This study has investigated the search options and features teachers use and prefer to have, when personalising their online search for teaching resources. This study focused on making web searching easier for UK teacher practitioners at primary, secondary and post-compulsory levels. In this study, a triangulated mixed method approach was carried out in a two phase iterative case study involving 75 teacher practitioners working in the UK educational setting. In this case study, a sequential evidence gathering method called ‘System Development Life Cycle’ (SDLC) was adapted linking findings obtained from the structured questionnaires, observations and semi-structured interviews in order to design, develop and test two versions of an experimental search tool called “PoSTech!”. This research has contributed to knowledge by offering a model of teachers’ web information needs and search behaviour. In this model twelve search options and features mostly used by teachers when personalising their search for finding online teaching resources via the revised search tool are listed, in order of popularity. A search options is selected by the teacher and features is the characteristic of an option teachers experiences. For example, search options 'Subject', ‘Age Group’, ‘Resource Type’, ‘Free and/ Paid resources’, ‘Search results language’, and search features that ‘Store search options selected by individual teachers and their returned results’. Teachers’ model of web information needs and search behaviour could be used by the Government, teacher trainers and search engine designers to gain an insight into the information needs and search behaviours of teachers when searching for online teaching resources by means of tackling technical barriers faced by teachers, when using the internet. In conclusion, the research work presented in this thesis has provided the initial and important steps towards understanding the web searching information needs and search behaviours of individual teachers, working in the UK educational setting.

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No description available.

The development of a novel method of droplet levitation to be employed in lab-on-a-chip (LOC) applications relies upon the mechanism of thermocapillary convection (due to the temperature dependence of surface tension) to drive a layer of lubricating gas between droplet and substrate. The fact that most droplets of interest in LOC applications are aqueous in nature, coupled with the fact that success in effecting thermocapillary transport in aqueous solutions has been limited, has led to the development of a technique for the controlled encapsulation of water droplets within a shell of inert silicone oil. These droplets can then be transported, virtually frictionlessly, resulting in ease of transport due to the lack of friction as well as improvements in sample cross-contamination prevention for multiple-use chips. Previous reports suggest that levitation of spherical O(nL)-volume droplets requires squeezing to increase the apparent contact area over which the pressure in the lubricating layer can act allowing sufficient opposition to gravity. This research explores thermocapillary levitation and translation of O(nL)-volume single-phase oil droplets; generation, capture, levitation, and translation of O(nL)-volume oil-encapsulated water droplets to demonstrate the benefits and applicability to LOC operations.

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Many applications for the analysis and processing of biological materials require the enrichment of cell subpopulations. Conventional cell sorting systems are large and expensive with complex equipment that necessitates specialized personnel for operation. Employing microfluidics technology for lab-on-a-chip adaptation of these devices provides several benefits: improved transport control, reduced sample volumes, simplicity of operation, portability, greater accessibility, and reduced cost. The designs of microfluidic cell sorting chips vary widely in literature; evaluation and optimization efforts are rarely reported. This study intends to investigate the primary components of the design to understand the effect of various parameters and to improve the performance of the microfluidic chip. Optimized individual elements are incorporated into a proposed cell sorter chip with the ability to dynamically sort target cells from a non-homogeneous solution using electrical driving forces. Numerical and experimental results are used to evaluate the sample focusing element for controlled cell dispensing, the sorting configuration for target cell collection, and the flow elements for reduced pressure effects and prevention of flow blockages. Compact models are adapted to solve the potential field and flow field in the chip and to predict the focused sample stream width. A commercial CFD package is used to perform 2-D simulations of the potential, velocity, and concentration fields. A fluorescence microscopy visualization system is implemented to conduct experiments on several generations of chip designs. The data from sample focusing experiments, performed with fluorescent dye samples, is analyzed using a Gaussian distribution model proposed in this work. A technique for real-time monitoring of fluorescent microspheres in the microfluidic chip enables the use of dynamic cell sorting to emulate fully autonomous operation. The performance values obtained from these experiments are used to characterize the various design configurations. Sample focusing is shown to depend largely on the relative size of the sheath fluid channel and the sample channel, but is virtually independent of the junction shape. Savings in the applied potential can be achieved by utilizing the size dependency. The focusing performance also provides information for optimizing the widths of the channels relative to the cell size. Successful sorting of desired cells is demonstrated for several designs. Key parameters that affect the sorting performance are discussed; a design employing the use of supplemental fluid streams to direct the particle during collection is chosen due to a high sorting evaluation and a low sensitivity to flow anomalies. The necessary reduction of pressure influences to achieve reliable flow conditions is accomplished by introducing channel constrictions to increase the hydrodynamic resistance. Also, prolonged operation is realized by including particle filters in the proposed design to prevent blockages caused by the accumulation of larger particles. A greater understanding of the behaviour of various components is demonstrated and a design is presented that incorporates the elements with the best performance. The capability of the microfluidic chip is summarized based on experimental results of the tested designs and theoretical cell sorting relationships. Adaptation of this chip to a stand-alone, autonomous device can be accomplished by integrating an optical detection system and further miniaturization of the critical components.

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Automatic control of processes is a field that has evolved extensively over theyears to reduce downtime, improve quality and increase the productivity ofprocesses in manufacturing industries. ÅF Consult is a consult organization thatprovides industrial solutions worldwide. In order to test equipment andintroduce employees and students to control systems, a PLC based lab station isnecessary. The methodology used in the project is based on a literature study,followed by the solution approach and finally an evaluation. A DistributedControl System setup using a Siemens S7-300 and a Siemens S7-400 PLC hasbeen developed. The PLCs communicate using PROFIBUS DP. The station isdivided into two major parts: a conveyor belt with transportation functionalityand a robotic arm with pick-and-place functionality. The station is providedwith equipment similar to systems currently used in paper and pulp industries.Existing solutions for unloading of paper reels in the paper and pulp industriesare non-universal due to extra equipment like pre-installed rails in trailers. Anautomated solution for unloading using a robotic arm is therefore presented,designed to reduce paper reel handling and to have the possibility to unload toany trailer. The lab station is implemented according to ÅF Consults demandsof a portable, field related station. The low budget resulted in cheap equipmentthat lack accuracy, mainly resulting in issues relating to the ability to control therobotic arm properly. The unloading solution is emulated as a lab task on thestation, showing that a control setup similar to the lab station would be a goodapproach for a real implementation solution.

Microdroplet microfluidics has gained much interested in the past decade due to its ability to conduct a wide variety of biological and microfluidic experiments with extremely high repeatability on a mass scale. In particular the ability to culture multiple batches of cells by creating microdroplets with a single encapsulated cell and observe their growth overtime allows for specific conditioning of cells. In addition, when conducting co-culture experiment the induction of a certain stimulus may provide observational rare differences in growth that may be characterized by harnessing a single batch of cells out of thousands of samples. This thesis first presents a variety of microdroplet microfluidic devices that use specific techniques to sufficiently produce, synchronize, merge, and analyze microdroplets. Although many of the devices are capable of producing stable droplets and somewhat efficient synchronization, the overall merging efficiency for most passive or active merging methods alone is lacking. Improvements on such methods and the incorporation of multiple merging methods can lead to a higher overall merging efficiency and greater droplet stability. Also, multiple droplet detection methods can be employed to analyze cellular growth under different conditions, while passive or active sorting methods can be used to acquire particular microdroplet samples downstream. The work presented in this thesis entails the characterization and detailed analysis of all aspects of microdroplet microfluidics necessary to adequately produce a microdroplet co-culture device for microbial studies. This includes the incorporation of multiple microdroplet generators for the production of water droplets immersed in oil serving as bio-reactors for cell culture experiments. In addition, multiple microdroplet synchronization devices were tested to sufficiently align multiple trains of droplets for downstream merging using a variety of passive, active, or combination merging methods. In particular, the use of an electric field can cause destabilization of the surfactant surrounding a microdroplet and allow for the formation of a liquid bridge. The formation of this liquid bridge in conjunction with passive merging methods can lead to droplet electrocoalescence. The incorporation of a more uniform electric field that reduces the angle between the droplet dipole moment and E-field can lead to better droplet merging while reducing voltage and frequency requirements observed in previously publications. The testing, observation, and optimization of such aspects of microdroplet microfluidics are crucial for the advancement and production of sound microdroplet culture devices for a variety of applications including the analysis of dangerous pathogenic substances, drug testing or delivery, and genetic studies.

Continuous progress in the nanotechnology field has allowed for the emergence of powerful, nanopore-based detection technology. Solid-state nanopores were developed for next-generation sequencing and single-molecule detection. They are advantageous over their biological counterpart because they offer robustness, stability, tunable pore size and the ability to be integrated within a microfluidic device. With all of these attractive attributes, solid-state nanopores are a top contender for point-of-care diagnostic technologies. However, hindering their performance is an inability to distinguish between small molecules, pore-clogging, and the detection rate's dependence on sample concentration. The concentration-dependent detection rate becomes particularly evident at low sample concentrations (<1 nM), sometimes taking hours for the nanopore to sense a single molecule because of diffusion. The inability to distinguish between small molecules can be addressed using DNA nanostructures; however, pore-clogging and variable detection rates hinder its potential in a clinical setting. This thesis proposes a microfluidic device design and methodology that seeks to mitigate pore-clogging and improve the detection rate for dilute samples. DNA coated microbeads will create a bead column within the microfluidic device and confine the target molecules to an extremely small (20 nL) volume. The sample can be washed, ridding the contaminants, and eluted on-chip, so the sample is purified and concentrated, affording a more reliable sensing performance. First, a magnetic microbead DNA assay was optimized off-chip, and the capture and release efficiencies were monitored using a Biotek™ Epoch™ 2 spectrophotometer (Chapter 2). Next, a novel microfluidic device design was optimized and validated to ensure precise sample manipulation (Chapter 3). Finally, the microbead assay was incorporated into the microfluidic device for sample concentration (Chapter 4). Fluorescence microscopy results suggest successful DNA elution from the microbeads within the microfluidic device, allowing for a 28.5 X concentration increase. This platform shows promise for sample preconcentration by reducing the starting DNA sample volume of 25 µL to 20 nL, which could improve the speed of solid-state nanopore sensing.