Abstract-Energy consumption is one of the most critical protocol properties in a wireless sensor network. Therefore, a precise energy model is required for the evaluation of protocols. In addition to evaluation, an energy model can also be used for on-line energy accounting. After processing user queries, nodes aware of the energy model can send an energy bill towards the network's data sink. This allows the user to adjust future queries to be more energy efficient. The contribution of this paper is twofold: First, a theoretical energy model based on simple finite automata is presented. This model can be used for online accounting, simulation and generation of a-priori knowledge. Second, the proposed theoretical model is backed up by practical measurements using a new measurement device called SNMD, which also offers management functions for sensor-net testbeds. Therewith, output of the theoretical model can be compared to and validated against by real-world measurements.

The development of efficient and sustainable electrochemical systems able to provide clean-energy fuels and chemicals is one of the main current challenges of materials science and engineering. Over the last decades, significant advances have been made in the development of robust electrocatalysts for different reactions, with fundamental insights from both computational and experimental work. Some of the most promising systems in the literature are based on expensive and scarce platinum-group metals; however, natural enzymes show the highest per-site catalytic activities, while their active sites are based exclusively on earth-abundant metals. Additionally, natural biomass provides a valuable feedstock for producing advanced carbonaceous materials with porous hierarchical structures. Utilizing resources and design inspiration from nature can help create more sustainable and cost-effective strategies for manufacturing cost-effective, sustainable, and robust electrochemical materials and devices. This review spans from materials to device engineering; we initially discuss the design of carbon-based materials with bioinspired features (such as enzyme active sites), the utilization of biomass resources to construct tailored carbon materials, and their activity in aqueous electrocatalysis for water splitting, oxygen reduction, and CO 2 reduction. We then delve in the applicability of bioinspired features in electrochemical devices, such as the engineering of bioinspired mass transport and electrode interfaces. Finally, we address remaining challenges, such as the stability of bioinspired active sites or the activity of metal-free carbon materials, and discuss new potential research directions that can open the gates to the implementation of bioinspired sustainable materials in electrochemical devices.

Ultrathin amorphous silica membranes with embedded organic molecular wires (oligo(pphenylenevinylene), 3 aryl units) provide chemical separation of incompatible catalytic environments of CO 2 reduction and H 2 O oxidation while maintaining electronic and protonic coupling between them. For an efficient nanoscale artificial photosystem, important performance criteria are high rate and directionality of charge flow. Here, the visible light induced charge flow from anchored Ru bipyridyl light absorber across the silica nanomembrane to Co 3 O 4 water oxidation catalyst is quantitatively evaluated by photocurrent measurements. Charge transfer rates increase linearly with wire density, with 5 nm -2 identified as optimal target. Accurate measurement of wire and light absorber densities is accomplished by the polarized FT-IRRAS method. Guided by DFT calculations, four wire derivatives featuring electron donating (methoxy) and withdrawing groups (sulfonate, perfluoro-phenyl) with HOMO potentials ranging from 1.48 to 0.64 V vs. NHE were synthesized and photocurrents evaluated. Charge transfer rates increase sharply with increasing driving force for hole transfer from the excited light absorber to the embedded wire, followed by a decrease as the HOMO potential of the wire moves beyond the Co 3 O 4 valence band level towards more negative values, pointing to an optimal wire HOMO potential around 1.3 V vs NHE. Comparison with photocurrents of samples without nanomembrane indicates that silica layers with optimized wires are able to approach undiminished electron flux at typical solar intensities. Combined with the established high proton conductivity and small molecule blocking property, the charge transfer measurements demonstrate that oxidation and reduction catalysis can be efficiently integrated on the nanoscale under separation by an ultrathin silica membrane.

Energy is the most limiting resource in sensor networks. This is particularly true for dynamic sensor networks in which the sensor-net application changes its hardware utilization over time. In such networks, offline estimation of energy consumption can not take into account all changes to the application's hardware utilization profile and thus invariably returns inaccurate estimates. Online accounting methods offer more precise energy consumption estimates. In this paper we describe an online energy accounting system for TinyOS consisting of two components: An energy-estimation system to collect information about energy consumption of a node and an energy-container system that allows an application to collect energy-consumption information about its tasks individually. The evaluation with TinyDB shows that it is both accurate and efficient.