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..

Metal Ion Enhanced Charge Transfer in a Terpyridine-bis-Pyrene System

The synthesis, electrochemical and photophysical properties of a branched molecule 3,5-bis(pyrene-1-yl)-4′-phenyl-2,2′:6′,2″-terpyridine are reported. Spectroscopy in different solvents reveals that an optical electron transfer from the pyrene donor to the terpyridyl electron acceptor can occur in polar media, as the system displays both charge transfer (CT) absorption and CT emission. Furthermore, the study of the zinc complex as well as the bis-protonated form shows an enhancement of the electron transfer character of the system, by an increase of the acceptor strength. This is accompanied by a large increase of the non-radiative processes. With sub-nanosecond transient absorption spectroscopy, the CT state, consisting of the pyrene radical cation and the terpyridine radical anion, has been detected. At room temperature, the study of the nanosecond transient absorption spectra reveals the formation of a low-lying triplet excited state that we attribute to the pyrene moiety through which the CT state decays. At 77K, the absence of the terpyridine triplet emission also suggests the population of a low-lying triplet state of the pyrene unit

Influence of halogen substitution on aggregation-induced near infrared emission of borondifluoride complexes of 2′-hydroxychalcones

International audienceThe generation of organic dyes displaying intense red and near infrared fluorescence emission in solution and in the solid state is a topic of intense current interest. In this study, we present the synthesis and investigation of nine new derivatives of borondifluoride complexes of 2 0-hydroxychalcones: four homo-and five hetero-substituted compounds X-X and X-Y (X, Y = F, Cl, Br, and I), where two halogen atoms are attached ortho and para (X and Y respectively in X-Y) to the 2 0-hydroxyl group. UV-vis absorption fluorescence spectra in solution and in the solid state, DFT calculations, and analyses of single-crystal structures were performed. For all compounds, a fluorescence emission enhancement was clearly observed when passing from the solution (DCM) to the crystal (up to more than 10 fold). These molecules thus exhibit aggregation-induced enhanced emission (AIEE) with fluorescence maxima ranging from 654 nm (F-F) to 807 nm (I-I) in the solid state. The highest fluorescence quantum yield value within the series is reached for Cl-Cl (24% at 730 nm) whilst I-Br shows a rather good efficiency (2.5% at 806 nm) despite the presence of the two heavy iodine and bromine atoms. This study sheds light on the role of the halogen substitution on crystalline packing and solid-state emission properties of the chalcone-BF 2 dyes. We outline that using halogen atoms provides a useful cocktail of steric, electrostatic and photophysical ingredients upon which to base the generation of near infrared emitting organic solids

Optical properties of quadrupolar and bi-quadrupolar dyes: intra and inter chromophoric interactions

International audienc

Near infrared electroluminescence from Nd(TTA) 3 phen in solution-processed small molecule organic light-emitting diodes

International audienceWe report on the near infrared electroluminescence properties of a Nd3+ complex with thenoyltrifluoroacetone and 1,10-phenantroline ligands in solution-processed organic light-emitting diodes. Spin-coated blends containing a 1,3-bis(9-carbazolyl)benzene host doped with the Nd3+ complex were found to exhibit a photoluminescence quantum yield of about 0.5%, regardless of the doping concentration level. Electroluminescent devices based on these small molecule blends showed the characteristic emission of Nd3+ at 890, 1060 and 1330 nm with an external quantum efficiency as high as 0.022%. These improved performances were mainly attributed to direct charge trapping and exciton formation on the near infrared emitter. Importantly, the efficiency roll-off at high current densities due to triplet-triplet exciton annihilation in the device containing 20 wt% of the complex was lower than what is typically observed in lanthanide complex-based electroluminescent devices. This is presumably due to the high triplet energy of the host material, which prevents guest-to-host energy-back transfer and thus host-guest triplet-triplet exciton annihilation

Synthesis of Bioinspired Curcuminoid Small Molecules for Solution-Processed Organic Solar Cells with High Open-Circuit Voltage

International audienceBorondifluoride complexes of curcuminoid derivatives end-capped with triphenylamine groups were designed for solution-processed bulk-heterojunction organic solar cells. They were obtained very simply in a one-pot synthesis from cheap building blocks. Compared to push-pull systems based on borondifluoride complexes of hydroxychalcones, curcuminoids present the donor-accept-or-donor electronic structure and exhibit significantly improved chemical and thermal stability and photovoltaic performance. Indeed, power conversion efficiency up to 4.14% and high open-circuit voltage over 1.0 V have been achieved using PC61BM as acceptor

Organic Monolithic Natural Hyperbolic Material

International audienc

Near-Infrared Electroluminescence and Low Threshold Amplified Spontaneous Emission above 800 nm from a Thermally Activated Delayed Fluorescent Emitter

International audienc

Optimal stride frequencies in running at different speeds

<div><p>During running at a constant speed, the optimal stride frequency (SF) can be derived from the u-shaped relationship between SF and heart rate (HR). Changing SF towards the optimum of this relationship is beneficial for energy expenditure and may positively change biomechanics of running. In the current study, the effects of speed on the optimal SF and the nature of the u-shaped relation were empirically tested using Generalized Estimating Equations. To this end, HR was recorded from twelve healthy (4 males, 8 females) inexperienced runners, who completed runs at three speeds. The three speeds were 90%, 100% and 110% of self-selected speed. A self-selected SF (SF_self) was determined for each of the speeds prior to the speed series. The speed series started with a free-chosen SF condition, followed by five imposed SF conditions (SF_self, 70, 80, 90, 100 strides·min^-1) assigned in random order. The conditions lasted 3 minutes with 2.5 minutes of walking in between. SF_self increased significantly (p<0.05) with speed with averages of 77, 79, 80 strides·min^-1 at 2.4, 2.6, 2.9 m·s^-1, respectively). As expected, the relation between SF and HR could be described by a parabolic curve for all speeds. Speed did not significantly affect the curvature, nor did it affect optimal SF. We conclude that over the speed range tested, inexperienced runners may not need to adapt their SF to running speed. However, since SF_self were lower than the SF_opt of 83 strides·min^-1, the runners could reduce HR by increasing their SF_self.</p></div