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Characterization of a novel sound absorption material derived from waste agricultural film
No full textA comprehensive sound absorption material was developed using waste agricultural plastic film as raw material. Comparing to traditional acoustic materials such as porous materials and perforated plates, the new material exhibited excellent sound absorption capability in both low-and high-frequency ranges and had a complex structure with perforations, cavities, and an air layer. The optimal average sound absorption coefficients of the material were 0.44 and 0.53 within the frequency ranges of 200-1600 and 500-6400 Hz, respectively. Furthermore, the low-frequency absorption range of the material could be adjusted according to the actual noise absorption requirements, thus broadening its application ranges. The density of the material is 0.55 g/cm(3) while its thickness is only 1 cm. Thus, it is lighter than most conventional sound absorption materials. The compressive strength of the samples were 0.56 +/- 0.01 MPa (unmanufactured), 0.51 +/- 0.01 MPa (4 perforations) and 0.45 +/- 0.02 MPa (4 perforations and 12 cavities) respectively and, its flexural strength was 91.2 +/- 1.22 N. Interfering tests indicated that water coverage could decline the sound absorption efficiency in all frequency ranges, while sand coverage only declined the low frequency absorption, but increased the high frequency absorption effect of the material. Accordingly, it is believed that the new waste-derived material is quite suitable for application on bridges and inside tunnels during high-speed road construction, and also appropriate for using as parts of vehicles and ceilings etc. (C) 2017 Elsevier Ltd. All rights reserved
Analysis of bromophenols in various aqueous samples using solid phase extraction followed by HPLC-MS/MS
No full textA reliable and effective method for simultaneous analysis of trace amount of bromophenols (BPs) in various aqueous samples was developed in this study. The aqueous samples must be acidified after sampling to prevent the fast degradation of bromophenols. Solid-phase extraction was chosen to extract and purify the water samples. High performance liquid chromatography coupled with tandem mass spectrometry with an electrospray ionization source (HPLC-ESI-MS/MS) was used for following identification and quantification. Under the optimized condition, fourteen out of fifteen target brominated phenols were successfully separated and detected with the exception of 2,6-bromophenol (2,6-BP) whose response was too low to be quantified by the MS detector. The method was validated by spiking river water and seawater samples with different concentrations of BPs, and the qualified spiking recoveries (64-100%) and precisions (0.4-11% RSD) were obtained. The method detection limits were 0.1-13.9 ng/L and 0.1-21.9 ng/L for 0.1 L of river water and seawater samples, respectively, showing the influences from the sample matrix. The proposed method was successfully applied to the analysis of bromophenol contamination in real water samples, and six bromophenols were identified with a wide concentrations ranging from ng/L to 1.1g/L
Atmospheric occurrence and health risks of PCDD/Fs, polychlorinated biphenyls, and polychlorinated naphthalenes by air inhalation in metallurgical plants
No full textMetallurgical plants are important sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs). It is significant to evaluate the air levels and human risks of PCDD/Fs, PCBs and PCNs in metallurgical plants considering their adverse effects on human health and thousands of metallurgical plants being in operation in China. The estimated inhalation intakes of PCDD/Fs, PCBs, and PCNs together in eight iron ore sintering plants, three secondary copper plants, four secondary aluminum plants, and one secondary lead plant were 4.9-213.4, 21.4-4026.4, 28.7-630, and 11.7 fg TEQ kg(-1) day(-1), respectively, and the corresponding cancer risks were estimated to be 8.7 x 10(-7) to 3.8 x 10(-5), 5.1 x 10(-6) to 1.1 x 10(-4), 3.8 x 10(-6) to 7.1 x 10(-4), and 2.1 x 10(-6), respectively. The estimated cancer risk were higher than 100 per million people for three secondary aluminum and copper smelters among the sixteen metallurgical plants, indicating high cancer risks. Stack gas samples from metallurgical plants were also collected and analyzed for comparing their emission profiles with that of air samples. The comparison of PCDD/F, PCB and PCN profiles between air samples and stack gas samples by similarity calculation and principal component analysis suggested the influence of stack gas emissions from metallurgical plants on surrounding air. These results are helpful for understanding the exposure risk to PCDD/Fs, PCBs and PCNs in numerous metallurgical plants being operation in China. (C) 2016 Elsevier B.V. All rights reserved
Blockade of IDO-kynurenine-AhR metabolic circuitry abrogates IFN-gamma-induced immunologic dormancy of tumor-repopulating cells
No full textInteractions with the immune system may lead tumorigenic cells into dormancy. However, the underlying molecular mechanism is poorly understood. Using a 3D fibrin gel model, we show that IFN-gamma induces tumour-repopulating cells (TRCs) to enter dormancy through an indolamine 2,3-dioxygenase 1 (IDO1)-kynurenine (Kyn)-aryl hydrocarbon receptor (AhR)-p27 dependent pathway. Mechanistically, IFN-gamma signalling triggers differentiated tumour cell apoptosis via STAT1; however, when IDO1 and AhR are highly expressed as in TRCs, IFN-gamma results in IDO1/AhR-dependent p27 induction that prevents STAT1 signalling, thus suppressing the process of cell death and activating the dormancy program. Blocking the IDO/AhR metabolic circuitry not only abrogates IFN-gamma-induced dormancy but also results in enhanced repression of tumour growth by IFN-gamma-induced apoptosis of TRCs both in vitro and in vivo. These data present a previously unrecognized mechanism of inducing TRC dormancy by IFN-gamma, suggesting a potential effective cancer immunotherapeutic modality through the combination of IFN-gamma and IDO/AhR inhibitors
Combined effect of crude fat content and initial substrate concentration on batch anaerobic digestion characteristics of food waste
No full textThe mesophilic anaerobic digestion (AD) characteristics of food waste (FW) with different crude fat (CF) contents and four initial substrate concentrations (4, 6, 8, and 10 gVS/L) were investigated. The maximum methane yields of FW with CF contents of 15%, 20%, 25%, 30%, and 35% were 565.0, 580.2, 606.0, 630.2 and 573.0 mL CH4/gVS(added), respectively. An acidification trend with a drop in pH (<6.80) and increase in the volatile fatty acids/total inorganic carbon (VFAs/TIC) ratio (>0.4) were found for CF contents of 30% (10 gVS/L) and 35% (8 and 10 gVS/L). A 35% CF content in FW led to decrease in the first-order degradation constant of approximately by 40%. The modified Gompertz model showed that the lag phase (lambda) was prolonged from 0.4 to 7.1 days when the CF content in FW and initial substrate concentration were increased to 35% and 10 gVS/L. (C) 2017 Elsevier Ltd. All rights reserved
Distribution, Bioaccumulation, Trophic Transfer, and Influences of CeO2 Nanoparticles in a Constructed Aquatic Food Web
No full textIn view of the final destination of nanomaterials, the water system would be an important sink. However, the environmental behavior of nanomaterials is rather confusing due to the complexity of the real environment. In this study, a freshwater ecosystem, including water, sediment, water lettuce, water silk, Asian clams, snails, water fleas, Japanese medaka, and Yamato shrimp, was constructed to study the distribution, bioaccumulation, and potential impacts of CeO2 nanoparticles (CeO2 NPs) via long-term exposure. The results demonstrated most of the CeO2 NPs deposited in the sediment (88.7%) when the partition approached to the constant 30 days later. The bioaccumulated Ce in six tested biota species was negatively correlated with its trophic level, showing no biomagnification of CeO2 NPs through this food web. CeO2 NP exposure induced visual abnormalities in hydrophytes, including chlorophyll loss in water silk and water lettuce, ultrastructural changes in pyrenoids of water silk, and root elongation in water lettuce. The generation of hydroxyl radical (OH) and cell-wall loosening induced by CeO2 NP exposure might mediate the root growth in water lettuce. The findings on the environmental behavior of CeO2 NPs in water system have provided useful information on the risk assessment of nanomaterials
Elemental Mass Size Distribution for Characterization, Quantification and Identification of Trace Nanoparticles in Serum and Environmental Waters
No full textAccurate characterization, quantification, and identification of nanoparticles (NPs) are essential to fully understand the environmental processes and effects of NPs. Herein, the elemental mass size distribution (EMSD), which measures particle size, mass, and composition, is proposed for the direct size characterization, mass quantification, and composition identification of trace NPs in complex matrixes. A one-step method for the rapid measurement of EMSDs in 8 min was developed through the online coupling of size-exclusion chromatography (SEC) with Size inductively coupled plasma mass spectrometry (ICP-MS). The use of a mobile phase with a relatively high ionic strength (a mixture of 2% FL-70 and 2 mM Na2S2O3) ensured the complete elution of different-sized NPs from the column and, therefore, a size-independent response. After application of a correction for instrumental broadening by a method developed in this study, the size distribution of NPs by EMSD determination agreed closely with that obtained from transmission electron microscopy (TEM) analysis. Compared with TEM, EMSD allows a more rapid determination with a higher mass sensitivity (1 pg for gold and silver NPs) and comparable size discrimination (0.27 nrn). The proposed EMSD-based method was capable of identifying trace Ag2S NPs and core-shell nanocomposite Au@Ag, as well as quantitatively tracking the dissolution and size transformation of silver nanoparticles in serum and environmental waters
Geographical Differences in Dietary Exposure to Perfluoroalkyl Acids between Manufacturing and Application Regions in China
No full textEmissions of perfluoroalkyl acids (PFAAs) have increased in China over the past decade, but human exposure pathways are poorly understood. Here we analyzed 15 PFAAs in commonly consumed food items and calculated body weight normalized dietary intake rates (estimated dietary intake, EDIs) in an area with ongoing PFAA production (Hubei province; n = 121) and an urbanized coastal area (Zhejiang province; n = 106). Geographical differences in concentrations were primarily observed for perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) in animal food items and short chain PFAAs in vegetable food items. The average EDI of Sigma PFAAs for adults in Hubei (998 ng kg(-1) day(-1)) was more than 2 orders of magnitude higher than that in Zhejiang (9.03 ng kg-1 day(-1)). In Hubei province, the average EDI of PFOS for adults (87 ng kg(-1) day(-1)) was close to or exceeded advisory guidelines used in other countries indicating health risks for the population from long-term exposure. Yet, PFOS could only account for about 10% of the EDI of Sigma PFAAs in the Hubei province, which was dominated by short-chain PFAAs through consumption of vegetables. The large contribution of short-chain PFAAs to the total EDIs in manufacturing areas emphasize the need for improved exposure and hazard assessment tools of these substances
Highly Efficient Removal of Silver-Containing Nanoparticles in Waters by Aged Iron Oxide Magnetic Particles
No full textMethods for the removal of silver nanoparticles (AgNPs) and their transformation products, silver-containing nanoparticles (AgCNPs), are important, because of their potential risks to the general population and the environment. In this study, aged iron oxide magnetic particles (IOMPs) were synthesized by a simple solvothermal reaction and used for the removal of AgCNPs. The prepared IOMPs exhibit a high adsorption capacity toward AgCNPs in aqueous medium. Kinetic studies indicated that the adsorption of AgCNPs is a pseudo-second-order process. The experimental data for the adsorption of AgCNPs follow the Langmuir isotherm model, and their maximum adsorption capacities were 19.9-62.8 mg/g at pH 6.2 and 298 K. The sorption mean free energy calculated by the Dubinin Radushkevich isotherm was 4.09-5.17 kJ/mol, indicating the occurrence of physisorption, which was mainly due to the electrostatic interactions. The IOMP adsorbents maintained high removal efficiencies after four cycles of adsorption-desorption, suggesting good reusability of the developed IOMPs. Moreover, good removal efficiencies (63.3%-99.9%) and recoveries (67.1%-99.9%) were obtained from the real samples spiked with AgCNPs at levels of 10 pg/L, showing that the aged IOMPs could be used as efficient and low-cost adsorbents for the removal and recovery of AgCNPs from real waters
Improved Biocompatibility of Black Phosphorus Nanosheets by Chemical Modification
No full textBlack phosphorus nanosheets (BPs) show great potential for various applications including biomedicine, thus their potential side effects and corresponding improvement strategy deserve investigation. Here, in vitro and in vivo biological effects of BPs with and without titanium sulfonate ligand (TiL4) modification are investigated. Compared to bare BPs, BPs with TiL4 modification (TiL4@BPs) can efficiently escape from macrophages uptake, and reduce cytotoxicity and proinflammation. The corresponding mechanisms are also discussed. These findings may not only guide the applications of BPs, but also propose an efficient strategy to further improve the biocompatibility of BPs