Use of Nanocellulose to Produce Water-Based Conductive Inks with Ag NPs for Printed Electronics

The need for more sustainable printed electronics has emerged in the past years. Due to this, the use of nanocellulose (NC) extracted from cellulose has recently been demonstrated to provide interesting materials such as functional inks and transparent flexible films due to its properties. Its high specific surface area together with the high content of reactive hydroxyl groups provide a highly tailorable surface chemistry with applications in ink formulations as a stabilizing, capping, binding and templating agent. Moreover, NC mechanical, physical and thermal properties (high strength, low porosity and high thermal stability, respectively) provide an excellent alternative for the currently used plastic films. In this work, we present a process for the production of water-based conductive inks that uses NC both as a template for silver nanoparticles (Ag NPs) formation and as an ink additive for ink formulation. The new inks present an electrical conductivity up to 2 × 10⁶ S/m, which is in the range of current commercially available conductive inks. Finally, the new Ag NP/NC-based conductive inks have been tested to fabricate NFC antennas by screen-printing onto NC-coated paper, demonstrating to be operative.     

Comportement mécanique à l'appareil de cisaillement de casagrande de trois graveleux latéritiques compactés provenant du Sénégal Occidental

Compacted laterite soils are widely used as fills and road construction materials in tropical countries. The shear strength characteristics of these soils have been the subject of important studies and have produced slightly contrasting results. The results of the shear strength of three OMP compacted laterites from Western Senegal are examined in this paper. The shear strength parameter obtained using the big shear box (150 mm×150 mm, which can be extended to 300 mm) is a fonction of the level of stress and is also dependent on the state of the samples (soaked or not).     

Geotechnical characterization of expansive soils and their implications in ground movements in Dakar

To better understand the role of problematic soils in the instability phenomena observed in Dakar, investigations and laboratory tests have been undertaken including the clay mineralogy, physical properties, mechanical properties, shear strength and shrink/swell characteristics of the soils—fine/coarse-grained volcanic tuffs and residual (weathered) soil. The results were related to the slope instability and foundation failures observed in Dakar and recommendations made to mitigate the effects of these problematic soils in future developments.      

Knowledge Retrieval, Use and Storage for Efficiency

The Knowledge Retrieval, Use and Storage for Efficiency (KRUSE) symposiums aim at providing a forum for research related to efficient processing and management of complex information and knowledge. This special issue presents selected articles from the KURSE'97 symposium held in Vancouver, Canada. In this introductory article we describe the goals of KRUSE and present some background topics that are fundamental to the articles herein. In particular, we provide an overview of partial order theory, formal concept analysis and taxonomic encoding. We also outline the articles that follow.     

DTN: an architectural retrospective

We review the rationale behind the current design of the Delay/Disruption Tolerant Networking (DTN) Architecture and highlight some remaining open issues. Its evolution, from a focus on deep space to a broader class of heterogeneous networks that may suffer disruptions, affected design decisions spanning naming and addressing, message formats, data encoding methods, routing, congestion management and security. Having now achieved relative stability with the design, additional experience is required in long-running operational environments in order to fine tune our understanding of DTN concepts and the types of capabilities that are worth the investment in implementation complexity. We expect key management, handling of congestion, multicasting capability, and routing to remain active areas of research and development, and that DTN may continue to be an active research endeavor for at least the next few years.     

A new lumped-parameter model of cerebrospinal hydrodynamics during the cardiac cycle in healthy volunteers

Our knowledge of cerebrospinal fluid (CSF) hydrodynamics has been considerably improved with the recent introduction of phase-contrast magnetic resonance imaging (phase-contrast MRI), which can provide CSF and blood flow measurements throughout the cardiac cycle. Key temporal and amplitude parameters can be calculated at different sites to elucidate the role played by the various CSF compartments during vascular brain expansion. Most of the models reported in the literature do not take into account CSF oscillation during the cardiac cycle and its kinetic energy impact on the brain. We propose a new lumped-parameter compartmental model of CSF and blood flows in healthy subjects during the cardiac cycle. The system was divided into five submodels representing arterial blood, venous blood, ventricular CSF, cranial subarachnoid space, and spinal subarachnoid space. These submodels are connected by resistances and compliances. The model developed was used to reproduce certain functional characteristics observed in seven healthy volunteers, such as the distribution (amplitude and phase shift) of arterial, venous, and CSF flows. The results show a good agreement between measured and simulated intracranial CSF and blood flows.     

The grafting of isoprene onto poly(propylene oxide)

The grafting of isoprene as well as a comonomer mixture of isoprene and acrylonitrile onto a backbone of high molecular weight poly(propylene oxide) with tertiary-butyl peroctoate gave a gumstock which is sulfur curable to a product having interesting elastomeric properties.