基于碳量子点和罗丹明B的新型比率荧光试纸片检测水中Hg(Ⅱ)

水环境中Hg(Ⅱ)的污染对生态环境和人类健康危害极大，目前Hg(Ⅱ)的检测主要有原子光谱/质谱和电化学等方法，但存在检测仪器昂贵、操作繁琐及前处理复杂等缺点，难以在日常水环境中微量Hg(Ⅱ)现场检测的应用。因此，建立一种灵敏、准确、快捷和经济的水中Hg(Ⅱ)检测方法具有重要意义。试纸法是将普通的化学反应从玻璃仪器转移到试纸上进行的一种快速检测方法，利用试剂与目标物之间产生的化学反应，通过颜色的变化可对目标物进行定性或半定量检测，具有操作简便、快速等优点。碳量子点是一类粒径小于10 nm的碳基纳米材料，具有优异的荧光性能、较低的毒性和较高的化学稳定性。利用Hg(Ⅱ)对碳量子点的荧光具有灵敏和高效的猝灭作用，构建了一种双色比率荧光试纸片用于快速检测水中微量Hg(Ⅱ)的含量。其中，采用氮掺杂水溶性碳量子点（NCDs）作为荧光响应信号、罗丹明B（RhB）作为荧光内标信号，在单一波长（355 nm）激发下产生位于440和580 nm的双色荧光发射峰。当体系加入不同浓度Hg(Ⅱ)后，NCDs表面官能团与Hg(Ⅱ)之间的静电作用和金属配位协同作用使荧光发生猝灭，而RhB的荧光信号保持不变，利用440和580 nm双色荧光信号或其强度的比值（F₄₄₀/F₅₈₀），可实现对微量Hg(Ⅱ)的快速检测。实验对检测条件进行了优化，结果表明在HAc-NaAc缓冲液浓度为1 mmol·L-1、pH为7的条件下，F₄₄₀/F₅₈₀值与Hg(Ⅱ)浓度（0～3 μmol·L-1）呈现良好的线性关系，线性方程为F₄₄₀/F₅₈₀=-0.785 2ｃ_Hg(Ⅱ)+3.103 8，相关系数r＞0.99，以3倍标准偏差计算的检出限为2.7 nmol·L-1(n=9)。对湖水与自来水中Hg(Ⅱ)进行加标回收实验，其加标回收率在91.9%～117.9%之间，说明该方法灵敏、准确，能用于水中Hg(Ⅱ)的检测。同时，将NCDs和RhB浸渍于尼龙片上构建了双色比率荧光检测试纸片，在紫外灯（365nm）照射下可观测到试纸发射淡蓝紫色荧光。而随着Hg(Ⅱ)浓度的增加，荧光颜色从淡蓝紫色到橙色发生变化，每次检测时间只需3分钟，裸眼可检出Hg(Ⅱ)浓度低至10 nmol·L-1，实现了对水中微量Hg(Ⅱ)的灵敏、快速检测。此外，该方法对Hg(Ⅱ)的检测表现出良好的特异性。因此，基于碳量子点和罗丹明B构建的双色比率荧光试纸片具有携带方便、操作简单，以及灵敏和快速等优点，为水中微量Hg(Ⅱ)的快速检测提供了新的方法和思路。     

An experimental method for eliminating effect of rigid out-of-plane motion on 2D-DIC

The out-of-plane motion is one of the most important factors that affect the precision of two-dimensional digital image correlation (2D-DIC). In this paper, a novel solution is presented to improve conventional 2D-DIC by eliminating the effect of out-of-plane motion, including translation and rotation. Firstly, an experimental technique using two projected laser strips is proposed to measure the out-of-plane motion of a planar specimen. A theoretical model is then established to predict the pseudostrains caused by out-of-plane motion based on the pin-hole imaging model. Using the measured out-of-plane displacement, the captured deformed images used in 2D-DIC are amended to eliminate the effect of out-of-plane motion by the theoretical model. Finally, two experiments were conducted to validate the effectiveness of the proposed method. Results indicate that application of the proposed method can effectively eliminate the errors caused by out-of-plane motion.     

A novel lipid droplets-targeting fluorescent probe based on dicyanisophorone and carbazole for Cu2+ and its application

A novel fluorescent probe, LCH , based on dicyanisophorone and carbazole, was prepared for the visual detection of Cu²⁺. The probe LCH could recognize Cu²⁺ by fluorescence quenching in EtOH/H₂O (1/4, v/v) solution, which could be easily identified under the 365 nm UV lamp, and the detection limit was as low as 0.785 μM. The recognition mechanism of probe LCH with Cu²⁺ was determined by combining ¹H NMR titration, MS, and theoretical calculations. Practical application experiments showed that probe LCH could be used to detect Cu²⁺ in the test strip experiments. Cell imaging experiments showed that the probe LCH owned good cell permeability and could be applied to the imaging of Cu²⁺ in HepG2 cells. In addition, fluorescence colocalization experiments showed that LCH could target lipid droplets. These results indicate that the probe LCH will have a good application prospect in environmental detection and clinical medicine.     

基于新型量子点荧光微球的氯霉素免疫层析试纸条的制备和应用

以羧基化CdTe/ZnSe量子点荧光微球为标记物,通过1-乙基-(3-二甲基氨基丙基)碳二亚胺/N-羟基琥珀酰亚胺(EDC/NHS)活化法将氯霉素(CAP)单克隆抗体与量子点荧光微球偶联制备荧光探针.氯霉素全抗原(CAP-HS-BSA)及羊抗鼠二抗分别喷涂硝酸纤维素膜,形成检测线(T线)和质控线(C线),组装成新型氯霉素量子点荧光微球免疫层析试纸条,建立了快速、定量检测牛奶中CAP的方法.本研究开发的量子点荧光微球试纸条可在15 min内完成牛奶样品中CAP的定量检测,线性范围为0.1~100.0μg/L,检出限为0.1μg/L.牛奶样品CAP的加标回收率为93.3%~97.9%,相对标准偏差在4.9%~6.9%之间.     

基于光纤智能夹层传感结构的应力测量研究

制作了一种模块化的光纤传感夹层,对夹层内的光纤传感器的应力特性进行了实验研究。分析了应变对传感系数的影响,对埋入到光纤智能夹层中的两种光纤传感器的输出特性进行了比较。实验结果表明:光纤Bragg光栅传感器的波长漂移与应变之间具有理想的线性关系,但应变灵敏度由1.2pm/με降至1.15pm/με;由于制作工艺的局限,对于非本征F-P光纤传感器,当应变达到350με后,应变与载荷具有较好的线性响应。与非本征F-P光纤传感器相比,光纤Bragg光栅传感器是光纤智能夹层首选的应变传感器。将埋入了Bragg光栅传感器的智能夹层粘贴于某型飞机的翼-身连接构件内部进行监测,实验结果为光纤智能夹层应用于复合材料结构的应变监测提供了参考。     

MODEL SHIFT AND STRANGE ATTRACTOR ON MBIUS STRIP

A new model shift mapping was given in bilateral symbol space. It is topologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, a model was constructed correspondent to the model shift mapping, i.e., a class of mapping on Mbius strip was given. Its attractors’ structure and dynamical behaviour were described.     

Griffith crack moving in a piezoelectric strip

Summary  The dynamic problem of an impermeable crack of constant length 2a propagating along a piezoelectric ceramic strip is considered under the action of uniform anti-plane shear stress and uniform electric field. The integral transform technique is employed to reduce the mixed-boundary-value problem to a singular integral equation. For the case of a crack moving in the mid-plane, explicit analytic expressions for the electroelastic field and the field intensity factors are obtained, while for an eccentric crack moving along a piezoelectric strip, numerical results are determined via the Lobatto–Chebyshev collocation method for solving a resulting singular integral equation. The results reveal that the electric-displacement intensity factor is independent of the crack velocity, while other field intensity factors depend on the crack velocity when referred to the moving coordinate system. If the crack velocity vanishes, the present results reduce to those for a stationary crack in a piezoelectric strip. In contrast to the results for a stationary crack, applied stress gives rise to a singular electric field and applied electric field results in a singular stress for a moving crack in a piezoelectric strip. Received 14 August 2001; accepted for publication 24 September 2002 The author is indebted to the AAM Reviewers for their helpful suggestions for improving this paper. The work was supported by the National Natural Science Foundation of China under Grant 70272043.     

Thermal analysis of the roll in the strip casting process

Coiled strip can be directly produced through the twin-roll strip casting process from the melt by incorporating casting and hot rolling together into a single step. In this unique process, the strip formation from the molten metal critically relies upon the casting rolls. Thus, the design of the rolls is extremely essential. The coupled heat transfer and deformation analysis of the casting roll is carried out in a two-dimensional numerical model, using a finite element program (MARC) to examine the thermal stress and displacement. The effects of several factors such as the nickel overlay thickness on the roll surface, the casting speed, and the roll diameter on thermal characteristics are investigated.     

光纤光栅传感器在大体积混凝土基础温度监测中的应用

光纤光栅传感器具有体积小、质量轻、灵敏度高、耐腐蚀、抗电磁干扰、传输频带较宽、易于进行分布式测量等诸多其他传感器所不具备的优点,更适用于现场的长期健康监测。大体积混凝土在施工过程中的温度问题如处理不当将会引起混凝土开裂。利用温度计、热电耦等作为传感器的传统的检测手段已经大大的制约了数据的准确性与精度。寻求一种高精度温度检测手段已经成为用于现场结构监测的前提。本文结合具体的工程实例介绍了光纤光栅传感器在基础混凝土温度监测中的应用,介绍了监测系统的组成,传感器的构造和标定,并利用实测温度预测基础混凝土底板中温度应力,及时采取措施防止混凝土的开裂。     

TORSIONAL IMPACT RESPONSE OF A PENNY-SHAPED CRACK IN A FUNCTIONAL GRADED STRIP

The torsional impact response of a penny-shaped crack in a nonhomogeneous strip is considered. The shear modulus is assumed to be functionally graded such that the mathematics is tractable. Laplace and Hankel transforms were used to reduce the problem to solving a Fredholm integral equation. The crack tip stress field is obtained by considering the asymptotic behavior of Bessel function. Explicit expressions of both the dynamic stress intensity factor and the energy density factor were derived. And it is shown that, as crack driving force, they are equivalent for the present crack problem. Investigated are the effects of material nonhomogeneity and strip‘s highness on the dynamic fracture behavior.Numerical results reveal that the peak of the dynamic stress intensity factor can be suppressed by increasing the nonhomogeneity parameter of the shear modulus, and that the dynamic behavior varies little with the adjusting of the strip‘ s highness.