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A NOVEL INTERPRETATION OF CONCENTRATION DEPENDENCE OF VISCOSITY OF DILUTE POLYMER SOLUTION 被引量:5
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作者 Yan Pan Rong-shi Cheng College of Material Science and Engineering, South China University of Technology, Guangzhou 510641, China College of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2000年第1期57-67,共11页
The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association... The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of a new concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined as the molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertible with the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association. The concept of self-association allows us to predict the existence of a boundary concentration C-s(dynamic contact concentration) which divides the dilute polymer solution into two regions. 展开更多
关键词 SELF-ASSOCIATION polymer solution VISCOSITY concentration dependence
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STUDY ON THE CONCENTRATION DEPENDENCE OF ORIENTATION OF POLYSTYRENE ON SILVER BY THE SERS TECHNIQUE
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作者 Dong-hui Zhang Jin-gui Qin +2 位作者 Jing-shu Shen You Wang Wan-jun Liu Department of Chemistry, Wuhan University, Wuhan 430072, China Polymer Physics Laboratory, Institute of Chemistry, Chinese Academy of Sciences Beijing 100080, China 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2000年第2期177-180,共4页
Polystyrene films were adsorbed onto a silver surface from dichloromethane solutions with concentrations of 0.1 to 12 wt%, and then studied by the surface enhanced Raman technique. A critical concentration for coil in... Polystyrene films were adsorbed onto a silver surface from dichloromethane solutions with concentrations of 0.1 to 12 wt%, and then studied by the surface enhanced Raman technique. A critical concentration for coil interpenetration was observed. 展开更多
关键词 surface enhanced Raman scattering (SERS) POLYSTYRENE concentration dependence
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Concentration and Temperature Dependence of Electrical Conductivity in Thermally Stable Chromium Polyacrylate 被引量:2
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作者 S. U.Rehman M.Siddique and Farid A.Khwaja(Materials Research Laboratory, Dept. of Physics, Quaid-i-Azam University, Islamabad, Pakistan)M.S.Zafar(Dept. of Physics, University of the Punjab, Lahore, Pakistan) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1995年第6期443-446,共4页
Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows depende... Electrical conductivity of chromium polyacrylate with dopant concentration 30, 40 and 50 wt-% of chromium has been measured over a broad range of temperatures (303 K to 383 K).The electrical conductivity shows dependence on temperature, as well as, level of doping. The conductivity is considered to be due to thermal hopping motion of localized charge carriers,which are believed to be polarons, in the temperature range 303 K to 323 K and for T>343 K,whereas. it is metal-like in the temperature range 323 K to 343 K 展开更多
关键词 concentration and Temperature dependence of Electrical Conductivity in Thermally Stable Chromium Polyacrylate
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Two Dimensional Cahn-Hilliard Equation with Concentration Dependent Mobility and Gradient Dependent Potential 被引量:1
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作者 HUANG RUI YIN JING-XUE WANG LIANG-WEI 《Communications in Mathematical Research》 CSCD 2011年第2期156-168,共13页
In this paper we consider the initial boundary value problem of Cahn-Hilliard equation with concentration dependent mobility and gradient dependent potential. By the L^P type estimates and the theory of Morrey spaces,... In this paper we consider the initial boundary value problem of Cahn-Hilliard equation with concentration dependent mobility and gradient dependent potential. By the L^P type estimates and the theory of Morrey spaces,we prove the Holder continuity of the solutions.Then we obtain the existence of global classical solutions.The present work can be viewed as an extension to the previous work on the Cahn-Hilliard equation with concentration dependent mobility and potential. 展开更多
关键词 Cahn-Hilliard equation concentration dependent mobility gradient de- pendent potential
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Luminescence Properties of Tb^(3+)-Doped LuAG Films Prepared by Pechini Sol-Gel Method 被引量:5
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作者 游宝贵 尹民 +2 位作者 张慰萍 郭海 林林 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第6期745-748,共4页
Lu3Al5O12(LuAG) thin films with different Tb^3+ concentration were prepared on carefully cleaned (111 ) silicon wafer by a Peehini process and dip-coating technique. Heat treatment was performed in the temperatur... Lu3Al5O12(LuAG) thin films with different Tb^3+ concentration were prepared on carefully cleaned (111 ) silicon wafer by a Peehini process and dip-coating technique. Heat treatment was performed in the temperature range from 800 to 1100 ℃. The crystal structure was analyzed by XRD. The results show that LuAG film starts to crystallize at about 900 ℃, and the particle size increases with the sintering temperature. Excitation and emission spectra of Tb^3+ doped LuAG films were measured. The effects of heat-treatment temperature and doping concentration of Th3 + on the luminescent properties were also investigated. For a comparison study, Th^3+-doped LuAG powders were also prepared by the same sol-gel method. 展开更多
关键词 SOL-GEL LUAG luminescence properties thin film concentration dependence rare earths
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3-Dimensional Cahn-Hilliard Equation with Concentration Dependent Mobility and Gradient Dependent Potential
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作者 Rui HUANG Yang CAO 《Journal of Mathematical Research and Exposition》 CSCD 2011年第3期402-410,共9页
In this paper we investigate the initial boundary value problem of Cahn-Hilliard equation with concentration dependent mobility and gradient dependent potential.By the energy method and the theory of Campanato spaces,... In this paper we investigate the initial boundary value problem of Cahn-Hilliard equation with concentration dependent mobility and gradient dependent potential.By the energy method and the theory of Campanato spaces,we prove the existence and the uniqueness of classical solutions in 3-dimensional space. 展开更多
关键词 Cahn-Hilliard equation concentration dependent mobility gradient dependent potential.
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Sorption and Leaching Potential of Isoproturon and Atrazine in Low Organic Carbon Soil of Pakistan Under a Wheat-Maize Rotation
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作者 Muhammad TAHIR Anwar Ul HASSAN +4 位作者 Saliha MAQBOOL Brian BARBER William C.KOSKINEN PENG Xinhua David J.MULLA 《Pedosphere》 SCIE CAS CSCD 2016年第5期687-698,共12页
Pesticide leaching is a great threat in low organic carbon soils when subjected to improper irrigation scheduling.Limited data are available on the sorption and leaching potential of pesticides in agricultural soils o... Pesticide leaching is a great threat in low organic carbon soils when subjected to improper irrigation scheduling.Limited data are available on the sorption and leaching potential of pesticides in agricultural soils of Pakistan with low soil organic carbon(SOC).Lysimeter and field studies were conducted with and without manure application at two irrigation levels in a wheat-fallowmaize rotation in Faisalabad,Punjab,Pakistan.Isoproturon was applied to wheat 55 d after sowing at 1 kg active ingredient(a.i.)ha^(-1),while atrazine was sprayed on maize 30 d after sowing at 0.774 kg a.i.ha^(-1).Soil was sampled from three depths(0-35,35-70,and 70-110 cm) for the field study and four depths(0-35,35-70,70-115,and 115-160 cm) for the lysimeter study,280 and 65 d after application of isoproturon and atrazine,respectively.The soil-water partition coefficients(K_d) of isoproturon and atrazine ranged from 0.3 to 1.2 and 0.4 to 1.5 L kg^(-1),respectively,and increased linearly with increase in SOC contents.The organic carbon-normalized soil-water partition coefficient(K_(oc)) of isoproturon and atrazine averaged 246.1 and 184.9 L kg^(-1),respectively,being higher with low spiking concentration.Isoproturon residues measured 280 d after application ranged from 2.1% to 3.6% of the applied mass in the lysimeter study and from 1.5% to 3.1% under field conditions.Atrazine residues 65 d after application ranged from only 0.62% to 0.78% and from 0.88% to 0.82% in the lysimeter and field studies,respectively.The lowest levels of residues for both pesticides were observed with frequent irrigation applied to manure-amended soil.A pesticide leaching risk screening tool,the ground water ubiquity score(GUS),indicated that in the absence of manure under both irrigation levels,isoproturon has a leaching potential(GUS = 2.8),while with the application of manure it has a very low leaching risk.Atrazine GUS ranged from 1.7 to 1.9,indicating a very low risk of leaching. 展开更多
关键词 concentration dependent sorption irrigation MANURE leaching risk assessment PESTICIDE
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