In this work, conducting polymers poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANi), and polypyrrole (PPy) were directly coated on the surface of reduced graphene oxide (RGO) sheets via ...an in situ polymerization process to prepare conducting-polymer-RGO nanocomposites with different loadings of the conducting polymers. Experiment results showed that ethanol played an important role in achieving a uniform coating of the polymers on RGO sheets. The electrochemical capacitive properties of the composite materials were investigated by using cycle voltammetry and charge/discharge techniques. The composite consisting of RGO and PANi (RGO-PANi) exhibited a specific capacitance of 361 F/g at a current density of 0.3 A/g. The composites consisting of RGO and PPy (RGO-PPy) and PEDOT (RGO-PEDOT) displayed specific capacitances of 248 and 108 F/g, respectively, at the same current density. More than 80% of initial capacitance retained after 1000 charge/discharge cycles, suggesting a good cycling stability of the composite electrodes. The good capacitive performance of the conducting–polymer-RGO composites is contributed to the synergic effect of the two components.
Supercapacitors, which are attracting rapidly growing interest from both academia and industry, are important energy‐storage devices for acquiring sustainable energy. Recent years have seen a number ...of significant breakthroughs in the research and development of supercapacitors. The emergence of innovative electrode materials (e.g., graphene) has clearly provided great opportunities for advancing the science in the field of electrochemical energy storage. Conversely, smart configurations of electrode materials and new designs of supercapacitor devices have, in many cases, boosted the electrochemical performance of the materials. We attempt to summarize recent research progress towards the design and configuration of electrode materials to maximize supercapacitor performance in terms of energy density, power density, and cycle stability. With a brief description of the structure, energy‐storage mechanism, and electrode configuration of supercapacitor devices, the design and configuration of symmetric supercapacitors are discussed, followed by that of asymmetric and hybrid supercapacitors. Emphasis is placed on the rational design and configuration of supercapacitor electrodes to maximize the electrochemical performance of the device.
Charged and ready to go: In the past few years, significant breakthroughs in the development of supercapacitors as energy‐storage devices is promoted by the emergence of innovative electrode materials (e.g., graphene) and driven by rapidly increasing demands for high‐performance energy‐storage devices (see picture; ASC/SSC=asymmetric/symmetric supercapacitor.
Inflammation and activation of the neuroendocrine systems comprise important aspects of stroke pathophysiology. The present study investigated whether baseline plasma brain natriuretic peptide (BNP), ...N‐terminal pro‐brain natriuretic peptide (NT‐proBNP), cortisol and copeptin levels on admission can predict short‐term outcomes and mortality after acute ischaemic stroke. The study group consisted of 189 patients who had their first acute ischaemic stroke. Plasma levels of BNP, NT‐proBNP, cortisol and copeptin were evaluated to determine their value with respect to predicting functional outcome and mortality within 3 months. As a result of cardiovascular and neurological investigations (including imaging techniques), lesion size, stroke subtype classification and clinical outcome after 3 months were determined. Plasma levels of BNP, NT‐proBNP, cortisol and copeptin were associated with stroke severity, as well as short‐term functional outcomes. After adjusting for all other significant outcome predictors, NT‐proBNP, cortisol and copeptin remained as independent outcome predictors. In the receiver operating characteristic curve analysis, the biomarker panel (including BNP, NT‐proBNP, cortisol and copeptin) predicted functional outcome and death within 90 days significantly more efficiently than the National Institute of Health Stroke Scale (NIHSS) or the biomarker alone. Copeptin showed a significantly greater discriminatory ability as a single biomarker compared to BNP, NT‐proBNP, cortisol and NIHSS score. These results suggest that a biomarker panel may add valuable and time‐sensitive prognostic information in the early evaluation of acute ischaemic stroke. This may provide a channel for interventional therapy in acute stroke.
Molecular-scale manipulation of electronic and ionic charge accumulation in materials is the backbone of electrochemical energy storage
. Layered van der Waals (vdW) crystals are a diverse family of ...materials into which mobile ions can electrochemically intercalate into the interlamellar gaps of the host atomic lattice
. The structural diversity of such materials enables the interfacial properties of composites to be optimized to improve ion intercalation for energy storage and electronic devices
. However, the ability of heterolayers to modify intercalation reactions, and their role at the atomic level, are yet to be elucidated. Here we demonstrate the electrointercalation of lithium at the level of individual atomic interfaces of dissimilar vdW layers. Electrochemical devices based on vdW heterostructures
of stacked hexagonal boron nitride, graphene and molybdenum dichalcogenide (MoX
; X = S, Se) layers are constructed. We use transmission electron microscopy, in situ magnetoresistance and optical spectroscopy techniques, as well as low-temperature quantum magneto-oscillation measurements and ab initio calculations, to resolve the intermediate stages of lithium intercalation at heterointerfaces. The formation of vdW heterointerfaces between graphene and MoX
results in a more than tenfold greater accumulation of charge in MoX
when compared to MoX
/MoX
homointerfaces, while enforcing a more negative intercalation potential than that of bulk MoX
by at least 0.5 V. Beyond energy storage, our combined experimental and computational methodology for manipulating and characterizing the electrochemical behaviour of layered systems opens new pathways to control the charge density in two-dimensional electronic and optoelectronic devices.
Background
Pomegranate peels have been widely used to treat diarrhea in China. The antidiarrheal activities of aqueous extracts of pomegranate peels have been evaluated. However, there have not been ...any bioactivity‐guided fractionation studies on the antidiarrheal effect to identify the bioactive components of the extract.
Methods
Bioactivity‐guided fractionation of an aqueous extract of pomegranate peels was performed using different solvents of increasing polarity, generating fractions dissolved in ethyl acetate, n‐butyl alcohol, and the residual fraction. The principal chemical composition of the active fraction was analyzed by HPLC/ESI‐MS.
Key Results
Fecal frequencies revealed that only the ethyl acetate fraction possessed significant antidiarrheal activity. Furthermore, administration of the ethyl acetate fraction at 100, 200, and 400 mg/kg significantly reduced gastrointestinal transit in charcoal meal tests in mice. It also significantly inhibited castor oil‐induced enteropooling compared to control animals. Histopathological analysis revealed that small intestine lesions of mice treated with the ethyl acetate fraction were alleviated compared to those in mice treated with castor oil. The ethyl acetate fraction was found to be composed mainly of punicalagin, corilagin, and ellagic acid, and a combination of these compounds could mediate the antidiarrheal activities.
Conclusion and Inferences
Our study describes the protective effects of pomegranate peels against castor oil‐induced diarrhea. The findings showed that the ethyl acetate fraction was the active fraction of pomegranate peels, of which punicalagin, corilagin, and ellagic acid were responsible for the antidiarrheal effect of aqueous extracts.
The antidiarrheal activities of aqueous extracts of pomegranate peels have been evaluated. However, the effective ingredients of antidiarrheal activities need to be determined.( The ethyl acetate fraction was the active fraction of pomegranate peels, of which punicalagin, corilagin, and ellagic acid were responsible for the antidiarrheal effect of aqueous extracts. )Determination of effective ingredients is conductive to the application of pomegranate peels on diarrheal diseases.
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•A total of 17 antibiotics were detected in water, sediment (biofilm), organism and feed samples.•Greenhouse ponds were more likely to accumulate antibiotics compared to outdoor ...ponds.•Zn as the coexisting contaminant was significantly correlated with antibiotic concentrations.•Aquaculture wastewater and domestic sewage were potential sources of antibiotics.•Ciprofloxacin and enrofloxacin may present high ecological and resistance risks.
This study focused on the distribution, combined pollution, potential source and risk assessment of 17 antibiotics in an aquaculture ecosystem surrounding the Yellow sea, North China. Antibiotics were detected in various matrices (seawater, sediment/biofilm, organism and feed) in different aquaculture modes (greenhouse and outdoor aquaculture) during the wet and dry seasons in coastal areas of Shandong province. The innovation points of the study were as follows: (1) To the best of our knowledge, this study was one of the few to investigate the occurrence and distribution of antibiotics in mariculture environments along the Yellow Sea coast; (2) Biofilms, a focus of the study, might act as a sink for antibiotics in the aquaculture ecosystem; and (3) The correlation of heavy metals and antibiotic concentrations was proved, which could correspondingly be used as an indicator for antibiotic concentrations in the studied area.
The levels of antibiotics in water were observed to be relatively low, at the ng/L level. Trimethoprim was the most prevalent antibiotic, and was detected in all water samples. Oxytetracycline was detected at high concentrations in biofilms (up to 1478.29 ng/g). Moreover, biofilms exhibited a higher antibiotic accumulation capacity compared to sediments. Concentrations of oxytetracycline and doxycycline were high in feed, while other antibiotics were almost undetected. Tetracycline was widely detected and the concentration of enrofloxacin was highest in organisms.
Correlation analysis demonstrated that environmental parameters and other coexisting contaminants (e.g. heavy metals) significantly affected antibiotic concentrations. In addition, the concentration of Zn was significantly correlated with the total antibiotic concentration and was proportional to several antibiotics in water and sediment (biofilm) samples (p < 0.01). High Mn concentrations were closely related to total and individual (e.g. sulfadiazine, sulfamethazine and enrofloxacin) antibiotic levels, which may result in the combined contamination of the environment. Antibiotics in estuaries and groundwater generally originated from aquaculture wastewater and untreated/treated domestic sewage. Most of the detected antibiotics posed no risk to the environment. Ciprofloxacin and enrofloxacin found in water may present high ecological and resistance risks, while the two antibiotics observed to accumulate in fish may pose a considerable risk to human health through diet consumption. All antibiotics detected in seafood were lower than the respective maximum residue limits. This study can act as a reference for the government for the determination of antibiotic discharge standards in aquaculture wastewater and the establishment of a standardized antibiotic monitoring and management system.
Magnetic cellulose/Fe₃O₄/activated carbon composites (m-Cell/Fe₃O₄/ACCs) were prepared successfully and characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), thermogravimetric ...analysis (TGA), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The adsorption of congo red onto the novel m-Cell/Fe₃O₄/ACCs was studied as a function of contact time, initial concentration of congo red, adsorbent dosage, and pH of solution. The saturated magnetization of m-Cell/Fe₃O₄/ACCs reached 48.2emug⁻¹ and the magnetic adsorbent showed characteristics of superparamagnetism, which indicated that m-Cell/Fe₃O₄/ACCs could be separated from treated solution by a magnetic process. A comparison of kinetic models showed that the overall adsorption process was best described by pseudo-second-order kinetic model. Thermodynamic analysis indicated an exothermic nature of adsorption and a spontaneous and favorable process. The m-Cell/Fe₃O₄/ACCs might be a promising candidate of high efficiency, low cost and convenient separation under magnetic field.
Abstract
The mechanical behavior of a single phase (fcc) Al
0.3
CoCrFeNi high-entropy alloy (HEA) was studied in the low and high strain-rate regimes. The combination of multiple strengthening ...mechanisms such as solid solution hardening, forest dislocation hardening, as well as mechanical twinning leads to a high work hardening rate, which is significantly larger than that for Al and is retained in the dynamic regime. The resistance to shear localization was studied by dynamically-loading hat-shaped specimens to induce forced shear localization. However, no adiabatic shear band could be observed. It is therefore proposed that the excellent strain hardening ability gives rise to remarkable resistance to shear localization, which makes this material an excellent candidate for penetration protection applications such as armors.
Ultraviolet laser radiation has been adopted in a wide range of applications as diverse as water purification, flexible displays, data storage, sterilization, diagnosis and bioagent detection. ...Success in developing semiconductor-based, compact ultraviolet laser sources, however, has been extremely limited. Here, we report that defect-free disordered AlGaN core-shell nanowire arrays, formed directly on a Si substrate, can be used to achieve highly stable, electrically pumped lasers across the entire ultraviolet AII (UV-AII) band (∼320-340 nm) at low temperatures. The laser threshold is in the range of tens of amps per centimetre squared, which is nearly three orders of magnitude lower than those of previously reported quantum-well lasers. This work also reports the first demonstration of electrically injected AlGaN-based ultraviolet lasers monolithically grown on a Si substrate, and offers a new avenue for achieving semiconductor lasers in the ultraviolet B (UV-B) (280-320 nm) and ultraviolet C (UV-C) (<280 nm) bands.
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