A convenient and rapid detection method for methanol in ethanol remains a major challenge due to their indistinguishable physical properties. Herein, a novel fluorescence probe based on perovskite ...was successfully designed to overcome this bottleneck. We report a new zero‐dimensional (0D) hybrid perovskite of MP2InxSb1−xCl7 ⋅ 6 H2O (MP=2‐methylpiperazine) displaying an unusual green light emission with near‐unity photoluminescence quantum yield. Remarkably, this 0D perovskite exhibits reversible methanol‐response luminescence switching between green and yellow color but fail in any other organic vapors. Even for blended alcohol solutions, the luminescent probe exhibits excellent sensing performance with multiple superiorities of rapid response time (30 s) and ultra‐low detection limit (40 ppm), etc. Therefore, this 0D perovskite can be utilized as a perfect fluorescence probe to detect traces of methanol from ethanol with ultrahigh sensitivity, selectivity and repeatability. To the best of our knowledge, this work represents the first perovskite as fluorescence probe for methanol with wide potential in environmental monitoring and methanol detection, etc.
0D hybrid lead‐free halide displays highly efficient broadband green light emission with a near‐unity photoluminescence quantum yield, and acts as a unique fluorescence sensor for methanol in ethanol with ultrahigh selectivity, sensitivity and repeatability as well as fast response time.
Fusing the advantages of multiple acoustic features is important for the robustness of voice activity detection (VAD). Recently, the machine-learning-based VADs have shown a superiority to ...traditional VADs on multiple feature fusion tasks. However, existing machine-learning-based VADs only utilize shallow models, which cannot explore the underlying manifold of the features. In this paper, we propose to fuse multiple features via a deep model, called deep belief network (DBN). DBN is a powerful hierarchical generative model for feature extraction. It can describe highly variant functions and discover the manifold of the features. We take the multiple serially-concatenated features as the input layer of DBN, and then extract a new feature by transferring these features through multiple nonlinear hidden layers. Finally, we predict the class of the new feature by a linear classifier. We further analyze that even a single-hidden-layer-based belief network is as powerful as the state-of-the-art models in the machine-learning-based VADs. In our empirical comparison, ten common features are used for performance analysis. Extensive experimental results on the AURORA2 corpus show that the DBN-based VAD not only outperforms eleven referenced VADs, but also can meet the real-time detection demand of VAD. The results also show that the DBN-based VAD can fuse the advantages of multiple features effectively.
Between the sheets: Sodium‐ion batteries are an attractive, low‐cost alternative to lithium‐ion batteries. Nitrogen‐doped porous carbon sheets are prepared by chemical activation of ...polypyrrole‐functionalized graphene sheets. When using the sheets as anode material in sodium‐ion batteries, their unique compositional and structural features result in high reversible capacity, good cycling stability, and high rate capability.
Summary
Membrane vesicles (MVs) released from bacteria act as extracellular vehicles carrying various functional cargoes between cells. MVs with different cargoes play multiple roles in stress ...adaptation, nutrient acquisition and microbial interactions. However, previous studies have primarily focused on MVs from Gram‐negative bacteria, while the characteristics of cargoes in MVs from Gram‐positive bacteria and their involvement in microbial interactions remain to be elucidated. Here, we used a Gram‐positive strain, Dietzia sp. DQ12‐45‐1b from Corynebacteriales, to analyse the characteristics and functions of MVs. We identified the ‘antioxidant’ canthaxanthin is stored within MVs by LC–MS/MS. In addition, nearly the entire genomic content of strain DQ12‐45‐1b are evenly distributed in MVs, suggesting that MVs from DQ12‐45‐1b might involve in horizontal gene transfer. Finally, the mycobactin‐type siderophores were detected in MVs. The iron‐loaded MVs effectively mediate iron binding and delivery to homologous bacteria from the order Corynebacteriales, but not to more distantly related species from the orders Pseudomonadales, Bacillales and Enterobacterales. These results revealed that the iron‐loaded MVs are shared between homologous species. Together, we report the Gram‐positive bacterium Dietzia sp. DQ12‐45‐1b released MVs that contain canthaxanthin, DNA and siderophores and prove that MVs act as public goods between closely related species.
Keeping mammalian gastrointestinal (GI) tract communities in balance is crucial for host health maintenance. However, our understanding of microbial communities in the GI tract is still very limited. ...In this study, samples taken from the GI tracts of C57BL/6 mice were subjected to 16S rRNA gene sequence-based analysis to examine the characteristic bacterial communities along the mouse GI tract, including those present in the stomach, duodenum, jejunum, ileum, cecum, colon and feces. Further analyses of the 283,234 valid sequences obtained from pyrosequencing revealed that the gastric, duodenal, large intestinal and fecal samples had higher phylogenetic diversity than the jejunum and ileum samples did. The microbial communities found in the small intestine and stomach were different from those seen in the large intestine and fecal samples. A greater proportion of Lactobacillaceae were found in the stomach and small intestine, while a larger proportion of anaerobes such as Bacteroidaceae, Prevotellaceae, Rikenellaceae, Lachnospiraceae, and Ruminococcaceae were found in the large intestine and feces. In addition, inter-mouse variations of microbiota were observed between the large intestinal and fecal samples, which were much smaller than those between the gastric and small intestinal samples. As far as we can ascertain, ours is the first study to systematically characterize bacterial communities from the GI tracts of C57BL/6 mice.
Metal trimers M3(O/OH)(OOCR)6 are among the most important structural building blocks. From these trimers, a great success has been achieved in the design of 6‐ or 9‐connected framework materials ...with various topological features and outstanding gas‐sorption properties. In comparison, 8‐connected trimer‐based metal–organic frameworks (MOFs) are rare. Given multiple competitive pathways for the formation of 6‐ or 9‐connected frameworks, it remains challenging to identify synthetic or structural parameters that can be used to direct the self‐assembly process toward trimer‐based 8‐connected materials. Here, a viable strategy called angle bending modulation is revealed for creating a prototypical MOF type based on 8‐connected M3(OH)(OOCR)5(Py‐R)3 trimers (M = Zn, Co, Fe). As a proof of concept, six members in this family are synthesized using three types of ligands (CPM‐80, ‐81, and ‐82). These materials do not possess open‐metal sites and show excellent uptake capacity for various hydrocarbon gas molecules and inverse C2H6/C2H4 selectivity. CPM‐81‐Co, made from 2,5‐furandicarboxylate and isonicotinate, features selectivity of 1.80 with high uptake capacity for ethane (123 cm3 g−1) and ethylene (113 cm3 g−1) at 298 K and 1 bar.
A series of open‐metal‐site‐free metal–organic frameworks (MOFs) based on 8‐connected metal trimers is developed by using a synthetic strategy called angle bending modulation. Despite the absence of open metal sites as binding sites, these materials exhibit excellent ethane uptake capacity and high inverse C2H6/C2H4 separation selectivity.
Five new zero-dimensional hybrid manganese halides based on discrete MnCl
4
2−
tetrahedrons were prepared and used as highly efficient green-light emitters. Through rational management of organic ...cations to tailor the Mn Mn separation distances between neighboring MnCl
4
2−
tetrahedrons, the photoluminescence quantum yield increased significantly from 7.98% to 81.11%.
Five new zero-dimensional hybrid manganese halides based on discrete MnCl
4
2−
tetrahedrons were prepared and used as highly efficient green-light emitters.
Microbes spontaneously release membrane vesicles (MVs), which play roles in nutrient acquisition and microbial interactions. Iron is indispensable for microbes, but is a difficult nutrient to ...acquire. However, whether MVs are also responsible for efficient iron uptake and therefore involved in microbial interaction remains to be elucidated. Here, we used a Gram-positive strain, Dietzia sp. DQ12-45-1b, to analyze the function of its MVs in heme-iron recycling and sharing between species. We determined the structure and constituent of MVs and showed that DQ12-45-1b releases MVs originating from the mycomembrane. When comparing proteomes of MVs between iron-limiting and iron-rich conditions, we found that under iron-limiting conditions, heme-binding proteins are enriched. Next, we proved that MVs participate in extracellular heme capture and transport, especially in heme recycling from environmental hemoproteins. Finally, we found that the heme carried in MVs is utilized by multiple species, and we further verified that membrane fusion efficiency and species evolutionary distance determine heme delivery. Together, our findings strongly suggest that MVs act as a newly identified pathway for heme recycling, and represent a public good shared between phylogenetically closely related species.
The self‐assembly of three giant hexagonal 3d–4f metallocycles with inner diameters of 16.4, 16.5, and 16.4 Å, is described. Hexagonal metallocycles were stacked along the crystallographic c axis, ...producing unique hexagonal macroscopic tubular single crystals. The assembly mechanism of the tubular crystals was investigated. Remarkably, all three hexagonal metallocycles show typical single‐molecule magnet behavior, benefiting from the ferromagnetic couplings between the 3d and 4f ions.
Giant hexagonal hetero‐metallocycles with an inner diameter of 16.4 Å were designed and assembled into macroscopic tubular hollow crystals by a combination of dissolution and transformation processes.
Thermoelectric materials and their devices can realize the solid-state energy conversion between thermal and electrical energy, therefore serving as a promising alternative to conventional fossil ...fuels for energy supply. As one promising thermoelectric material, Ag2Se-based semiconductors exhibit considerably high thermoelectric performance at near-room temperatures and show considerable application potential in self-powering wearable electronics and solid-state refrigeration. Considering the fast development in Ag2Se-based thermoelectrics, a timely review for summarizing their progress, challenges, and outlook is of significance. In this review, we first focus on the fundamentals of Ag2Se, including its thermodynamics, crystal structures, band structures, liquid-like behaviors, and mechanical properties. Then, the advanced strategies employed in Ag2Se-based thermoelectric materials for improving their thermoelectric and mechanical properties are summarized. Besides, this review overviews the development of device designs from computational simulations, fabrication technology, and novel applications. In the end, we discuss the major controversies, challenges, and outlook for the future development of Ag2Se-based thermoelectrics.
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