Phosphatase-mimicking Zr@PDA nanozyme with excellent dispersion stability for the detection of fructose 1,6-diphosphate.

Zr4+-doped polydopamine (Zr@PDA) nanozyme with phosphatase-like activity was synthesized by a one-pot hydrothermal method for the first time. Compared with previous representative phosphatase-mimicking nanozymes (i.e., CeO2 NPs, ZrO2 NPs and UiO-66), Zr@PDA not only exhibited higher dispersion stability in water, but also higher catalytical efficiency. Kcat/Km of Zr@PDA is 35 and 12 times that of UiO-66 and ZrO2 NPs, respectively, which would endow the Zr@PDA-based analytical methods with high sensitivity. As a demonstration, a novel colorimetric method based on Zr@PDA nanozyme was developed for sensitive detection of the drug fructose 1,6-diphosphate. The linear range is 1-15 µM with a detection limit as low as 0.38 µM.

[Impact of laser energy on measurement of fly ash carbon content].

A laser induced breakdown spectroscopy-based apparatus for the analysis of element, employing a 532 nm laser and a multi-channel optical spectrometer with a non-intensified CCD array, has been built and tested. It was applied to analyze the carbon content of coal fly ash. Seven groups of pulse laser in the range of 35 to 98 mJ were used to ablate the fly ash samples. The electron densities and plasma temperatures with different laser energy were determined, and the influence of laser energy on the intensity of analysis carbon lines was also analyzed. The results show that carbon line intensity increases slowly with the increase in laser energy in the range of 35 to 46 mJ, and increases fast in the range of 46 to 78 mJ, then trends to saturation and has a little drop. At the same time, air breakdown has increased significantly, and has an obvious effect on sample plasma. Furthermore, the electron density and plasma temperature increase with the laser energy until 78 mJ and then begin to decrease. It indicates that a proper laser energy can enhance the plasma emission signal, and avoid the negative impact of air breakdown that prevent the pulse laser from reaching the surface of sample and ablating it. In this experiment situation, the measurement accuracy of the carbon line can be improved.

[Investigation on the delay time of coal experiment by laser-induced breakdown spectroscopy].

Laser-induced breakdown spectroscopy is a new technology of elementary analysis, and it will be used in coal analysis. The delay time of signal is an important parameter of spectral analysis. A LIBS system was set up and three kinds of coal (Jiangxipingxiang coal, Shanxixishan coal and Guizhoupingzhai coal) were chosen for this investigation. The spectra in the range of 240 to 250 nm and 275 to 290 nm of the each three coal samples are shown and they record several spectral lines of components such as C, Mg and Si according to the NIST database. The temporal evolution of SNR of spectral line was obtained, and the value of SNR increased with the time delay, then decayed. The temporal evolution of SNR was different as the coal, element and spectral line differs. Finally, optimum delay time of each spectral lines of elements in the coal samples was calculated according to the biggest value of signal-to-noise ratio, and the relation between the characteristic of coal, element, spectral line and the op timum delay time was analyzed.