59 research outputs found
A D-optimal design to model the performances of dressings and devices for negative pressure wound therapy
No full textA D-optimal design was used to identify and model variables that affect the transit time of wound exudate through an illustrative dressing used for negative pressure wound therapy. Many authors have addressed the clinical benefits of negative pressure wound therapy, but limited information is available on how to assess performances of dressings. In this paper, the transit time of wound exudate through a dressing was chosen as a model parameter to show how experimental design (DOE) can be used for this purpose. Results demonstrated that rate of exudate production, temperature and dressing thickness were the variables with the largest impact on transit time. The DOE approach could be used to model other dressing properties, like for example capability of absorbing excess exudate or breathability
Catalytic CVD Synthesis of Carbon Nanotubes: Towards High Yield and Low Temperature Growth
No full textThe catalytic chemical vapor deposition (CCVD) is currently the most flexible and economically attractive method for the growth of carbon nanotubes. Although its principle is simple, the precisely controlled growth of carbon nanotubes remains very complex because many different parameters influence the growth process. In this article, we review our recent results obtained on the synthesis of carbon nanotubes via CCVD. We discuss the role of the catalyst and the catalyst support. Our recent results obtained from the water assisted growth and the equimolar C₂H₂-CO₂ reaction are also discussed. Both procedures lead to significantly enhanced carbon nanotube growth. In particular, the latter allows growing carbon nanotubes on diverse substrate materials at low temperatures.sponsorship: We thank the Centre Interdisciplinaire de Microscopie Electronique (CIME) for access to electron microscopes and technical support. We also thank R. Gaal, B. Korbely, M. Duchamp, J.C. Andresen, S. Casimirius for fruitful discussions. This work was financially supported by the National Centre of Competence in Research (NCCR) "Nanoscale Science" of the Swiss National Science Foundation and by the CABTURES project funded by Nano-Tera.ch. M. Mionic thanks for the grant of the Swiss National Science Foundation (NSF 121814). R. Smajda was funded by the European project VIACARBON (ICT-2007.8.1). J.W. Seo thanks the Belgian Hercules Stichting for their support in HER/08/25 and the K.U. Leuven for the support in STRT1/08/025 and GOA/10/004. (National Centre of Competence in Research (NCCR) "Nanoscale Science" of the Swiss National Science Foundation, Nano-Tera.ch., Swiss National Science Foundation|NSF 121814, VIACARBON|ICT-2007.8.1, HER/08/25, STRT1/08/025, GOA/10/004)status: Publishe
22 juin 2015 - "L'avenir de la démocratie délibérative" (Congrès AFSP 2015)
No full textSession thématique "L'avenir de la démocratie délibérative" au Congrès de l'Association française de science politique, lundi 22 juin 2015, Aix-en-Provence. Organisée par Charles Girard et Bernard Manin, avec Andrei Bächtiger, Loic Blondiaux, Antoine Chollet, Lionel Cordier, Andrea Felicetti, James S. Fishkin, Florence Haegel, Robert C. Luskin, Jane Mansbridge, Bernard Reber, Yves Sintomer, et David Smajda
Low-temperature, highly efficient growth of carbon nanotubes on functional materials by an oxidative dehydrogenation reaction
No full textIn many applications like photovoltaics, fuel cells, batteries, or interconnects in integrated circuits carbon nanotubes (CNTs) have the role of charge transport electrodes. The building of such devices requires an in situ growth of CNTs at temperatures where the structure or chemical composition of the functional materials is unaltered. We report that in a chemical vapor deposition process involving an oxidative dehydrogenation reaction of C2H2 with CO2 growth temperatures below 400 degrees C are achieved. Furthermore, the growth can be performed on versatile materials ranging from metals through oxides to organic materials.sponsorship: We thank the Centre Interdisciplinaire de Microscopie Electronique (CIME) for access to electron microscopes and technical support and D. Acquaviva and A. Arun for preparing patterned catalysts. We thank R. Gaal for the contact resistance measurements. This work was financially supported by the CABTURES project funded by Nano-Tera.ch. M.M. thanks the Swiss National Science Foundation for Grant NSF 121814. The work done by J.C. Andresen and R. Smajda was funded by the European projects VIACARBON (ICT-2007 8.1-216668) and MULTIPLAT (NMP4-SL-2009-228943). (Nano-Tera.ch, Swiss National Science Foundation|NSF 121814, VIACARBON|ICT-2007 8.1-216668, MULTIPLAT|NMP4-SL-2009-228943)status: Publishe
Production of high quality carbon nanotubes for less than $1 per gram
No full textIn this article, we report on the mass production of carbon nanotubes using a continuous production system based on a rotary tube furnace. At first, we have optimized the composition of the metallic nanoparticles. Bimetallic Fe2Ni and Fe2Co alloys exhibit higher catalytic activity than pure Fe, Co or Ni. Then, catalyst production process has been modified for the preparation of large quantity of catalyst with low aggregation suitable for large scale synthesis of CNTs. A production rate of about 1.2 kg per day has been achieved. This is yielding to a cost production of less than $1 per gram. Finally, we show that the CNTs growth can also be obtained on naturally occurring calcite support for further cost reduction of the synthesis. Quality of the CNTs produced has been established by measuring their mechanical properties using AFM. Young's modulus of the CNTs can be as high as the ideal value of 1 TPa. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimLPM
A combination of capillary and dielectrophoresis-driven assembly methods for wafer scale integration of carbon-nanotube-based nanocarpets
No full textThe wafer scale integration of carbon nanotubes (CNT) remains a challenge for electronic and electromechanical applications. We propose a novel CNT integration process relying on the combination of controlled capillary assembly and buried electrode dielectrophoresis (DEP). This process enables us to monitor the precise spatial localization of a high density of CNTs and their alignment in a pre-defined direction. Large arrays of independent and low resistivity (4.4 x 10-5 omega m) interconnections were achieved using this hybrid assembly with double-walled carbon nanotubes (DWNT). Finally, arrays of suspended individual CNT carpets are realized and we demonstrate their potential use as functional devices by monitoring their resonance frequencies (ranging between 1.7 and 10.5 MHz) using a Fabry–Perot interferometer
In vitro investigation of the cellular toxicity of boron nitride nanotubes
No full textNanotubes present one of the most promising opportunities in nanotechnology with a plethora of applications in nanoelectronics, mechanical engineering, as well as in biomedical technology. Due to their structure and some physical properties, boron nitride (BN) nanotubes (BNNTs) possess several advantages over carbon nanotubes (CNTs), and they are now commercially produced and used on a large scale. The human and environmental exposure to BN nanomaterials is expected to increase in the near future, and their biological responses need to be examined. Using complementary assays, we have extensively investigated the effects of BNNTs on the viability and metabolic status of different cell types: on the one hand, the effects on cells present in the lung alveoli, and on the other hand, on human embryonic kidney (HEK) cells. Our results indicate that BNNTs are cytotoxic for all cell types studied and, in most cases, are more cytotoxic than CNTs in their pristine (p-CNT) and functionalized (f-CNT) form. However, the level of toxicity and the prominent morphological alterations in the cell populations withstanding BNNT exposure are cell-type-dependent. For instance, BNNTs induced extensive multinucleated giant cell formation in macrophages and increased levels of eosinophilia in fibroblasts. Finally, our results point the toxicity of tubular nanomaterials to be strongly correlated with the cellular accumulation enhanced for straight nanotubes
Parental quality of life and recurrent ENT infections in their children : development of a questionnaire
No full textDuring the first 4 years of life, children develop ear, nose and throat (ENT) infections because their immune system is not fully mature. Some of them will develop a recurrence and repetition of these episodes might have impact on the parents' quality of life. Based on a literature review, face to face interviews with parents and meetings with a paediatrician, a 17 item French questionnaire has been devised in order to evaluate the specific impairment of parents' quality of life during a winter season. Cultural adaptations were made for Italy, Germany, Portugal and the Czech Republic. This questionnaire was completed by 1,214 parents in a longitudinal survey. The questionnaire was reduced to 14 items and three scores were identified through principal component analysis: an emotional score (eight items), a daily disturbance score (six items) and a global score (14 items). Construct validity was confirmed through multitrait analysis and internal consistency reliability confirmed using Cronbach's alpha. The emotional score was found to be linked to the number and type of ENT episodes while the daily disturbance score was linked to social consequences. The global score was linked to both aspects, demonstrating the clinical validity. This questionnaire is therefore able to measure the cumulative effect of recurrence of children's ENT infections on their parents' quality of life in France, Italy, Germany, Portugal and the Czech Republic. Qual Life Res 7:501-512 (C) 1998 Kluwer Academic Publishers
Synthesis, electrical resistivity, thermo-electric power and magnetization of cubic ZnMnO3
No full textCubic ZnMnO3 powder in the form of well-crystalline nanoflakes have been synthesized at low temperatures from a nitrate precursor. The electrical properties of cubic ZuMnO(3) samples have been established by DC resistivity (rho) and thermo-electric power (Seebeck coefficient) measurements on a pressed pellet. The material exhibits insulator behavior with 0.7 eV acceptor ionization energy in the measured temperature range of 170-300 K. The thermo-electric power indicates a positive sign of the charge carriers. The obtained material exhibits a superparamagnetic signature with a blocking temperature of 9 K and the ZFC-FC splitting temperature of 15 K. (C) 2010 Elsevier Ltd. All rights reserved.LPM
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