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Shrub Communities and Environmental Variables Responsible for Species Distribution Patterns in an Alpine Zone of the Qilian Mountains, Northwest China

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Journal of Mountain Science 2015年第1期12卷 166-176页

作者： HUO hong FENG Qi SU yong-hong Key Laboratory of Ecohydrology of Inland River Basin Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences University of Chinese Academy of Sciences

Understanding the factors that drive variation in species distribution is a central theme of ecological research. Although several studies focused on alpine vegetation, few efforts have been made to identify the environmental factors that are responsible for the variations in species composition and richness of alpine shrublands using numerical methods. In the present study, we investigated vegetation and associated environmental variables from 45 sample plots in the middle Qilian Mountains of the northwestern China to classify different community types and to elucidate the species- environment relationships. We also estimated the relative contributions of topography and site conditions to spatial distribution patterns of the shrub communities using the variation partitioning. The results showed that four shrub community types were identified and striking differences in fioristic composition were found among them. Species composition greatly depended on elevation, slope, shrub cover, soil pH and organic carbon. The important determinants of species richness were soil bulk density and slope. No significant differences in species richness were detected among the community types. Topography and site conditions had almost equal effects on compositional variation. Nonetheless,a large amount of the variation in species composition remained unexplained.

关键词： Alpine shrublands Floristic composition Cluster analysis Canonical Correspondence Analysis(CCA) Variation partitioning Species composition Species richness

Modelling of ultrasonic motor with dead-zone based on Hammerstein model structure

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第1期9卷 58-64页

作者： Xin-liang ZHANG yong-hong TAN Department of Automation School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200030 China Laboratory of Intelligent Systems and Control Engineering Guilin University of Electronic Technology Guilin 541004 China

The ultrasonic motor (USM) possesses heavy nonlinearities which vary with driving conditions and load-dependent characteristics such as the dead-zone. In this paper, an identification method for the rotary travelling-wave type ultrasonic motor (RTWUSM) with dead-zone is proposed based on a modified Hammerstein model structure. The driving voltage contributing effect on the nonlinearities of the RTWUSM was transformed to the change of dynamic parameters against the driving voltage. The dead-zone of the RTWUSM is identified based upon the above transformation. Experiment results showed good agreement be- tween the output of the proposed model and actual measured output.

关键词： Ultrasonic motor (USM) Hammerstein model Dead-zone Nonlinearity Identification

Is transcranial direct current stimulation a potential method for improving response inhibition?

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Neural Regeneration Research 2013年第11期8卷 1048-1054页

作者： yong Hyun Kwon jung Won Kwon Department of Physical Therapy Yeungnam College of Science & Technology Department of Physical Therapy College of Rehabilitation Science Daegu University

Inhibitory control of movement in motor learning requires the ability to suppress an inappropriate action, a skill needed to stop a planned or ongoing motor response in response to changes in a variety of environments. This study used a stop-signal task to determine whether transcranial direct-current stimulation over the pre-supplementary motor area alters the reaction time in motor inhibition. Forty healthy subjects were recruited for this study and were randomly assigned to either the transcranial direct-current stimulation condition or a sham-transcranial direct-current stimulation condition. All subjects consecutively performed the stop-signal task before, during, and after the delivery of anodal transcranial direct-current stimulation over the pre-supplementary motor area （pre-transcranial direct-current stimulation phase, transcranial direct-current stimulation phase, and post-transcranial direct-current stimulation phase）. Compared to the sham condition, there were significant reductions in the stop-signal processing times during and after transcranial direct-current stimulation, and change times were significantly greater in the transcranial direct-current stimulation condition. There was no significant change in go processing-times during or after transcranial direct-current stimulation in either condition. Anodal transcranial direct-current stimulation was feasibly coupled to an interactive improvement in inhibitory control. This coupling led to a decrease in the stop-signal process time required for the appropriate responses between motor execution and inhibition. However, there was no transcranial direct-current stimulation effect on the no-signal reaction time during the stop-signal task. Transcranial direct-current stimulation can adjust certain behaviors, and it could be a useful clinical intervention for patients who have difficulties with response inhibition.

关键词： neural regeneration neurorehabilitation transcranial direct current stimulation pre-supplementarymotor area stop-signal task response inhibition inhibitory control motor learning behavioralmodification grants-supported paper neuroregeneration

Experimental Investigation of the Mg–Zn–Zr Isothermal Section at 400 °C

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Acta Metallurgica Sinica(English Letters) 2019年第4期32卷 426-432页

作者： yong-Peng Liang Shu-hong Liu Kai Xu yong Du State Key Lab of Powder Metallurgy Central South University School of Materials Science and Engineering Central South University

Mg-Zn-Zr series Mg alloys(ZK) are one of the most important commercial Mg alloys due to their good comprehensive mechanical properties. The phase equilibria of the Mg-Zn-Zr system at 400 ℃ covering the overall composition range were investigated by X-ray diffraction and electron probe microanalyses on thirteen ternary alloys. Three ternary compounds, τ_1, τ_2 and τ_3, were detected to be thermodynamically stable at 400 ℃, and their homogeneity range was determined to be Mg_((7-17))Zn_((80-88))Zr_((4-6)), Mg_((15-22))Zn_((66-65))Zr_((9-16)) and Mg_9 Zn_(68)Zr_(23)(in at.%), respectively. Eight three-phase regions and four two-phase regions were observed. The maximum solubility of Mg in Zn_(22) Zr, Zn_(39) Zr_5 and Zn_3 Zr phases was measured to be 0.52, 0.37 and 0.99 at.%, respectively, while the solubility of Zr in MgZn_2 and Mg_2 Zn_3 phases is negligible. The isothermal section of the Mg-Zn-Zr system at 400 ℃ was then constructed based on the present experimental data.

关键词： Mg–Zn–Zr Isothermal section Phase equilibria Ternary compounds

Density Functional Theory Study of Infrared and Ultraviolet Spectra of Urea L-Malic Acid

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Chinese Journal of Chemical Physics 2008年第6期21卷 535-540页

作者： Yan-lan Zhang hong-yan Wang Dong-sheng Jiao yong-hong Hu Institute of Atomic and Molecular Physics Sichuan University Chengdu 610065 China College of Sciences Southwest Jiaotong University Chengdu 610031 China College of Life Science and Pharmaceutical Engineering Nanjing University of Technology Nanjing 210009 China

Urea L-malic acid, a new second order nonlinear optical crystal, was studied using density functional theory （DFT）. PBEPBE/6-31＋G（d,p） method, the optimal method for comparing the results from the several DFT methods, was chosen to study the molecular structure. Infrared and ultraviolet-visible spectra were obtained and compared with experiments. The ultraviolet-visible spectrum was also analyzed by the molecular orbital population. The geometries, and the infrared and ultraviolet-visible spectra in water were studied using DFT methods in combination with the polarized continuum model to predict the perturbations by the solvent effect.

关键词： Urea L-malic acid Density functional theory Molecular structure Infrared spectrum Ultraviolet-visible spectrum

Developmental Characteristics and Cinnamic Acid Resistance of Root Border Cells in Cucumber and Figleaf Gourd Seedlings

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Journal of Integrative Agriculture 2013年第11期12卷 2065-2073页

作者： QIAO yong-xu ZHANG yong-ping ZHANG hong-xin TIAN yong-qiang GAO Li-hong Department of Vegetable Science China Agriculture University/Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops Department of Life Science Tangshan Normal University

Root border cells （RBCs） originate from the root tip epidermis and surround the root apices. In this study, we evaluated the developmental characteristics and the roles of RBCs in protection of root apices of cucumber and ifgleaf gourd seedlings from CA toxicity. The formation of RBCs and the emergence of the root tip occurred almost simultaneously in root apices of cucumber and ifgleaf gourd seedlings. CA ranging from 0 to 0.25 mol L-1 inhibited root elongation and decreased root cell viability in the root tip, moreover the inhibitory effects of CA were more signiifcant in the CA-sensitive cucumber than in the CA-tolerant ifgleaf gourd. Removal of RBCs from root tips led to more severe CA induced inhibition of root elongation and decline in root cell viability. Increasing CA levels and treatment time decreased the relative viability of attached and detached RBCs. CA also induced a thicker mucilage layer surrounding attached RBCs of both species. Additionally, a signiifcantly higher relative cell viability of attached RBCs and thicker mucilage layers were observed in ifgleaf gourd. These results suggest that RBCs play an important role in protecting root tips from CA toxicity.

关键词： cinnamon acid autotoxicity root border cells cell viability

Study Hankel Transforms and Properties of Bessel Function via Entangled State Representation Transformation in Quantum Mechanics

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Communications in Theoretical Physics 2006年第5期45卷 819-824页

作者： FAN hong-Yi WANG yong Department of Material Science and Engineering University of Science and Technology of China Hefei 230026 China Department of Physics Shanghai Jiao Tong University Shanghai 200030 China Department of Special Class for Gifted Young University of Science and Technology of China Hefei 230026 China

In Phys. Lett. A 313 （2003） 343 we have found that the self-recipràcal Hankel transformation （HT） is embodied in quantum mechanics by a transform between two entangled state representations of continuum variables. In this work we study Hankel transforms and properties of Bessel function via entangled state representations＇ transformation in quantum mechanics.

关键词： entangled state representation Hankel transform Bessel function

Effect of Water Vapor on O^(2-) Content in Ironmaking Slag

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Journal of Iron and Steel Research International 2015年第10期22卷 909-915页

作者： Yousef MOHASSAB hong-yong SOHN Department of Metallurgical Engineering University of Utah

In principle, slag basicity can be expressed as the concentration of free oxygen （O^2-） in the slag system. This free oxygen content is equilibrated with different silicate anions in addition to other components in the silicate-based slags. X-ray photon spectroscopy （XPS） and scanning electron microscope equipped with energy dispersive spectrometer （SEM-EDS） were used to investigate the effect of water vapor on the free oxygen content in ironmaking slags. It was found that water in the gas atmosphere plays a significant role in the silicate anion equilibria. Water decreases the amount of free oxygen in the studied slags, with the free oxygen expressed as percentage of the total oxygen decreasing in the order of the following gas mixtures： CO＋CO2 （44%, PH2O = 0 kPa）〉 CO＋CO2＋H2＋H2O （41%, PH2O = 10.13 kPa）〉 H2＋H2O （37%, PH2O = 14.19 kPa）. The content of free oxygen ion affects the distribution of elements such as sulfur, phosphorus, and manganese. In addition, it affects the iron oxide content in the slag as well as the interaction between slag and furnace lining.

关键词： flash ironmaking ironmaking slag slag chemistry basicity water

Effect of Magnetic-Impurity Scattering in Disordered Two-Dimensional Square Lattices Around Half Filling

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Communications in Theoretical Physics 2005年第5X期44卷 929-935页

作者： QIAN Feng YANG yong-hong Department of Physics Southeast University Nanjing 210096 China National Laboratory of Solid State Microstructures Nanjing University Nanjing 210008 China

Abstract Weak-localization effect in the presence of magnetic impurities is studied in disordered two-dimensional tight-binding square lattices around half filling. Both the magnetic and nonmagnetic impurities are assumed to be randomly distributed on small fractions of the sites, while the nonmagnetic impurities have a strong potential yielding a unitary-limit scattering. We derive in details the expressions of diffusive π modes in the retarded-retarded （or advanced- advanced） channel, which result from the existence of particle-hole symmetry. The quantum interference correction to the density of states is calculated. While the magnetic-impurity scattering suppresses the quantum correction from π-mode cooperon, it does not affect the contribution of π-mode diffuson.

关键词： weak localization magnetic impurity density of states two-dimensional lattice