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Effects of nitrogen addition on the soil detachment in the typical grasslands of the Loess Plateau

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Journal of Mountain Science 2022年第12期19卷 3503-3516页

作者： li pan-pan WANG Bing YANG Yan-fen liU Guo-bin State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationNorthwest A&F UniversityYangling 712100China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China

Nitrogen deposition will alleviate the nitrogen limitation in terrestrial ecosystems and greatly affect vegetation growth,thereby soil *** is important to clarify the effects of nitrogen addition to the plant roots and soil properties on the soil erosion process.A nitrogen addition experiment was conducted in the grassland dominated by Bothriochloa ischaemum(linn.)Keng(BI),which has received 0,2.5,5,and 10 g N m^(-2) yr^(-1)(N_(0),N_(2.5),N_(5)and N_(10),respectively)for three consecutive ***,a total of 150 undisturbed soil samples were collected(including bare soil control)and subjected to flowing water to test their soil detachment capacities under six shear stress levels(10.2 Pa to 29.9 Pa).Three-year nitrogen addition increased the soil bulk density,soil cohesion and nitrate nitrogen while decreasing the saturated hydraulic conductivity,soil water-stable aggregates,soil organic carbon,total nitrogen and ammonium *** root mass density and root diameter decreased with nitrogen *** the root length,surface area and volume density of the N_(0) and N_(5) treatments were larger than those of the other treatments,while the plant roots were significantly inhibited by N_(10).Additionally,the soil detachment capacity(D_(c))and rill erodibility(K_(r))of the N_(0) and N_(5) treatments were significantly less than those of the N_(2.5) and N_(10)treatments,of which the Dc(0.020 kg m^(-2) s^(-1))of the N_(0) treatment was 69.0%,24.3%and 66.8%less than that of the N_(2.5),N_(5) and N_(10) treatments,*** Kr of the N_(0) treatment was 0.0012 s m^(-1),which was 72.1%,25.0%and 70.0%less than that of the *** study implies that an increase in nitrogen addition likely exacerbates soil erosion in the early(approximately 2.5 g N m^(-2) yr^(-1))and late phases(more than 10 g N m^(-2) yr^(-1)).However,when the nitrogen addition rate is approximately 5 g m^(-2) yr^(-1),soil erosion may be inhibited because of the responses of the plant ro

关键词： Nitrogen deposition Root traits Soil properties Soil detachment Grassland Loess Plateau

A Vanishing Theorem on a Class of Hartogs Domain

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Acta Mathematica Sinica,English Series 2023年第1期39卷 1-12页

作者： Cheng Chen ZHONG An WANG li Shuang pan School of Mathematical Sciences Peking UniversityBeijing 100871P.R.China School of Mathematical Sciences Capital Normal UniversityBeijing 100048P.R.China Science College Shijiazhuang UniversityHebei 050035P.R.China

In this paper,we consider the d-boundedness of the Bergman metric and a vanishing theorem of L2-cohomology on a class of Hartogs domain,whose base domain is the production of two irreducible bounded symmetric domains ... 详细信息

关键词： d-bounded vanishing theorem Bergman metric

Ti-Si-N films prepared by magnetron sputtering

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Rare Metals 2012年第2期31卷 183-188页

作者： pan, li Bai, Yizhen Zhang, Dong Wang, Jian Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education School of Physics and Optoelectronic Technology Dalian University of Technology Dalian 116024. China PLA No. 5311 Factory Nanjing 211100 China

A film growth mechanism, expressed in terms of depositing hard films onto the soft substrate, was proposed. Multicomponent thin films of Ti-Si-N were deposited onto Al substrate with a double-target magnetron sputtering system in an Ar-N 2 gas mixture. The Ti-Si-N films were investigated by characterization techniques such as X-ray diffraction (XRD), atomic force microscope (AFM), electron probe microanalyzer (EPMA), scratch test and nanoindentation. The as-deposited films have a good adhesion to Al substrate and appear with smooth and lustrous surface. The films show nanocomposite structure with nano TiN grains embedded in an amorphous SiN x matrix. The maximum hardness of the films was achieved as high as 27 GPa. The influences of the N 2 flow rate and substrate temperature on the growth rate and quality of the films were also discussed. For all samples, the Ar flow rate was maintained constant at 10 ml min 1 , while the flow rate of N 2 was varied to analyze the structural changes related to chemical composition and friction coefficient. The low temperature in the deposited Ti-Si-N films favors the formation of crystalline TiN, and it leads to a lower hardness at low N 2 flow rate. At the same time, the thin films deposited are all crystallized well and bonded firmly to Al substrate, with smooth and lustrous appearance and high hardness provided. The results indicate that magnetron sputtering is a promising method to deposit hard films onto soft substrate.

关键词： Ti-Si-N films nanocomposite nanoindentation hardness

Synthesis of High Performance Cyclic Olefin Polymers Using Highly Efficient WCl6-based Catalyst System

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Chinese Journal of Polymer Science 2018年第2期36卷 214-221页

作者： Yi-Ran Zhang Ji-Xing Yang li pan Yue-Sheng li Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin 300350China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China

Cyclic olefin polymers（COPs） with high glass transition temperature, high transparency（higher than 80%） in the visible light range, excellent thermal stability and outstanding mechanical properties have been synthesized by effective ring opening metathesis polymerization（ROMP） of exo-1,4,4 a,9,9 a,10-hexahydro-9,10（1′,2′）-benzeno-l,4-methanoanthracene（HBM） and dicyclopentadiene（DCPD） or norbornene（NBE） using WCl6/i-Bu3Al/ethanol/1-hexene catalyst system, followed by hydrogenation of double bonds. 1-Hexene acted as a molecular weight controller in the polymerization reaction, tuning the number-average molecular weight（Mn） of P-HBM from 5.8 × 10^4 to 41.1 × 10^4. The monomer composition and thermal properties of the copolymers were characterized by nuclear magnetic resonance（NMR）, differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）. The saturated polymers exhibited high decomposition temperatures（Td） around 340 ℃ and glass transition temperatures（Tg） in the range from 117.5 ℃ to 219.7 ℃. What is more, tensile tests indicated that the mechanical properties of the COPs could be effectively tuned in a wide range by introducing varying amount of small cyclic olefin such as DCPD or NBE.

关键词： Ring-opening metathesis polymerization Hydrogenation Cyclic olefin polymers Glass transition temperature Mechanical properties

Rotational motion of polyanion versus volume effect associated with ionic conductivity of several solid electrolytes

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Rare Metals 2018年第6期37卷 497-503页

作者： Qian Zhao li pan Yuan-Ji li li-Quan Chen Si-Qi Shi Materials Genome Institute Shanghai University School of Materials Science and Engineering Shanghai University Qianweichang College Shanghai University Institute of Physics Chinese Academy of Sciences

Volume effect has been extensively investigated in several families of solid electrolytes, i.e., expanding the skeleton lattice by bigger-size substitution favors the ionic conduction. However, this effect is not applicable in α-li2SO4 and α-Na3PO4 based inorganic ionic plastic crystal electrolytes, a unique family of solid electrolytes. Here, it is proposed that the underlying rotational motion effect of polyanion, which is actually inhibited by the substitution of bigger-size polyanion in single-phase solid solution region and causes the unexpected lowering of the ionic conductivity instead, should need the more consideration. Furthermore, through utilizing the rotational motion effect of polyanion, it is given that a new explanation of the ionic conductivities of li10MP2S12 （M = Si, Ge, Se） electrolytes deviating from the volume effect. These results inspire new vision of rationalization of the high-performance solid electrolytes by tuning the rotational motion effect of polyanion.

关键词： Volume effect Rotational motion ofpolyanion Ionic conductivity Inorganic plastic crystalelectrolyte

Detecting the Bull’s-Eye Effect in Seismic Inversion Low-Frequency Models Using the Optimized YOLOv7 Model

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Applied Geophysics 2024年第4期21卷 766-776,880,881页

作者： Jun li Jia-bing Meng pan li Institute of Disaster Prevention Sanhe 065201China Hebei Province University Smart Emergency Application Technology Research and Development Center Sanhe 065201China

To detect bull’s-eye anomalies in low-frequency seismic inversion models,the study proposed an advanced method using an optimized you only look once version 7(YOLOv7)*** model is enhanced by integrating advanced modules,including the bidirectional feature pyramid network(BiFPN),weighted intersection-over-union(wise-IoU),efficient channel attention(ECA),and atrous spatial pyramid pooling(ASPP).BiFPN facilitates robust feature extraction by enabling bidirectional information fl ow across network scales,which enhances the ability of the model to capture complex patterns in seismic inversion ***-IoU improves the precision and fi neness of reservoir feature localization through its weighted approach to ***,ECA optimizes interactions between channels,which promotes eff ective information exchange and enhances the overall response of the model to subtle inversion ***,the ASPP module strategically addresses spatial dependencies at multiple scales,which further enhances the ability of the model to identify complex reservoir *** synergistically integrating these advanced modules,the proposed model not only demonstrates superior performance in detecting bull’s-eye anomalies but also marks a pioneering step in utilizing cutting-edge deep learning technologies to enhance the accuracy and reliability of seismic reservoir prediction in oil and gas *** results meet scientifi c literature standards and provide new perspectives on methodology,which makes signifi cant contributions to ongoing eff orts to refi ne accurate and effi cient prediction models for oil and gas exploration.

关键词： bull’s-eye YOLO bidirectional feature pyramid network weighted intersection-over-union atrous spatial pyramid pooling

Effect of Functional Chemical Admixtures on the Performance of Cement Asphalt Mortar Used in Ballastless Track

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Journal of Wuhan University of Technology(Materials Science) 2015年第5期30卷 995-1000页

作者：蒋金洋 SHE Wei li Wei pan li Jiangsu Key Laboratory for Construction Materials Southeast University Jiangsu Institute of Building Science Co.LTD

Chemical admixtures are of paramount importance to the performance of modern cement based composites. In this paper, we performed a series of tests to investigate the effects of chemical admixtures on the cement asphalt mortar(CA mortar), i e, compressive strength, frost resistance, permeability, fatigue resistance, pore structure and microstructure. In particular, two types of chemical admixtures were tested, i e, defoamer(tributyl phosphate(TBP)) and polycarboxylate superplasticizer(PS). The results indicate that the addition of TBP and PS eliminates big bubbles and promotes small non-connected pores forming in matrix. Besides, an optimum dosage of TBP and PS may be determined with respect to the frost resistance, permeability and fatigue resistance of CA mortar. Further elaborative discussions are presented as well as experimental evidences from mercury intrusion porosimetry, scanning electron microscopy and energy dispersive spectroscopy.

关键词： cement asphalt mortar chemical admixture frost resistance fatigue resistance pore structure microstructure

Effect of Olefin-based Compatibilizers on the Formation of Cocontinuous Structure in Immiscible HDPE/iPP Blends

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Chinese Journal of Polymer Science 2020年第11期38卷 1248-1257,I0008页

作者： Fei Yang li pan Hui-Zhen Du Zhe Ma Yue-Sheng li Tianjin Key Laboratory of Composite and Functional Materials and School of Materials Science and EngineeringTianjin UniversityTianjin 300072China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China

In this work,the formation of cocontinuous structure in immiscible high density polyethylene/isotactic polypropylene(HDPE/iPP)blends was investigated for various olefin-based compatibilizers of distinct molecular architectures,including ternary random copolymer EPDM,olefin block copolymer(OBC),polypropylene-based OBC(PP-OBC),ethylene/a-olefin copolymer(POE),bottlebrush polymer poly(1-dodecene),and comb-like poly(propylene-co-high a-olefin)(PPO).The scanning electron microscopy results show that after adding OBC,PP-OBC,and POE copolymers,the finer droplet-in-matrix morphologies were obtained in 70/30 HDPE/iPP ***,for 70/30 HDPE/iPP blend with just 5 wt%of PPO copolymers,the phase inversion from droplet-in-matrix to cocontinuous morphology can be *** was proposed that the development of cocontinuous morphology contained the following steps:(1)in terfacial saturati on of compatibilizers and droplet deformation,(2)droplet-droplet coalesce nee,(3)continuity development,and(4)the formation of dual-phase con *** the diverse copolymers studied in this work,PPO copolymer can be easily removed out of the interface during droplet coalescence and stabilize the curvature of minor fiber phase,facilitating the formation of cocontinuous *** contrast,other olefin-based compatibilizers(EPDM,OBC,PP-OBC,and POE)exhibit the distinct steric repulsion effect to prohibit droplet ***,the cocontinous interval varies with the compatibilizer ***,after adding 10 wt%of PPO copolymers,the cocontinuous interval was greatly broadened from HDPE/iPP range of 45/55-60/40 to that of 40/60-70/30.

关键词： Compatibilizer Polyolefin Cocontinuous structure Droplet-coalescence Phase inversion

Topsoil organic carbon mineralization and CO_2 evolution of three paddy soils from South China and the temperature dependence

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Journal of Environmental Sciences 2007年第3期19卷 319-326页

作者： ZHANG Xu-hui li lian-qing pan Gen-xing Institute of Resources Ecosystem and Environment of Agriculture Nanjing Agricultural University Nanjing 210095 China.

Carbon mineralization and its response to climatic warming have been receiving global attention for the last decade. Although the virtual influence of temperature effect is still in great debate, little is known on the mineralization of organic carbon （SOC） of paddy soils of China under warming. SOC mineralization of three major types of China＇s paddy soils is studied through laboratory incubation for 114 d under soil moisture regime of 70% water holding capacity at 20℃ and 25℃ respectively. The carbon that mineralized as CO2 evolved was measured every day in the first 32 d and every two days in the following days. Carbon mineralized during the 114 d incubation ranged from 3.51 to 9.22 mg CO2-C/gC at 20℃ and from 4.24 to 11.35 mg CO2-C/gC at 25℃ respectively; and a mineralizable C pool in the range of 0.24 to 0.59 gC/kg, varying with different soils. The whole course of C mineralization in the 114 d incubation could be divided into three stages of varying rates, representing the three subpools of the total mineralizable C： very actively mineralized C at 1-23 d, actively tnineralized C at 24--74 d and a slowly mineralized pool with low and more or less stabilized C mineralization rate at 75-114 d. The calculated Q10 values ranged from 1.0 to 2.4, varying with the soil types and N status. Neither the total SOC pool nor the labile C pool could account for the total mineralization potential of the soils studied, despite a well correlation of labile C with the shortly and actively mineralized C, which were shown in sensitive response to soil warming. However, the portion of microbial C pool and the soil C/N ratio controlled the C mineralization and the temperature dependence. Therefore, C sequestration may not result in an increase of C mineralization proportionally. The relative control of C bioavailability and microbial metabolic activity on C mineralization with respect to stabilization of sequestered C in the paddy soils of China is to be further studied.

关键词： C mineralization carbon pool laboratory incubation paddy soil soil warming