Synergistic oxidation of Bisphenol A in a heterogeneous ultrasound-enhanced sludge biochar catalyst/persulfate process: Reactivity and mechanism.

Recently, clean-up of resistant organic compounds has attracted growing attention. In this study, a novel heterogeneous ultrasound-enhanced sludge biochar catalyst/persulfate (BC/PS/US) process was firstly developed for the degradation of bisphenol A (BPA) in water. The results revealed that BC/PS/US process could successfully achieve a positively synergistic effect between sonochemistry and catalytic chemistry on the degradation of BPA compared to its corresponding comparative process. Nearly 98% of BPA could be degraded within 80 min at optimum reaction conditions. The coexisting substances including Cl-, SO42- and NO3- had no obvious inhibition on the BPA degradation, whereas HCO3- and humic acid (HA) had significant inhibition effects on that. PS decomposition of BC/PS/US process was superior to that of BC/PS or US/PS process. Both SO4- and HO participated in the degradation of BPA, but SO4- was predominant radical in the BC/PS/US process. A possible pathway of BPA degradation was proposed, and the BPA molecule was attacked by SO4- and degraded into five kinds of intermediate products through hydroxylation and demethylation processes. This study helps to comprehend the application of sludge biochar catalyst as a persulfate activator for the degradation of organic compounds under ultrasound irradiation, and provides a new strategy in wastewater treatment.

Association of ischemic and hemorrhagic strokes hospital admission with extreme temperature in Nanchang, China-A case-crossover study.

Despite consistent evidence of a higher short-term risk of stroke mortality associated with ambient temperature, there are no findings on the association between extreme temperature and stroke. A total of 16,264 stroke hospital admissions were observed in three hospitals of Nanchang between 2008 and 2015. The case-crossover design was utilized for our study. Conditional logistic regression models were used to calculate the odds ratios. Extreme high temperature exposure during the 3days before the stroke was associated with both ischemic (OR=1.18; 95% CI: 1.07-1.36) and hemorrhagic stroke admissions (OR=1.34; 95% CI: 1.26-1.42) as compared to 3-day control periods (1-3days last week before the onset of stroke). Extreme low temperature was associated with hemorrhagic stroke admission (OR=1.42; 95% CI: 1.28-1.58) but not ischemic stroke (OR=1.06; 95% CI: 0.93-1.13). This study suggests that extreme high temperature might be a risk factor for both hemorrhagic and ischemic strokes, and that extreme low temperature might be a risk factor of hemorrhagic stroke. Further studies are necessary in order to clarify this relationship and provide evidence for stroke prevention.

Effects of Rad51 on survival of A549 cells.

Rad51, a key factor in the homologous recombination pathway for the DNA double-strand break repair, plays a vital role in genesis of non-small-cell lung cancer (NSCLC). In recent years, more and more studies indicate that high expression of Rad51 is of great relevance to resistance of NSCLC to chemotherapeutic agents and ionizing radiation. However, the underlying molecular mechanisms are poorly understood. In this study, we investigated the role of single Rad51 on cell viability in vitro. Our results show that depletion of endogenous Rad51 is sufficient to inhibit the growth of the A549 lung cancer cell line, by accumulating cells in G1 phase and inducing cell death. We conclude that independent Rad51 expression is critical to the survival of A549 cells and can be an independent prognostic factor in NSCLC patients.

Determination of decabrominated diphenyl ether in soils by Soxhlet extraction and high performance liquid chromatography.

This study described the development of a method based on Soxhlet extraction combining high performance liquid chromatography (Soxhlet-HPLC) for the accurate detection of BDE-209 in soils. The solvent effect of working standard solutions in HPLC was discussed. Results showed that 1:1 of methanol and acetone was the optimal condition which could totally dissolve the BDE-209 in environmental samples and avoid the decrease of the peak area and the peak deformation difference of BDE-209 in HPLC. The preliminary experiment was conducted on the configured grassland (1 µ g/g) to validate the method feasibility. The method produced reliable reproducibility, simulated soils (n = 4) RSD 1.0%, and was further verified by the analysis e-waste contaminated soils, RSD range 5.9-11.4%. The contamination level of BDE-209 in burning site was consistent with the previous study of Longtang town but lower than Guiyu town, and higher concentration of BDE-209 in paddy field mainly resulted from the long-standing disassembling area nearby. This accurate and fast method was successfully developed to extract and analyze BDE-209 in soil samples, showing its potential use for replacing GC to determinate BDE-209 in soil samples.

[Effect of covalent functionalization on DNA cleavage activity and ROS formation of single-walled carbon nanotubes].

Biotoxicity of selected covalent functionalizaed single-walled carbon nanotubes (SWNTs) was investigated by plasmid DNA cleavage assay. The effect of covalent functionalization on the physical structural and chemical activity of SWNTs was also studied by Vis-NIR spectroscopy, Raman spectroscopy and ROS assay. The DNA cleavage intensity was promoted by covalent functionalization, and the intensity of DNA damage caused by the three types of carbon nanotubes in a descending order was found to be carboxylated SWNTs (SWNT-COOH) > polyethyleneglycol-lated SWNTs (SWNT-PEG) > uncovalent functionalized SWNTs (uSWNTs). SWNTs were efficient intermediate to trigger electron transfer from electron donor to O2 in dark condition which lead to superoxide radical (O2*-) formation. The electron transfer intensity caused by selected SWNTs was also SWNT-COOH > SWNT-PEG > SWNTs. The reason is that defect sites which changed from sp2-hybridized carbon atom on the side wall of carbon nanotubes were more reactive than the perfect ones.

Dechlorination pathways of diverse chlorinated aromatic pollutants conducted by Dehalococcoides sp. strain CBDB1.

Dechlorination of chlorinated aromatic pollutants (CAPs) has become a major issue in recent decades. This paper reported a theoretical indicator for predicting the reductive dechlorination pathways of polychlorinated dibenzo-p-dioxins (PCDDs), chlorobenzenes and chlorophenols transformed by Dehalococcoides sp. strain CBDB1. Density functional theory (DFT) calculations were carried out at the B3LYP/6-31G(d) level for all related CAPs and Mulliken atomic charges on chlorine atoms (Q(Cl(n))) were adopted as the probe of the dechlorination reaction activity. Q(Cl(n)) can consistently indicate the main dechlorination daughter products of PCDDs, chlorobenzenes and chlorophenols conducted by strain CBDB1. The dechlorination reaction favors elimination of the chlorine atoms having greater Q(Cl(n)) values. The chlorine atom with the greatest Q(Cl(n)) value tends preferentially to be eliminated, whereas the chlorine atom with the smallest Q(Cl()(n)()) value tends unlikely to be eliminated or does not react at all. For a series of compounds having similar structure, the maximal Q(Cl(n)) of each molecular can be used to predict the possibility of its daughter product(s). In addition, the difference (Q(Cl(n))) between the maximal Q(Cl(n)) and the next maximal Q(Cl(n)) of the same molecule can be used to assess the possibility of formation of multiple dechlorination products.

Rapid degradation of phenanthrene by using Sphingomonas sp. GY2B immobilized in calcium alginate gel beads.

The strain Sphingomonas sp. GY2B is a high efficient phenanthrene-degrading strain isolated from crude oil contaminated soils that displays a broad-spectrum degradation ability towards PAHs and related aromatic compounds. This paper reports embedding immobilization of strain GY2B in calcium alginate gel beads and the rapid degradation of phenanthrene by the embedded strains. Results showed that embedded immobilized strains had high degradation percentages both in mineral salts medium (MSM) and 80% artificial seawater (AS) media, and had higher phenanthrene degradation efficiency than the free strains. More than 90% phenanthrene (100 mg x L(-1)) was degraded within 36 h, and the phenanthrene degradation percentages were >99.8% after 72 h for immobilized strains. 80% AS had significant negative effect on the phenanthrene degradation rate (PDR) of strain GY2B during the linear-decreasing stage of incubation and preadsorption of cells onto rice straw could improve the PDR of embedded strain GY2B. The immobilization of strain GY2B possesses a good potential for application in the treatment of industrial wastewater containing phenanthrene and other related aromatic compounds.

Modeling and prediction of photolysis half-lives of polycyclic aromatic hydrocarbons in aerosols by quantum chemical descriptors.

Quantitative structure-property relationship (QSPR) modeling is a powerful approach for predicting environmental fate parameters of organic pollutants with their structure descriptors. This study reports QSPR models for photolysis half-lives of polycyclic aromatic hydrocarbons (PAHs) in aerosols. Quantum chemical descriptors computed with density functional theory at B3LYP/6-31G(d) level and partial least squares (PLS) analysis with optimizing procedure were used for generating QSPR models. The correlation coefficient of the optimal model was 0.993, and the fitting results showed this optimal model had high fitting precision and good predictability. The predicted photolysis half-lives by the optimal model are very close to those observed. The PLS assistant analysis indicated that PAHs with large electronic spatial extent tend to be photolyzed faster, while PAHs with high molecular total energy and small Mulliken atomic charges on the most negative carbon atom tend to be photolyzed slower in aerosols.

[Influence of NTA on accumulation and subcellular distribution of copper and zinc in corn (Zea mays)].

The differential centrifugation method was used to study the subcellular distribution of Cu and Zn in the roots, stems and leaves of corn (zea mays) growing on multi-metal contaminated soil with the addition of chelator Nitrilotriacetic Acid (NTA). The results show that the subcellular distributions of Cu and Zn have significant relationship with the ability of metal uptake and accumulation in corn. NTA could evidently promote the uptake and accumulation of Cu and Zn in corn and affect on their distribution in cell wall and vacuole. Most of Cu was bound to the cell wall fraction and secondly cytoplasm fraction and only a small quantity of Cu bound to organelle fractions. For Zn, however, most of Zn was bound to cytoplasm fraction and there was more Zn bound to organelles than Cu. Under the inducement of NTA, there were increasing Cu and Zn bound to cytoplasm fraction, which mostly came from cell wall fraction and partly came from organelle fractions.