Development of a Miniaturized Electro-Fluidic Detector for Medical Diagnostics

In the last decades the interest towards personalized therapies has fostered a big number of studies dedicated to the realization and the optimization of bio-detectors to be used as fast diagnostic tools during medical treatment [1, 2, 3, 4]. Among the proposed devices the best performances, both in terms of multiplexing and cost reduction, are expected by the detectors based on electrical readout. These sensors can be integrated with microfluidic networks in the so called Lab-on-a-Chip systems and o ffer the possibility to develop complete diagnostic kits for the use as a medical practitioner\u2019s bench tool and, ultimately, for rapid and reliable analysis in low-resource areas and in the developing world [5, 6]. In this framework we focused on the development of an electrochemical biosensor based on capacitance readout, for the detection of biomolecules in small sample volumes. We performed electrochemical impedance spectroscopy (EIS) measurements of DNA-hybridization and protein-protein interaction in electrochemical cells with microfabricated gold electrodes. The time stability of the device was tested in two di erent configurations: two microelectrodes in a microfluidic channel; two microelectrodes plus a reference electrode in an electrochemical cell. Our results demonstrate that the three-electrode setup is more stable, more reproducible, and suitable for real-time measurements. A thorough study of the immobilization strategy of the DNA-molecules on the gold electrodes was carried out. In the last part of the work we performed a test study of DNA-hybridization in real time and we showed that the three-electrode configuration can measure the process in-situ. [1] Vladimir Gubala, Leanne F Harris, Antonio J Ricco, Ming X Tan, and David E Williams. Point of care diagnostics: status and future. Analytical chemistry, 84(2):487\u2013515, 2011. [2] V Tsouti, C Boutopoulos, I Zergioti, and S Chatzandroulis. Capacitive microsystems for biological sensing. Biosensors and Bioelectronics, 27(1):1\u201311, 2011. [3] Sandro Carrara. Nano-Bio-Technology and Sensing Chips: New Systems for Detection in Personalized Therapies and Cell Biology. Sensors, 10(1):526\u2013543, January 2010. [4] Shaurya Prakash, M.B. Karacor, and S. Banerjee. Surface modification in microsystems and nanosystems. Surface Science Reports, 64(7):233\u2013254, July 2009. [5] Paul Yager, Gonzalo J Domingo, and John Gerdes. Point-of-care diagnostics for global health. Annual review of biomedical engineering, 10:107\u201344, January 2008. [6] Xiaole Mao and Tony Jun Huang. Microfluidic diagnostics for the developing world. Lab on a chip, 12(8):1412\u20136, April 2012

The Impact of California's inefficiently high electricity prices on electric vehicle adoption in low-income communities

Thesis advisor: Richard SweeneyThe main Investor-Owned Utilities in California charge electricity prices that are way above the social marginal cost of consuming electricity. This results in economic inefficiency which previous studies prove to have negative implications for inequality and to slow down the electrification of the transportation sector. This paper seeks to build on the existing knowledge by investigating how the high electricity prices affect low and high income house-holds’ electric vehicle adoption differently in California, and it aims to quantify the extent of such difference. The results show that EV adoption among low income households would be considerably higher under efficient retail pricing, and that low income households are more negatively affected than their high income counterparts. However, the results relative to high income households specifically are inconclusive, and therefore the extent to which the two income groups are affected differently cannot be determined. Further research should tackle this issue by including additional variables such as income by year and EV quality, as well as more granular gasoline price data.Thesis (BA) — Boston College, 2023.Submitted to: Boston College. College of Arts and Sciences.Discipline: Departmental Honors.Discipline: Economics

Kinetic microscale thermophoresis

We established an extension of Microscale Thermophoresis (MST) to measure binding kinetics together with binding affinity in a single experimental run, by increasing the thermal dissipation of the sample. After the switch-off of an IR laser, that locally heated the sample, the temperature re-equilibrated within 250 ms. The kinetic relaxation fingerprints were extracted from the fluorescence changes back to thermodynamic equilibrium. We measured DNA hybridization on-rates and off-rates in the range between 104-106 M-1s-1 and 10-4-10-1 s‑1, respectively. We observed the expected exponential dependence of the DNA hybridization off-rates on salt concentration, strand length and inverse temperature. The measured on-rates showed a linear dependence on salt and weak if no dependence at all on length and temperature. For biological binding reactions with sufficient enthalpic contributions, Kinetic MST offers a robust and immobilization-free determination of kinetic rates and binding affinity and also in crowded solutions

Beyond the Landau Criterion for Superfluidity

According to the Landau criterion for superfluidity, a Bose-Einstein condensate flowing with a group velocity smaller than the sound velocity is energetically stable to the presence of perturbing potentials. We found that this is strictly correct only for vanishingly small perturbations. The superfluid critical velocity strongly depends on the strength and shape of the defect. We quantitatively study, both numerically and with an approximate analytical model, the dynamical response of a one-dimensional condensate flowing against an istantaneously raised spatially periodic defect. We found that the critical velocity $v_c$ decreases by incresing the strength of the defect $V_0$, up to to a critical value of the defect intensity where the critical velocity vanishes

The Urea Carboxylase and Allophanate Hydrolase Activities of Urea Amidolyase Are Functionally Independent

Urea amidolyase (UAL) is a multifunctional biotin-dependent enzyme that contributes to both bacterial and fungal pathogenicity by catalyzing the ATP-dependent cleavage of urea into ammonia and CO2. UAL is comprised of two enzymatic components: urea carboxylase (UC) and allophanate hydrolase (AH). These enzyme activities are encoded on separate but proximally related genes in prokaryotes while, in most fungi, they are encoded by a single gene that produces a fusion enzyme on a single polypeptide chain. It is unclear whether the UC and AH activities are connected through substrate channeling or other forms of direct communication. Here, we use multiple biochemical approaches to demonstrate that there is no substrate channeling or interdomain/intersubunit communication between UC and AH. Neither stable nor transient interactions can be detected between prokaryotic UC and AH and the catalytic efficiencies of UC and AH are independent of one another. Furthermore, an artificial fusion of UC and AH does not significantly alter the AH enzyme activity or catalytic efficiency. These results support the surprising functional independence of AH from UC in both the prokaryotic and fungal UAL enzymes and serve as an important reminder that the evolution of multifunctional enzymes through gene fusion events does not always correlate with enhanced catalytic function

Optical Lattices: Theory

This chapter presents an overview of the properties of a Bose-Einstein condensate (BEC) trapped in a periodic potential. This system has attracted a wide interest in the last years, and a few excellent reviews of the field have already appeared in the literature (see, for instance, [1-3] and references therein). For this reason, and because of the huge amount of published results, we do not pretend here to be comprehensive, but we will be content to provide a flavor of the richness of this subject, together with some useful references. On the other hand, there are good reasons for our effort. Probably, the most significant is that BEC in periodic potentials is a truly interdisciplinary problem, with obvious connections with electrons in crystal lattices, polarons and photons in optical fibers. Moreover, the BEC experimentalists have reached such a high level of accuracy to create in the lab, so to speak, paradigmatic Hamiltonians, which were first introduced as idealized theoretical models to study, among others, dynamical instabilities or quantum phase transitions.Comment: Chapter 13 in Part VIII: "Optical Lattices" of "Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer Series on Atomic, Optical, and Plasma Physics, 2007) - pages 247-26

The untitled title in the XX century art: revolutionary aspects and implications.

The ubiquitous abundance of the title untitled, in private hands as well as in museum collections, requires a more complex analysis. Titles deeply shape the reception of works of art, being considered a fundamental mediation point between the artist and the spectator. They have a major impact on the visual experience: the decision of not giving a title has significant ramifications, which must be further investigated. The goal of the present research is to comprehend what consequences the untitled title conveyed, and to define, through specific case studies and resulting interpreting categories, how and why it has been used, until becoming an unquestioned "term/definition" today. The untitled title, a topic that has received little attention, demands a thorough examination because it is linked to significant cultural transformations in society and an increasing concentration on spectatorship. Despite being extraordinary common, the lack of a title, or the untitled title, has not so far been documented and addressed: museum inventories even do not distinguish between the untitled title, as the actual lack of the title, and the Untitled title, as the result of an authorial choice. The core questions of the research focus on how and why so many works of art are titled untitled and on all the implications the use of this term has. The project has been developed thanks to primary sources such as titles on works of art and declarations of artists, which refer explicitly or not directly to the use of the Untitled; secondary sources such as reflections of art historians, curators, critics, scholars and gallery owners. A direct dialogue with scholars, who have conducted research on artists that have purposefully chosen the Untitled title also belongs to the latter category. The research has led to a clear definition of various classifications of use of the untitled as a title, allowing for key distinctions. Secondly, it has allowed to trace the art historical roots of the Untitled title, in particular by looking at declarations and writings of artists on the specific topic of titling. Furthermore, this research has enabled for the identification and better contextualization of the term Untitled, analysing in particular exhibitions and catalogs. It has been possible to demonstrate how the reasons behind the use of the title Untitled as a title can significantly differ, as for example in the case of artists affiliated with Abstract Expressionism, Minimalism and Arte povera. The project has also illustrated how the untitled title is a complicated issue in today's exhibition of works, particularly in relation to label definition. The Untitled title's revolutionary potency has waned in recent decades, and it has now become a popular term