| 1. |
- Attié, David, et al.
(författare)
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A time projection chamber with GEM-based readout
- 2017
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 856, s. 109-118
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Tidskriftsartikel (refereegranskat)abstract
- For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1. T solenoidal field and read out with three independent Gas Electron Multiplier (GEM) based readout modules, are reported. The TPC was exposed to a 6. GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented.
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| 2. |
- Chen, Yulan, et al.
(författare)
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Facile Synthesis of 3,8-Dibromo-Substituted Phenanthridine Derivatives and Their Conjugated Polymers
- 2010
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Ingår i: MACROMOLECULES. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 43:3, s. 1349-1355
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Tidskriftsartikel (refereegranskat)abstract
- We present an efficient and convenient synthesis of 3,8-dibromophenanthridine derivatives and their conjugated polymers and demonstrate that phenanthridine-containing conjugated polymers can be used as luminescent chemosensor materials. High molecular weight poly(phenanthridine-co-fluorene)s (P1, P2) and poly(phenanthridine-co-p-phenylene) (P3) were synthesized by palladium-catalyzed Suzuki-Miyaura-Schluter polycondensation (SMSPC). These phenanthridine-containing polymers are of high quantum yields in solution and show reversible optical response to protonation and deprotonation of the phenanthridine rings.
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| 3. |
- Kang, Shichang, et al.
(författare)
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Linking atmospheric pollution to cryospheric change in the Third Pole region : current progress and future prospects
- 2019
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Ingår i: National Science Review. - : Oxford University Press (OUP). - 2095-5138 .- 2053-714X. ; 6:4, s. 796-809
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Forskningsöversikt (refereegranskat)abstract
- The Tibetan Plateau and its surroundings are known as the Third Pole (TP). This region is noted for its high rates of glacier melt and the associated hydrological shifts that affect water supplies in Asia. Atmospheric pollutants contribute to climatic and cryospheric changes through their effects on solar radiation and the albedos of snow and ice surfaces; moreover, the behavior and fates within the cryosphere and environmental impacts of environmental pollutants are topics of increasing concern. In this review, we introduce a coordinated monitoring and research framework and network to link atmospheric pollution and cryospheric changes (APCC) within the TP region. We then provide an up-to-date summary of progress and achievements related to the APCC research framework, including aspects of atmospheric pollution's composition and concentration, spatial and temporal variations, trans-boundary transport pathways and mechanisms, and effects on the warming of atmosphere and changing in Indian monsoon, as well as melting of glacier and snow cover. We highlight that exogenous air pollutants can enter into the TP's environments and cause great impacts on regional climatic and environmental changes. At last, we propose future research priorities and map out an extended program at the global scale. The ongoing monitoring activities and research facilitate comprehensive studies of atmosphere-cryosphere interactions, represent one of China's key research expeditions to the TP and the polar regions and contribute to the global perspective of earth system science.
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| 4. |
- Li, Jing, et al.
(författare)
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Porous Metallosalen Hypercrosslinked Ionic Polymers for Cooperative CO2 Cycloaddition Conversion
- 2020
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 59:2, s. 676-684
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Tidskriftsartikel (refereegranskat)abstract
- Metallosalen-based porous ionic polymers have the potential to combine the merits of homogeneous organometallics and heterogeneous porous ionic catalysts in carbon dioxide (CO2) cycloaddition conversion. Herein, a series of porous metallosalen hypercrosslinked ionic polymers (M-HIPs) were synthesized through a simple method. The M-HIPs with high metal and Br anion concentrations were evaluated by catalyzing CO2 cycloaddition with epoxides. Because of the cooperative effect between Br anions and metal active species in the porous channel, M-HIPs exhibited a high CO2 catalytic performance even under ambient conditions. Among the M-HIPs (M = Co, Al, Zn), Co-HIP showed the best catalytic performance for various epoxides and was stable after five runs. Density functional theory calculations support the fact that Co-HIP had the lowest energy barrier, which agreed with the experimental results.
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| 5. |
- Tian, Liting, et al.
(författare)
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Lead concentration in plasma as a biomarker of exposure and risk, and modification of toxicity by delta-aminolevulinic acid dehydratase gene polymorphism
- 2013
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Ingår i: Toxicology Letters. - : Elsevier BV. - 1879-3169 .- 0378-4274. ; 221:2, s. 102-109
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Tidskriftsartikel (refereegranskat)abstract
- Blood lead concentration (B-Pb), the main biomarker of lead exposure and risk, is curvi-linearily related to exposure. We assessed plasma lead (P-Pb) as a marker for both lead exposure and toxic effects. We examined claims that delta-aminolevulinic acid dehydratase genotype (ALAD) can modify lead toxicity. In 290 lead-exposed and 91 unexposed Chinese workers, we determined P-Pb, B-Pb, urinary lead (U-Pb), AMD polymorphism (rs1800435, ALAD112; TaqMan assay), and also toxic effects on heme synthesis (blood zinc protoporphyrin and hemoglobin, urinary delta-aminolevulic acid), on the kidneys (urinary albumin, beta(2)microglobulin and N-acetyl-beta-D-glucosaminidase) and on the peripheral nervous system (sensory and motor conduction velocities). In exposed workers, median P-Pb was 4.10 (range 0.35-27) mu g/L, B-Pb 401 (110-950) mu g/L, and U-Pb 188 (22-590) mu g/g creatinine. P-Pb had a higher ratio between exposed and unexposed workers (median 39, range 18-110) than B-Pb (19, 15-36; p<0.001) and U-Pb (28, 15-36; p<0.001). All three biomarkers were associated with all toxic effects (P-Pb: r(s)= -0.10 to 0.79; B-Pb: r(s) = -0.08 to 0.75; all p <0.05). In the exposed workers, B-Pb and U-Pb were significantly higher (p = 0.04) in AIAD2 carriers (7% in the exposed population) than in ALAD1 homozygotes. P-Pb values were similar; ALAD1 homozygotes suffered higher kidney toxicity at the same P-Pb. Conclusions: (i) P-Pb has advantages over B-Pb as a biomarker of high Pb exposure, but it was not significantly better as an index of risk of toxicity. (ii) The ALAD genotype modifies toxicokinetics and toxicodynamics. (C) 2013 Elsevier Ireland Ltd. All rights reserved.
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| 6. |
- Zhao, Wei, et al.
(författare)
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Weak Crossability Barrier but Strong Juvenile Selection Supports Ecological Speciation of the Hybrid Pine Pinus Densata on the Tibetan Plateau
- 2014
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Ingår i: Evolution. - : John Wiley & Sons. - 0014-3820 .- 1558-5646. ; 68:11, s. 3120-3133
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Tidskriftsartikel (refereegranskat)abstract
- Determining how a new hybrid lineage can achieve reproductive isolation is a key to understanding the process and mechanisms of homoploid hybrid speciation. Here, we evaluated the degree and nature of reproductive isolation between the ecologically successful hybrid species Pinus densata and its parental species P. tabuliformis and P. yunnanensis. We performed interspecific crosses among the three species to assess their crossability. We then conducted reciprocal transplantation experiments to evaluate their fitness differentiation, and to examine how natural populations representing different directions of introgression differ in adaptation. The crossing experiments revealed weak genetic barriers among the species. The transplantation trials showed manifest evidence of local adaptation as the three species all performed best in their native habitats. Pinus densata populations from the western edge of its distribution have evolved a strong local adaptation to the specific habitat in that range; populations representing different directions of introgressants with the two parental species all showed fitness disadvantages in this P. densata habitat. These observations illustrate that premating isolation through selection against immigrants from other habitat types or postzygotic isolation through selection against backcrosses between the three species is strong. Thus, ecological selection in combination with endogenous components and geographic isolation has likely played a significant role in the speciation of P. densata.
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