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The natural organic matters (NOM) have been proved to form the hydraulically irreversible membrane fouling, which limit the application of the membrane in water treatment processes. To solve the membrane fouling caused by NOM, a novel one-step chemical cleaning method for the ceramic membrane derived from the base-activated persulfate oxidation process was developed in this study. When the SiC ceramic membranes was used to filtrate practical river water, the permeate flux dropped 65% as ΔTMP reached 30 kPa. After 2 h immersion of the fouled membrane in the cleaning solution (2 mM PMS and 8 mM NaOH), the flux recovery rate nearly reached 100%. Direct backwash of the membrane by the above cleaning solution further reduced the cleaning time to 25 mins, while achieving similar cleaning effect. Then the cleaned membranes were immersed in NaClO solution to release all the residual foulants, but the fluorescence excitation-emission matrix spectra (EEM) and total organic carbon (TOC) of the solution were found insignificant, which demonstrated the base-activated persulfate strategy had effectively removed the irreversible membrane fouling. Free radical quenching experiments were carried out and·O 2 - was identified as the dominant ROS responsible for the removal of the membrane foulants. The permeate flux and filtration efficiency of the SiC membrane were stable after 5 consecutive fouling-cleaning cycles, and the membrane structure was not damaged. In summary, the base-activated persulfate strategy is an efficient and cleaner method for SiC membrane cleaning, which is potential to be applied in practical membrane water treatment process. [Display omitted] • A novel one-step base-activated persulfate system was applied to the SiC membrane cleaning. • The cleaning process achieved full flux recovery rate in the optimized condition. • The·O 2 - was identified as the dominant ROS responsible for the removal of the membrane foulants. • This membrane cleaning strategy was long-term efficacy and no damage of the membrane structure was found. [ABSTRACT FROM AUTHOR]

The wide application of surfactants and engineered nanomaterials (ENMs) in industrial and consumer products lead to the high possibility of their co-presence in natural water environment, making it important to study the effect of surfactants on the environmental behavior and fate of ENMs. In this work, we selected an anionic sodium dodecyl sulfate (SDS) and a nonionic nonylphenol ethoxylate (NPEO, Tergitol NP-9) to study their effects on the aggregation and sedimentation of a 20 nm ZnO ENM in different water matrices. The adsorption of SDS and NP-9 by ZnO ENM were fitted with Langmuir model, and the maximum adsorption capacities were 43.73 ± 4.62 mg/g and 13.79 ± 1.09 respectively. As the surfactant concentration increased from 0 to 0.030% (m:v), SDS reduced the zeta potential of ZnO ENM from 17.56 ± 2.13 to − 27.96 ± 2.59 mV, whereas NP-9 did not affect the zeta potential. After a 24-h batch reactor experiment, SDS and NP-9 reduced 93.02% and 80.26% of the aggregate size of ZnO ENM (50 mg L − 1 ) in maximum at surfactant concentrations ≥ 0.015%. The ZnO ENM was not stable in natural aqueous matrices, mainly because of the relatively high ionic strength. However, surfactants were found to reduce the aggregation and sedimentation of ZnO ENM in six natural water matrices in different degrees. With the presence of 0.030% SDS in tap water, maximum reduction rates of aggregate size and sedimentation were recorded as 69.54% and 26.69%, respectively. The results of this study indicate that the presence of surfactants may alter the behaviors and fate of ENMs in natural water environment. [ABSTRACT FROM AUTHOR]

The high likelihood of the coexistence of surfactants and engineered nano-materials (ENMs) in aqueous environments redoubles the need to study the effects of surfactants on the behavior and transport of nano-materials. In this study, we chose anionic sodium dodecyl sulfate (SDS) and nonionic nonylphenol ethoxylate (NPEO, Tergitol NP-9) to study the effect of surfactants on the behaviors of a typical TiO 2 ENM in water environment. An adsorption isotherm and zeta potential study showed that both surfactants could be adsorbed onto the surface of nano-TiO 2 but that only SDS can significantly decrease the zeta potential of TiO 2 . For a better simulation of the dynamic natural water environment, we conducted a 24-h batch experiment to study the aggregation behaviors of nano-TiO 2 in the presence of SDS or NP-9 surfactants and recorded the sedimentation of the aggregates in solutions containing the surfactants over a 24 h-period. SDS and NP-9 both reduced the growth of the TiO 2 aggregates and retarded the aggregate sedimentation at surfactant concentrations ≥ 0.015% (w:v). The aggregation of TiO 2 was far more remarkable in six environmental water matrices from different natural origins than in Milli-Q water, mainly because of the relatively high ionic strength of the former. The introduction of surfactants, however, still retarded the aggregation and sedimentation of TiO 2 in the six environmental water matrices. SDS exerted a stronger reductive effect than NP-9. This study reveals that the presence of surfactants may increase the bioavailability and environmental risk of nanomaterial contaminants by retarding the aggregation and promoting the transport of nanomaterials in natural aqueous environments. [ABSTRACT FROM AUTHOR]

Brachycera is a clade with over 80,000 described species and originated from the Mesozoic, and its larvae employ comprehensive feeding strategies. The phylogeny of the lower Brachycera has been studied intensively over the past decades. In order to supplement the lack of genetic data in this important group, we sequenced the complete mitochondrial (mt) genome of Atylotus miser as well as the nearly complete mt genomes of another 11 orthorrhaphous flies. The mt genome of A. miser is 15,858 bp, which is typical of Diptera, with 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a 993 bp control region. The rest of the orthorrhaphous mt genomes in our study have the similar structure with A. miser . Additionally, we conducted a phylogenetic analysis of 20 mt genomes using Maximum-likelihood and Bayesian methods in order to reconstruct the evolutionary relationship of Orthorrhapha. The results show that all infraorders of Brachycera are monophyletic, and a relationship of Tabanomorpha + ((Xylophagomorpha + Stratiomyomorpha) + Muscomorpha) has been proposed. Within Xylophagomorpha, Nemestrinoidae forms the sister group of Xylophagidae. [ABSTRACT FROM AUTHOR]

Abstract: A novel biomolecule (urushiol) grafted Degussa P25 hybrid nanoparticle (UP25) was synthesized, and its structure was characterized. The UP25 hybrid nanoparticle showed high photoactivity under visible light irradiation (λ≥420nm). 4,4′-(propane-2,2-diyl)diphenol (Bisphenol A, BPA) can easily approach to UP25 surface through the hydrophobic channels between alkyl groups in urushiol. BPA degradation rate constants were 1.02×10−3 min−1 and 4.96×10−3 min−1 over P25 and UP25, respectively. Radical quenching experiments proved that the superoxide radical anion (O2 −) mediated oxidation pathways were dominant for degradation of BPA. [Copyright &y& Elsevier]

Au nanoparticles and reduced graphene oxide (r-GO) co-modified TiO 2 nanotube arrays (TNTs) were prepared by a facile and green strategy based on the electro-deposition technology for detecting H 2 O 2 , O 2 and nitrite. As-prepared Au/r-GO/TNTs electrode was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results clearly demonstrate that the successful attachment of r-GO sheets and narrow-range distribution of Au nanoparticles on TNTs. The reduced grapheme oxide sheet can help to improve the electronic conductive performance of TNTs and prevent the agglomeration of Au nanoparticles. Electrochemical studies reveal that the Au/r-GO/TNTs electrode exhibit excellent electrocatalytic performance toward the reduction of H 2 O 2 . Under the optimal experimental condition, the sensor has a quick response to H 2 O 2 at −0.3 V with a high sensitivity (1011.35 mA M −1 cm −2 ), wide linear range (0.01–22.3 mM) and low detection limit (0.006 μM). In addition, the sensor also has good stability and excellent selectivity. Moreover, the established Au/r-GO/TNTs electrode also shows high sensitivities towards dissolved O 2 and nitrite ions, which has great potential for the development of electrochemical sensors, molecular bioelectronics devices and biosensors. [ABSTRACT FROM AUTHOR]

As oxygen is one of the essential reactants in the standard SCR reactions, the ability of restoring and releasing oxygen is an important factor to determine the SCR activity of the catalyst. Ceria catalysts present an innate prospect in SCR reaction because of the facilitated redox cycles from Ce 4+ to Ce 3+ . In the present study, zirconium phosphate @ Ce 0.75 Z 0.25 O 2 (ZP/CZ) catalysts were pre-treated by O 2 , N 2 and H 2 to study the effects of lean-oxygen teatment on the structure, NH 3 /NO x adsorption and activity of catalysts. The catalysts were characterized by activity test, H 2 -TPR, XPS, DRIFT, NO x -TPD and kinetics study. The results showed that H 2 treatment led to deeply reduced catalyst surface, resulting in mainly nitrites instead of nitrates adsorbed on catalyst in NO + O 2 reaction and reduced Brønsted acidity of catalyst, which were responsible for the lowered deNO x activity of H 2 treated catalyst. N 2 treatment had only negligible influence on catalyst compared to O 2 treated catalyst. Ammonium nitrate route was consolidated as possible NH 3 -SCR reaction mechanism over ZP/CZ catalyst by kinetics study. [ABSTRACT FROM AUTHOR]

The Plecoptera (stoneflies) is a hemimetabolous order of insects, whose larvae are usually used as indicators for fresh water biomonitoring. Herein, we describe the complete mitochondrial (mt) genome of a stonefly species, namely Acroneuria hainana Wu belonging to the family Perlidae. This mt genome contains 13 PCGs, 22 tRNA-coding genes and 2 rRNA-coding genes that are conserved in most insect mt genomes, and it also has the identical gene order with the insect ancestral gene order. However, there are three special initiation codons of ND1 , ND5 and COI in PCGs: TTG, GTG and CGA, coding for L, V and R, respectively. Additionally, the 899-bp control region, with 73.30% A + T content, has two long repeated sequences which are found at the 3′-end closing to the tRNA Ile gene. Both of them can be folded into a stem-loop structure, whose adjacent upstream and downstream sequences can be also folded into stem-loop structures. It is presumed that the four special structures in series could be associated with the D-loop replication. It might be able to adjust the replication speed of two replicate directions. [ABSTRACT FROM AUTHOR]