Refinement and Extension of COSMO-RS-Trained Fragment Contribution Models for Predicting Partition Properties of C10–20 Chlorinated Paraffin Congeners

2021 ◽  
Author(s):  
Satoshi Endo
Keyword(s):  
Partition Coefficients ◽  
Aqueous Solubility ◽  
Stochastic Algorithm ◽  
Training Set ◽  
Subcooled Liquid ◽  
Conformer Generation ◽  
Model Predictions ◽  
Predicted Values ◽  
Chlorinated Paraffin ◽  
Long Chain

COSMO-RS-trained fragment contribution models (FCMs) to predict partition properties of chlorinated paraffin (CP) congeners were refined and extended. The improvement includes (i) the use of an improved conformer generation method for COSMO-RS, (ii) extension of training and validation sets for FCMs up to C<sub>20</sub> congeners covering short-chain (SCCPs), medium-chain (MCCPs) and long-chain CPs (LCCPs), and (iii) more realistic simulation of industrial CP mixture compositions by using a stochastic algorithm. Extension of the training set markedly improved the accuracy of model predictions for MCCPs and LCCPs, as compared to the previous study. The predicted values of the log octanol/water partition coefficients (<i>K</i><sub>ow</sub>) for CP mixtures agreed well with experimentally determined values from the literature. Using the established FCMs, this study provided a set of quantum chemically based predictions for 193 congener groups (C<sub>10–20</sub>, Cl<sub>0–21</sub>) regarding <i>K</i><sub>ow</sub>, air/water (<i>K</i><sub>aw</sub>), and octanol/air (<i>K</i><sub>oa</sub>) partition coefficients, subcooled liquid vapor pressure (VP) and aqueous solubility (<i>S</i><sub>w</sub>) in a temperature range of 5–45 °C as well as the respective enthalpy and internal energy changes.<br><br>This is a preprint version and has not yet been peer reviewed.

Refinement and Extension of COSMO-RS-Trained Fragment Contribution Models for Predicting Partition Properties of C10–20 Chlorinated Paraffin Congeners

2021 ◽  
Author(s):  
Satoshi Endo
Keyword(s):  
Partition Coefficients ◽  
Aqueous Solubility ◽  
Stochastic Algorithm ◽  
Training Set ◽  
Subcooled Liquid ◽  
Conformer Generation ◽  
Model Predictions ◽  
Predicted Values ◽  
Chlorinated Paraffin ◽  
Long Chain

COSMO-RS-trained fragment contribution models (FCMs) to predict partition properties of chlorinated paraffin (CP) congeners were refined and extended. The improvement includes (i) the use of an improved conformer generation method for COSMO-RS, (ii) extension of training and validation sets for FCMs up to C<sub>20</sub> congeners covering short-chain (SCCPs), medium-chain (MCCPs) and long-chain CPs (LCCPs), and (iii) more realistic simulation of industrial CP mixture compositions by using a stochastic algorithm. Extension of the training set markedly improved the accuracy of model predictions for MCCPs and LCCPs, as compared to the previous study. The predicted values of the log octanol/water partition coefficients (<i>K</i><sub>ow</sub>) for CP mixtures agreed well with experimentally determined values from the literature. Using the established FCMs, this study provided a set of quantum chemically based predictions for 193 congener groups (C<sub>10–20</sub>, Cl<sub>0–21</sub>) regarding <i>K</i><sub>ow</sub>, air/water (<i>K</i><sub>aw</sub>), and octanol/air (<i>K</i><sub>oa</sub>) partition coefficients, subcooled liquid vapor pressure (VP) and aqueous solubility (<i>S</i><sub>w</sub>) in a temperature range of 5–45 °C as well as the respective enthalpy and internal energy changes.<br><br>This is a preprint version and has not yet been peer reviewed.

Construction and Experimental Study of an Elevation Linear Fresnel Reflector

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
J. D. Nixon ◽  
P. A. Davies
Keyword(s):  
Heat Loss ◽  
Thermal Efficiency ◽  
Theoretical Models ◽  
Loss Coefficient ◽  
Heat Transfer Fluid ◽  
Stagnation Temperature ◽  
Model Predictions ◽  
The Difference ◽  
Predicted Values ◽  
Linear Fresnel Reflector

This paper outlines a novel elevation linear Fresnel reflector (ELFR) and presents and validates theoretical models defining its thermal performance. To validate the models, a series of experiments were carried out for receiver temperatures in the range of 30–100 °C to measure the heat loss coefficient, gain in heat transfer fluid (HTF) temperature, thermal efficiency, and stagnation temperature. The heat loss coefficient was underestimated due to the model exclusion of collector end heat losses. The measured HTF temperature gains were found to have a good correlation to the model predictions—less than a 5% difference. In comparison to model predictions for the thermal efficiency and stagnation temperature, measured values had a difference of −39% to +31% and 22–38%, respectively. The difference between the measured and predicted values was attributed to the low-temperature region for the experiments. It was concluded that the theoretical models are suitable for examining linear Fresnel reflector (LFR) systems and can be adopted by other researchers.

Stratospheric ozone depletion - an overview of the scientific debate

1995 ◽  
Vol 19 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Frances Drake
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Scientific Uncertainty ◽  
Perceived Threat ◽  
Stratospheric Ozone Depletion ◽  
Scientific Debate ◽  
Supersonic Transport ◽  
Model Predictions ◽  
Predicted Values

For almost half a century it was widely believed that the photochemistry of the stratosphere and hence ozone distribution were well understoood. As observations revealed a gap between observed and predicted values it was recognized that a number of substances acted as catalysts thereby increasing the destruction of ozone and that humanity could augment those catalysts and affect the ozone layer. Initial concern focused on nitrogen oxides from the exhausts of supersonic transport, but attention switched in the mid-1970s to chlorofluorocarbons (CFCs). Although the theory of anthropogenic ozone depletion by CFCs found widespread scientific support the perceived threat was minimized in particular by successive model predictions downgrading the amount of depletion. The appearance of the ozone hole over Antarctica in the mid-1980s reopened the debate as to whether such depletion was anthropogenic or natural in origin. It also highlighted the model's inadequate treatment of the processes occurring in the stratosphere and the importance of dynamics and radiative transfer in stratospheric ozone destruction. Scientific consensus again favours the anthropogenic depletion of the ozone layer. In conclusion it is considered that the degree of consensus outweighs the image of scientific uncertainty that is often portrayed in relation to the issue of stratospheric ozone depletion.

Vapour pressures, aqueous solubility, Henry’s law constants and air/water partition coefficients of 1,8-dichlorooctane and 1,8-dibromooctane

Chemosphere ◽  
2006 ◽  
Vol 64 (11) ◽  
pp. 1829-1836 ◽  
Author(s):  
Sabine Sarraute ◽  
Ilham Mokbel ◽  
Margarida F. Costa Gomes ◽  
Vladimir Majer ◽  
Hervé Delepine ◽  
...  
Keyword(s):  
Partition Coefficients ◽  
Aqueous Solubility ◽  
Henry's Law ◽  
Henry’S Law ◽  
Henry’S Law Constants ◽  
Henry's Law Constants

Overlooked long-chain chlorinated paraffin (LCCP) contamination in foodstuff from China

2021 ◽  
Vol 801 ◽  
pp. 149775 ◽  
Author(s):  
Lei Ding ◽  
Shiwen Zhang ◽  
Yuting Zhu ◽  
Nan Zhao ◽  
Wenbao Yan ◽  
...  
Keyword(s):  
Chlorinated Paraffin ◽  
Long Chain

Sodic soil reclamation: Modelling and field study

Soil Research ◽  
2001 ◽  
Vol 39 (6) ◽  
pp. 1225 ◽  
Author(s):  
Donald L. Suarez
Keyword(s):  
Management Practices ◽  
Drainage System ◽  
Water Model ◽  
Soil Reclamation ◽  
Sodium Absorption ◽  
Sodic Soils ◽  
Sodium Absorption Ratio ◽  
Model Predictions ◽  
Predicted Values ◽  
Almost Continuous

Reclamation of sodic soils has traditionally been undertaken using calculation of gypsum or Ca requirement assuming 100% exchange efficiency and neglect of the contribution of calcium carbonate in the profile. The UNSATCHEM model is reviewed and then evaluated for its ability to predict field reclamation of a sodic saline soil. The 40-ha field site was initially at an electrical conductivity (EC) of 50 dS/m and a sodium absorption ratio (SAR) of 144 in the top 30 cm. After installation of a drainage system, 24 Mg/ha of gypsum was applied to a depth of 15 cm in the soil. Subsequently, 114 cm of water was applied by almost continuous ponding for 3 months. Model simulations were made based on infiltration of 70–80 cm of water, correcting for the estimated evaporation of 41 cm of water. These infiltration estimates are consistent with the good fit between the measured Cl concentrations after reclamation and the model predicted values after 70–80 cm of infiltrated water. Model predictions of EC and SAR after reclamation gave a satisfactory fit to the measured values. The effectiveness of mixing gypsum to various depths was evaluated in terms of the predicted SAR profiles. Alternative management practices of green manuring in presence of calcite were simulated and appeared feasible. In this instance it appears likely that the field could have been reclaimed either with less water or without the addition of gypsum.

QSPR Studies on Vapor Pressure, Aqueous Solubility, and the Prediction of Water−Air Partition Coefficients

1998 ◽  
Vol 38 (4) ◽  
pp. 720-725 ◽  
Author(s):  
Alan R. Katritzky ◽  
Yilin Wang ◽  
Sulev Sild ◽  
Tarmo Tamm ◽  
Mati Karelson
Keyword(s):  
Vapor Pressure ◽  
Partition Coefficients ◽  
Aqueous Solubility

scholarly journals Development of a continuous evaporation system for an API solution stream prior to crystallization

2021 ◽  
Author(s):  
Phillip Roche ◽  
Roderick Jones ◽  
Brian Glennon ◽  
Philip Donnellan
Keyword(s):  
Steady State ◽  
Bubble Column ◽  
Feed Stream ◽  
Continuous Processing ◽  
Processing Mode ◽  
Model Predictions ◽  
Measured Effect ◽  
Predicted Values ◽  
Rate Of Evaporation ◽  
General Method

A bubble column was investigated as a method to achieve a desired and controllable rate of evaporation of a pharmaceutical solution in continuous processing mode. Applying a developed thermodynamic model to predict the rate of evaporation, all predicted values achieved accuracies within the bounds of instrumentation errors. The model accounted for the measured effect of reduced vapor pressure caused by dissolved solids as a function of their concentration. A general method to obtain accurate measurement of this effect is introduced and applied, improving the accuracy of model predictions. Predicting the rate of evaporation using the developed model, consistent and repeatable evaporation rates ranging from 0.7–6.9 g/min were achieved. Applying the column as a controllable evaporator, the concentration of a dilute feed stream was increased in a single equilibrium stage and coupled to a crystallizer. The configured system achieved a steady state of controllable operation over a duration of 5 hours

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