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Interfacial behaviors of PMMA-PEO block copolymers at the air/water interface

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Science china Chemistry 2005年第6期48卷 567-573页

作者： CHENG Caixia1, JIAO Tifeng2. TANG Rupei1, LIU Minghua2.& XI Fu1 1. State Key Laboratory of Polymer physics and Chemistry, Joint Laboratory of Polymer Science and Materials, {3. of Chemistry, Chinese Academy of Sciences,{2., china 2. CAS Key Laboratory of Colloid and Interface Science, {3. of Chemistry, Chinese Academy of Sciences,{2., china 1. State Key Laboratory of Polymer physics and Chemistry Joint Laboratory of Polymer Science and Materials Institute of Chemistry Chinese Academy of Sciences 100080 Beijing China 2. CAS Key Laboratory of Colloid and Interface Science Institute of Chemistry Chinese Academy of Sciences 100080 Beijing China

Diblock copolymer of PMMA2.1-b-PEO114 and triblock copolymer of PMMA12.-b- PEO2.7-b-PMMA12. were synthesized and their interfacial properties at the air-water interface were investigated, where both blocks of polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) are surface active but the former is soluble in water while the latter is not. Both the block copolymers could form monolayers with two obvious transition regions. The first transition point is around 10 mN/m, which could be assigned to the pancake-brush change of the PEO chains. The other is around 18 mN/m, which could be ascribed to the condensed packing of PMMA. The surface morphological changes during the compression of the Langmuir monolayers are inves-tigated by using the AFM and SEM methods for the films deposited at different surface pressure or molecular areas. At a lower surface pressure, a typical morphology of PEO-con- taining lipopolymers is observed. Upon compression, sphere-dominant morphologies were observed. While the diblock copolymer is easy to folding, the triblock copolymer is in favor of formation of circular domains through vesiculation.

关键词： PMMA-PEO, block copolymers, monolayer, Langmuir-Blodgett films, AFM.

Experimental studies on perturbed acoustic resonant spectroscopy by a small rock sample in a cylindrical cavity

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Science china(physics,Mechanics & Astronomy) 2006年第6期49卷 683-701页

作者： CHEN Dehua1,2.WANG Xiuming2.3.CONG Jiansheng1,XU Delong1,SONG Yanjie1 & MA Shuilong4 1. Department of Geophysics,Daqing Petroleum {3.,Daqing 163.18,{2. 2. {3. of Acoustics,Chinese Academy of Sciences,beijing 100080,{2. 3. Division of Petroleum,Australian Commonwealth Scientific and Industrial Research Organization,Bent-ley WA 6102.Australia 4. Daqing Testing and Technology Services Corporation,Daqing 163.53.{2. Department of Geophysics Daqing Petroleum Institute Daqing 163318 China institute of Acoustics Chinese Academy of Sciences Beijing 100080 China Division of Petroleum Australian Commonwealth Scientific Industrial Research Organization Bentley WA 6102 Australia Daqing Testing Technology Services Corporation Daqing 163153 China

A measurement system for acoustic resonant spectroscopy (ARS) is estab-lished,and the effects of resonant cavity geometry,inner perturbation samples and envi-ronmental temperature on the ARS are investigated. The ARSs of the small samples with various sizes and acoustic properties are measured. The results show that at the normal pressure,the resonant frequency decreases gradually with the increase of liquid tem-perature in the cylindrical cavity,while the resonant amplitude increases. At certain pres-sure and temperature,both the resonant frequency and the amplitude decrease greatly when there exist air bubbles inside the cavity fluid. The ARS is apparently affected by the sample porosity and the sample location in the resonant cavity. At the middle of the cavity,the resonant frequencies reach their maximum values for all of the measurement samples. The resonant frequencies of the porous rock samples are smaller than those of the com-pacted samples if other acoustic parameters are the same. As the sample is moved from the top to the middle of the cavity along its axis,the resonant amplitude increases gradu-ally for the compacted rocks while decreases for the unconsolidated rocks. Furthermore,the resonant amplitude increases firstly and then decreases if the porosity of the rock sample is relatively small. In addition,through the comparisons between the experimental and theoretical results,it is found that the effects of the acoustic parameters and sizes of the samples and the size of the cylindrical cavity on the laboratory results agree well with the theoretical ones qualitatively. These results may provide basic reference for the ex-periment study of rock acoustic properties in a low frequency using ARS.

关键词： acoustic resonant spectroscopy,acoustic velocity and attenuation,experiment measurement,rock acoustic property.

Improved ENSO simulation in regional coupled GCM using regressive correction method

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Science china Earth Sciences 2007年第8期50卷 1258-1265页

作者： FU WeiWei1 & ZHOU GuangQing2.1 Nansen-Zhu International Research Center (NZC), institute of atmospheric physics, Chinese Academy of Sciences (CAS), beijing 10002.,{2. 2.State Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics (lasg), institute of At-mospheric physics, CAS, beijing 10002.,{2. 1. Nansen-Zhu International Research Center (NZC) Institute of Atmospheric Physics Chinese Academy of Sciences (CAS) Beijing 100029 China 2. State Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics (lasg) Institute of Atmospheric Physics CAS Beijing 100029 China

A regressive correction method is presented with the primary goal of improving ENSO simulation in regional coupled GCM. It focuses on the correction of ocean-atmosphere exchanged fluxes. On the basis of numerical experiments and analysis, the method can be described as follows: first, driving the ocean model with heat and momentum flux computed from a long-term observation data set; the pro-duced SST is then applied to force the AGCM as its boundary condition; after that the AGCM’s simula-tion and the corresponding observation can be correlated by a linear regressive formula. Thus the re-gressive correction coefficients for the simulation with spatial and temporal variation could be obtained by linear fitting. Finally the coefficients are applied to redressing the variables used for the calculation of the exchanged air-sea flux in the coupled model when it starts integration. This method together with the anomaly coupling method is tested in a regional coupled model, which is composed of a global grid-point atmospheric general circulation model and a high-resolution tropical Pacific Ocean model. The comparison of the results shows that it is superior to the anomaly coupling both in reducing the coupled model ‘climate drift’ and in improving the ENSO simulation in the tropical Pacific Ocean.

关键词： anomaly coupling regressive correction method regional coupled model ENSO simulation

The numerical method for three-dimensional impact with friction of multi-rigid-body system

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Science china(physics,Mechanics & Astronomy) 2006年第1期49卷 102-118页

作者： ZHAO Zhen1,2. LIU Caishan2.& CHEN Bin2.1. {3. institute of Graphic Communication, {3. 102.00, china 2. Department of Mechanics & Engineering Science, Peking University, {3. 100871, china beijing institute of Graphic Communication Beijing 102600 China Department of Mechanics & Engineering Science Peking University Beijing 100871 China

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid nu- merical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tan- gential movement modes varied with the normal impulse during collision.

关键词： multi-rigid body, impact, friction.

Linear relationship between the interdecadal and interannual variabilities of North china rainfall in rainy season

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Chinese Science Bulletin 2003年第10期48卷 1040-1044页

作者： LU Riyu institute of atmospheric physics, Chinese Academy of Sciences, beijing 100080,{2. institute of atmospheric {2. Chinese Academy of Sciences Beijing 100080 China

Interdecadal and interannual timescales are dominant in the North china rainfall in rainy season (July and August). On the interdecadal timescale, the North china rainfall exhibited an abrupt decrease at the end of 1970s. In this study, we examined the effect of this abrupt rainfall decrease on the association between rainfall and circulation on the interannual timescale, and found that the interdecadal variation does not change the physical mechanism responsible for the interannual variation of North china rainfall. There is a linear relationship between the interdecadal and interannual variabilities of North china rainfall in rainy season.

关键词：线性关系中国北部降雨量大气环流

Computational stability of the forced dissipative nonlinear atmospheric equations

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Chinese Science Bulletin 1999年第10期44卷 949-952页

作者： LI Jianping and CHOU Jifan lasg , institute of atmospheric physics , Chinese Academy of Sciences ,{2.,{3. Department of atmospheric Sciences , Lanzhou University , Lanzhou 73.000,{3. beijing Meteorological College, beijing 100081,{3. lasg Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Department of atmospheric Sciences Lanzhou University Lanzhou China beijing Meteorological College Beijing China

A new concept of computational quasi-stability (CQS) is introduced to study the computational stability (CS) of the forced dissipative nonlinear (FDN) evolution equations. Based on the concept, the CQS criterion of difference scheme of FDN atmospheric equations is obtained. So it provides the theoretical basis for designing the computational stable difference scheme of FDN atmospheric equations.

关键词： computational stability (CS) computational quasi-stability (CQS) operator equation difference scheme forced dissipative nonlinear (FDN) equations.

Effects of 4DVAR with multifold observed data on the typhoon track forecast

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Chinese Science Bulletin 2003年第S2期48卷 93-98页

作者： WANG Yunfeng, WANG Bin, MA GANG & WANG Yushun 1. lasg, institute of atmospheric physics, Chinese Academy of Sciences. {2. 10002., china: 2. National Satellite Meteorological Center, {2. 100081. china Chinese Acad Sci Inst Atmospher Phys LASG Beijing 100029 Peoples R China Natl Satellite Meteorol Ctr Beijing 100081 Peoples R China

Effects of 4-dimension variational data assimi-lation (4DVAR) with multifold observed data on the typhoontrack forecast are studied, by using the MM5V3.model, theRTTOVS-5 model and their adjoint models. The data usedfor assimilation include large-scale background fields data,bogus data, cloud-derived wind data, satellite inverse data,and high resolution infrared radiation sounder data (HIRS).There are 5 typhoon cases are used to perform the numericalexperiments and assimilation experiments. The numericalresults show that with 4DVAR the initial fields can be greatlyimproved and the initial typhoon structure can be clearlydescribed.

关键词： multifold observed data 4DVAR typhoon track. DOI: 10.13.0/03.d0456

A new method of discovering new meteor showers from the IMO single-station video meteor database

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Science china(physics,Mechanics & Astronomy) 2008年第8期51卷 1170-1178页

作者： LI Jun1,2.& ZHU Jin3.1 No.2.Middle School of beijing,beijing 100010,{2. 2.School of Journalism and Communication,Tsinghua University,beijing 100084,{2. 3.beijing Planterium,beijing 100044,{2. 1. No.2.Middle School of beijing Beijing 100010 China 2. School of Journalism and Communication Tsinghua University Beijing 100084 China 3. beijing Planterium Beijing 100044 China

It has been found that unknown meteor showers could be efficiently discovered from the single station video meteor database of the International Meteor Organization(IMO) by assuming the geocentric velocity and adjusting it within the dynamically permitted range. The mean geocentric velocities of new meteor showers can be obtained,as well as the coordinates of the radiants. The activity period and maximum time can also be obtained if there are sufficient shower meteors. All single station video meteor observations between February 13.and 17(from 2.00 to 2.05) in IMO's database are processed with this method. As a result,two new meteor showers,one near RA=2.5.10°,Dec=41.82. in Hercules and the other near RA=2.3.03.,Dec=17.04° in Serpenids,are discovered. Some dynamical characteristics of the new meteor showers are also determined. Considering the random nature on the selection of period in this work,it is expected that there are some more potential new meteor showers in IMO's video database.

关键词： single-station video meteor database the process of single-station video meteor database discovery of new meteor showers

Influence of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific on the inter-decadal variations of the stratosphere-troposphere exchange of water vapor

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Science china Earth Sciences 2008年第8期51卷 1179-1193页

作者： ZHAN RuiFen1,2.LI JianPing2.1Shanghai Typhoon institute of{3. Meteorological Administration,Shanghai 2.003.,{2. 2.tate Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics(lasg),institute of atmospheric physics,Chinese Academy of Sciences,beijing 10002.,{2. 1. Shanghai Typhoon institute of china Meteorological Administration Shanghai 200030 China 2. State Key Laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics (lasg) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

This study investigates the Stratosphere-Troposphere Exchange(STE) of water vapor,emphasizes its interdecadal variations over Asia in boreal summer,and discusses the influences of atmospheric heat sources over the Tibetan Plateau and the tropical western North Pacific(WNP) on them by using the Wei method with reanalysis data from the European Centre for Medium-Range Weather Forecasts(ECMWF) for the years of *** climatology shows that the upward transport of water vapor across the tropopause in boreal summer is the most robust over the joining area of the South Asian Peninsula and Indian-Pacific Oceans(defined as AIPO).The upward transport over there can persistently convey the abundant water vapor into the stratosphere and then influence the distribution and variation of the stratospheric water *** analysis shows that interdecadal variations of the water vapor exchange over the AIPO are significant,and its abrupt change occurred in the mid-1970s and the early *** these three periods,as important channels of the water vapor exchange,the effect of Bay of Bengal-East Asia as well as South china Sea was gradually weakening,while the role of the WNP becomes more and more *** studies show that atmospheric heat sources over the Tibetan Plateau and the WNP are two main factors in determining the interdecadal variations of water vapor *** thermal influences over the Tibetan Plateau and the WNP have been greatly adjusted over the pass 44 *** synthesis influences the interdecadal variations of the water vapor exchange by changing the Asian summer monsoon,but their roles vary with time and *** after 199{3.the influence of heat source over the Tibetan Plateau remarkably weakens,while the heat source over the WNP dominates the across-tropopause water vapor *** have important implications for understanding the transport of other components in the atmosphere and estimating the impact of human activities(

关键词： Tibetan Plateau tropical western North Pacific atmospheric heat source STE inter-decadal variations