Unraveling Molecular Fingerprints of Catalytic Sulfur Poisoning at the Nanometer Scale with Near-Field Infrared Spectroscopy.

Fundamental understanding of catalytic deactivation phenomena such as sulfur poisoning occurring on metal/metal-oxide interfaces is essential for the development of high-performance heterogeneous catalysts with extended lifetimes. Unambiguous identification of catalytic poisoning species requires experimental methods simultaneously delivering accurate information regarding adsorption sites and adsorption geometries of adsorbates with nanometer-scale spatial resolution, as well as their detailed chemical structure and surface functional groups. However, to date, it has not been possible to study catalytic sulfur poisoning of metal/metal-oxide interfaces at the nanometer scale without sacrificing chemical definition. Here, we demonstrate that near-field nano-infrared spectroscopy can effectively identify the chemical nature, adsorption sites, and adsorption geometries of sulfur-based catalytic poisons on a Pd(nanodisk)/Al2O3 (thin-film) planar model catalyst surface at the nanometer scale. The current results reveal striking variations in the nature of sulfate species from one nanoparticle to another, vast alterations of sulfur poisoning on a single Pd nanoparticle as well as at the assortment of sulfate species at the active metal-metal-oxide support interfacial sites. These findings provide critical molecular-level insights crucial for the development of long-lifetime precious metal catalysts resistant toward deactivation by sulfur.

Relationship Between Polycystic Ovarian Morphology and Ectopic Pregnancy.

BACKGROUND: The purpose of the current study was to investigate the presence of polycystic ovarian morphology (PCOM) in patients with ectopic pregnancy (EP) and to find out the value of sonographic appearance of ovaries on the earlier diagnosis of EP. METHODS: In the current case-control study, thirty five patients with EP were recruited to evaluate ovarian sonographic morphology whereas 35 gestational age-matched women with healthy intrauterine pregnancy (IUP) were the controls. After ovarian sonography, ultrasound images were analyzed offline for ovarian area, ovarian volume, follicle number per cross section, and follicle distribution pattern. A questionnaire about the presence of hirsutism and menstrual irregularity prepared as well. Student's t-test or Mann-Whitney U test were used to compare continuous variables between 2 groups and categorical data were evaluated by using Chi-square or Fisher's exact test, where appropriate. Multiple logistic regression was used to find out the risk factors for EP. RESULTS: Mean gravidity and parity were significantly higher in the EP group compared to IUP group (p<0.05). PCOM was found to be significantly higher in the study group (51.4% vs. 20%, p=0.006). Logistic regression analysis showed that multiparity (OR=8.635; 95% CI, 1.653-45.104) and PCOM image on ultrasound (OR=19.081; 95% CI, 1.139-319.560) were found to be significantly associated with EP. CONCLUSION: PCOM is more prevalent among women diagnosed with EP. This study demonstrates that PCOM assessed by transvaginal ultrasound may reflect EP in women with EP suspicion and may therefore serve as a clinical marker to assess EP.