Integrated Calendar

Mass-spectrometric investigations are a powerful tool to probe chemical reactions in a highly idealized environment. Mass selection allows producing a particle beam of the desired ionic species in high purity, and collisions with neutral reagents permit to probe chemical reactions as well as dissociation processes. In this seminar, mechanistic investigations of inter- and intramolecular C–H bond activation reactions employing cationic [M(X)(bipy)]+ (M = Ni, Pd, Pt; X = CH3, Cl; bipy = 2,2'-bipyridine) are presented. Particularly, the collision-induced dissociation of [Pt(CH3)(bipy)]+ gives rise to the formation of "rollover"-cyclometalated [Pt(bipy – H)]+ via rotation of one of the pyridyl rings followed by C–H bond activation of the turned ring to produce CH4 as a neutral fragment. While "rollover"-cyclometalated complexes are known also in the condensed phase, their reactivity has hardly been studied. In this respect, gas-phase studies have demonstrated that this particular kind of cyclometalated species exhibits a rich chemistry. As an example, studies on the dehydrogenation of small alkanes at [Pt(bipy – H)]+ are presented in this seminar.

If integrons are mainly known as the genetic agents responsible for the capture and spread of antibiotic resistance determinants among Gram-negative pathogens, they are also are found in the genomes of hundreds of environmental bacterial species. In particular, all Vibrio genomes sequenced so far have been found to carry a sedentary integron platform. We reported a direct link between this gene capture system and the SOS response, a regulatory network induced by DNA damage, which is known to promote genetic variation in time of stress. We showed that LexA controls the expression of most integron integrases and that SOS induction increases the recombination of gene cassettes. We have now found that horizontal gene transfer mechanisms (conjugation and natural transformation) and most antibiotics induce the SOS response in Vibrio cholerae, and certainly in most Vibrio species. This coupling enhances the potential for cassette swapping and capture in cells undergoing stress, while freezing the cassette arrangement in steady environments. We will discuss how these discoveries sponsors integrons as integrated adaptive systems for these bacteria.

TBD

Lead nuclei, accelerated and collided by the LHC recreate the state of matter which existed when the Universe was few microseconds old. This matter, composed of quark and gluons, is hundred thousand times hotter than the core of the Sun and acts as a fluid whose viscosity is lower than of a super-cold helium. Expanding and cooling down, this matter converts back into hadrons, emitting dozens of thousands of particles. Understanding the nature of such matter and its evolution represents a challenge both to the theory and experiment. The ATLAS detector provides an excellent opportunity to perform complex and detailed studies of this fascinating object, measuring its bulk propertied and its response to penetrating probes. Study of particle correlations: differential and integrated anisotropic flow, and event-by-event fluctuations tell us about the initial geometry of the interactions and help to understand how this geometry evolves into the final state. The new ATLAS results directly show that the geometric shape of the medium affects the jets emerging from it. The new ATLAS studies of the jets suppression and jet fragmentation are essential to understand how the energetic partons are interacting with the medium. Recent high precision measurements of the boson production in heavy ion collisions and first results on the boson-jet correlations are important steps towards quantitative understanding of the parton energy loss mechanism.