Artificial selection is a promising approach to manipulate microbial communities. Here, we report the outcome of two artificial selection experiments at the microbial community level. Both used ...“propagule” selection strategies, whereby the best-performing communities are used as the inocula to form a new generation of communities. Both experiments were contrasted to a random selection control. The first experiment used a defined set of strains as the starting inoculum, and the function under selection was the amylolytic activity of the consortia. The second experiment used multiple soil communities as the starting inocula, and the function under selection was the communities’ cross-feeding potential. In both experiments, the selected communities reached a higher mean function than the control. In the first experiment, this was caused by a decline in function of the control, rather than an improvement of the selected line. In the second experiment, this response was fueled by the large initial variance in function across communities, and stopped when the top-performing community “fixed” in the metacommunity. Our results are in agreement with basic expectations from breeding theory, pointing to some of the limitations of community-level selection experiments that can inform the design of future studies.
Insight into COVID-19 intensive care unit (ICU) patient characteristics, rates and risks of invasive mechanical ventilation (IMV) and associated outcomes as well as any regional discrepancies is ...critical in this pandemic for individual case management and overall resource planning.
Electronic searches were performed for reports through May 1 2020 and reports on COVID-19 ICU admissions and outcomes were included using predefined search terms. Relevant data was subsequently extracted and pooled using fixed or random effects meta-analysis depending on heterogeneity. Study quality was assessed by the NIH tool and heterogeneity was assessed by I2 and Q tests. Baseline patient characteristics, ICU and IMV outcomes were pooled and meta-analyzed. Pooled odds ratios (pOR) were calculated for clinical features against ICU, IMV mortality. Subgroup analysis was carried out based on patient regions. A total of twenty-eight studies comprising 12,437 COVID-19 ICU admissions from seven countries were meta-analyzed. Pooled ICU admission rate was 21% 95% CI 0.12-0.34 and 69% of cases needed IMV 95% CI 0.61-0.75. ICU and IMV mortality were 28.3% 95% CI 0.25-0.32, 43% 95% CI 0.29-0.58 and ICU, IMV duration was 7.78 95% CI 6.99-8.63 and 10.12 95% CI 7.08-13.16 days respectively. Besides confirming the significance of comorbidities and clinical findings of COVID-19 previously reported, we found the major correlates with ICU mortality were IMV pOR 16.46, 95% CI 4.37-61.96, acute kidney injury (AKI) pOR 12.47, 95% CI 1.52-102.7, and acute respiratory distress syndrome (ARDS) pOR 6.52, 95% CI 2.66-16.01. Subgroup analyses confirm significant regional discrepancies in outcomes.
This is a comprehensive systematic review and meta-analysis of COVID-19 ICU and IMV cases and associated outcomes. The significant association of AKI, ARDS and IMV with mortality has implications for ICU resource planning for AKI and ARDS as well as suggesting the need for further research into optimal ventilation strategies for COVID-19 patients in the ICU setting. Regional differences in outcome implies a need to develop region specific protocols for ventilatory support as well as overall treatment.
Context
The flipped classroom (FC), reversing lecture and homework elements of a course, is popular in medical education. The FC uses technology‐enhanced pre‐class learning to transmit knowledge, ...incorporating in‐class interaction to enhance higher cognitive learning. However, the FC model is expensive and research on its effectiveness remains inconclusive. The aim of this study was to compare the efficacy of the FC model over traditional lecture‐based (LB) learning by meta‐analysis.
Methods
We systematically searched MEDLINE, PubMed, ERIC, CINAHL, EMBASE, reference lists and Association for Medical Education in Europe (AMEE) conference books. Controlled trials comparing academic outcomes between the FC and LB approaches in higher education were considered eligible. The main findings were pooled using a random‐effects model when appropriate.
Results
Forty‐six studies (9026 participants) were included, comprising four randomised controlled trials (RCTs), 19 quasi‐experimental studies and 23 cohort studies. Study populations were health science (n = 32) and non health science (n = 14) students. The risk of bias was high (36/37 articles). Meta‐analyses revealed that the FC had significantly better outcomes than the LB method in examination scores (post‐intervention and pre–post change) and course grades, but not in objective structured clinical examination scores. Subgroup analyses showed the advantage of the FC was not observed in RCTs, non‐USA countries, nursing and other health science disciplines and earlier publication years (2013 and 2014). Cumulative analysis and meta‐regression suggested a tendency for progressively better outcomes by year. Outcome assessments rarely focused on behaviour change.
Conclusions
The FC method is associated with greater academic achievement than the LB approach for higher‐level learning outcomes, which has become more obvious in recent years. However, results should be interpreted with caution because of the high methodological diversity, statistical heterogeneity and risk of bias in the studies used. Future studies should have high methodological rigour, a standardised FC format and utilise assessment tools evaluating higher cognitive learning and behaviour change to further examine differences between FC and LB learning.
The authors’ meta‐analysis (46 studies, >9000 participants, health and non‐health science education) found flipped classrooms generally have significantly better learning outcomes than lecture learning, with a tendency for better outcomes for more recent studies.
Understanding the mechanisms that maintain microbial biodiversity is a critical aspiration in ecology. Past work on microbial coexistence has largely focused on species pairs, but it is unclear ...whether pairwise coexistence in isolation is required for coexistence in a multispecies community. To address this question, we conducted hundreds of pairwise competition experiments among the stably coexisting members of 12 different enrichment communities in vitro. To determine the outcomes of these experiments, we developed an automated image analysis pipeline to quantify species abundances. We found that competitive exclusion was the most common outcome, and it was strongly hierarchical and transitive. Because many species that coexist within a stable multispecies community fail to coexist in pairwise co-culture under identical conditions, we concluded that multispecies coexistence is an emergent phenomenon. This work highlights the importance of community context for understanding the origins of coexistence in complex ecosystems.
Fast charging/discharging rate and long life span render supercapacitors a potential candidate for the next generation energy supply. Nevertheless, the remaining wide gap between the ...basic/experimental research and practical requirements acts as the main barrier for further progress. In consequence, devising new techniques and platforms to well match the key and urgent requirements from a commercial/usable standpoint is highly desired. Specifically, although great progress has been made for the configuration of tailor-made electrode materials in terms of methodology and mechanisms, to meet the practical requirement, a bottleneck and urgent issue is to keep a decent performance when increasing the mass loading multi-times to the commercial level. Frustratingly, due to the greatly inhibited and worsened charge storage and ion migration dynamics, it is so challenging to reach this goal and it has confused researchers to a great extent up to now. In this review, we try to illustrate and clarify the involved fundamental principles for commercial-level mass-loading electrodes, including the analysis and evaluation of ion permeation/diffusion, charge transfer and redox reaction dynamics. Subsequently, we summarize and comment on the up-to-date key achievements and progress toward commercial-level mass-loading electrodes, which is divided into six branches: coupling with 3D conductive substrates, creating available pore channels, configuring hierarchical structures, aligning internal constructions by physical force/field, optimizing the properties by hetero-atoms/ions and engineering conductive MOFs. In parallel, some scientific perceptions and impressive concepts to facilitate the reaction dynamics are also highlighted. Moreover, concise outlooks/perspectives are presented here with an expectation to spark new ideas and endeavors for bringing supercapacitors into practical and daily-life applications.
This review decouples the fundamental mechanisms and bottleneck issues toward commercial-level mass-loading supercapacitors. Also, the involved impressive strategies and forward-looking perspectives are summarized and clarified.
Chemical modification of electrode materials by heteroatom dopants is crucial for improving storage performance in rechargeable batteries. Electron configurations of different dopants significantly ...influence the chemical interactions inbetween and the chemical bonding with the host material, yet the underlying mechanism remains unclear. We revealed competitive doping chemistry of Group IIIA elements (boron and aluminum) taking nickel‐rich cathode materials as a model. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen. Density functional theory calculations reveal, Al is preferentially bonded to oxygen and vice versa, and shows a much lower diffusion barrier than BIII. In the case of Al‐preoccupation, the bulk diffusion of BIII is hindered. In this way, a B‐rich surface and Al‐rich bulk is formed, which helps to synergistically stabilize the structural evolution and surface chemistry of the cathode.
A model study has been performed on Group IIIA element (boron and aluminum) co‐doped high‐nickel layered oxide cathode materials to understand competitive doping chemistry. A notable difference between the atomic radii of B and Al accounts for different spatial configurations of the hybridized orbital in bonding with lattice oxygen, resulting in the formation of a B‐rich surface and an Al‐rich bulk.
Abstract
Photocatalytic formation of hydrocarbons using solar energy via artificial photosynthesis is a highly desirable renewable-energy source for replacing conventional fossil fuels. Using an
l
...-cysteine-based hydrothermal process, here we synthesize a carbon-doped SnS
2
(SnS
2
-C) metal dichalcogenide nanostructure, which exhibits a highly active and selective photocatalytic conversion of CO
2
to hydrocarbons under visible-light. The interstitial carbon doping induced microstrain in the SnS
2
lattice, resulting in different photophysical properties as compared with undoped SnS
2
. This SnS
2
-C photocatalyst significantly enhances the CO
2
reduction activity under visible light, attaining a photochemical quantum efficiency of above 0.7%. The SnS
2
-C photocatalyst represents an important contribution towards high quantum efficiency artificial photosynthesis based on gas phase photocatalytic CO
2
reduction under visible light, where the in situ carbon-doped SnS
2
nanostructure improves the stability and the light harvesting and charge separation efficiency, and significantly enhances the photocatalytic activity.
Ammonia, as a significant chemical for fertilizer production and also a promising energy carrier, is mainly produced through the traditional energy-intensive Haber-Bosch process. Recently, the ...electrocatalytic N
2
reduction reaction (NRR) for ammonia synthesis has received tremendous attention with the merits of energy saving and environmental friendliness. To date, the development of the NRR process is primarily hindered by the competing hydrogen evolution reaction (HER), whereas the corresponding strategies for inhibiting this undesired side reaction to achieve high NRR selectivity are still quite limited. Furthermore, for such a complex reaction involving three gas-liquid-solid phases and proton/electron transfer, it is also rather meaningful to decouple and summarize the current strategies for suppressing H
2
evolution in terms of NRR mechanisms, kinetics, thermodynamics, and electrocatalyst design in detail. Herein, on the basis of the NRR mechanisms, we systematically summarize the recent strategies to inhibit the HER for a highly selective electrocatalytic NRR, focusing on limiting the proton- and electron-transfer kinetics, shifting the chemical equilibrium, and designing the electrocatalysts. Additionally, insights into boosting the NRR selectivity and efficiency for practical applications are also presented in detail with regard to the determination of ammonia, the activation of the N
2
molecule, the regulation of the gas-liquid-solid three-phase interface, the coupled NRR with value-added oxidation reactions, and the development of flow cell reactors.
This review underlines the strategies to suppress HER for selective NRR in view of proton-/electron-transfer kinetics, thermodynamics, and electrocatalyst design on the basis of deep understanding for NRR mechanisms.
We demonstrate high-performance, air-stable, low-temperature processed (≤100 °C) semitransparent (ST) perovskite solar cells (PSCs) by the applications of atomic layer deposition (ALD) technology to ...deposit ZnO and Al2O3 films as cathode buffer layer (CBL) and encapsulation layer, respectively. The application of ALD ZnO film as CBL in PSCs delivers several remarkable features, including fine-tunability of the work function of the electrode, low deposition temperature (80 °C), high charge selectivity, good electron-transporting ability (filed-effect mobility = 16.1 cm2 V–1 s–1), and excellent film coverage. With these desired interfacial properties, the device with opaque Ag electrode delivers high power conversion efficiency (PCE) up to 16.5%, greatly outperforming the device with state-of-the-art CBL ZnO nanoparticles film (10.8%). For ST PSCs employing Ag nanowires as transparent top electrode, a remarkable PCE of 10.8% with a corresponding average visible transmittance (AVT) of 25.5% is demonstrated, which represents the highest PCE ever reported for ST PSCs with similar AVT. More significantly, the insufficient ambient stability of ST device is significantly improved by employing excellent gas-barrier performance of ALD Al2O3-based encapsulation layer with an oxygen transmission rate of 1.9 × 10–3 cm3 m–2 day–1 and a water vapor transmittance rate of 9.0 × 10–4 g m–2 day–1.
Coupling urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) is an effective energy‐saving technique for hydrogen generation. However, exploring efficient bifunctional ...electrocatalysts under high current density is still challenging. Herein, hierarchical Fe doped cobalt selenide coupled with FeCo layered double hydroxide (Fe‐Co0.85Se/FeCo LDH) array as a self‐supported superior bifunctional heterojunction electrode is rationally designed for both UOR and HER. The unique heterostructure facilitates electron transfer and interface interactions through local interfacial Co‐Se/O‐Fe bonding environment modulation, improving reaction kinetics and intrinsic activity. As a result, the heterostructured electrocatalyst exhibits ultralow potentials of −0.274 and 1.48 V to reach 500 mA cm−2 for catalyzing the HER and UOR, respectively. Particularly, the full urea electrolysis system driven by Fe‐Co0.85Se/FeCo LDH delivers 300 mA cm−2 at a relatively low potential of 1.57 V, which is 150 mV lower than the conventional water electrolysis. The combination of in situ characterization and theoretical analysis reveal that the active sites with the adjustable electronic environment are induced by the interfacial bonding of the heterojunction, facilitating the water decomposition of HER and the stabilization of intermediates in UOR. This work inspires the interfacial environment modulation to optimize advanced electrocatalysts for energy‐saving H2 production.
The heterostructure constructed by Fe doped Co0.85Se and FeCo LDH can induce the modulation of local interfacial bonding environment and optimize the d‐band center to benefit the intermediates adsorption/desorption during urea oxidation reaction. As a result, a low cell voltage of 1.57 V at 300 mA cm−2 for urea water splitting is achieved based on the heterostructure.
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