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Road effects on vegetation composition in a saline environment

Journal of Plant Ecology 2012年第2期5卷 206-218页

作者： sheng-Lan Zeng Ting-Ting Zhang Yu Gao Bo Li Chang-Ming Fang s.luke flory Bin Zhao Coastal Ecosystems Research station of the Yangtze River Estuary Ministry of Education Key Laboratory for Biodiversity Science and Ecological EngineeringInstitute of Biodiversity ScienceFudan University220 Han Dan RoadShanghai 200433P.R.China Department of Biology Indiana University1001 East 3rd StreetBloomingtonIN 47405USA

Aims Road effects from maintenance and traffic have the potential to alter plant communities,but the exact relationships between these effects and changes in plant community composition have not often been studied in diverse *** determine the direction and level of community composition changes in saline environment due to road effects,we conducted a study along roads of different ages and in nearby non-road(***)areas in the Yellow River Delta,***,to potentially elucidate the mechanisms underlying the changes in the richness and composition of plant communities along roads,we evaluated physiochemical changes in soil of roadside and non-road *** Floristic and environmental data were collected along roadside of different ages and nearby non-road *** evaluate plant communities at each site,six 2 m 32 m quadrats were placed at 3-m intervals along roads and six quadrats were arranged randomly in non-road *** determine the difference in plant community composition betweenroadside andnon-road areas,wemeasuredspecies richness and the abundance of each species,examined species turnover and floristic dissimilarity between the two areas and positioned plant species and sites in an abstract multivariate *** community(species richness,percentage of halophytes)and soil physicochemical properties(pH,salinity,moisture content,bulk density,nitrate and ammonium nitrogen concentration)were compared between roadside and non-road areas(young roadside *** non-road areas,old roadside *** non-road areas)by using *** and ordination techniques were used to examine the relationship between vegetation and related environmental variables in both roadside and non-road *** Findings For both the young and old roadside areas,species richness in roadside areas was significantly higher than in non-road areas and high floristic dissimilarity values indicated that roadside and non-roa

关键词： road effect salinization species composition vegetation–environment relationships

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Correlates of long-term physical activity adherence in women

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Journal of sport and Health science 2017年第4期6卷 434-442页

作者： Haichun sun Cheryl A. Vamos sara s.B. flory Rita DeBate Erika L. Thompson Jennifer Bleck Department of Teaching and Learning College of Education University of South Florida Tampa FL 33620 USA Department of Community and Family Health College of Public Health University of South Florida Tampa FL 33612 USA

Background: Little is known about the factors that may influence women's adherence to moderate-to-vigorous physical activity(MVPA) using longitudinal data. The purpose of this study was to examine the correlates of long-term physical activity(PA) participation among ***: Female data from Waves I, III, and IV(n = 5381) of the National Longitudinal study of Adolescent to Adult Health(Add Health) were used for the analysis. The outcome of PA adherence was operationalized as(1) consistently physically active(at least 5 instances during the week)in both Waves III and IV(during adulthood), and(2) consistently not physically active or only physically active in either Wave III or IV. Predictor variables from Wave I(during adolescence) included race/ethnicity, PA level, self-perception of being physically fit, general health status, attempt to change weight, parents' income level, parents' education, well-being, depression, access to PA resources, days of physical education(PE), and grade level. Crude and adjusted logistic regression models were utilized to estimate the adjusted odds ratio(a OR) and 95% confidence interval(95%CI) for the outcome ***: PA levels during adolescence significantly predicted PA adherence(a OR = 1.67, 95%CI: 1.35–2.05). Additionally, wanting to lose weight(a OR = 1.49, 95%CI: 1.20–1.85), using fitness center in the neighborhood(a OR = 1.29, 95%CI: 1.05–1.58), and having 5 days of PE a week(a OR = 1.48, 95%CI: 1.09–2.02) were significant predictors. Women who did not perceive being physically fit(a OR = 0.65, 95%CI: 0.44–0.95)and Black, non-Hispanics(a OR = 0.60, 95%CI: 0.44–0.82) were less likely to adhere to ***: The findings suggested that physically active adolescents were more likely to become active adults. Future research should address interventions(e.g., PE program, community resources) that may promote lifetime PA in women, with the goal of decreasing morbidity and mortality.

关键词： Females Longitudinal Moderate-to-vigorous physical activity social ecological frameworks

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Mesoscale modeling of microgel mechanics and kinetics through the swelling transition

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Applied Mathematics and Mechanics(English Edition) 2018年第1期39卷 47-62页

作者： s.NIKOLOV A.FERNANDEZ-NIEVEs A.ALEXEEV Woodruff school of Mechanical Engineering Georgia Institute of Technology school of Physics Georgia Institute of Technology

The mechanics and swelling kinetics of polymeric microgels are simulated using a mesoscale computational model based on dissipative particle dynamics. Microgels are represented by a random elastic network submerged in an explicit viscous solvent. The model is used to probe the effect of different solvent conditions on the bulk modulus of the microgels. Comparison of the simulation results through the volume phase transition reveals favorable agreement with flory-Rehner＇s theory for polymeric gels. The model is also used to examine the microgel swelling kinetics, and is found to be in good agreement with Tanaka＇s theory for spherical gels. The simulations show that, during the swelling process, the microgel maintains a nearly homogeneous structure, whereas deswelling is characterized by the formation of chain bundles and network coarsening.

关键词： soft matter dissipative particle dynamics micromechanics hydrogels

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Analogy between adsorption and sorption： An elementary mechanistic approach. I. Monolayer adsorption and sorption without solvent cluster formation

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Chinese Journal of Chemical Engineering 2017年第12期25卷 1740-1749页

作者： Pierre schaetzel sébastien Thomas Hasna Louahlia Gualous Laboratoire Universitaire des sciences Appliquées de Cherbourg Université de Caen IUT de Caen Boulevard Marechal Juin 14032 Caen cedex France Institut de chimie et procédés pour l'énergie l'environnement et la santé Université de Strasbourg 25 rue Becquerel 67087 Strasbourg cedex 2 France

The elementary mechanistic model of adsorption and sorption is based on a simple hypothesis： the adsorption sites are uniformly distnbuted on the surface of the pore walls in the adsorbent, the sorption sites are uniformly distributed in the volume of the polymer. In this first paper we will analyze the simple case where one solute molecule is only allowed to occupy a single adsorption or sorption site. A common elementary occupation law of the free sites is assumed： the differential increase of the number of the adsorbed/sorbed molecules is proportional to the differential increase of the activity of the solute and the concentration of the free （non-occupied） sites in the solid. The proportionality coefficient is called affinity coefficient depending on the solid/solute couple and on the temperature and independent of the concentration of the solute. In adsorption the concentration of the free sites is a surface concentration on the pore walls and in sorption it is expressed by the molarity. The simple monolayer adsorption law of Jovanovic is obtained： n = no（1 - e KP） where n is the number of moles adsorbed when the pressure is P. no is the total number of adsorption sites and K the affinity coefficient for adsorption. The sorption law writes： a = 1/k [Ф/1-Ф] ＋ 1-r/k In [1 ＋ 1/r Ф/1-Ф] where Ф, r and k hold respectively for the volume fraction of the solvent in the polymer, for the ratio of the molar volumes of the solvent to the elementary polymer chain containing one single adsorption site and for the sorption affinity coefficient. The confrontation of these equations to experimental isotherms is satisfactory in comparison with the classical Langmuir and flory-Huggins equations： the best results are obtained for adsorption of vapors on a 5A zeolite and for all analyzed sorption results.

关键词： Adsorption isotherms sorption isotherms flory-Huggins theory Langmuir equation

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VAPOR-LIQUID EQUILIBRIA OF POLYMER sOLUTION UsING UNIQUAC

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Chinese Journal of Chemical Engineering 1993年第3期1卷 29-36页

作者：温浩 Helle s.Elbro Institut for Kemiteknik Danmarks Tekniske Hφjskole2800 LyngbyDanmark

The UNIQUAC excess Gibbs energy model of Abrams and Prausnitz(1975)is extended to represent thevapor-liquid equilibria of polymer solution with only two adjustable *** on the application ofthe staverman-Guggenheim and the flory-Huggins combinatorial contribution in the UNIQUAC model are givenin this *** UNIQUAC model with either staverman-Guggenheim or flory-Huggins combinatorial expres-sion presents results with about the same accuracy for polymer *** between the UNIQUAC model and the flory equation show that theUNIQUAC model can give some better results than the flory equa-tion in general.

关键词： polymer solution UNIQUAC model VLE correlation polymer databank

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Miscibility Behavior of Polyacrylamides Poly(Ethylene Glycol)Blends:flory Huggins Interaction Parameter Determined by Thermal Analysis

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Journal of Modern Physics 2013年第7期4卷 45-51页

作者： Maria Elisa s.R.silva Valdir Mano Raquel R.J.Pacheco Roberto F.s.Freitas Department of Chemical Engineering Federal University of Minas GeraisBelo HorizonteBrazil Department de Natural sciences Federal University of Sao Joao del ReiSao Joao del ReiMinas GeraisBrazil

Blends of polyacrylamide—PAM, poly(N-isopropylacrylamide)—PNIPAAm, poly(N-tert-butylacrylamide)—PTBAA, poly(N,N-dimethylacrylamide)—PDMAA and poly(N,N-diethylacrylamide)—PDEAA with poly(ethylene glycol)— PEG were prepared by casting in methanol and water at concentrations of 20 wt%, 40 wt%, 60 wt%, and 80 wt% in PEG. The miscibility of the components was studied by Differential scanning Calorimetry—DsC. All blend systems are characterized by a single glass transition temperature (Tg), close to the Tg of the amorphous component. The Hoffman Weeks method was used to determine equilibrium melting temperature (Tm) data. The determination of the melt point depression of the blends allowed the calculation of flory-Huggins interaction parameter (χ12) of the two polymers in the melt, by using the Nishi Wang equation. The interaction parameters, calculated for all the blends, are slightly negative and close to zero, suggesting a partial miscibility between the components.

关键词： Polyacrylamides Poly(Ethylene Glycol) Polymer Blends flory-Huggins Interaction Parameter Differential scanning Calorimetry

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THE EFFECTs OF IRRADIATION ON THE THERMAL PROPERTIEs OF sEMI-CRYsTALLINE POLYAMIDEs

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Chinese Journal of Polymer science 1985年第3期 234-243页

作者：金熹高,Thomas s.Ellis,Frank E.Karasz Institute of Chemistry Academia sinica Beijing Department of Polymer science and Engineering University of Massachusetts. U.s. A. Department of Polymer science and Engineering University of Massachusetts. U.s. A.

Irradiation crosslinking of semi-crystalline polyamides was performed by high energy electronswith various dosages. It is known that the melting behavior of the polymers after irradiation is acomplex phenomenon. In company with the wide angle X-ray diffraction and DsC data of irradiatedand unirradiated polyamides it is possible to develop the local order and perfection of the crystallinitiesslightly which resulted from introduction of intermolecular crosslinking in amorphous region, incl-uding in amorphous-crystalline interface and crystalline defect regions due to irradiation. It canbe explained that slight increase of melting temperature （Tm） and heat of fusion （△H_f） with increasingdosage for both of higher crystallinity nylon 4 and nylon 6. For irradiated lower crystallinity nylons,in contrast, the Tmand △H_f decrease obviously with increasing dosage. In this case, radiation cross-linking "freeze in" the pre-existing morphology, and then the prevention for reorganization duringheating is a dominant effect. The Tmfrom the second melting for all of the samples were depressed,corresponding with flory theory. Therefore the crosslinks imposed on the molecules restrainedthe molecular mobility, and that not only depresses the crystallinity but also increases the imperfec-tion of crystallites when the radiated polymer melted and then recrystallized. These are also reflectedin the depression of heat and entropy of fusion as well as the appearance of double melting peakson the DsC thermograms.

关键词： nylon THE EFFECTs OF IRRADIATION ON THE THERMAL PROPERTIEs OF sEMI-CRYsTALLINE POLYAMIDEs

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硬脂酸酯高温下在PVC中的溶解度

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聚氯乙烯 1982年第3期 168-170页

作者： G.Pezzin ,G.Ceccorulli ,M.Pizzoli ,s.scandola ,G.Crose ,赵以正上海化工厂

引言在高温下关于低分子量物质(诸如增塑剂、润滑剂、和其他助剂)在PVC中的溶解度或热力学的相互作用参数仅有为数极少的报导。从热降价,交联的PVC的溶胀中Doty和Zable早就获得在53℃和76℃下,50种液体长期flory—Hugginsx参数。采用... 详细信息

引言在高温下关于低分子量物质(诸如增塑剂、润滑剂、和其他助剂)在PVC中的溶解度或热力学的相互作用参数仅有为数极少的报导。从热降价,交联的PVC的溶胀中Doty和Zable早就获得在53℃和76℃下,50种液体长期flory—Hugginsx参数。采用该方法获得高增塑剂浓度的x值,并假定聚合物的结晶度为“零”。

关键词： PVC 助剂硬脂酸十八(烷)酸饱和脂肪酸高温下干混料溶解度溶解系数

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缩聚-裂解反應動力学的理论分析

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化学学报 1956年第4期 271-287页

作者：唐敖慶江元生东北人民大学化学系

本文討論AB型,AA和BB型以及AA和BC型分子间的缩聚-裂解反應,由動力学方程出發,得到这三种类型反應过程中高聚分子的分佈情况,并求得几种不同反應條件下的缩聚度p和q是何种時间的函数,利用它们和实验数值比較,可以求得縮聚反應速度常数K... 详细信息

本文討論AB型,AA和BB型以及AA和BC型分子间的缩聚-裂解反應,由動力学方程出發,得到这三种类型反應过程中高聚分子的分佈情况,并求得几种不同反應條件下的缩聚度p和q是何种時间的函数,利用它们和实验数值比較,可以求得縮聚反應速度常数K和水解反應速度常数k-1,并在AA和BC型分子间的反應中,可以求得K＇和K″的此值,藉以比较官能團B和C的活潑度。还討論了三种平均分子量的表示式、数值以及它们相互的比值,後者僅在没有水解作用的情况下,才和flory的结果相同。

关键词：方程代表勤力速度常数分子代入平均分子量函数缩聚度力拳基本假定唐敖

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