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A theoretical model for bubble formation at a submerged orifice has been developed,which takes into account the interaction between the column wall and the growing bubble at the orifice,as well as the interaction between subsequen...
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A theoretical model for bubble formation at a submerged orifice has been developed,which takes into account the interaction between the column wall and the growing bubble at the orifice,as well as the interaction between subsequent bubbles formed and detached from the orifice.Experiments involving high-speed photography and bubble frequency measurements were carried out with different chamber volumes,column and orifice diameters,and gas flow.In particular,it was found that decreasing the column diameter (that is,increasing the bubble-wall interaction) led to increased bubble-bubble interaction,as evidenced by a greater tendency for pairing and multiple bubbling.Simulated results using the theoretical model agreed very well with experimental data.
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Flumetsulam (FLU) is a new class of broad-spectrum herbicides. With the widespread use of plastic products,
polyethylene (PE) microplastics (MPs) may remain in the soil. It is possible for these two novel contaminants to
co-exis...
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Flumetsulam (FLU) is a new class of broad-spectrum herbicides. With the widespread use of plastic products,
polyethylene (PE) microplastics (MPs) may remain in the soil. It is possible for these two novel contaminants to
co-exist in the soil environment. In the present study, we used brown soil as the test soil and determined the
toxicity of FLU at 0.05, 0.5 and 2.5 mg kg~(–1) alone and in combination with PE MPs (1%) on soil microorganisms.
The obtained results demonstrated that the exposure of FLU and FLU+MPs had an inhibitory effect on the
numbers of bacteria and fungi. In addition, FLU and FLU+MPs caused changes in the relevant functional bacterial
genera, favored nitrogen fixation and denitrification, and promoted soil carbon fixation, but inhibited
nitrification. Compared to FLU exposure alone, exposure to FLU+MPs gave rise to significant differences in soil
bacterial community composition, but did not affect carbon and nitrogen cycling. The integrated biomarker response results indicated that the toxicity of FLU and FLU+MPs to soil microorganisms increased with
increasing concentrations of FLU. The present experiment clarified the toxicological effects of co-exposure of FLU
and MPs on microorganisms and filled the toxicological data gap of FLU.
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Microplastics (MPs) may significantly affect the bioavailability of coexisting pollutants in soil by adsorptiondesorption
behavior. However, the mechanisms underlying these interaction remain unclear. Herein, the influence
of un...
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Microplastics (MPs) may significantly affect the bioavailability of coexisting pollutants in soil by adsorptiondesorption
behavior. However, the mechanisms underlying these interaction remain unclear. Herein, the influence
of unused polythylene mulch film-derived MPs (MFMPs) and farmland residual polyethylene mulch filmderived
MPs (MFMPs-aged) on the adsorption-desorption behavior and bioavailability of atrazine (ATZ) in soil
were investigated. The adsorption kinetics and the adsorption isotherms of ATZ on soil, MFMPs, and MFMPsaged
fitted well by the pseudo-second-order model and the Langmuir model, respectively. ATZ were easier to
desorb from soil, MFMPs, and MFMPs-aged in the simulated earthworm digestive fluid than that in the CaCl_2
solution. The adsorption and desorption capacities of MFMPs and MFMPs-aged for ATZ were higher than those of
soil, especially for MFMPs-aged. The existence of MPs in soil strengthened the adsorption and desorption capacities
of ATZ, and the strengthened effects were promoted by the addition amount and aging process of MPs.
Moreover, the occurrence of MPs significantly increased the bioaccumulation of ATZ in earthworms, especially for MFMPs-aged. This study deepens the knowledge of the interaction mechanisms of mulch film-derived MPs
and pesticide pollution.
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Trifloxystrobin has been widely applied to prevent fungal diseases because of its high efficiency and desirable safety characteristics. In the present study, the effects of trifloxystrobin on soil microorganisms were integrally in...
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Trifloxystrobin has been widely applied to prevent fungal diseases because of its high efficiency and desirable safety characteristics. In the present study, the effects of trifloxystrobin on soil microorganisms were integrally investigated. The results showed that trifloxystrobin inhibited urease activity, promoted dehydrogenase activity. Downregulated expressions of the nitrifying gene (amoA), denitrifying genes (nirK and nirS), and carbon fixation gene (cbbL) were also observed. Soil bacterial community structure analysis showed that trifloxystrobin changed the abundance of bacteria genera related to nitrogen and carbon cycle in soil. Through the comprehensive analysis of soil enzymes, functional gene abundance, and soil bacterial community structure, we concluded that trifloxystrobin inhibited both nitrification and denitrification of soil microorganisms, and also diminished the carbon-sequestration ability. Integrated biomarker response analysis showed that dehydrogenase and nifH were the most sensitive indicators of trifloxystrobin exposure. It provides new insights about trifloxystrobin environmental pollution and its influence on soil ecosystem.
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In this study, novel alkali-resistant nanocomposite nanofiltration (NF) membranes were prepared via phase inversion by immersion precipitation combined with the addition of two kinds of functionalized graphene nanosheets. The effe...
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In this study, novel alkali-resistant nanocomposite nanofiltration (NF) membranes were prepared via phase inversion by immersion precipitation combined with the addition of two kinds of functionalized graphene nanosheets. The effects of the functional groups and the concentrations of the graphene-based nanosheets on the microstructures and performances of nanocomposite membranes were systematically investigated. Compared with the pure polyethersulfone (PES) membrane, incorporation of a small amount of sulfonated graphene (SG) or graphene oxide (GO) into the PES matrix did not change the membrane morphology. However, the hydrophilicity, permeability and antifouling capabilities were remarkably enhanced without obvious reduction in membrane rejection. Particularly, the water fluxes of optimized PES–SG and PES–GO NF membranes at 0.1 wt% were improved by 119.7% and 71.3%, respectively. Moreover, the PES–SG series membranes exhibited better hydrophilicity and membrane separation performance than the PES–GO series membranes, which was attributed to the different ionisable functional groups from the SG and GO nanosheets. Both the optimized PES–SG and PES–GO NF membranes exhibited long-term stability during a seven-day test in alkaline solution, but PES–SG demonstrated greater promise as a novel alkali-resistant NF membrane due to its superior permeability and antifouling performance.
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The discrete element method combined with computational fluid dynamics was coupled with a capillary liquid bridge force model for computational studies of mixing behaviors in gas fluidized bed systems containing wet granular mater...
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The discrete element method combined with computational fluid dynamics was coupled with a capillary liquid bridge force model for computational studies of mixing behaviors in gas fluidized bed systems containing wet granular materials. Due to the presence of strong capillary liquid bridge forces between wet particles, relative motions between adjacent particles were hindered. There was a high tendency for wet particles to form large aggregates within which independent motions of individual particles were limited. This resulted in much lower mixing efficiencies in comparison with fluidization of dry particles. Capillary liquid bridge forces were on average stronger than both fluid drag forces and particle-particle collision forces and this accounted for the difficulty with which individual particles could be removed and transferred between aggregates. Such exchange of particles between aggregates was necessary for mixing to occur during fluidization of wet granular materials but required strong capillary liquid bridge forces to be overcome.
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A simple and effective drying model is desirable for evaluation of dryer performance, optimization, and evaluation of product quality. It should be able to model the phenomena of the drying process and yet be favorable for quick d...
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A simple and effective drying model is desirable for evaluation of dryer performance, optimization, and evaluation of product quality. It should be able to model the phenomena of the drying process and yet be favorable for quick decision-making in industries. Ideally, it should require a minimum number of experiments to generate the parameters. Reaction engineering approach (REA) has been shown for many years to be an alternative model for convective air drying of various dairy products. In this paper, a demonstration of the flexibilities of the REA is given for modeling various systems of drying of foods and biomaterials, including convective drying of grain, fruit tissues, and biomaterials as well as intermittent drying of grain and fruit tissues. While the results are accurate, the modeling itself has still proven to be simple. These exercises are very encouraging and have set up a good foundation for a wider range of applications in the near future.
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Molecular assembly is crucial in functional molecular materials and devices. Among the molecular interactions that can form assemblies, stacking among 7r-conjugated molecular backbones plays an essential role in charge transport t...
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Molecular assembly is crucial in functional molecular materials and devices. Among the molecular interactions that can form assemblies, stacking among 7r-conjugated molecular backbones plays an essential role in charge transport through organic materials and devices. The single-molecule junction technique allows for the application of an electric field of approximately 10~8 V/m to the nanoscale junctions and to investigate the electric field-induced assembly at the single-stacking level. Here, we demonstrate an electric field-induced stacking effect between two molecules using the scanning tunneling microscope break junction (STM-BJ) technique and we found an increase in the stacking probability with increasing intensity of the electric field. The combined density functional theory (DFT) calculations suggest that the molecules become more planar under the electric field, leading to the energetically preferred stacking configuration. Our study provides a new strategy for tuning molecular assembly by employing a strong electric field.
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The single-molecule electronic devices offer the ultimate solution to
miniaturize integrated circuits, and subthreshold swing (SS) is the key
indicator of the power consumption for single-molecule transistors but is still
quite...
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The single-molecule electronic devices offer the ultimate solution to
miniaturize integrated circuits, and subthreshold swing (SS) is the key
indicator of the power consumption for single-molecule transistors but is still
quite restricted. In this study, the redox-mediated single-molecule transistor
with a SS down to 120 mV decade~(−1) in the faradaic potential region via the
electrochemical-STM break junction (EC-STM-BJ) technique is fabricated. With
an off-state leakage current of less than 10 pA and an on/off ratio of 100, the
balance between low static power consumption and a high switching ratio is
achieved. The theoretical investigations reveal that the conductance tuning is
from the difference of transmission in the redox process. The study provides a
new strategy for the design of single-molecule transistors with promising SS,
which is essential for the potential application of single-molecule devices.
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The synergetic effect of alloy and morphology of nanocatalysts play critical roles towards ethanol electrooxidation. In this work, we developed a novel electrocatalyst fabricated by one-pot synthesis of hierarchical flower-like pa...
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The synergetic effect of alloy and morphology of nanocatalysts play critical roles towards ethanol electrooxidation. In this work, we developed a novel electrocatalyst fabricated by one-pot synthesis of hierarchical flower-like palladium (Pd)-copper (Cu) alloy nanocatalysts supported on reduced graphene oxide (Pd-Cu~((F))/RGO) for direct ethanol fuel cells. The structures of the catalysts were characterized by using scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrometer (XPS). The as-synthesized Pd-Cu~((F))/RGO nanocatalyst was found to exhibit higher electrocatalytic performances towards ethanol electrooxidation reaction in alkaline medium in contrast with RGO-supported Pd nanocatalyst and commercial Pd black catalyst in alkaline electrolyte, which could be attributed to the formation of alloy and the morphology of nanoparticles. The high performance of nanocatalyst reveals the great potential of the structure design of the supporting materials for the future fabrication of nanocatalysts.
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