196746 research outputs found
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An intense source of very cold neutrons using solid deuterium and nanodiamonds for the European Spallation Source
No full textThe European Spallation Source (ESS), currently under construction, is based on a high-brightness, bi-spectral, low-dimensional moderator placed above a spallation target, intended to initially serve fifteen neutron scattering instruments. Within the upgrade path of ESS, the HighNESS project aims at designing a source complementary to this upper moderator, focusing on delivering a higher intensity and a colder spectrum of neutrons. We have investigated the use of solid ortho-deuterium at 5 K as a source of very cold neutrons (VCNs). This source performs competitively as a high-intensity cold-neutron moderator, while also showing an order-of-magnitude flux increase in the very cold range above 40 ̊ A compared to a liquid deuterium moderator of similar volume and shape, also designed within HighNESS. The long-wavelength performance of the source can be improved further by encasing it in a thin layer of nanodiamonds. The cooling of a solid deuterium moderator placed so close to the spallation target of a high-power neutron source like ESS is very challenging, but may be feasible by augmenting the heat conductivity with the addition of low-density metallic foam structures within the moderator vessel. Such a source could provide unprecedented opportunities in fundamental physics research and neutron scattering using VCNs.</p
Analysis of Li-ion battery under high discharge rate embedded with metal foam phase change composite: A numerical study
No full textLithium-ion batteries (LIBs) have emerged as an unmatched candidate in the development of electric vehicles (EVs) and hybrid electric vehicles (HEVs). The LIBs produce significant amount of heat during operation and therefore, their thermal management is crucial for safety and reliable operation. Therefore, a unified three-dimensional numerical study from cell level to battery pack level incorporating an effective thermal management system is required. The current study presents an analysis on LIB module coupled with phase change material (PCM)/copper metal foam (MF) composite for thermal management. A three-dimensional (3D) thermal model is developed for a prismatic single cell and a 7S1P battery pack (26 V) subjected to rapid discharging, realistic drive cycles and thermally abusive conditions. The electrochemical behavior of the cell is modeled using a sub-scale equivalent circuit model. Both the thermal equilibrium and thermal non-equilibrium conditions have been compared for the coupled simulations of MF-PCM composite. The effect of composite characteristics such as PCM thickness, foam porosity and pores per inch (PPI) on the temperature distribution is analyzed. The thermal performance of the MF-PCM composite is evaluated for rapid discharging tests (5C and 4C), aggressive duty and realistic driving cycles, and external and internal short circuit tests. For 8 mm thickness of MF-PCM composite with porosity of 0.95, the MF-PCM composite is found to reduce the maximum cell temperature by 3.77 K compared to pure PCM case and maintains a more uniform temperature gradient. The temperature rise in cells can be reduced by 56 % compared to the cells with natural convection cooling. While simulating four continuous loops of aggressive duty cycles, the end temperature of the cells is found to be 310.9 K for MF-PCM composite, in contrast to 341.3 K for natural convection cooling. MF-PCM composite limits the temperature and temperature gradient in the battery pack (7S1P) and eliminates the temperature hotspots. The current configuration of PCM-MF is found to be effective in controlling the battery pack temperature for realistic drive cycles
How to measure circularity? State-of-the-art and insights on positive impacts on businesses
No full textAs the circular economy (CE) grows, it is necessary for companies to prepare for their transition from linear to circular, targeted to generate a positive business impact. Therefore, the aim of this study is threefold. First, to map what high impact research on circularity indicators and CE actions is reporting. Second, to point out challenges and opportunities in the application of circularity indicators. Third, to discuss implications for businesses wanting to generate positive impacts. To that end, a systematic literature review was carried out on the ScienceDirect, Scopus and Web of Science databases. Existing research on circularity indicators is based on either circularity measurement indices (0 to 100%) or circularity assessment tools, which are developed for one or more levels of application within micro, meso, and macro. The main challenges for establishing circularity indicators are linked to the lack of standardization on how to measure circularity and on providing clear guidance on how the indicator can and should be used. The main opportunities lie on bringing to life the concept of circularity through practical applications and reveling opportunities for internalizing flows. Internalizing flows can lead to a positive business impact and measuring circularity can be a tool for business management on top of bringing about circular-economy-related benefits
Degradation mechanisms in PBSAT nets immersed in seawater
No full textFishing gears are known to continue fishing after being abandoned, lost, or discarded through a phenomenon called ghost fishing. After this ghost fishing period, disintegrated nets contribute to plastic pollution. Biodegradable nets could be an alternative to conventional nets to reduce ghost fishing but must strike a delicate balance between durability and degradation. This study evaluates the seawater degradation of a net made of polybutylene(succinate-co-adipate-co-terepthalate) (PBSAT) at several scales: monofilament, knot, and net. Mechanical testing was used to monitor the strength at each scale during immersion at several temperatures: 4 °C, 15 °C, 25 °C, 40 °C. Steric exclusion chromatography (SEC), scanning electron microscopy (SEM) and X-ray tomography were used to investigate degradation processes. While no degradation was observed for samples immersed for 240 days at 4 °C, hydrolysis led to embrittlement at 40 °C. Biotic degradation was observed at both 15 °C and 25 °C with distinct degradation patterns and bacteria shapes. At both temperatures, the degradation was accelerated in the knot, leading to an unusable net after 240 days at 15 °C while no loss of strength was detected at the monofilament scale. These findings suggest that the durability of the knot is critical for successful development of a biodegradable polymer for application in gillnets
Evaluating the economic landscape of hybrid-electric regional aircraft:A cost analysis across three time horizons
No full textThis article presents the results of a prospective cost analysis of future regional aviation solutions, specifically focusing on hybrid-electric regional aircraft for 50 passengers. The study spans three time horizons (short term, medium term, long term) and employs a validated workflow to estimate costs for various solutions, including conventional, hybrid-electric, and hydrogen-based architectures. A specialized cost model is introduced to assess the electric components of the powertrain, emphasizing maintenance expenses and energy costs. Despite the environmental promise of hybrid and electric solutions, the results reveal significantly higher direct operating costs (up to 69.8%) compared to conventional options. The study highlights the importance of targeted policies to incentivize sustainable alternatives, suggesting potential solutions such as discouraging kerosene-based aircraft and promoting sustainable aviation fuel. These insights provide valuable guidance for industry stakeholders navigating the path toward a more sustainable and economically viable aviation future
Enhanced permanganate oxidation of phenolic pollutants by alumina and potential industrial application
No full textIn this study, we found that alumina (Al2O3) may improve the degradation of phenolic pollutants by KMnO4 oxidation. In KMnO4/Al2O3 system, the removal efficiency of 2,4-Dibromophenol (2,4-DBP) was increased by 26.5%, and the apparent activation energy was decreased from 44.5 kJ/mol to 30.9 kJ/mol. The mechanism of Al2O3-catalytic was elucidated by electrochemical processes, X-ray photoelectron spectroscopy (XPS) characterization and theoretical analysis that the oxidation potential of MnO4− was improved from 0.46 V to 0.49 V. The improvement was attributed to the formation of coordination bonds between the O atoms in MnO4− and the empty P orbitals of the Al atoms in Al2O3 crystal leading to the even-more electron deficient state of MnO4−. The excellent reusability of Al2O3, the good performance on degradation of 2,4-DBP in real water, the satisfactory degradation of fixed-bed reactor, and the enhanced removal of 6 other phenolic pollutants demonstrated that the KMnO4/Al2O3 system has satisfactory potential industrial application value. This study offers evidence for the improvement of highly-efficient MnO4− oxidation systems
Pivotal Role of Intracellular Oxidation by HOCl in Simultaneously Removing Antibiotic Resistance Genes and Enhancing Dewaterability during Conditioning of Sewage Sludge Using Fe<sup>2+</sup>/Ca(ClO)<sub>2</sub>
No full textPre-acidification has been shown to be crucial in attenuating antibiotic resistance genes (ARGs) during the conditioning of sewage sludge. However, it is of great significance to develop alternative conditioning approaches that can effectively eliminate sludge-borne ARGs without relying on pre-acidification. This is due to the high investment costs and operational complexities associated with sludge pre-acidification. In this study, the effects of Fe2+/Ca(ClO)2 conditioning treatment on the enhancement of sludge dewaterability and the removal of ARGs were compared with other conditioning technologies. The dose effect and the associated mechanisms were also investigated. The findings revealed that Fe2+/Ca(ClO)2 conditioning treatment had the highest potential, even surpassing Fenton treatment with pre-acidification, in terms of eliminating the total ARGs. Moreover, the effectiveness of the treatment was found to be dose-dependent. This study also identified that the •OH radical reacted with extracellular polymeric substance (EPS) and extracellular ARGs, and the HOCl, the production of which was positively correlated with the dose of Fe2+/Ca(ClO)2, could infiltrate the EPS layer and diffuse into the cell of sludge flocs, inducing the oxidation of intracellular ARGs. Furthermore, this study observed a significant decrease in the predicted hosts of ARGs and MGEs in sludge conditioned with Fe2+/Ca(ClO)2, accompanied by a significant downregulation of metabolic pathways associated with ARG propagation, thereby contributing to the attenuation of sludge-borne ARGs. Based on these findings, it can be concluded that Fe2+/Ca(ClO)2 conditioning treatment holds great potential for the removal of sludge-borne ARGs while also enhancing sludge dewaterability, which mainly relies on the intracellular oxidation by HOCl
Embedded iron and nitrogen co-doped carbon quantum dots within g-C<sub>3</sub>N<sub>4</sub> as an exceptional PMS photocatalytic activator for sulfamethoxazole degradation:The key role of FeN bridge
No full textThe covalent modification of graphite-phase carbon nitride (g-C3N4) by carbon quantum dots (CQDs) is a promising way to improve its photocatalytic performance. Although CQDs can act as charge mediator for electrons storage and transfer, it is crucial to construct efficient interfaces, which serves as active sites for tight connect with g-C3N4 and fast release of electrons. Herein, a novel iron and nitrogen co-doped carbon quantum dots (Fe, N-CQDs) assembled g-C3N4 composite (FNCCN) was constructed via FeN bridge by hydrothermal and thermal polymerization methods. The FNCNN rivaled popular nitrogen-doped carbon quantum dots (N-CQDs) combined with g-C3N4 composites for peroxymonosulfate (PMS) activation and degradation of sulfamethoxazole (SMX). The SMX degradation rate (0.0963 min−1) is 5.38 and 3.15 times higher than that of g-C3N4 and N-CQDs/g-C3N4. The characterization and DFT calculation results suggest that Fe, N-CQDs was successfully incorporated into carbon matrix of g-C3N4 via FeN covalent bond, which joints the two counterparts closely and creates electron transport channels for higher electrons transfer efficiency. The FeN coordinated structure promotes PMS reduction on Fe2+ of FeN sites for HO and SO4⋅- production and expedited photo carries separation through Fe3+/Fe2+ cycling. In addition, the degradation efficiency, ROS identification, EPR test and degradation pathway of SMX was determined, and the intermediate toxicity of degradation products was predicted. This work constructed a tight atomic-level connection between hydrophobic g-C3N4 and hydrophilic CQDs, which improved an effective strategy for accelerating electron transport and efficient photocatalytic activation of PMS.</div
Prevention of Thermal Gelation in Concentrated Whey Protein Isolate Dispersions by Using H<sub>2</sub>O<sub>2</sub> and SHMP
No full textIn the present study, the effect of hydrogen peroxide (H2O2) and sodium hexametaphosphate (SHMP) on the thermal (121.5 °C for 15 min) stability of aqueous dispersions of whey protein isolate (6 % and 10% w/w) was investigated. Based on findings, H2O2, by oxidizing the sulfhydryl (SH) groups, prevented the formation of S–S bonds, therefore prevented thermal aggregation. The presence of SHMP synergistically enhanced the effect of H2O2 by reducing its required concentration. The majority of H2O2 treated samples remained soluble over long cold storage period. This study proved the abilities of H2O2 and SHMP in preventing protein denaturation and improving the thermal stability of whey protein isolate based drinks
Design and Synthesis of Transition Metal- Based Oxygen Catalyst and their Applications in Sustainable Energy Technology
No full textIn response to the environmental challenges posed by traditional fossil fuels, there is an urgent demand for clean energy technologies to mitigate greenhouse gas emissions and address global warming. This imperative has driven the exploration of sustainable energy technologies, such as water electrolysis, zincair batteries, and fuel cells, each playing a vital role in reducing dependence on fossil fuels. Water electrolysis offers a pathway for hydrogen production, zinc-air batteries provide an eco-friendly energy storage solution, and fuel cells directly convert chemical energy into electricity with zero emissions. The common thread among these technologies lies in their reliance on efficient oxygen electrocatalysis. This thesis focuses on the design of affordable and stable oxygen electrocatalysts to address the sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).The initial part of the thesis concentrates on OER research in oxygen electrocatalysis, specifically the synthesis of Fe-doped metal-organic cobalt hydroxide (Fe0.2Co0.8(OH)(Hsal)). Employing a straightforward and cost-effective synthesis method without the need for complex surfactants, the study investigates the impact of Fe doping on the catalyst through XPS and in situ electrochemical impedance spectroscopy (ESI) tests. Results indicate that Fe0.2Co0.8(OH)(Hsal) outperforms Co(OH)(Hsal) in OER performance, attributing this improvement to introduced defects and altered surface electronic structure. Morphological and structural characterizations confirm the positive impact of Fe introduction, revealing lower resistance and higher catalytic activity in Fe0.2Co0.8(OH)(Hsal), suggesting its broad applicability in OER. The incorporation of Fe demonstrates a universally positive influence on the performance of single metal catalysts, presenting wide-ranging applicability in the development of catalysts for the oxygen evolution reaction (OER). This advancement is poised to yield oxygen electrocatalysts that are not only more effective but also cost-efficient.The second part explores the ORR aspect of oxygen electrocatalysis. Pt-FeNC, synthesized on single-atom transition metal-nitrogen-carbon (TMNC) materials through photoreduction, demonstrates excellent performance compared to commercial Pt/C. This catalyst exhibits outstanding ORR performance and stability in rechargeable zinc-air batteries (ZABs), positioning it as a potential catalyst for advancing sustainable energy technologies. To address the cost concerns associated with precious metal platinum in proton exchange membrane fuel cell (PEMFC) systems, Pt-Co electrocatalysts derived from zeolitic imidazolate frameworks (ZIFs) showcase the potential to maintain high initial activity and durability at low platinum loadings. Using an electrospun polyacrylonitrile (PAN) substrate, the study forms Pt-Co nanoparticles through ZIF structure growth and heat treatment, demonstrating superior ORR activity and providing a promising way to reduce the usage of Pt in PEMFC systems