Partition coefficient prediction of Baker's yeast invertase in aqueous two phase systems using hybrid group method data handling neural network

A hybrid GMDH neural network model has been developed in order to predict the partition coefficients of invertase from Baker's yeast. ATPS experiments were carried out changing the molar average mass of PEG(1500–6000 Da), p H(4.0–7.0), percentage of PEG(10.0–20.0 w/w), percentage of MgSO_4(8.0–16.0 w/w), percentage of the cell homogenate(10.0–20.0 w/w) and the percentage of MnSO_4(0–5.0 w/w) added as cosolute. The network evaluation was carried out comparing the partition coefficients obtained from the hybrid GMDH neural network with the experimental data using different statistical metrics. The hybrid GMDH neural network model showed better fitting(AARD = 32.752%) as well as good generalization capacity of the partition coefficients of the ATPS than the original GMDH network approach and a BPANN model. Therefore hybrid GMDH neural network model appears as a powerful tool for predicting partition coefficients during downstream processing of biomolecules.     

Modification of a thermodynamic model and an equation of state for accurate calculation of asphaltene precipitation phase behavior

In this study, DPTG (Dashtizadeh-Pazuki-Taghikhani-Ghotbi) equation of state has been modified for calculation of phase behavior of fluids and solubility parameter. The accuracy of the modified EOS has been proved by estimation of the properties of some hydrocarbons such as densities of methane and condensate gases, vaporization enthalpy, sublimation pressure, compressibility factor and comparison of the obtained results with the results of the present equations of state such as NJ (Nasrifar-Jalali), ZMJL (Zhi-Meiren-Jun-Lee) and PR (Peng-Robinson). Then, the Flory-Huggins model has been modified and asphaltene precipitation phase behavior at different ratios of solvents in the crude oil has been predicted by the modified EOS and the developed Flory-Huggins model. Comparison of the obtained results with the experimental data of asphaltene precipitation and the calculated ones by the main Flory-Huggins model shows the accuracy of the developed model.     

A Novel Photometric Technique to Detect the Onset of Asphaltene Precipitation at Low Concentrations: The Effect of Maltenes and Water

A photometer was utilized to measure the intensity of scattered light in toluene / heptane / asphaltenes mixtures. On the scattering‐intensity versus heptane‐to‐toluene ratio functions, two linear regions can be observed. The intersection of these regions determines the heptane‐to‐toluene ratio at which the precipitation of asphaltenes starts. The onset of asphaltene precipitation was determined as a function of asphaltene concentration in the presence and in the absence of maltenes as well as water. The onset is dependent on the asphaltene concentration. The presence of water promoted while the presence of maltenes inhibited the precipitation of asphaltenes.     

Cost effective recovery of lithium from lithium ion battery by reverse osmosis and precipitation: a perspective

Production of lithium from primary resources is lagging behind demand (12% versus 16% in 2016), cost of lithium is increasing (between 40 and 60% in 2016), battery energy density rapidly increasing versus declining cost, and estimated lithium ion battery (LIB) markets size ($77.42 billion by 2024) driven by projected demands for plug‐in electric vehicles (PEVs) clearly justifies recycling. PEV technology and projected demand raise several challenges, including lithium demand/scarcity and future technology to recover lithium from LIB waste. To address the circular economy, steady supply chain security, self‐reliance, environment safety, environment directive, energy security, resources conservation, futuristic carbon footprint, WEEE directives and waste crime, recycling of LIB is an absolute essential. During the last decade, LIB recycling research and industrial recycling of LIB have attracted the interest of researchers, industrialists, and environmentalists. All have reported progress in the recovery of valuable metals like Co, but have rarely focused on lithium recovery. Hence, this paper addresses logical hypothesis and application of available technology in a fashion where lithium recycling from LIB can be addressed. © 2017 Society of Chemical Industry     

Dense CO2 antisolvent precipitation of levothyroxine sodium: A comparative study of GAS and ARISE techniques based on morphology and particle size distributions

Morphology and particle size distribution of levothyroxine sodium are experimentally investigated by comparing gas antisolvent (GAS) and atomized rapid injection for solvent extraction (ARISE) techniques using dense CO₂. Precipitation of levothyroxine sodium from ethanol was carried out at 25, 40 and 50 °C, with pressure in the 90–120 bar range and different concentrations of the organic solution. Particles produced by the GAS process are nanospheres whereas ARISE processed particles are either spherical or rod-like micro and nanoparticles. Particle size and size distributions of GAS processed levothyroxine sodium are in the 370–500 nm range, while the ARISE process produced particles in the 360–1200 nm range. In most cases, both techniques produced bimodal size distributions, due to particle agglomeration. The different morphological characteristics and particle size distributions of levothyroxine sodium obtained using GAS and ARISE at different operating conditions can be useful depending on the type of drug formulation chosen, as well as the route of drug administration and delivery system.     

A semi‐empirical cell voltage model for polymer electrolyte/methanol systems: Applicability of the group contribution method

A new group contribution model is established to describe the cell voltage of a direct methanol fuel cell as a function of the current density. The model equation is validated with experimental data over a wide range of methanol concentrations and temperatures. The proposed model focuses on very unfavorable conditions for cell operation, that is, low methanol solution concentrations and relatively low cell temperatures. The proposed group contribution method includes a methanol crossover effect that plays a major role in determining the cell voltage of a direct methanol fuel cell. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Modeling viscosity of methane,nitrogen, and hydrocarbon gas mixtures at ultra-high pressures and temperatures using group method of data handling and gene expression programming techniques

Accurate gas viscosity determination is an important issue in the oil and gas industries. Experimental approaches for gas viscosity measurement are time-consuming, expensive and hardly possible at high pressures and high temperatures (HPHT). In this study, a number of correlations were developed to esti-mate gas viscosity by the use of group method of data handling (GMDH)-type neural network and gene expression programming (GEP) techniques using a large data set containing more than 3000 experimen-tal data points for methane, nitrogen, and hydrocarbon gas mixtures. It is worth mentioning that unlike many of viscosity correlations, the proposed ones in this study could compute gas viscosity at pressures ranging between 34 and 172 MPa and temperatures between 310 and 1300 K. Also, a comparison was performed between the results of these established models and the results of ten well-known models reported in the literature. Average absolute relative errors of GMDH models were obtained 4.23％, 0.64％, and 0.61％for hydrocarbon gas mixtures, methane, and nitrogen, respectively. In addition, graph-ical analyses indicate that the GMDH can predict gas viscosity with higher accuracy than GEP at HPHT conditions. Also, using leverage technique, valid, suspected and outlier data points were determined. Finally, trends of gas viscosity models at different conditions were evaluated.     

Modelling the amorphous phase of a melt crystallized,semicrystalline polymer: segment distribution,chain stiffness,and deformation

The analogy between the Gambler's Ruin problem and the statistics of loops and bridges in the amorphous region of lamellar semicrystalline polymers was first recognized by Guttman et al. Results for the loop and bridge distribution compare very well with recent data from Monte Carlo calculations. However, when the molecular weight of the polymer is low, a substantial part of the amorphous region is filled by cilia and free polymer. We examined their relative importance by adapting the matrix formalism developed by DiMarzio and Rubin. The Gambler's Ruin results are recovered for high molecular weight polymer. In addition it will be shown that the effect of the temperature (chain stiffness) can be simulated by rescaling the steplength of a random walk chain. Mean field theories incorporate segment-solvent interactions and allow for non-uniform segment densities by weighting each step according to the local concentrations. Using these weighting factors, we find deformation to be controlled by energetic interactions rather than by entropy. At large strain a ‘necking’ process occurs. However, in the presence of a good solvent, the material is soft and flexible.     

A model of fine particles deposition on smooth surfaces: II—Comparison with experimental data and simplified models

The application of a model of fine particles initial deposition from a flowing suspension on smooth surfaces is discussed by comparison with literature experimental data and simplified models (Leveque equation). The model and its original features, including an accurate account of particle-surface interactions and ad hoc solution techniques, with special emphasis on the treatment of boundaries, have been thoroughly presented in Part I. The model demonstrates that in many circumstances diffusion is the limiting mechanism so that simple models based on a continuous approach (through particles concentration) together with perfect sink assumption are accurate enough. Departures from such circumstances are identified by means of a parametric study based on our model. The comparison with the experimental data also suggests additional characterizations needed for future experimental investigations.     

Multistage estimation of the difference of locations of two negative exponential populations under a modified Linex loss function: Real data illustrations from cancer studies and reliability analysis

We have designed modified two-stage and purely sequential strategies to estimate the difference of location parameters from two independent negative exponential populations having unknown but proportional scale parameters under a modified Linex loss function. This article extends one-sample methodologies of Mukhopadhyay and Bapat (2016 Mukhopadhyay, N. and Bapat, S. R. (2016). Multistage Point Estimation Methodologies for a Negative Exponential Location under a Modified Linex Loss Function: Illustrations with Infant Mortality and Bone Marrow Data, Sequential Analysis 35: 175–206. http://dx.doi.org/10.1080/07474946.2016.1165532.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar], Sequential Analysis). Some preliminary results are established along the lines of Mukhopadhyay and Hamdy (1984 Mukhopadhyay, N. and Hamdy, H. I. (1984). On Estimating the Difference of Location Parameters of Two Negative Exponential Distributions, Canadian Journal of Statistics 12: 67–76.[Crossref] , [Google Scholar], Canadian Journal of Statistics) and Mukhopadhyay and Darmanto (1988 Mukhopadhyay, N. and Darmanto, S. (1988). Sequential Estimation of the Difference of Means of Two Negative Exponential Populations, Sequential Analysis 7: 165–190.[Taylor &; Francis Online] , [Google Scholar], Sequential Analysis). We have resorted to Mukhopadhyay and Duggan (1997 Mukhopadhyay, N. and Duggan, W. T. (1997). Can a Two-Stage Procedure Enjoy Second Order Properties? Sankhya, Series A 59: 435–448. [Google Scholar], Sankhya, Series A) in developing asymptotic second-order properties for the modified two-stage methodology and to nonlinear renewal theory of Lai and Siegmund (1977 Lai, T. L. and Siegmund, D. (1977). A Nonlinear Renewal Theory with Applications to Sequential Analysis I, Annals of Statistics 5: 946–954.[Crossref], [Web of Science ®] , [Google Scholar], 1979 Lai, T. L. and Siegmund, D. (1979). A Nonlinear Renewal Theory with Applications to Sequential Analysis II, Annals of Statistics 7: 60–76.[Crossref], [Web of Science ®] , [Google Scholar], Annals of Statistics) and Woodroofe (1977 Woodroofe, M. (1977). Second Order Approximation for Sequential Point and Interval Estimation, Annals of Statistics 5: 984–995.[Crossref], [Web of Science ®] , [Google Scholar], Annals of Statistics) in addressing analogous properties under the purely sequential methodology. Then, we supplement with extensive sets of data analysis via computer simulations validating that both modified two-stage and purely sequential methods perform very well. Both methodologies are also illustrated and implemented using real datasets from cancer studies and reliability analysis.     

A new approach to artificial and modified proteins: theory-based design, synthesis in a cell-free system and fast testing of structural properties by radiolabels

A novel approach to the creation of artificial and modifiedproteins has been elaborated. The approach includes a sequencedesign based on the molecular theory of protein secondary structureand folding patterns, gene expression in a cell-free systemand testing of structural properties of the synthesized polypeptidesat a nanogram level using radiolabelled chains. The approachhas been applied to a new synthetic protein albebetin whichhas been designed to form a 3-D fold which does not contradictany structural rule but has been never observed up to now innatural proteins. Using size-exclusion chromatography, urea-gradientelectrophoresis and limited proteolysis of a radiolabelled chain,it has been shown that the artificial protein is nearly as compactas natural proteins, cooperatively unfolds at high urea concentrationsand has some structural features of a definite structure consistentwith the designed one. As albebetin has been designed as consistingof two structural repeats, a ‘halfalbebetin’ (oneof these repeats) has also been synthesized and studied. Itwas shown that ‘half-albebetin’ is also compact