Die Untersuchung von mit Holzgeist denaturiertem Spiritus

Ohne Zusammenfassung     

Mixed self-assembled monolayers of azobenzene photoswitches with trifluoromethyl and cyano end groups

Mixed self-assembled monolayers (SAMs) of alkanethiolates carrying azobenzene chromophores with either a trifluoromethyl or a cyano substituent have been studied. High-resolution x-ray photoelectron spectroscopy proves that the ratio of adsorbed molecules can be arbitrarily adjusted via the molar fractions in solution. As a function of these molar fractions core level shifts are observed which are attributed to local work-function changes. By simulating the electric dipole field distribution, the continuous core level shifts are ascribed to a homogeneous mixture of molecules with different end groups adsorbed on adjacent lattice sites. Near-edge x-ray absorption fine structure measurements reveal formation of well-ordered SAMs. Despite the difference in dipole moment of the end groups, the molecular tilt and twist angles are identical for both single-component SAMs and a 1:1 mixed SAM.     

9Mg(OH)(2)·MgCl(2)·4H(2)O, a high temperature phase of the magnesia binder system

The metastable phase 9Mg(OH)(2)·MgCl(2)·4H(2)O (9-1-4 phase) was found at the extended metastable isotherm of Mg(OH)(2) in the system MgO-MgCl(2)-H(2)O at 120 °C and occurs as intermediate binder phase during setting of magnesia cement due to temperature development of the setting reaction. The crystal structure of the 9-1-4 phase was solved from high resolution laboratory X-ray powder diffraction data in space group I2/m (C2/m) (a = 22.2832(3) ?, b = 3.13501(4) ?, c = 8.1316(2) ?, β = 97.753(1)°, V = 562.86(2) ?(3), and Z = 1). Structural and characteristical relations of the phases in the system MgO-MgCl(2)-H(2)O can be derived, with which the development of the cement or concrete qualities becomes explainable.     

Crystallization of metastable monoclinic carnallite,KCl·MgCl2·6H2O: missing structural link in the carnallite family

During evaporation of natural and synthetic K–Mg–Cl brines, the formation of almost square plate‐like crystals of potassium carnallite (potassium chloride magnesium dichloride hexahydrate) was observed. A single‐crystal structure analysis revealed a monoclinic cell [a = 9.251 (2), b = 9.516 (2), c = 13.217 (4) Å, β = 90.06 (2)° and space group C2/c]. The structure is isomorphous with other carnallite‐type compounds, such as NH₄Cl·MgCl₂·6H₂O. Until now, natural and synthetic carnallite, KCl·MgCl₂·6H₂O, was only known in its orthorhombic form [a = 16.0780 (3), b = 22.3850 (5), c = 9.5422 (2) Å and space group Pnna].     

Dehydration of the Sorel Cement Phase 3Mg(OH)2·MgCl2·8H2O studied by in situ Synchrotron X‐ray Powder Diffraction and Thermal Analyses

Dehydration is an important process which affects the chemical, physical and mechanical properties of materials. This article describes the thermal dehydration and decomposition of the Sorel cement phase 3Mg(OH)₂ · MgCl₂ · 8H₂O, studied by in situ synchrotron X‐ray powder diffraction and thermal analyses. Attention is paid on the determination of the chemical composition and crystal structure of the lower hydrates, identified as the phases 3Mg(OH)₂ · MgCl₂ · 5.4H₂O and 3Mg(OH)₂ · MgCl₂ · 4.6H₂O. The crystal structure of 3Mg(OH)₂ · MgCl₂ · 4.6H₂O is solved and refined by the Rietveld method and a structural model for the 3Mg(OH)₂ · MgCl₂ · 5.4H₂O phase is given. These phases show statistical distribution of water molecules, hydroxide and chloride anions positioned as ligands on the magnesium octahedra. A structural scheme of the temperature induced transformations in the thermal range from 25 to 500 °C is presented.     

Fully charged: Maximizing the potential of cationic polyelectrolytes in applications ranging from membranes to gene delivery through rational design

Polyelectrolytes have found utility across various applications in materials science, from electrochemical devices to biotechnology, due to their facile processing and tunable properties. Through chemistry, rational manipulation of molecular structure enables individual families of polyelectrolytes to be used in emerging advanced applications. In this perspective, we focus on cationic systems, and we describe how various structural motifs influence macromolecular properties for anion exchange membranes and gene delivery vectors. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3167–3174     

Vergleich verschiedener quantitativer Auswerteverfahren für Autoradiograimme

Es wurden ein Joyce-Loebl-Mikrodensitometer mit angebauter Auswerteanlage, ein Zeiss-Schnellphotometer, das Gerätesystem ?, Densitron” und das Agfacontour-Professional-Verfahren zur Auswertung desselben Autoradiogrammes angewandt. Dabei wurden mittlere Schwärzungen und die Homogenität bestimmt, sowie auch eine Teilung der Autoradiogrammfläche in Schwärzungsbereiche (Bestimmung von Schwärzungssummen) vorgenommen.

Bei der Answertung der Autoradiogramme von Struklur- und Mikrosegregationsuntersuchungsproben ist die auf der Basis des Joyce-Loebl-Densitometers gebaute Anlage die präziseste und das Gerätesystem ?Densitron” eine präzise und wenig arbeitsaufwendige Anlage. Bei den Autoradiogrammen mit Zonen. oder Bandschwärzungsverteilungen bieten das ?Densitron” und das Agfacontour-Professional-Verfahren fast die gleichen Darstellungsmöglichkeiten, das ?Densitron”-System ermöglicht aber eine quantitative und die Agfacontour-Technik nur eine halbquantilative Auswertung des Autoradiogrammes. Schwärzungsverläufe (z. B. bei Diffusionsprofilen) sind mit Hilfe des Joyce-Loebl-Densitometers am besten zu erhalten.     

Autoradiographische Abbildung von 14N-Verteilungen mit Festkörperspurdetektoren

Laterale Verteilungen von Stickstoff in Festkörpern können mit Hilfe der nentroneninduzierten Autoradiographie auf Grund der Reaktion ¹⁴N (n, p)¹¹C aufgenommen werden. Als Festkörperspurdetektor werden kommerzielle Zellulosenitratfolien vom Typ LR 115 und CA 80—15 und auch selbsthergestellte CN-Folien eingesetzt.⁺

Die Ätz- und Bestrahlungsbedingungen werden dargestellt. Aus experimentellen Untersuchungen biologischer Objekte und stickstoffhaltiger Festkörperproben etgab sich für Stickstoff eine untere Nachweisgrenze von ungefähr 1 Gew.-%.     

Absolute coverage of C2H2 and C2H4 on Pt(111)

Quantitative XPS measurements have been performed in order to determine the absolute coverage of acetylene and ethylene adsorbed on Pt(111) showing a 2 × 2 LEED pattern. This LEED pattern has so far been attributed to a 2 × 2 superstructure with a coverage of 0.25. A quantitative evaluation of the C(1s) peak intensities for these adsorbed layers in comparison with adsorbed CO shows that the coverage is 0.5 instead of 0.25. Therefore the 2 × 2 LEED pattern should be assigned to a 2 × 1 superstructure in three domains rather than a 2 × 2 superstructure.