A comprehensive ecotoxicological evaluation of a sulfamethazine (SMZ) and sulfamethoxazole (SMX) mixture was conducted using an indicator microalga, Scenedesmus obliquus. The toxicological effects of ...this mixture were studied using microalgal growth patterns, biochemical characteristics (total chlorophyll, carotenoid, carbohydrate, fatty acid methyl ester), and elemental and Fourier-transform infrared spectroscopy analyses. The 96-h half maximal effective concentration (EC50) of the SMZ and SMX mixture was calculated to be 0.15 mg L−1 according to the dose-response curves obtained. The chlorophyll content decreased with elevated SMZ and SMX concentrations, while the carotenoid content initially increased and then decreased as concentration raised. The unsaturated fatty acid methyl esters (FAMEs) content was enhanced with higher SMZ and SMX concentrations, while that of saturated FAMEs simultaneously decreased due to SMZ and SMX stress. Elemental analyses showed an improved percentage of nitrogen and sulfur in the microalgal biomass as SMZ and SMX concentrations increased. The microalga S. obliquus was shown to biodegrade the chemicals tested and removed 31.4–62.3% of the 0.025–0.25 mg SMZ L−1 and 27.7–46.8% of the 0.025–0.25 mg SMX L−1 in the mixture after 12 days of cultivation. The greater biodegradation observed at higher SMZ and SMX concentrations indicates that microalgal degradation of SMZ and SMX could act as an efficient adaptive mechanism to antibiotics.
•S. obliquus can withstand high doses of SMZ and SMX.•EC50 of SMZ, SMX and their mixture for S. obliquus was 1.23, 0.12, and 0.15 mg L−1.•S. obliquus removed 62.3 and 46.8% of SMZ and SMX, respectively.•A greater biodegradation was observed in higher SMZ and SMX concentration.
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•Aqueous phase MP degradation using UV/persulfate method was investigated.•Degradation rate of MP followed pseudo-first-order kinetics.•MP degradation was pH dependent.•HCO3−, HPO42− ...and humic acid exhibited inhibitory effect on MP degradation.•Hydroxylation and hydrolysis were possible pathways of degradation of MP.
Methyl paraben (MP), a widely used preservative, exhibits endocrine-disrupting properties with estrogenic activities. The aqueous phase degradation of MP, using UV-activated persulfate method, was investigated in the present study. The combination of UV irradiation and persulfate anion successfully degraded MP showing 98.9% removal within 90min. A quenching experiment using ethanol (EtOH) and tert-butyl alcohol (TBA) showed the presence of both radicals (OH and SO4–) in the system; near neutral pH SO4– radical was the major species. The influence of various factors such as persulfate dose, initial MP concentration, solution pH, and water matrix components on the degradation kinetics was examined in view of the practical applications of the developed process. The degradation rate of MP was considerably increased as the amount of persulfate increased. The degradation of MP in the UV/persulfate system was pH dependent and more promising near neutral pH (6.5) conditions. The presence of anions such as Cl−, HPO42− and HCO3− showed inhibitory effect towards MP degradation. The presence of humic acid also suppressed the degradation efficiency of MP. The reaction rate followed pseudo-first-order kinetics for all of the degradations. The degradation of MP by UV/persulfate treatment led to the production of seven transformation byproducts, which were identified using ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS). A degradation pathway for MP degradation was also proposed. The results of the present study reveal that the UV/persulfate process could be an effective approach to remove MP from aqueous solutions.
Polymer solar cells (PSCs) are fabricated using a novel film deposition method, the electrostatic spray (e‐spray) technique. Stable atomization and uniform deposition of the polymer blend by e‐spray ...are achieved by manipulating the solution concentration, the solvent composition, and the electric field. The performance of PSCs is primarily influenced by the inherent film morphology of the e‐sprayed polymer‐blend active layers, which is significantly different from that of the conventional films that are formed using the spin‐coating (SC) method. The intrinsically formed interfacial boundaries between the e‐sprayed blend pancakes resist charge transport, which unfavorably influences device efficiency. The internal series resistance (RS) of the PSCs that are formed using the e‐spray method (e‐spray‐PSC) is significantly reduced by a solvent vapor soaking (SVS) treatment in addition to the conventional thermodynamic nanomorphology controls. The detailed relationship between the morphologies (film morphology and internal nanomorphology) and the RS is revealed using impedance spectroscopy. The performance of the e‐spray‐PSCs is comparable to those of the PSCs that are fabricated using the SC method under identical conditions. Therefore, the e‐spray method can be used to fabricate ultralow‐cost PSCs, because of the performance results combined with the intrinsic advantages that the e‐spray method is simple and has a low materials loss.
Polymer solar cells (PSCs) are fabricated using a novel film deposition method, the electrostatic spray (e‐spray) technique. The performance of PSCs is primarily influenced by the inherent film morphology of the e‐sprayed films, and is optimized by reducing the internal resistance. The performance of the e‐sprayed PSCs is comparable to that of the PSCs fabricated using the spin‐coating method under identical conditions.
Fatty acid analysis is an essential step in evaluating the potential of macroalgae for biodiesel production. An extraction method was developed to simultaneously analyze up to five types of ...biodiesel-fuel-related fatty acids (myristic acid, palmitic acid,
-palmitvaccenic acid, stearic acid, and oleic acid) in macroalgae using liquid chromatography and tandem mass spectrometry (LC-MS/MS). Lypophilization and solid-phase extraction (SPE) techniques were applied to improve the extraction efficiency and effectively purify samples. The optimal conditions for SPE were set by comparing the recoveries according to the various solvent conditions for each step (loading, washing, and elution). In addition, the introduction of trimethylaminoethyl (TMAE) derivatives to the hydroxyl group of the target analyte increased the ionization efficiency and sensitivity. The derivatized samples were analyzed using the LC-MS/MS method with electrospray ionization in the positive and multiple-reaction monitoring modes. The target analytes were separated and detected within 13.5 min using a CAPCELL PAK C18 MGII S3 column. Gradient elution was performed using distilled water and acetonitrile containing 5 mM ammonium acetate. This method offers a reliable and sensitive tool for the analysis of macroalgae samples for their potential use in biodiesel production. To the best of our knowledge, this is the first report on the simultaneous determination of fatty acids in macroalgae using LC-MS/MS with TMAE derivatization.
Levofloxacin (LEV), a fluoroquinolone antibiotic has been frequently observed in water resources imposing ecotoxicological effects on aquatic microbiota. The biodegradation and metabolic fate of LEV ...via a microalga, Scenedesmus obliquus in synthetic saline wastewater were investigated in this study. LEV removal (1mgL−1) by S. obliquus was relatively low in the synthetic wastewater without the addition of sodium chloride (NaCl); however, its removal increased significantly from 4.5 to 93.4% with increasing of its salinity from 0 to 171mM NaCl. Kinetic studies showed that the removal rate constant (k) increased from 0.005 to 0.289d−1 and degradation half-life decreased from 272 to 5d in the presence of NaCl (0–856mM). The removal mechanism analysis showed that the major mechanism of NaCl mediated enhancement of LEV removal was the bioaccumulation and subsequent intracellular biodegradation of LEV in microalgal cells. Six metabolites were identified via gas chromatography–mass spectrometry analysis after biodegradation of LEV. A metabolic pathway was postulated with regard to various cellular biocatalytic reactions in S. obliquus, including decarboxylation, demethylation, dehydroxylation, side chain breakdown, and ring cleavage.
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•Scenedesmus obliquus was tolerant to levofloxacin, and could withstand its high doses.•96h EC50 of levofloxacin for C. vulgaris was 65mgL−1.•Addition of NaCl stimulated the biodegradation of levofloxacin up to 93.4%.•Scenedesmus obliquus can biotransform levofloxacin in simple metabolic byproducts.
Two polymorphs of AgVO3, namely the α‐ and β‐ forms, were prepared and their physical, structural, optical, electrochemical, and photoelectrochemical characteristics were compared using a battery of ...experimental and theoretical tools. A two‐step method, previously developed in the our laboratory for the electrodeposition of inorganic semiconductor films, was applied to the electrosynthesis of silver vanadate (AgVO3) films on transparent, conducting oxide surfaces. In the first step, silver was cathodically deposited from a non‐aqueous bath containing silver nitrate. In the second step, the silver film was anodically stripped in an aqueous medium containing ammonium metavanadate. The anodically generated silver ions at the interface underwent a precipitation reaction with the vanadate species to generate the desired product in situ. Each of these steps were mechanistically corroborated via the use of electrochemical quartz crystal microgravimetry, used in conjunction with voltammetry and coulometry. As‐deposited films were crystalline and showed p‐type semiconductor behavior. Theoretical insights are provided for the electronic origin of the α→β phase transformation in AgVO3 and the disparate optical band gaps of the two polymorphs. Finally, implications for the application of this material in solar cells are provided.
Two sides of the same coin: Theoretical and experimental results are presented for two polymorphs of silver vanadate. This semiconductor material was electrodeposited via a two‐step approach pioneered in our laboratory. Electronic band structures, structural and optical data, and photoelectrochemical behavior for the two polymorphs are compared. Perspectives for solar photovoltaic applications are finally offered.
Etomidate (ET) is a commonly used sedative-hypnotic agent such as propofol to induce anesthesia, and it is rapidly metabolized to etomidate acid (ETA) in liver. Herein, a simple method to determine ...ET and ETA in urine simultaneously was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A simple sample preparation method reduced the total analysis time. For all analytes, the separation was achieved in 6.5 min using reversed-phase chromatography with gradient elution. The best separation and detection of ETA was achieved using a porous graphitic carbon column. The column temperature was maintained at 30 °C to improve the efficiency and sensitivity. The calibration curves were linear over the concentration ranges of 0.4-120.0 ng/mL (ET) and 1.0-300.0 ng/mL (ETA), obtained with a weighting factor of 1/x
. The coefficients of determination (r
) were greater than 0.9958. The lower limits of quantification were 0.4 ng/mL (ET) and 1.0 ng/mL (ETA), intra-day (n = 6) and inter-day (n = 24) precision values for all compounds were less than 10.2% and 8.4%, respectively, while the intra- and inter-day accuracies were in the -9.9-2.9%, and -7.0-0.6%. The applicability of the method was examined by analyzing the urine samples obtained from ET users.
A non-migratory antioxidant clean label was developed by photografting monomers onto a conventional packaging polymer. The polypropylene (PP) film was initially brushed with glycidyl methacrylate ...(GMA) to prepare a reactive surface with a large amount of oxirane ring (PP-g-GMA) using a photografting method. Next, a conducting polymer (p-anisidine (PA)) was immobilized on the surface of reactive film (PP-g-GMA) through a ring-opening reaction to develop an antioxidant film (PP-g-GMA-g-PA). The chemical structure and atomic composition of the surface of the antioxidant film were characterized through FTIR and XPS, respectively. In addition, the microstructure and morphology of the grafted surface were observed by SEM and AFM. A DPPH assay and electrochemical analysis showed that the PP-g-GMA-g-PA film displayed antioxidant properties and oxidation/reduction features. Moreover, the storage test in various food matrices demonstrated that the antioxidant films can prolong the shelf life of food, in which the antioxidant film significantly retarded vitamin C degradation and oil oxidation during storage. This system exhibited non-migratory characteristics; no migration residues were detected in simulant solvents after incubation, which can be used for biomedical and packaging applications.
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•Photografting of conducting polymer onto the brushed substrate planer.•P-anisidine immobilized on the surface as free-radical scavenging film.•Photographing antioxidant film to retard vitamin C degradation and oil oxidation.•Non-migratory antioxidant clean label for biomedical and packaging applications.
Estimating the measurement uncertainty (MU) is becoming increasingly mandatory in analytical toxicology. This study evaluates the uncertainty in the quantitative determination of urinary amphetamine ...(AP) and 4-hydroxyamphetamine (4HA) using a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method based on the dilute-and-shoot approach. Urine sample dilution, preparation of calibrators, calibration curve, and method repeatability were identified as the sources of uncertainty. To evaluate the MU, the Guide to the Expression of Uncertainty in Measurement (GUM) approach and the Monte Carlo method (MCM) were compared using the R programming language. The MCM afforded a smaller coverage interval for both AP (94.83, 104.74) and 4HA (10.52, 12.14) than that produced by the GUM (AP (92.06, 107.41) and 4HA (10.21, 12.45)). The GUM approach offers an underestimated coverage interval for Type A evaluation, whereas the MCM provides an exact coverage interval under an abnormal probability distribution of the measurand. The MCM is useful in complex settings where the measurand is combined with numerous distributions because it is generated from the uncertainties of input quantities based on the propagation of the distribution. Therefore, the MCM is more practical than the GUM for evaluating the MU of urinary AP and 4HA concentrations using LC–MS/MS.
Deterioration of our terrestrial environment due to decreasing soil quality brought on by crude oil spills and leakages is a major issue. In this study, soil samples were prepared by mixing clay ...(bentonite) and sand contaminated with 5 and 10 wt% crude oil (in order to study the effect of oil concentration), and weathered in a laboratory to simulate actual contaminated soil. Volatilization of light oil was inhibited in clay rich-soil, resulting in higher contamination after weathering. The efficiency of the pyrolytic treatment was evaluated by comparing the weight change and n-hexane extractable material (HEM) content of the soil samples. The working temperature influenced pyrolysis efficiency more than the reaction time. A residual amount of 0.29–0.61 wt% (below the soil pollution standard) was observed in the samples with high clay content and pollution level (by pyrolysis for 30 min at 400 °C). Infrared analysis of treated soil samples showed a reduction in alkyl functionality (CH), confirming a decrease in hydrophobicity and an improvement in water holding capacity (WHC). Seed germination and plant growth were relatively better in the pyrolyzed soil. The field applicability of the pyrolytic treatment process was confirmed at laboratory and pilot scale, as well as by treating soil samples collected from actual polluted sites.
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•Pyrolysis was used to remediate crude oil-contaminated soil.•Pyrolysis temperature influenced remediation efficiency more than the residence time.•FTIR and GC × GC confirmed changes in hydrocarbon composition.•Pyrolysis successfully treated real polluted soils in continuous treatment mode.•Seed germination was increased >50% in remediated soils.
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