Green Determination of Total Iron in Water by Digital Image Colorimetry

A green iOS digital image colorimeter was fabricated for the determination of total iron in natural water. A mobile application operating on an iOS device was designed using Euclidean distance theory to perform iron determination. The application records the components of the color by storing red, green, and blue values as well as calculating the hue, saturation, brightness, and gray values using standard color theory. The component values obtained from the images of orange solutions of iron(II) complex with 1,10-phenanthroline were collected in a database and used for evaluation of the total iron concentration in water samples. Under the optimal conditions for solid-phase extraction used for sample preconcentration, the enrichment factor was 8.18. The iron concentration was determined by this device for concentrations from 0.01 to 1.0?ppm. The iOS digital image colorimeter achieved a limit of quantitation of 0.1?ppm. The accuracy and precision of the iOS digital image colorimeter were validated using a certified reference material, riverine water. The instrumentation was used for the analysis of natural water samples.     

Failure prediction of hybrid composite using Arcan's device and Drucker-Prager model

Hybrid composites are promising materials due the possibility of combining the properties of different fiber types with those of the polymeric matrix. The higher number of phases involved in this kind of material and the hydrostatic component of polymer behavior make it unfeasible to use classic models for failure prediction, like the Von Mises or Treska models. In this study, a modified Arcan's device was applied for mechanical characterization of a polymeric blend matrix composite reinforced with randomly oriented continuous fibers (a clutch disc) to generate combined loading conditions. Experimental results were applied in the Von Mises and Drucker-Prager theoretical models for failure prediction. Additionally, scanning electron microscopy (SEM) was applied to analyze the fracture surface. The failure envelope provided by the Drucker-Prager model fit the experimental results, making it a promising tool for predicting the behavior of this type of hybrid composite.     

Hydrogel microfluidic co‐culture device for photothermal therapy and cancer migration

We developed the photo‐crosslinkable hydrogel microfluidic co‐culture device to study photothermal therapy and cancer cell migration. To culture MCF7 human breast carcinoma cells and metastatic U87MG human glioblastoma in the microfluidic device, we used 10 w/v% gelatin methacrylate (GelMA) hydrogels as a semi‐permeable physical barrier. We demonstrated the effect of gold nanorod on photothermal therapy of cancer cells in the microfluidic co‐culture device. Interestingly, we observed that metastatic U87MG human glioblastoma largely migrated toward vascular endothelial growth factor (VEGF)‐treated GelMA hydrogel‐embedding microchannels. The main advantage of this hydrogel microfluidic co‐culture device is to simultaneously analyze the physiological migration behaviors of two cancer cells with different physiochemical motilities and study gold nanorod‐mediated photothermal therapy effect. Therefore, this hydrogel microfluidic co‐culture device could be a potentially powerful tool for photothermal therapy and cancer cell migration applications.     

Effective length calibration method for processing the fluorescence signal detected by charge‐coupled device in capillary electrophoresis

A novel method named effective length calibration method has been developed to process the fluorescence signal detected by charge‐coupled device during capillary electrophoresis. The new method treated each pixel as an individual point detector, and effectively binned a large number of pixels into a final electropherogram without losing the narrow detection window defined by a single pixel. Capillary electrophoresis separations of DNA were carried out and detected by charge‐coupled device and conventional detector (photomultiplier tube). Detection properties including signal‐to‐noise ratio, peak width, detection frequency, and tilt of detector were investigated. It was found that the new method achieved much higher signal‐to‐noise ratio and smaller peak width than the conventional detector did. A Detection width of 0.5 μm was easily achieved.     

On the stability of Timoshenko-type systems with internal frictional dampings and discrete time delays

In this paper, we consider a vibrating system of Timoshenko-type in a bounded one-dimensional domain under Dirichlet–Dirichlet or Dirichlet–Neumann boundary conditions with one or two discrete time delays and one or two internal frictional dampings. First, we show that the system is well posed in the sens of semigroup theory. Second, we prove the exponential stability regardless to the speeds of wave propagation of the system if the weights of the time delays are smaller than the ones of the corresponding dampings, respectively. However, when the weight of one time delay is not smaller than the one of the corresponding damping, we prove the exponential stability in case of equal-speed wave propagation, and the polynomial stability in the opposite case.     

Existence and exact controllability of fractional evolution inclusions with damping

The aim of this paper is to deal with the existence of mild solutions and exact controllability for a class of fractional evolution inclusions with damping (FEID, for short) in Banach spaces. Firstly, we provide the representation of mild solutions for FEID by applying the method of Laplace transform and the theory of (α,κ)‐regularized families of operators. Next, we are concerned with the existence and exact controllability of FEID under some suitable sufficient conditions by using the method of measure of noncompactness and an appropraite fixed point theorem. Finally, an application to nonlinear partial differential equations with temporal fractional derivatives is presented to illustrate the effectiveness of our main results. Copyright © 2017 John Wiley & Sons, Ltd.     

UiO-66 and hcp UiO-66 Catalysts Synthesized from Ionic Liquids as Linker Precursors

Using ionic liquids (ILs) as linker precursors, the well-known metal-organic framework (MOF) UiO-66 (Universitetet i Oslo) and the recently reported MOF hcp UiO-66 (hexagonal closed packed) have been successfully synthesized and characterized. The advantage of the applied novel synthesis approach is an economically and environmentally benign work-up procedure, due to the better solubility of the IL. Additionally, the reactivity of the terephthalate anions is increased compared to terephthalic acid, resulting in faster MOF formation with an increased amount of defects in the MOF structure. In order to explore to the influence of defects on the catalytic performance, the cyclisation of citronellal to isopulegol was employed as test reaction. The activity of hcp UiO-66 and fcc UiO-66 (face centered cubic) is improved compared to other MOF or zeolite based catalysts, while the selectivity is similar.     

无溶剂法大量制备高效红光碳点及其在白光器件中的应用

以邻苯二胺、 2,5-二氨基苯磺酸和三氯化铝为原料, 通过无溶剂法大量制备了高效的红色荧光碳点 (R-CDs). 制得的碳点尺寸大约为2.4 nm, 含有13%的氮元素, 主要由高度石墨化的碳核及覆盖在其表面的大量官能团构成. 在不同的波长光激发下, 碳点在乙醇溶液中表现出不依赖于激发的红光发射, 其荧光峰位于 704 nm, 最大量子产率达到22%. 由于R-CDs具有优异的光学性质, 利用其构筑了紫外光激发的碳基白色发光二极管, 其色坐标为(0.33, 0.33), 非常接近自然光. 该研究为高效红色荧光碳点的大量制备提供了一种新路径, 同时拓宽了其在白光器件中的应用.     

在体酶生物燃料电池的研究进展

酶生物燃料电池(Enzymatic biofuel cells,EBFCs)具有高专一性和催化性能,可催化与氧化还原反应有关的燃料并获得电能.可用的生物燃料,如葡萄糖、乳酸和丙酮酸盐,可以从汗液、泪液和血液中提取,因而以体液为燃料的EBFCs在可植入式或可穿戴式设备中具有良好的应用前景.采用生物电催化机理对酶生物燃料电池在体液发电中的应用进行了研究,以及对可植入式或可穿戴式生物燃料电池的主要挑战和未来的前景进行了展望.     

A Complex Mode Method for Wind-Induced Responses of 6-Parameter Practical Viscoelastic Damping Energy Dissipation Structures Based on the Davenport Wind Speed Spectrum北大核心CSCD

针对六参数实用黏弹性阻尼耗能结构,基于Davenport风速谱系列响应问题进行了系统的研究.首先,利用六参数黏弹性阻尼器的微分型本构关系,建立了耗能结构基于Davenport风速谱激励下的运动方程;然后,运用复模态法将耗能结构的运动方程由二阶微分方程转化为一阶方程,获得了耗能结构系统对风振激励响应的频域解和功率谱密度函数表达式;最后,利用数学恒等式,基于随机振动理论获得了耗能结构系统在Davenport风速谱激励下的响应和阻尼器受力的解析解.该文方法不仅考虑了结构系统在风振激励作用下全振型展开的结果,表达式较现有结果更为简便,效率及精度更高,且适用于非经典阻尼结构.