Characterization of H5N1 highly pathogenic avian influenza virus strains isolated from migratory waterfowl in Mongolia on the way back from the southern Asia to their northern territory

AbstractH5N1 highly pathogenic avian influenza (HPAI) viruses were isolated from dead wild waterfowl at Khunt, Erkhel, Doityn Tsagaan, Doroo, and Ganga Lakes in Mongolia in July 2005, May 2006, May 2009, July 2009, and May 2010, respectively. The isolates in 2005 and 2006 were classified into genetic clade 2.2, and those in 2009 and 2010 into clade 2.3.2. A/whooper swan/Mongolia/6/2009 (H5N1) experimentally infected ducks and replicated systemically with higher mortality than that of the isolates in 2005 and 2006. Intensive surveillance of avian influenza in migratory waterfowl flying from their nesting lakes in Siberia to Mongolia in every autumn indicate that HPAI viruses have not perpetuated at their nesting lakes until 2009. The present results demonstrate that wild waterfowl were sporadically infected with H5N1 HPAI viruses prevailing in domestic poultry in the southern Asia and died in Mongolia on the way back to their northern territory in spring

Differential potential for envelope glycoprotein-mediated steric shielding of host cell surface proteins among filoviruses

The viral envelope glycoprotein (GP) is thought to play important roles in the pathogenesis of filovirus infection. It is known that GP expressed on the cell surface forms a steric shield over host proteins such as major histocompatibility complex class I and integrin pi, which may result in the disorder of cell-to-cell contacts and/or inhibition of the immune response. However, it is not clarified whether this phenomenon contributes to the pathogenicity of filoviruses. In this study, we found that the steric shielding efficiency differed among filovirus strains and was correlated with the difference in their relative pathogenicities. While the highly glycosylated mucin-like region of GP was indispensable, the differential shielding efficiency did not necessarily depend on the primary structure of the mucin-like region, suggesting the importance of the overall properties (e.g., flexibility and stability) of the GP molecule for efficient shielding of host proteins. (C) 2013 Elsevier Inc. All rights reserved

Experimental and Theoretical Elucidation of Metal‐Free Sulfur and Nitrogen Co‐Doped Porous Carbon Materials with an Efficient Synergistic Effect on the Oxygen Reduction Reaction

Abstract Metal‐free carbon‐based catalysts have attracted significant attention owing to their unique electronic structure and excellent catalytic activity for the oxygen reduction reaction (ORR). Recently, several heteroatom‐doped carbon catalysts with ORR performances comparable with those of state‐of‐the‐art Pt‐based catalysts have been reported. However, the intrinsic influence of heteroatoms on the catalytic activity has not been thoroughly investigated to date. This paper reports porous carbons co‐doped with N and S, prepared using an ion‐exchange resin and tetramethylammonium cations, with an onset potential of 0.93 V versus reversible hydrogen electrode (RHE) and a half‐wave potential of 0.79 V versus RHE. First‐principles calculations reveal that the change in the atomic charge caused by the co‐doping of N and S is important for inducing a high ORR activity. This paper presents a rational synthetic strategy for metal‐free catalysts and provides fundamental insights into their electrocatalysis

Fluoropyridine-medicated zeolite templating method for N/F co-doped carbon with high electrocatalytic performance on oxygen reduction reaction

Heteroatom-doped carbons have attracted increasing attention in recent years as inexpensive high-performance electrocatalytic materials owing to their electrical properties. A precisely controlled synthesis method for heteroatom-doped carbons is important to improve their performance and expand their applications. In this study, we developed a fluoropyridine-medicated zeolite templating method for Nitrogen/Fluorine (N/F) co-doped carbons. The N/F co-doped carbons showed better catalytic performances for oxygen reduction reaction (ORR) than N-doped carbon prepared using pyridine. In particular, the optimized N/F co-doped carbon exhibited a higher half-wave potential (0.87 V vs. RHE) than commercial Pt-loaded carbon black and N/F co-doped carbons reported in the literature. The comparative studies using various N/F co-doped carbons revealed that semi-ionic bonded C-F might improve ORR activity. In contrast, the contribution from covalent or ionic C-F to improving ORR activity would be negligible

Utilization of Deposited Coke on Zeolites During the Catalytic Cracking of Nitrogen-Containing Polymer for the Oxygen Reduction Reaction

This work focuses on the development of a new method to utilize deposited coke on zeolite catalysts, formed during the plastic waste cracking. Nitrogen-doped carbon catalysts are prepared using nylon-66 and Zn2+ ion-exchanged ZSM-5 zeolites. After the cracking reaction, nitrogen-doped carbon materials are obtained by removing zeolites from zeolite/coke composites using base and acid treatment. The synthesized N-doped carbon using Zn2+ type ZSM-5 zeolites exhibits higher catalytic performance on the oxygen reduction reaction (ORR) with an onset potential of 0.95 V (vs RHE) and a half-wave potential of 0.80 V (vs RHE) than that using H+ type ZSM-5 zeolites. The characterization revealed that the evaporation of Zn2+ in zeolites significantly enhanced the porosity of N-doped carbon. Moreover, the aromatization and poly-cyclization reactions promoted the generation of highly active edge Valley-N sites, leading to their outstanding activity on ORR. This work provides new directions for the utilization of deposited coke on zeolites.This work was the result of using research equipment shared in MEXT Project for promoting public utilization of advanced research infrastructure (Program for supporting construction of core facilities) Grant Number JPMXS0441200023. A part of this work was supported by “ARIM Project of the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), Grant No. JPMXP1222OS0034” at the Research Center for Ultra-High Voltage Electron Microscopy (Nanotechnology Open Facilities) in Osaka University. Part of this work was also supported by PID2021-123079OB-I00 project funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”