Half-life measurements and gamma spectroscopy in the decay184Re m →184W

The half-lives of the intrinsic states at 1,285.8 and 1,502.2 keV in¹⁸⁴W have been measured in the decay of¹⁸⁴Re ^m to be 8.33±0.18Μs and 2.35±0.10 ns, respectively. These half-lives determine absolute gamma-ray transition probabilities of eight transitions and yield upper limits for three transitions. The decay scheme of¹⁸⁴Re ^m →¹⁸⁴W is improved through measurements of delayed gamma-ray spectra with a Ge(Li) detector. Spin and Nilsson model interpretations are discussed.     

Darstellung von VO2-einkristallen der oberen und unteren phasengrenze durch chemischen transport

The chemical transport of VO₂ with TeCl₄ was investigated in the temperature range of about 1000°C and 600°C. In the first case there is TeO₂ existing in the gaseous phase, in the second case the TeO₂ has no noticeable vapour pressure. The transport takes place from the hot to the cool zone. In both cases we obtained high transport rates of 10 to 20 mg h^-1. The composition of the gaseous phase is calculated and the transport mechanisms are discussed. It is possible to obtain VO₂ with the upper and lower phase boundary by variation of the initial compositions. Starting with compositions lower than VO_1.99 we obtained near 1000°C in the deposition zone V₈O₁₅ first and after a time VO₂ with the lower phase boundary. Compositions higher than VO_2.00 give vanadium dioxide with the upper phase boundary. In the temperature range of about 600°C however we obtained the phase with the higher oxygen content first. The results are compared with those, which have been obtained by the transport of VO₂ with HCl and Cl₂ — which takes place from the cool to the hot zone.     

Die Bildungsenthalpie der Tellurtetrahalogenide

The Enthalpy of Formation for TeX₄ The enthalpies of formation were derived for the tetrahalogenides TeCl₄, TeBr₄, and TeJ₄ from the enthalpy of solution in KOH. The determination based on the enthalpy of formation for TeO₂ and the KX and their enthalpy of solution in KOH. Results see ?Inhaltsübersicht”?.     

Originalarbeiten: Neuartiger Ionisationsdetektor zum gaschromatographischen Nachweis von Schadstoffen in Luft

Zur kontinuierlichen Überwachung der Luft auf Schadstoffe werden Analysatoren eingesetzt, die auf dem Prinzip der Aerosolionisationsgasanalyse beruhen. Der nachzuweisende Schadstoff wird in ein Aerosol übergeführt und in einer speziellen Ionisationskammer mit eingebauter Strahlungsquelle detektiert.

Derartige Analysatoren sind nur für den Nachweis eines Schadstoffes geeignet, wobei es schwierig ist. Querempfindlichkeiten zu beseitigen. Der selektive, gleichzeitige Nachweis einer groβen Zahl von Schadstoffen in Luft ist möglich, wenn der Aerosolionisationsgasanalysator so modifiziert wird, daβ er als Detektor für die Gaschromatographie geeignet ist. Diese Anforderung erfüllt ein von den Autoren zum Patent angemeldeter Aerosolionisationsdetektor. Der Aufbau, die Wirkungsweise und erste Ergebnisse mit Halogenkohlenwasserstoffen werden beschrieben.     

n-representation infinite algebras

From the viewpoint of higher dimensional Auslander–Reiten theory, we introduce a new class of finite dimensional algebras of global dimension n, which we call n-representation infinite. They are a certain analog of representation infinite hereditary algebras, and we study three important classes of modules: n-preprojective, n-preinjective and n  -regular modules. We observe that their homological behaviour is quite interesting. For instance they provide first examples of algebras having infinite Ext¹${\mathrm{Ext}}^1$-orthogonal families of modules. Moreover we give general constructions of n-representation infinite algebras.     

Synthesis of Polyampholyte Janus‐like Microgels by Coacervation of Reactive Precursors in Precipitation Polymerization

Controlling the distribution of ionizable groups of opposite charge in microgels is an extremely challenging task, which could open new pathways to design a new generation of stimuli‐responsive colloids. Herein, we report a straightforward approach for the synthesis of polyampholyte Janus‐like microgels, where ionizable groups of opposite charge are located on different sides of the colloidal network. This synthesis approach is based on the controlled self‐assembly of growing polyelectrolyte microgel precursors during the precipitation polymerization process. We confirmed the morphology of polyampholyte Janus‐like microgels and demonstrate that they are capable of responding quickly to changes in both pH and temperature in aqueous solutions.     

Nanoscopic Visualization of Soft Matter Using Fluorescent Diarylethene Photoswitches

The in situ imaging of soft matter is of paramount importance for a detailed understanding of functionality on the nanoscopic scale. Although super‐resolution fluorescence microscopy methods with their unprecedented imaging capabilities have revolutionized research in the life sciences, this potential has been far less exploited in materials science. One of the main obstacles for a more universal application of super‐resolved fluorescence microscopy methods is the limitation of readily available suitable dyes to overcome the diffraction limit. Here, we report a novel diarylethene‐based photoswitch with a highly fluorescent closed and a nonfluorescent open form. Its photophysical properties, switching behavior, and high photostability make the dye an ideal candidate for photoactivation localization microscopy (PALM). It is capable of resolving apolar structures with an accuracy far beyond the diffraction limit of optical light in cylindrical micelles formed by amphiphilic block copolymers.     

Mechanism and substrate recognition of human holo ACP synthase

Mammals utilize a single phosphopantetheinyl transferase for the posttranslational modification of at least three different apoproteins: the carrier protein components of cytosolic and mitochondrial fatty acid synthases and the aminoadipate semialdehyde reductase involved in lysine degradation. We determined the crystal structure of the human phosphopantetheinyl transferase, a eukaryotic phosphopantetheinyl transferase characterized, complexed with CoA and Mg(2+), and in ternary complex with CoA and ACP. The involvement of key residues in ligand binding and catalysis was confirmed by mutagenesis and kinetic analysis. Human phosphopantetheinyl transferase exhibits an alpha/beta fold and 2-fold pseudosymmetry similar to the Sfp phosphopantetheinyl transferase from Bacillus subtilis. Although the bound ACP exhibits a typical four-helix structure, its binding is unusual in that it is facilitated predominantly by hydrophobic interactions. A detailed mechanism is proposed describing the substrate binding and catalytic process.     

Studies on the formation and characterization of poly(trimethylene 2,6‐naphthalenedicarboxylate)

Bis‐(3‐hydroxypropyl) 2,6‐naphthalenedicarboxylate (BHPN) was polymerized to poly(trimethylene 2,6‐naphthalenedicarboxylate) (PTN) in the presence of various catalysts. The order of the catalytic reactivity was Sb(III) < Zr(IV) < Sn(IV) < Ti(IV). The influence of temperature and catalyst concentration on the properties of PTN was studied with Ti(IV)butylate as a catalyst. The catalysis with titanium resulted in a yellowish polymer only if the polycondensation temperature exceeded 260 °C. PTN and its monomer BHPN were characterized by infrared spectroscopy. ¹H NMR spectroscopy was employed to determine the quantity of bis‐(3‐hydroxypropyl)ether in PTN. The content of diolether was less than 1 mol %. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 620–629, 2001     

Zur thermischen Zersetzung von TeSeO4 und Te3SeO8 – Koexistenzbeziehungen im ternären System TeO2/SeO2/Bi2SeO5

Thermal Decomposition of TeSeO₄ and Te₃SeO₈ – Phase Relations in the Ternary System TeO₂/SeO₂/Bi₂SeO₅ The saturation decomposition pressure of TeSeO₄ and Te₃SeO₈ were determined in a membran zero manometer. From the equilibrium data are derived the Enthalpies of formation and the Standard Entropies: Data see Inhaltsübersicht. Thus the coexistence ranges in the ternary triangle TeO₂/SeO₂/Bi₂SeO₅ can be determined. Informations about the melting diagram obtained by thermal analysis of the condensed compositions TeO₂/SeO₂.