Low‐cost, nonprecious transition metal (TM) catalysts toward efficient water oxidation are of critical importance to future sustainable energy technologies. The advances in structure engineering of ...water oxidation catalysts (WOCs) with single TM centers as active sites, for example, single metallic molecular complexes (SMMCs), supported SMMCs, and single‐atom catalysts (SACs) in recent reports are examined. The efforts made on these configurations in terms of design principle, advanced characterization, performances and theoretical studies, are critically reviewed. A clear roadmap with the correlations between the single‐TM‐site‐based structures (coordination and geometric structure, TM species, support), and the catalytic performances in water oxidation is provided. The insights bridging SMMCs with SACs are also given. Finally, the challenges and opportunities in the single‐TM‐site catalysis are proposed.
Focusing on single transition metal (TM) site catalysis, a clear roadmap with the correlations between the catalytic performances in water oxidation and the single‐TM‐site‐based structures including coordination and geometric structure, TM species, and support is provided. Bridging remarks between single metallic molecular complexes and single‐atom catalysts are also given.
Heteroatom (nitrogen and sulfur)-codoped porous carbons (N-S-PCs) with high surface areas and hierarchically porous structures were successfully synthesized via direct pyrolysis of a mixture of ...glucose, sodium bicarbonate, and thiourea. The resulting N-S-PCs exhibit excellent adsorption abilities and are highly efficient for potassium persulfate activation when employed as catalysts for the oxidative degradation of sulfachloropyridazine (SCP) solutions. The adsorption capacities of N-S-PC-2 (which contains 4.51 atom % nitrogen and 0.22 atom % sulfur and exhibits S BET of 1608 m2 g–1) are 73, 7, and 3 times higher than those of graphene oxide, reduced graphene oxide, and commercial single-walled carbon nanotube, respectively. For oxidation, the reaction rate constant of N-S-PC-2 is 0.28 min–1. This approach not only contributes to the large-scale production and application of high-quality catalysts in water remediation but also provides an innovative strategy for the production of heteroatom-doped PCs for energy applications.
Quasi‐1D cadmium chalcogenide quantum rods (QRs) are benchmark semiconductor materials that are combined with noble metals to constitute QR heterostructures for efficient photocatalysis. However, the ...high toxicity of cadmium and cost of noble metals are the main obstacles to their widespread use. Herein, a facile colloidal synthetic approach is reported that leads to the spontaneous formation of cadmium‐free alloyed ZnSxSe1−x QRs from polydisperse ZnSe nanowires by alkylthiol etching. The obtained non‐noble‐metal ZnSxSe1−x QRs can not only be directly adopted as efficient photocatalysts for water oxidation, showing a striking oxygen evolution capability of 3000 µmol g−1 h−1, but also be utilized to prepare QR‐sensitized TiO2 photoanodes which present enhanced photo‐electrochemical (PEC) activity. Density functional theory (DFT) simulations reveal that alloyed ZnSxSe1−x QRs have highly active Zn sites on the (100) surface and reduced energy barrier for oxygen evolution, which in turn, are beneficial to their outstanding photocatalytic and PEC activities.
Nearly monodisperse alloyed semiconductor quantum rods (QRs) are formed from polydisperse nanowires by means of etching of alkylthiol. The obtained noble‐ and heavy‐metal‐free alloyed QRs demonstrate striking oxygen evolution capability and enhanced photo‐electrochemical activity due to the highly active Zn sites on their (100) surface and reduced energy barrier for water oxidation, as revealed by the density functional theory simulations.
Cancer metastasis is the primary cause of death in patients diagnosed with colorectal cancer. Piperine, an active nontoxic ingredient in pepper, has potent anti-inflammatory and anti-cancer ...properties. However, little is known about the anti-migratory and anti-invasive effects of piperine on colorectal cancer. We demonstrated piperine inhibited the migration and invasion of colorectal cancer cells. Then, we found piperine reversed the biomarker expression of epithelial-to-mesenchymal transition (EMT), and suppressed the EMT regulator Snail. Furthermore, signal transducers and activators of transcription 3 (STAT3) was downregulated by piperine. Finally, STAT3 inhibitors were applied to observe the role of STAT3 in colorectal cancer migration, invasion and EMT. Collectively, piperine inhibits colorectal cancer migratory and invasive capacities through STAT3/Snail mediated EMT. Therefore, piperine could be applied as a possible therapeutic regimen for the prevention of colorectal cancer metastasis.
Many bilaterally symmetrical animals develop genetically programmed left–right asymmetries. In vertebrates, this process is under the control of Nodal signaling, which is restricted to the left side ...by Nodal antagonists Cerberus and Lefty. Amphioxus, the earliest diverging chordate lineage, has profound left–right asymmetry as a larva. We show that Cerberus, Nodal, Lefty, and their target transcription factor Pitx are sequentially activated in amphioxus embryos. We then address their function by transcription activator-like effector nucleases (TALEN)-based knockout and heat-shock promoter (HSP)-driven overexpression. Knockout of Cerberus leads to ectopic right-sided expression of Nodal, Lefty, and Pitx, whereas overexpression of Cerberus represses their left-sided expression. Overexpression of Nodal in turn represses Cerberus and activates Lefty and Pitx ectopically on the right side. We also show Lefty represses Nodal, whereas Pitx activates Nodal. These data combine in a model in which Cerberus determines whether the left-sided gene expression cassette is activated or repressed. These regulatory steps are essential for normal left–right asymmetry to develop, as when they are disrupted embryos may instead form two phenotypic left sides or two phenotypic right sides. Our study shows the regulatory cassette controlling left–right asymmetry was in place in the ancestor of amphioxus and vertebrates. This includes the Nodal inhibitors Cerberus and Lefty, both of which operate in feedback loops with Nodal and combine to establish asymmetric Pitx expression. Cerberus and Lefty are missing from most invertebrate lineages, marking this mechanism as an innovation in the lineage leading to modern chordates.
Abstract
Background
Existing epidemiological observational studies have suggested interesting but inconsistent clinical correlations between inflammatory bowel disease (IBD), including Crohn’s ...disease (CD) and ulcerative colitis (UC), and kidney stone disease (KSD). Herein, we implemented a two-sample bidirectional Mendelian randomization (MR) to investigate the causal relationship between IBD and KSD.
Methods
Data on IBD and KSD were obtained from Genome-Wide Association Studies (GWAS) summary statistics and the FinnGen consortium, respectively. Strict selection steps were used to screen for eligible instrumental SNPs. We applied inverse variance weighting (IVW) with the fix-effects model as the major method. Several sensitivity analyses were used to evaluate pleiotropy and heterogeneity. Causal relationships between IBD and KSD were explored in two opposite directions. Furthermore, we carried out multivariable MR (MVMR) to obtain the direct causal effects of IBD on KSD.
Results
Our results demonstrated that CD could increase the risk of KSD (IVW: OR = 1.06, 95% CI = 1.03–1.10,
p
< 0.001). Similar results were found in the validation group (IVW: OR = 1.05, 95% CI = 1.01–1.08,
p
= 0.013) and in the MVMR analysis. Meanwhile, no evidence of a causal association between UC and KSD was identified. The reverse MR analysis detected no causal association.
Conclusions
This MR study verified that CD plays a critical role in developing kidney stones and that the effect of UC on KSD needs to be further explored.
This study analyzes the effects of shot peening on the crack initiation behavior under fretting loading by using a numerical method. The residual stress relaxation and the contact stress evolution ...are both considered. The crack initiation life is predicted by the critical plane Smith⁻Watson⁻Topper (SWT) model. Considering that the fretting contact region has a high stress gradient along the depth direction, the process volume approach is adopted to calculate the SWT parameters. The results show that the remaining residual stress after relaxation strongly affects crack initiation life. The remaining residual stress decreases with the increase of fatigue loading, and the effect of shot peening on the improvement of crack initiation life is more obvious under smaller fatigue loading. Furthermore, under smaller fatigue loading, the crack initiation life of specimens with high shot peening intensity is longer than that of specimens with low shot peening intensity. However, the opposite phenomenon appears when the fatigue loading is large enough.
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•A novel low-temperature hydrothermal method is developed to prepare Co-N-rGO.•Co-N-rGO demonstrates higher catalytic activity for ORR than pyrolyzed Co-N-rGO.•Co is coordinated with ...N which is doped into the rGO structure via covalent bond.•Co and N show synergetic effect in enhancing the ORR activity of rGO.•The active sites responsible for ORR are proposed to be CoN2/C and CoN4/C species.
Cobalt and nitrogen co-doped reduced graphene oxide (Co-N-rGO) composites are prepared by a facile low-temperature hydrothermal method. Structure characterization reveals that cobalt and nitrogen are co-ordinately attached to the rGO sheets with the formation of covalent C-N and Co-O-C linkages. Cyclic voltammetry and linear sweep voltammetry show that the Co-N-rGO composite possesses higher electrocatalytic activity and four-electron selectivity for oxygen reduction reaction (ORR) as compared to the rGO, Co-rGO and N-rGO. In addition, the Co-N-rGO composite presents excellent stability and durability in alkaline medium comparable to commercial Pt/C. The edge plane CoN2/C, CoN4/C, and basal plane macrocyclic CoN4/C species within the Co-N-rGO structure are proposed to be the active sites performing catalysis in the ORR. The strong covalent linkages between the cobalt/nitrogen and rGO not only enable potent synergy of cobalt, nitrogen and rGO in catalysis, but also ensure structure stability of the composite. Due to the superior ORR activity of Co-N-rGO, high-temperature heat treatment is not able to improve its activity any more. The low-temperature hydrothermal method is anticipated to be used as a low-cost and facile preparation approach for ORR catalysts, and the superb ORR performance of Co-N-rGO endow it with great application potential in fuel cells, metal-air batteries and other ORR-related electrochemical industries.
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