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Fundacao para a Ciencia e a Tecnologia through project (PEst-C/LA0006/2013). The authors also thank Prof. Madalena Dionisio and Dr Natalia Correia for their support with the DSC analyses. Herein a straightforward approach for the enhancement of the water solubility of common antibiotic and NSAID active pharmaceutical ingredients (APIs) is presented. The APIs are converted into ionic liquids (API-ILs) and molten salts by combination with the organic superbases TMG, DBU and DBN. The prepared superionic liquids were characterized by 1H and 13C NMR as well as FTIR spectroscopy and elemental analysis. Most products are amorphous non-polymorphic room temperature ionic liquids with very high solubility in water, which may enhance the bioavailability of the API-ILs in comparison with the parent drugs. authorsversion published

In this report, novel systems, based on highly abundant saccharides, d-mannose, d-glucose, β-cyclodextrin, alginic acid and mannitol, in combination with an organic superbase, tetramethylguanidine (TMG) or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), are studied for carbon dioxide capture. With d-mannose and d-glucose, several ratios of equivalents of alcohol groups of saccharide : superbase were tested: 1, 0.625, 0.5 and 0.25. High wt% values of CO2 uptake were obtained with TMG-based systems. However, TMG itself can react directly with CO2, and, in the presence of d-mannose, competition between carbonate and carbamate based products was established. In order to circumvent this competition and obtain exclusively the carbonate-based product, DBU was used instead as an organic superbase. In the d-mannose series the highest result was obtained with a d-mannose : DBU ratio eq. = 0.625 (13.9% CO2 uptake, 3.3/5 alcohol groups converted into carbonates). A more effective stirring system, designed to overcome the high viscosity of the products, allowed the use of a d-glucose : DBU = 1 : 1 ratio with 11.5 wt% of CO2 uptake and 2.47/5 alcohol groups converted into carbonates. Additionally a DSC thermal study was performed in order to study the stability/reversibility of the CO2 loaded systems.

Purpose: This paper describes the development and test of physical and virtual integrated augmentative manipulation and communication assistive technologies (IAMCATs) that enable children with motor and speech impairments to manipulate educational items by controlling a robot with a gripper, while communicating through a speech generating device. Method: Nine children with disabilities, nine regular and nine special education teachers participated in the study. Teachers adapted academic activities so they could also be performed by the children with disabilities using the IAMCAT. An inductive content analysis of the teachers’ interviews before and after the intervention was performed. Results: Teachers considered the IAMCAT to be a useful resource that can be integrated into the regular class dynamics respecting their curricular planning. It had a positive impact on children with disabilities and on the educational community. However, teachers pointed out the difficulties in managing the class, even with another adult present, due to the extra time required by children with disabilities to complete the activities. Conclusions: The developed assistive technologies enable children with disabilities to participate in academic activities but full inclusion would require another adult in class and strategies to deal with the additional time required by children to complete the activities. Implications for Rehabilitation Integrated augmentative manipulation and communication assistive technologies are useful resources to promote the participation of children with motor and speech impairments in classroom activities. Virtual tools, running on a computer screen, may be easier to use but further research is needed in order to evaluate its effectiveness when compared to physical tools. Full participation of children with motor and speech impairments in academic activities using these technologies requires another adult in class and adequate strategies to manage the extra time the child with disabilities may require to complete the activities.

The effect of phase equilibrium on the kinetics of O2-oxidation of limonene was studied. Vapour–liquid equilibrium measurements of the system (CO2 + O2 + limonene) were performed at 328 K and 8, 10, 10.7 and 11 MPa. In an attempt to establish a relation between vapour–liquid equilibrium data and the kinetics of limonene oxidation, different reactions were performed at 328 K and at different CO2 total pressures of 9.3 MPa, 10 MPa and 10.3 MPa (with the reaction mixture being biphasic) and at 12.2 MPa (in a single supercritical phase). The volumetric concentration of O2 in the liquid phase increased as CO2 was added to the system, although this behaviour was only observed close to the critical region. Kinetics of oxidation reactions performed at biphasic conditions, suggests that is the volumetric concentration of O2 in the liquid phase that is controlling the reaction rates.

Vapour–liquid equilibrium of CO2 + [0.00871 glycerol + 0.99129 (ethanol or 1-propanol or 1-butanol)] mixtures was measured at the temperatures of 313.15 K and 333.15 K, and close to the critical line, at pressures up to 12 MPa. On the liquid side, the bubble points measured for these ternary mixtures follow closely the behaviour of VLE reported by several authors for the corresponding binary mixtures without glycerol. On the vapour side, however, dew points for the ternary mixtures deviate significantly from VLE results for the binaries. A correlation of the results obtained for the CO2 + glycerol + ethanol mixture with the Peng–Robinson equation of state, admitting quasi-binary behaviour, equally yields good agreement on the liquid side, and significant deviations on the vapour side.

Vapour–liquid equilibrium measurements for binary and ternary (carbon dioxide + β-myrcene and carbon dioxide + β-myrcene + hydrogen) systems have been carried out at 323.15 K and pressures in the range from 7 MPa to the critical pressure of the binary mixture and at pressures from 10 to 14 MPa for the investigated ternary systems. Samples from the coexisting phases were taken, and compositions were determined experimentally. Results were correlated using the Peng–Robinson and the Soave–Redlich–Kwong equations of state with the Mathias–Klotz–Prausnitz mixing rule. The set of interaction parameters for the employed equations of state and applied mixing rule for the system of CO2 + β-myrcene and of CO2 + β-myrcene + H2 were obtained. Additionally, the volume expansion of the liquid phase for the binary mixtures (carbon dioxide + β-myrcene and carbon dioxide + limonene) were measured at 323.15 K and at pressures from 4 MPa up to very close to the critical pressure of the mixture. The ratio of liquid phase total volumes at the given pressure and at 4 MPa was calculated.

Chalcones are a privileged class of compounds reported to have important biologically active properties. Supercritical carbon dioxide can play a promising role in chalcones’ processing, either in view of natural compounds extraction or more likely as an alternative solvent in organic chemical reaction. In this work, the phase behaviour of 1,3-diphenyl-2-propenone, the core structure of chalcones, in dense CO2 was explored. The influence of dense carbon dioxide in chalcone melting point was studied for pressures up to 20 MPa. Equilibrium experiments in supercritical CO2 were performed in the pressure range from 9 to 20 MPa, at temperatures between 308 and 338 K.

The effect of hydrogen partial pressure on the hydrogenation of limonene in high-pressure carbon dioxide, catalysed by carbon-supported palladium, was studied. Experiments were performed at various hydrogen pressures in the range from 2.5 up to 4.4 MPa at a fixed total pressure of 12.5 MPa, where the reaction mixture remains biphasic—liquid + gas. In these conditions, the liquid phase volume is expanded in relation to the initial volume of limonene in a fashion that is strongly dependent on the hydrogen to carbon dioxide pressure ratios. Surprisingly, the main factor in the kinetics of hydrogenation turns out to be the concentration (mol dm −3 ) of limonene, which decreases due to the volumetric expansion of the liquid phase when the CO 2 pressure increases.

The possibility of recovering biologically active polyphenolic compounds from hydro-alcoholic mixtures, with supercritical carbon dioxide, was investigated. In order to evaluate the viability of this fractionation step, vapor−liquid equilibrium measurements on the quaternary systems (CO2 + ethanol + water + phenolic compound = resveratrol, p-coumaric acid, quercetin-3-glucoside, and catechin) were performed at 40 °C and at (15 and 20) MPa. The separation factors for hydro-alcoholic mixtures of different compositions in water + ethanol were determined and compared.

The phase behaviour of the binary mixture of carbon dioxide and the cobalt complex dicarbonyl(η 5 -cyclopentadienyl)-cobalt, CpCo(CO) 2 , has been investigated. This organometallic compound is one of the most effective catalysts of cyclotrimerization reactions of arylisocyanates and alkynes. Vapour–liquid equilibrium (VLE) measurements were undertaken in a static analytical apparatus at 313.15, 323.15 and 363.15 K at pressures up to 15 MPa. p , T isopleths were measured by a synthetic method in a Cailletet apparatus. Nine different compositions ranging from 17.56 to 94.23 mol% of CO 2 were measured up to 15 MPa. Modelling with the Peng–Robinson equation of state (PR EOS) gave reasonable results in the correlation of the experimental phase equilibrium compositions using two temperature-dependent interaction parameters.

Vapour–liquid equilibrium compositions were measured for mixtures of δ-tocopherol and carbon dioxide, at pressures from 9 up to 27 MPa, and four temperatures between 306 and 333 K. The system exhibits liquid–liquid equilibrium at high pressures, similarly to previous results for mixtures of α-tocopherol with carbon dioxide. The results were correlated with the Peng–Robinson equation of state, using the Panagiotopoulos–Reid combination rules. Comparison of the solubilities of δ-tocopherol and α-tocopherol in supercritical carbon dioxide was performed using Chrastil’s equation to correlate the data. The number of solvent CO 2 molecules per solute molecule was calculated in both cases. An enthalpy of solvation per mole of CO 2 of −10 kJ mol −1 was obtained.

Since determining experimentally a wide variety of thermophysical properties—even for a very small portion of the already known room temperature ionic liquids (and their mixtures and solutions)—is an impossible goal, it is imperative that reliable predictive methods be developed. In turn, these methods might offer us clues to understanding the underlying ion–ion and ion–molecule interactions. 1-Butyl-3-methylimidazolium tetrafluoroborate, one of the most thoroughly investigated ionic liquids, together with water, the greenest of the solvents, have been chosen in this work in order to use their mixtures as a case study to model other, greener, ionic liquid aqueous solutions. We focus our attention both on very simple methodologies that permit one to calculate accurately the mixture's molar volumes and heat capacities as well as more sophisticated theories to predict excess properties, pressure and isotope effects in the phase diagrams, and anomalies in some response functions to criticality, with a minimum of information. In regard to experimental work, we have determined: (a) densities as a function of temperature (278.15 < T/K < 333.15), pressure (1 < p/bar < 600), and composition (0 < xIL < 1), thus also excess molar volumes; (b) heat capacities and excess molar enthalpies as a function of temperature (278.15 < T/K < 333.15) and composition (0 < xIL < 1); and (c) liquid–liquid phase diagrams and their pressure (1 < p/bar < 700) and isotopic (H2O/D2O) dependences. The evolution of some of the aforementioned properties in their approach to the critical region has deserved particular attention.

Phase equilibrium for CO2 + 2-phenylethanol and CO2 + 3-methyl-1-butanol was measured. The two alcohols are both major constituents of wine aroma. The experimental apparatus includes a transparent high-pressure cell made of a sapphire cylinder, which allows full visual observation of the inside. Measurements were performed at temperatures of (313.1 and 323.1) K and at pressures from (8 to 24) MPa for the system CO2 + 2- phenylethanol and pressures from (5 to 10) MPa for the system CO2 + 3-methyl-1-butanol. The experimental results were fitted with the Stryjek−Vera modification of the Peng−Robinson cubic equation of state, using the composition-dependent mixing rules of Panagiotopoulos and Reid.

In the search for understanding of several types of abnormal thermodynamic behaviour in the vicinity of critical lines of binary liquid mixtures, we have revisited an apparently forgotten relationship between the pressure dependence of the critical temperature and the second derivatives with respect to the composition of the volumetric and enthalpic properties of the mixture. We refer to an equation originally developed in the fifties by Prigogine and Defay and soon afterwards analysed by others. Under some restrictive assumptions, the T–p slope of the critical locus can simply be inferred from the ratio between vE and hE. The interest and usefulness of this approximate relation is self-evident. Values for any one of the three properties involved,(dT/dp)c, vE or hE, can be assessed based on the availability of the other two. Moreover, the amplitude of the divergence of thermodynamic response functions to criticality are intimately associated with the slope of the critical locus. A link between critical behaviour and solution excess properties is thus established. For instance, double critical points tend to occur if one of the excess properties changes its sign as the temperature or pressure is varied. In this work, we have started a detailed study of the practical limits of validity of the approximate relation. Five binary liquid mixtures were tested, all of them sharing a UCST/LCSP-type of phase transition. Although, from a theoretical perspective, the original second-derivatives approach should perform better, in practice, the direct ratio of the excess properties constitutes a superior strategy for obtaining (dT/dp)c values. The underlying reasons for this are discussed in detail. The T–p critical slope is normally found to play a secondary role in assessing the critical amplitudes of diverging thermodynamic functions.

A mixture that partially resembles the distillates obtained from the deodorization process of olive oils was used as a case study to test and develop mass-transfer models valid for supercritical fluid processes. Such models are useful engineering tools that provide a theoretical background for the scale-up of industrial plants. In the first part of this series of papers, the fractionation performance of the model mixture squalene/methyl oleate by supercritical carbon dioxide in a countercurrent packed column containing a corrugated gauze-type structured packing was presented. This second part presents a general correlation for predicting the mass-transfer efficiency of the high-pressure packed column. Several correlations taken from the literature were used and their results compared with the experimentally determined mass-transfer coefficients and holdup. A model formerly developed for distillation columns was found to be valid for our high-pressure system. It was found that the area of the gauze packing...

The design of countercurrent packed columns operating under high-pressure conditions requires knowledge of their hydrodynamic and mass transfer behavior. A laboratory-scale continuous supercritical fluid extraction apparatus was developed with the purpose of obtaining data needed for such designs. The current work is part of a study to assess the feasibility of supercritical carbon dioxide in fractionating a mixture of squalene and methyl oleate. This mixture partly emulates the residues obtained from the olive oil refining process. Phase equilibrium data were previously measured to evaluate the best operating conditions. Here, we examine the continuous fractionation of two different feeds, with 40 and 70 wt % of squalene, under various extraction conditions. An extraction yield as high as 90 wt % of squalene in the raffinate phase was achieved. The selectivity and extraction efficiency were determined as functions of the oil-to-carbon dioxide flow ratio as well as the reflux ratio. In a subsequent paper ...

Several physical properties of liquids as well as those of the coexistence between liquid and solid can be determined at absolute negative pressures. Examples for this include thermal pressure coefficients, loci of temperature of maximum density, melting lines, speed of propagation of low-intensity sound waves, and (p, T, x) conditions of occurrence of liquid/liquid phase separation. Three model temperature-pressure cycles, which allow for the measurement of temperature-pressure conditions of the occurrence of maxima of liquid density, negatively sloped fusion lines, and the upper critical solution temperature (UCST) of liquid solutions in these metastable regimes are described. A new apparatus for measuring negative pressures was developed. The temperature and pressure are determined within an uncertainty of ±0.05°C and ±5 bar, respectively. Water and heavy water have been used as testing systems with respect to the location of their temperatures of maximum density (TMD) loci. Empirical equations of state whose parameters have been fitted to experimental data located in the normal positive pressure region have proven to extrapolate well to the negative pressure regime. Furthermore, an attempt was made to use SAFT in order to provide a more theoretically founded framework. Preliminary results for gallium have shown that a TMD exists 45 K inside the supercooled regime, and that the continuation of its melting line down to −80 bar evolves with a slope of −515±25 bar·K−1.

Positive excess molar Gibbs energies were detected in liquid mixtures of (36Ar+40Ar) using a high-accuracy double differential manometric technique. The vapor pressure differences between a mixture of (36Ar+40Ar) and 40Ar and between 36Ar and 40Ar were measured simultaneously with the vapor pressure of 40Ar. Four different mixtures were selected and 80 temperatures were chosen in the 85–96 K temperature range. The results show that the vapor pressure of an equimolar liquid mixture is greater than what would be expected if the solution were strictly ideal, by approximately 2.5 Pa in the 85–96 K temperature range. The calculated excess Gibbs energy for the equimolar mixture at 85 K is G1/2E=(0.021±0.004) J mol−1. For the excess molar enthalpy a value of H1/2E=(0.12±0.04) J mol−1 was found. The corresponding deviations from Raoult’s law are therefore extremely small (3 to 4 orders of magnitude smaller than those typically found in binary mixtures of nonisotopic constituents). The evidence of nonideal behavio...

Phase equilibrium ratios of poly(ethylene glycol)s (PEG) of average molar masses 200, 400 and 600 with supercritical CO 2 , were measured at 20 MPa and 313 K. Additional measurements with the monomer, ethylene glycol and with PEG 400 at 293 K were also performed. Three different methods of analysing the PEG amounts in each phase were used. Using a size exclusion chromatography procedure (SEC/GPC) we have observed a relevant fractionation of the polymer in the case of the system CO 2 +PEG 600. Some of the results obtained differ significantly from previously published values on the same systems.

Fluid phase equilibrium data is essential for the design of supercritical fluid extraction columns. Examples are given of a feasibility study and an application to the design of a separation column involving the measurement of phase diagrams for ternary mixtures.

In order to analyse the effect of supercritical fluid (SCF) addition on polymer viscosity we have used, for the first time, a high precision vibrating wire instrument, for the simultaneous measurement of viscosities and densities of a SCF-saturated polymer. For the density measurements, this technique makes use of the buoyancy force exerted by a fluid on a solid sinker, detected by means of a vibrating wire sensor placed inside the measuring cell. The viscosity and density of the fluid are obtained by analysis of the resonance curve of the vibrating-wire, using a rigorous model for describing the hydrodynamic effects of the fluid on the wire motion. Results of the preliminary measurements carried out on a commercial linear thermoplastic oligomer [Poly(ethyleneglycol) 400] saturated with CO 2 are presented, in a range of temperatures from 313 to 348 K (3 isotherms) and at pressures up to 25 MPa. A sharp decrease of the viscosity was observed for all temperatures. The highest viscosity reduction was reached at the lowest temperature.

The vapor pressure isotope effect of samples of isotopically substituted methane and their mixtures was measured as a function of temperature and mixture composition: The differential vapor pressure between CHiD4−i (with i=0 or 4) and CHjD4−j (with j=1, 2, or 3), the differential vapor pressure between mixtures of (CHiD4−i+CHjD4−j) and CH4 (if i=4) or CHjD4−j (if i=0) and the absolute vapor pressure of CH4 (if i=4) or CHjD4−j (if i=0), were measured simultaneously between 96 and 121 K for mixtures of nominal composition 0.25, 0.50, and 0.75 mole fraction in the reference methane species. The p(x,T) data were used to calculate the excess molar Gibbs energy function, GE(x,T) and the excess molar enthalpy HE(x), assuming that this last function is independent of temperature in the experimental range. The deviations from ideal behavior are very small, GE being only some tenths of J/mol for equimolar mixtures. The experimental GE values compare well with estimated results based on a modified version of the sta...

The difference between the vapor pressure of completely protiated or deuterated methane (CH4 or CD4) and partially deuterated methanes (CH3D, CH2D2, or CHD3) has been measured over the 96–121 K temperature range. The vapor pressure data obtained were fitted to equations of the type T ln(p/p)=A/T+B, where the prime always refers to the lighter molecule. Within the studied temperature range, the vapor pressure isotope effect was found to be “inverse” (p>p) for all the systems, except in the low-temperature range of the (CH4/CH3D) system. Our data agrees with other results found in the literature, both experimental and theoretical. Differences in the enthalpy of vaporization were calculated from the experimental results. In the case of the (CH4/CHD3) system, our vapor pressure isotope effect (VPIE) results were also compared with liquid–vapor isotope fractionation factor (LVIFF) data from other authors.

Fluid phase equilibria for (carbon dioxide + Glycidol) were studied at temperatures from 292 K to 343 K and pressures up to 27 MPa. Six (vapour + liquid) pressure against composition isotherms, from T = 298 K to T = 343 K, were measured using an analytical method, in the pressure range from 9 MPa to 27 MPa. At lower pressures, the ( p , T ) projection of the three-phase (liquid + liquid + vapour) equilibrium surface was followed from T = 292 K up to the critical end-point, at T = 309.00 K and p = 7.966 MPa. An attempt to fit several cubic equations of state to the VLE isotherms, using different mixing and combining rules, was most successful for the Soave–van der Waals equation with the Panagiotopoulos–Reid combining rule. This, and other equations of state with good fitting results, were used to predict the behaviour of the system for higher pressures and temperatures than those of this experimental study.

The vapor pressure differences between a mixture of (CH4+CD4) and CH4 and between CD4 and CH4 were measured simultaneously with the CH4 vapor pressure. This was done at 29 temperatures between 97 and 122 K, and for six different mixtures, of compositions 0.150, 0.250, 0.375, 0.500, 0.625, and 0.750 mole fraction in CD4. These mixtures exhibit very small positive deviations from Raoult’s law. Calculated excess Gibbs energies for equimolar mixtures were 0.60 J mol−1 at 100 K and 0.42 J mol−1 at 120 K. These values of GE are 2 to 3 orders of magnitude smaller than those typically found in binary mixtures of simple nonisotopic species. The molar excess enthalpy, calculated from the temperature dependence of GE, is HE(x=0.5)=(1.5±0.2) J mol−1. The experimental results were used to test three theoretical models: the vdW‐1 fluid theory, 1cLJ perturbation theory, and the theory of isotope effects in mixtures. While the first two proved to be inadequate, the isotope effect theory agrees well with experiment.

This paper provides a short overview of developments in the field of supercritical fluids in the last thirty yearsand of actual and prospective applications

A recent suggestion on the applicability of supercritical fluid extraction to the deacidification of olive oils of high acid content was based on solubility data in clear disagreement with the results of other authors. In this work, we measured the solubilities of substances chosen for their importance in that extraction process, namely pure glycerol trioleate, the most abundant triglyceride in olive oil, and of a husk oil with a high acid content. Our results agree well with some of the previous reports on this subject. These seem to be a trustworthy data base, but more results are needed for a definite conclusion about the technical feasibility of the process.

Aqueous solutions of a copolymer derivative of a polyacrylamide showed very interesting behavior, that in which the system evolves from one kind of double criticality (pressure−hypercritical point) to another (temperature−hypercritical point) as polymer molecular weight decreases. While in the neighboring region of the former point one expects a change from contraction to expansion upon mixing with increasing pressure; in the latter, mixing should be accompanied by a change in the sign of the excess enthalpy as temperature increases. L−L equilibria studies were performed in a wide range of (T, p) experimental conditions (300 < T/K < 460, 0 < p/bar < 700). Poly(N-isopropylacrylamide), usually called PNIPAAM, and its copolymer derivative poly(N-isopropylacrylamide/1-deoxy-1-methacrylamido-d-glucitol), herein referred to as CP, were investigated for several chain lengths and compositions. An He/Ne laser light scattering technique was used for the determination of cloud-point (T, p, x) conditions. The experimental results were used to assist in the determination of computed values at temperatures beyond experimental accessibility, which are obtained by the application of a modified Flory−Huggins model. The model also estimates the excess properties of these solutions. Because of the intrinsic self-associating nature of these systems, all studied solutions show a lower critical solution temperature (LCST). Both modeling results and H/D isotope substitution effects suggest also the existence of upper critical solution temperatures (UCST) and therefore closed-loop-type phase diagrams. However, these upper-temperature branches are experimentally inaccessible. Pressure effects are particularly interesting. For a low-MW CP, experimental data display a tendency toward a reentrant T−p locus, which supports the conjecture that these systems are inherently of the closed-loop type. In the cases of PNIPAAMs and high-MW CPs, the T−p isopleths show extrema. The copolymer aqueous solutions under study in this work model a single chemical system where pressure−hypercritical behavior evolves to a temperature−hypercritical one as the chain length decreases.

Publisher Summary Olive oils with large quantities of free fatty acids must be refined to get a salable product. Deacidification is currently done by physical or chemical processes that may alter the organoleptic profile of the oil. Supercritical fluid deacidification of these oils has been suggested as a potential ecological alternative process, because it uses nontoxic solvents and low operating temperatures. The use of supercritical carbondioxide as a solvent for the deacidification of olive oils has shown the selective preference of carbon dioxide toward the free fatty acids (FFA) fraction and at the same time retaining the nutritional constituents of the oil. This chapter reviews a study carried out to evaluate the best operational conditions for the deacidification of olive oils by supercritical extraction (SCE) and to evaluate the design of an extraction unit. To assess the feasibility of the olive oil deacidification plant, an economical study that is described in the chapter was performed by simulating all the debits and credits involved in the industrial plant. The analysis was performed at constant prices instead of real prices and the units are in Portuguese escudos (PTE).

Using an expansion method, 32 ( p, V, T ) points were measured for liquid hydrogen chloride between the normal boiling temperature (188.18 K) and 245 K, and at pressures between the vapour pressure and 5 MPa. An equation of the Benedict-Webb-Rubin type was fitted to these results. Vapour-pressure measurements reported by several authors were correlated using a vapour-pressure equation given by Goodwin. (1) From these equations, orthobaric liquid volumes, isothermal compressibilities, and configurational internal energies of the liquid were calculated at regular intervals of temperature.

High pressure extraction of vegetable fatty oils by supercritical fluid carbon dioxide was investigated. Pressures from 9 to 20 MPa at 40°C were used. The extracts were monitored by high temperature capillary gas chromatography for sterol and tri-glyceride composition. The quality of the extracted oils was evaluated by numerical taxonomy methods. The extraction products compared well with the characteristics of commercial fatty oils of the same vegetable origin. No significant qualitative variation was detected in the pressure range studied.

Mesures des pressions de vapeur de CH 4 et CD 4 en phase liquide a douze temperatures comprises entre 95 et 122 K. Evaluation des enthalpies molaires de vaporisation

The equation of state of liquid nitrogen, liquid methane, and a mixture {(1−x)N2 + xCH4}(1) with x = 0.5 has been measured at 110.09, 113.70, 116.30, and 120.00 K to 138 MPa (or, with methane, to the freezing pressure). Similar studies have been made on two other mixtures, with x = 0.7 and x = 0.3, at the highest and lowest of these temperatures. The results show that the excess volume VE, while negative at low pressures, rapidly increases with rising pressure and eventually has a small positive and approximately constant value. The curve of VE against x becomes more symmetrical at higher pressures. The change in the excess functions GE, HE, and SE with rising pressure has been evaluated; GE proves to be much less affected by pressure than HE and SE. The experimental isotherms for the pure and mixed liquids have been used to test the ability of two-parameter equations of state to fit p, V, T results of this kind. Four equations were selected for this trial, namely the van der Waals equation, the Redlich-Kwong equation, and two equations which use the Carnahan-Starling expression for the term involving the b-parameter and the Redlich-Kwong or van der Waals term incorporating the a-parameter. The best overall fit of all the experimental isotherms from 0 to 80 MPa is given by the Carnahan-Starling-van der Waals.

Measurements are reported of the total vapour pressure of liquid mixtures of krypton + ethene at the triple-point temperature of krypton (115.77 K) as a function of composition, of the excess molar volumes of the mixtures at the same temperature, and of the excess enthalpy at 117.7 K. These results are compared with those obtained for similar systems, namely methane + ethene and xenon + ethene, and interpreted in the light of some simple theories of liquid mixtures.

Equations d'etat pour Kr et Xe liquides et de melanges equimolaires entre 180 et 195 K. Mesures des volumes d'exces et des enthalpies