With the advent of a number of wireless network technologies such as WCDMA and WLAN, current mobiles are equipped with multiple network interfaces, so called Multi-Mode Terminal (MMT). MMTs are capable to access different kinds of networks by performing a vertical handover between heterogeneous wireless networks, where during the idle state, the MMTs consume a lot of energy since their WLAN interface must wake up for listening to periodical beacons. However, previous studies on the vertical handover did not address how to select the optimal interface taking into account the characteristics of MMTs, especially energy consumption. Therefore, in this paper, we propose an energy-efficient interface selection scheme for MMTs in the integrated WLAN and cellular networks. The proposed interface selection scheme takes advantage of existing out-ofband paging channel of cellular networks, so that the WLAN interface can be completely turned off during the idle state leading to reduction in energy consumption. Simulation results show that the proposed scheme outperforms conventional approaches in terms of energy consumption with reduced signaling overhead and handover delay.

Lactic acid bacteria (LAB) quickly attenuate or are killed during the freeze-drying process and storage. The effect of some natural polysaccharides, which are known as potent antitumor and immunomodulating substances, on the viability of the LAB, Lactobacillus acidophilus and Bifidobacterium breve, on freeze-drying and storage were investigated. Among the polysaccharides tested, red ginseng polysaccharide (RGP) and chitosan significantly inhibited the cell death of the LAB during freeze-drying, and fucoidan and RGP most potently protected the cell death of the LAB during storage. The stabilities of the LAB on the addition of RGP and fucoidan were comparable to that of skimmed milk. However, white ginseng polysaccharide (WGP) did not promote storage stability. When 5% skimmed milk/5% RGP treated LAB were freeze-dried and stored, their viabilities were found to be significantly higher those treated with 5% or 10% RGP. The stabilizing effect of 5% RGP/5% skimmed milk during LAB freeze-drying and storage stability was comparable to that of treatment with 10% skimmed milk. Based on these findings, we believe that RGP beneficially improves the stability of LAB during the freeze-dry process and storage.

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