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Syntheses of amphiphilic biodegradable copolymers of poly(ethyl ethylene phosphate) and poly(3-hydroxybutyrate) for drug delivery

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science china Chemistry 2009年第7期52卷 961-968页

作者： CHENG Jing1 & WANG Jun2 1 Department of Polymer science and Engineering, university of science and technology of china, hefei 230026, china 2 hefei National Laboratory for Physical sciences at Microscale, school of Life sciences, university of science and technology of china, hefei 230027, china Department of Polymer science and Engineering University of Science and Technology of China Hefei China hefei National Laboratory for Physical sciences at Microscale School of Life Sciences University of Science and Technology of China Hefei China

Biodegradable and amphiphilic triblock copolymers poly(ethyl ethylene phosphate)-poly(3-hydroxybutyrate)-poly(ethyl ethylene phosphate) (PEEP-b-PHB-b-PEEP) have been successfully synthesized through ring-opening polymerization. The structures are confirmed by gel permeation chromatography and NMR analyses. Crystallization investigated by X-ray diffraction reveals that the block copolymer with higher content of poly(ethyl ethylene phosphate) (PEEP) is more amorphous, showing decreased crystallizability. The obtained copolymers self-assemble into biodegradable nanoparticles with a coreshell micellar structure in aqueous solution, verified by the probe-based fluorescence measurements and transmission electronic microscopy (TEM) observation. The hydrophobic poly(3-hydroxybutyrate) (PHB) block serves as the core of the micelles and the micelles are stabilized by the hydrophilic PEEP block. The size and size distribution are related to the compositions of the copolymers. Paclitaxel (PTX) has been encapsulated into the micelles as a model drug and a sustained drug release from the micelles is observed. MTT assay also demonstrates that the block copolymers are biocompatible, rendering these copolymers attractive for drug delivery.

关键词： poly(3-hydroxybutyrate) polyphosphoester drug delivery polymeric nanoparticles

Bell violation for the thermal states of an XXZ spin chain with Dzialoshiski-Moriya interaction

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science china(Physics,Mechanics & Astronomy) 2010年第11期53卷 2074-2079页

作者： MA XiaoSan 1 & WANG AnMin 2 1 school of Electric Engineering and Information,Anhui university of technology,Maanshan 243002,china 2 Department of Modern Physics,university of science and technology of china,hefei 230026,china school of Electric Engineering and Information Anhui University of Technology Maanshan China Department of Modern Physics University of Science and Technology of China Hefei China

The effect of Dzialoshiski-Moriya (DM) interaction on the violation of Bell inequality for thermal states of interacting qubits via a two-qubit XXZ spin chain is *** results imply that the DM interaction and anisotropy taking a large positive value can enhance the Bell violation and improve the threshold temperatures of *** the comparison between the Bell violation and thermal entanglement,we find that the threshold temperatures of thermal entanglement are higher than those of the Bell *** implies that some states are entangled but the Bell inequality is not violated.

关键词： Bell violation threshold temperatures DM interaction

Existence of unbiased estimate of regression parameters in simple linear EV models

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science china Mathematics 2005年第7期48卷 915-928页

作者： LIU Jixue & CHEN Xiru Department of Statistics and Finance, university of science and technology of china, hefei 230026, china Department of Mathematics, graduate school of Chinese Academy of sciences, Beijing 100049, china Department of Statistics and Finance University of Science and Technology of China Hefei 230026 China Department of Mathematics Graduate School Chinese Academy of Sciences Beijing 100049 China

It is well known that for one-dimensional normal EV regression model X = x+ u,Y =α+βx+e, where x, u, e are mutually independent normal variables and Eu=Ee=0, the regression parameters a and β are not identifiable without some restriction imposed on the parameters. This paper discusses the problem of existence of unbiased estimate for a and β under some restrictions commonly used in practice. It is proved that the unbiased estimate does not exist under many such restrictions. We also point out one important case in which the unbiased estimates of a and β exist, and the form of the MVUE of a and β are also given.

关键词： EV regression model unbiased estimate identiflability.

Uniform estimate for maximum of randomly weighted sums with applications to insurance risk theory

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science china Mathematics 2005年第10期48卷 1379-1394页

作者： WANG Dingcheng~1 SU Chun~2 & ZENG Yong~1 1. school of Management and school of Applied Mathematics,university of Electronic science and technology of china,Chengdu 610054,china 2. Department of Statistics and Finance,university of science and technology of china,hefei 230026,china school of Management and school of Applied Mathematics University of Electronic Science and Technology of China Chengdu China Department of Statistics and Finance University of Science and Technology of China Hefei China

This paper obtains the uniform estimate for maximum of sums of independent and heavy-tailed random variables with nonnegative random weights, which can be arbitrarily dependent of each other. Then the applications to ... 详细信息

关键词： dependent stochastic return, discount factor, heavy-tails, discrete time insurance risk model, maxima of randomly weighted sums, ruin probability, tail probabilities, uniformly asymptotic estimate.

Linear EV model with replicate observations on independent variables

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science china Mathematics 2006年第6期49卷 752-769页

作者： LIU Jixue, ZHANG Sanguo & CHEN Xiru Department of Statistics and Finance, university of science and technology of china, hefei 230026, china Department of Mathematics, graduate school of Chinese Academy of sciences, Beijing 100049, china Department of Statistics and Finance University of Science and Technology of China Hefei China Department of Mathematics Graduate School of Chinese Academy of Sciences Beijing China

This paper studies the linear EV model when replicate observations are made only on independent variables. We construct the estimates of regression coefficients and prove the consistency and asymptotic normality under some proper conditions. Results obtained reveal the difference between the case where the independent and dependent variables are observed repeatedly and simultaneously and the case studied in this article.

关键词： linear EV model, consistency, asymptotic normality.

A new approximating method for Holstein model

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science china(Physics,Mechanics & Astronomy) 2010年第1期53卷 44-48页

作者： REN XueZao 1 , LIAO Xu 1 , LI Lei 1 & WANG KeLin 2 1 school of science, Southwest university of science and technology, Mian Yang 621010, china 2 Department of Modern Physics, university of science and technology of china, hefei 230026, china school of science Southwest University of Science and Technology Mian Yang China Department of Modern Physics University of Science and Technology of China Hefei China

A new approach-the method of coherent state orthogonal expansion is developed for one-dimensional Holstein model. In zeroth order approximation, the formula of ground state energy is deduced analytically and the solutions in strong- and weak-coupling limits are obtained correctly. When the trial wave-function of ground state is expanded to the second order, the obtained ground state energy agrees quite well with that calculated by numerical method in all coupling regimes. The present approach can be easily generalized to the situations of higher dimensions and more electrons.

关键词： coherent-state orthogonal expansion polaron simulated annealing method

THE OPTIMAL MOTION OF TWO-DIMENSIONAL UNDULATING PLATE SWIMMING IN FLUID FLOW

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Journal of Hydrodynamics 2011年第1期23卷 12-20页

作者： QIAN Qin-jian LIU Miao-qin SUN Liang SUN De-jun Department of Modern Mechanics University of Science and Technology of China Hefei 230026 China school of Earth sciences University of Science and Technology of China Hefei 230026 China

The optimum shape of a two-dimensional undulatory plate in its motion in fluid flow is analyzed and the physical parameters（the thrust and the power）are calculated by the boundary element *** the commonly used Lagrange multiplier method,only a saddle point of the optimum solution can be obtained,but not the solution itself due to the singularity of the *** eliminate the singularity,a method is proposed by adding an amplitude *** new method is a generalization of that proposed by Wu,and it can be applied to more complex *** optimum shape of the linearly varying amplitude motion is studied in *** is shown that both the maximum and the minimum solutions exist when the frequency is higher than a critical *** a high frequency,the maximum efficient motion with a large amplitude at the leading edge and a small amplitude at the trailing edge induces a large leading edge suction *** the frequency decreases,the leading edge suction force decreases to a minimum and then *** high wavenumbers,there exists an optimum frequency with the maximum *** efficiency holds over a large range of *** optimum efficiency increases as the wavenumber *** increase of the wavenumber can also reduce the leading edge suction *** optimization method can also be applied to a quadratically varying amplitude *** is found that the optimum efficiency is larger than that for the linearly varying amplitude ***,the additional efficiency is relatively small,especially as the original efficiency is already high enough.

关键词： two-dimensional undulating plate boundary element method optimization

Characteristics of low-frequency oscillation intensity of airsea turbulent heat fluxes over the northwest Pacific

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science china Earth sciences 2009年第8期52卷 1137-1151页

作者： LI Gen, REN BaoHua, ZHENG JianQiu & WANG Jun school of Earth and Space sciences, university of science and technology of china, hefei 230026, china school of Earth and Space sciences University of Science and Technology of China Hefei China

Based on the daily turbulent heat fluxes and related meteorological variables datasets (1985-2006) from Objectively Analyzed air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea humidity gradient (Δq′) as well as mean air-sea humidity gradient ( Δ q), while the distribution of low-frequency oscillation intensity of sensible heat flux (SHF) is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea temperature gradient (ΔT′). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those of low-frequency oscillation intensity of Δq′, low-frequency oscillation intensity of anomalous wind speed (U′), Δ q and mean wind speed (U ), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency oscillation intensity of ΔT′ and U . 3) Over the tropical west Pacific and sea areas north of 20°N, the low-frequency oscillation of LHF (SHF) is mainly influenced by atmospheric variables qa′ (Ta′) and U′, indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific south of 20°N, qs′ (Ts′) also greatly influences the low-frequency oscillation of LHF (SHF).

关键词： northwest Pacific latent heat flux sensible heat flux low-frequency oscillation

Mineralogical evidence for continental deep subduction

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Chinese science Bulletin 2003年第10期48卷 952-954页

作者： ZHENG Yongfei school of Earth and Space sciences, university of science and technology of china, hefei 230026, china Univ Sci & Technol china Sch Earth & Space Sci Hefei 230026 Peoples R China

Diamond is an index mineral to prove ultrahigh pressure (UHP) metamorphic conditions because it is only stable at the pressures above 3.3 GPa. Its occurrence in eclogite-facies metamorphic rocks suggests plate subduction to depths over 120 km assuming the normal gradient of lithostatic pressure. Because UHP eclogites are the metamorphic products of basaltic rocks, the occurrence of diamond in the eclogites demonstrates a complete geodynamic cycle in that mafic crustal rocks were subducted to mantle depths at once and then returned back to the Earth's surface.

关键词：矿物学超高压石英地球表面正态重力梯度