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| 2. |
- Bergman, Inger, et al.
(författare)
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The influence of sulphate deposition on the seasonal variation of peat pore water methyl Hg in a boreal mire
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:9, s. e45547-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we investigate the hypothesis that long-term sulphate (SO42-) deposition has made peatlands a larger source of methyl mercury (MeHg) to remote boreal lakes. This was done on experimental plots at a boreal, low sedge mire where the effect of long-term addition of SO42- on peat pore water MeHg concentrations was observed weekly throughout the snow-free portion of 1999. The additions of SO42- started in 1995. The seasonal mean of the pore water MeHg concentrations on the plots with 17 kg ha(-1) yr(-1) of sulphur (S) addition (1.3 +/- 0.08 ng L-1, SE; n=44) was significantly (p<0.0001) higher than the mean MeHg concentration on the plots with 3 kg ha(-1) yr(-1) of ambient S deposition (0.6 +/- 0.02 ng L-1, SE; n=44). The temporal variation in pore water MeHg concentrations during the snow free season was larger in the S-addition plots, with an amplitude of >2 ng L-1 compared to +/-0.5 ng L-1 in the ambient S deposition plots. The concentrations of pore water MeHg in the S-addition plots were positively correlated (r(2)=0.21; p=0.001) to the groundwater level, with the lowest concentrations of MeHg during the period with the lowest groundwater levels. The pore water MeHg concentrations were not correlated to total Hg, DOC concentration or pH. The results from this study indicate that the persistently higher pore water concentrations of MeHg in the S-addition plots are caused by the long-term additions of SO42- to the mire surface. Since these waters are an important source of runoff, the results support the hypothesis that SO42- deposition has increased the contribution of peatlands to MeHg in downstream aquatic systems. This would mean that the increased deposition of SO42- in acid rain has contributed to the modern increase in the MeHg burdens of remote lakes hydrologically connected to peatlands.
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| 3. |
- Majidi, Vahid, et al.
(författare)
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Improving sensitivity for CE-ICP-MS using multicapillary parallel separation
- 1999
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Ingår i: Journal of Analytical Atomic Spectrometry. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 14:12, s. 1933-1935
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Tidskriftsartikel (refereegranskat)abstract
- A multicapillary, capillary electrophoresis inductively coupled plasma mass spectrometry interface is described. This interface allows for higher sample loading to improve the overall sensitivity and analyte detection limits without sacrificing the separation efficiencies. The results obtained with this parallel system are presented for a cross flow nebulizer. A comparison of single capillary electrophoresis for both DIHEN and cross flow nebulizers is presented.
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| 4. |
- Qvarnström, Johhanna, et al.
(författare)
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Flow injection-liquid chromatography-cold vapour atomic absorption spectrometry for rapid determination of methyl- and inorganic mercury
- 2000
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Ingår i: The Analyst. - : RSC Publishing. - 0003-2654 .- 1364-5528. ; 125:6, s. 1193-1197
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Tidskriftsartikel (refereegranskat)abstract
- A previously described system for determining low concentrations of mercury species in environmental samples using flow injection high-performance liquid chromatography cold vapour atomic absorption spectrometry (FI-HPLC-CVAAS) has been further developed with respect to time of analysis, long term signal stability, memory effects, detection limits, and environmental friendliness. Methyl and inorganic mercury were determined without pre-treatment in brackish water and in digested biological certified reference materials, DOLT-2 and TORT-2. Results were compared with those obtained by gas chromatography microwave-induced plasma atomic emission spectroscopy (GC-MIP-AES) using either butylation with a Grignard reagent or ethylation with sodium tetraethylborate. With the FI-HPLC-CVAAS system, absolute detection limits are 1.7 pg and 3.4 pg for methyl and inorganic mercury, respectively. Mercury species in a sample can be determined at the 0.4 ng l−1 level within 5 min. For lower concentrations the time for analysis has to be increased.
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| 5. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 6. |
- Sun, Xian-qiang, et al.
(författare)
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Structure-based ensemble-QSAR model : a novel approach to the study of the EGFR tyrosine kinase and its inhibitors
- 2014
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Ingår i: Acta Pharmacologica Sinica. - : Springer Science and Business Media LLC. - 1671-4083 .- 1745-7254. ; 35:2, s. 301-310
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To develop a novel 3D-QSAR approach for study of the epidermal growth factor receptor tyrosine kinase (EGFR TK) and its inhibitors. Methods: One hundred thirty nine EGFR TK inhibitors were classified into 3 clusters. Ensemble docking of these inhibitors with 19 EGFR TK crystal structures was performed. Three protein structures that showed the best recognition of each cluster were selected based on the docking results. Then, a novel QSAR (ensemble-QSAR) building method was developed based on the ligand conformations determined by the corresponding protein structures. Results: Compared with the 3D-QSAR model, in which the ligand conformations were determined by a single protein structure, ensemble-QSAR exhibited higher R2 (0.87) and Q2 (0.78) values and thus appeared to be a more reliable and better predictive model. Ensemble-QSAR was also able to more accurately describe the interactions between the target and the ligands. Conclusion: The novel ensemble-QSAR model built in this study outperforms the traditional 3D-QSAR model in rationality, and provides a good example of selecting suitable protein structures for docking prediction and for building structure-based QSAR using available protein structures.
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| 7. |
- Tu, Li, et al.
(författare)
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A wide-range operating synaptic device based on organic ferroelectricity with low energy consumption
- 2018
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 8:47, s. 26549-26553
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Tidskriftsartikel (refereegranskat)abstract
- In thiswork, a wide-range operating synaptic device based on organic ferroelectricity has been demonstrated. The device possesses a simple two-terminal structure by using a ferroelectric phase-separated polymer blend as the active layer and gold/indium tin oxide (ITO) as the top/bottom electrodes, and exhibits a distinctive history-dependent resistive switching behavior at room temperature. And the device with low energy consumption (similar to 50 fJ mu m(-2) per synaptic event) can provide a reliable synaptic function of potentiation, depression and the complex memory behavior simulation of differential responses to diverse stimulations. In addition, using simulations, the accuracy of 32 x 32 pixel image recognition is improved from 76.21% to 85.06% in the classical model Cifar-10 with 1024 levels of the device, which is an important step towards the higher performance goal in image recognition based on memristive neuromorphic networks.
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| 8. |
- Tu, Li, et al.
(författare)
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Aerosol jet printed silver nanowire transparent electrode for flexible electronic application
- 2018
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Ingår i: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 123:17
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol jet printing technology enables fine feature deposition of electronic materials onto low-temperature, non-planar substrates without masks. In this work, silver nanowires (AgNWs) are proposed to be printed into transparent flexible electrodes using a Maskless Mesoscale Material Deposition Aerosol Jet VR printing system on a glass substrate. The influence of the most significant process parameters, including printing cycles, printing speed, and nozzle size, on the performance of AgNW electrodes was systematically studied. The morphologies of printed patterns were characterized by scanning electron microscopy, and the transmittance was evaluated using an ultraviolet-visible spectrophotometer. Under optimum conditions, high transparent AgNW electrodes with a sheet resistance of 57.68 X/sq and a linewidth of 50.9 mu m were obtained, which is an important step towards a higher performance goal for flexible electronic applications.
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| 9. |
- Tu, Qiang, et al.
(författare)
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Determination of mercury species by capillary zone electrophoresis-inductively coupled plasma mass spectrometry: a comparison of two spray chamber-nebulizer combinations
- 2000
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Ingår i: ANALYST. - : Royal Society of Chemistry (RSC). ; 125:4, s. 705-710
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Tidskriftsartikel (refereegranskat)abstract
- A method based on capillary zone electrophoresis (CZE) separation and inductively coupled plasma mass spectrometry (ICP-MS) detection is presented for the determination of methylmercury and inorganic mercury. The CZE conditions were optimised with respect to the flow rates for nebulizer gas and sheath solution, concentration of electrolyte and applied voltage. The performances of two different sample injection systems were compared. A standard cross-flow nebulizer with a Scott spray chamber offered a shorter analysis time, better resolution and ruggedness, while a micro-concentric nebulizer (MCN-100) with a cyclone spray chamber improved the detection limit by a factor of 11 for CH3Hg+ and a factor of 19 for Hg2+. With the MCN-100,the detection limits were 13.6 ng ml(-1) for CH3Hg+ and 6.0 ng ml(-1) for Hg2+, corresponding to absolute detection limits of 2.3 pg and 1.0 pg, respectively, for a hydrodynamic injection of 170 nl. The method was tested using three biological certified reference materials with a certified methylmercury content. The pre-treatment of biological samples involves only digestion and pH adjustment, without the need for derivatization or extraction, so that potential errors involved in these usually time-consuming steps can be avoided.
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| 10. |
- Tu, Qiang, et al.
(författare)
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Rapid determination of methylmercury in biological materials by GC-MIP-AES or GC-ICP-MS following simultaneous ultrasonic-assisted in situ ethylation and solvent extraction
- 2000
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Ingår i: JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY. - : Royal Society of Chemistry (RSC). - 0267-9477 .- 1364-5544. ; 15:12, s. 1583-8
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Tidskriftsartikel (refereegranskat)abstract
- A simple and rapid sample pre-treatment procedure was developed for the determination of methylmercury in biological materials. The procedure is based on acid leaching (5 min) of sample materials followed by simultaneous in situ derivatisation and extraction (40 min) in the presence of sodium tetraethylborate and nonane, buffered at pH 7.0, in an ultrasonic held. The nonane phase with an overall average recovery of methylmercury higher than 90% was analysed by gas chromatography (GC) coupled to microwave induced plasma atomic emission spectrometry (MIP-AES) or inductively coupled plasma mass spectrometry (ICP-MS). Detection limits (as Hg), based on three times the standard deviation of a standard solution, were 4.4 ng g(-1) for GC-MIP-AES and 2.6 ng g(-1) for GC-ICP-MS. No artefact formation of methylmercury during sample pretreatment was observed following the addition of a (201)Hg2(+) isotope standard. The method was validated by the analysis of three biological certified reference materials and applied to the determination of methylmercury in a fish sample.
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