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2003-2020 全部
为您找到包含“National Natural Science Foundation”的内容共1496

ZHANG Junyu,LU Pengfei,LIANG Dan,JIA Baonan

In this paper,Valence Band Anticrossing (VBAC) model is used to investigate band structure of InN1-xBix, GaN1-xBix and AlN1-xBix for the purpose of optimal performance group-III nitride related devices. Obvious reduction in band gap and increase in spin-orbit splitting energy are founded by doping dilute concentration of bismuth in all these III-N material. The band gap of GaN1-xBix and AlN1-xBix show a step change, and this can be explained by the special position relation between of Bi impurity energy level with corresponding host\'s band offsets. We also show how bismuth may be used to form alloys whereby ΔSO>Eg thereby providing a means of suppressing non-radiative CHSH (hot-hole producing) Auger recombination and inter-valence band absorption. For InN1-xBix, bismuth concentration beyond 1.25% is found to be corresponding to the range of ΔSO>Eg and it shows a continuous adjustable bandgap from 0.7 eV to zero. This may make InN1-xBix a potential candidate for near or mid-infrared optoelectronic applications.

2017-11-14

National Natural Science Foundation (Nos. 61675032

National Natural Science Foundation (61675032

State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876, China,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876, China,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876, China,State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 72, Beijing 100876, China

#Physics#

0评论(0 分享(0)

YAN Hui,TANG Weihua

GaFeO3 bulks with x from 0.7 to 1.3 have been fabricated by using classic solid-state route. The structural, optical, and magnetic properties have been investigated systematically. The results of EDX demonstrated that the Fe content can be obtained by adjusting the Fe content in the powders. XRD spectra and FULLPROF profile fitting indicated that GFO bulks belong to the orthorhombic structure with space group Pc21n. Phase separation appeared at the Fe content of x=1.3. Meanwhile, the magnetic property measurements suggested that GaFeO3 is ferromagnetic, and magnetic properties can be enhanced by increasing the Fe content, which is of vital importance for the application of ferromagnetic semiconductors.

2017-12-20

National Natural Science Foundation (No. 11404029

National Natural Science Foundation ( 515722033

School of Science, Beijing University of Posts and Telecommunications, Beijing 100876,School of Science, Beijing University of Posts and Telecommunications, Beijing 100876

#Physics#

0评论(0 分享(0)

ZHAO Yang,LIU Xiangdong

Two commercially available amines, octanediamine (ODM) and m-xylylenediamine (MXDM), were chosen to tough polybenzoxazine resin due to their controllable capability to cause phase separation during the copolymerization with benzoxazine monomers. The toughing behavior and phase separation of the cured resins were investigated using tensile tests and analyses of DMA, SEM, and TGA-GC/MS. The resulting networks showed remarkable toughness without obvious degradation in thermo-mechanical performance. Especially, when ODM/MXDM molar ratio was 1:1, an elongation rate of 10.55% and a breaking strength of 82.67 Mpa, which are 86% and 128% higher than that of the neat benzoxazine resin, respectively, were achieved. These findings open a new way to improve toughness of brittle polybenzoxazine resins.

2017-11-16

National Natural Science Foundation of China (51573167)

National Natural Science Foundation of China (51573167)

National Natural Science Foundation of China (51573167)

National Natural Science Foundation of China (51573167

National Natural Science Foundation of China (51573167

Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018,Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018

#Materials Science#

0评论(0 分享(0)

GE Jin,GAO Feng,XU Guoyan,SONG Xiaolin

This paper designs an integrated control strategy of vehicle yaw and rollover stability to enhance the active safety of highway vehicles in turning scenario. A rollover predictor is built based on Time-To-Rollover index. Modified Linear Quadratic Regulation is used in roll stability control, and Partial-Integral design is used in yaw stability control. With Carsim and MATLAB, simulations of fishhook maneuver and double lane-change test are conducted to evaluate the effectiveness of the control configuration and to validate the control method. The result shows that this controller performs well in maintaining vehicle roll and yaw stability. This study provides a theoretical basis towards a unified chassis control of coupled roll and yaw stability.

2012-05-21

National Natural Science Foundation (No. 51105021

School of Transportation Science and Engineering, Beihang University, Beijing 100191,School of Transportation Science and Engineering, Beihang University, Beijing 100191,School of Transportation Science and Engineering, Beihang University, Beijing 100191,School of Transportation Science and Engineering, Beihang University, Beijing 100191

#Transportation Engineering#

0评论(0 分享(0)

Liang Sha,Guo Xueyi,Feng Ningchuan,Tian Qinghua

Pristine orange peel was chemically modified by introducing sulphur groups with the carbon disulfide treatment in alkaline medium. The presence of sulphur groups on orange peel xanthate were identified by FTIR spectroscopic study. Equilibrium isotherms and kinetics were obtained and the effect of various parameters including equilibrium pH, contact time, temperature and initial ion concentration on adsorption of Pb2+ were studied by batch experiments. The maximum adsorption capacity of orange peel xanthate was 204.50 mg•g-1, which was found to increase by about 150% compared to that of pristine orange peel. The adsorption process can attain equilibrium within 20 min, and kinetics was found to be best-fit pseudo-second order equation. Temperature has little effect on the adsorption capacity of orange peel xanthate. In addition, the adsorption mechanism was proposed.

2009-01-24

National Natural Science Foundation(50774100

School of Metallurgical Science and Engineering,Central South University,School of Metallurgical Science and Engineering,Central South University,School of Metallurgical Science and Engineering,Central South University,School of Metallurgical Science and Engineering,Central South University

#Metallurgical Engineering#

0评论(0 分享(0)

Guo Xueyi,Liang Sha,Tian Qinghua

In this study, sulfured orange peel (MOP) was used as adsorbent to investigate its adsorption behaviors of lead and zinc ions from aqueous solutions. The effects of solution pH, adsorption time and metal ion concentration on adsorption were studied in batch experiments. Both adsorption kinetics of Pb2+ and Zn2+ proceeded rapidly and could be well described by pesudo-second-order equation. The maximum Langmuir adsorption capacities for Pb2+ and Zn2+ removal by MOP were evaluated as 163.93 and 80.06 mg/g, respectively. A binary mixture of Pb2+ and Zn2+ was studied by using a packed column, suggesting that effective mutual separation and pre-concentration of Pb2+ away from Zn2+ using MOP could be satisfactory achieved. The results indicate that sulfured orange peel could be employed as an effective low-cost adsorbent for adsorption and separation of Pb2+ and Zn2+ from wastewater.

2010-12-14

National Natural Science Foundation(50774100

Central South University,Central South University,Central South University

#Metallurgical Engineering#

0评论(0 分享(0)

zhenglong Wang,yuxian Xia

Most fungi have two different conidiation patterns: normal conidiation and microcycle conidiation under different culture conditions, including the nutrients in the medium. However, the mechanism of conidiation pattern shift response to culture conditions is poorly understood. In this study, Metarhizium acridum conducting microcycle conidiation on sucrose yeast extract agar medium (SYA) shifted to normal conidiation when supplemented with sucrose, nitrate, or phosphate. The M. acridum transcripts on SYA, SYA supplemented with sucrose, nitrate or phosphate, and 1/4SDAY were sequenced by Solexa/Illumina deep-sequencing technology. The results showed that 6,931 genes involved in 243 biochemical pathways were either up- or downregulated in response to different nutrients. Comparative analysis demonstrated that 1,859 genes specifically upregulated at the microcycle conidiation stage were selected. One hundred and twelve, 292, or 216 genes might be associated with microcycle conidiation after adding sucrose, nitrate, or phosphates to SYA medium, respectively. Four hundred and seventy genes were specifically upregulated and might be related to normal conidiation. KEGG pathway analysis indicated that these genes were mainly associated with the cell cycle, cell proliferation, metabolism, protein transport and signal transduction, and the mitogen-activated protein kinase signaling and catabolism pathway. Changing sucrose, nitrate or phosphate, led to a shift between microcycle and normal conidiation by perturbing the cell cycle and metabolism of M. acridum. This research provides essential information about the molecular mechanism of conidiation pattern shift induced by single nutrients.

2013-05-01

National Natural Science Foundation(No. 30771446

Genetic Engineering Research Center, College of Life Sciences, Chongqing University, Chongqing 400030,Genetic Engineering Research Center, College of Life Sciences, Chongqing University, Chongqing

#Biology#

0评论(0 分享(0)

Lu Yinglin,Wei Guang-Mei

In this paper, a negative Gardner-KP equation is under investigation, whose Painlev'{e} analysis shows its non-integrability. Via the truncated Painlev'{e} expansion, an auto-B"{a}cklund transformation is presented and analytical solution is given. The bell-polynomial approach is used to obtain N-soliton solution for this non-integrable equation. Moreover, SAR image simulation of internal solitary wave propagation is provided, which shows prospective agreement with the observed SAR image.

2015-10-12

National Natural Science Foundation (No. 61072145

LMIB and School of Mathematics and System Sciences, Beihang University, Beijing 100191,LMIB and School of Mathematics and System Sciences, Beihang University, Beijing 100191

#Mathematics#

0评论(0 分享(0)

LIANG Jinhua,PENG Yuejian

Given a positive integer $n$ and an $r$-uniform hypergraph $F$, the {\em Tur\'an number} $ex(n,F)$ is the maximum number of edges in an $F$-free $r$-uniform hypergraph on $n$ vertices. The {\em Tur\'{a}n density} of $F$ is defined as $\pi(F)=\lim_{n\rightarrow\infty} { ex(n,F) \over {n \choose r } }.$ The {\em Lagrangian density } of $F$ is$\pi_{\lambda}(F)=\sup \{r! \lambda(G):G\;is\;F\text{-}free\}.$ Sidorenko observed that $\pi(F)\le \pi_{\lambda}(F)$, and Pikhurko observed that $\pi(F)=\pi_{\lambda}(F)$ if every pair of vertices in $F$ is contained in an edge of $F$. Recently, Lagrangian densities of hypergraphs and Tur\'{a}n numbers of their extensions have been studied actively. For example, in the paper `A hypergraph Tur\'an theorem via Lagrangians of intersectingfamilies, {\it J. Combin. Theory Ser. A} {\bf 120} (2013), 2020--2038.', Hefetz and Keevash studied the Lagrangian densitiy of the $3$-uniform graph spanned by $\{123, 456\}$ and the Tur\'{a}n number of its extension.In this paper, we show that the Lagrangian density of the $3$-uniform graph spanned by $\{123,234,456\}$ achieves only on $K_5^3$ . Applying it, we get the Tur\'{a}n number of its extension, and show that the unique extremal hypergraph is the balanced complete $5$-partite $3$-uniform hypergraph on $n$ vertices.

2018-05-04

National Natural Science Foundation (11671124

College of Mathematics and Econometrics, Hunan University, Changsha 410082,College of Mathematics and Econometrics, Hunan University, Changsha 410082

#Mathematics#

0评论(0 分享(0)

Jia Peng,Jia Peng,Ma Yanqi,Du Guozhen

Community structure is the focus of community ecology. Comparing the relative contribution of environmental and spatial variables on species composition is essential to understand the process of community assembly. In this study, we explored that the effects of regional spatial scale, local spatial scale and environmental variables on the species composition of meadow and steppe on the Qinghai-Tibet plateau. The results showed that environmental, regional and local spatial scale variables had significant effects on meadows and their functional groups, and the explanation of local spatial variables was relatively high. And the regional spatial scale variable had a significant effect on the species composition of the steppes and their functional groups. In addition, the total explanation of environmental and spatial variables accounted the highest for the legume groups species composition at the sample sites. And the sum of the explanation of impact factors on meadow functional groups was not equal to the effect on meadow species composition, and the same phenomenon in the steppe. The results demonstrated that environmental and spatial variables and the division of functional groups could fully detect and explain the species composition of community on the Qinghai-Tibetan Plateau.

2018-11-15

National Natural Science Foundation(41430749

State Key Laboratory of Grassland and Agro-Ecosystems,School of Life Science, Lanzhou University,730000,State Key Laboratory of Grassland and Agro-Ecosystems,School of Life Science, Lanzhou University,730000,State Key Laboratory of Grassland and Agro-Ecosystems,School of Life Science, Lanzhou University,730000,State Key Laboratory of Grassland and Agro-Ecosystems,School of Life Science, Lanzhou University,730000

#Biology#

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