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A novel synchronous fluorimetric and absorptiometric technique based on dynamic liquid drops coupled with flow injection is described for the determination of chromium(VI) in aqueous solutions. Drops formed continuously at the end of a quartz capillary tube serve as reactor and optical cell. The reaction between chromium(VI) and 3,3',5,5'-tetramethylbenzidine dichloride (TMB-d) results in a significant decrease in fluorescence and transmitted light intensity, proportional to the logarithm of the concentration of chromium(VI). The transmitted light and fluorescence emission are detected in counter and perpendicular positions of the excitation light by a photomultipler tube and photodiode, respectively. In HCl-NaOAc buffer solution (pH 3.29), the sensor has a wide linear calibration range of 2 x 10(-8)-1 x 10(-4) mol l(-1) chromium(VI) with an absolute mass detection limit of 12.88 fmol.

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By tilting a plasma jet and rotating 360°, a large area can be scanned and sterilized in a short time. Compared with the previous array device, this pipe has the significant advantages of high sterilization uniformity and low gas consumption. Firstly, a rotatable plasma jet device, which can control the swing and rotation of a jet pipe, is designed, and a corresponding theoretical model established to guide the experiment. Secondly, with Staphylococcus aureus and Escherichia coli as the target bacteria, the device achieves a short sterilization time of 158 s—the minimum sterilization flow of Staphylococcus aureus and Escherichia coli is 0.8 slm and 0.6 slm, respectively. The device is compared with an array plasma sterilization device in terms of sterilization speed and gas consumption. The results show that the device is not only better than an array plasma sterilization device with respect to scanning uniformity, but also far less than the array plasma sterilization device in gas consumption of 5 slm. Therefore, the device has great potential in applications involving efficient, large-area sterilization.