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1.
The surface of two natural smectite-type clay samples was chemically modified by covalent grafting of amine groups, by reaction with γ-aminopropyltriethoxysilane, which were easily protonated in HCl medium. Multisweep cyclic voltammograms of clay-film modified glassy carbon electrodes made of either the raw clays or the propylammonium-functionalized samples exposed to Ru(NH3)63+ or Fe(CN)63− electroactive probes were obtained. The results indicated a permselective behavior of these clay and organoclay-films based on either favorable or unfavorable electrostatic interactions. The cation-exchanging raw clay film modified electrodes exhibited accumulation properties for Ru(NH3)63+ species while rejecting Fe(CN)63−, whereas the anion-exchanging organoclay coatings acted as a barrier against Ru(NH3)63+ while increasing dramatically the concentration of Fe(CN)63− species at the electrode surface. Strong binding of the probe to the organoclays resulted in a potential shift of ca. 0.1 V of the voltammetric signals characteristic of the Fe(CN)63−/4− couple in the anodic direction. Their good preconcentration efficiency at low analyte concentration highlighted their interest for electroanalytical applications. 相似文献
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Ertan Onur Yunus Durmus Mohamed Gamal Hawas Sonia Marcela Heemstra de Groot Ignas G. M. M. Niemegeers 《Wireless Personal Communications》2011,58(1):71-93
In this paper, we present a visionary concept referred to as Collaborative and Cognitive Network Platforms (CCNPs) as a future-proof
solution for creating a dependable, self-organizing and self-managing communication substrate for effective ICT solutions
to societal problems. CCNP creates a cooperative communication platform to support critical services across a range of business
sectors. CCNP is based on the personal network (PN) technology which is an inherently cooperative environment prototyped in
the Dutch Freeband PNP2008 and the European Union IST MAGNET projects. In CCNP, the cognitive control plane strives to exploit
the resources to better satisfy the requirements of networked applications. CCNP facilitates collaboration inherently. Through
cognition in the cognitive control plane, CCNP becomes a self-managed substrate. The self-managed substrate, in this paper,
is defined as cognitive and collaborative middleware on which future applications run without user intervention. Endemic sensor
networks may be incorporated into the CCNP concept to feed its cognitive control plane. In this paper, we present the CCNP
concept and discuss the research challenges related to collaboration and cognition. 相似文献
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Zülküf Genç Umar H. Rizvi Ertan Onur Ignas Niemegeers 《Wireless Personal Communications》2010,53(3):349-364
The basic idea behind cooperative communications is that mobile terminals collaborate to send data to each other. This effectively
adds diversity in the system and improves the overall performance. In this paper, we investigate the potential gains of cooperative
communication in future home networks. We derive analytical expressions for the error probability of binary phase shift keying
(BPSK) signals over Nakagami-m fading channels in a multi relay communication network. Following to the analytical study, we analyze the contribution of
cooperative relaying to the 60GHz network connectivity through simulations using a realistic indoor environment model. We
compare the performance of different relay configurations under variable obstacle densities. We show that a typical 60GHz
indoor network should employ either a multi-relay configuration or a single-relay configuration with a smart relay selection
mechanism to achieve acceptable outage rates. In the use of multiple-relay configuration, both analytical and simulation studies
indicate that increasing the number of cooperative relays does not improve the system performance significantly after a certain
threshold. 相似文献
5.
Ignas K. Tonle Emmanuel Ngameni Alain Walcarius 《Sensors and actuators. B, Chemical》2005,110(2):195-203
This study is devoted to the evaluation of a carbon paste electrode modified by a natural 2:1 phyllosilicate clay functionalized with either amine or thiol groups as a sensor for mercury(II). Functionalization was achieved by grafting the pristine clay via its reaction with 3-aminopropyltriethoxysilane (APTES) or 3-mercaptopropyltrimethoxysilane (MPTMS), respectively. The electroanalytical procedure comprises two steps: the chemical accumulation of the analyte under open-circuit conditions followed by the electrochemical detection of the preconcentrated species using differential pulse anodic stripping voltammetry. The different parameters that govern the two steps (accumulation time, concentration of the analyte, composition of the detection medium, potential and duration of electrolysis) were studied in detail. After optimization, a linear response was obtained in the concentration range from 0.1 to 0.7 μM Hg(II). In these conditions, the detection limits of the method were found to be 8.7 × 10−8 and 6.8 × 10−8 M, respectively, for the amine- and thiol-functionalized clays, on the basis of a signal-to-noise ratio of 3. The effect of potential interference on the determination of Hg(II) by the carbon paste electrode modified with the thiol-functionalized clay was also studied and the applicability of the method to real sample analysis was evaluated. 相似文献
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Remigijus Jušk?nas Ignas ValsiūnasVitalija Jasulaitien? Vidas Pakštas 《Electrochimica acta》2002,47(26):4239-4243
An effect of cathodic charging conditions on the amount of the β-NiHx phase formed in nickel electrode in alkaline solutions was studied by means of X-ray diffraction technique. Electrolytic nickel coatings on copper substrate were hydrogenated in KOH, NaOH, LiOH and NH4OH solutions containing promoters such as As2O3, Sb and GeO2. Dependences of the β-NiHx phase volume fraction on the promotor concentration, charging current density and charging duration were studied. Optimal values of these charging conditions parameters were determined. The volume fraction of the β-NiHx phase amounted up to ∼56% of 10 μm thick nickel coating. The quantity of nickel hydride did not depend on the alkali and its concentration. Promoters were arranged in the following order of effectiveness in causing nickel hydride formation: S>As>Sb>Ge. It was suggested that NiAs type compounds could take part in the nickel hydride formation. 相似文献
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Ultra Wide Band (UWB) impulse radio, promises to be suitable for short-range, low-power, low cost and high data rate applications.
While most UWB research is concentrating on the physical layer, little research has been published on the link layer. The
fundamental operations in the link layer need to take into account the specifics of impulse radio and also the particular
features of ad hoc networks. A novel self-organizing link layer protocol based on time hopping impulse radio, called SDD,
was proposed by the authors. This protocol is a collision-free mechanism that enables the devices to discover neighboring
nodes and arrange the access to communication resources shared among the nodes. In this paper, some issues related to the
self-organizing link layer based on UWB impulse radio are investigated and addressed. The SDD protocol is further developed
and specified in detail. The simulations are carried out using GloMoSim simulation environment. An SDD module has been developed
and embedded in the simulator. Results show that the SDD protocol can work properly and efficiently in a single-hop ad hoc
network. 相似文献
10.
We report on a system for multi-touch tracking from linescan cameras using particle filters. We show that a particle filter incorporating a local search element is almost as accurate as an exhaustive search algorithm and is significantly faster as the number of touches increases. The system achieves over 95 % correct tracking with an error tolerance of 1 mm for up to eight touches. 相似文献