[Primary study on the relationship between high-risk HPV infection and vaginal cervical microbiota]

Objective: To understand characteristics of vaginal cervical microbiota in high-risk HPV (hrHPV) infected women and to uncover the relationship between hrHPV infection and vaginal cervical microbiota. Methods: All participants were randomly selected from Peking University First Hospital from September to October of 2017, including 5 subjects of control group, 5 cases of HPV16/18 group, 5 cases of other hrHPV infected group and 3 cases of cervical squamous carcinoma group. All subjects were required to fill in a questionnaire, and cervical and vaginal discharges were separately collected for microscopic examination and new generation sequencing targeting the variable region (V3-V4) of bacterial 16S rRNA gene. Results: Vaginal microbiota analysis: (1) 6 major phylum were found in vaginal microbiota:Firmicutes, Bacteroidetes, Fusobacteria, Actinobacteria, Tenericutes and Proteobacteria. Firmicutes contributed to the majority of normal vaginal flora, Bacteroidetes and Fusobacteria increased in hrHPV infected ones, while Fusobacteria showed significant difference in cervical carcinoma group. (2) Lactobacillus occupied most of normal vaginal flora while genus like Gardnella, Prevotella, Atopobium, Megasphaera and Sneathia increased in hrHPV infected subjects, Sneathia showed significant difference in cervical carcinoma group. (3) No significant difference had been calculated in Alpha diversity of four groups (P=0.073) . Cervical microbiota analysis: (1) Microbial diversity of cervical microbiota was higher than that of vaginal microbiota. (2) Significant difference had been found in Alpha diversity of four groups (P=0.046) . (3) Proteobacteria in normal cervical flora was much more than that in vagina, and Proteobacteria increased significantly in hrHPV infected cervical discharge. (3) Chlamydia increased significantly in cervical carcinoma group. Conclusions: The diversity of cervical microbiota is higher than that of vaginal microbiota. Change in cervical microbiota is more obvious than that of vagina in hrHPV infected subjects. Fusobacteria-Sneathia and Chlamydia significantly increase in cervical carcinoma group. Proteobacteria might relate to hrHPV infection.

Density functional theory study of oxygen reduction reaction on Pt/Pd3Al(111) alloy electrocatalyst

Developing efficient catalysts for the oxygen reduction reaction (ORR) to reduce cathode Pt loading without sacrificing the performance has been under intensive research. Herein, by using density functional theory calculations, the activity and stability of a Pt monolayer supported on Pd3Al(111) as the ORR catalyst have been systematically studied. The simulations demonstrate that due to alloying, the ORR intermediates bind weakly on Pt/Pd3Al(111) with optimal adsorption energy of O and OH. By considering the elemental ORR steps, the ORR mechanism is predicted to be an OOH dissociation mechanism. The rate determining step is OOH dissociation with a reaction barrier of 0.37 eV, lower than the corresponding value on Pt/Pt3Al(111) and Pt(111), indicating the superior activity of Pt/Pd3Al(111). Even considering the unfeasible H adsorption under high potential, the ORR mechanism on Pt/Pd3Al(111) would proceed via O2 hydration, OOH hydration, H2O formation, and H2O desorption, indicating a good ORR electrocatalyst. Furthermore, stability was evaluated by calculating the alloy formation energy and the electrochemical potential shift of surface Pt dissolution. The exceptionally negative alloy formation energy of Pd3Al and the positive dissolution potential shift of the surface Pt atoms show the enhanced durability of Pt/Pd3Al(111). The improved activity, in combination with its enhanced stability, makes the novel ternary alloy electrocatalyst very promising for development of new cathode catalysts for fuel cells.

A bifunctional two dimensional TM3(HHTP)2 monolayer and its variations for oxygen electrode reactions

To achieve renewable energy technologies, low-cost electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are required to replace Pt and IrO₂/RuO₂ catalysts.

The segregation resistance of the Pt2ML/Os/Pd3Al sandwich catalyst for oxygen reduction reaction: a density functional theory study

Pt_1ML/Pd₃Al, which comprises a Pd₃Al core protected by a Pt monolayer, may experience Al dealloying because of the strong affinity of Al toward O. To circumvent this issue, the Pt_2ML/Os/Pd₃Al catalyst has been designed to suppress the migration of Al by inserting an Os monolayer at the interface between the Pd₃Al core and two Pt monolayers. On the basis of segregation energies, Al leaching from the core to the 1st layer is determined to be endothermic even under O coverage, indicating an energetic preference for Al to reside in the core structure. The Pt_2ML/Os/Pd₃Al catalyst benefits from the energetic disadvantage of the inward movement of Os and the presence of the 2 ML Pt layer. As an ORR electrocatalyst, the relatively weak adsorption ability of Pt_2ML/Os/Pd₃Al suggests improved ORR activity. Finally, a representative OOH association mechanism with low reaction barriers of 0.46, 0.31, 0.38 and 0.41 eV for the OOH formation, OOH dissociation, OH formation and H₂O formation steps suggests that the catalyst can effectively activate the O-O bond and eliminate OH, which can act as a catalytic poison. These findings suggest the design of stable sandwich catalysts as potential candidates for ORR electrocatalysis.

Molecular analysis of the relationship between specific vaginal bacteria and bacterial vaginosis metronidazole therapy failure

Bacterial vaginosis frequently persists, even after treatment. The role of some strains of bacteria associated with bacterial vaginosis treatment failure remains poorly defined. The aim of our study was to define the risk of bacterial vaginosis treatment failure, including pre-treatment detection of specific vaginal bacteria. Bacterial vaginosis is present when the Nugent score is ≥7 and the modified Amsel criteria is positive. Women with bacterial vaginosis were treated with intravaginal metronidazole gel nightly for 5 nights. The 454 pyrosequencing method was used to detect bacteria in vaginal fluid. By univariate analysis, a history of bacterial vaginosis, intrauterine device use and the presence of Facklamia, Corynebacterium and Veillonella were significantly associated with bacterial vaginosis treatment failure. Lactobacillus crispatus, Lactobacillus pentosus and Megasphaera were significantly associated with curing bacterial vaginosis. After logistic regression analysis and detection of these bacteria for test-of-cure, we found that women who had a history of bacterial vaginosis had a higher incidence of bacterial vaginosis treatment failure, whereas women with L. crispatus had a lower incidence of treatment failure. Post-treatment sexual activity was not associated with the treatment effect. Our data suggested that treatment failure may be not caused by drug resistance. Rather, it has a closer relationship with the failed restoration of lactobacilli.