Recent advances in wide bandgap semiconductor biological and gas sensors

There has been significant recent interest in the use of surface-functionalized thin film and nanowire wide bandgap semiconductors, principally GaN, InN, ZnO and SiC, for sensing of gases, heavy metals, UV photons and biological molecules. For the detection of gases such as hydrogen, the semiconductors are typically coated with a catalyst metal such as Pd or Pt to increase the detection sensitivity at room temperature. Functionalizing the surface with oxides, polymers and nitrides is also useful in enhancing the detection sensitivity for gases and ionic solutions. The wide energy bandgap of these materials make them ideal for solar-blind UV detection, which can be of use for detecting fluorescence from biotoxins. The use of enzymes or adsorbed antibody layers on the semiconductor surface leads to highly specific detection of a broad range of antigens of interest in the medical and homeland security fields. We give examples of recent work showing sensitive detection of glucose, lactic acid, prostate cancer and breast cancer markers and the integration of the sensors with wireless data transmission systems to achieve robust, portable sensors.     

Poly(BCB)/Au-nanoparticles hybrid film modified electrode: Preparation, characterization and its application as a non-enzymatic sensor

We report electrochemical preparation and characterization of poly-brilliant cresyl blue (Poly(BCB))/gold nanoparticles (Au-NPs) modified electrode. The Poly(BCB)/Au-NPs modified electrode has been used as an electrochemical sensor for the detection of hydrogen peroxide (H₂O₂) at lower potential (− 0.2 V). The Poly(BCB)/Au-NPs film was characterized by scanning electron microscopy, Uv-visible spectroscopy (Uv-vis) and cyclic voltammetry. We have observed that, Au-NPs attached glassy carbon electrode (Au-NPs/GCE) significantly enhanced the polymerization of BCB compared to bare GCE. The Poly(BCB) film was irreversibly attached onto the Au-NPs modified electrode, the resulting hybrid film modified electrode was electrochemically active in the pH range from 2 to 11. Attachment of Poly(BCB)/Au-NPs hybrid film on the electrode surface was confirmed by Uv-vis spectra. In addition, electrocatalytic properties of the Poly(BCB)/Au-NPs/GCE towards reduction of H₂O₂ have been investigated, and it was found that the sensitivity, reduction potential as well as the corresponding detection limit were improved as compared to the voltammetric response of the Poly(BCB)/GCE and Au-NPs/GCE. Based on this study, a non-enzymatic electrochemical sensor for the determination of H₂O₂ has been reported. Moreover, analysis of commercial H₂O₂ samples was performed using the proposed method and satisfactory results were obtained.     

Hot-Tearing Susceptibility of Ternary Mg-Al-Sr Alloy Castings

The susceptibility of Mg-Al-Sr alloys to hot tearing during permanent mold casting was investigated using constrained rod casting (CRC) in a steel mold. The alloys included Mg-xAl-1.5Sr and Mg-xAl-3Sr, where x = 4, 6, or 8 wt pct. The hot-tearing susceptibility (HTS) was determined based on the widths and locations of the cracks in the rods. With the Mg-xAl-1.5 Sr alloys, the HTS decreased significantly with increasing Al content. With the Mg-xAl-3Sr alloys, the trend was similar but not as significant. At the same Al content, the HTS was significantly lower at 3 wt pct Sr than at 1.5 wt pct Sr. To help understand the HTS of these alloys, the solidification path and phase fractions were calculated for each alloy. The HTS was found to increase with increasing fraction solid at the end of primary solidification.     

The grain refining mechanism of C-Mn steel by CSP

The grain refining mechanism of C-Mn steel sheet on compact strip production(CSP) line was investigated in this study.The grain was about 100μm after F1 pass and decreased all the way of the rolling process(F2-F6) to 15μm.Repeated phase transformation experiment was conducted to the steel for grain refinement.The phase transformation at 860℃and 920℃can refine the grain size to 7.5μm.     

Cholesterol Removal from Squid Liver Oil by Crosslinked β-Cyclodextrin

The present study was designed to optimize the different conditions for β-cyclodextrin (β-CD) crosslinked by adipic acid on cholesterol removal from squid liver oil. Different factors were concentrations of crosslinked β-CD, mixing temperature, ratio of squid liver oil to distilled water, mixing time and mixing speed. It was found that cholesterol removal from squid liver oil was significantly affected by concentrations of crosslinked β-CD, mixing temperature, ratio of squid liver oil to distilled water, mixing time and mixing speed. In a recycling study, cholesterol removal from the squid liver oil with recycled crosslinked β-CD in the first recycling trial was 81.05%, which was slightly lower than that with new crosslinked β-CD (87.06%). In up to three time trials, over 70% of cholesterol removal was observed. The present study indicated that the optimum conditions for cholesterol removal from squid liver oil using crosslinked β-CD were a 1:3 ratio of squid liver oil to distilled water, 25% (crosslinked β-CD/distilled water, w/v) crosslinked β-CD concentration, 20 min mixing time, 800 rpm mixing speed and 55 °C mixing temperature with about 87% cholesterol removal.     

A numerical prediction on the reduction of microorganisms with UV disinfection

This paper investigates the three dimensional flow field and organism concentration in a UV disinfection channel. The modified P-1 model is newly adopted to solve the UV intensity field. This modified P-1 model for radiative transfer can yield an accurate light intensity for even complicated geometries. The effect of UV light intensity on the disinfection of microorganisms has been considered in the species equation. Differently from existing literatures, this study has used the Euler method for the calculation of both the flow field and the concentration of organisms. The CFD modeling results are compared with existing experimental data [1] for a UV channel, which shows outstanding agreement. The effects of inlet velocity, absorption coefficients of lamps quartz and water on the disinfection efficiency are investigated. With a smaller inlet velocity and smaller absorption coefficients, higher disinfection efficiency has been obtained. The current CFD model has the capability to predict the performance of UV disinfection channels.     

突变管段三相流流型研究

油气水三相流动极其复杂, 三相之间的混合界面稳定性较弱, 因此在不同的输送条件下存在多种流型。使用 VOF模型, 以突变管段内油气水三相流为模拟对象, 在气体体积分数、 原油黏度及流动速度等参数不同的条件下, 对流体在管内的流动进行了模拟, 得到了相应的相分布云图。研究结果表明, 气体体积分数及流速对多相 流流型具有很大的影响, 而原油的黏度对流型的影响不是很明显。