882 resultados para tips


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We report a new technique for preparing tips for electrochemical scanning tunneling microscopy (ECSTM) with particular consideration of its simplicity and reproducibility. In preparing scanning tunneling microscopy (STM) tips by electrochemical etching, w

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We have presented two simple methods of ''unfixed-position shield'' and ''pulling out'' for making sharp STM Pt-Ir tips with low aspect ratio by electrochemical etching in KCN/NaOH aqueous solution and ECSTM tips coated with paraffin. By limiting the elec

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Gold is the optimal tip metal for light emission in scanning tunnelling microscopy (LESTM) under ambient conditions. Sharp Au-tips of similar to 10nm radius were produced reliably using a safe, two-step etching method in 20% (w/w) CaCl2 solution. Previous CaCl2-based methods have tended to produce blunter tips, while other etching techniques that do produce sharp Au-tips, do so with the use of toxic or hazardous electrolytes. The tips are characterised using scanning electron microscopy and their efficacy in LESTM is evidenced by high-resolution, simultaneous topographic and photon mapping of Au(1 1 1)- and polycrystalline Au-surfaces. Spectra of the optical emission exhibit only one or two peaks with etched tips in contrast to the more complex spectra typical of cut tips; this feature, together with the highly symmetric geometry of the tips, facilitates a definitive analysis of the light emission process. (c) 2007 Elsevier B. V.. All rights reserved.

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The formation of chemically etched fibre tips for use in optical scanning probe microscopy is addressed. For tips formed at a cleaved fibre end in the bulk of a buffered HF acid solution the morphological features (tip height, cone angle) are found to depend strongly on the temperature and etchant composition. The tip formation process is analysed and explained in terms of a simple model in which the only pertinent physical parameters are the fibre core diameter and etch rates of the fibre core and cladding. The etch rates are determined in separate experiments as a function of temperature (in the range 24-50 degreesC) for etchant solutions of de ionised water: 50% HF acid: 40% NH4F in the volume ratio 1 : 1 : X for X=2, 4 and 6, and used in the model to yield a correct description of the experimental tip cone angles. The model is successfully extended to the intriguing case of negative tip formation which initiates in a normal, positive tip structure. By contrast, tip formation in the meniscus region of a bare fibre/etchant/organic solvent system is found to be independent of etchant composition and temperature. (C) 2000 Elsevier Science B.V. All rights reserved.

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Aims: Palliative care in long-term care (LTC) homes is an area of growing concern. Little work has been done to explore innovative ways to identify and care for residents who become palliative. The purpose of this intervention study was to evaluate the implementation of the Palliative Performance Scale (PPS) in LTC. Specifically we explored staff perceptions about implementing the PPS and how it cued staff to initiate palliative care discussion with residents and family when a resident’s health declined.

Methods: This study utilized a qualitative descriptive design that included data from four separate sources: journals of three ‘champions’ who were responsible for leading the implementation of the PPS; staff evaluations of three educational training sessions; minutes from meetings; and 11 interviews from key staff who were involved in the implementation process. Data were analyzed using thematic content analysis.

Results: Staff generally felt positively about using the PPS in LTC and stated that it increased awareness of palliative care and helped identify those residents who were nearing the end of life. There were some barriers to implementing it, such as staff resistance and lack of time to complete it. The importance of having a designated ‘champion’ and effective interdisciplinary communication in addition to widespread training, were identified as successful strategies to facilitate the implementation process.

Conclusion: These study findings support the use of the PPS in LTC and offer some perspective about ways to implement it successfully. Future work is needed to evaluate the PPS in LTC using more rigorous designs.

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