Anthropogenic environments have been implicated in enrichment and exchange of antibiotic resistance genes and bacteria. Here we study the impact of confined and controlled swine farm environments on ...temporal changes in the gut microbiome and resistome of veterinary students with occupational exposure for 3 months. By analyzing 16S rRNA and whole metagenome shotgun sequencing data in tandem with culture-based methods, we show that farm exposure shapes the gut microbiome of students, resulting in enrichment of potentially pathogenic taxa and antimicrobial resistance genes. Comparison of students' gut microbiomes and resistomes to farm workers' and environmental samples revealed extensive sharing of resistance genes and bacteria following exposure and after three months of their visit. Notably, antibiotic resistance genes were found in similar genetic contexts in student samples and farm environmental samples. Dynamic Bayesian network modeling predicted that the observed changes partially reverse over a 4-6 month period. Our results indicate that acute changes in a human's living environment can persistently shape their gut microbiota and antibiotic resistome.
Herein we present a new viologen‐based radical‐containing metal–organic framework (RMOF) Gd‐IHEP‐7, which upon heating in air undergoes a single‐crystal‐to‐single‐crystal transformation to generate ...Gd‐IHEP‐8. Both RMOFs exhibit excellent air and water stability as a result of favorable radical‐radical interactions, and their long‐lifetime radicals result in wide spectral absorption in the range 200–2500 nm. Gd‐IHEP‐7 and Gd‐IHEP‐8 show excellent activity toward solar‐driven nitrogen fixation, with ammonia production rates of 128 and 220 μmol h−1 g−1, respectively. Experiments and theoretical calculations indicate that both RMOFs have similar nitrogen fixation pathways. The enhanced catalytic efficiency of Gd‐IHEP‐8 versus Gd‐IHEP‐7 is attributed to intermediates stabilized by enhanced hydrogen bonding.
A single‐crystal‐to‐single‐crystal (SCSC) transformation of stable radical‐containing MOF Gd‐IHEP‐7 generates Gd‐IHEP‐8. It is accompanied by a marked increase in efficiency of sacrificial agent‐free photocatalytic nitrogen fixation to yield NH3 from H2O and N2 under simulated solar light irradiation at ambient temperature. The NH3 production rate of 220 μmol h−1 g−1 for Gd‐IHEP‐8 is a new record for MOF photocatalysts.
In natural photosynthesis, the architecture of multiproteins integrates more chromophores than redox centers and simultaneously creates a well‐controlled environment around the active site. Herein, ...we demonstrate that these features can be emulated in a prototype hydrogen‐bonded organic framework (HOF) through simply varying the proportion of metalated porphyrin in the structure. Further studies demonstrate that changing the metalloporphyrin content not only realizes a fine tuning of the photosensitizer/catalyst ratio, but also alters the microenvironment surrounding the active site and the charge separation efficiency. As a result, the obtained material achieves the challenging overall CO2 reduction with a high HCOOH production rate (29.8 μmol g−1 h−1, scavenger free), standing out from existing competitors. This work unveils that the degree of metalation is vital to the catalytic activity of the porphryinic framework, presenting as a new strategy to optimize the performance of heterogeneous catalysts.
A biomimetic catalyst for efficient overall CO2 photoreduction was developed through self‐assembling porphyrins into a hydrogen‐bonded organic framework. The combination of more photosensitizers than redox centers in the structure allows for not only the adequate photon input and efficient use of photogenerated charge, but noticeable changes to the microenvironment surrounding active sites.
Visible‐light‐driven H2 production from pure water is highly promising but unfortunately inefficient. Herein, for the first time, we report the realization of pure‐water‐splitting H2 production under ...visible‐light irradiation via single‐component CdS without any cocatalysts, employing a piezoelectric‐photocatalysis strategy. Wurtzite CdS nanorod arrays that combine piezoelectric and visible‐light photocatalytic properties was in‐situ assembled on FTO substrates to harvest both solar energy and ultrasonic vibration energy in water. The ultrasound‐induced piezoelectric field in CdS drives the separation of photo‐generated charge carriers, leading to more facile water‐splitting for H2 evolution than that under visible‐light irradiation alone. The CdS nanorod arrays achieves a high H2 production rate of 20 μL.h−1 under optimized coupling field, which is much higher than that of unsupported samples. This work demonstrates the capability of piezoelectric photocatalysts to simultaneously convert visible light energy and acoustic energy into hydrogen energy, which may break a new ground for the design of energy‐conversion materials towards harvesting discrete ambient energy in urban environment.
Getting down to light and sound: Visible‐light H2 evolution from pure water is realized by CdS photocatalyst with the indispensable assistance of ultrasonic vibration. A new fundamental mechanism of synergetic photo‐sono‐catalysis is proposed and proved, that is, photo‐generated electrons and holes are efficiently separated and reversely enriched on the surface of CdS nanorods by the ultrasound‐induced internal piezoelectric field.
Under topological guidance, the self‐assembly process based on a tetratopic porphyrin synthon results in a hydrogen‐bonded organic framework (HOF) with the predicted square layers topology (sql) but ...unsatisfied stability. Strikingly, simply introducing a transition metal in the porphyrin center does not change the network topology but drastically causes noticeable change on noncovalent interaction, orbital overlap, and molecular geometry, therefore ultimately giving rise to a series of metalloporphyrinic HOFs with high surface area, and excellent stability (intact after being soaked in boiling water, concentrated HCl, and heated to 270 °C). On integrating both photosensitizers and catalytic sites into robust backbones, this series of HOFs can effectively catalyze the photoreduction of CO2 to CO, and their catalytic performances greatly depend on the chelated metal species in the porphyrin centers. This work enriches the library of stable functional HOFs and expands their applications in photocatalytic CO2 reduction.
Crystallographic and computational studies on a series of porphyrinic hydrogen‐bonded organic frameworks (HOFs) reveal that metallization of porphyrin centers greatly alters the orbital overlap of the adjacent porphyrin, the geometry of the molecule/layer, and the strength of noncovalent interactions. Therefore, metalloporphyrin HOFs exhibit much higher stability, surface area, and catalytic activity than metal‐free porphyrinic HOFs.
Cognitive decline remains an unaddressed problem for the elderly. We show that myelination is highly active in young mice and greatly inhibited in aged mice, coinciding with spatial memory deficits. ...Inhibiting myelination by deletion of Olig2 in oligodendrocyte precursor cells impairs spatial memory in young mice, while enhancing myelination by deleting the muscarinic acetylcholine receptor 1 in oligodendrocyte precursor cells, or promoting oligodendroglial differentiation and myelination via clemastine treatment, rescues spatial memory decline during aging.
•Free Cl− content in concrete was determined by embedded Cl− selective electrodes.•Penetration of free Cl− in carbonated or uncarbonated concrete follows Fick’s second law.•The ability of carbonation ...to resist penetration of Cl− is stronger than that to promote Cl−.•Concrete after carbonation has a higher risk of inducing steel corrosion.
The free Cl− diffusion law, binding Cl− capacity and long-term reliability of electrodes in concrete were investigated under the effects of carbonation. Results reveal that the diffusion of free Cl- in concrete with and without carbonation adheres to Fick’s second law. Reducing ratio of water to binder and adding mineral admixture can decrease the free Cl- diffusion coefficient. Although the ability of carbonation to resist the penetration of Cl- is stronger than that to promote Cl- erosion, concrete after carbonation has a higher risk of initiating steel corrosion. Improving the reliability and decreasing the cost of electrodes requires more research.
Alzheimer's disease (AD) is one of the most common causes of dementia and is characterized by gradual loss in memory, language, and cognitive function. The hallmarks of AD include extracellular ...amyloid deposition, intracellular neuronal fiber entanglement, and neuronal loss. Despite strenuous efforts toward improvement of AD, there remains a lack of effective treatment and current pharmaceutical therapies only alleviate the symptoms for a short period of time. Interestingly, some progress has been achieved in treatment of AD based on mesenchymal stem cell (MSC) transplantation in recent years. MSC transplantation, as a rising therapy, is used as an intervention in AD, because of the enormous potential of MSCs, including differentiation potency, immunoregulatory function, and no immunological rejection. Although numerous strategies have focused on the use of MSCs to replace apoptotic or degenerating neurons, recent studies have implied that MSC-immunoregulation, which modulates the activity state of microglia or astrocytes and mediates neuroinflammation via several transcription factors (NFs) signaling pathways, may act as a major mechanism for the therapeutic efficacy of MSC and be responsible for some of the satisfactory results. In this review, we will focus on the role of MSC-immunoregulation in MSC-based therapy for AD.
Display omitted
Elastic metal–organic materials (MOMs) capable of multiple stimuli‐responsiveness based on dual‐stress and thermally responsive triple‐helix coordination polymers are presented. The strong ...metal‐coordination linkage and the flexibility of organic linkers in these MOMs, rather than the 4 Å stacking interactions observed in organic crystals, causes the helical chain to act like a molecular spring and thus accounts for their macroscopic elasticity. The thermosalient effect of elastic MOMs is reported for the first time. Crystal structure analyses at different temperatures reveal that this thermoresponsiveness is achieved by adaptive regulation of the triple‐helix chains by fine‐tuning the opening angle of flexible V‐shaped organic linkers and rotation of its lateral conjugated groups to resist possible expansion, thus demonstrating the vital role of adaptive reorganization of triple‐helix metal–organic chains as a molecular spring‐like motif in crystal jumping.
Dual‐stress and thermally responsive crystalline metal–organic materials (MOMs) based on molecular spring‐like triple‐helix coordination polymers are presented. As the first example of thermosalient effect in elastic MOMs, these compounds undergo elastic flexure upon external stress as well as cracking and jumping after thermal treatment.
PDF
