Removal of single and dual ring thiophene’s from dodecane using cavitation based processes

Utilising cavitation for enhancing oxidative desulphurization has been investigated for nearly-two decades with recent investigations shifting focus from low-capacity acoustic cavitation (AC) to scalable hydrodynamic cavitation (HC). This work focuses on developing a viable means for removing thiophene’s from fuels. In the first phase of this work, use of vortex based HC devices for removal of single and dual ring thiophenes from dodecane was investigated. HC was shown to be able to remove single ring thiophene from dodecane without using any external catalyst or additives. However, in absence of catalyst or additives, it was not possible to remove dual ring thiophenes such as dibenzothiophene using HC. Therefore, in the second phase of this work, various strategies based on use of catalyst or additives to augment cavitation based process were investigated. AC based experiments were opted for shortlisting suitable catalysts and additives for intensifying cavitation based processes. The influence of using oxidant (H₂O₂) and carboxylic acid catalysts on efficacy of removal of dual ring thiophenes is presented. Several conditions were tested, and the optimal volumetric ratios of 0.95 v/v % H₂O₂ and 6.25 v/v % HCOOH was identified and utilised throughout the remainder of the study. Regeneration of extractant which accumulates oxidised sulphur species from dodecane was also investigated using AC. The additives and process conditions reported in this work are useful for enhancing desulphurization performance.     

High-Performance Liquid Chromatographic Method for the Simultaneous Determination of Four Flavonols in Food Supplements and Pharmaceutical Formulations

A method using high-performance liquid chromatography with diode array detection (HPLC-DAD) as a powerful separation technique has been developed for the simultaneous determination of the four flavonols rutin, quercetin, kaempferol and isorhamnetin in food supplements and pharmaceutical formulations. The chromatographic separation was achieved in 36?min using a Symmetry C₁₈ column (250?×?3?mm; 5?µm) as the stationary phase and a mixture of methanol, acetonitrile, and pH 2.5 aqueous acetic acid as the mobile phase in gradient elution mode. The analytical wavelengths were 256?nm for rutin, quercetin and isorhamnetin, and 368?nm for kaempferol. An ultrasound-assisted extraction protocol was performed using methanol as solvent. The detection and quantification limits were lower than 0.03?µg mL^?1 and 0.08?µg mL^?1, respectively. The inter-day and intra-day precisions were less than 4.8 and 5.1%, respectively, and the average recoveries were in the range from 96 to 107%. The method was applied for the determination of the studied flavonols in food supplements and pharmaceutical preparations. The satisfactory recovery values demonstrate the potential of the developed method for the determination of the analytes in these samples. In addition, the method is suitable for routine quality control due its ease of operation.     

On‐chip technology for single‐cell arraying,electrorotation‐based analysis and selective release

This paper reports a method for label‐free single‐cell biophysical analysis of multiple cells trapped in suspension by electrokinetic forces. Tri‐dimensional pillar electrodes arranged along the width of a microfluidic chamber define actuators for single cell trapping and selective release by electrokinetic force. Moreover, a rotation can be induced on the cell in combination with a negative DEP force to retain the cell against the flow. The measurement of the rotation speed of the cell as a function of the electric field frequency define an electrorotation spectrum that allows to study the dielectric properties of the cell. The system presented here shows for the first time the simultaneous electrorotation analysis of multiple single cells in separate micro cages that can be selectively addressed to trap and/or release the cells. Chips with 39 micro‐actuators of different interelectrode distance were fabricated to study cells with different sizes. The extracted dielectric properties of Henrietta Lacks, human embryonic kidney 293, and human immortalized T lymphocytes cells were found in agreements with previous findings. Moreover, the membrane capacitance of M17 neuroblastoma cells was investigated and found to fall in in the range of 7.49 ± 0.39 mF/m².     

Structure transition and photoluminescence of CdS/Si nanoheterostructure array on thermal annealing

CdS/Si heterojunctions have been prepared through growing CdS nanocrystallites (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) by the chemical bath deposition method. Cadmium nanocrystallites (nc-Cd) have been observed and ascribed to the reducibility of Si-NPA. The reason for the appearance of CdO is indistinct and the related work will be done in the future. The blue, green and red emissions are ascribed to the silicon oxide layer, band gap of nc-CdS and the sulphur vacancies, respectively. Redshift and blueshift with the annealing temperature about green emissions are contributed to quantum size effect and the structure transition from nc-Cd to CdO. It is beneficial for investigating the structures and defects to the application of CdS/Si in the optoelectronic field.     

拉曼光谱编码的荧光液相生物芯片检测系统研究

随着医疗诊断需求的增加，生物分子检测技术越来越受到人们的重视，液相生物芯片技术作为一种高通量，多通道的分子检测手段在近几年得到了飞速发展。通过层层自组装方法制备以微片为载体的拉曼光谱编码液相生物芯片，并利用自行搭建的一套高灵敏度、高分辨率的光学系统，实现对液相生物芯片的定性与定量分析。光学系统由拉曼光谱检测系统与荧光显微成像系统耦合而成。在拉曼光谱检测系统中激光器发射出785 nm波长的激光，通过二向色镜，带反反射镜与物镜汇聚到样品上，样品产生的拉曼散射光，经物镜，带反反射镜，二向色镜与拉曼滤波片，最后通过凹透镜聚焦到光谱仪的狭缝上，光谱仪色散实现在线阵CCD上拉曼光谱的获取。荧光显微成像系统应用光学成像原理，通过调节凹透镜与405 nm的激发光之间的距离，使激发光通过物镜均匀的照射到样品之上，样品激发出的荧光，通过物镜，带反反射镜，二向色镜，滤波片与相应的凹透镜，最后成像到面阵CCD上。改进传统便携式拉曼光谱检测系统光路并选用相应波段的带反反射镜与焦距20倍的物镜完成拉曼光谱检测系统与荧光显微成像系统的耦合。为了减少两路系统之间的相互影响选用合适的二向色镜以及滤波片，在提高耦合系统获取数据的准确性中有着重要的作用。该系统通过对反应之后的液相生物芯片进行拉曼光谱检测，以完成对每个编码玻片的定性识别，即解码；同时激发反应后液相生物芯片的荧光并采集荧光强度图，根据每个解码玻片上的荧光强度值完成对目标检测物的定量分析。区别于传统荧光编码液相生物芯片, 拉曼光谱编码具有稳定性更强，光谱分辨率更高等优点。该光学系统集拉曼光谱检测系统与荧光显微成像系统于一体，解决了目前未有基于拉曼编码的液相生物芯片的检测系统的问题，并且可同时对多种目标物进行识别和定量分析，提升了实验结果的准确性。     

Loading rate and confining pressure effect on dilatancy,acoustic emission,and failure characteristics of fissured rock with two pre-existing flaws

Investigating the dilatancy, acoustic emission and failure characteristics of fissured rock are significant to ensure their geotechnical stability. In this paper, the uniaxial and triaxial compression experiments with AE monitoring under different loading rates were carried out on fissured rock specimens with the same geometrical distribution of two pre-existing flaws. The dilatancy and AE activity of these specimens were discussed, and the effects of the confining pressure and loading rate on the mechanical parameters and failure characteristics were analyzed. The results show that the exponential strength criterion is more suitable than the Mohr–Coulomb strength criterion to characterize the strength characteristics of fissured rock. The crack evolution and failure characteristics of fissured rock specimens are more complicated than those of intact rock specimens. The failure characteristics of the fissured rock follow the tensile shear coalescence model, crack branching occurs with increasing the loading rate, and the multi-section coalescence model is verified with increasing the confining pressure. The phenomena of stress drop and yield platform usually occur after the dilatancy onset, the specimen does not fail instantaneously, and the propagation and coalescence of cracks cause a sharp increase in the AE signals, circumferential strain, and volumetric strain.     

多层介质中超声相控阵声场仿真*

由于良好的声束偏转与聚焦特性,超声相控阵已经广泛应用于多层固体介质的缺陷检测。当超声束经过多层介质时,由于反射、透射以及模式转换的存在,多种声束存在于这种结构中,使得声场分析变得复杂。为了提高多层介质检测的准确性,有必要对超声声场的分布规律进行深入地了解。该文结合高斯声束等效点源模型以及射线追踪法,给出了相控阵声源在多层固体介质中激发声场的仿真方法,并且模拟计算了一维线型相控阵在楔块-铝-黄铜-钢四层固体介质中的辐射声场。通过对不同延时法则的计算,实现了声波在这种复杂介质中的偏转与聚焦,进而研究了不同焦点处聚焦声场的分布。结果表明:相控阵方法能使聚焦点处的声场幅值增大,能量集中,提高了检测分辨率;不同聚焦点处声场聚焦效果不同,实际检测时应根据检测区域结构及位置特点,合理放置相控阵换能器。与瑞利积分法的比较表明,该文的仿真方法适用于多层介质相控阵声场的计算。