Chonbuk National University

About: Chonbuk National University is a education organization based out in Jeonju, South Korea. It is known for research contribution in the topics: Apoptosis & Graphene. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

Multipath Routing in Wireless Sensor Networks: Survey and Research Challenges

Abstract: A wireless sensor network is a large collection of sensor nodes with limited power supply and constrained computational capability. Due to the restricted communication range and high density of sensor nodes, packet forwarding in sensor networks is usually performed through multi-hop data transmission. Therefore, routing in wireless sensor networks has been considered an important field of research over the past decade. Nowadays, multipath routing approach is widely used in wireless sensor networks to improve network performance through efficient utilization of available network resources. Accordingly, the main aim of this survey is to present the concept of the multipath routing approach and its fundamental challenges, as well as the basic motivations for utilizing this technique in wireless sensor networks. In addition, we present a comprehensive taxonomy on the existing multipath routing protocols, which are especially designed for wireless sensor networks. We highlight the primary motivation behind the development of each protocol category and explain the operation of different protocols in detail, with emphasis on their advantages and disadvantages. Furthermore, this paper compares and summarizes the state-of-the-art multipath routing techniques from the network application point of view. Finally, we identify open issues for further research in the development of multipath routing protocols for wireless sensor networks.

Overexpression of SIRT1 Protects Pancreatic β-Cells Against Cytokine Toxicity by Suppressing the Nuclear Factor-κB Signaling Pathway

Abstract: OBJECTIVE—SIRT1, a class III histone/protein deacetylase, is known to interfere with the nuclear factor-κB (NF-κB) signaling pathway and thereby has an anti-inflammatory function. Because of the central role of NF-κB in cytokine-mediated pancreatic β-cell damage, we postulated that SIRT1 might work in pancreatic β-cell damage models. RESEARCH DESIGN AND METHODS—RINm5F (RIN) cells or isolated rat islets were treated with interleukin-1β and interferon-γ. SIRT1 was activated by resveratrol, a pharmacological activator, or ectopic overexpression. The underlying mechanisms of SIRT1 against cytokine toxicity were further explored. RESULTS—Treatment of RIN cells with cytokines induced cell damage, and this damage was well correlated with the expression of the inducible form of nitric oxide (NO) synthase (iNOS) and NO production. However, SIRT1 overexpression completely prevented cytokine-mediated cytotoxicity, NO production, and iNOS expression. The molecular mechanism by which SIRT1 inhibits iNOS expression appeared to involve the inhibition of the NF-κB signaling pathway through deacetylation of p65. In addition, SIRT1 activation by either resveratrol or adenoviral-directed overexpression of SIRT1 could prevent cytokine toxicity and maintain normal insulin-secreting responses to glucose in isolated rat islets. CONCLUSIONS—This study will provide valuable information not only into the mechanisms underlying β-cell destruction but also into the regulation of SIRT1 as a possible target to attenuate cytokine-induced β-cell damage.

Highly Efficient and Bendable Organic Solar Cells with Solution-Processed Silver Nanowire Electrodes

Abstract: Highly efficient and bendable organic solar cells (OSCs) are fabricated using solution-processed silver nanowire (Ag NW) electrodes. The Ag NW films were highly transparent (diffusive transmittance ≈ 95% at a wavelength of 550 nm), highly conductive (sheet resistance ≈ 10 Ω sq−1), and highly flexible (change in resistance ≈ 1.1 ± 1% at a bending radius of ≈200 μm). Power conversion efficiencies of ≈5.80 and 5.02% were obtained for devices fabricated on Ag NWs/glass and Ag NWs/poly(ethylene terephthalate) (PET), respectively. Moreover, the bendable devices fabricated using the Ag NWs/PET films decrease slightly in their efficiency (to ≈96% of the initial value) even after the devices had been bent 1000 times with a radius of ≈1.5 mm.

Preparation and Enhanced Hydrostability and Hydrogen Storage Capacity of CNT@MOF-5 Hybrid Composite

Abstract: Metal−organic frameworks (MOFs) are a rapidly growing class of microporous materials. Various MOFs with tailored nanoporosities have recently been developed as potential storage media for natural gases and hydrogen. However, wider applications have been limited because even atmospheric moisture levels cause MOF instability, and unexpectedly low H2 storage capacity, at 298 K. To overcome these problems, we synthesized a hybrid composite of acid-treated multiwalled carbon nanotubes (MWCNTs) and MOF-5 [Zn4O(bdc)3; bdc = 1,4-benzenedicarbocylate] (denoted MOFMC). In a successful synthesis, well-dispersed MWCNTs in dimethylformamide (DMF) were mixed with a DMF solution of zinc nitrate tetrahydrate and terephthalic acid. The MOFMCs obtained had the same crystal structure and morphology as those of virgin MOF-5, but exhibited a much greater Langmuir specific surface area (increased from 2160 to 3550 m2/g), about a 50% increase in hydrogen storage capacity (from 1.2 to 1.52 wt % at 77 K and 1 bar and from 0.3 to ...