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FORMATION OF MESOGLOBULES BY POLY(N,N-DIETHYLACRYLAMIDE)CHAINS IN DILUTE SOLUTIONS

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Chinese Journal of Polymer Science 2009年第4期27卷 561-567页

作者：张广照 Department of Chemical Physics University of Science and Technology of China

The association of poly(N,N-diethylacrylamide)(PDEA) chains has been investigated by a combination of static and dynamic laser light scattering(LLS).Unlike poly(N-isopropylacrylamide)(PNIPAM),PDEA chains can not form the C=O…H-N hydrogen *** results demonstrate that a limited number of PDEA chains collapse and associate into metastable globules in dilute *** heating rate has great effect on the mesoglobule *** formation of such mesoglobules is attributed to the competition between intra...

关键词： Mesoglobule light scattering Microcalorimetry

Effect of sintering temperature on microstructure and electrical properties of Sr_(1-x)(Na_(0.5)Bi_(0.5))_(x)Bi_(2)Nb_(2)O_(9) solid solutions

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Journal of Advanced Ceramics 2014年第1期3卷 17-30页

作者： Hana NACEUR Adel MEGRICHE Mohamed EL MAAOUI Laboratory of Applied Mineral Chemistry Department of ChemistryFaculty of SciencesUniversity Tunis ElManarCampus 2092TunisTunisia

In this study,we investigated the effect of sintering temperature on densification,grain size,conductivity and dielectric properties of Sr_(1-x)(Na_(0.5)Bi_(0.5))_(x)Bi_(2)Nb_(2)O_(9) ceramics,prepared by hydrothermal *** were sintered at different *** increased with sintering temperature,reaching up to 96%at 800℃.A grain growth was observed with increasing sintering *** spectroscopy analyses of the sintered samples at various temperatures were *** in dielectric constant and in Curie temperature with sintering was *** conductivity and activation energy were calculated and attributed to the microstructural factors.

关键词： ceramics sintering light scattering dielectric properties

THE ADSORPTION OF LINEAR POLY(N-ISOPROPYLACRYLAMIDE)CHAINS ON SURFACTANT-FREE POLYSTYRENE NANOPARTICLES

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Chinese Journal of Polymer Science 1999年第6期17卷 595-601页

作者：吴奇 Department of Chemistry The Chinese University of Hong Kong Shatin N T. Hong Kong China The Open Laboratory of Bond Selective Chemistry Department of Chemical Physics University of the Science and Technology of China Hefei 230026 China

The adsorption of linear poly(N-isopropylacrylamide) (PNIPAM) chains on surfactant-free polystyrene (PS) nanoparticles was used as a model system to study the hydrophobic adsorption of polymer on the surface, because the hydrophobility of PNIPAM can be continuously varied by a small temperature change. The adsorption was investigated by a combination of static and dynamic laser light scattering (LLS) measurements. In static LLS, the absolute excess scattered light intensity led to the amount of PNIPAM adsorbed on the surface. In dynamic LLS, the hydrodynamic thickness of the adsorbed PNIPAM layer was accurately measured. For a given particle concentration, the adsorption increases as the PNIPAM concentration and the incubation temperature increase. The average density of the adsorbed PNIPAM layer is reciprocally proportional to the number of the PNIPAM chains on the surface, revealing a simple scaling of the chain density distribution. The adsorption follows the Langmuir's isotherm. The enthalpy change estimated from the adsorption at 25 degrees C and 30 degrees C is slightly positive, indicating that the adsorption involves the coil-to-globule transition of the chains on the surface.

关键词： poly(N-isopropylacrylamide) polystyrene nanoparticles surface adsorption of polymers light scattering

New Receiving Mode of Extinction for Determining Particle Size and Density without Convex Lens

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Chinese Journal of Lasers 2002年第1期11卷 46-51页

作者： WU Weiliang CHEN Hanping (School of Power and Energy Engineering, Shanghai Jiao Tong University, Shanghai 200030, China) CAI Xiaoshu WANG Naining (School of Power and Energy Engineering, University of Shanghai for Science and Technology, Shanghai 2 School of Power and Energy Engineering Shanghai Jiao Tong University 上海 200030 School of Power and Energy Engineering University of Shanghai for Science and Technology 上海 200093

In this article a new receiving mode for scattering light by particle is theoretically discussed. Using this receiving mode the convex lens can be omitted during determining the extinction of particle. Therefore the extinction coefficient of sphere particles is redefined by extrapolating the conventional one. In terms of the calculation results of light scattering the definition of near-field extinction coefficient of a swarm particle is depicted. Through the error analysis it is proved that the error coming from the new definition of extinction coefficient is acceptable for engineering application. In addition, a technique for determining the particle size and density is presented in this article and the advantage using this receiving mode is described.

关键词： extinction of particle light scattering fluctuation method particle size particle density

Reaction-induced phase separation in rubber-modified epoxy resin

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Science China Chemistry 1997年第1期40卷 15-23页

作者：张剑文张红东严栋周红卫杨玉良 Institute of Macromolecular Science Fudan UniversityLaboratory of Molecular Engineering of PolymersState Education CommissionShanghai 200433China

The phase separation mechanism,and structure development during curing of epoxy with a novel liquid rubber-ZR were investigated by time-resolved light scattering,optical microscope and differential scanning calonmetry (DSC) The mixture loaded with curing agent was a single-phase system in the early stage of *** the cure reaction proceeded,phase separation took place via the spinodal decomposition induced by polymerization of epoxy *** was supported by the characteristic change of light scattering profile with curing *** reaction plays an important role in the progress of phase *** bigger the cure reaction rate is,the longer periodic distance will *** overall two-phase structure was basically locked in when the conversion approached 80% estimated by DSC,and finally the co-continuous two-phase structure was successfully obtained.

关键词： polymerization-induced phase separation rubber toughened epoxy resin light scattering curing kinetics

Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions

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Chemical Research in Chinese Universities 2000年第2期16卷 156-162页

作者： ZHANG Lina XU Xiaojuan ZHU RongPing Iijima Hideki 武汉大学湖北武汉 430 0 72 国家标准物质研究中心国家标准物质研究中心北京 1 0 0 0 1 Asahi Chemical Industry Co. 日本 Miyazaki 882 -8847

Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weightaverage molecular weights M w, numberaverage molecular weights M n and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.

关键词： Erwinia gum light scattering SEC Membrane osmometry Viscometry Molecular weight Aggregation

Viscoelasticity of amyloid plaques in transgenic mouse brain studied by Brillouin microspectroscopy and correlative Raman analysis

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Journal of Innovative Optical Health Sciences 2017年第6期10卷 3-16页

作者： Sara Mattana Silvia Caponi Francesco Tamagnini Daniele Fioretto Francesca Palombo Department of Physics and Geology University of Perugia Perugia I-06123Italy Istituto Officina dei Materiali del CNR(CNR-IOM)-Unita di Perugia Department of Physics and Geology University of Perugia Perugia I-06123Italy Hatherly Laboratories Medical School University of ExeterExeter EX44PSUK School of Physics and Astronomy University of Exeter Exeter EX44QLUK

A myloidopathy is one of the most prominent hallmarks of Alkheimer's disease(AD),the leading cause of dementia worldwide,and is characterized by the accumulation of amyloid plaques in the brain *** plaques consist of abnornal deposits mainly composed of an aggregation-prone protein fragment,B-amyloid 140/1-42,into the extracellular *** micro-spectroscopy is an all-optical contactless technique that is based on the interaction between visible light and longitudinal acoustic waves or phonons,giving access to the viscoelasticity of a sample on a subcellular ***,we describe the first application of micromechanical mapping based on Brillouin scattering spectroscopy to probe the stifness of individual amyloid plaques in the hippocampal part of the brain of a B-amyloid overexpressi ng transgenic *** analysis based on Brillouin and Raman microspectroscopy showed that amyloid plaques have a complex structure with a rigid core of B-pleated shoet conformation(B-aryloid)protein sur-rounded by a softer ring-shaped region richer in lipids and other protein *** preliminary results give a new insight into the plaque biophysics and biomechanics,and a valuable contrast mechanism for the study and diagnosis of amnyloidopathy.

关键词： Alzheimer's imaging vibrational spectrosecopy protein misfolding light scattering

PO Analysis for RCS of Nonorthogonal Dihedral Corner Reflectors Coated by RAM

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Journal of Systems Engineering and Electronics 2001年第4期12卷 1-6页

作者：殷红成黄培康 National Electromagnetic scattering Laboratory Beijing 100854 P. R. China

The backscattering radar cross section (RCS) of nonorthogonal dihedral corner reflectors coated by RAM (radar absorbing materials) is formulated by the method of PO (physical optics), where singly, doubly, and triply reflected contributions are considered. The final expressions are analytical and allow for the incidence nonperpendicular to the fold axis of the reflector. The results are compared with ones of MoM (method of moment), which shows that the trend of backscatter pattern of the dihedral corner reflector can be well predicted by this method.

关键词： Computer simulation Directional patterns (antenna) light scattering Method of moments Mirrors Numerical analysis Radar antennas

ZnO hierarchical aggregates： Solvothermal synthesis and application in dye-sensitized solar cells

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Nano Research 2013年第6期6卷 441-448页

作者： Jianxing Shi Yunxin Liu Qing Peng Yadong Li Department of Chemistry Tsinghua University Beijing 100084 China

ZnO hierarchical aggregates have been successfully synthesized by solvothermal methods through reaction of zinc acetate and potassium hydroxide in methanol solution. The shapes of the aggregates were controlled by varying the ratio of Zn2~ and OH- ions in the reaction system, while the size can be tuned from 2μm to 100 nm. Oriented attachment was found to be the main mechanism of the three-dimensional assembly of small ZnO nanocrystallites into large aggregates. The performance of these aggregates in dye-sensitized solar cells （DSCs） indicated that hierarchical structured photoelectrodes can increase energy conversion efficiency of DSCs effectively when the sizes of aggregates match the wavelengths of visible light.

关键词： dye-sensitized solar cells zinc oxide hierarchical aggregate solvothermal synthesis light scattering