Gas-phase electronic spectroscopy of cold molecular cations of astrophysical interest

This thesis, which is the core of a project started in 2010, is aimed at developing an experimental technique suitable for the measurement of the electronic spectra of cold, large, gas-phase molecular cations. Two approaches were initially targeted: photoinduced charge transfer and photodissociation of ionic complexes with He atoms. Since the latter is both the simplest of the two and a universal method, most efforts would be put toward its implementation. The project included the design and assembly of a new apparatus, a tandem mass spectrometer centered on a 22-pole trap. When this thesis was initiated, the apparatus was partially assembled and as a first major task, the assembly had to be completed and characterized. For this reason, chapters 4 and 6 treat some aspects of the obtained electronic spectra that are not novel, but which are part of the characterization of the apparatus and the method. Chapter 2 presents the several types of spectroscopic features that prove that large molecules do form interstellar and circumstellar media. Observations and laboratory experiments are used to put constraints on the responsible molecules. The experimental apparatus and the procedure to obtain the electronic spectra are detailed in Chapter 3, and some aspects of the characterization of the apparatus are presented in Chapter 4. The electronic spectra of several gas-phase protonated H+PAHs at a rotational temperature of 10K constituted the first results of this apparatus and are presented in Chapter 5. These molecules were not studied with one of the two targeted methods, however, they were the firsts spectra obtained in the gas phase for such large cations for astronomical comparison. Also studying these five H+PAHs allowed us to get a better handling of the setup and to solve experimental issues, as shown in Chapter 6. Chapter 7 presents the first results obtained using one of the targetted methods, the electronic spectra of coronene+ and corannulene+, extrapolated from the photodissociation (PD) spectra of their complexes with He. Chapter 8 addresses the case of protonated C60, a project which has merely been started. Finally, Chapter 9 concludes and gives an outlook about the general challenge of identifying large molecules in the ISM and CSEs

Electronic Spectra of Corannulenic Cations and Neutrals in Neon Matrices and Protonated Corannulene in the Gas Phase at 15 K

Three absorption systems starting at 624.1, 601.2, and 590.0 nm were detected in a 6 K neon matrix following deposition of mass selected m/z = 250 ions produced from corannulene vapour in a hot cathode ion source. The two latter systems were also observed after deposition of neutral corannulene in solid neon with concomitant bombardment of the matrix with argon ions. The features in the absorption spectrum are assigned to the 42A′′  ←  X2A′′ transition of cylobutadieno-benzo[ghi]fluoranthene cation and to the 32A′  ←  X2A′′ and 32A′′  ←  X2A′ transitions of two Jahn-Teller structures of bowl-shaped corannulene cations, respectively. The assignment is based on excitation energies calculated with the SAC-CI and CASPT2 methods. The electronic absorption spectrum of protonated corannulene has onsets at 515.1 and 398.8 nm in a neon matrix, following deposition of a mass-selected beam produced by reactions of corannulene with EtOH2+. The absorptions are assigned, on the basis of theoretical predictions, to the 3,41A  ←  X1A transitions. The electronic spectrum was also recorded in the gas phase using a resonant multiphoton fragmentation technique in an ion trap at vibrational and rotational temperatures of 15 K. The 3,41A  ←  X1A transitions are observed with origin bands at 521 ± 1 nm and 396.4 ± 0.1 nm. The 31A excited electronic state indicates fast internal conversion of ≈ 5 fs, while the 41A state has a lifetime of ≈ 0.2 ps. A distinct vibrational pattern is discernible in the 41A  ←  X1A transition

Viral Gastroenteritis Outbreaks in Europe, 1995–2000

To gain understanding of surveillance and epidemiology of viral gastroenteritis outbreaks in Europe, we compiled data from 10 surveillance systems in the Foodborne Viruses in Europe network. Established surveillance systems found Norovirus to be responsible for >85% (N=3,714) of all nonbacterial outbreaks of gastroenteritis reported from 1995 to 2000. However, the absolute number and population-based rates of viral gastroenteritis outbreaks differed markedly among European surveillance systems. A wide range of estimates of the importance of foodborne transmission were also found. We review these differences within the context of the sources of outbreak surveillance information, clinical definitions, and structures of the outbreak surveillance systems

A global genomic analysis of Salmonella Concord reveals lineages with high antimicrobial resistance in Ethiopia.

Antimicrobial resistant Salmonella enterica serovar Concord (S. Concord) is known to cause severe gastrointestinal and bloodstream infections in patients from Ethiopia and Ethiopian adoptees, and occasional records exist of S. Concord linked to other countries. The evolution and geographical distribution of S. Concord remained unclear. Here, we provide a genomic overview of the population structure and antimicrobial resistance (AMR) of S. Concord by analysing genomes from 284 historical and contemporary isolates obtained between 1944 and 2022 across the globe. We demonstrate that S. Concord is a polyphyletic serovar distributed among three Salmonella super-lineages. Super-lineage A is composed of eight S. Concord lineages, of which four are associated with multiple countries and low levels of AMR. Other lineages are restricted to Ethiopia and horizontally acquired resistance to most antimicrobials used for treating invasive Salmonella infections in low- and middle-income countries. By reconstructing complete genomes for 10 representative strains, we demonstrate the presence of AMR markers integrated in structurally diverse IncHI2 and IncA/C2 plasmids, and/or the chromosome. Molecular surveillance of pathogens such as S. Concord supports the understanding of AMR and the multi-sector response to the global AMR threat. This study provides a comprehensive baseline data set essential for future molecular surveillance

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Burstlike first-order transformation studied by semi-adiabatic relaxation calorimetry

International audienceThis paper reports on a mode of analysis of semi-adiabatic relaxation data allowing to account for exotic phenomena sometimes observed in first-order transitions. The principal interest is to get a detailed characterization of the latent heat while using the same experimental configuration as that employed for accurate heat capacity measurements outside the transition. Special attention is paid to the recalescence/antirecalescence effects as well as to the existence of spikes in the time-dependent exchange of latent heat. The present approach —based on the notion of “power of latent heat”— is shown to be consistent with differential scanning calorimetry, magnetization measurements and the usual analysis in terms of heat capacity. The study is carried out on a LaFe10.77Si1.23Co0.28 compound which belongs to one of the most promising families of giant magnetocaloric materials

Burstlike first-order transformation studied by semi-adiabatic relaxation calorimetry

International audienceThis paper reports on a mode of analysis of semi-adiabatic relaxation data allowing to account for exotic phenomena sometimes observed in first-order transitions. The principal interest is to get a detailed characterization of the latent heat while using the same experimental configuration as that employed for accurate heat capacity measurements outside the transition. Special attention is paid to the recalescence/antirecalescence effects as well as to the existence of spikes in the time-dependent exchange of latent heat. The present approach —based on the notion of “power of latent heat”— is shown to be consistent with differential scanning calorimetry, magnetization measurements and the usual analysis in terms of heat capacity. The study is carried out on a LaFe10.77Si1.23Co0.28 compound which belongs to one of the most promising families of giant magnetocaloric materials

Recyclable heterogeneous palladium catalysts in pure water: sustainable developments in Suzuki, Heck, Sonogashira and Tsuji-Trost reactions

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Electronic Spectra of Protonated Fluoranthene in a Neon Matrix and Gas Phase at 10 K

Four electronic systems with origin bands at 759.5, 559.3, 476.3, and 385.5 nm are detected in a 6 K neon matrix following deposition of mass-selected protonated fluoranthene C16H11+ produced from a reaction of neutral vapor and ethanol in a hot-cathode ion source. Two cationic isomers are identified as the carriers of these band systems. The 559.3, 476.3, and 385.5 nm absorptions are assigned to 4,3,2 1A′ ← X 1A′ transitions of isomer E+ (γ−) and the 2 1A′ ← X 1A′ system at 759.5 nm is of isomer C+ (α−) of protonated fluoranthene on the basis of theoretical predictions. The electronic spectrum of E+ was also recorded in the gas phase using a resonant 1 + 1 two-photon excitation–dissociation technique in an ion trap at vibrational and rotational temperatures of 10 K. The 3,2 1A′ ← X 1A′ transitions have origin band maxima at 558.28 ± 0.01 and 474.92 ± 0.01 nm. Both the 2 1A′ and 3 1A′ excited states have a distinct vibrational pattern with lifetimes on the order of 1 ps