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Lactic acid bacteria are indispensable functional microorganisms for cereal vinegar brewing, but cell activities are inhibited by the dominant acetic acid stress. Herein, an acetic-acid-tolerant strain isolated previously was identified as Pediococcus acidilactici, which also exhibited good resistance to other stresses during vinegar brewing. Proteomics analysis evidenced that differentially expressed proteins involved in the glycolysis and gluconeogenesis pathway, pyruvate metabolism, and sugar phosphotransferase system were all downregulated. Meanwhile, saturation of fatty acids and antioxidant enzymes was strengthened. The effects of several proteins on the resistance of P. acidilacticiand Lactobacillus lactisrelied on the types of strain and stress. AccA and AcpP participating in fatty acid metabolism and biosynthesis and Mnc related to stress response were found to protect cells by modifying fatty acid compositions and reinforcing the antioxidant defense system. Our works deepen the mechanisms of P. acidilacticiunder acetic acid and offer targets for engineering cell tolerance.

Phase transitions of materials are usually accompanied by a remarkable change of properties. Tracing and identifying the structural changes at the atomic scale is the key to understanding the fundamental mechanisms behind their performances. However, the direct observation of three-dimensional structural transformations in single nanocrystals has been rarely achieved. Herein we reported the development of an in situthree-dimensional electron diffraction (3D ED) approach for single nanocrystal structural analysis by combining 3D ED with in situtransmission electron microscopy. Each data set covering a crystal tilting range of 50° was collected in around 1 min at the set temperature using an in situheating holder. The feasibility of this protocol was proved by its successful application in investigating the metal–insulator transition (MIT) of vanadium dioxide (VO2) crystals with atomic precision. Moreover, local domains were found in the monoclinic phase before and after the annealing process, of which the orientations obey a 4-fold rotation symmetry along the a-axis.

Nonasil (NON-type framework) zeolite, having inner large cages but only 6-ring (R) apertures, is recognized as a nonporous material without practical application values as catalysts or adsorbents. A novel bottom-up structural construction strategy assisted with well-designed Gemini-type surfactant is proposed to “open” the noncages, constructing two novel NON-related structures with accessible and stable acid sites. The obtained derivant (named as ECNU-27) possessed hierarchical porosity with short-range ordered 8-R micropores and abundant intercrystal mesopores, serving as a promising catalyst for the 1-butene cracking to lower alkenes.

This vertically self-pillared (VSP) structure extends the application range of traditional porous materials with facile mass/ion transport and enhanced reaction kinetics. Here, we prepare a single crystal metal-organic framework (MOF), employing the ZIF-67 structure as a proof of concept, which is constructed by vertically self-pillared nanosheets (VSP-MOF). We further converted VSP-MOF into VSP-cobalt sulfide (VSP-CoS2) through a sulfidation process. Catalysis plays an important role in almost all battery technologies; for metallic batteries, lithium anodes exhibit a high theoretical specific capacity, low density, and low redox potential. However, during the half-cell reaction (Li++e=Li), uncontrolled dendritic Li penetrates the separator and solid electrolyte interphase layer. When employed as a composite scaffold for lithium metal deposition, there are many advantage to using this framework: 1) the VSP-CoS2substrate provides a high specific surface area to dissipate the ion flux and mass transfer and acts as a pre-catalyst, 2) the catalytic Co center favors the charge transfer process and preferentially binds the Li+with the enhanced electrical fields, and 3) the VSP structure guides the metallic propagation along the nanosheet 2D orientation without the protrusive dendrites. All these features enable the VSP structure in metallic batteries with encouraging performances.

The oriented growth between topologically distinct metal–organic frameworks (MOFs) opens new opportunities for accessing unique MOF-on-MOF structures and material properties. However, current examples only explored the growth of a guest MOF on the most thermodynamically favored crystal facet of a template MOF, which greatly limited the structural diversity. We report here the first example of sequential oriented growth of two cubic MOFs, UiO-66 and UiO-67, on a hexagonal MOF, MIL-96(Al). We found that UiO-66 crystals preferably grew on the top and bottom faces of MIL-96(Al) through its {111} facets and then on the less-favored side crystal faces through its {001} facets in order of priority. Interestingly, when UiO-66 was replaced by its isoreticular structural analogue, UiO-67, the growth sequence became dependent on the modulator concentration. At a low modulator concentration, the top and bottom faces of MIL-96(Al) were still the most favored growth sites for UiO-67, whereas at a high modulator concentration, the equatorial belt was the most preferred growth site. With a moderate amount of modulator, UiO-67 crystals can be found directionally grown on all three different exposed crystal facets of MIL-96(Al). Further analysis of the underlying lattice uncovered the delicate interplay between lattice mismatch and modulator adsorption at the MOF–MOF interface in determining the growth sequence and orientation of the MOF-on-MOF structures. This example highlights the potential of using sequential oriented growth on multiple crystal facets to access complex MOF-on-MOF structures.

We report a dual-interfacial engineering approach that uses a sub-20 nm polycrystalline MOF-74 shell as a transition phase to engineer the MOF–polymer interface. The application of a shell MOF layer divides the original single interface problem into two interfaces: MOF–MOF and MOF–polymer, which can be individually addressed. The greater external surface area created by the uneven MOF-74 shell containing high-density open metal sites allows the MOF to interact with 300% polymer at the interface compared to traditional MOF, thereby ensuring good interfacial compatibility. When applied on UiO-66-NH2, its respective mixed-matrix membranes exhibit a simultaneous increase of CO2/CH4separation selectivity and CO2permeability with increasing MOF loading, implying a defect-free interface. When applied on MOF-801, the mixed-matrix membranes exhibit an ethylene/ethane separation selectivity up to 5.91, a drastic 76% increase compared to that of the neat polymer owing to a “gas focusing” mechanism promoted by the preferred pore orientation in the MOF-74 layer. This represents one of the most selective ethylene/ethane separation membranes reported to date.

We report here a new technique for the identification and visualization of functional domains in stratified metal–organic frameworks (MOFs). The technique, namely, gold diffusion enabled domain identification, utilizes the diffusion of Au nanoparticles within MOF cavities to track and selectively stain the more Au-philic domain in an MOF particle thereby allowing direct observation of domains, determination of domain sequences, and, in certain cases, domain boundaries under transmission electron microscopy. This method is an excellent tool for studying MOF materials with complex domain hierarchy.

Propane dehydrogenation (PDH) reaction has emerged as one of the most promising propylene production routes due to its high selectivity for propylene and good economic benefits. However, the commercial PDH processes usually rely on expensive platinum-based and poisonous chromium oxide based catalysts. The exploration of cost-effective and ecofriendly PDH catalysts with excellent catalytic activity, propylene selectivity, and stability is of great significance yet remains challenging. Here, we discovered a new active center, i.e., an unsaturated tricoordinated cobalt unit (≡Si–O)CoO(O–Mo) in a molybdenum-doped silicalite-1 zeolite, which afforded an unprecedentedly high propylene formation rate of 22.6 molC3H6gCo–1h–1and apparent rate coefficient of 130 molC3H6gCo–1h–1bar–1with >99% of propylene selectivity at 550 °C. Such activity is nearly one magnitude higher than that of previously reported Co-based catalysts in which cobalt atoms are commonly tetracoordinated, and even superior to that of most of Pt-based catalysts under similar operating conditions. Density functional theory calculations combined with the state-of-the-art characterizations unravel the role of the unsaturated tricoordinated Co unit in facilitating the C–H bond-breaking of propane and propylene desorption. The present work opens new opportunities for future large-scale industrial PDH production based on inexpensive non-noble metal catalysts.

Cobalt‐based compounds have been extensively studied due to their relatively high theoretical capacity as anode materials for sodium‐ion batteries (SIBs). However, the requirement for strong conductivity and excellent cycling stability is still an urgent challenge for the energy‐storage system. To address these problems, metal–organic‐framework‐74‐derived porous rod‐shaped nanostructure Co/C materials are designed as advanced anode materials for SIBs, which is beneficial for the reaction kinetics of SIBs. Moreover, the efficient synergistic utility of the nanostructure and the rich mesopores of Co/C materials provides the ion‐diffusion paths and active sites for the transfer and storage of Na+, which contributes to the energy‐storage ability. The indurative structure of the carbonization electrode material can alleviate the influence of volume change due to Na+insertion/extraction. Therefore, the Co/C anode exhibits a high Coulombic efficiency of 94.3% at 0.1 A g−1. After 300 cycles, the Na+‐storage capacity is 200.4 mAh g−1, and the Coulombic efficiency is 99.0%, where the capacity retention rate is up to 88.2%. Herein, insight is provided into the role of porous Co/C material in improving the kinetics of Na+reaction, supplying an effective strategy for the rational design of key materials for high‐performance rechargeable batteries. Here, metal–organic‐framework‐74‐derived porous rod‐shaped Co/C is prepared as the anode materials for sodium‐ion batteries, which has rich mesopore and large number of unsaturated active sites, contributing to improve the sodium‐storage capacity. In addition, the Co/C obtained by high‐temperature calcination has a stable structure, which greatly alleviates the effects of volume change during Na+insertion/extraction.

The uncontrolled deposition/dissolution process of lithium dendrites during electrochemical cycling in batteries limits the large-scale application of Li metal anodes. Investigating the microstructure of Li dendrites is a focal point. Currently, the only way to protect and observe sensitive Li dendrites is through low-temperature transmission electron microscopy (LT-TEM), whereas room-temperature characterization is still lacking. In this work, the room-temperature microstructure of Li dendrites was obtained by TEM using both vacuum- and inert-gas-transfer methods. Detailed comparison between LT- and room-temperature (RT-)TEM characterizations was provided to show the pros and cons of each method. Especially, RT-TEM shows the advantage of flexible incorporation with multifunctional characterizations, such as 3D tomography. By using RT-TEM, microstructural evolution of Li dendrites during the electrodeposition/dissolution process, including increase of the quantity of inorganic Li2O compounds in the solid electrolyte interphase, lateral growth behavior, and two types of inactive Li, has been revealed, enriching the understanding of the structure–property relationship of Li dendrites.