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•MOFs and their derived materials as EF catalysts in water purification were reviewed.•The fabrication strategies of MOFs and advantages of MOFs derivatives were introduced.•The ...suitable pH and stability of MOFs-based materials for EF process were discussed.•The challenges and prospects of MOFs-based materials for EF process were presented.
As an important advanced oxidation process, electro-Fenton (EF) has gained considerable attention owing to its impressive ability for the degradation of refractory organic pollutants. Over the past few years, metal-organic frameworks (MOFs) have received widespread interest due to their unique merits such as large surface area, tunable pore structure and abundant active sites. MOFs derivatives with similar structural characteristics possess additional advantages compared to original MOFs, which further broadens the applications of MOFs. Particularly, MOFs-based materials have been extensively used in EF process recently and this research area is rapidly growing. This article presents a timely and comprehensive overview of MOFs and their derivatives as catalysts for EF process in water purification. We firstly reviewed synthetic methods of MOFs for EF process and displayed the advantages of MOFs derivatives. Representative research on MOFs, MOFs composites and their derivatives for EF process were then summarized. The reaction mechanisms in the EF process for elimination of various contaminants (including antibiotics, herbicides, and dyes) with MOFs-based materials as catalysts were described. Finally, an outlook on the current challenges and promising opportunities in this research area were discussed. This review should be of value in facilitating MOFs-based materials to become a competitive choice as EF catalysts for water purification.
We combined year-round eddy covariance with biometry and biomass harvests along a chronosequence of boreal forest stands that were 1, 6, 15, 23, 40, ∼74, and ∼154 years old to understand how ...ecosystem production and carbon stocks change during recovery from stand-replacing crown fire. Live biomass (Clive) was low in the 1- and 6-year-old stands, and increased following a logistic pattern to high levels in the 74- and 154-year-old stands. Carbon stocks in the forest floor (Cforest floor) and coarse woody debris (CCWD) were comparatively high in the 1-year-old stand, reduced in the 6- through 40-year-old stands, and highest in the 74- and 154-year-old stands. Total net primary production (TNPP) was reduced in the 1- and 6-year-old stands, highest in the 23- through 74-year-old stands and somewhat reduced in the 154-year-old stand. The NPP decline at the 154-year-old stand was related to increased autotrophic respiration rather than decreased gross primary production (GPP). Net ecosystem production (NEP), calculated by integrated eddy covariance, indicated the 1- and 6-year-old stands were losing carbon, the 15-year-old stand was gaining a small amount of carbon, the 23- and 74-year-old stands were gaining considerable carbon, and the 40- and 154-year-old stands were gaining modest amounts of carbon. The recovery from fire was rapid; a linear fit through the NEP observations at the 6- and 15-year-old stands indicated the transition from carbon source to sink occurred within 11-12 years. The NEP decline at the 154-year-old stand appears related to increased losses from Clive by tree mortality and possibly from Cforest floor by decomposition. Our findings support the idea that NPP, carbon production efficiency (NPP/GPP), NEP, and carbon storage efficiency (NEP/TNPP) all decrease in old boreal stands.
Taiwan's vocational wood-furniture schools still focus only on the traditional manual training strategy, and so students' knowledge of the furniture-manufacturing process is fragmented. Moreover, ...they possess limited manual skills without learning the workflows and strategies of furniture production, which is inadequate for satisfying the direct work demands of the furniture industry overseas. In response, through virtual reality (VR) technology, this study employed simulations of the furniture production lines in a large Vietnamese furniture-manufacturing factory, enabling students to experience and observe the manufacturing process of furniture production through VR to overcome the limitations in the present teaching environment. In doing so, we recruited 29 freshmen majoring in a furniture-and-woodworking program and divided them into an experimental group (N=15) and a control group (N=14). They were trained with actual furniture production-process cases according to the furniture mass-production process, including paper-based tests, equipment configuration re-draws and production planning table writing. The results showed that the students in the experimental VR-training group had superior judgment concerning the concept of batch furniture production line. This indicates that applying VR technology to the vocational training of batch furniture production effectively enhanced the students' familiarity of the fast and dynamic production situation of furniture production lines.
The strategic incorporation of the neurotransmitter dopamine around a cobaloxime core resulted in excellent electrocatalytic (rate 8400 s−1) and photocatalytic H2 production under neutral aqueous ...conditions. The influence of the synthetic outer coordination sphere features continues even with a phenylene–diimino–dioxime motif-coordinated cobalt core.
Taking Chaoyang District of Beijing as an example, this paper identified Production-Living-Ecological Space in rural-urban fringe, and described the spatial pattern evolution with the help of ...transformation matrix and spatial analysis tools. On this basis, the spatial metrology models were selected to analyze the driving factors of space conversion. The results show that, 1) from 2005 to 2020, according to the spatial order from near to far from the city center, the scale of Production Space was reduced and concentrated, the Ecological Space formed a green ecological landscape belt in the periphery of Beijing, the Eco-Agricultural Production Space and the Life-agricultural Production Space were rapidly reduced, and the Living-Non-farm Production Space was rapidly expanded in the point-line-plane order. 2) From 2005 to 2020, the shift of Production Space to Living-Non-farm Production Space was always the main direction of conversion, the Living-Non-farm Production Space continued to gain a large amount of infl
•An extended goal programming model for the integrated lot sizing and cutting stock problem.•Column generation procedure to solve a goal programming model.•Study of the trade-offs among the different ...goals of the problem.•Weight sensitivity analysis for minimizing unwanted deviations from targets.•Result analysis using performance profile and time-to-target plot methodologies.
Lot sizing and cutting stock problems generally arise in manufacturing as a two stage connected process. Although these two problems have been addressed separately by many authors, recently, inspired by practical applications, some studies have emerged analyzing their integration. The mono-objective version of the integrated lot-sizing and cutting stock problem can be considered as an enhancement that minimizes the global production cost. However, it does not include the multiple criteria that can arise from the inclusion of multiple stakeholders in a modern, distributed manufacturing process. This paper aims to introduce a new extended goal programming model for the integrated lot-sizing and cutting stock problem which models the arising multiple criteria by a set of goals representing the interests of different stakeholders in the manufacturing process. This formulation allows for the consideration of the balance between the conflicting goals of multiple stakeholders and the cost efficiency of the overall process. In order to efficiently solve the proposed model, a column generation based heuristic procedure is applied. The trade-offs among the various criteria related to the problem are assessed, and a series of computational experiments are performed. The computational results compare individual criteria weighting schemes and evaluate the goals’ sensitivity using performance profiles and time-to-target plots methodologies.
Electroreduction of N2 into NH3 represents a promising method for N2 fixation. However, due to the inertness of NN covalent triple bonds, this process remains a huge challenge to achieve a high ...yield rate of NH3. In this work, we designed an effective approach to promoting N2 activation by introducing oxygen vacancies into LaCoO3. In N2 electroreduction, LaCoO3 with oxygen vacancies (denoted as V o-LaCoO3) exhibited a Faradaic efficiency of 7.6% for NH3 at −0.6 V versus the reversible hydrogen electrode (RHE). Notably, at −0.7 V versus RHE, the yield rate for NH3 of V o-LaCoO3 reached 182.2 μgNH3 mg–1 cat. h–1, which was 2.8 times higher than that (65.3 μgNH3 mg–1 h–1) of pristine LaCoO3. To the best of our knowledge, the yield rate for NH3 of V o-LaCoO3 approaches the activities of the state-of-the-art catalysts toward N2 electroreduction. Density functional theory calculations revealed that enhanced activation of N2 over V o-LaCoO3 originated from the increased charge density around the valence band edge via the introduction of oxygen vacancies. Furthermore, the analysis of the thermodynamic limiting potentials for N2 reduction and H2 evolution demonstrated the higher selectivity for N2 electroreduction over V o-LaCoO3 relative to pristine LaCoO3.
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•Urea groups acted as the docking sites of MnS and hydrogen evolving centers.•The formation of ligating linkage provided a charge transfer pathway.•The photocatalytic H2 evolution ...over MnS/D-Melon followed the Z-scheme mechanism.
Given that low hydrogen active sites and serious photoexcited electron-hole recombination greatly limits the solar-to-chemical energy conversion efficiency, a synergistically integrated strategy of the defect engineering and the construction of Z-scheme heterojunction is introduced to the design of PCN photocatalyst, a strand-like polymer carbon nitride, in this work to resolve these problems and enhance the photocatalytic activity. The PHE activity was intimately related to MnS compositions. A maximum hydrogen evolution rate of 670.5 μmol/g/h could be achieved over 5% MnS/D-PCN composite, almost 5 times the rate of D-PCN and 18.4 times higher than that pristine PCN. This high PHE activity of MnS/D-PCN was attributed to the following factors: defects effects and Z-scheme heterojunction. We found that defects sites, on one hand, were the docking sites of MnS through a linkage to bridging the MnS and defected PCN, which offered an efficient spatial transfer path for electron-hole pairs at the interface, on the other hand, acted as the hydrogen evolving centers gathering the excited photoelectrons from D-PCN and MnS. Furthermore, Z-scheme pathway greatly enhanced the photoexcited charge separation due to their enormous driving force in internal electric field of p-n heterojunction.
This study investigates the relationship between natural gas price and production and analyzes whether the recent shale gas boom has changed the nexus between the two. We set up a framework to test ...the directions of causal links between natural gas price and two measures of natural gas production: (1) gross natural gas production (aggregate of conventional natural gas and shale gas productions) and (2) conventional natural gas production only. Based on monthly data of 16 states in the U.S. between January 2007 and December 2016, we find robust evidence of a reliable relationship between natural gas price and gross production, but no reliable cointegration between gas price and conventional natural gas production. Our results are robust when we account for potential structural breaks and cross-section dependence in the data. Our evidence denotes that the recent shale gas boom has changed the relationship between natural gas price and production in the U.S. Moreover, our study shows that the structure break in the U.S market highly correlates to shale gas and also provides some evidence on that while cross-state factors result in long-term mean reversion, state-specific factors lead to a permanent shock.
•We investigate the long-run relationship between natural gas price and production considering the structural breaks.•We ask whether the recent shale gas boom changed the nexus between the two.•Based on monthly data of 16 states in the U.S. between January 2007 and December 2016.•Shale gas boom changed the long-run relationship between the natural gas price and production in the U.S.
We report a photocatalytic system that utilizes Cd0.5Zn0.5S nanotwins decorated with various Ni-based co-catalysts for solar-driven hydrogen production through lignocellulose reformation. In this ...noble-metal-free system, Ni(OH)2 emerges as the most effective Ni form in enhancing the photocatalytic evolution of H2. By optimizing the composition with 3 wt% Ni(OH)2 loading, we achieved the highest activity, with the hydrogen production rates of 7.00 mmol g−1 h−1 and 1.97 mmol g−1 h−1 from α-cellulose and waste straw photoreforming, respectively. This optimized composition exhibited the highest quantum efficiency of 7.68%. In principle, the lower potential of Ni2+/Ni compared to the conduction band of Cd0.5Zn0.5S facilitates the transfer of electrons from the conduction band of Cd0.5Zn0.5S to Ni(OH)2. Specifically, during the photocatalytic reaction, a fraction of surface Ni(OH)2 is reduced to Ni. The in-situ formed Ni clusters, along with the Ni(OH)2, enhance the separation photogenerated electrons and facilitate their transfer to H+, leading to significantly improved photocatalytic activity. This work not only provides an effective strategy for developing more efficient photocatalysts, but also offers a direct means of harnessing clean energy from abundant waste biomass on Earth.
•Ni(OH)2/Ni atoms or clusters can serve as co-catalysts enhance the hydrogen production activity of Cd0.5Zn0.5S.•The cellulose/lignocellulose photoreforming system exhibits exceptional H2 production efficiency.•The photothermal effect of the Ni(OH)2/Cd0.5Zn0.5S photocatalyst enhances the reaction activity.
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