Dual metal ions/BNQDs boost PMS activation over copper tungstate photocatalyst for antibiotic removal:Intermediate,toxicity assessment and mechanism

In the metal-based peroxymonosulfate(PMS)activation process,the sluggish surface redox cycle of metal ions generally hampered the efficiency of PMS activation for pollutant removal.Herein,Codoped CuWO 4/BN quantum dots(CW/Co/BNQDs)photocatalysts were developed to realize Cu^(2+)/Cu+and Co^(2+)/Co^(3+)dual ions redox cycles for PMS activation,which would facilitate the tetracycline(TC)removal.CW/4Co/2BNQDs could degrade 94.8%TC within 30 min in PMS/Vis system,and the apparent rate constant of CW/4Co/2BNQDs was 2.7 times and 1.2 times higher than those of CW and CW/4Co,respectively.The improved TC degradation performance could be attributed to the synergetic effect between BNQDs and dual redox cycles.X-ray photoelectron spectroscopy(XPS)spectra of samples before and after the reaction demonstrated that BNQDs were beneficial for accelerating the Cu^(2+)/Cu+and Co^(2+)/Co^(3+)redox cycles in CW/4Co/2BNQDs,further boosting the activation of PMS in TC degradation.Experiments of different radical scavengers revealed that the SO_(4)^(·−)/·OH/h+/^(1)O_(2)reactive species participated in the PMS activation for the TC degradation process.The possible TC degradation pathway and intermediate toxicity were detailed investigated.In addition,CW/4Co/2BNQDs exhibited outstanding photocatalytic activity over five consecutive cycles,which illustrated that it was supposed to be a reliable PMS activator over antibiotic elimination for practical application.And this work shed new light on constructing dual redox cycles for efficient PMS activation.

g-C3N4/Ag/GO Composite Photocatalyst with Efficient Photocatalytic Performance: Synthesis, Characterization, Kinetic Studies, Toxicity Assessment and Degradation Mechanism

The g-C3N4/Ag/GO(CNAG)photocatalysts were synthesized by a facile two-step reaction route.The as-prepared CNAG samples were characterized by X-ray diffraction(XRD),Fourier transform-infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),photoluminescence spectroscopy(PL)and ultraviolet-visible diffuse reflectance spectroscopy techniques(UV-vis DRS).The photocatalytic activity was obtained by degrading rhodamine B(RhB)under simulated sunlight and the results showed that photocatalytic activity of CNAG was much higher than that of pure g-C3N4 and g-C3N4/Ag.When the mass ratio of GO was 6%,the as-prepared CNAG-6%sample possessed the highest photocatalytic activity and the kinetic constant of RhB degradation was 0.077 min-1,which was almost 4.3 times higher than that of pure g-C3N4(0.018 min-1)and 2.5 times higher than that of the g-C3N4/Ag(0.031 min-1)composite,respectively.The toxicity of CNAG samples was assessed via seed germination experiment and no significant inhibitory effect was observed.The enhanced photocatalytic activity could be attributed to the synergistic effect of partial surface plasma resonance(SPR)effect of Ag,strong visible light absorption and the high separation efficiency of photon-generated carrier.The CNAG-6%sample exhibited excellent stability during the cycle experiment.Finally,a possible photocatalytic mechanism was proposed.

SYNTHESIS AND TOXICITY ASSESSMENT OF DRUGGABLE THIOSEMICARBAZONES

Introduction:There is a renewed interest for thiosemicarbazones in terms of antimicrobial,antiviral,and antitumor activity.With notable exceptions(e.g.thiopental)thiocarbonyl-containing chemical entities are commonly considered as non-druggable.Screening of a library of thiosemicarbazones showed,however,exceptional potential.The purpose of this work was both to develop

Using the nematode Caenorhabditis elegans as a model animal for assessing the toxicity induced by microcystin-LR

Among more than 75 variants of microcystin （MC）, microcystin-LR （MC-LR） is one of the most common toxins. In this study, the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied. C. elegans was treated with MC-LR at different concentrations ranging from 0.1 to 80 μg/L. The results showed that MC-LR could reduce lifespan, delay development, lengthen generation time, decrease brood size, suppress locomotion behavior, and decreases hsp-16-2-gfp expression. The endpoints of generation time, brood size, and percentage of the population expressing hsp-16-2-gfp were very sensitive to 1.0μg/L of MC-LR, and would be more useful for the evaluation of MC-LR toxicity. Furthermore, the tissue-specific hsp-16-2-gfp expressions were investigated in MC-LR-exposed animals, and the nervous system and intestine were primarily affected by MC-LR. Therefore, the generation time, brood size, and hsp-16-2-gfp expression in C. elegans can be explored to serve as valuable endpoints for evaluating the potential toxicity from MC-LR exposure.

Toxicity-based assessment of the treatment performance of wastewater treatment and reclamation processes

The reclamation and reuse of wastewater is one of the possible ways to relieve the serious fresh water resource crisis in China. Efficient reclamation treatment technologies ensure the safe reuse of reclaimed water. In order to screen out and evaluate technologies appropriate for reclamation treatment, a great deal of efforts have been brought to bear. In the present study, a toxicity-based method including a Photobacterium phosphoreum test for acute toxicity and SOS/umu test for genotoxicity, accompanied by the traditional physicochemical parameters DOC （dissolved organic carbon） and UV254 （absorbance at 254 nm）, was used to measure the treatment performance of different reclamation processes, including the anaerobic-anoxic-oxic biological process （A^2O） and subsequent physical/chemical reclamation processes （ultrafiltration, ozonation, chlorination）. It was found that for the secondary effluent after the Aao process, both the toxicity and physicochemical indices had greatly decreased compared with those of the influent. However, chemical reclamation processes such as ozonation and chlorination could possibly raise toxicity levels again. Fortunately, the toxicity elevation could be avoided by optimizing the ozone dosage and using activated carbon after ozonation. It was noted that by increasing the ozone dosage to 10 mg/L and employing activated carbon with more than 10 min hydraulic retention time, toxicity elevation was controlled. Furthermore, it was shown that pre-ozonation before activated carbon and chlorination played an important role in removing organic compounds and reducing the toxicity formation potential. The toxicity test could serve as a valuable tool to evaluate the performance of reclamation processes.

Toxic response of aquatic organisms to guide application of artemisinin sustained-release granule algaecide

In our previous study,we prepared the granules by embedding artemisinin into alginate-chitosan using microcapsule technology.These granules can release artemisinin sustainably and have a strong inhibitory effect on the growth of both single Microcystis aeruginosa and mixed algae.To safely and effectively use artemisinin sustained-release granules to control algal blooms,the ecotoxicity was studied by assessing their acute and chronic toxicity to Daphnia magna(D.magna)and Danio rerio(D.rerio),along with their antioxidant activities.The results showed that the 48-h median effective concentration(EC50)of pure artemisinin to D.magna was 24.54 mg/L and the 96-h median lethal concentration(LC50)of pure artemisinin to D.rerio was 68.08 mg/L.Both values were classified as intermediate toxicity according to the Organization for Economic Co-operation and Development(OECD).The optimal algae inhibitory concentration of artemisinin sustained-release granules(1 g/L)had low acute toxicity to both D.magna and D.rerio.The sustained-release granules had higher chronic toxicity to D.magna than to D.rerio.Partial indices of D.magna were inhibited by granules when the concentrations were larger than 0.1 g/L.Low granule concentration had an inductive effect on antioxidant enzyme activities in D.magna and D.rerio.With the increase of the exposure concentration and time,the enzyme activity presented a trend of first increasing and then decreasing,and the overall changes were significant.The change trend and range of enzyme activity indicated that the granules could cause serious oxidative stress to D.magna and D.rerio,and the changes were consistent with the results of toxicity experimentation.

Atmospheric fate of typical liquid crystal monomers in the tropospheric gas,liquid,and granular phases

Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers(LCMs).In this work,we investigated the reaction mechanisms and kinetics of three typical LCMs(4-cyano-3,5-difluorophenyl 4-ethylbenzoate(CEB-2F),4-cyano-3-fluorophenyl 4-ethylbenzoate(CEB-F),and 4-cyanophenyl 4-ethylbenzoate(CEB))with ozone(O_(3))in the atmospheric gas,liquid,and particle phases employing density functional theory(DFT).Here,O_(3)is prone to add to the benzene ring without F atom(s)in the selected LCMs.The ozonolysis products are aldehydes,carboxylic acids,epoxides,and unsaturated hydrocarbons containing aromatic rings.Those products undergo secondary ozonolysis to generate small molecular compounds such as glyoxal,which is beneficial for generating secondary organic aerosol(SOA).Titanium dioxide(TiO_(2)),an essential component of mineral aerosol particles,has good adsorption properties for LCMs;however,it slightly reduces the reactivity with O_(3).At 298 K,the reaction rate constant of the selected LCMs reacting with O_(3)in the gas and atmospheric liquid phases is(2.74–5.53)×10^(-24)cm^(3)/(mol·sec)and 5.58×10^(-3)–39.1 L/(mol·sec),while CEB-2F reacting with O_(3)on(TiO_(2))_(6)cluster is 1.84×10^(-24)cm^(3)/(mol·sec).The existence of TiO_(2)clusters increases the persistence and long-distance transportability of LCMs,which enlarges the contaminated area of LCMs.

Risk assessment for the daily intake of polycyclic aromatic hydrocarbons from the ingestion of cockle (Anadara granosa) and exposure to contaminated water and sediments along the west coast of Peninsular Malaysia

The concentration of carcinogenic polycyclic aromatic hydrocarbons （c-PAHs） present in the sediment and water of Peninsular Malaysia as well as in the cockle Anadara granosa was investigated. Samples were extracted and analysed with gas chromatographymass spectrometry. The concentrations of total carcinogenic polycyclic aromatic hydrocarbons （t-PAHs） were measured between 0.80±0.04 to 162.96 ±14.74 ng/g wet weight （ww） in sediment, between 21.85± 2.18 to 76.2± 10.82 ng/L in water samples and between 3.34 ±0.77 to 46.85 ± 5.50 ng/g ww in the cockle tissue. The risk assessment of probable human carcinogens in the Group B2 PAHs was calculated and assessed in accordance with the standards of the United States Environmental Protection Agency （US EPA）. Case I in the toxicity assessment analysed the cancer risk to consumers of Malaysian blood cockle. Case II assessed the risk of cancer from exposure to PAHs from multiple pathways. The average cancer risk of case I and case II were found to be classifiable as unsafe according to the US EPA standard. The cancer risk due to c-PAHs acquired by the ingestion of blood cockle was （8.82 ± 0.54） × 10^ 6 to （2.67 ± 0.06） × 10^-2, higher than the US EPA risk management criterion. The non-cancer risks associated with multiple pathways in Kuala Gula, Kuala Juru and Kuala Perlis were higher than the US EPA safe level, but the non-cancer risk for eating blood cockle was below the level of US EPA concern.

Insight into the role of binding interaction in the transformation of tetracycline and toxicity distribution

The transformation of free state organic micro-pollutants(MPs)has been widely studied;however,few studies have focused on mixed and bound states MPs,even though numerous ionizable organic MPs process a strong tendency to combine with dissolved organic matters in aquatic environments.This study systemically investigated the distribution and toxicity assessment of tetracycline(TET)transformation products in free,mixed and bound states during UV,UV/H2O2,UV/PS and CNTs/PS processes.A total of 33 major transformation products were identified by UPLC-Q-TOF-MSMS analysis,combining the double bond equivalence and aromaticity index calculations.The binding interaction would weaken the attack on the dimethylamino(-N(CH3)2)group and induce the direct destruction of rings A and B of TET through the analysis of 2D Kernel Density changes and density functional theory(DFT)calculations.Toxicity assessment and statistics revealed that the intermediate products with medium molecular weight(230
m/z
380)exhibited higher toxicity,which was closely related to the number of the rings in molecular structures(followed as 2»3>1z4).A predicted toxicity accumulation model(PTAM)was established to evaluate the overall toxicity changes during various oxidation processes.This finding provides new insight into the fate of bound MPs during various oxidation processes in the natural water matrix.

Development and validation of abiotic ligand model for nickel toxicity to wheat(Triticum aestivum)

A terrestrial biotic ligand model（t-BLM） was developed to predict nickel toxicity to wheat（Triticum aestivum） root elongation in hydroponic solutions. The competitive effects of five major cations（Ca^（2＋）, Mg^（2＋）, Na~＋, K~＋and H~＋） on Ni toxicity were investigated and Mg^（2＋）was found to be a strong competitor, while H＋showed less competing effect. Besides free Ni^（2＋）,the toxicity induced by the species NiHCO_3~＋ was non-neglect able at pH 〉 7 because NiHCO_3~＋ occupied a significant fraction of total Ni under such condition. Thus, a t-BLM including Ni^（2＋）, NiHCO_3~＋, Mg^（2＋）, and H＋could successfully predict the nickel toxicity to wheat root elongation and it performed better prediction than the conventional free ion activity model.In addition, the model was examined with two sets of independent experiments, which contained multiple cations and low-molecular-weight organic acids to mimic the rhizosphere condition. The developed t-BLM well predicted nickel toxicity in both experiments since it can account in both complexation and competition effects, suggesting its potential to be used in a complicated matrix like soil solution. This study provides direct evidence that the t-BLM is a reliable method for the risk assessment of nickel in terrestrial system.

Lead toxicity thresholds in 17 Chinese soils based on substrate-induced nitrification assay

The influence of soil properties on toxicity threshold values for Pb toward soil microbial processes is poorly recognized. The impact of leaching on the Pb threshold has not been assessed systematically. Lead toxicity was screened in 17 Chinese soils using a substrate-induced nitrification（SIN） assay under both leached and unleached conditions.The effective concentration of added Pb causing 50% inhibition（EC50） ranged from 185 to〉 2515 mg/kg soil for leached soil and 130 to 〉 2490 mg/kg soil for unleached soil. These results represented 〉 13- and 〉 19-fold variations among leached and unleached soils,respectively. Leaching significantly reduced Pb toxicity for 70% of both alkaline and acidic soils tested, with an average leaching factor of 3.0. Soil p H and CEC were the two most useful predictors of Pb toxicity in soils, explaining over 90% of variance in the unleached EC50 value. The relationships established in the present study predicted Pb toxicity within a factor of two of measured values. These relationships between Pb toxicity and soil properties could be used to establish site-specific guidance on Pb toxicity thresholds.

Emerging trends in organ-on-a-chip systems for drug screening

New drug discovery is under growing pressure to satisfy the demand from a wide range of domains, especially from the pharmaceutical industry and healthcare services. Assessment of drug efficacy and safety prior to human clinical trials is a crucial part of drug development, which deserves greater emphasis to reduce the cost and time in drug discovery. Recent advances in microfabrication and tissue engineering have given rise to organ-on-a-chip, an in vitro model capable of recapitulating human organ functions in vivo and providing insight into disease pathophysiology, which offers a potential alternative to animal models for more efficient pre-clinical screening of drug candidates. In this review, we first give a snapshot of general considerations for organ-on-a-chip device design. Then, we comprehensively review the recent advances in organ-on-a-chip for drug screening. Finally, we summarize some key challenges of the progress in this field and discuss future prospects of organ-on-a-chip development. Overall,this review highlights the new avenue that organ-on-a-chip opens for drug development, therapeutic innovation, and precision medicine.

Ceftriaxone sodium degradation by carbon quantum dots(CQDs)-decorated C-doped a-Bi_(2)O_(3) nanorods

A novel carbon quantum dots decorated C-doped a-Bi_(2)O_(3)photocatalyst(CBO/CQDs)was synthesized by solvothermal method.The synergistic effect of adsorption and photocatalysis highly improved contaminants removal efficiencies.The ceftriaxone sodium degradation rate constant(k)of CBO/CQDs was 11.4 and 3.2 times that of pure a-Bi2O3 and C-doped a-Bi_(2)O_(3),respectively.The interstitial carbon doping generated localized states above the valence band,which enhanced the utilization of visible light and facilitated the separation of photogenerated electrons and holes;the loading of CQDs improved the charge carrier separation and extended the visible light response;the reduced particle size of CBO/CQDs accelerated the migration of photogenerated carriers.The·O2-and ht were identified as the dominant reactive species in ceftriaxone sodium degradation,and the key role of·O2-was further investigated by NBT transformation experiments.The Fukui index was applied to ascertain the molecular bonds of ceftriaxone sodium susceptible to radical attack,and intermediates analysis was conducted to explore the possible degradation pathways.The toxicity evaluation revealed that some degradation intermediates possessed high toxicity,thus the contaminants require sufficient mineralization to ensure safe discharge.The present study makes new insights into synchronous carbon dopping and CQDs decoration on modification of a-Bi2O3,which provides references for future studies.

Polycyclic aromatic hydrocarbons (PAHs) in a sediment core from Lake Taihu and their associations with sedimentary organic matter

Sediment core is the recorder of polycyclic aromatic hydrocarbon(PAH)pollutions and the associated sedimentary organic matter(SOM),acting as crucial supports for pollution control and environmental management.Here,the sedimentary records of PAHs and SOM in the past century in Lake Taihu,China,were reconstructed from a 50-cm sediment core.On the one hand,the presence of PAHs ranged from 8.99 to 199.2 ng/g.Vertically,PAHs declined with the depth increased,and the sedimentation history of PAHswas divided into two stages with a discontinuity at 20 cm depth.In composition,PAHs in the sediment core were dominated by three-ring PAHs(44.6%±9.1%,mean±standard deviation),and were followed by four-ring(27.0%±3.3%),and five-ring(12.1%±4.0%)PAHs.In toxicity assessment,the sedimentary records of benzo[a]pyrene-based toxic equivalency were well described by an exponential model with R-square of 0.95,and the environmental background toxic value was identified as 1.62 ng/g.On the other hand,different components of SOM were successfully identified by n-alkanemarkers(p<0.01)and the variations of SOMwerewell explained(84.6%).A discontinuity of SOM was recognized at 22 cm depth.Association study showed that the sedimentary PAHs were associated with both anthropogenic and biogenic SOM(p<0.05)with explained variances for most individual PAHs of 60%.It indicated the vertical distributions of PAHs were driven by sedimentary SOM.Therefore,environmental processes such as biogenic factors should attract more attentions as well as PAH emissions to reduce the impacts of PAHs.

Evaluation of DNA adduct damage using G-quadruplex-based DNAzyme

Toxicity assessment is a major problem in pharmaceutical candidates and industry chemicals development.However,due to the lack of practical analytical methods for DNA adduct analysis,the safety evaluation of drug and industry chemicals was severely limited.Here,we develop a DNAzyme-based method to detect DNA adduct damage for toxicity assessment of drugs and chemicals.Among 18 structural variants of G4 DNAzyme,EA2 DNAzyme exhibits an obvious DNA damaging effect of styrene oxide(SO)due to its unstable structure.The covalent binding of SO to DNAzyme disrupts the Hoogsteen hydrogen bonding sites of G-plane guanines and affects the formation of the G4 quadruplex.DNA damage chemicals reduce the peroxidase activity of the G4 DNAzyme to monitor the DNA adduct damage by disrupting the structural integrity of the G4 DNAzyme.Our method for genotoxic assessment of pharmaceutical candidates and industrial chemicals can elucidate the complex chemical pathways leading to toxicity,predict toxic effects of chemicals,and evaluate possible risks to human health.

Comparing dark-and photo-Fenton-like degradation of emerging pollutant over photo-switchable Bi2WO6/CuFe2O4: Investigation on dominant reactive oxidation species

The extensive use of tetracycline hydrochloride(TCH)poses a threat to human health and the aquatic environment.Here,magnetic p-n Bi2WO6/CuFe2O4 catalyst was fabricated to efficiently remove TCH.The obtained Bi2WO6/CuFe2O4 exhibited 92.1%TCH degradation efficiency and 50.7%and 35.1%mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system,respectively.The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II)and Cu(II)/Cu(I)conversion for the Fenton-like reaction between Fe(II)/Cu(I)and H2O2,thereby generating abundant·OH for pollutant oxidation.Various environmental factors including H2O2 concentration,initial pH,catalyst dosage,TCH concentration and inorganic ions were explored.The reactive oxidation species(ROS)quenching results and electron spin resonance(ESR)spectra confirmed that·O2-and·OH were responsible for the dark and photo-Fenton-like systems,respectively.The degradation mechanisms and pathways of TCH were proposed,and the toxicity of products was evaluated.This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation.