Physical modelling of amorphous thermoplastic polymer and numerical simulation of micro hot embossing process

Micro hot embossing process is considered as one of the most promising micro replication processes for manufacturing of polymeric components, especially for the high aspect ratio components and large surface structural components. A large number of hot embossing experimental results have been published, the material modelling and processes simulation to improve the quality of micro replication by hot embossing process are still lacking. This paper consists to 3D modelling of micro hot embossing process with amorphous thermoplastic polymers, including the mechanical characterisation of polymers properties, identification of the viscoelastic behaviour law of the polymers, numerical simulation and experimental investigation of micro hot embossing process. Static compression creep tests have been carried out to investigate the selected polymers’ viscoelastic properties. The Generalized Maxwell model has been proposed to describe the relaxation modulus of the polymers and good agreement has been observed. The numerical simulation of the hot embossing process in 3D has been achieved by taking into account the viscoelastic behaviour of the polymers. The microfluidic devices with the thickness of 2 mm have been elaborated by hot embossing process. The hot embossing process has been carried out using horizontal injection/compression moulding equipment, especially developed for this study. A complete compression mould tool, equipped with the heating system, the cooling system, the ejection system and the vacuum system, has been designed and elaborated in our research. Polymer-based microfluidic devices have been successfully replicated by the hot embossing process using the compression system developed. Proper agreement between the numerical simulation and the experimental elaboration has been observed. It shows strong possibility for the development of the 3D numerical model to optimize the micro hot embossing process in the future

Tunnel switch diode based on AlSb/GaSb heterojunctions

We report on tunnel switch diodes based on AlSb barriers and GaSb p–n junctions grown by molecular beam epitaxy. These were the devices with thyristor like switching in the GaSb/AlSb system. The characteristic "S" shaped current–voltage curve was found to occur for structures with AlSb barriers less than 300 Å thick. The switching voltage and current density exhibited less sensitivity to barrier and epilayer thickness than was predicted by the punch-through model. The results were correlated with drift diffusion simulations which have been modified to account for the presence of a tunneling contact

Current influences on traditional Chinese medicine education in the UK: the experience of a collaborative programme between Middlesex University and Beijing University of chinese medicine.

A long and successful collaboration has existed between Middlesex University and Beijing University of Chinese Medicine in the delivery of high quality education and practitioner training in Traditional Chinese Medicine (TCM) in the UK. A joint degree programme was validated by the two Universities in 1997 offering integrated training at undergraduate level in both Chinese Herbal Medicine and Acupuncture & Moxibustion. This programme was the first of its kind to be offered in Europe by a public sector higher education institute. Students on the programme undertake academic study at Middlesex University and gain clinical experience on placement in hospitals affiliated to Beijing University of Chinese Medicine in addition to practitioner training in the UK at the Asante Academy of Chinese Medicine. There have been several drivers for the relatively recent move towards degree status for TCM, along with other Complementary and Alternative Medicine (CAM) professions in the UK. Concern over patient safety and the rising popularity of CAM led to an inquiry being held by a House of Lords select committee. Their report, published in 2000, made several recommendations, including that the acupuncture and herbal medicine professions seek statutory status. Following this recommendation, the UK Department of Health launched a public consultation in March 2004, seeking views on proposals for statutory professional self-regulation of these professions. In developing its proposals, the Department of Health considered and built on the recommendations of two independent regulatory working groups for Acupuncture and Herbal Medicine. The views expressed in the consultation will help frame the provisions to be included in an order to be laid before the UK Parliament prior to becoming law. The matters which concern a regulatory body include education, registration, continuing professional development and disciplinary and ethical matters. A pre-requisite for regulation is the establishment of a core curriculum and minimum standards for competent practice as well as an expert mechanism to assess educational qualifications. This paper considers the impact of the move towards statutory self-regulation on the development of TCM education in the UK and the implications of future regulatory frameworks for educational institutions