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Cloud point phenomenon in aqueous mixtures of cationic-anionic surfactants

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Chinese Journal of Chemistry 1994年第6期12卷 552-554页

作者： XIAO, Jin-Xin ZHAO, Guo-Xidepartment of Chemistry, peking university, beijing 100871, china department of Chemistry Peking University Beijing 100871 China Keywords Cloud point cation‐anionic surfactants.

It used to be held that the cloud point phenomenon was only a characteris-tic of nonionic surfactants alone. Such phenomenon is rarely observed in ionicsurfactants. The present study shows that the mixture of cationic-anionic surfac-tants not only has a krafft point which is the characteristic of an ionic surfactant,but also exhibits the cloud point phenomenon obviously at certain concentrations.

关键词： Cloud point cation-anionic surfactants.

The correlation of flare's location on solar disc and the sudden increase of total electron content

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Chinese Science Bulletin 2002年第1期47卷 82-85页

作者： ZHANG Donghe, XIAO Zuo & CHANG Qingdepartment of geophysics, peking university, beijing 100871, china Qingdao Research Center, china Research Insitute of Radio-wave Propagation, Qingdao 266071, china department of Electronic Engineering, beijing Universit department of geophysics Peking University Beijing China Qingdao Research Center China Research Insitute of Radio-wave Propagation Qingdao China department of Electronic Engineering Beijing University of Aeronautics and Astronautics Beijing China

The correlation of flare’s location on solar disc with the value of sudden increase of total electron content is analyzed with flare’s parameters observed by GOES satellite from 1997 to 1999 and total electron content derived from GPS data observed by international GPS Service for Geo-dynamics. It is found that, besides the flare’s maximum X-ray flux, flare’s location on solar disc has some relation with the value of SITEC during the flare. The ionospheric response to a flare with a smaller maximum X-ray flux and nearer angular distance to the Sun’s central meridian line may be stronger than that of the flare with a larger maxi-mum X-ray flux and far angular distance. To the flares with the same class of maximum X-ray flux, the nearer the angu-lar distance to the Sun’s meridian, the stronger the ionospheric response.

关键词： flare SITEC GPS.

Composition of sandstone and heavy minerals implies the provenance of Kuqa Depression in Jurassic, Tarim basin, china

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Progress in Natural Science:Materials International 2005年第7期15卷 633-640页

作者： WU Chaodong, LIN Changsong, SHEN Yanping and FENG Xue ( Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, peking university, beijing 100871, china department of Resources, china university of Geosciences, beijing 100083, china) Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education Peking University Beijing 100871 China. department of Resources China University of Geosciences Beijing 100083 China

The petrological characteristics and heavy mineral assembly of the Jurassic System in Kuqa Basin are consistent with the tectonic evolution, which is the major factor controlling the filling process of Kuqa Basin. Controlled by the source areas at the both sides of the Basin, the matrixes are dominated by sedimentary rock, high-grade metamorphic rock, acid magmatic rock, and the highest heavy mineral assemblage of zircon-garnet-magnetite in the content. According to heavy mineral indexes, the Jurassic strata can be classified into three rhythmic units of heavy mineral. The lower sequence contains abundant heavy minerals and relatively high content of detritus and its matrixes primarily came form the recycling orogen. The assemblage of "zircon-garnet-magnetite" indicates that the sedimentary area in the early evolution period of the basin is relatively near the provenance. The middle sequence is different from the lower sequence in the heavy mineral assemblage and has the different characteristics from that of source rock. The heavy mineral assemblage is "garnet-zircon" with the highest content of garnet and its main matrices are the high-grade metamorphic rock, acid magmatic rock and hydrothermal vein at the northeastern edge of the basin. The middle and upper sequences are characterized by the clast provenance, which is primarily from the recycling orogen at the northern edge of the basin and secondarily from the southern uplift. As a result of the two provenances, the strata with apparent changes of heavy mineral assemblage and index better coincides with the interfaces of the secondary strata sequences, which reflects the denudation history and the filling process of the orogen at the northern edge of the basin.

关键词： sandstone components provenance analysis filling sequence tectonic evolution.

STABILITY OF POLY(N,N'-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)MICROGEL DISPERSION AND ADJUSTMENT OF THE HYDROPHOBICITY IN THE MICROGELS

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Chinese Journal of Polymer Science 2005年第6期23卷 635-642页

作者： Qing-de Chen Xing-hai Shen and Hong-cheng Gao department of Applied Chemistry,College of Chemistry and Molecular Engineering,peking university,beijing 100871,china peking Univ Dept Appl Chem Coll Chem & Mol Engn Beijing 100871 Peoples R China

In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine）（poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.

关键词： Microgel dispersion(s) 4-Vinylpyridine Flocculation-coagulation parameter Zeta potential

EFFECTS OF L-PHENYLALANINE ON THE RADIATION SYNTHESIS OF POLY(N,N'-METHYLENEBISACRYLAMIDE-co-4-VINYLPYRIDINE)(MICRO)GELS

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Chinese Journal of Polymer Science 2005年第6期23卷 643-650页

The effects of L-phenylalanine （L-Phe） on the synthesis ofpoly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine）（poly（Bis-co-4-VP））（micro）gels by γ-ray irradiation were studied. The addition of L-Phe could not only decrease the gelation dose （Dg） of the synthesis obviously, but also transform the morphology of copolymer from microgel to gel. In addition, the swelling ability of the （micro）gels was also affected in the presence of L-Phe. The decrease of Dg was ascribed to the effect of pH, while the transformation of the morphology was ascribed to the effect of L-Phe on the stability of the poly（Bis-co-4-VP） microgel. Such an effect was confirmed further as compared with the effects of L-alanine, L-glutamic acid, L-arginine, sulfuric acid and aqueous ammonia.

关键词： L-Phenylalanine γ-Ray irradiation Gelation dose Morphology transformation (Micro)gel

ON THE ONE-SIDED LOGARITHMIC LAW FOR ARRAYS

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Systems Science and Mathematical Sciences 1999年第2期12卷 123-132页

作者： QI Yongcheng(department of Probability and Statistics, peking university, beijing 100871, china) 北京大学概率统计系北京

This paper studies the one-sided logarithmic law for arrays of independent random variables and derives the necessary and sufficient condition for it in the case where the random variables are lid.

关键词： Logarithmic law array of random variables.

THE RIEMANN-HILBERT BOUNDARY VALUE PROBLEM FOR FIRST ORDER COMPLEX EQUATIONS OF MIXED TYPE

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Systems Science and Mathematical Sciences 1999年第4期12卷 357-365页

作者： WEN Guochun(department of Mathematics, peking university, beijing 100871, china) 北京大学数学系北京

In this Paper the Riemann--Hilbert boundary value problem for first orderquasilinear complex equations of mixed (elliptic- hyperbolic ) type is discussed. Firstly, therepresentation theorem is given, afterwards by using the method of successive iterations,the existence and uniqueness of solutions for the above problem are proved. In [1], *** discussed the Tricomi problem for some linear mixed equation of second order,which can be derived from the results of the present paper.

关键词： Riemann-Hilbert problem mixed complex equations uniqueness and existence.

Dual Space, Carleson Measure and Sequence Interpolation on A^p(φ)(0

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Acta Mathematica Sinica,English Series 1994年第2期10卷 192-201页

作者： Xiao Jie department of Mathematics peking university beijing, 100871 china

Let D={z∈: |z|<1} and φ be a normal function on [0, 1). For p∈(0, 1) such a function φ is used to define a Bergman space A^p(φ) on D with weight φ~p(|·|)/(1-|·|~2). In this paper, the dual space of A^p(φ) is ... 详细信息

Let D={z∈: |z|2). In this paper, the dual space of A^p(φ) is given, four characteristics of Carleson measure on A^p(φ) are obtained. Moreover, as an application, three sequence interpolation theorems in A^p(φ) are derived.

关键词： Carleson Measure and Sequence Interpolation on A~p Dual Space p<1 Math

Pole assignment in descriptor periodic systems

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Science china Mathematics 2005年第10期48卷 1309-1332页

作者： FAN Hung-Yuan~1 LIN Wen-Wei~1 & XU Shufang~2 1. department of Mathematics,Tsing Hua university,Hsinchu 30043,china 2. LMAM,School of Mathematical Sciences,peking university,beijing 100871,china 1. department of Mathematics Tsing Hua University 30043 Hsinchu China 2. LMAM School of Mathematical Sciences Peking University 100871 Beijing China

In this paper a pole assignment problem is considered for the descriptor linear discrete-time periodic systems, which is using the periodic proportional-derivative feedback to modify a given system such that the closed loop system has a specified selfconjugate set of eigenvalues. It is shown that the complete reachability of an open loop periodic system is equivalent to the possibility of assigning an arbitrary set of the eigenvalues to the system by choosing the suitable periodic proportional-derivative feedback.A computational approach is also proposed to solve the problem, which uses the reliable numerical techniques based on the orthogonal transformations. Numerical examples are presented to illustrate the effectiveness of the proposed approach.

关键词： descriptor linear periodic system, pole assignment, proportional and derivative feedback, numerical method, periodic Schur decomposition.