DC and radio-frequency transmission characteristics of double-walled carbon nanotubes-based ink

In this paper, double-walled carbon nanotubes (DWNTs) network layers were patterned using inkjet transfer printing. The remarkable conductive characteristics of carbon nanotubes (CNTs) are considered as promising candidates for transmission line as well as microelectronic interconnects of an arbitrary pattern. In this work, the DWNTs were prepared by the catalytic chemical vapor deposition process, oxidized and dispersed in ethylene glycol solution. The DWNTs networks were deposited between electrodes contact and then characterized at DC through current-voltage measurements, low frequency, and high frequency by scattering parameters measurements from 40 MHz up to 40 GHz through a vector network analyzer. By varying the number of inkjet overwrites, the results confirm that the DC resistance of DWNTs networks can be varied according to their number and that furthermore the networks preserve ohmic characteristics up to 100 MHz. The microwave transmission parameters were obtained from the measured S-parameter data. An algorithm is developed to calculate the propagation constant "γ", attenuation constant "α" in order to show the frequency dependence of the equivalent resistance of DWNTs networks, which decreases with increasing frequency

Etude de filtres millimétriques accordables en technologie microfluidique

National audienceCet article présente les travaux initiés au Lab-STICC et au LAAS sur la conception de dispositifs passifs hyperfréquences accordables sur la basse d'une approche microfluidique. L'idée est d'utiliser des micros canaux dans lesquels circulent des fluides. Ces fluides, diélectriques dans un premier temps, sont utilisés pour modifier la permittivité effective d'un substrat sur lequel est réalisée une structure planaire. La perturbation apportée par le fluide diélectrique va ainsi modifier la fréquence de travail du dispositif. En première approche, des stubs quart d'onde et des filtres passe-bande à stubs sont examinés

Risk Factors and Outcomes for Late Presentation for HIV-Positive Persons in Europe: Results from the Collaboration of Observational HIV Epidemiological Research Europe Study (COHERE)

Background: Few studies have monitored late presentation (LP) of HIV infection over the European continent, including Eastern Europe. Study objectives were to explore the impact of LP on AIDS and mortality. Methods and Findings: LP was defined in Collaboration of Observational HIV Epidemiological Research Europe (COHERE) as HIV diagnosis with a CD4 count <350/mm3 or an AIDS diagnosis within 6 months of HIV diagnosis among persons presenting for care between 1 January 2000 and 30 June 2011. Logistic regression was used to identify factors associated with LP and Poisson regression to explore the impact on AIDS/death. 84,524 individuals from 23 cohorts in 35 countries contributed data; 45,488 were LP (53.8%). LP was highest in heterosexual males (66.1%), Southern European countries (57.0%), and persons originating from Africa (65.1%). LP decreased from 57.3% in 2000 to 51.7% in 2010/2011 (adjusted odds ratio [aOR] 0.96; 95% CI 0.95-0.97). LP decreased over time in both Central and Northern Europe among homosexual men, and male and female heterosexuals, but increased over time for female heterosexuals and male intravenous drug users (IDUs) from Southern Europe and in male and female IDUs from Eastern Europe. 8,187 AIDS/deaths occurred during 327,003 person-years of follow-up. In the first year after HIV diagnosis, LP was associated with over a 13-fold increased incidence of AIDS/death in Southern Europe (adjusted incidence rate ratio [aIRR] 13.02; 95% CI 8.19-20.70) and over a 6-fold increased rate in Eastern Europe (aIRR 6.64; 95% CI 3.55-12.43). Conclusions: LP has decreased over time across Europe, but remains a significant issue in the region in all HIV exposure groups. LP increased in male IDUs and female heterosexuals from Southern Europe and IDUs in Eastern Europe. LP was associated with an increased rate of AIDS/deaths, particularly in the first year after HIV diagnosis, with significant variation across Europe. Earlier and more widespread testing, timely referrals after testing positive, and improved retention in care strategies are required to further reduce the incidence of LP

Transcriptional Regulation by CHIP/LDB Complexes

It is increasingly clear that transcription factors play versatile roles in turning genes “on” or “off” depending on cellular context via the various transcription complexes they form. This poses a major challenge in unraveling combinatorial transcription complex codes. Here we use the powerful genetics of Drosophila combined with microarray and bioinformatics analyses to tackle this challenge. The nuclear adaptor CHIP/LDB is a major developmental regulator capable of forming tissue-specific transcription complexes with various types of transcription factors and cofactors, making it a valuable model to study the intricacies of gene regulation. To date only few CHIP/LDB complexes target genes have been identified, and possible tissue-dependent crosstalk between these complexes has not been rigorously explored. SSDP proteins protect CHIP/LDB complexes from proteasome dependent degradation and are rate-limiting cofactors for these complexes. By using mutations in SSDP, we identified 189 down-stream targets of CHIP/LDB and show that these genes are enriched for the binding sites of APTEROUS (AP) and PANNIER (PNR), two well studied transcription factors associated with CHIP/LDB complexes. We performed extensive genetic screens and identified target genes that genetically interact with components of CHIP/LDB complexes in directing the development of the wings (28 genes) and thoracic bristles (23 genes). Moreover, by in vivo RNAi silencing we uncovered novel roles for two of the target genes, xbp1 and Gs-alpha, in early development of these structures. Taken together, our results suggest that loss of SSDP disrupts the normal balance between the CHIP-AP and the CHIP-PNR transcription complexes, resulting in down-regulation of CHIP-AP target genes and the concomitant up-regulation of CHIP-PNR target genes. Understanding the combinatorial nature of transcription complexes as presented here is crucial to the study of transcription regulation of gene batteries required for development

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New developments in inkjet of deposits carried out under localized extraction or helium

International audienceThis paper presents the first results obtained by mounting on an ink-jet print head two first systems which through injection of a helium flow, allow faster ink-jet evaporation rates and higher resolution or increased droplet velocity without modifying the droplet diameter. A third type of system features extraction specifically located at the impact of the droplets onto the substrate. This avoids contamination of the machine environment while significantly improving printing resolution. In all cases, these systems allow printing at much lower temperatures and the use of inks with high-boiling point solvents

Fabrication of Activated Carbon Electrodes by Inkjet Deposition

International audienceThe inkjet deposition technology turns out to be interesting in various applications when one attempts to reduce manufacturing costs, simplify technological steps, and implement materials that could not be deposited in any other way. One of the limitations however, is the issue raised by resolution which is directly linked to the ejection head manufacturing technology. In this paper, a method of activated carbon deposition based on inkjet is presented. Activated carbon is extensively used in chemistry for its impurity absorption capabilities and in other applications like the fabrication of supercapacitors. It is shown in particular that by using a localized surface treatment with OTS and an activated carbon suspension stabilized by a surfactant, one can get 10 µm structures, which are, therefore, much smaller than the ejection head nozzle diameter. To implement and optimize the process, the contact angle measurement technique is utilized

STUDY OF A HIGHLY LOCALIZED ACTIVATED CARBON DEPOSITION PROCESS USING INKJET PRINTING TECHNOLOGY

International audienceAn activated carbon deposition technique based on inkjet printing is proposed for the fabrication of supercapacitors electrodes. By mastering the activated carbon suspension in ethylene glycol through the use of a surfactant and by functionalizing the substrate with OTS, 10µm wide structures were obtained with 50 µm ink jet nozzles