| 1. |
- Abramsson, Mia L, et al.
(författare)
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Charge engineering reveals the roles of ionizable side chains in electrospray ionization mass spectrometry
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The role of ionizable side chains in the electrospray ionization mass spectrometry of intact proteins remains hotly debated but has not been conclusively addressed because multiple chargeable sites are present in virtually all proteins. Using engineered soluble proteins, we show that ionizable side chains are completely dispensable for charging under native conditions, but if present, they are preferential protonation sites. The absence of ionizable side chains results in identical charge state distributions under native-like and denaturing conditions, whilst co-existing conformers can be distinguished using ion mobility separation. An excess of ionizable side chains, on the other hand, effectively modulates protein ion stability. We conclude that the sum of charges is governed solely by Coulombic terms, while their locations affect the stability of the protein in the gas phase.
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| 2. |
- Abramsson, Mia L., et al.
(författare)
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Charge Engineering Reveals the Roles of Ionizable Side Chains in Electrospray Ionization Mass Spectrometry
- 2021
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Ingår i: JACS Au. - : American Chemical Society (ACS). - 2691-3704. ; 1:12, s. 2385-2393
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Tidskriftsartikel (refereegranskat)abstract
- In solution, the charge of a protein is intricately linked to its stability, but electrospray ionization distorts this connection, potentially limiting the ability of native mass spectrometry to inform about protein structure and dynamics. How the behavior of intact proteins in the gas phase depends on the presence and distribution of ionizable surface residues has been difficult to answer because multiple chargeable sites are present in virtually all proteins. Turning to protein engineering, we show that ionizable side chains are completely dispensable for charging under native conditions, but if present, they are preferential protonation sites. The absence of ionizable side chains results in identical charge state distributions under native-like and denaturing conditions, while coexisting conformers can be distinguished using ion mobility separation. An excess of ionizable side chains, on the other hand, effectively modulates protein ion stability. In fact, moving a single ionizable group can dramatically alter the gas-phase conformation of a protein ion. We conclude that although the sum of the charges is governed solely by Coulombic terms, their locations affect the stability of the protein in the gas phase.
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| 3. |
- Bian, Guodong, et al.
(författare)
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Detection and attribution of flood responses to precipitation change and urbanization : A case study in Qinhuai River Basin, Southeast China
- 2020
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Ingår i: Hydrology Research. - : IWA Publishing. - 1998-9563 .- 0029-1277 .- 2224-7955. ; 51:2, s. 351-365
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Tidskriftsartikel (refereegranskat)abstract
- Both flood magnitude and frequency might change under the changing environment. In this study, a procedure combining statistical methods, flood frequency analysis and attribution analysis was proposed to investigate the response of floods to urbanization and precipitation change in the Qinhuai River Basin, an urbanized basin located in Southeast China, over the period from 1986 to 2013. The Mann–Kendall test was employed to detect the gradual trend of the annual maximum streamflow and the peaks over threshold series. The frequency analysis was applied to estimate the changes in the magnitude and frequency of floods between the baseline period (1986–2001) and urbanization period (2002–2013). An attribution analysis was proposed to separate the effects of precipitation change and urbanization on flood sizes between the two periods. Results showed that: (1) there are significant increasing trends in medium and small flood series according to the Mann–Kendall test; (2) the mean and threshold values of flood series in the urbanization period were larger than those in the baseline period, while the standard deviation, coefficient of variation and coefficient of skewness of flood series were both higher during the baseline period than those during the urbanization period; (3) the flood magnitude was higher during the urbanization period than that during the baseline period at the same return period. The relative changes in magnitude were larger for small floods than for big floods from the baseline period to the urbanization period; (4) the contributions of urbanization on floods appeared to amplify with the decreasing return period, while the effects of precipitation diminish. The procedure presented in this study could be useful to detect the changes of floods in the changing environment and conduct the attribution analysis of flood series. The findings of this study are beneficial to further understanding interactions between flood behavior and the drivers, thereby improving flood management in urbanized basins.
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| 4. |
- Gan, Mingming, et al.
(författare)
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A ray tracing algorithm for intelligent transport systems in tunnels
- 2014
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- It is well-known that the radio wave propagation mechanisms inside a tunnel are different from the typical outdoor and indoor situations. Since the tunnels represent a significant type of vehicular environments, understanding the channel characteristics for the in-tunnel scenario is crucial for intelligent transport systems design. A widely used tool for simulating channel characteristics for outdoor and indoor scenarios is a deterministic propagation prediction tool, known as ray tracing (RT). However, RT applied for tunnel scenarios has not been studied adequately. In this paper, we first evaluate the real-world in-tunnel vehicle-to-vehicle radio channel measurements on the basis of time-varying power delay profile analysis. Secondly we introduce a RT tool that includes influence of the moving objects, to predict wave propagation mechanisms in the tunnel. In order to reduce computational complexity of RT, we suggest to combine an approximate algorithm for the higher-order reflection components with conventional RT and use a novel subdivision algorithm for modeling the diffuse scattering. Combining the higher-order reflection algorithm with conventional RT allows us to obtain more accurate delay spread results. The numerical simulations show that contribution of both the higher-order reflection and the diffuse components are equally important for the in-tunnel scenarios.
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| 5. |
- Jin, Cenqin, et al.
(författare)
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High-Speed Long-Haul Multi-Channel Nonlinear Optical Communication Systems Influenced by Equalization Enhanced Phase Noise
- 2022
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Ingår i: 2022 IEEE 14Th International Conference On Advanced Infocomm Technology (ICAIT 2022). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 103-106
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Konferensbidrag (refereegranskat)abstract
- In this work, the performance of high-speed long-haul nonlinear Nyquist-spaced multi-channel coherent optical fiber communication systems utilizing electronic dispersion compensation and digital nonlinearity compensation is explored taking into consideration the enhanced equalization phase noise. The analytical model has also been developed to estimate the system performance under different transmission scenarios.
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| 6. |
- Wang, Ling-Zhi, et al.
(författare)
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Sphagnumspore banks in two montane peatlands at different elevations
- 2020
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Ingår i: Wetlands Ecology and Management. - : SPRINGER. - 0923-4861 .- 1572-9834. ; 28:5, s. 825-835
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Tidskriftsartikel (refereegranskat)abstract
- Spore production of bryophytes is common in subalpine ecosystems, but how spore banks of bryophytes vary with elevations is unknown. We used peat cores from twoSphagnumdominated peatlands, a low- (780 m a.s.l.) and a high-elevation (1480 m a.s.l.) site to test the hypotheses that spore concentration, accumulation rate, germinability and longevity are lower at a high-elevation peatland than those at lower elevation due to the assumed climatic limitations at high elevation. Along the cores,Sphagnumspores were extracted, burial time of spores was dated and spore germinability was tested layer by layer.Sphagnumspore concentration, accumulation rate and germinability were greater at the high-elevation peatland than at the low-elevation site. Both peatlands had long-term persistentSphagnumspore banks with a predicted longevity (the burial time when 1% spores are viable) ofc. 390 and 140 years for the low- and high-elevation sites, respectively. Our study suggests thatSphagnum, the ecological engineer of peatlands, by regulating spore production and longevity can maintain relatively constant spore banks which may be of great importance in population regeneration and persistence in a changing world.
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| 7. |
- Xu, Sihong, et al.
(författare)
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Carbon doped MO-SDC material as an SOFC anode
- 2007
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 165:1, s. 82-86
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Tidskriftsartikel (refereegranskat)abstract
- Oxide mixtures MO-SDC, M=Cu, Ni, Co, SDC=Ce0.9Sm0.1O1.95 were synthesized by employing a citrate/nitrate combustion technique. Two kinds of Carbon materials, activated carbon (AC) and vapor grown carbon fiber (VGCF) were homogeneously dispersed into the MO-SDC. The materials can be used as anodes to fabricate single cells using a uniaxial die-press method. The sintering temperature was studied to optimize cell performance. Experimental results showed that cells sintered at 700 degrees C had better performance. When the temperature was above 750 degrees C, the cells were severely distorted, and cannot be tested. Compared with the basic MO-SDC anode, AC and VGCF improve the solid oxide fuel cell (SOFC) anode properties, due to a change of the microstructures of the anode materials which enhance their electron conductivity. Single cell performances were evaluated by I-V measurements, and when 1.25 wt.%VGCF was introduced into the MO-SDC by ball-milling, termed: 1.25 wt.%VGCF-MO-SDC, the 1.25 wt.%VGCF-MO-SDC anode material could achieve the highest power density of up to 0.326 W cm(-2) with H-2 as fuel. The calcination temperature of the MO-SDC dry gel also strongly influenced the electrochemical performance of the 1.25 wt.%VGCF-MO-SDC material. XRD spectra for each calcined temperature and the I-V measurement both suggest that calcinations at 550 degrees C for 1 h are suitable. 1.0 wt.%AC-MO-SDC and 1.25 wt.%VGCF-MO-SDC have similar performance when the cell was fed in methanol/3%H2O, and the corresponding power density was up to 0.253 W cm(-2). Traces of carbon were found in the off-gases.
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| 8. |
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| 9. |
- Yusup, Shuayib, et al.
(författare)
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Smoke promotes germination of peatland bryophyte spores
- 2023
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 74:1, s. 251-264
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Tidskriftsartikel (refereegranskat)abstract
- Northern peatlands are globally important carbon stores. With increasing fire frequency, the re-establishment of bryophytes becomes crucial for their carbon sequestration. Smoke-responsive germination is a common trait of seeds in fire-prone ecosystems but has not been demonstrated in bryophytes. To investigate the potential role of smoke in post-fire peatland recovery, we tested the germination of spores of 15 bryophyte species after treatment with smoke-water. The smoke responsiveness of spores with different laboratory storage times and burial depths/age (3-200 years) was subsequently tested. Smoke increased the germination percentage for 10 of the species and the germination speed for four of these. Smoke responsiveness increased along the fire frequency gradient from open expanse to forest margin, consistent with the theory that this selects for the maintenance of fire-adapted traits. Smoke enhanced the germinability of 1-year but not 4-year laboratory-stored spores, and considerably increased the germinability of spores naturally buried in peat for up to similar to 200 years. The effect of fire may be overlooked in non-fire-prone ecosystems, such as those in which wetland bryophytes dominate. Our study reveals a mechanism by which an increase in fire frequency may lead to shifts in species dominance, which may affect long-term carbon sequestration in peatlands.
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