| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Ding, Jinzhi, et al.
(författare)
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Decadal soil carbon accumulation across Tibetan permafrost regions
- 2017
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 10:6, s. 420-424
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Tidskriftsartikel (refereegranskat)abstract
- Permafrost soils store large amounts of carbon. Warming can result in carbon release from thawing permafrost, but it can also lead to enhanced primary production, which can increase soil carbon stocks. The balance of these fluxes determines the nature of the permafrost feedback to warming. Here we assessed decadal changes in soil organic carbon stocks in the active layer-the uppermost 30 cm-of permafrost soils across Tibetan alpine regions, based on repeated soil carbon measurements in the early 2000s and 2010s at the same sites. We observed an overall accumulation of soil organic carbon irrespective of vegetation type, with a mean rate of 28.0 g Cm-2 yr(-1) across Tibetan permafrost regions. This soil organic carbon accrual occurred only in the subsurface soil, between depths of 10 and 30 cm, mainly induced by an increase of soil organic carbon concentrations. We conclude that the upper active layer of Tibetan alpine permafrost currently represents a substantial regional soil carbon sink in a warming climate, implying that carbon losses of deeper and older permafrost carbon might be offset by increases in upper-active-layer soil organic carbon stocks, which probably results from enhanced vegetation growth.
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| 3. |
- Li, Junjie, et al.
(författare)
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A Novel Dry Selective Isotropic Atomic Layer Etching of SiGe for Manufacturing Vertical Nanowire Array with Diameter Less than 20 nm
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944 .- 1996-1944. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires have great application prospects in field effect transistors and sensors. In this study, the process and challenges of manufacturing vertical SiGe/Si nanowire array by using the conventional lithography and novel dry atomic layer etching technology. The final results demonstrate that vertical nanowires with a diameter less than 20 nm can be obtained. The diameter of nanowires is adjustable with an accuracy error less than 0.3 nm. This technology provides a new way for advanced 3D transistors and sensors.
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| 4. |
- Chen, Wenchuang, et al.
(författare)
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Experiments and CFD modeling of a dual-raft wave energy dissipator
- 2021
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Ingår i: Ocean Engineering. - : Elsevier BV. - 0029-8018 .- 1873-5258. ; 237
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Tidskriftsartikel (refereegranskat)abstract
- A wave energy dissipator (WED) is proposed in this paper, composed of two asymmetric hinged floaters and two hydraulic cylinders, with the purpose to resist wave-induced relative rotation around the hinge. Experimental studies are performed to explore its performance under a wide range of regular waves. Based on Reynolds-averaged Navier-Stokes equations, a 3D numerical model is set up, considering the non-linear interaction of wave and WED. The agreement between the experimental and numerical results is good. With the validated numerical model, the influence of the WED geometrical factors on energy conversion and wave transmission is examined. For a given raft length, the difference in energy conversion between the two multiplicative inverse fore-and-aft raft lengths is significant, which is dependent on the wave frequency. However, as for the wave transmission, the difference in between is insignificantly small, almost independent of the wave frequency. The findings demonstrate that, for energy conversion, its maximum value per unit length corresponds to a large fore-and-aft length ratio but a small total raft length. The combination of experiments and simulations provides reference for both understanding of hydrodynamic behaviours and design including parameter selection of the dissipator.
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| 5. |
- Li, Qinghu, et al.
(författare)
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Retroperitoneal packing or angioembolization for haemorrhage control of pelvic fractures-Quasi-randomized clinical trial of 56 haemodynamically unstable patients with Injury Severity Score ≥33
- 2016
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Ingår i: Injury. - : Elsevier BV. - 0020-1383 .- 1879-0267. ; 47:2, s. 395-401
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Both retroperitoneal pelvic packing and primary angioembolization are widely used to control haemorrhage related to pelvic fractures. It is still unknown which protocol is the safest. The primary aim of this study is to compare survival and complications of pelvic packing and angioembolization in massive haemorrhage related to pelvic fractures.METHODS: Patients with haemodynamically unstable pelvic fractures were quasi-randomized to either pelvic packing (PACK) or angiography (ANGIO) using the time of admission as separator. Physiological markers of haemorrhage, time to intervention, procedure/surgical time, transfusion requirements, complications and early mortality were recorded and analyzed.RESULTS: 29 patients were randomized to PACK and 27 patients to ANGIO. The Injury Severity Score (ISS) in the ANGIO group was lower than in the PACK group (43±7 vs 48±6) (p<0.01). The median time from admission to angiography for the ANGIO group was 102min (range 76-214), and longer than 77min (range 43-125) from admission to surgery for the PACK group (p<0.01). The procedure time for the ANGIO group was 84min (range 62-105); while the surgical time was 60min (range 41-92) for the PACK group (p<0.001). The ANGIO group received 6.4 units packed red blood cells (range 4-10) in the first 24h after angiography. The PACK group required 5.2 units (range 3-10) in the first 24h after leaving the operating theatre (p=0.124). 9 patients in the ANGIO group underwent pelvic packing for persistent bleeding. 6 patients in the PACK group required pelvic angiography after pelvic packing for ongoing hypotension following packing (p=0.353). 5 patients in the ANGIO group died (2 from exsanguination), while 4 in the PACK group died (none from exsanguination) (p=0.449). Complications occurred without differences in both groups.CONCLUSIONS: Compared with angioembolization, pelvic packing has shorter time to intervention and surgical time. Thus pelvic packing is the more rapid treatment of severe pelvic trauma than pelvic angioembolization. It is suitable for patients with haemodynamic instability at centers where the interventional radiology staff is not in-house at all times.REGISTRATION: ClinicalTrials.gov (NCT02535624) and ISRCTN registry (ISRCTN91713422).
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| 6. |
- Mak, Yim Ling, et al.
(författare)
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Perfluorinated Compounds in Tap Water from China and Several Other Countries
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:13, s. 4824-4829
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Tidskriftsartikel (refereegranskat)abstract
- The recent development of a sensitive and accurate analytical method for the analysis of 20 perfluorinated compounds (PFCs), including several short-chain PFCs, has enabled their quantification in tap water collected in China, Japan, India, the United States, and Canada between 2006 and 2008. Of the PFCs measured, PFOS, PFHxS, PFBS, PFPrS, PFEtS, PFOSA, N-EtFOSAA, PFDoDA, PFUnDA, PFDA, PFNA, PFHpA, PFHxA, PFPeA, PFBA, and PFPrA were found at detectable concentrations in the tap water samples. The water samples from Shanghai (China) contained the greatest concentrations of total PFCs (arithmetic mean = 130 ng/L), whereas those from Toyama (Japan) contained only 0.62 ng/L. In addition to PFOS and PFOA, short-chain PFCs such as PFHxS, PFBS, PFHxA, and PFBA were found to be prevalent in drinking water. According to the health-based values (HBVs) and advisory guidelines derived for PFOS, PFOA, PFBA, PFHxS, PFBS, PFHxA, and PFPeA by the U.S.EPA and the Minnesota Department of Health, tap water may not pose an immediate health risk to consumers.
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| 7. |
- Pan, Jing, et al.
(författare)
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Altitudinal distributions of PCDD/Fs, dioxin-like PCBs and PCNs in soil and yak samples from Wolong high mountain area, eastern Tibet-Qinghai Plateau, China
- 2013
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 444, s. 102-109
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Tidskriftsartikel (refereegranskat)abstract
- Topsoil along the altitudinal gradient (2086-4487m above sea level) and yak samples, collected from Wolong high mountain area of Sichuan Province, western China, were analyzed for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs) and polychlorinated naphthalenes (PCNs) using HRGC-HRMS. The total concentrations of PCDD/Fs, dl-PCBs, and PCNs in soils were: 2.48-4.30pgg-1 dw (dry weight), 7.6-10.5pgg-1 dw, and 13.0-29.0pgg-1 dw, respectively; the greatest concentrations were found at sampling sites of 3927m, 4487m and 3345m, correspondingly. The total PCDD/Fs and dl-PCBs concentrations showed positive correlations with increasing altitudinal gradient. The congener profiles of both 2,3,7,8-PCDD/Fs and dl-PCBs at different altitudes showed similar patterns. PCNs were dominated by Tri-CNs. The long-range atmospheric transport and subsequent aerial deposition are likely the sources for these POPs in area examined. The total TEQs in soils were in the range of 0.28-0.42pgg-1 dw, and the total TEQs in the yak muscle and fatty tissue samples were 3.81-4.09pgTEQg-1 lipid weight. The daily intake of TEQs was estimated to be below the WHO's tolerable daily intake according to the local people's dietary habits in Wolong area, which is unlikely to cause any adverse health effects to the yak muscle consuming people.
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| 8. |
- Pan, Jing, et al.
(författare)
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Comparison of Historical Record of PCDD/Fs, Dioxin-Like PCBs, and PCNs in Sediment Cores from Jiaozhou Bay and Coastal Yellow Sea : Implication of Different Sources
- 2012
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Ingår i: Bulletin of Environmental Contamination and Toxicology. - : Springer. - 0007-4861 .- 1432-0800. ; 89:6, s. 1240-1246
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Tidskriftsartikel (refereegranskat)abstract
- The concentrations of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs) were measured in two sediment cores collected from Jiaozhou Bay. The concentrations of PCDD/Fs, dioxin-like PCBs, and PCNs in the cores were in the range of 2.8-26.3, 7.1-82.4 and 3.9-56.4 pg/g dw, respectively. The depth profiles of total concentrations PCDD/Fs and dioxin-like PCBs were similar in the sediment core J37 inside Jiaozhou Bay, but different from those in the sediment core J94 outside the bay, suggesting the different sources. In both cores Tri-CNs and Tetra-CNs were dominant, similar to the PCNs composition of some Halowax technical products. The maximal PCNs contamination occurred in the mid-1970s (outside the Bay) and early-1990s (inside the Bay). An increase of the indicator CN congeners characteristic for thermal source in the top layers of the sediment core inside the bay indicated that the contribution from the municipal solid waste incineration has been more important in recent years.
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| 9. |
- Tan, Shijing, et al.
(författare)
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Visualizing Elementary Reactions of Methanol by Electrons and Holes on TiO2(110) Surface
- 2018
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 122:50, s. 28805-28814
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Tidskriftsartikel (refereegranskat)abstract
- Direct visualization and comparison of the elementary reactions induced by electrons and holes are of importance for finding a way to conduct chemical reactions and reaction sequences in a controllable manner. As a semiconductor, TiO2 provides a playground to perform the measurements, and moreover, the information can be useful for design of high-performance TiO2-based catalysts and photocatalysts. Here, we present our investigation on the elementary reactions of CH3OH on TiO2 surface through visualization of specific elementary steps by highly controllable electron and hole injection using scanning tunneling microscopy. The distinct sequential routes and their kinetics, namely, breaking C-O and O-H bonds by electrons and breaking O-H and C-H bonds by holes, respectively, have been experimentally identified and well elucidated by density functional theory calculations. Our nonlocal h-injection experimental and theoretical results suggest that the delocalized holes in the TiO2 substrate should be responsible for the temperature-dependent h-route reactions. The locally triggered e-route reaction is associated with the fact that the location of the unoccupied hybridization states is much higher than that of the conduction band onset. Our findings resolve the long-standing debate about the intermediate species and reaction mechanism in photocatalytic oxidation of CH3OH. Our proposed protocol offers a powerful means to study elementary reactions induced by electrons and holes on a semiconductor surface in general.
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