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The crystal structure of a-plane GaN/ZnO heterostructures on r-plane sapphire was investigated by using the XRD and TEM measurment. It was found the formation of (220) ZnGa2O4 and crystal orientation of semipolar (10$\bar 1$3) GaN at GaN/ZnO interface. The epitaxial relation of normal surface direction are the sapphire (1$\bar 1$02) // a-GaN (11$\bar 2$0) and ZnGa2O4 (220) // semi-polar GaN (10$\bar 1$$\bar 3$). Beside, the emission peak energy of ZnO appears shift about 60 meV in the GaN/ZnO/GaN heterostructures due to the re-crystallization of ZnO layer with Ga or N atom and the formation of the localized state.
To investigate a nosocomial outbreak of infection with multidrug-resistant (MDR) Acinetobacter baumannii in the intensive care units at China Medical University Hospital in Taiwan.
Design.
Prospective outbreak investigation.
Setting.
Three intensive care units in a 2,000-bed university hospital in Taichung, Taiwan.
Methods.
Thirty-eight stable patients in 3 intensive care units, all of whom had undergone an invasive procedure, were enrolled in our study. Ninety-four A. baumannii strains were isolated from the patients or the environment in the 3 intensive care units, during the period from January 1 through December 31, 2006. We characterized A. baumannii isolates by use of repetitive extragenic palindromic–polymerase chain reaction (REP-PCR) and random amplified polymorphic DNA (RAPD) fingerprinting. The clinical characteristics of the source patients and the environment were noted.
Results.
All of the clinical isolates were determined to belong to the same epidemic strain of MDR A. baumannii by the use of antimicrobial susceptibility tests, REP-PCR, and RAPD fingerprinting. All patients involved in the infection outbreak had undergone an invasive procedure. The outbreak strain was also isolated from the environment and the equipment in the intensive care units. Moreover, an environmental survey of one of the intensive care units found that both the patients and the environment harbored the same outbreak strain.
Conclusion.
The outbreak strain of A. baumannii might have been transmitted among medical staff and administration equipment. Routine and aggressive environmental and equipment disinfection is essential for preventing recurrent outbreaks of nosocomial infection with MDR A. baumannii.
Aberration correction leads to a substantial improvement in the directly interpretable resolution of transmission electron microscopes. Correction of the aberrations has been achieved electron-optically through a hexapole-based corrector and also indirectly by computational analysis of a focal or tilt series of images. These direct and indirect methods are complementary, and a combination of the two offers further advantages. Materials characterization has benefitted from the reduced delocalization and higher resolution in the corrected images. It is now possible, for example, to locate atomic columns at surfaces to higher accuracy and reliability. This article describes the JEM-2200FS in Oxford, which is equipped with correctors for both the image-forming and probe-forming lenses. Examples of the use of this instrument in the characterization of nanocrystalline catalysts are given together with initial results combining direct and indirect methods. The double corrector configuration enables direct imaging of the corrected probe, and a potential confocal imaging mode is described. Finally, modifications to a second generation instrument are outlined.
Methods for accurate and automated determination of the coefficients
of the wave aberration function are compared with particular emphasis on
measurements of higher order coefficients in corrected instruments.
Experimental applications of aberration measurement to the determination
of illumination isoplanicity and high precision local refinement of
restored exit waves are also described.
Exit wave restoration using focus series of images has become a widely
used technique to improve image resolution and interpretation. To
understand the effects of the imaging approximations used, we have
critically compared the specimen exit wave functions restored using the
efficient linear Wiener filter, with a general nonlinear maximum
likelihood method.
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