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The development of solid lipid nanoparticles (SLN) using supercritical fluid at room temperature is an innovative alternative compared to traditional pharmaceutical methods and the safety and drug efficacy of SLN made using supercritical CO 2 is increased. One of the micronization techniques which have provided the best results in the production of SLN is particles from gas-saturated solution (PGSS). The solid–liquid–vapour coexistence curve of a solid in a compressed gas is of primary importance in assessing the feasibility of PGSS and the selection of appropriate operating conditions. The objectives of this work are to perform experimental measurements using a high pressure differential scanning calorimeter (DSC) to obtain melting properties as a function of composition and develop a simplified approach to model multiphase equilibria of lipids in compressed CO 2 . The selected lipid was tristearin. Before assessment of triestearin and CO 2 phase equilibrium, the performance of this thermodynamic model was evaluated in two other lipids which provided results with high accuracy.

An original experimental setup based on UV-vis spectroscopy was developed to study the precipitation kinetics of a biodegradable polymer by gas antisolvent processes (GAS). Po(v(L-lactide) acid (PLA) precipitations were carried out in a high-pressure optical cell equipped with sapphire windows, working at 1-80 bar and 301.15 - 307.15 K The particle formation and precipitation kinetics were investigated in situ by measuring UV-vis absorbance of polymeric particles at a wavelength of 600 nm. They were measured in a batch system at different pressurization rates (different supersaturation conditions). To rationalize the precipitation kinetics in GAS processes, a population balance model was developed considering particle nucleation, growth, aggregation, and settling. Nucleation and growth were represented by the McCabe model, whereas both independent- and nonindependent-kemel Smoluchowski's coagulation equations were used for aggregation. Settling was approximated by a first-order kinetic. Absorbance measurements were related to the second moment of the simulated particle-size distribution, and the kinetic parameters were estimated based on spectroscopic data. The model gave a correct phenomenological representation of all experimental data and fairly predicted the particle-size distribution of the precipitated PLA microparticles.

In this work, a new thermodynamic method, based on the McMillan–Mayer solution theory, is proposed to interpret and predict the solubility of low- and high-molecular-weight compounds in compressed CO2. In the thermodynamic approach presented here, the solute is referred to as a pseudo pure component while the compressed CO2 is represented as a continuous medium that affects the interactions among solute molecules. The perturbed-hard-sphere-chain (PHSC) theory is used within the McMillan–Mayer framework to derive an expression for the repulsive and attractive contributions to the Helmholtz free energy of the solute. While easy to handle, the model enlightens the effects of molecular weight and other physical–chemical characteristics on compounds solubility in compressed media. The thermodynamic approach fairly describes the experimental data concerning the solubility of several substances in compressed CO2 at different temperatures. The model also predicts CO2 solubility in PEG polymer and semi-quantitatively reproduces high-molecular-weight component solubility in compressed CO2 containing low amount of ethanol as co-solvent.

Toward improved understanding of the dilute-solution properties of arborescent polystyrenes, new measurements are reported for osmotic second virial coefficients and for intrinsic viscosities in three common organic solvents. As observed for other branched polymers, branching decreases the second virial coefficient in good solvents and lowers the theta temperature for a polymer–solvent system. For generation-zero arborescent polystyrene in methylcyclohexane, the theta temperature is 36±2°C. A correspondence between intrinsic viscosity and second virial coefficient, valid for hard-spheres solutions, holds in good solvents; this correspondence improves with decreasing branch molecular weight. The osmotic-pressure data are interpreted with a colloid-like thermodynamic framework using a van der Waals-type equation of state. The reference state is the hard sphere and the perturbation is given by an attraction decaying with the sixth power of the center-to-center distance between polymers. The hard-sphere diameter is obtained from intrinsic-viscosity data. Predicted and observed osmotic pressures are in good agreement.

Experimental osmotic second virial coefficients are reported for polystyrene in toluene (good solvent), cyclohexane (ϑ solvent) and methylcyclohexane (poor solvent) in the temperature range 10−60 °C. The ϑ temperature for eight-arm star polystyrene in methylcyclohexane is 29 ± 3 °C. Intrinsic viscosity for polystyrene in cyclohexane and methylcyclohexane has been measured over a wide temperature range. A coil-globule transition has been observed for eight-arm star polystyrene in methylcyclohexane at temperatures close to the ϑ temperature. The ϑ point for star polymers with three, four, five, and six arms have been determined by standard Monte Carlo simulation calculations. For six-arm star polymers at the ϑ point, defined as the well depth at which the radius of gyration squared scales linearly with the number of segments, the osmotic second virial coefficient is zero. As shown by others, for a branched polymer, the osmotic second virial coefficient at good solvent conditions and the ϑ temperature are lo...

A method for calculating the vapor−liquid equilibria of mixtures between hydrofluorocarbons and lubricant oils is presented. A cubic equation of state is used (Sako, T.; et al. J. Appl. Polym. Sci. 1989, 38, 1839), containing three parameters: the attractive one, a, the volume parameter, b, and the number of external degrees of freedom per molecule, c. To allow calculation of the parameters of the high molecular weight components, whose critical constants and vapor pressure are unknown, a group-contribution approach is developed for a, b, and c. The extension to mixtures is achieved by applying Huron−Vidal mixing rules. A modified Uniquac model is used to evaluate infinite-pressure activity coefficients. With the proposed method, the density of pure heavy components (such as n-hexadecane and pentaerythritol esters) is predicted as a function of temperature. Vapor−liquid equilibria calculations are presented for binary mixtures between several hydrofluorocarbons and pentaerythritol esters or hexadecane; a...

The feasibility of deterpenating orange peel oil with supercritical CO2 depends on relevant vapor-liquid equilibrium data because the selectivity of this solvent for limonene and linalool (the two key components of the oil) is of crucial importance. The vapor-liquid equilibrium data of the CO2-limonene binary system was measured at 50, 60 and 70oC and pressures up to 10 MPa, and of the CO2-linalool binary system at 50oC and pressures up to 85 bar. These results were compared with published data when available in the literature. The unpublished ternary phase equilibrium of CO2-limonene-linalool was studied at 50oC and up to 9 MPa. Selectivities obtained using these ternary data were compared with those calculated using binary data and indicate that a selective separation of limonene and linalool can be achieved.

An apparatus for the measurement of vapor–liquid equilibria (P–T–x–y) data of refrigerant systems was designed, built and tested. The recirculation method was used and the vapor phase was forced through the liquid phase by a magnetic pump. The thermodynamic equilibrium was reached in a visual cell with an internal volume of 50 cm3. The compositions of the phases were analyzed by a gas chromatograph connected on-line with either FID or TCD detectors. The operating temperature and pressure in the apparatus, as tested before delivery to the laboratory [R. Stryjek, personal communication], range from 240 to 350 K and from 0.1 to 10 MPa, respectively. The estimated accuracy of the measured data was ±0.01 K for temperature, ±0.8 kPa for pressure and 0.001 in mole fraction for liquid and vapor compositions. Vapor–liquid equilibria data were obtained for the following systems: 1,1,1,2-tetrafluorethane+isobutane (R134a+R600a) at 293.66 and 303.68 K; 1,1,1,2-tetrafluorethane+1,1,1,3,3,3-hexafluoropropane (R134a+R236fa) at 283.62 and 303.68 K; and isobutane+1,1,1,3,3,3-hexafluoropropane (R600a+R236fa) at 303.68 K. The thermodynamic consistency of the experimental results was tested.

The hydrogenation of organic substrates in a fixed-bed catalytic reactor is considered, using supercritical CO 2 as a solvent to increase the solubility of hydrogen in the liquid reactants. Reaction rates can be adjusted by changing operating conditions, allowing the reaction volume to be much smaller than in conventional processes. Although it is possible to perform the reaction in a homogenous phase, to avoid interphase mass-transfer limitations, extremely high temperature and pressure may be needed to reach such a condition; therefore the reaction is carried out at conditions where both a gas and a liquid phase are present. Taking into account the solid catalyst, a three-phase reaction system has to be delat with. A trickle-bed high-pressure reactor was simulated using a pseudo-homogenous two-dimensional model, where both mass and energy balance are considered. The PDE system was solved using anorthogonal collocation method. The model does not include any adjustable parameters, and was developed as an user-written subroutine to be linked with a widely used process simulator (Aspen Plus), thus allowing accurate and flexible thermophysical and VLE calculations. Experiments were carried out in a pilot-scale unit running at Hoffmann-La Roche facilities, so that simulated and experimental values could be compared to state the accuracy of the model.

Catalytic hydrogenation in supercritical carbon dioxide has been studied. Experimental results and theoretical calculations are presented, attempting to elucidate the effects of temperature, pressure, and CO{sub 2} concentration on the rate of reaction. An effort has been made to develop a procedure to test catalytic reactions in supercritical fluids in view of future industrial applications. Hydrogenation rates of the two double bonds of an unsaturated ketone on a commercial alumina-supported palladium catalyst were measured in a continuous gradientless internal-recycle reactor at different temperatures, pressures, and CO{sub 2}-to-feed ratios. A Berty-type reactor has been suitably modified for use with supercritical solvents. The accurate control of the organic, carbon dioxide, and hydrogen feed flow rates and of the temperature and pressure inside the reactor provided reproducible values of the product stream compositions, which were measured on-line after separation of the gaseous components. In order to develop a kinetic model, vapor-liquid equilibrium calculations were carried out through a Peng-Robinson equation of state, tuned on binary high-pressure-vapor-liquid equilibrium data. Compositions in the liquid phase inside the reactor were predicted, starting from the on-line analysis after depressurization. A simplified power law kinetic equation is shown to provide a good description of the experimental data.

This paper considers the calculation of homogeneous chemical equilibria in high-pressure gaseous systems. A modified Redlich-Kwong-Soave equation of state, which represents satisfactorily single-phase fugacity coefficients of pure fluids, is extended to mixtures. Mixture parameters are derived from the corresponding pure-component ones by means of the classical mixing rules. Equilibrium compositions are predicted for the ammonia synthesis, the water-gas shift reaction, and the methanol synthesis. In the case of ammonia, extensive experimental data between 10 and 80 MPa are reproduced with good accuracy ; when the model is extrapolated up to 350 MPa, still satisfactory results can be calculated. For the water-gas shift reaction, acceptable results are obtained with limited experimental data sets. As to methanol synthesis, an interesting behavior is evidenced when operating near methanol's critical temperature. The proposed model is shown to be superior to both the Lewis-Randall approach and the original Redlich-Kwong-Soave equation of state and can be used to predict equilibrium conversion of gas-phase reactions under high pressures.

A new way to define the two parameters a, b of the Redlich-Kwong equation of state without using the critical constants is introduced. First, the “shifted” covolume (b - c) of the Peneloux modification of the equation of state is estimated by group contributions (for a wide range of compounds); from it and one vapor pressure-liquid density pair, the covolume b is then determined. The attractive parameter a is derived, at any temperature, from the covolume and the compound vapor pressure. The proposed method makes it possible to treat substances whose critical constants are not known (heavy or thermally unstable compounds) by using one density value and the vapor pressure curve. Examples are given of vapor-liquid equilibrium calculations.

We investigate the use of infinite-dilution activity coefficients to define the interaction parameters of the Redlich-Kwong equation of state (SRK-EOS), with the Huron-Vidal mixing rules. The group-contributions of a UNIFAC-type model were regressed from experimental infinite-dilution activity coefficients of a number of significant systems, including strongly polar components. Such parameters were then used to predict vapor-liquid equilibria (VLE) over the whole composition range, at pressures up to 6 MPa, with generally good results

A method has been developed for extrapolating vapour pressures of pure substances below 1,300 Pa. It is based on the integration of the Clausius Clapeyron equation, with a suitable expression of the integrating function. The vaporization enthalpy is extrapolated according to the Majer-Svoboda equation with parameters fitted on enthalpy values calculated from available data on vapour pressure above 1,300 Pa. The modified two-parameter Miller equation is used in vapour pressure data reduction. The change of molar volume is expressed by means of a modified Redlich-Kwong equation of state. The procedure is devised so that only vapour pressure data in the range 1,300–100,000 Pa and critical temperature are needed for calculation. Results obtained with this method are compared for many compounds with available and selected vapour pressure data in the range 0.3–100 Pa. In conclusion, the proposed procedure ensures a good prediction of very low vapour pressures. When reliable and smooth pressure data are...

A method for evaluating solid–liquid equilibria of mixtures of lipids and carbon dioxide (CO2) under pressure is developed and presented in this article. Experimental measurements by high-pressure differential scanning calorimetry (DSC) are performed to determine solid–liquid transition temperatures as a function of composition. These data are used to develop a simplified approach for thermodynamic modeling, that is, correlation and prediction, of the solid–liquid equilibria. The model requires fewer pure component properties in comparison with cubic equations of state: the solid-state fugacity is determined with reference to the subcooled liquid state whereas regular solution theory is applied for the calculation of liquid-phase activity coefficients. Application of the model is demonstrated for mixtures of ceramide 3A and cholesterol in compressed CO2 in the range of pressure from 0.1 to 6.1 MPa. A satisfactory correlation of solid–liquid equilibria is obtained for binary systems consisting of either the lipid mixture or one lipid in compressed CO2. With the fitted binary interactions parameters, the eutectic temperature of the ternary mixture is predicted to within 1°C of the experimental value in the range of pressure considered. The proposed evaluation method looks sufficiently accurate for representing multiphase equilibria of lipid mixtures in compressed CO2 and has direct application to gas-assisted micronization processes such as PGSS (Particles from Gas-Saturated Solution). © 2008 American Institute of Chemical Engineers AIChE J, 2008

We present a theoretical investigation on thermodynamic and transport phenomena taking place in a gas antisolvent precipitation process for binary and ternary systems containing an organic solvent,...

` () A group-contribution GC method was coupled with the perturbed-hard-sphere-chain () ( ) PHSC equation of state EOS to predict its characteristic parameters. This model can describe both equilibrium and ®olumetric properties of regular fluids and chain-like molecules. The estimation of group contributions for the characteristic ®olume, surface area, and interaction energy was based only on ®apor-pressure and saturated liquid-den- sity ®alues of low-molecular-weight compounds. It was successful in estimating the EOS parameters of high-molecular-weight compounds and chain-like molecules. Some ap- plication results show its reliability but the method was not applied to all classes of compounds. Good estimation of polymer density was obtained by GC PHSC with only the knowledge of their molecular structure. For mixtures, the original model was re- tained; binary interaction parameters were regressed from ®apor liquid equilibria of binary systems. In most cases, only one binary interaction parameter is enough to de- scribe binary systems in a wide range of temperatures. The same model is extended to the calculation of liquid liquid equilibria of a system exhibiting both upper critical () ( ) solution temperature UCST and lower critical solution temperature LCST . In sum- mary, the data required for calculating multicomponent phase equilibria are the molecu- lar structure in term of functional groups and binary interaction parameter ®alues.

The correlating and predictive capabilities of a thermodynamic model based on the perturbation theory are investigated, with reference to mixtures containing components of di!erent size and molecular interactions. The simpli"ed Perturbed-Hard-SphereChain (PHSC) equation of state is applied to a series of pure polymers, a number of solvents and pure carbon dioxide, and both volumetric and equilibrium properties are considered. The ability of the proposed model to reproduce experimental phase equilibrium data is discussed and tested with reference to binary and multicomponent mixtures, in the presence of vapor}liquid, liquid}liquid and vapor}liquid}liquid equilibria. Attention is focused on the ternary system polystyrene}cyclohexane}carbon dioxide, to test the proposed thermodynamic model in view of simulating supercritical antisolvent-induced fractionation processes. It is shown that the PHSC equation of state can be reliably used for calculating the phase behavior of such a complex system in di!erent conditions. ( 2000 Elsevier Science Ltd. All rights reserved.

The evaluation of thermodynamic properties of pure hydrofluorocarbons and hydrocarbons, and their binary mixtures is considered. A modification of the perturbed-hard- sphere-chain equation of state is applied to these compounds and tested on a large database of refrigerants, hydrocarbons and their mixtures, with reference to both volumetric and equilib- rium properties. The ability of the proposed model to reproduce experimental values is discussed. First, the theoretical background of the model is revisited in order to obtain a predictive method for the 'a priori' calculation of the values of parameters which reflect the size, shape and interaction energy of the molecule (three parameters for each pure component). Expressions to predict these values as a function of molecular quantities are presented and it is shown that the proposed model can be reliably used for calculating the properties of pure refrigerants and hydrocarbons, starting from the Bondi volume and surface area values, and the vapor pressure curve (2% error in the PVT behavior at worst). Then, the extension to mixtures is addressed. Attention is focused on the evaluation of binary interaction parameters (k ij ) for systems of refrigerant—refrigerant, hydrocarbon—refrigerant and hydrocarbon—hydrocarbon type. Vapor—liquid equilibrium data of eighteen binary systems at several temperatures have been regressed, with errors in pressure ranging below 2% for refrigerant and below 1% for hydrocarbons when using a single value of k ij for each binary pair, independent of temperature. ( 1998 Elsevier Science Ltd. All rights reserved.

A nonlinear extended Kalmanfilter has been developed to infer the outlet composition of a ternary distillation column from temperature measurements. The reliability of the developed estimator is discussed with respect to disturbances on either steam, reflux and feed flowrates. It is shown that the accuracy of the adopted vapor–liquid equilibrium model plays a crucial role. The performance of the estimator is tested by comparison with actual outlet compositions measured in a pilot plant, where the separation of a ternary mixture of ethanol, tert -butanol and water is carried out.

This paper deals with the evaluation of thermodynamic properties of pure hydrofluorocarbons. A perturbed-hard-sphere-chain equation of state was adapted to these compounds and tested on a large database of refrigerants and hydrocarbons, with reference to both volumetric and equilibrium properties. The ability of the proposed model to reproduce experimental values is discussed and comparison with that of the PHCT equation of state is presented. The model contains three parameters, which are only slightly correlated with one another. Expressions for predicting the parameter values as a function of molecular quantities are proposed. The results obtained show that the proposed model can be reliably used for calculation of pure properties of refrigerants, starting from the Bondi volume and surface area values, plus a single vapour pressure value. The results are promising in view of application to mixtures of refrigerants and long-chain hydrocarbons. In this respect, the paper can be regarded as a necessary step toward the prediction of the mixture behaviour of refrigerants and the effect of the presence of the lubricant oil in the mixture.

A method for testing the thermodynamic consistency of binary and isothermal vapor-liquid equilibrium data at moderate and high pressures is proposed, using a ϕ-ϕ approach. The Redlich-Kwong-Soave equation of state with Huron-Vidal mixing rules at infinite pressure is used in the data-reduction procedure, and a Margules equation is used to calculate the activity coefficients at infinite pressure. This model is shown to be thermodynamically consistent. The proposed method allows us to check consistency of vapor-liquid equilibrium data in the presence of components at the gaseous and supercritical states.

Supercritical fluids are being increasingly used as media for fine particles formation: the most important techniques are the rapid expansion of a supercritical solution process (RESS), the particles from gas-saturated solutions process (PGSS), and the supercritical antisolvent recrystallization process (SAS). To verify the feasibility of such processes, and to optimize the choice of operative variables, it is important to understand the phase behavior of the systems involved. To perform a thermodynamic analysis, an equation of state has to be used to take into account the effects of pressure; moreover, a solid phase is involved, and the heavy component is usually a high molecular weight and poorly characterized compound. In this work the Peng−Robinson equation of state with classical mixing rules and one or two binary interaction parameters are used. The fugacity of the heavy component in the solid phase is calculated by means of a subcooled liquid reference state: only heat of fusion and melting tempe...

Publisher Summary A high-pressure circulation-type apparatus is designed and constructed in this chapter to investigate the vapor–liquid equilibria (VLE) of systems containing limonene, linalool, and supercritical carbondioxide (scCO2). The main piece of the equipment is a high-pressure phase equilibrium cell of approximately 100 cm3. The apparatus includes a compressed-air actuated piston-pump that allows circulating one or both phases to bring the vapor and liquid in close contact with each other. This pump, the cell, and all the related valves are placed in a constant-temperature water bath to have and to keep uniformly the desired temperature. VLE data of binary and ternary systems of limonene, linalool, and scCO2 can be determined in the ranges of pressure and temperature of interest for the deterpenation of coldpressed orange oil. The preliminary results obtained for the binaries CO2–linalool and CO2–limonene are compared in the chapter to data already published with acceptable accuracy and well correlated by a modified Soave–Redlich–Kwong (SRK) equation of state.

This paper is a contribution to the development of a method for the prediction of the thermodynamic behaviour of refrigerant mixtures at low and moderate pressure, for which experimental data are not always available. The proposed model is based on a modified Redlich-Kwong-Soave equation of state, with mixing rules as proposed by Huron and Vidal. The calculation of the attractive parameter is based on infinite-pressure activity coefficients according to Soave et al. Activity coefficients are expressed by a group-contribution model derived from UNIFAC. A list of groups and subgroups is proposed for CFCs, HCFCs, HFCs and FCs. Two interaction parameters are regressed from experimental infinite-dilution activity coefficients of binary mixtures. As a result, only the structure, critical constants and vapour pressure of pure components are needed to calculate thermodynamic properties of refrigerant mixtures. The proposed approach is able to predict experimental data with satisfactory accuracy over the full composition range.

Soave, G., Barolo, M. and Bertucco, A., 1993. Estimation of high-pressure fugacity coefficients of pure gaseous fluids by a modified SRK equation of state. Fluid Phase Equilibria, 91: 87-100. This paper considers the prediction of pure-compound fugacity coefficients at high temperature and high pressure by a modified form of the Redlich -Kwong equation of state (G. Soave, Chem. Eng. Sci., 27: 1197), with an added volume shift as proposed by A. Peneloux and E. Rauzy, Fluid Phase Equilibria, 8: 7-23. Two quantities are involved: a volume translation σ and an attractive parameter α. At each temperature and pressure, they were first determined from the corresponding experimental Z, φ values; outside the critical area, σ is independent of temperature and pressure and a depends on temperature only. Since the value of σ is close to that determined from liquid densities, the value was assumed from the liquid density at 20°C or at the boiling point. Experimental Z, φ values were regressed directly, to determine the best values of α at each temperature. Owing to the small correction of σ, it was impossible to reproduce satisfactorily both Z and φ data, so it was decided to consider fugacity coefficients alone. Several literature equations for a were considered. When parameters were determined by regression of experimental vapor pressures, none of the equations were finally satisfactory; 12α gives a linear function of 12T, as in the one-parameter expression proposed in 1972 by Soave, which was selected. A criterion was found to estimate the single parameter m from the value of the acentric factor, with a negligible loss of accuracy. Fugucity coefficients can be predicted accurately for non-polar compounds; for alcohols and polar compounds they are less satisfactory, but a good accuracy can be attained by adjusting both m and σ on experimental data.

The capability of a modified Carnahan—Starling—Van der Waals equation of state to correlate binary solid or liquid solubility data in a supercritic

Equations of state of different families are shortly described and reviewed. Simple models, such as the cubic equations of state, are considered in their performance to more sophisticated ones. Furthermore, different mixing rules are discussed, including the simple, random, and the complicate density-dependent mixing rules. Attention has been focused on the problem of the parameter estimation in equations of state: calculations are presented showing how an equation of state can be tuned for representing thermodynamic properties. Limitations of multiproperty and mixture prediction are also put forward.

A modification of the perturbed-hard-sphere-chain equation of state (EOS) is used to describe vapor–liquid (VLE) and liquid–liquid equilibria (LLE) of mixtures containing new-generation refrigerants and a lubricant oil. For refrigerants, pure-component parameters are obtained from thermodynamic data. For the oil, they are predicted by a group-contribution method, and the calculation is checked on liquid density values of polyol-ester lubricants. Extension to mixtures is performed by using conventional one-fluid mixing rules with binary interaction parameters regressed from VLE experimental data. VLE calculations are reported for mixtures containing a refrigerant and a polyol-ester lubricant over wide temperature and concentration ranges. The thermodynamic condition for LLE is checked. If two liquid phases are present, LLE is calculated and compared with experimental measurements.

A thermodynamic analysis is developed to interpret the influence of temperature and pressure in the production of solid lipid nano- and microparticles by a high-pressure technique named particle from gas-saturated solution (PGSS). The pressure−temperature charts show three regions above the P−T solid−liquid−fluid coexistence curve, from which sub-cooled solid, solid−liquid, or liquid products can be obtained. The relation between the initial and final thermodynamic properties of the PGSS process were calculated by solving simultaneously the energy balance and a proper equation of state. The expansion of high-pressure CO2−lipid saturated solution through the micrometric nozzle was represented by a transformation at constant total enthalpy. To represent the equilibrium and thermodynamic behavior of CO2−lipid systems the perturbed-hard-sphere-chain theory (PHSCT) was used. As examples, CO2 absorption isotherms in lipids and residual properties of high-pressure tristearin−CO2 and tristearin−phosphatidylcoline...