Use of Hydration Inhibitors to Improve Bond Durability of Aluminum Adhesive Joints

An investigation is conducted of the mechanisms by which nitrilotris methylene phosphonic acid (NTMP) and related compounds are adsorbed onto oxidized aluminum surfaces to inhibit hydration and increase the durability of adhesive bonds formed with inhibitor-treated panels. P - O - Al bonds are identified as the basis of adsorption, and it is found that water initially adsorbed onto the etched aluminum surfaces is displaced by the NTMP. The hydration of the NTMP-treated surfaces occurs in three stages, namely the reverisble physisorption of water, the slow dissolution of NTMP followed by rapid hydration of the freshly exposed Al2O3 to AlOOH and further hydration of the surface to Al(OH)3. Five properties of an ideal inhibitor are identified

Capture-zone scaling in island nucleation: phenomenological theory of an example of universal fluctuation behavior

In studies of island nucleation and growth, the distribution of capture zones, essentially proximity cells, can give more insight than island-size distributions. In contrast to the complicated expressions, ad hoc or derived from rate equations, usually used, we find the capture-zone distribution can be described by a simple expression generalizing the Wigner surmise from random matrix theory that accounts for the distribution of spacings in a host of fluctuation phenomena. Furthermore, its single adjustable parameter can be simply related to the critical nucleus of growth models and the substrate dimensionality. We compare with extensive published kinetic Monte Carlo data and limited experimental data. A phenomenological theory sheds light on the result.Comment: 5 pages, 4 figures, originally submitted to Phys. Rev. Lett. on Dec. 15, 2006; revised version v2 tightens and focuses the presentation, emphasizes the importance of universal features of fluctuations, corrects an error for d=1, replaces 2 of the figure

Atomistic mechanisms for the ordered growth of Co nano-dots on Au(788): comparison of VT-STM experiments and multi-scaled calculations

Hetero-epitaxial growth on a strain-relief vicinal patterned substrate has revealed unprecedented 2D long range ordered growth of uniform cobalt nanostructures. The morphology of a Co sub-monolayer deposit on a Au(111) reconstructed vicinal surface is analyzed by Variable Temperature Scanning Tunneling Microscopy (VT-STM) experiments. A rectangular array of nano-dots (3.8 nm x 7.2 nm) is found for a particularly large deposit temperature range lying from 60 K to 300 K. Although the nanodot lattice is stable at room temperature, this paper focus on the early stage of ordered nucleation and growth at temperatures between 35 K and 480 K. The atomistic mechanisms leading to the nanodots array are elucidated by comparing statistical analysis of VT-STM images with multi-scaled numerical calculations combining both Molecular Dynamics for the quantitative determination of the activation energies for the atomic motion and the Kinetic Monte Carlo method for the simulations of the mesoscopic time and scale evolution of the Co submonolayer

Crossover in the scaling of island size and capture zone distributions

Simulations of irreversible growth of extended (fractal and square) islands with critical island sizes i=1 and 2 are performed in broad ranges of coverage \theta and diffusion-to-deposition ratios R in order to investigate scaling of island size and capture zone area distributions (ISD, CZD). Large \theta and small R lead to a crossover from the CZD predicted by the theory of Pimpinelli and Einstein (PE), with Gaussian right tail, to CZD with simple exponential decays. The corresponding ISD also cross over from Gaussian or faster decays to simple exponential ones. For fractal islands, these features are explained by changes in the island growth kinetics, from a competition for capture of diffusing adatoms (PE scaling) to aggregation of adatoms with effectively irrelevant diffusion, which is characteristic of random sequential adsorption (RSA) without surface diffusion. This interpretation is confirmed by studying the crossover with similar CZ areas (of order 100 sites) in a model with freezing of diffusing adatoms that corresponds to i=0. For square islands, deviations from PE predictions appear for coverages near \theta=0.2 and are mainly related to island coalescence. Our results show that the range of applicability of the PE theory is narrow, thus observing the predicted Gaussian tail of CZD may be difficult in real systems.Comment: 9 pages, 7 figure

Learning in Partnership: Leadership as a Cornerstone for Interprofessional Education Between GPs and Community Pharmacists

Objective: Interprofessional education (IPE), defined as ‘Occasions where two or more professions learn with, from and about each other to improved collaboration and the quality of care’ (Barr, 2002), is vital for development of new NHS models of patient care. This project aimed to develop and evaluate an IPE programme to encourage the development of networks of Community Pharmacists and GPs, and to deepen understanding of each other’s NHS contracts and their role in helping achieve better patient outcomes. / Design: Leadership training provided common ground for IPE with GPs and community pharmacists. Five pairs of GPs and community pharmacists, recruited from London and the South East, attended an initial project induction event and five half-day sessions focussing on leadership training based on the Healthcare Leadership Model (NHS Leadership Academy, 2013). The pairs then spent four half day placements in each other’s practice. As an outcome of these activities, each pair was required to jointly undertake, write up and present a Quality Improvement Project (QIP). The leadership training was evaluated using a questionnaire containing open questions developed from previously used questionnaires. Responses were scrutinised to identify and frequency-count themes. / Results: Eight responses were received. Ten overarching themes emerged. The most frequent themes were ‘developing understanding’ and ‘collaborative working’, as illustrated by the following quotes: ‘I have a new found respect for Doctors now and realise we are in the same boat.’ ‘We can work together to achieve a common goal.’ / Conclusion: The focus on leadership training enabled pharmacists and GPs to learn from, with and about each other through the identification of similar challenges and issues. This provided a strong basis to develop interprofessional communication and collaborative working to improve the patient journey

Diamond Solitaire

We investigate the game of peg solitaire on different board shapes, and find those of diamond or rhombus shape have interesting properties. When one peg captures many pegs consecutively, this is called a sweep. Rhombus boards of side 6 have the property that no matter which peg is missing at the start, the game can be solved to one peg using a maximal sweep of length 16. We show how to construct a solution on a rhombus board of side 6i, where the final move is a maximal sweep of length r, where r=(9i-1)(3i-1) is a "rhombic matchstick number".Comment: 11 pages, 12 figure

Cognitive mapping: Using local knowledge for planning health research

Background: Cognitive mapping is a participatory research methodology that documents, in visual form, a construct of the local environment in which people live and work. We adapted this method to provide detailed data about study locales to inform recruitment and retention strategies for HIV prevention community based clinical trials. Methods: Four cognitive mapping studies were undertaken between 2005 and 2010, in and around Johannesburg in Orange Farm, and Hillbrow. Participants included members of clinical trial Community Advisory Boards (CAB), young people recruited from schools in Hillbrow and an organization for out of school youth, and men recruited from a database of men in the community interested in taking part in research. These groups participated in reconnaissance walks and in depth interviews, and drew detailed sketch maps. Results: The cognitive maps defined the physical boundaries of the research locales, provided insights into their social histories, and identified important characteristics of the population such as movement, social and sexual networks, ethnic and other divisions. Important differences between the official cartographic maps and the cognitive maps were raised. The mapping data was applied by identifying key areas for recruitment that recruitment staff members were less familiar with and that may otherwise have been overlooked. Conclusions: Cognitive mapping is an effective, rapid and low cost method that can be used to inform recruitment and retention strategies for community-based clinical trial research. The method also provides a means for clinical trial researchers to involve the local community in research and to familiarise them with the social setting

Continuous and correlated nucleation during nonstandard island growth at Ag/Si(111)-7x7 heteroepitaxy

We present a combined experimental and theoretical study of submonolayer heteroepitaxial growth of Ag on Si(111)-7x7 at temperatures from 420 K to 550 K when Ag atoms can easily diffuse on the surface and the reconstruction 7x7 remains stable. STM measurements for coverages from 0.05 ML to 0.6 ML show that there is an excess of smallest islands (each of them fills up just one half-unit cell - HUC) in all stages of growth. Formation of 2D wetting layer proceeds by continuous nucleation of the smallest islands in the proximity of larger 2D islands (extended over several HUCs) and following coalescence with them. Such a growth scenario is verified by kinetic Monte Carlo simulation which uses a coarse-grained model based on a limited capacity of HUC and a mechanism which increases nucleation probability in a neighbourhood of already saturated HUCs (correlated nucleation). The model provides a good fit for experimental dependences of the relative number of Ag-occupied HUCs and the preference in occupation of faulted HUCs on temperature and amount of deposited Ag. Parameters obtained for the hopping of Ag adatoms between HUCs agree with those reported earlier for initial stages of growth. The model provides two new parameters - maximum number of Ag atoms inside HUC, and on HUC boundary.Comment: LaTeX2e, BibTeX, 9 pages, 7 images, accepted to Phys. Rev.