Responses of submerged macrophytes to different particle size microplastics and tetracycline co-pollutants at the community and population level.

Microplastics (MPs) and antibiotics are ubiquitous in aquatic ecosystems, and their accumulation and combined effects are considered emerging threats that may affect biodiversity and ecosystem function. The particle size of microplastics plays an important role in their combined effects with antibiotics. Submerged macrophytes are crucial in maintaining the health and stability of freshwater ecosystems. However, little is known about the combined effects of different particle size of MPs and antibiotics on freshwater plants, particularly their effects on submerged macrophyte communities. Thus, there is an urgent need to study their effects on the macrophyte communities to provide essential information for freshwater ecosystem management. In the present study, a mesocosm experiment was conducted to explore the effects of three particle sizes (5 µm, 50 µm, and 500 µm) of polystyrene-microplastics (PSMPs) (75 mg/L), tetracycline (TC) (50 mg/L), and their co-pollutants on interactions between Hydrilla verticillata and Elodea nuttallii. Our results showed that the effects of MPs are size-dependent on macrophytes at the community level rather than at the population level, and that small and medium sized MPs can promote the growth of the two test macrophytes at the community level. In addition, macrophytes at the community level have a stronger resistance to pollutant stress than those at the population level. Combined exposure to MPs and TC co-pollutants induces species-specific responses and antagonistic toxic effects on the physio-biochemical traits of submerged macrophytes. Our study provides evidence that MPs and co-pollutants not only affect the morphology and physiology at the population level but also the interactions between macrophytes. Thus, there are promising indications on the potential consequences of MPs and co-pollutants on macrophyte community structure, which suggests that future studies should focus on the effects of microplastics and their co-pollutants on aquatic macrophytes at the community level rather than only at the population level. This will improve our understanding of the profound effects of co-pollutants in aquatic environments on the structure and behavior of aquatic communities and ecosystems.

Effect of hydraulic parameters of leachate treatment process on di(2-ethylhexyl) phthalate removal from aged leachate.

The effect of hydraulic parameters of an anaerobic/anoxic/oxic leachate treatment reactor on the removal of di(2-ethylhexyl) phthalate (DEHP) from aged landfill leachate was studied. The mean DEHP removal efficiencies were 79.5%, 87.1%, 89.7% and 87.8% at hydraulic retention times of 6, 4.5, 3 and 2 d, respectively. The removal efficiency of DEHP was significantly higher when the internal reflux ratio was 200% than others. There was no significant difference among the DEHP removal efficiencies at different external reflux ratios of the reactor. Due to the overall efficiency of the reactor, hydraulic retention time 3 d, internal reflux ratio 200% and external reflux ratio 60%, were considered the optimal hydraulic parameters for DEHP removal from aged leachate. The removal efficiency of DEHP was significantly improved (from 75.7% to 89.1%) after the optimization of hydraulic parameters of the reactor. The removal percentages of DEHP in the anaerobic, anoxic, and oxic units of the reactor were 42.8%, 17.6%, and 15.3%, respectively. The oxic microcosms in the reactor had little effect on DEHP removal. The correlation between DEHP and leachate pollutants indicated that DEHP removal was strongly correlated with leachate COD and NH4+-N.

Microplastics and co-pollutant with ciprofloxacin affect interactions between free-floating macrophytes.

Microplastic and antibiotic contamination are considered an increasing environmental problem in aquatic systems, while little is known about the impact of microplastics and co-pollutant with antibiotics on freshwater vascular plants, particularly the effects of interactions between macrophytes. Here, we performed a mesocosm experiment to evaluate the impact of polyethylene-microplastics and their co-pollutants with ciprofloxacin on the growth and physiological characteristics of Spirodela polyrhiza and Lemna minor and the interactions between these two macrophytes. Our results showed that microplastics alone cannot significantly influence fresh weight and specific leaf area of the two test free-floating macrophytes, but the effects on photosynthetic pigments, malondialdehyde, catalase and soluble sugar contents were species-specific. Ciprofloxacin can significant adverse effects on the growth and physiological traits of the two test macrophytes and microplastic mitigated the toxicity of ciprofloxacin on the two free-floating plants to a certain extent. In addition, our studies showed that microplastics and co-pollutants can influence relative yield and competitiveness of S. polyrhiza and L. minor by directly or indirectly influencing their physiology and growth. Therefore our findings suggest that species-specific sensibility to microplastic and its co-pollutant among free-floating macrophytes may influence macrophyte population dynamics and thereby community structure and ecosystem functioning. And microplastics altered other contaminant behaviours and toxicity, and may directly or indirectly influence macrophytes interactions and community structure. The present study is the first experimental study exploring the effects of microplastics alone and with their co-pollutants on interactions between free-floating macrophytes, which can provide basic theoretical guidance for improving the stability of freshwater ecosystems.

Removal of Di-n-butyl phthalate from aged leachate under optimal hydraulic condition of leachate treatment process and in the presence of its dominant bacterial strains.

The effects of hydraulic condition of reactor and the dominant degrading bacteria on the removal of di-n-butyl phthalate (DBP) from aged landfill leachate by anaerobic/anoxic/oxic (A/A/O) leachate treatment process were investigated. The optimal DBP removal (96.0%) was obtained from aged leachate when the hydraulic retention time (HRT) of the reactor was 3 d, internal reflux ratio of the reactor was 200%, and external reflux ratio of the reactor was 60%, respectively. The removal efficiency of DBP was significantly improved after the inoculation of the dominant DBP-degrading bacteria (Pseudomonas sp. W1) in the reactor. The mean removal efficiencies of DBP before and after inoculation were 94.1% and 97.7%, respectively. Furthermore, the inoculation of dominant DBP-degrading bacteria changed the original sludge structure and characteristics, which was more conducive to the removal of DBP. These results provide theoretical basis for the effective removal of DBP from aged leachate by the biological treatment process.

Antibiotics in Leachates from Landfills in Northern Zhejiang Province, China.

The concentrations and distributions of five sulfonamide, three tetracycline, and two macrolide antibiotics in leachates from three landfill sites in northern Zhejiang Province, China, were determined by solid-phase extraction and ultra-high performance liquid chromatography mass spectrometry. Most of the antibiotics were detected in the leachate samples. The concentrations and distributions of the antibiotics in leachates of different ages were very different. The total sulfonamide, tetracycline, and macrolide concentrations in the leachates ranged from not detected to 1.57 × 103, not detected to 5.19 × 103, and 7.30 to 5.42 × 102 ng/L, respectively. The total concentrations of detectable antibiotics were higher in fresh leachates than aged and middle-aged leachates. Higher TC-group concentrations were found in the leachates than have been found in previously published studies of landfill leachates in China. The results improve our understanding of and ability to manage antibiotic residues in landfills.

ZIF-Derived Cobalt-Containing N-Doped Carbon-Coated SiOx Nanoparticles for Superior Lithium Storage.

N-Doped carbon-encapsulated SiOx and Co nanoparticles are synthesized by the calcination of ZIF-67-coated SiOx nanoparticles. This composite exhibits good electrochemical conductivity and superior accommodation to volume change from N-doped carbon and Co with SiOx nanoparticles, exhibiting improved cycle and rate performances for lithium storage. It retains a capacity of 1044 mA h g-1 over 150 cycles at 1.5 A g-1, outperforming those without Co or N-doped carbon. It well confirms the contributions of Co- and N-doped carbon to the electrochemical properties of SiOx. Even after 350 cycles at 1.0 A g-1, this composite nonetheless delivers a capacity of 900 mA h g-1. If it is coupled with LiFePO4, the full cells show a stable cycling, indicating the promising application of this composite.

Metal-Organic Frameworks-Derived Mesoporous Si/SiOx @NC Nanospheres as a Long-Lifespan Anode Material for Lithium-Ion Batteries.

Silicon (Si)-based anode materials with suitable engineered nanostructures generally have improved lithium storage capabilities, which provide great promise for the electrochemical performance in lithium-ion batteries (LIBs). Herein, a metal-organic framework (MOF)-derived unique core-shell Si/SiOx @NC structure has been synthesized by a facile magnesio-thermic reduction, in which the Si and SiOx matrix were encapsulated by nitrogen (N)-doped carbon. Importantly, the well-designed nanostructure has enough space to accommodate the volume change during the lithiation/delithiation process. The conductive porous N-doped carbon was optimized through direct carbonization and reduction of SiO2 into Si/SiOx simultaneously. Benefiting from the core-shell structure, the synthesized product exhibited enhanced electrochemical performance as an anode material in LIBs. Particularly, the Si/SiOx @NC-650 anode showed the best reversible capacities up to 724 and 702 mAh g-1 even after 100 cycles. The excellent cycling stability of Si/SiOx @NC-650 may be attributed to the core-shell structure as well as the synergistic effect between the Si/SiOx and MOF-derived N-doped carbon.

Removal of phthalic acid dieters with dissolved organic matter by an anaerobic/anoxic/oxic leachate treatment process.

The removal of di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) with dissolved organic matter (DOM) was studied in a laboratory scale anaerobic/anoxic/oxic reactor for landfill leachate treatment. The removal rate was up to 98.0% for DBP and 78.2% for DEHP, which was related to humification of DOM (i.e., the aromaticity and molecular weight (MW) of humic substances in landfill leachate). The dissolved organic carbon (DOC) was mostly humic acid and fulvic acid in the fraction of 1-100 kDa MW, indicating strong aromaticity and a high DBP/DEHP concentration. With complete removal of the fraction, the removal rate of DBP/DEHP was also high. The positive correlation of the DOC and DBP/DEHP concentration in raw leachate and the effluent from each reactor showed that the interaction between DOM and DBP/DEHP facilitated the removal of organic pollutants.

Systematic Exploration of the Role of a Modified Layer on the Separator in the Electrochemistry of Lithium-Sulfur Batteries.

As a significant constituent of lithium-sulfur batteries, the separator also exerts a considerable effect on the performance of the sulfur cathode. In our work, the mixture of acetylene black and multiwalled carbon nanotubes is uniformly applied onto the commercial polypropylene membranes to attain the modified separators. While investigating different samples, the underlying influence of the coating layer is systematically scrutinized on the electrochemical behaviors of sulfur cathodes, relying on the extensive electrochemical and structural measurements. During the charge/discharge process, the coating layer can function as the second current collector and drastically contribute to the improved lithium ions diffusion, determining the electrochemical kinetics of sulfur-involved reactions. Moreover, it is found that the thicker the layer, the faster the lithium ions diffuse. It should be noted that the coating layer also plays a role of the second sulfur reservoir to endow the ample active sites for sulfur and polysulfides, which is directly witnessed for the first time. Because of the positiveness and effectiveness of the modified layer on separators, the sulfur cathode can offer the superior cycling and rate performance to that with the original separator.

One-Step Construction of N,P-Codoped Porous Carbon Sheets/CoP Hybrids with Enhanced Lithium and Potassium Storage.

Despite the desirable advancement in synthesizing transition-metal phosphides (TMPs)-based hybrid structures, most methods depend on foreign-template-based multistep procedures for tailoring the specific structure. Herein, a self-template and recrystallization-self-assembly strategy for the one-step synthesis of core-shell-like cobalt phosphide (CoP) nanoparticles embedded into nitrogen and phosphorus codoped porous carbon sheets (CoP⊂NPPCS), is first proposed. Relying on the unusual coordination ability of melamine with metal ions and the cooperative hydrogen bonding of melamine and phytic acid to form a 2D network, a self-synthesized single precursor can be attained. Importantly, this approach can be easily expanded to synthesize other TMPs⊂NPPCS. Due to the unique compositional and structural characteristics, these CoP⊂NPPCSs manifest outstanding electrochemical performances as anode materials for both lithium- and potassium-ion batteries. The unusual hybrid architecture, the high specific surface area, and porous features make the CoP⊂NPPCS attractive for other potential applications, such as supercapacitors and electrocatalysis.

Nickel hexacyanoferrate/carbon composite as a high-rate and long-life cathode material for aqueous hybrid energy storage.

A nickel hexacyanoferrate (NiHCF)/carbon composite is prepared to realize reduced structure vacancies and enhanced conductivity simultaneously. The resultant composite as a cathode material exhibits good capacity retentions both for rate capability (93% of that at 0.1 A g-1 for 2 A g-1) and cycle stability (94% after 900 cycles at 0.5 A g-1). This feature is also kept in an aqueous hybrid energy storage device, after coupling with rGO as the anode. After 5000 cycles at 2 A g-1, 94% of the initial capacity is preserved, exhibiting extraordinary stability at high rates.

Fabrication and improved photoelectrochemical properties of a transferred GaN-based thin film with InGaN/GaN layers.

Herein, a lift-off mesoporous GaN-based thin film, which consisted of a strong phase-separated InGaN/GaN layer and an n-GaN layer, was fabricated via an electrochemical etching method in a hydrofluoric acid (HF) solution for the first time and then transferred onto quartz or n-Si substrates, acting as photoanodes during photoelectrochemical (PEC) water splitting in a 1 M NaCl aqueous solution. Compared to the as-grown GaN-based film, the transferred GaN-based thin films possess higher and blue-shifted light emission, presumably resulting from an increase in the surface area and stress relaxation in the InGaN/GaN layer embedded on the mesoporous n-GaN. The properties such as (i) high photoconversion efficiency, (ii) low turn-on voltage (-0.79 V versus Ag/AgCl), and (iii) outstanding stability enable the transferred films to have excellent PEC water splitting ability. Furthermore, as compared to the film transferred onto the quartz substrate, the film transferred onto the n-Si substrate exhibits higher photoconversion efficiency (2.99% at -0.10 V) due to holes (h+) in the mesoporous n-GaN layer that originate from the n-Si substrate.

Sensitive determination of protein based on the fluorescence enhancement effect of terbium (III)-epinephrine-protein-sodium dodecylsulfate system.

It was found that the fluorescence of Tb(3+)-epinephrine (E) complex can be enhanced by both bovine serum albumin (BSA) and sodium dodecylsulfate (SDS), and stabilized by ascorbic acid (AA). It is considered that the fluorescence enhancement of the Tb(3+)-E-BSA-AA-SDS system originates not only from the hydrophobic microenvironment provided by BSA-SDS, but also from the energy transfer from BSA to Tb(3+) in this system. Therefore, a new fluorescence method for the determination of protein concentrations as low as 1.3 x 10(-9) g mL(-1) BSA is established using Tb(3+)-epinephrine complex as probe. The method has been applied for the determination of BSA and human serum albumin in actual samples, and the results obtained are satisfactory. Compared with other fluorescence methods, this method is simpler and more sensitive for the determination of protein. The mechanism of the fluorescence enhancement of the system is studied in detail.

[Determination of inorganic elements in different parts of Sonchus oleraceus L by flame atomic absorption spectrometry].

Flame atomic absorption spectrometry with air-acetylene flame was used for the determination of inorganic metal elements in different parts ( flower, leaf, stem and root) of Sonchus oleraceus L. The contents of Ca, Mg, K, Na, Fe, Mn, Cu, Zn, Cr, Co, Ni, Pb and Cd in the flower, leaf, stem and root of Sonchus oleraceus L were compared. The order from high to low of the additive weight (microg x g(-1)) for the 13 kinds of metal elements is as follows: leaf (77 213.72) > flower (47 927.15) > stem(42 280.99) > root (28 131.18). From the experimental results it was found that there were considerable differences in the contents of the metal elements in different parts, and there were richer contents of Fe, Zn, Mn and Cu in root and flower, which are necessary to human health, than in other parts.

Interaction between proteins and cationic gemini surfactant.

Surface tension, fluorescence, and circular dichroism (CD) methods have been used to investigate the interaction between cationic gemini surfactant 1,2-ethane bis(dimethyldodecylammonium bromide) (C12C2C12) and proteins including bovine serum albumin (BSA) and gelatin. Surface tension measurements show that the complexes of gelatin--C12C2C12 form more easily than that of BSA--C12C2C12. Addition of C12C2C12 has a different effect not only on the polarity of the microenvironment in BSA and gelatin systems but also on their fluorescence spectra. It can be seen from far-UV CD spectra that the alpha-helical network of BSA is disrupted and its content decreases from 41.7% to 27.6% while the random coil content of gelatin increases from 53.0% to 55.9% with increasing C12C2C12 concentration. The results from near-UV CD spectra show that the binding of C12C2C12 induces changes of the microenvironment around the aromatic amino acid residues and disulfide bonds of BSA at high C12C2C12 concentrations.

Multi-phase equilibrium microemulsions and synthesis of hierarchically structured calcium carbonate through microemulsion-based routes.

Middle-phase microemulsions (MPMs) in two systems of a cationic surfactant, tetradecyltrimethylammonium bromide (TTABr)/n-butanol/iso-octane/Na2CO3 or CaCl2 and an anionic surfactant, sodium dodecyl sulfate (SDS)/n-butanol/iso-octane/Na2CO3 or CaCl2, were used to synthesize nanostructured calcium carbonates. MPMs provide a simple and versatile reaction media, i.e., upper-phase W/O, BC, and O/W structured equilibrium microemulsions to be used for synthesizing hierarchically structured CaCO3 at the nanometer scale. On the basis of the investigations on the phase behavior of the MPMs, hierarchically structured calcium carbonates with dendrites, ellipsoids, square-schistose cubes, and spheres were synthesized through the MPM-based routes.

Study on the co-luminescence effect of Tb-Gd-epinephrine system and its application to the sensitive determination of epinephrine at nanomol level.

A new fluorimetric method for the determination of epinephrine is established by rare earth co-luminescence effect of Tb-Gd-E-Tris system. Under optimum conditions, a linear relationship has been obtained between the fluorescence intensity and the concentration of epinephrine in the range of 1.8x10(-8) to 2.5x10(-6)mol/l, and the detection limit is 4.5x10(-9)mol/l (S/N=3). The method is applied for the determination of epinephrine in injection and the recovery test in urine by standard addition method, and the results obtained are satisfactory. The mechanism of the co-luminescence in the system was also discussed.