Optical pH sensor based on carbon nanomaterials and metal redox chemistry

Most pH sensors operate under potentiometric conditions using a simple two-electrode scheme. More generally, a conventional meter measures the electrical potential of the solution using a glass electrode (pH) against another electrode (reference), whose electrochemical potential is known and insensitive to pH. Modern pH sensors are robust, accurate and low cost, but they are limited by the macroscopic electrode size. They also require electrical contacts and they are often affected by errors associated with the contamination of the small electrode liquid junctions. This thesis targets pH measurements at nanoscale interfaces and explores the miniaturization of the pH sensor for local and remote (optical) measurements. By taking advantage of a non-destructive optical technique based on Raman spectroscopy and of the redox chemistry of metals, this work aims to develop a remote pH sensor based on carbon nanomaterials, namely the single walled carbon nanotube (SWCNT) and the graphene in the form of a single layer. By making use of the highly sensitive Raman response of metallic SWCNTs, we devised a pH responsive optical probe consisting of a SWCNT in direct contact with a platinum redox couple. When placed in a buffer solution, the Pt-SWCNT probe shows strong Raman shifts of the nanotube G-band as a function of pH, which is ascribed to charge transfer doping of the SWCNT reference electrode. Referenced potential measurements are demonstrated using a nanoscale version of the Pt-SWCNT electrode, along with the accurate monitoring of pH in solutions of different ionic strengths. Controlled experiments at a constant ionic strength show pH measurement across the full range between 1 to 12 with a best accuracy of ±500 mpH unit. This study also explores the influence of different transition metals (Pt, Ru and Pd), of semiconducting vs. metallic SWCNTs, and supporting substrates on pH sensing. A model based on electron transfer between the redox metal system and the SWCNT is proposed and tested using electrical conductance measurements. Due to the outstanding properties of graphene, such as a semi metallic behavior and its relatively inert surface, graphene was selected as a second nanomaterial to further investigate the Raman-pH sensing. From the study with SWCNTs, which determines optimal response with the Pt/PtO redox couple, we explore the Raman response of graphene coated with a thin layer of Pt in different buffer solutions of pH between 1 and 12. The spectra show clear evidence of charge transfer and doping of graphene in contact with the platinum redox couple. Significant Raman shift with pH is noted in the region of the G-band and also in D-band, which are consistent with the behavior found with the metallic Pt-SWCNT system. An analysis of the Raman shift provides a better understanding of the doping behavior observed for different pH. The analysis provides an estimate of the potential and confirms the Nernstian behavior of the pH sensor. Redox pH sensing at the nanoscale using carbon nanomaterials solves the main limitations highlighted above, namely coverage of the full pH range and a clear miniaturization of the sensor down to the nanometer scale. Although the accuracy requires further improvement, this work demonstrates for the first time an optical pH sensing scheme that is analogous to a conventional pH sensor equipped with a built-in internal reference.La plupart des capteurs de pH fonctionnent dans des conditions potentiométriques en utilisant un schéma simple à deux électrodes. Plus généralement, un pH mètre classique mesure le potentiel électrique de la solution à l'aide d'une électrode en verre (pH) contre une autre électrode (référence), dont le potentiel électrochimique est connu et insensible au pH. Les capteurs de pH modernes sont robustes, précis et peu coûteux, mais ils sont limités par les tailles macroscopiques des électrodes. Ils nécessitent également des contacts électriques et sont souvent affectés par des erreurs liées à la contamination des petites jonctions liquides des électrodes. Cette thèse concerne l'amélioration des mesures de pH aux interfaces nanométriques et explore la miniaturisation du capteur de pH pour des mesures (optiques) locales et à distance. En tirant parti d'une technique optique non destructive basée sur la spectroscopie Raman et de la chimie redox des métaux, ce travail vise à développer un capteur de pH à distance à base de nanomatériaux de carbone, à savoir le nanotube de carbone à simple paroi (SWCNT) et le graphène monofeuillet. En utilisant la réponse Raman très sensible des SWCNT métalliques, nous avons conçu une sonde optique sensible au pH constituée d'un SWCNT en contact direct avec un couple redox platine. Lorsqu'elle est placée dans une solution tampon, la sonde Pt-SWCNT montre un fort décalage Raman de la bande G du nanotube en fonction du pH, qui est attribué au dopage par transfert de charge de l'électrode de référence SWCNT. La mesure du potentiel référencé est démontrée à l'aide d'une version nanométrique de l'électrode Pt-SWCNT, ainsi que par la surveillance précise du pH dans des solutions de différentes forces ioniques. Des expériences contrôlées à force ionique constante montrent des mesures de pH sur toute la gamme entre 1 et 12 avec une précision allant jusqu'à ± 500 mpH. Cette étude explore également l'influence de différents métaux de transition (Pt, Ru et Pd), du caractère électronique des SWCNTs et des substrats de soutien sur les détection de pH. Un modèle basé sur le transfert d'électrons entre le système métallique redox et le SWCNT est proposé et testé à l'aide de mesures de conductance électrique. En raison des propriétés exceptionnelles du graphène, telles qu'un comportement semi-métallique et une surface relativement inerte, le graphène a été sélectionné comme deuxième nanomatériau pour approfondir la détection Raman-pH. À partir de l'étude avec les SWCNT, qui détermine qu'une réponse optimale est obtenue avec le couple redox Pt / PtO, nous explorons la réponse Raman du graphène recouvert d'une fine couche de Pt dans différentes solutions tampons avec pH iv entre 1 et 12. Les spectres montrent des preuves claires de transfert de charge et dopage du graphène en contact avec le couple redox platine. Un décalage Raman significatif avec le pH est noté dans la région de la bande G et également dans la bande D, ce qui est cohérent avec le comportement trouvé avec le système Pt-SWCNT métallique. Une analyse du décalage Raman permet de mieux comprendre le comportement de dopage observé à différents pH. L'analyse fournit une estimation du potentiel et confirme le comportement Nerstien du capteur de pH. La détection de pH redox à l'échelle nanométrique avec des nanomatériaux de carbone permet de résoudre les principales limitations mises en évidence ci-dessus, à savoir la couverture de toute la gamme de pH et une miniaturisation claire du capteur jusqu'à l'échelle nanométrique. Bien que la précision nécessite une amélioration supplémentaire, ce travail démontre pour la première fois un schéma de détection optique du pH qui est analogue à un capteur de pH conventionnel équipé d'une référence interne intégrée

A study of residual stresses and their effect on thermo mechanical fatigue in complex geometries

It is known that residual stresses within engine components, such as turbine housings, can combine with service generated stresses and cause unexpected failures during operation, therefore it is important that all the stresses (residual and induced, compressive and tensile) are fully characterised and understood. The use of neutrons as a tool to measure the strains within a material is well established; however, applying this technique to complex engineering components can prove challenging. This research investigates the measurement of residual stresses in complex geometries found within the turbine housing component of a turbocharger using neutron diffraction. The effect of various production methods on residual stress distributions is also explored. Successful strain measurements were taken using the Engin-X instrument at the ISIS spallation source from three turbine housings selected from various stages in the manufacturing process, allowing a study of the effect of heat treatment and machining on stress magnitudes and direction. The turbine housing consists of various sections greater than the maximum 60mm path length of the neutrons, therefore path lengths must be carefully chosen to achieve acceptable neutron count rates. Engin-X benefits from an automated experimental setup to make the selection of this limited path length easier on complex shapes. The turbine housings were mounted on to a positioning table allowing translation in X, Y, Z directions and also rotation in , . Each of the housings were scanned using laser scanners and this in conjunction with the virtual path length measurement software SScanSS allowed automated measurements of acceptable path lengths to be made. On this occasion measurements in one principal direction were measured and the correct measurement methodology established. Continuation of this work was then carried out on SALSA at the ILL reactor source. Measurements were made on turbine housings, one as cast and one heat treated. The internal divider wall of each turbine housing was examined as this is an area where crack initiation can occur. The results showed that, heat treatment can reduce compressive residual stresses. However, compressive stresses are thought to slow the onset of crack initiation and could be beneficial in the material, this will be investigated further in future work. It is hoped that this information will be used to improve production methods and result in improved simulation methodologies to allow accurate predictions of thermal fatigue and fracture locations to be established. The authors wish to thank Dr Jon James (Open University) for his help in setting up the experiment and for the use of the SScanSS software

Effectiveness of Self-Talk Technique and Positive Empathy on Deficient Attitudes, Hopelessness, and Suicidal Thoughts in Women with Breast Cancer

Background: Problems stemming from individuals' reactions to the diagnosis and treatment of breast cancer have various effects on the different dimensions of individuals and families' lives such as deficient attitudes, hopelessness, and suicidal thoughts. The study aim was determining the effectiveness of self-talk technique and positive empathy in reducing symptoms and modifying deficient attitudes, hopelessness, and suicidal thoughts in women with breast cancer in Tehran.Methods: The present study was semi-experimental with a pre-test post-test design along with a control group in Tehran from 2014 to 2015. The statistical population consisted of 20 women with breast cancer who were randomly divided into two groups: experiment group (10 individuals) and control group (10 individuals). The experiment group received 12 sessions (each session=90 minutes) with educational structures of self-talk and positive empathy techniques. Data collection tools included Wizeman and Beck's deficient Attitudes Scales, Beck's Hopelessness, and Beck's Suicidal Thoughts Measurement. Data were obtained using SPSS19 software in two sections: descriptive and inferential (variance analysis with repeated measurement and Post Hoc test LSD).Results: The interactive effect of test time and group of each dependent variable was significant. The mean difference between pre-test and post-test in measuring all three dependent variables was significant. On the other hand, the mean difference between post-test and control test was not significant in any of the dependent variables. However, the mean difference between pre-test and control test was significant in all three variables.Conclusion: Teaching self-talk and positive empathy techniques had positive effects on reducing deficient attitudes, hopelessness, and suicidal thoughts. In addition, results proved the sustainability of intervention effects on the size of dependent variables

Does a walk-through video help the parser down the garden-path? A visually enhanced self-paced reading study in Dutch

The human language processing mechanism assigns a structure to the incoming materials as they unfold. There is evidence that the parser prefers some attachment types over others; however, theories of sentence processing are still in dispute over the stage at which each source of information contributes to the parsing system. The present study aims to identify the nature of initial parsing decisions during sentence processing through manipulating attachment type and verbs’ argument structure. To this end, we designed a self-paced reading task using globally ambiguous constructions in Dutch. The structures included double locative prepositional phrases (PPs) where the first PP could attach both to the verb (high attachment) and the noun preceding it (low attachment). To disambiguate the structures, we presented a visual context in the form of short animation clips prior to each reading task. Furthermore, we manipulated the argument structure of the sentences using 2- and 3-argument verbs. The results showed that parsing decisions were influenced by contextual cues depending on the argument structure of the verb. That is, the visual context overcame the preference for high attachment only in the case of 2-argument verbs, while this preference persisted in structures including 3-argument verbs as represented by longer reading times for the low attachment interpretations. These findings can be taken as evidence that our language processing system actively integrates information from linguistic and non-linguistic sources from the initial stages of analysis to build up meaning. We discuss our findings in light of serial and parallel models of sentence processing

Readiness of Iran Universities of Medical Sciences for Conducting Total Quality Management (TQM) according to Educational Managers’ Point of View

Background & Objective : Total Quality Management (TQM) is a new approach to management which must be implemented gradually during some stages. The first step is to create readiness for change conducting quality management is not possible before acquiring enough readiness. This study was conducted to evaluate the readiness of Iran Universities of Medical Sciences for conducting Total Quality Management (TQM) according to educational managers’ point of view. Methods : In this descriptive study, the participants were all educational managers of 34 Universities of Medical Sciences including 314 vice chancellors for educational affairs, heads of Medical Education Development Centers, deans and pro-vice chancellors for education. Data was collected using a researcher-made questionnaire containing 27 questions about 11 signs of readiness. Results : The results of this study revealed that, considering readiness for conducting Total Quality Management, 9% of the universities were moderate (50 to 59% of the score), 79% were approximately good (60 to 69% of the score) and 12% were good (70 to 73% of the score ). The mean score for universities’ readiness was 64.5%. Readiness for applying TQM philosophy in behavior had the highest score while readiness for allocating resources had the lowest score (78% and 47.86% respectively). Conclusion : The results imply that the universities have had an improving trend and an appropriate atmosphere is ready for conducting Total Quality Management. Keywords: Total Quality Management, Management approach, Quality management philosophy, University of Medical Sciences

Bittersweet Longing of Nostalgia

“Bittersweet Longing of Nostalgia”, aims to demonstrate the relationship between art, nostalgia and politics. In the early 20th century, the human world underwent many changes. The swift pace of change has touched every aspect of human life, including science, philosophy, politics, and society, and this transformation has also been reflected in the arts. During this period, committed artists were both supported and opposed, as many debated the role of politics in art. From 2022 through 2023, Iran is experiencing a revolution that will profoundly impact its political, social, and cultural landscape. The aim of this treatise is to examine whether artists can participate in ideological changes and whether the politicization of works affects the artist's intentions. The research utilized a combination of library-based research, autobiographical and auto ethnographic techniques, and studio-based exploration to investigate the intersection of politics, art, and protest. The research concludes that artists who genuinely believe in their ideologies (not due to government coercion) should enter the political arena and use their art to support the social movement. I argue that by expressing their preferred ideology, artists can create long-lasting and influential works. In order to develop a connection to the Women Life Freedom Protests in Iran, I am creating artworks that are related to my memories and/or the common nostalgia of collective memory. I borrow from the style of Persian miniature, a form of art that has a long history in Iranian culture and contains a great deal of metaphor and hidden meaning. I specifically use the Persian miniature as a symbol for Iranian to evoke their nostalgic memories in the new environment and create a connection between the present and the past. Keywords: Art protest, Nostalgia, Miniature, Politics, Anti-art washin

Animal models and their role in imaging-assisted co-clinical trials

The availability of high-fidelity animal models for oncology research has grown enormously in recent years, enabling preclinical studies relevant to prevention, diagnosis, and treatment of cancer to be undertaken. This has led to increased opportunities to conduct co-clinical trials, which are studies on patients that are carried out parallel to or sequentially with animal models of cancer that mirror the biology of the patients\u27 tumors. Patient-derived xenografts (PDX) and genetically engineered mouse models (GEMM) are considered to be the models that best represent human disease and have high translational value. Notably, one element of co-clinical trials that still needs significant optimization is quantitative imaging. The National Cancer Institute has organized a Co-Clinical Imaging Resource Program (CIRP) network to establish best practices for co-clinical imaging and to optimize translational quantitative imaging methodologies. This overview describes the ten co-clinical trials of investigators from eleven institutions who are currently supported by the CIRP initiative and are members of the Animal Models and Co-clinical Trials (AMCT) Working Group. Each team describes their corresponding clinical trial, type of cancer targeted, rationale for choice of animal models, therapy, and imaging modalities. The strengths and weaknesses of the co-clinical trial design and the challenges encountered are considered. The rich research resources generated by the members of the AMCT Working Group will benefit the broad research community and improve the quality and translational impact of imaging in co-clinical trials

Co-Clinical Imaging Resource Program (CIRP): Bridging the translational divide to advance precision medicine

The National Institutes of Health\u27s (National Cancer Institute) precision medicine initiative emphasizes the biological and molecular bases for cancer prevention and treatment. Importantly, it addresses the need for consistency in preclinical and clinical research. To overcome the translational gap in cancer treatment and prevention, the cancer research community has been transitioning toward using animal models that more fatefully recapitulate human tumor biology. There is a growing need to develop best practices in translational research, including imaging research, to better inform therapeutic choices and decision-making. Therefore, the National Cancer Institute has recently launched the Co-Clinical Imaging Research Resource Program (CIRP). Its overarching mission is to advance the practice of precision medicine by establishing consensus-based best practices for co-clinical imaging research by developing optimized state-of-the-art translational quantitative imaging methodologies to enable disease detection, risk stratification, and assessment/prediction of response to therapy. In this communication, we discuss our involvement in the CIRP, detailing key considerations including animal model selection, co-clinical study design, need for standardization of co-clinical instruments, and harmonization of preclinical and clinical quantitative imaging pipelines. An underlying emphasis in the program is to develop best practices toward reproducible, repeatable, and precise quantitative imaging biomarkers for use in translational cancer imaging and therapy. We will conclude with our thoughts on informatics needs to enable collaborative and open science research to advance precision medicine