Acetylene Derivatives of Cationic Diazaoxatriangulenes and Diaza [4]Helicenes - Access to Red Emitters and Planar Chiral Stereochemical Traits

Cationic triangulenes, and related helicenes, constitute a rich class of dyes and fluorophores, usually absorbing and emitting light at low energy, in the orange to red domains. Recently, to broaden the scope of applications, regioselective late-stage functionalizations on these core moieties have been developed. For instance, with the introduction of electron-donating groups (EDGs), important bathochromic shifts are observed pushing absorptions towards or in the near-infrared (NIR) spectral domain while emissive properties disappear essentially completely. Herein, to upset this drawback, acetylene derivatives of cationic diazaoxa triangulenes (DAOTA) and [4]helicenes are prepared (16 examples). Contrary to other EDG-functionalized derivatives, C≡C− functionalized products remain broadly fluorescent, with red-shifted absorptions (Δλ_abs up to 25 nm) and emissions (Δλ_em up to 73 nm, Φ_PL up to 51 %). Quite interestingly, a general dynamic stereoisomerism phenomenon is evidenced for the compounds derived from achiral DAOTA cores. At low temperature in ¹H NMR spectroscopy (218 K), N−CH₂ protons become diastereotopic with chemical shifts differences (Δδ) as high as +1.64 ppm. The signal coalescence occurs around 273 K with a barrier of ∼12 kcal mol⁻¹. This phenomenon is due to planar chiral conformations (S_p and R_p configurations), induced by the geometry of the alkyl (n-propyl) side-chains next to the acetylenic substituents. Ion pairing studies with Δ-TRISPHAT anion not only confirm the occurrence of the chiral conformations but evidence a moderate but definite asymmetric induction from the chiral anion onto the cations. Finally, DFT calculations offer a valuable insight on the geometries, the corresponding stereodynamics and also on the very large difference in NMR for some of the diastereotopic protons.     

Comprehensive Characterization of Shredded Lithium-Ion Battery Recycling Material

Herein we report on an analytical study of dry-shredded lithium-ion battery (LIB) materials with unknown composition. Samples from an industrial recycling process were analyzed concerning the elemental composition and (organic) compound speciation. Deep understanding of the base material for LIB recycling was obtained by identification and analysis of transition metal stoichiometry, current collector metals, base electrolyte and electrolyte additive residues, aging marker molecules and polymer binder fingerprints. For reversed engineering purposes, the main electrode and electrolyte chemistries were traced back to pristine materials. Furthermore, possible lifetime application and accompanied aging was evaluated based on target analysis on characteristic molecules described in literature. With this, the reported analytics provided precious information for value estimation of the undefined spent batteries and enabled tailored recycling process deliberations. The comprehensive feedstock characterization shown in this work paves the way for targeted process control in LIB recycling processes.     

Radical Reactivity of the Biradical [⋅P(μ-NTer)2P⋅] and Isolation of a Persistent Phosphorus-Cantered Monoradical [⋅P(μ-NTer)2P-Et]

The activation of C−Br bonds in various bromoalkanes by the biradical [⋅P(μ-NTer)₂P⋅] ( 1 ) (Ter=2,6-bis-(2,4,6-trimethylphenyl)-phenyl) is reported, yielding trans-addition products of the type [Br−P(μ-NTer)₂P−R] ( 2 ), so-called 1,3-substituted cyclo-1,3-diphospha-2,4-diazanes. This addition reaction, which represents a new easy approach to asymmetrically substituted cyclo-1,3-diphospha-2,4-diazanes, was investigated mechanistically by different spectroscopic methods (NMR, EPR, IR, Raman); the results suggested a stepwise radical reaction mechanism, as evidenced by the in-situ detection of the phosphorus-centered monoradical [⋅P(μ-NTer)₂P-R].< To provide further evidence for the radical mechanism, [⋅P(μ-NTer)₂P-Et] ( 3Et ⋅) was synthesized directly by reduction of the bromoethane addition product [Br-P(μ-NTer)₂P-Et] ( 2 a ) with magnesium, resulting in the formation of the persistent phosphorus-centered monoradical [⋅P(μ-NTer)₂P-Et], which could be isolated and fully characterized, including single-crystal X-ray diffraction. Comparison of the EPR spectrum of the radical intermediate in the addition reaction with that of the synthesized new [⋅P(μ-NTer)₂P-Et] radical clearly proves the existence of radicals over the course of the reaction of biradical [⋅P(μ-NTer)₂P⋅] ( 1 ) with bromoethane. Extensive DFT and coupled cluster calculations corroborate the experimental data for a radical mechanism in the reaction of biradical [⋅P(μ-NTer)₂P⋅] with EtBr. In the field of hetero-cyclobutane-1,3-diyls, the demonstration of a stepwise radical reaction represents a new aspect and closes the gap between P-centered biradicals and P-centered monoradicals in terms of radical reactivity.     

On the organization of hemicelluloses in the wood cell wall

Cellulose - The structural arrangement of the polymers in the cell wall of wood has still not been fully established. This relates specifically to the role of the two hemicelluloses, glucomannan...     

Einige Bemerkungen zu einer allgemeinen Klasse von Stoffgesetzen für große elasto-plastische Formänderungen

Übersicht Unter den üblichen Voraussetzungen der phänomenologischen Plastizitätstheorie großer Formänderungen werden die Formulierungsbedingungen und einige spezielle Formulierungsmöglichkeiten für Fließbedingungen einer ziemlich allgemeinen Klasse erörtert, die isotrope und anisotrope Verfestigung umfaßt. Es schließen sich einige Bemerkungen zur Belastungsbedingung und zum zugehörigen Formänderungsgesetz an.

---

Summary The restrictions for the formulation of yield conditions belonging to a rather general class comprehending isotropic and anisotropic hardening and some special cases are discussed under the usual assumptions of the phenomenological theory of plasticity at large deformations. Connected with this some remarks are following on the loading condition and the related stress-strain relations.

---

---

Herrn Professor Dr. Dr. h. c. U. Wegner zum 70. Geburtstag.     

Mikroskopische Untersuchung der Tropfenkondensation

The heat transfer during dropwise condensation can be calculated from the distribution function of the drop sizes and the growth function of single drops. Both functions are obtained from motion pictures with high magnification. The motion pictures are taken during condensation of steam of about 25 °C on vertical copper and brass surfaces. A simple approximation for the growth function is given which agrees with the exact solution ofUmur andGriffith [8] within the limits of about 1%.     

Deformation und Stabilität windbeanspruchter Kühlturmschalen

Übersicht Nach der Formulierung des Deformations- und des Stabilitätsproblems auf der Grundlage ursprünglich nicht-konformer, dreiecksförmiger, gekrümmter finiter Elemente wird zunächst das Deformationsproblem für eine ausgeführte Kühlturmschale numerisch gelöst. Die nachfolgende Stabilitätsanalyse dieser Kühlturmschale zeigt gute Übereinstimmung der mittels der Methode der finiten Elemente errechneten Beulsicherheit mit dem aufgrund des Munganschen Beulkriteriums erhaltenen Kleinstwert der Beulsicherheit.

---

Summary Following the formulation of the deformation and stability problem on the basis of originally non-conforming triangular curved finite elements with the help of a variational principle with subsidiary conditions, the deformation problem is solved numerically for an existing cooling tower shell. The subsequent stability analysis of this cooling tower shell shows relatively good agreement of the buckling safety computed by means of the finite element method and the minimum of buckling safety obtained with the help of Mungan's stability criterion.

---

---

Diese Arbeit wurde mit Unterstützung der Cooling Tower Division von Zurn Industries, Tampa, Florida, USA, begonnen und mit Unterstützung Seitens des Fonds zur Förderung der wissenschaftlichen Forschung, Wien, zu Ende geführt. Beiden Sponsoren Sei an dieser Stelle aufrichtig gedankt. Der erstgenannte Autor ist darüber hinaus der Max Kade Foundation, New York, N. Y., für die Finanzierung Seines Studienaufenthaltes an der Cornell University, Ithaca, N. Y., im Rahmen dessen er mit der Thematik dieses Aufsatzes konfrontiert wurde, zu Dank verpflichtet. Aus demselben Grund sagt der dritte Autor für ein NATO Fellowship Dank.     

Nichtisotherme ebene Freistrahlen unter Schwerkrafteinfluß

Higher-order boundary layer theory is used to study the behaviour of nonisothermal laminar and turbulent free jet flows. In addition to the Prandtl boundary layer equations, an equation is used to describe the equilibrium of forces normal to the flow direction. This equilibrium exists between the buoyancy forces caused by gravity and the centrifugal forces resulting from the curvature in the flow. The proper selection of reference values permits the characteristics of the jet flow to be expressed as universal functions in which only the initial jet orientation and the Prandtl number in the case of laminar flow are input parameters. When the volume flow is given in addition to the momentum and thermal energy, the characteristic parameter are the Archimedes number for turbulent flow and the modified Archimedes number for laminar flow. The jet flow is calculated using an integral method in which the eddy viscosity and the turbulent Prandtl number are given as functions of the local Archimedes number. Comparison of experimental data from the literature and from our laboratory on nonisothermal free jets with the theoretical results, show satisfactory agreement. The universal diagrams given in the paper are valid forall plane laminar (Pr=0.7) and turbulent nonisothermal jets.     

Schnelle Berechnung der mittleren Temperaturdifferenz in luftgekühlten Kreuzstromwärmeaustauschern

Zusammenfassung Es wird eine bekannte, explizite Näherungsgleichung mit zehn neuen Sätzen von jeweils sechzehn empirischen Konstanten vorgestellt zur schnellen Berechnung der mittleren Temperaturdifferenz von nunmehr insgesamt achtzehn Kreuzstromführungen. Die mittlere Temperaturdifferenz wird aus der dimensionslosen Abkühlung des Prozeßstromes und der Zahl der Übergangseinheiten auf der Luftseite berechnet.

---

Fast calculation of mean temperature difference in air-cooled cross-flow heat exchangers

A known approximate explicit equation together with ten new sets of sixteen empirical coefficients is presented for the fast calculation of the mean temperature difference of by now all together eighteen crossflow arrangements. The mean temperature difference is calculated from the effectiveness of the process stream and the number of transfer units on the air side.

---

Bezeichnungen b_{i, K} Konstanten in Gl. (6) - c_p spezifische Wärmekapazität der Luft bei Konstanten Druck - Wärmekapazitätsstrom der Luft - F Austauschfläche, Fläche - f mittlerer absoluter Fehler von r - i, k Exponenten und Summenzähler in Gl. (6) - K Wärmedurchgangskoeffizient - m, n Maximalwerte von i bzw. k - p, q dimensionslose Temperaturänderungen beider Fluide, definiert durch Gln. (2) und (3) - r dimensionslose mittlere Temperaturdifferenz, definiert durch Gl. (1) - s Zahl der Übergangseinheiten (NTU) auf der Luftseite, definiert durch Gl. (4) - T Temperatur des Prozeßstroms - w Anströmgeschwindigkeit der Luft - z Zahl der Punkte - endliche Differenz - Dichte der Luft Indices I eine Rohrreihe - 1, 2 Eintritt, Austritt - a Anströmquerschnitt - Ge Gegenstrom - Gl Gleichstrom - M Mittelwert - max Maximalwert (nicht Mittelwert) Herrn Prof. em. Dr.-Ing. Dr.-Ing. E. h. H. Hausen zur Vollendung seines 85. Lebensjahres