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To investigate the proton exchange membrane fuel cell stack performance heterogeneity, a pseudo two-dimensional stack model integrating non-uniform flow distributions is developed. The frictional a...

Centrifugal compressor is a typical air compressor, which is an important subcomponent of the air supply system in fuel cell system. Optimizing the designing structure of centrifugal compressor pla...

Proton exchange membrane (PEM) fuel cells with an off-gas recirculation anode (ORA) or dead-ended anode (DEA) are widely adopted in engineering. However, those two hydrogen flow arrangements may cause anodic water and nitrogen accumulation in comparison with the flow-through anode (FTA) mode, which causes significant performance degradation. In this paper, a two-dimensional cold-start model is developed with detailed consideration of water phase changes and the nitrogen crossover phenomenon. A simplified electrochemical module is built to calculate the current density distribution in the model. The simulation results are consistent with the experimental data at both subzero temperatures and normal operating temperatures. The effects of hydrogen flow arrangements, flow configurations, and startup strategies are investigated during startup process from subzero to normal operating temperatures. Much less ice is generated in counter-flow cases than in co-flow cases during constant current operation. A relatively lower startup voltage can effectively shorten the cold-start process and enhance the cold-start capacity for the PEM fuel cell. The ORA mode has the best hydrogen flow arrangement due to its general abilities, including higher hydrogen utilization efficiency, higher anodic nitrogen tolerance, better output performance and better startup capability.

Osteogenic differentiation of BMSCs is beneficial to the treatment of osteoarthritis. Progranulin (PGRN) is a chondrogenic factor. However, the role of progranulin in the differentiation of BMSCs under inflammation remains unclear. Rat BMSCs were isolated and divided into control group, inflammation group (treated with LPS), and PGRN group (5 and 10 /μM) followed by analysis of survival rate of BMSCs by MTT assay, Caspase 3 activity, ALP activity, expression of Runx2 and OP by real time PCR, level of MMP-3, TIMP-1, FAK and MAPK by Western blot and IL-6 and IL-10 secretion by ELISA. LPS treatment significantly inhibited BMSCs proliferation, increased Caspase 3 activity, decreased ALP activity, expression of Runx2 and OP, increased IL-6 secretion, decreased IL-10 secretion, increased MMP-3 expression, decreased expression of TIMP-1, FAK and p-P38 (P < 0.05). PGRN treatment on BMSCs under inflammation significantly promoted cell proliferation, decreased Caspase 3 activity, increased ALP activity, expression of Runx2 and OP, decreased IL-6 secretion, increased IL-10 secretion, decreased MMP-3 expression, and increased TIMP-1, FAK and p-P38 expression (P < 0.05) with more significant changes in the higher concentration. Under inflammation, BMSCs proliferation was inhibited, apoptosis was increased, and osteogenic differentiation was weakened. PGRN inhibits the proliferation of BMSCs and apoptosis, and promotes osteogenic differentiation by regulating FAK/MAPK pathway.

Water and heat management remains a major obstacle to the successful commercialization of proton exchange membrane fuel cell (PEMFC), especially at a complicated system level. To investigate the interaction among stack and associated auxiliary subsystems, a comprehensive transient PEMFC system model is developed, including stack, membrane humidifier, electrochemical hydrogen pump, air compressor, and radiator. Each individual sub-model has been rigorously validated against experimental data. The results show that the system performance deteriorates significantly under relatively low operating current densities (0.5 A cm−2). The voltage degradation is inhibited as more product water is generated and subsequently utilized by the humidifier, enhancing the stack inlet gas humidification. Under low operating current densities, increasing the operating temperature of membrane humidifier is unfavorable as it exacerbates the membrane dehydration. The voltage undershoot is observed, which is caused by the mismatch between dynamic changes of membrane water content in fuel cell and that of humidifier. If the temperature of dry air flowing into humidifier is well managed, the membrane dehydration may be avoided and assisted heating methods for humidifier may be unnecessary. Increasing the air stoichiometry is disadvantageous as it leads to more generated water being rapidly purged out of the system.

Objective: Yes-associated protein (Yes-associated protein 1 [YAP1]) is an important oncogene that is related to the pathogenesis and progression of liver cancer. It was found that miR-424-...

Anode recirculation operation is one method to both achieve self-humidification and increase hydrogen utilization for proton exchange membrane fuel cells (PEMFCs) automotive application. In this study, effect of operating conditions, including cathode inlet relative humidity, anode and cathode inlet pressure, and anode stoichiometry on performance of PEMFC with anode recirculation are analyzed by simulation work. Generally, the performance variation when the PEMFC starts anode recirculation can be divided into two stages. The performance increases first due to the self-humidification effect and then decreases due to the nitrogen crossover. The results show that performance enhancement caused by self-humidification becomes less significant with increasing cathode inlet humidity. Increasing anode inlet pressure can retard the performance decline caused by nitrogen crossover and increasing cathode inlet pressure will exacerbate it. Increasing anode stoichiometry can enhance the self-humidification by anode recirculation.

It is widely acknowledged that the water balance issue is extremely important for improving the performance and durability of the proton exchange membrane fuel cell. In the presented paper, the visualization platform of the single fuel cell and the water balance model were built to investigate the water transport mechanisms. A transparent 25 cm2 single fuel cell with serpentine flow channels was adopted. Based on the experimental data, firstly, the change rate of water content in the fuel cell was calculated quantitatively and the reliability of the water balance model was rigorously validated. Then, the water state in the fuel cell as the qualitative finding was observed online to assist the research of water transport mechanisms. Finally, the effects of inlet gas temperature, inlet gas humidity, and hydrogen/air stoichiometry on the EIS, the voltage, and the water content in the fuel cell were studied quantitatively, respectively. The corresponding relationship between the performance and the water content in the fuel cell was obtained.

Interleukin-2 (IL-2) benefits some cancer patients by promoting the proliferation of cytotoxic effector T cells, but this process is limited by the expansion of regulatory T cells (Tregs). Low-dose cyclophosphamide (CTX) can inhibit the number and function of Tregs. We treated carcinoma-bearing mice with Vehicle, CTX, IL-2 and CTX + IL-2 to investigate the effects of low-dose CTX combined with IL-2 in antitumor treatment. In comparison to monotherapy, CTX + IL-2 significantly limited tumor growth, via tumor cell proliferation inhibition and increased apoptosis. The infiltration of CD8

Sleep quality can affect the physical and mental health, as well as the personal development of college students. Mindfulness practices are known to ameliorate sleep disorder and improve sleep quality. Trait mindfulness, an innate capacity often enhanced by mindfulness training, has been shown to relate to better sleep quality and different aspects of psychological well-being. However, how individual difference factors such as trait mindfulness relate to sleep quality remains largely unclear, which limits the optimization and further application of mindfulness-based intervention schemes targeting the improvement of sleep quality. In this study, we aimed to investigate how negative emotions and neuroticism may influence the relationship between trait mindfulness and sleep quality. A conditional process model was built to examine these relationships in 1,423 Chinese young adults. Specifically, the conditional process model was constructed with trait mindfulness as the independent variable, sleep quality as the dependent variable, negative emotions as the mediating variable, and neuroticism as the moderating variable. Our results showed that negative emotions mediated the link between mindfulness and sleep quality and that neuroticism had a moderating effect on the relationship between mindfulness and sleep quality. Together, these findings suggested a potential mechanism of how trait mindfulness influences sleep quality, provided a therapeutic target for which mindfulness-based interventions may act upon to improve sleep quality, and offered a basis for prediction of different intervention effects among individuals.

Anode recirculation of proton exchange membrane fuel cell (PEMFC) is considered as an effective way for self-humidification and efficient hydrogen utilization, but nitrogen crossover presents a problem. To investigate the transient characteristics of PEMFC with anode recirculation, a comprehensive quasi-2D non-isothermal transient model is developed. The simulation results show that for a PEMFC initially operated with dry hydrogen, anode recirculation leads to certain level of performance increase in the beginning due to self-humidification effect, and then the performance decreases caused by nitrogen crossover, hydrogen dilution and the increase of anode activation loss. The nitrogen accumulation in anode downstream is severer than upstream, and the performance decline rate decreases with increasing cathode inlet velocity under the simulated operating conditions. The performance and current density distribution uniformity of counter-flow configuration is better than co-flow under low inlet humidity, but the difference becomes smaller with anode recirculation. Anode recirculation and dead-ended anode (DEA) operation both have self-humidification effect, and compared to DEA, the advantages of anode recirculation can be summarized as lower performance decline rate, less chance of local hydrogen starvation and better current density distribution uniformity.

A comprehensive steady-state model is developed to investigate the effects of electrode structure on the performance of solid oxide fuel cell, considering detailed heat and mass transfer processes, as well as electronic and ionic charge transport. The percolation theory is used to evaluate the effective transport properties in electrode. The uniform and non-uniform distributions of electronic/ionic conducting materials in anode/cathode function layer (AFL/CFL) are comprehensively compared. The effects of function layer thickness and particle sizes are found to be different in anode and cathode. The optimal AFL thickness is increased with the increment of particle sizes. The results show that the optimal AFL thickness ranges from 5 μm to 30 μm with relatively small particle sizes (

In this study, an enhanced non-isothermal, two-phase 1D analytical proton exchange membrane fuel cell (PEMFC) model is developed, which not only considers the water saturation jump, but also proposes a novel method to analytically solve the water phase changes and couple the liquid and vapor transport together. A stringent model validation procedure is used to show good agreement between the simulated results and the experimental data, taking advantage of the “three-step” and “multi-case” validation methods. It is revealed that the uncertain parameters may deteriorate model reliability and credibility, thus demonstrating the necessity to conduct sensitivity analysis. A multi-parametric screening method i.e. the elementary effect (EE) method based on Monte Carlo experiments is implemented to comprehensively analyze the total 22 uncertain parameters (including geometric, physical and electrochemical parameters), which are finally classified into very sensitive ones, rather sensitive ones and insensitive ones. The cathodic parameters are found more sensitive than the anodic ones, and the parameters of different components may have distinct sensitivity. Besides, whether the effect of each parameter is positive or negative on cell performance is also discussed. Furthermore, three cases with different groups of parameters are presented, which show almost the same polarization curve, and the two-sample Kolmogorov-Smirnov (KS) test is applied to verify the stability difference. It is concluded that those uncertain parameters not only influence the cell performance but also affect the model stability, and hence the effects of varying operating conditions should be taken into account in validation work.

The demand for advanced energy storage devices such as supercapacitors and lithium-ion batteries has been increasing to meet the application requirements of hybrid vehicles and renewable energy systems. Here, high energy density aqueous asymmetric supercapacitor (ASC) is assembled based on chestnut shell-based activated carbon (CAC)/PANI composite positive electrode and tungsten trioxide (WO3) nanowires negative electrode. The CAC/PANI composite and WO3 nanowires were synthesized through an interfacial polymerization method and a simple sodium sulfate assisted hydrothermal process, respectively. The CAC/PANI//WO3 ASC device operates with a voltage of 1.5 V in 1 M H2SO4 electrolyte and achieved a high energy density of 15.4 Wh kg−1 at a power density of 252 W kg−1. Furthermore, the device shows an excellent cycling performance with capacitance retention of 83% after 1500 cycles.

Metal foam (MF) material is a promising alternative in fuel cell for its extremely porous structure, high electrical conductivity, controllable permeability and strong mechanical strength. However, there are seldom applications of MF flow field in alkaline anion exchange membrane (AAEM) fuel cell so far. Therefore, a three-dimensional (3D) multi-phase numerical model is implemented to investigate the feasibility of MF flow field in AAEM fuel cell and validated with experimental data from both the literature and this study. The performance of AAEM fuel cell with MF flow field is compared with that with traditional serpentine flow field. The simulation results show that MF flow field is able to improve the performance of AAEM fuel cell significantly, especially at higher current density where the concentration loss is dominant. According to analysis of transports and distributions of reactants and water (including liquid water, membrane water, and water vapor), the MF flow field is proven to be beneficial to membrane hydration, anode water removal, cathode water utilization, and reactant distribution.

The undersaturated lead or iodide ions can produce defects during the preparation of polycrystalline perovskite films, the defects critically influenced photovoltaic device efficiency and stabilities. The leakage of toxic lead also has certain environmental safety risks. In response to the above problems, we designed a molecular modification strategy for problems. A tetra-thiol copper porphyrin (CuP) molecule was synthesized and used to modify the perovskite film. The Raman spectroscopy tests determined that CuP can be anchored on the surface of perovskite film through the Pb–S bonds between the thiol of CuP and lead on perovskite film surface. The density functional theory (DFT) calculation indicate that CuP can adsorb iodide ion and iodine, then effectively reduced iodide ions and iodine vacancies. In addition, the photoluminescence and space-charge limited current measurements shown that CuP can effectively passivate defects and improve film quality. Finally, the CuP modified PSCs enhancement of the power conversion efficiencies, the best efficiency up to 20.7%. The stabilities of humidity, thermal and photo also improved. Moreover, the surface encapsulation of CuP can also effectively prevent the leakage of lead. This work provides a strategy to fabricate stable and clean PSCs by the in situ chemical coordination on perovskite films.

A transient multiphase model for cold start process is developed considering micro-porous layer (MPL), super-cooled water freezing mechanism and ice formation in cathode channel. The effect of MPL's hydrophobicity on the output performance and ice/water distribution is investigated under various startup temperatures, structural properties, membrane thicknesses and surrounding heat transfer coefficients. Under the maximum power startup mode, it is found that the hydrophobicity disparity of MPL has negligible influences when started from −15 °C, but it strongly affects the overall performance when started from −10 °C, especially after the cell survives the cold start. Decreasing the MPL's hydrophobicity leads to higher current density, meanwhile, it facilitates the super-cooled water's removal, which in turn reduces the ice formation in catalyst layer. However, excessive water accumulation happens if the generated water is hindered from getting into gas diffusion layer (GDL) due to the significant hydrophobicity gap. Weakening the GDL's hydrophobicity contributes to the water removal since the generated water is easier to diffuse out. A thinner membrane benefits the cold start owing to the reduction of ohmic loss and improvement of membrane hydration, and is more sensitive to the hydrophobicity of MPL. Ice formation in cathode channel is identified under various surrounding heat transfer coefficients.

Yes-associated protein (Yes-associated protein 1 [YAP1]) is an important oncogene that is related to the pathogenesis and progression of liver cancer. It was found that miR-424-5p expression was significantly decreased in liver cancer tissues, revealing its anticancer effect. Bioinformatic analysis demonstrated the targeted relationship between miR-424-5p and the 3' untranslated region of YAP1. This study investigated the role of miR-424-5p in regulating YAP1 expression and affecting hepatoma cell proliferation and apoptosis.Tumors and normal liver tissues adjacent to tumors were collected from patients to detect the expression of miR-424-5p and YAP1. A dual-luciferase reporter gene assay was adopted to explore the targeted regulation between miR-424-5p and YAP1. Liver cancer HCCLM3 and MHCC97-L cells and normal liver HL-7702 cells were cultured in vitro to compare expression levels of miR-424-5p and YAP1. HCCLM3 and MHCC97-L cells were divided into the miR-NC group and miR-424-5p mimic group. Cell apoptosis was detected by flow cytometry. Cell proliferation was determined by EdU staining.Compared with normal liver tissue, miR-424-5p expression was significantly decreased, while YAP1 mRNA and protein levels were obviously upregulated in liver cancer tissues, which were related to the clinical stage. A negative correlation was found between miR-424-5p and YAP1 mRNA levels in liver cancer tissues. Dual-luciferase reporter gene assay confirmed the targeted relationship between miR-424-5p and YAP1. miR-424-5p expression in HCCLM3 and MHCC97-L cells decreased compared with L20 cells, which correlated with malignancy. YAP1 level in HCCLM3 and MHCC97-L cells was significantly enhanced, which correlated with malignancy. miR-424-5p mimic transfection significantly downregulated YAP1 expression in HCCLM3 and MHCC97-L cells, resulting in enhanced apoptosis and attenuated cell proliferation.Decreased miR-424-5p expression and increased YAP1 expression are found in patients with liver cancer. Increased miR-424-5p can inhibit YAP1 expression, attenuate hepatoma cell proliferation, and induce cell apoptosis.