Modified hydrogel matrices in fibre optic sensors

Common problems encountered in clinical sensing are those of non-biocompatibility, and slow response time of the device. The latter, also applying to chemical sensors, is possibly due to a lack of understanding of polymer support or membrane properties and hence failure to optimise membranes chosen for specific sensor applications. Hydrogels can be described as polymers which swell in water. In addition to this, the presence of water in the polymer matrix offers some control of biocompatibility. They thus provide a medium through which rapid transport of a sensed species to an incorporated reagent could occur. This work considers the feasibility of such a system, leading to the design and construction of an optical sensor test bed. The development of suitable membrane systems and of suitable coating techniques in order to apply them to the fibre optics is described. Initial results obtained from hydrogel coatings implied that the refractive index change in the polymer matrix, due to a change in water content with pH is the major factor contributing to the sensor response. However the presence of the colourimetric reagent was also altering the output signal obtained. An analysis of factors contributing to the overall response, such as colour change and membrane composition were made on both the test bed, via optical response, and on whole membranes via measurement of water content change. The investigation of coatings with low equilibrium water contents, of less than 10% was carried out and in fact a clearer signal response from the test bed was noted. Again these membranes were suprisingly responding via refractive index change, with the reagent playing a primary role in obtaining a sensible or non-random response, although not in a colourimetric fashion. A photographic study of these coatings revealed some clues as to the physical nature of these coatings and hence partially explained this phenomenon. A study of the transport properties of the most successful membrane, on a coated wire electrode and also on the fibre optic test bed, in a series of test environments, indicated that the reagent was possibly acting as an ion exchanger and hence having a major influence on transport and therefore sensor characteristics.

Properties and performance of polymer modified cements and mortars

Polymer modified cements and mortars have become popular for use as patch repair materials. General evidence suggests that these materials offer considerable improvements compared to traditional mortars although the mechanisms for this are not fully understood. This work elucidates the factors which govern some properties and performance of different polymer systems. In view of the wide range of commercial systems available, investigations concentrated on the use of three of the most commonly available groups of polymers. These were: (1) Styrene Butadiene Rubber (SBR), (2) Acrylics and, (3) Ethylene Vinyl Acetates (EVA). The later two were in the form of both emulsions and redispersible powders. Experiments concentrated on: (1) Rheological behaviour of polymer modified cement pastes; (2) Workability of polymer modified mortars; (3) Influence of curing conditions on the pore size distribution and diffusion of chloride ions; (4) Bond strength of polymer modified cement and mortar patches; and (5) Microscopic examination and semi-quantitative analyses of the bulk and interfacial microstructures. The following main conclusions were reached: (1) The addition of polymer emulsions have a considerable influence on the workability of fresh cement pastes, the extent of this depending on the type of system used. (2) The rheological parameters of fresh polymer modified mortars can be established using a two-point workability test which may be used when comparing the properties of different systems at constant workability. (3) Curing conditions affect the properties of polymer modified systems and a wet/dry curing regime was essential for good adhesion of these materials to mortar substrates. (4) In contrast, the wet/dry curing regime resulted in a curing affected zone at the surface of patch materials. This can result in a much coarser pore structure and enhanced diffusion of e.g. chloride ions. (5) The microstructure of polymer modified systems was very different compared with the unmodified cement/mortar and varied depending on curing conditions.

Apparatus and test methods for measuring the impact of golf balls on turf and their application in the field

An apparatus was developed to project spinning golf balls directly onto golf greens. This employed a modified baseball/practice machine with two counter-rotating pneumatic wheels. The speed of the wheels could be varied independently allowing backspin to be given to the ball. The ball was projected into a darkened enclosure where the motion of the ball before and after impacting with the turf was recorded using a still camera and a stroboscope. The resulting photographs contained successive images of the ball on a single frame of film. The apparatus was tested on eighteen golf courses resulting in 721 photographs of impacts. Statistical analysis was carried out on the results of the photographs and from this, two types of green emerged. On the first, the ball tended to rebound with topspin, while on the second, the ball retained backspin after impact if the initial backspin was greater than about 350 rads-1. Eleven tests were devised to determine the characteristics of greens and statistical techniques were used to analyse the relationships between these tests. These showed the effects of the green characteristics on ball/turf impacts. It was found that the ball retained backspin on greens that were freely drained and had less than 60% of Poa annua (annual meadow grass) in their swards. Visco-elastic models were used to simulate the impact of the ball with the turf. Impacts were simulated by considering the ball to be rigid and the turf to be a two layered system consisting of springs and dampers. The model showed good agreement with experiment and was used to simulate impacts from two different shots onto two contrasting types of green.

Ophthalmic engineering:the development of novel instrumentation to further research in the field

The principle theme of this thesis is the advancement and expansion of ophthalmic research via the collaboration between professional Engineers and professional Optometrists. The aim has been to develop new and novel approaches and solutions to contemporary problems in the field. The work is sub divided into three areas of investigation; 1) High technology systems, 2) Modification of current systems to increase functionality, and 3) Development of smaller more portable and cost effective systems. High Technology Systems: A novel high speed Optical Coherence Tomography (OCT) system with integrated simultaneous high speed photography was developed achieving better operational speed than is currently available commercially. The mechanical design of the system featured a novel 8 axis alignment system. A full set of capture, analysis, and post processing software was developed providing custom analysis systems for ophthalmic OCT imaging, expanding the current capabilities of the technology. A large clinical trial was undertaken to test the dynamics of contact lens edge interaction with the cornea in-vivo. The interaction between lens edge design, lens base curvature, post insertion times and edge positions was investigated. A novel method for correction of optical distortion when assessing lens indentation was also demonstrated. Modification of Current Systems: A commercial autorefractor, the WAM-5500, was modified with the addition of extra hardware and a custom software and firmware solution to produce a system that was capable of measuring dynamic accommodative response to various stimuli in real time. A novel software package to control the data capture process was developed allowing real time monitoring of data by the practitioner, adding considerable functionality of the instrument further to the standard system. The device was used to assess the accommodative response differences between subjects who had worn UV blocking contact lens for 5 years, verses a control group that had not worn UV blocking lenses. While the standard static measurement of accommodation showed no differences between the two groups, it was determined that the UV blocking group did show better accommodative rise and fall times (faster), thus demonstrating the benefits of the modification of this commercially available instrumentation. Portable and Cost effective Systems: A new instrument was developed to expand the capability of the now defunct Keeler Tearscope. A device was developed that provided a similar capability in allowing observation of the reflected mires from the tear film surface, but with the added advantage of being able to record the observations. The device was tested comparatively with the tearscope and other tear film break-up techniques, demonstrating its potential. In Conclusion: This work has successfully demonstrated the advantages of interdisciplinary research between engineering and ophthalmic research has provided new and novel instrumented solutions as well as having added to the sum of scientific understanding in the ophthalmic field.

Bending characteristics of fiber long-period gratings with cladding index modified by femtosecond laser

A femtosecond laser has been used to asymmetrically modify the cladding of fiber containing long-period gratings. Following modification, devices in single-mode fiber are shown to be capable of sensing the magnitude and direction of bending in one plane by producing blue and red wavelength shifts depending upon the orientation of the bend. The resulting curvature sensitivities were -1.62 and +3.82 nm·m. Devices have also been produced using an elliptical core fiber to study the effects of the cladding modification on the two polarization eigenstates. A cladding modification applied on the fast axis of the fiber is shown to affect the light in the fast axis much more significantly than the light in the orthogonal state; this behavior may ultimately lead to a sensor capable of detecting the direction of bending in two dimensions for applications in shape sensing. © 2006 IEEE.

The antioxidant potential of modified quercetins and quercetin-metal complexes

Quercetin is a naturally occurring polyphenol compound present in grapes, red wine, tea, apples and some vegetables. Like other flavonoids, it has been found to have antioxidant activity in studies in vitro, although there is still much debate about the bioavailability of flavonoids in the diet and their in vivo antioxidant activity. In general, it is thought that the antioxidant efficiency of polyphenols increases with increasing hydroxylation of the rings, but there have been few studies of other substitutions. We have prepared several derivatives of quercetin, to test the effect of modification on their antioxidant potential. Sodium salts of quercetin-5-sulfonate and quercetin-5,8-sulfonate, and transition metal complexes of quercetin-5-sulfonate were analysed for their total antioxidant potential using the FRAP assay, and compared to unmodified quercetin. It was found that quercetin-5-sulfonate complexes with Zn, Cu(II), Fe(II) and Mg were all significantly better antioxidants than quercetin, quercetin-5-sulfonate was comparable to quercetin, whereas the sodium salt of quercetin-5,8-sulfonate had a decreased total antioxidant potential. Kinetic studies of the FRAP reaction showed no significant differences between quercitin and any of the derivatives. The reaction of all the quercetins in the FRAP assay was found to be slower to reach completion than ascorbate, and appeared to have biphasic characteristics. These results suggest that transition metal ions may facilitate the transfer of electrons from the polyphenol ring system to the oxidant, while substitution with S03 is electron-withdrawing and destabilizes the ring system. This is important both for understanding the antioxidant ability of flavonoids, and for the design of novel antioxidant compounds. Further work is being carried out to assess the ability of the quercetin complexes to protect cultured cells from oxidative stress.

Improved methodology to evaluate fracture properties of warm-mix asphalt using overlay test

This study developed a reliable and repeatable methodology to evaluate the fracture properties of asphalt mixtures with an overlay test (OT). In the proposed methodology, first, a two-step OT protocol was used to characterize the undamaged and damaged behaviors of asphalt mixtures. Second, a new methodology combining the mechanical analysis of viscoelastic force equilibrium in the OT specimen and finite element simulations was used to determine the undamaged properties and crack growth function of asphalt mixtures. Third, a modified Paris's law replacing the stress intensity factor by the pseudo J-integral was employed to characterize the fracture behavior of asphalt mixtures. Theoretical equations were derived to calculate the parameters A and n (defined as the fracture properties) in the modified Paris's law. The study used a detailed example to calculate A and n from the OT data. The proposed methodology was successfully applied to evaluate the impact of warm-mix asphalt (WMA) technologies on fracture properties. The results of the tested specimens showed that Evotherm WMA technology slightly improved the cracking resistance of asphalt mixtures, while foaming WMA technology provided comparable fracture properties. In addition, the study found that A decreased with the increase in n in general. A linear relationship between 2log(A) and n was established.

Effects of a modified English listening comprehension curriculum on students' achievement in English listening comprehension at Tamsui Oxford University College in Taiwan

Due to increased international trade, English as a foreign language is important to Taiwan. However, ESL teaching and learning in Taiwan emphasizes reading and writing skills only. ESL teaching in Taiwan causes students to lack competence in complete communication. Improving students' listening and speaking is a vital issue in Taiwan. ^ The purposes of this study are to determine the effects of a modified curriculum for the English listening comprehension course, to investigate whether the modified curriculum results in a significant improvement in student's listening comprehension, and to determine whether students were motivated to increase listening comprehension ability as a result of the new listening activities. An experimental and a control group, randomly assigned, received either the modified or the traditional curriculum at Tamsui Oxford University College (TOUC) in Taiwan over a fourteen week period of time. ^ A Michigan Listening Comprehension posttest was used to determine the difference in achievement between the two groups. A final examination was conducted to compare the two groups' achievement and to determine whether the goal of increasing listening comprehension achievement by using a modified curriculum was met. Subjects completed two questionnaires, one common form prior to class and another unique form for each group at the end of instruction. ^ Frequency distribution, chi-square, t-test for independent samples and analysis of covariance were used to analyze the data. The findings indicated that there were no significant differences in students' attitude and interest in English listening comprehension between those who were taught with an English listening modified curriculum compared with those students who were taught with a traditional curriculum. The findings also indicated that there was a difference in the final examination with the control group taught using the traditional curriculum scoring higher than the experimental group taught using the modified curriculum for performance in English listening comprehension, but there was no difference in scores on the Michigan Listening Comprehension Test (posttest). In addition, it was found that learning attitude and motivation influence students' learning. ^

Test of a smock system on CPR primary emergency measures and medical errors during simulated emergencies

Rates of survival of victims of sudden cardiac arrest (SCA) using cardio pulmonary resuscitation (CPR) have shown little improvement over the past three decades. Since registered nurses (RNs) comprise the largest group of healthcare providers in U.S. hospitals, it is essential that they are competent in performing the four primary measures (compression, ventilation, medication administration, and defibrillation) of CPR in order to improve survival rates of SCA patients. The purpose of this experimental study was to test a color-coded SMOCK system on: 1) time to implement emergency patient care measures 2) technical skills performance 3) number of medical errors, and 4) team performance during simulated CPR exercises. The study sample was 260 RNs (M 40 years, SD=11.6) with work experience as an RN (M 7.25 years, SD=9.42).Nurses were allocated to a control or intervention arm consisting of 20 groups of 5-8 RNs per arm for a total of 130 RNs in each arm. Nurses in each study arm were given clinical scenarios requiring emergency CPR. Nurses in the intervention group wore different color labeled aprons (smocks) indicating their role assignment (medications, ventilation, compression, defibrillation, etc) on the code team during CPR. Findings indicated that the intervention using color-labeled smocks for pre-assigned roles had a significant effect on the time nurses started compressions (t=3.03, p=0.005), ventilations (t=2.86, p=0.004) and defibrillations (t=2.00, p=.05) when compared to the controls using the standard of care. In performing technical skills, nurses in the intervention groups performed compressions and ventilations significantly better than those in the control groups. The control groups made significantly (t=-2.61, p=0.013) more total errors (7.55 SD 1.54) than the intervention group (5.60, SD 1.90). There were no significant differences in team performance measures between the groups. Study findings indicate use of colored labeled smocks during CPR emergencies resulted in: shorter times to start emergency CPR; reduced errors; more technical skills completed successfully; and no differences in team performance.

A precise measurement of the two -photon exchange effect

The two-photon exchange phenomenon is believed to be responsible for the discrepancy observed between the ratio of proton electric and magnetic form factors, measured by the Rosenbluth and polarization transfer methods. This disagreement is about a factor of three at Q 2 of 5.6 GeV2. The precise knowledge of the proton form factors is of critical importance in understanding the structure of this nucleon. The theoretical models that estimate the size of the two-photon exchange (TPE) radiative correction are poorly constrained. This factor was found to be directly measurable by taking the ratio of the electron-proton and positron-proton elastic scattering cross sections, as the TPE effect changes sign with respect to the charge of the incident particle. A test run of a modified beamline has been conducted with the CEBAF Large Acceptance Spectrometer (CLAS) at Thomas Jefferson National Accelerator Facility. This test run demonstrated the feasibility of producing a mixed electron/positron beam of good quality. Extensive simulations performed prior to the run were used to reduce the background rate that limits the production luminosity. A 3.3 GeV primary electron beam was used that resulted in an average secondary lepton beam of 1 GeV. As a result, the elastic scattering data of both lepton types were obtained at scattering angles up to 40 degrees for Q2 up to 1.5 GeV2. The cross section ratio displayed an &epsis; dependence that was Q2 dependent at smaller Q2 limits. The magnitude of the average ratio as a function of &epsis; was consistent with the previous measurements, and the elastic (Blunden) model to within the experimental uncertainties. Ultimately, higher luminosity is needed to extend the data range to lower &epsis; where the TPE effect is predicted to be largest.

Development of test-based wind-driven rain intrusion model for hurricane-induced building interior and contents damage

Major portion of hurricane-induced economic loss originates from damages to building structures. The damages on building structures are typically grouped into three main categories: exterior, interior, and contents damage. Although the latter two types of damages, in most cases, cause more than 50% of the total loss, little has been done to investigate the physical damage process and unveil the interdependence of interior damage parameters. Building interior and contents damages are mainly due to wind-driven rain (WDR) intrusion through building envelope defects, breaches, and other functional openings. The limitation of research works and subsequent knowledge gaps, are in most part due to the complexity of damage phenomena during hurricanes and lack of established measurement methodologies to quantify rainwater intrusion. This dissertation focuses on devising methodologies for large-scale experimental simulation of tropical cyclone WDR and measurements of rainwater intrusion to acquire benchmark test-based data for the development of hurricane-induced building interior and contents damage model. Target WDR parameters derived from tropical cyclone rainfall data were used to simulate the WDR characteristics at the Wall of Wind (WOW) facility. The proposed WDR simulation methodology presents detailed procedures for selection of type and number of nozzles formulated based on tropical cyclone WDR study. The simulated WDR was later used to experimentally investigate the mechanisms of rainwater deposition/intrusion in buildings. Test-based dataset of two rainwater intrusion parameters that quantify the distribution of direct impinging raindrops and surface runoff rainwater over building surface — rain admittance factor (RAF) and surface runoff coefficient (SRC), respectively —were developed using common shapes of low-rise buildings. The dataset was applied to a newly formulated WDR estimation model to predict the volume of rainwater ingress through envelope openings such as wall and roof deck breaches and window sill cracks. The validation of the new model using experimental data indicated reasonable estimation of rainwater ingress through envelope defects and breaches during tropical cyclones. The WDR estimation model and experimental dataset of WDR parameters developed in this dissertation work can be used to enhance the prediction capabilities of existing interior damage models such as the Florida Public Hurricane Loss Model (FPHLM).^

Modified continuous ant colony algorithm for function optimization

Many classical as well as modern optimization techniques exist. One such modern method belonging to the field of swarm intelligence is termed ant colony optimization. This relatively new concept in optimization involves the use of artificial ants and is based on real ant behavior inspired by the way ants search for food. In this thesis, a novel ant colony optimization technique for continuous domains was developed. The goal was to provide improvements in computing time and robustness when compared to other optimization algorithms. Optimization function spaces can have extreme topologies and are therefore difficult to optimize. The proposed method effectively searched the domain and solved difficult single-objective optimization problems. The developed algorithm was run for numerous classic test cases for both single and multi-objective problems. The results demonstrate that the method is robust, stable, and that the number of objective function evaluations is comparable to other optimization algorithms.

A Test of the Biogenicity Criteria Established for Microfossils and Stromatolites on Quaternary Tufa and Speleothem Materials Formed in the “Twilight Zone” at Caerwys, UK

Natural Resources Wales and Steven Griffiths are thanked for access to Caerwys quarry and permission to work on the site. Sebastiaan Edelman and Thomas Logeman assisted with fieldwork and provided some of the field photographs. Bouke Lacet (Sedimentology laboratory, VU University Amsterdam) prepared the thin-sections. Three anonymous reviewers helped to sharpen the manuscript, and Sherry Cady provided valuable editorial advice and assistance. A.T.B. was inspired by Martin Brasier. He dedicates this manuscript to his father’s memory.

A Test of the Biogenicity Criteria Established for Microfossils and Stromatolites on Quaternary Tufa and Speleothem Materials Formed in the “Twilight Zone” at Caerwys, UK

Natural Resources Wales and Steven Griffiths are thanked for access to Caerwys quarry and permission to work on the site. Sebastiaan Edelman and Thomas Logeman assisted with fieldwork and provided some of the field photographs. Bouke Lacet (Sedimentology laboratory, VU University Amsterdam) prepared the thin-sections. Three anonymous reviewers helped to sharpen the manuscript, and Sherry Cady provided valuable editorial advice and assistance. A.T.B. was inspired by Martin Brasier. He dedicates this manuscript to his father’s memory.