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.

CoxNiy-decorated graphene as novel, stable and super effective non-precious electro-catalyst for methanol oxidation

Abstract: Graphene and alloy structure can overcome the main problem facing the non-precious electro-catalysts; low performance and poor stability. In this study, Co x Ni y -decorated graphene is introduced as novel, super effective and stable non-precious electro-catalyst for methanol oxidation. The obtained results have indicated that utilizing graphene as a support strongly enhances the electro-catalytic activity as the current density was doubled ten times, moreover a negative onset potential (−40 mV vs. Ag/AgCl) was obtained which is a distinct progress in the non-precious electro-catalysts research field. The electronic structure which is controlled by the alloy composition showed strong influence on the electro-catalytic activity; Co 0.2 Ni 0.2 alloy nanoparticles revealed the best performance while Co 0.1 Ni 0.3 nanoparticles were the worst. Due to the alloy structure, the introduced graphene-supported electro-catalyst reveals distinguished stability. In-situ decoration of graphene by Co x Ni y alloy nanoparticle is utilized to produce the introduced electro-catalyst. Briefly, cobalt acetate and nickel acetate were added to the reaction media during graphene preparation using a modified chemical route. Later on, the resultant material was calcined in argon atmosphere at 850 °C. The utilized physicochemical characteristics affirmed formation of multi-layer graphene sheets decorated by solid solution Co x Ni y alloy nanoparticle.

Esophagogastric neoplasms: palliation with a modified gianturco stent.

Abstract: Self-expanding metallic stents of a modified Gianturco design were used for palliative treatment of malignant esophagogastric strictures. Over a 10-month period, 10 stents were placed in nine patients. All patients with severe dysphagia due to malignant strictures in whom all other treatment options had failed were candidates for these stents. Neither extensive length of esophageal involvement nor complete esophageal obstruction was a contraindication. All stents were placed with fluoroscopic guidance without any technical failures or procedural morbidity or mortality. Mild reflux occurred in three patients in whom the stent tubes straddled the distal esophageal sphincter. Five patients were still alive after 1-8 months. The remaining four patients died 6-28 weeks after stent placement; all stents were patent at the time of death. These stents are easy to insert, safe, and reasonably effective for short-term palliative treatment of esophagogastric neoplasms.

A ligand channel through the G protein coupled receptor opsin.

Abstract: The G protein coupled receptor rhodopsin contains a pocket within its seven-transmembrane helix (TM) structure, which bears the inactivating 11-cis-retinal bound by a protonated Schiff-base to Lys296 in TM7. Light-induced 11-cis-/all-trans-isomerization leads to the Schiff-base deprotonated active Meta II intermediate. With Meta II decay, the Schiff-base bond is hydrolyzed, all-trans-retinal is released from the pocket, and the apoprotein opsin reloaded with new 11-cis-retinal. The crystal structure of opsin in its active Ops* conformation provides the basis for computational modeling of retinal release and uptake. The ligand-free 7TM bundle of opsin opens into the hydrophobic membrane layer through openings A (between TM1 and 7), and B (between TM5 and 6), respectively. Using skeleton search and molecular docking, we find a continuous channel through the protein that connects these two openings and comprises in its central part the retinal binding pocket. The channel traverses the receptor over a distance of ca. 70 A and is between 11.6 and 3.2 A wide. Both openings are lined with aromatic residues, while the central part is highly polar. Four constrictions within the channel are so narrow that they must stretch to allow passage of the retinal β-ionone-ring. Constrictions are at openings A and B, respectively, and at Trp265 and Lys296 within the retinal pocket. The lysine enforces a 90° elbow-like kink in the channel which limits retinal passage. With a favorable Lys side chain conformation, 11-cis-retinal can take the turn, whereas passage of the all-trans isomer would require more global conformational changes. We discuss possible scenarios for the uptake of 11-cis- and release of all-trans-retinal. If the uptake gate of 11-cis-retinal is assigned to opening B, all-trans is likely to leave through the same gate. The unidirectional passage proposed previously requires uptake of 11-cis-retinal through A and release of photolyzed all-trans-retinal through B.