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Resolving single-crystal structures of two-dimensional covalent organic frameworks (2D COFs) is a great challenge, hindered in part by limited strategies for growing high-quality crystals. A better understanding of the growth mechanism facilitates development of methods to grow high-quality 2D COF single crystals. Here, we take a different perspective to explore the 2D COF growth process by tracing growth intermediates. We discover two different growth mechanisms, nucleation and self-healing, in which self-assembly and pre-arrangement of monomers and oligomers are important factors for obtaining highly crystalline 2D COFs. These findings enable us to grow micron-sized 2D single crystalline COF Py-1P. The crystal structure of Py-1P is successfully characterized by three-dimensional electron diffraction (3DED), which confirms that Py-1P does, in part, adopt the widely predicted AA stacking structure. In addition, we find the majority of Py-1P crystals (>90%) have a previously unknown structure, containing 6 stacking layers within one unit cell. Resolving single-crystal structures of two-dimensional covalent organic frameworks (2D COFs) is a great challenge. Here, the authors identify two different growth mechanisms of COFs, enabling the growth and structure determination of micron-sized 2D single-crystalline COFs.

Refineries generally employ multiple energy-intensive distillation/adsorption columns to separate and purify complicated chemical mixtures. Materials such as multi-functional molecular separators integrating various modules capable of separating molecules according to their shape and chemical properties simultaneously may represent an alternative. Herein, we address this challenge in the context of one-step removal of alkynes and propadiene from cracking gases (up to 10 components) using a multi-functional and responsive material ZU-33 through a guest/temperature dual-response regulation strategy. The responsive and guest-adaptive properties of ZU-33 provide the optimized binding energy for alkynes and propadiene, and avoid the competitive adsorption of olefins and paraffins, which is verified by breakthrough tests, single-crystal X-ray diffraction experiments, and simulation studies. The responsive properties to different stimuli endow materials with multiple regulation methods and broaden the boundaries of the applicability of porous materials to challenging separations. Separating mixtures of hydrocarbons of low molecular weight is desirable but challenging. Here, the authors report a porous material with responsive and self-adaptive properties that enables one-step removal of alkynes and propadiene from cracking gases.

Mesenchymal stem cells (MSCs) are a common kind of multipotent cell in vivo, but their heterogeneity limits their further applications. To identify MSC subpopulations and clarify their relationships, we performed cell mapping of bone-marrow-derived MSCs through single-cell RNA (scRNA) sequencing. In our study, three main subpopulations, namely, the stemness subpopulation, functional subpopulation, and proliferative subpopulation, were identified using marker genes and further bioinformatic analyses. Developmental trajectory analysis showed that the stemness subpopulation was the root and then became either the functional subpopulation or the proliferative subpopulation. The functional subpopulation showed stronger immunoregulatory and osteogenic differentiation abilities but lower proliferation and adipogenic differentiation. MSCs at different passages or isolated from different donors exhibited distinct cell mapping profiles, which accounted for their corresponding different functions. This study provides new insight into the biological features and clinical use of MSCs at the single-cell level, which may contribute to expanding their application in the clinic.Stem cells: Three subpopulations found in bone marrowStem cells in the bone marrow are not all the same: a team led by Huiyong Shen and Yanfeng Wu from Sun Yat-sen University in Shenzhen, China, have identified three main subpopulations of adult stem cells in human marrow, a finding that could lead to more consistent and purer populations of cells for use in in clinical applications. The researchers analyzed gene expression profiles of mesenchymal stem cells (MSCs) using single-cell RNA sequencing methods. The genetic patterns pointed to three distinct cell subpopulations: one that maintained its stem-like capacity for self-renewal; a second “functional” group with strong bone- and blood-forming potential; and a third characterized by active proliferation and cell cycle progression. The authors propose that protocols that isolate only the functional subpopulation of cells could help reduce a source of variation that has limited the therapeutic efficacy of MSC-based therapies.

Growing evidence indicates that bone marrow-derived mesenchymal stem cells (BM-MSCs) enhance wound repair via paracrine. Because the extent of environmental oxygenation affects the innate characteristics of BM-MSCs, including their stemness and migration capacity, the current study set out to elucidate and compare the impact of normoxic and hypoxic cell-culture conditions on the expression and secretion of BM-MSC-derived paracrine molecules (e.g., cytokines, growth factors and chemokines) that hypothetically contribute to cutaneous wound healing in vivo. Semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) analyses of normoxic and hypoxic BM-MSCs and their conditioned medium fractions showed that the stem cells expressed and secreted significantly higher amounts of basic fibroblast growth factor (bFGF),vascular endothelial growth factor A (VEGF-A) interleukin 6 (IL-6) and interleukin 8 (IL-8) under hypoxic conditions. Moreover, hypoxic BM-MSC-derived conditioned medium (hypoCM) vs. normoxic BM-MSC-derived conditioned medium (norCM) or vehicle control medium significantly enhanced the proliferation of keratinocytes, fibroblasts and endothelial cells, the migration of keratinocytes, fibroblasts, endothelial cells and monocytes, and the formation of tubular structures by endothelial cells cultured on Matrigel matrix. Consistent with these in vitro results, skin wound contraction was significantly accelerated in Balb/c nude mice treated with topical hypoCM relative to norCM or the vehicle control. Notably increased in vivo cell proliferation, neovascularization as well as recruitment of inflammatory macrophages and evidently decreased collagen I, and collagen III were also found in the hypoCM-treated group. These findings suggest that BM-MSCs promote murine skin wound healing via hypoxia-enhanced paracrine.

The interactions between adsorbed gas molecules within porous metal-organic frameworks are crucial to gas selectivity but remain poorly explored. Here, we report the modulation of packing geometries of CO 2 and C 2 H 2 clusters within the ultramicroporous CUK-1 material as a function of temperature. In-situ synchrotron X-ray diffraction reveals a unique temperature-dependent reversal of CO 2 and C 2 H 2 adsorption affinities on CUK-1, which is validated by gas sorption and dynamic breakthrough experiments, affording high-purity C 2 H 2 (99.95%) from the equimolar mixture of C 2 H 2 /CO 2 via a one-step purification process. At low temperatures (<253 K), CUK-1 preferentially adsorbs CO 2 with both high selectivity (>10) and capacity (170 cm 3 g −1 ) owing to the formation of CO 2 tetramers that simultaneously maximize the guest-guest and host-guest interactions. At room temperature, conventionally selective adsorption of C 2 H 2 is observed. The selectivity reversal, structural robustness, and facile regeneration of CUK-1 suggest its potential for producing high-purity C 2 H 2 by temperature-swing sorption. Guest clusters within confined nanospaces have a significant impact on molecular recognition. Here authors highlight the potential to systematically control gas-cluster rearrangement, leading to tunable sorption and separation behaviour in a MOF.

Burn infection delays wound healing and increases the burn patient mortality. Consequently, a new dressing with antibacterial and anti‐inflammatory dual properties is urgently required for wound healing. In this study, we propose a combination of methacrylate gelatin (GelMA) hydrogel system with silver nanoparticles embed in γ‐cyclodextrin metal–organic frameworks (Ag@MOF) and hyaluronic acid‐epigallocatechin gallate (HA‐E) for the burn wound infection treatment. Ag@MOF is used as an antibacterial agent and epigallocatechin gallate (EGCG) has exhibited biological properties of anti‐inflammation and antibacterial. The GelMA/HA‐E/Ag@MOF hydrogel enjoys suitable physical properties and sustained release of Ag+. Meanwhile, the hydrogel has excellent biocompatibility and could promote macrophage polarization from M1 to M2. In vivo wound healing evaluations further demonstrate that the GelMA/HA‐E/Ag@MOF hydrogel reduces the number of the bacterium efficiently, accelerates wound healing, promotes early angiogenesis, and regulates immune reaction. A further evaluation indicates that the noncanonical Wnt signal pathway is significantly activated in the GelMA/HA‐E/Ag@MOF hydrogel treated group. In conclusion, the GelMA/HA‐E/Ag@MOF hydrogel could serve as a promising multifunctional dressing for the burn wound healing.

Background Researches have suggested that chronic sleep deprivation (SD) can lead to neurological dysfunction and facilitate the onset and progression of Parkinson’s disease (PD). However, the association between SD and PD remains unclear. Exosome (exo) cargo comprises microRNAs (miRNAs), which are potential regulators of PD. This study focused on assessing the role and related mechanisms of SD on PD. Methods SD plus 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice were used to investigate effects of SD on PD. Exos were extracted from plasma by polymer precipitation method. Impacts of exos on PD were validated through intervention in 1-methyl-4-phenylpyridinium (MPP + )-induced PD cells and MPTP-induced PD mice. Levels of miRNA in exos were analyzed by gene expression profile microarray. Levels of miR-150-5p in exos and substantia nigra pars compacta (SNpc) were further confirmed by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Target genes of miRNAs were predicted by TargetScan and confirmed by Dual-Luciferase Reporter Assay. Mimics and inhibitors of miR-150-5p were transfected into MPP + -induced PD cells, while agomir and antagomir of miR-150-5p were stereotaxic intracranial injected into SNpc of SD + MPTP-induced PD mice, enabling the determination of specific molecular mechanisms affecting PD. Results We found that SD and SD-derived exos aggravated PD-related damage. SD-derived exos were identified as potent inducers of PD. MiR-150-5p was recognized as a key element in SD-derived exos, and doublecortin-like kinase 1 (DCLK1) was confirmed as its target gene. Supplementing miR-150-5p alleviated PD damage by inhibiting DCLK1 and abnormal α-synuclein (α-syn) expression, decreasing reactive oxygen species (ROS), p62, cleaved-caspase-3 and cleaved-caspase-9 levels, and increasing Parkin and PINK1 levels and the LC3II/I ratio. Conclusion These findings suggested that miR-150-5p-dependent downregulation in SD-derived exos could aggravate the progression of PD via the DCLK1/α-syn pathway. MiR-150-5p decreased ROS levels, promoted mitophagy, and inhibited apoptosis, thus mitigating PD-related damage. These findings indicated that plasma-derived exos and their miRNA cargo might serve as therapeutic targets for PD, providing insights into a mechanism that links SD-related deterioration to the progression of PD.

In current timber structures, the low initial stiffness, and weak bending resistance of the connections result in significant structural deformation and failures. To improve the mechanical capabilities of timber structural joints, a novel timber-component anchorage system with robust bending resistance was introduced. Thirteen scaled-down specimens of glulam columns with anchored connections were meticulously fabricated for testing, scaled at a ratio of 1/2. Cyclic loading tests were conducted, considering three types of the volume compression percentage of confined wood perpendicular to the grain; and five axial-load levels. Subsequently, various seismic performance aspects of glulam columns with anchored connections were examined, including the failure mode, hysteresis behavior, envelope curve, strength degradation, stiffness degradation, energy dissipation capacity, and critical points. During the analysis, the influence of the P – Δ effect on the results was discussed and a damage-based hysteretic model was presented. Finally, a comparison of the mechanical performance for various types of timber structural joints was conducted. The findings revealed that the failure mode of the anchored glulam columns occurred as cracking perpendicular to the grain, and the anchored columns exhibited superior bending resistance and overall seismic performance.

In order to elucidate the influence of flame encapsulation thickness on the thermal response characteristics of concrete-filled steel tube columns in a fire environment, a study was conducted focusing on the primary control mechanism of heat radiation power from fire——the thickness of fire encapsulation. The thermal resistance effect at the interface between the steel tube and concrete, as well as the temperature rise characteristics of the flame, were comprehensively considered. A calculation method was established for the thermal response characteristics of concrete-filled steel tube columns under different flame encapsulation thickness conditions, providing support for the simulation of thermal response and temperature rise prediction of concrete-filled steel tube columns in fires. The results indicate that the flame emissivity and radiant heat power increase with the increase of flame encapsulation thickness. As the flame encapsulation thickness gradually increases, the growth trend of flame radiant power slows down. When the flame encapsulation thickness L < 1 m, the temperature rise rate of the concrete-filled steel tube column is significant. When the flame encapsulation thickness L ≥ 1 m, the temperature rise rate of the concrete-filled steel tube column tends towards a constant value.

To investigate the seismic performance of RC circular column strengthened with self-compacting concrete (SCC) -filled steel tubes (SCFST), nine specimens of height 1200 mm, varying with a cross-section shape of steel tube (external diameter: 218 mm, cross-section dimensions: 200 mm × 200 mm) were tested under axial load and cyclic lateral load. Three parameters, including the axial compression ratio, the cross-section shape of steel tube, and the embedding rebars ratio, were considered in the tests. The failure mode, hysteresis curves, skeleton curves, ductility, stiffness degradation, and energy-dissipation capacity were analysed. Experimental results showed that the bearing capacity and stiffness of the strengthened column were 5.4 and 9.08 times than that of the unstrengthened column respectively, and the improvement ratio of ductility and energy dissipation reached 123% and 85.7% respectively. The bearing capacity and stiffness of the square SCFST strengthened column was enhanced by 28.57% and 42.11% respectively, compared with the circular SCFST strengthened column. With the designed axial compression ratio increasing, the bearing capacity, initial stiffness, and energy dissipation capacity of strengthened columns increased by 17–39%, 21–60%, and 15–40% respectively, but the ductility coefficient decreased by 8.56–32.4%. The bearing capacity and energy dissipation of the specimen with an embedding rebars ratio of 0.06% increased by 7.5% and 9.31% respectively, but the ductility decreased by 12.81%. When the embedding rebars ratio was 0.1%, the reinforcement effect can be basically negligible.