THE KINETICS OF CALCITE DISSOLUTION PRECIPITATION

The channel-flow cell method is used to establish the dissolution/precipitation kinetics of calcite under wide ranges of bulk Ca1+ concentration (0-10 mM) and solution flow rate (10-30.3 cm3 s-1) for different bulk pH values. Detailed mathematical modeling of the heterogeneous reaction, and accompanying solution processes leads to the following rate equation based on a model in which Ca2+ and CO2- 3 undergo Langmuirian adsorption on the calcite surface: Dnet/mol cm-2s-1 = kbKCaKCO3 { KSP - [Ca2+]o[CO2- 3]O (1 + KCo[Ca2+]o(1 + KCO3 [CO3]o)} Here Dnet is the net flux of dissolving calcium ions, kb is a rate constant, Ksp, is the solubility product of calcite corrected for the ionic strength of the solution, KA (A = Ca2+ or CO2- 3) are Langmuirian adsorption constants, and [ ]o denotes the concentration at the Outer Helmholtz Plane. © 1993 Academic Press. All rights reserved

A Systematic Scoping Review and Textual Narrative Synthesis of Undergraduate Pediatric Nursing Simulations: What, Why, and How?

Background: Simulation is increasingly being used to train healthcare professionals however there is limited knowledge on how paediatric simulation is being used to train undergraduate nurses. This article systematically scopes the literature on the types of undergraduate paediatric nursing simulations taking place, their value, the research methods used and areas of research focused on. Methods: A systematic scoping literature review, combined descriptive synthesis, and textual narrative synthesis was undertaken. Results: 139 studies were identified by the search strategy. Of these, 32 articles were included for appraisal and synthesis. 17 papers were quantitative, five qualitative, and eight mixed-methods. The research took place in six different geographical locations. The total participant sample was 2,039. Studies were categorised according to their aims and objectives, and simulation types. Conclusions: This review revealed the heterogeneity of studies on this subject. Ultimately, studies were small and confined to single institutions or geographical locations. Studies that described or explored simulation as an intervention provided more interesting insights than those that evaluated or tested effectiveness. The variety of simulation types was wide and the fidelity of the simulations being described was frequently noted, however no reference was made as to how this was determined. Future studies would benefit from detailing the low, medium or high technological, psychological or environmental aspects of the simulation and how this was determined