scholarly journals Model Building on Selectivity of Gas Antisolvent Fractionation Method Using the Solubility Parameter

2019 ◽  
Vol 63 (2) ◽  
pp. 294-302 ◽  
Author(s):  
Máté Mihalovits ◽  
Attila Horváth ◽  
László Lőrincz ◽  
Edit Székely ◽  
Sándor Kemény
Keyword(s):  
Solubility Parameter ◽  
Model Building ◽  
Linear Models ◽  
Optical Resolution ◽  
Solubility Parameters ◽  
Operational Parameters ◽  
Single Term ◽  
Designed Experiment ◽  
Fractionation Method ◽  
Gas Antisolvent

Solubility parameters are widely used in the polymer industry and are often applied in the high pressure field as well as they give the possibility of combining the effects of all operational parameters on solubility in a single term. We demonstrate a statistical methodology to apply solubility parameters in constructing a model to describe antisolvent fractionation based chiral resolution, which is a complex process including a chemical equilibrium, precipitation and extraction as well. The solubility parameter used in this article, is the Hansen parameter. The evaluation of experimental results of resolution and crystallization of ibuprofen with (R)-phenylethylamine based on diastereomeric salt formation by gas antisolvent fractionation method was carried out. Two sets of experiments were performed, one with methanol as organic solvent in an undesigned experiment and one with ethanol in a designed experiment. The utilization of D-optimal design in order to decrease the necessary number of experiments and to overcome the problem of constrained design space was demonstrated. Linear models including dependence of pressure, temperature and the solubility parameter were appropriate to describe the selectivity of the GASF optical resolution method in both sets of experiments.

scholarly journals Gas Antisolvent Fractionation: A New Approach for the Optical Resolution of 4-chloromandelic Acid

2019 ◽  
Vol 63 (2) ◽  
pp. 303-311
Author(s):  
Amit Zodge ◽  
Márton Kőrösi ◽  
János Madarász ◽  
Imre Miklós Szilágyi ◽  
Erzsébet Varga ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Organic Solvent ◽  
Enantiomeric Excess ◽  
Optical Resolution ◽  
Operational Parameters ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Resolution Method ◽  
New Approach ◽  
Gas Antisolvent

A new, rapid optical resolution method of 4-chloromandelic acid is presented using (R)-1-phenylethanamine as the resolving agent. Gas antisolvent fractionation was investigated as the separation method, studying the effect of pressure, temperature and carbon dioxide to organic solvent mass ratio in details. Generally, the method offers green operation using supercritical carbon dioxide as the precipitative agent, and can be less time- and organic solvent-intensive than conventional processes. By upscaling, the possibility of controlling the crystal-morphology might also be improved. At 16 MPa, 40 °C and 7.5 carbon dioxide to methanol ratio 72 % enantiomeric excess was reached in the crystalline product, along a 73 % yield. The resolution efficiency was not affected by any of the operational parameters. Enantiomeric enrichment beyond 90 % can be carried out by repeated resolution of a scalemic mixture of the acid. Solid products were investigated using differential scanning calorimetry, powder X-ray diffraction and scanning electron microscopy confirming the formation of a crystalline (R)-1-phenylethanammonium-4-chloromandelate salt.

scholarly journals modelBuildR: an R package for model building and feature selection with erroneous classifications

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10849
Author(s):  
Maximilian Knoll ◽  
Jennifer Furkel ◽  
Juergen Debus ◽  
Amir Abdollahi
Keyword(s):  
Feature Selection ◽  
Cross Validation ◽  
Model Building ◽  
Linear Models ◽  
Binary Classification ◽  
Ground Truth ◽  
R Package ◽  
Methylation Array ◽  
Survival Difference ◽  
Error Probabilities

Background Model building is a crucial part of omics based biomedical research to transfer classifications and obtain insights into underlying mechanisms. Feature selection is often based on minimizing error between model predictions and given classification (maximizing accuracy). Human ratings/classifications, however, might be error prone, with discordance rates between experts of 5–15%. We therefore evaluate if a feature pre-filtering step might improve identification of features associated with true underlying groups. Methods Data was simulated for up to 100 samples and up to 10,000 features, 10% of which were associated with the ground truth comprising 2–10 normally distributed populations. Binary and semi-quantitative ratings with varying error probabilities were used as classification. For feature preselection standard cross-validation (V2) was compared to a novel heuristic (V1) applying univariate testing, multiplicity adjustment and cross-validation on switched dependent (classification) and independent (features) variables. Preselected features were used to train logistic regression/linear models (backward selection, AIC). Predictions were compared against the ground truth (ROC, multiclass-ROC). As use case, multiple feature selection/classification methods were benchmarked against the novel heuristic to identify prognostically different G-CIMP negative glioblastoma tumors from the TCGA-GBM 450 k methylation array data cohort, starting from a fuzzy umap based rough and erroneous separation. Results V1 yielded higher median AUC ranks for two true groups (ground truth), with smaller differences for true graduated differences (3–10 groups). Lower fractions of models were successfully fit with V1. Median AUCs for binary classification and two true groups were 0.91 (range: 0.54–1.00) for V1 (Benjamini-Hochberg) and 0.70 (0.28–1.00) for V2, 13% (n = 616) of V2 models showed AUCs < = 50% for 25 samples and 100 features. For larger numbers of features and samples, median AUCs were 0.75 (range 0.59–1.00) for V1 and 0.54 (range 0.32–0.75) for V2. In the TCGA-GBM data, modelBuildR allowed best prognostic separation of patients with highest median overall survival difference (7.51 months) followed a difference of 6.04 months for a random forest based method. Conclusions The proposed heuristic is beneficial for the retrieval of features associated with two true groups classified with errors. We provide the R package modelBuildR to simplify (comparative) evaluation/application of the proposed heuristic (http://github.com/mknoll/modelBuildR).

scholarly journals Practical Determination of the Solubility Parameters of 1-Alkyl-3-methylimidazolium Bromide ([CnC1im]Br, n = 5, 6, 7, 8) Ionic Liquids by Inverse Gas Chromatography and the Hansen Solubility Parameter

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1346 ◽  
Author(s):  
Qiao-Na Zhu ◽  
Qiang Wang ◽  
Yan-Biao Hu ◽  
Xawkat Abliz
Keyword(s):  
Gas Chromatography ◽  
Ionic Liquids ◽  
Physicochemical Properties ◽  
Solubility Parameter ◽  
Room Temperature ◽  
Inverse Gas Chromatography ◽  
Retention Volume ◽  
Solubility Parameters ◽  
Hansen Solubility Parameter ◽  
Hansen Solubility

The physicochemical properties of four 1-alkyl-3-methylimidazolium bromide ([CnC1im]Br, n = 5, 6, 7, 8) ionic liquids (ILs) were investigated in this work by using inverse gas chromatography (IGC) from 303.15 K to 343.15 K. Twenty-eight organic solvents were used to obtain the physicochemical properties between each IL and solvent via the IGC method, including the specific retention volume and the Flory–Huggins interaction parameter. The Hildebrand solubility parameters of the four [CnC1im]Br ILs were determined by linear extrapolation to be δ 2 ( [ C 5 C 1 im ] Br ) = 25.78 (J·cm−3)0.5, δ 2 ( [ C 6 C 1 im ] Br ) = 25.38 (J·cm−3)0.5, δ 2 ( [ C 7 C 1 im ] Br ) =24.78 (J·cm−3)0.5 and δ 2 ( [ C 8 C 1 im ] Br ) = 24.23 (J·cm−3)0.5 at room temperature (298.15 K). At the same time, the Hansen solubility parameters of the four [CnC1im]Br ILs were simulated by using the Hansen Solubility Parameter in Practice (HSPiP) at room temperature (298.15 K). The results were as follows: δ t ( [ C 5 C 1 im ] Br ) = 25.86 (J·cm−3)0.5, δ t ( [ C 6 C 1 im ] Br ) = 25.39 (J·cm−3)0.5, δ t ( [ C 7 C 1 im ] Br ) = 24.81 (J·cm−3)0.5 and δ t ( [ C 8 C 1 im ] Br ) = 24.33 (J·cm−3)0.5. These values were slightly higher than those obtained by the IGC method, but they only exhibited small errors, covering a range of 0.01 to 0.1 (J·cm−3)0.5. In addition, the miscibility between the IL and the probe was evaluated by IGC, and it exhibited a basic agreement with the HSPiP. This study confirms that the combination of the two methods can accurately calculate solubility parameters and select solvents.

scholarly journals Tuning the Solubility Parameters of Carbon Nanotubes by Means of Their Adducts with Janus Pyrrole Compounds

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1176
Author(s):  
Daniele Locatelli ◽  
Vincenzina Barbera ◽  
Luigi Brambilla ◽  
Chiara Castiglioni ◽  
Annalisa Sironi ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Solubility Parameter ◽  
Reaction Pathway ◽  
Aqueous Dispersion ◽  
Solubility Parameters ◽  
High Yield ◽  
Primary Amines ◽  
Multiwalled Carbon ◽  
Chemical Structures ◽  
Carbon Efficiency

The solubility parameters of multiwalled carbon nanotubes (CNTs) was tuned via their chemical modification with pyrrole compounds (PyCs), by means of a simple and sustainable methodology. PyCs were synthesized with high atom efficiency through the Paal–Knorr reaction of primary amines with 2,5-hexanedione, in the absence of solvents and catalysts. Methylamine, 1-dodecylamine, 2-amino-1,3-propanediol, and 3-(triethoxysilyl)propan-1-amine were selected. PyCs are characterized by two moieties, the pyrrole ring and the substituent of the nitrogen atom, and can be considered as Janus molecules. The functionalization of CNTs occurred with a high yield by simply heating CNTs and PyC. The whole reaction pathway did not produce any waste and was characterized by a carbon efficiency up to almost 100%. Thanks to the variety of PyC chemical structures, the CNT solubility parameter was modified in a pretty broad range of values, in the expected direction. Stable CNT dispersions were prepared in different solvents. From the aqueous dispersion, coating layers were prepared with high electrical conductivity, larger with respect to a top commercial product. The “pyrrole methodology” reported here is based on one reaction and allows almost infinite variations of the CNT solubility parameter, thus promoting their compatibility with target matrices and allowing the preparation of nanocomposite materials with improved properties. This work thus paves the way for a highly efficient exploitation of CNTs.

Nested Nonlinear Regression Models

2017 ◽  
Author(s):  
Russell Cheng
Keyword(s):  
Regression Models ◽  
Free Choice ◽  
Model Building ◽  
Linear Models ◽  
Nonlinear Models ◽  
Real Data ◽  
Nonlinear Regression Models ◽  
Stepwise Method ◽  
Forward Stepwise ◽  
Nested Regression

Stepwise fitting of nonlinear nested regression models is considered in this chapter. The forward stepwise method of linear model building is used as far as possible. With linear models this is straightforward as there is in principle a free choice of the order that individual terms or factors are selected for inclusion. The only real issue is that sufficient submodels are examined to ensure that those finally selected really are amongst the best. The nonlinear case is not so straightforward, as embeddedness and parameter indeterminacy issues impose restrictions on the order in which steps can be taken to build a valid model, as certain parameters can only be meaningfully included if other specific parameters are definitely present. A systematic way of building valid nonlinear models of increasing complexity is described and illustrated by two examples using real data. A brief review of non-nested model building is also given.

scholarly journals Modelling Tabular Data with an Ordered Outcome

1996 ◽  
Vol 1 (3) ◽  
pp. 1-10
Author(s):  
Vernon Gayle
Keyword(s):  
Model Building ◽  
Linear Models ◽  
Statistical Modelling ◽  
Categorical Variables ◽  
Sociological Research ◽  
Ratio Model ◽  
Ordered Categories ◽  
Continuation Ratio ◽  
Recent Developments ◽  
Log Linear

A large amount of data that is considered within sociological studies consists of categorical variables that lend themselves to tabular analysis. In the sociological analysis of data regarding social class and educational attainment, for example, the variables of interest can often plausibly be considered as having a substantively interesting order. Standard log-linear models do not take ordinality into account, thereby potentially they may disregard useful information. Analyzing tables where the response variable has ordered categories through model building has been problematic in software packages such as GLIM (Aitken et al., 1989). Recent developments in statistical modelling have offered new possibilities and this paper explores one option, namely the continuation ratio model which was initially reported by Fienberg and Mason (1979). The fitting of this model to data in tabular form is possible in GLIM although not especially trivial and by and large this approach has not been employed in sociological research. In this paper I outline the continuation ratio model and comment upon how it can be fitted to data by sociologists using the GLIM software. In addition I present a short description of the relative merits of such an approach. Presenting this paper in an electronic format facilitates the possibility of replicating the analysis. The data is appended to the paper in the appropriate format along with a copy of the GLIM transcript. A dumped GLIM4 file is also attached.

scholarly journals Methods for Determining the Solubility Parameter of Additives for Lubricating Oils

2019 ◽  
Vol 35 (4) ◽  
pp. 1297-1301
Author(s):  
Ioana Stanciu
Keyword(s):  
Solubility Parameter ◽  
Solubility Parameters ◽  
Improved Method ◽  
Lubricating Oils

In this article I have been looking at the determination of the solubility parameter by two methods for an additive KELTAN 4200 used in lubricating oils. To determine the solubility parameter, it is necessary to know the intrinsic viscosities of the polymer in as many solvents with different solubility parameters. Determination of the partial and global solubility parameters was done, first, using the Hansen method, then by an improved method.

Prediction of Solubility Parameters of Lignin and Ionic Liquids Using Multi-resolution Simulation Approaches

2021 ◽  
Author(s):  
Mood Mohan ◽  
Kaixuan Huang ◽  
Venkataramana Pidatala ◽  
Blake Simmons ◽  
Seema Singh ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Molecular Species ◽  
Solubility Parameter ◽  
Solubility Parameters ◽  
Resolution Simulation

The solubility parameter (SP) of a molecular species is a vital feature that evaluates polarity and quantifies the ‘like-seeks-like' principle, which is used in chemistry to screen solvents for dissolution....

scholarly journals Gas Antisolvent Fractionation: a New Method to Obtain Enantiopure Compounds, a Case Study on Mandelic Acid

2018 ◽  
Vol 63 (1) ◽  
pp. 130-137 ◽  
Author(s):  
Márton Kőrösi ◽  
Attila Sedon ◽  
Kinga Komka ◽  
Tamás Sohajda ◽  
Edit Székely
Keyword(s):  
Mandelic Acid ◽  
Fine Particles ◽  
Racemic Mixture ◽  
Operational Parameters ◽  
Batch Type ◽  
Equivalent Quantity ◽  
Molar Equivalent ◽  
Gas Antisolvent ◽  
Diastereomeric Excess

Micronization processes involving supercritical carbon dioxide are rapid methods to produce fine particles. They also might offer the possibility of using less organic solvent than conventional crystallization methods leading to an environmentally friendlier processing. The separation capabilities of such processes are now demonstrated on the diastereomeric resolution of mandelic acid using (R)-1-phenylethanamine as a resolving agent, utilizing the batch type gas antisolvent fractionation as the separation method. A detailed study was conducted on the effects of the operational parameters pressure (12-20 MPa), temperature (35-55 °C) and co-solvent concentration (33-99 mg/ml). At 12 MPa, 35 °C and 99 mg/ml methanol concentration, a selectivity of 0.52 and a diastereomeric excess of 62% was reached. The same operational parameters were applied during the investigation of the recrystallization-based further purification of the diastereomeric salts, applying the resolving agent in molar equivalent quantity to a non-racemic mixture of mandelic acid. It has been found that the more stable (R)-1-phenylethylammonium-(R)-mandelate salt can be purified to de>98% through four additional recrystallization steps following the initial, half-molar equivalent resolution step.

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