The dissolution of waste glasses by groundwater presents a key mechanism for immobilised or encapsulated contaminant release over geological timescales. Accurately predicting glass dissolution rates remains a challenge to waste management, where a complete understanding of glass dissolution mechanisms is required to model the release and fate of contaminants. Here, this work investigated the suitability of boron isotope fingerprinting techniques for studying glass dissolution mechanisms, focussing on solid-state diffusion processes during boron release. Two glasses (magnesium-free 10B-ISG and magnesium-bearing 6Li-Mg-EM) were altered in deionised water at 90 °C for 0.25 to 112 d. Solution renewal experiments were used to further study altered surface layer properties. At ≤ 28 d, solution boron isotope (11B/10B) ratios for 6Li-Mg-EM were consistent with the apparent congruent release of boron alongside sorption/coprecipitation processes with secondary minerals, but decreasing solution 11B/10B ratios at > 28 d suggested diffusion occurred across the altered layer at a dissolution front spatially separated from that of lithium. Contrastingly, solution 11B/10B ratios for 10B-ISG at ≤ 28 d were fitted well using a diffusion model assuming a time-dependent apparent diffusion coefficient, but those at > 28 d were better explained by either sorption/coprecipitation processes with secondary minerals or a spatially-dependent apparent diffusion coefficient. The altered layer formed for 10B-ISG after 28 d was not protective following solution renewal, and renewed solution 11B/10B ratios were instead consistent with an apparent congruent release mechanism. This study presents boron isotopes as in situ tracers for studying glass dissolution mechanisms, assisting in predicting contaminant releases during waste glass-aqueous solution interactions.
Sunlight-driven photosynthesis by covalent organic frameworks (COFs) from water and air without using sacrificial reagents is a promising H2O2 fabrication approach, but is still restricted by the insufficient charge separation and sluggish 2e- water oxidation process. Herein, we provide a facile strategy to simultaneously improve charge separation and water oxidation in COFs via confining the charge transfer pathways from two diversion ones to a confluence one through regulating the site of nitrogen in bipyridine. Combining in-situ characterization with computational calculations, we reveal that compared to COF-BD1 containing two diversion charge transfer pathways, the charge transfer pathway in COF-BD2 is confined to a confluence one due to the electron-deficiency effect of nitrogen, which greatly accelerates the intermolecular and out-of-plane charge transfer. Via effectively reducing the energy barrier of rate-determining water oxidation reaction, the subsequent water oxidation process to produce key *OH intermediate in COF-BD2 is also greatly facilitated, boosting the yield of H2O2 (5211 μmol g-1 h-1) from water, oxygen, and light without sacrificial agents or additional energy consumption. We further demonstrate that H2O2 can be efficiently produced by COF-BD2 in broad pH range, in real water, and in enlarged reactor with using natural sunlight for water decontamination.
Using data from the China Family Panel Studies (CFPS), this study examines the impact of art education on Chinese citizens’ trust in Americans. We find that participation in art tutorials correlates with increased trust towards Americans, with the level of trust rising with time spent in art education. Further analysis indicates that this effect is more pronounced in males and individuals whose parents already hold positive views of Americans. These results highlight the role of art education in fostering intercultural understanding. The study contributes to the literature on trust formation and the effects of art education, underscoring the significance of cultural engagement in promoting cross-cultural trust in global relations.
Addressing poverty is paramount, aligning with the first Sustainable Development Goal focused on eradicating poverty in all its forms. While the effects of high-speed rail (HSR) on absolute poverty have been documented, its impact on relative poverty remains understudied. This paper examines the influence of HSR on household relative poverty in China through a quasi-experimental design. The main results are as follows: (1) The opening of HSR significantly reduced the household relative poverty by approximately 1.8 %. (2) This alleviation effect primarily transpires through the expansion of economic activities and employment opportunities. (3) Notably, the impact of HSR is more pronounced in lower-ranked, smaller cities and in the western regions of China. Moreover, households with migrant workers or those engaged in non-agricultural sectors derive greater benefits from HSR developments. Our results suggest that HSR opening could have contributed to China’s relative poverty alleviation. Policymakers can consider the role of transportation infrastructure in mitigating household relative poverty, especially for low rank cities, small cities and periphery regions in other developing countries.
The advantage of Chinese-as-a-heritage-language (CHL) learners in acquiring Chinese has been widely recognized. However, it is still unclear whether the effect of CHL background on Chinese receptive vocabulary breadth varies across different countries. To address this gap, the present study recruited 232 Chinese language learners (half were CHL learners) from Indonesia and Thailand and administered a Chinese vocabulary proficiency test. The results of regression analysis revealed an interaction effect between country and CHL background on vocabulary breadth, with the contribution of CHL background to vocabulary breadth more robust in the Indonesian group than that in the Thai group. Interviews were then conducted to explore the factors that might influence such an interaction effect. Analysis of the interview data found that the influencing factors could be categorized into four themes, including individual differences, family background, Chinese language education and socio-cultural factors. The overall results were discussed within the framework of ecological system theory, and pedagogical implications for CHL learners were proposed.
Worldwide, humanities and social sciences (HSS) scholars produce and disseminate knowledge in an unequal global knowledge space, which can be caused by various structural, epistemological, and individual-level factors. Although global epistemic injustice receives much attention, the factors contributing to it, including the extraverted mindsets and practices of non-Euro-American scholars, remain less discussed. This article draws on semibiographical interviews with 30 high-achieving ethnic Chinese HSS scholars in mainland China, in Hong Kong, and overseas. It explores how these scholars display intellectual extraversion and why and how they are reflexive about and confronting it. The findings reveal three manifestations of intellectual extraversion, four sources of reflexivity regarding such extraversion, and three ways to confront it. The research uncovers the continuous reflexivity and efforts of ethnic Chinese HSS scholars in dealing with lingering epistemic discontinuities and exclusions and sheds light on new possible approaches to challenging global epistemic injustice in HSS research.
As a judicious correspondence to the classical maxcut, the anti-Cheeger cut has more balanced structure, but few numerical results on it have been reported so far. In this paper, we propose a continuous iterative algorithm (CIA) for the anti-Cheeger cut problem through fully using an equivalent continuous formulation. It does not need rounding at all and has advantages that all subproblems have explicit analytic solutions, the objective function values are monotonically updated and the iteration points converge to a local optimum in finite steps via an appropriate subgradient selection. It can also be easily combined with the maxcut iterations for breaking out of local optima and improving the solution quality thanks to the similarity between the anti-Cheeger cut problem and the maxcut problem. The performance of CIAs is fully demonstrated through numerical experiments on G-set from two aspects: one is on the solution quality where we find that the approximate solutions obtained by CIAs are of comparable quality to those by the multiple search operator heuristic method; the other is on the computational cost where we show that CIAs always run faster than the often-used continuous iterative algorithm based on the rank-two relaxation.
Mineral precipitation is ubiquitous in natural and engineered environments, such as carbon mineralization, contaminant remediation, and oil recovery in unconventional reservoirs. The precipitation process continuously alters the medium permeability, thereby influencing fluid transport and subsequent reaction kinetics. The diversity of preferential precipitation zones controls flow and transport efficiency as well as the capacity of mineral sequestration and immobilization. Taking barite precipitation as an example, previous studies have examined this process in porous and/or fractured media, but pore-scale mechanisms under varying flowing and geochemical conditions remain unexplored. In this study, we conducted real-rock microfluidic experiments to investigate the precipitation dynamics within a fractured porous system. Direct observations of the evolution of the porous structure and flow channel and quantifications of barite precipitation dynamics using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), revealed two distinct precipitation regimes: precipitation on the fracture surface (regime I) and precipitation in the alteration zone (regime II). Through theoretical analysis of the rate of advection and nucleation, we defined a dimensionless number Da above which regime I occurs and regime II prevails otherwise. At the large Da number, when the precipitation rate is large compared with the flow rate, precipitation on the fracture surface is favored. As the precipitation regimes are expected to impact differently the permeability of the fractured porous media, the mass transfer across matrix and fractures, and the spatial distributions of coprecipitated contaminants, our work sheds light on accurately modeling reactive transport in fractured porous media across diverse applications.
Impurity-containing iron hydroxides, abundant in many natural and engineered soil and aqueous environments, control the fate and transport of multiple aqueous contaminants. Fe(III) hydroxide was reported to simultaneously detoxicate As(III) and Cr(VI). However, the mechanisms and reaction intermediates are not clear, and the effects of impurities in ferrihydrite were far from being well understood. Here, Cr(III)-incorporated Fe(III) hydroxides were precipitated from acidic solutions (pH ∼ 3.0) with varied Fe(III)/Cr(III) molar ratios (10 : 0 to 8 : 2) for simultaneous removal of As(III) and Cr(VI). Multiple characterization techniques were combined to investigate the effects of Cr-incorporation on the size, band gap, adsorption, and catalytic efficiency of Fe hydroxides. With the amounts of Cr-incorporation increasing, the particle size of Fe hydroxides rapidly decreased (from 16.7 to 6.0 nm), and the removal of total As/Cr increased, as the Cr-incorporated Fe hydroxides with smaller size had larger surface area, promoting As/Cr removal by adsorption. Based on As/Cr speciation analysis of both aqueous and solid phases, the molar ratios of the oxidized As(III) (88%) to reduced Cr(VI) (∼56%) were calculated to be ∼1.5, indicating that the coupled redox conversion was the dominant removal mechanism over As(III)/Cr(VI) adsorption and As(III) oxidation. Intermediate characterization and molecular simulation found that Cr-incorporation promoted the early formation of H2O2 and Cr(V) intermediates, and enhanced the adsorption of reaction intermediates on Cr-incorporated Fe hydroxides, thus promoting their catalytic efficiency for coupled As(III)/Cr(VI) redox reactions.
The Transformer model, particularly its cross-attention module, is widely used for feature fusion in target sound extraction which extracts the signal of interest based on given clues. Despite its effectiveness, this approach suffers from low computational efficiency. Recent advancements in state space models, notably the latest work Mamba, have shown comparable performance to Transformer-based methods while significantly reducing computational complexity in various tasks. However, Mamba’s applicability in target sound extraction is limited due to its inability to capture dependencies between different sequences as the cross-attention does. In this paper, we propose CrossMamba for target sound extraction, which leverages the hidden attention mechanism of Mamba to compute dependencies between the given clues and the audio mixture. The calculation of Mamba can be divided to the query, key and value. We utilize the clue to generate the query and the audio mixture to derive the key and value, adhering to the principle of the cross-attention mechanism in Transformers. Experimental results from two representative target sound extraction methods validate the efficacy of the proposed CrossMamba
