The gas diffusion layer (GDL) has garnered extensive attention as one of the key materials for membrane electrode assembly (MEA) in proton exchange membrane fuel cells (PEMFCs). The durability of the GDL has a signifi...
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The gas diffusion layer (GDL) has garnered extensive attention as one of the key materials for membrane electrode assembly (MEA) in proton exchange membrane fuel cells (PEMFCs). The durability of the GDL has a significant impact on the lifetime of PEMFCs. However, there exists a gap in independent and systematic research on the durability of carbon papers (CPs), which serve as GDL substrates. In this study, carbon corrosion tests were conducted on commercial SGL 29AA CPs by applying a series of fixed potentials. Through physical, electrochemical, and spectroscopic analyses, the effect of applied potential on the carbon corrosion mechanism and its corresponding impact on fuel cell performance were explored. We observed that carbon corrosion tends to occur more on carbonized resins. The oxidation of carbonized resins mainly produced C-O bonds at low potential oxidation (E = 1.00 V), leading to a slight decrease in the contact angle by 11.2 degrees. Higher potential oxidation (E >= 1.25 V) resulted in carbonized resin detachment and an increase in surface C=O bonds, which led to a hydrophilic contact angle and a more than 3-fold increase in resistivity. Furthermore, we discovered that TGP-H-060 CPs with a high graphitization degree improve high potential carbon corrosion resistance. Thus, our findings suggest that the primary strategy for augmenting the corrosion resistance of CPs is elevating the graphitization level of carbonized resins.
Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic conditions characterized by periods of intestinal inflammation and have become global diseases. Dietary p...
Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic conditions characterized by periods of intestinal inflammation and have become global diseases. Dietary pectins have shown protective effects on IBD models. However, the development of pectin-based diet intervention for IBD individuals requires knowledge of both the bioactive structural patterns and the mechanisms underlying diet-microbiota-host interactions. Here, dextran sulfate sodium (DSS) induced colitis mice were fed with different pectins with various domain compositions, including AG, P37, P55 and P85, in order to understand why different structural patterns function differently on colitis mouse models. The structural diversity of pectin manifests in the different percentages of the homogalacturonan (HG) backbone, Ara sidechains, and Gal sidechains. AG comprises only neutral sugar chains consisting of 14% Ara and 86% Gal, and P85 is a commercial HG pectin mainly composed of 85% HG. P37 and P55 were isolated from raspberry pulps with different domain ratios (P37 = 37% HG + 22% Ara + 32% Gal;P55 = 55% HG + 16% Ara + 18% Gal). Compared to the monotonous structure of AG and P85, the domain-diverse pectins P37 and P55 show superior protective effects against colitis through inhibiting the proliferation of the mucin-consuming bacteria and the pro-inflammatory microorganisms, potentiating the MUC2 expression and the mucus layer and regulating the gut-spleen axis. The HG structure promoted the proliferation of the mucin-degrading microbiota and potentiated mucus erosion. AG enhanced the mucus thickness but increased the growth of the pro-inflammatory microbiota. Our study revealed that the specific domain composition of pectic fibers was a key factor on which the diet-induced alterations in the gut microbiota and the intestinal barrier function highly depended.
Bimetallic Ni/Fe-nanoparticles were developed to enhance the dechlorination reactivity of nano-sized zero-valent iron. The physical structures of Ni/Fe-NPs with an Ni loading ranging from 0.5 wt% to 20 wt% and their s...
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Bimetallic Ni/Fe-nanoparticles were developed to enhance the dechlorination reactivity of nano-sized zero-valent iron. The physical structures of Ni/Fe-NPs with an Ni loading ranging from 0.5 wt% to 20 wt% and their structure-dependent reactivity variations towards trichloroethene (TCE) and carbon tetrachloride (CT) were fully investigated. A Ni-accumulated surface was observed for the Ni/Fe-NPs with a high Ni loading (20 wt%), and the structure of the other Ni/Fe NPs was identified as a Ni/Fe alloy-like structure, with the 5 wt% Ni/Fe NPs owning the highest surface area and Fe0 content. While the best CT dechlorination rate was 2.5-fold that of B-nZVI at 5 wt% Ni loading, the best TCE reduction was 12-fold of B-nZVI at a medium Ni loading (3-5 wt%). Given that the primary TCE degradation mechanism was via atomic hydrogen (H*), and the degradation of CT proceeds via direct electron transfer, the more efficient reduction mechanism for the Ni/Fe NP system was preferably H* reduction. The variation in the reduction rate and the by-product yield between the medium loading (3-5 wt%) and low/high (0.5 wt% and 20 wt%) loading was more significant for TCE than CT. It was found that the medium Ni loading (3-5 wt%) obviously boosted the beta-elimination of TCE to VC due to the good storage of H* in the Ni catalyst. The production of H* and enhanced electron migration rate were well demonstrated by the CV curve and Tafel curve, respectively. The location of direct electron transfer and H* catalyst in the bimetallic Ni/Fe system was further discussed.
The large emission of greenhouse gases has underscored the critical need for advancing research on carbon capture, utilization, and storage (CCUS) technology. Nanoemulsions have emerged as a promising approach to addr...
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The large emission of greenhouse gases has underscored the critical need for advancing research on carbon capture, utilization, and storage (CCUS) technology. Nanoemulsions have emerged as a promising approach to addressing safety challenges posed by factors such as CO2 plume migration during carbon geological sequestration. Prolonging the lifetime of nanoemulsions can significantly enhance both the efficiency and the security of carbon storage. The effects of surfactants on supercritical carbon dioxide (sCO2) nanoemulsions and the sCO2-H2O interface are investigated using molecular dynamics simulations. It is revealed that surfactants incorporating trisiloxane hydrophobic groups and polyacrylamide hydrophilic chains exhibited a synergistic interaction, substantially improving the stability of nanoemulsions. Moreover, the acrylamide group is identified as the most significant contributor during the association process among the surfactant components. The PA5 surfactant reduced the self-aggregation rate to 13.00% and extended the nanoemulsion aggregation time from 11.32 ns (control group without surfactants) to 81.16 ns. The enhancement in stability is attributed to PA5 achieving an optimal balance between hydrophilicity and CO2 affinity and binding at the nanoemulsion surface with efficiency and stability. PA5 holds great promise as a high-performance surfactant for applications in CCUS technology.
With broad usage of lithium-ion batteries (LIBs) in electronic devices and electric vehicles (EVs), a large number of decommissioned LIBs will be generated, which cause serious environmental pollution and waste of res...
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With broad usage of lithium-ion batteries (LIBs) in electronic devices and electric vehicles (EVs), a large number of decommissioned LIBs will be generated, which cause serious environmental pollution and waste of resources. Therefore, to reduce environmental pressure and realize secondary resource utilization of valuable metals, recycling decommissioned LIBs is urgent. At present, although pyrometallurgy, hydrometallurgy, direct regeneration and other methods have been used significantly in the recovery of failed LIB cathode materials, it is still necessary to formulate the best recovery strategy to achieve higher recovery efficiencies and value-added materials from spent cathodes. Thus, in this article, the latest progress in the recycling of retired LIB layered oxide cathode materials is reviewed in detail, and the recycling process, advantages and limits of each recycling method are analyzed. In view of the recycling challenges, the future development is prospected to promote the sustainable, environmentally friendly and efficient reutilization of failed LIB cathodes and contribute to the low-carbon circular economy.
Iridium (Ir)-based catalysts embracing both catalytic activity and stability are of great significance for scaling up the application of proton exchange membrane water electrolysis (PEMWE). Herein, supported IrO2 on T...
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Iridium (Ir)-based catalysts embracing both catalytic activity and stability are of great significance for scaling up the application of proton exchange membrane water electrolysis (PEMWE). Herein, supported IrO2 on TiO2 (IrO2/TiO2) with high specific surface area and electrolytic activity was prepared by adopting a chlorine (Cl)-free synthesis based on the Adams fusion method. The crucial influential factors of annealing temperature were systematically explored on the catalytic activity and stability of IrO2/TiO2. Although increasing annealing temperature is believed to be of benefit to the increase of crystallinity and nanoparticle size in the catalyst, thus improving the stability of the catalyst, the as-prepared catalyst annealed at high temperature exhibited inferior stability at a constant-current density working state. This result is mainly attributed to the adverse impact of the annealing process at high temperatures on the catalytic activity, in terms of decreasing the active surface area due to the aggregation effect and decreasing the intrinsic activity due to the formation of a highly crystalline structure. The inferior catalytic activity caused by the adverse impact can induce a large working voltage, which can accelerate the catalyst degradation via a positive feedback mechanism (PFM) beneath the electrocatalytic system consisting of 'catalytic activity-electrocatalytic performance (working voltage)-aging'. Besides, the influences of Cl residue on the catalytic activity and stability of the as-prepared IrO2/TiO2 were also investigated by substituting a Cl-free precursor using IrCl3 (IrO2/TiO2-Cl). It presented slightly inferior initial oxygen evolution reaction (OER) electrocatalytic performance to that using a Cl-free precursor, perhaps due to the strong adsorption of Cl residue on IrO2 nanoparticles. However, the stability of the as-prepared IrO2/TiO2-Cl deteriorates significantly in chronopotentiometric measurement probably due to the PFM. Consequen
Assessment of vegetation characteristics plays an important role in monitoring ecosystem health and restoration status, and it is necessary to consider the response characteristics of vegetation assessment indicator (...
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Assessment of vegetation characteristics plays an important role in monitoring ecosystem health and restoration status, and it is necessary to consider the response characteristics of vegetation assessment indicator (VAI) to multidimensional landscape structure. Therefore, this research constructed a framework for analyzing landscape structure from two dimensions of landscape element and landscape pattern, selected fractional vegetation cover (FVC) and net primary productivity (NPP) as VAI, determined the response degree and spatial correlation of VAI to landscape structure by using geographical detector and bivariate Moran's index, and finally obtained the change threshold of VAI based on the constraints of landscape pattern by building a cubic polynomial. FVC and NPP were significantly higher from 2001 to 2021, with the expansion of the high-value areas. Cropland and woodland were the dominant landscape elements. The spatial explanatory power of landscape element for VAI was better than that of landscape pattern characteristics, while the combined factors in landscape structure all explained VAI better than univariate. The response of FVC to landscape structure was more significant compared to NPP. The high value areas of FVC tended to occur in natural landscape elements. FVC showed spatial correlation and clustering characteristics with both PD and LPI. One or more thresholds existed in the response of FVC to changes in landscape pattern. The research results have important reference value in the optimization of landscape structure and vegetation restoration, and can provide practical guidance for the sustainable development of the ecosystem.
Anisotropic composite valves that approximate natural heart valves are essential for the successful construction of tissue-engineered heart valves. In this work, anisotropic nylon (polyamides, PA) fiber membranes were...
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Anisotropic composite valves that approximate natural heart valves are essential for the successful construction of tissue-engineered heart valves. In this work, anisotropic nylon (polyamides, PA) fiber membranes were prepared via electrospinning and further composited with thermoplastic polyurethane (TPU) by the impregnation method to obtain anisotropic PA/TPU composite valves. Young's modulus of the PA/TPU composite valves in the axial and radial directions along the fibers was 85.07 +/- 4.22 MPa and 28.72 +/- 1.16 MPa, respectively. The anisotropic PA/TPU composite valve exhibited excellent anisotropy, and its anisotropy ratio was 3.03, which was close to that of natural valves. Besides, the anisotropic PA/TPU composite valve exhibits high transparency (similar to 87%). The in vitro experiments revealed that anisotropic PA/TPU composite valves have better resistance to calcification and good blood compatibility compared with anisotropic nylon fiber membranes. Moreover, the hydrophilicity presented by the anisotropic PA/TPU composite valve reduced the adhesion of calcified particles. The good anticoagulant properties exhibited by the anisotropic PA/TPU composite valve effectively reduced the formation of thrombus after implantation. Cellular experiments and subcutaneous implantation experiments in rats showed that anisotropic PA/TPU composite valves exhibit cellular nontoxicity and good biocompatibility, contributing to cellular differentiation and growth. This preparation method has great potential in preparing anisotropic composite valves.
In recent years, because of a booming development of the snail rice noodles industry, investigations of Liuzhou Quality Inspection and Testing research Centre have revealed many snail rice noodle products in the marke...
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In recent years, because of a booming development of the snail rice noodles industry, investigations of Liuzhou Quality Inspection and Testing research Centre have revealed many snail rice noodle products in the market contain adulterated snail meat ingredients. Therefore, we developed a real-time fluorescence PCR assay for the rapid identification of snail meat components in snail rice noodles. The 16S ribosomal RNA genes of Cipangopaludina and Bellamya used as target genes for TaqMan real-time fluorescence PCR were designed. The assay for the detection of snail meat is highly specific, and the detection limit is 0.05% snail meat (w/w). When the assay was applied to commercially available snail rice noodle soups, the samples that contained snail meat tested positive, whereas none of the samples that did not contain snail meat yielded amplification curves. The assay allows rapid and efficient authenticity screening of snail meat components in rice noodles.
The use of microjoule high pulse repetition frequency (PRF) lasers as excitation sources is an important direction in the miniaturisation of laser-induced breakdown spectroscopy (LIBS) instruments. However, high PRF L...
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The use of microjoule high pulse repetition frequency (PRF) lasers as excitation sources is an important direction in the miniaturisation of laser-induced breakdown spectroscopy (LIBS) instruments. However, high PRF LIBS is sensitive to experimental parameters, and the relationship between the experimental parameters and the spectral intensity of high PRF LIBS is less studied. In this work, we present a model based on Gaussian spot overlapping ablation with aluminium alloys as samples. After the index values have been collected in the non-motion state, the model derivation formula can be used to calculate the intensity of the spectral peaks under any proposed experimental parameters in the motion state. The experimental results show that the mean relative error (MRE) between the measured and predicted values of spectral peak intensity is <= 0.15 under different experimental parameters, and this result proves the validity of the model in predicting the spectral peak intensity. Meanwhile, we used 5 standard aluminium alloy samples to construct the standard curves of measured and predicted values under different experimental parameters. The experimental results show that the MRE between the measured and predicted values is <= 0.15, and the two standard curves fitted with the measured and predicted values have a high similarity with an average R2 >= 0.85. This study is expected to provide a universally applicable and efficient method for the quantitative analysis of high PRF LIBS in different application scenarios.
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