19 research outputs found
Double walled carbon nanotube/polymer composites via in-situ nitroxide mediated polymerisation of amphiphilic block copolymers
Get PDFBecause of their unique physical, chemical, and structural properties, carbon nanotubes (CNT) are playing an increasingly important role in the development of new engineering materials [1]. Across many different applications, CNT/polymer composites have been extensively studied [2] S.B. Sinnot and R. Andrews, Carbon nanotubes: synthesis, properties, and applications, Crit Rev Solid State Mater Sci 26 (2001), pp. 145–249.[2]. The key problem for CNT/polymer composite elaboration is the dispersion, compatibilization, and stabilization of the CNT in the polymer matrix. To solve this problem, a structure with di-block copolymers, one with a good affinity to CNT (monomer M1), the other being the matrix (monomer M2), is proposed in this study, as shown on the two steps mechanism of Fig. 1
Le rôle de l'activité ludique dans la confiance en soi des élèves
No full textSelf-confidence is omnipresent in the academic context, and it is an important metric for the success of our students. Yet, studies often favor pedagogical metrics which can be quantified objectively more easily than self-confidence. This study offers a theoretical approach of self-confidence, but also of learning games which remove a constraint for the students who are anxious towards formal evaluation methods. The challenge of the experiment has been to offer a way to measure the self-confidence of my students,but also to analyze its evolution after a learning game.La confiance en soi est omniprésente dans le contexte scolaire, et elle est un critère important pour la réussite de nos élèves. Pourtant, cet indicateur est souvent oublié au profit d'indicateurs pédagogiques plus faciles à mesurer de manière objective. Cette étude présente une approche théorique de la confiance en soi, mais également de l'activité ludique qui permet de lever certains freins pour les élèves appréhensifs de l'évaluation formelle. Le défi de l'expérimentation a été de proposer une mesure de la confiance en soi chez les élèves, mais également une analyse de l'évolution de celle-ci suite à la mise en place d'une activité ludique
Investigation of the cytotoxicity of CCVD carbon nanotubes towards human umbilical vein endothelial cells
Get PDFThe cytotoxicity of different samples of carbon nanotubes synthesised by catalytic chemical vapour deposition was investigated towards human umbilical vein endothelial cells, using two cytotoxicity standard assays (neutral red assay for the cell viability and MTT assay—tetrazolinium salt—for the cell metabolic activity). No cytotoxicity was found for any sample
Impact of the surface roughness on the electrical capacitance
Get PDFA new hybrid approach consists to use the advantages of both systems namely the high geometric aspects of the electrodes of the ultracapacitor and the high dielectric strength of polymer materials used in dielectric capacitors. The surface roughness of the electrodes of the ultracapacitor is manufactured with nano-porous materials; activated carbon and carbon nanotubes (CNTs). Many compositions of both carbonaceous materials are tested with different insulating materials (liquid and solid) to constitute the hybrid capacitor. It appears that the capacitance increases with the carbonaceous composition: An increasing from 15 to 40% is observed as compared to a plane capacitor, it can be twice with a 100 wt% of CNTs content. But, the impregnation of the insulating material in the surface roughness remains the key point of the realization of the hybrid capacitor. The roughness accessibility is a major property to optimize in order to improve the impregnation of the insulating material to increase the electrical capacitance
DC and radio-frequency transmission characteristics of double-walled carbon nanotubes-based ink
Get PDFIn 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
Complement activation and protein adsorption by carbon nanotubes
Get PDFAs a first step to validate the use of carbon nanotubes as novel vaccine or drug delivery devices, their interaction with a part of the human immune system, complement, has been explored. Haemolytic assays were conducted to investigate the activation of the human serum complement system via the classical and alternative pathways. Western blot and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) techniques were used to elucidate the mechanism of activation of complement via the classical pathway, and to analyse the interaction of complement and other plasma proteins with carbon nanotubes. We report for the first time that carbon nanotubes activate human complement via both classical and alternative pathways. We conclude that complement activation by nanotubes is consistent with reported adjuvant effects, and might also in various circumstances promote damaging effects of excessive complement activation, such as inflammation and granuloma formation. C1q binds directly to carbon nanotubes. Protein binding to carbon nanotubes is highly selective, since out of the many different proteins in plasma, very few bind to the carbon nanotubes. Fibrinogen and apolipoproteins (AI, AIV and CIII) were the proteins that bound to carbon nanotubes in greatest quantit
Un recueil de chansons de Charles-Louis Cadet de Gassicourt
No full textEine Liedersammlung von Charles-Louis Cadet de Gassicourt.
Diese handschriftliche Sammlung von vierzig C.-L. Cadet de Gassicourt (1769-1821) zu verdankenden Lieder, für die meisten, zwischen 1815 und 1827 verfasst, bietet zugleich strenge Urteile über des panser Leben, die Gesellschaft, die königliche Autorität, und Anklänge an das unordentliche sentimentale Leben des Verfassers. Unter einer geistreicher Form und in einer regen Schreibart erscheinen die tieferen Gefühle des Verfassers, ganz mit Enttäuschungen und Bitterkeit zersetzt.A collection of songs from Charles-Louis Cadet de Gassicourt.
This unpublished manuscript collection of forty songs by C.-L. Cadet de Gassicourt (1769- 1821), written for the most part between 1815 and 1827, offers simultaneously severe judgments on Parisian life, society and royal authority, and reflections of the disordered sentimental life of the author. Spiritual in form and sprightly in style, these are the deep feelings of the author, which seem strongly imbued with disappointment and bitterness.Flahaut Jean. Un recueil de chansons de Charles-Louis Cadet de Gassicourt. In: Revue d'histoire de la pharmacie, 82ᵉ année, n°300, 1994. pp. 7-21
Nanoparticle-induced systemic toxicity and immune response in Galleria mellonella larvae
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The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.Introduction: Nanotechnology is one of the most rapidly advancing scientific fields, offering innovative solutions in diverse areas such as medicine, agriculture, and materials science. However, concerns regarding the environmental and biological toxicity of nanomaterials continue to rise. It is thus essential to develop reliable, ethical, and cost-effective models to assess the in vivo toxicity of Nanoparticles (NPs). This study aims to evaluate the immunotoxicity and systemic effects of various inorganic nanoparticles using Galleria mellonella (GM) larvae as a non-mammalian in vivo model.
Methods: GM larvae were exposed to different types of NPs, including starch-coated and anionic superparamagnetic iron oxide nanoparticles (SPIONs), double-walled carbon nanotubes (CNTs), and gold nanoparticles (GNPs). Flow cytometry was used to monitor haemocyte numbers, while larval survival assays assessed mortality. Histological analyses were conducted to detect CNT accumulation in tissues. The immunosuppressive effects of GNPs were assessed in GM larvae challenged with sub-lethal doses of Pseudomonas aeruginosa and Acinetobacter baumannii.
Results: The results demonstrate NP retention in GM tissues and showed that surface and size properties of NPs significantly influenced their biological effects. Anionic SPIONs lacking a starch coating caused greater haemocyte depletion and higher mortality than their biocompatible coated counterparts. GNP toxicity was found to be size-dependent, with particles between 60 and 100 nm producing the most severe haemocyte depletion, which was comparable to that obtained with the immune suppressant cyclophosphamide.
Conclusion: Overall, this study supports the use of GM larvae as an effective model for nanoparticle toxicity screening and demonstrates the usefulness of this model in detecting both toxic and immunosuppressive properties of nanomaterials.The author(s) declare that financial support was received for the research and/or publication of this article. R.R.M. is supported by a Biotechnology and Biological Sciences Research Council New Investigator Award (BB/V007823/1) and a Medical Research Council Grant (MR/Y001354/1). R.R.M. is also supported by the Academy of Medical Sciences/the Wellcome Trust/the Government Department of Business, Energy and Industrial Strategy/the British Heart Foundation/Diabetes UK Springboard Award (SBF006∖1,040). These grants enabled the bacterial infection studies. The National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) (NC/V001582/1) supported the establishment of the Galleria mellonella infection model
Converting Ambipolar Double Walled Nanotube bundles to Unipolar Carbon Nanotube Field Effect Transistor devices by inner functionalization
No full textInternational audienceCarbon nanotube (CNT)-based transistor devices have been demonstrated and are seen as the next-generation alternative to replace the current generation electronic devices based on silicon MOS technology. Their limitations, however, are related to their instability in ambient conditions and technical challenges in scaling up production of individual CNT devices. Herein, a simple technique to convert ambipolar (both n- and p-carrier) individual CNT-based transistors into unipolar (p-type carrier) transistors that carry large currents ≈±7 mA before saturation is demonstrated. Such large current-carrying capability from an individual or single-bundle CNTs will be ideal for applications that require high currents such as output stages of radio frequency (RF) and audio amplifiers. This work highlights the ability to tune CNT-based transistor devices to suit specific applications, which is essential for the development of next generation of nanoelectronics
Distinctive features of the oropharyngeal microbiome in Inuit of Nunavik and correlations of mild to moderate bronchial obstruction with dysbiosis
No full textAbstract Inuit of Nunavik are coping with living conditions that can influence respiratory health. Our objective was to investigate associations between respiratory health in Inuit communities and their airway microbiome. Oropharyngeal samples were collected during the Qanuilirpitaa? 2017 Inuit Health Survey and subjected to metagenomic analyses. Participants were assigned to a bronchial obstruction group or a control group based on their clinical history and their pulmonary function, as monitored by spirometry. The Inuit microbiota composition was found to be distinct from other studied populations. Within the Inuit microbiota, differences in diversity measures tend to distinguish the two groups. Bacterial taxa found to be more abundant in the control group included candidate probiotic strains, while those enriched in the bronchial obstruction group included opportunistic pathogens. Crossing taxa affiliation method and machine learning consolidated our finding of distinct core microbiomes between the two groups. More microbial metabolic pathways were enriched in the control participants and these were often involved in vitamin and anti-inflammatory metabolism, while a link could be established between the enriched pathways in the disease group and inflammation. Overall, our results suggest a link between microbial abundance, interactions and metabolic activities and respiratory health in the Inuit population
