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Spatial patterns of vegetation and climate in the North China Plain during the Last Glacial Maximum and Holocene climatic optimum

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Science China Earth Sciences 2019年第8期62卷 1279-1287页

作者： Manyue LI shengrui ZHANG Qinghai xu Jule XIAO Ruilin WEN Institute of Nihewan Archaeology Hebei Normal UniversityShijiazhuang050024China College of Resources and Environment Hebei Key Laboratory of Environmental Change and Ecological ConstructionHebei Normal UniversityShijiazhuang050024China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China CAS Center for Excellence in Life and Paleoenvironment Beijing100044China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing100049China

Reconstructing the spatial patterns of regional climate and vegetation during specific intervals in the past is important for assessing the possible responses of the ecological environment under future global warming scenarios. In this study, we reconstructed the history of regional vegetation and climate based on six radiocarbon-dated pollen records from the North China Plain. Combining the results with existing pollen records, we reconstruct the paleoenvironment of the North China Plain during the Last Glacial Maximum(LGM) and the Holocene Climatic Optimum(HCO). The results show that changes in the regional vegetation since the LGM were primarily determined by climatic conditions, the geomorphic landscape and by human activity.During the LGM, the climate was cold and dry;mixed broadleaf-coniferous forest and deciduous-evergreen broadleaf forest developed in the southern mountains, and cold-resistant coniferous forest and mixed broadleaf-coniferous forest were present in the northern mountains. The forest cover was relatively low, with mesophytic and hygrophilous meadow occupying the southern part of the plain, and temperate grassland and desert steppe were distributed in the north;Chenopodiaceae-dominated halophytes grew on the exposed continental shelf of the Bohai Sea and Yellow Sea. During the HCO, the climate was warm and wet;deciduous broadleaf forest and deciduous-evergreen broadleaf forest, with subtropical species, developed in the southern mountains, and deciduous broadleaf forest with thermophilic species was present in northern mountains. Although the degree of forest cover was greater than during the LGM, the vegetation of the plain area was still dominated by herbs, while halophytes had migrated inland due to sea level rise. In addition, the expansion of human activities, especially the intensification of cultivation,had a significant influence on the natural vegetation. Our results provide data and a scientific basis for paleoclimate modelling and regional carbon cycle assessment in north China, w

关键词： North China Plain Last Glacial Maximum Holocene Climatic Optimum Pollen Vegetation Paleoenvironment

Quantitative indicative significance of pollen assemblages on vegetation coverage in deciduous Quercus forest in the central Loess Plateau, China

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Science China Earth Sciences 2019年第6期62卷 992-1001页

作者： Yuanhao SUN shengrui ZHANG Qinghai xu Yiwen LI Wei SHEN Tao WANG Zhongze ZHOU Ruchun ZHANG College of Resources and Environment Sciences Hebei Key Laboratory of Environmental Change and Ecological ConstructionHebei Normal University Institute of Nihewan Archaeology Hebei Normal University College of Resources and Environment Anhui University Institute of Geographical Science Hebei Academy of Sciences

We compared the pollen assemblages of surface moss samples and corresponding vegetation inventory data from 34 sites in the Huangling region of the central Loess Plateau. Our aims were to determine the characteristics of the pollen assemblages from the deciduous broadleaved forest climax community and its significance in terms of vegetation type and species composition. The pollen assemblages are dominated by woody plants such as Quercus(42% of total terrestrial pollen),Betula(16%) and Pinus(12%), with minor differences between different plant communities. The pollen assemblages of individual sampling sites differed from the vegetation composition within the 0–100 m scope and were more similar to the vegetation coverage within the 0–1000 m scope. This indicates that the surface pollen assemblages mainly reflect the comprehensive information from the vegetation composition of a large area, rather than the vegetation composition close to the sampling site. The contents of Quercus, Betula and Pinus pollen are high, and close to their vegetation coverage; whereas the contents of deciduous broadleaved arbor taxa(such as Malus and Acer) are lower, but their corresponding regional vegetation cover is higher. This suggests that the vegetation information conveyed by poorly-represented pollen taxa should be considered when interpreting stratigraphic pollen assemblages. Using the observed quantitative relationships between pollen and vegetation of the main taxa, we reconstructed the regional vegetation composition in the Gonghai Lake area of the northeastern Loess Plateau during the middle Holocene(7300–5000 yr BP). The results indicated that Quercus-dominated deciduous broadleaved forest climax community developed in the mountains surrounding the lake.

关键词： Loess Plateau Deciduous broadleaved forest Climax community Pollen assemblage Absolute vegetation coverage

Investigation of etching method for fabricating deep through holes on ultra-high resistivity silicon

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Journal of Semiconductors 2017年第5期38卷 106-110页

作者： Lin Du shengrui xu Ying Wang Ling Lü Jincheng Zhang Yue Hao School of Microelectronics Xidian University

In this paper,the etching characteristics of the ultra-high resistivity silicon(UHRS) by using the Bosch process were investigated.The experimental results indicated that the sulfur hexafluoride flux,the temperature of the substrate,the platen power and the etching intermittence had important influence on the etching rate and the etching morphology of the UHRS.The profiles and morphologies of sidewall were characterized with scanning electron microscopy(SEM).By using an improved three-stage Bosch process,380-μm deep through holes were fabricated on the UHRS with the average etching rate of about 3.14 μm/min.Meanwhile,the fabrication mechanism of deep through holes on the UHRS by using the three-stage Bosch process was illustrated on the basis of the experimental results.

关键词： ultra-high resistivity silicon deep through hole three-stage etching method Bosch process

1.7 kV normally-off p-GaN gate high-electron-mobility transistors on a semi-insulating SiC substrate

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Science China(Information Sciences) 2023年第2期66卷 250-255页

作者： Shenglei ZHAO Jincheng ZHANG Yachao ZHANG Lansheng FENG Shuang LIU Xiufeng SONG Yixin YAO Jun LUO Zhihong LIU shengrui xu Yue HAO Key Lab of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices School of Microelectronics Xidian University School of Mechano-Electronic Engineering Xidian University Testing Center Sichuan Institute of Solid-State CircuitsChina Electronics Technology Group Corporation

A study of 1.7 kV normally-off p-GaN gate high-electron-mobility transistors(HEMTs) on SiC substrates is presented. The fabricated p-GaN HEMT with a gate-drain spacing LGD = 5 μm exhibited a threshold voltage of 1.10 V, a maximum drain current of 235 mA/mm, an ON/OFF ratio of 108, and a breakdown voltage of 440 V. Benefiting from the semi-insulating and high-critical-electric-field substrate, the p-GaN HEMT with LGD = 23 μm achieved the remarkably high breakdown voltage of 1740 V with substrate grounded. This breakdown voltage is very high compared with the reported values for p-GaN HEMTs on silicon substrates with substrate grounded. The vertical breakdown voltage for the p-GaN-on-SiC material exceeded 3 kV with substrate grounded. In addition, the maximum drain current at 500 K was 48% of that at 300 K with a negligible threshold voltage shift. These results indicate the substantial potential of p-GaN gate HEMTs on SiC substrates for high-voltage power applications.

关键词： p-GaN gate HEMTs high voltage SiC substrate

AGRICULTURAL GREEN DEVELOPMENT IN THE ERHAI LAKE BASIN-THE WAY FORWARD

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Frontiers of Agricultural Science and Engineering 2023年第4期10卷 510-517页

作者： Yong HOU Wen xu Wen-Feng CONG Kemo JIN Jiuliang xu Hao YING shengrui WANG Hu SHENG Linzhang YANG Wenqi MA Oene OENEMA Zhengxiong ZHAO Fusuo ZHANG State Key Laboratory of Nutrient Use and Management College of Resources and Environmental SciencesChina Agricultural UniversityBeijing 100193China College of Resources and Environmental Sciences Yunnan Agricultural UniversityKunming 650201China. Guangdong-Hong Kong Joint Laboratory for Water Security Center for Water ResearchAdvanced Institute of Natural SciencesBeijing Normal UniversityZhuhai 519087China Lishui Institute of Ecological Environment Nanjing UniversityNanjing 211200China. Key Laboratory of Agro-Environment in downstream of Yangze Plain Ministry of Agriculture and Rural Affairs of ChinaJiangsu Academy of Agricultural SciencesNanjing 210014China College of Resources and Environmental Sciences Hebei Agricultural UniversityBaoding 071001China Wageningen Environmental Research Wageningen University and Research6700 AA Wageningenthe Netherlands

Pollution of high-altitude lake basins by agriculture and rural activities,and the control of this pollution,have received increasing attention from academic research and government policy in China.Series of restrictions and regulations have been implemented to protect the surface,water quality.These restrictions and regulations have greatly impacted and transformed the agricultural systems and rural livelihoods surrounding these lake basins.Using Erhai Lake basin in Yunnan Province as a case study,three main challenges were identified for concurrently decreasing pollution in the lake and increasing farmer income.It is contended that scientifically-sound environmental protection policies and agricultural green development practices are key to reversing the current situation.This will help to protect the lake from pollution while smallholder farmers will be able to produce healthy food in an environmentally sustainable manner,and with a fair remuneration for all the services farmers providetothe society.

关键词： agriculturef af rmer income nitrogen phosphorus waterpollution

Application of nano-patterned InGaN fabricated by selfassembled Ni nano-masks in green InGaN/GaN multiple quantum wells

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Journal of Semiconductors 2023年第4期44卷 86-91页

作者： Ruoshi Peng shengrui xu Xiaomeng Fan Hongchang Tao Huake Su Yuan Gao Jincheng Zhang Yue Hao Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory School of MicroelectronicsXi'dian UniversityXi'an 710071China

The nano-patterned InGaN film was used in green InGaN/GaN multiple quantum wells(MQWs)structure,to relieve the unpleasantly existing mismatch between high indium content InGaN and GaN,as well as to enhance the light output.The different self-assembled nano-masks were formed on InGaN by annealing thin Ni layers of different thicknesses.Whereafter,the InGaN films were etched into nano-patterned films.Compared with the green MQWs structure grown on untreated InGaN film,which on nano-patterned InGaN had better luminous performance.Among them the MQWs performed best when 3 nm thick Ni film was used as mask,because that optimally balanced the effects of nano-patterned InGaN on the crystal quality and the light output.

关键词： GaN InGaN nano-mask nano-patterned MQWs

Mixing of Enriched Lithospheric Mantle-Derived and Crustal Magmas： Evidence from the Habo Cenozoic Porphyry in Western Yunnan

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Acta Geologica Sinica(English Edition) 2018年第5期92卷 1753-1768页

作者： XIA Bin LU Ye YUAN Yajuan CHEN Weiyan ZHANG Xiao xu Chi YU shengrui WAN Zhifeng School of Marine Sciences Sun Yat-sen University Guangzhou 510006 China Key Laboratory of Offshore Oil Exploration and Development of Guangdong Higher Education Institutes Guangzhou 51006 China Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering Guangzhou 510006China

New zircon U–Pb ages, whole-rock geochemistry and zircon Hf isotopes from the Habo porphyry Western Yunnan, China, were determined to provide constraints on the timing of uplift of the Eastern Tibetan Plateau. The intrusive rocks consist of shoshonitic porphyry(syenite porphyry and monzonite porphyry). Zircon laser ablation inductively coupled plasma mass spectrometry(LA-ICPMS) U–Pb dating indicates coeval emplacement ages of ～35 Ma. The porphyries have alkaline affinities, enrichment in large ion lithophile elements(LILEs) and light rare earth elements(LREEs)(e.g., Rb, Th, U, Pb), with depletion of high field strength elements(HFSEs)(e.g., Nb, Ti, Ta) and weak Eu anomalies. They display uniform Lu–Hf isotopic compositions with negative zircon εHf(t) values ranging from-3.9 to-0.6. The chemical characteristics of the syenite porphyries indicated that they most likely originated from the lower crust, with mantle-derived material involved in their generation. Geochemically, the monzonite porphyries are similar to the syenite porphyries; however, the lower MgO contents suggest that they were produced by different degrees of partial melting of the same lower crust source. Combined with the geochemical and isotopic data in this paper, imply that the alkali-rich porphyries of the Habo polymetallic deposit were derived from the partial melting of lower crust, enriched by mantle magma, formed in a conversion stage from stress extrusion(a strike-slip shear process) to local stress relaxation(a strike-slip pull-apart process) at the Ailaoshao tectonic zone.

关键词：岩浆混合斑岩外壳云南西方新生代亲石元素证据

由“统一”回归“地域”的语言塑造——现代影视表演中“方言”的审美价值

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电影评介 2023年第6期 29-35页

作者：于声瑞徐顺璐南京传媒学院戏剧影视学院表演系

如果从1963年中国内地第一部方言电影《抓壮丁》算起,方言电影在中国经历了半个多世纪的发展。[1]近年来,方言影视作品发展势头愈发强劲,涌现了一批颇具代表性又独有韵味的高质量作品,受到了行业内外人士的广泛关注,也颇受观众青睐。方... 详细信息

如果从1963年中国内地第一部方言电影《抓壮丁》算起,方言电影在中国经历了半个多世纪的发展。[1]近年来,方言影视作品发展势头愈发强劲,涌现了一批颇具代表性又独有韵味的高质量作品,受到了行业内外人士的广泛关注,也颇受观众青睐。方言不仅丰富了电影的有声语言形式,而且通过影视作品通常展现了鲜明的地域特征,较真实地还原出不同地域的生活面貌,将我国丰富的社会和文化意识传播到世界各地。

关键词：影视表演方言电影方言影视作品业内外人士语言塑造《抓壮丁》有声语言生活面貌

Enhancement of optical characteristic of InGaN/GaN multiple quantum-well structures by self-growing air voids

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Science China(Technological Sciences) 2021年第7期64卷 1583-1588页

作者： DU JinJuan XU ShengRui PENG RuoShi FAN XiaoMeng ZHAO Ying TAO HongChang SU HuaKe NIU MuTong ZHANG JinCheng HAO Yue The National Key Disciplines Laboratory of Wide Band-gap Semiconductor School of MicroelectronicsXidian UniversityXi’an710071China Suzhou Institute of Nano-tech and Nano-Bionics(SINANO) Chinese Academy of SciencesSuzhou215132China

InGaN/GaN multiple quantum-well(MQW) structures with a wavelength range of green were successfully grown on a c-plane GaN template with SiO_2 stripe patterns along the [11-20] and [1-100] directions as a mask. The surface morphologies of both samples were investigated using scanning electron microscopy and demonstrated anisotropic growth characteristics of GaN. The optical characteristics were investigated using Raman spectra and photoluminescence(PL). The InGaN/GaN MQW structure grown on the GaN template with SiO_2 stripes along the [1-100] orientation exhibited less stress and higher PL intensity.Transmission electron microscopy results indicated that portions of MQWs were grown on an inclined semipolar plane, and air voids occurred only when the direction of the mask stripe was along the [1-100] orientation. The enhancement of the optical characteristic was due to the air-void structure and inclined semipolar quantum-well sidewalls.

关键词： InGaN/GaN MQWs SiO_2 mask stripes optical characteristic inclined quantum-well sidewall air voids