Electrochemical nucleation

A study has been made of electrochemical nucleation of metals from aqueous solution. Of principal concern was the electrochemical nucleation of silver on graphite, of silver on platinum and of mercury on graphite.In the first part a survey was made of the existing theories of electrochemical nucleation, of the growth of established nuclei and of the kinetics of nucleation.'The second part is concerned with the results of this research. The experimental work itself was concerned to develop smooth electrodes of good reproducibility. Potentiostatic current-time transients wereIrecordedd using high quality signal generation and. data acquisition systems. These measurements were supplemented by visual observation of the nuclear density. The current-time transients were used to examine existing theories of diffusion-controlled nuclear growth and to determine the number of nuclei as a function of over potential, concentration and, acidity. The potentiostatic double pu13e method was also used in an effort to determine the induction time or time lag for the onset of nucleation.The third part of the thesis is concerned with the adequacy of the existing theories of nuclear growth and inter alia with the general problem of electrode kinetics at small electrodes. Both explicit and implicit.'numerical methods of computer simulation have been developed to deal with these problems and a range of new procedures have been shown to be accurate in this respect. Numerical methods have also been applied to more complex processes where the dimensions of the electrode change progressively with time. This is at the heart of the nucleation work and the 'moving boundary' methods successfully developed here indicate not only that both of the existing analytic descriptions are seriously in error but that the nuclear densities calculated by the new techniques are much closer to those visually observed.</p

Doctor of Philosophy

dissertationA rapid method of constructing fused bicyclic 4-hydroxy-2-cyclopentenones was introduced. Fused bicyclic 4-pyrones, prepared by condensation of enamines derived from cyclic ketones with diketene or equivalents, upon photolysis in hydroxylic medium, gave bicyclio[n.3.0]alkenones bearing allylic hydroxy groups. This process occurs via regioselective nucleophilic solvent trapping of the intermediate tricyclic oxyallyl zwitterion

Primary leiomyosarcoma of bones – a rare entity in two different presentations

Introduction. Leiomyosarcomas (LMS) originate from smooth muscle cells. They are very rare malignant neoplasms. Bony Leiomyosarcoma is a variant of spindle cell sarcoma, primarily affecting long bones, predominantly the distal femur and the proximal tibia followed by craniofacial skeleton. Aim. To describe clinical presentation and diagnostic approach of primary leiomyosarcoma of bones in two different patients. Description of the cases. Case 1. A 64-year-old male with a fracture of left distal femur after a fall was investigated and found to have a pathological fracture. An open biopsy of the fracture site confirms leiomyosarcoma. Case 2. A 58-year-old previously healthy female presented with a swelling on right side mandibular region. Orthopantomogram radiograph (OPG) of mandible and Cone beam CT (CBCT) mandible was taken initially and revealed a large area of bone destruction of the right side of the mandible associated with a soft tissue mass. Initial incisional biopsy made the diagnosis of spindle cell sarcoma followed by excisional biopsy, which confirms the diagnosis of moderately differentiated leiomyosarcoma. Conclusion. Primary leiomyosarcoma of bones is very rare. Imaging features are helpful in the evaluation of such conditions, but final diagnosis should be based on histopathologic and immunohistochemical features

rural Sri Lanka

pilot study on the usefulness of information and education campaign materials in enhancing the knowledge, attitude and practice on rabies i