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International audience; In the field of p-conjugated nanohoops, the size of the macrocycle has a huge impact on its structural characteristics, which in turn affect its electronic properties. In this work, we report the first experimental investigations linking the size of a nanohoop to its charge transport properties, a key property in organic electronics. We describe the synthesis and the study of the first example of cyclocarbazole possessing five constituting building units, namely [5]-cyclo-N-butyl-2,7-carbazole [5]C-Bu-Cbz. By comparison with a shorter analogue, [4]-cyclo-N-butyl-2,7-carbazole [4]C-Bu-Cbz, we detail the photophysical, electrochemical, morphological and charge transport properties, highlighting the key role played by the hoop size. Particularly, we show that the saturated field effect mobility of [5]C-Bu-Cbz is four times higher than that of its smaller analogue [4]C-Bu-Cbz (4.22 × 10-5vs 1.04 × 10-5 cm².V-1.s-1). However, the study of the other OFET characteristics (threshold voltage VTH and subthreshold slope SS) suggest that a small nanohoop is beneficial for a good organization of the molecules in thin films whereas a large one increases the density of structural defects, and hence of traps for the charge carriers. The present findings are of interest for the further development of nanohoops in electronics.

Estrogens act through nuclear and membrane-initiated signaling. Estrogen receptor alpha (ERα) is critical for reproduction, but the relative contribution of its nuclear and membrane signaling is unclear. To address this question, we used two complementary approaches: estetrol (E4) a natural estrogen described to act as an agonist of nuclear ERα and a mERα antagonist and the C451A-ERα mouse lacking mERα. E4dose-dependently blocks ovulation in female rats, but the mechanism underlying this effect is unknown. To determine whether E4acts centrally to control ovulation, we tested its effect on the positive feedback of estradiol (E2) on LH secretion. In ovariectomized females chronically exposed to a low dose of E2, estradiol benzoate (EB) alone or combined with progesterone (P) induced a LH surge and the associated increase in the number of activated kisspeptin (Kp) and gonadotropin-releasing hormone (GnRH) neurons. However, E4blocked these effects of EB when provided alone, but not when combined to P. These results indicate that E4blocked the induction of the positive feedback and the associated neuronal activation in the absence of P, suggesting an antagonistic effect of E4on mERα as shown in peripheral tissues. In parallel, C451A-ERα females do not show a pre-ovulatory LH surge and the associated activation of Kp and GnRH neurons in response to EB unless they are treated with P. The similarity of the responses of C451A-ERα mice and wild-type females treated with E4 supports a role for membrane-initiated estrogen signaling in the EB-induced LH surge.

Synthesis, polymorph investigation, crystallographic study, and fabrication of OFETs in solution-processed thin films of C7-BTBT-C7.

This study is focused on the Y6 electron acceptor to assess the impact of elongating the inner side chain from 8 to 12 carbon atoms by combining DFT calculations, UV-visible spectroscopy, atomic force microscopy analysis and device characterization.

Peptoids are peptide regioisomers with attractive structural tunability in terms of sequence and three-dimensional arrangement. Peptoids are foreseen to have a great potential for many diverse applications, including their utilization as a chiral stationary phase in chromatography. To achieve chiral recognition, a chiral side chain is required to allow specific interactions with a given enantiomer from a racemic mixture. One of the most studied chiral stationary phases, built with (S)-N-1-phenylethyl (Nspe) units, was shown to be successful in resolving racemic mixtures of binaphthyl derivatives. However, there is currently no description at the atomic scale of the factors favoring its enantioselectivity. Here, we take advantage of steered molecular dynamics simulations to mimic the elution process at the atomic scale and present evidence that the predominantly right-handed helical conformation of Nspe peptoids and their ability to form stronger hydrogen bonds with the (S) enantiomer are responsible for the chiral recognition of the popular chiral probe 2,2′-bihydroxy-1,1′-binaphthyl.

We report on the growth of metal- and metal-oxide based nanoparticles (NPs) in heated polyol solutions. For this purpose, NPs are produced by the sputtering of a silver, gold, or a copper target to produce either silver, gold, or copper oxide NPs in pentaerythritol ethoxylate (PEEL) which has been annealed up to 200 °C. The objective of the annealing step is the fine modulation of their size. Thus, the evolution of the NP size and shape after thermal annealing is explained according to collision/coalescence kinetics and the affinity between the metal-/metal-oxide and PEEL molecule. Moreover, highlights of few phenomena arising from the annealing step are described such as (i) the reduction of copper oxide into copper by the polyol process and (ii) the effective formation of carbon dots after annealing at 200 °C.

International audience; A number of factors contribute to orbital energy alignment with respect to the Fermi level in molecular tunnel junctions. Here, we report a combined experimental and theoretical effort to quantify the effect of metal image potentials on the highest occupied molecular orbital to Fermi level offset, ε(h), for molecular junctions based on self-assembled monolayers (SAMs) of oligophenylene ethynylene dithiols (OPX) on Au. Our experimental approach involves the use of both transport and photoelectron spectroscopy to extract the offsets, ε(h)(trans) and ε(h)(UPS), respectively. We take the difference in these quantities to be the image potential energy eV(image). In the theoretical approach, we use density functional theory (DFT) to calculate directly eV(image) between positive charge on an OPX molecule and the negative image charge in the Au. Both approaches yield eV(image) ∼ -0.1 eV per metal contact, meaning that the total image potential energy is ∼-0.2 eV for an assembled junction with two Au contacts. Thus, we find that the total image potential energy is 25-30% of the total offset ε(h), which means that image charge effects are significant in OPX junctions. Our methods should be generally applicable to understanding image charge effects as a function of molecular size, for example, in a variety of SAM-based junctions.

The song control nucleus HVC of songbirds has emerged as a widespread model system to study adult neurogenesis and the factors that modulate the incorporation of new neurons, including seasonal state, sex differences or sex steroid hormone concentrations. However, the specific function of these new neurons born in adulthood remains poorly understood. We implemented a new procedure based on focal X-ray irradiation to deplete neural progenitors in the ventricular zone adjacent to HVC and study the functional consequences. A 23 Gy dose depleted by more than 50 percent the incorporation of BrdU in neural progenitors, a depletion that was confirmed by a significant decrease in doublecortin positive neurons. This depletion of neurogenesis significantly increased the variability of testosterone-induced songs in females and decreased their bandwidth. Expression of the immediate early gene ZENK (a.k.a. egr-1) in secondary auditory areas of the telencephalon that respond to song was also inhibited. These data provide compelling evidence that new neurons in HVC play a role in both song production and perception and that X-ray focal irradiation represents an excellent tool to advance our understanding of adult neurogenesis.

Lung transplantation is the only curative option of end-stage chronic respiratory diseases. However the survival rate is only about 50% at 5 years. Whereas experimental evidences support that innate allo-responses impact on the clinical outcome, the knowledge of the involved mechanisms is limited. Here, we evaluate a cross-circulatory platform for monitoring the early recruitment and activation of immune cells in an extracorporeal donor lung by coupling blood perfusion to cell mapping with a fluorescent marker in the pig, a commonly-used species for lung transplantation. The perfusing pig cells were easily detectable in lung cell suspensions, in broncho-alveolar lavages and in different areas of lung sections, indicating infiltration of the organ. Myeloid cells (granulocytes and monocytic cells) were the dominantly recruited subsets. Between 6 and 10 h of perfusion, recruited monocytic cells presented a strong upregulation of MHC class II and CD80/86 expression, whereas alveolar macrophages and donor monocytic cells showed no significant modulation of expression. Altogether the cross-circulation model permits to monitor the initial encounter between perfusing cells and lung graft, in an easy, rapid, and controllable manner, for generating robust information on innate response and testing targeted therapies for improvement of lung transplantation outcome.

The binding of 17β-oestradiol to oestrogen receptor alpha (ERα) plays a crucial role in the control of reproduction, acting through both nuclear and membrane-initiated signalling. To study the physiological role of membrane ERα in the reproductive system, we used the C451A-ERα mouse model with selective loss of function of membrane ERα. Despite C451A-ERα mice being described as sterile, daily weighing and ultrasound imaging revealed that homozygous females do become pregnant, allowing the investigation of the role of ERα during pregnancy for the first time. All neonatal deaths of the mutant offspring mice resulted from delayed parturition associated with failure in pre-term progesterone withdrawal. Moreover, pregnant C451A-ERα females exhibited partial intrauterine embryo arrest at about E9.5. The observed embryonic lethality resulted from altered expansion of Tpbpa-positive spiral artery-associated trophoblast giant cells into the utero-placental unit, which is associated with an imbalance in expression of angiogenic factors. Together, these processes control the trophoblast-mediated spiral arterial remodelling. Hence, loss of membrane ERα within maternal tissues clearly alters the activity of invasive trophoblast cells during placentogenesis. This previously unreported function of membrane ERα could open new avenues towards a better understanding of human pregnancy-associated pathologies.