A hybrid photocatalytic system enables direct glucose utilization for methanogenesis.

Integration of methanogenic archaea with photocatalysts presents a sustainable solution for solar-driven methanogenesis. However, maximizing CH4 conversion efficiency remains challenging due to the intrinsic energy conservation and strictly restricted substrates of methanogenic archaea. Here, we report a solar-driven biotic-abiotic hybrid (biohybrid) system by incorporating cadmium sulfide (CdS) nanoparticles with a rationally designed methanogenic archaeon Methanosarcina acetivorans C2A, in which the glucose synergist protein and glucose kinase, an energy-efficient route for glucose transport and phosphorylation from Zymomonas mobilis, were implemented to facilitate nonnative substrate glucose for methanogenesis. We demonstrate that the photo-excited electrons facilitate membrane-bound electron transport chain, thereby augmenting the Na+ and H+ ion gradients across membrane to enhance adenosine triphosphate (ATP) synthesis. Additionally, this biohybrid system promotes the metabolism of pyruvate to acetyl coenzyme A (AcCoA) and inhibits the flow of AcCoA to the tricarboxylic acid (TCA) cycle, resulting in a 1.26-fold augmentation in CH4 production from glucose-derived carbon. Our results provide a unique strategy for enhancing methanogenesis through rational biohybrid design and reprogramming, which gives a promising avenue for sustainably manufacturing value-added chemicals.

Respiration-driven methanotrophic growth of diverse marine methanogens.

Anaerobic marine environments are the third largest producer of the greenhouse gas methane. The release to the atmosphere is prevented by anaerobic 'methanotrophic archaea (ANME) dependent on a symbiotic association with sulfate-reducing bacteria or direct reduction of metal oxides. Metagenomic analyses of ANME are consistent with a reverse methanogenesis pathway, although no wild-type isolates have been available for validation and biochemical investigation. Herein is reported the characterization of methanotrophic growth for the diverse marine methanogens Methanosarcina acetivorans C2A and Methanococcoides orientis sp. nov. Growth was dependent on reduction of either ferrihydrite or humic acids revealing a respiratory mode of energy conservation. Acetate and/or formate were end products. Reversal of the well-characterized methanogenic pathways is remarkably like the consensus pathways for uncultured ANME based on extensive metagenomic analyses.

Mechanism of transport and toxicity response of Chlorella sorokiniana to polystyrene nanoplastics.

The toxicity of nanoparticles to freshwater microalgae is of significant importance in maintaining the overall stability of aquatic ecosystems. However, the transport mechanism and toxicity response of microalgae towards nanoplastics (NPs) remain to be further investigated. In this study, we examined the toxicity and internalization mechanisms of polystyrene nanoplastics (PS-NPs) in the microalga Chlorella sorokiniana. The results revealed that the PS-NPs inhibited algal cells' growth and disrupted cell integrity upon contact, leading to cell shrinkage or rupture. Moreover, amino-modified PS-NPs (Nano-PS-NH2) exhibited greater toxicity to C. sorokiniana than carboxyl-modified PS-NPs (Nano-PS-COOH). Furthermore, significant inhibition of PS-NPs internalization was observed when four different endocytosis-related inhibitors were used, indicating that internalized PS-NPs can enter algal cells through endocytic pathways. More importantly, C. sorokiniana exposed to Nano-PS-NH2 responded to the reduction in carbon sources and energy resulting from the suppression of photosynthesis by regulating the metabolism of carbohydrates. These findings elucidate the effects of PS-NPs on C. sorokiniana, including their impact on cell morphology and metabolism, while shedding light on the internalization mechanisms of NPs by C. sorokiniana which deepen our understanding of the toxicity of nanoplastics on algae and provide important theoretical support for solving such aquatic ecological environment problems.

Do Polystyrene Nanoplastics Have Similar Effects on Duckweed (Lemna minor L.) at Environmentally Relevant and Observed-Effect Concentrations?

Although the biological effects of nanoplastics (<100 nm in size) in aquatic environments have been increasingly investigated, almost all such studies have been performed at observed-effect concentrations (higher than 1 µg/mL). The use of observed-effect concentrations of nanoplastics can provide essential data for evaluating the potential risks, but how these results apply to the effects of concentrations of nanoplastics observed in the environment remains unclear. Here, we show that exposure to both positively and negatively charged nanoplastics at the observed-effect concentration (ranging from 0 to 50 µg/mL) can result in physiological changes of Lemna minor L., a typical flowering aquatic plant species, inducing H2O2 and O2- accumulation and even cell death. However, the nanoplastics at environmentally relevant concentrations (lower than 0.1 µg/mL) had no obvious effects on phenotype of L. minor. Moreover, nanoplastics at both observed-effect and environmentally relevant concentrations were adsorbed onto the roots and fronds of the plants, whereas uptake by the roots and fronds occurred only at the observed-effect concentration. Although no phenotypic changes across 30 generations of cultivation were observed when the plants were exposed to 0.015 µg/mL nanoplastics, the expression of genes related to the response to stimuli and to oxidative and osmotic stress was upregulated under both observed-effect and environmentally relevant concentrations. Our findings suggest that the long-term presence of nanoplastics at environmentally relevant concentrations might induce some variations in the transcription level and have potential threat to floating microphytes and aquatic ecosystems.

Aged microplastics enhance their interaction with ciprofloxacin and joint toxicity on Escherichia coli.

Microplastics (MPs) in natural environments undergo complex aging processes, changing their interactions with coexisting antibiotics, and posing unpredictable ecological risks. However, the joint toxicity of aged MPs (aMPs) and antibiotics to bacteria, especially at the molecular level, is unclear. In this study, non-thermal plasma technology was used to simultaneously simulate various radical oxidation and physical reactions that occur naturally in the environment, breaking the limitation of simple aging process in laboratory aging technologies. After aging, we investigated the altered properties of aMPs, their interactions with ciprofloxacin (CIP), and the molecular responses of E. coli exposed to pristine MPs (13.5 mg/L), aMPs (13.5 mg/L), and CIP (2 µg/L) individually or simultaneously. aMPs bound far more CIP to their surfaces than pristine MPs, especially in freshwater ecosystems. Notably, the growth of E. coli exposed to aMPs alone was inhibited, whereas pristine MPs exposure didn't affect the growth of E. coli. Moreover, the most differentially expressed genes in E. coli were induced by the coexposure of aMPs and CIP. Although E. coli depended on chemotaxis to improve its flagellar rotation and escaped the stress of pollutants, the coexposure of aMPs and CIP still caused cell membrane damage, oxidative stress, obstruction of DNA replication, and osmotic imbalance in E. coli. This study filled the knowledge gap between the toxicity of aMPs and pristine MPs coexisting with antibiotics at the transcription level, helping in the accurate assessment of the potential risks of MPs to the environment.

Nanoplastics Promote Microcystin Synthesis and Release from Cyanobacterial Microcystis aeruginosa.

Although the fate of nanoplastics (<100 nm) in freshwater systems is increasingly well studied, much less is known about its potential threats to cyanobacterial blooms, the ultimate phenomenon of eutrophication occurrence worldwide. Previous studies have evaluated the consequences of nanoplastics increasing the membrane permeability of microbes, however, there is no direct evidence for interactions between nanoplastics and microcystin; intracellular hepatotoxins are produced by some genera of cyanobacteria. Here, we show that the amino-modified polystyrene nanoplastics (PS-NH2) promote microcystin synthesis and release from Microcystis aeruginosa, a dominant species causing cyanobacterial blooms, even without the change of coloration. We demonstrate that PS-NH2 inhibits photosystem II efficiency, reduces organic substance synthesis, and induces oxidative stress, enhancing the synthesis of microcystin. Furthermore, PS-NH2 promotes the extracellular release of microcystin from M. aeruginosa via transporter protein upregulation and impaired cell membrane integrity. Our findings propose that the presence of nanoplastics in freshwater ecosystems might enhance the threat of eutrophication to aquatic ecology and human health.

Auto-induction of phase I and phase II metabolism of artemisinin in healthy Chinese subjects after oral administration of a new artemisinin-piperaquine fixed combination.

BACKGROUND: Artequick is a relatively inexpensive artemisinin (Qing-hao-su; QHS)-based combination therapy (ACT) that contains QHS and piperaquine (PQ), which has not been widely used because of the decreased concentration level of QHS after repeated oral administrations for five to seven days as a monotherapy. This study was designed to evaluate the potential auto-induction metabolism of QHS in healthy Chinese adults after a two-day oral administration of QHS-PQ. The effect of QHS-PQ on the activity of the CYP2B6 and CYP3A4 was also investigated. METHODS: Fourteen healthy Chinese subjects received two-day oral doses of QHS-PQ (Artequick). A two-drug cocktail consisting of bupropion and midazolam was used to assess the activities of CYP2B6 and CYP3A, respectively. Plasma samples were analysed for QHS and its phase I/II metabolites, probe drugs and their metabolites, using a validated liquid chromatography tandem mass spectrometric (LC-MS) method. RESULTS: Four major phase I metabolites of QHS (M1-M3 and deoxy-QHS) and two subsequent phase II metabolites (M4-M5) were detected in human plasma after oral administrations of QHS-PQ. The AUC0-t of the QHS and its phase I metabolites decreased significantly (P < 0.05) with increased oral clearance (CL/F) after two-day oral doses of QHS-PQ, whereas its phase II metabolites exhibited higher AUC (P < 0.01). The phase I metabolic capability, calculated by the AUC0-t ratio of all phase I metabolites to QHS, increased 1.5-fold after the repeated dose (P < 0.01), and the phase II metabolic capability increased 1.5-fold for M4 and 3.0-fold for M5. The enzyme activity of CYP2B6 and CYP3A4 increased 2.1-fold and 3.2-fold, respectively, after two-day oral doses of QHS-PQ. CONCLUSIONS: The auto-induction of both phase I and phase II metabolism of QHS was present in healthy Chinese subjects after a recommended two-day oral dose of QHS-PQ. The auto-induction metabolism also existed for phase I metabolites of QHS. The enzyme activity of CYP2B6 and CYP3A4 was induced after the two-day oral doses of QHS-PQ. Based on these results, the alternative common three-day regimen for QHS-PQ could probably lead to lower bioavailability of QHS and higher potential of drug-drug interaction caused by the induction of drug-metabolizing enzymes.

The effect of UGTs polymorphism on the auto-induction phase II metabolism-mediated pharmacokinetics of dihydroartemisinin in healthy Chinese subjects after oral administration of a fixed combination of dihydroartemisinin-piperaquine.

BACKGROUND: Dihydroartemisinin (DHA) is a component of artemisinin-based combination therapy (ACT), which is widely recommended for treatment of uncomplicated falciparum malaria. DHA is also the main metabolite of artemether and artesunate, both of which are used in ACT. Due to auto-induction metabolism, declining plasma concentrations after the repeated dosing have been reported for artemisinin (Qing-hao-su) and artemether. This study was designed to evaluate the potential auto-induction metabolism of DHA in healthy Chinese adults after multiple oral doses of DHA. The polymorphic effects of UGT1A9 (I399C>T) and UGT2B7*2 (802C>T), the major enzymes involved in the metabolism of DHA, on the pharmacokinetic profiles of DHA and its metabolite was also studied. METHODS: Sixteen healthy Chinese subjects (four I399TT/802CC, four I399CC/802TT, four I399TT/802TT and four I399CT/802CT) received four recommended oral doses of Artekin, an ACT containing DHA (80 mg/dose) and piperaquine (PQ; 640 mg/dose), at 0, 6, 24 and 32 h. Plasma samples were analysed for DHA and its metabolite using a validated liquid chromatography tandem mass spectrometric (LC-MS) method. RESULTS: DHA and its glucuronidated metabolite DHA-Glu were detected in human plasma after oral administration of DHA-PQ. Compared with the first dose, the AUC0-t of the parent drug DHA decreased significantly (P<0.01) with increased oral clearance (CL/F) after each repeated dose of DHA-PQ, whereas its metabolite DHA-Glu did not change (P>0.05) in AUC(0-t) or C(max). The phase II metabolic capability, calculated by the AUC(0-t) ratio of DHA-Glu to the parent drug DHA, increased 1.5-fold (90% CI, 1.3-1.7), 1.2-fold (90% CI, 1.1-1.3) and 1.7-fold (90% CI, 1.5-1.8) after the second, third and fourth dose, respectively. No polymorphic effect was found for UGT1A9 (I399C>T) and UGT2B7*2 (802C>T) on the pharmacokinetic profiles of DHA and its metabolite DHA-Glu. CONCLUSIONS: The auto-induction phase II metabolism of DHA was present in healthy Chinese subjects after the recommended two-day oral doses of DHA-PQ (Artekin). The metabolic capability could recover after a 12-h dosing interval, which suggested that the alternative common three-day regimen (once daily) for DHA-PQ could probably lead to higher bioavailability of DHA. The polymorphism of UGT1A9 (I399C>T) and UGT2B7*2 (802C>T) may not be a concern during the treatment with DHA.

Effective inhibition of chloride ion interference in photocatalytic process by negatively charged molecularly imprinted photocatalyst: Behavior and mechanism.

The ubiquitous chloride ions (Cl-) in water seriously interfere with pollutant oxidation and inevitably generate undesirable chlorinated byproducts. In this study, we report for the first time that a negatively charged molecularly imprinted photocatalyst (MIP) can effectively inhibit Cl- interference and suppress the production of chlorination byproducts (the yield of chloroacetic acid was only 16 % of the bare photocatalyst system) while ensuring efficient degradation of target pollutants, thereby greatly improving the safety of the pollutant degradation process. Taking antibiotics as target pollutant, we investigated the mechanism of action of MIP by comparing the antibiotic degradation pathways, fate of photogenerated active species and production of reactive chlorine species (RCS) in the MIP and bare photocatalyst system. The mechanism by which MIP inhibits Cl- interference was mainly based on a synergy between electrostatic repulsion and steric hindrance induced by the specific capture of antibiotics in imprinted cavity, which effectively suppressed the production of RCS and hindered the participation of RCS in antibiotics degradation. In addition, MIP showed good compatibility with common cations, anions and organic matter, and performed well within a broad pH range in various water environments. Thus, the negatively charged MIP provides a feasible approach for the safe and efficient removal of pollutants in Cl- containing water.

A critical review of distribution, toxicological effects, current analytical methods and future prospects of synthetic musks in aquatic environments.

Synthetic musks (SMs) have gained widespread utilization in daily consumer products, leading to their widespread dissemination in aquatic environments through various pathways. Over the past few decades, the production of SMs has consistently risen, prompting significant concern over their potential adverse impacts on ecosystems and human health. Although several studies have focused on the development of analytical techniques for detecting SMs in biological samples and cosmetic products, a comprehensive evaluation of their global distribution in diverse aquatic media and biological matrices remains lacking. This review aims to provide an up-to-date overview of the occurrence of SMs in both aquatic and various biological matrices, investigating their worldwide distribution trends, assessing their ecological toxicity, and comparing different methodologies for processing and analysis of SMs. The findings underscore the prevalence of polycyclic musks as predominant SMs, with consumption of various products in different countries leading to contrasting distribution of contaminants. Furthermore, the migration of SMs from sediments to the water phase is investigated, indicating the role of solid-phase reservoirs. Incomplete degradation of SMs in the environment could contribute to their accumulation in aquatic systems, impacting the growth and oxidative stress of aquatic organisms, and having a possibility of genotoxicity to them. Human exposure data highlight substantial risks for vulnerable populations such as pregnant women and infants. Moreover, contemporary methods for SMs analysis are presented in this review, particularly focusing on advancements made in the last five years. Finally, research enhancement and critical questions regarding the analysis of SMs are provided, offering suggestions for future research endeavors.

Chemical Dynamics of Selenium Nanoparticles in Archaeal Systems.

Methanogenic archaea, characterized by their cell membrane lipid molecules consisting of isoprenoid chains linked to glycerol-1-phosphate via ether bonds, exhibit exceptional adaptability to extreme environments. However, this distinct lipid architecture also complicates the interactions between methanogenic archaea and nanoparticles. This study addresses this challenge by exploring the interaction and transformation of selenium nanoparticles (SeNPs) within archaeal Methanosarcina acetivorans C2A. We demonstrated that the effects of SeNPs are highly concentration-dependent, with chemical stimulation of cellular processes at lower SeNPs concentrations as well as oxidative stress and metabolic disruption at higher concentrations. Notably, we observed the formation of a protein corona on SeNPs, characterized by the selective adsorption of enzymes critical for methylotrophic methanogenesis and those involved in selenium methylation, suggesting potential alterations in protein function and metabolic pathways. Furthermore, the intracellular transformation of SeNPs into both inorganic and organic selenium species highlighted their bioavailability and dynamic transformation within archaea. These findings provide vital insights into the nano-bio interface in archaeal systems, contributing to our understanding of archaeal catalysis and its broader applications.

Development of diffusive gradients in thin-films technique for monitoring polycyclic aromatic hydrocarbons in coastal waters.

Addressing the challenge of accurately monitoring polycyclic aromatic hydrocarbons (PAHs) in aquatic systems, this study employed diffusive gradients in thin-films (DGT) technique to achieve methods detection limits as low as 0.02 ng L-1 to 0.05 ng L-1 through in situ preconcentration and determination of time-integrated concentrations. The efficacy of the developed DGT samplers was validated under diverse environmental conditions, demonstrating independence from factors such as pH (5.03-9.01), dissolved organic matter (0-20 mg L-1), and ionic strength (0.0001-0.6 M). Notably, the introduction of a novel theoretical approach to calculate diffusion coefficients based on solvent-accessible volume tailored for PAHs significantly enhanced the method's applicability, particularly for organic pollutants with low solubility. Field deployments in coastal zones validated the DGT method against traditional grab sampling, with findings advocating a 4 to 7-day optimal deployment duration for balancing sensitivity and mitigating lag time effects. These results provide a sophisticated, efficient solution to the persistent challenge of monitoring hydrophobic organic pollutants in aquatic environments, broadening the scope and applicability of DGT in environmental science and providing a robust tool for researchers.

Multi-class organic pollutants in PM2.5 in mixed area of Shanghai: Levels, sources and health risk assessment.

The occurrence of 25 multi-class pollutants comprising phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), and synthetic musks (SMs) were studied in PM2.5 samples collected at an industrial/commercial/residential/traffic mixed area in Shanghai during four seasons. During the whole period, a slight exceedance of the PM2.5 annual limit was observed, with an average of 36.8 µg/m3, and PAEs were the most predominant, accounting for >70 % of the studied organic pollutants in PM2.5, followed by PAHs and SMs. Statistically significant differences were observed for the concentrations of PM2.5, PAEs, PAHs, and SMs in winter and summer. This seasonal variation could be derived from anthropogenic activities and atmospheric dynamics. Principal component analysis (PCA) and PAHs ratios suggested a mixed source mainly derived from vehicle emissions and industrial processes. Moreover, gaseous pollutants were also accounted for, indicating the emission of PAHs might accompany the NO2 emission process. Finally, inhalation of PM2.5-bound organic pollutants for carcinogenic and non-carcinogenic risks were estimated as average values for each season, showing outside the safe levels in autumn and winter in some cases, suggesting that new policies should be to developed to reduce their emissions and protect human health in this area.

Incorporation of Selenium Derived from Nanoparticles into Plant Proteins in Vivo.

Diets comprising selenium-deficient crops have been linked to immune disorders and cardiomyopathy. Selenium nanoparticles (SeNPs) have emerged as a promising nanoplatform for selenium-biofortified agriculture. However, SeNPs fail to reach field-scale applications due to a poor understanding of the fundamental principles of its behavior. Here, we describe the transport, transformation, and bioavailability of SeNPs through a combination of in vivo and in vitro experiments. We show synthesized amorphous SeNPs, when sprayed onto the leaves of Arabidopsis thaliana, are rapidly biotransformed into selenium(IV), nonspecifically incorporated as selenomethionine (SeMet), and specifically incorporated into two selenium-binding proteins (SBPs). The SBPs identified were linked to stress and reactive oxygen species (mainly H2O2 and O2-) reduction, processes that enhance plant growth and primary root elongation. Selenium is transported both upwards and downwards in the plant when SeNPs are sprayed onto the leaves. With the application of Silwet L-77 (a common agrochemical surfactant), selenium distributed throughout the whole plant including the roots, where pristine SeNPs cannot reach. Our results demonstrate that foliar application of SeNPs promotes plant growth without causing nanomaterial accumulation, offering an efficient way to obtain selenium-fortified agriculture.

Humic acid-dependent respiratory growth of Methanosarcina acetivorans involves pyrroloquinoline quinone.

Although microbial humus respiration plays a critical role in organic matter decomposition and biogeochemical cycling of elements in diverse anoxic environments, the role of methane-producing species (methanogens) is not well defined. Here we report that a major fraction of humus, humic acid reduction enhanced the growth of Methanosarcina acetivorans above that attributed to methanogenesis when utilizing the energy sources methanol or acetate, results which showed both respiratory and fermentative modes of energy conservation. Growth characteristics with methanol were the same for an identically cultured mutant deleted for the gene encoding a multi-heme cytochrome c (MmcA), results indicating MmcA is not essential for respiratory electron transport to humic acid. Transcriptomic analyses revealed that growth with humic acid promoted the upregulation of genes annotated as cell surface pyrroloquinoline quinone (PQQ)-binding proteins. Furthermore, PQQ isolated from the membrane fraction was more abundant in humic acid-respiring cells, and the addition of PQQ improved efficiency of the extracellular electron transport. Given that the PQQ-binding proteins are widely distributed in methanogens, the findings extend current understanding of microbial humus respiration in the context of global methane dynamics.

An investigation of the auto-induction of and gender-related variability in the pharmacokinetics of dihydroartemisinin in the rat.

BACKGROUND: Artemisinin (QHS) and its derivatives dihydroartemisinin (DHA), artemether and artesunate have become the first-line anti-malarials in areas of multidrug resistance. Declining plasma concentrations during the repeated dosing have been reported for QHS, artemether and less convincingly for artesunate (ARS). However, there is limited information on whether the concentrations of their active metabolite DHA and its subsequent metabolites increased after multiple drug administrations. This study was designed to evaluate the potential auto-induction metabolism of DHA in animal species. The sex-specific effect on the pharmacokinetic profiles of DHA and its metabolites was studied. The pharmacokinetics of ARS, the prodrug of DHA, and its phase I/II metabolites were also investigated. METHODS: Two groups of rats received a single oral dose of DHA or ARS, and another two groups of rats were given oral doses of DHA or ARS once daily for five consecutive days. Plasma samples were analyzed for DHA, ARS and their phase I/II metabolites, using a validated liquid chromatography tandem mass spectrometric (LC-MS) method. RESULTS: DHA, monohydroxylated DHA (M1) and the glucuronide of DHA (DHA-G) were detected in rat plasma after oral administration of DHA or ARS. Neither DHA nor its metabolites (M1 and DHA-G) changed significantly (P > 0.05) in AUC0-t after 5-day oral doses of DHA or ARS. Sex difference was observed for DHA and its metabolites (M1 and DHA-G), whereas its prodrug ARS did not show similar characteristics for the corresponding metabolites (DHA, M1 and DHA-G). CONCLUSIONS: The results gave the direct evidence for the absence of auto-induction of phase I and phase II metabolism of DHA and ARS in rats. The sex effect existed for DHA but not for ARS, which could be caused by the sex-specific differences in absorption of DHA.

Degradation of UV-P mediated by hydroxyl radical, sulfate radical and singlet oxygen in aquatic solution: DFT and experimental studies.

2-(2'-hydroxy-5'-methylphenyl) benzotriazole (UV-P) is a type of emerging persistent organic pollutant that is reported harmful to organisms. However, its degradation mechanisms and transformation behaviors in aquatic environments are not yet clear, which are significant for better understanding its environmental fate and potential toxicological impacts. In present work, the degradation mechanisms, kinetics, half-life times and eco-toxicity assessment of UV-P initiated by hydroxyl radical (•OH), sulfate radical (SO4•‾), and singlet oxygen (1O2) are systematically studied using density functional theory (DFT) and experimental methods. The initiated reaction results show that benzene ring of UV-P is vulnerable to attack by •OH, while benzotriazole is easily attacked by SO4•‾. The kinetic calculations indicate that •OH-addition reaction R15 is dominant initial pathway. And the half-life (t1/2) of UV-P is calculated according to rate constants, t1/2 decreases rapidly with [ROS] increasing. UV-P exhibits environmental persistence when [•OH] ≤ 10-17 M. The subsequent degradation mechanisms of hydroxylated UV-P react with •OH and O2 are also calculated. A novel ring-opening reaction channel is proposed that O2-addition intermediate combines with hydroperoxyl radical (HO2•) to cleave aromatic ring. The rate-determining step is intramolecular dehydration reaction with the energy barrier of 32.98 kcal mol-1 and 41.13 kcal mol-1 to cleave benzene ring and benzotriazole ring, respectively. The degradation experiments of UV-P are conducted in Co3O4 activated potassium peroxymonosulfate (PMS) system, and liquid chromatograph-mass spectrometer (LC-MS) results identified that dihydroxylated species are main intermediates, which is consistent with theoretical calculation results. Furthermore, the eco-toxicity assessment shows that the acute and chronic toxicities of most degradation products are reduced compared with UV-P, however, their toxicity levels still keep at toxic and harmful. The environmental risk of UV-P deserves more attention.

The evaluation of Bacillus-secreted polyglutamic acid as anti-scaling treatment for circulating cooling water.

Polyaspartic acid is considered a green agent for the treatment of circulating cooling water. However, its chemosynthetic process is not green, as it requires significant amounts of energy and causes water pollution. In this work, we identified an analog of polyaspartic acid, namely polyglutamic acid (γ-PGA), which could be directly produced by Bacillus spp., and we explored its performance and scale inhibition mechanism as a scale inhibitor. We found that γ-PGA secreted by B. megaterium with a molecular weight of ~ 70 kDa showed poor scale inhibition, while the γ-PGA secreted by B. licheniformis with a molecular weight of ~ 15 kDa had a 26.87% higher efficiency compared to commercially available polyaspartic acid. The scale inhibition mechanism was explored using the γ-PGA material secreted by B. licheniformis. Fourier transform spectrometer, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy analysis demonstrated that the scale inhibition performance of γ-PGA was due to the combination of its functional groups and Ca2+, which affected the growth process of CaCO3 and inhibited the formation of CaCO3. This study provided deeper insight into scale inhibition performance related to the scale inhibition mechanism.

Metabolite identification of artemether by data-dependent accurate mass spectrometric analysis using an LTQ-Orbitrap hybrid mass spectrometer in combination with the online hydrogen/deuterium exchange technique.

Artemether (ARM), the O-methyl ether prodrug of dihydroartemisinin (DHA), is a first-line antimalarial drug used in areas of multi-drug resistance. Artemisinin drugs can be metabolized extensively in vivo and this seems related to their autoinduction pharmacokinetics. In the present study, the metabolite identification of ARM was performed by the generic data-dependent accurate mass spectrometric analysis, using high-resolution (HR) liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) and tandem mass spectrometry (MS/MS) LTQ-Orbitrap hybrid mass spectrometer in conjunction with online hydrogen (H)/deuterium (D) exchange for rapid structural characterization. The LC separation was improved allowing the separation of ARM parent drugs and their metabolites from their diastereomers. A total of 77 phase I metabolites of ARM were identified in rat liver microsomal incubates and rat urine, including dihydroartemisinin and artemisinin. In rat bile, 12 phase II metabolites were found. Accurate mass data were obtained in both full scan and HR-MS/MS mode to support assignments of metabolite structures. Online H/D exchange LC/HR-ESI-MS experiments provided additional evidence in differentiating dihydroxylated deoxy-ARM from mono-hydroxylated ARM. The results showed the main phase I metabolites of artemether are hydroxylated, dehydro, demethylated and deoxy products, and they will undergo subsequent phase II glucuronidation processes. Most metabolites were reported for the first time. This study also demonstrated the effectiveness of high-resolution mass spectrometry in combination with an online H/D exchange LC/HR-MS(n) technique in rapid identification of drug metabolites.

Kelp-derived N-doped biochar activated peroxymonosulfate for ofloxacin degradation.

N-doped carbon materials have been proven to be effective catalysts for activating peroxymonosulfate (PMS). Marine algae biomass is rich in nitrogenous substances , which can reduce the cost of N-doping process and can obtain excellent N-doped catalysts cheaply and easily. In this study, kelp biomass was selected to prepare N-doped kelp biochar (KB) materials. The high defect degree, high specific surface area, and participation of graphite N make KB have excellent catalytic degradation ability. The KB degraded 40 mg/L ofloxacin (OFL) close to 100% within 60 min, applied with PMS. Through quenching experiments and electron paramagnetic resonance spectroscopy, the degradation process dominated by non-radical pathways was determined. At the same time, O2·- and 1O2 were closely related, and a significant impact of quenching O2·- on the reaction was observed. The non-radical approach made the system excellent performance over a wide pH range and in the presence of multiple anions. The experiments of reusability confirmed the stability of the material. Its catalytic performance was restored after low-temperature pyrolysis. This research supports the use of endogenous nitrogen in biomass. It provides more options for advanced oxidation process application and marine resource development.