Application of FeIII-TAML/H2O2 system for treatment of fluoroquinolone antibiotics.

Over the recent past, fluoroquinolone antibiotics (FQs) have raised extensive attention due to their potential to induce the formation of resistance genes and "superbugs", thus various advanced oxidation techniques have been developed to eliminate their release into the environment. In the present study, the prototype tetraamido macrocyclic ligand (FeIII-TAML)/hydrogen peroxide (H2O2) system is employed to degrade FQs (i.e., norfloxacin and ciprofloxacin) over a wide pH range (i.e., pH 6-10), and the reaction rate increases with the increase in pH level. The effect of dosage of FeIII-TAML and H2O2 on the degradation of FQs is evaluated, and the reaction rate is linearly correlated with the added amount of chemicals. Moreover, the impact of natural organic matters (NOM) on the removal of FQs is investigated, and the degradation kinetics show that both NOM type and experimental concentration exhibit negligible influence on the oxidative degradation of selected antibiotics. Based on the results of liquid chromatography-high resolution mass spectrometry and theoretical calculations, the reaction sites and pathways of FQs by FeIII-TAML/H2O2 system are further predicted and elucidated.

Hydrolysis of Chloramphenicol Catalyzed by Clay Minerals under Nonaqueous Conditions.

Soil contamination with antibiotics has raised great environmental concerns, while the abiotic degradation of antibiotics on drought soil particles has been largely ignored. In this study, we examined the transformation of chloramphenicol (CAP) on phyllosilicates under nonaqueous conditions. A significant hydrolysis of CAP mediated by kaolinite occurred under moderate relative humidities (RH: 33-76%) with the half-lives of 10-20 days. By contrast, incubation with montmorillonite did not result in detectable degradation of CAP. Infrared and Raman spectroscopies together with density functional theory calculations suggested that the surface-catalyzed CAP hydrolysis was mainly attributed to the basal plane hydroxyl groups of kaolinite, which formed hydrogen-bond interactions with the carbonyl of CAP such that the hydrolysis activation energy of CAP was greatly reduced. Neither the Brønsted nor the Lewis acidity was the determinant for the hydrolysis reaction. The surface moisture content played an essential role in CAP hydrolysis. Specifically, water facilitated the mass transfer of CAP over the low-RH range, whereas excessive water competed for the reactive hydroxyl sites. These results highlight an important but long-overlooked abiotic transformation pathway for antibiotics in field soil, where the soil moisture is low and the microbial activity is suppressed.

Rapid Hydrolysis of Penicillin Antibiotics Mediated by Adsorbed Zinc on Goethite Surfaces.

The soil environment is an important sink for penicillin antibiotics released from animal manure and wastewater, but the mineral-catalyzed transformation of penicillins in soil has not been well studied. To simulate this environmental process, we systematically investigated the behavior of penicillin G and amoxicillin, the two most widely-used penicillin antibiotics, in the presence of goethite and metal ions. The results demonstrated that Zn ions significantly promoted the hydrolysis of penicillins in goethite suspensions, as evidenced by the degradation rate nearly 3 orders of magnitude higher than that of the non-Zn-containing control. The spectroscopic analysis indicated that the specific complexation between penicillins, adsorbed Zn, and goethite was responsible for the enhanced degradation. Metastable interactions, involving hydrogen bonds between carbonyl groups in the ß-lactam ring and the double/triple hydroxyl groups on goethite surface, and coordination bonding between carboxyl groups and surface irons were proposed to stabilize the ternary reaction intermediates. Moreover, the surface zinc-hydroxide might act as powerful nucleophile to rapidly rupture the ß-lactam ring in penicillins. This study is among the first to identify the synergic roles of Zn ion and goethite in facilitating penicillin degradation and provides insights into ß-lactam antibiotics to assess their environmental risk in soil.

The trends of disease burden due to high temperature in Mainland China from 1990 to 2019 and its prediction to 2030.

The risk of high-temperature-related diseases is increasing owing to global warming. This study aimed to assess the trend of disease burden caused by high temperatures in Mainland China from 1990 to 2019 and to predict the trend of disease burden over the next 10 years. The latest data were downloaded from the Global Burden of Disease Database (GBD) for analysis, and the disease burden related to high temperature was described by mortality and disability-adjusted life-years (DALYs) and stratified by etiology, sex, and age. Statistical analyses were performed using the R software. In 2019, there were 13,907 deaths attributed to high temperatures in Mainland China, and this was 29.55% higher than the 10,735 deaths in 1990. Overall, the age-standardized mortality and DALYs attributed to high temperatures showed a downward trend from 1990 to 2019. We observed an etiological shift in high-temperature-related diseases. The age-standardized DALYs contribution attributed to high temperatures in 1990 was mainly from communicable, maternal, neonatal, and nutritional diseases (CMNND) (21.81/100,000), followed by injury (18.30/100,000) and non-communicable diseases (10.40/100,000). In 2019, the largest contribution shifted to non-communicable diseases (10.07/100,000), followed by injuries (5.21/100,000), and CMNND (2.30/100,000). The disease burden attributed to high temperatures was higher in males than in females and increased with age. In 2030, the mortality rate and DALYs due to high temperatures are predicted to decrease further, and the largest contribution will come from chronic non-communicable diseases, the occurrence of which will remain at a high level over the next 10 years. The burden of disease due to high temperatures in Mainland China is still heavy, mainly due to population aging and an increase in non-communicable diseases.

Effect of common low-molecular-weight organic acid on the photodegradation of sertraline by ferrihydrite.

Sertraline is one of the most commonly used antidepressant pharmaceuticals with ubiquitous distribution in the aqueous environment. However, the environmental behavior of sertraline in the co-presence of low-molecular-weight organic acid (LMWOA) and iron oxide mineral is still poorly understood. In this study, the photodegradation of sertraline was systematically investigated in a common photosensitizing system (ferrihydrite (Fh)-LMWOA). Six LMWOAs, including citrate acid (CA), tartrate acid (TA), malate acid (MA), lactate acid (LA), succinate acid (SA) and malonic acid (MOA) were chosen as the representatives. Our results implied that the different Fe3+ dissolution rates would lead to rather different sertraline degradation patterns following the order of Fh-CA > Fh-TA > Fh-MA > Fh-LA > Fh-SA > Fh-MOA. The reaction was initiated by the interaction between LMWOA and Fh via ligand-promoted-dissolution mechanism. Furthermore, the Fe3+ dissolution rates also showed a strong correlation with the metal-organic complexation constants, indicating that the photodegradation process is strongly related to the complexation ability of LMWOA with Fe3+. •OH, O2•- and CO2•- were detected, indicating that they contributed to the photodegradation of sertraline. •OH was demonstrated to be the dominant Reactive oxygen species (ROS) for the degradation of sertraline, and the detailed transformation pathways were proposed based on the product analysis and theoretical calculation. According to the ecological structure activity relationship estimation, the photodegradation products of sertraline possessed lower toxicity compared to the parent compound. These findings contribute to a more comprehensive understanding of the environmental fate of sertraline and evaluate its potential ecotoxicity in natural systems.

Dissolution of Fe from Fe-bearing minerals during the brown-carbonization processes in atmosphere.

Previous studies found Fe dissolution in atmosphere correlates to biomass burning, while the underlying mechanisms need to be further investigated. In this study, we reported a laboratory investigation about Fe dissolution behavior of two model Fe-bearing clay minerals of montmorillonite (SWy-2) and illite (IMt-2), and one standard mineral dust of Arizona test dust (AZTD) in atmospheric condition (pH = 2), after the minerals engaging into the brown-carbonization reaction with guaiacol, which is a commonly detected volatile phenol substance in biomass burning. The results show that the pre-brown-carbonization reaction promoted Fe dissolution from all the three minerals, attributing to the reduction of Fe(III) by gaseous guaiacol. The Fe dissolution from SWy-2, IMt-2 and AZTD were also compared under both light and dark conditions to simulate the daytime and nighttime atmospheric processes. As a result, model solar irradiation further promoted Fe dissolution from IMt-2 and AZTD, since both minerals contain moderate photo-reducible Fe(III) oxide or/and Fe(III) oxyhydroxide. The promotive effect of solar irradiation on Fe dissolution from AZTD would be gradually diminished because the photo-reactive Fe(III) is also guaiacol-reducible. Whereas, it was on the contrary for SWy-2 which does not contain the Fe(III) (oxyhydr-)oxide phase. And more dependently, the photo-induced hydroxyl radical (OH) on SWy-2 would re-oxidize the formed Fe(II), unless sufficient amount of guaiacol or brown-carbonization products on SWy-2 consumed the OH and complexed with surface coordinated Fe(III) forming photo-reducible Fe(III). The results of this study suggested the brown carbonization process on minerals would greatly mediate the Fe dissolution behavior from the Fe-bearing mineral dusts in atmosphere. Similar processes might need to be taken into consideration to accurately evaluate the input of Fe from atmosphere to open oceans.

Effect of common inorganic anions on iron-catalyzed secondary brown carbon formation from guaiacol.

Brown carbon (BrC) is the important component of aerosol with strong UV-visible absorbance. However, the formation of BrC is still elusive. Inorganic anions, e.g., Cl-, NO3- and SO42-, exist ubiquitously in the atmosphere, while their effects on the formation of BrC are poorly understood. In this study, we have systematically investigated the effects of pH (1, 2 and 3), inorganic anion (Cl-, NO3- and SO42-) and ionic strength (0.1, 0.5 and 1.0 M) on BrC generation process by measuring the optical, aggregation and product properties. Our results clearly show that the three factors strongly affect the BrC formation by influencing the oxidation activity and the complexation capability of different Fe(III) species. Marcus theory was used in this research to calculate the oxidation activity of different Fe(III) species. Among all the species of Fe(III), FeOH2+ is the most reactive form in the BrC formation reaction. Furthermore, the aggregation process of BrC was also studied, which is affected by different anions due to their different concentration and hydrability, and SO42- exhibits the highest efficiency to induce the aggregation of BrC. This study will deepen our understanding about the natural formation of BrC under environmentally relevant conditions, and be beneficial for controlling the production of atmospheric particulates and the subsequent health effects.

Enhanced alteration of poly(vinyl chloride) microplastics by hydrated electrons derived from indole-3-acetic acid assisted by a common cationic surfactant.

In this study, a new photo-irradiated reductive dechlorination pathway and the underlying transformation mechanism are described for poly(vinyl chloride) microplastics (PVC-MPs). PVC-MPs underwent photo-reductive dechlorination process with the release of chloride ions. This reaction could be facilitated in the presence of indole-3-acetic acid (IAA) and hexadecyltrimethylammonium bromide (CTAB) under neutral pH and simulated sunlight irradiation conditions. Electrostatic interaction between IAA and CTAB produced neutral IAA/CTAB complex, which might account for the enhanced adsorption of IAA on PVC powders. Upon photo-irradiation, the adsorbed IAA was excited to generate hydrated electrons (eaq-), which could pass through a shorter distance to PVC-MP surface than that derived from homogeneous IAA molecules in aqueous solution. Transient spectra of laser flash photolysis provided direct evidence for the generation of eaq-, which supported the proposed dechlorination mechanism. Based on the results of attenuated total reflectance/Fourier transform infrared (ATR/FTIR) and Raman spectra, C-Cl bond cleavage and polyene formation were involved in the structural transformation of PVC-MPs. Due to the hydrophobic effects and π-π interactions between aromatic rings and polyene structures in PVC-MP surface, the PVC-MP powders irradiated in the presence of IAA/CTAB showed an enhanced sorption for both hydrophobic and hydrophilic aromatic chemicals.

Characterization for the transformation of dissolved organic matters during ultraviolet disinfection by differential absorbance spectroscopy.

The transformation of dissolved organic matter (DOM) during various disinfection processes has raised great concerns due to the generation of carcinogenic disinfection by-products (DBPs). Ultraviolet (UV) irradiation is an effective method for drinking water disinfection, during which DOM undergoes changes in functional groups and molecular weight. In this study, the spectrophotometric titration and gel permeation chromatography (GPC) determination were employed to investigate the changes in oxygenated groups and weight-averaged molecular weight (Mw) of two typical DOM during UV irradiation. The differential absorbance spectra (DAS) of DOM could be deconvoluted into six Gaussian bands. The change of relative band intensity was attributed to the change of oxygenated groups (carboxylic and phenolic groups), which was confirmed by combining DAS data and revised Non-Ideal Competitive Adsorption -Donnan model. The GPC result demonstrated that the Mw of DOM decreased after UV disinfection. Moreover, a linear correlation between Mw and the intensity of deconvoluted Gaussian band from DAS was established, which might be served as an alternative approach to estimate Mw and predict the hydrophobicity and DBPs formation potential of DOM in drinking water treatment and monitoring.

A new pathway of monomethylmercury photodegradation mediated by singlet oxygen on the interface of sediment soil and water.

Photodegradation is an important pathway for monomethylmercury (MeHg) degradation in aquatic ecosystems. In this process, dissolved organic matter (DOM) plays an essential role. However, little information is available regarding the photo-transformation of MeHg in shallow aquatic environments, where a significant portion of MeHg is associated with soil suspensions. In this study, 14 soils sampled from different sites in China were used to simulate these conditions. Our results clearly demonstrated that soil organic matter (SOM) was the most important factor controlling the MeHg photodegradation in suspension. Degradation in this heterogeneous aqueous system was shown to be mediated by the 1O2 produced by organic matter on the surface of the soil particles rather than by DOM. This was confirmed by the strong correlation between the kinetics rate constant of MeHg degradation and steady state concentrations of 1O2 (R2 = 0.81). Our results propose a new pathway of MeHg induced by sediment soils under sunlight irradiation. Identification of this pathway may improve the estimates of potential ecological risk of Hg in shallow field ecosystems.

p43 induces IP-10 expression through the JAK-STAT signaling pathway in HMEC-1 cells.

p43 is a cofactor of aminoacyl-tRNA synthetase in mammals that effectively inhibits angiogenesis. However, the role of p43 in angiogenesis remains unclear. In the present study, we examined the effects of p43 on angiogenesis using human microvascular endothelial cells-1 (HMEC-1) cells as a model. Our microarray data showed that p43 regulated a number of cytokines, and the majoity of these are involved in the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway. IP-10 was previously shown to inhibit angiogenesis and suppress tumor growth via the JAK-STAT signaling pathway in vitro and in vivo. Our results showed that p43 induces both the mRNA and protein expression of IP-10. Furthermore, we demonstrated that p43 exerted an effect on the JAK-STAT signaling pathway by regulating key factors of the pathway. Using a JAK inhibitor, AG490, we studied the effect of p43 on HMEC-1 cells by blocking the JAK-STAT pathway. We found that AG490 inhibited the induction of IP-10 expression by p43, and suppressed the inhibitory effect of p43 on tubule formation and cell migration in HMEC-1 cells. We concluded that p43 inhibits tubule formation and cell migration by inducing IP-10 through the JAK-STAT signaling pathway, and blocking the JAK-STAT pathway with AG490 diminishes the inhibitory effects of p43 on angiogenesis.

Construction of 2,4,6-Trinitrotoluene Biosensors with Novel Sensing Elements from Escherichia coli K-12 MG1655.

Detection of 2,4,6-trinitrotoluene (TNT) has been extensively studied since it is a common explosive filling for landmines, posing significant threats to the environment and human safety. The rapid advances in synthetic biology give new hope to detect such toxic and hazardous compounds in a more sensitive and safe way. Biosensor construction anticipates finding sensing elements able to detect TNT. As TNT can induce some physiological responses in E. coli, it may be useful to define the sensing elements from E. coli to detect TNT. An E. coli MG1655 genomic promoter library containing nearly 5,400 elements was constructed. Five elements, yadG, yqgC, aspC, recE, and topA, displayed high sensing specificity to TNT and its indicator compounds 1,3-DNB and 2,4-DNT. Based on this, a whole cell biosensor was constructed using E. coli, in which green fluorescent protein was positioned downstream of the five sensing elements via genetic fusion. The threshold value, detection time, EC200 value, and other aspects of five sensing elements were determined and the minimum responding concentration to TNT was 4.75 mg/L. According to the synthetic biology, the five sensing elements enriched the reservoir of TNT-sensing elements, and provided a more applicable toolkit to be applied in genetic routes and live systems of biosensors in future.