Search

Three-dimensional biofilm electrode reactors (3D-BERs) represent a novel technology for wastewater denitrification. Formation of mature electroactive biofilm on particle electrodes is crucial to realize successful denitrification in 3D-BERs. However, long start-up time and low electroactivity of the biofilm formed on particle electrodes limit the further application of 3D-BERs in wastewater treatment. In this work, self-assembled hybrid biofilms (SAHB) was cultivated on granular activate carbon particle electrodes of the 3D-BER by assembling nano ɑ-Fe2O3 into the biofilm. ɑ-Fe2O3 was selected due to its high affinity to bacterial outer-membrane cytochromes, an important mediator for microbial electron transfer. SAHB formed on particle electrodes were characterized and the denitrification performance of 3D-BERs was also investigated. Results indicate that nano ɑ-Fe2O3 plays positive roles in the start-up of 3D-BER, which captures more microbes into SAHB and constructs thick biofilm on particle electrodes. Special microorganisms with denitrification function related with genera of Hydrogenophaga and Opitutus are distinctively enriched in SAHB. Nano ɑ-Fe2O3 induced SAHB exhibit superior denitrification performance compared to natural biofilm. The average denitrification rate increases from 0.62 mg total nitrogen/L/h for natural biofilm to 1.73 mg total nitrogen/L/h for SAHB, mainly ascribed to accelerated nitrites reduction. Our work provides new technical solution to enhance nitrates removal in 3D-BERs and brings deep insights into application of bio-electrochemical system in wastewater treatment. Keywords: Hydrogen autotrophic denitrification, Nano ɑ-Fe2O3, Self-assembled hybrid biofilm (SAHB), Three-dimensional biofilm electrode reactors (3D-BERs)

The applications of polypropylene/carbon fiber (PP/CF) composite are hindered by the high flammability of PP substrate. This work reports a facile solvothermal method to modify CF though grafting maleic anhydride (MAH) on its surface, with the goal of enhancing the compatibility of intumescent flame retardant (IFR) with PP substrate, thus enhancing the flame-retardant and mechanical performance of the resulting PP/CF/IFR composite. The effect of maleic anhydride-g-carbon fiber (MAH-g-CF) to IFR ratio on the overall performance of the composite was assessed. The possible interactions between MAH-g-CF and IFR were characterized by dynamic thermomechanical analysis and Fourier-transform infrared spectroscopy. Results show that when 3 wt% MAH-g-CF and 22 wt% IFR were added to the PP substrate, the composite exhibited a much lower heat release rate value and smoke suppression ability. Meanwhile, the composites achieved 26.7 MPa in tensile strength and 50.6 MPa in flexural strength. We propose that MAH on MAH-g-CF acts as a compatibilizer that improves the adhesion and cross-linking between CF and IFR, thereby enhancing mechanical strength and flame-retardancy of the PP/IFR/MAH-g-CF composite.

Objective To investigate the relationship of IL ⁃ 17, IL ⁃ 10 and MMP ⁃ 12 with the vulnerability of carotid atherosclerotic plaque and cerebral infarction. Methods According to clinical stroke event 70 carotid atherosclersis patients were divided into asymptomatic carotid atherosclerosis (ACAS) group (n = 35) and acute atherosclerotic cerebral infarction (AACI) group (n = 35). The patients were also divided into vulnerable plague (VP) group (n = 38) and unvulnerable plague (UVP) group (n = 32) by color ultrasonic technique. Normal control group (n = 35) was established. The plasma levels of cytokines were tested by enzyme ⁃ linked immunosorbent assay (ELISA). Results Compared with the control group, the concentrations of IL ⁃ 17, IL ⁃ 10 and MMP ⁃ 12 in ACAS group and AACI group were significantly elevated (P = 0.000; P = 0.000), moreover, the concentrations of IL⁃17 and MMP⁃12 in AACI group were higher than those in ACAS group (P = 0.000; P = 0.002, respectively). In AACI group, the level of IL⁃10 was lower than the ACAS group and control group (P = 0.000, for all), whereas, no significant difference of IL⁃10 level was seen between ACAS group and control group (P = 0.275). In VP group, the concentrations of IL ⁃ 17 and MMP ⁃ 12 were higher than those in UVP group (P = 0.000 and 0.014, respectively). In VP group, the level of IL⁃10 was lower than that in UVP group and control group (P = 0.000, for all), but no significant difference of IL⁃10 level was seen between UVP group and control group (P = 0.742). Correlation analysis showed, the level of IL⁃17 was positively correlated with the level of MMP⁃12 (r = 0.640, P = 0.000), and was negatively correlated with the level of IL⁃10 (r = ⁃ 0.430, P = 0.000). The level of MMP ⁃ 12 was weakly negatively correlated with the level of IL ⁃ 10 (r = ⁃ 0.242, P = 0.013). Conclusion IL ⁃ 17, IL ⁃ 10 and MMP ⁃ 12 all participate the pathological process of atherosclerosis and cerebral infarction. The elevated IL⁃17 and MMP⁃12 levels and decreased IL⁃10 level may be closely correlated with the plague vulnerability. These results would be helpful to discover the vulnerability of plague in the early stage and to predict the incidence of acute ischemic stroke. DOI：10.3969/j.issn.1672⁃6731.2012.03.020

Because wear is one of the most common reasons for the failure of metals, the development of a low-cost coating with enhanced wear resistance is of great importance. In the present study, Fe–Si–Al coatings with superior and stable wear resistance were prepared by laser cladding Fe–Si–Al industrial waste onto 1045 carbon steel. The microstructure, as well as the wear mechanism of the Fe–Si–Al coatings, was investigated. The Fe–Si–Al coatings consist of a (Al, Fe, Si) solid solution phase in both columnar grain form and equiaxed grain form. The Fe–Si–Al coatings possess enhanced microhardness of 494 ± 15 HV0.3 and low mass loss of 5 × 10−5 mg·(N·m)−1. The wear resistance is ten times higher than that of the 1045 carbon steel matrix. The wear of the Fe–Si–Al coatings is mainly dominated by abrasive wear and adhesive wear. This work provides important insight into the preparation of low-cost, wear-resistant coatings, as well as stable, superior wear resistance.

Extending two-dimensional (2D) graphene nanosheets to a three-dimensional (3D) network can enhance the design of all-carbon electronic devices. Based on the great diversity of carbon atomic bonding, we have constructed four superlattice-type carbon allotrope candidates, containing sp2-bonding transport channels and sp3-bonding insulating layers, using density functional theory. It was demonstrated through systematic simulations that the ultra-thin insulating layer with only three-atom thickness can switch off the tunneling transport and isolate the electronic connection between the adjacent graphene strips, and these alternating perpendicular strips also extend the electron road from 2D to 3D. Designing electronic anisotropy originates from the mutually perpendicular π bonds and the rare partial charge density of the corresponding carriers in insulating layers. Our results indicate the possibility of producing custom-designed 3D all-carbon devices with building blocks of graphene and diamond. [ABSTRACT FROM AUTHOR]

Magnetically separable TiO-coated SrFeO electrospun nanofibers were obtained successfully by means of sol-gel, electrospinning, and coating technology, followed by heat treatment at 550-650 °C for 3 h. The average diameter of the electrospun fibers was 500-600 nm. The fibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM). The optimized calcining temperature was determined by XRD and the analysis of decolorizing efficiency of methylene blue (MB) under UV-vis irradiation. The photocatalytic activity of the TiO-coated SrFeO fibers was investigated using ultraviolet-visible absorbance by following the photooxidative decomposition of a model pollutant dye solution, MB in a photochemical reactor. In contrast to pure TiO fibers, the TiO-coated SrFeO fibers have higher absorption in 250-750 nm wavelength regions. The presence of SrFeO not only broadened the response region of visible-light, but also enhanced the absorbance for UV light. The decolorizing efficiency of MB under UV-vis irradiation was up to 98.19%, which was a little higher than that of Degussa P25 (97.68%). Furthermore, these fibers could be recollected easily with a magnet in a photocatalytic process and had effectively avoided secondary pollution of treated water. [ABSTRACT FROM AUTHOR]