Isothermal Compressibility Coefficient Research Articles

Effect of Gramicidin D on the Compressibility and Volume Fluctuations of DPPC – Peptide Bilayers: A Densitometry and Sound Velocimetry Study

The effects of increasing gramicidin D (gD) concentration on the partial specific volume, vo, and the adiabaticcompressibility coefficient of the lipid, βSlipid of the bilayer reveals a continual decrease in ?o and βSlipid (within therange of concentration studied) with concentration, except between 5 and 7.5 %, where a very slight decrease wasobserved. At gD concentrations higher than 5 mol%, the isothermal compressibility coefficient, βTlipid is greater thanβSlipid at the gel-fluid region by ? 10 – 20 % in the entire temperature range covered. The maximum value of therelative volume fluctuation of 12 % is reached for DPPC at the main transition, and is strongly dampened uponaddition of gD. A gradual decrease in the calculated relative volume fluctuations with gD concentration at Tm isobserved between concentrations 1 and 10 mol%.

Thermodynamics of liquid-liquid crossover transition in liquid Si15Te85eutectic alloy

Specific heat of liquid Si 15 Te 85 was measured using both the adiabatic scanning calorimetry and modulation calorimetry. The specific heat has a very broad peak around 660°C of which the peak value is 46 J/mol.K. The results are totally different from the previous results that the specific heat is as large as 140 J/mol.K at the liquidus temperature and decreases rapidly with raising temperature. Combining the molar volume and sound velocity as a function of temperature, the thermodynamic susceptibilities, i.e. constant pressure specific heat, isothermal compressibility and thermal expansion coefficient, have been evaluated. Their temperature dependences and magnitudes are in good accordance with the predictions for a crossover transition in a liquid. Comparison is made to a liquid-liquid crossover transition in Ge 15 Te 85 which is sharpest among crossover liquid-liquid transitions of this kind so far found.

Compressibilities and Volume Fluctuations of Archaeal Tetraether Liposomes

Bipolar tetraether lipids (BTLs) are abundant in crenarchaeota, which thrive in both thermophilic and nonthermophilic environments, with wide-ranging growth temperatures (4–108°C). BTL liposomes can serve as membrane models to explore the role of BTLs in the thermal stability of the plasma membrane of crenarchaeota. In this study, we focus on the liposomes made of the polar lipid fraction E (PLFE). PLFE is one of the main BTLs isolated from the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius. Using molecular acoustics (ultrasound velocimetry and densimetry), pressure perturbation calorimetry, and differential scanning calorimetry, we have determined partial specific adiabatic and isothermal compressibility, their respective compressibility coefficients, partial specific volume, and relative volume fluctuations of PLFE large unilamellar vesicles (LUVs) over a wide range of temperatures (20–85°C). The results are compared with those obtained from liposomes made of dipalmitoyl-L- α-phosphatidylcholine (DPPC), a conventional monopolar diester lipid. We found that, in the entire temperature range examined, compressibilities of PLFE LUVs are low, comparable to those found in gel state of DPPC. Relative volume fluctuations of PLFE LUVs at any given temperature examined are 1.6–2.2 times more damped than those found in DPPC LUVs. Both compressibilities and relative volume fluctuations in PLFE LUVs are much less temperature-sensitive than those in DPPC liposomes. The isothermal compressibility coefficient ( β T lipid) of PLFE LUVs changes from 3.59 × 10 −10 Pa −1 at 25°C to 4.08 × 10 −10 Pa −1 at 78°C. Volume fluctuations of PLFE LUVs change only 0.25% from 30°C to 80°C. The highly damped volume fluctuations and their low temperature sensitivity, echo that PLFE liposomes are rigid and tightly packed. To our knowledge, the data provide a deeper understanding of lipid packing in PLFE liposomes than has been previously reported, as well as a molecular explanation for the low solute permeation and limited membrane lateral motion. The obtained results may help to establish new strategies for rational design of stable BTL-based liposomes for drug/vaccine delivery.

Acoustic and thermodynamic properties of the binary liquid system n-dodecane+n-hexadecane

By the method of direct measurement of the pulse-passage time, the velocity of sound in a binary liquid mixture n-dodecane+n-hexadecane has been investigated in the temperature range 298–433 K and in the pressure range 0.1–100.1 MPa. The maximum measurement error is 0.1%. Experimental data on the velocity of sound for the investigated mixture have been obtained for the first time. On the basis of the data on the velocity of sound, we have determined the density, the isobaric expansion coefficient, the isobaric and isochoric heat capacities, and the isothermal compressibility coefficient of a mixture of three compositions in the 298–433 K temperature range and in the 0.1–100.1 MPa range of pressures. The coefficients of the Tate equations in the above range of parameters have been calculated. A table of thermodynamic properties of the mixture is presented.

Densities and Volumetric Properties of Ethylene Glycol + Dimethylsulfoxide Mixtures at Temperatures of (278.15 to 323.15) K and Pressures of (0.1 to 100) MPa

Densities, ρ, and compressibility coefficients, k = (vo − v)/vo, of ethylene glycol (1) + dimethylsulfoxide (2) mixtures were measured over the whole concentration range at pressures of (0.1 to 100) MPa and temperatures of (278.15 to 323.15) K. Excess molar volumes, isothermal compressibility, and thermal isobaric expansivity coefficients as well as thermal pressure coefficients were calculated. It was revealed that concentration dependences of specific volumes, v, at some state parameters passed a minimum. The shift of minimum position to molar fraction x2 = 0.5 was observed with increasing pressure and decreasing temperature. The negative excess molar volumes, VmE, indicated a compression of EG (1) + DMSO (2) systems when mixing. Composition dependences of isothermal compressibility, κT, and thermal isobaric expansivity coefficients, α, as well as thermal pressure coefficients, β, were near-linear. Both increasing and decreasing of κT and β values were observed with x2 increase depending on temperature ...

New correlations to predict natural gas viscosity and compressibility factor

This study proposed two new accurate simple explicit numerical methods for calculating the z-Factor and viscosity of natural gases. Results of these correlations are compared versus experimental data. Proposed correlation for z-Factor has 0.402 and 1.366 of Absolute Average Percent Error (AAE%) respectively versus Standing and Katz chart and experimental data. The output of this correlation can be directly assumed or be used as an initial value of other implicit correlations. In addition, this correlation is valid for gas coefficient of isothermal compressibility ( c g) calculations. The new method for viscosity accounts for the presence of heptane plus and non-hydrocarbon components. This model was derived from 1260 experimental measurement of gas viscosity of eleven different mixtures with AAE% of 2.083. This model is simpler and more efficient than published correlations, and the comparisons indicate superiority of the proposed model over other methods.

A novel correlation approach for prediction of natural gas compressibility factor

Gas compressibility factor (z-Factor) is one of the most important parameters in upstream and downstream calculations of petroleum industries. The importance of z-Factor cannot be overemphasized in oil and gas engineering calculations. The experimental measurements, Equations of State (EoS) and empirical correlations are the most common sources of z-Factor calculations. There are more than twenty correlations available with two variables for calculating the z-Factor from fitting in an EoS or just through fitting techniques. However, these correlations are too complex, which require initial value and more complicated and longer computations or have magnitude error. The purpose of this study is to develop a new accurate correlation to rapidly estimate z-Factor. Result of this correlation is compared with large scale of database and experimental data also. Proposed correlation has 1.660 of Absolute Percent Relative Error (E ABS) versus Standing and Katz chart and has also 3.221 of E ABS versus experimental data. The output of this correlation can be directly assumed or be used as an initial value of other implicit correlations. This correlation is valid for gas coefficient of isothermal compressibility (c g) calculations also.

Final Comments by the Authors

Ionic liquids (ILs) are an important new media and one of the most attractive solvents used in extraction and separation processes. This work presents some important physico-chemical properties and topics related to ILs, which were found by us as good extractive solvents for the desulfurization of fuels and for the separation of water/biobutan-1-ol. It consists of the most important series of experimental measurements of density and viscosity of pure ILs and in binary systems with thiophene and butan-1-ol: (N-hydroxyethylpyridinium tricyanomethanide, [C2OHPy][TCM] + thiophene), or (N-hydroxypropylpyridinium tricyanomethanide, [C3OHPy][TCM] + thiophene) or (N-benzyl-N-dodecyl-N,N-dimethylammonium bis(trifluoromethyl-sulfonyl)imide, [N1,1,12,Bz][NTf2] + butan-1-ol). These systems exhibit mainly negative molar excess volumes, VE in systems with thiophene and slightly positive and negative in the system with butan-1-ol. The Redlich – Kister equation was used for correlation of the liquid density, excess molar volumes and dynamic viscosity deviations as a function of temperature and composition, whereas Vogel-Fulcher-Tammann, VFT was used for describing the temperature dependence of dynamic viscosities. Very often, the high pressure is proposed for new technologies of separation and that is why we present the influence of pressure on the density of [C2OHPy][TCM], [C3OHPy][TCM] and [N1,1,12,Bz][NTf2] in a wide range of temperature from T = (298.15–348.15) K and pressure from p = (0.1–40) MPa. The Tait equation was used for the correlation of density as a function of mole fraction, temperature, and pressure. The influence of pressure for ILs, is as usual, not significant. The thermal expansion coefficient α and isothermal compressibility coefficient κ as a function of temperature T, and pressure p are presented. Herein, surface tension of new ILs was measured for the collection of physico-chemical properties of the ILs used in this work. Also, the octan-1-ol/water, Kow partition coefficients in ternary liquid-liquid phase equilibrium were determined for the systems {[C2OHPy][TCM], or [C3OHPy][TCM] (1) + octan-1-ol (2) + water (3)} at temperature T = 298.15 K and the discussion of the biocompatibility of the used ILs is presented.

Bi-velocity transport processes. Single-component liquid and gaseous continua

The present contribution supplements the previous findings regarding the need for two independent velocities rather than one when quantifying mass, momentum and energy transport phenomena in fluid continua. Explicitly, for the case of single-component fluids the present paper furnishes detailed expressions for the phenomenological coefficients appearing in the constitutive equations governing these bi-velocity transport processes. Whereas prior analyses furnished coefficient values only for the case of dilute monatomic gases using data from Burnett’s solution of the Boltzmann equation, the present study furnishes values applicable to all fluids, liquids as well as dense gases. Moreover, whereas prior coefficient calculations derived these values (for dilute monatomic gases) from Burnett’s solution of Boltzmann’s gas-kinetic equation, the latter a molecular theory, the present analysis derives the liquid- and gas-phase values from purely macroscopic data requiring knowledge only of the fluid’s coefficients of thermal expansion, isothermal compressibility, and thermometric diffusivity. In the dilute monatomic gas case common to both levels of analysis, the respective molecularly and macroscopically derived phenomenological coefficients are found to be in excellent agreement, confirming the credibility of both bi-velocity theory and the theory establishing the values of the phenomenological coefficients appearing in the constitutive relations derived therefrom. Whereas the preceding macroscopic calculations invoked Onsager’s reciprocal theorem relating coupled phenomenological coefficients, an alternative scheme is presented at the conclusion of the paper, one that reverses the usual order of things, at least in the present single-component fluid case. This alternate scheme enables Onsager’s nonequilibrium reciprocal relation, originally derived by him using molecular arguments, to be derived using purely macroscopic arguments originating from knowledge of Maxwell’s equilibrium reciprocal relations, the latter fundamental to equilibrium thermodynamics.

Acoustic and Thermophysical Properties of Binary Liquid Mixtures of Primary Butanols with Hexane and Cyclohexane at 293.15 K

The experimental density and speed of ultrasound measurements, along with literature data, were used to calculate adiabatic and isothermal compressibility coefficients, the specific heat ratio, and isobaric thermal expansion coefficients for the binaries of 1-butanol with hexane and cyclohexane. They were also used to determine Beyer’s parameter of nonlinearity, B/A, and free intermolecular lengths, L. The free intermolecular lengths, L, calculated according to the Jacobson equation, were compared with values estimated from thermoacoustical parameters.

Thermodynamic and transport properties of (1-Butanol + 1,4-Butanediol) at temperatures from (298.15 to 318.15) K

Densities and kinematic viscosities have been measured for (1-butanol + 1,4-butanediol) over the temperature range from (298.15 to 318.15) K. The speeds of sound within the temperature range from (293.15 to 318.15) K have been measured as well. Using these results and literature values of isobaric heat capacities, the molar volumes, isentropic and isothermal compressibility coefficients, molar isentropic and isothermal compressibilities, isochoric heat capacities as well as internal pressures were calculated. Also the corresponding excess and deviation values (excess molar volumes, excess isentropic and isothermal compressibility coefficients, excess molar isentropic and isothermal compressibilities, different defined deviation speed of sound and dynamic viscosity deviations) were calculated. The excess values are negative over the whole concentration and temperature range. The excess and deviation values are expressed by Redlich–Kister polynomials and discussed in terms of the variations of the structure of the system caused by the participation of the two different alcohol molecules in the dynamic intermolecular association process through hydrogen bonding at various temperatures. The predictive abilities of Grunberg–Nissan and McAllister equations for viscosities of mixtures have also been examined.

Effect of temperature and pressure on the thermal conductivity of sandstone

Effective thermal conductivity (ETC) of dry sandstone was measured over a temperature range from 275 to 523 K and at pressures up to 400 MPa with a guarded parallel-plate apparatus. The estimated uncertainty of the ETC measurements is 2%. The porosity of the sample was 13%. A rapid increase of ETC was found for dry sandstone at low pressures between 0.1 and 100 MPa along various isotherms. At high-pressure range ( P>100 MPa) a weak linear dependence of the ETC with pressure was observed. The pressure effect is negligibly small after first 80–100 MPa where bridging of microcracks or improvement of grain contacts takes place. We interpreted the measured ETC data using a various theoretical and semi-empirical models in order to check their accuracy and predictive capability. The effect of structure (size, shape, and distribution of the pores), porosity, and mineralogical composition on temperature and pressure dependences of the ETC of sandstone was discussed. To estimate the effect of temperature and pressure on the ETC of sandstone the pressure, β P , and temperature, β T , coefficients of ETC were calculated from the measured values of ETC. The measured values of the ETC were also used to calculate the values of the isothermal compressibility, χ T , and thermal expansion coefficient, α. The equation of state of sandstone was developed using the measured ETC data.

The effect of the size and packing of molecules on the thermodynamic properties of mixtures

The suggested approach explains the concentration dependence of density and of bulk-and-elastic properties of thermodynamically ideal mixture from the structural standpoint. It is demonstrated that the deviations of the concentration dependence of volumetric density and of the coefficient of isothermal compressibility from the mole-additive rule are caused by the difference between the structure parameters of pure liquids contained in the mixture (molecular volume, packing factors, and molecular densities). The contribution made by each one of the structure parameters to the deviation of the behavior of density of thermodynamically ideal mixture from the mole-additive rule is identified and estimated within suggested simulation for mixtures of different types.

Determination of the thermodynamic properties of liquid n-hexadecane from the measurements of the velocity of sound

The density, the isobaric expansion coefficient, the specific heats at constant pressure and constant volume, and the isothermal compressibility coefficient of liquid n-hexadecane have been calculated in the range of temperatures 298-433 K and pressures 0.1-140 MPa from the data on the velocity of sound. The coefficients of the Tate equation in the above parametric range have been determined. The table of the thermodynamic properties of n-hexadecane has been presented. Introduction. Normal hexadecane (C 16 ) has been the subject of numerous investigations of thermodynamic properties for years. A considerable volume of experimental data on the thermodynamic properties of n-hexadecane at atmospheric pressure is accumulated at present; also, the results of measurements of the density (1-10) and the veloc- ity of sound (11-15) in the high-pressure range are available. However, there are no experimental data on the density at pressures and temperatures higher than 3.5 MPa and 393 K. It is only in (11) that the velocity of sound has been measured at pressures higher than 70 MPa. In the only experimental investigation (8), the specific heat at constant pressure has been determined at elevated pressures up to 10 MPa and temperatures of 318 to 373 K. The other ther- modynamic properties at elevated pressure have virtually not been studied experimentally. At the same time, such properties as density, heat capacity, and compressibility can be determined by calculation from the experimental de- pendences of the density, specific heat at constant atmospheric pressure, and velocity of sound on temperature and pressure. The accuracy of calculation is comparable with the accuracy of direct measurements of the above quantities. The present work seeks to calculate the thermodynamic properties of liquid n-hexadecane at temperatures of 298 to 433 K and pressures up to 140 MPa. Initial Data. We have used, as the initial data on the velocity of sound, our measurements (4, 15) performed at temperatures of 298 to 433 K and pressures up to 100 MPa with an error of 0.1%, the results of experiments (11) at T = 293-473 K and p = 0.1-140.1 MPa having an accuracy of 0.1%, the data of (12) at T = 303-393 K and p = 0.1-70 MPa with an accuracy of 0.2%, and the results of (16-20) at atmospheric pressure, having an error of less than 0.1%. An analysis of the mentioned works has shown that their results are consistent with a deviation no higher than 0.1-0.2%.

The thermal properties of water-n,n-dimethylformamide solutions at 278–323.15 K and 0.1–100 MPa

The isothermal compressibility coefficients κ T , volumetric thermal expansion coefficients α, and pressure coefficients (∂p/∂T) v were calculated for water-N,N-dimethylformamide (DMFA) mixtures of 12 compositions over the temperature and pressure ranges 278–323.15 K and 0.1–100 MPa. The composition dependences of κ T passed minima, and the corresponding α and (∂p/∂T) v dependences passed maxima. The structural features of water and hydrophobic hydration effects were found to play a determining role in changes in the thermodynamic properties of water-DMFA solutions.

High Temperature and High Pressure Volumetric (Density and Apparent Molar Volumes) Properties of (CaCl2 + C2H5OH) Solutions

The (p, ρ, T) and some derived volumetric properties such as apparent molar volumes Vϕ of CaCl2 in ethanol, isothermal compressibility, and thermal expansion coefficients of (CaCl2 + C2H5OH) solutions at T = (298.15 to 398.15) K and pressures up to p = 40 MPa are reported. The density measurements were made at seven molalities of m = (0.09327, 0.17427, 0.43788, 0.68992, 0.98955, 1.26564, and 1.55045) mol·kg−1 of CaCl2. An empirical correlation for the density of (CaCl2 + C2H5OH) as a function of pressure, temperature, and molality has been developed. This equation of state was used to calculate other volumetric properties such as isothermal compressibility and thermal expansion coefficients. The derived values of apparent molar volumes were extrapolated to zero concentration to calculate the values of apparent molar volumes (or partial molar volumes) at infinite dilution.

Thermal Conductivity and Density of Plant Oils under High Pressure

The effect of pressure on the thermal conductivity and density of olive, safflower, linseed, and castor oils in the temperature range of (283 to 333) K and pressures up to 400 MPa was studied. The thermal conductivity measurements were carried out using a transient hot-wire method with an estimated uncertainty of 2.7 mW·m−1·K−1. The density of olive oil was determined within an uncertainty of 0.3 % by a Jamin interferometer. Results reveal an increase in the thermal conductivity and density with pressure. The pressure dependency of the thermal conductivity of these plant oils correlates with the coefficient of isothermal compressibility. The temperature dependency of the thermal conductivity is linked to the isobaric thermal expansion coefficient. This agrees well with the vibrational theory of thermal conductivity due to Horrocks and McLaughlin. From this model, the relation between thermal conductivity and density λ/λ0 = (ρ/ρ0)g can be obtained. The application of our data to this relation leads to g ≈ 3, which is typical for organic liquids.

Effect of Cholesterol and Ergosterol on the Compressibility and Volume Fluctuations of Phospholipid-Sterol Bilayers in the Critical Point Region: A Molecular Acoustic and Calorimetric Study

Although sterol-phospholipid interactions have been of interest for many years now, a complete thermodynamic profile of these systems is still missing. To contribute to a better understanding of the thermodynamic functions of these systems, we determined isothermal compressibility coefficient data for dipalmitoylphosphocholine (DPPC) and DPPC-containing cholesterol and ergosterol vesicles by means of molecular acoustics (ultrasound velocimetry and densimetry) and differential scanning and pressure perturbation calorimetric techniques. A particular focus was on the influence of the differential structural properties of the two sterols on the thermodynamic properties of lipid bilayers, and on the nature of the critical point region of phospholipid-sterol systems by determining thermodynamic fluctuation parameters. Contrary to significant changes in conformational and dynamical properties of the DPPC-sterol membranes, no marked differences were found in the various thermodynamic properties studied, including the adiabatic ( β S lipid ) and isothermal ( β T lipid ) compressibility, as well as the volume fluctuations. Differences in β T lipid and β S lipid become dramatic in the gel-fluid transition region only, due to a significant degree of slow relaxational processes in the microsecond time range in the transition region. Our data show no evidence for the existence of a typical critical point phenomenon in the concentration and temperature range where a critical point in the DPPC-sterol phase diagram is expected to appear. Hence, on a macroscopic level, it seems more appropriate to describe the sterol-phospholipid binary mixtures in the liquid-ordered/liquid-disordered coexistence region as a phase region consisting essentially of small nanodomains only. Such small-domain dimensions, with a series of particular properties such as increased line energy, spontaneous curvature, and limited lifetime, seem also to be typical of raftlike domains in cell membranes.

Prediction of volumetric and thermodynamic properties of two aromatic–alcohol mixtures using GMA equation of state

In this work, we have calculated the densities of two mixtures composed of 1-propanol + toluene and ethanol + toluene at different temperatures, pressures, and compositions using GMA equation of state (EoS). We have also calculated some thermodynamic properties of these mixtures such as isobaric thermal expansion coefficient, isothermal compressibility coefficient, internal pressure, and excess functions such as the excess volumes, excess Gibbs free energy, excess enthalpy, excess entropy, excess internal energy, and excess Helmholtz free energy. A wide comparison with the experimental data shows the ability of this equation of state to reproduce and predict different thermodynamic properties. The composition dependence of the parameters of this equation of state has been assumed as quadratic functions of mole fraction. Using these quadratic mixing rules, the excellent agreement has been obtained between the calculated values and experimental data. To assess the validity of GMA EoS, the density of studied mixtures has been calculated based on this equation of state and Tait equation and compared using statistical parameters. The lower values of statistical parameters obtained by GMA EoS for these mixtures confirm the ability of this EoS to reproduce and predict the density of mixtures.

Pressure−Density−Temperature (p−ρ−T) Surface of [C6mim][NTf2

In the framework of the IUPAC Project entitled “Thermodynamics of ionic liquids, ionic liquid mixtures, and the development of standardized systems”, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C6mim][NTf2], was selected as the standard ionic liquid on which to perform round-robin measurements on a series of selected properties. In this work, the pressure, density, temperature (p, ρ, T) surface was determined in the temperature range (293 to 338) K and up to a nominal pressure of 65 MPa. The isothermal compressibility and isobaric expansion coefficients were calculated from the (p, ρ, T) data.