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To evaluate the appropriateness of the screening strategy for healthcare personnel (HCP) during a hospital-associated Middle East Respiratory Syndrome (MERS) outbreak, we performed a serologic investigation in 189 rRT-PCR–negative HCP exposed and assigned to MERS patients. Although 20%–25% of HCP experienced MERS-like symptoms, none of them showed seroconversion by plaque reduction neutralization test (PRNT).
To determine the effectiveness of infection control strategies to reduce transmission of vancomycin-resistant enterococci (VRE), a cohort study was performed in a university hospital. Contact precautions alone were not effective in reducing transmission of VRE. Strict isolation of affected patients in private rooms, in addition to use of contact precautions, showed a significantly improved reduction in the transmission of VRE.
To investigate the characteristics and origins of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from neonatal patients admitted to a tertiary care hospital from local and primary care obstetrics clinics.
Molecular typing study.
A 1,278-bed tertiary care hospital (Samsung Medical Center) and 2 primary obstetrics clinics in Seoul, Korea.
The genotypic characteristics of 12 MRSA samples isolated from 11 neonatal patients transferred from 2 primary care obstetrics clinics to a tertiary care hospital were investigated by means of multilocus sequence typing, spa (staphylococcal protein A) typing, and SCCmec typing. Ten MRSA strains isolated from workers and environments in the associated obstetrics clinics were also investigated.
Although the antibiograms of isolates from 2 obstetrics clinics differed, no strain showed multidrug resistance to antimicrobials. Multilocus sequence typing analysis showed that all 22 MRSA isolates analyzed in this study had sequence type 1 (with the allelic profile 1-1-1-1-1-1-1), sequence type 493 (62-1-1-1-1-1-1), or a novel sequence type (25-1-1-1-1-1-1) and that all belonged to a single clonal complex (clonal complex 1). Moreover, they all contained SCCmec type IVA and the identical spa type (UJEBKBP). These genotypic characteristics are similar to those of typical community-associated MRSA strains rather than the hospital-acquired MRSA strains common in Korea.
The findings of this study suggest that community-acquired MRSA strains can spread in primary care clinics and be imported into tertiary care settings.
The adhesion force of pad and alumina were experimentally and theoretically investigated in slurry solutions of different pHs. The isoelectric point (IEP) of pad particles was measured to be around pH 3. The wafer surfaces showed negative zeta potentials in the investigated pH ranges with exception of FSG and Ta. Cu and Ta showed higher interaction forces than dielectric materials. The lowest adhesion force was measured between pad particle and wafer surfaces in a slurry solution of pH 11. The magnitude of adhesion force of pad particles was lower than alumina particles.
CuGaSe2 absorber layers were prepared by evaporating elemental Cu, Ga and Se in three stage on Molybdenum coated soda lime glass. The composition of the resultant film was studied by monitoring the substrate temperature, which decreased when a Cu-Se secondary phase was formed. As the Ga supplement increased during the third stage the void that formed in the beginning of the third stage was removed, while a small grain Ga-rich layer was formed on the surface, resulting in a Cu deficient surface. Therefore, the Voc was improved because of the enhanced surface morphology and the Jsc was reduced, due to the Ga rich layer on of the surface. Under optimal conditions, we achieved a cell performance of Voc = 780 mV, Jsc = 12.9 mA/cm2, ff = 62.5 and ν = 7.3 %.
The friction behavior and adhesion of abrasive particles were experimentally investigated during Cu CMP process. The highest particle adhesion force was measured in alumina slurry without citric acid. However, the alumina slurry with addition of citric acid had the lowest particle adhesion due to the adsorption of citrate ions on the alumina surfaces. While citrate ions could be easily adsorbed on alumina particles, silica particle showed the least effect on adsorption in citric acid solutions. The magnitude of adsorptions of citrate ions on the particle surfaces had significant effect on frictional behavior as well as adhesion force. Higher particle adhesion force resulted in higher friction, particle contamination and scratches in CMP process. It indicates that the magnitudes of particle adhesions on wafer surfaces in slurries can be directly related to the frictional behavior during CMP process.
The interaction between Cu surface and abrasive particles in slurry solution was characterized. The adsorption behavior of the citrate ions was dependent on the pH of the slurry and the concentration of the citric acid. The adsorption of citrate ions generated a highly negative charge on the alumina surface and shifted isoelectric point (IEP) to lower pH values. The Cu removal rate of alumina slurry was higher than that of colloidal silica based slurry in the investigated pH ranges. Although lower friction forces of Cu were observed in alumina based slurry of pH 4, 6 and 8, a higher friction force was observed at pH 2. This high friction force was attributed to the positive zeta potential and greater adhesion force of particle. It indicates that the magnitudes of particle adhesions on Cu surfaces in slurries can be directly related to the frictional behavior during CMP process.
The structural and the optical properties of 10-period In0.15Ga0.85N/GaN multiple quantum wells (MQWs) have been investigated using HRXRD (high-resolution X-ray diffraction) and PL (photoluminescence). For the samples, the barrier thickness was kept constant, 7.5 nm and the well thicknesses were varied, 1.5, 3.0, 4.5, and 6.0 nm. For the structural characterization, an ω/2θ-scan and an ω-scan for GaN (00 2) reflection and a reciprocal space mapping (RSM) around the GaN (10 5) lattice point were employed. The average strain for the MQWs increased as the well thickness increased. The MQW with a 6.0 nm well thickness experienced lattice relaxation and the crystallinity of the sample was poor compared to that of the other samples. MQWs with well thicknesses of 1.5, 3.0 and 4.5 nm, however, maintained lattice coherency with the GaN epilayers underneath, and the critical well thickness for lattice relaxation of the MQWs used in the study was 6.0 nm. The PL spectra showed that the relative emission intensity of the sample with a 6.0 nm well thickness was lower than for the others, a fact consistent with the X-ray results. The emission intensity, therefore, is considered to be affected by defects due to lattice relaxation of the epilayer.
6H-SiC single crystals were grown on various substrates, treated mechanically and chemically in different conditions, by physical vapor transport. To investigate the defect evolution according to the different substrate treatment prior to the growth, the grown crystals were examined by optical micrograph, scanning electron microscopy, atomic force microscopy and molten KOH etching technique. The smoother substrate surface was, the lower defect density the grown SiC had. The highest quality SiC crystal was grown on substrate etched by hydrogen after polished by 0.25 νm diamond paste, having an edge/screw dislocation density of 7.3 ×102 / cm2 without micropipes. Defects, such as dislocations and micropipes, of the grown crystals are found to be strongly correlated with the substrate morphology.
The junction depth should be less than 0.05 microns to fabricate sub 0.1 micron devices. This requires implanting boron with energy of less than 1 keV. One drawback in a low energy ion source is low throughput due to low ion beam current. At present, boron known for a major p-type dopant for PMOSFET has problem to easily diffuse into Si wafer even in rapid thermal processing by high diffusivity. To resolve this problem, decaborane (B10H14) molecules are implanted to make p+/n junction on n-type Si wafers for low-energy boron dopant source. Ionized decaborane is accelerated at 1∼10 kV and implanted up to dosages from 1×1012/cm2 to 5×1013/cm2. Afterwards, Decaborane implanted Si wafers were post-annealed for 10 sec at 800, 900 and 1000°C, respectively. From RBS results on as-implanted n-type Si wafer implanted at 5 kV, it is observed there are amorphous Si layers with 4 nm in depth and boron ions are implanted up to 1∼5 nm in depth from SIMS analysis. The electrical properties of these p-n junctions are 127∼130 ω/sq. as sheet resistance, +0.3 V turn-on voltage and −1.1 V breakdown voltage obtained from I-V measurement.
CuInSe2 films were prepared by the three-stage process using the evaporation of In2Se3, Cu2Se and Se. In the third stage, the depth of Cu-poor surface region was precisely adjusted by the control of the evaporation rate of In2Se3 and Se. The interface between Cu-poor surface region and stoichiometric CuInSe2 film was characterized using AES, microEDAX, and RBS. The 9.59% efficiency was achieved in the 0.16 cm2 area cell. The efficiency is the same level of the CIS cell prepared using the element coevaporation, opening up the application of binary compounds for highly efficient Cu(In,Ga)Se2 cells.
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