De-Jun Chen

The PROP enables novel GenX degradation chemistry and enhances its fragmentation to lower and non-fluorinated products.

Microplastic (MP) pollution poses an emerging environmental concern, yet current methods for isolation and quantification are often time-consuming, costly, and poorly adapted to real-world variability. In this study, a workflow for the preparation, filtration, and quantification of MP standards, emphasizing environmental relevance and methodological efficiency, was developed and evaluated. To address the scarcity of irregularly shaped MP standards, low-cost, environmentally representative standards were lab-prepared by grinding and sieving plastic sheets. These MPs were successfully categorized according to sizes up to ~250 μm and dyed for enhanced visibility. The filtration efficiency for two systems, a long-circuit pump (LC-pump) and a short-circuit vacuum (SC-vacuum), was compared. The SC-vacuum method demonstrated a more than 11-fold increase in filtration speed and higher MP recovery rates for both polystyrene and polypropylene standards. Ethanol-based solvents significantly improved MP dispersion and recovery for irregular shapes of the MPs, including polystyrene and polypropylene. Finally, a user-guided machine learning tool (Ilastik) was implemented for automated MP quantification. Ilastik showed a strong correlation with manual counting (r = 0.824) and reduced variability, offering a reproducible and time-efficient alternative. By cutting down cost, time, and technical complexity relative to existing MP analysis techniques, this workflow provides a more accessible path toward consistent and scalable environmental MP assessments.

Whether a tire crumb rubber (TCR) playground would expose children to potentially harmful chemicals such as heavy metals is an open question. The released metals available for pickup on the surface of TCR tiles was studied by accelerated 2-year aging of the TCRs in the NIST-SPHERE (National Institute of Standards and Technology Simulated Photodegradation via High Energy Radiant Exposure). The dermal contact was mimicked by a method of composite surface wiping from US Environmental Protection Agency throughout the weathering process. The surface release of ten most concerned harmful metals (Be, Cr, Cu, As, Se, Cd, Sb, Ba, Tl, Pb) was monitored through the course of aging. The cumulative release of Cu, As, Tl, and Sb reached potentially harmful levels at various times within 3 years, although only Cr was found at a harmful level on the surface of the tiles. Taking the cleansing effect of precipitation or periodic cleansing with rain into account, TCR playgrounds may still be safe for use.

Radar and AIS (Automatic Identification System, AIS) are two types of safety navigational aids that ships must be equipped with. Due to the complementarity and redundancy of the data collected by the two, the fusion method of AIS and radar information can be used to improve the accuracy of the track. In view of the fact that the distributed Kalman filtering method that has emerged in recent years fails to consider the impact of ship speed changes on the fusion accuracy, this paper puts forward a ship track fusion model based on distributed extended Kalman filter. The correctness and effectiveness of the proposed method are illustrated through the analysis of evaluation indicators and experiments.

The current production from the alkaline methanol electrooxidation reaction does not reach a steady-state on a smooth platinum catalyst under potentiostatic conditions. We investigated two possible explanations for this phenomenon: changes on the catalyst surface and changes in the solution near the electrode. In situ Fourier transform infrared spectroscopy experiments were conducted to evaluate the catalyst surface and a simulation model was set up to describe changes of concentrations inside the solution. Linear- and bridge-bonded carbon monoxide are the only organic compounds which can be detected by in situ spectroscopy at fixed potentials but their amount do not increase over time. The simulation shows that the consumption of hydroxide ions and production of carbonaceous species during alkaline oxidation causes a local pH-shift near the catalyst surface. Assuming a one-electron transfer as the limiting step, this pH-shift was found accountable for the observed current loss at a potential of 0.7 V.

A combined in situ electrochemical attenuated total reflection-surface enhanced IR absorption spectroscopy, microkinetic simulation, and density functional theory calculation study shows that not only can the adsorbed sulfide disproportionally affect the surface binding of OOH^* (E_OOH^*) vs OH^* (E_OH^*), i.e., breaking the original scaling relationship of pure metals (Ir, Pd, Pt, Au), to enhance oxygen reduction reaction (ORR) activity but can also be used as a reaction pathway alternating species to help deepen our mechanistic understanding of ORR.