204 research outputs found
Graphene in silicon photovoltaic cells
Graphene is an allotrope of carbon. Its structure is one-atom-thick planar sheets of carbon atoms that are
densely packed in a honeycomb crystal lattice [1]. The richness of optical and electronic properties of
graphene attracts enormous interest. Its true potential seems to be in photonics and optoelectronics, where
the combination of its unique optical and electronic properties can be fully exploited. The optical
absorption of graphene layers is proportional to the number of layers, each absorbing A=1-T=πα=2.3%
over the visible spectrum [2].The rise of graphene in photonics and optoelectronics is shown by several
recent results, ranging from solar cells and light emitting devices, to touch screens, photodetectors and
ultrafast lasers.
Current photovoltaic (PV) technology is dominated by Si cells, with an energy conversion coefficient
up to 25% [3]. Such an inorganic PV consists in a current transparent conductor (TC) replacing one of the
electrodes of a PIN photodiode. The standard material used so far for these electrodes is indium-tinoxide,
or ITO. But indium is expensive and relatively rare, so the search has been on for a suitable
replacement. A possible substitute made from inexpensive and ubiquitous carbon is graphene. Being only
constituted of carbon, it will become cheap and easily recyclable. But at the moment, the major difficulty
consists in its fabrication and/or transfer.
Our project consists in synthetizing graphene by CVD (Chemical Vapor Deposition) on Cu and in
transferring the obtained layer on silicon PV cells, and then in testing their energy conversion efficiency
JION: A JavaSpaces Implementation for Opportunistic Networks
International audienceDisconnected mobile ad hoc networks (or D-MANETs) are partially or intermittently connected wireless networks, in which continuous end-to-end connectivity between mobile nodes is not guaranteed. The ability to self-form and self-manage brings great opportunities for D-MANETs, but developing distributed applications capable of running in such networks remains a major challenge. A middleware system is thus needed between network level and application level in order to ease application development, and help developers take advantage of D-MANETs' unique features. In this paper, we introduce JION (JavaSpaces Implementation for Opportunistic Networks), a coordination middleware specifically designed for D-MANETs, and with which pre-existing or new JavaSpaces-based applications can be easily deployed in such networks
JOMS: a Java Message Service Provider for Disconnected MANETs
International audienceA disconnected mobile ad hoc network (or D-MANET) is a wireless network, which because of the sparse distribution of mobile hosts appears at best as a partially or intermittently connected network. Designing and implementing distributed applications capable of running in such a challenged environment is not a trivial task. Middleware systems such as Java Message Service (JMS) have made application development easy and cost-effective in traditional wired networks. It can be expected that middleware systems designed specifically for D-MANETs bring similar benefits. In this paper, we introduce JOMS (Java Opportunistic Message Service), a JMS provider for D-MANETs with which pre-existing and new JMS-based applications can be deployed simply in D-MANETs
Intentional overdose with insulin: prognostic factors and toxicokinetic/toxicodynamic profiles
International audienc
C3PO: a Spontaneous and Ephemeral Social Networking Framework for a collaborative Creation and Publishing of Multimedia Contents
International audienceOnline social networks have been adopted by a large part of the population, and have become in few years essential communication means and a source of information for journalists. Nevertheless, these networks have some drawbacks that make people reluctant to use them, such as the impossibility to claim for ownership of data and to avoid commercial analysis of them, or the absence of collaborative tools to produce multimedia contents with a real editorial value. In this paper, we present a new kind of social networks, namely spontaneous and ephemeral social networks (SESNs). SESNs allow people to collaborate spontaneously in the production of multimedia documents so as to cover cultural and sport events
In situ monitoring of galactolipid digestion by infrared spectroscopy in both model micelles and spinach chloroplasts
Galactolipids are the main lipids from plant photosynthetic membranes and they can be digested by pancreatic lipase related protein 2 (PLRP2), an enzyme found in the pancreatic secretion in many animal species. Here, we used transmission Fourier-transform infrared spectroscopy (FTIR) to monitor continuously the hydrolysis of galactolipids by PLRP2, in situ and in real time. The method was first developed with a model substrate, a synthetic monogalactosyl diacylglycerol with 8-carbon acyl chains (C8-MGDG), in the form of mixed micelles with a bile salt, sodium taurodeoxycholate (NaTDC). The concentrations of the residual substrate and reaction products (monogalactosylmonoglyceride, MGMG; monogalactosylglycerol, MGG; octanoic acid) were estimated from the carbonyl and carboxylate vibration bands after calibration with reference standards. The results were confirmed by thin layer chromatography analysis (TLC) and specific staining of galactosylated compounds with thymol and sulfuric acid. The method was then applied to the lipolysis of more complex substrates, a natural extract of MGDG with long acyl chains, micellized with NaTDC, and intact chloroplasts isolated from spinach leaves. After a calibration performed with α-linolenic acid, the main fatty acid (FA) found in plant galactolipids, FTIR allowed quantitative measurement of chloroplast lipolysis by PLRP2. A full release of FA from membrane galactolipids was observed, that was not dependent on the presence of bile salts. Nevertheless, the evolution of amide vibration band in FTIR spectra suggested the interaction of membrane proteins with NaTDC and lipolysis products
Migratory Pathways and Connectivity in Asian Houbara Bustards: Evidence from 15 Years of Satellite Tracking
Information on migratory pathways and connectivity is essential to understanding population dynamics and structure of migrant species. Our manuscript uses a unique dataset, the fruit of 103 individual Asian houbara bustards captured on their breeding grounds in Central Asia over 15 years and equipped with satellite transmitters, to provide a better understanding of migratory pathways and connectivity; such information is critical to the implementation of biologically sound conservation measures in migrant species. At the scale of the distribution range we find substantial migratory connectivity, with a clear separation of migration pathways and wintering areas between western and eastern migrants. Within eastern migrants, we also describe a pattern of segregation on the wintering grounds. But at the local level connectivity is weak: birds breeding within the limits of our study areas were often found several hundreds of kilometres apart during winter. Although houbara wintering in Arabia are known to originate from Central Asia, out of all the birds captured and tracked here not one wintered on the Arabian Peninsula. This is very likely the result of decades of unregulated off-take and severe habitat degradation in this area. At a time when conservation measures are being implemented to safeguard the long-term future of this species, this study provides critical data on the spatial structuring of populations
Mutation screening of ASMT, the last enzyme of the melatonin pathway, in a large sample of patients with intellectual disability.
International audienceBACKGROUND: Intellectual disability (ID) is frequently associated with sleep disorders. Treatment with melatonin demonstrated efficacy, suggesting that, at least in a subgroup of patients, the endogenous melatonin level may not be sufficient to adequately set the sleep-wake cycles. Mutations in ASMT gene, coding the last enzyme of the melatonin pathway have been reported as a risk factor for autism spectrum disorders (ASD), which are often comorbid with ID. Thus the aim of the study was to ascertain the genetic variability of ASMT in a large cohort of patients with ID and controls. METHODS: Here, we sequenced all exons of ASMT in a sample of 361 patients with ID and 440 controls. We then measured the ASMT activity in B lymphoblastoid cell lines (BLCL) of patients with ID carrying an ASMT variant and compared it to controls. RESULTS: We could identify eleven variations modifying the protein sequence of ASMT (ID only: N13H, N17K, V171M, E288D; controls only: E61Q, D210G, K219R, P243L, C273S, R291Q; ID and controls: L298F) and two deleterious splice site mutations (IVS5+2T>C and IVS7+1G>T) only observed in patients with ID. We then ascertained ASMT activity in B lymphoblastoid cell lines from patients carrying the mutations and showed significantly lower enzyme activity in patients carrying mutations compared to controls (p = 0.004). CONCLUSIONS: We could identify patients with deleterious ASMT mutations as well as decreased ASMT activity. However, this study does not support ASMT as a causative gene for ID since we observed no significant enrichment in the frequency of ASMT variants in ID compared to controls. Nevertheless, given the impact of sleep difficulties in patients with ID, melatonin supplementation might be of great benefit for a subgroup of patients with low melatonin synthesis
Phenotypic and genotypic characteristics of mastocytosis according to the age of onset.
International audienceAdult's mastocytosis is usually associated with persistent systemic involvement and c-kit 816 mutation, while pediatrics disease is mostly limited to the skin and often resolves spontaneously. We prospectively included 142 adult patients with histologically proven mastocytosis. We compared phenotypic and genotypic features of adults patients whose disease started during childhood (Group 1, n = 28) with those of patients whose disease started at adult's age (Group 2, n = 114). Genotypic analysis was performed on skin biopsy by sequencing of c-kit exons 17 and 8 to 13. According to WHO classification, the percentage of systemic disease was similar (75 vs. 73%) in 2 groups. C-kit 816 mutation was found in 42% and 77% of patients in groups 1 and 2, respectively (p<0.001). 816 c-kit mutation was associated with systemic mastocytosis in group 2 (87% of patients with systemic mastocytosis vs. 45% with cutaneous mastocytosis, p = 0.0001). Other c-kit activating mutations were found in 23% of patients with mastocytosis' onset before the age of 5, 0% between 6 and 15 years and 2% at adults' age (p<0.001). In conclusion, pathogenesis of mastocytosis significantly differs according to the age of disease's onset. Our data may have major therapeutic relevance when considering c-kit-targeted therapy
Extending the clinical spectrum of X-linked Tonne-Kalscheuer syndrome (TOKAS):new insights from the fetal perspective
INTRODUCTION: Tonne-Kalscheuer syndrome (TOKAS) is a recessive X-linked multiple congenital anomaly disorder caused by RLIM variations. Of the 41 patients reported, only 7 antenatal cases were described.METHOD: After the antenatal diagnosis of TOKAS by exome analysis in a family followed for over 35 years because of multiple congenital anomalies in five male fetuses, a call for collaboration was made, resulting in a cohort of 11 previously unpublished cases.RESULTS: We present a TOKAS antenatal cohort, describing 11 new cases in 6 French families. We report a high frequency of diaphragmatic hernia (9 of 11), differences in sex development (10 of 11) and various visceral malformations. We report some recurrent dysmorphic features, but also pontocerebellar hypoplasia, pre-auricular skin tags and olfactory bulb abnormalities previously unreported in the literature. Although no clear genotype-phenotype correlation has yet emerged, we show that a recurrent p.(Arg611Cys) variant accounts for 66% of fetal TOKAS cases. We also report two new likely pathogenic variants in RLIM, outside of the two previously known mutational hotspots.CONCLUSION: Overall, we present the first fetal cohort of TOKAS, describe the clinical features that made it a recognisable syndrome at fetopathological examination, and extend the phenotypical spectrum and the known genotype of this rare disorder.</p
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