Global Challenges最新文献

V. R. S. Kumar, V. Sankar, N. Chandrasekaran, A. Sukumaran, S. A. R. M. Rafic, R. S. Bharath, R. V. Baskaran, C. Oommen, P. K. Radhakrishnan, S. K. Choudhary, “Sanal Flow Choking: A Paradigm Shift in Computational Fluid Dynamics Code Verification and Diagnosing Detonation and Hemorrhage in Real-World Fluid-Flow Systems.” Global Challenges 2020, 4, 2000012. https://doi.org/10.1002/gch2.202000012

The above article, published on May 27, 2020 in Wiley Online Library, has been retracted by agreement between the journal Editor-in-Chief, Mara Staffilani, and Wiley-VCH GmbH, Weinheim.

The retraction has been agreed due to concerns raised by a third party in a submitted Comment regarding the paper's proposed theory and its application of concepts.

Post-publication review by an independent reviewer determined that the article applies the concept of compressible flow to an inherently incompressible flow system. As a result, the article's hypothesis and following argument do not scientifically support its conclusions. Therefore, the conclusions are considered unreliable.

An investigation by Wiley and the journal's Editor-in-Chief supported this conclusion.

Carbons form critical components in biogas purification and energy storage systems and are used to modify polymer matrices. The environmental impact of producing carbons has driven research interest in biomass-derived carbons, although these have yield, processing, and resource competition limitations. Naturally formed fungal filaments are investigated, which are abundantly available as food- and biotechnology-industry by-products and wastes as cost-effective and sustainable templates for carbon networks. Pyrolyzed Agaricus bisporus and Pleurotus eryngii filament networks are mesoporous and microscale with a size regime close to carbon fibers. Their BET surface areas of ≈282 m² g⁻¹ and ≈60 m² g⁻¹, respectively, greatly exceed values associated with carbon fibers and non-activated pyrolyzed bacterial cellulose and approximately on par with values for carbon black and CNTs in addition to pyrolyzed pinewood, rice husk, corn stover or olive mill waste. They also exhibit greater specific capacitance than both non-activated and activated pyrolyzed bacterial cellulose in addition to YP-50F (coconut shell based) commercial carbons. The high surface area and specific capacitance of fungal carbon coupled with the potential to tune these properties through species- and growth-environment-associated differences in network and filament morphology and inclusion of inorganic material through biomineralization makes them potentially useful in creating supercapacitors.

In the present study, information collected from 360 coffee-cultivating households (HHs) is used to investigate perceptions of deficiencies in three sub-counties in Eastern Uganda and to study changes in these perceptions between two survey rounds. The results of an explorative principal components analysis identify five factors affecting farmers’ perceptions. Whereas perceptions of deficiencies in the preconditions for farm management activities differ significantly between the three sub-counties investigated, indicators of deficiencies in general life quality are distributed more equally. Deteriorations are explained mainly by perceived changes in weather conditions. On the one hand, it can be assumed that the high constraint level will continue to increase in the future due to climate change and its impacts on life quality and the basic conditions required for farm management. On the other hand, access to resources such as water taps but also increased competition between buyers, have improved the situation. Results further indicate that if activities such as the expansion of information access and improvement of road conditions (after land registration) are implemented on a larger scale, these negative trends can be partly counteracted to help farmers maintain the conditions for effective farm management and improve their quality of life in the future.

The acute water and electricity shortages in Gaza necessitate comprehensive solutions that recognize the interconnected nature of these vital resources. This article presents pragmatic solutions to align supply with fundamental needs in both domains, offering viable pathways for achieving strategic water-energy security in Gaza. Baseline data reveals a deficit in the current water supply, falling below the international minimum of 100 L per capita per day, while the reported 137–189 MW per day electricity supply significantly lags behind the estimated 390 MW per day peak demand. To meet projected 2024 residential, commercial, and industrial demands, this study proposes actionable measures including expanding wastewater treatment to enable over 150 MCM per year tertiary effluents for agricultural reuse and adopting energy-efficient forward osmosis-reverse osmosis and osmotically assisted reverse osmosis desalination methods to increase potable water supply to 150 MCM per year. Electricity supply strategies include scaling renewable capacity towards 110 MW per day, exploring regional cooperation to unlock over 360 MW of power per day, and potentially recovering up to 60 MW per day through system efficiencies. These recommendations aim to prevent exacerbated scarcity and alleviate hardships in Gaza.

In this work, bismuth tungstate Bi₂WO₆ is immobilized on polymer membranes to photocatalytically remove micropollutants from water as an alternative to titanium dioxide TiO₂. A synthesis method for Bi₂WO₆ preparation and its immobilization on a polymer membrane is developed. Bi₂WO₆ is characterized using X-ray diffraction and UV–vis reflectance spectroscopy, while the membrane undergoes analysis through scanning electron microscopy, X-ray photoelectron spectroscopy, and degradation experiments. The density of states calculations for TiO₂ and Bi₂WO₆, along with PVDF reactions with potential reactive species, are investigated by density functional theory. The generation of hydroxyl radicals OH^• is investigated via the reaction of coumarin to umbelliferone via fluorescence probe detection and electron paramagnetic resonance. Increasing reactant concentration enhances Bi₂WO₆ crystallinity. Under UV light at pH 7 and 11, the Bi₂WO₆ membrane completely degrades propranolol in 3 and 1 h, respectively, remaining stable and reusable for over 10 cycles (30 h). Active under visible light with a bandgap of 2.91 eV, the Bi₂WO₆ membrane demonstrates superior stability compared to a TiO₂ membrane during a 7-day exposure to UV light as Bi₂WO₆ does not generate OH^• radicals. The Bi₂WO₆ membrane is an alternative for water pollutant degradation due to its visible light activity and long-term stability.

Silicon (Si), the eighth most common element in the known universe by mass and widely applied in the industry of electronics chips and solar cells, rarely emerges as a pure element in the Earth's crust. Optimizing its manufacturing can be crucial in the global challenge of reducing the cost of renewable energy modules and implementing sustainable development goals in the future. In the industry of solar cells, this challenge is stimulating studies of ultrathin Si-based architectures, which are rapidly attracting broad attention. Ultrathin solar cells require up to two orders of magnitude less Si than conventional solar cells, and owning to a flexible nature, they are opening applications in different industries that conventional cells do not yet serve. Despite these attractive factors, a difficulty in ultrathin Si solar cells is overcoming the weak light absorption at near-infrared wavelengths. The primary goal in addressing this problem is scaling up cost-effective and innovative textures for anti-reflection and light-trapping with shallower depth junctions, which can offer similar performances to traditional thick modules. This review provides an overview of this area of research, discussing this field both as science and engineering and highlighting present progress and future outlooks.

Ceramic membranes are taking center stage for separation technologies in water treatment. Among them, ceramic nanofiltration membranes are at the forefront of membrane technologies. The desalination of seawater using ceramic nanofiltration membranes is a potential application toward increasing the global water supply and tackling water scarcity. However, while the high fabrication cost poses a challenge to their large-scale applications, high-value separation applications can help to offset the overall cost. In this regard, ceramic nanofiltration membranes can also be explored as a viable option for high-value lithium extraction from the waste seawater brine. In order to determine the potential of nanofiltration ceramic membranes for desalination and lithium recovery from seawater, the current efficiency of salt rejection across various operation parameters must be thoroughly evaluated. Specifically, the interactions between the Donnan exclusion, steric exclusion, zeta potential, and salt concentration play an important role in determining the salt rejection efficiency. Several strategies are then proposed to guide ceramic nanofiltration membranes toward potentially practical applications regarding desalination and lithium recovery.

In this study, thermodynamic analysis is implemented to the kerosene-fuelled high by-pass turbofan (HBP-TF) engine to assess entropy, exergy, environmental, and sustainability metrics for different design variables such as pressure ratio of high-pressure compressor (HPC-PR) ranging from 7.5 to 8.5 and turbine inlet temperature (TIT) varying from 1400 to 1525 K considering variable needs in the aviation industry. As a novelty, entropic improvement potential (EIP) index for turbomachinery components and specific irreversibility production for the whole engine are calculated. Sustainability-based parameters for different cases are compared with the baseline values of the HBP-TF engine. The combustor has the highest entropy production of 44.4425 kW K⁻¹ at the baseline. The higher TIT increases the entropy production of the combustor by 16.56%, whereas the higher HPC-PR decreases it by 5.83%. The higher TIT and HPC-PR favorably affect the sustainable efficiency factor of the engine, which is observed as 1.5482 at baseline and increases by 4.5% and 0.058% with the increment of TIT and HPC-PR, respectively. The higher TIT and higher HPC-PR results in lowering sustainability of the engine. The specific irreversibility production of the engine decreases by 3.78% and 0.1171% respectively, as TIT and HPC-PR reach the highest point considered in the study.