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ABSTRACT: As many antibiotics are ionizable and may have different dissociation forms in the aquatic environment, we hypothesized that the different dissociation species have disparate photolytic pathways, products and kinetics, and adopted ciprofloxacin (CIP) as a case to test this hypothesis. Simulated sunlight experiments and matrix calculations were performed to differentiate the photolytic reactivity for each dissociation species (H4CIP3+, H3CIP2+, H2CIP+, HCIP0 and CIP-). The results prove that the five dissociation species do have dissimilar photolytic kinetics and products. H4CIP3+ mainly undergoes stepwise cleavage of the piperazine ring, while H2CIP+ mainly undergoes defluorination. For H3CIP2+, HCIP0 and CIP-, the major photolytic pathway is oxidation. By density functional theory calculation, we clarified the defluorination mechanisms for the five dissociation species at the excited triplet states: All the five species can defluorinate by reaction with hydroxide ions (OH-) to form hydroxylated products, and H2CIP+ can also undergo C-F bond cleavage to produce F- and a carbon-centered radical. This study is a first attempt to differentiate the photolytic products and mechanisms for different dissociation species of ionizable compounds. The results imply that for accurate ecological risk assessment of ionizable emerging pollutants, it is necessary to investigate the environmental photochemical behavior of all dissociation species.
Environmental Science & Technology 04/2013; · 4.80 Impact Factor
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ABSTRACT: Hydroxylated polybrominated diphenyl ethers (HO-PBDEs) pose potential ecological risks due to their endocrine disrupting effects and extensive sources. It is of great importance to know their environmental transformation for the purpose of ecological risk assessment. Photodegradation is an important transformation pathway of HO-PBDEs. As HO-PBDEs ionize in natural waters, the photochemical reactivities of both neutral and anionic HO-PBDEs need to be unveiled. In this study, six HO-PBDEs were selected as model compounds. Their direct photolysis rate constants (k(d)), quantum yields (Φ), light absorptions (A), second-order reaction rate constants with (1)O(2) (k(1O2)) and ()OH (k(OH)) at different pH were determined, as well as these parameters for the neutral and anionic HO-PBDEs. The k(d), Φ, A, k(1O2) and k(OH) for the anions are much higher than those for the neutral molecules and vary with the bromination degree. Molecular parameters computed with the density functional theory (DFT) were employed to construct structure-reactivity equations. The ether bond strength, the frontier molecular orbital energy and the charge distribution were found to be the intrinsic structural characters governing the photochemical reactivities. The half-lives range from 0.7 to 60.1h for the photodegradation including the direct photolysis and the reactions with (1)O(2) and ()OH in surface waters at 45°N latitude under the continuous solar irradiation of sunny noon on 15 July. Direct photolysis is the dominant pathway. The photochemical reactivities of other HO-PBDEs at a given pH can also be estimated based on the structure-reactivity equations, which is important for the ecological risk assessment of HO-PBDEs.
Chemosphere 07/2012; · 3.21 Impact Factor
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ABSTRACT: Our recent study first demonstrated that human bone marrow mesenchymal stem cell (hBMSC) transplantation could prevent death from fulminant hepatic failure (FHF) in pigs. To further clarify the metabolic mechanism of hBMSC transplantation in FHF, the plasma collected from FHF pigs that received transplantation of hBMSCs was examined using metabolic analysis to identify the key molecular markers that regulate recovery. The results showed that obvious metabolic disturbance occurred during FHF, whereas the hBMSC transplantation group showed less severe liver injury. The metabolic trajectory returns to its original state at week 3 following the hBMSC transplantation. In total, the concentration of 26 metabolites, including conjugated bile acids, phosphatidylcholines, lysophosphatidylcholines, fatty acids, amino acid and sphingomyelin, are significantly different between the FHF group and the hBMSC transplantation group. Moreover, the time course of changes in the metabolites corresponded with that of the biochemical and histological analyses. Real-time PCR further confirmed that the gene expression of phospholipase A1, lecithin-cholesterol acyltransferase and lysophosphatidylcholine acyltransferase 1 decreased significantly, whereas that of phospholipase A2 remained stable, which explains the decrease of the phosphatidylcholines and lysophosphatidylcholines. These novel results have revealed a metabolic mechanism for the hBMSC transplantation in FHF, which could lead to the future development of treatment strategies for stem cell therapies.
Journal of Proteome Research 05/2012; · 5.11 Impact Factor
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ABSTRACT: The Yellow River is the second largest river in China. In this study, the levels of polybrominated diphenyl ethers (PBDEs) in the modern Yellow River Delta (mYRD) were firstly reported. Twenty PBDE congeners in soil/sediment samples from mYRD were measured. The total PBDE concentrations ranged from non-detectable to 18257ngkg(-1) with a mean value of 836ngkg(-1). BDE-209 was the dominant congener, accounting for ∼86.1-99.5% of the total PBDEs. The congener profiles of PBDEs with higher abundances of BDE-153 and BDE-183 were similar to those in sediment of the Bohai Sea, indicating that they shared similar sources. The concentrations and congener patterns varied among different regions. Higher levels of PBDEs were found in the middle area (MA), and more complicated congener compositions were also observed in the MA, whereas lower levels of PBDEs were found in the modern course (MC) and the old course (OC). Much more PBDEs were detected in the top layer (TL) soil where more congeners were also held compared to lower soil layers, implying that more PBDEs were emitted into this area in recent years/decades. Organic matter controlled the PBDE distribution in the soil. Soil in this area might be a source of BDE209 for the Bohai Sea.
Chemosphere 04/2012; 88(7):791-7. · 3.21 Impact Factor
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Shaorui Hao,
Jiaojiao Xin,
Jiangshan Lian, Qing Xie,
Deying Chen,
Yongzheng Guo,
Yingfeng Lu,
Guoping Sheng,
Wei Xu,
Jianrong Huang,
Lanjuan Li
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ABSTRACT: Liver failure induced by hepatitis B virus (HBV) is a severe disease with a high mortality rate. Liver support treatment is
a powerful method for treating liver failure and is a bridge to liver transplantation. Patients with similar liver function
indices, however, have different outcomes following treatment, and no satisfying prediction parameters exist. In this study,
we used ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) to investigate plasma metabolites in groups of
acute-on-chronic liver failure patients with different prognosis. An orthogonal partial least squares (OPLS) model, with satisfactory
explanatory and predictive ability (R
2
Y=0.943, Q
2=0.913) was established using SIMCA-P+12.0. The model was based on samples collected just before the first artificial
treatment for comparable model efficacy. The concordance statistics of our model was 0.968 (95% CI [0.951, 0.985]) which is
superior to that of the MELD (the Model for End-stage Liver Diseases) score (0.737, 95% CI [0.578, 0.896]). Three groups of
markers were identified: lysophosphatidylcholine, primary fatty acid amides and conjugated bile acids. Lysophosphatidylcholine
and conjugated bile acids were protection factors for survival and primary fatty acid amides were risk factors. The cut-off
point for the predictive value of our model was greater than or equal to 0.196, at which the model showed the best discrimination
between the recovery and non-recovery groups, with a sensitivity of 95% and a specificity of 87%. This metabolomic model,
based on plasma UPLC-MS profiles, provides not only excellent discrimination and prognostic ability for HBV-induced acute-on-chronic
liver failure but also early and precise warning of possible liver transplantation.
KeywordsMetabolomics–Acute-on-chronic liver failure–Hepatitis B virus–Liver support treatment
Metabolomics 04/2012; 7(3):400-412. · 4.51 Impact Factor
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ABSTRACT: Hybrid electrical energy storage (HEES) systems, composed of multiple banks of heterogeneous electrical energy storage (EES) elements with their unique strengths and weaknesses, have been introduced to efficiently store and retrieve electrical energy while attaining performance metrics that are close to their respective best values across their constituent EES elements. This paper is the first paper to formally describe the charge allocation problem and provide a systematic solution method aiming at the maximum charge allocation efficiency, which performing proper distribution of the incoming power to selected destination banks. We introduce a generalized HEES architecture and build the corresponding electrical circuit models of the chargers and banks. We formulate a mixed integer nonlinear optimization problem, where the objective function is the global charge allocation efficiency, and the constraints are energy conservations, with careful consideration of the conversion power loss in the chargers, rate capacity effect and self-discharge of the EES elements, charge transfer losses, and so on. We present a rigorous algorithm to achieve a near-optimal global charge allocation efficiency for long-term charge allocation process (i.e., tens of hours.) Experimental results based on a photovoltaic cell array as the incoming power source and a HEES system comprised on batteries and supercapacitors demonstrate a significant gain in charge allocation efficiency for the proposed algorithm.
Hardware/Software Codesign and System Synthesis (CODES+ISSS), 2011 Proceedings of the 9th International Conference on; 11/2011
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Environmental Science & Technology 08/2011; 45(18):7945-6; author reply 7947-8. · 4.80 Impact Factor
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ABSTRACT: Highly uniform four-fold shape Ce(OH)CO<sub>3</sub> dendrites were successfully prepared in large quantities through a facile reduction hydrothermal approach. The samples were prepared from the reaction of Ce(NH<sub>4</sub>)<sub>2</sub>(NO<sub>3</sub>)<sub>6</sub> with CO(NH<sub>2</sub>)<sub>2</sub> at 160°C in a water°N<sub>2</sub>H<sub>4</sub> complex. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterise the products. The influence of the N<sub>2</sub>H<sub>4</sub> on the dendrites formation was discussed.
Micro & Nano Letters 07/2011; · 0.94 Impact Factor
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ABSTRACT: Computational approaches are crucial to risk assessment and pollution prevention of newly synthesized compounds prior to large-scale production and commercialization. Understanding the kinetics and mechanism of the tropospheric reaction of semivolatile organic compounds with ·OH is an indispensable component of risk assessment. In this study, we show that the density functional theory (DFT) can be successfully employed to probe the kinetics and mechanism of atmospheric photooxidation of polybrominated diphenyl ethers (PBDEs) by ·OH, taking 4,4'-dibromodiphenyl ether (BDE-15) as a case. The predicted products (HO-PBDEs, brominated phenols and Br(2)) and overall rate constant (k(OH)) at 298 K are consistent with the experimental results. Two pathways leading to formation of HO-PBDEs are identified: Br substitution by ·OH, and abstraction of H gem to ·OH in BDE-OH adducts by O(2). This study offers a cost-effective way for probing the atmospheric indirect photooxidation kinetics and mechanism of PBDEs.
Environmental Science & Technology 06/2011; 45(11):4839-45. · 4.80 Impact Factor
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ABSTRACT: Perfluorooctane sulfonate (PFOS) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) are two persistent environmental contaminants that are toxic to developing nervous systems, particularly via their disruption of thyroid hormone (TH) function. To investigate whether an interaction existed between PFOS and BDE-47 on TH-mediated pathways, adult female Wistar rats were exposed to 3.2 and 32 mg/kg of PFOS or BDE-47 in their diet and co-exposed to a combination of each chemical (3.2 mg/kg) from gestational day 1 to postnatal day (PND) 14. Serum and brain tissues from both male and female neonates were collected on PNDs 1, 7, and 14 to examine TH-regulated gene and protein expression. The results revealed that (1) a significant accumulation difference occurred between the two chemicals; (2) On a equimolar basis, BDE-47 and PFOS affected serum total triiodothyronine and total thyroxine differently in adults and offspring; (3) there were region-specific and exposure- and time-dependent alterations in TH concentrations and tested gene and protein expression levels; and (4) interaction for the combined chemicals was only observed for brain-derived neurotrophic factor (BDNF), which exhibited a synergistic effect on PND 1 in the cortex and an antagonistic effect on PND 14 in the hippocampus. Our results suggest a complex TH-mediated gene and protein response to BDE-47 and/or PFOS exposure that seems little related to TH homeostasis and that little combined interaction of co-exposures was observed except on BDNF. The underlying mechanisms remain uncertain but seem to involve more actions than just TH-regulated pathway.
Toxicological Sciences 03/2011; 121(2):279-91. · 4.65 Impact Factor
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ABSTRACT: Transformation products usually differ in environmental behaviors and toxicological properties from the parent contaminants, and probably cause potential risks to the environment. Toxicity evolution of a labile preservative, bronopol, upon primary aquatic degradation processes was investigated. Bronopol rapidly hydrolyzed in natural waters, and primarily produced more stable 2-bromo-2-nitroethanol (BNE) and bromonitromethane (BNM). Light enhanced degradation of the targeted compounds with water site specific photoactivity. The bond order analysis theoretically revealed that the reversible retroaldol reactions were primary degradation routes for bronopol and BNE. Judging from toxicity assays and the relative pesticide toxicity index, these degradation products (i.e., BNE and BNM), more persistent and higher toxic than the parent, probably accumulated in natural waters and resulted in higher or prolonging adverse impacts. Therefore, these transformation products should be included into the assessment of ecological risks of non-persistent and low toxic chemicals such as the preservative bronopol.
Environmental pollution (Barking, Essex: 1987) 10/2010; 159(2):609-15. · 3.43 Impact Factor
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ABSTRACT: Pattern recognition has been used extensively in medical information retrieval and data analyses. Specifically, it involves pattern classification, indexing, clustering, anomaly detection and rule detection. Among various patterns, trend is a simple yet powerful pattern that can be associated with many complex clinical symptoms. Detecting adverse clinical trend is thus an important proactive approach to critical clinical situation managements. In this paper, we propose an online trend pattern detection system, the Anaesthetic Data Analyser (ADA), as a platform to monitor trend patterns of physiological data collected during anaesthesia. ADA differentiates from current approaches by looking at trends rather than a single data value against a preset threshold. Our online trend pattern detection and trend query processing algorithms also make ADA support real time trend monitoring efficiently. Experiments on physiological data collected from patients demonstrate the efficiency and effectiveness of the ADA system and our algorithms.
Software Engineering and Data Mining (SEDM), 2010 2nd International Conference on; 07/2010
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ABSTRACT: The octanol-air partition coefficient (K(OA)) of 19 hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and 10 methoxylated polybrominated diphenyl ethers (MeO-PBDEs) were measured as a function of temperature using a gas chromatographic retention time technique. At room temperature (298.15K), log K(OA) ranged from 8.30 for monobrominated OH/MeO-PBDEs to 13.29 for hexabrominated OH/MeO-PBDEs. The internal energies of phase change from octanol to air (Delta(OA)U) for 29 OH/MeO-PBDE congeners ranged from 72 to 126 kJ mol(-1). Using partial least-squares (PLS) analysis, a statistically quantitative structure-property relationship (QSPR) model for logK(OA) of OH/MeO-PBDE congeners was developed based on the 16 fundamental quantum chemical descriptors computed by PM3 Hamiltonian, for which the Q(cum)(2) was about 0.937. The molecular weight (Mw) and energy of the lowest unoccupied molecular orbital (E(LUMO)) were found to be main factors governing the log K(OA).
Chemosphere 07/2010; 80(6):660-4. · 3.21 Impact Factor
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Chemosphere 05/2010; · 3.21 Impact Factor
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ABSTRACT: Hydroxylated polybrominated diphenyl ethers (HO-PBDEs) may disrupt thyroid hormone status because of their structural similarity to thyroid hormone. However, the molecular mechanisms of interactions with thyroid hormone receptors (TRs) are not fully understood.
We investigated the interactions between HO-PBDEs and TRbeta to identify critical structural features and physicochemical properties of HO-PBDEs related to their hormone activity, and to develop quantitative structure-activity relationship (QSAR) models for the thyroid hormone activity of HO-PBDEs.
We used the recombinant two-hybrid yeast assay to determine the hormone activities to TRbeta and molecular docking to model the ligand-receptor interaction in the binding site. Based on the mechanism of action, molecular structural descriptors were computed, selected, and employed to characterize the interactions, and finally a QSAR model was constructed. The applicability domain (AD) of the model was assessed by Williams plot.
The 18 HO-PBDEs tested exhibited significantly higher thyroid hormone activities than did PBDEs (p < 0.05). Hydrogen bonding was the characteristic interaction between HO-PBDE molecules and TRbeta, and aromaticity had a negative effect on the thyroid hormone activity of HO-PBDEs. The developed QSAR model had good robustness, predictive ability, and mechanism interpretability.
Hydrogen bonding and electrostatic interactions between HO-PBDEs and TRbeta are important factors governing thyroid hormone activities.
Environmental Health Perspectives 05/2010; 118(5):602-6. · 7.04 Impact Factor
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ABSTRACT: A facile route using simple hydrothermal reaction and sequential calcinations to synthesise three-dimensional flower-like Cd(OH)<sub>2</sub> architectures without employing templates or matrix for self-assembly is presented. X-ray diffraction (XRD) patterns of the as-synthesised samples reveal clearly that all diffraction peaks match well with the hexagonal phase of Cd(OH)<sub>2</sub>. The flower-like structures are composed of nanosheets with a thickness of about 50 nm, which is verified by the field-emission electron microscopy. Every flake is curled and thin, has a smooth surface and a large surface area.
Micro & Nano Letters 05/2010; · 0.94 Impact Factor
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ABSTRACT: Photochemical behaviour of polycyclic aromatic hydrocarbons (PAHs) is strongly dependent on the physical and chemical nature of the media in/on which they exist. To understand the media effects, the photolysis of phenanthrene (PHE) and benzo[a]pyrene (BaP) in several solvents was investigated. Distinct photolysis rate constants for PHE and BaP in the different solvents were observed. Some theoretical parameters reflecting the solvent properties were computed and employed to explain the solvent effects. Acetone competitively absorbed light with PHE and BaP, and the excited acetone molecules played different roles for the photodegradation of PHE and BaP. The photolysis rate constants of PHE and BaP in hexane, isopropanol, ethanol, methanol, acetonitrile and dichloromethane were observed to correlate with the electron-accepting potential of the solvent molecules. Absolute electronegativity of the solvents linearly correlated with the photolytic activity (log k) of the PAHs significantly. The results are important for better understanding the photodegradation mechanism of PAHs in different media.
Journal of hazardous materials 03/2010; 179(1-3):173-7. · 4.14 Impact Factor
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ABSTRACT: The ubiquity of fluoroquinolone antibiotics (FQs) in surface waters urges insights into their fate in the aqueous euphotic zone. In this study, eight FQs (ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin, enrofloxacin, gatifloxacin, and balofloxacin) were exposed to simulated sunlight, and their photodegradation was observed to follow apparent first-order kinetics. Based on the determined photolytic quantum yields, solar photodegradation half-lives for the FQs in pure water and at 45 degrees N latitude were calculated to range from 1.25 min for enrofloxacin to 58.0 min for balofloxacin, suggesting that FQs would intrinsically photodegrade fast in sunlit surface waters. However, we found freshwater and seawater constituents inhibited their photodegradation. The inhibition was further explored by a central composite design using sarafloxacin and gatifloxacin as representatives. Humic acids (HA), Fe(III), NO(3)(-), and HA-Cl(-) interaction inhibited the photodegradation, as they mainly acted as radiation filters and/or scavengers for reactive oxygen species. The photodegradation product identification and ROS scavenging experiments indicated that the FQs underwent both direct photolysis and self-sensitized photo-oxidation via *OH and (1)O(2). Piperazinyl N(4)-dealkylation was primary for N(4)-alkylated FQs, whereas decarboxylation and defluorination were comparatively important for the other FQs. These results are of importance toward the goal of assessing the persistence of FQs in surface waters.
Environmental Science and Technology 03/2010; 44(7):2400-5. · 5.23 Impact Factor
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ABSTRACT: Polybrominated diphenyl ethers (PBDEs) are potential persistent organic pollutants which have raised many concerns in recent years. Research focusing on children exposure to PBDEs is important but insufficient. The levels and patterns of PBDEs in children's plasma from Dalian, China were studied for the first time. Seventeen PBDE congeners (BDE-30, 28, 35, 37, 75, 47, 66, 100, 99, 116, 155, 154, 153, 183, 181, 190 and 209) in 29 plasma samples were measured. Median PBDE concentration was 31.61 ng g(-1) lipid. BDE-153 was the dominant congener, followed by BDE-99, 47, and 183. High abundance of BDE-183 suggested a higher Octa-BDE use in China. No significant differences were observed between males and females or among different age groups. The levels of PBDEs in children's plasma in the present study were 9-30 times higher than those in non-occupational exposure people from Guangzhou, South China and those in human milk of general adults from other cities of China, but were at the moderate levels of those in children around the world. These results indicate that children in Dalian are at a high risk of exposure to PBDEs.
Environment international 11/2009; 36(2):163-7. · 4.79 Impact Factor
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ABSTRACT: Photolysis of deca-bromodiphenyl ether (BDE-209) was investigated in tetrahydrofuran, dichloromethane, isopropanol, acetone, ethanol, methanol, acetonitrile and dimethylsulfoxide. Noticeable differences of the photolytic rates and quantum yields were found in the diverse solvents. Different to the previous deductions, hydrogen donating efficiency and electron donating efficiency of solvents were not the decisive factors for the photolytic rate in this study, which was proved by the fast photolysis of BDE-209 in CCl(4), a solvent without hydrogen and difficult to donate electrons. Besides hydrogen addition process, intermolecular polymerization might occur during the photolysis. Density functional theory (DFT) calculation was performed to understand the molecular properties of BDE-209 in different solvents. The lowest singlet vertical excitation energy (E(ex)) and the average formal charge on Br (q(Br)(+)) of BDE-209, reflecting the difficulty for the excitation of BDE-209 and for the departing of Br atom, respectively, were changed by the reaction fields formed by the different solvents. E(ex) and q(Br)(+) linearly correlated with the photolytic activity (logk). This study is helpful to better understand the photolytic behavior of BDE-209 in different media.
Chemosphere 09/2009; 76(11):1486-90. · 3.21 Impact Factor
