Due to the COVID‐19 epidemic crisis, students from higher education institutions around the world are forced to participate in comprehensive online curriculums. In such a scenario, it is worth ...investigating how students perceived their learning outcomes and satisfaction based on this method of teaching and learning online. This study aims to explore the role of six factors, namely, system quality, course design, learner‐learner interaction, learner‐instructor interaction, learner‐content interaction, and self‐discipline, on university students' perceived learning outcomes and their effect on student satisfaction with online curricula during the COVID‐19 epidemic. A structural equation modelling technique was used to assess survey questionnaires obtained from 457 validated students at a Public University in China. The results demonstrated that these determinants had a positive effect on satisfaction and learning outcomes, whereas learner‐instructor interaction had no significant effect. Furthermore, the strongest determinant that affected not only students' satisfaction but also their learning outcomes was the learner‐content interaction.
Lay Description
What is already known about this topic?
Online teaching can support students' learning in COVID‐19 epidemic.
Various determining factors affect students' learning outcomes and satisfaction towards online learning.
What this paper adds?
This study investigates six determinants on students' learning outcomes and satisfaction towards online learning.
Learner‐content interaction yielded a stronger effect on university students' learning outcomes and satisfaction.
Learner‐instructor interaction has no significant effect.
Implications for practice and/or policy
System quality, course design, learner‐learner interaction, learner‐content interaction, and self‐discipline, had a positive impact on university students' perceived learning outcomes and satisfaction in COVID‐19.
Due to its clear inherited backgrounds as well as simple and diverse genetic manipulation systems, Bacillus subtilis is the key Gram-positive model bacterium for studies on physiology and metabolism. ...Furthermore, due to its highly efficient protein secretion system and adaptable metabolism, it has been widely used as a cell factory for microbial production of chemicals, enzymes, and antimicrobial materials for industry, agriculture, and medicine. In this mini-review, we first summarize the basic genetic manipulation tools and expression systems for this bacterium, including traditional methods and novel engineering systems. Secondly, we briefly introduce its applications in the production of chemicals and enzymes, and summarize its advantages, mainly focusing on some noteworthy products and recent progress in the engineering of B. subtilis. Finally, this review also covers applications such as microbial additives and antimicrobials, as well as biofilm systems and spore formation. We hope to provide an overview for novice researchers in this area, offering them a better understanding of B. subtilis and its applications.
The large‐scale production of metal–air batteries, an appealing solution for next‐generation energy storage, requires low‐cost, earth‐abundant, and efficient oxygen electrode materials, yet insights ...into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen‐doped carbon nanotubes decorated by spinel CuCo2O4 quantum dots (CuCo2O4/N‐CNTs) is reported, outperforming the benchmark of state‐of‐the‐art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo2O4 and N‐doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu2+ and CuN) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo2O4/N‐CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all‐solid‐state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm−2 in liquid state, 1.86 W g−1 in all‐solid‐state), and long lifetime (48 h in liquid state, 9 h in all‐solid‐state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.
Advanced Cu Co bimetallic oxide quantum dots are decorated on nitrogen‐doped carbon nanotubes to serve as the bifunctional oxygen catalyst. A strong synergetic coupling in CuCo2O4/N‐CNTs is proposed, which provides advantaged local chemical environment and enriched catalytic sites. Benefiting from these features, CuCo2O4/N‐CNTs with reversible oxygen catalytic activity is capable of operating the new‐generation rechargeable zinc–air batteries.
Rational design and exploration of robust and low‐cost bifunctional oxygen reduction/evolution electrocatalysts are greatly desired for metal–air batteries. Herein, a novel high‐performance oxygen ...electrode catalyst is developed based on bimetal FeCo nanoparticles encapsulated in in situ grown nitrogen‐doped graphitic carbon nanotubes with bamboo‐like structure. The obtained catalyst exhibits a positive half‐wave potential of 0.92 V (vs the reversible hydrogen electrode, RHE) for oxygen reduction reaction, and a low operating potential of 1.73 V to achieve a 10 mA cm−2 current density for oxygen evolution reaction. The reversible oxygen electrode index is 0.81 V, surpassing that of most highly active bifunctional catalysts reported to date. By combining experimental and simulation studies, a strong synergetic coupling between FeCo alloy and N‐doped carbon nanotubes is proposed in producing a favorable local coordination environment and electronic structure, which affords the pyridinic N‐rich catalyst surface promoting the reversible oxygen reactions. Impressively, the assembled zinc–air batteries using liquid electrolytes and the all‐solid‐state batteries with the synthesized bifunctional catalyst as the air electrode demonstrate superior charging–discharging performance, long lifetime, and high flexibility, holding great potential in practical implementation of new‐generation powerful rechargeable batteries with portable or even wearable characteristic.
Bamboo‐like FeCo alloy encapsulated in nitrogen‐doped carbon nanotubes exhibits superior catalytic oxygen reduction and oxygen evolution performance than that of noble metal benchmarks, which benefits from the nitrogen‐rich and defect‐rich catalyst surface. The all‐solid‐state zinc–air batteries equipped by the synthesized materials show low charging/discharging overpotentials, long lifetime, and high flexibility, suitable for practical application.
Promoting copper catalysts with C60Ethylene glycol, a commodity chemical used as a feedstock and antifreeze agent, is synthesized industrially from dimethyl oxalate (DMO) by hydrogenation over ...precious-metal palladium catalysts at high pressures (typically 20 bars). Copper-chromium catalysts supported on silica as an alternative have required even high pressures. Zheng et al. show the addition of fullerene (C60) onto copper-silica allows DMO hydrogenation to be performed at ambient pressures with high yield (98%) and without deactivation after 1000 hours (see the Perspective by Gravel and Doris). The use of C60 to stabilize electron-deficient copper species that enhance hydrogen adsorption could likely be applied to other hydrogenation reactions catalyzed by copper. —PDS
Artificial photosynthesis for CO2 reduction coupled with water oxidation currently suffers from low efficiency due to inadequate interfacial charge separation of conventional Z‐scheme ...heterojunctions. Herein, an unprecedented nanoscale Janus Z‐scheme heterojunction of CsPbBr3/TiOx is constructed for photocatalytic CO2 reduction. Benefitting from the short carrier transport distance and direct contact interface, CsPbBr3/TiOx exhibits significantly accelerated interfacial charge transfer between CsPbBr3 and TiOx (8.90 × 108 s−1) compared with CsPbBr3:TiOx counterpart (4.87 × 107 s−1) prepared by traditional electrostatic self‐assembling. The electron consumption rate of cobalt doped CsPbBr3/TiOx can reach as high as 405.2 ± 5.6 µmol g−1 h−1 for photocatalytic CO2 reduction to CO coupled with H2O oxidation to O2 under AM1.5 sunlight (100 mW cm−2), over 11‐fold higher than that of CsPbBr3:TiOx, and surpassing the reported halide‐perovskite‐based photocatalysts under similar conditions. This work provides a novel strategy to boost charge transfer of photocatalysts for enhancing the performance of artificial photosynthesis.
A metal‐halide‐perovskite‐based nanoscale Janus Z‐scheme heterojunction of CsPbBr3/TiOx has been successfully constructed by a facile interfacial synthesis method, which possesses highly‐efficient interfacial charge separation and exhibits an outstanding photocatalytic activity for CO2 reduction coupled with water oxidation, with a high electron consumption rate of 405.2 ± 5.6 µmol g−1 h−1.
Electrets are dielectric materials that have a quasi-permanent dipole polarization. A single-molecule electret is a long-sought-after nanoscale component because it can lead to miniaturized ...non-volatile memory storage devices. The signature of a single-molecule electret is the switching between two electric dipole states by an external electric field. The existence of these electrets has remained controversial because of the poor electric dipole stability in single molecules. Here we report the observation of a gate-controlled switching between two electronic states in Gd@C82. The encapsulated Gd atom forms a charged centre that sets up two single-electron transport channels. A gate voltage of ±11 V (corresponding to a coercive field of ~50 mV Å–1) switches the system between the two transport channels with a ferroelectricity-like hysteresis loop. Using density functional theory, we assign the two states to two different permanent electrical dipole orientations generated from the Gd atom being trapped at two different sites inside the C82 cage. The two dipole states are separated by a transition energy barrier of 11 meV. The conductance switching is then attributed to the electric-field-driven reorientation of the individual dipole, as the coercive field provides the necessary energy to overcome the transition barrier.A Gd@C82 molecule shows electric polarization switching behaviour under a gate bias voltage, thus demonstrating a single-molecule electret device.
Perovskite solar cells are promising candidates for next‐generation photovoltaics. Fullerenes and their derivatives can act as efficient electron transport layers, interfacial modification layers, ...and trap state passivators in perovskite solar cells, all of which play an important role in increasing efficiency, reducing current hysteresis, and enhancing device stability. Herein, recent progress in the use of fullerenes and their derivatives in perovskite solar cells is reviewed, with a particular emphasis on fullerene chemical structures that affect device performance. Potential fullerene candidates that could further improve device performance and stability are also discussed.
The application of fullerene materials in perovskite solar cells, such as in electron transport layers, interfacial modification layers, and trap state passivators, is reviewed. Fullerene structures that influence performance and function are emphasized. Utilizing hydrophobic, crosslinked, and doped fullerene materials may facilitate the development of perovskite solar cells with high efficiency and excellent long‐term stability.
Background/purpose An increased prevalence of non-alcoholic fatty liver disease (NAFLD) is observed in patients with inflammatory bowel disease (IBD) in Western countries. Both intestinal ...inflammation and metabolic factors contribute to the pathogenesis of IBD-associated NAFLD. The burden of NAFLD is not clear in the Asian population. This study aimed to evaluate the prevalence of NAFLD and liver fibrosis in a cohort of Taiwanese patients with IBD. Methods From January to December 2019, patients with IBD who underwent ultrasound examination were enrolled. Hepatic steatosis and fibrosis were measured with liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) using FibroScan. Patients with a history of excessive alcohol or recent steroid use were excluded. Univariate and multivariate analysis were performed. Results A total of 81 consecutive patients were enrolled and included in the analysis (45 with ulcerative colitis, 36 with Crohn's disease). The median age was 42 years old. The patients were classified in terms of body mass index as normal weight (54.3%), underweight (11.1%), overweight (28.4%), and obese (6.2%). The mean CAP increased to 162.22 dB/m in the underweight group, 210.86 dB/m in the normal weight group, 260.7 dB/m in the overweight group, and 274.0 dB/m in the obese group. NAFLD was observed in 29.6% of the patients, 1.2% of which had significant fibrosis. Increased body mass index (odds ratio OR 1.33, 95% confidence interval CI 1.1-1.62) and older age at IBD diagnosis (OR: 1.05, 95% CI 1-1.11) was found to be associated with the presence of NAFLD. Conclusion In this study, the prevalence of NAFLD was lower (29.6%) in IBD patients than in the Western population. Higher BMI and older age were associated with NAFLD in our study.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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