The two-dimensional material C3N is expected to be an ideal material for the next generation of high-strength electronic devices based on its excellent properties. Here we systemically study the ...electronic properties for the sawtoothlike C3N nanoribbons by using the first principles calculations. We find that the fully polarized system occurs for specific windows of energies in the pristine nanoribbons. Passivation of the nanoribbons edges with hydrogen atoms can enhance the stability of the nanoribbon and change its electronic properties. The passivated Tree-saw C3N nanoribbons transforms into a direct band gap semiconductor. While the passivated Christmas tree C3N nanoribbons exhibit semiconducting or metallic properties depending on the edge. Finally, we propose a molecular junction based on the zigzag graphene nanoribbons electrode. The computational results imply that the device can be used as a rectifier or a spin valve. These results are helpful expand the application of C3N in nanoelectronic devices.
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•Two novel sawtoothlike C3N nanoribbons are proposed.•H passivation at its edge can alter the nanoribbon’s electronic properties.•Devices with spin filtering and NDR effects are designed.
In this paper, Ag-Metal−organic framework loaded chitosan nanoparticles (0.1%Ag@MOF/1.5%CSNPs) and polyvinyl alcohol/sodium alginate/chitosan (PACS) were used as the upper and lower layers to ...successfully prepare a bilayer composite dressing for wound healing. The performance of bilayer dressing was evaluated. The lower layer (PACS) had uniform pore size distribution, good water retention, swelling, water vapor permeability, and biocompatibility while PACS had almost no antibacterial activity. The upper layer (Ag@MOF/CSNPs) possessed excellent antibacterial activity and poor biocompatibility. As the upper layer, it can avoid direct contact with the skin and inhibit microbial invasion. In addition, the bilayer can adhere to a large number of red blood cells and platelets, promoting blood coagulation and cell proliferation. Ag@MOF, CSNPs, Ag@MOF/CSNPs and bilayer showed antibacterial activity in ascending order, due to the synergistic antibacterial action of the upper and lower layer. In vivo evaluation showed that both bilayer and PACS could significantly accelerate the wound healing, and the bilayer dressing showed more complete re-epithelialization with less inflammatory cells. In summary, this new bilayer composite is an ideal dressing for accelerating wound healing.
•Novel bilayer dressing can accelerate wound healing.•Novel bilayer dressing with good hemostasis and low hemolytic•The bilayer possessed higher antibacterial properties and lower cytotoxic effect.
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•Microplastics (MPs, 10 μm) accumulated on the chorion, but did not enter the embryo.•High levels of MPs (20 and 200 μg/L) inhibited hatching and growth of marine medaka.•High levels ...of MPs did not alter the toxicity of phenanthrene (Phe).•Low level of MPs (2 μg/L) decreased the teratogenicity and lethality of Phe.•Combined exposure to MPs and Phe may lead to a decrease of marine fish population.
Microplastics (MPs) have become global environmental concern. However, the effects of environmental concentrations of MPs, singly or in combination with organic pollutants, on the early development of marine fish remain unclear. In this study, fertilized eggs of marine medaka (Oryzias melastigma) were exposed to polystyrene MPs (0, 2, 20, 200 μg/L) and/or phenanthrene (Phe, 50 μg/L) for 28 days. The results revealed that MPs were accumulated on the chorion and ingested by larvae from 2 days post-hatching. High levels of MPs (20 and 200 μg/L) decreased the hatchability, delayed the hatching time, and suppressed the growth, whereas Phe inhibited hatching and caused malformations in larvae. The presence of MPs at 20 and 200 μg/L did not alter the toxicity of Phe. By contrast, combined exposure to 2 μg/L MPs and Phe increased the hatchability by 25.8%, decreased malformation and mortality rates, and restored Phe-induced abnormal expressions of cardiac development-related genes. The reduced early developmental toxicity could be attributed to the decreased bioavailability and bioaccumulation of Phe by the low level of MPs. These findings contradicted the view that MPs would aggravate the toxicity of organic pollutants, and future studies are warranted to elucidate the ecological risks of marine MPs.
Bioturbation by the razor clam, Sinonovacula constricta, influenced the redox conditions and changed the sedimentary environment, providing a suitable micro-environment for microbial growth. However, ...the mechanism of the integrated razor clam-microbial community in organic matter mineralization remains elusive. To study this mechanism, an in situ experiment was conducted to investigate the bioturbation effects of S. constricta on the microbial community and enzyme activities in the sediment of an ecological aquaculture wastewater treatment system. According to principal coordinate analysis (PCoA) and PERMANOVA, we found that the microbial community was significantly (P < 0.05) influenced by the bioturbation effect of S. constricta. Linear discriminant analysis effect size (LEfSe) showed that species involved in reduced effluent concentrations of TN and TP, such as Prolixibacteraceae, Nitrospira and Actinobacteria, were increased significantly (P < 0.05) by S. constricta. Molecular ecological network (MENs) analysis indicated that the bioturbation effect of S. constricta increased the complexity of interspecies interaction and changed the topological properties of individual OTUs. The results elucidated that S. constricta increased the microbial community network, as substantiated by a higher total number of nodes and a shorter geodesic distance. Zi < 2.5 and Pi <0.62 in MENs showed that the S. constricta treatment significantly increased (P < 0.05) the potential microbial community, with the keystone (OTU747049) Proteobacteria and (OTU74388) Bacteroidetes family Prolixibacteraceae, which connected different co-expressed OTUs. Furthermore, S. constricta significantly increased (P < 0.05) the enzymatic activities (alkaline phosphatase (APA), dehydrogenase and urease) of the substrate at different sampling depths. Overall, this study provides evidence that the bioturbation effect of S. constricta changes the microbial community structure, increases enzymatic activities and accelerates the degradation of organic matter in an aquaculture wastewater environment.
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•Integrated clam-microbial are potential for aquaculture wastewater treatment•Bioturbation of S. constricta influenced the mineralization of sediment organic matter•S. constricta altered the topological roles of individual OTUs and keystone community•The enzyme activities of APA, dehydrogenase and urease were affected by S. constricta
Wound dressing materials which are capable of meeting the demands of accelerating wound closure and promoting wound healing process have being highly desired. Electrospun nanofibrous materials show ...great application potentials for wound healing owing to relatively large surface area, better mimicry of native extracellular matrix, adjustable waterproofness and breathability, and programmable drug delivery process. In this review article, we begin with a discussion of wound healing process and current commercial wound dressing materials. Then, we emphasize on electrospun nanofibrous materials for wound dressing, covering the efforts for controlling fiber alignment and morphology, constructing 3D scaffolds, developing waterproof-breathable membrane, governing drug delivery performance, and regulating stem cell behavior. Finally, we finish with challenges and future prospects of electrospun nanofibrous materials for wound dressings.
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Developing novel bilayer food packing film having the ability to prevent bacterial infections and capable of inhibiting oxidation is utmost important, since bacterial infections and oxidation can ...cause food spoilage. Ag-Metal−organic framework loaded p-coumaric acid modified chitosan (P-CS/Ag@MOF) or chitosan nanoparticles (P-CSNPs/Ag@MOF) and polyvinyl alcohol/starch (PVA/ST) were used as the upper film and lower layer film to successfully prepare a bilayer composite film. The microscopic morphology, water resistance, oil resistance, oxidation resistance, optical properties, cytotoxicity and antibacterial properties of the composite films were compared. The results showed that the surface of P-CS/Ag@MOF bilayer was relatively smooth and its tensile strength (TS) was higher (27.67 MPa). Among them, P-CS/Ag@MOF bilayer films had better oil resistance and oxidation resistance activity. In addition, the P-CS/Ag@MOF bilayer film had good UV-blocking properties and transparency. P-CSNPs/Ag@MOF bilayer film had higher antibacterial activity and cytotoxicity.
•P-CSNPs/Ag@MOF/PVA/ST provided the best antibacterial activity.•P-CS/Ag@MOF reduced the cytotoxicity of the films.•P-CS/Ag@MOF improved the mechanical properties of the films.•P-CS/Ag@MOF enhanced optical barrier properties.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in marine environments and have arouse great concern since they pose adverse effects to marine ecosystem. To determine the potential ...impacts of environmentally relevant PAHs on early life stages of marine fish, this study exposed embryos of marine medaka (Oryzias melastigma) to 0, 2, 10, 50, and 250 μg/L of phenanthrene (Phe), one of the most abundant PAHs. The results demonstrated that Phe exposure decreased hatching rates, delayed hatching time of embryos, and increased deformity rate of newly-hatched larvae. Exposure to 10 and 50 μg/L Phe decreased the survival rate of marine medaka larvae at 28 days post-fertilization (dpf), and no embryo successfully hatched in 250 μg/L Phe exposure group. Morphology results showed that 10, 50, and 250 μg/L Phe exposure significantly retarded the development of embryos, and 2, 10, and 50 μg/L caused yolk sac edema and pericardial edema in newly-hatched larvae, indicating that low concentrations of Phe could induce developmental cardiac toxicity. Furthermore, the changes in the expression of heart development-related genes were determined, and the results showed that Phe-induced cardiac malformation might be related with fgf8, bmp4, smyd1, ATPase and gata4 genes. Overall, environmentally relevant PAHs could disrupt heart morphogenesis and hatching process of marine medaka, which might have profound consequences for sustainability of fish population.
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•Environmentally relevant Phe increased deformity rate of marine medaka larvae.•Phe exposure decreased hatching rates and delayed hatching time of embryos.•Heart might be an important target organ of Phe during the fish early-life stage.•Low concentration of Phe (2 μg/L) could induce developmental cardiac toxicity.•Environmentally relevant PAHs may threaten the sustainability of fish population.
In this work, the statistical inference of inverted exponentiated half-logistic distribution is considered under the progressive type-II censored data with competing risks. The parameter estimations ...of the constant scale parameters but different shape parameters that changed due to various risk factors are investigated in this study. The maximum likelihood estimation is deduced to obtain the parameter estimators and asymptotic confidence intervals; meanwhile, the existence and uniqueness of the maximum likelihood estimators are discussed. Subsequently, bootstrap confidence intervals are calculated and presented. The Bayes estimates based on the square error loss function are derived using the Markov Chain Monte Carlo method. Then, the highest posterior density credible intervals are calculated and provided. Simulations are implemented to compare two kinds of estimates. For illustrative purposes, two experimental lifetime datasets from different fields are exhibited and analyzed. Finally, an optimal censoring scheme is suggested under two optimality criteria.
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•MnFe2O4 magnetic catalysts had excellent ozone catalytic oxidation performance on the real BPSCW.•The effect of operational parameters in practical applications on catalytic ...ozonation is investigated.•The removal efficiencies of COD and volatile phenol could reach 85.2% and 94.1%, respectively.•MnFe2O4 magnetic catalysts catalyzed O3/H2O2 to produce hydroxyl radicals (∙OH).•MnFe2O4 magnetic catalysts were superparamagnetic (67.8 emu∙g−1) and reused without high loss of activity.
In this study, spinel-type MnFe2O4 magnetic nanoparticles were successfully synthesized employing the purified sol–gel method and used for the advanced treatment of biologically pretreated semi-coking wastewater (BPSCW) by the O3/H2O2 catalytic system. Results showed that the MnFe2O4 magnetic catalysts did not have a regular surface morphology, and their surface contained numerous fine particles that showed a particle accumulation state and formed a good nano-spinel structure. Their surface morphology, ratio, size, and X-ray photoelectron spectroscopy revealed two active metal elements in the catalyst, namely, Fe3+ and Mn2+, which were consistent with the elemental composition and valence of MnFe2O4. Under optimal reaction conditions, the removal efficiency of O3/H2O2/MnFe2O4 catalytic system for chemical oxygen demand (COD) and volatile phenol (VP) can reach 85.2% and 94.1%, respectively (catalyst dosage = 2.0 g∙L−1, O3 dosage = 1.2 mg∙min−1, H2O2 concentration = 0.15 mol∙L−1, pH = 7.0, and treatment time = 70 min). The free radical quenching experiment and electron paramagnetic resonance (EPR) experiment verified that hydroxyl radicals (∙OH) played a role in the deep treatment of BPSCW in the O3/H2O2/MnFe2O4 catalytic system. Phosphate experiments proved that lewis acid sites on the surface of the MnFe2O4 magnetic catalysts were the catalytically active sites. The superparamagnetic properties of the MnFe2O4 magnetic catalysts (67.8 emu∙g−1) facilitated magnetic separation from the treated wastewater. After 10 cycles, the activity of the MnFe2O4 magnetic catalysts remained high, and the removal efficiencies of COD and VP only decreased by 13.6% and 11.9%, respectively. Considering excellent degradation performance, easy magnetic separation and high stability, this study provided important insights into the practical application of the O3/H2O2 catalytic system for the advanced treatment of BPSCW.
