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- 2019
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Wan, Cheng-Liang, et al.
(författare)
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基于玻璃毛细管的大气环境MeV质子微束的产生与测量 : [Production and measurement of MeV proton microbeams in atmospheric environment based on glass capillary]
- 2024
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Ingår i: Wuli xuebao. - 1000-3290. ; 73:10
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Tidskriftsartikel (refereegranskat)abstract
- 本文采用玻璃毛细管产生了大气环境中工作的2.5 MeV质子外束微束, 并对束斑直径及能量分布随玻璃毛细管与束流方向之间角度(倾角)变化进行测量. 测量结果表明, 在玻璃毛细管轴向与束流方向一致时(倾角为0°), 产生的微束中存在保持初始入射能量的直接穿透部分以及散射部分, 其中直接穿透的质子占比最大, 束斑直径也最大. 随着玻璃毛细管倾角的增大, 当其大于几何张角时, 束斑直径变小, 产生的微束全部为能量减小的散射部分, 直接穿透质子消失. 我们对质子在玻璃毛细管内传输时的内壁散射过程进行了模拟计算及离子轨迹分析, 发现大角度的散射部分决定了形成的外束微束斑外围轮廓, 而束斑中心区域由不与毛细管内壁产生任何作用的直接穿透离子构成, 其大小由玻璃毛细管出口直径以及几何容许张角决定. 采用玻璃毛细管产生的外束微束具有产生简单廉价, 微束区域定位简单的特点, 有望在辐射生物学、医学、材料等领域得到广泛应用.
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- Zhou, Guoyi, et al.
(författare)
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Climate and litter C/N ratio constrain soil organic carbon accumulation
- 2019
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Ingår i: National Science Review. - : Oxford University Press (OUP). - 2095-5138 .- 2053-714X. ; 6:4, s. 746-757
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Tidskriftsartikel (refereegranskat)abstract
- Soil organic carbon (SOC) plays critical roles in stabilizing atmospheric CO2 concentration, but the mechanistic controls on the amount and distribution of SOC on global scales are not well understood. In turn, this has hampered the ability to model global C budgets and to find measures to mitigate climate change. Here, based on the data from a large field survey campaign with 2600 plots across China's forest ecosystems and a global collection of published data from forested land, we find that a low litter carbon-to-nitrogen ratio (C/N) and high wetness index (P/PET, precipitation-to-potential-evapotranspiration ratio) are the two factors that promote SOC accumulation, with only minor contributions of litter quantity and soil texture. The field survey data demonstrated that high plant diversity decreased litter C/N and thus indirectly promoted SOC accumulation by increasing the litter quality. We conclude that any changes in plant-community composition, plant-species richness and environmental factors that can reduce the litter C/N ratio, or climatic changes that increase wetness index, may promote SOC accumulation. The study provides a guideline for modeling the carbon cycle of various ecosystem scales and formulates the principle for land-based actions for mitigating the rising atmospheric CO2 concentration.
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| 7. |
- Zhou, Xian-Jing, et al.
(författare)
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Thermo-sensitive Microgels Supported Gold Nanoparticles as Temperature-mediated Catalyst
- 2019
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Ingår i: Chinese Journal of Polymer Science. - : Springer Science and Business Media LLC. - 0256-7679 .- 1439-6203. ; 37:3, s. 235-242
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Tidskriftsartikel (refereegranskat)abstract
- Microgels with a thermo-sensitive poly(N-isopropylacrylamide) (polyNIPAm) backbone and bis-imidazolium (VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microgels were converted to nanoreactors, denoted as Au@PNI MGs, upon generation and immobilization of gold nanoparticles (Au NPs) of 5-8 nm in size into poly(NIPAm-co-VIM). The content of Au NPs in microgels could be regulated by controlling the 1,6-dibromohexane/vinylimidazole molar ratio in the quaternization reaction. The microgel-based nanoreactors were morphologically spherical and uniform in size, and presented reversible thermo-sensitive behavior with volume phase transition temperatures (VPTTs) at 39-40 degrees C. The Au@PNI MGs were used for the reduction of 4-nitrophenol, of which the catalytic activity could be modulated by temperature.
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| 8. |
- Adyari, Bob, et al.
(författare)
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Strong impact of micropollutants on prokaryotic communities at the horizontal but not vertical scales in a subtropical reservoir, China
- 2020
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 721
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Tidskriftsartikel (refereegranskat)abstract
- Micropollutants have become of great concern, because of their disrupting effects on the structure and function of microbial communities. However, little is known about the relative importance of trace micropollutants on the aquatic prokaryotic communities as compared to the traditional physico-chemical characteristics, especially at different spatial dimensions. Here, we investigated free-living (FL) and particle-associated (PA) prokaryotic communities in a subtropical water reservoir, China, across seasons at horizontal (surface water) and vertical (depth-profile) scales by using 16S rRNA gene amplicon sequencing. Our results showed that the shared variances of physico-chemicals and micropollutants explained majority of the spatial variations in prokaryotic communities, suggesting a strong joint effect of the two abiotic categories on reservoir prokaryotic communities. Micropollutants appeared to exert strong independent influence on the core sub-communities (i.e., abundant and wide-spread taxa) than on the satellite (i.e., less abundant and narrow-range taxa) counterparts. The pure effect of micropollutants on both core and satellite sub-communities from FL and PA fractions was similar to 1.5 folds greater than that of physico-chemical factors at the horizontal scale, whereas an opposite effect was observed at the vertical scale. Moreover, eight micropollutants including anti-fungal agents, antibiotics, bisphenol analogues, stimulant and UV-filter were identified as the major disrupting compounds with strong associations with core taxa of typical freshwater prokaryotes. Altogether, we concluded that the ecological disrupting effects of micropollutants on prokaryotic communities may vary along horizontal and vertical dimensions in freshwater ecosystems.
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- Alimena, Juliette, et al.
(författare)
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Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider
- 2020
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Ingår i: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 47:9
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Tidskriftsartikel (refereegranskat)abstract
- Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton-proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments-as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER-to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity 'dark showers', highlighting opportunities for expanding the LHC reach for these signals.
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| 10. |
- Angleby, Helen, et al.
(författare)
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Forensic Informativity of similar to 3000bp of Coding Sequence of Domestic Dog mtDNA
- 2014
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Ingår i: Journal of Forensic Sciences. - : Wiley. - 0022-1198 .- 1556-4029. ; 59:4, s. 898-908
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Tidskriftsartikel (refereegranskat)abstract
- The discriminatory power of the noncoding control region (CR) of domestic dog mitochondrial DNA alone is relatively low. The extent to which the discriminatory power could be increased by analyzing additional highly variable coding regions of the mitochondrial genome (mtGenome) was therefore investigated. Genetic variability across the mtGenome was evaluated by phylogenetic analysis, and the three most variable similar to 1kb coding regions identified. We then sampled 100 Swedish dogs to represent breeds in accordance with their frequency in the Swedish population. A previously published dataset of 59 dog mtGenomes collected in the United States was also analyzed. Inclusion of the three coding regions increased the exclusion capacity considerably for the Swedish sample, from 0.920 for the CR alone to 0.964 for all four regions. The number of mtDNA types among all 159 dogs increased from 41 to 72, the four most frequent CR haplotypes being resolved into 22 different haplotypes.
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