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Du J.,CAS Research Center for Eco Environmental Sciences | Jing C.,CAS Research Center for Eco Environmental Sciences
Journal of Physical Chemistry C | Year: 2011

In situ detection and identification of PAHs, a group of well-known persistent organic pollutants, presents a great challenge to environmental researchers. This work developed a novel substrate based on thiol-functionalized Fe 3O 4@Ag core-shell magnetic nanoparticles for surface enhanced Raman scattering (SERS) sensing of PAHs. The surface morphology, structure, and magnetic properties of the substrate were characterized using multiple complementary techniques including transmission electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry analysis, and extended X-ray absorption fine structure spectroscopy. The high saturation magnetization at 48.35 emu g -1 enabled the complete and rapid separation of the substrate from the PAH solution. Benzene, naphthalene, anthracene, phenanthrene, fluorene, pyrene, perylene, and BaP were chosen as probe molecules. Qualitative and quantitative determination of PAHs was achieved using a portable Raman spectrometer. The SERS sensitivity was positively correlated with the hydrophobic nature of PAHs. The SERS response exhibited a linear dependence on the PAHs concentration between 1 to 50 mg/L, and the detection limit in the order 10 -5 to 10 -7 M was obtained. The SERS platform with magnetic substrate provides a new way for in situ PAH monitoring. © 2011 American Chemical Society.

Xie H.Q.,CAS Research Center for Eco Environmental Sciences
Environmental health perspectives | Year: 2013

Deficits in cognitive functioning have been reported in humans exposed to dioxins and dioxin-like compounds. Evidence suggests that dioxins induce cholinergic dysfunction mediated by hypothyroidism. However, little is known about direct effects of dioxins on the cholinergic system. We investigated the action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on acetylcholinesterase (AChE), a key enzyme in cholinergic neurotransmission. We used SK-N-SH human-derived neuronal cells to evaluate the effect of dioxin exposure on AChE. We consistently found a significant decrease in enzymatic activity of AChE in cultured neurons treated with TCDD. We also found that, unlike organophosphate pesticides that directly act on the catalytic center of AChE, the suppressive effect of dioxin was through transcriptional regulation. The addition of CH223191, an inhibitor of the aryl hydrocarbon receptor (AhR)-dependent pathway, counteracted the TCDD-induced suppression of AChE, suggesting involvement of the AhR-dependent pathway. The existence of putative dioxin-responsive element (DRE) consensus sequences in the human ACHE promoter region further supported this hypothesis. Consistent with the absence of DRE elements in mouse or rat ACHE promoter regions, suppression of AChE by TCDD did not occur in rat neuronal cells, indicating a potential species-specific effect. In SK-N-SH cells, dioxin suppressed the activity of neuronal AChE via AhR-mediated transcriptional down-regulation. This is the first study to report direct interference by dioxin with the cholinergic neurotransmission system.

Yin Y.,CAS Research Center for Eco Environmental Sciences | Liu J.,CAS Research Center for Eco Environmental Sciences | Jiang G.,CAS Research Center for Eco Environmental Sciences
ACS Nano | Year: 2012

Despite the possible occurrence of metal nanoparticles in the environment due to the discharge of engineered nanoparticles and the natural transformation of metal ions into metal nanoparticles, little is known about the transformation mechanism, fates, behaviors, and effects of these nanoparticles in the environment. Here, we show that dissolved organic matter (DOM) in environmental waters can mediate the reduction of ionic Ag and Au to their metallic nanoparticles under natural sunlight, suggesting that this process may be general for metals with high reduction potential. We demonstrated that the reduction was mediated by superoxide from photoirradiation of the phenol group in DOM, and the dissolved O 2 significantly enhanced the formation of Ag nanoparticles. These results imply that previous knowledge about O 2-induced dissolution and its effect on persistence of Ag nanoparticles should be reconsidered in a sunlit DOM-rich aqueous environment. This study can also shed light on understanding possible natural sources of Ag and Au nanoparticles in the aquatic environment, which is possibly critical in the supergene enrichment of Ag and Au. © 2012 American Chemical Society.

Liu F.,CAS Research Center for Eco Environmental Sciences | He H.,CAS Research Center for Eco Environmental Sciences
Journal of Physical Chemistry C | Year: 2010

A series of iron titanate catalysts, FeaTibO x, with different Fe-Ti molar ratios are synthesized via a facile coprecipitation method and tested for the selective catalytic reduction (SCR) of NOx with NH3. The structural properties and redox behavior of the serial catalysts are comprehensively characterized. Comparing with pristine TiO2 and Fe2O3, the coexistence of iron and titanium species is favorable to form crystallites with specific Fe-O-Ti structure, which is highly active for the NH3-SCR reaction. Fe4Ti4Ox catalyst with a Fe-Ti molar ratio of 1:1 shows the highest intrinsic activity, due to its smallest particle size, enhanced oxidative ability of Fe3+, highest mobility of lattice oxygen, and abundant acid sites. The correlation between catalytic performance and reactant adsorption capability/conformation is also studied, indicating that an appropriate method to improve the low temperature SCR activity of iron titanate catalyst is to enhance the adsorption ability of NOx as monodentate nitrate on catalyst surface. © 2010 American Chemical Society.

Zhang B.,CAS Research Center for Eco Environmental Sciences | Guo L.-H.,CAS Research Center for Eco Environmental Sciences
Biosensors and Bioelectronics | Year: 2012

A "turn-on" photoelectrochemical sensor for Hg 2+ detection based on thymine-Hg 2+-thymine interaction is presented by using a thymine-rich oligonucleotide film and a double-strand DNA intercalator, Ru(bpy) 2(dppz) 2+ (bpy=2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c]phenazine) as the photocurrent signal reporter. The presence of Hg 2+ induces the formation of a double helical DNA structure which provides binding sites for Ru(bpy) 2(dppz) 2+. The double helical structure was confirmed by circular dichroism and fluorescence measurements. Under the optimized conditions, a linear relationship between photocurrent and Hg 2+ concentration was obtained over the range of 0.1nM to 10nMHg 2+, with a detection limit of 20pM. Interference by 10 other metal ions was negligible. Analytical results of Hg 2+ spiked into tap water and lake water by the sensor were in good agreement with mass spectrometry data. With the advantages of high sensitivity and selectivity, simple sensor construction, low instrument cost and low sample volume, this method is potentially suitable for the on-site monitoring of Hg 2+ contamination. © 2012 Elsevier B.V.

Zhou W.,CAS Research Center for Eco Environmental Sciences
IEEE Geoscience and Remote Sensing Letters | Year: 2013

Digital surface models (DSMs) derived from light detection and ranging (LiDAR) data have been increasingly integrated with high-resolution multispectral satellite/aerial imagery for urban land cover classification. Fewer studies, however, have investigated the usefulness of LiDAR intensity in aid of urban land cover classification, particularly in highly developed urban settings. In this letter, we use an object-based classification approach to investigate whether a combination of LiDAR height and intensity data can accurately map urban land cover. We further compare the approach to a method that uses multispectral imagery as the primary data source, but LiDAR DSM as ancillary data to aid in classification. The study site is a suburban area in Baltimore County, MD. The LiDAR data were acquired in March 2005, from which DSM and two intensity layers (first and last returns), with 1-m spatial resolution were generated, respectively. Four classes were included: 1) buildings; 2) pavement; 3) trees and shrubs; and 4) grass. Our results indicated that the object-based approach provided flexible and effective means to integrate LiDAR height and intensity data for urban land cover classification. A combination of the LiDAR height and intensity data proved to be effective for urban land cover classification. The overall accuracy of the classification was 90.7%, and the overall Kappa statistics equaled 0.872, with the user's and producer's accuracies ranging from 86.8% to 93.6%. The accuracy of the results were far better than those using multispectral imagery alone, and comparable to using DSM data in combination with high-resolution multispectral satellite/aerial imagery. © 2004-2012 IEEE.

Pang L.,CAS Research Center for Eco Environmental Sciences | Liu J.-F.,CAS Research Center for Eco Environmental Sciences
Journal of Chromatography A | Year: 2012

A novel approach was developed for the fabrication of solid-phase microextraction (SPME) fiber by coating stainless steel fiber with a polymeric ionic liquid (PIL) through covalent bond. The stainless steel fiber was sequentially coated with a gold film by replacement reaction between Fe and Au when immerged in chloroauric acid, assembled with a monolayer of 3-(mercaptopropyl) triethoxysilane on the gold layer through the Au-S bond, and coated with a silica layer by the hydrolysis and polycondensation reaction of the surface-bonded siloxane moieties and the active silicate solution. Then, 1-vinyl-3-(3-triethoxysilylpropyl)-4,5-dihydroimidazolium chloride ionic liquid was anchored on the silica layer by covalent bond, and the PIL film was further formed by free radical copolymerization between 1-vinyl-3-(3-triethoxysilylpropyl)-4,5-dihydroimidazdium and vinyl-substituted imidazolium with azobisisobutyronitrile (AIBN) as initiator. Parameters influencing the preparation of PIL fiber were optimized, and the developed SPME fiber has a coating thickness of ~20μm with good thermal stability and long lifetime. The performance of the PIL fiber was evaluated by analysis of polycyclic aromatic hydrocarbons (PAHs) in water samples. The developed PIL fiber showed good linearity between 0.5 and 20μgl -1 with regression coefficient in the range of 0.963-0.999, detection limit ranging from 0.05 to 0.25μgl -1, and relative standard deviation of 9.2-29% (n=7). This developed PIL fiber exhibited comparable analytical performance to commercial 7μm thickness PDMS fiber in the extraction of PAHs. The spiked recoveries for three real water samples at 0.5-5μgl -1 levels were 49.6-111% for the PIL fiber and 40.8-103% for the commercial PDMS fiber. © 2012 Elsevier B.V.

Zhang C.,Tianjin Medical University | Zhang C.,CAS Research Center for Eco Environmental Sciences
Oncogene | Year: 2014

Rho-associated kinase (ROCK) has an essential role in governing cell morphology and motility, and increased ROCK activity contributes to cancer cell invasion and metastasis. Burgeoning data suggest that ROCK is also involved in the growth regulation of tumor cells. However, thus far, the molecular mechanisms responsible for ROCK-governed tumor cell growth have not been clearly elucidated. Here we showed that inhibition of ROCK kinase activity, either by a selective ROCK inhibitor Y27632 or by specific ROCK small interfering RNA (siRNA) molecules, attenuated not only motility but also the proliferation of PC3 prostate cancer cells in vitro and in vivo. Importantly, mechanistic investigation revealed that ROCK endowed cancer cells with tumorigenic capability, mainly by targeting c-Myc. ROCK could increase the transcriptional activity of c-Myc by promoting c-Myc protein stability, and ROCK inhibition reduced c-Myc-mediated expression of mRNA targets (such as HSPC111) and microRNA targets (such as miR-17-92 cluster). We provided evidence demonstrating that ROCK1 directly interacted with and phosphorylated c-Myc, resulting in stabilization of the protein and activation of its transcriptional activity. Suppression of ROCK-c-Myc downstream molecules, such as c-Myc-regulated miR-17, also impaired tumor cell growth in vitro and in vivo. In addition, c-Myc was shown to exert a positive feedback regulation on ROCK by increasing RhoA mRNA expression. Therefore, inhibition of ROCK and its stimulated signaling might prove to be a promising strategy for restraining tumor progression in prostate cancer.

Zhang S.,CAS Research Center for Eco Environmental Sciences
PloS one | Year: 2012

Ant-aphid mutualism is known to play a key role in the structure of the arthropod community in the tree canopy, but its possible ecological effects for the forest floor are unknown. We hypothesized that aphids in the canopy can increase the abundance of ants on the forest floor, thus intensifying the impacts of ants on other arthropods on the forest floor. We tested this hypothesis in a deciduous temperate forest in Beijing, China. We excluded the aphid-tending ants Lasius fuliginosus from the canopy using plots of varying sizes, and monitored the change in the abundance of ants and other arthropods on the forest floor in the treated and control plots. We also surveyed the abundance of ants and other arthropods on the forest floor to explore the relationships between ants and other arthropods in the field. Through a three-year experimental study, we found that the exclusion of ants from the canopy significantly decreased the abundance of ants on the forest floor, but increased the abundance of beetles, although the effect was only significant in the large ant-exclusion plot (80*60 m). The field survey showed that the abundance of both beetles and spiders was negatively related to the abundance of ants. These results suggest that aphids located in the tree canopy have indirect negative effects on beetles by enhancing the ant abundance on the forest floor. Considering that most of the beetles in our study are important predators, the ant-aphid mutualism can have further trophic cascading effects on the forest floor food web.

CAS Research Center for Eco Environmental Sciences | Date: 2011-11-09

Disclosed is a Ce-based composite oxide catalyst for selective catalytic reducing nitrogen oxides with ammonia, which comprises Ce oxide and at least one oxide of transition metal except Ce. The Ce-based composite oxide catalyst is prepared by a simple method which uses non-toxic and harmless raw materials, and it has the following advantages: high catalytic activity, and excellent selectivity for generating nitrogen etc. The catalyst can be applied in catalytic cleaning plant for nitrogen oxides from mobile and stationary sources.

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