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This study aims to develop three-dimension reduced graphene oxide aerogel supported nano zero-valent iron (rGOA-nZVI) by hydrothermal and liquid phase reduction approach and applies it to the removal of two typical dyes, methylene blue (MB) and methyl orange (MO) from aqueous solutions. The obtained magnetic rGOA-nZVI composites were characterized by scanning electron microscopy (SEM), atomic force microscopy, Brunauer-Emmett-Teller, X-ray diffraction and Fourier transform infrared spectroscopy, and its removal efficiencies for MB and MO from aqueous solutions were evaluated. The removal processes of MB and MO could be completed within 30 min, which were well described by the pseudo-second order kinetic model. The rGOA-nZVI nanocomposites exhibited remarkable performance for the removal of MB (the maximum adsorption amount, qmax = 3918 mg/g) and MO (qmax = 667 mg/g) in a wide pH range (pH 1.0-10.0). Furthermore, rGOA-nZVI is stable and recyclable with high dye removal efficiencies (> 90%) after five cycles. The removal mechanisms were demonstrated with SEM and XRD analyses before and after MB and MO removal. This study showed that rGOA acts as an excellent carrier for nZVI, and the rGOA-nZVI nanocomposites are efficient materials for the advanced treatment of dye wastewater over a wide pH range. [ABSTRACT FROM AUTHOR]

Background ‒ The aim of this study was to investigate the circ_0004370 expression in EC, its effects on cell proliferation, apoptosis, migration, invasion, and epithelial– mesenchymal transition (EMT) process, and the underlying regulatory mechanisms in EC. Methods ‒ The protein levels of COL1A1 and EMT-related proteins were detected by western blot. The role of circ_0004370 on cell viability, proliferation, and apoptosis was analyzed by Cell Counting Kit-8 (CCK-8) assay, colony formation assay, and flow cytometry, respectively. The transwell assay was used to examine cell migration and invasion. The binding sites between miR-1301-3p and circ_ 0004370 or COL1A1 were predicted by starbase software and confirmed by dual-luciferase reporter assay and RNA pull-down assay. Results ‒ We discovered that circ_0004370 was remarkably upregulated in EC tissues and cells. Knockdown of circ_0004370 inhibited cell proliferation, migration as well as invasion, and promoted apoptosis in vitro, while its effect was rescued by miR-1301-3p inhibition. And circ_0004370 mediated the EMT process in EC cells. Moreover, we explored its regulatory mechanism and found that circ_0004370 directly bound to miR-1301-3p and COL1A1 was verified as a target of miR-1301-3p. COL1A1 was highly expressed in EC cells and upregulation of COL1A1 reversed the effects of miR-1301-3p on cell proliferation, migration, invasion, and apoptosis. In addition, silencing of circ_0004370 reduced tumor volumes and weights in vivo. We showed that circ_0004370/miR-1301-3p/COL1A1 axis played the critical role in EC to regulate the cell activities. Conclusion ‒ Circ_0004370 promotes EC proliferation, migration and invasion, and EMT process and suppresses apoptosis by regulating the miR-1301-3p/COL1A1 axis, indicating that circ_0004370 may be used as a potential therapeutic target for EC. [ABSTRACT FROM AUTHOR]

Micro-/nanoscale patterns are popular in many applications, and several techniques to transfer multiscale patterns have been developed. Ultraviolet nanoimprint lithography (UV-NIL) is the most promising method to quickly produce complex structures, and there is a need to understand the resist-flowing and cavity-filling processes because partial cavity filling may cause defects. One crucial element of a stamp is the layout of the multiscale cavities. They can induce some difficulties during the filling process. Five different stamps with various micro-/nanoscale features (one nano feature, one micro feature, one nano feature, and one micro feature, two nano features and one micro feature) were employed in this simulation study. The imprint results show that the neighbouring effect has major issues in the microscale cavity filling and minor issues in the nanoscale. The layout of complex cavities results in poor filling proportions, and longer imprint times and a symmetrical layout were needed to improve the imprint quality. The contact pressure between the stamp and the resist generally declined when the location approached the centre from both sides of the stamp. The overall physical performance of neighbouring micro-/nanoscale cavities was obtained, and this is essential for further understanding and improvements in the UV-NIL process. [ABSTRACT FROM AUTHOR]

Pattern density is an important factor in UV nanoimprint stamp design. Various pattern densities may affect the thickness of the residual layer and its uniformity. This work investigated the effect of pattern density as well as other stamp parameters, including stamp material, stamp thickness and cavity height, on residual layer thickness (RLT), contact pressure, and imprint quality. Two kinds of stamps were designed for simulation, one with detached uniform lines and the other with adjacent non-uniform lines. Results show that areas near the edges of the imprint field in all stamps are the first to achieve high contact pressure. The study observed that long imprint time enables a reduction of RLT after a stable period, particularly obvious with high density. For a long-term imprint of patterns with various densities, flowing behaviour of the residual resist was revealed. These conclusions are beneficial for making guidelines for stamp design in UV nanoimprint lithography. [ABSTRACT FROM AUTHOR]

High aspect ratio three-dimensional micro- and nanopatterns have important applications in diverse fields. However, fabricating these structures by a nanoimprinting method invites problems like collapse, dislocation, and defects. Finite-element analysis (FEA) is a good approach to help understand the filling process and stress distribution. The FEA method was employed to simulate the nanoimprinting process using positive and negative molds with aspect ratios of 1:1, 3:1, 5:1, and 7:1. During the filling process, the resist adjacent to boundaries has the maximum displacement. The corners of contact areas between the protruding part of the mold and the resist has the maximum Von Mises stress. For both positive and negative molds, the maximum stress in the mold increases with aspect ratio. However, filling up negative molds is more difficult than positive ones. With the same aspect ratio, the maximum stress in a negative mold is approximately twice as large as that in a positive one. [ABSTRACT FROM AUTHOR]

The combined technology of electrokinetic (EK)-assisted bioremediation was used on field soil from a Beijing Coking Plant in China to assess its feasibility in remediating field soils. Total polycyclic aromatic hydrocarbon (PAH) concentration in the soil was 91.4mg/kg, with a high level of high-molecular-weight PAHs. During 200 days of EK-assisted bioremediation, neutral soil pH was maintained by periodically changing the direction of the electronic field. Electrical conductivity of the soil in the EK cell was higher than that in the control soil. Meanwhile, ammonium and phosphate could be effectively injected into the soil by the electric field. Degradation rates of all 16 U.S. Environmental Protection Agency (EPA) priority PAHs at different sampling positions in the EK cell were twice as high as those in the control soil. The number of PAH degraders in the EK cell was enhanced compared to those in the control at the end of the experiment. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) results indicated that the soils sampled near the electrodes in the EK cell showed relatively greater biodiversity compared to those in the control system. Hence, the present study provides a promising bioremediation technology for remediation of soils contaminated by PAHs. [ABSTRACT FROM AUTHOR]

The sorption of chloramphenicol on four types of sediment and the effect of coexistence Cu(II) on the sorption were studied. Sorption isotherms and thermodynamic analysis were employed to dispose the experimental sorption data. Experimental results showed that organic matter was the dominant parameter and the coexistence of heavy metal Cu(II) could promote the sorption of chloramphenicol on four tested sediments. The adsorption parameter analysis showed sorption of chloramphenicol on the sediment was not pure distributional effects, not a strong interaction between molecule and surface, but other weak interactions. Thermodynamic parameters values such as ▵ G, ▵ H and ▵ S were all below zero, which indicated that the sorption was a spontaneous and exothermal process. [ABSTRACT FROM AUTHOR]

Bioturbation by the burrowing crab Helice tiensinensis was investigated to determine its impact on polycyclic aromatic hydrocarbon (PAH)-contaminated estuarine sediments. The concentrations of 16 U.S. Environmental Protection Agency (U.S. EPA) priority PAHs in sediment and pore water from a crab bed (including surface and burrow samples) and a control area, as well as in crabs, were measured. The total concentration of the 16 U.S. EPA priority PAHs in surface sediment of the crab bed (average 2,772 ng/g dry weight) was significantly higher than in the control area (1,173 ng/g dry weight). In the crab bed, the total concentration of PAHs in burrow sediment (1,239 ng/g dry weight) was lower than in surface sediment, and a similar trend was found for most of the individual PAHs, except for indeno[1,2,3-cd]pyrene, and benzo[ghi]perylene. The enhanced PAH desorption in the burrow, which could be attributed to the increase in dissolved organic matter in pore water as well as the mechanical mixing by the crab, is expected to increase PAH flux to the sea. In addition to increased flushing to the sea, incorporation of PAHs in crab biomass and metabolism of PAHs by the crab, stimulated microbial degradation, was proposed as an ignorable factor that lowered the PAH concentration in burrow sediment, because crab bioturbation increases the abundance and activity of microorganisms through several means. Log KOW and log KOC correlated well for individual PAHs in sediment in the control area, although this correlation was poor for sediments in the crab bed. The log biota-sediment accumulation factor (BSAF) of PAHs exhibited a negative relationship with log KOW, suggesting that the bioaccumulation of sorbed PAHs was controlled primarily by their bioavailability. Environ. Toxicol. Chem. 2010;29:1248–1255. © 2010 SETAC [ABSTRACT FROM AUTHOR]

Perchlorate is a potent thyroid hormone–disrupting compound. Drinking water is one of the major sources of human exposure to perchlorate. Little is known about the occurrence of perchlorate in waters from China. In this study, water samples ( n = 300) collected from 15 locations in 13 provinces and municipalities were analyzed for the presence of perchlorate. In addition, other inorganic anions that commonly occur in water—iodide, bromide, and nitrate—and the disinfection byproducts, bromate, chlorate, and chlorite were determined by high-performance liquid chromatography interfaced with tandem mass spectrometry. Perchlorate was detected in 86% of the samples analyzed, at concentrations ranging from <0.02 to 54.4 μg l−1 (mean ± SD 2.20 ± 6.39 μg l−1; median 0.62 μg l−1). Mean concentrations of perchlorate in tap water, groundwater, surface waters, and bottled water were 2.46, 3.04, 2.82, and 0.22 μg l−1, respectively. Significant positive correlations were found between the concentrations of perchlorate and nitrate, perchlorate and chlorate, bromide and iodide, and nitrate and iodide. [ABSTRACT FROM AUTHOR]

Nonylphenol polyethoxylates (NPnEO) and nonylphenol (NP) have drawn much environmental concern because of their weak estrogenic activities. The present study focused on the spatial distribution of NPnEO and NP in surface sediments and their corresponding porewaters along Lanzhou Reach of Yellow River, China. Long EO chain NPnEO analogs with n > 2 were not measurable in most sediment and porewater samples, so only NP, nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) were discussed in this study. Concentrations of NP, NP1EO, and NP2EO in the sediments ranged from 61.3 to 113.9, 31.1 to 55.9, and 47.9 to 74.1 ng/g dry weight, respectively. A significant correlation ( R 2 = 0.56, p < 0.01) was observed between NP levels and organic carbon content of the sediments, whereas no correlation was found for the more hydrophilic NP1EO and NP2EO. The concentrations of NP, NP1EO, and NP2EO in the porewaters ranged from 0.35 to 1.95, 0.06 to 0.63, and 0.08 to 0.38 μg/L. The mean in situ log K oc values ( n = 13, S1 excluded) of NP, NP1EO, and NP2EO were 4.48, 4.94, and 5.06, respectively, which were lower than those measured in batch adsorption experiments. [ABSTRACT FROM AUTHOR]

The crack-free silica monolith with macropores and mesopores has successfully been achieved in the presence of citric acid as nonsurfactant via sol-gel reactions of tetramethoxysilane (TMOS). Citric acid was removed by calcination to afford monolithic bodies with high specific surface area of 648 m2/g, pore volume of 0.9 cm3/g. Poly (ethyl glycol) has been used together with citric acid to control the particle aggregation and internal structure. Macropores in the micrometer range originate from the spinodal phase separation and gelation kinetics. Textural mesopores in the 2–8 nm range are controlled through adding citric acid and postsynthesis treatment in ammonia solution. By employing the glycerol as drying control chemical additives (DCCA), cracks of the materials can be successfully avoided. [ABSTRACT FROM AUTHOR]

Desorption of pyrene from three different soils was studied using a semipermeable membrane device (SPMD)-assisted method to develop a new approach to predict bioavailability of hydrophobic organic compounds (HOCs) in soils. The results showed that pyrene desorption increased with reduction of soil organic matter content and elevation of pyrene concentration in unaged soils, and the 50-d desorption percentage was 52.2 ± 3.6%, 76.3 ± 1.5%, and 99.4 ± 3.3% for soils 1, 2, and 3, respectively, at an initial pyrene concentration of 10 mg/kg and 73.6 ± 4.9%, 94.1 ± 4.1%, and 98.3 ± 4.9%, respectively, at an initial pyrene concentration of 100 mg/kg. Aging led to a reduction in SPMD-assisted desorption because of movement of pyrene molecules from easy-desorbing to difficult-desorbing sites. The pyrene 50-d desorption percentage from 180-d-aged soils reduced to 5.8 ± 0.6%, 18.8 ± 0.9%, and 34.2 ± 3.1% in soils 1, 2, and 3, respectively, at an initial pyrene concentration of 10 mg/kg and 43.9 ± 2.9%, 54.3 ± 4.7%, and 86.3 ± 3.5%, respectively, at an initial pyrene concentration of 100 mg/kg. Dry and wet conditions during aging had different effects on aging-derived reduction of pyrene desorption, which was found, to our knowledge for the first time, to depend on pollutant concentration. The water to soil ratio during desorption had a significant effect on SPMD-assisted desorption dynamics. When this ratio changed from 10:1 to 1:1, desorption dynamics became more linear and slower, because when the ratio was low, the SPMD could not contact with soil particles well and the diffusion of pyrene from pore water into the SPMD might become the limiting step for SPMD accumulation of pyrene from soils. Good correlations were found between SPMD-assisted desorption and the biota-soil accumulation factor for both unaged and aged soils. The SPMD-assisted desorption is considered to be a reliable approach to predict the bioavailability of HOCs in soils. [ABSTRACT FROM AUTHOR]

The decomposition of hexachlorobenzene (HCB) has been investigated over ultrafine Ca–Fe composite oxide catalyst (Ca/Fe atomic ratio was 3.4), CaO and α-Fe2O3 by using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Adsorption experiments on the surface of oxides monitored by in situ DRIFTS showed that partial oxidation products, i.e., phenolate and acetate species were formed on the surface of Ca–Fe composite oxide. The further studies indicated that Ca–Fe composite oxide catalyst was easier to induce the rupture of C–Cl bond and C–C bond of aromatic rings. The best catalytic activity of Ca–Fe composite oxide may be related to the acidity, which was determined by NH3–TPD. The products after reaction have been analyzed by XRD and chloride selective electrode. Ca–Fe composite oxide exhibited the highest extent of mineralization for organic chlorine among the different oxides tested. The combined results of current and previous experiments demonstrated that two competitive reactions took place during the decomposition process of HCB: (1) hydrodechlorination resulting in the formation of lower chlorinated benzenes and (2) oxidation of aromatic rings leading to the rupture of aromaticity and the formation of oxidation products. The latter is the major process in the coexisted competitive reaction. A possible decomposition pathway was discussed. [ABSTRACT FROM AUTHOR]

We describe high-efficiency gratings illuminated by incident lights in the C + L bands as the (de)multiplexers for dense wavelength division multiplexing (DWDM) application. This grating is fabricated in fused silica and replicate in polydimethylsiloxane (PDMS) and polyethylene terephthalate glycol (PETG) with the technology of nanoimprint. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1504–1507, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21719 [ABSTRACT FROM AUTHOR]

Focused ion beam (FIB) was employed to fabricate nanoimprint lithography stamps. Complex micro/nanopatterns were fabricated in the stamp, including curved nanograting structures. These micro/nanostructures were then replicated to SU-8 2000.1 resist, with an imprint temperature of 95 °C, which is lower than for conventional imprint polymers. Atomic force microscopy was used to characterize the surface profiles of stamp and replica’s and the replication fidelity as well. The results show that nanoimprint with the FIB fabricated stamp can successfully replicate complex micro/nanostructures under low temperature in SU-8. [ABSTRACT FROM AUTHOR]