The optoelectronic properties of new dyes based on thienopyrazine

International audienceIn this article, we present the quantum result of six dyes based on thienopyrazine (D1–D6) with donor–π–acceptor structure (D–π–A) using DFT/B3LYP/6-31G(d,p) and TD-DFT/CAM-B3LYP/6-31G(d,p) levels. The donor unit varied and the influence was investigated. The study of structural, electronic, and optical properties of these dyes could help design more efficient functional photovoltaic organic materials. Key parameters in close connection with the short-circuit current density (J sc ) including light harvesting efficiency, injection driving force (ΔG inject ), and total reorganization energy (λ total ) are discussed in this work

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Contribution a l'etude des composes non stoechiometriques partiellement ioniques : application au dioxyde de cerium CeO_2_-_x

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Proceedings of the International Conference on Natural Language Processing, Signal and Speech Processing

International audienceThis book is a collection of the articles accepted in the conference ICNLSSP 2017. The objective of this is to create a synergy between different areas related to language processing: Speech Recognition, Social Network, Opinion mining, Images, Videos,...The conference highlights new approaches related to the language from basic theories to applications. ICNLSSP is an international conference dedicated to Natural Language Processing and Speech recognition (https://isga.ma/icnlsp_web/index.php). It is a technical conference not only proposing new researches on the concerned topics but also permits exchanging ideas between researchers from the world that will be very useful for PhD students and developers in this area

Effects of the terminal donor unit on the photovoltaic parameters of benzocarbazole-based dyes for DSSCs: DFT/TD-DFT investigations

In this paper, a computational study on five organic p-conjugated molecules based benzocarbazole (BC) is reported. These new dyes were characterize theoretically by density functional theory (DFT) and time-dependent (TD-DFT) approaches. Different electron side groups were introduced as a terminal donor to investigate their effects on the electronic structure; the HOMO, LUMO, free energy of electron injection (∆Ginject), free energy regeneration (∆Greg), open circuit voltage (Voc), the gap energy and UV–visible absorption spectra analysis of these dyes have been reported and discussed. The calculated results show that dye M3 with phenoxazine as a terminal donor groups can be used as a potential donor of electron in DSSCs, due to its best electronic and optical properties and good photovoltaic

Multicultureel manifest

Verdediging van de waarde van de multiculturaliteit tegenover de schrijvers van het Conservatief Manifes

DFT, DFTB and TD-DFT theoretical investigations of π-conjugated molecules based on thieno[2,3-b] indole for dye-sensitized solar cell applications

In this study, the electrochemical, photovoltaic and absorption properties of the new designed organic sensitizers dyes: Dye-1, Dye-2, Dye-3 and Dye-4 based on Dye-R, of D-π-A architecture, before and after binding to the TiO2 cluster surface on the ability to inject electrons to the surface. The D donor is the thieno[2,3-b] indole, π-spacer is thiophene, A acceptor is cycnoacrylic acid (CA). The properties were calculated using functional density theory (DFT), time-dependent TD-DFT and the density-functional tight-binding (DFTB) approach. Our study also focused on the analysis of the effects of the introduction of the auxiliary donor (D′)/acceptor (A′) groups on the main photovoltaic properties of the reference molecule Dye-R and to study the relationship between the molecular structure and optoelectronic properties. The analysis of the calculated properties of the new designed compounds D-D′-π-A (Dye-1), D-π-D′-A (Dye-2), D-A′-π-A (Dye-3) and D-π-A′-A (Dye-4), where A′ is benzothiadiazole and D′ is 9,9-diethyl-9H-fluorene, indicate that the molecular architecture has a significant effect on various properties of the studied dyes and that nature (donor D ′or acceptor A′) of the introduced groups, as well as the choice of their locations with respect to the π bridge, is of great importance. Indeed, among the four designed compounds Dye-4 (D-π-A′-A) and Dye-3 (D-A′-π-A) display significantly better properties than those of the reference molecule Dye-R (D-π-A) and of the two other designed dyes Dye-1 (D-D′-π-A), Dye-2 (D-π-D′-A). © 2022 Elsevier B.V

DFT theoretical investigations of p-conjugated molecules based on thienopyrazine and different acceptor moieties for organic photovoltaic cells

International audienceIn this work, theoretical study by using the DFT method on eleven conjugated com- pounds based on thienopyrazine is reported. Different electron side groups were introduced to investigate their effects on the electronic structure; The HOMO, LUMO and Gap energy of these compounds have been calculated and reported in this paper. A systematic theoretical study of such compound has not been reported as we know. Thus, our aim is first, to explore their electronic and spectroscopic properties on the basis of the DFT quantum chemical calculations. Second, we are interested to elucidate the parameters that influence the photovoltaic efficiency toward better under- standing of the structure-property relationships. The study of structural, electronic and optical properties for these compounds could help to design more efficient functional photovoltaic organic materials

Integrated Analysis by GC/MS and ¹³C NMR of Moroccan <i>Cladanthus mixtus</i> Essential Oil; Identification of Uncommon Epoxyfarnesanes

Cladanthus mixtus (L.) Chevall., Asteraceae, also known as Moroccan chamomile, is a spontaneous, annual plant growing wild in North-Western Morocco. Economically, the essential oil of C. mixtus is of high interest, Morocco being the only supplier on the international market. Two essential oil samples (EO) were isolated from aerial parts of Cladanthus mixtus (L.) Chevall., and analyzed by a combination of chromatographic and spectroscopic techniques (gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS), and 13C NMR spectroscopy). Computer matching against the in-house 13C NMR library allowed the identification of the eight components at appreciable contents, namely 3,6,6,9-bis-epoxy-farnesa-1,7(14),10-triene, and its 3-epi, 9-epi, and 3,9-diepi epimers, and 6,9-epoxy-farnesa-1,7(14),10-trien-3-ol and its 3-epi, 6-epi, and 3,6-diepi epimers. Our results confirm the tremendous chemical variability of Moroccan C. mixtus essential oil and the usefulness of 13C NMR analysis, in combination with GC(RI), for the identification of uncommon oxygenated sesquiterpenes that induce an original composition