Global Challenges最新文献

The interaction between multi-component rare earth element (REE) aqueous solutions and carbonate grains (dolomite, aragonite, and calcite) are studied at hydrothermal conditions (21–210 °C). The effect of ionic radii of five REEs (La, Ce, Pr, Nd, Dy) on solid formation are analyzed using two solution types: equal REE concentrations and concentrations normalized to Post Archean Australian Shale Standard (PAAS). The interaction replaces the host Ca–Mg carbonate grains with a series of REE minerals (lanthanite → kozoite → bastnäsite → cerianite). At 165 °C, equal concentration solutions promote kozoite crystallization, maintaining similar REE ratios in solids and solution. PAAS solutions result in zoned REE-bearing crystals with heterogeneous elemental distributions and discreet REE phases (e.g., cerianite). Chemical signatures indicate metastable REE-bearing phases transforming into more stable polymorphs, along with symplectite textures formed by adjacent phase reactions. Overall, experiments highlight the dependence of polymorph selection, crystallization pathway, mineral formation kinetics, and chemical texture on REE concentrations, ionic radii, temperature, time, and host grain solubility.

Global terrestrial water supplies are rapidly depleting due to the consequences of climate change. Water scarcity results in an inevitable compromise of safe hygiene and sanitation practices, leading to the transmission of water-borne infectious diseases, and the preventable deaths of over 800.000 people each year. Moreover, almost 500 million people lack access to toilets and sanitation systems. Ecosystems are estimated to be contaminated by 6.2 million tons of nitrogenous products from human wastewater management practices. It is therefore imperative to transform toilet and sewage systems to promote equitable access to water and sanitation, improve public health, conserve water, and protect ecosystems. Here, the integration of emerging technologies in toilet and sewage networks to repurpose toilet and wastewater systems is reviewed. Potential applications of these systems to develop sustainable solutions to environmental challenges, promote public health, and advance person-centered healthcare are discussed.

Photocatalytic hydrogen evolution is an environmentally friendly means of energy generation. Although g-C₃N₄ possesses fascinating features, its inherent shortcomings limit its photocatalytic applications. Therefore, modifying the intrinsic properties of g-C₃N₄ and introducing cocatalysts are essential to ameliorate the photocatalytic efficiency. To achieve this, metal-like Ti₃C₂T_x is integrated with crystalline g-C₃N₄ via a combined salt-assisted and freeze-drying approach to form crystalline g-C₃N₄/Ti₃C₂T_x (CCN/TCT) hybrids with different Ti₃C₂T_x loading amounts (0, 0.2, 0.3, 0.4, 0.5, 1, 5, 10 wt.%). Benefiting from the crystallization of CN, as evidenced by the XRD graph, and the marvelous conductivity of Ti₃C₂T_x supported by EIS plots, CCN/TCT/Pt loaded with 0.5 wt.% Ti₃C₂T_x displays an elevated H2 (2) should be subscripted evolution rate of 2651.93 µmol g⁻¹ h⁻¹ and a high apparent quantum efficiency of 7.26% (420 nm), outperforming CN/Pt, CCN/Pt, and other CCN/TCT/Pt hybrids. The enhanced performance is attributed to the synergistic effect of the highly crystalline structure of CCN that enables fleet charge transport and the efficient dual cocatalysts, Ti₃C₂T_x and Pt, that foster charge separation and provide plentiful active sites. This work demonstrates the potential of CCN/TCT as a promising material for hydrogen production, suggesting a significant advancement in the design of CCN heterostructures for effective photocatalytic systems.

A recent comment by Boivin et al. urges academia and governments to address sexism and fight bias at higher education and research institutions as losing female academics is costing science and society too much. Herein, I discuss further underlying reasons of sexism in academia and the importance of a deep dive into the causes of inequity at individual faculty and school levels to develop bespoke and enforceable gender equity plans, the importance of not using basic statistic as the only tool to measure equity/inequity as well as how key performance indicators could be better used to advance gender equity and end sexism in academia.

This review aims to provide an overview of sustainable approaches that can be incorporated into well-known procedures for the development of materials, pre- and post-treatments, modifications, and applications of 3D-printed objects, especially for fused filament fabrication (FFF). Different examples of conductive and non-conductive bespoke filaments using renewable biopolymers, bioplasticizers, and recycled materials are presented and discussed. The main final characteristics of the polymeric materials achieved according to the feedstock, preparation, extrusion, and treatments are also covered. In addition to recycling and remanufacturing, this review also explores other alternative approaches that can be adopted to enhance the sustainability of methods, aiming to produce efficient and environmentally friendly 3D printed products. Adjusting printing parameters and miniaturizing systems are also highlighted in this regard. All these recommended strategies are employed to minimize environmental damage, while also enabling the production of high-quality, economical materials and 3D printed systems. These efforts align with the principles of Green Chemistry, Sustainable Development Goals (SDGs), 3Rs (Reduce, Reuse, Recycle), and Circular Economy concepts.

This study presents the parameter extraction of single, double, and triple-diode photovoltaic (PV) models using the weighted leader search algorithm (WLS). The primary objective is to develop models that accurately reflect the characteristics of PV devices so that technical and economic benefits are maximized under all constraints. For this purpose, 24 models, 6 for two different PV cells, and 18 for six PV modules, whose experimental data are publicly available, are developed successfully. The second objective of this research is the selection of the most suitable algorithm for this problem. It is a significant challenge since the evaluation process requires using advanced statistical tools and techniques to determine the reliable selection. Therefore, seven brand-new algorithms, including WLS, the spider wasp optimizer, the shrimp and goby association search, the reversible elementary cellular automata, the fennec fox optimization, the Kepler optimization, and the rime optimization algorithms, are tested. The WLS has yielded the smallest minimum, average, RMSE, and standard deviation among those. Its superiority is also verified by Friedman and Wilcoxon signed-rank test based on 144 pairwise comparisons. In conclusion, it is demonstrated that the WLS is a superior algorithm in PV parameter extraction for developing accurate models.

The use of light as a catalytic prompt for the synthesis of industrial relevant compounds is widely explored in the past years, with a special consideration over the hydrogen evolution reaction (HER). However, semiconductors for heterogeneous photocatalysis suffer from fast charge recombination and, consequently, low solar-to-hydrogen efficiency. These drawbacks can be mitigated by coupling photocatalysts with an external circuit that can physically separate the photogenerated charge carriers (electrons and holes). For this reason, photoelectrochemical (PEC) production of hydrogen is under the spotlight as promising green and sustainable technique and widely investigated in numerous publications. However, considering that a significant fraction of the hydrogen produced is used for reduction processes, the development of PEC devices for direct in situ hydrogenation can address the challenges associated with hydrogen storage and distribution. This Perspective aims at highlighting the fundamental aspects of HER from PEC systems, and how these can be harnessed toward the implementation of suitable settings for the hydrogenation of organic compounds of industrial value.

In this study, photocatalysts with high photocatalytic activity performance are synthesized by synthesizing graphene aerogel-supported, cadmium-doped TiO₂ composites by hydrothermal method for the effective degradation of organic dyes in wastewater. Here, GA–TiO₂–Cd is investigated as a photocatalyst for the degradation of toxic dyes named Orange G, Acid Blue 161, and Brilliant Green in the UV part of the light spectrum. As a result of the experiments, it is observed that the effective decomposition of organic dyes is due to graphene aerogel (GA) and cadmium-doped TiO₂ nanoparticles. The results show that for 20 ppm solutions of Orange G, Acid Blue 161, and Brilliant Green, dyes are removed at approximately 81.075%, 84.15%, and 95.18% in 120 min. The morphology and elemental analysis of the synthesized composites are determined using SEM-EDS, crystal structure analysis by XRD, chemical bond analysis by FTIR, optical properties by UV-Vis-NIR spectrophotometry, and thermal resistance by TGA analysis.

Water scarcity presents a formidable challenge to agriculture, particularly in arid, semiarid, and rainfed settings. In agricultural contexts, hydrogels serve as granular agents for water retention, undergoing considerable expansion upon water exposure. They assume versatile roles encompassing soil-water retention, the dispensation of nutrients and pesticides, seed encapsulation, erosion mitigation, and even food supplementation. This study's objective involves the examination of biochar-infused hydrogels, fashioned by incorporating vine pruning waste-derived biochars, and the assessment of swelling behaviors in various aqueous environments encompassing deionized, tap, and saline water at concentrations of 0.5–1%. Characterizations of the vine-biochars-VB and biochar-incorporated hydrogels-VBHG are executed, with particular attention to their swelling properties across diverse media. As an initial step toward appraising their agricultural relevance, these hydrogels are introduced to a germination medium featuring wheat seeds to discern potential influences on germination dynamics. The maximum swelling capacity of VBHG is recorded in deionized water, tap water at pH 7.0, tap water at pH 9.0, saline water at 0.5%, and saline water at 1%, reaching 352%, 207%, 230%, 522%, and 549%, respectively. Remarkably, the 0.5% VBHG treatment exhibits the most pronounced root elongation. The application of hydrogels in agriculture exhibits promise, particularly within drought-related contexts and potential soilless applications.