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Authors = Daijun Yang

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15 pages, 2424 KiB  
Article
Cyanuric Chloride with the s-Triazine Ring Fabricated by Interfacial Polymerization for Acid-Resistant Nanofiltration
by Zhuangzhuang Tian, Yun Yin, Jiandong Wang, Xiuling Ao, Daijun Liu, Yang Jin, Jun Li and Jianjun Chen
Membranes 2025, 15(8), 231; https://doi.org/10.3390/membranes15080231 - 1 Aug 2025
Viewed by 262
Abstract
Nanofiltration (NF) is considered a competitive purification method for acidic stream treatments. However, conventional thin-film composite NF membranes degrade under acid exposures, limiting their applications in industrial acid treatment. For example, wet-process phosphoric acid contains impurities of multivalent metal ions, but NF membrane [...] Read more.
Nanofiltration (NF) is considered a competitive purification method for acidic stream treatments. However, conventional thin-film composite NF membranes degrade under acid exposures, limiting their applications in industrial acid treatment. For example, wet-process phosphoric acid contains impurities of multivalent metal ions, but NF membrane technologies for impurity removal under harsh conditions are still immature. In this work, we develop a novel strategy of acid-resistant nanofiltration membranes based on interfacial polymerization (IP) of polyethyleneimine (PEI) and cyanuric chloride (CC) with the s-triazine ring. The IP process was optimized by orthogonal experiments to obtain positively charged PEI-CC membranes with a molecular weight cut-off (MWCO) of 337 Da. We further applied it to the approximate industrial phosphoric acid purification condition. In the tests using a mixed solution containing 20 wt% P2O5, 2 g/L Fe3+, 2 g/L Al3+, and 2 g/L Mg2+ at 0.7 MPa and 25 °C, the NF membrane achieved 56% rejection of Fe, Al, and Mg and over 97% permeation of phosphorus. In addition, the PEI-CC membrane exhibited excellent acid resistance in the 48 h dynamic acid permeation experiment. The simple fabrication procedure of PEI-CC membrane has excellent acid resistance and great potential for industrial applications. Full article
(This article belongs to the Special Issue Nanofiltration Membranes for Precise Separation)
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20 pages, 18100 KiB  
Article
Targeting p-FGFR1Y654 Enhances CD8+ T Cells Infiltration and Overcomes Immunotherapy Resistance in Esophageal Squamous Cell Carcinoma by Regulating the CXCL8–CXCR2 Axis
by Hong Luo, Liwei Wang, Hui Gao, Daijun Zhou, Yu Qiu, Lijia Yang, Jing Li, Dan Du, Xiaoli Huang, Yu Zhao, Zhongchun Qi, Yue Zhang, Xuemei Huang, Lihan Sun, Tao Xu and Dong Li
Biomedicines 2025, 13(7), 1667; https://doi.org/10.3390/biomedicines13071667 - 8 Jul 2025
Viewed by 507
Abstract
Background: Esophageal squamous cell carcinoma (ESCC) is a fatal malignant tumor. Several studies have demonstrated that immune checkpoint inhibitors can provide clinical benefits to patients with ESCC. However, the single-agent efficacy of these agents remains limited. Although combination therapies (e.g., radiotherapy, chemotherapy) can [...] Read more.
Background: Esophageal squamous cell carcinoma (ESCC) is a fatal malignant tumor. Several studies have demonstrated that immune checkpoint inhibitors can provide clinical benefits to patients with ESCC. However, the single-agent efficacy of these agents remains limited. Although combination therapies (e.g., radiotherapy, chemotherapy) can help to overcome immunotherapy resistance in ESCC, their severe side effects limit clinical application. This study aimed to explore new resistance mechanisms to immunotherapy in ESCC and identify novel molecular targets to overcome immunotherapy resistance. Methods: We employed immunohistochemistry staining to examine the p-FGFR1Y654 in tumor samples obtained from 103 patients with ESCC, in addition to evaluating CD8+ T cell infiltration. In vitro expression, western blotting, CCK-8, 5-bromo-2′-deoxyuridine incorporation assays, and migration assays were used to confirm the impact of AZD4547 on p-FGFR1Y654 expression and the proliferation and migration in ESCC cell lines. Through RNA sequencing analysis, databases such as the Cancer Genome Atlas (TCGA) and Gene Set Cancer Analysis (GSCA), and the reconstruction of transgenic mice using the humanized immune system, we validated the correlation between the expression of p-FGFR1Y654 and CD8+ T cell infiltration. We also explored how p-FGFR1Y654 recruits myeloid-derived suppressor cells (MDSCs) through the CXCL8–CXCR2 axis to suppress the therapeutic efficacy of immunotherapy in ESCC. Finally, the tumor-suppressive effects of AZD4547 combined with immunotherapy were confirmed in vivo in tumor-bearing mice with a humanized immune system. Results: We found that the inhibition of p-FGFR1Y654 expression in ESCC can enhance CD8+ T cell infiltration by suppressing the CXCL8-–XCR2 recruitment of MDSCs. AZD4547, combined with immunotherapy, further promotes immunotherapeutic efficacy in ESCC. Conclusions: In conclusion, our study presents a promising model for combination therapy in ESCC immunotherapy. Full article
(This article belongs to the Section Immunology and Immunotherapy)
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18 pages, 6772 KiB  
Article
Integrated Multi-Omics Analysis Reveals the Regulatory Mechanism of Peanut Skin Procyanidins on Lipid Metabolism in High-Fat-Diet-Induced Obese Mice
by Jinxin Shen, Yi Zhou, Daijun Yang, Ruonan Liu, Xiaoling Zhu and Rui Liu
Nutrients 2025, 17(13), 2228; https://doi.org/10.3390/nu17132228 - 5 Jul 2025
Viewed by 563
Abstract
Background: Obesity-associated metabolic disorders represent a critical global health challenge, which necessitates innovative strategies targeting lipid metabolism. Peanut skin procyanidins (PSPs), abundant bioactive compounds derived from agricultural by-products, show potential in lipid regulation, but molecular mechanisms remain unclear. Methods: This study [...] Read more.
Background: Obesity-associated metabolic disorders represent a critical global health challenge, which necessitates innovative strategies targeting lipid metabolism. Peanut skin procyanidins (PSPs), abundant bioactive compounds derived from agricultural by-products, show potential in lipid regulation, but molecular mechanisms remain unclear. Methods: This study integrated hepatic metabolomics, network pharmacology, and gut microbiota analysis to systematically decipher the mechanisms for PSP to ameliorate high-fat diet (HFD)-induced lipid metabolism disorders. Results: PSP intervention significantly attenuated HFD-induced increases in LDL-C, TG, and TC levels and effectively mitigated hepatic lipid accumulation. Metabolomics revealed that PSP reshaped hepatic lipid dynamics by modulating glycerophospholipid, linoleic acid, arachidonic acid, tryptophan, and nitrogen metabolism. Subsequent network pharmacology identified PLA2G10, PLA2G5, PLA2G2A, and CYP1B1 as the core targets, and PSP could markedly suppress their HFD-induced overexpression. Furthermore, PSP selectively reshaped the gut microbiota, enriching beneficial genera such as Akkermansia and Bacteroides while reducing the abundance of harmful bacteria within Firmicutes. PICRUSt-based functional prediction indicated that PSP alters gut microbial glutamine synthetase activity. Conclusions: Mechanistically, PSP regulates lipid metabolism by downregulating PLA2G10, PLA2G5, PLA2G2A, and CYP1B1 expression, remodeling gut microbiota structure, and increasing hepatic glutamine level. These findings provide novel insights into value-added utilization of agricultural byproducts and development of targeted intervention strategies for metabolic diseases. Full article
(This article belongs to the Section Nutrition and Metabolism)
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26 pages, 26537 KiB  
Article
Contrastive Learning with Image Deformation and Refined NT-Xent Loss for Urban Morphology Discovery
by Chunliang Hua, Daijun Chen, Mengyuan Niu, Lizhong Gao, Junyan Yang and Qiao Wang
ISPRS Int. J. Geo-Inf. 2025, 14(5), 196; https://doi.org/10.3390/ijgi14050196 - 8 May 2025
Viewed by 682
Abstract
The traditional paradigm for studying urban morphology involves the interpretation of Nolli maps, using methods such as morphometrics and visual neural networks. Previous studies on urban morphology discovery have always been based on raster analysis and have been limited to the central city [...] Read more.
The traditional paradigm for studying urban morphology involves the interpretation of Nolli maps, using methods such as morphometrics and visual neural networks. Previous studies on urban morphology discovery have always been based on raster analysis and have been limited to the central city area. Raster analysis can lead to fragmented forms, and focusing only on the central city area ignores many representative urban forms in the suburbs and towns. In this study, a vast and complex dataset was applied to the urban morphology discovery based on the administrative community or village boundary, and a new image deformation pipeline was proposed to enhance the morphological characteristics of building groups. This allows visual neural networks to focus on extracting the morphological characteristics of building groups. Additionally, the research on urban morphology often uses unsupervised learning, which means that the learning process is difficult to control. Therefore, we refined the NT-Xent loss so that it can integrate morphological indicators. This improvement allows the visual neural network to “recognize” the similarity of samples during optimization. By defining the similarity, we can guide the network to bring samples closer or move them farther apart based on certain morphological indicators. Three Chinese cities were used for our testing. Representative urban types were identified, particularly some types located at the urban fringe. The data analysis demonstrated the effectiveness of our image deformation pipeline and loss function, and the sociological analysis illustrated the unique urban functions of these urban types. Full article
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20 pages, 22665 KiB  
Article
The 3D Multifractal Characteristics of Urban Morphology in Chinese Old Districts
by Chenyang Zhang, Junyan Yang, Xinzhe Liu, Dian Shao, Zhonghu Zhang, Zhihan Zhang, Haocheng Sun, Yuyue Huang, Daijun Chen and Xun Zhang
Fractal Fract. 2025, 9(3), 195; https://doi.org/10.3390/fractalfract9030195 - 20 Mar 2025
Viewed by 548
Abstract
The compactness, diversity, and nested structures of the old districts in Chinese cities, in terms of their three-dimensional (3D) morphology, are particularly distinctive. However, existing multifractal measurement methods are insufficient in revealing these 3D structures. This paper introduces a 3D multifractal approach based [...] Read more.
The compactness, diversity, and nested structures of the old districts in Chinese cities, in terms of their three-dimensional (3D) morphology, are particularly distinctive. However, existing multifractal measurement methods are insufficient in revealing these 3D structures. This paper introduces a 3D multifractal approach based on generalized dimension and Rényi entropy. In particular, a local indicator τq(h) is introduced for the analysis of the mapping of 3D units, with the Nanjing Old City serving as a case study. The results indicate the following: (1) The significant fractal characteristics of the Nanjing Old City, with a capacity dimension value of 2.344, indicating its limited 3D spatial occupancy. (2) The fluctuating generalized dimension spectrum ranges from 2.241 to 2.660, which differs from previous studies, suggesting that the 3D morphology does not exhibit typical multifractal characteristics. (3) The 3D map matrix reveals a fragmented open space system, a heterogeneous distribution of high-rise buildings, and cross-scale variations in morphological heterogeneity. This 3D multifractal method aids urban planners in assessing critical issues such as the fragmentation, crowding, and excessive heterogeneity of urban morphology, providing a spatial coordination and scaling of these issues through the 3D map matrix and enhancing the discussion of the broader mechanisms influencing morphological characteristics. Full article
(This article belongs to the Section Geometry)
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18 pages, 16125 KiB  
Article
Research on the Correlation between the Dynamic Distribution Patterns of Urban Population Density and Land Use Morphology Based on Human–Land Big Data: A Case Study of the Shanghai Central Urban Area
by Yi Shi, Yi Zheng, Daijun Chen, Junyan Yang, Yue Cao and Ao Cui
Land 2024, 13(10), 1547; https://doi.org/10.3390/land13101547 - 24 Sep 2024
Cited by 5 | Viewed by 2112
Abstract
The dynamic distribution of urban population density and the interaction with land use elements involve mutual constraints and guidance. However, in the existing research on the relationship between urban population density and land use, the discussion on the distribution patterns of urban population [...] Read more.
The dynamic distribution of urban population density and the interaction with land use elements involve mutual constraints and guidance. However, in the existing research on the relationship between urban population density and land use, the discussion on the distribution patterns of urban population density typically spans long time periods and uses large spatial units, lacking analysis of the dynamic changes in population density within high granularity land parcels over a day. In studies related to the urban built environment, the complex relationships between different-dimensional land use elements and the dynamic distribution of population density also need further exploration. To address these bottlenecks, this study takes Shanghai’s central urban area as an example. Based on 24 h mobile signaling data on weekdays, weekends, and typical holidays, as well as urban land use data, clustering algorithms are used to summarize patterns of dynamic population density distribution. Pearson correlation analysis is then employed to study the correlation between dynamic population density distribution patterns and different land use elements. The results indicate that various urban land use factors such as locational centrality, functional diversity, transportation accessibility, compactness, and landscape quality have different impacts on the dynamic distribution of population density in spatial units, and the dynamic distribution patterns of population density in different land use types also vary. This research contributes to guiding the optimization of spatial quality and formulating planning and management measures that more effectively match construction intensity with population activity density. Full article
(This article belongs to the Special Issue A Livable City: Rational Land Use and Sustainable Urban Space)
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24 pages, 32512 KiB  
Article
Enhancing Urban–Rural Integration in China: A Comparative Case Study of Introducing Small Rural Industries in Huangyan-Taizhou
by Huang Huang, Daijun Song, Liyao Wang, Guiqing Yang, Yizheng Wang, Liyuan Fei and Ava Lynam
Land 2024, 13(7), 946; https://doi.org/10.3390/land13070946 - 28 Jun 2024
Cited by 4 | Viewed by 3334
Abstract
Strengthening urban–rural linkages (URLs) has been proposed by UN-Habitat within the framework of ‘Sustainable Development Goals (SDGs)’ to narrow down urban–rural differences via shaping new urban–rural relationships. Like URL, the aim of urban–rural integration (URI) has been promoted by the Chinese government since [...] Read more.
Strengthening urban–rural linkages (URLs) has been proposed by UN-Habitat within the framework of ‘Sustainable Development Goals (SDGs)’ to narrow down urban–rural differences via shaping new urban–rural relationships. Like URL, the aim of urban–rural integration (URI) has been promoted by the Chinese government since 2019 to address existing urban–rural divides. This concept underlines the ‘rural revitalisation’ strategy and emphasises a two-way flow of urban–rural development factors. Introducing and upgrading ‘appropriate’ rural industries is crucial to stimulate and facilitate the circulation of urban–rural development factors. This research studied three neighbouring villages, situated in urban–rural interface areas in Huangyan-Taizhou, China, each driven by different types of small industries supported by URI. It analyses the impact of small rural industries on the flow of development factors between urban and rural areas. The results showed that small-scale rural industries have been enhanced URL by decreasing urban–rural differences by creating new job opportunities to attract an in-flow population, increasing investments, and upgrading public services and infrastructure. Indigenous industries demonstrated lower profitability but exhibited greater resilience compared to industries linked to global production chains and rural tourism. Thus, this study demonstrates the imperative to carefully consider the opportunities and potential risks associated with pursuing strategies of URI through rural industry development. By providing empirical insights from URI projects in China, this study contributes to theoretical and policy dialogues concerning the concepts of both URL and URI by exploring the localization of SDGs. Furthermore, it offers valuable practical knowledge and experience for other global regions confronting similar challenges to urban and rural development. Full article
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13 pages, 6044 KiB  
Article
Preparation of ZnO Ultrasonic Transducer by Radio-Frequency Sputtering and Its Application in Bolt Preload Detection
by Yi Xu, Yanghui Jiang, Kai Tan, Wenrui Yang, Jie Lv, Daijun Deng, Dengguo Zheng, Changsheng Li, Jun Zhang and Bing Yang
Coatings 2024, 14(6), 718; https://doi.org/10.3390/coatings14060718 - 5 Jun 2024
Viewed by 1178
Abstract
Accurate detection of the preload force of tower crane bolts is of great significance for the stable and safe operation of the equipment. The method of contact ultrasonic detection of bolt preload has always been the focus of attention, which can realize rapid [...] Read more.
Accurate detection of the preload force of tower crane bolts is of great significance for the stable and safe operation of the equipment. The method of contact ultrasonic detection of bolt preload has always been the focus of attention, which can realize rapid in situ detection without damaging the parts. In order to improve the accuracy and convenience of ultrasonic measurement of bolt preload and meet the urgent needs of the actual industrial site for high-precision measurement of bolt preload, we propose to prepare ZnO piezoelectric coatings as functional layers for ultrasonic transducers using magnetron sputtering and deposit them directly on bolts. The growth behavior of the ZnO coatings is investigated by varying the sputtering power, sputtering gas pressure and target substrate distance, and the morphology, structure, and properties are characterized and analyzed. The ZnO piezoelectric coatings with high c-axis optimal growth orientation and excitation of ultrasonic longitudinal waves were finally obtained and verified to be effective and stable when applied to the bolts. Full article
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14 pages, 3014 KiB  
Article
The Piezocatalytic Degradation of Sulfadiazine by Lanthanum-Doped Barium Titanate
by Daijun Meng, Yuqi Xiang, Ziwei Yang, Hao Yuan, Liang Tang and Shiyang Li
Molecules 2024, 29(8), 1719; https://doi.org/10.3390/molecules29081719 - 10 Apr 2024
Cited by 5 | Viewed by 1846
Abstract
Piezocatalysis, a heterogeneous catalytic technique, leverages the periodic electric field changes generated by piezoelectric materials under external forces to drive carriers for the advanced oxidation of organic pollutants. Antibiotics, as emerging trace organic pollutants in water sources, pose a potential threat to animals [...] Read more.
Piezocatalysis, a heterogeneous catalytic technique, leverages the periodic electric field changes generated by piezoelectric materials under external forces to drive carriers for the advanced oxidation of organic pollutants. Antibiotics, as emerging trace organic pollutants in water sources, pose a potential threat to animals and drinking water safety. Thus, piezoelectric catalysis can be used to degrade trace organic pollutants in water. In this work, BaTiO3 and La-doped BaTiO3 were synthesized using an improved sol–gel–hydrothermal method and used as piezocatalytic materials to degrade sulfadiazine (SDZ) with ultrasound activation. High-crystallinity products with nano cubic and spherical morphologies were successfully synthesized. An initial concentration of SDZ ranging from 1 to 10 mg/L, a catalysis dosage range from 1 to 2.5 mg/mL, pH, and the background ions in the water were considered as influencing factors and tested. The reaction rate constant was 0.0378 min−1 under the optimum working conditions, and the degradation efficiency achieved was 89.06% in 60 min. La-doped BaTiO3 had a better degradation efficiency, at 14.98% on average, compared to undoped BaTiO3. Further investigations into scavengers revealed a partially piezocatalytic process for the degradation of SDZ. In summary, our work provides an idea for green environmental protection in dealing with new types of environmental pollution. Full article
(This article belongs to the Special Issue Advanced Oxidation Processes for Degradation of Antibiotics in Water)
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15 pages, 4432 KiB  
Article
Effects of Traditional Chinese Herbal Feed Additive on Production Performance, Egg Quality, Antioxidant Capacity, Immunity and Intestinal Health of Laying Hens
by Baiheng Liu, Ruyue Ma, Qinlin Yang, You Yang, Yuanjing Fang, Zhihong Sun and Daijun Song
Animals 2023, 13(15), 2510; https://doi.org/10.3390/ani13152510 - 3 Aug 2023
Cited by 24 | Viewed by 4490
Abstract
Chinese herbs have been used as feed additives in animal production. This study investigated the effects of a Chinese herbal feed-additive (TCM, which contained Elsholtzia ciliate, Atractylodes macrocephala, Punica granatum pericarpium, and Cyperus rotundus) on the production performance, egg [...] Read more.
Chinese herbs have been used as feed additives in animal production. This study investigated the effects of a Chinese herbal feed-additive (TCM, which contained Elsholtzia ciliate, Atractylodes macrocephala, Punica granatum pericarpium, and Cyperus rotundus) on the production performance, egg quality, antioxidant capacity, immunity, and intestinal health of Roman laying hens. A total of 720 28-week-old hens were randomly allotted to three groups with six replicates of forty hens each. The groups were fed a basal diet (CON group), a basal diet with 50 mg/kg zinc bacitracin (ABX group), or a basal diet with 400 mg/kg TCM (TCM group) for 56 days. The results showed that the TCM group increased egg production, egg mass, albumen height, and Haugh unit compared with the CON group (p < 0.05). There were no significant differences in egg weight, feed intake, feed conversion rate, and eggshell strength among all three groups (p > 0.05). Compared with the CON group, the TCM group enhanced the activities of glutathione peroxidase, total antioxidant capacity, and superoxide dismutase in serum and liver, and reduced malondialdehyde content (p < 0.05). The TCM also increased the levels of interleukin-2, interferon-γ, immunoglobulin A, immunoglobulin M, and immunoglobulin G, and decreased the levels of interleukin-6 and interleukin-8 compared with the CON group (p < 0.05). Furthermore, the TCM group increased jejunal goblet cell density and decreased ileal crypt depth and lymphocyte density compared with the CON group (p < 0.05). The results of 16S rRNA demonstrated that the TCM can change the diversity and composition of intestinal microbiota. At the phylum level, the abundance of Bacteroides increased while that of Firmicutes decreased in the TCM group (p > 0.05). At the genus level, the abundance of Lactobacillus, Rikenellaceae_RC9_gut_group, and Phascolarctobacterium increased while that of Bacteroides and unclassified_o__Bacteroidales decreased in the TCM group (p > 0.05). The effects of ABX were weaker than those of the TCM. In conclusion, the TCM has positive effects on production performance and the intestinal health of hens. Full article
(This article belongs to the Section Animal Nutrition)
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16 pages, 6844 KiB  
Article
Innovative Coating–Etching Method of Biocarrier Fabrication for Treating Wastewater with a Low C/N Ratio
by Ning Yu, Daijun Zhang, Yu Lei, Jianhui Wang, Yang Dong and Youpeng Chen
Polymers 2022, 14(15), 3010; https://doi.org/10.3390/polym14153010 - 25 Jul 2022
Cited by 2 | Viewed by 2092
Abstract
A novel method was used to fabricate the bio-carrier with both a high specific surface area and good compatibility. The results of monitoring the growth of biofilms at a low C/N ratio (0.83) showed that resulting carrier-PLA-cavity offered certain advantages for biofilm growth [...] Read more.
A novel method was used to fabricate the bio-carrier with both a high specific surface area and good compatibility. The results of monitoring the growth of biofilms at a low C/N ratio (0.83) showed that resulting carrier-PLA-cavity offered certain advantages for biofilm growth by providing an appropriate microenvironment for bacterial growth in wastewater treatment. The biofilm on carrier-PLA-cavity grew and updated faster than the naked-carrier. The biomass and thickness of biofilms growing on carrier-PLA-cavity were 10 kg/m3 and 500 μm, respectively. From the wastewater tests, 90% of the total nitrogen was removed via simultaneous nitrification and denitrification (SND) by the biofilm biomass attached to carrier-PLA-cavity, compared to 68% for the naked-carrier. The COD removal efficiency values of the carrier-PLA-cavity and naked-carrier were 94% and 86%, respectively. The microbial community analysis of carrier biofilms showed that Halomonas was the most abundant genus, and heterotrophic nitrification and denitrification were responsible for nitrogen removal in both reactors. Notably, this method does not require any complicated equipment or structural design. This novel method might be a promising strategy for fabricating biocarriers for treating wastewater with a low C/N ratio. Full article
(This article belongs to the Section Polymer Applications)
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17 pages, 3762 KiB  
Article
Influence of Degassing Treatment on the Ink Properties and Performance of Proton Exchange Membrane Fuel Cells
by Pengcheng Liu, Daijun Yang, Bing Li, Cunman Zhang and Pingwen Ming
Membranes 2022, 12(5), 541; https://doi.org/10.3390/membranes12050541 - 22 May 2022
Cited by 2 | Viewed by 5417
Abstract
Degradation occurs in catalyst inks because of the catalytic oxidation of the solvent. Identification of the generation process of impurities and their effects on the properties of HSC ink and LSC ink is crucial in mitigating them. In this study, gas chromatography-mass spectrometry [...] Read more.
Degradation occurs in catalyst inks because of the catalytic oxidation of the solvent. Identification of the generation process of impurities and their effects on the properties of HSC ink and LSC ink is crucial in mitigating them. In this study, gas chromatography-mass spectrometry (GC-MS) and cyclic voltammetry (CV) showed that oxidation of NPA and EA was the primary cause of impurities such as acetic acid, aldehyde, propionic acid, propanal, 1,1-dipropoxypropane, and propyl propionate. After the degassing treatment, the degradation of the HSC ink was suppressed, and the concentrations of acetic acid, propionic acid, and propyl propionate plummeted from 0.0898 wt.%, 0.00224 wt.%, and 0.00046 wt.% to 0.0025 wt.%, 0.0126 wt.%, and 0.0003 wt.%, respectively. The smaller particle size and higher zeta potential in the degassed HSC ink indicated the higher utilization of Pt, thus leading to optimized mass transfer in the catalyst layer (CL) during working conditions. The electrochemical performance test result shows that the MEA fabricated from the degassed HSC ink had a peak power density of 0.84 W cm−2, which was 0.21 W cm−2 higher than that fabricated from the normal HSC ink. However, the introduction of propionic acid in the LSC ink caused the Marangoni flux to inhibit the coffee ring effect and promote the uniform deposition of the catalyst. The RDE tests indicated that the electrode deposited from the LSC ink with propionic acid possessed a mass activity of 84.4 mA∙mgPt−1, which was higher than the 60.5 mA∙mgPt−1 of the electrode deposited from the normal LSC ink. Full article
(This article belongs to the Topic Electromaterials for Environment & Energy)
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24 pages, 5899 KiB  
Review
A Review of the Transition Region of Membrane Electrode Assembly of Proton Exchange Membrane Fuel Cells: Design, Degradation, and Mitigation
by Daijun Yang, Yongle Tan, Bing Li, Pingwen Ming, Qiangfeng Xiao and Cunman Zhang
Membranes 2022, 12(3), 306; https://doi.org/10.3390/membranes12030306 - 9 Mar 2022
Cited by 30 | Viewed by 8732
Abstract
As the core component of a proton exchange fuel cell (PEMFC), a membrane electrode assembly (MEA) consists of function region (active area), structure region, and transition region. Situated between the function and structure regions, the transition region influences the reliability and durability of [...] Read more.
As the core component of a proton exchange fuel cell (PEMFC), a membrane electrode assembly (MEA) consists of function region (active area), structure region, and transition region. Situated between the function and structure regions, the transition region influences the reliability and durability of the MEA. The degradation of the electrolyte membrane in this region can be induced by mechanical stress and chemical aggression. Therefore, prudent design, reliable and robust structure of the transition region can greatly help avoid early failure of MEAs. This review begins with the summarization of current structural concepts of MEAs, focusing on the transition region structures. It can be seen that aiming at better repeatability and robustness, partly or total integration of the materials in the transition region is becoming a development trend. Next the degradation problem at the transition region is introduced, which can be attributed to the hygro-thermal environment, free radical aggression, air pressure shock, and seal material decomposition. Finally, the mitigation approaches for the deterioration at this region are summarized, with a principle of avoiding the exposure of the membrane at the edge of the catalyst-coated membrane (CCM). Besides, durability test methods of the transition region are included in this review, among which temperature and humidity cycling are frequently used. Full article
(This article belongs to the Special Issue Membrane Electrode Assembly (MEA))
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19 pages, 4418 KiB  
Article
A High-Durability Graphitic Black Pearl Supported Pt Catalyst for a Proton Exchange Membrane Fuel Cell Stack
by Bing Li, Meng Xie, Kechuang Wan, Xiaolei Wang, Daijun Yang, Zhikun Liu, Tiankuo Chu, Pingwen Ming and Cunman Zhang
Membranes 2022, 12(3), 301; https://doi.org/10.3390/membranes12030301 - 7 Mar 2022
Cited by 9 | Viewed by 4066
Abstract
Graphitized black pearl (GBP) 2000 supported Pt nanoparticle catalysts is synthesized by a formic acid reduction method. The results of a half-cell accelerated degradation test (ADT) of two protocols and a single-cell ADT show that, Pt/GBP catalyst has excellent stability and durability compared [...] Read more.
Graphitized black pearl (GBP) 2000 supported Pt nanoparticle catalysts is synthesized by a formic acid reduction method. The results of a half-cell accelerated degradation test (ADT) of two protocols and a single-cell ADT show that, Pt/GBP catalyst has excellent stability and durability compared with commercial Pt/C. Especially, the survival time of Pt/GBP-membrane electrode assembly (MEA) reaches 205 min, indicating that it has better reversal tolerance. After the 1003-hour durability test, the proton exchange membrane fuel cell (PEMFC) stack with Pt/GBP presents a slow voltage degradation rate of 5.19% and 36 μV h−1 at 1000 mA cm−2. The durability of the stack is improved because of the durability and stability of the catalyst. In addition, the post morphology characterizations indicate that the structure and particle size of the Pt/GBP catalyst remain unchanged during the dynamic testing protocol, implying its better stability under dynamic load cycles. Therefore, Pt/GBP is a valuable and promising catalyst for PEMFC, and considered as an alternative to classical Pt/C. Full article
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18 pages, 7238 KiB  
Article
Temporal Information Extraction for Afforestation in the Middle Section of the Yarlung Zangbo River Using Time-Series Landsat Images Based on Google Earth Engine
by Hao Fu, Wei Zhao, Qiqi Zhan, Mengjiao Yang, Donghong Xiong and Daijun Yu
Remote Sens. 2021, 13(23), 4785; https://doi.org/10.3390/rs13234785 - 25 Nov 2021
Cited by 6 | Viewed by 3038
Abstract
Afforestation is one of the most efficient ways to control land desertification in the middle section of the Yarlung Zangbo River (YZR) valley. However, the lack of a quantitative way to record the planting time of artificial forest (AF) constrains further management for [...] Read more.
Afforestation is one of the most efficient ways to control land desertification in the middle section of the Yarlung Zangbo River (YZR) valley. However, the lack of a quantitative way to record the planting time of artificial forest (AF) constrains further management for these forests. The long-term archived Landsat images (including the Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI)) provide a good opportunity to capture the temporal change information about AF plantations. Under the condition that there would be an abrupt increasing trend in the normalized difference vegetation index (NDVI) time-series curve after afforestation, and this characteristic can be thought of as the indicator of the AF planting time. To extract the indicator, an algorithm based on the Google Earth Engine (GEE) for detecting this trend change point (TCP) on the maximum NDVI time series within the growing season (May to September) was proposed. In this algorithm, the time-series NDVI was initially smoothed and segmented into two subspaces. Then, a trend change indicator Sdiff was calculated with the difference between the fitting slopes of the subspaces before and after each target point. A self-adaptive method was applied to the NDVI series to find the right year with the maximum TCP, which is recorded as the AF planting time. Based on the proposed method, the AF planting time of the middle section of the YZR valley from 1988 to 2020 was derived. The detected afforestation temporal information was validated by 222 samples collected from the field survey, with a Pearson correlation coefficient of 0.93 and a root mean squared error (RMSE) of 2.95 years. Meanwhile, the area distribution of the AF planted each year has good temporal consistency with the implementation of the eco-reconstruction project. Overall, the study provides a good way to map AF planting times that is not only helpful for sustainable management of AF areas but also provides a basis for further research on the impact of afforestation on desertification control. Full article
(This article belongs to the Special Issue Remote Sensing of Ecosystems)
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