[Ventilator-associated pneumonia among premature infants <34 weeks' gestational age in neonatal intensive care unit in China: a multicenter study].

Objective: To investigate the incidence and pathogen distribution of ventilator-associated pneumonia (VAP) among preterm infants admitted to level Ⅲ neonatal intensive care units (NICU) in China. Method: A prospective study was conducted in 25 level Ⅲ NICU, enrolling all preterm infants <34 weeks gestational age admitted to the participating NICU within the first 7 days of life from May 2015 to April 2016. Chi-square test, t test and Mann-Whitney U test were used for statistical analysis. Result: A total of 7 918 patients were enrolled, within whom 4 623(58.4%) were males. The birth weight was (1 639±415) g and the gestational age was (31.4±2.0) weeks; 4 654(58.8%) infants required non-invasive mechanical ventilation and 2 154(27.2%) required intubation. Of all the mechanically ventilated patients, VAP occurred in 95 patients. The overall VAP rate was 7.0 episodes per 1 000 ventilator days, varying from 0 to 34.4 episodes per 1 000 ventilator days in different centers. The incidence of VAP was 9.6 and 6.0 per 1 000 ventilator days in children's hospitals and maternity-infant hospitals respectively, without significant differences (t=1.002, P=0.327). Gram-negative bacilli (76 strains, 91.6%) were the primary VAP microorganisms, mainly Acinetobacter baumannii (24 strains, 28.9%), Klebsiella pneumonia (23 strains, 27.7%), and Pseudomonas aeruginosa (10 strains, 12.0%). Conclusion: The incidence of VAP in China is similar to that in developed counties, with substantial variability in different NICU settings. More efforts are needed to monitor and evaluate the preventable factors associated with VAP and conduct interventions that could effectively reduce the occurrence of VAP.

[Microstructure of erbium-doped Si-rich thermal oxidation SiO2/Si luminescent thin films].

Er ions with 108 keV to a dose of 1 x 10(17) cm-2 were implanted into Si-rich thermal oxidation SiO2/Si thin film using metal vapor vacuum arc (MEVVA) ion source implanter. Er concentration in as-implanted sample, which was attained to -10 at % correspond to the level of -10(21) atoms.cm-3, was analyzed by Rutherford back-scattering (RBS) and X-ray photoelectron spectroscope (XPS). Contents of Er, Si and O in annealed samples were investigated using XPS at room temperature. It showed that Si content was increased and SiO2 content was decreased with increasing the fluence of Si ions. It was found by use dof reflective high energy electron diffraction (RHEED) and atomic force microscope (AFM) that needle micro-crystalline Si in the surface of annealed samples had been formed and Er segregation and precipitation were formed little. Photoluminescence around 1.54 microns from Er-doped Si-rich thermal oxidized SiO2/Si thin film were studied with a He-Cd laser pumping at 414.6 nm at the low temperature of 77 K and room-temperature (RT).