Numerical and sensitivity analysis of MHD bioconvective slip flow of nanomaterial with binary chemical reaction and Newtonian heating

The impact of Stefan blowing on the MHD bioconvective slip flow of a nanofluid towards a sheet is explored using numerical and statistical tools. The governing partial differential equations are nondimensionalized and converted to similarity equations using apposite transformations. These transformed equations are solved using the Runge–Kutta–Fehlberg method with the shooting technique. Graphical visualizations are used to scrutinize the effect of the controlling parameters on the flow profiles, skin friction coefficient, local Nusselt, and Sherwood number. Moreover, the sensitivities of the reduced Sherwood and Nusselt number to the input variables of interest are explored by adopting the response surface methodology. The outcomes of the limiting cases are emphatically in corroboration with the outcomes from preceding research. It is found that the heat transfer rate has a positive sensitivity towards the haphazard motion of the nanoparticles and a negative sensitivity towards the thermomigration. The thermal field is enhanced by the Stefan blowing aspect. Moreover, the fluid velocity can be controlled by the applied magnetic field.     

Milling performance of stone-plastic composite with diamond cutters

In order to meet the requirements of cutting efficiency and economy in the processing of stone plastic composite, milling tests of the stone plastic composite were conducted using straight tooth diamond tools. Cutting forces and temperature were measured under different cutting parameters. Response surface methodology was used to analyze the variation of cutting forces and temperature and to determine the significant contribution of each variable and its two-level interaction. The correlation between actual and predicted results was found by building mathematical models of cutting forces and temperatures, which can be used to make accurate predictions. At last, the optimal cutting parameters for stone plastic composite straight-tooth milling with low cutting forces and cutting temperatures were found to be 10° front angle, 37.9 m/s cutting speed, 0.32 mm feed per tooth, and 0.5 mm milling depth. It is possible to improve processing efficiency and reduce production costs by using these parameters in industrial processing.     

ASTEMA: Design and preliminary performance assessment of a novel tele-microsurgery system

To overcome the challenges of reconstructive microsurgery, a teleoperated robot called ASTEMA was built to help surgeons performing microanastomoses. The surgeons’ needs are first analyzed then the design steps are summarized. This robot is composed of three orthogonal linear actuators and a spherical wrist with its remote center of motion at the instrument tip. Geometric model of the spherical wrist was calibrated through mathematical optimization in order to compensate for imperfections of machining and assembling. Two preliminary experiments were carried out to assess the ASTEMA performance. The first was performed with a simple circular position trajectory. The second was a complex angular trajectory. Results show a significant improvement of gesture precision with respect to manual trajectory execution. They also show that subjects instinctively compensate the errors from the non-ideal wrist, thanks to visual feedback from microscope.     

响应面法优化α-淀粉酶的酶反应体系

目的:采用单因素实验及响应面法优化α-淀粉酶的反应体系。方法:以淀粉为底物对象，以可溶性淀粉浓度、α-淀粉酶浓度、反应时间为考察因素，在单因素实验基础上，运用Box-behnken实验设计方法研究各因素及其交互作用对α-淀粉酶作用底物时的反应速度的影响。结果:建立α-淀粉酶酶反应体系的最佳反应条件为12.0 mg/mL可溶性淀粉、1.50 U/mL α-淀粉酶、10.0 min反应时间，在此条件下，α-淀粉酶表现出的反应速度达到（19.53±1.74） mmol/（L·min），接近模型中的预测数值18.75 mmol/（L·min）。结论:此优化α-淀粉酶酶反应体系的方法可行，能够使α-淀粉酶在反应过程中发挥的酶活最大化，为日后在此体系下进行糖苷酶抑制剂的研究奠定了基础，具有一定的指导意义。     

Development of mix design method based on statistical analysis of different factors for geopolymer concrete

The present study proposes the mix design method of Fly Ash (FA) based geopolymer concrete using Response Surface Methodology (RSM). In this method, different factors, including binder content, alkali/binder ratio, NS/NH ratio (sodium silicate/sodium hydroxide), NH molarity, and water/solids ratio were considered for the mix design of geopolymer concrete. The 2D contour plots were used to setup the mix design method to achieve the target compressive strength. The proposed mix design method of geopolymer concrete is divided into three categories based on curing regime, specifically one ambient curing (25 °C) and two heat curing (60 and 90 °C). The proposed mix design method of geopolymer concrete was validated through experimentation of M30, M50, and M70 concrete mixes at all curing regimes. The observed experimental compressive strength results validate the mix design method by more than 90% of their target strength. Furthermore, the current study concluded that the required compressive strength can be achieved by varying any factor in the mix design. In addition, the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.     

H2S Reactive Absorption from Off‐Gas in a Spray Column: Insights from Experiments and Modeling

H₂S removal from an off‐gas stream was performed in a spray column by H₂S reactive absorption into a NaOH solution. The individual and interactive effects of three independent operating variables on the percentage of absorbed H₂S were investigated: the initial pH of the scrubbing solution, the initial scrubbing solution temperature, and the volumetric liquid‐to‐gas ratio. The optimum operating variables were determined by response surface methodology (RSM) attaining a percentage of absorbed H₂S of 98.7 ± 0.2 %. Additionally, the process performance was modeled by an artificial neural network (ANN) to predict the percentage of absorbed H₂S. The results showed that the experimental data agreed better with the ANN model than with the RSM results.     

液晶材料中间体-4-(反式,反式-4-丙基双环己基)苯乙酮的合成

液晶材料目前的制备方法复杂,市场上成熟的原料合成路线基本没有。要制备性能优异的、使用广泛的液晶材料需要多步反应。以市场中常见的4-(反式,反式-4-丙基双环己基)苯为原料,经傅克酰基化反应得到目标产物。主要考察了4-(反式,反式-4-丙基双环己基)苯乙酮的合成条件,如酰基化反应溶剂、酰基化反应温度、酰基化反应时间及水解反应溶剂四个条件的影响,确定了合成反应的最佳条件。并采用红外光谱和核磁共振方法确证了目标产物。     

Efficient loading and entrapment of tamoxifen in human serum albumin based nanoparticulate delivery system by a modified desolvation technique

Herein, the poorly water-soluble drug, Tamoxifen (Tmx), was loaded in the amphipathic matrix of human serum albumin (HSA) nanoparticles by a modified desolvation method. In order to enhance the drug loading (DL) and drug entrapment efficiency (DEE) (<2% and 10%, respectively), ultrasonication of Tmx-HSA mixture was performed prior to desolvation process. Tmx loading and entrapment efficiency were optimized by employment of the response surface methodology (RSM)-central composite design (CCD) of experiments. Under the optimum conditions of 1.59 mg Tmx/ml concentration, 7.76 pH and 5 h incubation of HSA-Tmx, the DL of 6.7% and DEE of 74% are achievable. Particles with the average size of 195 nm, zeta potential of −21 mV and polydispersity index of 0.09 were produced under these conditions. A more sustained Tmx release behavior was observed from polyethylene glycol (PEG) conjugated nanoparticles in comparison to the non-PEGylated ones. The short-term stability investigation showed no alteration in physicochemical properties of nanoparticles at 4 and 37 °C, but small increase in nanoparticles size was observed after three months of storage at room temperature. This is the first report for efficient production of a Tmx delivery system based on HSA nanoparticles.     

互叶白千层花、果与叶挥发油成分的对比分析

以水蒸气蒸馏法提取互叶白千层花、果、叶三个不同部位的挥发油,采用气相色谱法、气相色谱-质谱联用法分别鉴定了花、果和叶中挥发油的化学成分,并比较互叶白千层不同部位挥发油的主要化学成分及含量差异。分析结果可为互叶白千层花、果研究提供试验依据。     

气相色谱-质谱法测定化妆品中13种硝基苯类化合物

建立了水剂、粉剂、膏霜类、唇膏唇彩类化妆品中13种硝基苯类化合物的气相色谱-质谱（GC-MS）测定方法。水剂和粉剂类化妆品采用溶剂提取,浓缩后测定;膏霜类和唇膏唇彩类化妆品采用溶剂提取,佛罗里硅土固相萃取柱净化后测定。样液经OV-225（30m×0.25mm×0.25μm）毛细管色谱柱分离,GC-MS的选择离子监测（SIM）模式检测,以保留时间和特征离子比值定性,内标法定量。结果显示,13种硝基苯类化合物在0.1-5.0mg/L浓度范围内线性关系良好,方法检出限（S/N=3）在0.02-0.85mg/kg之间,3个添加水平的平均回收率在81.2%-11.3%之间,相对标准偏差（RSD,n=6）为4.5%-12.1%。