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Diffusiophoresis takes place when a particle in solution moves due to the presence of a solute concentration gradient. This phenomenon is often studied under some simplifying assumptions, such as negligible diffusive layer thickness or infinite diffusion coefficient. In this work we simulate diffusiophoresis without these simplifications. The goal of this numerical study is to investigate equilibrium and fully developed states of non-electrolyte phoretic systems. Simulation results show that equilibrium states depend on solute diffusivity and on a reference solute concentration far from the particle. An expression is regressed that gives the (equilibrium) diffusiophoretic velocity as a function of solute concentration gradient, solute diffusion coefficient and the reference solute concentration far from the particle. A different set of results reveals that the state of phoretic systems does not depend on the initial conditions when time goes to infinity. This motivates the definition of fully developed states, designating those systems whose properties no longer depend on initial conditions. Apart from these findings, this work also depicts the effect of solute–interface interactions on diffusiophoresis. Simulation results for two solid particles with different interaction potentials are used to illustrate particle separation via diffusiophoresis. Finally, values of particle mobility are calculated for different solute–interface attraction strengths. These results are compared with another work in the literature, which studies polymer diffusiophoresis via molecular simulations (Ramírez-Hinestrosa et al., J. Chem. Phys., vol. 152, 2020, p. 164901).

International audience; Gas-expanded liquids have been studied during past years; however, the physicochemical properties of some of these fluids still need to be characterized and understood. In particular, the study of properties concerning solvation and mass transport is key for industrial applications. This work presents the characterization of eight CO2-expanded biosourced solvents: organic carbonates (dimethyl, diethyl, ethylene, and propylene carbonates), anisole, veratrole, γ-valerolactone, and 2-methyltetrahydrofuran. Two approaches have been used: spectroscopic measurements and molecular modeling. Phase equilibrium was determined for each CO2/biosourced solvent system, and then the solvatochromic probe Nile Red was used to determine changes in dipolarity/polarizability (π* Kamlet–Taft parameter) by CO2 pressure. Molecular dynamics calculations were performed to determine the density and viscosity changes with CO2 pressure. It is shown in this study that the degree of modulation of dipolarity/polarizability parameter can go from that of pure solvent (around 0.4 for linear organic carbonates) to negative values, close to that of pure CO2 at the T and P used in this study. Concerning transport properties, such as density and viscosity, a great decrease in both these properties’ values was observed after swelling of the solvent by CO2, for instance, in linear organic carbonates where density can decrease to 50% the density of pure solvent; concerning viscosity a decrease of up to 90% was measured for these compounds. It was observed that the solubility of CO2 and then modulation of properties were higher in linear organic carbonates than in the cyclic ones. This study shows once more that CO2 has a great capacity to be used as a knob for triggering changes in the physicochemical properties of green biosourced solvents that can help to implement these solvents in industrial applications.

International audience; The separation of ternary nonideal systems with multi‐azeotrope is very important because they are often found in the waste of chemical and pharmaceutical industries, which is much more difficult due to the formation of multi‐azeotrope and distillation boundary. We propose a systematic procedure for design and control of a triple‐column pressure‐swing distillation for separating ternary systems with three binary minimum azeotropes. This procedure involves thermodynamic insights, a two‐step optimization method, and effective control strategy. The separation of tetrahydrofuran (THF)/ethanol/water is used to illustrate the capability of the proposed procedure. It is found that the pressure limits in columns can be determined through the analysis of residue curve maps, distillation boundary, and isovolatility curves. The optimal triple‐column pressure‐swing distillation is generated with the minimum total annual cost (TAC) of $2.181 × 106 in sequence A. The operating conditions are well controlled approaching their desired specifications in an acceptable time when disturbances occur.

Edible oil extraction is a large and well-developed sector based on solvent assisted extraction using volatile organic compounds such as hexane. The extraction of oil from oilseeds generates large volumes of oilseed by-products rich in proteins, fibres, minerals and secondary metabolites that can be valued. This work reviews the current status and the bio-macro-composition of oilseeds, namely soybean, rapeseed, sunflower and flaxseed, and the refining process, comprising the extraction of oil, the valorisation and separation of valuable secondary metabolites such as phenolic compounds, and the removal of anti-nutritional factors such as glucosinolates, while retaining the protein in the oilseed meal. It also provides an overview of alternative solvents and some of the unconventional processes used as a replacement to the conventional extraction of edible oil, as well as the solvents used for the extraction of secondary metabolites and anti-nutritional factors. These biologically active compounds, including oils, are primordial raw materials for several industries such as food, pharmaceutical or cosmetics.

International audience; Residue curve maps (RCMs) and univolatility curves are crucial tools for analysis and design of distillation processes. Even in the case of ternary mixtures, the topology of these maps is highly non-trivial, as shown by Serafimov’s and Zhvanetskii’s classifications. We propose a novel method allowing detection and computation of the existence of univolatility curves in homogeneous ternary mixtures independently of the presence of azeotropes, which is particularly important in the case of zeotropic mixtures. The method is based on analysis of the geometry of the boiling temperature surface constrained by the univolatility or unidistribution condition. The introduced on the concepts of the generalized univolatility and unidistribution curves in the three dimensional composition – temperature state space that lead to a simple non iterative and efficient algorithm of computation of the univolatility curves. Two peculiar ternary systems, namely diethylamine – chloroform – methanol and hexane – benzene – hexafluorobenzene are used for illustration. When varying pressure, tangential azeotropy, bi-ternary azeotropy, saddle-node ternary azeotrope, and bi-binary azeotropy are found. In both examples, a distinctive crossing shape of the univolatility curve appears as a consequence of the existence of a common tangent point between the three dimensional univolatility hypersurface and the boiling temperature surface. Moreover, rare univolatility curves starting and ending on the same binary side are found.

Designing a sustainable and economical distillation system is a big global challenge in the industrial chemical field. To address this issue, one of most promising solutions is the so-called dividing wall columns addressed in this work, which not only can cut energy cost but also use limited installation space. An improved shortcut design approach is developed in this work to provide accurate models for each section of dividing wall columns; meanwhile Underwood’s and Gilliland’s equations are employed to determine minimum reflux ratio and total number of stages in different column sections in terms of corresponding design specifications and operating conditions. This proposed approach has been applied to separations of mixtures of hydrocarbons and alcohol with different values on the ease of separation index. To test its effectiveness, the preliminary design parameters obtained through the improved proposed shortcut method are further validated by a rigorous simulation in Aspen HYSYS. Furthermore, the res...

Instability in bottled wines refer to tartaric salts crystallization such as potassium bitartrate (KHT). It is not desirable as consumers see the settled salts as an evidence of a poor quality control. In some cases, it causes excessive gushing in sparkling wine. We investigate the effect of two oenological carboxymethylcellulose (CMC) for KHT inhibition in a model solution of white wine by studying the impact of some properties of CMC such as the degree of polymerization, the degree of substitution, and the apparent dissociation constant determined by potentiometric titration. Polyelectrolyte adsorption is used for determining the surface and total charge and for providing information about the availability of CMC charged groups for interacting with KHT crystal faces. The inhibitory efficiency of CMC on model solution is evaluated by measuring the induction time with the help of conductimetric methods. Crystals growth with and without CMC are studied by observation with MEB and by thermal analysis using DSC. The results confirm the effectiveness of CMC as an inhibitor of KHT crystallization in a model solution. The main hypothesis of the mechanism lies in the interaction of dissociated anionic carboxymethyl groups along the cellulose backbone with positively charged layers on KHT faces like the {0 1 0} face. Key factors such as pH, CMC chain length and total charge are discusses.

Project developer in the domain of land settlement project are involved with many stakeholders and are usually overflown by data relative to technical, economic and social issues. This paper contributes to the necessary multi-scale approach challenge and we propose a holistic framework that enables to describe the development process of land settlement project and assess its sustainability. It would help developers to take decisions compliant with the project complexity. In the model driven engineering perspective, the metamodel framework is described with the ISO 19440 four views to represent complex systems: architectural, structural, functional and behavioural. We confront it to describe two case studies: the successful project of hydro-wind power plant in El Hierro in the Canaries, and the Sivens Dam project in France sadly famous for its deadly outcome. Their comparison enables us to draw hypothesis on what are the ingredients of success and validate the framework.

International audience; We investigate the use of computer aided molecular design (CAMD) approach for enhancing the properties of existing molecules by modifying their chemical structure to match target property values. The activity of tailoring molecules requires to aggregate knowledge disseminated across the whole chemical enterprise hierarchy, from the manager level to the chemists and chemical engineers, with different backgrounds and perception of what the ideal molecule would be. So, we propose a framework that allows the search to be successful in matching all requirements while capitalizing this knowledge spread among actors with different backgrounds with the help of SBVR (Semantics of Business Vocabulary and Rules) and OCL (Object Constraint Language). In the context of using biomass as the feedstock, we discuss the coupling of CAMD tools with computer aided organic synthesis tools so as to propose enhanced bio-sourced molecule candidates which could be synthesized with eco-friendly pathways. Finally, we evaluate the sustainability of the molecules and of the whole decision-process as well. Specific applications that concern the use of bio-sourced molecules are presented: a case of typical derivatives of chemical platform molecules issued from the itaconic acid to substitute N-methyl-2-pyrrolidone NMP or dimethyl-formamide DMF solvents and a case of derivatives of lipids to be used a biolubricants.

This work provides a short review of extractive distillation (ED) technology, covering all relevant topics: concept and working principles, residue curve maps, solvent design, screening and selection, types of mass separating agents, influence on VLE, solvent-to-feed ratio, process design, advanced ED in dividing-wall columns, and a list of applications.

International audience; In this paper, we revise the structure of the residue curve maps (RCM) theory of simple evaporation from the point of view of Differential Geometry. RCM are broadly used for the qualitative analysis of distillation of multicomponent mixtures within the thermodynamic equilibrium model. Nevertheless, some of their basic properties are still a matter of discussion. For instance, this concerns the connection between RCM and the associated boiling temperature surface and the topological characterization of the distillation boundaries. In this paper we put in evidence the Riemannian metric hidden behind the thermodynamic equilibrium condition written in the form of the van der Waals–Storonkin equation, and we show that the differential equations of residue curves have formal gradient structure. We discuss the first non-trivial consequences ofthis factfor the RCM theory ofternary mixtures.

International audience; Four recently launched cyclic glycerol acetals or ketals are evaluated as bio-based solvents. Three of them are industrially available and result from the condensation of glycerol with formaldehyde, acetone and isobutyl methyl ketone. The fourth is under development and is prepared by the reaction of glycerol with benzaldehyde under heterogeneous acidic catalysis. Their solvent properties are evaluated through Hansen and COSMO-RS (COnductor-like Screening MOdel for Real Solvents) approaches, in comparison to traditional petrochemical solvents. Dioxolane- and dioxane-type isomers have close solubility parameters; however the nature of the starting aldehyde/ketone significantly impacts the solvency properties. Stability to hydrolysis depends heavily on both the aldehyde/ketone part and on the size of the ring. In acidic medium, acetals are found to be more stable than ketals and glycerol-based ketals are more stable than ethylene glycol-based ketals. In the case of benzaldehyde glycerol acetal, it is shown that the 6-member ring isomer (dioxane-type) is approximately 8 times more stable than the 5-member ring counterpart (dioxolane-type) at low pH. Stability towards autoxidation by O2 is high for formaldehyde and acetone-derived acetals and drops for the other two compounds. Glycerol acetals and ketals are promising potential alternatives to some harmful solvents such as glycol ethers and aniline.

International audience; The substitution of conventional solvents, in line with regulation changes, requires the use of appropriate methodologies able to generate candidate molecules. Starting from the widely used trial and error approach, we developed two improved, time- and cost-saving methodologies, involving the prediction of molecule properties and reverse design. Reverse design is an innovative methodology to design biosolvents through a virtual laboratory: stages of generation of molecular structures and properties prediction are integrated into a computer-aided molecular design tool providing solutions that meet targeted specifi cations. These two substitution methodologies were applied in a case study aiming at replacing acetone and methyl ethyl ketone for the solubilization of epoxy resin prepolymers. The generation of performing biosolvents was carried ot from furfural as a bio-based platform molecule, thanks to the prediction of different relevant properties (physico-chemical, safety, and environmental characteristics). The reverse design succeeded in ranking these solvent candidates according to their capacity to match the required specifi cations.

International audience; The Solid Fat Content (SFC) of vegetable oils is a fundamental property in fatty foods. Also, chemical interesterification (the exchange of fatty acids within and between triacylglycerols) has been used to enhance the melting profile of vegetable oils blends used in food industry. The present work uses a computational approach using Solid-Liquid Equilibrium (SLE) to predict SFC and simulate the chemical interesterification reaction (CI) for different formulations using palm oil (PO), sunflower oil (SFO) and palm kernel oil (PKO). More than 3696 SLE problems are solved, allowing the evaluation of how the fraction of each oil, the temperature and the CI reaction impacts the SFC. The calculated SFC values are compared with experimental data taken from literature. For systems composed of two or one single vegetable oil, the average absolute error (AAE) is 5.2% before CI and 4.2% after CI. For systems composed of three vegetable oils, the AAE is 6.3% before CI and 4.2% after CI. The predictions of SFC before and after CI reaction can aid the food makers to face the combinatorial problem imposed by the choice of the vegetable oil and its fraction in the blend. Future improvements in the pure component properties, thermodynamic model and distribution model of fatty acids in the triacylglycerols can increase the use of computational approaches allowing the experiments to be focused on the most promising formulations in terms of melting profile

We have studied the batch and continuous extractive distillation of minimum- and maximum-boiling azeotropic mixtures with a heavy entrainer. These systems exhibit class 1.0-1a and 1.0-2 ternary diagrams, each with two subcases depending on the location of the univolatility line. The feasible product and feasible ranges of the operating parameters reflux ratio (R) and entrainer/feed flow rate ratio for continuous (FE/F) and batch (FE/V) operation were assessed. Class 1.0-1a processes allow the recovery of only one product because of the location of the univolatility line above a minimum value of the entrainer/feed flow rate ratio for both batch and continuous processes. A minimum reflux ratio R also exists. For an identical target purity, the minimum feed ratio is higher for the continuous process than for the batch process, for the continuous process where stricter feasible conditions arise because the composition profile of the stripping section must intersect that of the extractive section. Class 1.0-2 mixtures allow either A or B to be obtained as a product, depending on the feed location. Then, the univolatility line location sets limiting values for either the maximum or minimum of the feed ratio FE/F. Again, the feasible range of operating parameters for the continuous process is smaller than that for the batch process. Entrainer comparison in terms of minimum reflux ratio and minimum entrainer/feed ratio is enabled by the proposed methodology.

Flash point is the most important variable used to characterize the fire and explosion hazard of liquids. This paper presents the first partially miscible aqueousorganic mixtures flash point measurements and modeling for the ternary type-I mixtures, water + ethanol + 1-butanol, water + ethanol + 2-butanol, and the type-II mixture, water + 1-butanol + 2-butanol. Results reveal that the flash points are constant in each tie line. Handling the non-ideality of the liquid phase through the use of activity coefficient models, the general flash-point model of Liaw et al. extended to partially miscible mixtures predicts the experimental data well when using literature LLE and the VLE activity coefficient model binary parameters to estimate sequentially the span and flash point in each tie line and the flash point in the mutual solubility region, respectively. The constant flash-point behavior in a tie line is also observed and predicted, in agreement with the VLLE tie line property that a single vapor is in equilibrium with all liquid composition on a tie line. For the aqueousorganic mixtures here studied, a deviation between prediction and measurements is observed, arising from the failure of the constant lower flammable limit assumption in the mutual solubility inert-rich region. Potential application for the model concerns the assessment of fire and explosion hazards and the development of inherently safer designs for chemical processes containing partially miscible aqueousorganic mixtures.

The wet granulation process is sensitive to changes in product properties and process variables. The optimal process and formulation are based on the knowledge of the granule growth mechanisms and of the effects of product properties and process variables. This paper presents the study of wet granulation of microcrystalline cellulose powder, MCC (Avicel PH101) using high-shear mixer granulator. It aims at understanding the effect of operating parameters (impeller rotational speed, liquid binder flow ate) and of physicochemical properties (viscosity, wettability) of a binder solution on solid particles surfaces, on the agglomeration kinetics. The experiments are carried out with water, aqueous solutions of sodium carboxymethylcellulose, polyvinylpyrrolidone, hydroxypropylméthylcellulose or a non ionic surfactant oxo-C10C6 at a critical micellar concentration. Concerning the process variables the experimental results show that an optimal interval of impeller speed operation exists ranging from 150 to 200 rpm for granule growth. Below, an uncontrollable agglomerate size and localised over-wetting occur, and above granule breakage occurs. Increasing the liquid binder flow rate reduces the extension of the non growth regime, but does not affect the granule mean size. The effect of the physicochemical properties is evaluated using a modified capillary viscous number, Ca′, that we define as the ratio between the viscous forces (μLU) and the work of adhesion Wa=γL(1+cosθ). For Ca′b1, the viscosity of the solution does not significantly affect the granulation process. The dominant forces in the granulation process are the interfacial forces since increasing the work of adhesion enhances the growth kinetics. For Ca′N1.6, the viscous forces predominate and control the granule growth.

RESUMO – A computer aided product design (CAPD) tool was developed aiming to find bio-based molecules that match a set of desired properties. Molecules are represented by molecular graphs that are split into basic groups by automatic decomposition methods. These groups are further used for property predictions using Group Contributions methods by the property calculation component, a Dynamic-Link Library (DLL) that handles properties predictions for each candidate molecule generated by the search component. The search component uses a Genetic Algorithm to generate/modify molecular structures and search for molecules/mixtures that satisfy the desired properties. The capabilities of the tool are illustrated through a case study aiming to find chlorinated paraffin substitutes using levulinic acid as building block for alternative molecules.

The structures of clusters of spherical and homogeneous particles are investigated using a combination of global optimization methods. The pairwise potential between particles is integrated exactly from elementary Lennard-Jones interactions, and the use of reduced units allows us to get insight into the effects of the particle diameter. As the diameter increases, the potential becomes very sharp, and the cluster structure generally changes from icosahedral (small radius) to close-packed cubic (large radius), possibly through intermediate decahedral shapes. The results are interpreted in terms of the effective range of the potential.

A general and polyvalent model for the dynamic simulation of a vapor, liquid, liquid–liquid, vapor–liquid or vapor–liquid–liquid stage is proposed. This model is based on the τ -method introduced as a minimization problem by [Comput. Chem. Eng. 22 (7/8) (1998) 897] for steady-state simulation. They suggested modifying the mole fraction summation such that the same set of governing equations becomes valid for all phase regions. Thanks to judicious additional switch equations, the τ -formulation is extended to dynamic simulation and the minimization problem is transformed into a set of differential algebraic equations (DAE). Validation of the model consists in testing its capacity to overcome phase number changes and to be able to solve several problems with the same set of equations: calculation of heterogeneous residue curves, azeotropic points and distillation boundaries in ternary diagrams.

A general and polyvalent model for the dynamic simulation of a vapor, liquid, liquid-liquid, vapor-liquid or vapor-liquid-liquid stage is proposed. This model is based on the τ -method introduced as a minimization problem by Han & Rangaiah (1998) for steady-state simulation. They suggested modifying the mole fraction summation such that the same set of governing equations becomes valid for all phase regions. Thanks to judicious additional switch equations, the τ -formulation is extended to dynamic simulation and the minimization problem is transformed into a set of differential algebraic equations (DAE). Validation of the model consists in testing its capacity to overcome phase number changes and to be able to solve several problems with the same set of equations: calculation of heterogeneous residue curves, azeotropic points and distillation boundaries in ternary diagrams. Topical Heading Process System Engineering

International audience; Following previous studies on heterogeneous batch azeotropic distillation, we evaluate the use of heterogeneous entrainers for the separation of binary azeotropic mixtures by extractive distillation. This process is well suited for systems where the entrainer forms a saddle heteregeneous azeotrope with anyone of the original components, such systems being unsuitable for non extractive heterogeneous batch distillation processes. Process feasibility is assessed from the isovolatility curves and the volatility order diagram. It tells us whether the homogeneous original component or the heteroazeotrope is drawn at the column top and establishes the distillation tasks sequence using a batch rectifying column. The theoretical insights are validated via rigourous simulation for the separation of the mixture acetonitrile – water with hexylamine or butyl acetate. Finally, the same method is applied for the theoretical analysis of a reported industrial example where water is used for the separation of binary organic mixture leading to a complex ternary system with several binary azeotropic points and a homogenous ternary azeotrope.

Synthesis of heterogeneous batch distillation is discussed, which aims at splitting azeotropic mixtures by adding an entrainer partially miscible with one of the initial binary mixture components. Key operational parameters are identified such as the amount of entrainer added in the ternary feed, the reflux policy, and the vapor line position by examples. Synthesis and operation are less straightforward for heterogeneous batch distillation than those for the homogeneous case, but offer many advantages: more design alternatives, simplified distillation sequences, a lower consumption of entrainer, and a crossing of distillation boundaries by the still path. Feasibility is assessed using simplified modeling and confirmed using a commercial batch process simulator package. Synthesis expectations and simulated results are verified throughout bench-plant experiments for the separation of the acetonitrile-water mixture using acrylonitrile as a light heterogeneous entrainer.

A computer aided product design (CAPD) tool is proposed that finds mixtures matching target properties. Genetic algorithm crossover and mutation operators are completed with insertion or deletion operators adapted for side branches. A new substitution operator is devised for cyclic molecules. The mixture fitness is evaluated by a weighted sum of property performances. Molecules are represented by molecular graphs. They are split into molecular fragments which are built from polyatomic groups. Molecules or molecular fragments can be fixed, constrained or left free for building a new molecule. Building blocks are chemical functional groups or bio-sourced synthons. A specific coding of hydrogen-suppressed atoms is devised that can be used with various property estimation models where atom connectivity information is required. Illustration is provided through three case studies to find levulinic, glycerol and bio-based derivatives as substitute for chlorinated paraffin, methyl p-coumarate ester solvent and blanket wash solvent, respectively.

This work deals with Product Design by means of theoretical predictions of the Solid Fat Content of different formulations using 3 vegetable oils. A Soli-Liquid Equilibrium (SLE) model was implemented and integrated into an optimization algorithm based on the Generalized Reduced Gradient method. A total of 3,696 SLE problems are solved, covering 57 binary blends, 3 pure vegetable oils and 171 ternary blends problems, before and after chemical interesterification reaction and at 8 different temperatures. A combinatorial random distribution of fatty acids in the glycerol structure is used to simulate the effect of the reaction. The results were compared with 256 experimental points, giving an average absolute error of 5.4 and 4.4 in Solid Fat Content for systems before and after reaction, respectively. Computer-aided tools can be useful to deal with the large combinatorial problem faced by product design, especially when desired product performance is related to a phase behavior in multicomponent mixtures.

Despite the greater attention given to biofuels application in the literature, there are many economic and environmental drivers to use vegetables oils (VOs) as a renewable feedstock for other applications. These drivers are discussed in the present work and the technological challenges imposed by this shift towards new VOs uses are also discussed. They are mainly associated to the reaction routes issues, the performance regarding end-user properties, experimental procedures and property prediction models. The need for more holistic approaches (life cycle analysis) is briefly discussed and the potential benefits arising from new computer-aided tools are highlighted as well.

The design and synthesis of extractive distillation rely upon the knowledge of residue curve map topology and the calculation of univolatility curves to analyze the volatility order of the mixture. Contrary to common belief, light, intermediate, heavy, and heterogeneous entrainers can be used to separate minimum- or maximum-boiling azeotropes and low-relative-volatility mixtures. After a preliminary selection of candidate entrainers based on selectivity and entrainer capacity, a general feasibility criterion enables one to find attainable products and suitable process configurations with the entrainer fed at a different location than the main mixture to be separated, inducing an extractive section within the column. It shows that the most or the least volatile component is recovered from a direct or an indirect split-column configuration in the distillate or in the bottom stream, respectively. Batch and continuous operations are governed by the same entrainer selection rules, but the operating parameter value ranges for the entrainer-feed flow rate ratio and the reflux ratio are different.

Pancreatic juice is supersaturated with calcium carbonate. Calcite crystals therefore may occur, obstruct pancreatic ducts, and finally cause a lithiasis. Human lithostathine, a protein synthesized by the pancreas, inhibits the growth of calcite crystals by inducing a habit modification: the rhombohedral (10 14) usual habit is transformed into a needle-like habit through the (11 0) crystal form. A similar observation was made with the N-terminal undecapeptide (pE(1)R(11)) of lithostathine. We therefore aimed at discovering how peptides inhibit calcium salt crystal growth. We solved the complete x-ray structure of lithostathine, including the flexible N-terminal domain, at 1.3 A. Docking studies of pE(1)R(11) with the (10 14) and (11 0) faces through molecular dynamics simulation resulted in three successive steps. First, the undecapeptide progressively unfolded as it approached the calcite surface. Second, mobile lateral chains of amino acids made hydrogen bonds with the calcite surface. Last, electrostatic bonds between calcium ions and peptide bonds stabilized and anchored pE(1)R(11) on the crystal surface. pE(1)R(11)-calcite interaction was stronger with the (11 0) face than with the (10 14) face, confirming earlier experimental observations. Energy contributions showed that the peptide backbone governed the binding more than did the lateral chains. The ability of peptides to inhibit crystal growth is therefore essentially based on backbone flexibility.

International audience; A Solid Liquid Equilibrium model coupled with analgorithm for direct minimization of the Gibbs free energy function was used to compute the melting profiles for binary blends of vegetable oils. The effect of interest erification on the Solid Fat Content (SFC) is simulated by using a completely random distribution of fatty acids on the glycerol structures. The methodology was applied to different blends of 6 vegetable oils: canola oil, fully hydrogen ated palm oils tear in, palm oils tear in, cotton seed oil, milk fat and corn oil. The predicted results were compared with experimental data from literature and the average absolute error in SFC was 3.33 (physical mixture without interesterification) and 4.13% (after interesterification). Additionally, two qualitative aspects also observed inexperimental works could be computationally detected: the existence of temperatures in which the blends have the same SFC before and after reaction and the fact that randomized blends tend to melt at lower temperatures than their corresponding mixtures. The results reinforced the potential use of computer-based tools to explore new formulations aiming to match a desired melting range, reducing the experimental efforts in product design where vegetable oils are used and the thermal profile has a fundamental role.

The nucleation of potassium hydrogen tartrate (KHT) in water-ethanol model solutions and in wines is investigated by the induction time technique. The results suggest that KHT nucleation in wine is inhibited by natural compounds. The value of the specific surface energy is found to be around 4 mJ m −2 , when derived from a mononuclear mechanism and 6.4, 6.7 and 7.5 mJ m −2 when the polynuclear mechanism is used with volume diffusion-controlled, normal and spiral growth, respectively. Complementary experiments made with a potassium ion selective electrode show that potassium ions are partly associated in solution with organic acids, like tartaric acid. Calculation of KHT supersaturation should therefore take into account the fraction of associated potassium. Further experiments are needed to identify all the associated species and to obtain the dissociation constants of their equilibria.