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[en] Microscopic investigations under polarized light and monochromatic light scattering experiments were performed on choles cholesteryl laurate-cholesteryl caprylate mixture (25:75% by weight). It was shown that the mixture exhibited several mesomorphic transitions: cholesteric, smectic A and smectic C. These mesophases are also revealed by electrical measurements; changes in activation energies, obtained from the Arrhenius plots (lnI = f(1/T) and changes in electric conductivity anisotropy (σsub(parallel)/σsub(perpendicular) or dielectric anisotropy (epsilonsub(parallel)/epsilonsub(perpendicular)) were obtained. (author)
[en] Complete text of publication follows. In this work is concerned with the simultaneous determination of ezitimibe and simvastatine in a binary mixture by using different methods. The first one is a derivative spectrophotometric procedure and the second one is ratio spectra first derivative spectrophotometry . In the first method, first derivative spectrophotometry, ezitimibe or simvastatine by using measurement of their first derivative signals at 237.361 nm, or 233.244 nm, respectively. The Calibration graphs were linear over the range for 4.0-28.0 μl-1 ezitimibe, or 4.0-36.0 μl-1 simvastatine. Other method, ratio spectra first derivative spectrophotometry, is based on ratio first derivative spectrophotometry, the amplitudes in the first derivative of the ratio spectra at 235.83 and at 249.51 nm were selected to determine ezitimibe and simvastatine in the binary mixture. Calibration graphs were established for 6.0-26.0 μl-1 ; linear correlation coefficient 0.9993 for ezitimibe and 3.0 - 24.6 μl-1 ; linear correlation coefficient 0.9991 for simvastatine in a binary mixture. The results obtained from first derivative spectrophotometric method were comparable with those obtained by using ratio spectra first derivative spectrophotometry. It was concluded that both the developed methods are equally accurate, sensitive, precise, reproducible, robust and rugged and the proposed methods were successfully applied to the pharmaceutical dosage from containing the above-mentioned drug combination without any interference by the excipients.
[en] This paper describes the mechanism of defect-mediated relaxation in a dodecagonal square-triangle random tiling phase exhibited by a simulated binary mixture of soft discs in 2D. We examine the internal transitions within the elementary mobile defect (christened the “zipper”) that allow it to move, as well as the mechanisms by which the zipper is created and annihilated. The structural relaxation of the random tiling phase is quantified and we show that this relaxation is well described by a model based on the distribution of waiting times for each atom to be visited by the diffusing zipper. This system, representing one of the few instances where a well defined mobile defect is capable of structural relaxation, can provide a valuable test case for general theories of relaxation in complex and disordered materials
[en] Compound contamination and toxicity interaction necessitate the development of models that have an insight into the combined toxicity of chemicals. In this paper, a novel and simple model dependent only on the mixture information (MIM), was developed. Firstly, the concentration-response data of seven groups of binary and multi-component (pseudo-binary) mixtures with different mixture ratios to Vibrio qinghaiensis sp.-Q67 were determined using the microplate toxicity analysis. Then, a desirable non-linear function was selected to fit the data. It was found that there are good linear correlations between the location parameter (α) and mixture ratio (p) of a component and between the steepness (β) and p. Based on the correlations, a mixture toxicity model independent of pure component toxicity profiles was built. The model can be used to accurately estimate the toxicities of the seven groups of mixtures, which greatly simplified the predictive procedure of the combined toxicity. - Highlights: → We develop a mixture toxicity model only on the mixture toxicity profiles. → We regard all multi-component mixtures as pseudo-binary mixtures. → The model is built by using a set of uniform design mixtures. → The model is validated by using a set of fixed concentration ratio mixtures. → The model can also predict the toxicity of external mixtures. - A novel method depends only on mixture information but not on pure component toxicity profiles for evaluating the combined toxicity.
[en] The systematic study of LiF-AF4 binary systems (A = Np-Pu) has led to the identification of three new complex fluorides of transuranide elements: Li4NpF8, LiNp4F17 and LiPu4F17. Synthesis conditions and radiocrystallographic characteristics are described and compared to the results available from the literature. (orig.)
[de]Systematische Untersuchungen der binaeren System LiF - AF4 (A = Np - Pu) fuehrte zur Identifizierung dreier neuer komplexer Transuranfloride: Li4NpF8, LiNp4F17 und LiPu4F17. Die Synthesebedingungen und die radiokristallographischen Charakteristika werden beschrieben und mit Literaturdaten verglichen. (orig.)
[en] The short-range order and the structure in liquid isotopic solutions and crystals (p-H2)c(o-D2)1-c (O≤c≤1) were investigated by the method of neutron diffraction with a pulsed source. The partial structure factor Scc(Q), characterizing the concentration-concentration correlation, was measured directly for a solution with average neutron coherent-scattering length equal to zero (c = 0.64). It was found that Scc(Q) is not constant; this indicates that the isotopic solution deviates from an ideal solution and that concentration fluctuations in short-range order exist. Crystals of the isotopic mixture are single-phase, but additivity breaks down and the excess mixing volume is negative: ΔVE/V ∼ -1.2% for c = 0.5. These effects are caused by the difference in the zero-point vibrations of the components and indicate a weak tendency toward separation in an isotopic solution. 29 refs., 6 figs., 1 tab
[en] A fluorimetric micro spot array using non-specific recognition function is described for the analysis of liquid samples. The array was composed of binary mixtures of various fluorescence dyes which were embedded in a hydrogel matrix. The interactions between the fluorescent dyes and their molecular surrounding inside the hydrogel, influence their fluorescence wave length and intensities. The array was used for the characterization of solvent mixtures. Developed fluorescence patterns of the complete array as well as the fluorescence intensity changes of single spots were analysed. It was proven, that specific analytical information can be gained using this non-specific recognition approach. The identification of some alcoholic beverages is described as an example of the application of this method when used for quality control purposes. Analogous to the appellation 'electronic nose' and 'electronic tongue' the described micro spot array acts as an 'optochemical tongue'
[en] Highlights: • The VLE of 1-(methoxymethoxy)-2-methyl-propane binary systems were reported. • Saturated vapor pressure data of 1-(methoxymethoxy)-2-methyl-propane were reported. • The VLE data provide a reference for separating 1-(methoxymethoxy)-2-methyl-propane. - Abstract: Isobaric vapour-liquid equilibria (VLE) experimental results for binary systems of 1-(methoxymethoxy)-2-methyl-propane with 1-butanol and isobutanol at 101.33 kPa were determined. Each binary mixture shows a minimum boiling azeotrope at 101.33 kPa, in which the azeotropic temperature and composition are 381.19 K and 26.72 mol% (1-butanol) and 377.55 K and 53.34 mol% (isobutanol), respectively. The VLE measurements were correlated by the van Laar, Wilson and NRTL models for which the binary interaction parameters are reported. The results show that the measurements of two binary systems provide a good agreement with the calculated values acquired by the Wilson and NRTL models, respectively. The thermodynamic consistency of the VLE measurements was checked using the traditional area test and the direct test methods.
[en] The Boltzmann-Hilbert equation for the self diffusion coefficient in a binary hard sphere mixture described by concentration csub(A) = nsub(A)/n, mass ratio α = msub(A)/msub(B) and size ratio γ = sigma2sub(AB)/sigma2sub(AA) is solved by an iterative technique using the method of 'successive uncorrelated binary collisions' (SUBC-model). In the numerical procedure the contribution of each of N collisions of a tagged particle (say A) with particles of either species A or B to the solution of the integro-differential equation is calculated for hard spheres for a wide range of mass ratios (10-3) less than or equal to α less than or equal to 103), 0.33 less than or equal to γ less than or equal to 16 and the full concentration range 0 less than or equal to csub(A) less than or equal to 1 in steps of 0.1. A brief discussion for Maxwell-molecules, other forms of potentials and the limiting cases for a Lorentz gas (csub(A) → 0, α → 0) and the quasi Lorentz gas or Rayleigh gas (csub(A) → 0, α → infinity) are included. The self diffusion coefficient is calculated for the mixture using the time integral over the velocity autocorrelation function in the Kubo-Green formalism. The results are compared with a highly accurate Sonine poloynominal type approximation of the Boltzmann equation (for csub(A) → 0) and it is shown that the Chapman-Enskog method is more effective for α → 0 while the SUBC-model is more effective for α → infinity. The SUBC-model is used to calculate a simple 'two collision approximation' and to compare it with the numerical solution of the Boltzmann-Hilbert equation and the results obtained for the self diffusion coefficient. The 'exact' results of the self diffusion coefficient are reproduced by the 'two collision approximation' to better than +- 1% in the investigated range of (csub(A), α, γ) values. (Author)