Disinfection performance of chlorine dioxide gas at ultra-low concentrations and the decay rules under different environmental factors.

Gaseous chlorine dioxide (ClO2) is one of the most promising air disinfectants. In this study, an ultra-low concentration of ClO2 gas (< 1.2 mg/m3) was generated in an office at various levels of humidity and illuminance to investigate the decay law. The disinfection efficiency and metal corrosiveness of ultra-low concentrations of ClO2 gas were also studied using an experimental chamber. At 48% and 75% humidity, the decay rate constants of ClO2 gas were 0.0034 min-1 and 0.0036 min-1, respectively. The rate of decline of the ClO2 concentration increased as the humidity of the environment increased. The decay rate constant of ClO2 gas at an illuminance of 76 lux and 3429 lux was 0.0034 min-1 and 0.00427 min-1, respectively; hence, the decay rate increased with increased illumination. At a humidity of 72% and illuminance of 2112 lux, the decay rate constant reached 0.00880 min-1. The effects of humidity and illuminance on the attenuation of the ClO2 concentration were strongly synergistic. When the gas concentration was maintained below 0.9 mg/m3, the disinfection rate of ClO2 on bacteria (P. aeruginosa, V. mimicus and S. aureus) exceeded 99.9%; thus, ClO2 gas exhibited a high disinfection efficiency. In addition, there was no corrosion to various metals by ClO2 under the same conditions. Consequently, gaseous ClO2 at ultra-low concentrations has a high sterilization efficiency and is non-corrosive to metals. IMPLICATIONS: Humidity and illuminance can influence decay laws of extremely low concentration ClO2 gas. The gaseous ClO2 at ultra-low concentrations has a high sterilisation efficiency and is non-corrosive to metals.

Control synthesis, subtle surface modification of rare-earth-doped upconversion nanoparticles and their applications in cancer diagnosis and treatment.

Rare earth doped upconversion nanoparticles (UCNPs) are a new class of luminescent materials that can absorb long-wavelength near-infrared photons and emit short-wavelength UV-visible photons. UCNPs have little damage to biological tissues, have deep tissue penetration ability, have no background fluorescence noise interference, have high imaging sensitivity, and have no photobleaching effect. In the field of biomedicine, especially in the field of diagnosis and treatment of cancer, a wide range of research interests has arisen. In this paper, we briefly introduce the luminescent principle of rare-earth doped UCNPs, discuss several widely used control synthesis and modification methods, and focus on the research progress of UCNPs in detection of cancer cells, photodynamic therapy (PDT) and photothermal therapy (PTT) field. We also summarize the application of UCNPs as a diagnostic and therapeutic integrated nanoplatform in the diagnosis and treatment of cancer. At last, we explore the application challenge and prospect of UCNPs in oncology field.

Kinetics and mechanism of photocatalytic degradation of methyl orange in water by mesoporous Nd-TiO2-SBA-15 nanocatalyst.

High-efficiency nanophotocatalysts with large specific surface areas have a broad range of application prospects in the catalytic oxidation treatment of organic pollutants in wastewater. A chemical method was used to synthesize a TiO2 nanophotocatalyst with a mesoporous structure upon which a rare earth metal (Nd) was deposited, namely Nd-TiO2-SBA-15 (NTS). The prepared NTS was characterized using X-ray diffractometry, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectrometry. The photocatalytic mechanism was explored using scavenger experiments with photoinduced carriers combined with total organic carbon and UV-Vis measurements. At the same time, the kinetic properties of the NTS photocatalytic degradation of methyl orange (MO) were evaluated. The results showed that the deposition of TiO2 nanoparticles on the surface of the SBA-15 molecular sieve did not change the mesoporous structure, and Nd was uniformly distributed on the surface of the nanophotocatalyst. The photogenerated holes of the NTS played an important role in the photocatalysis process. In addition, the synthesized NTS had good adaptability in the range of pH 2-10. At pH 4, the reaction rate constant (k) of the MO photocatalytic degradation by NTS was 0.011825 mg·(L·min)-1, and the adsorption equilibrium constant (K) was 0.051359 L mg-1. In addition, the photocatalytic degradation rate of MO by NTS remained above 70%, even when the NTS was recycled four times. The NTS showed a good performance after recycling. This work provides a good foundation for the large-scale application of NTS.

Study on the controlled synthesis and photocatalytic performance of rare earth Nd deposited on mesoporous TiO2 photocatalysts.

Nanosized TiO2 photocatalysis technology is one of the most promising technologies for the treatment of wastewater containing azo dyes. In this work, TiO2 was deposited on a mesoporous SBA-15 molecular sieve by chemical deposition, and rare earth (RE) metal neodymium (Nd) was further deposited on the surface of the catalyst to obtain an Nd-TiO2-SBA-15 photocatalyst. The prepared photocatalyst was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and N2 adsorption-desorption. The activity of the Nd-TiO2-SBA-15 photocatalyst was evaluated by using methyl orange to represent the azo dye. The effects of different Nd deposition amounts and different solution pH values on the photocatalyst performance were principally studied. The results show that the synthesized photocatalyst formed an anatase crystal with a mesoporous structure. The specific surface area and pore size of the photocatalyst are 548.2 m2/g and 6.5 nm, respectively. As the amount of Nd deposition gradually increases, the activity of photocatalyst undergoes a process of first rising and then decreasing. In addition, the photocatalyst maintains high photocatalytic activity in the pH range of 2-10, exhibiting good acid-base adaptability. This work demonstrates that the Nd-TiO2-SBA-15 nanophotocatalyst has broad practical application prospects on a large scale.

Advances in the application of upconversion nanoparticles for detecting and treating cancers.

The detection and treatment of cancer cells at an early stage are crucial for prolonging the survival time and improving the quality of life of patients. Upconversion nanoparticles (UCNPs) have unique physical and chemical advantages and likely provide a platform for detecting and treating cancer cells at an early stage. In this paper, the principle of UCNPs as chemical sensors based on fluorescence resonance energy transfer (FRET) has been briefly introduced. Research progress in such chemical sensors for detecting and analyzing bioactive substances and heavy metal ions at the subcellular level has been summarized. The principle of UCNP-based nanoprobe-targeting of cancer cells has been described. The research progress in using nanocomposites for cancer cell detection, namely cancer cell targeted imaging and tissue staining, has been discussed. In the field of cancer treatment, the principles and research progress of UCNPs in photodynamic therapy and photothermal therapy of cancer cells are systematically discussed. Finally, the prospects for UCNPs and remaining challenges to UCNP application in the field of cancer diagnosis and treatment are briefly described. This review provides powerful theoretical guidance and useful practical information for the research and application of UCNPs in the field of cancer.