Die Nielsenäquivalenzklassen der metabelsch gemachten Torusknotengruppen

Ohne Zusammenfassung     

Strahlungseigenschaften von Anordnungen aus Josephsonverbindungen

Radiation Properties of Josephson-Junction Arrays Starting from the basic equations of the interaction of a statistical array of Josephson junctions with a single cavity mode the creation of the superradiant state is discussed within the frame of an adiabatic approximation. The condition of synchronisation is presented. Essentially it compares the number of Josephson radiators and the coupling intensity with the Maxwell field on the one hand with the mean square fluctuation of the impressed Josephson frequencies and the cavity damping on the other hand.     

Book reviews

Ohne Zusammenfassung

---

Book reviews

     

Short‐circuit current improvement of CuGaSe2 solar cells with a ZnS/(Zn,Mg)O buffer combination

CuGaSe₂ (CGS) thin‐film solar cells were prepared with an in‐line co‐evaporation process and the established buffer combination CdS/i‐ZnO was replaced by ZnS/(Zn,Mg)O. We obtained functional CGS solar cells with a strong gain in the short‐circuit current density as compared to the CdS/i‐ZnO buffer reference cells. The enhanced current density is a result of improved transmission in the wavelength region between 330 nm and 550 nm of the ZnS/(Zn,Mg)O buffer combination as compared to CdS/i‐ZnO. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Sequential Hydrogen Tunneling in o-Tolylmethylene

o-Tolylmethylene 1 is a metastable triplet carbene that rearranges to o-xylylene 2 even at temperatures as low as 2.7 K via [1,4] H atom tunneling. Electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopical techniques were used to identify two conformers of 1 (anti and syn) in noble gas matrices and in frozen organic solutions. Conformer-specific kinetic measurements revealed that the rate constants for the rearrangements of the anti and syn conformers of 1 are very similar. However, the orbital alignment in the syn conformer is less favorable for the hydrogen transfer reaction than the orbital configuration in the anti conformer. Our spectroscopic and quantum chemical investigations indicate that anti 1 and syn 1 rapidly interconvert via efficient quantum tunneling forming a rotational pre-equilibrium. The subsequent second tunneling reaction, the [1,4] H migration from anti 1 to 2 , is rate-limiting for the formation of 2 . We here present an efficient strategy for the study of such tunneling equilibria.     

The 1,2,3-tridehydrobenzene triradical: 2B or not 2B? The answer is 2A!

The molecular and electronic structure of 1,2,3-tridehydrobenzene was investigated by a variety of computational methods. The two lowest electronic states of the triradical are the (2)B(2) and (2)A(1) doublet states characterized by different interactions of the unpaired electrons. Vertically, the two states are well separated in energy-by 4.9 and 1.4 eV, respectively. However, due to different bonding patterns, their equilibrium structures are very different and, adiabatically, the two states are nearly degenerate. The adiabatic energy gap between the (2)B(2) and (2)A(1) states is estimated to be 0.7-2.1 kcal/mol, in favor of the (2)A(1) state. Harmonic vibrational frequencies and anharmonic corrections were calculated for both states. Comparison with the three experimentally observed IR transitions supports the assignment of the (2)A(1) ground state for the triradical with a weakly bonding distance of 1.67-1.69 A between the meta radical centers.     

Formamide dimers: a computational and matrix isolation study

The dimerization of formamide (FMA) has been investigated by matrix isolation spectroscopy, static ab initio calculations, and ab initio molecular dynamics (AIMD) simulations. Comparison of the experimental matrix IR spectra with the ab initio calculations reveals that two types of dimers A and C are predominantly formed, with two and one strong NH...O hydrogen bonds, respectively. This is in accordance with previously published experiments. In addition, there is also experimental evidence for the formation of the thermally labile dimer B after deposition of high concentrations of FMA in solid xenon. The AIMD simulations of the aggregation process show that in all cases dimer C is initially formed, but rearrangement to the more stable doubly hydrogen-bonded structures A or B occurs for a fraction of collisions on the sub-picosecond time scale.     

Phenothiazinium derivatives for pathogen inactivation in blood products

Phenothiazine-based photosensitisers have been employed in photoantimicrobial research for nearly 80 years, both as lead and novel compounds. However, the main structural variations have mainly involved the auxochromic side chains and little has been reported concerning either peripheral substitution or structures with chromophores other than those of the phenothiazinium or annelated benzo[a]phenothiazinium type. In terms of application, the phenothiazinium series has featured commonly in cytology and cytopathology, as well as in haematological staining. The current work covers the evolution of improved photosensitisers based on the phenothiazine ring system, with particular reference to the field of pathogen inactivation, and the structural alteration of lead compounds such as methylene blue and Nile blue to yield improved photosensitisers for this important aspect of blood product safety.