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21.
Fluorescent rare-earth-doped glass particles glued to the end of an atomic force microscope tip have been used to perform scanning near-field optical measurements on nanostructured samples. The fixation procedure of the fluorescent fragment at the end of the tip is described in detail. The procedure consists of depositing a thin adhesive layer on the tip. Then a tip approach is performed on a fragment that remains stuck near the tip extremity. To displace the particle and position it at the very end of the tip, a nanomanipulation is achieved by use of a second tip mounted on piezoelectric scanners. Afterward, the particle size is reduced by focused ion beam milling. These particles exhibit a strong green luminescence where excited in the near infrared by an upconversion mechanism. Images obtained near a metallic edge show a lateral resolution in the 180-200-nm range. Images we obtained by measuring the light scattered by 250-nm holes show a resolution well below 100 nm. This phenomenon can be explained by a local excitation of the particle and by the nonlinear nature of the excitation. 相似文献
22.
From the absorption and emission spectra recorded in a conventional way at 13 K, the Stark levels in manifolds from 4I15/2 to 2H9/2 for Er3+-doped ZBLAN (ZrF4–BaF2–LaF3–AlF3–NaF) glass have been investigated by means of the effective crystal field model previously proposed to describe the average of local symmetries occupied by rare earth ions in oxide glasses [1]. This model, based on the principle of descending symmetry, used the symmetry group chain scheme. Crystal field strength, homogeneous and inhomogeneous widths of levels have been determined, and the former models and results about optical properties for rare earth ions in heavy metal fluoride glasses are discussed. In fluoride glasses, the rare earth ions appear more evenly distributed than in oxide glasses, and the crystal field strength is weaker than in oxide glasses. 相似文献
23.
This paper reports an optical investigation of glass-ceramics formed by annealing glasses with compositions 50 GeO2-40 PbO-10 PbF2-x EuF3, x = [0.5; 1; 1.5; 2] and polycrystalline ceramics with composition 100 PbF2, y EuF3, with y = 5, 10, 15 and 20. For each material, the photoluminescence spectrum and the photoluminescence lifetimes of the 5D0, 5D1 and 5D2 Eu3+ levels are measured. Occurrence of Eu3+:β-PbF2 nanocrystallites in the glass-ceramics is confirmed and total ceramisation requires more than 10% of EuF3 with respect to PbF2 in the starting glass.In the Eu3+:β-PbF2 ceramics and glass-ceramics, Eu3+ ions replace Pb2+ in their regular cubic site, but they interact together to form dimers and higher nuclearity clusters. These two species are easily distinguished according to their photoluminescence decay rate. For the EuF3 rates investigated here, there are no isolated Eu3+ ions in the PbF2 lattice.A preliminary investigation of the optical properties of co-doped Gd3+:Eu3+:β-PbF2 ceramics was also performed. It shows that mixed Gd3+-Eu3+ dimers and clusters are formed, and that efficient Gd3+ → Eu3+ energy transfer occurs in these ceramics. The Pb2+ ions of the lattice may also be involved in the energy transfer process. 相似文献
24.
Survey of home hemodialysis patients and nursing staff regarding vascular access use and care 下载免费PDF全文
Leslie A. Spry John M. Burkart Christina Holcroft Leigh Mortier Joel D. Glickman 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(2):225-234
Vascular access infections are of concern to hemodialysis patients and nurses. Best demonstrated practices (BDPs) have not been developed for home hemodialysis (HHD) access use, but there have been generally accepted practices (GAPs) endorsed by dialysis professionals. We developed a survey to gather information about training provided and actual practices of HHD patients using the NxStage System One HHD machine. We used GAP to assess training used by nurses to teach HHD access care and then assess actual practice (adherence) by HHD patients. We also assessed training and adherence where GAPs do not exist. We received a 43% response rate from patients and 76% response from nurses representing 19 randomly selected HHD training centers. We found that nurses were not uniformly instructing HHD patients according to GAP, patients were not performing access cannulation according to GAP, nor were they adherent to their training procedures. Identification of signs and symptoms of infection was commonly trained appropriately, but we observed a reluctance to report some signs and symptoms of infection by patients. Of particular concern, when aggregating all steps surveyed, not a single nurse or patient reported training or performing all steps in accordance with GAP. We also identified practices for which there are no GAPs that require further study and may or may not impact outcomes such as infection. Further research is needed to develop strategies to implement and expand GAP, measure outcomes, and ultimately develop BDP for HHD to improve infectious complications. 相似文献
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Jill F. McLellan Roy M. Mortier Stefan T. Orszulik R. Michael Paton 《Journal of the American Oil Chemists' Society》1994,71(2):231-232
Formaldehyde undergoes ethylaluminum dichloride-catalyzed ene reaction with jojoba oil to afford a mixture of 1∶1 and 1∶2
adducts. The hydroxymethyl products were identified by comparison with model adducts prepared from methyl oleate and oleyl
acetate. 相似文献
27.
E. Saïdi J. Labéguerie-Egéa L. Billot J. Lesueur M. Mortier L. Aigouy 《International Journal of Thermophysics》2013,34(8-9):1405-1412
A fluorescent erbium/ytterbium co-doped fluoride nanocrystal glued at the end of a sharp atomic force microscope tungsten tip was used as a nanoscale thermometer. The thermally induced fluorescence quenching enabled observation of the heating and measurement of the temperature distribution in a Joule-heated 80 nm wide and 2 μm long titanium nanowire fabricated on an oxidized silicon substrate. The measurements have been carried out in an alternating heating mode by applying a modulated current on the device at low frequency. The heating is found to be inhomogeneous along the wire, and the temperature in its center increases quadratically with the applied current. Heat appears to be confined mainly along the wire, with weak lateral diffusion along the substrate and in the lateral metallic pads. The lateral resolution of this thermal measurement technique is better than 250 nm. It could also be used to study thermally induced defects in nanodevices. 相似文献
28.
Adsorption of CO onto the single crystal of dehydrated Ca-chabazite described in Pt. I reduced slightly the perturbation of TO distances () and perhaps the OTO angles (~ 0.2°). The distances between Ca and framework oxygens increased about 0.02Å. The CO molecule is adsorbed onto the Ca(II) cation which is displaced into the large cavity from the 6-ring. Although the structure refinement is uncertain because of large “temperature” factors for C and O, it is certain that the CO molecule is canted off the triad axis. The oxygen is apparently at to framework oxygens, the Ca(II)C and CO distances are 2.74(5) and 1.31(8)Å, and the Ca(II)CO angle is 134(5)°, but the errors may be unrealistically low. 相似文献
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