Calcium-magnesium-alumino-silicate induced degradation of La2(Zr0.7Ce0.3)2O7/YSZ double-ceramic–layer thermal barrier coatings prepared by electron beam-physical vapor deposition

During last decades, much effort has been made to develop new alternative thermal barrier coating (TBC) to traditional YSZ for applications above 1250oC. La2(Zr0.7Ce0.3)2O7(LZ7C3) is deemed as a very promising TBC candidate for advanced gas turbine because of its extremely low thermal conductivity, high sintering resistance and phase stability from room temperature to 1600oC. Thermal cycling with a gas burner showed that the LZ7C3/YSZ double-ceramic-layer (DCL) coatings prepared by electron beam-physical vapor deposition (EB-PVD) or atmospheric plasma spraying had a much longer lifetime than that of YSZ coating at 1250± 50oC.The use of the new TBC can allow higher gas temperatures, resulting in further improved thermal efficiency and engine performance. However, at these high operating temperatures, TBCs become susceptible to attack by calcium-magnesium-alumino-silicate (CMAS, relative to the main chemical components Ca, Mg, Al and Si) deposits resulting from the ingestion of siliceous minerals (dust, sand, volcanic ash, runway debris) with the intake air. CMAS becomes molten at temperatures above 1200oC and then rapidly penetrates the TBCs by capillary force, resulting in the loss of strain tolerance and premature failure of the coatings. In this paper, CMAS induced degradation of LZ7C3/YSZ DCL coatings prepared by EB-PVD method were investigated. Hot corrosion tests were performed at 1250oC at durations varying from 0.5 h to 24 h. It is observed that the infiltration of CMAS in the intercolumnar gaps was largely suppressed in the case of EB-PVD LZ7C3 coating. The penetration depth rarely exceeded 40 μm below the original surface even after 24 h exposure at 1250oC. This was ascribed to rapid dissolution of the LZ7C3 and essentially concurrent formation of a sealing layer made of crystalline apatite and fluorite phases, which is consistent with the observation on Gd2Zr2O7. However, large vertical cracks would form in the EB-PVD LZ7C3 coating during thermal cycling as a result of re-crystallization, sintering and thermal expansion mismatch between ceramic coating and substrate. These vertical cracks can also act as channels to CMAS melt infiltration. Since the kinetics of the dissolve-reprecipitation reaction was slower than the infiltration rate of CMAS in the vertical crack, the majority of vertical cracks were not sealed. As a result, CMAS flowed down to the LZ7C3/YSZ interface along the vertical cracks, and then easily penetrated the YSZ buffer layer by capillary force. Chemical interaction also occurred in the YSZ buffer layer. What\u27s more, the YSZ layer in the DCL coating even underwent a severer CMAS attack than the single YSZ coating. After 4 h CMAS exposure, the YSZ layer of the LZ7C3/YSZ bilayer coating was totally dissolved by molten CMAS followed by precipitation of a large number of globular ZrO2 particles, while the single YSZ coating just suffered a slight degradation in the same experimental conditions and still kept its columnar structure. The probable reason was that the CMAS melt in the YSZ layer of the DCL coating had a higher CaO/SiO2 ration than the original CMAS composition due to the formation of apatite phase when CMAS reacted with the upper LZ7C3 layer. The initial Si: Ca ratio (Si: Ca≈1.4) in CMAS melt is less than the corresponding apatite (Si: Ca≈3), leading to progressive CaO enrichment during apatite crystallization. For this reason, it is suggested that the effectiveness of the CMAS mitigation strategy for YSZ TBCs by adopting a so-called CMAS-resistant top layer needs to be assessed in the context of more realistic conditions. If the formation of large vertical cracks in TBCs was not avoided, this CMAS mitigation approach may not as effective as expected

Tailoring single-atom FeN4 moieties as a robust heterogeneous catalyst for high-performance electro-Fenton treatment of organic pollutants

An iron single-atom catalyst, composed of robust FeN4 moieties anchored on a nitrogen-doped porous carbón matrix (Fe-SAC/NC), has been developed via a surfactant-coordinated metal-organic framework (MOF) approach for application in heterogeneous electro-Fenton (HEF) process. The cohesive interaction between the surfactant and MOF precursor enabled the formation of abundant and stable FeN4 moieties. The Fe-SAC/NC-catalyzed HEF allowed the complete degradation of 2,4-dichlorophenol with low iron leaching (1.2 mg L-1), being superior to nanoparticle catalyst synthesized without surfactant. The experiments and density functional theory (DFT) calculations demonstrated the dominant role of single-atom FeN4 sites to activate the electrogenerated H2O2 yielding ¿OH. The dense FeN4 moieties allowed harnessing the modulated electronic structure of the SAC to facilitate the electron transfer, whereas the adjacent pyrrolic N enhanced the adsorption of target organic pollutants. Moreover, the excellent catalysis, recyclability and viability of the Fe-SAC/NC were verified by successfully treating several organic pollutants even in urban wastewater

Biochar addition can negatively affect plant community performance when altering soil properties in saline-alkali wetlands

Biochar is a widely proposed solution for improving degraded soil in coastal wetland ecosystems. However, the impacts of biochar addition on the soil and plant communities in the wetland remains largely unknown. In this study, we conducted a greenhouse experiment using soil seed bank from a coastal saline-alkaline wetland. Three types of biochar, including Juglans regia biochar (JBC), Spartina alterniflora biochar (SBC) and Flaveria bidentis biochar (FBC), were added to the saline-alkaline soil at ratios of 1%, 3% and 5% (w/w). Our findings revealed that biochar addition significantly increased soil pH, and increased available potassium (AK) by 3.74% - 170.91%, while reduced soil salinity (expect for 3% SBC and 5%SBC) by 28.08% - 46.93%. Among the different biochar types, the application of 5% FBC was found to be the most effective in increasing nutrients and reducing salinity. Furthermore, biochar addition generally resulted in a decrease of 7.27% - 90.94% in species abundance, 17.26% - 61.21% in community height, 12.28% - 56.42% in stem diameter, 55.34% - 90.11% in total biomass and 29.22% - 78.55% in root tissue density (RTD). In particular, such negative effects was the worst in the SBC samples. However, 3% and 5% SBC increased specific root length (SRL) by 177.89% and 265.65%, and specific root surface area (SRSA) by 477.02% and 286.57%, respectively. The findings suggested that the plant community performance was primarily affected by soil pH, salinity and nutrients levels. Furthermore, biochar addition also influenced species diversity and functional diversity, ultimately affecting ecosystem stability. Therefore, it is important to consider the negative findings indirectly indicate the ecological risks associated with biochar addition in coastal salt-alkaline soils. Furthermore, Spartina alterniflora was needed to desalt before carbonization to prevent soil salinization when using S. alterniflora biochar, as it is a halophyte

The p38 MAPK Inhibitor SB203580 Abrogates Tumor Necrosis Factor-Induced Proliferative Expansion of Mouse CD4+Foxp3+ Regulatory T Cells

There is now compelling evidence that tumor necrosis factor (TNF) preferentially activates and expands CD4+Foxp3+ regulatory T cells (Tregs) through TNF receptor type II (TNFR2). However, it remains unclear which signaling transduction pathway(s) of TNFR2 is required for the stimulation of Tregs. Previously, it was shown that the interaction of TNF–TNFR2 resulted in the activation of a number of signaling pathways, including p38 MAPK, NF-κB, in T cells. We thus examined the role of p38 MAPK and NF-κB in TNF-mediated activation of Tregs, by using specific small molecule inhibitors. The results show that treatment with specific p38 MAPK inhibitor SB203580, rather than NF-κB inhibitors (Sulfasalazine and Bay 11-7082), abrogated TNF-induced expansion of Tregs in vitro. Furthermore, upregulation of TNFR2 and Foxp3 expression in Tregs by TNF was also markedly inhibited by SB203580. The proliferative expansion and the upregulation of TNFR2 expression on Tregs in LPS-treated mice were mediated by TNF–TNFR2 interaction, as shown by our previous study. The expansion of Tregs in LPS-treated mice were also markedly inhibited by in vivo treatment with SB203580. Taken together, our data clearly indicate that the activation of p38 MAPK is attributable to TNF/TNFR2-mediated activation and proliferative expansion of Tregs. Our results also suggest that targeting of p38 MAPK by pharmacological agent may represent a novel strategy to up- or downregulation of Treg activity for therapeutic purposes

Selective Ethylene Glycol Oxidation to Formate on Nickel Selenide with Simultaneous Evolution of Hydrogen

There is an urgent need for cost-effective strategies to produce hydrogen from renewable net-zero carbon sources using renewable energies. In this context, the electrochemical hydrogen evolution reaction can be boosted by replacing the oxygen evolution reaction with the oxidation of small organic molecules, such as ethylene glycol (EG). EG is a particularly interesting organic liquid with two hydroxyl groups that can be transformed into a variety of C1 and C2 chemicals, depending on the catalyst and reaction conditions. Here, a catalyst is demonstrated for the selective EG oxidation reaction (EGOR) to formate on nickel selenide. The catalyst nanoparticle (NP) morphology and crystallographic phase are tuned to maximize its performance. The optimized NiS electrocatalyst requires just 1.395 V to drive a current density of 50 mA cm −2 in 1 potassium hydroxide (KOH) and 1 EG. A combination of in situ electrochemical infrared absorption spectroscopy (IRAS) to monitor the electrocatalytic process and ex situ analysis of the electrolyte composition shows the main EGOR product is formate, with a Faradaic efficiency above 80%. Additionally, C2 chemicals such as glycolate and oxalate are detected and quantified as minor products. Density functional theory (DFT) calculations of the reaction process show the glycol-to-oxalate pathway to be favored via the glycolate formation, where the C-C bond is broken and further electro-oxidized to formate. A combination of in situ and ex situ analysis shows the main product of the ethylene glycol (EG) oxidation reaction (EGOR) is formate with a Faradaic efficiency above 80%, and glycolate and oxalate as minor chemicals on nickel selenide nanoparticles (NPs). Further density functional theory (DFT) calculation reveals the electrooxidation mechanism to these products

Angiography-Based Computational Modeling for In Vivo Assessment of Endothelial Dynamic Strain in Coronary Arteries with De Novo Lesions: Comparison of Treatment Effects of Drug-Coated Balloons Between Small and Large Arteries

Acute morphological changes in de novo coronary lesions after drug-coated balloon (DCB) angioplasty can affect endothelial mechanics and consequently clinical outcomes. Angiography-based computational modeling has been validated to assess endothelial dynamic strain (EDS) in coronary arteries in vivo. The EDS was calculated on the basis of pre- and post-DCB angiography. Parameters of quantitative coronary angiography and EDS were quantified at cross-sections in the treated segments. A total of 336 and 348 lesion cross-sections were included in the small/large vessel groups, respectively. The acute lumen gain after DCB was significantly higher in large than small vessels (relative changes: 21.3% [17.4%, 25.1%] vs. 7.4% [4.8%, 10.1%], P < 0.001). Before treatment, three indices of EDS were significantly higher in small than large vessels (for ED-EDS: 29.2% [19.8%, 44.8%] vs. 20.4% [14.3%, 30.2%]; for ES-EDS: 26.8% [18.9%, 37.7%] vs. 18.3% [13.9%, 25.4%]; for TA-EDS: 19.1% [13.9%, 27.8%] vs. 14.3% [10.5%, 20.1%], P < 0.001). After treatment, the EDS in small vessels significantly decreased (P < 0.001). ED-EDS showed the highest correlation with pre-DCB DSP (r = 0.43, P < 0.001) and post-DCB MLD (r = 0.35, P < 0.001). The levels of EDS parameters for small or large vessel lesions significantly differed. Further study is required to examine the clinical value of EDS in predicting cardiac events after DCB treatment

Distributed secondary control of microgrids with unknown disturbances and non-linear dynamics

In this paper, the voltage and frequency regulation of microgrid with unknown disturbances and non-linear dynamics was studied. The disturbance observer was designed and the sliding mode control (SMC) method was used to realize the secondary regulation of voltage and frequency. First, a distributed secondary control protocol was designed to reduce the communication burden between generators and to solve voltage and frequency deviations. Second, a consensus protocol for secondary control of voltage and frequency was designed, based on the idea of multi-agent consensus, to indirectly ensure that the voltage and frequency to be adjusted reach the reference values when the consensus is realized. In addition, considering unknown disturbances in the microgrid, a sliding mode control strategy, based on a disturbance observer, was designed to overcome the influence of disturbances and to reduce chatter. This SMC scheme ensured finite time accessibility of the sliding mode surface. This design provides sufficient conditions for voltage and frequency regulation. The effectiveness of this design scheme was verified through simulation

Supporting Information for Adv. Sci., DOI 10.1002/advs.202300841 Selective Ethylene Glycol Oxidation to Formate on Nickel Selenide with Simultaneous Evolution of Hydrogen

16 pages. -- SEM-EDS characterization. -- HRTEM characterization. -- XPS spectra. -- Electrochemical characterization. -- EGOR Electrocatalytic performance comparision with previous results. -- Sample characterization after CA operation. -- IC Profile. -- Electrolytic cell coupling HER and EGOR. -- DFT data.Peer reviewe

Selective Ethylene Glycol Oxidation to Formate on Nickel Selenide with Simultaneous Evolution of Hydrogen

There is an urgent need for cost-effective strategies to produce hydrogen from renewable net-zero carbon sources using renewable energies. In this context, the electrochemical hydrogen evolution reaction can be boosted by replacing the oxygen evolution reaction with the oxidation of small organic molecules, such as ethylene glycol (EG). EG is a particularly interesting organic liquid with two hydroxyl groups that can be transformed into a variety of C1 and C2 chemicals, depending on the catalyst and reaction conditions. Here, a catalyst is demonstrated for the selective EG oxidation reaction (EGOR) to formate on nickel selenide. The catalyst nanoparticle (NP) morphology and crystallographic phase are tuned to maximize its performance. The optimized NiS electrocatalyst requires just 1.395 V to drive a current density of 50 mA cm-2 in 1 m potassium hydroxide (KOH) and 1 m EG. A combination of in situ electrochemical infrared absorption spectroscopy (IRAS) to monitor the electrocatalytic process and ex situ analysis of the electrolyte composition shows the main EGOR product is formate, with a Faradaic efficiency above 80%. Additionally, C2 chemicals such as glycolate and oxalate are detected and quantified as minor products. Density functional theory (DFT) calculations of the reaction process show the glycol-to-oxalate pathway to be favored via the glycolate formation, where the CC bond is broken and further electro-oxidized to formate.This work was supported by the start-up funding at Chengdu University and the Natural Science Foundation of Sichuan (NSFSC) project funded by the Science and Technology Department of Sichuan Province (Project No. 2022NSFSC1229), and also the open project from Hebei Key Laboratory of Photoelectric Control on Surface and Interface (Project No. ZD2022003). It was also supported by the European Regional Development Funds and by the Spanish Ministerio de Ciencia e Innovación through the project COMBENERGY (Project No. PID2019-105490RB-C32). Y.-Y.Y. acknowledges funding from the National Natural Science Foundation of China (NSFC, Grant No. 22172121), the Natural Science Foundation of Sichuan Province (NSFSC, Grant No. 23NSFSC6266) and the Fundamental Research Funds for the Central Universities, Southwest Minzu University (Grant No. xiao2021102). X.H. has received funding from the CSC-UAB Ph.D. scholarship program. X.H. and J.A. acknowledge funding from Generalitat de Catalunya 2021SGR00457. ICN2 acknowledges support from the Severo Ochoa Programme from Spanish MCIN/AEI (Grant No. CEX2021-001214-S). ICN2 authors thank the support from the project NANOGEN (PID2020-116093RB-C43), funded by MCIN/AEI/10.13039/501100011033/ and by "EDRF a way of making Europe", by the "European Union". IREC and ICN2 were funded by the CERCA Programme/Generalitat de Catalunya. Part of the present work was performed in the framework of the Universitat Autònoma de Barcelona Materials Science Ph.D. program. This study was also supported by MCIN with funding from European Union NextGenerationEU (Grant No. PRTR-C17.I1) and Generalitat de Catalunya.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2021-001214-S)Peer reviewe