Gareth Thomson

An investigation into the impact of safety features on the ergonomics of surgical scalpels

In the case of surgical scalpels, blade retraction and disposability have been incorporated into a number of commercial designs to address sharps injury and infection transmission issues. Despite these new designs, the traditional metal reusable scalpel is still extensively used and this paper attempts to determine whether the introduction of safety features has compromised the ergonomics and so potentially the take-up of the newer designs. Examples of scalpels have been analysed to determine the ergonomic impact of these design changes. Trials and questionnaires were carried out using both clinical and non-clinical user groups, with the trials making use of assessment of incision quality, cutting force, electromyography and video monitoring. The results showed that ergonomic performance was altered by the design changes and that while these could be for the worse, the introduction of safety features could act as a catalyst to encourage re-evaluation of the ergonomic demands of a highly traditional product.

Preparation and characterisation of novel polycaprolactone-chitosan blends

This research paper reports on the production of a biocompatible and biodegradable material to be used in a polymer stent used for counteracting the occurrence of anastomotic leakage following gastrointestinal surgery. Chitosan was blended with polycaprolactone in a solvent mixture of acetic acid and water. Membranes were formed with a range of 50/50%, 60/40%, 65/35%, 70/30% and 80/20% polycaprolactone/chitosan. The tensile properties of the blends were examined over a time period to access material degradation. In addition the biocompatibilities of the polycaprolactone/chitosan blends were tested for cytotoxic effect using primary tendon fibroblastic cells. This research concluded that the polycaprolactone/chitosan was non-toxic to the fibroblasts cells in-vitro. Analysis of the mechanical properties of the blends showed a range of mechanical strengths and polymer life spans. Overall, blends of 65/35%, 70/30% and 80/20% polycaprolactone/chitosan emerged as possible candidates for the production of a gastrointestinal stent.

THE DEVELOPMENT AND STABILITY ANALYSIS OF A NONLINEAR GROWTH MODEL FOR MICROORGANISMS

A nonlinear dynamic model of microbial growth is established based on the theories of the diffusion response of thermodynamics and the chemotactic response of biology. Except for the two traditional variables, i.e. the density of bacteria and the concentration of attractant, the pH value, a crucial influencing factor to the microbial growth, is also considered in this model. The pH effect on the microbial growth is taken as a Gaussian function G0e-(f- fc)2/G1, where G0, G1 and fc are constants, f represents the pH value and fc represents the critical pH value that best fits for microbial growth. To study the effects of the reproduction rate of the bacteria and the pH value on the stability of the system, three parameters a, G0 and G1 are studied in detail, where a denotes the reproduction rate of the bacteria, G0 denotes the impacting intensity of the pH value to microbial growth and G1 denotes the bacterial adaptability to the pH value. When the effect of the pH value of the solution which microorganisms live in is ignored in the governing equations of the model, the microbial system is more stable with larger a. When the effect of the bacterial chemotaxis is ignored, the microbial system is more stable with the larger G1 and more unstable with the larger G0 for f0 > fc. However, the stability of the microbial system is almost unaffected by the variation G0 and G1 and it is always stable for f0 fc. However, the system is more unstable with larger a for f0 fc. The results obtained in this study provide a biophysical insight into the understanding of the growth and stability behavior of microorganisms.

Using an infra-red sensor to measure the dynamic behaviour of N2O gas escaping through different sized holes

An anastomosis is a surgical procedure that consists of the re-connection of two parts of an organ and is commonly required in cases of colorectal cancer. Approximately 80% of the patients diagnosed with this problem require surgery. The malignant tissue located on the gastrointestinal track must be resected and the most common procedure adopted is the anastomosis. Studies made with 2,980 patients that had this procedure, show that the leakage through the anastomosis was 5.1%. This paper discusses the dynamic behavior of N2O gas through different sized leakages as detected by an Infra-Red gas sensor and how the sensors response time changes depending on the leakage size. Different sized holes were made in the rigid tube to simulate an anastomostic leakage. N2O gas was injected into the tube through a pipe and the leakage rate measured by the infra-red gas sensor. Tests were also made experimentally also using a CFD (Computational Fluid Dynamics) package called FloWorks. The results will be compared and discussed in this paper.

Disinfection of clinical materials using photo-activated tolonium chloride solution

Photo-activated disinfection is beginning to be used in dental surgery to treat deep seated bacterial infection. It works by combining a photosensitiser and light of a specific frequency to generate singlet oxygen which is toxic to many types of bacteria. It is suggested that this technique could be used as a means to help treat infection more generally. To do so, it needs to work with materials and geometries exhibiting different physical and optical characteristics to teeth. In these trials, samples of stainless steel and polymethylmethacrylate were exposed to bacterial solutions of Staphylococcus aureus and Staphylococcus epidermis. These were treated with tolonium chloride-based photo-activated disinfection regimes showing positive results with typically 4 log10 reductions in colony forming units. Tests were also carried out using slotted samples to represent geometric features which might be found on implants. These tests, showed disinfectant effect however to a much lesser degree.

IMPLEMENTING CDIO - REVOLUTION OR EVOLUTION ?

While the CDIO standards and syllabus give a strong framework upon which to develop good quality engineering programmes, the exact means by which Universities and Colleges implement these is often less clear. Within the UK and Ireland CDIO region most institutions have gradually evolved their programmes to meet the CDIO standards. At Aston University we have instead, for local reasons, opted for a rapid step-change to create a swift and revolutionary change within our programmes. This was done for a number of purely educational reasons to ensure our students could get an enhanced learning experience from a very early stage. There were also however other considerations which influenced the nature of our approach including being able to make a bold statement of intent to academic and executive staff within the University. While this methodology has reaped significant rewards it has not been a painless experience. This paper will outline some aspects of our own experience and the decision making processes used while examining a number of other strategies from around the CDIO community.

CDIO and resources - Can we do it on a budget ?

Universities are continually under pressure to do more in terms of delivery, for less in terms of resources. For engineering and design courses, particularly those where a high level of practical project work is expected, this can be a particular challenge. The session will be structured around participants taking part in a simple, low cost and hopefully enjoyable CDIO activity in order to catalyse debate amongst participants on effective CDIO learning under limited resource.

Step Change Implementation of CDIO - The Aston University Story

The aim of this paper is to provide a comprehensive account of the experience of Mechanical Engineering & Design (MED) at Aston University in adopting a system level implementation of the CDIO framework at EQF Level 4. This is Aston’s first experience of CDIO and represents a step-change in learning and teaching philosophy from a long-established traditional engineering science didactic format. The paper describes the reasons for changing, the innovative teaching and learning practices that have been employed, how it has been implemented, and the experiences of staff involved during its development and practical implementation. The account shows the progress that Aston has made in its first semester of implementation and details some of the cultural challenges it has faced, along with some of the unexpected benefits of improving learning and teaching practice. Through building engineering and design programmes around large 30 credit active learning modules based upon the CDIO framework Aston academics have found that early stage implementation has increased efficiencies in terms of reduced assessment loading by 54 % and reduced space utilisation requirements by 37 %. Furthermore the changes have been made without significant increase in workload beyond the creation of new learning experiences, and without sacrificing academic challenge. Successful implementation of the new CDIO based programmes have been demonstrated as being effective at increasing student engagement, creativity and problem solving in both practical, active learning sessions and conventional declarative knowledge learning sessions.

Disinfection of Surgical Materials Using Photo-Activated Tolonium Chloride

Photo-activated disinfection is a technique which has recently become available for use in disinfection in dentistry. This technique makes use of the dye toluidine blue O coupled to a low powered laser to generate singlet oxygen which kills the bacteria without harming the patient. In this paper trials were performed to try to investigate the possibility of the technique for use in other medical applications, particularly related to implants, and orthopedic fixtures. In the trials, samples of stainless steel and polymethylmethacrylate (PMMA) were exposed to Staphylococcus Aureus and Staphylococcus Epidermis bacteria before being treated with a variety of irradiation exposures. Results found that if laser exposure energy exceeded 4.25 J/cm2 then a log reduction of 4 times CFU/cm2 might be expected. Results were similar for both the highly reflective stainless steel and transparent PMMA. Trials were also performed using light emitting diode technology and while these results were less effective, it is felt that the rapid rate of developments in this technology could lead to a cost effective route to rolling photo-activated disinfection out to many more medical applications.

Material and Structures for Gastrointestinal Stents

Stents are used to counteract and relieve in-vivo duct or vessel obstructions. The purpose of the current study is to select a biocompatible, biodegradable material for use in the manufacture of stents to counteract anastomotic leakage following gastrointestinal surgery. Chitosan a biocompatible, biodegradable environmentally friendly natural polysaccharide was blended with polycaprolactone, a versatile synthetic polymer. This material was fabricated in the form of sheets by moulding and curing blends of chitosan / polycaprolactone. The tensile strength of chitosan and chitosan / polycaprolactone blends were investigated. These tensile tests were carried out on chitosan and chitosan / polycaprolactone blends of 50/50, 40/60, 30/70 and 20/80 wt/wt %, cured in 5% sodium hydroxide. The chitosan / polycaprolactone blends were then formed into stents. The sheet mouldings were wound around a stainless steel stent former while fixing the layers together with un-cured chitosan / polycaprolactone blend and subsequently curing the layers together with sodium hydroxide, producing the stent shape.