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Predictive Model for Dermal Exposure Assessment
Published in Rhoda G.M. Wang, Water Contamination and Health, 2020
Annette L. Bunge, Gordon L. Flynn, Richard H. Guy
Recently, Flynn (13) compiled a large data base (—90 values) of permeability coefficients through human skin following exposure to aqueous solutions. The results were analyzed empirically using the rationale articulated in the approach of Kasting et al. (8). Flynn also recognized the importance of molecular size in his analysis and divided the data set, somewhat arbitrarily, into “low-molecular-weight” and “high-molecular-weight” groupings. The permeability coefficients were also classified according to chemical polarity: (a) a large intermediate group, for which an essentially linear dependence of permeability upon octanol-water partition coefficient (Kocl) was apparent; (b) a subset of very polar chemicals, the K™sc values of which were similar and were greater than those predicted by a linear extrapolation of the K™sc versus Koct dependence exhibited by the first group; and (c) a collection of very hydrophobic substances of high (but, again, essentially Koct independent) KpSC. Empirical algorithms were then set out to predict permeability coefficients from partition coefficients and molecular weights.
Extraction of Organic Pollutants and Sample Cleanup
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
Highly porous and granular aluminum oxide (available in three pH ranges: acidic, neutral, and basic) is used in column chromatography. Analytes are separated from the interfering compounds by virtue of their different chemical polarity.
Application of Thermal Desorption–Mass Spectrometry for the Analysis of Environmental Pollutants
Published in Leo M. L. Nollet, Dimitra A. Lambropoulou, Chromatographic Analysis of the Environment, 2017
Steven Sai Hang Ho, Judith C. Chow, Jian Zhen Yu, John G. Watson, Jun-Ji Cao, Yu Huang
With capillary GC, organic compounds in aerosol samples are separated according to their physical (boiling point) and chemical (polarity) properties before quantification by MS. Chromatographic separation prior to FID or MS detection minimizes interferences from coexisting species.
Preparation of temperature-sensitive slow-release snowmelt agent by UV-irradiation grafting method
Published in Road Materials and Pavement Design, 2023
ShengYue Wang, DanNi Guo, RuPeng Tian
The phenomenon can be understood as follows, generally, snowmelt salt has high moisture absorption, and melted salt water has high chemical polarity, which can easily lead to the separation of asphalt film outside aggregate, and then reduce the water stability of the mixture. Secondly, the precipitation of snowmelt agent will increase the micro porosity of binder in the mixture and reduce the mechanical strength of the mixture. Here, in the preparation of TSSF, the surface of the carrier has been subjected to waterproof pretreatment. These waterproofing membranes can effectively prevent the snowmelt carrier from absorbing water and reduce the reduction of the water stability of the asphalt mixture. In addition, due to a high adhesion property of bamboo powder particles, the adhesion property between aggregate and asphalt was further enhanced, which further prevented the spalling of aggregate under the action of dynamic water scour, and improved the water stability of asphalt mixture to a certain extent.
Examination of physical property degradation due to severe short-term ageing and effect of hydrated lime as antioxidant in asphalt mixture
Published in Road Materials and Pavement Design, 2019
Sungun Kim, Junan Shen, Sungjin Lee, Yeongsam Kim, Kwang W. Kim
For the HL, 1.5% by weight of mix was used and the corresponding amount of mineral filler was subtracted. Although, no effect of HL or KL was found on ageing just after mixing before SA (Kim et al., 2016), the effect was found after SA treatments. The HL is known to be active filler in reducing age-hardening because of the high disperse-ability of fine powder having chemical polarity and high porosity (European Lime Association, 2011; Lesueur, Petit, & Ritter, 2013; Little, Epps, & Sebaaly, 2006). It is known that the HL particle reacts chemically with the acids of the bitumen and the high porosity contributes to disturbing aggregation of asphaltene. The HL has higher Rigden voids, generally between 60% and 70% with 65% on average (Lesueur, 2010), than mineral fillers, such as most limestone fillers of 28–45%.
Synthesis of sawdust carbon supported nickel nanoparticles and its application in upgrading heavy crude oil
Published in Petroleum Science and Technology, 2021
Yi-Tang Zhong, Xiao-Dong Tang, Jing-Jing Li, Guang-Fu Qin, Cheng-Xin Xiang
Heavy crude oil with viscosity over 100 mPa·s is defined as heavy crude oil (Li et al. 2014; Shang et al. 2016). There are a lot of heavy components including resins and asphaltenes in heavy crude oil, which proportion is much higher than that of conventional oil. Many heavy hydrocarbon molecules establish strong intermolecular forces, and form three-dimensional clusters in the heavy crude oil. The abundant heteroatomic components of sulfur, nitrogen and oxygen exist in heavy crude oil, and which form C-S, C-N and C-O bonds with carbon, and elevate the chemical polarity of the heavy crude oil molecules (Chen et al. 2009). The root cause of the heavy crude oil high viscosity is the complex macromolecular hydrocarbon and the internal intermolecular forces (Li et al. 2019a).