Herein we describe a mild method for the dual C(sp3)−H bond functionalization of saturated nitrogen‐containing heterocycles through a sequential visible‐light photocatalyzed dehydrogenation/2+2 ...cycloaddition procedure. As a complementary approach to the well‐established use of iminium ion and α‐amino radical intermediates, the elusive cyclic enamine intermediates were effectively generated by photoredox catalysis under mild conditions and efficiently captured by acetylene esters to form a wide array of bicyclic amino acid derivatives, thus enabling the simultaneous functionalization of two vicinal C(sp3)−H bonds.
A great team: A dual C(sp3)−H bond functionalization strategy was developed by merging dehydrogenation under visible‐light photocatalysis with a 2+2 cycloaddition reaction in a sequential process. This method enabled cyclobutene rings to be fused to various saturated nitrogen‐containing heterocycles to produce a series of cyclic amino acid derivatives.
An artificial while very stable solid electrolyte interphase film is formed on lithium metal using an electrochemical strategy. When this protected Li anode is first used in a Li–O2 battery, the film ...formed on the anode can effectively suppress the parasitic reactions on the Li anode/electrolyte interface and significantly enhance the cycling stability of the Li–O2 battery.
We present a novel clustering objective that learns a neural network classifier from scratch, given only unlabelled data samples. The model discovers clusters that accurately match semantic classes, ...achieving state-of-the-art results in eight unsupervised clustering benchmarks spanning image classification and segmentation. These include STL10, an unsupervised variant of ImageNet, and CIFAR10, where we significantly beat the accuracy of our closest competitors by 6.6 and 9.5 absolute percentage points respectively. The method is not specialised to computer vision and operates on any paired dataset samples; in our experiments we use random transforms to obtain a pair from each image. The trained network directly outputs semantic labels, rather than high dimensional representations that need external processing to be usable for semantic clustering. The objective is simply to maximise mutual information between the class assignments of each pair. It is easy to implement and rigorously grounded in information theory, meaning we effortlessly avoid degenerate solutions that other clustering methods are susceptible to. In addition to the fully unsupervised mode, we also test two semi-supervised settings. The first achieves 88.8% accuracy on STL10 classification, setting a new global state-of-the-art over all existing methods (whether supervised, semi-supervised or unsupervised). The second shows robustness to 90% reductions in label coverage, of relevance to applications that wish to make use of small amounts of labels. github.com/xu-ji/IIC.
Every institution in China has undergone reform and piloting based on its unique situation to enhance the quality of instruction as a result of the ongoing advancement of the times and the ...educational idea in the information age. The effectiveness of education is increased by hybrid teaching, which combines offline and online approaches. It empowered educators and motivates learners to take responsibility for their learning. Classes in physical education (PE) that place a strong emphasis on training and technical performance are especially well-suited for hybrid instruction. This mode improves teaching abilities and supports the long-term growth of education. As a result, we offer an online and offline technique for assessing the quality of PE instruction that is relied on mobile edge computing (MEC). With the use of the target, index, weight, and standard assessments, this study builds a quality evaluation index (QEI) approach for PE that combines online and offline techniques. Assessing the corresponding significance of every index, factor, and cluster analysis compresses index elements. The weights of the QEIs for integrated instruction are determined using MEC. The efficacy of combined PE is assessed using the fuzzy logic-based comprehensive assessment methodology. According to the analytical model, this strategy increases teaching quality while reducing costs and mistakes and improves assessment effectiveness. The experimental results proved that the proposed model has provided an accuracy of 95.98%.
•Effects of berberine and metformin were evaluated in db/db obese T2DM mice.•Both berberine and metformin reduced food intake and promoted weight loss.•Both treatments reduced blood glucose, HbA1c, ...and LPS levels.•The drugs relieved intestinal inflammation and repaired intestinal barrier structure.•The effects of berberine and metformin are exerted via the gut microbiome.
Berberine and metformin, both established pharmaceutical agents with herbal origins, have incidental beneficial effects on multiple diseases, including diabetes. These effects have been speculated to occur via the gut microbiome. In this study, we administered either berberine or metformin to db/db mice and investigated changes in body weight, food intake, and blood glucose levels. Fresh stool samples were analyzed using 16 s rDNA high-throughput sequencing to evaluate the gut microbiome. Short-chain fatty acids (SCFA) in the stool were quantified using gas chromatography. The expression of NF-κB signaling pathway and tight junction (ZO1 and occludin) proteins in the intestinal epithelium was determined using qPCR and western blotting. The intestinal barrier structure was examined using transmission electron microscopy and serum lipopolysaccharide (LPS) was measured using a commercial kit. Both berberine and metformin reduced food intake, body weight, and blood glucose and HbA1c levels. Both treatments effectively restored the intestinal SCFA content, reduced the level of serum LPS, relieved intestinal inflammation, and repaired intestinal barrier structure. Intervention with metformin or berberine modified the gut microbiome in db/db mice, increasing the number of SCFA-producing bacteria (e.g., Butyricimonas, Coprococcus, Ruminococcus) and reducing opportunistic pathogens (e.g., Prevotella, Proteus). An increased abundance of other probiotics including Lactobacillus and Akkermansia was also observed. Berberine and metformin can modulate the composition of the gut microbiome and reduce body weight, blood glucose levels, and intestinal inflammation in db/db mice, which demonstrates their effectiveness in the reduction of diabetic complications in this model.
A photoinduced flexible Li‐CO2 battery with well‐designed, hierarchical porous, and free‐standing In2S3@CNT/SS (ICS) as a bifunctional photoelectrode to accelerate both the CO2 reduction and ...evolution reactions (CDRR and CDER) is presented. The photoinduced Li‐CO2 battery achieved a record‐high discharge voltage of 3.14 V, surpassing the thermodynamic limit of 2.80 V, and an ultra‐low charge voltage of 3.20 V, achieving a round trip efficiency of 98.1 %, which is the highest value ever reported (<80 %) so far. These excellent properties can be ascribed to the hierarchical porous and free‐standing structure of ICS, as well as the key role of photogenerated electrons and holes during discharging and charging processes. A mechanism is proposed for pre‐activating CO2 by reducing In3+ to In+ under light illumination. The mechanism of the bifunctional light‐assisted process provides insight into photoinduced Li‐CO2 batteries and contributes to resolving the major setbacks of the system.
Battery life on Mars: A photoinduced flexible Li‐CO2 battery with hierarchical, porous, and free‐standing In2S3@CNT/SS as a bifunctional photoelectrode to accelerate both CO2 reduction and evolution is presented. The Li‐CO2 battery achieved a record‐high discharge voltage of 3.14 V (thermodynamic limit: 2.80 V), and an ultra‐low charge voltage of 3.20 V, and a roundtrip efficiency of 98.1 %.
Summary
Background
Early detection of melanoma is essential to reduce mortality. Total body photography (TBP) can facilitate the detection of melanoma in high‐risk individuals. However, the accuracy ...of TBP in diagnosing melanoma remains unclear.
Objectives
To determine the diagnostic accuracy of TBP for the detection of melanoma in adults.
Methods
MEDLINE, Embase, Cochrane and Centre for Reviews databases were searched from inception to 26 May 2020. Studies that included TBP for diagnosing melanoma with at least one follow‐up appointment were eligible for inclusion in the systematic review if they provided data to calculate at least one diagnostic accuracy measure. Two authors independently screened articles, extracted data and assessed quality. Disagreements were resolved by a third reviewer.
Results
In total, 10 studies were included, comprising 41 703 patients who underwent TBP and 6203 biopsies. Melanoma in situ (MIS) was diagnosed in 315 (5·1%) lesions and invasive melanoma was diagnosed in 187 (3·0%) lesions biopsied. Summary estimates for TBP in diagnosing melanoma were calculated as follows: mean percentage of biopsies positive for MIS or melanoma was 15% 95% confidence interval (CI) 10–21, number needed to biopsy (NNB) was 8·6 (range 2·3–19·6), naevus : melanoma ratio was 7·6 (range 1·3–18·6), and MIS : melanoma ratio was 1·7 (1·0–3·5). Regression analysis showed a negative correlation between NNB and MIS : melanoma ratio.
Conclusions
Available data regarding the diagnostic accuracy of TBP are heterogeneous, owing to variability in the risk profile of cohorts and TBP protocols. Best current estimates suggest that TBP for diagnosing melanoma has an acceptable NNB in high‐risk patients. However, prospective diagnostic test accuracy studies are needed to gauge the diagnostic accuracy of TBP.
What is already known about this topic?
Early detection of melanoma is essential to reduce morbidity and mortality.
Total body photography (TBP) can facilitate the detection of melanoma in high‐risk individuals.
The accuracy of TBP in diagnosing melanoma is unknown.
What does this study add?
Best current estimates suggest that the use of TBP for the diagnosis of melanoma has an acceptable number needed to biopsy in patients at high risk of melanoma.
There is heterogeneity in the design and delivery of studies evaluating TBP in high‐risk patients.
There is a need for robustly designed prospective diagnostic test accuracy studies, in order to assess the diagnostic accuracy of TBP.
Linked Comment: H. Kittler. Br J Dermatol 2021; 185:241.
Plain language summary available online
Lithium-oxygen batteries with ultrahigh energy density have received considerable attention as of the future energy storage technologies. The development of effective electrocatalysts and a ...corresponding working mechanism during cycling are critically important for lithium-oxygen batteries. Here, a single cobalt atom electrocatalyst is synthesized for lithium-oxygen batteries by a polymer encapsulation strategy. The isolated moieties of single atom catalysts can effectively regulate the distribution of active sites to form micrometre-sized flower-like lithium peroxide and promote the decomposition of lithium peroxide by a one-electron pathway. The battery with single cobalt atoms can operate with high round-trip efficiency (86.2%) and long-term stability (218 days), which is superior to a commercial 5 wt% platinum/carbon catalyst. We reveal that the synergy between a single atom and the support endows the catalyst with excellent stability and durability. The promising results provide insights into the design of highly efficient catalysts for lithium-oxygen batteries and greatly expand the scope of future investigation.
Although flexible power sources are crucial for the realization next-generation flexible electronics, their application in such devices is hindered by their low theoretical energy density. ...Rechargeable lithium-oxygen (Li-O2) batteries can provide extremely high specific energies, while the conventional Li-O2 battery is bulky, inflexible and limited by the absence of effective components and an adjustable cell configuration. Here we show that a flexible Li-O2 battery can be fabricated using unique TiO2 nanowire arrays grown onto carbon textiles (NAs/CT) as a free-standing cathode and that superior electrochemical performances can be obtained even under stringent bending and twisting conditions. Furthermore, the TiO2 NAs/CT cathode features excellent recoverability, which significantly extends the cycle life of the Li-O2 battery and lowers its life cycle cost.
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