Electroluminescence from a polythiophene molecular wire suspended in a plasmonic scanning tunneling microscope junction

The electroluminescence of a polythiophene wire suspended between two metallic electrodes is probed using a scanning tunneling microscope. Under positive sample voltage, the spectral and voltage dependencies of the emitted light are consistent with the fluorescence of the wire junction mediated by localized plasmons. This emission is strongly attenuated for the opposite polarity. Both emission mechanism and polarity dependence are similar to what occurs in organic light emitting diodes (OLED) but at the level of a single molecular wire.Comment: to be published in Physical Review Letter

Pulling and Stretching a Molecular Wire to Tune its Conductance

A scanning tunnelling microscope is used to pull a polythiophene wire from a Au(111) surface while measuring the current traversing the junction. Abrupt current increases measured during the lifting procedure are associated to the detachment of molecular sub-units, in apparent contradiction with the expected exponential decrease of the conductance with wire length. \textit{Ab initio} simulations reproduce the experimental data and demonstrate that this unexpected behavior is due to release of mechanical stress in the wire, paving the way to mechanically gated single-molecule electronic devices

Control of the organization of 4,4′-bis(carbazole)-1,1′-biphenyl (CBP) molecular materials through siloxane functionalization

Funding: This research was funded by the French National Research Agency (ANR) through the Programme d’Investissement d’Avenir under contract ANR-11-LABX-0058-NIE within the Investissement d’Avenir program ANR-10-IDEX-0002-02.We show that through the introduction of short dimethylsiloxane chains, it was possible to suppress the crystalline state of CBP in favor of various types of organization, transitioning from a soft crystal to a fluid liquid crystal mesophase, then to a liquid state. Characterized by X-ray scattering, all organizations reveal a similar layered configuration in which layers of edge-on lying CBP cores alternate with siloxane. The difference between all CBP organizations essentially lay on the regularity of the molecular packing that modulates the interactions of neighboring conjugated cores. As a result, the materials show quite different thin film absorption and emission properties, which could be correlated to the features of the chemical architectures and the molecular organizations.Peer reviewe

Nomogram Predicting the Likelihood of Parametrial Involvement in Early-Stage Cervical Cancer: Avoiding Unjustified Radical Hysterectomies

Background: We aimed to establish a tool predicting parametrial involvement (PI) in patients with early-stage cervical cancer and select a sub-group of patients who would most benefit from a less radical surgery. Methods: We retrospectively reviewed patients from two prospective multicentric databases—SENTICOL I and II—from 2005 to 2012. Patients with early-stage cervical cancer (FIGO 2018 IA with lympho-vascular involvement to IIA1), undergoing radical surgery (hysterectomy or trachelectomy) with bilateral sentinel lymph node (SLN) mapping with no metastatic node or PI on pre-operative imaging, were included. Results: In total, 5.2% patients (11/211) presented a histologic PI. After univariate analysis, SLN status, lympho-vascular space invasion, deep stromal invasion and tumor size were significantly associated with PI and were included in our nomogram. Our predictive model had an AUC of 0.92 (IC95% = 0.86–0.98) and presented a good calibration. A low risk group, defined according to the optimal sensitivity and specificity, presented a predicted probability of PI of 2%. Conclusion: Patients could benefit from a two-step approach. Final surgery (i.e. radical surgery and/or lymphadenectomy) would depend on the SLN status and the probability PI calculated after an initial conization with bilateral SLN mapping

Resilience and development: Mobilizing for transformation

In 2014, the Third International Conference on the resilience of social-ecological systems chose the theme “resilience and development: mobilizing for transformation.” The conference aimed specifically at fostering an encounter between the experiences and thinking focused on the issue of resilience through a social and ecological system perspective, and the experiences focused on the issue of resilience through a development perspective. In this perspectives piece, we reflect on the outcomes of the meeting and document the differences and similarities between the two perspectives as discussed during the conference, and identify bridging questions designed to guide future interactions. After the conference, we read the documents (abstracts, PowerPoints) that were prepared and left in the conference database by the participants (about 600 contributions), and searched the web for associated items, such as videos, blogs, and tweets from the conference participants. All of these documents were assessed through one lens: what do they say about resilience and development? Once the perspectives were established, we examined different themes that were significantly addressed during the conference. Our analysis paves the way for new collective developments on a set of issues: (1) Who declares/assign/cares for the resilience of what, of whom? (2) What are the models of transformations and how do they combine the respective role of agency and structure? (3) What are the combinations of measurement and assessment processes? (4) At what scale should resilience be studied? Social transformations and scientific approaches are coconstructed. For the last decades, development has been conceived as a modernization process supported by scientific rationality and technical expertise. The definition of a new perspective on development goes with a negotiation on a new scientific approach. Resilience is presently at the center of this negotiation on a new science for development. (Résumé d'auteur

Madurese Seafarers. Prahus, Timber and Illegality on the Margins of the Indonesian State, Kurt Stenross

Dans l’archipel indonésien, l’une des singularités de Madura est d’être une île aride et déshéritée dans un arc d’îles prospères. Les Madourais, quant à eux, constituent le troisième groupe ethnique du pays, estimé en l’absence de statistiques par ethnie à environ 13 millions d’individus dont seulement 2,5 millions sur l’île. Cette île, si proche et pourtant si différente de Java, hormis quelques études linguistiques (Kiliaan, Hendricks conduites vers 1830) a longtemps été ignorée par la comm..

Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors.

Strong-coupling between excitons and confined photonic modes can lead to the formation of new quasi-particles termed exciton-polaritons which can display a range of interesting properties such as super-fluidity, ultrafast transport and Bose-Einstein condensation. Strong-coupling typically occurs when an excitonic material is confided in a dielectric or plasmonic microcavity. Here, we show polaritons can form at room temperature in a range of chemically diverse, organic semiconductor thin films, despite the absence of an external cavity. We find evidence of strong light-matter coupling via angle-dependent peak splittings in the reflectivity spectra of the materials and emission from collective polariton states. We additionally show exciton-polaritons are the primary photoexcitation in these organic materials by directly imaging their ultrafast (5 × 106 m s-1), ultralong (~270 nm) transport. These results open-up new fundamental physics and could enable a new generation of organic optoelectronic and light harvesting devices based on cavity-free exciton-polaritons.EPSRC (EP/R025517/1), EPSRC (EP/M025330/1), ERC Horizon 2020 (grant agreements No 670405 and No 758826), ERC (ERC-2014-STG H2020 639088), Netherlands Organisation for Scientific Research, Swedish Research Council (VR, 2014-06948), Knut and Alice Wallenberg Foundation 3DEM-NATUR (no. 2012.0112), Royal Commission for the Exhibition of 1851, CNRS (France), US Department of Energy, Office of Science, Basic Energy Sciences, CPIMS Program, Early Career Research Program (DE-SC0019188)