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Chemical interactions between silver nanoparticles and thiols: a comparison of mercaptohexanol against cysteine

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Science China Chemistry 2014年第9期57卷 1199-1210页

作者： TOH Her Shuang BATCHeLOR-MCAULeY Christopher TSCHULIK Kristina COMPTON Richard g Department of Chemistry Physical and Theoretical Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxford OX1 3QZUK

The interaction between citrate capped silver nanoparticles and two different thiols, mercaptohexanol （MH） and cysteine, was investigated. The thiols interacted with silver nanoparticles in a significantly contrasting manner. With MH, a sparingly soluble silver（1） thiolate complex AgSRm （Rm = -（CH2）6OH） was formed on the silver nanoparticle surface. Cyclic voltammograms and UV-vis spectra were used to infer that the AgSRm complex on the nanoparticle surface undergoes a phase transition to give a mixture of AgSRm and Ag2S-like complexes. In contrast, when silver nanoparticles were exposed to cysteine, the citrate cap- ping agent on the silver nanoparticles was replaced by cysteine to give cysteine capped nanoparticles. As cysteine capped nanoparticles form, the electrochemical data displayed a decrease in oxidative peak charge but the UV-vis spectra showed a constant signal. Therefore, cysteine capped nanoparticles were suggested to have either inactivated the silver surface or else pro- moted detachment from the electrode surface.

关键词： silver nanoparticles interaction thiol

Hormonal Imbalance in Polycystic Ovarian Syndrome (Pcos) in Teaching Hospitals in ekiti State, Nigeria

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Open Journal of Obstetrics and gynecology 2018年第13期8卷 1456-1464页

作者： O. g. Oyebanji M. F. Asaolu e. O. Amonimo Department of Biochemistry Ekiti State University Ado Ekiti Nigeria

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders of women at reproductive age and the major cause of anovulatory infertility. The aim of this study is to determine hormonal imbalance in women with PCOS in teaching hospitals in ekiti State, Nigeria. Samples of 110 females (50 freshly diagnosed PCOS subjects and 60 healthy subjects) between the ages of 25 - 45 years old were collected from ekiti State University Teaching Hospital, Ado ekiti and Federal Teaching Hospital, Ido ekiti, ekiti State, Nigeria. Serum Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), Total Testosterone, Prolactin, Progesterone, estradiol and Insulin were evaluated in subjects’ blood sample using enzyme-Linked Immunosorbent assay (eLISA). Results obtained were subjected to statistical analysis (p e PCOS subjects showed significant increase (p e concentrations of Total Testosterone, Insulin, LH, estradiol and LH/FSH ratio, while FSH and progesterone concentrations showed significant decrease (p e healthy control group. However, there was no significant difference in the concentration of Prolactin when compared with the healthy control group. Also, the PCOS subjects’ age at Menarche was significantly decreased (p > 0.05) when compared with the healthy control group. Hormonal values obtained in this study indicates hormonal imbalance in PCOS. Further investigation into novel helpful markers is required as it might help in achieving the therapeutical target in PCOS management research.

关键词： Polycystic Ovarian Syndrome Insulin Testosterone Progesterone estradiol Luteinizing Hormone

Application of site-specific biomass models to quantify spatial distribution of stocks and historical emissions from deforestation in a tropical forest ecosystem

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Journal of Forestry Research 2018年第1期29卷 205-213页

作者： Cedric A.goussanou Sabin guendehou Achille e.Assogbadjo Brice Sinsin Laboratory of Applied ecology Faculty of Agronomic Sciences University of Abomey-Calavi 01 PO Box 526 Cotonou Republic of Benin Benin Centre for Scientific Research and Innovation 03 PO Box 1665 Cotonou Republic of Benin

Allometric equations developed for the Lama forest, located in southern Benin, West Africa, were applied to estimate carbon stocks of three vegetation types：undisturbed forest, degraded forest, and fallow. Carbon stock of the undisturbed forest was 2.7 times higher than that in the degraded forest and 3.4 times higher than that in fallow. The structure of the forest suggests that the individual species were generally concentrated in lower diameter classes. Carbon stock was positively correlated to basal area and negatively related to tree density, suggesting that trees in higher diameter classes contributed significantly to the total carbon stock. The study demonstrated that large trees constitute an important component to include in the sampling approach to achieve accurate carbon quantification in forestry. Historical emissions from deforestation that converted more than 30% of the Lama forest into cropland between the years 1946 and 1987 amounted to 260,563.17 tons of carbon per year（t CO2/year） for the biomass pool only. The study explained the application of biomass models and ground truth data to estimate reference carbon stock of forests.

关键词： Biomass Reference level Site-specific biomass model Spatial distribution Tropical forest ecosystem

Juicy Stories on Female Reproductive Tissue Development: Coordinating the Hormone Flows

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Journal of Integrative Plant Biology 2013年第9期55卷 847-863页

作者： Veronica A.grieneisen Athanasius F.M.Marée Lars φstergaard Computational and Systems Biology John Innes Centre Norwich Research ParkNorwich NR4 7UH UK Crop genetics John Innes Centre Norwich Research ParkNorwich NR4 7UH UK

In the past 20-30 years, developmental biologists have made tremendous progress in identifying genes required for the specifica-tion of individual cell types of an organ and in describing how they interact in genetic networks. In comparison, very little is known about the mechanisms that regulate tissue polarity and overall organ patterning. gynoecia and fruits from members of the Brassicaceae family of flowering plants provide excellent model systems to study organ patterning and tissue specification because they become partitioned into distinct domains whose formation is determined by polarity establishment both at a cellular and whole tissue level. Interactions among key regulators of Arabidopsis gynoecium and fruit development have revealed a network of upstream transcription factor activities required for such tissue differentiation. Regulation of the plant hormone auxin is emerging as both an immediate downstream output and input of these activities, and here we aim to provide an overview of the current knowledge regarding the link between auxin and female reproductive development in plants. In this review, we will also demonstrate how available data can be exploited in a mathematical modeling approach to reveal and understand the feedback regulatory circuits that underpin the polarity establishment, necessary to guide auxin flows.

关键词： Auxin dynamics brassicaceae cell and tissue polarity fruit gynoecium mathematical modelling organ patterning ROPs wavepinning

Hopf-flip bifurcation of high dimensional maps and application to vibro-impact systems

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Acta Mechanica Sinica 2005年第4期21卷 402-410页

作者： Jianhua Xie Wangcai Ding e.H. Dowell L. N. Virgin Department of Applied Mechanics and engineering Southwest Jiaotong University Chengdu 610031 China School of Mechanical engineering Lanzhou Jiaotong UniversityLanzhou 730070 China School of engineering.Duke University. Durham NC27708-0300USA

This paper addresses the problem of Hopf-flip bifurcation of high dimensional maps. Using the center manifold theorem, we obtain a three dimensional reduced map through the projection technique. The reduced map is further transformed into its normal form whose coefficients are determined by that of the original system. The dynamics of the map near the Hopf-flip bifurcation point is approximated by a so called “time-2τ^2 map” of a planar autonomous differential equation. It is shown that high dimensional maps may result in cycles of period two, tori T^1 （Hopf invariant circles）, tori 2T^1 and tori 2T^2 depending both on how the critical eigenvalues pass the unit circle and on the signs of resonant terms＇ coefficients. A two-degree-of-freedom vibro-impact system is given as an example to show how the procedure of this paper works. It reveals that through Hopf-flip bifurcations, periodic motions may lead directly to different types of motion, such as subharmonic motions, quasi-periodic motions, motions on high dimensional tori and even to chaotic motions depending both on change in direction of the parameter vector and on the nonlinear terms of the first three orders.

关键词： Maps Vibro-impact dynamics Hopf-flip bifurcation Torus Chaos

evaluation of the earth＇s Magnetospheric Magnetic Field Models by Means of Cosmic Ray Data

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Journal of Physical Science and Application 2012年第6期2卷 175-185页

作者： Marta I. Tyasto Olga A. Danilova Natalia g. Ptitsyna Valery e. Sdobnov St. Petersburg Filial of lnstitute of Terrestrial Magnetism Ionosphere and Radiowave Propagation Russian Academy of Science(SPbF IZMIRAN) St. Petersburg 191023 Russia Institute of Solar-Terrestrial Physics Irkutsk 333101 Russia

At present, there are no reliable methods to evaluate uncertainty of model representation of magnetic field （MF） in the whole volume of the earth＇s magnetosphere. Cosmic ray intensity distribution on the earth surface contains information on the space distribution of magnetospheric MF through which charged particles propagate. Feasibility and limitations of cosmic ray data to be a tool for the validation of magnetospheric MF models have been analyzed. The authors＇ approach is based on the fact that time variations of magnetospheric cosmic ray are related to the changes in geomagnetic cutoff rigidities. The obtained cutoff rigidity changes by the trajectory tracing method in the MF model with those obtained on the base of experimental cosmic ray data have also been compared. The obtained results have shown that cosmic ray data can be successfully used for validation of models in presenting the dynamic structure of magnetospheric MF at mid latitudes.

关键词： Magnetospheric model cosmic rays geomagnetic cutoff rigidity.

An ADRC Parameters Self-Tuning Control Strategy of Tension System Based on RBF Neural Network

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Journal of Renewable Materials 2023年第4期11卷 1991-2014页

作者： Shanhui Liu Haodi Ding Ziyu Wang Li’e Ma Zheng Li Faculty of Printing Packaging Engineering and Digital Media TechnologyXi’an University of TechnologyXi’an710048China Shaanxi Beiren Printing Machinery Co. Ltd.Weinan714000China

High precision control of substrate tension is the premise and guarantee for producing high-quality products in roll-to-roll precision coating ***,the complex relationships in tension system make the problems of decoupling control difficult to be solved,which has limited the improvement of tension control accuracy for the coating ***,an ADRC parameters self-tuning decoupling strategy based on RBF neural network is proposed to improve the control accuracy of tension system in this ***,a global coupling nonlinear model of the tension system is established according to the composition of the coating machine,and the global coupling model is linearized based on the first-order Taylor ***,according to the linear model of the tension system,a parameters self-tuning decoupling algorithm of the tension system is proposed by integrating feedforward control,ADRC and ***,the simulation results show that the proposed tension control strategy has good decoupling control performance and effectively improves the tension control accuracy for the coating machine.

关键词： Coating machine tension system decoupling control ADRC RBF

Influence of wall slip on the hydrodynamic behavior of a two-dimensional slider bearing

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Acta Mechanica Sinica 2007年第6期23卷 655-661页

作者： g. J. Ma C. W. Wu P. Zhou State Key Laboratory of Structural Analysis for Industrial equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

In the present paper, a multi-linearity method is used to address the nonlinear slip control equation for the hydrodynamic analysis of a two-dimensional （2-D） slip gap flow. Numerical analysis of a finite length slider bearing with wall slip shows that the surface limiting shear stress exerts complicated influences on the hydrodynamic behavior of the gap flow. If the slip occurs at either the stationary surface or the moving surface （especially at the stationary surface）, there is a transition point in the initial limiting shear stress for the proportional coefficient to affect the hydrodynamic load support in two opposite ways： it increases the hydrodynamic load support at higher initial limiting shear stresses, but decreases the hydrodynamic load support at lower initial limiting shear stresses. If the slip occurs at the moving surface only, no fluid pressure is generated in the case of null initial limiting shear stress. If the slip occurs at both the surfaces with the same slip property, the hydrodynamic load support goes off after a critical sliding speed is reached. A small initial limiting shear stress and a small proportionality coefficient always give rise to a low friction drag.

关键词： Wall slip Slider beating Multi-linearity method Quadratic programming

Stokes flow before plane boundary with mixed stick-slip boundary conditions

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Applied Mathematics and Mechanics(english edition) 2011年第6期32卷 795-804页

作者： N.AKHTAR g.A.H.CHOWDHURY S.K.SeN Department of Mathematics Shahjalal University of Science and Technology Research Centre for Mathematical and Physical Sciences University of Chittagong

A general theorem for the Stokes flow over a plane boundary with mixed stick-slip boundary conditions is established. This is done by using a representation for the velocity and pressure fields in the three-dimensional Stokes flow in terms of a biharmonic function and a harmonic function. The earlier theorem for the Stokes flow due to fundamental singularities before a no-slip plane boundary is shown to be a special case of the present theorem. Furthermore, in terms of the Stokes stream function, a corollary of the theorem is also derived, providing a solution to the problem of the axisymmetric Stokes flow along a rigid plane with stick-slip boundary conditions. The formulae for the drag and torque exerted by the fluid on the boundary are established. An illustrative example is given.

关键词： Stokes flow Stokes stream function stick-slip boundary conditions,harmonic function biharmonic function