Search results for "mission"
showing 10 items of 5334 documents
Statistical study of the influence of CNTs purification and plasma functionalization on the properties of Polycarbonate-CNTs nanocomposites
2014
This work reports a statistical study on the relationship between the chemical-physical properties of CNTs, which vary by changing the conditions of purification and plasma treatment, and the macroscopic properties of PC-based nanocomposites. CNTs are synthesized and then purified in two different ways and used as fillers for the preparation of PC/CNTs nanocomposites. In some cases, oxygen plasma treatment is carried out to improve their affinity to the matrix. The CNTs are characterized by TGA, ICP/OES and FT-Raman spectroscopy, titration and morphological analysis. Mechanical, dynamic-mechanical, electrical and morphological tests are used for characterizing PC/CNTs nanocomposites.
Structural studies of dielectric polymer nanocomposites
2013
A constant need for the development of new and superior materials is always present; for example, a better electrical insulator would enable more efficient use of electrical power. Polymeric nanocomposites, i.e. nanodielectrics, are thought to have unique electrical properties. The basic chemical constitution of a material alone fails to provide an understanding of how desired properties of a material originate or predict the long term behavior of a material. We need to define the structure behind the functionality of a material. To do that, the structure of the material must be studied on several scales. This research was part of the Finnish Funding Agency for Technology and Innovation (TE…
Nano-graphite cold cathodes for electric solar wind sail
2015
The nanographite (NG) films consisting of tiny graphite crystallites (nanowalls) are produced by carbon condensation from methane–hydrogen gas mixture activated by a direct current discharge. High aspect ratio and structural features of the NG crystallites provides efficient field electron emission (FE). Applicability and performance of the NG films in an electron gun (E-gun) of a solar wind thruster system with an electric sail (E-sail) is tested. The long-term tests are demonstrated suitability of E-gun assembly with the NG cathodes for the real space missions. The results of the tests are analyzed and physical mechanisms of the cathode aging and practical methods for improvement performa…
Preparation of Nd:YAG Nanopowder in a Confined Environment
2007
Nanopowder of yttrium aluminum garnet (YAG, Y3Al5O12) doped with neodymium ions (Nd:YAG) was prepared in the water/cetyltrimethylammonium bromide/1-butanol/n-heptane system. Aluminum, yttrium, and neodymium nitrates were used as starting materials, and ammonia was used as a precipitating agent. Coprecipitate hydroxide precursors where thermally treated at 900 degrees C to achieve the garnet phase. The starting system with and without reactants was characterized by means of the small-angle neutron scattering technique. The system, without reactants, is constituted by a bicontinuous structure laying near the borderline with the lamellar phase region. The introduction of nitrates stabilizes th…
Optoelectronic devices based on caesium lead halide perovskite nanocrystals
2020
Tradicionalmente, la implementación de materiales activos en circuitos fotónicos integrados se ha basado en la utilización de semiconductores III-V y vidrios y materiales ferroeléctricos dopados con iones de tierras raras. Sin embargo, en la actualidad existe una alternativa basada en (nano) materiales sintetizados por técnicas de química coloidal. La posibilidad de procesar nanomateriales en solución permite fabricar semiconductores con propiedades ópticas (emisión, absorción, dispersión de luz) que pueden diseñarse durante la síntesis. Además, su naturaleza coloidal permite integrarlas en cualquier arquitectura óptica mediante sencillas técnicas de impresión en tinta. En este contexto, lo…
Mechanisms of cell death in canine parvovirus-infected cells provide intuitive insights to developing nanotools for medicine
2010
Jonna Nykky, Jenni E Tuusa, Sanna Kirjavainen, Matti Vuento, Leona GilbertNanoscience Center and Department of Biological and Environmental Science, University of Jyväskylä, FinlandAbstract: Viruses have great potential as nanotools in medicine for gene transfer, targeted gene delivery, and oncolytic cancer virotherapy. Here we have studied cell death mechanisms of canine parvovirus (CPV) to increase the knowledge on the CPV life cycle in order to facilitate the development of better parvovirus vectors. Morphological studies of CPV-infected Norden laboratory feline kidney (NLFK) cells and canine fibroma cells (A72) displayed characteristic apoptotic events. Apoptosis was f…
Application of Zero Exclusion Condition to Stability Analysis of Computer Networks
2016
Stability, or robust [Dscr ]-stability analysis of computer network considered as a dynamic system, relies on increasing the speed of data transmission while minimizing the queuing time delays of its packets in the router buffers that can affect the overall data flow of the network traffic. We consider a zero exclusion condition as an effective method for testing and analyzing the computer networks stability. Our findings indicate that keeping control over the queuing time delays as well as including some factors of the RED algorithm and its variants, which we present in this paper, can improve the quality of network services significantly. Our method can be applicable both to single-loop a…
Transcranial Magnetic Stimulation and Neuroimaging Coregistration
2013
The development of neuroimaging techniques is one of the most impressive advancements in neuroscience. The main reason for the widespread use of these instruments lies in their capacity to provide an accurate description of neural activity during a cognitive process or during rest. This important advancement is related to the possibility to selectively detect changes of neuronal activity in space and time by means of different biological markers. Specifically, functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and nearinfrared spectroscopy (NIRS) use metabolic markers of ongoing neuronal activity to provide a…
Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3a
2022
Abbott, R., et al. (LIGO and VIRGO Collaboration)
The advanced Virgo longitudinal control system for the O2 observing run
2020
Following a successful period of data-taking between 2006 and 2011, the Virgo gravitational-wave detector was taken offline for a major upgrade. The changes made to the instrument significantly increased the complexity of the control systems and meant that an extended period of commissioning was required to reach a sensitivity appropriate for science data-taking. This commissioning period was completed in July of 2017 and the second-generation Advanced Virgo detector went on to join the Advanced LIGO detectors in the O2 science run in August of the same year. The upgraded detector was approximately twice as sensitive to binary neutron star mergers as the first-generation instrument. During …