ABSTRACT
Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses.
ABSTRACT
Phase-change materials are the alloys at the heart of an emerging class of next-generation, non-volatile digital memory technologies. However, the widely studied Ge-Sb-Te system possesses several undesirable properties, and enhancing its properties, e.g. by doping, is an area of active research. Various first-row transition-metal dopants have been shown to impart useful property enhancements, but a systematic study of the entire period has yet to be undertaken, and little has been done to investigate their interaction with the host material at the atomic level. We have carried out first-principles computer simulations of the complete phase-change cycle in Ge2Sb2Te5 doped with each of the ten first-row transition metals. In this article, we present a comprehensive survey of the electronic, magnetic and optical properties of these doped materials. We discuss in detail their atomic-level structure, and relate the microscopic behaviours of the dopant atoms to their influence on the Ge2Sb2Te5 host. By considering an entire family of similar materials, we identify trends and patterns which might be used to predict suitable dopants for optimizing materials for specific phase-change applications. The computational method employed here is general, and this materials-discovery approach could be applied in the future to study other families of potential dopants for such materials.
ABSTRACT
Few tools for home visit evaluation of students exist in current nursing literature. Therefore, a tool was developed that utilizes a nursing process framework to measure essential nursing behaviors in the home. Incorporated into the tool are unique facets of community-oriented nursing practice, such as home environment assessment, family-oriented nursing diagnoses, bag technique, and contracting. The tool is a two-page form designed to evaluate pre-visit, onsite, and post-visit nursing activities. The tool has been refined using empirical data from clinical experiences with over 200 students in community health nursing.
Subject(s)
Community Health Nursing/education , Employee Performance Appraisal , Home Care Services/standards , Nursing Process , Personnel Management , Education, Nursing , HumansABSTRACT
In summary, we have attempted, in planning the Diploma Nursing Program at Okanagan College, to retain the positive aspects of existent hospital and college programs, while at the same time developing some unique features: a health promotion focus, a comprehensive curriculum framework and a cooperative education design. As yet, in this first year the program, it is too early to predict outcomes, but we anticipate that our students will be better equipped to deal with the reality of a work situation.
