Magnetic Nanoscaled Fe₃O₄/CeO₂ Composite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of 4‑Chlorophenol

Magnetic nanoscaled Fe₃O₄/CeO₂ composite was prepared by the impregnation method and characterized as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation. The catalytic activity was evaluated in view of the effects of various processes, pH value, catalyst addition, hydrogen peroxide (H₂O₂) concentration, and temperature, and the pseudo-first-order kinetic constant of 0.11 min^–1 was obtained for 4-CP degradation at 30 °C and pH 3.0 with 30 mM H₂O₂, 2.0 g L^–1 Fe₃O₄/CeO₂, and 0.78 mM 4-CP. The high utilization efficiency of H₂O₂, calculated as 79.2%, showed a promising application of the catalyst in the oxidative degradation of organic pollutants. The reusability of Fe₃O₄/CeO₂ composite was also investigated after six successive runs. On the basis of the results of metal leaching, the effects of radical scavengers, intermediates determination, and X-ray photoelectron spectroscopic (XPS) analysis, the dissolution of Fe₃O₄ facilitated by CeO₂ played a significant role, and 4-CP was decomposed mainly by the attack of hydroxyl radicals (•OH), including surface-bound •OH_ads generated by the reaction of Fe²⁺ and Ce³⁺ species with H₂O₂ on the catalyst surface, and •OH_free in the bulk solution mainly attributed to the leaching of Fe

Magnetic Nanoscaled Fe₃O₄/CeO₂ Composite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of 4‑Chlorophenol

Magnetic nanoscaled Fe₃O₄/CeO₂ composite was prepared by the impregnation method and characterized as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation. The catalytic activity was evaluated in view of the effects of various processes, pH value, catalyst addition, hydrogen peroxide (H₂O₂) concentration, and temperature, and the pseudo-first-order kinetic constant of 0.11 min^–1 was obtained for 4-CP degradation at 30 °C and pH 3.0 with 30 mM H₂O₂, 2.0 g L^–1 Fe₃O₄/CeO₂, and 0.78 mM 4-CP. The high utilization efficiency of H₂O₂, calculated as 79.2%, showed a promising application of the catalyst in the oxidative degradation of organic pollutants. The reusability of Fe₃O₄/CeO₂ composite was also investigated after six successive runs. On the basis of the results of metal leaching, the effects of radical scavengers, intermediates determination, and X-ray photoelectron spectroscopic (XPS) analysis, the dissolution of Fe₃O₄ facilitated by CeO₂ played a significant role, and 4-CP was decomposed mainly by the attack of hydroxyl radicals (•OH), including surface-bound •OH_ads generated by the reaction of Fe²⁺ and Ce³⁺ species with H₂O₂ on the catalyst surface, and •OH_free in the bulk solution mainly attributed to the leaching of Fe

Discrepant Catalytic Activity of Biochar-Based Fe and Co Homonuclear and Heteronuclear Diatomic Catalysts for Activating Peroxymonosulfate to Degrade Emerging Pollutants

In this study, biochar-based Fe and Co homonuclear (DAC–Fe–Co) and heteronuclear (DAC-Fe/Co) diatomic catalysts were first prepared via controlling the ligands of Fe and Co, and used to activate peroxymonosulfate (PMS) for the degradation of emerging organic pollutants, such as sulfamethoxazole (SMX), bisphenol A, phenol, atrazine, and nitrobenzene. The results showed that acid pretreatment of biochar was necessary for biochar to synthesize atomic catalysts. The DAC-Fe/Co had higher contents of Fe and Co than DAC–Fe–Co, but lower catalytic activity, in which the SMX first-order kinetics rate constant for DAC–Fe–Co was 4.1 times higher than that for DAC-Fe/Co, achieving 0.32 min–1. DAC–Fe–Co and DAC-Fe/Co could activate PMS to produce similar reactive species, including radicals and nonradicals. But DAC–Fe–Co produced a higher concentration of radicals than DAC-Fe/Co. The density functional theory (DFT) calculation indicated that compared to DAC-Fe/Co, DAC–Fe–Co had a higher adsorption capacity for PMS (−7.90 eV) and lower energy barrier for the regeneration of Fe (−1.20 eV) and Co (−1.16 eV) active sites. The enhanced regeneration of Fe and Co active sites promoted the formation of radicals, which explained the faster SMX removal rate in the system of DAC–Fe–Co/PMS than DAC-Fe/Co/PMS. The DAC–Fe–Co/PMS system exhibited high resistance to inorganic anions and showed excellent catalytic stability in the cycling experiments. This study provides insight into the discrepant catalytic activity of homonuclear and heteronuclear diatomic catalysts for PMS activation to degrade emerging organic contaminants, and offers a new way to prepare the homonuclear diatomic catalyst

Effect of Pore Size Distribution of Carbon Matrix on the Performance of Phosphorus@Carbon Material as Anode for Lithium-Ion Batteries

Phosphorus@carbon composites are alternative anode materials for lithium-ion batteries due to their high specific capacity. Serving as a conductive and buffer matrix, the carbon substrate is important to the performance of the composite. Our results exhibit that the electrochemical performances of phosphorus@carbon composites could be significantly enhanced by pore size distributions of the carbon matrix. The initial Coulombic efficiency of phosphorus@YP-50F reaches 80% and the capacity remains stable at 1370 mAh g^–1 after 100 cycles at 300 mA g^–1. The work may provide a general strategy for designing or selecting the optimal carbon matrix for phosphorus@carbon performance, and pave the way to practical application in lithium-ion batteries

DataSheet_2_RAAWC-UNet: an apple leaf and disease segmentation method based on residual attention and atrous spatial pyramid pooling improved UNet with weight compression loss.zip

IntroductionEarly detection of leaf diseases is necessary to control the spread of plant diseases, and one of the important steps is the segmentation of leaf and disease images. The uneven light and leaf overlap in complex situations make segmentation of leaves and diseases quite difficult. Moreover, the significant differences in ratios of leaf and disease pixels results in a challenge in identifying diseases.MethodsTo solve the above issues, the residual attention mechanism combined with atrous spatial pyramid pooling and weight compression loss of UNet is proposed, which is named RAAWC-UNet. Firstly, weights compression loss is a method that introduces a modulation factor in front of the cross-entropy loss, aiming at solving the problem of the imbalance between foreground and background pixels. Secondly, the residual network and the convolutional block attention module are combined to form Res_CBAM. It can accurately localize pixels at the edge of the disease and alleviate the vanishing of gradient and semantic information from downsampling. Finally, in the last layer of downsampling, the atrous spatial pyramid pooling is used instead of two convolutions to solve the problem of insufficient spatial context information.ResultsThe experimental results show that the proposed RAAWC-UNet increases the intersection over union in leaf and disease segmentation by 1.91% and 5.61%, and the pixel accuracy of disease by 4.65% compared with UNet.DiscussionThe effectiveness of the proposed method was further verified by the better results in comparison with deep learning methods with similar network architectures.</p

DataSheet_1_RAAWC-UNet: an apple leaf and disease segmentation method based on residual attention and atrous spatial pyramid pooling improved UNet with weight compression loss.pdf

IntroductionEarly detection of leaf diseases is necessary to control the spread of plant diseases, and one of the important steps is the segmentation of leaf and disease images. The uneven light and leaf overlap in complex situations make segmentation of leaves and diseases quite difficult. Moreover, the significant differences in ratios of leaf and disease pixels results in a challenge in identifying diseases.MethodsTo solve the above issues, the residual attention mechanism combined with atrous spatial pyramid pooling and weight compression loss of UNet is proposed, which is named RAAWC-UNet. Firstly, weights compression loss is a method that introduces a modulation factor in front of the cross-entropy loss, aiming at solving the problem of the imbalance between foreground and background pixels. Secondly, the residual network and the convolutional block attention module are combined to form Res_CBAM. It can accurately localize pixels at the edge of the disease and alleviate the vanishing of gradient and semantic information from downsampling. Finally, in the last layer of downsampling, the atrous spatial pyramid pooling is used instead of two convolutions to solve the problem of insufficient spatial context information.ResultsThe experimental results show that the proposed RAAWC-UNet increases the intersection over union in leaf and disease segmentation by 1.91% and 5.61%, and the pixel accuracy of disease by 4.65% compared with UNet.DiscussionThe effectiveness of the proposed method was further verified by the better results in comparison with deep learning methods with similar network architectures.</p

Clinically Approved Ferric Maltol: A Potent Nanozyme with Added Effect for High-Efficient Catalytic Disinfection

Nanozyme has been proven to be an attractive and promising candidate to alleviate the current pressing medical problems. However, the unknown clinical safety and limited function beyond the catalysis of the most reported nanozymes cannot promise an ideal therapeutic outcome in further clinical application. Herein, we find that ferric maltol (FM), a clinically approved iron supplement synthesized through a facile scalable method, exhibits excellent peroxidase-like activity than natural horseradish peroxidase-like (HRP) and commonly reported Fe-based nanozymes, and also shows high antibacterial performance for methicillin-resistant Staphylococcus aureus (MRSA) elimination (100%) and wound disinfection. In addition, with added effects inherited from contained maltol, FM can accelerate skin barrier recovery. Therefore, the exploration of FM as a safe and desired nanozyme provides a timely alternative to current antibiotic therapy against drug-resistant bacteria

Can the digital economy address the loss of green development efficiency due to resource mismatch? Evidence from China’s land transaction markets

Land is the driving force of economic growth, but the proliferation of industrial land has resulted in wasted land resources, impaired economic efficiency, and ecological damage in China. Currently, the digital economy is transforming China’s economic growth model. Exploring the corrective mechanisms of the digital economy for land resource mismatch can contribute to efficient economic growth. Using a sample of Chinese prefecture-level cities from 2007–2019, we employ a spatial Durbin model to explore the impact of land resource mismatch on green development efficiency (GDE) in the context of the digital economy, which is critical to rational planning, utilization, and regulation of land resources. The findings show that (1) land resource mismatch inhibits GDE, and the crowding-out, structural inhibition, and agglomeration economy dilution effect are primary influencing mechanisms. (2) A local land resource mismatch harms GDE in neighboring areas. (3) The digital economy has a positive moderating effect on land resource mismatch and GDE. (4) Land resource mismatch reduces GDE in the eastern and central regions; the moderating effect of the digital economy exists only in the eastern region. Finally, this study proposes comprehensive and complete countermeasures to correct the land resource mismatch and its influence channels and enhance the construction of the digital economy. The conclusions of this study provide specific theoretical contributions to promote the spatial allocation efficiency of land resources, promote green and efficient economic development, and stimulate and release the dividends of the digital economy.</p

Crystal Orientation Tuning of LiFePO₄ Nanoplates for High Rate Lithium Battery Cathode Materials

We report the crystal orientation tuning of LiFePO₄ nanoplates for high rate lithium battery cathode materials. Olivine LiFePO₄ nanoplates can be easily prepared by glycol-based solvothermal process, and the largest crystallographic facet of the LiFePO₄ nanoplates, as well as so-caused electrochemical performances, can be tuned by the mixing procedure of starting materials. LiFePO₄ nanoplates with crystal orientation along the <i>ac</i> facet and <i>bc</i> facet present similar reversible capacities of around 160 mAh g^–1 at 0.1, 0.5, and 1 C-rates but quite different ones at high C-rates. The former delivers 156 mAh g^–1 and 148 mAh g^–1 at 5 C-rate and 10 C-rate, respectively, while the latter delivers 132 mAh g^–1 and only 28 mAh g^–1 at 5 C-rate and 10 C-rate, respectively, demonstrating that the crystal orientation plays important role for the performance of LiFePO₄ nanoplates. This paves a facile way to prepare high performance LiFePO₄ nanoplate cathode material for lithium ion batteries

Nitrogen-Enriched Hierarchically Porous Carbons Prepared from Polybenzoxazine for High-Performance Supercapacitors

Nitrogen-enriched hierarchically porous carbons (HPCs) were synthesized from a novel nitrile-functionalized benzoxazine based on benzoxazine chemistry using a soft-templating method and a potassium hydroxide (KOH) chemical activation method and used as electrode materials for supercapacitors. The textural and chemical properties could be easily tuned by adding a soft template and changing the activation temperature. The introduction of the soft-templating agent (surfactant F127) resulted in the formation of mesopores, which facilitated fast ionic diffusion and reduced the internal resistance. The micropores of HPCs were extensively developed by KOH activation to provide large electrochemical double-layer capacitance. As the activation temperature increased from 600 to 800 °C, the specific surface area of nitrogen-enriched carbons increased dramatically, micropores were enlarged, and more meso/macropores were developed, but the nitrogen and oxygen content decreased, which affected the electrochemical performance. The sample HPC-800 activated at 800 °C possesses a high specific surface area (1555.4 m² g^–1), high oxygen (10.61 wt %) and nitrogen (3.64 wt %) contents, a hierarchical pore structure, a high graphitization degree, and good electrical conductivity. It shows great pseudocapacitance and the largest specific capacitance of 641.6 F g^–1 at a current density of 1 A g^–1 in a 6 mol L^–1 KOH aqueous electrolyte when measured in a three-electrode system. Furthermore, the HPC-800 electrode exhibits excellent rate capability (443.0 F g^–1 remained at 40 A g^–1) and good cycling stability (94.3% capacitance retention over 5000 cycles)