The determination of the second and third virial coefficients frompVT-X data of binary systems

The compressibility factor of multicomponent systems can be obtained in terms of virial coefficients of the pure components and their binary mixtures. This paper concerns a method with which, for that purpose, the second and third virial coefficients for these binaries have been determined from experimental data. From useful data, second and third virial coefficients are obtained as a quadratic function of the temperature. The density domain for which these results are applicable is discussed. When ample data are available, results for a sample mixture can be obtained in a straightforward manner. Nevertheless, it is shown that under much less favorable conditions—sometimes even when pure-component data are lacking—fairly good results can still be obtained. In that case, the choice for an appropriate combining rule has to be considered carefully. Finally, the involvement of ternary mixture data, both obtained experimentally and predicted by the equation, is considered.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

The lean flammability limits in air of methane,hydrogen and carbon monoxide at low temperatures

The lean flammability limits in air for methane, hydrogen and carbon monoxide at atmospheric pressure were established under isothermal initial conditions at temperatures extending down to ?130°C. Simple guidelines are then suggested for predicting these limits on the basis of the calculated flame temperature of the limiting mixtures. Estimates were also made of the extent of changes in these limits due to heat transfer over a wide mixture temperature range.     

Determination of the interaction second virial coefficients for the carbon dioxide-ethane system from refractive index measurements

The compressibility behavior of the CO₂-C₂H₆ system was investigated experimentally. In this work, the refractive indexes of the pure gases and the mixtures were measured using an optical apparatus. On the basis of these data, density and compressibility factors were computed using the Lorentz-Lorenz law. For the pure components, carbon dioxide and ethane, the data from the optical system were slightly adjusted by a fit to Burnett apparatus data measured separately. The experiments produced very accurate virial coefficients and refraction virial coefficients. This paper reports on the effect of temperature on the second and third virial coefficients. For the first refraction virial coefficient, no influence of temperature was found with the equipment used. The interaction second virial coefficient B ₁₂ (as a function of temperature) was computed from experimental data for the CO₂-C₂H₆ binary system. The data, for which an accuracy of ±1.5 cm³ · mol^–1 was estimated, are in agreement with the data published by Holste et al.     

p,V, T and derived thermodynamic data for bromobenzene at temperatures from 278 to 323 K and pressures up to 280 MPa

Experimentally determined p, V, T data are reported for bromobenzene at 278, 288, 298, 313, and 323 K, at pressures up to about 280 MPa or (at 278 and 288 K) a lower pressure slightly below the freezing pressure at the temperature of measurement. Values of the isobaric expansivity, isothermal compressibility, internal pressure, and equivalent hard-sphere diameter, derived from the p, V, T data, are presented.On leave from the Department of Chemistry, The University of Auckland, Auckland, New Zealand.     

Freezing pressures,p, V,T, and self-diffusion data at 298 and 313 K and pressures up to 300 MPa for 1,3,5-trimethylbenzene

Mesurements are reported for the melting point of 1,3,5-trimethylbenzene at pressures up to 345 MPa. Self-diffusion coefficients and p, V, T data have been obtained at 298 and 313 K for pressures up to 280 MPa. Isothermal compressibilities have been calculated from the p, V, T results. The freezing pressures at 0.1 MPa correspond to previously reported values for modification III of trimethylbenzene. Equivalent hard-sphere diameters estimated from the melting point and p, V, T data are used to apply the rough hard-spheres theory to the self-diffusion data; the calculations indicate that there is random packing of the particles.On leave from Department of Chemistry, University of Auckland, Auckland, New Zealand.     

Emerging Delivery Strategies of Carbon Monoxide for Therapeutic Applications: from CO Gas to CO Releasing Nanomaterials

Carbon monoxide (CO) therapy has emerged as a hot topic under exploration in the field of gas therapy as it shows the promise of treating various diseases. Due to the gaseous property and the high affinity for human hemoglobin, the main challenges of administrating medicinal CO are the lack of target selectivity as well as the toxic profile at relatively high concentrations. Although abundant CO releasing molecules (CORMs) with the capacity to deliver CO in biological systems have been developed, several disadvantages related to CORMs, including random diffusion, poor solubility, potential toxicity, and lack of on‐demand CO release in deep tissue, still confine their practical use. Recently, the advent of versatile nanomedicine has provided a promising chance for improving the properties of naked CORMs and simultaneously realizing the therapeutic applications of CO. This review presents a brief summarization of the emerging delivery strategies of CO based on nanomaterials for therapeutic application. First, an introduction covering the therapeutic roles of CO and several frequently used CORMs is provided. Then, recent advancements in the synthesis and application of versatile CO releasing nanomaterials are elaborated. Finally, the current challenges and future directions of these important delivery strategies are proposed.     

Mean polarizabilities and second optical and density virial coefficients of CH3OH and CCl2F2 between 300 and 355 K

Mean dipole polarizabilities ₀(, T) as well as second optical (or refractive index) virial coefficients b _R(, T) and second density virial coefficients B(T) of gaseous CH₃OH and CCl₂F₂ have been determined by precise measurements of the refractive index n(, T, p) [543 nm 633 nm, 300 K T 355 K, p<0.25 bar (CH₃OH) and p<3 bar (CCl₂F₂)]. ₀ critically compared with the few data in literature. The b _R of these gases was measured for the first time with the cyclic-expansion method. The values of ¦B¦ and b _R=3160(25) cm³ · mol^–1 measured for CH₃OH are considerably greater than the values calculated by Buckingham's statistical-mechanical expressions for a Stockmayer interaction potential. This difference is discussed by assuming dimerization via H bonds, with result H ₂ ⁰ –(28 ... 33) kJ · mol^–1 and S ₂ ⁰ –(116 133) J · mol^–1 · K^–1 for the dimerization enthalpy and entropy for standard conditions, respectively. On the other hand, Buckingham's formulae can be used with success to estimate b _R and B of CCl₂F₂.Dedicated to Prof. Dr. F. Kohler on the occasion of his 65th birthday     

Precise determination of the compressibility factor of methane,nitrogen, and their mixtures from refractive index measurements

We show that the absolute determination of the refractive index, when combined with an expansion technique for obtaining the higher-order coefficients of the Lorentz-Lorenz expansion, leads to precise values of density. A grating interferometer has been developed for the refractive index measurements as a function of pressure. The advantage of a grating interferometer is that it performs a reversible counting and generates a DC compensated signal from the interference fringes. The pressure is also measured with an interferometer, previously calibrated with an oil-type precision piston gauge. For the precise determination of the compressibility factor, the absolute measurement of the refractive index is combined with the differential technique to determine the refractivity virial coefficients of the Lorentz-Lorenz expansion. The compressibility factors of methane, nitrogen, and their mixtures have been determined at 323.15 K for pressures up to 335 bar. The optical method for the determination of the compressibility factor not only is shown to be precise, but also has the ability to produce numerous experimental points in a short time as compared to other methods.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Microbiological,colour and sensory properties of fresh beef steaks in low carbon monoxide concentration

Steaks from gluteus medius m. (GM) and longissimus dorsi m. (LD) were packaged in atmospheres containing two low levels of CO (0.2 and 0.4%) in combination with 21% O₂ or without oxygen. The other components of the modified atmosphere packaging systems were carbon dioxide (30%) and nitrogen (balance). Steaks were evaluated on 0, 7, 14 and 21 days of storage at about 2^oC to investigate the effects of the gas mixtures on the microflora, instrumental (CIE L*a*b*) and visual colour and odour. The preservation of colour and odour of GM and LD steaks packaged under low carbon monoxide was best achieved using anoxic mixtures containing 0.2% CO and 30% CO₂. Steaks packaged without oxygen retained a desirable colour and practically did not present a visible discoloration or perceptive off‐odour along the entire storage time. Colour stabilization with 0.2% CO and 30% CO₂, without O₂, following storage up to 21 days at 2°C did not increase microbial risk of products. The increase in CO from 0.2 to 0.4% had a negative effect on the colour of LD steaks which was regarded as ‘artificial’ by some panellists. The higher stability achieved in this study using 0.2% CO may result from increased stability of the colour from Bos indicus × Bos Taurus cross. Discoloration and off‐odour were evident in the GM and LD steaks packaged aerobically after 14 days of storage when the counts of deteriorant bacteria achieved approximately 6.5 to 9.7 log CFU/g. Highest bacteriostatic effect could be obtained if the volume of injected CO₂ was sufficient to saturate the meat and keep in balance around the product during storage. Copyright © 2010 John Wiley & Sons, Ltd.     

Prediction of the temperature dependence of binary diffusion coefficients of gaseous systems from thermal diffusion factors and diffusion coefficients at 300 K

Data are presented which enable binary diffusion coefficients and their concentration dependences to be predicted from diffusion coefficients and thermal diffusion factors at 300 K. The results up to 2000 K are compared with corresponding values derived from the complication of Mason and Marrero. Paper dedicated to Professor Edward A. Mason.     

0.2 K～300 K温区氦-3的p-h和T-s图

基于最新的德拜模型氦-3状态方程、氦-3饱和曲线特征方程和熔化曲线特征方程编写了氦-3热物性计算程序.在大量热物性的计算数据的基础上绘制了氦-3在0.2 K～300 K,0.000 1MPa～30 MPa范围内的p-h图和T-s图.与先前基于实验数据绘制的0.2 K～20 K温区氦-3的p-h图和T-s图相比,该图的绘制是建立在热力学理论计算的基础之上,适用温区得到了拓展,随机误差一般在2%以内.     

Experimental Measurements of the Speed of Sound in n-Hexane from 293 to 373 K and up to 150 MPa

Speed-of-sound measurements were performed at pressures up to 150 MPa in the temperature range from 293 to 373 K on n-hexane in the liquid state. Theses data were then used to evaluate the isentropic and isothermal compressibility in the same range of pressures and temperatures. The speed-of-sound measurements, as well as the related compressibility coefficients, compare very well with the values calculated from the correlation of Randzio et al. Volumetric properties also compare very well with the direct measurements reported in the standard reference data tables.     

PVT and derived thermodynamic properties for the glycine-water system at temperatures from 298 to 323 K and pressures up to 300 MPa

The specific volumes for the glycine-water system have been measured in the temperature range 298–323 K and at pressures up to 300 MPa, using a glass piezometer. The uncertainties in the specific volume are estimated to be less than 0.03%. The PVT relations are correlated by the Tait equation. Good agreement was found with correlations by the Tait equation using a simple extension similar to that proposed by Dymond and Malhotra. The isothermal compressibility and apparent molar volume of glycine are calculated by the Tait equation. The apparent molar volume of glycine increases with increasing pressure.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Densities of liquid R 114 at temperatures from 310 to 400 K and pressures up to 10 MPa

Density measurements for liquid R 114 (dichlorotetrafluoroethane) have been obtained with a variable-volume method. The results cover the high-density region from 1007 to 1462 kg·m^–3 along ten isotherms between 310 and 400 K at 16 pressures from 0.5 to 10.0 MPa. The experimental uncertainty in the density measurements was estimated to be no greater than 0.2%. Based on the present results the derivatives with respect to temperature and pressure were calculated, and numerical values of the volume expansion coefficient and of the isothermal compressibility are tabulated as a function of temperature and pressure.     

The Ratio D<Subscript><Emphasis Type="Italic">int</Emphasis></Subscript> /D between the Coefficients for the Diffusion of Internal Energy and of Self Diffusion in Thermal Conductivity Data Correlations for Gases of Linear Molecules

Highly consistent sets of generalized cross sections are used to judge critically correlations of the thermal conductivity in the limit of zero density for nitrogen, carbon monoxide, and carbon dioxide. The correlations were developed by Millat, Vesovic, and Wakeham some years ago using restricted experimental information in order to deduce a set of generalized cross sections as consistent as possible for the extrapolation beyond the temperature range of the primary experimental data. Recently, the generalized cross sections needed have been evaluated by means of classical trajectory calculations for rigid rotors on the basis of accurate anisotropic ab initio potential energy hypersurfaces including a new improved way to take into account the vibrational degrees of freedom. It is shown that the ratio between the coefficients of internal energy and of self diffusion D_int /D was not appropriately chosen and that this effect was extensively compensated in a fortuitous way in the course of the development of the data correlations by a likewise unsuitable choice of the ratio A* between the effective cross sections of viscosity and self-diffusion.Paper presented at the Sixteenth European Conference on Thermophysical Properties, September 1–4, 2002, London, United Kingdom.     

Measurements of the compressibility and sound velocity in methane up to 1 GPa,revisited

New density measurements of methane (CH₄) at 298.15 K up to 1 GPa are reported. The precision of the measurements is 0.03%, while the estimated accuracy is between 0.05 and 0.1%. Velocities of sound have been remeasured between 148.15 and 298.15 K at intervals of 25 K and at pressures up to 1 GPa, with an estimated accuracy of 0.12% at 100 M Pa, 0.10% at 150 MPa, and 0.08% above 150 MPa. Comparisons with experimental results and equations of state of other workers are presented. The isothermal and the adiabatic compressibility and the ratio of specific heats have been calculated at 298.15 K.     

Thermodynamic properties and excess volumes of 2,2,4-trimethylpentane + n-heptane mixtures from 298 to 338 K for pressures up to 400 MPa

(p, V, T) data for mixtures of 2,2,4-trimethylpentane (TMP) and heptane have been obtained in the form of volume ratios for four temperatures in the range 298.15 to 338.15 K for pressures up to 390 MPa. The data have been represented by the Tait equation of state for the purposes of interpolation and extrapolation. The atmospheric pressure densities of both pure components and their mixtures for three temperatures have been measured and used to determine the excess molar volumes. Isothermal compressibilities have been evaluated from the volumetric data.     

Acoustic quality factor of copper, brass and beryllium copper from 50 mK to 300 K

The amplitude-independent background mechanical quality factors (reciprocal internal frictions) of oxygen-free electronic (OFE) copper (C 10100), free-turning brass (C36000) and beryllium copper (C17200) were measured in the temperature range 50 mk – 300 K. The data were obtained from measurements on 1 kHz torsional modes of mechanical resonators configurated to minimize extraneous internal friction effects. The resonant frequency dependence on temperatures was also obtained, giving the temperature dependence of the dynamic shear modulus. Strongly enhanced quality factors were obtained from appropriate heat treatment.     

Optical and Electrochemical Properties of Single-walled Carbon Nanotube Arrays Attached to Silicon (100) Surfaces

Arrays of aligned single-walled carbon nanotubes (SWCNTs) have been attached to a Si (100) surface using two approaches. The first method uses a self-assembled ethyl undecanoate monolayer (SWCNTs-SAM structure), while the second sees the nanotubes attached directly to an ultrathin SiO₂ layer (SWCNTs-SiO₂ structure). The optical and electrochemical properties of two nanotube arrays were compared by fluorescence spectroscopy and cyclic voltammetry. The results show that the SWCNTs-SiO₂ structure has strong coupling between the attached SWCNTs and the silicon substrate, but the coupling gets smaller with increasing size of attached SWCNT bundles. The SWCNTs-SAM structure shows poor conductivity and electrochemical reversibility. The SWCNTs-SiO₂ structure does appear to be a very useful substrate for use in further applications.