Pseudopeptidic ligands: exploring the self-assembly of isopthaloylbisglycine (H2IBG) and divalent metal ions

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Toward a simulation approach for alkene ring-closing metathesis : scope and limitations of a model for RCM

A published model for revealing solvent effects on the ring-closing metathesis (RCM) reaction of di-Et diallylmalonate 7 has been evaluated over a wider range of conditions, to assess its suitability for new applications. Unfortunately, the model is too flexible and the published rate consts. do not agree with exptl. studies in the literature. However, by fixing the values of important rate consts. and restricting the concn. ranges studied, useful conclusions can be drawn about the relative rates of RCM of different substrates, precatalyst concn. can be simulated accurately and the effect of precatalyst loading can be anticipated. Progress has also been made toward applying the model to precatalyst evaluation, but further modifications to the model are necessary to achieve much broader aims

Impact of drone route geometry on information collection in wireless sensor networks

The recent technological evolution of drones along with the constantly growing maturity of its commercialization, has led to the emergence of novel drone-based applications within the field of wireless sensor networks for information collection purposes. In such settings, especially when deployed in outdoor environments with limited external control, energy consumption and robustness are challenging problems for the system's operation. In the present paper, a drone-assisted wireless sensor network is studied, the aim being to coordinate the routing of information (among the ground nodes and its propagation to the drone), investigating several drone trajectories or route shapes and examining their impact on information collection (the aim being to minimize transmissions and consequently, energy consumption). The main contribution lies on the proposed algorithms that coordinate the communication between (terrestrial) sensor nodes and the drone that may follow different route shapes. It is shown through simulations using soft random geometric graphs that the number of transmitted messages for each drone route shape depends on the rotational symmetry around the center of each shape. An interesting result is that the higher the order of symmetry, the lower the number of transmitted messages for data collection. Contrary, for those cases that the order of symmetry is the same, even for different route shapes, similar number of messages is transmitted. In addition to the simulation results, an experimental demonstration, using spatial data from grit bin locations, further validates the proposed solution under real-world conditions, demonstrating the applicability of the proposed approach. © 202

Synchronization of data measurements in wireless sensor networks for IoT applications

Time synchronization is a challenging problem for wireless sensor networks, as clocks deviate and sensor measurements need to be associated with the reference clock time they took place. In Internet of Things (IoT) environments, crucial factors like energy, robustness, limited capabilities and extreme ambient conditions (e.g., when nodes are deployed in soil) lead researchers to consider various schemes of relaxing the synchronization requirements. In this paper, a lightweight synchronization algorithm is proposed for wireless sensor networks, focusing on synchronizing the particular measurements in a per hop basis as they are transmitted encapsulated in data packets towards the sink node. The aim is to synchronize data measurements instead of node clocks, and thereby, induce negligible extra overhead, since extra messages and re-synchronization periods are not required. The analysis of the proposed algorithm regarding time deviation and the corresponding variance shows a dependency on residual time (i.e., the particular time period a data packet remains within a node), distance (i.e., the number of hops between the sink node and the sensor node that sensed the data in the first place) and the average skew deviation value. Various simulations were carried out aiming to exhibit thoroughly the effectiveness of the proposed algorithm, as well as the validation of the analytical results. Findings from a comparison between the proposed algorithm and a traditional synchronization algorithm along with their simulation results show that the proposed algorithm can be a suitable solution for demanding environments like IoT systems. © 2019 Elsevier B.V