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Nonanal, (E)-2-nonenal, (E,E)-2,4-nonadienal, and (E,Z)-2,6-nonadienal were used to study the effect of number and position of the unsaturated bond in aliphatic aldehydes on meat flavorings. Cysteine-Amadori and thiazolidine derivatives were synthesized, identified by UPLC-TOF/MS and NMR, and quantitatively by UPLC-MS/MS. The polyunsaturated aldehydes exhibited higher inhibition than monounsaturated aldehydes, and monounsaturated aldehydes exhibited higher inhibition than saturated aldehydes, mainly manifested by the inhibition of the cysteine-Amadori formation and acceleration of the thiazolidine derivatives formation. The effect of unsaturated bonds position in aliphatic aldehydes on the initial Maillard reaction stage was similar. The cysteine played an important role in catalyzing the reaction of aliphatic aldehydes. A total of 109 volatile compounds derived by heating prepared thiazolidine derivatives degradation were detected by GC-MS. Formation pathways of volatile compounds were proposed by retro-aldol, oxidation, etc. Particularly, a route to form thiazole by the decarboxylation reaction of thiazolidine derivatives which derivatives from formaldehyde reacting with cysteine was proposed.

The effect of acrolein on the formation of the 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was investigated in a chemical model. Acrolein was found to increase PhIP formation at each tested addition level. 0–0.2 mmol of acrolein increased PhIP formation dose-dependently, while high levels of acrolein (>0.2 mmol) did not further increase PhIP formation. Mechanistic study showed that acrolein addition decreased the residue of phenylalanine and creatinine, but increased the content of some key intermediates. Further analysis indicated that acrolein can react with phenylalanine, creatinine, and PhIP to form adducts. These results suggested that acrolein was able to contribute to PhIP formation as a consequence of its comprehensive ability to facilitate Strecker degradation of phenylalanine and react with phenylalanine, creatinine, and PhIP. In addition, oxidation of the tilapia fish increased the PhIP formation in the roasted fish patties, further supporting the potential contribution role of lipid oxidation products to the formation of PhIP.

Photocatalysis was an attractive strategy that had potential to tackle the Microcystin-LR (MC-LR) contamination of aquatic ecosystems. Herein, magnetic photocatalyst Fe 3 O 4 /Bi 2 WO 6 /Reduced graphene oxide composites (Bi 2 WO 6 /Fe 3 O 4 /RGO) were employed to degrade MC-LR. The removal efficiency and kinetic constant of the optimized Bi 2 WO 6 /Fe 3 O 4 /RGO (Bi 2 WO 6 /Fe 3 O 4 -40%/RGO) was 1.8 and 2.3 times stronger than the pure Bi 2 WO 6 . The improved activity of Bi 2 WO 6 /Fe 3 O 4 -40%/RGO was corresponded to the expanded visible light adsorption ability and reduction of photogenerated carrier recombination efficiency through the integration of Bi 2 WO 6 and Fe 3 O 4 -40%/RGO. The MC-LR removal efficiency exhibited a positive tendency to the initial density of algae cells, fulvic acid, and the concentration of MC-LR decreased. The existed anions (Cl - , CO 3 -2 , NO 3 - , H 2 PO 4 - ) reduced MC-LR removal efficiency of Bi 2 WO 6 /Fe 3 O 4 -40%/RGO. The Bi 2 WO 6 /Fe 3 played a significant role in MC-LR degradation. The LC-MS/MS result revealed the intermediates and possible degradation pathways.4 -40%/RGO could degrade 79.3% of MC-LR at pH = 7 after 180 min reaction process. The trapping experiments and ESR tests confirmed that the h + , ∙OH, and ∙O 2 - played a significant role in MC-LR degradation. The LC-MS/MS result revealed the intermediates and possible degradation pathways., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Bicyclic pyrroloimidazolones and pyrrolopyrimidinones were synthesized by reacting aryl-substituted 4-oxobutanoic acids with aliphatic binucleophiles with different alkyl chain lengths using a sealed vessels reactor (SVR). By varying the synthesis conditions, the reaction path was studied and formed intermediates were isolated. The structures of the obtained compounds were proved using a set of FTIR, 1H, 13C NMR spectroscopy methods and X-ray diffraction data. Temperature and pressure changes data collected during the syntheses were analyzed and assigned to the processes which occurred inside the vials. It was shown that the reaction of 4-aryl-4-oxobutanoic acids with terminal aliphatic N,N-diamines starts from the formation of corresponded (AlkN2)2+An2- salts followed by two subsequent dehydration processes giving rise to the corresponding amides and, finally, heterocycles of pyrroloimidazolone and pyrrolopyrimidinone series.

The misuse of aromatic amines like 4-chloroaniline (4-CA) has led to severe environmental and health issues. However, it's difficult to be utilized by microorganisms for degradation. Nano-zero-valent iron (nZVI) is a promising material for the remediation of chloroaniline pollution, however, the synergistic effect and mechanism of nZVI with microorganisms for the degradation of 4-CA are still unclear. This study investigated the potential of 4-CA removal by the synergistic system involving nZVI and 4-CA degrading microbial flora. The results indicate that the addition of nZVI significantly enhanced the bio-degradation rate of 4-CA from 43.13 % to 62.26 %. Under conditions involving 0.1 % nZVI addition at a 24-hour interval, pH maintained at 7, and glucose as an external carbon source, the microbial biomass, antioxidant enzymes, and dehydrogenase were significantly increased, and the optimal 4-CA degradation rate achieved 68.79 %. Additionally, gas chromatography-mass spectrometry (GC-MS) analysis of intermediates indicated that the addition of nZVI reduced compounds containing benzene rings and enhanced the dechlorination efficiency. The microbial community remained stable during the 4-CA degradation process. This study illustrates the potential of nZVI in co-microbial remediation of 4-CA compounds in the environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

There is currently a concern about the endocrine-disrupting capacity of many bisphenol A substitutes, such as BPAF, BPAP, BPB, BPC, BPC-Cl, BPE, BPF, BPS and BPZ in natural waters. However, fundamental data (i.e., kinetics and mechanisms) about the performance of advanced oxidation processes and UV radiation for water decontamination are scarce. In this study, the removal of bisphenol A substitutes was evaluated by UV/H 2 O 2 and UV treatments under neutral pH conditions. Reactivity of hydroxyl radical (·OH) with bisphenol analogues was studied by competition kinetics and their quantum yield was determined at 254 nm. Results revealed similar values of the second-order rate constants of ·OH with all bisphenols (5.89-14.1 × 10 9  M -1  s -1 ), as well as comparable values of the quantum yields (4.8-28.7 × 10 -3  mol E -1 ), except for BPC-Cl. This compound showed a remarkably high quantum yield (4.7 × 10 -1  mol E -1 ), which resulted in a removal higher than 60 % at typical UV disinfection doses (ca. 40 mJ cm -2 ). The transformation products formed by ·OH and UV-induced reactions were also assessed. Catechol and ortho-quinone derivatives were suggested as the main intermediates from the reaction of bisphenols with ·OH. Excluding BPC-Cl, the resulting photolysis products of bisphenols coincided with those from the ·OH reaction. A distinguished mechanism was proposed for the formation of the photolysis products of BPC-Cl, based on the favoured cleavage of the C-Cl bonds under UV irradiation. Phenanthrene-3,6-diol was suggested as main initial photolysis byproduct of BPC-Cl. Estrogenicity of bisphenols and detected intermediates was predicted using a Quantitative Structure-Activity Relationship (QSAR) approach. Certain byproducts produced during bisphenols reaction with ·OH, such as catechol derivatives, may exhibit estrogenic activity, as they were predicted as very strong binders. Similarly, all photolysis intermediates of BPC-Cl were predicted as very strong binders as well, suggesting that estrogenicity could persist after the treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

As a phytotoxin and synthetic chemical, coumarin (COU) is known for its hepatotoxicity and carcinogenicity. However, no thorough characterization of its microbial degradation has been reported. Here, Pseudomonas sp. strain NyZ480 was isolated for its capability of utilizing COU as the sole carbon source. Studies on its growth and degradation efficiency of COU under various conditions suggested that strain NyZ480 performed the optimum degradation at 30 ℃, pH 7, and 0.5 mM COU was completely removed within 4 h with 1% inoculum. HPLC and LC-MS analyses indicated that dihydrocoumarin (DHC), melilotic acid (MA) and 3-(2,3-dihydroxyphenyl)propionate (DHPP) were the upstream biotransformation intermediates of COU. Enzyme assay established that the initial reaction transforming COU to DHC required an NAD(P)H-dependent reductase, followed by the hydrolysis of DHC to generate MA, and the third reaction catalyzing the monooxygenation of MA to DHPP utilized a strict NADH-dependent hydroxylase. Combining genomics and transcriptomics, we proposed that the COU downstream degradation (from DHPP) was catalyzed by enzymes encoded by a gene cluster homologous to the mhp cluster for 3(3-hydroxyphenyl)propionate degradation via DHPP in E. coli. This study thoroughly identified the intermediates from the COU catabolism, providing essential insights into the molecular evidences of its biodegradation pathway., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Carbon quantum dots (CQDs) have been supported on WO 3 /TiO 2 -NRs using a hydrothermal method and a novel CQDs/WO 3 /TiO 2 -NRs composite formed via dielectric barrier discharge. The composite electrodes were characterized using morphology, structural, optical and electrochemical analysis. The CQDs were successfully prepared on the composite electrode with the highest photocurrent density reaching 2.51 mA·cm -2 under UV-visible light irradiation (100 mW·cm -2 ) and an applied voltage of 0.6 V vs. Ag/AgCl. The CQDs/WO 3 /TiO 2 -NRs electrode exhibited a good degradation effect toward bisphenol A (BPA) (75.66 %) combined with the production of hydrogen (0.89 mmol) in Na 2 SO 4 system after 2 h of the photoelectrocatalytic (PEC) reaction and the BPA degradation rate reached 100 % after 7 min of reaction in both simulated and real seawater. The CQDs/WO 3 /TiO 2 -NRs exhibited excellent stability and efficient PEC performance in which the CQDs acted as electron reservoirs to capture and promote charge separation. Our analysis of intermediates of BPA degradation indicated the possible degradation pathways that mainly formed BPA polymers in the Na 2 SO 4 system or chlorinated compounds in the high chloride salt system., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This work aimed to investigate the changes and correlations of precursors, intermediates and heterocyclic amines (HCAs) in lamb during charcoal grilling. 28 chemical compounds were detected by high-performance liquid chromatography and gas chromatography-mass spectrometry in grilled lamb from raw to charred. Results demonstrated the types and contents of HCAs were increased during grilling, of which 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) was dominant and accounted for 61% at the end of grilling (42 min). Glucose and creatine (P < 0.05) decreased with grilling time, creatinine (P < 0.05) and total free amino acid increased. The types and contents of four intermediates (formaldehyde, acetaldehyde, phenylacetaldehyde, 2,5-dimethylpyrazine) increased during grilling. Glucose, creatine, creatinine, ten free amino acids and four intermediates showed significant correlation to HCAs. Also, the ratios of four precursors were significantly correlated with HCAs (P < 0.05), besides creatine/glucose ratio. These results suggested that the time of charcoal grilling should not exceed 14 min at 145 °C in order to reduce the formation of harmful compounds in lamb meat., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Photochemical transformation of pharmaceuticals plays an important role in their natural attenuation, especially in lagoon-based wastewater treatment plants and surface waters receiving substantial sunlight. In this study, the photodegradation of five important pharmaceuticals was studied in samples obtained from a wastewater treatment plant and surface water sources. Batch photodegradation studies for a mixture of pharmaceuticals (diclofenac, sulfamethoxazole, acetaminophen, carbamazepine and gemfibrozil) were carried out in a photochemical reactor. Multiple aliquots of samples removed from the reactor during the experiment were analyzed through high-performance liquid chromatography (HPLC) coupled to a photodiode array (PDA) detector. Intermediate products formed due to photodegradation were identified by ultra-high-performance liquid chromatography coupled with a time-of-flight mass spectrometry (UHPLC-MS/MS). Diclofenac and sulfamethoxazole were found to undergo direct photodegradation due to strong light absorption, whereas the indirect route of photosensitized degradation in the presence of dissolved organic matter (DOM) and model humic acid was significant for acetaminophen, carbamazepine, and gemfibrozil. The reactive radicals such as hydroxyl (OH • ), singlet oxygen ( 1 O 2 ) and excited states of DOM (*DOM) were predominantly responsible for the indirect photodegradation of acetaminophen, gemfibrozil and carbamazepine, respectively. Computational analysis revealed that chlorine and carbon atoms belonging to the benzene ring of diclofenac were more reactive to radical attack. Sulfamethoxazole photodegradation occurred through oxidation of the NH 2 group. Acetaminophen was more susceptible to electrophilic radical attack at the O-11, and N-7 positions and carbon atoms ortho to the phenolic oxygen and the amine group. The double bonds between C-7, C-8 and C-13 were the most reactive sites for carbamazepine that participated in the phototransformation pathway. Organic matter plays a critical role in the photodegradation of emerging contaminants. The coupling of DFT calculations with UHPLC-MS/MS analysis provided insights on key functional groups participating in the phototransformation pathway. Thus, both parent pharmaceuticals and the photodegradation intermediates should be considered during wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Bisphenol F (BPF) and bisphenol S (BPS) are the most employed substitutes of bisphenol A (BPA), after being restricted by legislation in different countries because of its endocrine disrupting behaviour. In the present work, a deep study was performed about the reactivity of BPF and BPS with ozone and hydroxyl radical. Firstly, the second order rate constants of ozone with the di-protonated, mono-protonated and deprotonated species of both bisphenols were determined to be 2.38 × 10 4 , 1.31 × 10 9 and 1.43 × 10 9 M -1 s -1 for BPF and 5.01, 2.82 × 10 7 and 1.09 × 10 9 M -1 s -1 for BPS. Then, the second order rate constants for the reaction of hydroxyl radical with BPF and BPS were established through UV/H 2 O 2 and UV experiments at pH 7, resulting in the values of 8.60 × 10 9 and 6.60 × 10 9 M -1 s -1 , respectively. Finally, a study regarding the transformation products (TPs) from the reaction of both bisphenols with molecular ozone and hydroxyl radical was also performed. Hydroxylation in the ortho position of the phenol rings was observed as main degradation pathway. Additionally, most of the TPs were accumulated over the reactions at relatively high oxidant doses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

1,4-dioxane is a heterocyclic ether used as a polar industrial solvent and are released as waste discharges. 1,4-dioxane deteriorates health and quality, thereby attracts concern by the environment technologists. The need of attaining sustainable development goals have resulted in search of an eco-friendly and technically viable treatment strategy. This extensive review is aimed to emphasis on the (a) characteristics of 1,4-dioxane and their occurrence in the environment as well as their toxicity, (b) remedial strategies, such as physico-chemical treatment and advanced oxidation techniques. Special reference to bioremediation that involves diverse microbial strains and their mechanism are highlighted in this review. The role of macronutrients, stimulants and other abiotic cofactors in the biodegradation of 1,4-dioxane is discussed lucidly. We have critically discussed the inducible enzymes, enzyme-based remediation, distinct instrumental method of analyses to know the fate of intermediates produced from 1,4-dioxane biotransformation. This comprehensive survey also tries to put forth the different toxicity assessment tools used in evaluating the extent of detoxification of 1,4-dioxane achieved through biotransforming mechanism. Conclusively, the challenges, opportunities, techno-economic feasibility and future prospects of implementing 1,4-dioxane through biotechnological interventions are also discussed., (Copyright © 2022 Elsevier Inc. All rights reserved.)

To understand the conversion mechanism of photocatalytic gaseous formaldehyde (HCHO) degradation, strontium (Sr)-doped TiO 2-x -OV catalysts was designed and synthesized in this study, with comparable HCHO removal performance. Our results proved that foreign-element doping reduced Ti 4+ to the lower oxidation state Ti (4- x)+ , and that the internal charge kinetics was largely facilitated by the unbalanced electron distribution. Oxygen vacancies (OVs) were developed spontaneously to realize an electron-localized phenomenon in TiO 2-x -OV, thereby boosting O 2 adsorption and activation for the enhanced generation of reactive oxygen species (ROS). At the chemisorption stage, in-situ DRIFTS spectra and density functional theory calculation results revealed that surface adsorbed O 2 (O ads ) and lattice O (O lat ) engaged in the isomerisation of HCHO to dioxymethylene (DOM) on TiO 2-x -OV and TiO 2 , respectively. Time-resolved DRIFTS spectra under light irradiation revealed that the DOM was then converted to formate and thoroughly oxidized to CO 2 and H 2 O in TiO 2-x -OV. While bicarbonate byproducts were detected from DOM hydroxylation or possible side conversion of CO 2 in TiO 2 , owing to insufficient consumption of surface hydroxyl. Our study enhances the understanding on the photocatalytic oxidation of HCHO, thereby promoting the practical application in indoor air purification., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Recently, persulfate (PS) activation system has grown up as a primary branch of advanced oxidation processes, and biochar has been recognized as a potential nonmetal material in this field. However, few studies have focused on the corresponding relationship between actives sites on biochar and active species in AOPs. To pave this way, similar biochar (obtained from different pyrolysis temperature) with different functional structures were involved. In this study, biochar derived from swine bone (BBC) was applied in PS activation system to degrade acetaminophen (ACT). The results showed that both radical and non-radical pathway worked in the PS/BBCs systems, and the degradation rate (from 0.1042 to 0.4364 min -1 ) climbed with the increase of pyrolysis temperature (from 700 to 900 °C). To probe into the corresponding relationship between functional structure and active species, the effect of pyrolysis temperature on functional structure was analyzed. It came out that 1) defects could act as active sites for various active species; 2) persistent free radicals could do favor to the generation of 1 O 2 and O 2 - mainly contributed to the generation of high toxic intermediates (such as biphenyl and diphenyl ether) in the PS/BBCs system. Furthermore, the enhancement of adsorption capacity would mitigate the toxicity of PS/BBCs systems to some extent.4 - mainly contributed to the generation of high toxic intermediates (such as biphenyl and diphenyl ether) in the PS/BBCs system. Furthermore, the enhancement of adsorption capacity would mitigate the toxicity of PS/BBCs systems to some extent., Competing Interests: Declaration of competing interest None., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this study, two pyridine-degrading strains namely Enterobacter cloacae complex sp. BD17 and Enterobacter sp.BD19 were isolated from the aerobic tank of a pesticide wastewater treatment plant. The mixed bacteria H4 composed of BD17 and BD19 at a ratio of 1:1 was immobilized by Solidago canadensis L. stem biochar with a dosage of 2 g·L -1 . The highest pyridine removal rate of 91.70% was achieved by the immobilized H4 at an initial pyridine concentration of 200 mg·L -1 , pH of 7.0, temperature of 28 °C and salinity of 3.0% within 36 h. The main intermediates of pyridine degradation by BD17 were pyridine-2-carboxamide, 2-aminopropanediamide, and 2-aminoacetamide, while 2-picolinic acid, isopropyl acetate, isopropyl alcohol, and acetaldehyde were identified with BD19 by adopting GC-MS technique. Interestingly, there was a possibility of totally mineralization of pyridine and the corresponding degradation pathways of BD17 and BD19 were revealed for the first time., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Nornicotine, the primary nicotine metabolite that is formed through demethylation of nicotine in the genus Nicotiana tabacum L. Nornicotine is not only a precursor of tobacco-specific nitrosamine N-nitrosonornicotine but also have detrimental effects to human health. Till now, information on the biotransformation of nornicotine is limited. Herein, we identified and characterized a bacterium Arthrobacter sp. strain NOR5, utilized nornicotine as the sole of carbon and energy source, and degraded 500 mg/L nornicotine completely within 60 h under the optimum conditions of pH 7.0 and 30 °C. In this study, we not only identified previously reported intermediate metabolites such as 6-OH-nornicotine, 6-OH-mysomine, 6-OH-pseudooxy-nornicotine (6HPONor) but also identified a new intermediate metabolite 2,6-di-OH-pseudooxy-nornicotine (2,6DHPONor) by UV spectroscopy and liquid chromatography coupled with time of flight mass spectrometry. About half of 6HPONor could be transformed into 2,6DHPONor that was identified as a novel catabolic intermediate of nornicotine. By the addition of an electron acceptor 2,6-dichlorophenolindophenol (DCIP), the cell-free extract exhibited inducible 6HPONor dehydrogenase activity at 179 ± 60 mU/mg that could convert 6HPONor to 2,6DHPONor. Our study demonstrated that Arthrobacter sp. strain NOR5 has a high potential to degrade the nornicotine completely., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Volatile organic compounds (VOCs) exists ubiquitously in chemical industries and were regarded as major contributors to air pollution, which should be strictly regulated. Vacuum ultraviolet irradiation coupled with photocatalytic oxidation (VUV-PCO) has been considered as an efficient approach to VOCs removal due to high-energy photons which could break down VOCs directly and be absorbed by photocatalysts to generate free radicals for further oxidation. However, the photochemical transformation mechanisms of VOCs have not been fully revealed. Herein, we systematically analyzed the intermediates using proton-transfer-reaction mass spectrometer (PTR-MS) to explore the transformation mechanisms of toluene degradation in VUV and VUV-PCO processes. VUV-PCO process displayed superior toluene degradation efficiency (50 %) and mineralization efficiency (65 %) compared with single VUV photolysis (35 %) and UV photocatalysis (5 %). TiO 2 was deeply involved into CO 2 generalization by amplifying the advantages of VUV system and further mineralizing the intermediates. In VUV and VUV-PCO processes, O 2 participation changed the intermediates distribution by increasing multiple oxygenated products, while the introduction of water contributed to the formation and degradation of most intermediates. A possible degradation mechanism of toluene under VUV irradiation combined with TiO 2 was proposed. This study provides a deep mechanistic insight into VOCs degradation by VUV-PCO process., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, scrap irons (SI)/granular activated carbons (GAC) micro-electrolysis treatment and persulfate-releasing materials (PRM) treatment were employed to construct the combination reduction and oxidation system to treat 2,4-dinitrotoluene (2,4-DNT) contaminated groundwater. The 2,4-DNT treatment efficiencies in the PRM pre-treatment before SI/GAC micro-electrolysis treatment (FM-1 = PRM + SI/GAC) and SI/GAC micro-electrolysis pre-treatment before the PRM treatment (FM-3 = SI/GAC + PRM) were investigated in two separated columns. As control groups, the separated SI and GAC instead of the SI/GAC mixture were used in another two separated columns (FM-2 = PRM + SI + GAC; FM-4 = SI + GAC + PRM). The highest treatment efficiencies of 2,4-DNT in the FM-1 and FM-3 systems reached 79% and 93% during 5 PV, respectively. We found that the filling position of SI, GAC and PRM significantly affected the variations of pH, oxidation-reduction potential, Fe 2+ and S 2 O 8 concentrations in the combined systems. These results indicated that the SI/GAC micro-electrolysis pre-treatment of 2,4-DNT before the PRM treatment (FM-3) is more beneficial. The fifteen main intermediates in the combined system were identified by the detection of liquid chromatograph mass spectrometer. Furthermore, the possible treatment pathways of 2.4-DNT were proposed on the basis of identified intermediates. The treatment mechanisms in the FM-1 and FM-3 systems were proposed with the reduction mechanism in the SI/GAC micro-electrolysis system and the oxidation mechanism in the PRM treatment. Therefore, the combination of the reduction pre-treatment with the SI/GAC micro-electrolysis system and the oxidation post-treatment with persulfate can effectively treat the nitroaromatic compounds contaminated groundwater.2- concentrations in the combined systems. These results indicated that the SI/GAC micro-electrolysis pre-treatment of 2,4-DNT before the PRM treatment (FM-3) is more beneficial. The fifteen main intermediates in the combined system were identified by the detection of liquid chromatograph mass spectrometer. Furthermore, the possible treatment pathways of 2.4-DNT were proposed on the basis of identified intermediates. The treatment mechanisms in the FM-1 and FM-3 systems were proposed with the reduction mechanism in the SI/GAC micro-electrolysis system and the oxidation mechanism in the PRM treatment. Therefore, the combination of the reduction pre-treatment with the SI/GAC micro-electrolysis system and the oxidation post-treatment with persulfate can effectively treat the nitroaromatic compounds contaminated groundwater., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled “A comparative study on the treatment of 2,4-dinitrotoluene contaminated groundwater in the combined system: efficiencies, intermediates and mechanisms”., (Copyright © 2020. Published by Elsevier B.V.)

Cytochromes P450 bind and cleave dioxygen to generate a potent intermediate compound I, capable of hydroxylating inert hydrocarbon substrates. Cytochrome P450 119, a bacterial cytochrome P450 that serves as a good model system for the study of the intermediate states in the P450 catalytic cycle. CYP119 is found in high temperature and sulfur rich environments. Though the natural substrate and redox partner are still unknown, a potential application of such thermophilic P450s is utilizing them as biocatalysts in biotechnological industry; e.g., the synthesis of organic compounds otherwise requiring hostile environments like extremes of pH or temperature. In the present work the oxygenated complex of this enzyme bound to lauric acid, a surrogate substrate known to have a good binding affinity, was studied by a combination of cryoradiolysis and resonance Raman spectroscopy, to trap and characterize active site structures of the key fleeting enzymatic intermediates, including the peroxo and hydroperoxo species., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

A single-chamber bio-photoelectrochemical system (BPES) constructed with BiVO 4 /reduced graphene oxide (RGO) photocathode was proposed for 2,4-dichlorophenol (2,4-DCP) degradation under simulated solar irradiation. The BiVO 4 /RGO (B/G) composites were synthesized, optimized and characterized by various techniques to analyze their physico-chemical and photocatalytic properties. Results showed that B/G (5 wt% - 9 h - 150 °C) exhibited the best photocatalytic activity for 2,4-DCP degradation, which was 1.5 times of that of BiVO 4 , due to its better light absorption, faster electrons transfer, and more efficient photo-generated e - - h + separation. Reactive species trapping experiments revealed that ·OH was the main radical leading to 2,4-DCP degradation, and h + also influenced 2,4-DCP removal. The 2,4-DCP (20 mg/L) removal rate and current output from the illuminated BPES were much higher than those of the unilluminated reactor (68.5 % vs. 41.8 %, 60.31 A/m 3 vs. 40.07 A/m 3 ) in 24 h, and the cathode potential was more negative, indicating that photocathode catalytic process was favorable to pollutants degradation and energy generation. Intermediates of 2,4-DCP degradation in the BPES were identified, and accordingly, possible degradation pathway and mechanism were proposed. This research advanced the development of efficient photocathode and mechanism of recalcitrant wastewater treatment in the BPES., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Electron beam (EB) has proven to be an effective advanced oxidation reduction process (AORP) to degrade the psychiatric drug carbamazepine (CBZ); however, the degradation mechanism and the toxicity of the final reaction solutions to aquatic microorganisms needed further investigation. In this study, CBZ was eventually degraded and even mineralized by EB treatment, where the degradation of CBZ followed the pseudo-first-order kinetics with R 2  > 0.98. Acidic conditions, presence of an additional oxidant (2.5 mmol L -1 H 2 O 2 ), and O 2 /air-saturated conditions improved the degradation efficiency of CBZ, as well as the radiation chemical yield (G-value defined as the efficiency of the irradiation process). Concentrations of transient reactive species (TRS) caused by EB were quantified under different conditions at doses of 0.956 and 3.17 kGy, and the apparent quantum yield of CBZ degradation was in the order of OH > H > e aq - >H due to the generation of only a small amount of H. Findings regarding the changes of in CBZ degradation intermediates, short-chain fatty acids (SCFAs), and total organic carbon showed that CBZ can gradually be mineralized into CO aq - >H due to the generation of only a small amount of H. Findings regarding the changes of in CBZ degradation intermediates, short-chain fatty acids (SCFAs), and total organic carbon showed that CBZ can gradually be mineralized into CO 2 /CO 3 2 - , H 2 O, and NH 3 /NH 4 + by the EB process. Additionally, an excellent rotifer survival rate after 5-day culturing in the reaction solutions resulting from 5-kGy treatment indicated that EB can be a safe AORP to mineralize CBZ in solution. These findings provide scientific proof for the EB being an effective AORP for removal of psychiatric drugs from aqueous solutions, laying the foundation for future remediation research., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Developing inexpensive and stable photocatalysts without noble metals, yet remarkably enhancing the photocatalytic activities, is highly needed. Here, a novel carbon and cerium co-doped porous g-C 3 N 4 (C/Ce-CN) has been successfully prepared through thermal polymerization of the supramolecular aggregation. The morphologies, chemical structures, optical and photoelectrochemical properties of the synthesized photocatalysts were analyzed via a series of characterization measurements. Experimental results indicated that C/Ce-CN showed remarkably enhanced photocatalytic activity of TC and RhB degradation, which is about 2.6 and 2.4 times higher than that of pristine CN, and it also exhibited a good stability. Compared with bare CN, the enhanced performance of C/Ce-CN is mainly attributed to the stronger utilization rate of visible light, the rapider charge transfer rate, the longer lifetime of carriers and the larger surface specific area. The main intermediates in degradation process of antibiotics were tested by the HPLC-MS. Finally, the possible photocatalytic degradation pathways and mechanisms were proposed., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The photo-Fenton process, with UV-A LED (λ = 380-390, 390-400 and 380-400 nm) has demonstrated to be effective in the abatement of a target micropollutant, such as diphenhydramine hydrochloride (DPH). Different concentrations of iron (Fe 2+ ) and H 2 O 2 were tested and monitored, and the best results in DPH removal were obtained for the highest concentrations of both iron (II) and H 2 O 2 (10 mg Fe 2+ /L - 150 mg H 2 O 2 /L). The evolution of iron and peroxide concentration was also monitored. Kinetic studies showed that dark Fenton process prevails at the beginning of the experiment, when Fe 2+ concentration is higher. However, after these initial moments, the prevailing process is photo-Fenton and, in addition, wavelength radiation plays an important role. Concerning the effect of radiation, four LEDs (4.2 W total power) were used, emitting radiation in the wavelength range between 380-390 or 390-400 nm. Similar results were obtained in both cases in DPH removal by photo-Fenton (30 min for total elimination). However, a synergistic effect was observed when two LEDs of 380-390 nm and two LEDs of 390-400 nm were used. Total power was the same (4.2 W) in each experimental condition, but the increase in the wavelength range to 20 nm (380-400 nm) produces an increase in the rate of DPH removal, achieving its total elimination at 15 min. This fact, with the use of a simple radiation model, reveals the important role that radiation plays in the photo-Fenton process. Finally, the formed intermediates were determined and some reaction pathways were proposed., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Tetracyclines accumulation in soil environment potentially threatens agroecosystem safety. Interestingly, biochar could clean up organic pollutants, but to what extent biochar affects the removal of tetracyclines is unknown. To investigate it, five types of biochars derived from cow manure (CMB) and other four plant materials were respectively added into soils contaminated with a mixture of tetracycline, oxytetracycline, and chlortetracycline for 60-day incubation in the dark. Three parent tetracyclines and their corresponding intermediates (epitetracycline, anhydrotetracycline, epianhydrotetracycline, epioxytetracycline, epichlortetracycline, and demethylchlortetracycline) were respectively determined and named as TTCs, OTCs and CTCs. Obtained results showed biochar especially CMB could effectively remove the antibiotics (P < 0.05). Compared to control, the removal rate of TTCs, OTCs and CTCs respectively increased by up to 10.86%, 10.29% and 10.12% in CMB-added soil. The increased removal rate of the antibiotics after biochar addition was due to the increasing accessibilities for degrading microorganisms via the elevating electrical conductivity. Moreover, biochar addition might stimulate these microbial activities through the increase of C and N supplement. Our results indicate biochar accelerates the removal of tetracyclines and their intermediates by altering soil properties and thus increasing the antibiotics accessibilities, which provide insights into how biochar accelerates the removal for these antibiotics., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Aggregation of the neuronal protein α-synuclein into amyloid fibrils is a hallmark of Parkinson's disease. The propensity of α-synuclein to aggregate increases with the protein concentration. For the development of efficient inhibitors of α-synuclein aggregation, it is important to know the critical concentration of aggregation (the concentration of monomeric protein, below which the protein does not aggregate)., Methods: We performed in vitro aggregation studies of α-synuclein at low concentrations (0.11-20 μM). Aggregation kinetics was measured by ThT fluorescence. Obtained aggregates were characterized using CD-spectroscopy, fluorescent spectroscopy, dynamic light scattering and AFM imaging., Results: Monomeric α-synuclein at concentrations 0.45 μM and above was able to bind to fibril ends resulting in fibril growth. At the protein concentrations below 0.4 μM, monomers did not fibrillize, and fibrils disaggregated. In the absence of seeds, fibrils were formed only at monomer concentrations higher than 10 μM. At low micromolar concentrations, we observed formation of prefibrillar amyloid aggregates, which are able to induce fibril formation in α-synuclein solutions of high concentrations., Conclusions: The critical concentration of α-synuclein fibril growth is ~0.4 μM. Prefibrillar amyloid aggregates appear at concentrations between 0.45 and 3 μM and are an intermediate state between monomers and fibrils. Although morphologically different from fibrils, prefibrillar aggregates have similar properties to those of fibrils., General Significance: We determined the critical concentration of α-synuclein fibril growth. We showed that fibrils can grow at much lower monomer concentrations than that required for de novo fibril formation. We characterized a prefibrillar intermediate species formed upon aggregation of α-synuclein at low micromolar concentration., (Copyright © 2019. Published by Elsevier B.V.)

In this work, the photolysis of enrofloxacin (ENR), pefloxacin (PEF), and sulfaquinoxaline (SQX) in aqueous solution by UV combined with H 2 O 2 or ferrous ions (Fe(II)), as well as Fenton (Fe(II)/H 2 O 2 ) processes, was investigated. In addition, the toxicity of the final reaction solution after UV/H 2 O 2 /Fe(II) treatment toward zebrafish embryos was determined. The degradation of the test compounds followed pseudo-first-order reaction kinetics. The optimum concentrations of H 2 O 2 for ENR, PEF and SQX removal under UV/H 2 O 2 treatment were 20, 20 and 5 mM, respectively. The optimum concentrations of Fe(II) for ENR, PEF and SQX removal in the UV/Fe(II) system were 0.25, 10, and 1 mM, respectively. For the UV/H 2 O 2 /Fe(II) system, pH = 3 is the best initial pH for the degradation of ENR, PEF and SQX with the degradation efficiencies at 100%, 79.1% and 100% after 180 min, respectively. Considering the degradation rate and electrical energy per order of the test compounds, the UV/H 2 O 2 /Fe(II) process was better than the UV/H 2 O 2 and UV/Fe(II) processes because of the greater OH generation. Based on major transformation products of ENR, PEF, and SQX detected during UV/H 2 O 2 /Fe(II) treatment, the probable degradation pathway of each compound is proposed. The fluorine atom of ENR and PEF was transformed into fluorine ion, and the sulfur atom was transformed into SO 2 /SO 4 2- . The nitrogen atom was mainly transformed into NH 3 . Formic acid, acetic acid, oxalic acid, and fumaric acid were identified in the irradiated solutions and all the test compounds and their intermediates can be finally mineralized. In addition, after the UV/H 4 + . Formic acid, acetic acid, oxalic acid, and fumaric acid were identified in the irradiated solutions and all the test compounds and their intermediates can be finally mineralized. In addition, after the UV/H 2 O 2 /Fe(II) process, the acute toxicity of the final reaction solutions on zebrafish embryos was lower than that of the initial solution without any treatment. In summary, UV/H 2 O 2 /Fe(II) is a safe and efficient technology for antibiotic degradation., (Copyright © 2018. Published by Elsevier B.V.)

Thin-layer chromatography for the rapid separation of several sterols on neutral alumina impregnated with silver nitrate is described. The method is particularly effective for sterols that differ in the number and location of olefinic bonds.

Laccase has been applied extensively as a biocatalyst to remove different organic pollutants. This study characterized a spore-laccase from the bisphenol A (BPA)-degrading strain Bacillus sp. GZB. The spore-laccase was encoded with 513 amino acids, containing spore coat protein A (CotA). It showed optimal activity at 70 °C and pH = 7.2 in presence of 2, 6-dimethoxyphenol. At 60 °C, optimal activity was also seen at pH = 3.0 and pH = 6.8 with 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate) and syringaldazine, respectively. The spore-laccase was stable at high temperature, at acidic to alkaline pH values, and in the presence of different organic solvents. Spore-laccase activity was increased by introducing Cu 2+ , Mg 2+ , and Na + , but was strongly inhibited by Fe 2+ , Ag + , l-cysteine, dithiothreitol, and NaN 3 . The cotA gene was cloned and expressed in E. coli BL21 (DE3); the purified protein was estimated as having a molecular weight of ~63 kDa. Different synthetic dyes and BPA were effectively decolorized or degraded both by the spore laccase and recombinant laccase. When BPA oxidation was catalyzed using laccase, there was an initial formation of phenoxy radicals and further oxidation or CC bond cleavage of the radicals produced different organic acids. Detailed reaction pathways were developed based on nine identified intermediates. The acute toxicity decreased gradually during BPA degradation by laccase. This study is the first report about a genus of Bacillus that can produce a highly active and stable laccase to degrade BPA., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This study investigated the coupling of sulfate radical generating oxidants, (persulfate, PS and peroxymonosulfate, PMS) with TiO 2 photocatalysis for the degradation of microcystin-LR (MC-LR). Treatment efficiency was evaluated by estimating the electrical energy per order (E EO ). Oxidant addition at 4 mg/L reduced the energy requirements of the treatment by 60% and 12% for PMS and PS, respectively compared with conventional photocatalysis. Quenching studies indicated that both sulfate and hydroxyl radicals contributed towards the degradation of MC-LR for both oxidants, while Electron Paramagnetic Resonance (EPR) studies confirmed that the oxidants prolonged that lifetime of both radicals (concentration maxima shifted from 10 to 20 min), allowing for bulk diffusion and enhancing cyanotoxin removal. Structural identification of transformation products (TPs) formed during all treatments, indicated that early stage degradation of MC-LR occurred mainly on the aromatic ring and conjugated carbon double bonds of the ADDA amino acid. In addition, simultaneous hydroxyl substitution of the aromatic ring and the conjugated double carbon bonds of ADDA (m/z = 1027.5) are reported for the first time. Oxidant addition also increased the rates of formation/degradation of TPs and affected the overall toxicity of the treated samples. The detoxification and degradation order of the treatments was UVA/TiO 2 /PMS > UVA/TiO 2 /PS>> UVA/TiO 2 ., (Copyright © 2018. Published by Elsevier B.V.)

Cotinine, the primary nicotine metabolite, not only more stable and more difficult to degrade in the environment but is a potential health risk to human. To date, little is known about the biodegradation process of cotinine. In this study, a bacterial strain JQ2195 was isolated from municipal wastewater and was identified as Nocardioides sp. based on morphological, physiological characteristics, and 16 S rRNA gene phylogenetic analysis. This strain utilized cotinine as a sole carbon source and degraded 0.5 g L -1 cotinine completely within 32 h. Optimum degradation of cotinine by JQ2195 was at 30 °C and pH 7.0. Two cotinine degradation intermediates were identified as 6-hydroxy-cotinine and 6-hydroxy-3-succinoylpyridine by UV/VIS spectroscopy and liquid chromatography coupled with time-of-flight mass spectrometry. In addition, about half of cotinine was transformed to 6-hydroxy-3-succinoylpyridine which was a value-added compound for biocatalysis. When 2,6-dichlorophenolindophenol was used as an electron acceptor, the cell-free extract containing the inducible cotinine dehydrogenase could convert cotinine into 6-hydroxy-cotinine with the activity 40 ± 6 mUnmg -1 ., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Biodegradation of pharmaceutically active compounds (PhACs) in the subsurface layer of constructed wetlands (CWs) under various anaerobic redox conditions is rarely studied. In this study, CW sediment microbial populations were enriched for PhAC biodegrading organisms. Biodegradation effectivity of a mixture of six PhACs (caffeine, CAF; naproxen, NAP; metoprolol, MET; propranolol, PRO; ibuprofen, IBP; carbamazepine, CBZ) and single compounds (CAF, NAP) was investigated under nitrate reducing, sulfate reducing, and methanogenic conditions using chemical and toxicological analyses. Biodegradation efficiencies varied strongly among the six PhACs and three redox conditions chosen. CAF and NAP were completely biodegraded under sulfate reducing and methanogenic conditions whereas biodegradation efficiencies of the other PhACs were much less (MET, PRO <20%; IBP, CBZ, negligible). CAF and NAP showed significantly lower biodegradation under nitrate reducing conditions than under the other two redox conditions. No difference was found in biodegradation efficiencies of CAF and NAP when present as single compound, or as a mixture with other PhACs. Different intermediates were observed, indicating different biodegradation pathways under different redox conditions and when the PhACs were present as single compound or in a mixture. From toxicological perspective, toxicity of PhACs and/or their intermediates to Vibrio fischeri was attenuated during the biodegradation process. Chemical and toxicological data showed positive correlations in principle component analysis, by which potentially toxic PhACs and intermediates are indicated for further ecotoxicological hazard assessment., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Tetrabromobisphenol A (TBBPA), a toxic persistent pollutant, should be effectively removed from the environment. In this study, an electrochemical sequential reduction-oxidation system was proposed by controlling reaction atmosphere with Pd-Fe nanoparticles modified Ni foam (Pd-Fe/Ni) electrode as cathode for TBBPA degradation. To obtain an efficient Pd-Fe/Ni electrode for TBBPA degradation, various factors, like Pd loading, Fe 2+ adding amounts, were examined. The Pd-Fe/Ni electrode exhibited higher TBBPA conversion and debromination than the counterparts, due to the synergism of Fe 0 and electrochemical reduction. Similar TBBPA conversions and debromination ratios were observed for the cases of sparging N 2 only and sparging N 2 followed by air, which were higher than those of aeration. Reductive debromination occurred while first bubbling N 2 , forming tri-BBPA, di-BBPA, mono-BBPA and BPA; and these intermediates were likely to be further oxidized by OH generated from H 2 O 2 together with Pd-Fe/Ni electrode under aeration. Reductive and oxidative intermediates (including aromatic ring-opened product) were identified by HPLC and UPLC-QTOF-MS. Based on the intermediates, the possible TBBPA degradation mechanism and pathway were proposed. This study demonstrates that sequential reduction-oxidation process tuned by N 2 and air bubbling was favored for TBBPA degradation, thus, it should be a promising process for HOCs degradation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The treatment of two typical UV filters benzophenone-4 (BP4) and benzophenone-9 (BP9) was evaluated in aqueous solutions by UV/H 2 O 2 process. High-resolution accurate mass spectrometry (HRMS) was used to identify the degradation intermediates. A total of 12 BP4 degradation products and 17 BP9 degradation products were identified. A series of OH-initiated reactions, including hydroxylation, dihydroxylation, decarboxylation, demethylation, and ring breaking, lead to the final mineralization of BP4 and BP9. The degradation mechanisms of BP4 and BP9 are also proposed, separately. Toxicity prediction and assessment indicate that the bio-toxicity of the intermediates is higher, even if the parent compounds are completely transformed. It is necessary to further assess the environmental risk of BP4, BP9 and their intermediates in engineered systems and ambient aquatic environments., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This study aims to investigate the biodegradation of 4,5-dichloro-2-(n-octyl)-3[2H]-isothiazolone (DCOIT) by a brown-rot fungus Gloeophyllum trabeum as well as the involved mechanism. In the present study, the retentions of DCOIT in treated Masson pine (Pinus massoniana) (MP) chips were determined periodically after incubation with G. trabeum. Then a Fenton-like reaction, known as the chelator-mediated Fenton (CMF) chemistry was used to degrade DCOIT that mimics the degradation pathway of DCOIT by typical brown-rot fungi, and the degradation intermediates were further analyzed. The results demonstrated that DCOIT was rapidly depleted in the early stages of incubation by G. trabeum. The CMF treatment was shown to oxidatively decompose DCOIT by producing reactive oxygen species. This evidence suggests that the CMF chemistry employed by brown-rot fungi contributes to the rapid depletion of DCOIT during G. trabeum exposure, although this does not rule out other possible mechanisms for the biodegradation of DCOIT. The new findings give new insights into the mechanism for the biodegradation of organic biocides, and potentially provide an efficient approach for the removal of organic pollutants in the contaminated water., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A novel magnetic mesoporous nanomicrospheres Fe3O4@SiO2@mTiO2 were synthetized and characterized by a series of techniques including FE-TEM, EDS, FE-SEM, PXRD, XPS, BET, TGA as well as VSM, and subsequently tested as a photocatalyst for the degradation of Acephate, Omethoate, and Methyl parathion under UV irradiation. The well-designed nanomicrospheres exhibit a pure and highly crystalline anatase TiO2 layer, large specific surface area, and high-magnetic-response. Photocatalytic degradation of the three organophosphorus pesticides (OPPs) and the formation intermediates were identified using HPLC, TOC-Vcpn, IC, pH meter and GC-MS. Acephate, Omethoate, and Methyl parathion disappeared after 45min, 45min, and 80min UV illumination, respectively. At the end of the treatment, the total organic carbon (TOC) of the OPPs was reduced 80-85%. The main mineralization products were SO4(2-), NO3(-) and PO4(3-) and Omethoate additionally formed NO2(-). Based on the results, we proposed the photocatalytic degradation pathways for Acephate, Omethoate, and Methyl parathion., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The understanding of proteolytic processes includes manifold aspects, ranging from the characterization of proteases and their corresponding substrates to the localization of cleavage sites. The analysis of protease-catalyzed reactions at a single time-point in many cases excludes the identification of intermediate cleavage products of potential biological function. To overcome this problem, proteolysis has to be monitored over time. For that purpose, we established a straight-forward two-step approach. First, Tricine-SDS-PAGE separation of the proteolytic products is applied to survey the proteolytic reaction. In the second step, the reaction mixture is analyzed by an LC-MS set-up. An optimized chromatographic separation coupled to electrospray Orbitrap mass spectrometry allowed the simultaneous monitoring of intact substrates, intermediates and cleavage products of lower molecular weight. The applicability of the strategy was shown on the example of the gastric protease pepsin and its physiologically relevant substrate hen egg white lysozyme, one of the major egg allergens. While lysozyme-derived cysteine-free peptides were cleaved comparatively fast, disulfide bonds protected connected peptides from rapid peptic proteolysis. Two previously identified potential IgE-binding motifs were observed as disulfide-linked cleavage products. In summary, the presented approach is not only ideally suited for the simulation of gastro-intestinal digestion, which is of high interest in food research, but can be transferred to any protease-substrate pair of interest. Furthermore the strategy can be exploited to deduce the effect of post-translational modifications on proteolysis., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study investigated the photocatalytic degradation of codeine by UV-irradiated TiO2. The degradation kinetics was determined under varied conditions including the TiO2 loading, codeine concentration, and pH. Codeine and several reaction intermediates including morphine were identified and tracked during degradation using HPLC/MS-MS technique, along with TOC and IC measurements. Specifically, removal of 100 μg/L of spike codeine was complete in 3 min by contact with a 0.1 g/L suspension of TiO2 under UV irradiation at pH 7. The degradation kinetics of codeine was first-order with respect to both the catalyst TiO2 and the reactant codeine, with enhanced reaction rates with increasing pH up to pH 9. Mineralization of codeine was possible upon prolonged contact; near complete mineralization of 10 mg/L of codeine was achieved in 90 min with 0.1 g/L TiO2 under irradiation at pH 5, during which the organic nitrogen was converted to NH3-N (74%) and NO3-N (22%). Based on the identified intermediates, two degradation pathways were proposed of which one involved ipso-substitution followed by cleavage of the aromatic ring and another involved repeated hydroxylation of the codeine molecule followed by its fragmentation., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Analogues of intermediates involved in the purine salvage pathway can be exploited as potential drug molecules against enzymes of protozoan parasites. To develop such analogues we need knowledge of the solution structures, predominant tautomer at physiological pH and protonation-state of the corresponding natural ligand. In this regard, we have employed ultraviolet resonance Raman spectroscopy (UVRR) in combination with density functional theory (DFT) to study the solution structures of two relatively unexplored intermediates, 6-phosphoryl IMP (6-pIMP) and succinyl adenosine-5'-monophosphate (sAMP), of purine salvage pathway. These molecules are intermediates in a two step enzymatic process that converts inosine-5'-monpophosphate (IMP) to adenosine-5'-monophosphate (AMP). Experimental data on the molecular structure of these ligands is lacking. We report UVRR spectra of these two ligands, obtained at an excitation wavelength of 260 nm. Using isotope induced shifts and DFT calculations we assigned observed spectra to computed normal modes. We find that sAMP exists as neutral species at physiological pH and the predominant tautomer in solution bears proton at N10 position of purine ring. Though transient in solution, 6-pIMP is captured in the enzyme-bound form. This work provides the structural information of these ligands in solution state at physiological pH. We further compare these structures with the structures of AMP and IMP. Despite the presence of similar purine rings in AMP and sAMP, their UVRR spectra are found to be very different. Similarly, though the purine ring in 6-pIMP resembles that of IMP, UVRR spectra of the two molecules are distinct. These differences in the vibrational spectra provide direct information on the effects of exocyclic groups on the skeletal structures of these molecules. Our results identify key bands in the vibrational spectra of these ligands which may serve as markers of hydrogen bonding interactions upon binding to the active-sites of enzymes., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The wide distribution of bisphenol A (BPA) in the environment is problematic because of its endocrine-disrupting characteristics and toxicity. Developing cost-effective remediation methods for wide implementation is crucial. Therefore, this study investigated the BPA biodegradation ability of various microorganisms from river sediment. An acclimated microcosm completely degraded 10 mg L(-1) BPA within 28 h and transformed the contaminant into several metabolic intermediates. During the degradation process, the microbial compositions fluctuated and the final, predominant microorganisms were Pseudomonas knackmussii and Methylomonas clara. From the original river sediment, we isolated four distinct strains, which deplete the BPA over 7-9 days. They were all genetically similar to P. knackmussii. The degradation ability of mixed strains was higher than that of single strain but was far less than that of the microbial consortium. The novel BPA degradation ability of P. knackmussii and its role in the decomposing microcosm were first demonstrated. Our results revealed that microbial diversity plays a crucial role in pollutant decomposition., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A novel strain, Pusillimonas sp. T2, which is capable of degrading nicotine, was isolated and identified. This strain could completely degrade 500 mg/L nicotine within 8 h at 30 °C, pH 7.0. Six intermediates were detected and identified as 6-hydroxy-nicotine, 6-hydroxy-N-methylmyosmine, 6-hydroxypseudooxynicotine, 2,6-dihydroxypyridine, 6-hydroxy-3-succinoyl-pyridine and 2,5-dihydroxypyridine. Activities of 6-hydroxy-3-succinoyl-pyridine hydroxylase and 2,6-dihydroxypyridine hydroxylase were demonstrated in the cell extracts of strain T2, indicating that this strain may employ a novel variant of the pyridine and pyrrolidine pathways that is different from those of other species. This study provides the first evidence that Pusillimonas bacteria participate in nicotine degradation., (Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)