Acylase (AC) was immobilized and stabilized on carboxylated polyaniline nanofibers (cPANFs) for the development of antifouling nanobiocatalysts with high enzyme loading and stability. AC was immobilized via three different approaches: covalent attachment (CA), enzyme coating (EC), and magnetically separable enzyme precipitate coating (Mag-EPC). The enzyme activity per unit weight of cPANFs with Mag-EPC was 75 and 300 times higher than that of those with CA and EC, respectively, representing improved enzyme loading in the form of Mag-EPC. After incubation under shaking at 200 rpm for 20 days, Mag-EPC maintained 55% of its initial activity, whereas CA and EC showed 3 and 16% of their initial activities, respectively. The antifouling of highly loaded and stable Mag-EPC against the biofouling/biofilm formation of Pseudomonas aeruginosa was tested under static- and continuous-flow conditions. Biofilm formation in the presence of 40 μg/mL Mag-EPC under static condition was 5 times lower than that under control condition with no addition of Mag-EPC. Under continuous membrane filtration, Mag-EPC delayed the increase of transmembrane pressure (TMP) more effectively as the concentration of added Mag-EPC increased. When separating Mag-EPC and membranes in two different vessels under internal circulation of the culture solution, Mag-EPC maintained a higher permeability than the control with no Mag-EPC addition. It was also confirmed that the addition of Mag-EPC reduced the generation of N-acyl homoserine lactone (AHL) autoinducers. This result reveals that the inhibition of biofilm formation and biofouling in the presence of Mag-EPC is due to the hydrolysis of AHL autoinducers, catalyzed by the immobilized and stabilized AC in the form of Mag-EPC. Mag-EPC of AC with high enzyme loadings and improved stability has demonstrated its great potential as an antifouling agent by reducing biofilm formation and membrane biofouling based on "enzymatic quorum quenching" of autoinducers.

Abstract. Minimizing energy consumption is crucial for portable wireless stations because they operate on a limited battery supply. For example, the IEEE 802.11 standard includes a mechanism called power-saving mode (PSM), which allows a network interface on a mobile station to enter a sleep state whenever possible to reduce its energy consumption. We consider a generic wireless system composed of an access point (AP) and several stations that offer a PSM to its users. Our PSM is APcentric (i.e., gives control to the AP) to save more energy. We formulate a downlink scheduling optimization problem aimed at saving energy and propose two heuristic scheduling policies to solve it. One of these policies is non-work-conserving, and it offers an interesting tradeoff between energy consumption and user performance.We also study and show how the length of the Beacon Period (BP) has a significant impact on the energy and the delay performance of wireless stations. For each of our two scheduling policies, we derive simple approximate formulas for the length of the BP that minimizes the energy consumption and for the relationship between the delay performance and the length of the BP. Assuming the maximum allowable average packet delay is given by the users as a QoS requirement, we illustrate how to dimension the length of the BP for the two schedulers we have proposed and show that we can achieve significant energy savings while meeting the delay constraint with the non-work conserving one in many cases. Extensive simulations show that a fine-tuning of the length of the BP as well as well-designed scheduling disciplines is essential to saving energy in wireless stations.

In order to efficiently reduce the amount of electricity usage in residential areas, the demand response (DR) of consumers is of importance. The in-home display (IHD) system provides energy monitoring information for the consumer DR. Considering the building structures and the existing automatic meter systems, several types of IHD systems have recently been developed based on the 2.4GHz ZigBee radio, the power line communication technique, and the sub 1-GHz narrow-bandwidth radios. In this paper, five cases of IHD system developments and implementations are introduced and their technologies including network architectures compared 1 .

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