Microplastics have become a major concern in recent years as they can be recognized as the transport vectors for pollutants in environment. In this study, the sorption behavior of two phthalate ...esters (PAEs), including diethyl phthalate (DEP) and dibutyl phthalate (DBP), onto three types of microplastics (PVC: polyvinyl chloride, PE: polyethylene, and PS: polystyrene) was investigated. The sorption isotherms of both DEP and DBP on microplastics were highly linear, suggesting that the partition was the main sorption mechanism. The Kd values of DBP were much higher than those of DEP, demonstrating that hydrophobic interaction governed the partition mechanism. Sorption of the two PAEs on the three microplastics followed the order of PS > PE > PVC, indicating that chemical properties of microplastics played an important roles in their sorption behaviors. Solution pH and natural organic matter had no significant impact on PAEs sorption by microplastics. However, the presence of NaCl and CaCl2 enhanced the sorption of both DEP and DBP because of the salting-out effect. The findings of the present study may have significant implications for the fate and transport assessment of both PAEs and microplastics.
•Sorption of PAEs on the three microplastics followed the order of PS > PE > PVC.•The highly linear sorption isotherms were governed by the partition mechanism.•The presence of NaCl and CaCl2 enhanced the sorption of PAEs on microplastics.•Solution pH and natural organic matter had no significant impact on PAEs sorption.
Fibrosis is the abnormal deposition of extracellular matrix, which can lead to organ dysfunction, morbidity, and death. The disease burden caused by fibrosis is substantial, and there are currently ...no therapies that can prevent or reverse fibrosis. Metabolic alterations are increasingly recognized as an important pathogenic process that underlies fibrosis across many organ types. As a result, metabolically targeted therapies could become important strategies for fibrosis reduction. Indeed, some of the pathways targeted by antifibrotic drugs in development - such as the activation of transforming growth factor-β and the deposition of extracellular matrix - have metabolic implications. This Review summarizes the evidence to date and describes novel opportunities for the discovery and development of drugs for metabolic reprogramming, their associated challenges, and their utility in reducing fibrosis. Fibrotic therapies are potentially relevant to numerous common diseases such as cirrhosis, non-alcoholic steatohepatitis, chronic renal disease, heart failure, diabetes, idiopathic pulmonary fibrosis, and scleroderma.
Biological ion channels are known as membrane proteins which can turn on and off under environmental stimulus to regulate ion transport and energy conversion. Rapid progress made in biological ion ...channels provides inspiration for developing artificial nanochannels to mimic the structures and functions of ion transport systems and energy conversion in biological ion channels. Due to the advantages of abundant pore channels, metal–organic frameworks (MOFs) have become competitive materials to control the nanofluidic transport. Herein, a facile in situ synthesis method is developed to prepare hybrid nanochannels constructed by 2D MOFs and porous anodic aluminum (PAA). The introduction of asymmetries in the chemical composition and surface charge properties gives the hybrid outstanding ion current rectification properties and excellent ion selectivity. A power density of 1.6 W m−2 is achieved by integrating it into a salinity‐gradient‐driven device. With advantages of facile fabrication method and high ion selectivity, the prepared 2D MOFs/PAA hybrid membrane offers a promising candidate for power conversion and water desalination.
A 2D metal–organic frameworks/porous anodic aluminum (MOFs/PAA) hybrid membrane is fabricated with a facile strategy via in situ growth of 2D MOFs on a nanoporous PAA membrane. The as‐prepared hybrid nanochannel presents obvious ionic rectification properties and excellent ion selectivity, which can be used for manipulating ion transport and efficient salinity‐gradient energy conversion.
A Variable Step Size INC MPPT Method for PV Systems Fangrui Liu, Fangrui Liu; Shanxu Duan, Shanxu Duan; Fei Liu, Fei Liu ...
IEEE transactions on industrial electronics (1982),
07/2008, Volume:
55, Issue:
7
Journal Article
Peer reviewed
Open access
Maximum power point tracking (MPPT) techniques are employed in photovoltaic (PV) systems to make full utilization of PV array output power which depends on solar irradiation and ambient temperature. ...Among all the MPPT strategies, the incremental conductance (INC) algorithm is widely used due to the high tracking accuracy at steady state and good adaptability to the rapidly changing atmospheric conditions. In this paper, a modified variable step size INC MPPT algorithm is proposed, which automatically adjusts the step size to track the PV array maximum power point. Compared with the conventional fixed step size method, the proposed approach can effectively improve the MPPT speed and accuracy simultaneously. Furthermore, it is simple and can be easily implemented in digital signal processors. A theoretical analysis and the design principle of the proposed method are provided and its feasibility is also verified by simulation and experimental results.
Adsorption of three selected pharmaceuticals and personal care products (PPCPs) (ketoprofen (KEP), carbamazepine (CBZ), and bisphenol A (BPA)) by two reduced graphene oxides (rGO1 and rGO2) and one ...commercial graphene was examined under different solution conditions. Single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and powdered graphite were also investigated for comparison. All adsorption isotherms followed the order of SWCNTs > rGO1 > rGO2 > MWCNTs > graphene > graphite, consistent with the orders of their surface areas and micropore volumes. After surface area normalization, adsorption affinities of the three PPCPs onto graphenes were lower than onto graphite, suggesting incomplete occupation for adsorption sites because of the aggregation of graphene sheets and the presence of oxygen-containing functional groups. The observed pH effects on adsorption correlated well with the pH-regulated distribution of the protonated neutral species of the three PPCPs. Increasing ionic strength from 0 to 20 mM increased KEP adsorption due to the electrostatic screening by Na(+) and Ca(2+). Both humic acid (HA) and sodium dodecylbenzenesulfonate (SDBS) suppressed PPCPs adsorption to all adsorbents, but their impacts onto graphenes were lower than those onto CNTs because of their lower adsorption by graphenes. More severe HA (or SDBS) effect was found on negatively charged KEP at the tested solution pH 6.50 due to the electrostatic repulsion between the same charged KEP and HA (or SDBS). The findings of the present study may have significant implications for the environmental fate assessment of PPCPs and graphene.
Toxicity of single microplastics on organisms has been reported widely, however, their joint toxicity with other contaminants on phytoplankton is rarely investigated. Here, we studied the toxicity of ...triclosan (TCS) with four kinds of microplastics namely polyethylene (PE, 74 μm), polystyrene (PS, 74 μm), polyvinyl chloride (PVC, 74 μm), and PVC800 (1 μm) on microalgae Skeletonema costatum. Both growth inhibition and oxidative stress including superoxide dismutase (SOD) and malondialdehyde (MDA) were determined. We found that TCS had obvious inhibition effect on microalgae growth within the test concentrations, and single microplastics also had significant inhibition effect which followed the order of PVC800 > PVC > PS > PE. However, the joint toxicity of PVC and PVC800 in combination with TCS decreased more than that of PE and PS. The higher adsorption capacity of TCS on PVC and PVC800 was one possible reason for the greater reduction of their toxicity. The joint toxicity of PVC800 was still most significant (PE < PVC < PS < PVC800) because of the minimum particle size. According to the independent action model, the joint toxicity systems were all antagonism. Moreover, the reduction of SOD was higher than MDA which revealed that the physical damage was more serious than intracellular damage. SEM images revealed that the aggregation of microplastics and physical damage on algae was obvious. Collectively, the present research provides evidences that the existence of organic pollutants is capable of influencing the effects of microplastics, and the further research on the joint toxicity of microplastics with different pollutants is urgent.
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•Joint toxicity of microplastics and triclosan on microalgae was investigated.•Antagonistic effects increased with the higher adsorption capacity of triclosan.•The particles size is more important than category for the toxicity in some degree.•The toxicity of microplastics on microalgae mainly resulted from physical damage.
Joint toxicity effect of microplastics and triclosan on microalgae was antagonism.
Crack assessment of bridge piers using unmanned aerial vehicles (UAVs) eliminates unsafe factors of manual inspection and provides a potential way for the maintenance of transportation ...infrastructures. However, the implementation of UAV‐based crack assessment for real bridge piers is hindered by several key issues, including the following: (a) both perspective distortion and the geometry distortion by nonflat structural surfaces usually appear on crack images taken by the UAV system from the pier surface; however, these two kinds of distortions are difficult to correct at the same time; and (b) the crack image taken by a close‐range inspection flight UAV system is partially imaged, containing only a small part of the entire surface of the pier, and thereby hinders crack localization. In this paper, a new image‐based crack assessment methodology for bridge piers using UAV and three‐dimensional (3D) scene reconstruction is proposed. First, the data acquisition of UAV‐based crack assessment is discussed, and the UAV flight path and photography strategy for bridge pier assessment are proposed. Second, image‐based crack detection and 3D reconstruction are conducted to obtain crack width feature pair sequences and 3D surface models, respectively. Third, a new method of projecting cracks onto a meshed 3D surface triangular model is proposed, which can correct both the perspective distortion and geometry distortion by nonflat structural surfaces, and realize the crack localization. Field test investigations of crack assessment of a real bridge pier using a UAV are carried out for illustration, validation, and error analysis of the proposed methodology.
The layer‐structured MoS2 is a typical hydrogen evolution reaction (HER) electrocatalyst but it possesses poor activity for the oxygen evolution reaction (OER). In this work, a cobalt covalent doping ...approach capable of inducing HER and OER bifunctionality into MoS2 for efficient overall water splitting is reported. The results demonstrate that covalently doping cobalt into MoS2 can lead to dramatically enhanced HER activity while simultaneously inducing remarkable OER activity. The catalyst with optimal cobalt doping density can readily achieve HER and OER onset potentials of −0.02 and 1.45 V (vs reversible hydrogen electrode (RHE)) in 1.0 m KOH. Importantly, it can deliver high current densities of 10, 100, and 200 mA cm−2 at low HER and OER overpotentials of 48, 132, 165 mV and 260, 350, 390 mV, respectively. The reported catalyst activation approach can be adapted for bifunctionalization of other transition metal dichalcogenides.
A cobalt covalent doping catalyst activation approach to induce hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctionality of MoS2 is proposed and experimentally validated, demonstrating superior bifunctional electrocatalytic activities with great application potential for overall water splitting in alkaline media.
Attached microalgae cultivation could simplify the microalgae harvest process and reduce its associated cost, which has attracted much attention recently. In this paper, the reactor patterns, ...advantages, microalgae biomass productivity, influencing factors and the microalgae physicochemical properties in the attached microalgae cultivation was summarized to show the sketch of this novel microalgae cultivation. It was concluded that the attached microalgae cultivation is advantageous in achieving less water and space consumption, higher water treatment potential and higher biomass productivity compared with the traditional suspended microalgae cultivation. The accumulation of the attached microalgae biomass showed a linear increase with culture time with the largest productivity up to 20.7 g m−2 d−1. Chlorella and Scenedesmus were the top two species that have been studied in attached culture system. Cellulose acetate/nitrate membrane, polycarbonate membrane and cotton were the most popular materials used owing to their high hydrophilicity and wide availability. Flow rate, nutrients, light, CO2 and other factors could affect the attached microalgae productivity and the physicochemical property in a way different from the suspended microalgae, which were described in detail in this review. At last, some technical bottlenecks and the corresponding solvents in the attached microalgae were suggested.
•Attached cultivation could simplify microalgae harvest process and reduce its cost.•Attached microalgae showed a linear growth with the rate up to 20.7 g m−2 d−1.•Algae species, support media and nutrients affected attached microalgae growth.•Physicochemical property and their influence factors varied with culture patterns.
Multilevel inverters are one of the preferred solutions for medium-voltage and high-power applications and have found successful industrial applications. Five-level active neutral point clamped ...inverter (5L-ANPC) is one of the most popular topologies among five-level inverters. A six-switch 5L-ANPC (6S-5L-ANPC) topology is proposed. Compared to the conventional 5L-ANPC inverters, the 6S-5L-ANPC reduces two active switches and has lower conduction loss. The proposed modulation enables the 6S-5L-ANPC inverter to operate under both active and reactive power conditions. The flying-capacitor capacitance is designed under both active and reactive power conditions. The analysis shows the proposed topology is suitable for photovoltaic grid-connected applications. A 1 KVA single-phase experimental prototype is built to verify the validity and flexibility of the proposed topology and modulation method.
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