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High-resolution X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) were used to characterize IrO2(110) films on Ir(100) with stoichiometric as well as OH-rich terminations. Core-level Ir 4f and O 1s peaks were identified for the undercoordinated Ir and O atoms and bridging and on-top OH groups at the IrO2(110) surfaces. Peak assignments were validated by comparison of the core-level shifts determined experimentally with those computed using DFT, quantitative analysis of the concentrations of surface species, and the measured variation of the Ir 4f peak intensities with photoelectron kinetic energy. We show that exposure of the IrO2(110) surface to O2 near room temperature produces a large quantity of on-top OH groups because of reaction of background H2 with the surface. The peak assignments made in this study can serve as a foundation for future experiments designed to utilize XPS to uncover atomic-level details of the surface chemistry of IrO2(110).
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INTRODUCTION: Neonatal mortality is increasingly recognized as an important global public health challenge. The spectrum of organisms that cause neonatal sepsis changes over time and varies from region to another. This study was conducted to determine the profile, antibiotic sensitivity pattern of bacterial isolates and outcome of confirmed neonatal sepsis in a tertiary care center. STUDY DESIGN: All blood culture reports (n = 285), obtained during the study period (January 2012-September 2012) from the neonatal intensive care unit were analyzed. RESULTS: Blood culture positivity rate was 22.1% (67/285). Seventy-three percent babies were outborn. Sixty-two percent babies were preterm and 80% were low birth weight. Thirty-six (57%) babies had early onset and remaining 27 (43%) had late onset neonatal sepsis. Blood culture isolates included Gram-negative bacilli (38/67, 56.7%), Gram-positive cocci (20/67, 29.8%), and Candida species (9/67, 13.4%). Staphylococci and Klebsiellae were the most common organisms responsible for infections, accounting for 25.4% (17/67) and 19.4% (13/67) of the isolates, respectively. All Gram positive isolates were sensitive to vancomycin, while 50-65% Gram negative isolates were sensitive to amikacin, ciprofloxacin and meropenem. Fifty-eight percent babies were discharged after completion of the antibiotic therapy, while 28.6% babies expired. CONCLUSION: Multidrug resistant Gram negative isolates pose serious challenge, particularly in setting of emerging resistance to fluoroquinolones and carbepenems.