Novel biodegradable fibres for applications in tissue engineering and drug delivery

The preparation and characterisation of novel biodegradable polymer fibres for application in tissue engineering and drug delivery are reported. Poly(e-caprolactone) (PCL) fibres were produced by wet spinning from solutions in acetone under low shear (gravity flow) conditions. The tensile strength and stiffness of as-spun fibres were highly dependent on the concentration of the spinning solution. Use of a 6% w/v solution resulted in fibres having strength and stiffness of 1.8 MPa and 0.01 GPa respectively, whereas these values increased to 9.9 MPa and 0.1 GPa when fibres were produced from 20% w/v solutions. Cold drawing to an extension of 500% resulted in further increases in fibre strength (up to 50 MPa) and stiffness (0.3 GPa). Hot drawing to 500% further increased the fibre strength (up to 81 MPa) and stiffness (0.5 GPa). The surface morphology of as-spun fibres was modified, to yield a directional grooved pattern by drying in contact with a mandrel having a machined topography characterised by a peak-peak separation of 91 mm and a peak height of 30 mm. Differential scanning calorimetery (DSC) analysis of as-spun fibres revealed the characteristic melting point of PCL at around 58°C and a % crystallinity of approximately 60%. The biocompatibility of as-spun fibres was assessed using cell culture. The number of attached 3T3 Swiss mouse fibroblasts, C2C12 mouse myoblasts and human umbilical vein endothelial cells (HUVECs) on as-spun, 500% cold drawn, and gelatin coated PCL fibres were observed. The results showed that the fibres promoted cell proliferation for 9 days in cell culture and was slightly lower than on tissue culture plastic. The morphology of all cell lines was assessed on the various PCL fibres using scanning electron microscopy. The cell function of HUVECs growing on the as-spun PCL fibres was evaluated. The ability HUVECs to induce an immune response when stimulated with lipopolysaccaride (LPS) and thereby to increase the amount of cell surface receptors was assessed by flow cytometry and reverse transcription-polymerase chain reaction (RT-PCR). The results showed that PCL fibres did not inhibit this function compared to TCP. As-spun PCL fibres were loaded with 1 % ovine albumin (OVA) powder, 1% OVA nanoparticles and 5% OVA nanoparticles by weight and the protein release was assessed in vitro. PCL fibres loaded with 1 % OVA powder released 70%, 1% OVA nanoparticle released 60% and the 5% OVA nanoparticle released 25% of their protein content over 28 days. These release figures did not alter when the fibres were subjected to lipase enzymatic degradation. The OVA released was examined for structural integrity by SDS-PAGE. This showed that the protein molecular weight was not altered after incorporation into the fibres. The bioactivity of progesterone was assessed following incorporation into PCL fibres. Results showed that the progesterone released had a pronounced effect on MCF-7 breast epithelial cells, inhibiting their proliferation. The PCL fibres display high fibre compliance, a potential for controlling the fibre surface architecture to promote contact guidance effects, favorable proliferation rate of fibroblasts, myoblasts and HUVECs and the ability to release pharmaceuticals. These properties recommended their use for 3-D scaffold production in soft tissue engineering and the fibres could also be exploited for controlled presentation and release of biopharmaceuticals such as growth factors.

A study of factors relating to health and safety in the engineering industry in Northern Ireland

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Researching with, not on:using photography in researching street children in Accra, Ghana

What is discussed in this chapter is work-in-progress, an opportunity for reflection upon elements of an on-going research project examining the lives of street children in Accra, Ghana. Street children have received much research in recent years but our project is, we believe, distinctive in two respects. The first of these is that access to reliable data on the growing presence of children on the streets of African cities is often problematic. Available research is often diffuse and hard to access, it is more often than not driven by the short-term requirements of specific programmes and interventions and as a consequence can be lacking in depth, rigour and innovation. Without the means to provide a sufficiently self-conscious and critical engagement with accepted understandings of the lives of street children, consideration of the experience of street children in Africa continues to rely heavily on the more capacious and better disseminated research from the Americas (e.g., Mickelson, 2000). At the very least, Africa's specific experience of large population displacements, diversity of family forms, rapid urbanisation, vigorous structural adjustment and internal conflict raise important questions about the appropriateness of such ready generalisations. Judith Ennew (2003, p. 4) is clear that caution is needed in an uncritical endorsement of the “globalisation of the street child based on Latin American work”. She is equally mindful, however, that as far as Africa is concerned the absence of reliable evidence continues to hinder debate.

Experiences on dynamic simulation software in chemical engineering education

Commercial process simulators are increasing interest in the chemical engineer education. In this paper, the use of commercial dynamic simulation software, D-SPICE® and K-Spice®, for three different chemical engineering courses is described and discussed. The courses cover the following topics: basic chemical engineering, operability and safety analysis and process control. User experiences from both teachers and students are presented. The benefits of dynamic simulation as an additional teaching tool are discussed and summarized. The experiences confirm that commercial dynamic simulators provide realistic training and can be successfully integrated into undergraduate and graduate teaching, laboratory courses and research. © 2012 The Institution of Chemical Engineers.

Practically oriented design projects in mechatronics engineering:a case study of design experiences and outcomes

This paper discusses and presents a case study of a practically oriented design project together with a few examples of implemented design projects recently incorporated into an undergraduate system course at the mechatronics engineering department in Ah-Balqa’ Applied University. These projects have had a positive impact on both the department and its graduates. The focus of these projects is the design and implementation of processor-based system. This helps graduate students cross the border between hardware design and software design. Our case study discusses the research methodology adopted for the physical development of the project, the technology used in the project, and the design experiences and outcomes.

Using observation ageing to improve Markovian model learning in QoS engineering

Markovian models are widely used to analyse quality-of-service properties of both system designs and deployed systems. Thanks to the emergence of probabilistic model checkers, this analysis can be performed with high accuracy. However, its usefulness is heavily dependent on how well the model captures the actual behaviour of the analysed system. Our work addresses this problem for a class of Markovian models termed discrete-time Markov chains (DTMCs). We propose a new Bayesian technique for learning the state transition probabilities of DTMCs based on observations of the modelled system. Unlike existing approaches, our technique weighs observations based on their age, to account for the fact that older observations are less relevant than more recent ones. A case study from the area of bioinformatics workflows demonstrates the effectiveness of the technique in scenarios where the model parameters change over time.

A matter of professionalism? Reflection and reflexivity in continuing engineering education and practice

The argument that this paper sets out to critique is that in order to promote professionalism in Engineering Education and Practice, graduate level engineering programmes need to introduce the concepts of reflection and reflexivity into the curriculum right from the onset. By focusing upon the delivery of a newly developed „Work Based‟ Master’s level programme in Professional Engineering, this paper provides an overview of the first part of an empirical study which sets out to investigate the challenges associated with embedding reflection and reflexivity into Engineering Education. The paper concludes by noting that whilst student engineers may struggle with the concepts of reflection and reflexivity, with support and encouragement such difficulties can be overcome. Moreover, by encouraging students to reflect upon their Professional Practice, the programme not only enables students to consider how they may apply what they have learnt to their Professional Practice, but also encourages them to think about how they can link their experiences as Professional Engineers to what and how they learn both whilst on the programme but also as lifelong learners.

Remote sensing applied to slope stability in mountainous roads in Iran

The Alborz Mountain range separates the northern part of Iran from the southern part. It also isolates a narrow coastal strip to the south of the Caspian Sea from the Central Iran plateau. Communication between the south and north until the 1950's was via two roads and one rail link. In 1963 work was completed on a major access road via the Haraz Valley (the most physically hostile area in the region). From the beginning the road was plagued by accidents resulting from unstable slopes on either side of the valley. Heavy casualties persuaded the government to undertake major engineering works to eliminate ''black spots" and make the road safe. However, despite substantial and prolonged expenditure the problems were not solved and casualties increased steadily due to the increase in traffic using the road. Another road was built to bypass the Haraz road and opened to traffic in 1983. But closure of the Haraz road was still impossible because of the growth of settlements along the route and the need for access to other installations such as the Lar Dam. The aim of this research was to explore the possibility of applying Landsat MSS imagery to locating black spots along the road and the instability problems. Landsat data had not previously been applied to highway engineering problems in the study area. Aerial photographs are better in general than satellite images for detailed mapping, but Landsat images are superior for reconnaissance and adequate for mapping at the 1 :250,000 scale. The broad overview and lack of distortion in the Landsat imagery make the images ideal for structural interpretation. The results of Landsat digital image analysis showed that certain rock types and structural features can be delineated and mapped. The most unstable areas comprising steep slopes, free of vegetation cover can be identified using image processing techniques. Structural lineaments revealed from the image analysis led to improved results (delineation of unstable features). Damavand Quaternary volcanics were found to be the dominant rock type along a 40 km stretch of the road. These rock types are inherently unstable and partly responsible for the difficulties along the road. For more detailed geological and morphological interpretation a sample of small subscenes was selected and analysed. A special developed image analysis package was designed at Aston for use on a non specialized computing system. Using this package a new and unique method for image classification was developed, allowing accurate delineation of the critical features of the study area.

Microcomputers for civil engineering consultancy in developing countries

The civil engineering industry generally regards new methods and technology with a high amount of scepticism, preferring to use traditional and trusted methods. During the 1980s competition for civil engineering consultancy work in the world has become fierce. Halcrow recognised the need to maintain and improve their competitive edge over other consultants. The use of new technology in the form of microcomputers was seen to be one method to maintain and improve their repuation in the world. This thesis examines the role of microcomputers in civil engineering consultancy with particular reference to overseas projects. The involvement of civil engineers with computers, both past and present, has been investigated and a survey of the use of microcomputers by consultancies was carried out, the results are presented and analysed. A resume of the state-of-the-art of microcomputer technology was made. Various case studies were carried out in order to examine the feasibility of using microcomputers on overseas projects. One case study involved the examination of two projects in Bangladesh and is used to illustrate the requirements and problems encountered in such situations. Two programming applications were undertaken, a dynamic programming model of a single site reservoir and the simulation of the Bangladesh gas grid system. A cost-benefit analysis of a water resources project using microcomputers in the Aguan Valley, Honduras was carried out. Although the initial cost of microcomputers is often small, the overall costs can prove to be very high and are likely to exceed the costs of traditional computer methods. A planned approach for the use of microcomputers is essential in order to reap the expected benefits and recommendations for the implementation of such an approach are presented.

Fluctuation-induced traffic congestion in heterogeneous networks

In studies of complex heterogeneous networks, particularly of the Internet, significant attention was paid to analyzing network failures caused by hardware faults or overload, where the network reaction was modeled as rerouting of traffic away from failed or congested elements. Here we model another type of the network reaction to congestion - a sharp reduction of the input traffic rate through congested routes which occurs on much shorter time scales. We consider the onset of congestion in the Internet where local mismatch between demand and capacity results in traffic losses and show that it can be described as a phase transition characterized by strong non-Gaussian loss fluctuations at a mesoscopic time scale. The fluctuations, caused by noise in input traffic, are exacerbated by the heterogeneous nature of the network manifested in a scale-free load distribution. They result in the network strongly overreacting to the first signs of congestion by significantly reducing input traffic along the communication paths where congestion is utterly negligible. © Copyright EPLA, 2012.

Modeling high-speed network traffic with truncated α-stable processes

It has been reported that high-speed communication network traffic exhibits both long-range dependence (LRD) and burstiness, which posed new challenges in network engineering. While many models have been studied in capturing the traffic LRD, they are not capable of capturing efficiently the traffic impulsiveness. It is desirable to develop a model that can capture both LRD and burstiness. In this letter, we propose a truncated a-stable LRD process model for this purpose, which can characterize both LRD and burstiness accurately. A procedure is developed further to estimate the model parameters from real traffic. Simulations demonstrate that our proposed model has a higher accuracy compared to existing models and is flexible in capturing the characteristics of high-speed network traffic. © 2012 Springer-Verlag GmbH.

Fluctuation-driven traffic congestion in a scale-free model of the Internet

In studies of complex heterogeneous networks, particularly of the Internet, significant attention was paid to analysing network failures caused by hardware faults or overload. There network reaction was modelled as rerouting of traffic away from failed or congested elements. Here we model network reaction to congestion on much shorter time scales when the input traffic rate through congested routes is reduced. As an example we consider the Internet where local mismatch between demand and capacity results in traffic losses. We describe the onset of congestion as a phase transition characterised by strong, albeit relatively short-lived, fluctuations of losses caused by noise in input traffic and exacerbated by the heterogeneous nature of the network manifested in a power-law load distribution. The fluctuations may result in the network strongly overreacting to the first signs of congestion by significantly reducing input traffic along the communication paths where congestion is utterly negligible. © 2013 IEEE.