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The study of atomically dispersed metal‐nitrogen electrocatalysts is still limited in terms of understanding their catalytic mechanism because of the inability to precisely regulate the coordination number and type of N in combination with the metal elements. Inspired by the high catalytic activity and selectivity of natural enzymes, herein, we have designed and fabricated ultrathin carbon nanosheet‐supported Mn single‐atom catalysts (SACs) with a precise pyrrole‐type Mn‐N4 (PT‐MnN4) configuration using a bio‐mimicking strategy. The PT‐MnN4 SACs display outstanding oxygen reduction reaction (ORR) activity, with a half‐wave potential (E1/2) of 0.88 V (vs. revisible hydrogen electrode [RHE]) and extremely high stability in alkaline media. Moreover, superior ORR activities are also obtained, E1/2 of 0.73 V and 0.63 V in acid and neutral electrolytes, respectively, indicating the efficient pH‐universal ORR performances. The assembled zinc–air battery using the PT‐MnN4 SACs as air cathodes exhibits a high peak power density (175 mW cm−2) and long‐term stability up to 150 h, implying its promising application in metal–air batteries. This study has paved the way toward the rational design and precise regulation of single‐atom electrocatalysts.

The optimal control of time‐varying nonlinear systems is an important research topic and faces many difficulties and challenges, but also has substantial benefits. In this paper, the outpu...

To evaluate the impact of DCAcAm on zebrafish gill, we measure the responses of antioxidant enzyme (superoxide dismutase, SOD), lipid peroxidation (malondialdehyde, MDA), ATPase (Na+ /K+ -ATPase and Ca2+ /Mg2+ -ATP) and histopathological changes of gill in adult zebrafish, after exposed to different concentrations of DCAcAm (0, 1, 10, 100, and 1000 μg L-1 ) for 30 days. Results indicated that DCAcAm first increased and then decreased SOD activity, and DCAcAm also lowered the activities of Na+ /K+ -ATPase and Ca2+ /Mg2+ -ATPase. These results indicated that high affinity of DCAcAm probably be a main factor, which can damage the structures of enzymes, thereby inhibiting the SOD and ATPase activities. Besides, histopathological investigation results also manifested that chronic exposure to DCAcAm can damage the gill tissues, disrupting the normal function of gills. We conclude that chronic exposure to DCAcAm was harmful to organisms, not only influence gill function, but also further cause damage on the gill tissues.

Manipulation of the emission properties of pure organic molecules through external stimuli is attractive but challenging. Herein, a dual-emissive hexathiobenzene-based molecule is reported with significant aggregation-induced phosphorescence characteristics, and demonstrates reversible switching among blue, green, and yellow phosphorescence by controlling molecular aggregation state or protonation state. Variation of solvent or pH value manipulates the interconversion between fluorescence and phosphorescence, while the change in protonation state in organic solvent switches two short-lived emissions in a controllable manner. Such a controlled manipulation is achieved by the rational design of combining a twisted structure and the proper arrangement of energy gaps among different excited states. This work provides a new design principle for organic molecules with efficient room-temperature phosphorescence and tunable singlet-triplet emissive properties, and contributes to the design and development of smart materials and intelligent optoelectronic devices.

Objective To evaluate whether an adjuvant therapy of leukotriene receptor antagonists (LTRAs) based on oral H1-antihistamines (H1) can increase efficacy of allergic rhinitis (AR) treatment. Data Sources The search involved databases of PubMed, EMBASE, and Cochrane Central Register of Controlled Trials, from inception up to September 23, 2017. Randomized controlled trials (RCTs) that compared efficacy of LTRAs + H1 vs H1 alone were eligible. Review Methods Pooled comparative effects were measured using weighted mean difference (WMD) and 95% confidence interval (CI). Subgroup analysis comparing seasonal vs perennial AR was prespecified to explore the source of heterogeneity. The evidence quality of each outcome was assessed by the GRADE approach. Results A total of 8 RCTs were included (n = 1886), and all measured outcomes used scaled scores. Compared with H1 alone, H1 + LTRAs were superior to improve overall daytime (WMD, -0.11; 95% CI, -0.19 to -0.03, high quality) and composite (WMD, -0.12; 95% CI, -0.23 to -0.01; low quality) nasal symptoms. Specifically, H1 + LTRAs had better efficacy against composite nasal rhinorrhea, sneezing, and daytime itching but not congestion. The effects were more pronounced in patients with perennial AR compared to those with seasonal AR. There were no significant differences in nighttime nasal symptoms and eye symptoms between the 2 groups. Conclusion The current evidence suggests that LTRAs + H1 can increase the therapeutic efficacy against daytime and composite nasal symptoms, including rhinorrhea, sneezing, and itching; however, it does not affect nighttime nasal symptoms and eye symptoms. The patients with perennial AR may benefit more from the combination therapy.

Rational phase engineering of reduction cocatalyst offers a promising route to modulate the photocatalytic activity and selectivity in the conversion of CO2 to chemical feedstocks. However, it remains a great challenge to choose a suitable phase given that high-crystallinity phase is more conducive to the charge transfer and separation, while amorphous phase is more favorable for the adsorption and activation of CO2 molecules. To resolve this dilemma, herein, with Pd as a well-defined model, a surface amorphization strategy has been developed to fabricate crystalline@amorphous semi-core-shell cocatalysts based on the transformation of outer layer atoms of crystalline cocatalysts to disorder phase. According to the theoretical and experimental analysis, in the heterostructured cocatalysts, crystalline core shuttles the photoexcited electrons from light-harvesting semiconductor to amorphous shell due to its strong electronic coupling with both components. Meanwhile, amorphous shell provides efficient active sites for preferential activation and conversion of CO2 and suppression of undesirable proton reduction. Benefiting from the synergistic effects between crystalline core and amorphous shell, the optimized heterophase cocatalyst with suitable thickness of amorphous shell achieves superior CO (22.2 µmol gcat-1 h-1 ) and CH4 (38.1 µmol gcat-1 h-1 ) formation rates with considerable selectivity and high stability in comparison with crystalline and amorphous counterparts.

Graphene-Fe3 O4 nanoparticles were prepared using one-step solvothermal method and characterized by X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, and vibrating sample magnetometry. The results demonstrated that Fe3 O4 nanoparticles were homogeneously anchored on graphene nanosheets. The as-synthesized graphene-Fe3 O4 nanoparticles were employed as sorbent for magnetic solid-phase extraction of sulfonamides in milk prior to capillary electrophoresis analysis. The optimal capillary electrophoresis conditions were as follows: 60 mmol/L Na2 HPO4 containing 2 mmol/L ethylenediaminetetraacetic acid disodium salt and 24% v/v methanol as running buffer, separation voltage of 14 kV, and detection wavelength of 270 nm. The parameters affecting extraction efficiency including desorption solution, the amount of graphene-Fe3 O4 nanoparticles, extraction time, and sample pH were investigated in detail. Under the optimal conditions, good linearity (5-200 μg/L) with correlation coefficients ≥0.9910 was obtained. The limits of detection were 0.89-2.31 μg/L. The relative standard deviations for intraday and interday analyses were 4.9-8.5 and 4.0-9.0%, respectively. The proposed method was successfully applied to the analysis of sulfonamides in milk samples with recoveries ranging from 62.7 to 104.8% and relative standard deviations less than 10.2%.

Synergistic catalysis induced by transition metal single‐atom sites coordinated onto pyrrolic N‐rich graphitic carbon nitride leads to an outstanding performance toward the photocatalytic Fenton‐like reaction with outstanding cyclic stability and a wide effective pH range.

The doping of carbon quantum dots with nitrogen provides a promising direction to improve fluorescence performance and broaden their applications in sensing systems. Herein we report a one-pot solvothermal synthesis of N-doped carbon quantum dots (NCQDs) and the synthesis of a series of NCQDs with different nitrogen contents. The as-prepared NCQDs were compared with carbon quantum dots (CQDs); the introduction of nitrogen atoms largely increased the quantum yield of NCQDs and highest emission efficiency is up to 36.3 %. The fluorescence enhancement may originate from more polyaromatic structures induced by incorporated nitrogen atoms and protonation of nitrogen atoms on dots. It was found that NCQDs can act as a multifunctional fluorescence sensing platform because they can be used to detect pH values, Ag(I), and Fe(III) in aqueous solution. The fluorescence intensity of NCQDs is inversely proportional to pH values across a broad range from 5.0 to 13.5, which indicates that NCQDs can be devised as an effective pH indicator. Selective detection of Ag(I) and Fe(III) was achieved based on their distinctive fluorescence influence because Ag(I) can significantly enhance the fluorescence whereas Fe(III) can greatly quench the fluorescence. The quantitative determination of Ag(I) can be accomplished with NCQDs by using the linear relationship between fluorescence intensity of NCQDs and concentration of Ag(I). The sensitive detection of H2O2 was developed by taking advantage of the distinct quenching ability of Fe(III) and Fe(II) toward the fluorescence of NCQDs. Cellular toxicity test showed NCQDs still retain low toxicity to cells despite the introduction of a great deal of nitrogen atoms. Moreover, bioimaging experiments demonstrated that NCQDs have stronger resistance to photobleaching than CQDs and more excellent fluorescence labeling performance.

Aims We aimed to perform a systematic review and meta-analysis to assess the association between serum uric acid and incident heart failure (HF)/prognosis of HF patients. Methods and results A systematic electronic literature search was conducted in Embase (Ovid SP, from 1974 to May 2013), Medline (Ovid SP, from 1946 to May 2013), and the Chinese Biomedical Literature Database (CBM, from 1978 to May 2013) to identify studies reporting on the association between serum uric acid and HF. Either a random effects model or a fixed effects model was used for pooling data. Five studies reporting on incident HF and 28 studies reporting on the adverse outcomes of HF patients were included. The results showed that hyperuricaemia was associated with an increased risk of incident HF [hazard ratio (HR) 1.65, 95% confidence interval (CI) 1.41–1.94], and the risk of all-cause mortality (HR 2.15, 95% CI 1.64–2.83), cardiovascular mortality (HR 1.45, 95% CI 1.18–1.78), and the composite of death or cardiac events (HR 1.39, 95% CI 1.18–1.63) in HF patients. For every 1 mg/dL increase in serum uric acid, the odds of development of HF increased by 19% (HR 1.19, 95% CI 1.17–1.21), and the risk of all-cause mortality and the composite endpoint in HF patients increased by 4% (HR 1.04, 95% CI 1.02–1.06) and 28% (HR 1.28, 95% CI 0.97–1.70), respectively. Subgroup analyses supported the positive association between serum uric acid and HF. Conclusions Elevated serum uric acid is associated with an increased risk of incident HF and adverse outcomes in HF patients.

High photovoltaic efficiency is a key index in the application of silicon (Si) solar cells. In this study, a composite of a photovoltaic Si p–n junction solar cell and a magnetostrictive TbxDy1−xFe2 alloy was fabricated. By utilizing the magnetostrictive strain to modulate the energy bandgap of Si, the open-circuit voltage and the maximum photovoltaic output power of the Si p–n junction solar cell could be enhanced by ∼12% and 9.1% under a dc magnetic field of ∼250 mT, respectively. The significantly enhanced photovoltaic performance and the simple fabrication process make the Si-p–n/TbxDy1−xFe2 composite a promising material for high-efficiency solar cell devices. The structure of the proposed Si-p–n/TbxDy1−xFe2 laminated composite.

Intercalators are well known for their DNA binding specificity by inserting between base pairs, whereas the binding event occurring to apurine/apyrimidine site (AP site)-containing DNA for this type of noncovalent interaction is still not highlighted although AP site is frequently in vivo produced in living cells. Here proflavine (PF) as an example is used to investigate the binding specificity of the AP site in DNA for a non-hydrogen bond ligand. Experimental results indicate that the AP site should be the preferential binding site for PF. The intrinsic binding constant of PF for the AP site is one order of magnitude greater than that occurring for PF intercalation. Additionally, the thermostability of the AP site-containing DNA is significantly increased after PF binding. The PF bound to the AP site should adopt a specific binding orientation distinguishable from that by which PF intercalated into base pairs. The results obtained here should be very useful for judging biochemical and biophysical effectiveness of small molecules based on their different binding behavior to DNA.