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20S-protopanaxatriol (PPT) might be a potential candidate to treat Alzheimer's disease-related cognitive decline via enhancing endogenous neurogenesis.

Background: Asthma is a chronic inflammatory airway disease that causes damage to and exfo-liation of the airway epithelium. The continuous damage to the airway epithelium in asthma cannot be repaired quickly and generates irreversible damage, repeated attacks, and aggravation. Vitamin A (VA) has multifarious biological functions that include maintaining membrane stability and integrity of the structure and function of epithelial cells. Our research explored the role of VA in repairing the airway epithelium and provided a novel treatment strategy for asthma. Methods: A mouse asthma model was established by house dust mite (HDM) and treated with VA by gavage. Human bronchial epithelial (16HBE) cells were treated with HDM and all-trans retinoic acid (ATRA) in vitro. We analyzed the mRNA and protein expression of characteristic markers, such as acetyl-α-tubulin (Ac-TUB) and FOXJ1 in ciliated cells and MUC5AC in secretory cells, mucus secretion, airway inflammation, the morphology of cilia, and the integrity of the airway epithelium. Results: Findings showed destruction of airway epithelial integrity, damaged cilia, high mucus secretion, increased MUC5AC expression, and decreased Ac-TUB and FOXJ1 expression in asth-matic mice. The VA intervention reversed the effect on Ac-TUB and FOXJ1 and promoted ciliated cells to repair the damage and maintain airway epithelial integrity. In 16HBE cells, we could confirm that ATRA promoted the expression of Ac-TUB and FOXJ1. Conclusion: These results demonstrated that VA-regulated ciliated cells to repair the damaged airway epithelium caused by asthma and maintain airway epithelial integrity. VA intervention is a potential adjunct to conventional treatment for asthma.

In this work, ferroferric oxide (Fe3O4) microspheres with a diameter of ~ 150 nm were in situ grown on the surface of graphene oxide (GO) to obtain GO@Fe3O4 hybrids. Then, novel PMIA/CF/GO@Fe3O4 electromagnetic shielding composites have been developed with a simple and efficient paper-making method using poly(m-phenylene isophthalamide) (PMIA) fibers as matrix and carbon fiber (CF) and GO@Fe3O4 as fillers. Due to the introduction of GO@Fe3O4 and a large number of voids into the materials, the obtained PMIA/CF/GO@Fe3O4 composites exhibit good magnetic sensitivity and low density. Besides, the obtained PMIA/CF/GO@Fe3O4 composites with 10 wt% GO@Fe3O4 loading shows outstanding EMI-shielding effectiveness (EMI SE) of 42.55–46.98 dB at 8–12 GHz, and as the content of GO@Fe3O4 increases to 30 wt%, the EMI SE increases to 55.22 to 60.23 dB. The EMI SE of the PMIA/CF/GO@Fe3O4 composites is far more than the target value (20 dB) required by practical application. Thus, it provides a path to obtain a new class of high-performance and lightweight PMIA-based composites for enhanced shielding of electromagnetic pollution.

Single-atom catalysts (SACs) exhibit excellent performance for various catalytic reactions but it is still challenging to have adequate total activity for practical applications. Here we report the high-valence, square planar Pt1–O4 as an active site that enables significantly to increase the total activity of the Pt1/Fe2O3 SAC with a Pt loading of only ∼30 ppm, which is similar to that of a 1.0 wt% nano-Pt/Fe2O3, for CO oxidation at 350 °C. Density functional theory calculations reveal that Pt1–O4 catalyzes CO oxidation through a non-classical Mars–van Krevelen mechanism. The adsorbed O2 on Pt1 atoms activates the coordination oxygen in the Pt1–O4 configuration, and then a barrierless O2 dissociation occurs on the Pt1–Fe2 triangle to replenish the consumed coordination oxygen by the cooperative action of Pt 5d and Fe 3d electrons. This work provides a new fundamental understanding of oxidation catalysis on stable and active SACs, providing guidance for rationally designing future heterogeneous catalysts.

Bimetallic nanocrystals often outperform their monometallic counterparts in catalysis as a result of the electronic coupling and geometric effect arising from two different metals. Here we report a...

In this work, a series of fluorene-containing fluorinated polyethersulfone (PES-6AF/BHPF) copolymers with high temperature resistance and intrinsic low dielectric constant (low-e) have been designed and synthesized from 4,4′-dichlorophenyl sulfone (DCS) and polyphenol. The performance of obtained PES-6AF/BHPF can be controlled and optimized by controlling the copolymers structure. The thermal and dielectric properties of PES-6AF/BHPF were evaluated comprehensively. The obtained PES-6AF/BHPF copolymers show high glass transition temperatures (Tg) ranging from 200 to 260 °C, and 5% weight loss temperatures (Td5%) is stable up to 500 °C. The e value of PES-6AF/BHPF-0% and PES-6AF/BHPF-100% are as low as 2.1 and 2.3, and the loss tangent (tan δ) are only 0.0088 and 0.003 at 1 kHz, respectively. In addition, all of PES-6AF/BHPF films show good stability of dielectric properties in high temperature conditions. More importantly, the PES-6AF/BHPF copolymers are soluble in common solvents (such as DMAc, NMP, DMF, THF). The PES-6AF/BHPF copolymers are amorphous and can be easily cast into transparent and flexible films with tensile strength of 62–74 MPa and an elongation at break of 13.3–15.8%. The outstanding comprehensive properties made it possible to be the most promising polymer candidates for high-performance interlayer dielectrics.

Early recognition of severe clinical outcomes in children with pneumonia-related bacteremia is vitally important because of the high mortality. This study aims to explore risk factors for severe clinical outcomes in children with pneumonia-related bacteremia and evaluate the value of time to first positive blood cultures (TTFP) in predicting prognosis. Children with pneumonia-related bacteremia in Children's Hospital of Chongqing Medical University were included (January 2013-May 2019), respectively. TTFP and clinical parameters were collected and analyzed. The area under the curve (AUC)-receiver operating characteristic was used to evaluate the discrimination ability of TTFP. Multivariate logistic regression tests were performed to evaluate the association between TTFP and severe clinical outcomes. A total of 242 children with pneumonia-related bacteremia were included. The least absolute shrinkage and selection operator (LASSO) regression analysis identified TTFP, serum albumin (ALB) and lactic dehydrogenase (LDH) as predictors of in-hospital mortality. Multivariate logistic regression analysis showed that shorter TTFP (OR 0.94; 95% CI 0.89 to 0.97; p

Author: Please verify that the changes made to improve the English still retain your original meaning.Here, we report that a cationic bimetallic site consisting of one Pd and three Zn atoms (Pd1Zn3...

Exclusive Pt species supported on inert substrates have not achieved satisfactory performance for cryogenic CO oxidation because of the constraint of the competitive Langmuir–Hinshelwood process in...

Herein, we report a theoretical and experimental study of the water-gas shift (WGS) reaction on Ir1 /FeOx single-atom catalysts. Water dissociates to OH* on the Ir1 single atom and H* on the first-neighbour O atom bonded with a Fe site. The adsorbed CO on Ir1 reacts with another adjacent O atom to produce CO2 , yielding an oxygen vacancy (Ovac ). Then, the formation of H2 becomes feasible due to migration of H from adsorbed OH* toward Ir1 and its subsequent reaction with another H*. The interaction of Ir1 and the second-neighbouring Fe species demonstrates a new WGS pathway featured by electron transfer at the active site from Fe3+ -O⋅⋅⋅Ir2+ -Ovac to Fe2+ -Ovac ⋅⋅⋅Ir3+ -O with the involvement of Ovac . The redox mechanism for WGS reaction through a dual metal active site (DMAS) is different from the conventional associative mechanism with the formation of formate or carboxyl intermediates. The proposed new reaction mechanism is corroborated by the experimental results with Ir1 /FeOx for sequential production of CO2 and H2 .

Identifying the activity origin of noble-metal-based catalysts is extremely important for fundamental research and practical application. We report that single Au atoms on Co3O4 (Au1/Co3O4 single-a...

The fact that supported single metal atoms can do catalysis provides unparalleled opportunities to develop innovative technologies for a sustainable and greener chemical industry. Single-atom catalysts not only maximize the utilization efficiency of expensive metals of rare resources but also have a great potential to significantly improve selectivity of the targeted catalytic reactions and lower the operation cost. This short review highlights the recent progress of understanding the nature of single-atom catalysts and their applications with a focus on major challenges encountered in heterogeneous catalysis such as carbon dioxide conversion, production of hydrogen, ammonia synthesis, and methane valorization.

Li metal is regarded as the best candidate for anode materials because of its high theoretical capacity and negative electrode potential. However, due to the continuous parasitic side reactions and messy growing Li dendrites, the practical use of the Li metal as an anode is seriously limited. An in situ formed artificial solid electrolyte interface (SEI) can commendably solve the above-mentioned problems; however, inevitable cracks and fractures are found during their long-term service due to the existence of inorganic compounds (or alloys) in the artificial-SEI. Herein, a self-repairing alloy for protecting the Li metal anode was prepared via a facile in situ reaction. A long-term cycling life of more than 1800 h and 1400 h was obtained for the self-repairing alloy protected Li metal anode at a practical current density of 2 mA cm−2 and 5 mA cm−2. Even after increasing the deposition capacity to 15 mA h cm−2, no dendrite formation was detected in the self-repairing alloy protective Li anode. This is expected to be a promising strategy in achieving a stable Li metal anode/electrolyte interface and providing a new way of thinking for the development of Li metal batteries.

We report the effect of in situ transforming ZnO supported single Au atoms to 3-dimensional Au clusters (Au3D) on room temperature CO oxidation activity. We discovered that an intermediate, highly distorted 2-dimensional Au layer species is much more active than both the Au3D clusters and the Au single atoms. The geometric arrangement of Au clusters and their interactions with support surfaces play a pivotal role in determining their catalytic performance in room temperature CO oxidation on ZnO supported Au catalysts.

Tracheobronchomalacia (TBM) is often manifested as wheezing. Reassessing the role of TBM in persistent wheezing in children is essential.We selected children who were diagnosed with TBM by bronchoscopy and who underwent bronchoscopic reexamination for persistent wheezing or chronic cough between January 2009 and July 2019. The clinical and bronchoscopy data were collected and retrospectively reviewed. For statistical analysis, we used the Kaplan-Meier method, Kruskal-Wallis test, and Fisher exact test.A total of 79 patients (57 males and 22 females) were included. The median age of the first TBM diagnosis was 7 (interquartile [IQR] 4-11) months. The median age of the first wheezing episode was 4 (IQR 3-7) months. During the time interval between the two bronchoscopies, malacia lesions resolved in 50 patients (63.3%), improvement was seen in 14 patients (17.7%), no change was observed in 11 patients (13.9%), and the condition was aggravated in 4 patients (5.1%). The malacia lesions in 37 patients resolved before 2 years of age. Among the 50 resolved patients, 22 patients (44.0%) reported wheezing three times or more between bronchoscopy evaluations, and 13 of these 22 patients (59.1%) with atopy or family history of allergic diseases were ultimately diagnosed with bronchial asthma.In children with persistent wheezing, the role of TBM should be reassessed, especially in those with atopy or family history of allergic diseases, and bronchial asthma should be considered early.

CO oxidation is of great importance in both fundamental study and industrial application. Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost. Single-atom catalysts (SACs) can maximize the metal atom efficiency. Herein, ZnO nanowire (ZnO-nw) supported Rh, Au, and Pt SACs were successfully developed to investigate their CO oxidation performance. Interestingly, it was found that Rh1/ZnO-nw showed much higher activity than the other noble metals which are usually regarded as good candidates for CO oxidation. In addition, the Rh SAC possessed high stability in high-temperature CO oxidation under simulated conditions in the presence of water and hydrocarbons. The high activity and stability make Rh1/ZnO-nw promising for practical applications, especially in the automotive exhaust emission control. Theoretical calculations indicate that the CO oxidation proceeds via the Mars-van Krevelen mechanism and the lowest barrier for the rate-limiting O2 dissociation at a surface oxygen vacancy site is a key factor in determining the observed highest activity of Rh1/ZnO-nw amongst the studied SACs.

Astrocyte, the most abundant cell type in the central nervous system, is increasingly recognized and is thought to depend on curial and diverse roles in maintaining brain homeostasis, the blood-brain barrier, ion homeostasis, secrete neurotrophic factors and regulate synaptic transmission which is essential to tune individual-to-network neuronal activity. Senescence in astrocytes has been discovered to be an important contributor to several age-related neurological diseases like Alzheimer's and Parkinson's disease. However, the latest research about astrocytes from aged subjects or aged astrocytes in vitro is not yet adequate to be well elucidated on their curial process in the regulation of brain function. In this study, an in vitro cell model of aged astrocytes was constructed by serial passaging until passage 20-25, and those passages within 1-5 were used as young astrocytes. Meanwhile, oxidative induced astrocyte senescence model was also constructed by H2O2 induction. Our results indicate that after serial passaging or oxidative stress-induced astrocytes, all showed manifest changes in several established markers of cellular senescence like P53, P21, the release of inflammatory cytokine IL-6 and SA-β-gal positive cells. Results also showed mitochondrial dysfunction in the oxidative stress-induced astrocyte senescence model and treatment of berberine could reverse these alterations. What’s more interests us is that those two types of senescent astrocytes’ conditioned medium co-cultured with neuronal cells could do impact on neuron apoptosis no matter in direct or indirect ways. This study may help us better understand the fundamental role of astrocyte senescence on the regulation of normal and pathological brain aging.

Single-atom catalysts (SACs) exhibit unique catalytic property and maximum atom efficiency of rare, expensive metals. A critical barrier to applications of SACs is sintering of active metal atoms under operating conditions. Anchoring metal atoms onto oxide supports via strong metal-support bonds may alleviate sintering. Such an approach, however, usually comes at a cost: stabilization results from passivation of metal sites by excessive oxygen ligation—too many open coordination sites taken up by the support, too few left for catalytic action. Furthermore, when such stabilized metal atoms are activated by reduction at elevated temperatures they become unlinked and so move and sinter, leading to loss of catalytic function. We report a new strategy, confining atomically dispersed metal atoms onto functional oxide nanoclusters (denoted as nanoglues) that are isolated and immobilized on a robust, high-surface-area support—so that metal atoms do not sinter under conditions of catalyst activation and/or operation. High-number-density, ultra-small and defective CeOx nanoclusters were grafted onto high-surface-area SiO2 as nanoglues to host atomically dispersed Pt. The Pt atoms remained on the CeOx nanoglue islands under both O2 and H2 environment at high temperatures. Activation of CeOx supported Pt atoms increased the turnover frequency for CO oxidation by 150 times. The exceptional stability under reductive conditions is attributed to the much stronger affinity of Pt atoms for CeOx than for SiO2—the Pt atoms can move but they are confined to their respective nanoglue islands, preventing formation of larger Pt particles. The strategy of using functional nanoglues to confine atomically dispersed metal atoms and simultaneously enhance catalytic performance of localized metal atoms is general and takes SACs one major step closer to practical applications as robust catalysts for a wide range of catalytic transformations

Single-atom catalysts

Selective hydrogenation of unsaturated aldehydes to unsaturated alcohols is a valuable but challenging task for synthesizing fine chemicals. We report that single Rh atoms anchored to the edges of 2D MoS2 sheets can efficiently convert crotonaldehyde to crotyl alcohol with 100% selectivity via a steric confinement effect of pocketlike active sites. Characterization results suggest that the synthesized Rh1/MoS2 single-atom catalysts (SACs) possess a unique geometric and electronic configuration, which confines the adsorption mode of the reactant molecule by a steric effect. The DFT calculations suggest that the MoS2 sheets terminate with oxidized Mo edges and the Rh1 stably anchors at the Mo cation vacancy site, which can facilely dissociate H2 to H atoms. The dissociated H atoms spill over to react with the edge O atoms to form OH species and create an HO-Mo-Rh1-Mo-OH configuration, resembling a pocketlike active site, which confines the adsorption mode of the crotonaldehyde due to steric effects. Such specific adsorption configuration yields 100% selectivity. The strategy of constructing pocketlike active centers with single metal atoms and 2D nanosheets opens new approaches to designing highly selective SACs for specific classes of catalytic transformations.

Methanol partial oxidation is an extremely promising route of realizing the hydrogen production for onboard such as in automobiles. Here, we report the design of a catalyst comprising isolated sing...

In this work, the encapsulated barium titanate (BT) (C-PEN@BT) nanoparticles were successfully prepared via rotary coating technology combined with a post-treatment chemical bonding process, by using carboxyl-functionalized poly(arylene ether nitrile) (C-PEN) as modification agent. The TEM, FTIR and TGA results confirmed that the polymer layer (about 8 nm) has been uniformly surrounded on the surface of BT nanoparticles. Then, a facilitated physical dispersion technology was employed to prepare C-PEN@BT filled composite films using crystalline PEN as matrix and 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BPH) as a novel cross-linking agent. The effects of both the surface modification of BT nanoparticles and matrix cross-linking on the mechanical, thermal and dielectric properties of PEN-based composites were investigated in detail. Compared with PEN-I film, the latter results showed that the strong interface interactions exerted between polymer matrix and CPEN layer on BT surface, especially the formation of cross-linking network across the PEN matrix, resulted in increased tensile strength and Young’ modulus by 29% and 32%, respectively. More importantly, the PEN/C-PEN@BT composite film shows stable dielectric properties in the temperature range of 20–204 °C, which is very close to the glass transition temperature.

Free-standing, hierarchical, ultrathin, and two-dimensional (2D) polycrystalline Co3O4 flowers were synthesized by a hydrothermal and topotactic transformation process. Aberration-corrected electron microscopy study of both the CoOx precursor structure and the subsequent topotactic transformation processes revealed the nucleation and growth mechanisms of the 2D polycrystalline Co3O4 nanosheets. The free-standing flower-shaped CoOx powders (1–5 μm) consist of numerous self-assembled nanocrystallites (average size ∼1.8 nm). After the topotactic transformation, via a rapid calcination process, the powders maintained their hierarchical flower-like shape, but the CoOx nanocrystallites structurally transformed into ultrathin 2D Co3O4 nanoplates with thicknesses ranging from 1 to 5 nm (average thickness ∼2.4 nm). The final, free-standing, ultrathin 2D polycrystalline Co3O4 flowers possess a BET surface area of 138 m2/g. Statistical structural analyses revealed that the exposed surfaces of the Co3O4 flowers are d...

Summary The scaling up of electrocatalytic CO2 reduction for practical applications is still hindered by a few challenges: low selectivity, small current density to maintain a reasonable selectivity, and the cost of the catalytic materials. Here we report a facile synthesis of earth-abundant Ni single-atom catalysts on commercial carbon black, which were further employed in a gas-phase electrocatalytic reactor under ambient conditions. As a result, those single-atomic sites exhibit an extraordinary performance in reducing CO2 to CO, yielding a current density above 100 mA cm−2, with nearly 100% selectivity for CO and around 1% toward the hydrogen evolution side reaction. By further scaling up the electrode into a 10 × 10-cm2 modular cell, the overall current in one unit cell can easily ramp up to more than 8 A while maintaining an exclusive CO evolution with a generation rate of 3.34 L hr−1 per unit cell.

Bimetallic nanocrystals often outperform their monometallic counterparts in catalysis as a result of the electronic coupling and geometric effect arising from two different metals. Here we report a facile synthesis of Pd-Cu Janus nanocrystals with controlled shapes through site-selected growth by reducing the Cu(II) precursor with glucose in the presence of hexadecylamine and Pd icosahedral seeds. Specifically, at a slow reduction rate, the Cu atoms nucleate and grow from one vertex of the icosahedral seed to form a penta-twinned Janus nanocrystal in the shape of a pentagonal bipyramid or decahedron. At a fast reduction rate, in contrast, the Cu atoms can directly nucleate from or diffuse to the edge of the icosahedral seed for the generation of a singly twinned Janus nanocrystal in the shape of a truncated bitetrahedron. The segregation of two elements and the presence of twin boundaries on the surface make the Pd-Cu Janus nanocrystals effective catalysts for the electrochemical reduction of CO

Overproduction of mucus and impaired clearance play important roles in the pathogenesis of muco-obstructive lung diseases (MOLDs). This study aims to evaluate the therapeutic effect and safety of nebulized hypertonic saline (HS) on MOLDs. Five electronic databases including PubMed, Excerpt Medica Database (EMBASE), Cochrane Central Register of Controlled Trials, ClinicalTrials.gov and International Standard Randomized Controlled Trial Number Register were searched until June 2019. Randomized controlled trials or randomized controlled crossover trials which investigated the therapeutic effect of HS versus non-HS for MOLDs were included. Twenty-one studies met the eligibility criteria. For cystic fibrosis (CF), although the forced expiratory volume in the first second and forced vital capacity did not improve significantly (mean difference (MD) −0.48, 95% CI −3.72 to 2.76), (MD 1.85, 95% CI −4.31 to 8.01), respectively), the clearance capability of lung and quality of life (QOL) improved significantly in the HS group ((standard mean difference 0.44, 95% CI 0.02 to 0.87), (MD −0.64, 95% CI −)1.14, to 0.13), respectively). However, the results of trial sequential analysis showed the evidence needed more researches to support. The effect of nebulized HS on non-CF bronchiectasis, chronic obstructive pulmonary disease, and primary ciliary dyskinesia also need more evidence to conclude, since current studies are limited and results are inconsistent. Most adverse events of nebulized HS were mild and transient. In summary, the current available evidence suggests that nebulized HS may increase the QOL in CF, but there was no significant improvement in lung function. However, it is not possible to draw firm conclusions for other MOLDs due to limited data.

Here, we report that a cationic bimetallic site consisting of one Pd and three Zn atoms (Pd