Fabrication of novel sensors from nanomaterials

This thesis describes the fabrication and characterisation of novel sensors from nanomaterials. These are materials that have at least one length scale in the nanometre region, and in many cases they exhibit fascinating electrical, mechanical or optical properties due to their small size. While their small size makes them candidates for miniaturising macro-scale technologies, many researchers are concerned with exploiting their unique properties in larger scale applications. These might include strong, lightweight building materials based on their mechanical properties, or visual displays based on their electrical and/or optical properties. To achieve transfer of the properties from the nano-scale to the macro-scale however is not straight forward, and there are a number of obstacles that must be overcome. One obstacle is that of processing the nanomaterials, ensuring that their properties do not become lost when they are incorporated into bulk materials or composites due to aggregation or poor interactions with their host matrix. This obstacle will also be addressed in the thesis, as we fabricate and characterise composites incorporating nanomaterials, and develop methods to process these materials into novel sensors.The synthesis and characterisation of a number of different composites has been achieved, incorporating either carbon nanotubes or silver nanowires as the nanomaterials of interest. These have been fabricated using either mixing or in situ polymerisation routes, with surfactants, polysaccharides or conducting polymers as the dispersant. The composites are all soluble in either water or organic solvents to give stable dispersions, and show interesting properties including optical activity, high loading fractions of the nanomaterials and electrochromic behaviour.The methods that we have developed for processing the dispersions are drop deposition, inkjet printing and dielectrophoretic assembly. Drop deposition has been performed as it forms the basis of numerous solution-based processing techniques, and we have investigated specifically the effects of substrate hydrophobicity and the effect of aggregates in the dispersion on the resulting composite films that are formed. We have reported for the first time the inkjet printing of single wall carbon nanotubes, and have printed composite films that show good transparency and high conductivity. A novel method for arresting the structures formed through dielectrophoretic assembly within a gel solution has also been developed. This has led to the fabrication of electrically anisotropic gels, and free-standing 'strings' of yeast cells. Novel sensors have been fabricated through two of our processing methods.Thin films containing carbon nanotubes have been inkjet printed, and show sensitivity to water vapour (with gellan gum as the composite material) and alcohol vapour (with a water soluble conducting polymer as the composite material). A sensor based on biotin-functionalised silver nanowires assembled into a microwire and encapsulated within agarose gel has also been fabricated. This sensor showed sensitivity to streptavidin when the response was measured parallel to the formed microwire, but gave a much lower signal when the response was measured perpendicular to the microwire. This provides a proof of concept that a whole range of biosensors based on assembled silver nanowires into an anisotropic gel can be produced by employing an antigen-antibody strategy, similar to the one shown for biotin-streptavidin

A Note on Dialectics in Mathematics

A complete dialectical process is defined; it is shown that such a process is a function, and that every real function is a complete dialectical process. Some general implications of this result are discussed

XXVII.— Notes on larval Trematodes

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Acute lobar pneumonia: with special reference to its treatment

Acute Lobar Pneumonia is one of the most important diseases with which we have to deal, on account of the appalling mortality with which it is attended. In his "Clinical Studies”, Bramwell says "There is perhaps no disease which cuts off so many valuable lives as Acute Croupous Pneumonia, killing as it does so many people at the height of their full vigour, activity, and usefulness”,In Great Britain alone, about 1,000 lives per week are terminated by this malady.Although most fatal at the extremes of life, no age escapes its ravages, and many of the apparently most robust fall victims to it.The percentage mortality varies considerably in different epidemics, and under different physicians, but it is usually from 20 - 30$. Out of the huge total of 465,000 cases collected, by E. F. Wells from all sources, 94,826 died, giving a mortality of 20.4$

Fabrication and Electric Field Dependent Transport Measurements of Mesoscopic Graphite Devices

We have developed a unique micromechanical method to extract extremely thin graphite samples. Graphite crystallites with thicknesses ranging from 10 - 100 nm and lateral size $\sim$ 2 $\mu$m are extracted from bulk. Mesoscopic graphite devices are fabricated from these samples for electric field dependent conductance measurements. Strong conductance modulation as a function of gate voltage is observed in the thinner crystallite devices. The temperature dependent resistivity measurements show more boundary scattering contribution in the thinner graphite samples.Comment: 3 pages, 3 figures included, submitted to Appl. Phys. Let

intraoperative Radiotherapy for Breast Cancer

Intraoperative radiotherapy (IORT) for early stage breast cancer is a technique for partial breast irradiation. There are several technologies in clinical use to perform breast IORT. Regardless of technique, IORT generally refers to the delivery of a single dose of radiation to the periphery of the tumor bed in the immediate intraoperative time frame, although some protocols have performed IORT as a second procedure. There are two large prospective randomized trials establishing the safety and efficacy of breast IORT in early stage breast cancer patients with sufficient follow-up time on thousands of women. The advantages of IORT for partial breast irradiation include: direct visualization of the target tissue ensuring treatment of the high-risk tissue and eliminating the risk of marginal miss; the use of a single dose coordinated with the necessary surgical excision thereby reduc- ing omission of radiation and the selection of mastectomy for women without access to a radiotherapy facility or unable to undergo several weeks of daily radiation; favorable toxicity profiles; patient convenience and cost savings; radiobiological and tumor micro- environment conditions which lead to enhanced tumor control. The main disadvantage of IORT is the lack of final pathologic information on the tumor size, histology, margins, and nodal status. When unexpected findings on final pathology such as positive margins or positive sentinel nodes predict a higher risk of local or regional recurrence, additional whole breast radiation may be indicated, thereby reducing some of the convenience and low-toxicity advantages of sole IORT. However, IORT as a tumor bed boost has also been studied and appears to be safe with acceptable toxicity. IORT has potential efficacy advantages related to overall survival related to reduced cardiopulmonary radia- tion doses. It may also be very useful in specific situations, such as prior to oncoplastic reconstruction to improve accuracy of adjuvant radiation delivery, or when used as a boost in higher risk patients to improve tumor control. Ongoing international clinical trials are studying these uses and follow-up data are accumulating on completed studies

Using Quality Improvement To Implement Substance Use Disorders Services In Primary Health Care In Kenya: Impact And Experiences Of A Blended Course Among Health Workers Using The NextGenU Online Model

Background: Worldwide, mental and substance use disorders (SUD) account for over 183.9 million disability adjusted life years. While interventions do exist they are not readily implemented, especially in low- and middle-income countries, due to a lack of available human resources, monetary resources, stigma, and difficulties in changing practice patterns. Quality Improvement (QI) has been reported in literature to successfully improve health services and systems through small-scale, iterative change cycles. Objectives: This study assessed the impact of the NextGenU.org online blended course in terms of integrating, improving and sustaining mental health services using quality improvement methods in primary health care in Kenya. It also analyzed the experience of participants who completed the NextGenU.org online blended course. Method: A mixed-methods study was conducted, incorporating both qualitative focus groups (FGD) and key informant interviews (KII), and quantitative statistical measures. Data came from the Computer-Based and Alcohol Training Assessment in Kenya (eDATA K), which was implemented in collaboration with the University of British Columbia (UBC) and African Mental Health Foundation (AMHF). FGDs and KIIs were analyzed using NVivo through a constant-comparison method, to identify themes emerging from the data. A second coder analyzed the data to ensure reliability and validity. Quantitative analysis was conducted to analyze the course completion rates. Additionally, the researcher incorporated their own notes from observations made during fieldwork over the course of a 12-week practicum with AMHF to triangulate the results. Results: Overall, 27 screeners and clinicians completed the NextGenU.org online blended course. There were two FGDS and two KIIs conducted in Makueni county during July - September 2015. In terms of the staff’s experience in completing the online course many participants noted strong facilitators such as: the certificates, desire for knowledge, personal motivations, relevant material, and case studies. The limited amount of space, computers, and restrictions on Internet access acted as barriers. Participants perceived their knowledge of QI methods, leadership, and time management to have increased from completing the course. Perceived self-efficacy also increased, as staff believed their ability to be a leader, manage time and deal with errors and mistakes within the workplace improved. There was also a positive shift in stigma associated with SUD. Most importantly, the integration and improvement in mental health services was maintained even though staff discussed common challenges, such as heavy workload and limited time. Some participants reported that some people in management roles should have been more supportive, as their limited involvement acts as a barrier to greater integration of services, while other where thankful of the management support. Conclusion: This is one of the first studies of using QI methods to integrate, improve and sustain mental health services in the primary health care system in Kenya. Based upon the experiences described in the FGDs and KIIs, the blended online course was perceived to be acceptable, feasible and successful. The results indicate that quality improvement continues to be integrated in Makueni overall improving mental health services