重要的地位。引晶必须在温度梯度较小,温度分布趋于稳定的条件下进行。目前,工业生产蓝宝石主要依靠人工经验操控籽晶杆实现引晶操作,但是人工引晶操作的准确性不高会导致成品品质不佳、资源浪费。为此,本文提出一种基于蓝宝石视觉辐条图案识别方法来检测蓝宝石熔体状态自由液面状态,从而实现一种高效率引晶的机制。此方法利用经典骨架化算法细化辐条图案,Harris算子实现特征信息的提取,提取的特征信息放入运动轨迹模型中判断熔体稳定性,分析液面温度分布稳定性从而实现引晶。结果表明,此算法具有有效性,蓝宝石晶体引晶效率大大提高,生产出的成品良率也有提升,可有效指导蓝宝石的工业生产。     

热解吸反压低温等离子体电离源质谱检测食品中的邻苯二甲酸酯EI北大核心CSCD

基于低温等离子体设计并实现了一套热解吸反压低温等离子体电离(TD-iLTPI)装置。TD-iLTPI装置由热解吸模块和电离源模块集成在一个π型四通管上组成,进样探针取得样品后插入热解吸模块使其气化,之后随载气进入电离区域被电离。iLTPI内部的针电极接交流电,外部的环形电极接地,电极连接方式与LTP相反。该文对热解吸反压低温等离子体电离源进行了参数的优化,并与三重四极杆质谱联用检测了12种代表性的邻苯二甲酸酯,同时考察了TD-iLTPI-MS的分析性能,并对含有邻苯二甲酸酯的实际样品进行了检测。结果表明,邻苯二甲酸丁苄酯(BBP)的标准曲线具有良好的线性相关系数(R;=0.9958),加标回收率为89.7%~116.8%,相对标准偏差为4.5%~8.2%,对邻苯二甲酸酯的检出限也远低于其他敞开式离子源。对白酒、果汁、面包、奶酪和黄油中的邻苯二甲酸酯进行了快速筛查,并定量检测了果汁中的邻苯二甲酸丁苄酯。     

Moderate Deviation for the Rightmost Position in a Branching Brownian Motion

We study the moderate deviation probability of the position of the rightmost particle in a branching Brownian motion and obtain its moderate deviation function. Firstly, Chauvin and Rouault studied the large deviation probability for the rightmost position in a branching Brownian motion. Recently, Derrida and Shiconsidered lower deviation for the same model. By contrast, Our main result is more extensive.     

An approach to characterization of the agricultural self-propelled machines stability

This paper presents an analytical algorithm with appropriate software specified for the approximation of the allowed critical slope of the solid flat terrain that guarantees static and/or dynamic stability of the specified self-propelled agricultural machines and their aggregates. This algorithm assumes machine as a rigid body, having 3 or 4 contact points (defined by wheels or crawlers), under uniform motion at different constant velocities and radii of curvature trajectories. Using this algorithm, based on the principles of theoretical mechanics combined with 3D analytical geometry, the computer program SSPM (stability of the self-propelled agricultural machines) has been coded. This software is intended to facilitate the analysis, comparison and optimization of different configurations of self-propelled agricultural machines in operation on horizontal and sloped flat terrains at constant velocities and radii of trajectory with respect to their static and dynamic stability. It calculates critical pitch and roll angles of the self-propelled machine and the maximum allowed slope of the flat terrain under the given conditions. The algorithm and the appropriate SSPM software were experimentally verified using the platform and low-scale tractor model. Average difference between calculated and experimental critical values of roll and pitch angles were about 4°     

新型Cd(Ⅱ)-MOF的合成及对4-硝基苯胺的高效识别

采用新型1,3,5-三(1H-苯并[d]咪唑-2-基)苯(TBB)配体及2,5-二羟基对苯二甲酸(H₂dhtp)线性配体, 以Cd(Ⅱ)离子为中心节点, 构筑了具有新型拓扑结构(unj)的手性金属-有机框架材料[Cd(TBB)(dhtp) ](配合物1). 该配合物具有较强的光致发光性能, 可分散在溶液中荧光检测硝基配合物等污染物. 其中, 4-硝基苯胺对配合物1具有高效的荧光猝灭能力, 检测限可低至0.145 mg/L, 并具有较好的选择性.     

Synthesis of mesoporous-silica coated multi-branched gold nanoparticles for surface enhanced Raman scattering evaluation of 4-bromomethcathinone

Mesoporous silica-coated multi-branched gold nanoparticles (bAu@mesoSiO₂) aiming for enhanced Raman sensing for 4-bromomethcathinone (4-BMC) detection is reported. In this work, we present an effective strategy to probe the Raman signal of 4-MBC. Morphologies and optical properties of the synthesized materials with different [Au³⁺]/[Au⁰] ratios are characterized utilizing transmission electron microscopy (TEM), UV–vis and mid-infrared spectroscopy. Both experimental and theoretical (simulation) studies were investigated. Taking advantages of gold core branches that provide highly localized and strongly enhanced electromagnetic fields due to plasmon resonance, surface-enhanced Raman scattering (SERS) is observed. The experimental results show that the SERS intensity exhibits a 100-fold increase with the increased average length and quantity of gold branches (nano tips). The analytical performance yielded a detection limit of 0.1?mg/ml for the 4-MBC target within 5?mins. The sensing method will likely find further improvement and broad use in the forensic science. Besides rapid detection and portability, the combination of the Raman effect and enhanced materials imparts other notable advantages, such as its non-contact and free of reagents.     

常见光谱技术在植物油品质检测中的应用

植物油品质检测技术中,以光谱技术为代表的更为简单方便、快速而不失准确性的无损检测技术为市场所需要。该文从植物油组成成分、市场售卖植物油掺假现状两方面对植物油的品质相关指标进行了介绍,着重介绍了红外光谱技术、拉曼光谱技术、荧光光谱技术、紫外光谱技术等不同光谱技术在植物油品质检测中的研究进展和应用现状,最后提出了光谱技术在植物油品质检测发展中的瓶颈,并对光谱技术在植物油品质检测中应用前景进行了展望。     

氧化石墨烯/多壁碳纳米管负载金铂核壳纳米粒子构建一种三维新型抗坏血酸电化学传感器

该文采用涂覆的方式构建了一种用于灵敏检测抗坏血酸(AA)的电化学传感器。先将多壁碳纳米管(MWCNTs)和氧化石墨烯(GO)混合悬浮液修饰在玻碳电极(GCE)表面,修饰的GO可有效防止MWCNTs聚集,再将具有良好电催化性能的金铂核壳纳米粒子(Au@Pt NPs)修饰在GO/MWCNTs电极上,层层组装构建形成GO/MWCNTs/Au@Pt NPs/GCE三维新型抗坏血酸电化学传感器。该修饰电极在磷酸缓冲溶液中对AA显示了较宽的线性范围和极低的检出限,氧化峰电流与AA浓度在0.005～0.5μmol/L和0.5～1 000μmol/L范围内呈良好的线性关系,相关系数均为0.999,检出限(S/N=3)为4×10~(-9) mol/L,稀释人体血清样品的加标浓度为0.01、0.1、10μmol/L,回收率为90.9%～108%,相对标准偏差(RSD,n=3)为1.2%～2.8%。该修饰电极对AA具有良好的选择性,可有效排除多巴胺、尿酸、葡萄糖等生物小分子的干扰。方法简单、高效、灵敏,可用于临床实际检测。