Single-atom catalysts often exhibit unexpected catalytic activity for many important chemical reactions because of their unique electronic and geometric structures with respect to their bulk ...counterparts. Herein we adopt metal–organic frameworks (MOFs) to assist the preparation of a catalyst containing single Ni sites for efficient electroreduction of CO2. The synthesis is based on ionic exchange between Zn nodes and adsorbed Ni ions within the cavities of the MOF. This single-atom catalyst exhibited an excellent turnover frequency for electroreduction of CO2 (5273 h–1), with a Faradaic efficiency for CO production of over 71.9% and a current density of 10.48 mA cm–2 at an overpotential of 0.89 V. Our findings present some guidelines for the rational design and accurate modulation of nanostructured catalysts at the atomic scale.
•Circ_0000285 was elevated while miR-654-3p was down-regulated in DN.•Circ_0000285 acted as a sponge of miR-654-3p.•MAPK6 functioned as downstream target of miR-654-3p.
Recently, increasing evidence ...has reported that circRNAs are non-coding RNAs and they bind with the corresponding miRNAs to modulate the target genes. However, the detailed role of circRNAs in the pathogenesis of DN still remains poorly known. Currently, we aimed to study how circ_0000285 functions in DN development. We found that circ_0000285 was significantly increased in DN mice models and mouse podocytes incubated with HG. Then, circ_0000285 was overexpressed in mouse podocytes and we observed that overexpression of circ_0000285 promoted podocytes injury. Moreover, miR-654-3p was precited as a target of circ_0000285. It was shown that circ_0000285 was strongly pulled down by circ_0000285 specific probe and circ_0000285 specific probe was used to successfully enrich miR-654-3p. In addition, we reported that miR-654-3p was obviously down-regulated in DN. Inhibitors of miR-654-3p greatly reversed the effects of circ_0000285 siRNA on podocytes injury. Moreover, the inflammation release was restrained by loss of circ_0000285, while induced by miR-654-3p inhibitors. IL-6, L-1β and TNF-α level was remarkably depressed by the knockdown of circ_0000285 and miR-654-3p inhibitors induced that. Furthermore, MAPK6 was confirmed as a direct downstream target of miR-654-3p. As shown, MAPK6 was markedly suppressed by circ_0000285 siRNA, which was rescued by the decrease of miR-654-3p. These findings revealed that circ_0000285 promoted podocyte injury via sponging miR-654-3p and activating MAPK6 in DN.
Abstract
The interplay between task-relevant and task-irrelevant information may induce conflicts that impair behavioral performance, a.k.a. behavioral congruency effects. The neuronal mechanisms ...underlying behavioral congruency effects, however, are poorly understood. We recorded single unit activity in monkey prefrontal cortex using a task-switching paradigm and discovered a neuronal congruency effect (NCE) that is carried by target and distractor neurons which process target and distractor-related information, respectively. The former neurons provide more signal, the latter less noise in congruent compared to incongruent conditions, resulting in a better target representation. Such NCE is dominated by the level of congruency, and is not determined by the task rules the subjects used, their reaction times (RT), the length of the delay period, nor the response levels of the neurons. We propose that this NCE can explain behavioral congruency effects in general, as well as previous fMRI and EEG results in various conflict paradigms.
Oxidative and inflammatory damage have been suggested to play important roles in the pathogenesis of diabetic nephropathy (DN). Chlorogenic acid (CGA) is one of the most abundant polyphenols and has ...known immunoprotective, antioxidant and anti-inflammatory properties. In the present study, animal experiments were designed to examine the protective effects of CGA in DN, and cellular experiments were designed to explore the underlying mechanisms. CGA significantly attenuated diabetic renal damage based on histological pathology and molecular biological methods. Pre-treatment with CGA increased the nuclear translocation of nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and the expression of heme oxygenase-1 (HO-1) and reduced the phosphorylation of IĸB and subsequent nuclear translocation of nuclear factor kappa beta (NF-ĸB). Nrf2 small interfering RNA (siRNA) and the HO-1 inhibitor zinc protoporphyrin (ZnPPIX) significantly increased the nuclear translocation of NF-ĸB and the production of pro-inflammatory cytokines in HBZY-1 cells. The NF-ĸB inhibitor pyrrolidine dithiocarbamate (PDTC) increased Nrf2 nuclear translocation and HO-1 expression and antioxidant levels. Thus, these results suggest that CGA is a potential therapeutic agent in the treatment of DN due to its antioxidant and anti-inflammatory effects which are mediated via the modulation of the Nrf2/HO-1 and NF-ĸB pathways. Moreover, CGA-induced the activation of Nrf2/HO-1,which interacts with the inhibition of NF-ĸB, as each begets and amplifies the other.
•Chlorogenic acid mitigates diabetic renal oxidative stress via regulating the Nrf2 pathway.•Chlorogenic acid relieves diabetic renal inflammation by inhibiting NF-ĸB pathway.•CGA-induced activation of Nrf2/HO-1 interacts with the inhibition of NF-ĸB, as each begets and amplifies the other.•CGA could be a potential therapeutic agent in the treatment of diabetic nephropathy.
Ultrathin metal layers can be highly active carbon dioxide electroreduction catalysts, but may also be prone to oxidation. Here we construct a model of graphene confined ultrathin layers of highly ...reactive metals, taking the synthetic highly reactive tin quantum sheets confined in graphene as an example. The higher electrochemical active area ensures 9 times larger carbon dioxide adsorption capacity relative to bulk tin, while the highly-conductive graphene favours rate-determining electron transfer from carbon dioxide to its radical anion. The lowered tin-tin coordination numbers, revealed by X-ray absorption fine structure spectroscopy, enable tin quantum sheets confined in graphene to efficiently stabilize the carbon dioxide radical anion, verified by 0.13 volts lowered potential of hydroxyl ion adsorption compared with bulk tin. Hence, the tin quantum sheets confined in graphene show enhanced electrocatalytic activity and stability. This work may provide a promising lead for designing efficient and robust catalysts for electrolytic fuel synthesis.
Limited by the relatively sluggish charge‐carrier separation in semiconductors, the photocatalytic performance is still far below what is expected. Herein, a model of ZnIn2S4 (ZIS) nanosheets with ...oxygen doping is put forward to obtain in‐depth understanding of the role that doping atoms play in photocatalysis. It shows enhanced photocatalytic activity compared with pristine ZIS. The electron dynamics analyzed by ultrafast transient absorption spectroscopy reveals that the average recovery lifetime of photoexcited electrons is increased by 1.53 times upon oxygen incorporation into the ZIS crystals, indicating enhanced separation of photoexcited carriers in oxygen‐doped ZIS nanosheets. As expected, the oxygen‐doped ZIS nanosheets show a remarkably improved photocatalytic activity with a hydrogen evolution rate of up to 2120 μmol h−1 g−1 under visible‐light irradiation, which is 4.5 times higher than that of the pristine ZIS nanosheets.
Doping control: A model of ultrathin ZnIn2S4 nanosheets with oxygen doping offers insights into the influence of oxygen doping on the separation of photogenerated electron–hole pairs and the photocatalytic activity of catalysts at the atomic level. Experimental and theoretical studies reveal that the oxygen‐doped ZnIn2S4 ultrathin nanosheets have enhanced photocatalytic activity.
We develop a host-guest strategy to construct an electrocatalyst with Fe-Co dual sites embedded on N-doped porous carbon and demonstrate its activity for oxygen reduction reaction in acidic ...electrolyte. Our catalyst exhibits superior oxygen reduction reaction performance, with comparable onset potential (E onset, 1.06 vs 1.03 V) and half-wave potential (E 1/2, 0.863 vs 0.858 V) than commercial Pt/C. The fuel cell test reveals (Fe,Co)/N-C outperforms most reported Pt-free catalysts in H2/O2 and H2/air. In addition, this cathode catalyst with dual metal sites is stable in a long-term operation with 50 000 cycles for electrode measurement and 100 h for H2/air single cell operation. Density functional theory calculations reveal the dual sites is favored for activation of O-O, crucial for four-electron oxygen reduction.
Manipulation of multi‐functions in molecular materials is promising for future switching and memory devices, although it is currently difficult. Herein, we assembled the asymmetric {Fe2Co} unit into ...a cyanide‐bridged mixed‐valence chain {(Tp)Fe(CN)32Co(BIT)} ⋅ 2CH3OH (1) (Tp=hydrotris(pyrazolyl)borate and BIT=3,4‐bis‐(1H‐imidazol‐1‐yl)thiophene), which showed reversible multi‐phase transitions accompanied by photo‐switchable single‐chain magnet properties and a dielectric anomaly. Variable‐temperature X‐ray structural studies revealed thermo‐ and photo‐induced selective electron transfer (ET) between the Co and one of the Fe ions. Alternating‐current magnetic susceptibility studies revealed that 1 displayed on and off single‐chain magnet behavior by alternating 946‐nm and 532‐nm light irradiation. A substantial anomaly in the dielectric constant was discovered during the electron transfer process, which is uncommon in similar ET complexes. These findings illustrate that 1 provided a new platform for multi‐phase transitions and multi‐switches adjusted by selective metal‐to‐metal ET.
A cyanide‐bridged mixed‐valence chain complex of {(Tp)Fe(CN)32Co(BIT)} ⋅ 2 CH3OH (1; Tp=hydrotris(pyrazolyl)borate and BIT=3,4‐bis‐(1H‐imidazol‐1‐yl)thiophene) was synthesized by assembling asymmetric electron transfer‐active {Fe2Co} units with BIT ligands. It showed reversible multi‐phase transitions accompanied by photo‐switchable single‐chain magnet properties and a dielectric anomaly.
The design of active, selective, and stable CO2 reduction electrocatalysts is still challenging. A series of atomically dispersed Co catalysts with different nitrogen coordination numbers were ...prepared and their CO2 electroreduction catalytic performance was explored. The best catalyst, atomically dispersed Co with two‐coordinate nitrogen atoms, achieves both high selectivity and superior activity with 94 % CO formation Faradaic efficiency and a current density of 18.1 mA cm−2 at an overpotential of 520 mV. The CO formation turnover frequency reaches a record value of 18 200 h−1, surpassing most reported metal‐based catalysts under comparable conditions. Our experimental and theoretical results demonstrate that lower a coordination number facilitates activation of CO2 to the CO2.− intermediate and hence enhances CO2 electroreduction activity.
A remarkable carbon dioxide electroreduction catalytic performance with superior activity and high selectivity was achieved on atomically dispersed Co sites through coordination environment regulating. First step in picture: C–N fragments, 1000 °C; second step: NH3 treatment.
Achieving active and stable oxygen evolution reaction (OER) in acid media based on single-atom catalysts is highly promising for cost-effective and sustainable energy supply in proton electrolyte ...membrane electrolyzers. Here, we report an atomically dispersed Ru
-N
site anchored on nitrogen-carbon support (Ru-N-C) as an efficient and durable electrocatalyst for acidic OER. The single-atom Ru-N-C catalyst delivers an exceptionally intrinsic activity, reaching a mass activity as high as 3571 A g
and turnover frequency of 3348 O
h
with a low overpotential of 267 mV at a current density of 10 mA cm
. The catalyst shows no evident deactivation or decomposition after 30-hour operation in acidic environment. Operando synchrotron radiation X-ray absorption spectroscopy and infrared spectroscopy identify the dynamic adsorption of single oxygen atom on Ru site under working potentials, and theoretical calculations demonstrate that the O-Ru
-N
site is responsible for the high OER activity and stability.
PDF
