Coherent structures in an electron beam

The formation and evolution of coherent structures in a low-energy electron beam produced in a Malmberg-Penning trap is investigated by means of CCD diagnostics. The electrons are emitted from a thermionic cathode and their energy is controlled by an acceleration grid. By varying the spatial distribution of the energy of emitted electrons, different space charge effects are observed, as, e. g., a sharp or a gradual transition to a space charge dominated regime. The variation of the coherent structures along the beam is studied by varying the electron density or/and the value of the confined magnetic field. The observed processes are interpreted using a tridimensional particle-in-cell code which solves the Vlasov-Poisson system in zeroth order drift approximation.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Epidemiological study of pathogens isolated from blood in Liguria during 2011

Objectives. An epidemiological study addressed to identify the most represented pathogens isolated from blood and to evaluate their antibiotic susceptibility patterns, was conducted. Methods. Five clinical microbiology laboratories, homogenously distributed in Liguria, were required to collected all consecutive non-duplicates strains isolated from blood cultures during March 2011 to May 2011. the strains were sent to the reference laboratory (Section of Microbiology, DISC, University of Genoa, Italy). Results. A total of 159 microorganisms were enrolled, including 81 Gram positive, 69 Gram negative and 9 fungi.The most represented pathogens were: Escherichia coli (35), Staphylococcus aureus (26), S. epidermidis (20), S. hominis (10). Samples were collected mainly from medicine (59 isolates).Among the staphylococci, the most active molecules were: vancomycin (100% of susceptible strains), teicoplanin (93.4%), trimethoprim-sulfamethoxazole (83.8%) and tobramycin (61.6%). Enterococci showed rates of resistance to vancomycin of 25%. Enterobacteriaceae exhibited resistance to ampicillin (76.9%), ceftriaxone (44.4%), ciprofloxacin (43.3%), trimethoprim-sulfamethoxazole (36.6%) and ceftazidime (32.2%). Conclusions. The data show a higher incidence of Gram positive (51%) in comparison to Gram negative (43.4%). Gram-positive strains showed a high resistance level to fluoroquinolones (92.3%) while Gram-negative resulted resistant to ceftriaxone (44.4%) and fluoroquinolone (43.3%)

Epidemiological study of pathogens isolated from blood in Liguria (January-April 2010)

Objectives. An epidemiological study to identify the most represented pathogens isolated from blood and to evaluate their antibiotic susceptibility patterns, was conducted. Methods. Seven clinical microbiology laboratories, homogeneously distributed in the Ligurian area,were required to collected all consecutive non-duplicates strains isolated froom blood cultures during January 2010 to April 2010. The strains were sent to the reference laboratory (Sezione di Microbiologia del DISC, University of Genoa, Italy). Results. A total of 277 microorganisms were enrolled, including 155 Gram positive and 122 Gram negative.The most represented pathogens were: Escherichia coli (68), Staphylococcus aureus (57), Staphylococcus epidermidis (32), Staphylococcus hominis (17), Pseudomonas aeruginosa (15), Klebsiella pneumoniae (15), Enterococcus faecalis (11). Samples were collected mainly from medicine (66, 33.3%, of this number was determined by E. coli), intensive care units (33, 18.2% of this number consisted of S. epidermidis), surgery (24, 33.3% consisted of E. coli) and infectious diseases (20, of which S. aureus, E. coli and S. epidermidis equally represented 20.0%).Among the Staphylococci the most active molecules were: vancomycin and teicoplanin (100% of susceptible strains), chloramphenicol (92.3%) and trimethoprim-sulfamethoxazole (89.8%). Among the OXA-R Staphylococci (81/123, 65.9%) the most active molecules were: vancomycin and teicoplanin (100% of susceptible strains), chloramphenicol (93.8%) and trimethoprim-sulfamethoxazole (84.8%). Enterococci showed rates of resistance to vancomycin of 5.9%. Enterobacteriaceae exhibited resistance to ampicillin (77.5%), trimethoprim-sulfamethoxazole (42.6%), ciprofloxacin (41.2%), ceftriaxone (37.5%), ceftazidime (28.2%), cefepime (26.7%), cefoxitin (22.1%), piperacillintazobactam (20.4%), imipenem (4.7%) and amikacin (2.9%). The Gram negative non-Enterobacteriaceae showed rates of resistance of 100% to ceftriaxone, 81.3% to trimethoprim-sulfamethoxazole, 42.1% to ciprofloxacin and piperacillin-tazobactam, 33.3% to ceftazidime, 31.6% to cefepime, 27.8% to imipenem, 26.3 % to amikacin. Conclusions. The data show a higher incidence of Gram positive (56%) in comparison to Gram negative (44%).This confirms the high incidence of oxacillino-resistance in Staphylococci in our geographic area.Against Enterobacteriaceae rates of resistance were observed in excess of 20% for all drugs tested except imipenem (4.7%) and amikacin (2.9%). The proportion of imipenem-resistant isolates was constituted of strains of K. pneumoniae carbapenemase producers

Epidemiological study of pathogens collected from blood for a period of a year (2008-2009)

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The kinetics of low-temperature spatial atomic layer deposition of aluminum oxide

Spatial atomic layer deposition can be used as a high-throughput manufacturing technique in functional thin film deposition for applications such as flexible electronics. This, however, requires low-temperature deposition processes. We have investigated the kinetics of low-temperature (<100 °C) spatial atomic layer deposition of alumina from tri-methyl aluminum and water. The water partial pressure and the exposure time were identified as the critical parameters in this process

Spatial atomic layer deposition of zinc oxide thin films

Zinc oxide thin films have been deposited at high growth rates (up to 1 nm/s) by spatial atomic layer deposition technique at atmospheric pressure. Water has been used as oxidant for diethylzinc (DEZ) at deposition temperatures between 75 and 250 °C. The electrical, structural (crystallinity and morphology), and optical properties of the films have been analyzed by using Hall, four-point probe, X-ray diffraction, scanning electron microscopy, spectrophotometry, and photoluminescence, respectively. All the films have c-axis (100) preferential orientation, good crystalline quality and high transparency ( 85%) in the visible range. By varying the DEZ partial pressure, the electrical properties of ZnO can be controlled, ranging from heavily n-type conductive (with 4 mOhm.cm resistivity for 250 nm thickness) to insulating. Combining the high deposition rates with a precise control of functional properties (i.e., conductivity and transparency) of the films, the industrially scalable spatial ALD technique can become a disruptive manufacturing method for the ZnO-based industry

Atmospheric spatial atomic layer deposition of In-doped ZnO

Indium-doped zinc oxide (ZnO:In) has been grown by spatial atomic layer deposition at atmospheric pressure (spatial-ALD). Trimethyl indium (TMIn), diethyl zinc (DEZ) and deionized water have been used as In, Zn and O precursor, respectively. The metal content of the films is controlled in the range from In/[In+Zn] = 0 to 23% by co-injecting the vaporized metal precursors (i.e. DEZ and TMIn) in the deposition region and varying their flows. A high doping efficiency (up to 95%) is achieved, resulting in films with very high carrier density (6·1020 cm-3), low resistivity (3 mO·cm) and high transparency in the visible range (> 85%). The morphology of the films changes from polycrystalline to amorphous with increasing indium content above 15%, while maintaining a low resistivity value (<7 mO·cm). Spatial-ALD combines a fine tuning of the composition, morphology and electrical properties of ZnO:In films with high deposition rates (> 0.1 nm/s)