Electrochemical surface modification of Single walled carbon nanotubes and graphene-based electrodes for (bio)sensing applications

Sensors are devices that have shown widespread use, from the detection of gas molecules to the tracking of chemical signals in biological cells. Single walled carbon nanotube (SWCNT) and graphene based electrodes have demonstrated to be an excellent material for the development of electrochemical biosensors as they display remarkable electronic properties and the ability to act as individual nanoelectrodes, display an excellent low-dimensional charge carrier transport, and promote surface electrocatalysis. The present work aims at the preparation and investigation of electrochemically modified SWCNT and graphene-based electrodes for applications in the field of biosensors. We initially studied SWCNT films and focused on their topography and surface composition, electrical and optical properties. Parallel to SWCNTs, graphene films were investigated. Higher resistance values were obtained in comparison with nanotubes films. The electrochemical surface modification of both electrodes was investigated following two routes (i) the electrografting of aryl diazonium salts, and (ii) the electrophylic addition of 1, 3-benzodithiolylium tetrafluoroborate (BDYT). Both the qualitative and quantitative characteristics of the modified electrode surfaces were studied such as the degree of functionalization and their surface composition. The combination of Raman, X-ray photoelectron spectroscopy, atomic force microscopy, electrochemistry and other techniques, has demonstrated that selected precursors could be covalently anchored to the nanotubes and graphene-based electrode surfaces through novel carbon-carbon formation.

Thermoelectric performance of p-type TiCoSb half-Heusler compounds - Intrinsic phase separation and charge carrier concentration optimization as key to high efficiency

The world's rising demand of energy turns the development of sustainable and more efficient technologies for energy production and storage into an inevitable task. Thermoelectric generators, composed of pairs of n-type and p-type semiconducting materials, di¬rectly transform waste heat into useful electricity. The efficiency of a thermoelectric mate¬rial depends on its electronic and lattice properties, summarized in its figure of merit ZT. Desirable are high electrical conductivity and Seebeck coefficients, and low thermal con¬ductivity. Half-Heusler materials are very promising candidates for thermoelectric applications in the medium¬ temperature range such as in industrial and automotive waste heat recovery. The advantage of Heusler compounds are excellent electronic properties and high thermal and mechanical stability, as well as their low toxicity and elemental abundance. Thus, the main obstacle to further enhance their thermoelectric performance is their relatively high thermal conductivity.rn rnIn this work, the thermoelectric properties of the p-type material (Ti/Zr/Hf)CoSb1-xSnx were optimized in a multistep process. The concept of an intrinsic phase separation has recently become a focus of research in the compatible n-type (Ti/Zr/Hf)NiSn system to achieve low thermal conductivities and boost the TE performance. This concept is successfully transferred to the TiCoSb system. The phase separation approach can form a significant alternative to the previous nanostructuring approach via ball milling and hot pressing, saving pro¬cessing time, energy consumption and increasing the thermoelectric efficiency. A fundamental concept to tune the performance of thermoelectric materials is charge carrier concentration optimization. The optimum carrier concentration is reached with a substitution level for Sn of x = 0.15, enhancing the ZT about 40% compared to previous state-of-the-art samples with x = 0.2. The TE performance can be enhanced further by a fine-tuning of the Ti-to-Hf ratio. A correlation of the microstructure and the thermoelectric properties is observed and a record figure of merit ZT = 1.2 at 710°C was reached with the composition Ti0.25Hf0.75CoSb0.85Sn0.15.rnTowards application, the long term stability of the material under actual conditions of operation are an important issue. The impact of such a heat treatment on the structural and thermoelectric properties is investigated. Particularly, the best and most reliable performance is achieved in Ti0.5Hf0.5CoSb0.85Sn0.15, which reached a maximum ZT of 1.1 at 700°C. The intrinsic phase separation and resulting microstructure is stable even after 500 heating and cooling cycles.

Analisi dei discorsi di ringraziamento di attori e attrici alle cerimonie dei premi oscar

Il presente elaborato ha come obiettivo l’analisi dei discorsi di ringraziamento pronunciati nelle cerimonie dei premi Oscar dal 1990 al 2015 da attori e attrici, protagonisti e non protagonisti, premiati con la statuetta dorata per le loro performance recitative. L’elaborato si articola in tre capitoli: nel primo, si delinea la storia dei premi Oscar, considerati la cerimonia di premiazione cinematografica per antonomasia, con particolare attenzione ai metodi di selezione di premiati e vincitori da parte dell’Academy of Motion Pictures Arts and Sciences. Ci si concentra anche sul significato, letterale e simbolico, dei discorsi di ringraziamento, e sulla rilevanza che essi hanno all’interno della cerimonia. Nel secondo capitolo, si analizzano i discorsi di ringraziamento dei vincitori da un punto di vista linguistico, con particolare attenzione a prosodia, prossemica, retorica e deissi. Nel terzo e ultimo capitolo, infine, l’analisi assume toni più prettamente culturali, focalizzando l’attenzione sugli aspetti pragmatici e contenutistici dei discorsi, nonché nel tentativo di confrontare gli atteggiamenti delle due categorie nazionali più premiate agli Oscar: gli americani e i britannici.

Three-dimensional portable document format: a simple way to present 3-dimensional data in an electronic publication

Three-dimensional (3D) models of teeth and soft and hard tissues are tessellated surfaces used for diagnosis, treatment planning, appliance fabrication, outcome evaluation, and research. In scientific publications or communications with colleagues, these 3D data are often reduced to 2-dimensional pictures or need special software for visualization. The portable document format (PDF) offers a simple way to interactively display 3D surface data without additional software other than a recent version of Adobe Reader (Adobe, San Jose, Calif). The purposes of this article were to give an example of how 3D data and their analyses can be interactively displayed in 3 dimensions in electronic publications, and to show how they can be exported from any software for diagnostic reports and communications among colleagues.

The Lady Footballers and the British Press, 1895

Nettie Honeyball and Florence Dixie founded the British Ladies Football Club (BLFC) in 1894 with the aim to provide football-playing opportunities for girls and young women, but also as a means of making money. Theirs, in effect, was an attempt to create a professional football league for women. Public interest in 'the lady footballers' was enormous, at least in its early stages, and generated considerable attention from the press. Overall, press coverage of the BLFC was negative (football is a man's sport; football is a working-class sport; women are physically incapable of playing the game; women shouldn't appear publicly in bifurcated garments, etc.), with only a few notable exceptions. Did the stance adopted depend on the political leaning of the newspaper? Or were the reporters simply reflecting the social and economic realities of their time, struggling to 'explain' a marginal group - women athletes, or more specifically, middle-class women football players - engaging in a working-class male game? This article examines the press coverage of the BLFC. The double standard evident in the newspaper coverage was, on the surface, as one might expect: if a woman played well, she was a freak, possibly a man in disguise; if she didn't play well, it proved that women shouldn't play football. But on closer examination, the double standard was actually rather nuanced: if she played well and looked the part of a woman, she could be subject to praise; yet if she played well and didn't conform to the standard of feminine beauty, she faced ridicule, and her gender called into question.

Educating...for what?: Meaning and Purpose

Higgins School of the Humanities/Difficult Dialogues: Video Recording from 10/5/2011 event featuring Diana Chapman Walsh and Arthur Zajonc titled "Meaning and Purpose" Event Description: As Kronman tells us, questions of meaning and purpose are often suspect in colleges and universities. If an understanding that to be educated relies on the integration of all of our higher faculties (mind, heart and spirit ) once existed, it was eclipsed long ago by a focus on the rational mind as the locus of reliable behavior. This reduced scope of teaching and learning within the academy has deprived both faculty and students of more substantive and meaningful experiences. How might we re-orient the academy to these deeper purposes—to the heart of higher education? Our guests for a conversation on questions of meaning and purpose are Diana Chapman Walsh, former President of Wellesley College, and Arthur Zajonc, professor of physics at Amherst College. In their work and their writing, they both inspire and ignite conversations around the issue of integrative education.

Educating...for what?: Livelihood and Vocation

Higgins School of the Humanities/Difficult Dialogues: Video Recording from 10/18/2011 event featuring Lynn Pasquerella and David Angel titled "Livlihood and Vocation" Event Description: Some of the most vocal challenges to higher education imply that a liberal education does not have direct vocational application. What good is it? the critics ask. Bill Gates and Mark Zuckerberg didn’t finish college. What is the responsibility of a college or university in ensuring that students have membership in an economy? And what actually best prepares them to do so? How do we define economy? Is the best preparation for a career the same or different than preparation for a discerning and meaningful life? In what ways do the humanities contribute to all these kinds of development? How can we better assist our students in joining their work with their ideals? Our guests for a conversation on livelihood are Lynn Pasquerella, President of Mount Holyoke College, and David Angel, President of Clark University.

Educating...for what?: Creativity and Resilience

Higgins School of the Humanities/Difficult Dialogues: Video Recording from 12/1/2011 event featuring Katja Esson, Li- Young Lee and Alison Granucci titled "Creativity and Resilience" Event Description: To be creative is one of life’s most engaging and satisfying experiences. Can we insure that students trust those capacities and processes in themselves, and develop reliable paths toward them? Can we encourage the cultivation of the imagination in our students, as well as the resilience to weather discouragement, whether in their creative search or other aspects of life? Our guests for a conversation on creativity and resilience are filmmaker Katja Esson, poet Li-Young Lee, and co-producer Alison Granucci. They are collaborators on the new film Poetry of Resilience.