Wave packet dynamics in triplet states of Na2 attached to helium nanodroplets

The dynamics of vibrational wave packets excited in Na2 dimers in the triplet ground and excited states is investigated by means of helium nanodroplet isolation (HENDI) combined with femtosecond pump-probe spectroscopy. Different pathways in the employed resonant multiphoton ionization scheme are identified. Within the precision of the method, the wave packet dynamics appears to be unperturbed by the helium droplet environment.     

Neue ONS‐Liganden und ihre Zinkkomplexe mit Bezug zum Zinkenzym Alkoholdehydrogenase

New ONS Ligands and their Zinc Complexes with Relation to the Zinc Enzyme Alcoholdehydrogenase By ring opening of dimethyl thiirane with ethanolamine or by Schiff base condensation between salicylic aldehydes and 2‐mercaptoisobutylamine the tridentate ONS ligands H₂MIEA, H₂MIIMP, and H₂MIIMTP were obtained. The former yielded the zinc complex (MIEA)Zn(ethanolamine) ( 1 ) with a trigonal bipyramidal ZnO₂N₂S coordination. The latter two and Zn[N(SiMe₃)₂]₂ yielded the presumably dimeric complexes Zn(MIIMP) and Zn(MIIMTP) ( 2 a , b ). Benzoyl pyridine and phenylhydroxymethylpyridine as bidentate coligands L could be combined with H₂MIIMP in the complexes L · Zn(MIIMP) ( 3 , 4 ) whose ZnO₂N₂S coordination corresponds to that of 1 . Partial hydrolytic degradation led to the unusual trinuclear complex 5 which contains, inter alia, the condensation product of the salicylic aldimine and benzoyl pyridine as a ligand. The complexes obtained and the coordination patterns observed represent new structural analogies with the environment of zinc in the enzyme horse liver alcoholdehydrogenase.     

A stochastic approach to Wilson loops

Wilson loops exp (i A (x) dx) are investigated in two-dimensional Euclidean space-time. The electromagnetic vector potential A is regarded as a generalized random field given by the stochastic partial differential equation A = F where is a first-order differential operator and F is white noise. We give a rigorous definition of Wilson loops and examine the properties of the N-loop Schwinger functions.     

End‐functionalized polylactides using a calcium‐based precatalyst: Synthesis and insights by mass spectrometry

A simple and convenient method for the synthesis of end functionalized polylactides (PLAs) under mild conditions by ring opening polymerization (ROP) in the absence of potentially toxic catalysts is described. Various alcohols were used as initiators in combination with Ca[N(SiMe₃)₂]₂(THF)₂ as the precatalyst in THF at room temperature. Tailored end functionalities were obtained in a controlled fashion. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF‐MS) and electrospray ionization quadrupole time of flight mass spectrometry (ESI‐Q‐ToF‐MS) analysis were performed to investigate the end groups. The results confirmed that the end group fidelity was maintained in the isolated PLAs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 437–448     

Detoxification of VX and Other V‐Type Nerve Agents in Water at 37 °C and pH 7.4 by Substituted Sulfonatocalix[4]arenes

Sulfonatocalix[4]arenes with an appended hydroxamic acid residue can detoxify VX and related V‐type neurotoxic organophosphonates with half‐lives down to 3 min in aqueous buffer at 37 °C and pH 7.4. The detoxification activity is attributed to the millimolar affinity of the calixarene moiety for the positively charged organophosphonates in combination with the correct arrangement of the hydroxamic acid group. The reaction involves phosphonylation of the hydroxamic acid followed by a Lossen rearrangement, thus rendering the mode of action stoichiometric rather than catalytic. Nevertheless, these calixarenes are currently the most efficient low‐molecular‐weight compounds for detoxifying persistent V‐type nerve agents under mild conditions. They thus represent lead structures for novel antidotes that allow treatment of poisonings by these highly toxic chemicals.     

UVB-INDUCED SUPPRESSION OF THE MIXED EPIDERMAL CELL LYMPHOCYTE REACTION IS CRITICALLY DEPENDENT ON IRRADIANCE

The mixed epidermal cell lymphocyte reaction (MECLR) is a commonly used method to study the effects of ultraviolet B (UVB) radiation on the skin immune system. In UVB experiments dosimetry is very important. The influence of irradiance on the MECLR was studied in vitro using Philips FS40 lamps with variable UV intensities. Irradiation of isolated epidermal cells with high irradiance impaired the alloactivating capacity more than irradiation with low irradiance. In vivo, the influence of long-term UVB exposure on the MECLR was studied by treating normal healthy volunteers with suberythemagenic doses of UVB thrice weekly during 4 weeks. The first set of experiments, using low irradiance Sylvania UV-21 F75/85 W lamps, resulted in a decrease of MECLR responses of 83.1%. In the second set of experiments performed a year later, employing an identical protocol except for the use of high irradiance Waldmann UV-21 F85/100 W lamps, an increase of MECLR responses of 99.7% was observed. Volunteers of both sets of experiments received equal doses of UVB. In conclusion, this study shows that in vitro UVB-induced suppression of the MECLR is critically dependent on irradiance and therefore might explain contradictory results described in the literature. The in vivo data suggest that, comparable to the in vitro experiments, irradiance may influence the effects of UVB irradiation in vivo. Further experiments should prove whether this is indeed the case.     

Simulation of Wooden Particle Drying

With regard to future calculations of the combustion inside a packed bed of wooden particles, the drying process of a single wet particle is simulated in the present study. Essentially, conservation equations in spherical coordinates are solved by a finite volume approach for the interior of the single wooden particle. It is shown that a thin transition zone between the wet and the dry area exists during evaporation. The fundamental reasons are pointed out. Furthermore, the high velocity values in the transition zone are explained physically. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

First osmium-catalysed ketamination of alkenes

Conditions for a first oxidative conversion of alkenes into 2-amino ketones are described, which yield racemic products within a direct oxidation pathway and 2-amino ketones with up to 99% enantiomeric excess from the corresponding enantiopure amino alcohols.