| 1. |
- Pfaller, M.A., et al.
(författare)
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Twelve years of fluconazole in clinical practice : Global-trends in species distribution and fluconazole susceptibility of bloodstream isolates of Candida
- 2004
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Ingår i: Clinical Microbiology and Infection. - : Elsevier BV. - 1198-743X .- 1469-0691. ; 10:SUPPL. 1, s. 11-23
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Tidskriftsartikel (refereegranskat)abstract
- We determined the species distribution and in-vitro susceptibility of 6082 bloodstream infection (BSI) isolates of Candida spp. collected from 250 medical centres in 32 nations over a 10-year period from 1992 through 2001. The species included 3401 C. albicans, 984 C. glabrata, 796 C. parapsilosis, 585 C. tropicalis, 153 C. krusei, 67 C. lusitaniae, 48 C. guilliermondii, 10 C. famata, 10 C. kefyr, six C. pelliculosa, five C. rugosa, four C. lipolytica, three C. dubliniensis, three C. inconspicua, two C. sake and one isolate each of C. lambica, C. norvegensis and C. zeylanoides. Minimum inhibitory concentration determinations were made using the National Committee for Clinical Laboratory Standards reference broth microdilution method. Variation in the rank order and frequency of the different species of Candida was observed over time and by geographic area. The proportion of BSI due to C. albicans and C. glabrata increased and C. parapsilosis decreased over time in Canada, the USA and Europe. C. glabrata was an infrequent cause of BSI in Latin America and the Asia-Pacific region. Very little variation in fluconazole susceptibility was observed among isolates of C. albicans, C. tropicalis and C. parapsilosis. These species accounted for 78% of all BSI and remained highly susceptible (91-100% susceptible) to fluconazole from 1992 to 2001 irrespective of geographic origin. The prevalence of fluconazole resistance among C. glabrata isolates was variable both over time and among the various countries and regions. Resistance to fluconazole among C. glabrata isolates was greatest in the USA and varied by US census region (range 0-23%). These observations are generally encouraging relative to the sustained usefulness of fluconazole as a systemically active antifungal agent for the treatment of candida BSI. © 2004 Copyright by the European Society of Clinical Microbiology and Infectious Diseases.
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| 2. |
- Palma, Carlos-Andres, et al.
(författare)
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Photo-induced C-C reactions on insulators towards photolithography of graphene nanoarchitectures
- 2014
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 136, s. 4651-4658
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Tidskriftsartikel (refereegranskat)abstract
- On-surface chemistry for atomically precise sp2 macromolecules requires top-down lithographic methods on insulating surfaces in order to pattern the long-range complex architectures needed by the semiconductor industry. Here, we fabricate sp2-carbon nm-thin films on insulators and under ultra-high vacuum (UHV) conditions from photo-coupled brominated precursors. We reveal that covalent coupling is initiated by C-Br bond cleavage through photon energies exceeding 4.4 eV, as monitored by laser desorption ionization (LDI) mass spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) gives insight into the mechanisms of C-Br scission and C-C coupling processes. Further, unreacted material can be sublimed and the coupled sp2-carbon precursors can be graphitized by e-beam treatment at 500°C, demonstrating promising applications in photolithography of graphene nanoarchitectures. Our results present UV-induced reactions on insulators for the formation of all sp2-carbon architectures, thereby converging top-down lithography and bottom-up on-surface chemistry into technology.
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| 3. |
- Zhang, Yi-Qi, et al.
(författare)
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Homo-coupling of terminal alkynes on a noble metal surface
- 2012
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The covalent linking of acetylenes presents an important route for the fabrication of novel carbon-based scaffolds and two-dimensional materials distinct from graphene. To date few attempts have been reported to implement this strategy at well-defined interfaces or monolayer templates. Here we demonstrate through real space direct visualization and manipulation in combination with X-ray photoelectron spectroscopy and density functional theory calculations the Ag surface-mediated terminal alkyne Csp−H bond activation and concomitant homo-coupling in a process formally reminiscent of the classical Glaser–Hay type reaction. The alkyne homo-coupling takes place on the Ag(111) noble metal surface in ultrahigh vacuum under soft conditions in the absence of conventionally used transition metal catalysts and with volatile H2 as the only by-product. With the employed multitopic ethynyl species, we demonstrate a hierarchic reaction pathway that affords discrete compounds or polymeric networks featuring a conjugated backbone. This presents a new approach towards on-surface covalent chemistry and the realization of two-dimensional carbon-rich or all-carbon polymers.
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| 4. |
- Zhang, Yi-Qi, et al.
(författare)
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Unusual Deprotonated Alkynyl Hydrogen Bonding in Metal-Supported Hydrocarbon Assembly
- 2015
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society. - 1932-7447 .- 1932-7455. ; 119:17, s. 9669-9679
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that terminal alkynyl moieties represent powerful functional groups for driving thermally stable, on-surface supramolecular structure formation on a reactive substrate. Through a combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, near-edge X-ray absorption-fine-structure spectroscopy and density functional theory calculations, we investigate the molecule-surface interaction and self-assembly of two prototypical hydrocarbon species on Cu(111). For 1,3,5-tris(4-ethynylphenyl)benzene (Ext-TEB) adsorption at low temperature (200 K) results in nonassembling, conformationally adapted intact species. Deprotonation of the terminal alkyne moieties, taking place at temperatures ranging from 300 to 350 K, triggers the formation of room-temperature stable, close-packed supramolecular islands. Through DFT calculations, the stabilizing interaction is identified as a trifurcated ionic C-H center dot center dot center dot pi(-delta) hydrogen bonding between the g-system of the ionic alkynyl groups and methine moieties of nearby benzene rings, providing an energy gain of 0.26 eV/molecule upon network formation. Robust assemblies result from the combination of this weak directional attraction with the strong surface anchoring also provided by the alkynyl groups. The generality of this novel ionic hydrogen-bonding type is demonstrated by the observation of low-dimensional assemblies of 9,10-diethynyl-anthracene on the same surface, consistently explained with the same type of interaction.
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