Gas-phase Lifetimes of Nucleobase Analogues by Picosecond Pumpionization and Streak Techniques

The picosecond (ps) timescale is relevant for the investigation of many molecular dynamical processes such as fluorescence, nonradiative relaxation, intramolecular vibrational relaxation, molecular rotation and intermolecular energy transfer, to name a few. While investigations of ultrafast (femtosecond) processes of biological molecules, e.g. nucleobases and their analogues in the gas phase are available, there are few investigations on the ps time scale. We have constructed a ps pump-ionization setup and a ps streak camera fluorescence apparatus for the determination of lifetimes of supersonic jet-cooled and isolated molecules and clusters. The ps pump-ionization setup was used to determine the lifetimes of the nucleobase analogue 2-aminopurine (2AP) and of two 2AP˙(H2O)n water cluster isomers with n=1 and 2. Their lifetimes lie between 150 ps and 3 ns and are strongly cluster-size dependent. The ps streak camera setup was used to determine accurate fluorescence lifetimes of the uracil analogue 2-pyridone (2PY), its self-dimer (2PY)2, two isomers of its trimer (2PY)3 and its tetramer (2PY)4, which lie in the 7–12 ns range.

Radar investigations of Apollinaris Mons on Mars: Exploring the origin of the fan deposits

Apollinaris Mons is an isolated volcano on Mars straddling the boundary between the southern highlands and the northern plains. One of its most distinctive features is its massive fan-shaped deposit that extends from a breach on its summit to distances of more than 150 km and drapes its entire southern flank. The composition and formation mechanism of these deposits remains controversial. We investigate the radar properties of the fan deposits (FD) of Apollinaris Mons using low-frequency sounding radar data in combination with high-resolution images and crater-size frequency analysis to constrain their inner shape and bulk composition. Our analysis indicates that the FD attains an irregular thickness and is gradually thinner towards their lateral margins. The crater-size frequency analysis shows that they may have undergone repeated resurfacing, which is suggestive of long-term evolution. Our analysis of Shallow Radar (SHARAD) radargrams traversing different sections of the FD reveals multiple and different subsurface interfaces among the radargrams crossing the thinnest part, which suggests a layered and complex inner shape. Our estimates for the bulk real part of the dielectric constant of the FD ranges from 3 to 5, which is consistent with an icy-silicate mixture or pyroclastic composition. Therefore, we conclude that lahars or pyroclastic flows are the most likely mechanism that created the FD, yet we cannot rule out additional contributions from lava flows. A combination of multiple processes is also possible since the deposits appear to have been modified by fluvial processes at a later stage of their formation.

Functionally Optimized Neuritogenic Farinosone C Analogs: SAR-Study and Investigations on Their Mode of Action

Several natural products derived from entomopathogenic fungi have been shown to initiate neuronal differentiation in the rat pheochromocytoma PC12 cell line. After the successful completion of the total synthesis program, the reduction of structural complexity while retaining biological activity was targeted. In this study, farinosone C served as a lead structure and inspired the preparation of small molecules with reduced complexity, of which several were able to induce neurite outgrowth. This allowed for the elaboration of a detailed structure-activity relationship. Investigations on the mode of action utilizing a computational similarity ensemble approach suggested the involvement of the endocannabinoid system as potential target for our analogs and also led to the discovery of four potent new endocannabinoid transport inhibitors.

Schnidejoch und Lötschenpass. Archäologische Forschungen in den Berner Alpen. Schnidejoch et Lötschenpass. Investigations archéologiques dans les Alpes bernoises.

Archäologie in den Hochalpen: Vom Rückgang der Gletscher sind auch archäologische Objekte betroffen. Über Jahrtausende hinweg haben sie im Eis überdauert, nun kommen sie zum Vorschein. Im Hitzesommer 2003 fand eine Wanderin am Schnidejoch ein fremdartiges Objekt aus Birkenrinde. Es erwies sich als Teil eines 4800 Jahre alten Bogenfutterals. In den Jahren 2004 bis 2011 unternahm der Archäologische Dienst des Kantons Bern über 30 Begehungen der Nordseite und – zusammen mit der Walliser Kantonsarchäologie – auch der Südseite des Schnidejochs. Zahlreiche weitere Funde aus Holz, Leder und Metall konnten geborgen und wissenschaftlich untersucht werden. Einzigartige Funde Zu den spektakulärsten Funden vom Schnidejoch zählt das Bogenfutteral aus Birkenrinde. Weiter stechen aus den rund 900 Funden ein Pfeilbogen, mehrere vollständige Pfeile und Fragmente einer Schale aus Ulmenholz hervor. Es handelt sich dabei um das älteste Holzgefäss der Schweiz. Weitere herausragende Funde sind ein bronzezeitliches Holzgefäss aus Birkenrinde, eine bronzezeitliche Gewandnadel sowie Bekleidung und Schuhe aus Leder. Archéologie dans les Alpes bernoises Le recul des glaciers a aussi un impact sur les découvertes archéologiques. Il fait réapparaître des objets préservés dans les glaces depuis des millénaires. Pendant l’été caniculaire de 2003, une randonneuse a découvert un objet singulier en écorce de bouleau, qui s’est avéré être un morceau de carquois vieux de 4800 ans. De 2004 à 2011, le Service archéologique du canton de Berne s’est rendu plus de trente fois sur le versant nord du Schnidejoch et, en collaboration avec le Service d’archéologie du canton du Valais, sur le versant sud de ce col. De nombreux autres objets en bois, cuir et métal ont pu être mis au jour et étudiés scientifiquement. Des découvertes uniques Le carquois en écorce de bouleau constitue l’une des découvertes les plus sensationnelles du Schnidejoch. Parmi les quelque 900 objets mis au jour figurent un arc, plusieurs flèches complètes et les fragments d’un bol en bois d’orme. Ce bol est le plus ancien récipient en bois de Suisse. D’autres trouvailles spectaculaires ont été faites, notamment un récipient en écorce de bouleau et une épingle à vêtements datant de l’Âge du Bronze ainsi que des vêtements et des chaussures en cuir.

Testing "saintly" authenticity - Investigations on two catacomb saints

The goal of this study was to examine two catacomb saints from Switzerland with conventional radiographic imaging and minimally invasive techniques to test their authenticity.

Towards harmonised procedures in wildlife epidemiological investigations: A serosurvey of infection with Mycobacterium bovis and closely related agents in wild boar (Sus scrofa) in Switzerland

Bovine tuberculosis (bTB) is a (re-)emerging disease in European countries, including Switzerland. This study assesses the seroprevalence of infection with Mycobacterium bovis and closely related agents in wild boar (Sus scrofa) in Switzerland, because wild boar are potential maintenance hosts of these pathogens. The study employs harmonised laboratory methods to facilitate comparison with the situation in other countries. Eighteen out of 743 blood samples tested seropositive (2.4%, CI: 1.5-3.9%) by ELISA, and the results for 61 animals previously assessed using culture and PCR indicated that this serological test was not 100% specific for M. bovis, cross-reacting with M. microti. Nevertheless, serology appears to be an appropriate test methodology in the harmonisation of wild boar testing throughout Europe. In accordance with previous findings, the low seroprevalence found in wild boar suggests wildlife is an unlikely source of the M. bovis infections recently detected in cattle in Switzerland. This finding contrasts with the epidemiological situation pertaining in southern Spain.

Permittivity measurements of porous matter in support of investigations of the surface and interior of 67P/Churyumov-Gerasimenko

Aims. Permittivity measurements on porous samples of volcanic origin have been performed in the 0.05-190 GHz range under laboratory conditions in support of the Rosetta mission to comet 67P/Churyumov-Gerasimenko, specifically with the MIRO radiometric experiment and CONSERT radar experiment. Methods. The samples were split into several subsamples with different size ranges covering a few mu m to 500 mu m. Bulk densities of the subsamples were estimated to be in the 800 to 1500 kg/m(3) range. The porosities were in the range of 48% to 65%. From 50 MHz to 6 GHz and at 190 GHz, permittivity has been determined with a coaxial cell and with a quasi-optical bench, respectively. Results. Without taking into account the volume-scattering effect at 190 GHz, the real part of the permittivity, normalized by the bulk density, is in the range of 2.1 to 2.6. The results suggest that the real part of the permittivity of an ice-free dust mantle covering the nucleus is in the 1.5-2.2 range at 190 GHz. From these values, a lower limit for the absorption length for the millimeter receiver of MIRO has been estimated to be between 0.6 and 2 cm, in agreement with results obtained from MIRO in September 2014. At frequencies of interest for CONSERT experiment, the real part of the permittivity of a suspected ice-free dust mantle should be below 2.2. It may be in the range of 1.2 to 1.7 for the nucleus, in agreement with first CONSERT results, taking into account a mean temperature of 110 K and different values for the dust-to-ice volumetric ratio. Estimations of contributions of the different parameters to the permittivity variation may indicate that the porosity is the main parameter.