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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- 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. ; 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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| 3. |
- 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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| 4. |
- Chen, WenChuang, et al.
(författare)
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Numerical modelling of a point-absorbing wave energy converter in irregular and extreme waves
- 2017
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Ingår i: Applied Ocean Research. - : Elsevier BV. - 0141-1187 .- 1879-1549. ; 63, s. 90-105
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Tidskriftsartikel (refereegranskat)abstract
- Based on the Navier-Stokes (RANS) equations, a three-dimensional (3-D) mathematical model for the hydrodynamics and structural dynamics of a floating point-absorbing wave energy converter (WEC) with a stroke control system in irregular and extreme waves is presented. The model is validated by a comparison of the numerical results with the wave tank experiment results of other researchers. The validated model is then utilized to examine the effect of wave height on structure displacements and connection rope tension. In the examined cases, the differences in WEC’s performance exhibited by an inviscid fluid and a viscous fluid can be neglected. Our results also reveal that the differences in behavior predicted by boundary element method (BEM) and the RANS-based method can be significant and vary considerably, depending on wave height.
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| 5. |
- Li, Bin, et al.
(författare)
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Inverted-V and low-energy broadband electron acceleration features of multiple auroras within a large-scale surge
- 2013
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Ingår i: Journal of Geophysical Research: Space Physics. - : American Geophysical Union (AGU). - 2169-9380. ; 118:9, s. 5543-5552
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Tidskriftsartikel (refereegranskat)abstract
- Results are presented from a Cluster C2 satellite crossing through the acceleration region of multiple auroral structures within a large-scale surge, simultaneously monitored by DMSP F17 imager data. The magnetic and electric field data are consistent with the auroral distribution at large and medium scales. We identify the quasi-static acceleration above and below C2 orbit by downgoing inverted-V electrons and parallel electric potential drops, respectively. In the poleward surge region, within or adjacent to the inverted-V arcs, intense low-energy (broadband) electron fluxes are seen as well as a rough equality between E/B and the Alfven velocity, suggesting that these are of Alfvenic origin. The most poleward and equatorward auroral structure is found to be Alfvenic and quasi-static, respectively. In between, the structures are of mixed origin. We estimate the relative role of the acceleration processes by the contributions to the downward electron energy flux by electrons above and below 1.62keV. Although these are local estimates, they should be representative also below Cluster altitude, except for two regions of intense downward Poynting flux, the power of which will be dissipated at lower altitudes and increasing the Alfvenic contribution. This is also supported by intense fluxes of low-energy, broadband, upgoing electrons observed within these regions. Otherwise, the inverted-V contribution dominates for most of the auroral structures observed by Cluster. The Alfvenic contribution to the mixed arc emissions is to extend these to higher altitudes, as shown by numerical simulation results.
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| 6. |
- 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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| 7. |
- Li, Ziyue, et al.
(författare)
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Integrating life cycle assessment and a farmer survey of management practices to study environmental impacts of peach production in Beijing, China
- 2022
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Ingår i: Environmental Science and Pollution Research. - : Springer Nature. - 0944-1344 .- 1614-7499.
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Tidskriftsartikel (refereegranskat)abstract
- While intensive peach production has expanded rapidly in recent years, few studies have explored the environmental impacts associated with specific regional systems or the optimal management strategies to minimize associated environmental risks. Here, data from a survey of 290 native farmers were used to conduct a life cycle assessment to quantify the acidification potential (AP), global warming potential (GWP), eutrophication potential (EP), and reactive nitrogen (Nr) losses in peach production in Pinggu District, Beijing. Total annual Nr losses, and GWP, AP, and EP values for peach production in Pinggu District were respectively 10.7 kg N t−1, 857 kg CO2-eq t−1, 12.9 kg SO2-eq t−1, and 4.1 kg PO4-eq t−1. The principal driving factors were fertilizer production, transportation, and application, which together accounted for 94%, 67%, 75%, and 94% of Nr losses, GWP, AP, and EP, respectively. In the high yield, high nitrogen-use efficiency (HH) group, relative values of Nr losses, GWP, AP, and EP were respectively 33%, 25%, 39%, and 32% lower than the overall averages for 290 orchards. Further analyses indicate that improved farming practices such as decreasing application rates of fertilizers, increasing proportion of base fertilization rate, and proper fertilization frequency in the HH group were the main reasons for these orchards’ better performance in peach yields and partial factor productivity of nitrogen fertilizer, and their reduced environmental impacts. These results highlight the need to optimize nutrient management in peach production in order simultaneously to realize both environmental sustainability and high productivity in the peach production system.
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