No abstract

The crystal morphology of adipic acid (AA) and its mediation by the action of the homologous additives, caproic acid, glutaric acid, and succinic acid, has been investigated via computational molecular modeling-based simulation techniques (Clydesdale, G.; Docherty, R.; Roberts, K. J. HABIT95, Quantum Chemistry Program Exchange (QCPE), Bloomington, IN 47405, Program Number 670, 1996). With the aid of intermolecular and interatomic energetic analyses, the experimental effect of these impurities has been rationalized. The predicted morphologies are in good agreement with sublimation-grown experimental data. This is not so for solution growth data, reflecting the possible adsorption of water molecules onto exposed carboxylic acid groups via hydrogen bonding on the {100} faces, thus allowing this form to become dominant. Modeling the adsorption of the additives reveals preferential adsorption onto the {302̄} faces, consistent with good additive/host templating at the growth interface, as demonstrated experimentally. Intermolecular bonding interactions examined those that disappeared in the presence of the additives. It was shown that impurity incorporation disrupted the hydrogen-bonding network within the system, due to an increase in interaction distances and in atom−atom repulsions. Despite its industrial significance, this is the first detailed study of the intermolecular interactions involved in impurity incorporation within adipic acid crystallization, and so any conclusions concerning the effect of impurities within the crystallizing mixture will be most useful.

The influence of impurities on the morphology of ε-caprolactam crystals was examined in terms of molecular recognition processes at the crystal/solution interface. Summing the intermolecular interactions, using the atom−atom approximation together with the DREIDING force field provided a convergence in the lattice energy summation with a good correlation to thermodynamic data. Attachment energy calculations using the HABIT95 program predicted a growth morphology dominated by {200}, {110}, and {111̄} crystal forms in good agreement with known experimental vapor growth data. Molecular dynamics studies of acetone, ethanol, toluene, water, and hexane solvent adsorption on the habit faces predicted the effect of solvent on the crystal morphology and in particular the development of the {311̄} growth form. Surface visualization modeling revealed the {311̄} surface to be much rougher, on the molecular scale, than the other major habit faces, consistent with easier impurity incorporation. Parallel studies of the binding of the impurity cyclohexanone revealed significantly strong binding on all habit faces, particularly on the solvent-dependent {311̄} face. Implications for attaining a high-purity product when crystallizing caprolactam in the presence of this impurity are discussed.

The Gnosall Primary Care Memory Clinic has been operating since 2006 and adds the skills of a specialist old age psychiatrist to the extensive skills and knowledge available in primary care. Key to the organisation and function of the clinic is the eldercare facilitator, a new role situated in primary care and linking with the specialist and a wide range of other agencies and people. In order to facilitate replication of the model elsewhere, the function, role and competencies of existing and previous eldercare facilitators in the clinic have been reviewed, clarified and related to a competency framework and to similar initiatives in the literature. The selection and training of people with the attributes and skills required to become an eldercare facilitator will determine whether extension of the model is successful elsewhere.