| 1. |
- Hu, Yunfeng, et al.
(författare)
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Spatial-Temporal Pattern of GIMMS NDVI and Its Dynamics in Mongolian Plateau
- 2008
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Ingår i: International Workshop on Earth Observation and Remote Sensing Applications, EORSA2008. - NEW YORK : IEEE. - 9781424423934 ; , s. 119-124
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Konferensbidrag (refereegranskat)abstract
- The physical geography of Mongolian Plateau plays an important role in the East Asian climate ecology system. In this research, GIMMS NDVI, the third generation of NDVI dataset, was processed using the MVC method first, then the spatial-temporal patterns of GIMMS NDVI in Mongolian Plateau during 1982-2003 was investigated, and the transect from Tariat to Xilin Gol was also selected to analyze the NDVI dynamic processes in detail. The results demonstrated that: 1) The general spatial distribution pattern of NDVI showed a clear spatial differentiation. The high value pixels were mainly distributed in the east and north of Mongolian Plateau with forest and meadow steppe land cover, while the low value pixels were mainly distributed in the west and centre part of Mongolian Plateau with desert and Gobi land cover. However, the annual NDVI variability was relative small either in the high-covered regions (i.e. forest, forest steppe, and meadow steppe) or in low-covered regions (i.e. steppe desert, desert and Gobi), while the region with typical steppe normally had higher annual NDVI variability; 2) During 1982-2003, the dynamic evolution process of NDVI in Mongolian Plateau also showed an evident spatial differentiation. About 12.4% of total area featured a significant increase, 4.8% of total area featured an increase but without significance, and 9.3% of total area featured decrease without significance. The other part, about 73.5% of total area, had no obvious change. The NDVI increased significantly in the South-East, South and of Mongolian Plateau, while it decreased in the North-East and North of Mongolian Plateau. Further, the NDVI-increased regions were those typical steppe and farming-pastoral regions before, while the NDVI-decreased regions were those well-covered forest, forest steppe and meadow steppe regions before.
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| 2. |
- Chen, Hong, et al.
(författare)
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Layered V-B-O Polyoxometalate Nets Linked by Diethylenetriamine Complexes with Dangling Amine Groups
- 2014
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Ingår i: Dalton Transactions. - 1477-9226 .- 1477-9234. ; 43:41, s. 15283-15286
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Tidskriftsartikel (refereegranskat)abstract
- Two layered V-B-O contained polyoxometalate (POM) net structures, denoted as SUT-12 and SUT-13, are reported here. SUT-12 was synthesized by the boric acid flux method, and it represents the first 2D structure constructed from the V6B20 vanadoborate cluster. SUT-13 was synthesized through the hydrothermal method and constructed from V12B6P12 vanadium borophosphate clusters. In both structures, the vanadoborate or vanadium borophosphate clusters were linked through in-situ formed Zn(DETA)2 or Cu(DETA)2 complexes. Surprisingly, for all DETA molecules in the two metal complexes, there is one dangling amine group when it coordinated to the metal. The phenomena of the dangling amine group feature is abnormal and the Cu(DETA)2 complexes in SUT-13 was taken as an example and studied by density function theory (DFT) calculation in order to understand this unusual feature.
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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. |
- Hu, Yunfeng, et al.
(författare)
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The Trajectory of Urbanization Process in the Yangtze River Delta During 1990 to 2005
- 2009
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Ingår i: 2009 JOINT URBAN REMOTE SENSING EVENT. - NEW YORK : IEEE. - 9781424434602 ; , s. 407-414
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Konferensbidrag (refereegranskat)abstract
- Rapid economic development, combined with tremendous population growth and migration from rural areas, has resulted in a dramatic urbanization in the Yangtze River Delta over the last three decades. In order to develop a more quantitative understanding of urbanization trajectory in the Yangtze Delta from the late 1980s to 2005, the time-series national land cover/land-use database (NLCD), interpreted from remote sensing imagery (including Landsat TM, ETM+ and CBERS), was examined from the aspects of spatial pattern and temporal process. The results showed that the urban land in the Yangtze River Delta has increased from 2.29x10(3) km(2) in the late 1980s to 4.19x10(3) km(2) in 2005. The percentages of total land area in the Yangtze Delta occupied by urban environments in the late 1980s, 1995, 2000 and 2005 were 2.09%, 3.03%, 3.28%, and 3.82% respectively. During the late 1980s - 2005, the total urban expansion in this region was 1.92x10(3) km(2), resulting in an annual urban expansion area (UXa) of about 118.72 km(2) per year, with an urban erpansion intensity (UXt)of 83.03%. There were significant spatial trends and differences in urbanization level and urban expansion. Most urban land and urban expansion have occurred along the Huning Railway (Shanghai-Nanjing) and the Hanzhou Bay. This study also revealed substantial temporal differences in the rate at which urban areas have expanded. There was a great deal of urban growth in the late 1980s - 1995, and also in 2000 - 2005. The 1995 - 2000 period saw a slow expansion speed due to government initiatives designed to hall the loss of agricultural land. In this study, both patterns and dynamics of urban distribution and urban expansion were examined on temporal and spatial scales, and integrated to produce a comprehensive evaluation of recent urbanization trajectory in the Yangtze River Delta.
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| 5. |
- Lin, Zijie, et al.
(författare)
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Evaluation and review of ways to differentiate sources of ethanol in postmortem blood
- 2020
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Ingår i: International journal of legal medicine. - : SPRINGER. - 0937-9827 .- 1437-1596. ; 134, s. 2081-2093
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Forskningsöversikt (refereegranskat)abstract
- Accurate determination of a persons blood alcohol concentration (BAC) is an important task in forensic toxicology laboratories because of the existence of statutory limits for driving a motor vehicle and workplace alcohol testing regulations. However, making a correct interpretation of the BAC determined in postmortem (PM) specimens is complicated, owing to the possibility that ethanol was produced in the body after death by the action of various micro-organisms (e.g., Candida species) and fermentation processes. This article reviews various ways to establish the source of ethanol in PM blood, including collection and analysis of alternative specimens (e.g., bile, vitreous humor (VH), and bladder urine), the identification of non-oxidative metabolites of ethanol, ethyl glucuronide (EtG) and ethyl sulfate (EtS), the urinary metabolites of serotonin (5-HTOL/5-HIAA), and identification ofn-propanol andn-butanol in blood, which are known putrefaction products. Practical utility of the various biomarkers including specificity and stability is discussed.
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| 6. |
- Liu, Jian, et al.
(författare)
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Printable highly conductive conjugated polymer sensitized ZnO NCs as cathode interfacial layer for efficient polymer solar cells
- 2014
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:11, s. 8237-8245
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Tidskriftsartikel (refereegranskat)abstract
- We report a facile way to produce printable highly conductive cathode interfacial layer (CIL) for efficient polymer solar cells (PSCs) by sensitizing ZnO nanocrystals (NCs) with a blue fluorescent conjugated polymer, poly(9, 9-bis-(6-diethoxylphosphorylhexyl) fluorene) (PFEP). Herein, PFEP plays dual distinctive roles in the composite. Firstly, PFEP chains can effectively block the aggregation of ZnO NCs, leading to uniform and smooth film during solution processing via assembly on ZnO NC surfaces through their pending phosphonate groups. Secondly, PFEP can greatly improve the conductivity of ZnO NCs by charge transfer doping, that is the charge transfer from the sensitizer driven by electron-chemical potential equilibrium, which could be even more pronounced under light illumination because of light excitation of PFEP sensitizer. The increased conductivity in ZnO-PFEP layer renders more efficient electron transport and extraction compared to pristine ZnO layer. This ZnO-PFEP CIL was successfully applied to PSCs based on three polymer donor systems with different band-gaps, and efficiency enhancements from 44 to 70% were observed compared to those PSCs with pristine ZnO CIL. The highest efficiency of 7.56% was achieved in P(IID-DTC):PC70BM-based PSCs by using ZnO-PFEP film as CIL. Moreover, the enhanced conductivity due to the charge-transfer doping effect allows thick ZnO-PFEP film to be used as CIL in high-performance PSCs. Both the high conductivity and good film-forming properties of ZnO-PFEP CIL are favorable for large-scale printable PSCs, which is also verified by high-efficiency PSCs with ZnO-PFEP CIL fabricated using doctor-blading, a large-scale processing technique. The work provides an efficient printable cathode interfacial material for efficient PSCs.
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| 7. |
- Liu, Jiyuan, et al.
(författare)
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Regional differences of China's urban expansion from late 20th to early 21st century based on remote sensing information
- 2012
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Ingår i: Chinese Geographical Science. - : Springer Science and Business Media LLC. - 1002-0063 .- 1993-064X. ; 22:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the regional differences of China's urban land expansion from the late 1980s to the year of 2008, based on the spatio-temporal analysis of CLCD (China's land cover/land use database) datasets which were mainly produced from remote sensing imagery data. A newly defined urbanization level index (UI), based on urban land area, is proposed to describe Chinese urban expansion process at 1 kilometer, provincial, regional, and national scales, together with the absolute urban expansion index (UE(a)) and the relative urbanization expansion index (UE(r)). The results indicate that the percentages of total land area occupied by urban in the late 1980s, 1995, 2000, 2005, and 2008 were approximately 0.25%, 0.32%, 0.33%, 0.43% and 0.52% of China's total land area, respectively. Between the late 1980s and 2008, the total urban expansion in the mainland of China was 2.645 x 10(4) km(2), resulting in an annual urban expansion area of about 1322.7 km(2)/yr, with the UE(r) of 111.9%. This study also finds that there has been an obvious spatial gradient of urbanization ratio running from the east coast to the west inland, and the urbanization gaps among different regions have persisted over the past two decades. The study also reveals obvious temporal variations of the urbanization rates. There was very little urban growth during the period of 1995-2000 due to the governmental policy factors.
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| 8. |
- Song, Zhengyang, et al.
(författare)
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Mechanical Responses of a Deeply Buried Granite Exposed to Multilevel Uniaxial and Triaxial Cyclic Stresses : Insights into Deformation Behavior, Energy Dissipation, and Hysteresis
- 2021
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Ingår i: Advances in Materials Science and Engineering. - : Hindawi Publishing Corporation. - 1687-8434 .- 1687-8442. ; 2021
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the results for cyclic uni/triaxial tests on the deeply seated granite samples drilled from a -915m deep tunnel in Sanshandao (SSD) gold mine. The monotonic and cyclic tests were carried out to observe the mechanical responses of the granite samples under different loading regimes. The disparities concerning the strain evolution and compressive strength of granite samples considering monotonic and cyclic uniaxial and triaxial loading are presented. Deformation behaviour, dissipated energy, and hysteresis are documented and evaluated. Quantitative correlations between strain evolution and cyclic stress levels are revealed. The amount of energy transformation during uniaxial and triaxial cyclic loading is determined. The impacts of confining pressure level on ultimate strain, energy dissipation, and stress-strain phase shift are presented. The mechanical responses of the granite samples subjected to different stress paths and loading strategies are summarised, and corresponding interpretations are given to clarify the differences of mechanical behaviour encountered in distinct loading methods.
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| 9. |
- Xing, Xu, et al.
(författare)
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Double bismuth-based Bi2S3/Bi2MoO6 S-scheme heterojunction for ultrafast photocatalytic removal of Cr(VI)
- 2024
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Ingår i: Journal of Environmental Chemical Engineering. - 2213-3437. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- The mild, fast and green removal of hexavalent chromium (Cr(VI)) from wastewater has already attracted extensive attention due to the severe acute toxicity and carcinogenicity of Cr(VI). At present work, Bi2S3/Bi2MoO6 S-scheme heterojunctions were constructed by facile solvothermal assembly and in situ anion exchange methods for visible light-driven efficient photocatalytic removal of Cr(VI). The structure-activity relationship, photoelectrochemical properties, and density functional theory (DFT) calculations revealed that the controllable construction of the heterostructure significantly expanded the light response range and remarkably enhanced the light absorption capacity. In particular, the unique charge transfer mechanism of this S-scheme heterojunction is conducive to promoting efficient separation of photogenerated charges and thus enhancing the photocatalytic performance. The results show that the total efficiency of Cr(VI) removal by the developed Bi2S3/Bi2MoO6 heterojunction under visible light irradiation is 98.5% within 6 min, with a k value of 0.466 min−1. This work provides a new route with enormous promise to construct bismuth-based S-scheme heterojunction photocatalysts for clean and efficient environmental remediation.
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| 10. |
- Xueyan, Zhang, et al.
(författare)
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NDVI spatial pattern and its differentiation on the Mongolian Plateau
- 2009
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Ingår i: JOURNAL OF GEOGRAPHICAL SCIENCES. - : Springer Science and Business Media LLC. - 1009-637X .- 1861-9568. ; 19:4, s. 403-415
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Tidskriftsartikel (refereegranskat)abstract
- GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north, areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was indicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVI spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0.
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