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Abstract Model uncertainty quantification is essential for enhancing the validity of simulations of nonlinear dynamic systems. However, its effectiveness may be significantly affected when experimental or monitoring data are sparse. To tackle this challenge, we drew inspiration from population-based structural health monitoring, which enhances damage diagnostics by facilitating information sharing across a population of similar (in some context) but different systems. In this article, we propose a novel population-based model bias correction (PMBC) framework that employs federated learning (FL) to enable distributed, privacy-preserving bias correction for populations of nonlinear dynamic systems sharing a common design framework but with different system models in reality due to uncertainty in unit-specific model parameters and model-structural errors. The model uncertainty in a population of nonlinear dynamic systems is first analyzed using the Kennedy and O’Hagan (KOH) framework. The proposed method then constructs a shared nonlinear autoregressive with eXogenous inputs (NARX) surrogate model for the simulation model and develops system-specific bias datasets that capture both model-structural errors and parameter uncertainty. Federated training is employed to collaboratively learn a global bias correction model, which is subsequently fine-tuned into system-specific bias models using local datasets to correct biases in a population of nonlinear dynamic systems. The effectiveness of the proposed framework is demonstrated through two case studies, namely a population of Duffing oscillators and a fleet of three ship-heading models. In both cases, the PMBC approach is compared with a conventional single-system bias correction method, a centralized approach with and without fine-tuning, and the original simulation model. The results indicate that the proposed PMBC method consistently produces the lowest prediction errors, maintaining robust generalization under untested new input excitations. 

We present and analyze the static spectroscopy and radiative dynamics of very high quality, well characterized silver indium gallium sulfide quantum dots. We find that the static spectroscopy and radiative dynamics are very different from those in II–VI and III–V quantum dots. The absorption spectrum is broad and featureless, but sharp, high quantum yield (90%) band edge photoluminescence is observed. Despite the spectrally sharp photoluminescence, the photoluminescence decays are long and nonexponential, having components ranging from 40 to 150 ns. The spectroscopy and radiative kinetics are understood in the context of the radial composition profile of each element, as determined by energy dispersive x-ray spectroscopy line profiles. The radially dependent compositions show that the core is largely Ag2S with the fraction of gallium increasing with radial distance. We suggest that random spatial fluctuations in the local silver concentration localize holes at the most silver-rich regions of the particle. The lowest energy transition is nominally parity forbidden and the parity selection rule is relaxed in the random alloy crystal environment. The sites at which holes localize have varying degrees of local crystal asymmetry and varying magnitudes of internal electric fields. Both types of perturbations can break the local symmetry and thereby relax the parity selection rule, giving rise to inhomogeneity in the radiative rates. We also consider the possibility that the nonexponential photoluminescence decay kinetics can be explained by a delayed emission model but consider this to be less likely than the inhomogeneous radiative rate model. 

Abstract The capture, utilization, and storage of CO₂are the primary options to minimize the adverse effects of global warming and related climate change resulting from increased anthropogenic CO₂emissions. In recent years, amino acids and amino acid‐based ionic liquids (AAILs) are proposed as promising alternatives to the traditional aqueous amine solvent‐based CO₂capture technology due to the presence of the ─NH₂group and a CO₂adsorption mechanism like amines, but with many additional advantages. Besides CO₂absorption in solvent form, amino acids/AAILs‐functionalized porous sorbents demonstrate potential in CO₂adsorption technology, a promising alternative to solvent‐based CO₂absorption technology, as they can avoid the huge energy penalty associated with aqueous solution regeneration by heating. Additionally, amino acids/AAILs, with their CO₂capture abilities, have demonstrated their potential in other promising CO₂sequestration technologies: direct air capture, CO₂mineralization using alkaline industrial waste, and conversion of CO₂into value‐added products. This article reviews the mechanism, comparative performance, and prospects of amino acid‐based state‐of‐the‐art technologies for CO₂absorption and adsorption, direct air capture, bio‐mineralization, and conversion of CO₂into value‐added products, which is helpful for the further development of amino acid‐based CO₂sequestration technologies. 

The complex distribution of functional groups in carbohydrates, coupled with their strong solvation in water, makes them challenging targets for synthetic receptors. Despite extensive research into various molecular frameworks, most synthetic carbohydrate receptors have exhibited low affinities, and their interactions with sugars in aqueous environments remain poorly understood. In this work, we present a simple pyridinium-based hydrogen-bonding receptor derived from a subtle structural modification of a well-known tetralactam macrocycle. This small structural change resulted in a dramatic enhancement of glucose binding affinity, increasing from 56 M−1 to 3001 M−1. Remarkably, the performance of our synthetic lectin surpasses that of the natural lectin, concanavalin A, by over fivefold. X-ray crystallography of the macrocycle–glucose complex reveals a distinctive hydrogen bonding pattern, which allows for a larger surface overlap between the receptor and glucose, contributing to the enhanced affinity. Furthermore, this receptor possesses allosteric binding sites, which involve chloride binding and trigger receptor aggregation. This unique allosteric process reveals the critical role of structural flexibility in this hydrogen-bonding receptor for the effective recognition of sugars. We also demonstrate the potential of this synthetic lectin as a highly sensitive glucose sensor in aqueous solutions.