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 & Nanofiber. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

Novel Receiver Design for the Cooperative Relaying System With Non-Orthogonal Multiple Access

Abstract: In this letter, a novel detection scheme for the cooperative relaying system using non-orthogonal multiple access (CRS-NOMA) is proposed. For CRS-NOMA, the source simultaneously transmits two symbols by employing the superposition code, and the relay decodes and forwards the symbol with lower allocated power by employing the successive interference cancellation (SIC). In the proposed scheme, the destination jointly decodes two symbols from both the directed signal and the forwarded signal by employing the maximum-ratio combination and another SIC. The ergodic sum rate and the outage performance of the system are investigated. A suboptimal allocation strategy is also designed. Both analysis and simulations reveal the advantages of the proposed scheme.

Significant vertical phase separation in solvent-vapor-annealed poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) composite films leading to better conductivity and work function for high-performance indium tin oxide-free optoelectronics.

Abstract: In the present study, a novel polar-solvent vapor annealing (PSVA) was used to induce a significant structural rearrangement in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films in order to improve their electrical conductivity and work function. The effects of polar-solvent vapor annealing on PEDOT:PSS were systematically compared with those of a conventional solvent additive method (SAM) and investigated in detail by analyzing the changes in conductivity, morphology, top and bottom surface composition, conformational PEDOT chains, and work function. The results confirmed that PSVA induces significant phase separation between excess PSS and PEDOT chains and a spontaneous formation of a highly enriched PSS layer on the top surface of the PEDOT:PSS polymer blend, which in turn leads to better 3-dimensional connections between the conducting PEDOT chains and higher work function. The resultant PSVA-treated PEDOT:PSS anode films exhibited a significantly enhanced conductivity of up t...

Nitrogen-doped graphene encapsulated FeCoMoS nanoparticles as advanced trifunctional catalyst for water splitting devices and zinc–air batteries

Abstract: Emerging demands for the highly active, durable, and cost-effective trifunctional catalysts for overall water splitting and metal–air batteries in the scientific community. Herein, a novel strategy is demonstrated for the rational design of hierarchical iron cobalt molybdenum sulfide nanoflower encapsulated in nitrogen doped graphene (FeCoMoS@NG) through a facile, cost-effective, and single-step in-situ hydrothermal process. Owing to its hierarchical nanostructures, larger specific surface area, and exclusive porous networks, the optimal FeCoMoS@NG shows excellent catalytic activities for OER ƞ10 = 238 mV, HER ƞ10 = 137 mV, and ORR (0.83 V vs RHE). Most significantly, FeCoMoS@NG||FeCoMoS@NG water splitting device achieves a cell voltage of 1.58 V at 10 mA cm−2. Furthermore, FeCoMoS@NG based zinc–air battery endows a high power density of 118 mW cm−2, and overall water splitting was successfully driven by FeCoMoS@NG based zinc–air battery. This work provides new pathway for designing highly active and durable multifunctional catalysts for energy conversion and storage applications.

Facile nucleophilic fluorination reactions using tert-alcohols as a reaction medium: significantly enhanced reactivity of alkali metal fluorides and improved selectivity.

Abstract: Although protic solvents are generally not preferred for nucleophilic displacement reactions because of their partial positive charge and hydrogen-bonding capacity that solvate the nucleophile and reduce its reactivity, we recently reported a remarkably beneficial effect of using tertiary alcohols as a reaction media for nucleophilic fluorination with alkali metal fluorides, as well as fluorine-18 radiolabeling with [18F]fluoride ion for the preparation of PET radiopharmaceuticals. In this work, we investigate further the influence of the tert-alcohol reaction medium for nucleophilic fluorination with alkali metal fluorides by studying various interactions among tert-alcohols, the alkali metal fluoride (CsF), and the sulfonyloxy substrate. Factors such as hydrogen bonding between CsF and the tert-alcohol solvent, the formation of a tert-alcohol solvated fluoride, and hydrogen bonding between the sulfonate leaving group and the tert-alcohol appear to contribute to the dramatic increase in the rate of the nucleophilic fluorination reaction in the absence of any kind of catalyst. We found that fluorination of 1-(2-mesyloxyethyl)naphthalene (5) and N-5-bromopentanoyl-3,4-dimethoxyaniline (8) with Bu(4)N(+)F(-) in a tert-alcohol afforded the corresponding fluoro products in much higher yield than obtained by the conventional methods using dipolar aprotic solvents. The protic medium also suppresses formation of byproducts, such as alkenes, ethers, and cyclic adducts.