Abstract
The 21st century is an era of information explosion, and the multimedia technology is also growing vigorously. It not only changes the conditions of many industries, but also brings a ...completely new innovation to the education industry. The advent of Computer multimedia technology has brought about a qualitative change in educational concepts and ideas. It has brought opportunities and challenges to educators, as well as efficiency and science to students. Students no longer accept the knowledge singly and passively, and do not need to be restricted by the age of teachers and teaching methods. With the assistance of Computer multimedia technology, college track and field teaching and training will have a new look, allowing students to devote themselves to learning more willingly, and the vast and abundant technical resources also allow students to get more high-quality and advanced teaching materials. Because Computer multimedia technology has an obvious influence on track and field teaching and training, this paper will discuss the track and field teaching and training. First, it will discuss the necessity of integrating Computer multimedia technology into track and field training, and then talk about the great significance of Computer multimedia technology in the track and field teaching and training. Finally, it puts forward some constructive suggestions for the better integration of Computer multimedia technology with track and field teaching and training and to maximize the effect. I hope that we can contribute to the physical education cause in the motherland.
► The materials of anode and cathode in MFCs are classified according to configuration. ► We analyzed the characteristic, performance and cost of these electrode materials. ► The modification methods ...for the anodic electrode are summarized. ► The challenges and prospects of future electrode development are briefly discussed.
The performance and cost of electrodes are the most important aspects in the design of microbial fuel cell (MFC) reactors. A wide range of electrode materials and configurations have been tested and developed in recent years to improve MFC performance and lower material cost. As well, anodic electrode surface modifications have been widely used to improve bacterial adhesion and electron transfer from bacteria to the electrode surface. In this paper, a review of recent advances in electrode material and a configuration of both the anode and cathode in MFCs are provided. The advantages and drawbacks of these electrodes, in terms of their conductivity, surface properties, biocompatibility, and cost are analyzed, and the modification methods for the anodic electrode are summarized. Finally, to achieve improvements and the commercial use of MFCs, the challenges and prospects of future electrode development are briefly discussed.
To achieve high charge density for the triboelectric polymer is a crucial task for fabricating triboelectric nanogenerators (TENGs). This work has developed a quenching polarization (QP) method to ...create ultrahigh and long‐persistent triboelectric charge on the triboelectric polymer with weak dipole polarity. The Ethylene chlorotrifluoroethylene copolymer (ECTFE) film can reach a charge density of 391 µC m−2 in the vertical contact mode by using this QP treatment, which is 200% higher than the result achieved by the most widely used method of corona polarization. The mechanism of the improvement through QP on the triboelectric properties is studied on the basis of the polarization induced grain refinement and interfacial trapping. The QP‐treated ECTFE can maintain ultra‐high charge density for both solid‐solid and solid‐liquid TENG. More interestingly, the charge induced by QP treatment is so persistent that it produces a recoverable discharging phenomenon for solid‐liquid TENG, which has never been observed before. This QP method provides a different approach for fabricating high‐performance triboelectric materials, while the QP‐induced changes in crystallization and tribo‐charge density can help to complete the physical understanding of the electrification mechanism of triboelectric polymer.
A quenching polarization method is developed to create ultrahigh and long‐persistent triboelectric charge on weak polar triboelectric polymer. This method refines the grains of ECTFE through the drastic change of temperature under the externally applied electric field and increases interfaces between the crystalline and amorphous regions, which induce a large amount of interfacial deep traps for charges storage.
Abstract
Triboelectric polymer with high charge density is the foundation to promote the wide range of applications of triboelectric nanogenerators. This work develops a method to produce ...triboelectric polymer based on repeated rheological forging. The fluorinated ethylene propylene film fabricated by repeated forging method not only has excellent mechanical properties and good transmittance, but also can maintain an ultrahigh tribo-charge density. Based on the film with a thickness of 30 μm, the output charge density from contact-separation nanogenerator reaches 352 μC·m
−2
. Then, the same film is applied for the nanogenerator with air-breakdown mode and a charge density of 510 μC·m
−2
is further achieved. The repeated forging method can effectively regulate the composition of surface functional groups, the crystallinity, and the dielectric constants of the fluorinated ethylene propylene, leading to the superior capability of triboelectrification. Finally, we summarize the key parameters for elevating the electrification performance on the basis of molecular structure and related fabrication crafts, which can guide the further development of triboelectric polymers.
This study constructed a 1000 L modularized MFC system, the largest volume so far, to treat practical municipal wastewater. This MFC system was operated under two different water flow connections in ...two municipal wastewater treatment plants (MWTP) for more than one year to test their treating abilities for wastewater with both low (average 80 mg L−1) and high initial COD concentration (average 250 mg L−1). The COD concentration in the effluent from the MFC system remained below 50 mg L−1 with a removal rate of 70–90%, which stably met the level A of the first class in discharge standard of pollutants for MWTP of China. A maximum power density of 125 W m−3 (7.58 W m−2) was generated when the MFC system was fed with artificial wastewater, while it lay in a range of 7–60 W m−3 (0.42–3.64 W m−2) when treating municipal wastewater. The energy recovery of 0.033 ± 0.005 kWh per m3 of municipal wastewater was achieved, with a hydraulic retention time (HRT) of 2 h.
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•Scaled-up (1000 L) MFC consisted of 50 modules was operated for a year.•The MFC was applied to treat artificial and real municipal wastewater.•Concentration of COD released was below 50 mg L−1 with a removal rate of 70–90%.•The maximum power density harvested from municipal wastewater was 7–60 W m−3.
The outbreak of the novel coronavirus in China (SARS‐CoV‐2) that began in December 2019 presents a significant and urgent threat to global health. This study was conducted to provide the ...international community with a deeper understanding of this new infectious disease. Epidemiological, clinical features, laboratory findings, radiological characteristics, treatment, and clinical outcomes of 135 patients in northeast Chongqing were collected and analyzed in this study. A total of 135 hospitalized patients with COVID‐19 were enrolled. The median age was 47 years (interquartile range, 36‐55), and there was no significant gender difference (53.3% men). The majority of patients had contact with people from the Wuhan area. Forty‐three (31.9%) patients had underlying disease, primarily hypertension (13 9.6%), diabetes (12 8.9%), cardiovascular disease (7 5.2%), and malignancy (4 3.0%). Common symptoms included fever (120 88.9%), cough (102 76.5%), and fatigue (44 32.5%). Chest computed tomography scans showed bilateral patchy shadows or ground glass opacity in the lungs of all the patients. All patients received antiviral therapy (135 100%) (Kaletra and interferon were both used), antibacterial therapy (59 43.7%), and corticosteroids (36 26.7%). In addition, many patients received traditional Chinese medicine (TCM) (124 91.8%). It is suggested that patients should receive Kaletra early and should be treated by a combination of Western and Chinese medicines. Compared to the mild cases, the severe ones had lower lymphocyte counts and higher plasma levels of Pt, APTT, d‐dimer, lactate dehydrogenase, PCT, ALB, C‐reactive protein, and aspartate aminotransferase. This study demonstrates the clinic features and therapies of 135 COVID‐19 patients. Kaletra and TCM played an important role in the treatment of the viral pneumonia. Further studies are required to explore the role of Kaletra and TCM in the treatment of COVID‐19.
Research Highlights
83.7% of the patients had contact history in Wuhan or had been to Wuhan or had contact with people from Wuhan.
Common symptoms included fever, cough, and fatigue. Other symptoms include myalgia, fatigue, dyspnea, anorexia, etc.
Common complications of the patients include acute respiratory distress syndrome, acute cardiac injury, acute kidney injury, secondary infection and shock. ICU patients were more likely to have these complications than non‐ICU patients.
Compared with non‐ICU patients, ICU patients had lower lymphocyte count, and higher plasma levels of the Pt, APTT, D‐dimer, LDH, PCT, ALB, CRP, AST.
All patients received antiviral therapy (kaletra or interferon), antibacterial therapy and corticosteroid and many received traditional chinese medicine. It was suggested that patients should use kaletra early.
Microplastic pollution has become emerging environmental concern around world. The wastewater treatment plants (WWTPs) are attributed to a major pathway for microplastics (MPs) to enter into aquatic ...environment. To understand the fate and control strategies of MPs in WWTPs, we investigated MPs at a full-scale WWTP, Eastern China, with two parallel wastewater treatment systems, i.e. oxidation ditch (OD) and membrane bioreactor (MBR) for case study. The influent MPs consisted of polyethylene terephthalate (PET, 47%), polystyrene (PS, 20%), polyethylene (PE, 18%) and polypropylene (PP, 15%). MP morphotypes dominated in fragments (65%) and fibers (21%), which mainly were PET, with limited films (12%) and foams (2%). Typical plastic microbeads were not observed. The dominant size of MPs was >500 μm (40%) and 62.5–125 μm (29%). MP concentrations increased across the treatment systems depends on facility of treatment process. Influent MPs were removed by 99.5% in MBR system versus 97% in OD system on the basis of plastic mass while 82.1% versus 53.6% on MP number. The removed MPs accumulated in sludge phase. MBR system has much higher MP removal efficiency than OD system, likely due to membrane filtration. The results suggest that the source control of MPs by eliminating MP fibers from laundry facilities, banning use of plastic microbeads, Styrofoam products and plastic bags and properly selecting WWTP treatment unit could significantly reduce the mass and number of MPs from WWTPs.
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•Microplastics (MP) numbers increased cross oxidation ditch and MBR systems.•MPs belonging to PET, PS, PE and PP dominated in morphotypes of fragments and fibers.•MPs removed from water phase by >97% and accumulated in sludge phase.•MBR was superior in MP removal due to micromembrane filtration.•Strategies for MP source reduction and enhancement of WWTP management are proposed.
•FO membrane had an excellent rejecting effect for real sewage.•Concentrating multiple of pollutants did not reach concentrating volume multiple.•FO membrane flux was affected mainly by DS ...concentration.•Cross-flow velocity had little influence on membrane flux change.•Fouled FO membrane could be remitted by physical and chemical cleaning.
Forward osmosis (FO) draws attention due to its advantages compares to traditional pressure-driven membrane processes. In this study, a FO membrane concentrating system was built for sewage concentration to investigate membrane rejection, concentrating effect, membrane fouling behavior. Sewage could be concentrated to 1/10 original volume by FO membrane, while pollutants concentrating multiple could not reach 10. The FO membrane had excellent rejecting effect, with effluent COD, ammonia nitrogen, total nitrogen, total phosphorus concentration of 18, 2.5, 2.8, 0.4mg/L, respectively. The FO membrane flux was mainly associated with the draw solution (DS) concentration, which increased with DS concentration but more severe membrane fouling engendered in the meantime. Scanning electronic microscope and fourier transform infrared spectroscopy analysis indicated the formation and constitution of the fouling layer, which included humic acid, protein, and polysaccharide. After concentration, fouled FO membrane was remitted by physical and chemical cleaning, with recovery of 90% and 96%.
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► Nano-ZnO modified PVDF membrane reached 100% water flux recovery. ► The initial flux of modified membrane maintained stable in the long-term operation. ► Moderate modification ...almost doubled the water permeability. ► Modified internal pores might render enhanced anti-irreversible fouling property.
Irreversible membrane fouling is harmful for long-term operation of filtration. In this study, a novel anti-irreversible fouling polyvinylidene fluoride (PVDF) membrane was successfully fabricated using the wet phase separation methods. Nano-ZnO, with different dosages ranging from 6.7% to 26.7% (percentage of PVDF weight), was blended as an additive into the membrane matrix for the modification of the internal surfaces of membrane pores. A series of tests, such as filtration experiments, contact angle measurements, scanning electron microscope (SEM)/energy dispersive X-ray spectrometer (EDS) analyses and mechanical tests, were performed to characterize the modified membranes. The multi-cycle filtration experiments showed that the modified PVDF membranes demonstrated significant anti-irreversible fouling property. All the modified membranes achieved almost 100% water flux recovery after physical cleaning, whereas the raw membrane only reached 78% recovery. This promotion might be related to the increase of membrane hydrophilicity. The implantation of nano-ZnO into membrane inner surface (i.e., pore wall), as indicated by SEM/EDS tests, might be responsible for the enhancement of anti-irreversible fouling property. The water permeability of the modified membrane almost doubled by adding 6.7% nano-ZnO which was determined as the optimum dosage (within the dosage range in this study) for PVDF membrane modification. Additionally, the mechanical strength was found reinforced for modified membranes, which should also benefit the filtration application.
Activated carbon (AC) is a useful and environmentally sustainable catalyst for oxygen reduction in air-cathode microbial fuel cells (MFCs), but there is great interest in improving its performance ...and longevity. To enhance the performance of AC cathodes, carbon black (CB) was added into AC at CB:AC ratios of 0, 2, 5, 10, and 15 wt % to increase electrical conductivity and facilitate electron transfer. AC cathodes were then evaluated in both MFCs and electrochemical cells and compared to reactors with cathodes made with Pt. Maximum power densities of MFCs were increased by 9–16% with CB compared to the plain AC in the first week. The optimal CB:AC ratio was 10% based on both MFC polarization tests and three electrode electrochemical tests. The maximum power density of the 10% CB cathode was initially 1560 ± 40 mW/m2 and decreased by only 7% after 5 months of operation compared to a 61% decrease for the control (Pt catalyst, 570 ± 30 mW/m2 after 5 months). The catalytic activities of Pt and AC (plain or with 10% CB) were further examined in rotating disk electrode (RDE) tests that minimized mass transfer limitations. The RDE tests showed that the limiting current of the AC with 10% CB was improved by up to 21% primarily due to a decrease in charge transfer resistance (25%). These results show that blending CB in AC is a simple and effective strategy to enhance AC cathode performance in MFCs and that further improvement in performance could be obtained by reducing mass transfer limitations.
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