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Effect of Fe_2O_3/SiO_2 ratio on maghemite-silica particulate nanocomposites

Journal of Central South University 2013年第11期20卷 2954-2959页

作者： ang Bee Chin YAACOB Iskandar Idris NURDIN Irwan Department of Mechanical University of Malaya Department of Manufacturing and Materials Engineering Kulliyyah of EngineeringInternational Islamic University Malaysia

Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 ℃for 3 d. A variety of mass ratios of Fe2O3/SiO2 was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 20 from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO2 amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites （360-390 m^2/g）. This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.

关键词： maghemite nanoparticles nanocomposites sol-gel silica

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A Nonclassical lIl for Geometrically Weighted Series in Banach Space

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Acta Mathematica Sinica,English Series 2013年第7期29卷 1413-1420页

作者： Ke ang FU Xiao Rong Yang Wei hUang School of Statistics and Mathematics Zhejiang Gongshang University Department of Mathematics Zhejiang University

We consider efficient methods for the recovery of block sparse signals from underdetermined system of linear equations. We show that if the measurement matrix satisfies the block RIP with δ2s 〈 0.4931, then every block s-sparse signal can be recovered through the proposed mixed l2/ll-minimization approach in the noiseless case and is stably recovered in the presence of noise and mismodeling error. This improves the result of Eldar and Mishali （in IEEE Trans. Inform. Theory 55： 5302-5316, 2009）. We also give another sufficient condition on block RIP for such recovery method： 58 〈 0.307.

关键词： Banach space geometrically weighted series nonclassical law of the iterated logarithm

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Phenotypic nutrient up-take differences in an alley cropping system in semi-arid Machakos, Kenya

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Journal of Environmental Sciences 2001年第2期13卷 164-169页

作者： D.N. Mungai C.l.Coulson C.J. Stigter J.K. Ng’ang’a D.N.Mugendi Department of Geography University of NairobiNairdbiKenya Department of Botany University of NairobiNairobiKenya Department of Enviromnental Sciences Graduate School of Productian EcologyWageningen UniversityDuivendaal 26701 APThe Netherlands Department of Meteorology University of NairobiNairobiKenya Kenya Forestry Research Instiute(KEFRI NairobiKanya)

Alley cropping of Cassia siamea and maize was studied in semi arid Kenya for soil fertility improvement. Katumani composite maize was planted except in the short rains of 1988 (SR88) when a hybrid variety was sown. Therefore the grain yield per row increased differently in the alley cropped maize (CM). Sole maize (SM) and CM yields were higher in SR88 than in the long rains of 1988 (lR88) by 62% and 38%, while yields from the same treatments in lR89 were only 21% and 45% of those in SR88 These differences in relative maize yields are attributed to differences between the two maize varieties in competition under nutrient stress conditions.

关键词： alley cropping Cassia siamea maize nutrients maize yield semi arid condition soil moisture Kenya

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Precise large Deviations for Sums of Claim-size Vectors in a Two-dimensional Size-dependent Renewal Risk Model

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Acta Mathematicae Applicatae Sinica 2021年第3期37卷 539-547页

作者： Ke-ang FU Xin-mei ShEN hui-jie lI Department of Statistics Zhejiang University City CollegeHangzhou 310015China School of Mathematical Sciences Dalian University of TechnologyDalian 116024China Shunfeng Express Shanghai 200120China

Consider a two-dimensional renewal risk model,in which the claim sizes{Xk;k≥1}form a sequence of *** of a non-negative random vector whose two components are *** that the claim sizes and inter-arrival times form a sequence of *** pairs,with each pair obeying a dependence structure via the conditional distribution of the inter-arrival time given the subsequent claim size being *** a precise large-deviation formula of the aggregate amount of claims is obtained.

关键词： consistent variation extended regular variation large deviations size-dependence two-dimensional risk model

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Experimental study on dynamic mechanism of vortex evolution in a turbulent boundary layer of low Reynolds number

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Journal of hydrodynamics 2020年第5期32卷 807-819页

作者： Yan-ang Guo Xiang-rui Dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key laboratory of Multiphase Flow and heat Transfer in Shanghai Power Engineering Shanghai 200093China

The dynamic mechanism of the vortex generation and evolution process in a fully developed turbulent boundary layer with Reθ=97-194 is experimentally *** this study,a moving single-frame and long-exposure(MSFlE)imaging method and a moving particle image velocimetry/particle tracing velocimetry(M-PIV/PTV)are designed and implemented for measuring the temporal and spatial evolution of vortex cores in both qualitative and quantitative ways,*** the other hand,the liutex vector,which is a new mathematical definition and identification of the vortex core proposed by liu’s group,is first applied in the experiment for the structural visualization and quantitative analysis of the local fluid *** results show that an intuitional process of vortex evolution can be clearly observed by tracking the vortex using MSFlE and verify that the roll-up of the shear layer induced by shear instability is the origin of vortex formation in ***,a quantitative investigation in terms of the critical vortex core boundary(size)and its accurate rotation strength is carried out based on the liutex vector field analysis by M-PIV/*** to statistics of the relation between vortex core size and the rotation strength during the whole process,the physical mechanism of vortex generation and evolution in a turbulent boundary layer of low Reynolds number can be summarized as a four-dominant-state course consisting of the“synchronous linear segment(Sl)-absolute enhancement segment(AE)-absolute diffusion segment(AD)-skewing dissipation segment(SD)”.

关键词： Turbulent boundary layer high-and low-speed fluid vortex generation moving single-frame and long-exposure moving particle image velocimetry/particle tracing velocimetry liutex vector

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Commentary on “Psychiatry and Cinema: What can We learn from the Magical Screen?”

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上海精神医学 2017年第5期29卷 314-315页

作者： Qiuqing ang hesure International Inc Texas USA

Filmmakers describe mental illnesses in different ways and show morbid mental phenomena using different film vocabularies. This process is almost as long as the film's course. After all, film is about ideology. Metaphysically, there cannot be a lack of emotion and spirit, and the emotion towards morbidity and spiritual expression cannot be missing. It is the same as all the relationships between narrators and the ones being narrated, the one who was narrated in the narrator's mouth reflects the one being narrated himself and also brands the narrator's own shadow. This is like the relationship of a mirror and the person who looks into the mirror. The image in the mirror reflects the person who looks into the mirror and shows many characteristics of the mirror such as diopter and focalization. however, the mirror does not know about it; the narrator might not know about it as well. Since the objects described are themselves as well as their own way of thinking and the expression of their emotional state, seeing the psychotic patient described by a filmmaker one can catch a glimpse of the filmmaker himself and the cultural systems and ideologies that are embedded in them. This point will always be the source that is most interesting and most worthwhile to ruminate over when considering this topic.

关键词： Filmmakers describe mental illnesses in different ways and show morbid mental phenomena using different film vocabularies

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Effect of Fe concentration on the nonlinear refraction and reverse saturable absorption in ferroelectric X-cut liNbO_3 crystal

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Chinese Optics letters 2015年第7期13卷 92-95页

作者： h.l.Saadon laser Applications and Optical Materials Group Department of Physics College of ScienceUniversity of Basrah

In this letter, the effects of the iron （Fe） dopant concentration on the nonlinear optical properties of iron-doped ferroelectric X-cut liNbO3 crystals plates are studied by using the Z-scan technique with a cw laser at the wave- length of 532 nm. The amount of iron in the compound is varied from 0 to 0.15 mol%. Measurements of nonlinear refractive index n2 and the nonlinear absorption coefficient β are determined. The sign of the nonlinear refractive index is found to be negative and the magnitude is on the order of 10-s cm2/W. This nonlinear effect increases as the concentration increases from 0 to 0.15 mol%. A good linear relationship is obtained between nonlinear refractive index, nonlinear absorption coefficient, and concentration.

关键词： Fe Effect of Fe concentration on the nonlinear refraction and reverse saturable absorption in ferroelectric X-cut liNbO3 crystal

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Experimental Study on the Effect of Increased Downstroke Duration for an FWAV with Morphing-coupled Wing Flapping Configuration

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Journal of Bionic Engineering 2024年第1期21卷 192-208页

作者： ang Chen Bifeng Song ZhiheWang Kang liu Dong Xue Xiaojun Yang School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China harbin Institute of Technology Shenzhen 518055China

This paper is based on a previously developed bio-inspired Flapping Wing Aerial Vehicle(FWAV),RoboFalcon,which can fly with a morphing-coupled flapping *** this paper,a simple flapping stroke control system based on hall effect sensors is designed and applied,which is capable of assigning different up-and down-stroke speeds for the RoboFalcon platform to achieve an adjustable downstroke *** aerodynamic and power characteristics of the morphing-coupled flapping pattern and the conventional flapping pattern with varying downstroke ratios are measured through a wind tunnel experiment,and the corresponding aerodynamic models are developed and analyzed by the nonlinear least squares *** relatively low power consumption of the slow-downstroke mode of this vehicle is verified through outdoor flight *** results of wind tunnel experiments and flight tests indicate that increased downstroke duration can improve aerodynamic and power performance for the RoboFalcon platform.

关键词： Flapping wing aerial vehicle(FWAV) Downstroke ratio Bio-inspired design Morphing-coupled flapping

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Ethylene Response Factor TERF1 Enhances Glucose Sensitivity in Tobacco through Activating the Expression of Sugar-related Genes

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Journal of Integrative Plant Biology 2009年第2期51卷 184-193页

作者： ang li Zhijin Zhang Xue-Chen Wang Rongfeng huang National laboratory of Plant Physiology and Biochemistry College of Biological Sciences China Agricultural University Beijing 100094 China Biotechnology Research Institute the Chinese Academy of Agricultural Sciences Beijing 100081 China National Key Facility of Crop Gene Resources and Genetic Improvement Beijing 100081 China National Center for Plant Gene Research (Beijing) Beijing 100081 China

Ethylene response factor （ERF） proteins are important plant-specific transcription factors. Increasing evidence shows that ERF proteins regulate plant pathogen resistance, abiotic stress response and plant development through interaction with different stress responsive pathways. Previously, we revealed that overexpression of TERF1 in tobacco activates a cluster gene expression through interacting with GCC box and dehydration responsive element （DRE）, resulting in enhanced sensitivity to abscisic acid （ABA） and tolerance to drought, and dark green leaves of mature plants, indicating that TERF1 participates in the integration of ethylene and osmotic responses. here we further report that overexpression of TERF1 confers sugar response in tobacco. Analysis of the novel isolated tomato TERF1 promoter provides information indicating that there are many cis-acting elements, including sugar responsive elements （SURE） and W box, suggesting that TERF1 might be sugar inducible. This prediction is confirmed by results of reverse transcription-polymerase chain reaction amplification, indicating that transcripts of TERF1 are accumulated in tomato seedlings after application of glucose. Further investigation indicates that the expression of TERF1 in tobacco enhances sensitivity to glucose during seed germination, root and seedling development, showing a decrease of the fresh weight and root elongation under glucose treatment. Detailed investigations provide evidence that TERF1 interacts with the sugar responsive cis-acting element SURE and activates the expression of sugar response genes, establishing the transcriptional regulation of TERF1 in sugar response. Therefore, our results deepen our understanding of the glucose response mediated by the ERF protein TERF1 in tobacco.

关键词： Ethylene response factor protein TERF1 glucose sugar responsive gene tobacco

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Multi-affine registration using local polynomial expansion

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Journal of Zhejiang University-Science C(Computers and Electronics) 2010年第7期11卷 495-503页

作者： Yuan-jun W'ang Guimar FARNEBACK Carl-Fredrik WESTIN Digital Medical Research Center Shanghai Medical School Fudan University Shanghai 200032 China lab of Mathematics in Imaging Brigham and Women's Hospital Harvard Medical School Boston 02115 MA USA

In this paper, we present a non-linear (multi-affine) registration algorithm based on a local polynomial expansion model. We generalize previous work using a quadratic polynomial expansion model. local affine models are estimated using this generalized model analytically and iteratively, and combined to a deformable registration algorithm. Experiments show that the affine parameter calculations derived from this quadratic model are more accurate than using a linear model. Experiments further indicate that the multi-affine deformable registration method can handle complex non-linear deformation fields necessary for deformable registration, and a faster convergent rate is verified from our comparison experiment.

关键词： Deformable registration Polynomial expansion least squares Multi-affine Normalized convolution

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