An algebraic method that includes Gibbs minimization for performing phase equilibrium calculations for any number of components or phases

The most widely used technique for performing phase equilibria calculations is the K-value method (equality of chemical potentials). This paper proposes a more efficient algorithm to achieve the results that includes Gibbs minimization when we know the number of phases. Using the orthogonal derivatives, the tangent plane equation and mass balances, it is possible to reduce the Gibbs minimization procedure to the task of finding the solution of a system of non-linear equations. Such an operation is easier and faster than finding tangents or areas, and appears to converge as fast as the K-value method. Examples illustrate application of the new technique to two and three phases in equilibrium for binary and ternary mixtures.     

Vapor-liquid equilibria for polybutadiene and polyisoprene solutions

Vapor-liquid equilibria in binary solutions of hydrocarbons (n-hexane, benzene, toluene, cyclohexane) and chlorinated methanes [carbon tetrachloride (CCl₄), chloroform (CHCl₃), and dichloromethane (CH₂Cl₂)] in polybutadiene (PBD) and polyisoprene have been determined at 23.5°C by using the piezoelectric sorption method. The weight-fraction activity coefficient of solvent (a₁/w₁) in cis-PBD (98% cis-1,4 addition) and random cis-trans-PBD (r-PBD, 34.3% cis-1,4 addition; 54.3% trans-1,4 addition; 11.4% vinyl-1,2 addition) are almost equal for CCI₄, CHCI₃, CH₂CI₂, benzene, and toluene solutions, while the values of a₁/w₁ in n-hexane and cyclohexane solutions in cis-PBD are larger than those in r-PBD solutions. The values of a₁/w₁ for solutions of hydrocarbons and chlorinated methanes in cis-1,4 polyisoprene (95% cis-1,4 addition) have been compared with those for cis-PBD.     

Design of Dynamically Loaded Fiber-Reinforced Structures with Account of Their Vibro-Acoustic Behavior

Dynamically loaded structures for high-technology applications generally require high material damping combined with low construction weight and adequate stiffness. Advanced lightweight structures will have to meet not only these dynamic demands but also improved acoustic (low noise) standards. High-performance materials like magnesium, aluminum, or titanium, which are mainly used in today's lightweight applications, reach their limits with respect to these dynamic and especially vibro-acoustic requirements. They offer a high specific stiffness and strength, but a relatively low damping, which leads to intense acoustic radiation. Therefore, composites or compound materials with a dynamically and vibro-acoustically optimized property profile are needed. The structural dynamic and vibro-acoustic behavior of these types of lightweight structures cannot be described by the use of classical models. Here, the advanced methods developed at ILK are considered, which take into account the special mechanical properties of the fiber-matrix compound. Also, sophisticated numerical simulation techniques such as the finite and the boundary element method are successfully applied.     

The effect of polymer side chains on vapor sorption in polyacrylate and polymethacrylate solutions

The segment fraction Ψ₁ activity coefficients, a₁/Ψ₁, of solvents have been determined by the piezoelectric sorption method for 0.1 ≤ Ψ₁ ≤ 0.5 in binary solutions of chlorinated methanes [carbon tetrachloride (CCl₄), chloroform (CHCl₃), and dichloromethane (CH₂Cl₂)] with aromatic hydrocarbons (benzene and toluene) in poly(methyl methacrylate), poly(methyl acrylate), poly(ethyl methacrylate), and poly(n-butyl acrylate) at 23.5°C. The present results for toluene in PMMA agree with previously published values obtained by gas-liquid chromatography. For CCl₄ and the aromatic hydrocarbons, the polymer–solvent interaction parameter χ is positive and constant, while for the polar solvents (CHCl₃ and CH₂Cl₂), χ is negative and increases with increasing Ψ₁. The effect of the polymer side chains on vapor sorption in nonpolar and polar solvent systems is discussed in terms of the χ parameter.     

Vapor-liquid equilibria for polyisobutylene solutions

Vapor sorption isotherms in binary solutions of polyisobutylene (PIB), (M_η = 4.7 × 10⁶ g/mol) in hydrocarbons (cyclopentane; cyclohexane; n-heptane; 2,2-dimethyl butane; and 2,2,4-trimethyl pentane) and chlorinated methanes [carbon tetrachloride (CCI₄) and chloroform (CHCI₃)] have been determined at 23.5°C using the piezoelectric sorption method. The polymer-solvent interaction parameter χ obtained agrees with previously published values determined by using gas-liquid chromatography and a quartz-helix vapor sorption apparatus. The Flory theory of corresponding-states has been applied to the experimental results through the χ parameter and affords a good prediction of the concentration dependence of χ for solutions of chloroform, carbon tetrachloride, n-heptane, and 2,2-dimethyl butane in PIB. The experimental values of \documentclass{article}\pagestyle{empty}\begin{document}$ [\partial (a_1 /\psi _1 )/\partial a_1 ]_{T,P} $\end{document} for the PIB solutions are constant over the measured concentration range, for example \documentclass{article}\pagestyle{empty}\begin{document}$ [\partial (a_1 /\psi _1 )/\partial a_1 ]_{T,P} $\end{document} = ?4.1 for CCI₄, ?3.65 for CHCI₃, ?3.0 for 2,2-dimethyl butane and n-heptane, ?2.7 for 2,2,4-trimethyl pentane, ?2.7 for cyclohexane, and ?1.7 for cyclopentane, where a₁ is the solvent activity and ψ₁ is the solvent segment fraction. The correlations between the values of \documentclass{article}\pagestyle{empty}\begin{document}$ [\partial (a_1 /\psi _1 )/\partial a_1 ]_{T,P} $\end{document} and the theories of Guggenheim, Miller, Huggins, and Flory are discussed.     

The photon-ion merged-beams experiment PIPE at PETRA III—The first five years

The Photon-Ion Spectrometer at PETRA III—in short, PIPE—is a permanently installed user facility at the "Variable Polarization XUV Beamline" P04 of the synchrotron light source PETRA III operated by DESY in Hamburg, Germany. The careful design of the PIPE ion-optics in combination with the record-high photon flux at P04 has lead to a breakthrough in experimental studies of photon interactions with ionized small quantum systems. This short review provides an overview over the published scientific results from photon-ion merged-beams experiments at PIPE that were obtained since the start of P04 operations in 2013. The topics covered comprise photoionization of ions of astrophysical relevance, quantitative studies of multi-electron processes upon inner-shell photoexcitation and photoionization of negative and positive atomic ions, precision spectroscopy of photoionization resonances, photoionization and photofragmentation of molecular ions, and of endohedral fullerene ions.     

Dislocation Structure and Strain Localisation in Nickel Single Crystals Cyclically Deformed at 77 K

An experimentally based investigation is presented of the dislocation structure and of glide effects occurring in single slip oriented nickel crystals cyclically deformed at 77 K until saturation of the stress amplitude. Special attention is paid to a comparison of slip and structure phenomena observed in fatigue tests at 77 K and those found after cycling at room temperature (RT) and elevated temperatures. At strain amplitudes within the plateau region of the cyclic stress‐strain curve, where at higher temperatures in the crystal two structure types co‐exist, at 77 K nearly the entire specimen volume is occupied by one structure “phase”, a dislocation‐“condensed” wall configuration. On different scale levels the main characteristics of this extended wall structure were found to be independent of the imposed amplitude, and they turned out to fit in the temperature dependence of the structure features of the ladder‐like wall phase characterising the zones of intense slip (persistent slip bands) at RT and elevated temperatures. At 77 K the strain is localised in narrow slip bands (SBs) in the same way as at higher temperatures, although there is no indication of a “two‐phase” structure. From the experimental findings it is concluded that WINTERs “two‐phase” model remains valid, when averaging the plastic strain values over all SBs and over a sufficient number of cycles.     

Determination of internal stresses in cyclically deformed metals

Single crystals of Fe and Fe-0·5 wt. % Si alloy were cyclically deformed to saturation. Internal stresses have been determined by stress relaxation and stress dip methods as a function of prior strain rate. The values of internal stresses are generally strain rate dependent and are systematically higher for the stress relaxation method. The physical meaning of strain rate independent internal stress obtained by extrapolation to zero strain rate is discussed.     

Vorschlag zur Vollautomatisierung der Voltammetrie/Polarographie bei Verwendung eines Probentellers

Zusammenfassung Durch fehlende Vollautomatisierung inkl. automatischer Probenzuführung fand die Voltammetrie als sehr empfindliche und präzise Methode in der Trinkwasserroutineanalytik von Metallspuren bisher nur wenig Anwendung. In dieser Arbeit wird ein automatisches Probenwechselsystem mit Durchflußmeßzellen vorgestellt, das im Prinzip an alle vorhandenen Voltammaten angepaßt werden kann, in diesem Fall an die PAR 384 A-Anlage angeschlossen wurde. Mittels Rechnerkopplung können dabei die Analysenmöglichkeiten des Grundgerätes verbessert werden; zudem wird die automatisierte Anwendung der Standardaddition möglich. Gleichzeitig eröffnet der Rechner auch die Möglichkeit zur effektiven Verwaltung und Verarbeitung der Analysendaten und erspart bei geeigneter Ablegung auf einem Datenträger auch die Eingabe der Ergebnisse in eine EDV-Einheit. Insofern mindestens 50 ml Probevolumen zur Verfügung stehen, läßt sich dieses System auch für viele andere Probenarten bereitstellen.

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Proposal for completely automated voltammetry/ polarography using a sampler

Summary Because of missing completely automated voltammetry/polarography with automated sampling this sensitive and precise method has not been used for routine analysis of heavy metals in drinking water. In this investigation a proposal is given for an automated sample system that should be compatible with all existing voltammetry devices, in this case with the PAR 384 A Polarographic Analyzer. Using a PC for monitoring gives an improvement of the PAR 384A concerning analytical facilities. Automated standard addition is also possible. Furthermore, the computer realises an effective management and processing of analytical data. If there is a minimum volume of 50 ml, this system will also be applicable to other kinds of samples.