Bidentate ligation of magnesium by 1,2-dimethoxyethane in the gas phase

International audienceThe 1:1 Mg[centered ellipsis]1,2-dimethoxyethane (Mg-DXE) complexes are studied experimentally and theoretically. They are generated by a laser ablation source in a supersonic expansion. They are studied spectroscopically by resonance two-photon ionization. Density functional theory/Becke three-dimensional Lee, Yang, and Parr and ab initio calculations using the MOLPRO quantum chemistry package are performed to document their ground and excited states in a series of geometry ranging from monodentate to bidentate ligation of Mg by the O atoms of DXE. An absorption band is observed in the 27 800–30 500 cm−1 range, which, thanks to the calculations, is attributed to the bidentate complex. The structure of the band is discussed in terms of the excitation of electronic states of the complex correlating adiabatically to the 3s3p 1P and 3s4s 1S states of Mg at large separation between Mg and DXE

PSS8 Use of consumer market research panels to generate prevalence and disease burden estimates in data-sparse diseases: a case study in severe Chronic Hand Eczema

Farrando, Jordi;Febles, Maria Dolors ;Henrich, Jordi;Tarrasó, Olga ;Fuertes, J.C.;Pérez, S

Ion-Induced Dipole Interactions and Fragmentation Times : Cα\alpha -Cβ\beta Chromophore Bond Dissociation Channel

The fragmentation times corresponding to the loss of the chromophore (C$\alpha$-- C$\beta$ bond dissociation channel) after photoexcitation at 263 nm have been investigated for several small peptides containing tryptophan or tyrosine. For tryptophan-containing peptides, the aromatic chromophore is lost as an ionic fragment (m/z 130), and the fragmentation time increases with the mass of the neutral fragment. In contrast, for tyrosine-containing peptides the aromatic chromophore is always lost as a neutral fragment (mass = 107 amu) and the fragmentation time is found to be fast (\textless{}20 ns). These different behaviors are explained by the role of the postfragmentation interaction in the complex formed after the C$\alpha$--C$\beta$ bond cleavage

CH abundance gradient in TMC-1

We observed the 9-cm Lambda-doubling lines of CH along the dense filament of TMC-1. The CH column densities were compared with the total H2 column densities derived using the 2MASS NIR data and previously published SCUBA maps and with OH column densities derived using previous observations with Effelsberg. We also modelled the chemical evolution of TMC-1 adopting physical conditions typical of dark clouds using the UMIST Database for Astrochemistry gas-phase reaction network to aid the interpretation of the observed OH/CH abundance ratios. The CH column density has a clear peak in the vicinity of the cyanopolyyne maximum of TMC-1. The fractional CH abundance relative to H2 increases steadily from the northwestern end of the filament where it lies around 1.0e-8, to the southeast where it reaches a value of 2.0e-8. The OH and CH column densities are well correlated, and we obtained OH/CH abundance ratios of ~ 16 - 20. These values are clearly larger than what has been measured recently in diffuse interstellar gas and is likely to be related to C to CO conversion at higher densities. The good correlation between CH and OH can be explained by similar production and destruction pathways. We suggest that the observed CH and OH abundance gradients are mainly due to enhanced abundances in a low-density envelope which becomes more prominent in the southeastern part and seems to continue beyond the dense filament. An extensive envelope probably signifies an early stage of dynamical evolution, and conforms with the detection of a large CH abundance in the southeastern part of the cloud. The implied presence of other simple forms of carbon in the gas phase provides a natural explanation for the observation of "early-type" molecules in this region.Comment: 12 pages, 16 figure

Mental health literacy of depression: gender differences and attitudinal antecedents in a representative British sample

Background Poor mental health literacy and negative attitudes toward individuals with mental health disorders may impede optimal help-seeking for symptoms of mental ill-health. The present study examined the ability to recognize cases of depression as a function of respondent and target gender, as well as individual psychological differences in attitudes toward persons with depression. Methods In a representative British general population survey, the ability to correctly recognize vignettes of depression was assessed among 1,218 adults. Respondents also rated the vignettes along a number of attitudinal dimensions and completed measures of attitudes toward seeking psychological help, psychiatric skepticism, and anti-scientific attitudes. Results There were significant differences in the ability to correctly identify cases of depression as a function of respondent and target gender. Respondents were more likely to indicate that a male vignette did not suffer from a mental health disorder compared to a female vignette, and women were more likely than men to indicate that the male vignette suffered from a mental health disorder. Attitudes toward persons with depression were associated with attitudes toward seeking psychological help, psychiatric skepticism, and anti-scientific attitudes. Conclusion Initiatives that consider the impact of gender stereotypes as well as individual differences may enhance mental health literacy, which in turn is associated with improved help-seeking behaviors for symptoms of mental ill-health

Ab initio study of the spin-orbit coupling between the A and b3Πu electronic states of Na2

Accurate ab initio representations of the ground X and the excited A and b3u electronic states of Na2 are computed along with the transition dipole moment between X and A and the spin-orbit coupling term between A and b3u. These data are used to simulate an experiment involving these three states to investigate the effect of spin-orbit coupling on the dynamics of a wave packet oscillating on the A stat

Photodepletion measurements of the Zrcdots, three dots, centeredF–CH3 van der Waals complex

International audienceWe report here on the observation of the Zrcdots, three dots, centeredF–CH3 van der Waals complexes in a laser ablation – supersonic expansion source. The complexes are studied using a combination of laser spectroscopy and time-of-flight mass spectrometric detection. We show that the (1:1) Zrcdots, three dots, centeredF–CH3 complex is stable in the ground electronic state. By a ground state photodepletion method, we have characterized one of the transitions in the 600–700 nm region as correlating asymptotically with the View the MathML source atomic transition from the ground state of free Zr atom. The corresponding excited state of the Zrcdots, three dots, centeredF–CH3 complex is reactive with activation of the C–F bond

Reactions of laser-ablated zirconium atoms within a supersonic expansion: insertion versus radical mechanism.

In a laser ablation type microreactor followed by supersonic expansion, zirconium atoms have been reacted with methyl fluoride, CH(3)F (MeF), and mixtures of MeF and dimethylether, CH(3)-O-CH(3) (DME) seeded in He. With both mixtures, only a number of simple fluorinated products are formed, and they have been identified by one-photon ionization. All products can be linked to radical reactions either with F atoms, CH(3), or ZrF(1, 2, 3) radicals. No insertion products of the Grignard reagent type, F -Zr-CH(3) could be identified with or in the absence of DME. On the other hand, evidence has been found for the presence of organometallic compounds of the type ZrC(2)H(n=2, 4, 6), which could result from radical attack. Thus, even in conditions where intense solvation is at work, induced by clustering with polar DME molecules, which can act as stabilizing agents, a direct insertion mechanism into the C-F bond involving barrier suppression is not at work in our conditions. The reactivity due to radicals is very effective in this type of reactor, and the products that are efficiently formed can be quickly stabilized in the expansion. The radical attack supersedes, in the case of zirconium solvated by DME, the metastable mechanism with Zr(4d)(3)(5s)(1), that is certainly energetically impossible in the absence of strong reaction barrier suppression by a solvent. High level ab initio calculations performed at the CASPT2 level of theory are used for characterizing the electronic and geometric structure of the inserted products. They also reveal striking features of the reaction mechanism that support the absence of observation of inserted products within solvated clusters of zirconium.Journal Articleinfo:eu-repo/semantics/publishe

Photodissociation Spectroscopy of Cold Protonated Synephrine: Surprising Differences Between IR-UV Hole-Burning and IR Photodissociation Spectroscopy of the O-H and N-H modes

International audienceWe report the UV and IR photofragmentation spectroscopies of protonated synephrine in a cryogenically cooled Paul trap. Single (UV or IR) and double (UV-UV and IR-UV) resonance spectroscopies have been performed and compared to quantum chemistry calculations, allowing the assignment of the lowest-energy conformer with two rotamers depending on the orientation of the phenol hydroxyl (OH) group. The IR-UV Hole Burning spectrum exhibits the four expected vibrational modes in the 3 µm region, i.e. the phenol OH, C-OH and two NH2 + stretches. The striking difference is that among these modes, only the free phenol OH mode is active through IRPD. The protonated amino group acts as a proton donor in the internal hydrogen bond and displays large frequency shifts upon isomerization expected during the multiphoton absorption process, leading to the so-called IRMPD transparency. More interestingly, while the C-OH is a proton acceptor group with moderate frequency shift for the different conformations, this mode is still inactive through IRPD.