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DESIGN AND SYNTHESIS OF NOVEL CHIRAL IONIC LIQUIDS AND THEIR APPLICATION IN FREE RADICAL POLYMERIZATION OF METHYL METHACRYLATE

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Chinese Journal of Polymer Science 2003年第3期21卷 265-270页

作者：宛新华 department of Polymer Science & engineering College of Chemistry & Molecular engineering.Peking University Beijing 100871 China

Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by ~1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl_2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization ofmenthyl methacrylate (MnMA) in chlorobenzene, which yielded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.

关键词： Chiral ionic liquids Reverse ATRP Free radical polymerization Methyl methacrylate Menthyl methacrylate

Asymmetry of the water flux induced by the deformation of a nanotube

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Chinese Physics B 2012年第5期21卷 372-377页

作者：何俊霞陆杭军刘扬吴锋民聂雪川周晓艳陈艳燕 department of Physics Zhejiang Normal University department of Mechanical engineering the Hong Kong Polytechnic University

The behavior of nano-confined water is expected to be fundamentally different from the behavior of bulk *** the nanoscale,it is still unclear whether water flows more easily along the convergent direction or the divergent one,and whether a hourglass shape is more convenient than a funnel shape for water molecules to pass through a ***,we present an approach to explore these questions by changing the deformation position of a carbon *** results of our molecular dynamics simulation indicate that the water flux through the nanotube changes significantly when the deformation position moves away from the middle region of the *** from the macroscopic level,we find water flux asymmetry（water flows more easily along the convergent direction than along the divergent one）,which plays a key role in a nano water pump driven by a ratchet-like *** explore the mechanism and calculate the water flux by means of the Fokker-Planck equation and find that our theoretical results are well consistent with the simulation ***,the simulation results demonstrate that the effect of deformation location on the water flux will be reduced when the diameter of the nanochannel *** findings are helpful for devising water transporters or filters based on carbon nanotubes and understanding the molecular mechanism of biological channels.

关键词： single-walled carbon nanotube deformation position molecular dynamics simulation,water flux

Surface tension effects on the behaviour of a rising bubble driven by buoyancy force

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Chinese Physics B 2010年第2期19卷 392-400页

作者：王含张振宇杨永明张慧生 department of Mechanics and engineering Science Fudan University department of Mathematics Shanghai University of Finance and Economics

In the inviscid and incompressible fluid flow regime,surface tension effects on the behaviour of an initially spherical buoyancy-driven bubble rising in an infinite and initially stationary liquid are investigated numerically by a volume of fluid （VOF） method. The ratio of the gas density to the liquid density is 0.001, which is close to the case of an air bubble rising in water. It is found by numerical experiment that there exist four critical Weber numbers We1,~We2,~We3 and We4, which distinguish five different kinds of bubble behaviours. It is also found that when 1≤We2, the bubble will finally reach a steady shape, and in this case after it rises acceleratedly for a moment, it will rise with an almost constant speed, and the lower the Weber number is, the higher the speed is. When We 〉We2, the bubble will not reach a steady shape, and in this case it will not rise with a constant speed. The mechanism of the above phenomena has been analysed theoretically and numerically.

关键词： rising bubble surface tension buoyancy volume of fluid (VOF) method

Assessing dynamic response of multispan viscoelastic thin beams under a moving mass via generalized moving least square method

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Acta Mechanica Sinica 2010年第5期26卷 721-733页

作者： Keivan Kiani Ali Nikkhoo Bahman Mehri department of Civil engineering Sharif University of Technology department of Mathematical Sciences Sharif University of Technology

Dynamic response of multispan viscoelastic thin beams subjected to a moving mass is studied by an efficient numerical method in some detail. To this end, the unknown parameters of the problem are discretized in spatial domain using generalized moving least square method （GMLSM） and then, discrete equations of motion based on Lagrange＇s equation are obtained. Maximum deflection and bending moments are considered as the important design parameters. The design parameter spectra in terms of mass weight and velocity of the moving mass are presented for multispan viscoelastic beams as well as various values of relaxation rate and beam span number. A reasonable good agreement is achieved between the results of the proposed solution and those obtained by other researchers. The results indicate that, although the load inertia effects in beams with higher span number would be intensified for higher levels of moving mass velocity, the maximum values of design parameters would increase either. Moreover, the possibility of mass separation is shown to be more critical as the span number of the beam increases. This fact also violates the linear relation between the mass weight of the moving load and the associated design parameters, especially for high moving mass velocities. However, as the relaxation rate of the beam material increases, the load inertia effects as well as the possibility of moving mass separation reduces.

关键词： Moving mass-beam interaction - Multispan viscoelastic beam Euler-Bernoulli beam Generalized moving least square method (GMLSM)

On the Correct Form of the Saha Equation for Two-Temperature Plasmas

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Chinese Physics Letters 1999年第3期16卷 193-195页

作者： HAN Peng CHEN Xi LI He-ping department of engineering Mechanics Tsinghua UniversityBeijing 100084

Two quite different Saha equations modified to a two-temperature plasma were proposed and employed in many *** order to clear up this confusion phenomenon lasted for a few decades in the community of thermal plasma science and technology,this paper re-examines the thermodynamic derivation of the two-temperature Saha *** is pointed out that the modified Saha equation deduced by using the minimum Gibbs or Helmholtz free energy is incorrect for the two-temperature ***,a more rigorous derivation is presented here from the basic thermodynamic principle that the entropy in an isolated system always assumes its maximum value at chemical equilibrium.

关键词： derivation thermodynamic assume

Morphology evolution and crystallographic feature of Nb nanowire in an in-situ NiTi-Nb nanocomposite

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Rare Metals 2014年第5期33卷 563-567页

作者： Zhen-Yang Liu Fang-Min Guo Zhong-Qiang Wang Li-Shan Cui department of Materials Science and engineering China University of Petroleum

In–situ NiTi shape memory alloy–Nb nanowire nanocomposite was revealed to exhibit exceptional mechanical properties. The properties of high strength and ultra-large elastic strains are closely related with the high performance of in situ-formed Nb nanowire reinforcements. In this study, the morphology evolution and crystallographic feature of Nb nanowires in NiTi shape memory alloy matrix during cold drawing were investigated by means of transmission electron microscopy（TEM）. It is revealed that, as a result of the severe work hardening and amorphization of NiTi matrix, the cold work reduction of nanowire reinforcements can exceed that of the entire composite. The irregular-shaped Nb nanowires are reshaped to straight and smooth nanowires during cold drawing process. By means of TEM nanobeam diffraction,it is revealed that the in situ-formed Nb nanowire in such top-down processed NiTi–Nb composite keeps single crystalline over 1,000 nm at length direction. As a consequence, the aspect ratio of nanowire reinforcements in NiTi matrix exceeds 25：1.

关键词： Deep drawing Nanowire Metal matrix composite TEM

Three-dimensional simulation for problem of penetrative convection near the maximum density

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Journal of Hydrodynamics 2015年第2期27卷 292-303页

作者： HARFASH Akil J. ALSHARA Ahmed K. department of Mathematics College of SciencesUniversity of Basrah Petroleum department College of EngineeringUniversity of Misan

The problem of penetrative convection with the cubic and fifth-order equations of state proposed by Merker, Waas and Grigull is studied. Both linear instability and nonlinear stability analyses are performed to assess the suitability of linear theory to predict destabilisation of the convection. The validity of both the linear instability and global nonlinear energy stability thresholds are tested using three-dimensional simulation. The results show that the linear threshold accurately predicts the onset of instability in the basic steady state solution.

关键词： thermal convection linear instability nonlinear stability finite difference scheme

Web C: toward a portable framework for deploying legacy code in web browsers

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Science China(Information Sciences) 2015年第7期58卷 113-127页

作者： YIN Jie TAN Gang BAI XiaoLong HU ShiMin department of Computer Science and Technology Tsinghua University department of Computer Science and engineering Lehigh University

For security, most web applications are developed in some type-safe language, such as Java Script or Java. However, there is a huge amount of legacy codes developed in unsafe languages, which provide rich functionality and are more efficient than their type-safe counterparts. To allow browsers to incorporate type-safe components in a secure way, previous approaches use the software-based fault isolation(SFI) to isolate untrusted legacy code. The SFI approach performs machine-code transformation for security, but the downside is the loss of architecture independence. We propose Web C, a system that allows legacy code transmitted over the web via the Low Level Virtual Machine(LLVM) bitcode format. The untrusted bitcode is transformed by Web C into code in the Web C security language, which enforces both memory isolation and control-flow integrity. Compared with previous approaches, Web C is more portable, provides stronger security, and allows more flexible memory management. Experimental results show that the average runtime overhead of Web C is modest.

关键词： Web C software fault isolation symbol link shadow memory area portable

Some interesting properties of black hydrogen-treated TiO2 nanowires and their potential application in solar energy conversion

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Science China Chemistry 2015年第12期58卷 1810-1815页

作者： Ping Yu Jinzhong Zhang department of Chemical engineering Shenyang University of Chemical Technology department of Chemistry and Biochemistry University of California

Hydrogen treatment has been proposed as a simple and effective strategy to enhance the performance of Ti O2 nanostructures for applications such as photocatalysis and photoelectrochemical(PEC) water splitting. While some studies have suggested that the black color can be ascribed to surface disorder, other reports have suggested that it is caused by the "oxygen vacancy" states associated with Ti3+ within the bandgap of the Ti O2. The chemical nature and potential use of the bandgap states responsible for the black color of increased visible absorption is not yet well understood and subject of strong interest. Here we briefly review current understanding of the possible mechanisms behind the black color of hydrogen-treated Ti O2 nanowires and its relevance to photocatalysis and solar water splitting for hydrogen generation. One important conclusion to date is that while hydrogen treatment enhances photocurrent of Ti O2 with UV excitation, no noticeable photocurrent can be detected with visible light, which seems to be due to the very short lifetimes of the bandgap oxygen vacancy states arising from hydrogen treatment.

关键词： black Ti O2 photoelectrochemical water splitting Ti O2 nanowires hydrogen treatment oxygen vacancy