Calculations of current densities for neutral and doubly charged persubstituted benzenes using effective core potentials

Magnetically induced current density susceptibilities and ring-current strengths have been calculated for neutral and doubly charged persubstituted benzenes C6X6 and C6X62+ with X = F, Cl, Br, I, At, SeH, SeMe, TeH, TeMe, and SbH2. The current densities have been calculated using the gauge-including magnetically induced current (GIMIC) method, which has been interfaced to the Gaussian electronic structure code rendering current density calculations using effective core potentials (ECP) feasible. Relativistic effects on the ring-current strengths have been assessed by employing ECP calculations of the current densities. Comparison of the ring-current strengths obtained in calculations on C6At6 and C6At62+ using relativistic and non-relativistic ECPs show that scalar relativistic effects have only a small influence on the ring-current strengths. Comparisons of the ring-current strengths and ring-current profiles show that the C6I62+, C6At62+, C-6(SeH)(6)(2+), C-6(SeMe)(6)(2+), C-6(TeH)(6)(2+), C-6(TeMe)(6)(2+), and C-6(SbH2)(6)(2+) dications are doubly aromatic sustaining spatially separated ring currents in the carbon ring and in the exterior of the molecule. The C6I6+ radical cation is also found to be doubly aromatic with a weaker ring current than obtained for the dication.Peer reviewe

Methyl-laudanosine: A new pharmacological tool to investigate the function of small-conductance Ca2+-activated K+ channels

ABSTRACT Small-conductance Ca 2ϩ -activated K ϩ channels (SK channels) underlie the prolonged postspike afterhyperpolarization (AHP) observed in many central neurons and play an important role in modulating neuronal activity. However, a lack of specific and reversible blockers of these channels hampers their study in various experimental conditions. Because previous work has shown that bicuculline salts block these channels, we examined whether related alkaloids, namely laudanosine quaternary derivatives, would produce similar effects. Intracellular recordings were performed on rat midbrain dopaminergic neurons and hippocampus CA1 pyramidal cells. Binding experiments were performed on rat cerebral cortex membranes. Laudanosine, methyl-laudanosine, and ethyl-laudanosine blocked the apamin-sensitive AHP of dopaminergic neurons with mean IC 50 values of 152, 15, and 47 M, respectively. The benzyl and butyl derivatives were less potent. Methyl-laudanosine had no effect on the I h current, action potential parameters, or membrane resistance of dopaminergic cells, or on the decrease in input resistance induced by muscimol, indicating a lack of antagonism at GABA A receptors. Interestingly, 100 M methyllaudanosine induced a significant increase in spiking frequency of dopaminergic neurons but not of CA1 pyramidal cells, suggesting the possibility of regional selectivity. Binding experiments on laudanosine derivatives were in good agreement with electrophysiological data. Moreover, methyl-laudanosine has no affinity for voltage-gated potassium channels, and its affinity for SK channels (IC 50 4 M) is superior to its affinity for muscarinic (IC 50 114 M) and neuronal nicotinic (IC 50 Ն367 M) receptors . Methyl-laudanosine may be a valuable pharmacological tool to investigate the role of SK channels in various experimental models. Other than neurotransmitter receptors and transporters, ion channels constitute an attractive target to develop new drugs that will be active on the central nervous system. Currently, the only ion channel that is well established as a central nervous system target is the voltage-gated Na ϩ channel, which is blocked by antiepileptic drugs such as phenytoin, carbamazepine, and lamotrigine Evidence suggests that SK-channel modulation may be interesting in a range of central nervous system disorders, This work was supported in part by Grant 3.4525.98 from the National Fund for Scientific Research (Brussels, Belgium). This work has been presented in meeting abstract form: Scuvée-Moreau J, Liégeois JF, and Seutin V (2002) Effect of laudanosine derivatives on the apamin-sensitive afterhyperpolarization of rat dopaminergic neurons-identification of methyl-laudanosine as a new specific blocker (Abstract). Fundam Clin Pharmacol 16:67

Bulletins météo télévisés et vulgarisation scientifique – Analyse critique des données (non-) disponibles

Les bulletins météo sont, du point du vue linguistique et discursif, des textes très intéressants car ils transmettent une explication scientifique relativement compliquée à la population et représentent donc une forme de vulgarisation scientifique ou de communication scientifique externe. Plusieurs questions apparaissent alors : Quelles différences apparaissent entre les bulletins météo destinés aux scientifiques et ceux destinés au grand public ? D’où proviennent les données scientifiques – ou les structures linguistiques scientifiques – remplacées par des modes d’expression plus expressifs ou plus subjectifs ?... Le projet de recherche « Analyse textuelle et modélisation syntactico-sémantique de bulletins météorologiques à partir de schémas lexicogrammaticaux » s’intéresse à ces questions, avec une attention particulière pour l’évolution linguistique de ces textes pendant la seconde moitié du siècle dernier. Néanmoins, il est très difficile de collecter ces bulletins télévisés. Pendant le siècle dernier, beaucoup de bulletins météo télévisés ont été perdus parce que les archives n’étaient pas encore préparées au recollement des données vidéographiques et, ensuite, parce que la conservation de ces données ne semblait pas si importante que la conservation du journal télévisé ou de données et graphiques météorologiques.Par conséquent, les archives ne renferment souvent qu’une collection fragmentaire de ce type de textes et parfois leur qualité est aussi discutable. Un bonne exemple se trouve à l’Inathèque, où l’on peut trouver l’enregistrement d’un présentateur se faisant canarder par de nombreux produits alimentaires (Inathèque, URL : « https://www.ina.fr/video/CPC03008653/meteo-video.html ») Il n’y a aucun doute que des bulletins météorologiques de ce type posent des problèmes pour l’analyse de l’évolution linguistique des textes : ils présentent des structures non-prototypiques et ils diminuent la qualité du corpus. D’une part, nous aborderons cette question avec une certaine « méthodologie de recollement », qui concerne la recherche d’archives et les métadonnées disponibles pour tous les textes. D’autre part, nous approcherons ce problème avec une « méthodologie linguistique », qui observe l’analyse linguistique finale et l’importance de ces métadonnées et la variation textuelle

La linguistique et le bulletin météo télévisé comme vulgarisation scientifique. Analyse corpus-based d’expressivité et de perception dans un corpus comparatif de bulletins météorologiques français et allemands.

Du point de vue de la linguistique des discours spécialisés, le bulletin météorologique est défini comme une forme de communication professionnelle externe (Krycki 2006). Cela veut dire que les données d’un domaine spécialisé – dans ce cas la météorologie – sont transformées (on dit aussi « recontextualisées » ) pour être comprises d’un public non-spécialiste, comme les téléspectateurs. Ce processus de recontextualisation est très intéressant pour les linguistes du discours. Pour mon doctorat je suis concerné par deux questions liées à cette recontextualisation : (i) Comment sont ces données spécialistes recontextualisées d’un point de vue linguistique ? ; (ii) Dans quelle mesure est recontextualisation est-elle variable ou différente d’un bulletin météo à un autre ? La présentation traite exclusivement la deuxième question, à travers une analyse des éléments d’expressivité (par ex. belles éclaircies, grand beau, beau temps) et du sensoriel dans les bulletins météorologiques français. Le but est de montrer comment le discours des bulletins météo diffère dans différents formats et pourquoi. À cet égard, la présentation sera la continuation de la présentation réalisée durant la Semaine DATA/SHS de 2020 et illustrera de façon détaillée les méthodes quantitatives et qualitatives utilisés pendant ma recherche de doctorat

Faraday Effect in Stacks of Aromatic Molecules

© 2017 American Chemical Society. The effects of stacking aromatic units on the Verdet constant are analyzed by employing quantum chemistry calculations and are compared to the effects of oligomerization. Building stacked oligomers leads to enhanced Verdet constants, but still smaller than in the corresponding linear oligomers. Further enhancements appear when going from simple to fused-ring polyaromatic compounds.status: publishe

On the Aromatic Character of 1,2-Dihydro-1,2-azaborine2 According to Magnetic Criteria

The behavior of benzene, 1,2-dihydro-1,2-azaborine, and borazineunder a magnetic perturbation is theoretically evaluated to assess how the 1,2-dihydro-1,2-azaborine molecule displays an intermediate character between itshydrocarbon (benzene) and fully boro-nitrogen (borazine) parents. The use oftridimensional visualization tools confirm that “single-value” magnetic propertiesdo not allow one to properly evaluate the whole magnetic behavior and the“magnetic π-aromaticity” of these compounds, since the σ-electron response isalso modified due to the introduction of polar B-N bond(s) and has a significantinfluence on the various magnetic properties

Laser à fibre amplifié à 1060 nm paramétrable en fréquence et en durée d'impulsion: résultats à 1 MHz, 500 ps

National audienc

The impact of taking up care tasks on pensions : results of typical-case simulations for several European countries

Abstract: Informal care is often accompanied by a reduction or abandonment of professional activity by the caregiver. Therefore, caregiving may be associated with a lower pension for the former caregiver than for people without care obligations. There is a large gender difference in informal care responsibilities, and this may contribute to the gender pension gap. As the impact of care-related labour market decisions depends on the design of the pension system, we carry out a cross-country comparison, in which we analyse the impact of care obligations in countries with high (Luxembourg), middle (Liechtenstein, Belgium, Portugal) and low (Slovenia) gender pension gaps. Using typical-case simulation models, we examine how the impact of care-related events is mediated by pension rules, given women's labour market decisions. To what extent does working part time or interrupting one's career at the age of 30 or 54 reduce the later pension benefit? How are these losses mitigated by pension credits that are conditional on caregiving? We find that the mitigating effects are generally strongest in Belgium, followed by Luxembourg and Slovenia. Such credits hardly exist in Portugal, while in Liechtenstein they have only a small impact. However, the consequences of either working part time or interrupting work can also be mitigated via general rules in the system that are unrelated to caregiving (such as in Portugal and Liechtenstein). They can, on the other hand, be aggravated by the existence of higher accrual rates for individuals who extend their careers, as in Luxembourg and Slovenia

Spiro-based thermally activated delayed fluorescence emitters with reduced non-radiative decay for high quantum efficiency, low roll-off, light-emitting diodes

Herein, we report the use of spiro-configured fluorene-xanthene scaffolds as a novel, promising and effective strategy in thermally activated delayed fluorescence (TADF) emitter design to attain high photoluminescence quantum yields (PL), short delayed luminescence lifetime, high external quantum efficiency (EQE) and minimum efficiency roll-off characteristics in organic light-emitting diodes (OLEDs). The optoelectronic and electroluminescence properties of SFX-, spiro-(fluorene-9,9’-xanthene), based emitters (SFX-PO-DPA, SFX-PO-DPA-Me and SFX-PO-DPA-OMe) were investigated both theoretically and experimentally. All three emitters exhibited sky blue to green emission enabled by a Herzberg-Teller mechanism in the excited state. They possess short excited state delayed lifetimes (<10 s), high photoluminescence quantum yields (PL ~70%) and small singlet-triplet splitting energies (EST < 0.10 eV) in the doped films in an mCP host matrix. The OLEDs showed some of the highest EQEs using spiro-containing emitters where maximum external quantum efficiencies (EQEmax) of 11% and 16% were obtained for devices using SFX-PO-DPA and SFX-PO-DPA-OMe, respectively. Further, a record EQEmax of 23% for a spiro-based emitter coupled with a small efficiency roll off (19% at 100 cd m-2) was attained with SFX-PO-DPA-Me