Thermally crosslinked sulfonated polybenzimidazole membranes and their performance in high temperature polymer electrolyte fuel cells

Nambi Krishnan, N.,Konovalova, Anastasiia,Aili, David,Li, Qingfeng,Park, Hyun Seo,Jang, Jong Hyun,Kim, Hyoung-Juhn,Henkensmeier, Dirk Elsevier 2019 Journal of membrane science Vol.588 No.-

<P><B>Abstract</B></P> <P>The degradation pathway of phosphoric acid doped polybenzimidazole membranes in high temperature polymer electrolyte membrane fuel cells depends on the acid contents. If it is high, creep is discussed as the main reason. If it is low (membranes prepared by solvent evaporation and post-doping), the main cause may be loss of acid due to evaporation. The net transport of acid to the anode side at high current densities should also lead to local softening of the membrane, which could be mitigated by crosslinking the membrane.</P> <P>Here we show that sulfonated <I>para</I>-polybenzimidazole membranes can be stabilized by curing at 350 °C. In contrast to <I>meta</I>-polybenzimidazole and sulfonated <I>para</I>-polybenzimidazole, crosslinked sulfonated <I>para</I>-polybenzimidazole is insoluble in dimethylacetamide at room temperature and phosphoric acid at 160 °C. At 160 °C and 5% relative humidity the conductivity of crosslinked sulfonated <I>para</I>-polybenzimidazole and <I>meta</I>-polybenzimidazole is 214 mS cm<SUP>−1</SUP> and 147 mS cm<SUP>−1</SUP>, respectively. At 600 mA cm<SUP>−</SUP> <SUP>2</SUP>, the voltage decay rate is 16 μV h<SUP>−1</SUP>, much lower than published for commercial <I>meta</I>-polybenzimidazole (308 μV h<SUP>−1</SUP>). Furthermore, the average voltage at 600 mA cm<SUP>−</SUP> <SUP>2</SUP> is 523 mV, while a previously published cured <I>meta</I>-polybenzimidazole membrane only reaches 475 mV.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sulfonated <I>para</I>-PBI is covalently crosslinked by heating. </LI> <LI> Membranes are stable in DMAc at 27 °C and in 85 wt% phosphoric acid at 160 °C. </LI> <LI> Non-crosslinked sulfonated <I>para</I>-PBI and <I>meta</I>-PBI dissolve under these conditions. </LI> <LI> Conductivity is 44% higher than for <I>meta</I>-PBI. </LI> <LI> Fuel cell performance is stable; test time was 2100 h, half of that at 600 mA/cm<SUP>2</SUP> </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Performance optimization of flexible a-Si:H solar cells with nanotextured plasmonic substrate by tuning the thickness of oxide spacer layer

Xiao, Huapeng,Wang, Jun,Huang, Hongtao,Lu, Linfeng,Lin, Qingfeng,Fan, Zhiyong,Chen, Xiaoyuan,Jeong, Chaehwan,Zhu, Xufei,Li, Dongdong Elsevier 2015 Nano energy Vol.11 No.-

<P><B>Abstract</B></P> <P>Plasmonic thin film solar cells deposited on periodically textured photonic crystal substrates have been extensively studied since the substantially enhanced light absorption. The reduction of parasitic absorption losses in the metal and spacer layers becomes one of the key issues to achieve high efficiency solar cells. Herein, plasmonic amorphous silicon (a-Si:H) flexible thin film solar cells with different thickness of oxide spacer layers are systematically investigated. An increase of the spacer layer thickness leads to an evolution in surface morphology of AZO and final devices. More intriguingly, the increase of spacer layer thickness reduces the absorption in Ag layer while induces more absorption in spacer layer. The highest light absorption in silicon layer is observed as applying 100nm spacer layer, which is further verified by electrical measurements. Our observations demonstrate a versatile and convenient route towards rational design of light harvesting nanostructure for high performance plasmonic solar cells based on a broad range of materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Amorphous silicon thin film solar cells are constructed on patterned substrates. </LI> <LI> The devices properties are studied as a function of spacer layer thickness. </LI> <LI> An increase of spacer layer thickness reduces the absorption loss of Ag layer. </LI> <LI> The device with 100nm spacer layer confines more incident light in silicon layer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Purification efficiency of eight aquatic plant species in an artificial floating island system in relation to extracellular enzyme activity and microbial community

Lei Li,You Feng,Jinye Li,Qing Li,Ting Liu,Qingfeng Chen 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.6

The floating island system exploits the combination of aquatic plants, microorganisms, and extracellular enzymes to purify wastewater. We investigated the purification efficiency of eight aquatic plant species cultured in wastewater. The relationships of plant purification capacity with extracellular enzyme activity and microbial community were analyzed to explore the crucial factors that affect the plant purification capacity and the mechanism of pollutants removal in different plant systems. Three plant species, namely Oenanthe javanica, Thalia dealbata, and lris pseudacorus, were most effective for purification of ammonium-nitrogen (NH₄<SUP>+</SUP>-N), total phosphate (TP), and chemical oxygen demand (COD) with maximum efficiencies of 76.09, 85.87, and 89.10%, respectively. Urease, alkaline phosphatase (AP), and β-glucosidase activities were significantly and positively correlated with root system development (P < 0.05). Activities of urease and AP were positively correlated with NH₄<SUP>+</SUP>-N and TP removal, respectively. The magnitude of urease and AP activity was generally consistent with the plant’s capacity to remove NH₄<SUP>+</SUP>-N and TP. β-Glucosidase activity and COD removal were not significantly correlated. The dominant microbial phylum in each species treatment was Proteobacteria. Alphaproteobacteria and Bacteroidia showed > 1% relative abundance and greater involvement in degradation of pollutants in the experimental system.

Efficacy and Safety of Anti-Tumor Necrosis Factor- Alpha Agents for Patients with Intestinal Behcet’s Disease: A Systematic Review and Meta-Analysis

Qingfeng Zhang,Chunyan Ma,Rongrong Dong,Weizhen Xiang,Meiqi Li,Zhenzhen Ma,Qingrui Yang 연세대학교의과대학 2022 Yonsei medical journal Vol.63 No.2

Purpose: Intestinal Behcet’s disease (BD) is a systemic autoimmune disease for which treatment options are limited. As a prospectivetherapeutic strategy for intestinal BD, anti-tumor necrosis factor-alpha (anti-TNF-α) agents have received increasing attention. In this study, we conducted a systematic review and meta-analysis to evaluate the efficacy and safety of anti-TNF-αagents for patients with intestinal BD. Materials and Methods: We searched PubMed, Embase, and Cochrane Library databases up to July 1, 2021 and articles that metthe eligibility criteria were further assessed. Pooled rates were synthesized by a randomized effects model using Stata software. Results: Eleven clinical trials covering 671 patients with intestinal BD were included. According to compositive data, the pooledrate for remission was 39% [95% confidence interval (CI) 26–52] in patients receiving anti-TNF-α agents. Intestinal symptomswere cured in 70% (95% CI 53–84) of the patients, and the rate for endoscopic healing was 65% (95% CI 52–78). Corticosteroid discontinuationwas achieved in 43% (95% CI 28–58) of the patients, and the dose reduction of corticosteroid was 20.43 mg (95% CI13.4–27.46). There were 239 adverse events and 80 serious adverse events during follow-up. Conclusion: Our study indicated that anti-TNF-α agents may serve as an effective treatment with acceptable safety for patientswith intestinal BD. However, more robust evidence from randomized controlled trials is urgently needed to assess the long-termefficacy and safety of anti-TNF-α agents for those patients.

High-Temperature Oxidation Behavior of NiCoCrAlY Coatings Deposited by Laser Cladding on 304 Stainless Steel

Yuxin Li,Jinhao Nie,Yixin Yang,Peikang Bai,Hongjian Zhang,Zhanyong Zhao,Shouzheng Wei,Jie Cai,Qingfeng Guan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

To improve the high-temperature resistance of the key hot-end parts of the steam turbine, NiCoCrAlY coatings were depositedon a 304 stainless steel substrate by laser cladding. The microstructure and high-temperature oxidation behavior of theNiCoCrAlY coatings were analyzed. The results showed that the NiCoCrAlY coatings contained γ/γ′ and β phases, and themicrostructure was mainly composed of elongated columnar crystals. In addition, after 100 h of oxidation at three differentoxidation temperatures (750, 850 and 950 °C), the coatings showed a relatively low oxidation rate, which was approximatelya quarter of the oxidation rate of the substrate. At the same time, the protective Cr2O3scales were formed on the coatingsurface. When the oxidation temperature was 850 °C, the FeCr2O4spinel formed and internal oxidation zone appeared,when the oxidation temperature reached 950 °C, the FeCr2O4spinel gathered in the local area on the surface of the Cr2O3scale and the internal oxidation was aggravated. In other words, as the oxidation temperature increased, the Fe element inthe matrix formed the FeCr2O4spinel, which accelerated the consumption of Cr element in the coatings and reduced theoverall oxidation resistance of the NiCoCrAlY coatings.

n-Acetylcysteine protects against diazinon-induced histopathological damage and apoptosis in renal tissue of rats

Dong Gaiqin,Li Qingfeng,Yu Chun,Wang Qing,Zuo Danhua,Li Xiaozhong 한국독성학회 2024 Toxicological Research Vol.40 No.2

Diazinon (DZN) is a member of organophosphorus insecticides that has cytotoxic effects on different organs. n-Acetyl cysteine (NAC) is a widely used antioxidant in clinical, in vivo and in vitro studies. We evaluated the protective role of NAC against DZN-induced toxicity in kidney tissue of Wistar rats. 30 male Wistar rats were divided into 5 groups of control, single dose of DZN, continuous dose of DZN, single doses of DZN + NAC and continuous doses of DZN + NAC. Kidney function test (blood urea nitrogen, creatinine and uric acid) was provided. Levels of malondialdehyde (MDA), total antioxidant capacity (TAC) and total sulfhydryl (T-SH) were determined in renal tissues. Renal cells apoptosis was detected using TUNEL assay. The mRNA expressions of apoptosis, oxidative stress and inflammatory mediators, including B-cell lymphoma-2 (Bcl2), Bcl-2-associated X protein (Bax), superoxide dismutase (SOD), catalase (CAT), Interleukin 10 (IL-10), Tumor necrosis factor-α (TNF-α), Caspase-3 and Caspase-8 were analyzed in kidney tissues using Real Time PCR method. Chronic exposure to DZN was associated with severe morphological changes in the kidney, as well as impairment of its function and decreased kidney weights. Continues treatment with DZN significantly decreased the percentage of renal apoptotic cells as compared to rats treated with continuous dose of DZN alone (17.69 ± 3.67% vs. 39.46% ± 2.44%; p < 0.001). Continuous exposure to DZN significantly decreased TAC and T-SH contents, as well as SOD and CAT expression, but increased MDA contents in the kidney tissues (p < 0.001). A significant increase was observed in mRNA expression of Bax, Caspase-3, Caspase-8, as well as TNF-α following exposure to DZN, but the expression of IL-10 and Bcl2 was significantly decreased. NAC can protect kidney tissue against DZN-induced toxicity by elevating antioxidants capacity, mitigating oxidative stress, inflammation and apoptosis.

Carbon Paper-Supported NiCo/C–N Catalysts Synthesized by Directly Pyrolyzing NiCo-Doped Polyaniline for Oxygen Reduction Reaction

Zhongliang Deng,Qingfeng Yi,Yuanyuan Zhang,Huidong Nie,Guang Li,Liang Yu,Xiulin Zhou 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.1

In this study, we report the findings that the C–N composites containing Ni and Co (Ni1Co1/C–N, Ni3Co1/C–N, Ni6Co1/C–N, Ni9Co1/C–N, Ni10Co0/C–N and Ni0Co10/C–N) can be produced by direct pyrolysis of the NiCo-doped polyaniline (PANI) precursors in N2 atmosphere at 800 ℃ and show efficient electroactivity for oxygen reduction reaction (ORR) in alkaline media. Distribution and compositions of the catalysts were characterized by SEM, TEM, EDS and XRD techniques. The catalysts were loaded on carbon paper to prepare gas diffusion electrodes, in which electrocatalytic activity for ORR in alkaline media was investigated by voltammetric techniques. The ORR current density on these carbon paper-supported NiCo/C–N catalysts exhibits a linear increase with the negative shift of ORR potential. The ORR onset potential is around 0.2 V (versus Ag/AgCl) in alkaline media. Among the prepared catalysts, the catalyst Ni6Co1/C–N presents the largest ORR current density, which is 68.5 mA cm -2@-0.8 V (versus Ag/AgCl) in alkaline media. Moreover, Ni6Co1/C–N catalyst also presents good electrocatalytic activity stability for ORR.

Associations of MMP-2 21306 C/T and MMP-9 21562 C/T polymorphisms with breast cancer risk among different populations: a meta-analysis

Meng Han,Qingfeng Yang,Kai Feng,Rongping Li,Jia Ren,Liguang Wei 한국유전학회 2017 Genes & Genomics Vol.39 No.3

The meta-analysis aims to investigate association between two matrix metalloproteinases (MMPs) polymorphisms (MMP-2 -1306 C/T and MMP-9 -1562 C/T) and breast cancer risk. Eligible studies were retrieved from relevant databases, based on predefined criteria. Quality assessment was evaluated by Newcastle–Ottawa Scale. Odds ratio (OR) with its 95% confidence interval (CI) was selected as the effect size for the meta-analysis. As a result, 13 studies were included. MMP-2 -1306 C/T polymorphism was not significantly associated with breast cancer risk under all genetic models (P[0.05). However, subgroup analysis stratified by ethnicity showed a significant association between MMP-2 -1306 C/T polymorphism and reduced breast cancer risk in Asian populations under allelic model (OR 0.60, 95% CI 0.39–0.90, P = 0.02) and dominant model (OR 0.55, 95% CI 0.34–0.89, P = 0.02). MMP-9 -1562 C/T polymorphism was significantly related to increased breast cancer risk under allelic model (OR 1.50, 95% CI 1.06–2.12, P = 0.02), additive model (OR 1.45, 95% CI 1.02–2.05, P = 0.04) and recessive model (OR 1.54, 95% CI 1.13–2.12, OR 0.007). A significant association between MMP-9 -1562 C/T polymorphism and increased breast cancer risk in Caucasian was detected under most of the genetic models (P\0.05). MMP-2 -1306 C/T polymorphism might be significantly associated with reduced breast cancer risk in Asian, while MMP-9 -1562 C/T might be closely related to increased breast cancer risk, especially in Caucasian.

ALMA Reveals Sequential High-mass Star Formation in the G9.62+0.19 Complex

Liu, Tie,Lacy, John,Li, Pak Shing,Wang, Ke,Qin, Sheng-Li,Zhang, Qizhou,Kim, Kee-Tae,Garay, Guido,Wu, Yuefang,Mardones, Diego,Zhu, Qingfeng,Tatematsu, Ken’ichi,Hirota, Tomoya,Ren, Zhiyuan,Liu, Sheng-Yu American Astronomical Society 2017 The Astrophysical journal Vol.849 No.1

<P>Stellar feedback from high-mass stars (e.g., H II regions) can strongly influence the surrounding interstellar medium and regulate star formation. Our new ALMA observations reveal sequential high-mass star formation taking place within one subvirial filamentary clump (the G9.62 clump) in the G9.62+0.19 complex. The 12 dense cores (MM1-MM12) detected by ALMA are at very different evolutionary stages, from the starless core phase to the UC H II region phase. Three dense cores (MM6, MM7/G, MM8/F) are associated with outflows. The mass-velocity diagrams of the outflows associated with MM7/G and MM8/F can be well-fit by broken power laws. The mass-velocity diagram of the SiO outflow associated with MM8/F breaks much earlier than other outflow tracers (e.g., CO, SO, CS, HCN), suggesting that SiO traces newly shocked gas, while the other molecular lines (e.g., CO, SO, CS, HCN) mainly trace the ambient gas continuously entrained by outflow jets. Five cores (MM1, MM3, MM5, MM9, MM10) are massive starless core candidates whose masses are estimated to be larger than 25 M-circle dot, assuming a dust temperature of <= 20 K. The shocks from the expanding H II regions ('B' and 'C') to the west may have a great impact on the G9.62 clump by compressing it into a filament and inducing core collapse successively, leading to sequential star formation. Our findings suggest that stellar feedback from H II regions may enhance the star formation efficiency and suppress low-mass star formation in adjacent pre-existing massive clumps.</P>

Design of the flexible switching controller for small PWR core power control with the multi-model

Zeng, Wenjie,Jiang, Qingfeng,Du, Shangmian,Hui, Tianyu,Liu, Yinuo,Li, Sha Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

Small PWR can be used for power generation and heating. Considering that small PWR has the characteristics of flexible operating conditions and complex operating environment, the controller designed based on single power level is difficult to achieve the ideal control of small PWR in the whole range of core power range. To solve this problem, a flexible switching controller based on fuzzy controller and LQG/LTR controller is designed. Firstly, a core fuzzy multi-model suitable for full power range is established. Then, T-S fuzzy rules are designed to realize the flexible switching between fuzzy controller and LQG/LTR controller. Finally, based on the core power feedback principle, the core flexible switching control system of small PWR is established and simulated. The results show that the flexible switching controller can effectively control the core power of small PWR and the control effect has the advantages of both fuzzy controller and LQG/LTR controller.