Molecular Engineering in a Family of Pillared-Layered Metal Organic Frameworks for Tuning Gas Adsorption Behavior

In this work, inspired by a water-assisted three-dimensional supramolecular structure 1, we use a mixed-ligand strategy to form a 3D pillared-layered matrix by introduction of linear ligands to compete against...

Zirconium Carboxyaminophosphonate Nanosheets as Support for Ag Nanoparticles

A layered insoluble inorganic-organic solid, namely zirconium phosphate glycine-N,N-bismethylphosphonate, was used to prepare dispersions of nanosheets to support active metals such as metallic silver nanoparticles and zinc ions. Zr phosphate-phosphonate microcrystals were first exfoliated with methylamine to produce a stable colloidal dispersion and then the methylamine was removed by treatment with hydrochloric acid. The obtained colloidal dispersion of Zr phosphate-phosphonate nanosheets was used to immobilize silver or zinc cations, via ion exchange, with the acidic protons of the sheets. The layered matrix showed a great affinity for the metal cations up taking all the added cations. The treatment of the dispersions containing silver ions with ethanol yielded metal silver nanoparticles grafted on the surface of the layered host. The samples were characterized by X-ray powder diffraction, elemental analysis transmission electron microscopy, and selected samples were submitted to antimicrobial tests. The nanocomposites based on Ag nanoparticles showed good bactericidal properties against the bacterial reference strain Staphylococcus epidermidis (S. epidermidis).

A Practical Ultrasonic Inspection Method for Detecting and Characterising Defects Found Within Composite Repairs

Two steel substrate test panels were developed to represent common plate thicknesses found on naval vessels and scanned using the Babcock developed ultrasonic technique. One sample comprised of a series of slotted surface breaking flaws of varying widths and through thicknesses to represent fracturing/cracking. The inspection method detected simulated cracking to a depth of 2mm and 0.5mm in width. The second sample included numerous loss of wall thickness areas of varying diameters and through thicknesses, with the smallest detectable loss of wall thickness being 0.1mm at a 15mm diameter. After proving confidence in detection, there was a need to characterise flaws to provide support and ascertain a repair action. Samples were produced that were subjected to either impact or heat exposure to induce realistic representative damage. The practical ultrasonic method was successfully used to independently characterise between the samples, with induced de-laminations caused by blisters, and multi layered matrix cracking caused by varying levels of projectile impacts, due to their unique morphology.

Development and Evaluation of Multilayered Layered Matrix Tablets of Water Soluble Drug

A new approach to zero- order drug delivery that includes geometric factors is described. Systems such as multilayered tablets and other geometrically altered devices have been created to perform this function. The multi-layered matrix system overcomes inherent disadvantages of non-linearity associated with diffusion controlled matrix devices by providing additional release surface with time to compensate for the decreasing release rate. These formulations designed to deliver the drug at predetermined rate, maintain therapeutically effective concentrations in systemic circulation for prolonged period of time. Recently, pharmaceutical research has focused on controlled drug delivery offer definite advantages over conventional release formulation of the same drug. Controlled delivery systems that can provide zero-order drug delivery have the potential for maximizing efficacy while minimizing dose frequency and toxicity. In the present study, guar gum was used as hydrophilic matrix carrier for designing oral controlled drug delivery systems of highly soluble drug lamivudine. Three layered matrix tablets of lamivudine prepared by wet granulation technique were subjected for various evaluating parameters and optimized.