1-(Bromoacetyl)pyrene,a novel photoinitiator for the copolymerization of styrene and acrylonitrile

A comparative study on photoinitiated solution copolymerization of Styrene (Sty), with acrylonitrile (AN) using pyrene, 1-acetylpyrene, and 1-(bromoacetyl)pyrene (BrPy) as initiators, showed that the introduction of a chromophoric moiety, bromoacetyl (–COCH₂Br), significantly increased the photoinitiating ability of pyrene. The kinetics and mechanism of copolymerization of Sty with AN (Sty–co–AN) using BrPy as photoinitiator has been studied in detail. The kinetic data, inhibiting effect of benzoquinone, and electron spin resonance (ESR) studies suggest that the polymerization proceeds via a free radical mechanism. The system followed non-ideal kinetics (R _p α[BrPy]^0.7[Sty]^1.09[AN]^1.01) and degradative solvent transfer reasonably explained these kinetic non-idealities. The co-monomer reactivity ratios calculated by using the Finemann–Ross and Kelen–Tudos models were r ₁ (Sty) = 0.39 and r ₂ (AN) = 0.05. The reactivity ratios strongly indicate that the two monomers enter in almost alternating arrangement along the copolymer chain.     

Analysis of urinary estrogens,their oxidized metabolites,and other endogenous steroids by benchtop orbitrap LCMS versus traditional quadrupole GCMS

Estrogens and other endogenous steroids are known risk markers for cancer. Gas chromatography (GC) with mass spectrometry (MS) has traditionally predominated the analysis of estrogens and other endogenous steroids, but liquid chromatography (LC) MS is increasingly favored. Direct comparisons of the two technologies have hitherto not been performed. Steroids were analyzed from 232 urine samples of 78 premenopausal women in a blinded fashion by benchtop orbitrap LCMS and single quadrupole GCMS. Sixteen steroidal estrogens including oxidized metabolites could be analyzed by LCMS. LCMS–GCMS Spearman rank correlations of the major estrogens E₁, E₂, E₃, 16α-OHE₁, and 2-OHE₁ were very high (r = 0.72–0.91), and absolute concentrations also agreed (<5% difference for E₁, E₂, E₃, 16α-OHE₁). LCMS allowed reinterrogation of the acquired data due to orbitrap technology, which permitted post-analysis quantitation of progesterone, cortisol, and cortisone (LCMS–GCMS Spearman rank correlations = 0.80–0.84; absolute difference, <7%; n = 137). GCMS allows the measurement of a wide range of steroids including non-polar analytes that escape the presented LCMS assay. In contrast, orbitrap-based LCMS can detect more estrogens, is faster, less costly, allows post-data acquisition reinterrogation of certain analytes that had not been targeted a priori, and requires much less urine.     

Modeling of a voltammetric experiment in a limiting diffusion space

A voltammetric experiment confined in a limiting diffusion space is analyzed theoretically governed by conventional or time-anomalous factional diffusion under conditions of cyclic and square-wave voltammetry. The solution for conventional diffusion is derived by means of the Jacobi theta function Q( a²/p²t )( a = LD ^{- 1/2} \Theta \left( {{a^2}/{\pi^2}t} \right)\left( {a = L{D^{ - 1/2}}} \right. , where L is the thickness of the finite diffusion space, D is the diffusion coefficient, and t is the time of the experiment) and compared with the solution frequently used in the literature expressed in the form Θ(a ⁻² t). For L → ∞, the present solution converges to the one for the semi-infinite diffusion, thus being of a general applicability for both finite and semi-infinite diffusion. Hence, the mathematical model for simulation of both cyclic and square-wave voltammetric experiment provides significant advances in terms of simulation time and accuracy compared to the previous model based on the modified step-function method Mirčeski (J Phys Chem B 108:13719, 2004). For the fractional diffusion experiment, the solution is derived by combining an infinite series and the Wright function f( - a/2,a/2; - 2ax ^{- 1/2}t ^{- a/2} ) \phi \left( { - \alpha /2,\alpha /2; - 2a{\xi^{ - 1/2}}{t^{ - \alpha /2}}} \right) , where α is the time fractional parameter ranging over the interval 0 < a < 1 0 < \alpha < {1} , and ξ = 1 s^1−α is the auxiliary constant. The voltammetric properties of the experiment controlled by fractional diffusion are comparable for both finite and semi-infinite diffusion.     

Dissolution behaviour of model alkali-soluble emulsion polymers: effects of molecular weights and ionic strength

The dissolution behaviour of model alkali-soluble polymer emulsions with different molecular weights was studied using conductometric and potentiometric titration and laser light scattering techniques. The behaviour of the copolymer was studied as a function of the degree of neutralisation, α = [NaOH]/[COOH]. The polymer latex swells with increasing α values up to α = 0.5–0.7, after which the dissociation of polymer chains commences. At α = 1.0, all the polymer latexes dissociate into individual polymer chains. By combining the results of static and dynamic laser light scattering, we observed that the polymers have a compact conformation at α = 0. This compact conformation changes to a random coil at around α = 0.5, which then becomes a fully extended coiled conformation at α = 1.0, when all the COOH polymer groups are hydrolysed. The dissolution of low-molecular-weight polymers is faster than that of high-molecular-weight polymers. Received: 15 February 1999 Accepted in revised form: 13 July 1999     

Oxygen excess nonstoichiometry and thermodynamic quantities of La2NiO4?+?δ

The oxygen excess nonstoichiometry of La₂NiO_4 + δ is measured as a function of temperature and oxygen partial pressure (pO₂) by coulometric titration method. A positive deviation from the ideal dilution solution behavior is exhibited, and the partial molar thermodynamic quantities of La₂NiO_4 + δ are calculated from the Gibbs–Helmholtz equation for regular solution by introducing the activity coefficient of the charge carriers. The activity coefficient of holes is successfully calculated by using the Joyce–Dixon approximation of the Fermi–Dirac integral. The effective mass of holes ( m_\texth^* m_{\text{h}}^{{*}} ) is 1.27–1.29 times the rest mass (m _h), which indicate the action of band-like conduction and allow the effect of the small degree of polaron hopping to be ignored. The activity coefficient of holes calculated against the oxygen nonstoichiometry clearly illustrates the early positive deviation of the activity coefficient of holes from unit, leading to g_{\texth ^·} \gamma_{{{\text{h}}^{ \bullet }}}  ≈ 14 at δ ≈ 0.08, which is quite close to the literature value of g_{\texth ^·} \gamma_{{{\text{h}}^{ \bullet }}}  ≈ 10 at δ ≈ 0.08. All the evaluated thermodynamic quantities are in good agreement with the experimental literature values.     

Structural and calorimetric investigations on nonaqueous liquid crystals and gel phases in the binary system K-stearate/glycerol

The K-stearate/glycerol (KC₁₈/Gl) binary system was studied at mole fractions of stearate of x _KC18 = 0.10, 0.25, 0.30 and 0.50. Small- and wide-angle X-ray diffraction (XRD) measurements were combined with differential scanning calorimetry (DSC) measurements at different temperatures. The investigations were intended to verify the previously published phase diagram and were targeted at the confirmation of the gel-like (G₁) phase and the isotropic (I) phase. The XRD and DSC measurements lead to the conclusion that the G₁ phase as well as the I phase, the existence of which had been proposed from texture observations, do in fact not exist. Consequently, a correction of the preliminary phase diagram is given. This corrected phase diagram reveals the crystalline phase (C) ⇆ gel phase (G) ⇆ hexagonal phase (H_α) ⇆ isotropic, micellar phase phase transitions for low KC₁₈ concentrations of x _KC18 = 0.15–0.3 and the C ⇆ G ⇆ lamellar phase (L_α) phase transitions for concentrations about or higher than x _KC18 = 0.35. The C, G, L_α and H_α phases have been further characterized by structural parameters (characteristic d values) as a function of temperature. The phase transitions C ⇆ G, G ⇆ L_α and G ⇆ H_α correlate with sharp shifts in the d value of the first small-angle reflections. Received: 20 April 1999 Accepted: 28 July 1999     

Giant colloidal crystals of fluorine-containing polymer spheres in exhaustively deionized aqueous suspensions and in the presence of sodium chloride

 Gigantic colloidal single crystals (2–6 mm) are formed for fluorine-containing polymer spheres (120–210 nm in diameter) in exhaustively deionized aqueous suspensions. The spheres used are poly(tetrafluoroethylene) (PTFEA and PTFEB), copolymer of tetrafluoroethylene and perfluorovinylether (PFA) and copolymer of tetrafluoroethylene and perfluoropropylene (PTP). The phase diagrams of these spheres are obtained in the deionized suspensions and also in the presence of sodium chloride for PFA. The critical sphere concentrations of crystal melting (φ _c) for these spheres are around 0.0006 in volume fraction, which are close to, but slightly larger than, those of monodispersed polystyrene spheres (φ _c ≈ 0.00015) and colloidal silica spheres(φ _c = 0.0002–0.0004) reported previously. The crystals are largest when the sphere concentrations are a bit higher than the φ _c value and their size decreases as the sphere concentration increases. Reflection spectra are taken in sedimentation equilibrium as a function of the height from the bottom of the suspension. The static elastic modulus is estimated to be 10.8 and 28.7 Pa for PTFEA and PTP spheres at the sphere concentrations 0.00325 and 0.00322 in volume fraction, respectively. Received: 27 October 1999 Accepted in revised form: 16 November 1999     

Low-rate dynamic contact angles on poly(n-butyl methacrylate) and the determination of solid surface tensions

 Low-rate dynamic contact angles of 22 liquids on a poly(n-butyl methacrylate) (PnBMA) polymer are measured by an automated axisymmetric drop shape analysis-profile (ADSA-P). It is found that 16 liquids yielded non-constant contact angles, and/or dissolved the polymer on contact. From the experimental contact angles of the remaining 6 liquids, it is found that the liquid–vapor surface tension times cosine of the contact angle changes smoothly with the liquid–vapor surface tension, i.e. γ_lv cos θ depends only on γ_lv for a given solid surface (or solid surface tension). This contact angle pattern is in harmony with those from other inert and non-inert (polar and non-polar) surfaces [34–37, 45–47]. The solid–vapor surface tension calculated from the equation-of-state approach for solid-liquid interfacial tensions [14] is found to be 28.8 mJ/m², with a 95% confidence limit of ±0.5 mJ/m², from the experimental contact angles of the 6 liquids. Received: 12 September 1997 Accepted: 22 January 1998     

Chemiluminescent imaging analysis of interferon alpha in serum samples

Enzyme-linked immunosorbent assay (ELISA), horseradish peroxidase (HRP)-catalyzed fluorescent reaction, and oxalate chemiluminescence imaging analysis have been combined to develop a sensitive, simple, and rapid method for analysis of interferon alpha (α-IFN) in human serum samples. A typical “sandwich type” immunoassay was used. Reaction of o-phenylenediamine (OPD) with hydrogen peroxide (H₂O₂), catalyzed by HRP, produced 2,3-diaminophenazine (PDA), which was detected by chemiluminescence imaging analysis with the bis(2,4,6-trichlorophenyl)oxalate (TCPO)–H₂O₂–glyoxaline–PDA chemiluminescent system. The TCPO chemiluminescent imaging system is more sensitive and the chemiluminescence quantum yield is at least five times higher than for the luminol–H₂O₂–HRP–PIP (p-iodophenol) chemiluminescent imaging system. The results showed there was a very good linear correlation between response and amount of α-IFN in the range 1.3–156.0 pg mL⁻¹ (R = 0.9991) and the detection limit was 0.8 pg mL⁻¹ (S/N=3). The relative standard deviation (n = 9) was 4.7%. The proposed method has been used for successful analysis of the amount of α-IFN in human serum. The results obtained compared well with those obtained by conventional colorimetric ELISA and luminol chemiluminescent ELISA. Figure Procedures of the proposed method     

Al,B, and F doped LiNi<Subscript>1/3</Subscript>Co<Subscript>1/3</Subscript>Mn<Subscript>1/3</Subscript>O<Subscript>2</Subscript> as cathode material of lithium-ion batteries

A series of the mixed transition metal compounds, Li[(Ni_1/3Co_1/3Mn_1/3)_1–x-y Al _x B _y ]O_2-z F _z (x = 0, 0.02, y = 0, 0.02, z = 0, 0.02), were synthesized via coprecipitation followed by a high-temperature heat-treatment. XRD patterns revealed that this material has a typical α-NaFeO₂ type layered structure with R3^- m space group. Rietveld refinement explained that cation mixing within the Li(Ni_1/3Co_1/3Mn_1/3)O₂ could be absolutely diminished by Al-doping. Al, B and F doped compounds showed both improved physical and electrochemical properties, high tap-density, and delivered a reversible capacity of 190 mAh/g with excellent capacity retention even when the electrodes were cycled between 3.0 and 4.7 V.     

Synthesis and Reactivity of Stannyloligosilanes IV [1]: From Hydrido Substituted Stannasilanes Towards Stannasiloxanes

Summary.  Hydrido substituted stannasilanes of the type or (Z = H, Me, Ph; R, R′ = alkyl, Ph) are accessible by reaction of either alkali metal stannides (MSn(Z)R ₂; M = Li, Na) with halogen substituted silanes (; X = F, Cl) or chlorostannanes (R ₂SnCl₂, Ph₃SnCl) and fluorosilanes in the presence of magnesium. Stannasilanes with halogen substituents at the silicon as well as the tin atom are formed by treatment of the hydrido substituted stannasilanes with CHCl₃ or CCl₄. The hydrido substituted stannasilanes decompose in contact with air to distannanes and siloxanes or to the linear ( ^t Bu₂Sn(–O– ^t Bu₂Si–OH)₂) and cyclic ((– ^t Bu₂Sn–O– ⁱ Pr₂Si–O–)₂) stannasiloxanes. Received November 29, 2001. Accepted (revised) January 16, 2002     

Studies on Equation-of-State Parameters and Linear Polymer Dimensions of Poly(p-chlorostyrene) in Diethylene Glycol Monobutyl Ether by Intrinsic Viscosity Measurements

Intrinsic viscosities, [η], of poly(p-chlorostyrene) (PPCS) in diethylene glycol monobutyl ether (DGMBE) which exhibits an exothermic solubility behavior with the polymer were measured using an Ubbelohde type capillary viscometer between 25 and 85°C. Polymer solvent interaction parameters at infinite dilution (χ₁), exchange energy parameter ([`(X)]₁₂)(\bar{X}_{12}) , exchange enthalpy (X₁₂), and entropy parameters (Q₁₂), of the PPCS/DGMBE pair were found at studied temperature range according to equation-of-state theory. In the blob theory, dependence of [η] on temperature can be scaled by a master curve in a plot of α_η³|τ|M^1/2 versus |τ|M^1/2 as the polymer coil contracts below the Θ-point, however, it can be scaled by a master curve in a plot of α_η⁻⁵|τ|M^1/2 versus |τ|M^1/2 as the polymer coil expands above the Θ-point in an endothermic solubility behavior. Since the studied PPCS/DGMBE system represents exothermic solubility behavior, the master curves of the system were plotted in α_η³|τ|M^1/2 versus |τ|M^1/2 as the polymer coil contracts above the Θ-point and in α_η⁻⁵|τ|M^1/2 versus |τ|M^1/2 as the polymer coil expands below the Θ-point. The universal plots of α_η(N/N_c)^1/6 versus N/N_c and α_η(N/N_c)^−1/10 versus N/N_c were plotted above and below Θ-point, respectively.     

Study of a new derivatizing reagent that improves the analysis of amino acids by HPLC with fluorescence detection: application to hydrolyzed rape bee pollen

A simple and sensitive method for evaluating the chemical compositions of protein amino acids, including cystine (Cys)₂ and tryptophane (Try) has been developed, based on the use of a sensitive labeling reagent 2-(11H-benzo[α]-carbazol-11-yl) ethyl chloroformate (BCEC–Cl) along with fluorescence detection. The chromophore of the 1,2-benzo-3,4-dihydrocarbazole-ethyl chloroformate (BCEOC-Cl) molecule was replaced with the 2-(11H-benzo[α]-carbazol-11-yl) ethyl functional group, yielding the sensitive fluorescence molecule BCEC–Cl. The new reagent BCEC–Cl could then be substituted for labeling reagents commonly used in amino acid derivatization. The BCEC–amino acid derivatives exhibited very high detection sensitivities, particularly in the cases of (Cys)₂ and Try, which cannot be determined using traditional labeling reagents such as 9-fluorenyl methylchloroformate (FMOC-Cl) and ortho-phthaldialdehyde (OPA). The fluorescence detection intensities for the BCEC derivatives were compared to those obtained when using FMOC-Cl and BCEOC-Cl as labeling reagents. The ratios I _BCEC/I _BCEOC = 1.17–3.57, I _BCEC/I _FMOC = 1.13–8.21, and UV_BCEC/UV_BCEOC = 1.67–4.90 (where I is the fluorescence intensity and UV is the ultraviolet absorbance). Derivative separation was optimized on a Hypersil BDS C₁₈ column. The detection limits calculated from 1.0 pmol injections, at a signal-to-noise ratio of 3, ranged from 7.2 fmol for Try to 8.4 fmol for (Cys)₂. Excellent linear responses were observed, with coefficients of >0.9994. When coupled with high-performance liquid chromatography, the method established here allowed the development of a highly sensitive and specific method for the quantitative analysis of trace levels of amino acids including (Cys)₂ and Try from bee-collected pollen (bee pollen) samples.     

Cathodoluminescence Depth Profiling in SiO2:Ge Layers

 For investigation of the luminescent center profile cathodoluminescence measurements are used under variation of the primary electron energy E ₀ = 2…30 keV. Applying a constant incident power regime (E ₀·I ₀ = const), the depth profiles of luminescent centers are deduced from the range of the electron energy transfer profiles dE/dx. Thermally grown SiO₂ layers of thickness d = 500 nm have been implanted by Ge⁺-ions of energy 350 keV and doses (0.5–5)10¹⁶ ions/cm². Thus Ge profiles with a concentration maximum of (0.4 – 4) at% at the depth of d_m≅240 nm are expected. Afterwards the layers have been partially annealed up to T _a = 1100 °C for one hour in dry nitrogen. After thermal annealing, not only the typical violet luminescence (λ = 400 nm) of the Ge centers is strongly increased but also the luminescent center profiles are shifted from about 250 nm to 170 nm depth towards the surface. This process should be described by Ge diffusion processes, precipitation and finally Ge nanocluster formation. Additionally, a Ge surface layer is piled-up extending to a depth of roughly 25 nm.     

Sequestering Ability of Dicarboxylic Ligands Towards Dioxouranium(VI) in NaCl and KNO<Subscript>3</Subscript> Aqueous Solutions at <Emphasis Type="Italic">T</Emphasis>=298.15 K

The formation constants of dioxouranium(VI)-2,2′-oxydiacetic acid (diglycolic acid, ODA) and 3,6,9-trioxaundecanedioic acid (diethylenetrioxydiacetic acid, TODA) complexes were determined in NaCl (0.1≤I≤1.0 mol⋅L⁻¹) and KNO₃ (I=0.1 mol⋅L⁻¹) aqueous solutions at T=298.15 K by ISE-[H⁺] glass electrode potentiometry and visible spectrophotometry. Quite different speciation models were obtained for the systems investigated, namely: ML⁰, MLOH⁻, ML₂²⁻, M₂L₂(OH)⁻, and M₂L₂(OH)₂²⁻, for the dioxouranium(VI)–ODA system, and ML⁰, MLH⁺, and MLOH⁻ for the dioxouranium(VI)–TODA system (M=UO₂²⁺ and L = ODA or TODA), respectively. The dependence on ionic strength of the protonation constants of ODA and TODA and of both metal-ligand complexes was investigated using the SIT (Specific Ion Interaction Theory) approach. Formation constants at infinite dilution are [for the generic equilibrium pUO₂²⁺+q(L²⁻)+rH⁺ ⇌(UO₂²⁺) _p (L) _q H _r ^(2p−2q+r);β _pqr ]: log ₁₀ β ₁₁₀=6.146, log ₁₀ β ₁₁₋₁=0.196, log ₁₀ β ₁₂₀=8.360, log ₁₀ β ₂₂₋₁=8.966, log ₁₀ β ₂₂₋₂=3.529, for the dioxouranium(VI)–ODA system and log β ₁₁₀=3.636, log ₁₀ β ₁₁₁=6.650, log ₁₀ β ₁₁₋₁=−1.242 for dioxouranium(VI)–TODA system. The influence of etheric oxygen(s) on the interaction towards the metal ion was discussed, and this effect was quantified by means of a sigmoid Boltzman type equation that allows definition of a quantitative parameter (pL ₅₀) that expresses the sequestering capacity of ODA and TODA towards UO₂²⁺; a comparison with other dicarboxylates was made. A visible absorption spectrum for each complex reaching a significant percentage of formation in solution (KNO₃ medium) has been calculated to better characterize the compounds found by pH-metric refinement.     

Ion-Solvation Behavior of Pyridinium Dichromate in Water–N,N-Dimethyl Formamide Solvent Mixtures

The electrical conductances of pyridinium dichromate have been measured in N,N-dimethyl formamide–water mixtures of different compositions in the temperature range 283–313 K. The limiting molar conductance, Λ₀, association constant of the ion pair, K _A, and dissociation constant K _C have been calculated using the Shedlovsky and Kraus–Bray equations. The effective ionic radii (r _i ) of C₅H₅NH⁺ and Cr₂O₇ ^-\mathrm{Cr}_{2}\mathrm{O}_{7}^{ -} have been determined from the L_i⁰\Lambda_{i}^{0} values using Gill’s modification of Stokes’ law. The influence of the mixed solvent composition on the solvation of ions is discussed with the help of the ‘R’-factor ( R = \frachL _±⁰(solvent)hL _±⁰(water)R = \frac{\eta \Lambda_{ \pm}^{0}(\mathrm{solvent})}{\eta\Lambda_{ \pm}^{0}(\mathrm{water})}). Thermodynamic parameters are evaluated and reported. The results of this study are interpreted in terms of ion–solvent interactions and solvent properties.     

Phase Transitions and Critical Behaviour of Binary Liquid Mixtures

 Compared to the simple one-component case, the phase behaviour of binary liquid mixtures shows an incredibly rich variety of phenomena. In this contribution we restrict ourselves to so-called binary symmetric mixtures, i.e. where like-particle interactions are equal (Φ₁₁(r) = Φ₂₂(r)), whereas the interactions between unlike fluid particles differ from those of likes ones (Φ₁₁(r) ≠ Φ₁₂(r)). Using both the simple mean spherical approximation and the more sophisticated self-consistent Ornstein-Zernike approximation, we have calculated the structural and thermodynamic properties of such a system and determine phase diagrams, paying particular attention to the critical behaviour (critical and tricritical points, critical end points). We then study the thermodynamic properties of the same binary mixture when it is in thermal equilibrium with a disordered porous matrix which we have realized by a frozen configuration of equally sized particles. We observe – in qualitative agreement with experiment – that already a minute matrix density is able to lead to drastic changes in the phase behaviour of the fluid. We systematically investigate the influence of the external system parameters (due to the matrix properties and the fluid–matrix interactions) and of the internal system parameters (due to the fluid properties) on the phase diagram.     

An electroconductivity study on degree of counterion binding or dissociation of a-sulfonatomyristic acid methyl ester micelles in water as a function of temperature

 For a sodium salt of α-sulfonatomyristic acid methyl ester (14SFNa), one of the α-SFMe series surfactants, the differential conductivity (∂κ/∂C) _T , _P vs. square root of concentration (√C) was employed in order to determine not only CMC but also the limiting molar conductance (Λ⁰) and the molar conductance of micellar species (Λ^M). Based on the data of the degree of counterion binding to micelles (β) determined previously at different temperatures ranging 15–50 °C at every 5 °C, the experimental values of the degree of dissociation (ionization) of a micelle (α_EX) were calculated by regarding as α_EX=1−β. The ratio Λ^M/Λ⁰ corresponding to the ratio of slopes below and above CMC in the curve of specific conductivity (κ) vs. concentration (C), which has been often assumed to be the degree of ionization of micelles (α), was compared with the present α_EX. However, the ratio Λ^M/Λ⁰ (=α) was found to have a correlationship with α_EX (=1−β) as α_EX≈0.40×(Λ^M/Λ⁰), or strictly, α_EX=0.40 (Λ^M/Λ⁰)+0.08, indicating that the simple ratio of the slopes below and above CMC in κ vs. C curve is not true for α_EX=1−β. On the other hand, the method proposed by Evans gave a value closer to α_EX compared with the simple ratio. Received: 17 September 1996 Accepted: 8 April 1997     

Phase Transitions and Critical Behaviour of Binary Liquid Mixtures

Summary.  Compared to the simple one-component case, the phase behaviour of binary liquid mixtures shows an incredibly rich variety of phenomena. In this contribution we restrict ourselves to so-called binary symmetric mixtures, i.e. where like-particle interactions are equal (Φ₁₁(r) = Φ₂₂(r)), whereas the interactions between unlike fluid particles differ from those of likes ones (Φ₁₁(r) ≠ Φ₁₂(r)). Using both the simple mean spherical approximation and the more sophisticated self-consistent Ornstein-Zernike approximation, we have calculated the structural and thermodynamic properties of such a system and determine phase diagrams, paying particular attention to the critical behaviour (critical and tricritical points, critical end points). We then study the thermodynamic properties of the same binary mixture when it is in thermal equilibrium with a disordered porous matrix which we have realized by a frozen configuration of equally sized particles. We observe – in qualitative agreement with experiment – that already a minute matrix density is able to lead to drastic changes in the phase behaviour of the fluid. We systematically investigate the influence of the external system parameters (due to the matrix properties and the fluid–matrix interactions) and of the internal system parameters (due to the fluid properties) on the phase diagram. Received June 27, 2001. Accepted July 2, 2001