DMSP-OLS (Defense Meteorological Satellite Program Operational Linescan System) night-time light data can accurately reflect the scope and intensity of human activities. However, the raw data cannot be used directly for temporal analyses due to the lack of inflight calibration. There are three problems that should be addressed in intercalibration. First, because of differences between sensors, the data are not identical even when obtained in the same year. Second, different acquisition times may lead to random or systematic fluctuations in the data obtained by satellites in different orbits. Third, a pixel saturation phenomenon also exists in the urban centres of the image. Therefore, an invariant region method was used in this article, and the relative radiometric calibration and saturation correction achieved the desired results. In the meantime, intercalibration models for each satellite year of DMSP-OLS night-time light data were produced. Finally, intercalibration accuracy was evaluated, and the intercalibration results were tested with the corresponding gross domestic product (GDP) data.

Analysis of nanoscale biological particles and organelles (BPOs) at the single-particle level is fundamental to the in-depth study of biosciences. Flow cytometry is a versatile technique that has been well-established for the analysis of eukaryotic cells, yet conventional flow cytometry can hardly meet the sensitivity requirement for nanoscale BPOs. Recent advances in high-sensitivity flow cytometry have made it possible to conduct precise, sensitive, and specific analyses of nanoscale BPOs, with exceptional benefits for bacteria, mitochondria, viruses, and extracellular vesicles (EVs). In this article, we discuss the significance, challenges, and efforts toward sensitivity enhancement, followed by the introduction of flow cytometric analysis of nanoscale BPOs. With the development of the nano-flow cytometer that can detect single viruses and EVs as small as 27 nm and 40 nm, respectively, more exciting applications in nanoscale BPO analysis can be envisioned.

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A laboratory-built high-sensitivity flow cytometer (HSFCM) was employed for the rapid and accurate detection of lactic acid bacteria (LAB) and their viability in probiotic products. LAB were stained with both the cell membrane-permeable SYTO 9 green-fluorescent nucleic acid stain and the red-fluorescent nucleic acid stain, propidium iodide, which penetrates only bacteria with compromised membranes. The side scatter and dual-color fluorescence signals of single bacteria were detected simultaneously by the HSFCM. Ultra-high temperature processing milk and skim milk spiked with Lactobacillus casei were used as the model systems for the optimization of sample pretreatment and staining. The viable LAB counts measured by the HSFCM were in good agreement with those of the plate count method, and the measured ratios between the live and dead LAB matched well with the theoretical ratios. The established method was successfully applied to the rapid quantification of live/dead LAB in yogurts and fermented milk beverages of different brands. Moreover, the concentration and viability status of LAB in ambient yogurt, a relatively new yet popular milk product in China, are also reported.

4-Dichlorophenol, as a highly toxic pollutant, widely exists in wastewater discharged from several industries. In this work, the use of immobilized horseradish peroxidase for 2,4-dichlorophenol removal from wastewater was investigated. Sodium hydroxide and hydrochloric acid treated PAN-based beads were modified with ethanediamine and chitosan, and then were activated with glutaraldehyde. The enzyme was immobilized onto the activated beads by covalent crosslinking. The surface of the immobilized bead was observed using EDX (SEM) and FTIR. The removal of 2,4-dichlorophenol has been studied using immobilized beads in beakers equipped with magnetic stirrer. Optimum pH of the free and immobilized enzyme were determined as 6.0 and 7.0 respectively, and the optimum ratio of hydrogen peroxide to 2,4-dichlorophenol is 1. The experimental results showed that about 90% of the 2,4-dichlorophenol was removed by the enzyme-immobilized capsules, and the immobilized enzyme had a lower efficiency in the removal of 2,4-dichlorophenol in comparison with the free enzyme.However, the immobilized beads have shown good operational stability.