No abstract

The effect of the curvature of the carbon lattice is discussed taking into account NMR data on various fluorinated carbons including C(60) fullerenes, single, double and multiwall carbon nanotubes. Graphite fluorides and highly fluorinated fullerenes are used as limit model compounds for planar and spherical geometries, respectively. The curvature results in a weakening of the C-F bonding covalence. First of all, various highly fluorinated fullerenes with increasing F/C molar ratio were prepared by treatment with pure gaseous fluorine. A preliminary study using XRD, EPR and IR spectroscopy confirms that the highest fluorination level can be reached either at 133 or at 300 degrees C. In order to extract the correlation between fluorine and carbon atoms and the C-F bond length, specific sequences such as solid echo, two-dimensional (19)F -->(13)C cross polarization wide-line separation and inverse (19)F -->(13)C cross polarization were also used for fluorinated C(60).

Diarrhoeagenic Escherichia coli (DEC) infection is a major health problem in developing countries. The prevalence and characteristics of DEC have not been thoroughly investigated in China. Consecutive faecal specimens from outpatients with acute diarrhoea in nine sentinel hospitals in southeastern China were collected from July 2009 to June 2011. Bacterial and viral pathogens were detected by culture and RT‐PCR, respectively. DEC isolates were further classified into five pathotypes using multiplex PCR. The O/H serotypes, sequence types (STs) and antimicrobial susceptibility profiles of the DEC isolates were determined. A total of 2466 faecal specimens were collected, from which 347 (14.1%) DEC isolates were isolated. DEC was the dominant bacterial pathogen detected. The DEC isolates included 217 EAEC, 62 ETEC, 52 EPEC, 14 STEC, one EIEC and one EAEC/ETEC. O45 (6.6%) was the predominant serotype. Genotypic analysis revealed that the major genotype was ST complex 10 (87, 25.6%). Isolates belonging to the serogroups or genotypes of O6, O25, O159, ST48, ST218, ST94 and ST1491 were highly susceptible to the majority of antimicrobials. In contrast, isolates belonging to O45, O15, O1, O169, ST38, ST226, ST69, ST31, ST93, ST394 and ST648 were highly resistant to the majority of antimicrobials. DEC accounted for the majority of bacterial pathogens causing acute diarrhoea in southeastern China, and it is therefore necessary to test for all DEC, not only the EHEC O157:H7. Some serogroups or genotypes of DEC were highly resistant to the majority of antimicrobials. DEC surveillance should be emphasized.