Characterizing polycyclic aromatic hydrocarbons on road dusts in Shenzhen, China: implications for road stormwater reuse safety.

Urban road stormwater reuse is one of the most effective ways to mitigate water resource shortage. However, due to a diversity of human activities such as traffic, various toxic pollutants can be deposited on road surfaces during dry periods and washed off during wet periods, threatening stormwater reuse safety. Among these pollutants, polycyclic aromatic hydrocarbons (PAHs) have been widely found in road stormwater. This study selected twelve road sites in Shenzhen, China, and investigated PAHs deposited on urban roads and their influential factors (traffic characteristics, land use and road surface condition). The research outcomes showed that high-molecular-weight PAH species (5-6 benzene rings) had higher concentrations and variability on spatial distributions than light-molecular-weight ones (2-4 benzene rings). Additionally, more PAHs were attached to dusts with small particle sizes (< 150 µm), and among influential factors, commercial land use showed a stronger correlation with PAHs distributions, regardless of particle sizes. Furthermore, it is noteworthy that traffic volume did not have an important influence on PAH generations on roads, while the source tracking results did indicate that traffic activities were the main contributor of PAHs. This implies that other traffic characteristics such as frequent go-and-stop activities might also contribute PAHs on roads. This means that areas with frequent traffic congestions could be the "hot spot" areas of PAHs, although the traffic volume might be not high. These research outcomes can provide useful insight into effective stormwater management and ensuring their reuse safety.

GAS5 regulates viability and apoptosis in TGF-ß1-stimulated bronchial epithelial cells by regulating miR-217/HDAC4 axis.

BACKGROUND: Asthma is a serious respiratory disease that affects the physical and mental health of children. Airway epithelial apoptosis concomitantly mediated by transforming growth factor-ß1 (TGF-ß1) is a crucial component of asthma pathogenesis. LncRNA growth Arrest Specific 5 (GAS5), microRNA-217 (miR-217) and Histone deacetylase 4 (HDAC4) shown a close relationship with TGF-ß1-induced injury of airway epithelial. However, the mechanism underlying TGF-ß1-induced injury of airway epithelial in asthma still needs to be investigated. OBJECTIVE: We aimed to investigate the effect and underlying mechanism of GAS5/miR-217/HDAC4 axis in TGF-ß1-stimulated bronchial epithelial cells. METHODS: The levels of were detected by quantitative real-time polymerase chain reaction (RT-qPCR). All protein levels were determined by western blot. Cell viability and apoptosis rate were assessed by Methyl thiazolyl tetrazolium (MTT) and Flow cytometry, respectively. The targeting relationship between miR-217 and GAS5 or HDAC4 was examined with dual-luciferase reporter assay. RESULTS: TGF-ß1, GAS5, HDAC4 were up-regulated, while miR-217 was down-regulated in bronchial mucosal tissues of asthmatic children and TGF-ß1-treated BEAS-2B cells. TGF-ß1 could reduce cell viability and induce apoptosis, while these effects could be reversed by downregulation of GAS5 or HDAC4. Mechanically, GAS5 acted as a sponge for miR-217 to regulate the expression of HDAC4. Furthermore, overexpression of HDAC4 rescued the effects of GAS5 knockdown on viability and apoptosis of TGF-ß1-induced BEAS-2B cells. GAS5 knockdown induced cell viability and hampered cell apoptosis in TGF-ß1-stimulated BEAS-2B cells by regulating the miR-217/HDAC4 axis. CONCLUSIONS: The lncRNA GAS5/miR-217/HDAC4 axis played an important role in regulating TGF-ß1-induced bronchial epithelial cells injury, thus contributing to asthma.

Start-up of completely autotrophic nitrogen removal over nitrite enhanced by hydrophilic-modified carbon fiber.

In order to assess the effects of the surface hydrophilicity of supports on the biofilm formation and evaluate the performance of completely autotrophic nitrogen removal over nitrite (CANON) process in a sequencing batch biofilm reactor (SBBR), unmodified activity carbon fibers (ACFs) and ACFs hydrophilic modified by heat treatment were used as supports. CANON process was initiated in a SBBR from conventional activated sludge. An operation temperature of 32 ± 2 °C, dissolved oxygen (DO) level at 1.5 mg L⁻¹ and free ammonia (FA) concentration with 3.98-15.93 mg L⁻¹ were maintained in the SBBR. Fourier transform infrared (FT-IR) spectra and Boehm's neutralizing titration exhibited that modified ACFs had more oxygen-containing groups than unmodified ACFs. Larger biofilm growth on the modified surfaces examined by scanning electron microscopy and biofilm's total dry weight, and the biofilm on the modified surfaces were more active, compared with those on the unmodified surfaces. This study demonstrates the hydrophilic-modified ACFs have better biological affinity than unmodified ACFs. Maximal total nitrogen removal rate of 0.088 k g N m⁻³ day⁻¹ was achieved for the CANON process on day 80, indicating the CANON process was successfully started up. Apart from supports, the strategies of DO supplying and controlling FA concentration were also keys in starting up the CANON process within a shorter period.