Time-dependent mixing and demixing processes in binary lipid monolayers studied by mixed and separate spreading using film pressure and film potential measurements

Using both spreading techniques — mixed spreading and separate spreading- and, simultaneously, film pressure and film potential measurements, the mixing behavior of the following five binary systems was investigated and compared: 1) system 1,2-dilauroyl-phosphatidylethanolamine/cholesterol; 2) system 1,2-dimyristoyl-phosphatidylethanolamine/cholesterol; 3) system 1,2-dipalmitoyl-phosphatidylethanolamine/cholesterol; 4) system Na-eicosyl sulphate/hexadecanol; 5) system phosphatidic acid/1,2-dimyristoyl-phosphatidylethanolamine.Analyzing the time and concentration dependence of the /a isotherms and v/a isotherms (^s = film pressure, v ^s potential,a=average area per molecule in mixed films in the monolayers) of the binary monolayers it can be concluded that the components of the binary systems 1–4 are complete miscible in the monolayers. On the other hand the components of the system 5 are probably partially miscible only.     

p-V m-x Properties of Water-Dimethylformamide System at 288.15 K over the Pressure Range 0.1-100 MPa

The compressibility factors k ((p ₀) - ta;(p))/ta;(p ₀ )) of water-dimethylformamide (DMF) binary mixtures are measured over the entire concentration range at 288.15 K and pressures of up to 100 MPa with a constant-volume piezometer. The specific and molar volumes in the water-DMF system are estimated as well as the isothermal compressibility coefficient s and excess and partial molar volumes of the system components. The composition dependence of the specific volume in the water-DMF system has extrema, its shape being pressure-dependent; such a dependence of the compressibility factor passes through a minimum; and the partial coefficient of the isothermal compressibility of water has an inversion point.     

Interaction of a Single State with a Known Infinite System Containing One-Parameter Eigenvalue Band

Interaction of a quantum system S ₁ ^a containing a single state |> with a known infinite-dimensional quantum system S ^b containing an eigenvalue band [ _a , _b ] is considered. A new approach for the treatment of the combined system S =S ₁ ^a S ^b is developed. This system contains embedded eigenstates |()> with continuous eigenvalues [ _a , _b ], and, in addition, it may contain isolated eigenstates | _I > with discrete eigenvalues _I [ _a , _b ]. Exact expressions for the solution of the combined system are derived. In particular, due to the interaction with the system S ^b , eigenvalue E of the state |> shifts and, in addition, if E[ _a , _b ] this shifted eigenvalue broadens. Exact expressions for the eigenvalue shift and for the eigenvalue distribution of the state |> are derived. In the case of the weak coupling this eigenvalue distribution reduces to the standard resonance curve. Also, exact expressions for the time evolution of the state |(t)> that is initially prepared in the state |(0)>|> are obtained. Here again in the case of the weak coupling this time evolution reduces to the familiar exponential decay. The suggested method is exact and it applies to each coupling of the system S ₁ ^a with the system S ^b , however strong. It also presents a relatively good approximation for the interaction of a nondegenerate eigenstate | _s > of an arbitrary system S ^a with an infinite system S ^b containing a single eigenvalue band, provided this eigenstate is relatively well separated from other eigenstates of S ^a and provided the interaction between the systems S ^a and S ^b is not excessively strong.     

Binding/antibinding analyses for diatomic interactions H 2 + system

The region-functional concept of electron density has been quantitatively examined for 1s_g, 2p_u, 2p_u, and 3d_g states of H ₂ ⁺ system on the basis of Berlin diagram which divides the three-dimensional molecular space into binding and antibinding regions. The electronic charge, Hellmann-Feynman (H-F) force, and stabilization energy of the system are partitioned into the binding and antibinding contributions by the regional integrations.Dynamic behaviors of the electron density (i.e. electron-cloud preceding and following) during the interaction processes are also clarified using the centers of electron density and force density.Differences in attractive and repulsive, and - and -type interactions are discussed from the force and density point of view.     

The phase diagram of the water-hydrogen system in the crystallization field of solid solutions based on ices Ih and II at high pressures

The decomposition curves of the solid solutions based on ices Ih (-solutions) and II (-solutions) in the water-hydrogen system were studied by the DTA technique at pressures up to 7 kbar. The -solution is destabilized by pressure but to a lesser degree than ice Ih and is stable up to 2.3 kbar. The-solution is stabilized by pressure and at 7 kbar decomposes at about 20°C. TheP, T-phase diagram of the water-hydrogen system in the crystallization range is constructed on the basis of reference [1] and our data. All possible types of stoichiometric interrelationships in the guest —host system are demonstrated by the example of the water-hydrogen system.     

An estimation of force constant change of Mössbauer119Sn impurity nuclei in lead host

The recoilless fractionf and the SOD data of Sn as impurity in Pb are analyzed for any force constant change in the framework of MANNHEIM's model. On the basis off-values, the force constant ratio _ih / _hh turns out to be 0.81±0.02. Expectedly no localized modes are found to exist in the system.     

Structure of microemulsions of AOT and water in dodecane

The dielectric properties of the system water/AOT/dodecane are studied as a function of volume fraction of the dispersed phase and molar ration (water/surfactant). Data shows that the spherical model is valid only at lown values or low values. At high concentrations of dispersed phase, one has to consider micellar aggregation or deformation.     

1H-NMR-spektroskopische Analyse von 2-Chlor-1.3.2-dioxarsolan

The¹H-NMR-spectral data of 2-chloro-1.3.2-dioxarsolane are presented and discussed. The protons of the methylene groups form in concentrated solutions by rapide chlorine exchange anAAAA spin system. In dilute solutions the protons form anAABB spin system, which is changed to anAAAA system by addition of chlorine ions.The vicinal H–C–C–H-coupling constants indicate a twist-envelope conformation.

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Mit 1 Abbildung     

Phase behavior and dynamic properties in mixed systems of anionic and cationic surfactants: lithium perfluorooctanesulfonate/diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) and lithium dodecyl sulfate/DEFUMAC aqueous mixtures

Two ternary phase diagrams of the cationic perfluorosurfactant diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) with an anionic perfluorosurfactant lithium perfluorooctanesulfonate (LiFOS) and an anionic hydrocarbon surfactant lithium dodecyl sulfate (LiDS) have been established at 25°C. The total surfactant concentration was less than 20wt%. In a wide mixing region of the LiFOS/DEFUMAC system, a lamellar-type phase,P , was identified by its texture under a polarization microscope and by its x-ray diffraction pattern. Dispersed fragments ofP -phase are present in the dilute solutions in which one surfactant was in excess. The anisotropy of electrical conductivity, flow birefringence, dynamic light scattering, and electric briefringence demonstrate that theP fragments are disk-like with a radius of 0.7 m. The disk-likeP particles are transformed by shear into a spherical aggregate ofL above a critical shear gradient. LiDS/DEFUMAC mixed solution forms dispersed and precipitatedL in the dominant region. Radius and micropolarity of the dispersedL aggregates are decreased as the ratio of LiDS:DEFUMAC approaches 1:1. On the basis of x-ray diffraction measurement the structure of precipitatedL -phase seems to consist of monolayers.     

The multi-centre integrals of derivative,spherical GTOs

The multi-centre integrals of the orbital system ⁿ Y _lm () exp (–r ²) are evaluated using the Talmi transformation of nuclear shell theory. The integrals are simpler than those of the systems r ²ⁿ Y lm(r) exp (–r ²), x ^l y ^m z ⁿ exp (–r ²), (/x) ^l (/y) ^m (/z) ⁿ exp (–r ²) and the spherical oscillator functions. The integral types investigated are: overlap, electric dipole transition (momentum operator), kinetic energy, three-centre nuclear attraction, four-centre electronic repulsion, three-centre spin-orbit coupling, and magnetic dipole transition (three-centre integrals of the angular momentum operator).     

Thermodynamic parameters of coupled chemical reactions from temperature jump relaxation amplitudes

Equations describing the temperature jump amplitudes associated with a system of two coupled reactions (TRIS-phenol red) as well as the ternary system (Mg²⁺-iminodiacetic acid-phenol red) are presented. The termodynamic parameters calculated from experimentally measured temperature perturbation amplitudes using a multiparametric curve fitting procedure are found to be in good agreement with those determined from pH- and costant rate thermometric titrations. For phenol red, pK _I =7.55, H _I =3.45 kcal, and for Mg²⁺ iminodiacetic acid, log K _M =2.84, H _M =3.25 kcal, were obtained. It is shown that this method can be used to determine accurate thermodynamic enthalpy changes over a narrow temperature interval of less than 1.0°C from a single experiment requiring about 50 l of sample solution.     

Analysis of the Temperature and Composition Dependence of Viscosimetric Properties of 2-Butanone <Emphasis Type="Bold">+</Emphasis> 2-Butanol Solvent Mixtures

Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0x_i1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(x_i), and =(T, x_i). Viscosity deviations, , from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G*^E, have been calculated. As an alternative and complementary approach to such investigations, the fluidity () of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components.     

Kinematic Viscosities of Binary Liquid Mixtures of 2-Butanone with 1,2-Propanediol

Kinematic viscosities of the binary 2-butanone (1) + 1,2-propanediol (2) solvent system have been measured for mixtures covering the whole miscibility range expressed by 0 x _i 1, at 19 temperatures in the range –10 t/°C 80. The measured values have been used to test empirical equations that express the kinematic viscosities as functions of the composition and temperature. Excess kinematic viscosities (^E) have also been calculated. Sign and magnitude of these quantities are discussed in terms of type and nature of specific intermolecular interactions. Furthermore, derived quantities such as thermodynamic parameters of viscous flow (G, H and S), are analyzed on the basis of Eyring's model. All the investigated excess mixing properties indicate the probable existence of stable two-component adducts in this binary solvent system.     

K β /K α X-ray intensity ratio in the region of 15≤Z≤22

The X-ray intensity ratioK /K has been measured by using a 10 mCi⁵⁵Fe source (MnK X-rays) and high resolution Si(Li) detector system coupled to a computer-controlled multichannel analyzer over the range of 15Z22. Corrections have been made to the measured relative intensities (K andK X-rays) for self-absorption in the sample, air, Be-window absorption and detection efficiency. The results are compared with those of other experiments and with the Scofield calculations.     

On the Interaction of Two Finite-Dimensional Quantum Systems

Interaction of quantum system S ^a described by the generalised × eigenvalue equation A| _s =E _s S ^a | _s (s=1,...,) with quantum system S ^b described by the generalised n×n eigenvalue equation B| _i = _i S ^b | _i (i=1,...,n) is considered. With the system S ^a is associated -dimensional space X ^a and with the system S ^b is associated an n-dimensional space X _n ^b that is orthogonal to X ^a . Combined system S is described by the generalised (+n)×(+n) eigenvalue equation [A+B+V]| _k = _k [S ^a +S ^b +P]| _k (k=1,...,n+) where operators V and P represent interaction between those two systems. All operators are Hermitian, while operators S ^a ,S ^b and S=S ^a +S ^b +P are, in addition, positive definite. It is shown that each eigenvalue _{k i} of the combined system is the eigenvalue of the × eigenvalue equation . Operator in this equation is expressed in terms of the eigenvalues _i of the system S ^b and in terms of matrix elements _s |V| _i and _s |P| _i where vectors | _s form a base in X ^a . Eigenstate | _k ^a of this equation is the projection of the eigenstate | _k of the combined system on the space X ^a . Projection | _k ^b of | _k on the space X _n ^b is given by | _k ^b =( _k S ^b –B)^–1(V– _k P})| _k ^a where ( _k S ^b –B)^–1 is inverse of ( _k S ^b –B) in X _n ^b . Hence, if the solution to the system S ^b is known, one can obtain all eigenvalues _{k i} } and all the corresponding eigenstates | _k of the combined system as a solution of the above × eigenvalue equation that refers to the system S ^a alone. Slightly more complicated expressions are obtained for the eigenvalues _{k i} } and the corresponding eigenstates, provided such eigenvalues and eigenstates exist.     

Complexation of (l)-alanine-β-naphthylamide hydrobromide with methyl-β-cyclodextrin: An ultrafiltration study

The complexation constant for the system (l)-alanine--naphthylamide hydrobromide (S) and methyl--cyclodextrin (Me--CD) has been determined using an ultrafiltration method. Me--CD and its inclusion complex are retained by ultrafiltration (UF) membranes of 1 kDalton molecular weight cut-off with a rejection rate of 97%. As the substrate S passes freely throughout the UF membrane, the concentration of free and bounded S is easily determined. The value thus obtained for the complexation constants is in good agreement with those previously reported for similar inclusion complexes. In addition, the specific optical rotation of the complex has been determined. As expected, the specific rotations of S and CD are not additive.     

Schrödinger Equation Solutions for the Central Field Power Potential Energy II. V(r) = −V 0(r/a 0)2ν−2, 0 ≤ ν ≤ 1, the Bound States

The bound states of the generalized Schrödinger equation system with radial potential energy V(r) = –V ₀(r/a ₀)^2–2, 0 1, are described. The solutions of the differential equation are related to the functions for the bound state problem with 1. The Green's function is constructed as well as its first iteration, the traces of both functions are calculated, and an upper and lower bound for the ground state is established. A WKB-like approximate solution for the eigenvalues and eigenfunctions is derived.     

A model study of the interaction of a hydrogen bond with a π-electron system

A semi-empirical CNDO/2 calculation of the structure of the diimide-hydrogen fluoride hydrogen bonded complex is reported. The results are compared to calculations on a similar saturated system in an attempt to elucidate the effect of a neighboring -system on a hydrogen bond, and to uncomplexed diimide to study the effect of the hydrogen bond on the -system.     

A thermodynamic study of the inclusion processes of α- andβ-cyclodextrins with the acid forms of methyl orange and methyl yellow

The effect of temperature on the UV-visible spectra of the acid forms of methyl orange and methyl yellow in the presence of - and-cyclodextrins was analysed in terms of 1 : 1 inclusion processes. Three inclusion processes were considered for each azo dye/cyclodextrin system. The processes are the apparent inclusion process, the ammonium inclusion process, and the azonium inclusion process. The values of H ⁰ and S ⁰ are reported for each process. The inclusion complexes of the ammonium tautomer are more stable than those of the azonium tautomer and -cyclodextrin inclusion complexes are more stable than those of-cyclodextrin. The inclusion processes resulted in a shift in the position of the tautomeric equilibrium of an azo dye. A significant color fading was observed in -cyclodextrin/methyl yellow solutions. No measurable changes in the absorbances were observed in the case of azo dye solutions containing -cyclodextrin.