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peer-reviewed The Medical Device industry lags other industries such as automotive and aerospace in terms of the use of predictive modeling as a design tool. This has started to change with growing experience being established with metal scaffold type structures (stents, Transcatheter aortic valve structures etc.). However, these computational methods are generally used with structures that are composed of a single material type as with Finite Element Analysis (FEA). Composite interventional catheters generally features 3-layer composite structures (polymer layer A/Metal reinforcement layer B/polymer layer C) which offer different challenges than single material structures in terms of predictive modeling. The results achieved with two different Experimental Design or Design of Experiments (DOE) based predictive modeling methodologies will be compared. The Classic DOE approach is based on a full factorial DOE with center points. The Custom DOE approach is based on the full factorial approach but is augmented with a series of experiments to fill the internal design space more completely rather than rely on just taking sample points predominantly around the boundaries of the design space as in classic DOE. Results generated from both approaches relate to catheter performance criteria of value in early stage composite catheter design. Strengths and drawbacks of both modeling approaches are discussed.

Currently there are limited predictive modeling tools available for composite interventional catheter design. Most interventional catheter development involves iteration based design. Composite interventional catheters typically consist of a PTFE inner layer wrapped with a fine strand, metal reinforcement layer covered with a TPE (thermoplastic elastomer) outer layer. Fast reliable computational based techniques for early stage catheter design would limit the number of prototypes required to get to concept or design freeze stage therefore reducing development time. This paper’s goal is to examine how effective FEA is as a technique for predicting the performance of a composite catheter shaft. The steps taken and challenges overcome in creating a configurable FE model for a spirally reinforced composite catheter are outlined. The paper presents Finite Element (FE) generated data for tensile yield. This is a fundamental performance parameter in interventional catheter design. Catheters are designed to operate below their yield point. Models developed for simulating tensile yield can likely be adapted to simulate other performance characteristics such as flexural properties and torsion characteristics as part of future work. Data from FEA analysis is compared with data from physically testing catheters built to the same specification as that used in the FE model configuration.

Two dithiadiazolyl radicals of formula [F 2 C 6 H 3 CNSSN] ˙ were prepared and characterised by X-ray crystallography; in the solid state the 2′,3′-difluoro isomer forms discrete twisted dimers through a spin-paired singly occupied–singly occupied molecular orbital interaction with an intra-dimer S · · · S distance of 3.020(4) A, whereas the 2′,5′-isomer is composed of uniform stacks with unexpectedly long intra-stack S · · · S contacts [3.544(3) A].

Feeding of fluorinated benzoic acids to fermentations of a Phoma sp. resulted in the biosynthesis of a series of novel fluorinated squalestatins. The feeding studies, isolation, structural elucidation and biological activities of these compounds are reported.