Germanene, a 2D honeycomb lattice analogous to graphene, is fabricated on a Pt(111) surface. It exhibits a buckled configuration with a (3 × 3) superlattice coinciding with the substrate's (√19 × ...√19) superstructure. Covalent bonds exist throughout the germanene layer. The resulting high‐quality germanene enables researchers to explore the fundamentals of germanene and its potential applications.
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Mango peel was chosen as the carbon source to generate carbon dots (CDs), for its green and potential satisfactory photoluminescent nature in addition to the waste recycling usage of ...mango peel. An eco-friendly approach which combined pyrolyzation with oxygenolysis was adopted to produce CDs from mango peel without any other treatment. The prepared CDs were 2–6 nm nanoparticles with a high fluorescence quantum yield of 8.5 ± 0.2%. Additionally, the CDs exhibited excellent fluorescent stability towards salt and ultraviolet irradiation, and reversible fluorescence between acid and base conditions. Owing to their low toxicity, good biocompatibility and multicolor fluorescence, CDs were successfully applied to cellular labeling on A549 cells in three colors (blue, green and red). Additionally, the fluorescence of CDs could be significantly quenched by Fe2+. Thus the CDs were applied as the fluorescent probe for detection of Fe2+ in ferrous succinate tablets with the linearity range of 4 μM–16 μM and the detection limit of 1.2 μM. The CDs from the mango peel were promising for multiple applications.
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•High quantum yield N,S,P tri-doped carbon dots (NSP-CDs) were prepared.•The fluorescence of NSP-CDs was sensitive to pH irrelevant to the buffer type.•NSP-CDs were successfully ...applied in detection of Cl− in simulated sweat.•NSP-CDs modified TiO2 had higher degradation efficiency of methylene blue.
The preparation and application exploration of multi-heteroatom doped carbon dots (CDs) have drawn tremendous attention. In this study, the N, S, P tri-doped carbon dots (NSP-CDs) were prepared by one-pot hydrothermal method with sulfonamide and phosphoric acid as precursors, possessing a fluorescence quantum yield up to 33 %. The fluorescence intensity of NSP-CDs exhibited a good linear relationship with the surrounding pH in the range of 3–7, showing the great promising pH sensing potential of NSP-CDs. Moreover, the fluorescence of NSP-CDs could be selectively quenched by Cl−; based on it, a Cl− fluorescence sensor was constructed and successfully applied to detecting Cl− in sweat samples with the recoveries of 94 %–110 %. Furthermore, TiO2 was modified with the NSP-CDs by simple immersion method, and the as-prepared composite demonstrated higher photocatalytic activity for the degradation of methylene blue under UV irradiation than pristine TiO2. The prepared NSP-CDs had potential for multiple applications.
•Hongcaitai was used as carbon precursor for carbon dots (CDs) by hydrothermal method.•The CDs were divided into CDs-A (ethanol soluble) and CDs-B (ethanol insoluble).•The CDs had similar ...physicochemical and photoluminescent properties but different selectivity.•CDs-A and CDs-B were applied to detect ClO− and Hg2+, respectively.•Both CDs showed low cytotoxicity to HepG2 cells and labeled them successfully.
Natural source is an effective carbon precursor to produce carbon dots (CDs) with prominent physicochemical and photoluminescent properties. To enrich the CDs’ type and widen their applications, more natural sources are desired. Herein, Hongcaitai (Brassica compestris L. var. purpurea Bailey), one of the popular and cheap vegetables in Hubei province of China, was attempted as the carbon precursor for synthesis of CDs by hydrothermal method. The obtained CDs were divided into two parts based on different solubilities in ethanol, CDs-A (ethanol soluble) and CDs-B (ethanol insoluble). Both CDs possessed multi functionalities; however, CDs-B contained sulfur element while CDs-A did not. Fluorescence quenching occured for both CDs in the presence of ClO− and Hg2+. However, CDs-A were more sensitive towards ClO−, while CDs-B were more sensitive towards Hg2+. Thus, CDs-A were successful to determine ClO− in tap water with limit of detection at 0.015 μM. CDs-B were successful to determine Hg2+ in river water with limit of detection at 0.06 μM. The results demonstrate that the sub-classfication of CDs by the subtle different properties, e.g. ethanol solubility, is necessary for better application performance of CDs. In addition, thanks to their low toxicity, both CDs were suitable for cellular labelling on HepG2 cells.
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•Mesoporous melamine-formaldehyde resin microsphere was fabricated.•It had high adsorption amount of perfluorooctanoic acid than activated carbon.•The adsorption can be performed in a ...wide pH and temperature range.•The material could be well regenerated by dilute ammonia solution.•It was a potential adsorbent to remove perfluorooctanoic acid from water.
Perfluoroalkyl and polyfluoroalkyl substances are priority contaminants of global concern. It is urgent to remove them from the environment. Adsorption is an efficient approach, but the adsorption capacity and regeneration of adsorbent were not satisfactory. In the present study, mesoporous melamine-formaldehyde resin microsphere (MMFRS) was fabricated through suspension polymerization. Owing to its mesoporous property and large anion-exchange capacity of 0.3mmol/g, MMFRS was applied to the adsorption of perfluorooctanoic acid, a model target. The sorption kinetics obeyed pseudo-second-order equation and the sorption isotherms fitted both Freundlich and Langmuir models well. MMFRS exhibited a superiority over commercial powdered activated carbon on the adsorption amount. The sorption could reach equilibrium within 24h. In addition, the material could be easily and economically regenerated by dilute NH3·H2O (7.5mM); a regeneration percentage (>85%) after 20 recycles was obtained. This study provides a facile, environmentally-friendly and low energy-consumption strategy for removal of perfluorooctanoic acid from aqueous solution in waste-water treatment.
With the rapid advancement of urbanization, the green space well-being (GSWB) of developing countries faces drastic changes and is increasingly threatened. Green and residential spaces are the core ...elements of GSWB; however, we know very little about the interaction and combination of the two in terms of their effect on GSWB. This study identified the spatiotemporal features of GSWB and critically examined how patterns of residential–green combinations affect GSWB. Based on land-use data for Jinan from 2006 to 2018, and using the spatial measurement tool GeoDa, we found that both green and residential space have increased significantly in central Jinan. At the macro level, the spatial correlation between the two decreased significantly; meanwhile, at the micro level, there are obvious differences in time and geography. This led to differences in the distribution of GSWB between regions with high value and those with low value. We revealed that the development, preservation, and demolition of residential and green spaces influence changes in GSWB. The positive effects on GSWB come from (1) mountain park development policy in built-up areas, (2) theme park development policy in new urban areas, and (3) urban renewal and demolition policy. The negative effects on GSWB come from (1) issues remaining from prior extensive urban development, (2) the replacement of central areas driven by urban branding, and (3) the lack of supervision of nearby facilities for new housing development. To better understand changes in GSWB, it is necessary to consider its internal residential–green spatial collaboration and propose targeted response strategies. This can help to better safeguard the quality of human settlements in the process of urbanization in developing countries.
A model of neoclassical tearing mode (NTM) induced by resonant magnetic perturbation (RMP) in the presence of the bootstrap current in tokamak plasmas is established based on the full ...magnetohydrodynamic equations. The model is solved numerically by using a finite difference method and the numerical results are obtained. It is found that, the NTM can be induced by the given stable equilibrium, added the perturbed bootstrap current in ohm equation, and the applied RMP. Moreover, with the increasing amplitude of the static RMP, locked mode occurs, which is determined by the plasma flow and fraction of bootstrap current. The mode locking threshold increases with the increasing of plasma rotation frequency and decreasing of fraction of bootstrap current. Furthermore, the dynamic RMP is investigated, results show that the mode locking threshold is lower compared to the static RMP applied, which provides a better way of adjusting the NTM to the frequency of dynamic RMP and slightly suppressing the neoclassical magnetic island.
•A new MHD code, named NTM2D, is used to numerically simulate the NTMs induced by RMPs in tokamak plasmas.•The mode locking threshold is further investigated with the RMP applied in the whole charge period.•It is found that the mode locking threshold with the dynamic RMP is lower than the threshold with the static RMP.
Fourteen polybrominated diphenyl ether (PBDE) congeners were measured in water, suspended particulate matter (SPM), and sediment samples collected from the entire expanse of the Yellow River in dry ...and wet seasons. Higher concentrations of PBDEs were found in the middle and lower reaches of the river compared with those in the upper reaches, ascribed to the relatively developed and urbanized cities located in the areas near the middle and lower reaches. The PBDE concentrations in the samples collected during the dry season were lower than those in the samples collected during the wet season because of thaw and rainfall. The dominant congener, with a contribution of 44.6–90.3%, was BDE-209, which originated from the residual of commercial deca-BDE. Three groups of congeners in all the samples showed good correlations with the coefficient ranging from 0.662 to 0.999 (p < 0.01), indicating common sources and similar environmental behaviors. Regression analysis suggested that the local industrial product (IP) and population density (PD) were good indicators of PBDEs in the water and sediment of the Yellow River.
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•14 PBDEs were investigated in multi phases along the whole Yellow River for two seasons.•Higher level PBDEs in middle and lower reaches caused by industrial activities.•SPM contained relatively high PBDEs due to the high sediment concentration in Yellow River.•Local industrial product and population density were good indicators of PBDEs.
Background
To study the antidiabetic effects and mechanisms of the fenugreek extracts in streptozotocin (STZ)‐induced type 2 diabetic (T2DM) mice fed a high‐fat diet (HFD).
Methods
We established ...C57BL/6J mice model of T2DM using HFD‐fed and STZ‐induced method. Then, the mice were administered with two types of fenugreek extracts (E1, flavonoid and E2, stilbene glycoside) for 4 weeks and the effects on fasting blood glucose (FBG), weight, superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and pathological indexes were investigated.
Results
Administration of fenugreek extracts decreased the FBG level compared with that of the model group. Comparatively, the high‐dose E2 decreased the FBG more significantly than the other treatments did. Both extracts showed an obvious antioxidant effect by increasing serum SOD and CAT activities and decreasing the MDA content. Furthermore, the high‐dose E1 showed a significant difference (P < .01) compared with the model group in the three investigated indexes.
Conclusion
Our study demonstrated that both the flavonoid and stilbene glycoside extracts of fenugreek improved the hyperglycemia in the T2DM mice model. Moreover, the antidiabetic effects of both extracts might be due to their antioxidant activity in vivo.
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