Pt@Nb-TiO₂ Catalyst Membranes Fabricated by Electrospinning and Atomic Layer Deposition

A facile method was developed to fabricate fibrous membranes of niobium-doped titania-supported platinum catalysts (Pt@Nb-TiO₂) by a two-step approach. The process started with generating niobium-doped titania (Nb-TiO₂) fibrous membranes by electrospinning, followed by the deposition of Pt nanoparticles (NPs) using an atomic layer deposition (ALD) technique. The area-specific oxygen reduction reaction (ORR) activity of Pt@TiO₂ catalyst membrane was increased by ∼20 folds if 10 at.% of Nb was incorporated into the ceramic fibers. The area-specific activity also increased with the number of ALD cycles, because of the increase of the Pt loading in the catalysts. After post-treatment of the catalyst membrane at high temperature in H₂-containing atmosphere, the ORR activity became 0.28 mA/cm²_Pt at 0.9 V (vs RHE), because of the improvement in conductivity of Nb-TiO₂ fibers and better crystalinity of Pt NPs. The results of accelerated-stability test showed that the Pt@Nb-TiO₂ catalyst membrane was highly stable and lost only 10% of its initial activity after 30 000 potential cycles (0.6 to 1.0 V vs RHE) under a strong acidic condition

Protection of Electroactive Biofilm from Extreme Acid Shock by Polydopamine Encapsulation

Electroactive biofilm has a low tolerance for accidental shocks, such as extreme acid shock, which is a potential limitation for the application of bioelectrochemical systems (BESs), especially as a sensor for water quality monitoring. In this work, we encapsulated electroactive biofilms with biocompatible polydopamine (PDA) to protect against extreme acid shock. The bacterial cells were completely encapsulated in ∼50 nm films formed by PDA spheres, which protected their viability and current recoverability even after pH 0.5 and 1.5 shocks. The limiting current density of the PDA-encapsulated anode was 0.20 ± 0.05 A/m², which was 1900% higher than that of the unprotected control (0.01 ± 0.01 A/m²) after strong acid shock (pH 0.5, 30 min). Without PDA encapsulation, the biofilm partly disintegrated with a thickness decreased by 68% from 72 to 23 μm, where 92% of the cells were dead. Our findings reported a novel and effective method for protecting electroactive biofilm under extreme conditions, which will greatly extend the use of BESs in the future

Real-Time Imaging Revealed That Exoelectrogens from Wastewater Are Selected at the Center of a Gradient Electric Field

Exoelectrogens acclimated from the environment are the key to energy recovery from waste in bioelectrochemical systems. However, it is still unknown how these bacteria are selectively enriched on the electrode. Here we confirmed for the first time that the electric field (EF) intensity selects exoelectrogens from wastewater using an integrated electrovisual system with a gradient EF. Under the operating conditions (<i>I</i> = 3 × 10^–3A), the EF intensity on the working electrode ranged from 6.00 V/cm at the center to 1.08 V/cm at the edge. A thick biofilm (88.9 μm) with spherical pink aggregates was observed at the center, while the color became gray at the edge (33.8 μm). The coverage of the biofilm also increased linearly with EF intensity from 0.42 at the edge (12 mm to the center) to 0.78 at the center. The biofilm at the center contained 76% Geobacter, which was 25% higher than that at the edge (60%). Geobacter anodireducens was the main species induced by the EF (50% at the center vs 24% at the edge). These results improve our fundamental knowledge of exoelectrogen acclimation and mixed electroactive biofilm formation, which has broader implications for energy recovery from waste and general understanding of microbial ecology

A comprehensive proton exchange membrane fuel cell system model integrating various auxiliary subsystems

© 2019 Elsevier Ltd A comprehensive proton exchange membrane fuel cell (PEMFC) system model is developed, including a pseudo two-dimensional transient multiphase stack model, a one-dimensional transient multiphase membrane humidifier model, a one-dimensional electrochemical hydrogen pump model, an air compressor model with proportion-integral-derivative control and a ribbon-tubular fin radiator model. All sub-models have been rigorously validated against experimental data to guarantee the system model accuracy. The effects of stack operating temperature, gas flow pattern and humidifier structural design are investigated to cast insights into the interaction among stack and auxiliary subsystems. The results indicate that the stack is successfully maintained at required operating temperatures (60 °C, 70 °C, 80 °C) with help of the radiator when the whole system starts from ambient temperature (25 °C). However, the stack is likely to suffer from membrane dehydration when operated at 70 °C, and the problem becomes more severe at 80 °C, causing significant performance deterioration. The water and temperature distribution inside the system are further demonstrated. The co-current flow pattern contributes to better water utilization of the whole system which may lead to higher output performances. But the counter-current flow pattern has positive effects on parameter distribution uniformity inside fuel cell, which is beneficial for the stack durability. As regards the membrane dehydration, it is found that optimizing membrane humidifier area does not fundamentally solve the problem. Increasing humidifier area contributes to higher water vapor transfer rate, however, it results in much slower humidification responses

Sorption Enhancement of Lead Ions from Water by Surface Charged Polystyrene-Supported Nano-Zirconium Oxide Composites

A novel hybrid nanomaterial was fabricated by encapsulating ZrO₂ nanoparticles into spherical polystyrene beads (MPS) covalently bound with charged sulfonate groups (−SO₃^–). The resultant adsorbent, Zr–MPS, exhibited more preferential sorption toward Pb­(II) than the simple equivalent mixture of MPS and ZrO₂. Such observation might be ascribed to the presence of sulfonate groups of the polymeric host, which could enhance nano-ZrO₂ dispersion and Pb­(II) diffusion kinetics. To further elucidate the role of surface functional groups, we encapsulated nano-ZrO₂ onto another two macroporous polystyrene with different surface groups (i.e., −N­(CH₃)₃⁺/–CH₂Cl, respectively) and a conventional activated carbon. The three obtained nanocomposites were denoted as Zr–MPN, Zr–MPC, and Zr–GAC. The presence of −SO₃^– and −N­(CH₃)₃⁺ was more favorable for nano-ZrO₂ dispersion than the neutral −CH₂Cl, resulting in the sequence of sorption capacities as Zr–MPS > Zr–MPN > Zr–GAC > Zr–MPC. Column Pb­(II) sorption by the four nanocomposites further demonstrated the excellent Pb­(II) retention by Zr–MPS. Comparatively, Zr–MPN of well-dispersed nano-ZrO₂ and high sorption capacities showed much faster breakthrough for Pb­(II) sequestration than Zr–MPS, because the electrostatic repulsion of surface quaternary ammonium group of MPN and Pb­(II) ion would result in a poor sorption kinetics. This study suggests that charged groups in the host resins improve the dispersion of embedded nanoparticles and enhance the reactivity and capacity for sorption of metal ions. Suitably charged functional groups in the hosts are crucial in the fabrication of efficient nanocomposites for the decontamination of water from toxic metals and other charged pollutants

Propofol inhibits proliferation, migration, and invasion but promotes apoptosis by regulation of Sox4 in endometrial cancer cells

<div><p>Propofol is an intravenous sedative hypnotic agent of which the growth-inhibitory effect has been reported on various cancers. However, the roles of propofol in endometrial cancer (EC) remain unclear. This study aimed to explore the effects of propofol on EC in vitro and in vivo. Different concentrations of propofol were used to treat Ishikawa cells. Colony number, cell viability, cell cycle, apoptosis, migration, and invasion were analyzed by colony formation, MTT, flow cytometry, and Transwell assays. In addition, the pcDNA3.1-Sox4 and Sox4 siRNA plasmids were transfected into Ishikawa cells to explore the relationship between propofol and Sox4 in EC cell proliferation. Tumor weight in vivo was measured by xenograft tumor model assay. Protein levels of cell cycle-related factors, apoptosis-related factors, matrix metalloproteinases 9 (MMP9), matrix metalloproteinases 2 (MMP2) and Wnt/β-catenin pathway were examined by western blot. Results showed that propofol significantly decreased colony numbers, inhibited cell viability, migration, and invasion but promoted apoptosis in a dose-dependent manner in Ishikawa cells. Moreover, propofol reduced the expression of Sox4 in a dose-dependent manner. Additionally, propofol significantly suppressed the proportions of Ki67+ cells, but Sox4 overexpression reversed the results. Furthermore, in vivo assay results showed that propofol inhibited tumor growth; however, the inhibitory effect was abolished by Sox4 overexpression. Moreover, propofol inhibited Sox4 expression via inactivation of Wnt/β-catenin signal pathway. Our study demonstrated that propofol inhibited cell proliferation, migration, and invasion but promoted apoptosis by regulation of Sox4 in EC cells. These findings might indicate a novel treatment strategy for EC.</p></div

Enabling real-time optimization of dynamic processes of proton exchange membrane fuel cell: Data-driven approach with semi-recurrent sliding window method

The reliability of proton exchange membrane fuel cell (PEMFC) tightly depends on the suitable operating conditions during dynamic operations. This study proposes an optimization framework to determine the optimal control strategy for PEMFC cold starts underpinned by a novel artificial intelligence method, to improve cold-start capacity and shorten the start-up time. The effects of constant and dynamic currents on PEMFC cold starts under various initial temperatures are studied. The numerical results from a developed PEMFC dynamic model show that the constant current slope strategy (CCSS) is more efficient than the constant current strategy (CCS) in respect of the cold-start time. In the CCSS study, a too-large current slope can lead to a voltage undershoot and then cause a failed cold start, but a too-small current slope can result in a long start-up process in the investigated range of the operating conditions. A data-driven model is developed for dynamic prediction and real-time optimization during the cold start by a semi-recurrent sliding window (SW) method coupled with artificial neural networks (NN) with the simulation data. Based on this NN-SW model, the specific safety–critical operating condition curve under the CCSS has been identified. A real-time adaptive control strategy (RACS) is further proposed to optimize the operating current during the PEMFC cold starts with various initial temperatures. Compared to the optimal CCSS, RACS proves to be more robust and efficient for PEMFC cold-start startups. Based on RACS, the start-up time for an initial temperature of −20 °C can be cut down by 26.7%. Furthermore, the ice predictions by the NN-SW model are also tested and the results are satisfying with an average R2 = 0.9773

Table_5_Regional disparity in epidemiological characteristics of adolescent scoliosis in China: Data from a screening program.docx

ObjectiveWe investigated regional disparities in rates of scoliosis among adolescents in western and eastern China and the dominant factors underlying these disparities.MethodsThis cross-sectional study used data from a school scoliosis screening program conducted in two typical areas: Yangpu District of Shanghai (eastern China) and Tianzhu Tibetan Autonomous County of Gansu Province (western China), during October 2020 to February 2021. Participants included adolescents aged 12–16 years (4,240 in Shanghai and 2,510 in Gansu Province). School scoliosis screening data were obtained on age, sex, height, weight and BMI, and region as well. We screened angles of trunk rotation in level of proximal thoracic (T1–T4), main thoracic (T5–T12), and lumbar (T12–L4) by the forward bend test with scoliometer. An angle of trunk rotation ≥5° was used as the criterion to identify suspected scoliosis.ResultsThe proportion of suspected scoliosis was lower in Shanghai (6.9%) than in Gansu (8.6%). Angle of trunk rotation tended to increase with age in Shanghai, peaking at 15 years, but decreased with age in Gansu, and bottomed at 15 years. The angle of trunk rotation in the proximal thoracic, main thoracic, and lumbar part of the spine appeared to be larger in Gansu adolescents and in Shanghai female adolescents. Age was a relevant factor in angle trunk rotation in regression models and interacted with region as well.ConclusionWe found regional and age- and sex-related disparities in rates of suspected scoliosis.</p

Table_1_Regional disparity in epidemiological characteristics of adolescent scoliosis in China: Data from a screening program.docx

ObjectiveWe investigated regional disparities in rates of scoliosis among adolescents in western and eastern China and the dominant factors underlying these disparities.MethodsThis cross-sectional study used data from a school scoliosis screening program conducted in two typical areas: Yangpu District of Shanghai (eastern China) and Tianzhu Tibetan Autonomous County of Gansu Province (western China), during October 2020 to February 2021. Participants included adolescents aged 12–16 years (4,240 in Shanghai and 2,510 in Gansu Province). School scoliosis screening data were obtained on age, sex, height, weight and BMI, and region as well. We screened angles of trunk rotation in level of proximal thoracic (T1–T4), main thoracic (T5–T12), and lumbar (T12–L4) by the forward bend test with scoliometer. An angle of trunk rotation ≥5° was used as the criterion to identify suspected scoliosis.ResultsThe proportion of suspected scoliosis was lower in Shanghai (6.9%) than in Gansu (8.6%). Angle of trunk rotation tended to increase with age in Shanghai, peaking at 15 years, but decreased with age in Gansu, and bottomed at 15 years. The angle of trunk rotation in the proximal thoracic, main thoracic, and lumbar part of the spine appeared to be larger in Gansu adolescents and in Shanghai female adolescents. Age was a relevant factor in angle trunk rotation in regression models and interacted with region as well.ConclusionWe found regional and age- and sex-related disparities in rates of suspected scoliosis.</p

Table_4_Regional disparity in epidemiological characteristics of adolescent scoliosis in China: Data from a screening program.docx

ObjectiveWe investigated regional disparities in rates of scoliosis among adolescents in western and eastern China and the dominant factors underlying these disparities.MethodsThis cross-sectional study used data from a school scoliosis screening program conducted in two typical areas: Yangpu District of Shanghai (eastern China) and Tianzhu Tibetan Autonomous County of Gansu Province (western China), during October 2020 to February 2021. Participants included adolescents aged 12–16 years (4,240 in Shanghai and 2,510 in Gansu Province). School scoliosis screening data were obtained on age, sex, height, weight and BMI, and region as well. We screened angles of trunk rotation in level of proximal thoracic (T1–T4), main thoracic (T5–T12), and lumbar (T12–L4) by the forward bend test with scoliometer. An angle of trunk rotation ≥5° was used as the criterion to identify suspected scoliosis.ResultsThe proportion of suspected scoliosis was lower in Shanghai (6.9%) than in Gansu (8.6%). Angle of trunk rotation tended to increase with age in Shanghai, peaking at 15 years, but decreased with age in Gansu, and bottomed at 15 years. The angle of trunk rotation in the proximal thoracic, main thoracic, and lumbar part of the spine appeared to be larger in Gansu adolescents and in Shanghai female adolescents. Age was a relevant factor in angle trunk rotation in regression models and interacted with region as well.ConclusionWe found regional and age- and sex-related disparities in rates of suspected scoliosis.</p