Synthesis of Photoluminescent Core–Shell-Structured Carbon dots@silica Nanocomposite Fingermark Powders for Latent Fingermarks Visualization

To obtain solid-state photoluminescent core–shell-structured carbon dots@silica (C-dots@SiO2) nanocomposites, the C-dots were synthesized by microwave irradiation and were dispersed in SiO2through sol–gel technique. Then, the excellent fluorescent property with excitation-independent feature and the core–shell structure of C-dots@SiO2nanocomposites were successfully characterized through the fluorescence spectroscopy, ultraviolet–visible absorption spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The as-prepared C-dots@SiO2powder was mixed with reduced iron powder and then applied to latent fingermark detection. The latent fingermarks on several surfaces labeled with C-dots@SiO2fingermark powders emitted blue fluorescence under 365[Formula: see text]nm UV light and exhibited high contrast between the background and the ridges. Additionally, the C-dots@SiO2fingermark powder as a fluorescent label for enhancing latent fingermarks demonstrated greater advantages as compared to the conventional fluorescent fingermark powder especially for latent fingermark deposited on porous surfaces.

Effects of Silk-worm Excrement Biochar Combined with Different Iron-Based Materials on the Speciation of Cadmium and Lead in Soil

A 56d incubation experiment was conducted to explore the effects of the silk-worm excrement biochar (500 °C, BC) combined with different iron-based materials (FeCl3, FeSO4, and reduced iron powder) on the speciation of cadmium (Cd) and lead (Pb) in a contaminated soil. Application rate of BC and iron-based materials is 1% (W/W) and 0.2% (W/W) of the soil, respectively. At the same time, the soil physicochemical properties, such as pH, cation exchange capacity (CEC), and the structure of soil, were determined in order to explore the influence mechanism of amendments to forms of Cd and Pb in soil. The results show that the stabilization effects on Cd is (BC + FeSO4) > (BC + FeCl3) > (BC + Fe) > (BC) and Pb is (BC + Fe) > (BC + FeSO4) > (BC + FeCl3) > (BC) at the end of incubation, compared with the effect of the control group. The treatment of (BC + FeSO4) is the most effective in terms of the stabilization of Cd and Pb, which makes the percentages of organic-bound and residual Cd and Pb increase by 40.90% and 23.51% respectively. In addition, with different ways of treatment, the pH value and CEC of soil see a remarkable increase by 1.65–2.01 units and 2.01–2.58 cmol·kg−1 respectively. X-ray diffraction (XRD) patterns show that the soil imprisons Cd and Pb in different mineral phases. As such the treatment of (BC + FeSO4) can significantly improve soil environment, increase soil pH value & CEC and exert a relatively good stabilization effect on both Cd and Pb.