The analytic models for size-dependent ordering and Curie temperatures of FePt nanoparticles have been proposed in terms of the size-dependent melting temperature. It is found that the order-disorder transition temperature TO and Curie temperature TC decrease with decreasing the particle size D, and the drop becomes dramatic once the size decreases to about 3 and 6 nm below for TO and TC, respectively. Moreover, the suppression in TC(D) is nearly twice as large as that in TO(D) when D is in the range of 5–20 nm. The accuracy of the developed model is verified by the recent experimental and computer simulation results.

No abstract

A novel nanogold‐enriched carbon nanohorn structure (nanoAu/CNH) was designed as a trace tag for highly efficient electrochemical detection of tumor marker using a disposable immunosensor. The nanoAu/CNH was synthesized by one‐pot in situ growth of nanogold on carboxylated single‐walled CNH. The labeling of signal antibody was performed via the inherent interaction between protein and nanogold. The disposable immunosensor was constructed by covalently cross‐linking capture antibody on chitosan modified screen‐printed carbon electrode. With a sandwich format, the nanoAu/CNH labeled antibody was conjugated on the immunosensor for electrochemical measurement of tumor marker by electrooxidizing the nanoAu at +1.3 V and then cathodic potential scan in 0.1 M HCl. Using α‐fetoprotein as model target, the proposed immunoassay showed acceptable precision and wide linear range from 0.1 pg mL−1 to 1 ng mL−1 with a detection limit of 0.07 pg mL−1. The new nanoAu/CNH label as well as the disposable immunosensor showed possessed potential application in point‐of‐care testing.

The analytic models for size-dependent Curie temperature T c and saturation magnetization at room temperature M s of Fe 3 O 4 nanoparticles have been proposed in terms of the size-dependent melting temperature. The T c (r) and M s (r) values decrease with a decreasing of the particle radius r. Agreement between model predictions and the corresponding experimental results can be found, which enable us to determine the size dependences of the thickness of nonmagnetic surface layer δ(r) and t(r) in respectively describing T c (r) and M s (r) functions. It is found that both δ(r) and t(r) increase with a decreasing of r and t(r) is always twice as large as δ(r). Moreover, the surface layer should be an intrinsic property of ferromagnetic crystals since the nonmagnetic surface layer exists in the whole size range rather than vanishes as r approaches infinite.

No abstract

The global panic caused by COVID-19 has continued to increase people’s demand for masks. However, due to inadequate management and disposal practice, these masks have, unfortunately, entered the environment and release a large amount of microplastics (MPs), posing a serious threat to the environment and human health. Understanding the occurrence of mask waste in various environments, release of mask-origin MPs, and related environmental risk is essential to mask-waste management in current and future epidemic prevention and control. This paper focuses on the global distribution of mask waste, the potential release of waste-origin MPs, and the impact on the environment. Specifically, the physical and chemical properties of polypropylene (the most common plastic material in a mask), which show a high adsorption capacity for heavy metals and organic pollutants and play a role as a support for microbial growth, were extensively reported. In addition, several important issues that need to be resolved are raised, which offers a direction for future research. This review focuses on the essentiality of handling masks to avoid potential environmental issues.

No abstract

To cope with the increasingly severe challenges of zinc oxide nanoparticles (ZnO-NPs) in the field of the aquatic environment, this paper uses poly-aluminum ferric chloride (PAFC) and cationic polyacrylamide (CPAM) as coagulants to enhance the removal of ZnO-NPs from water. In two environments (pure-water environment and kaolin environment) that simulate suspended solids, we studied the dosage, pH, precipitation time, and hydraulic power of ZnO-NPs at three different initial concentrations (1, 2, and 30 mg/L). The effects of various conditions on the performance of PAFC, CPAM, and PAFC/CPAM to remove ZnO-NPs were examined. Results showed that the overall removal rate of ZnO-NPs in the kaolin environment was slightly higher than that in the pure-water environment. In contrast the removal rate of ZnO-NPs in the PAFC/CPAM was significantly higher than that of PAFC or CPAM alone. The coagulation removal conditions of ZnO-NPs were optimized using a response-surface model. Under the best conditions, the removal rate of ZnO-NPs with an initial mass concentration of 30 mg/L in the PAFC/CPAM combination in pure-water and kaolin environments was 98.54% and 99.17%, respectively. Finally, by studying the changes in floc size during coagulation, enhanced coagulation was an efficient method of removing ZnO-NPs from water.