942 research outputs found
NANOSTRUCTURED COMPOSITE FILMS FOR BRAIN-MACHINE INTERFACE APPLICATIONS
No full textBiohybrid electronic technologies, fostering information flow and processing between natural and artificial components [1] are essential for developing energy-efficient, compact interfaces that integrate bioelectrical activity for personalized medicine. In this frame, advances in thin-film sensors and non-invasive signal processing enable wearable systems to monitor brain and peripheral neural activity [2] in view of the development of efficient Brain-Machine Interfaces (BMIs) [3]. While the quality and quantity of signal recordings have improved [4], managing and processing large data volumes in real-time necessitates significant hardware and software advancements. Crucial concern is also the mechanical matching and biocompatibility of the materials used in Micro Electrode Arrays (MEAs) and other recording devices, as well as the proper device geometries and scaling for in vivo brain activity.
Nanostructured Cluster Assembled Films (NCAFs) are of particular interest for the development of artificial systems showing neuromorphic behaviors and as the basis for BMIs. Au NCAFs show nonlinear electrical properties and resistive switching behavior [5], [6]. ZrOx NCAFs are biocompatible, and they have been used as substrates for the growth of neural cells. Thanks to their controlled nanoscale roughness, they can be used to induce phenotypic modifications via mechanotransductive signaling [7], [8], [9], [10].
My work was focused on combining these two aspects by fabricating and characterizing a nanocomposite Au-ZrOx system showing resisting switching behavior and capable of enabling a suitable information coding/decoding protocol in view of the development of BMIs.
I developed planar layered Au/ZrOx two terminal systems, on glass substrates [11]. An electrical characterization highlighted hysteretic I-V curves, and two separate resistance states explored with alternated polarity pulses. This system showed neuromorphic properties such as short-time memory with stretched-exponential relaxation, and potentiation/depotentiation for subsequent applied voltage pulses. I characterized the bilayered NCAF conduction processes, suggesting a memristive-like model to explain the system's hysteresis characteristics taking into account the competition of a Poole-Frenkel (PF) and a Schottky conduction mechanisms [12]. Layered Au/ZrOx devices can be interfaced with biological systems, but their electrical resistance is very high (around 1 GΩ), being prohibitive for noise and readout operations. Furthermore, their electrical properties are strongly dependent on the characteristics of the 2-D interface between the two films, making it hard to control tuning geometry and deposition parameters.
For these reasons, I worked on the development of a deposition system able to produce composite NCAFs where Au and ZrOx clusters are interspersed. I have demonstrated a two-source Supersonic Cluster Beam Deposition Apparatus [Filippo Profumo et al., submitted] and I fabricated by this technique nanocomposite Au/ZrOx NCAFs with different zirconia contents. Their electrical properties, monitored in-situ during fabrication, resulted strongly related to zirconia concentrations and ranged from insulating characteristics for high ZrOx content to those of Au NCAFs. By the ex-situ electrical characterization of nanocomposite devices, I highlighted a “soft” activation of resistive switching with a gradual resistance transition, enhanced resistance retention, and the presence of Negative Differential Resistivity (NDR). Through an in-situ thermal TEM analysis of the morphological rearrangements of composite NCAFs with varying zirconia contents, combined with molecular dynamics simulations, I have addressed the improved stability of composite electrical properties to zirconia clusters acting as an insulating matrix and reducing the thermally driven diffusivity of gold atoms. [Andrea Falqui et al., submitted].
Since NCAFs exhibit complicated quasi-random electrical activity, a different neural signal processing approach than those described for other memristive devices [13] is needed to proceed toward a BMI application. The Inter-Switch Interval (ISI) analysis [14], [15] has been used to analyze the switching features of Au NCAFs under constant applied voltage [5], [16]. However, I mainly focused on pulsed stimuli, producing current traces with non-Gaussian distributions if applied on composite NCAF, and incompatible with an ISI analysis.
I thus investigated the autocorrelation function of current traces following a power law decrease, as reported for similar gold nanoparticle systems [15], and sensitive to voltage and alternated polarity of pulses capable of varying its decay trend. To identify distinctive parameters of current recordings and their relationship with input pulse parameters, I introduced the use of a time-series analysis capable of comparing a large number of statistical methods at once [17]. I evinced that the voltage and polarity of applied pulses influence significantly other statistical features of the current trace recorded from the nanocomposite devices and that general voltage input signals (input-timeseries) are mapped into current recording (output-timeseries) with new statistical features.
Exploiting this input/output map, I have demonstrated the possibility of classifying, in real-time, in-vivo neural recordings of rats according to their registration location and activity (normal or abnormal) [Filippo Profumo, submitted], representing a step towards the decoding of neuronal signals by the intrinsic processing of neuromorphic devices and thus towards the development of NCAF-based BMI.
References
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[4] E. Musk, ‘An integrated brain-machine interface platform with thousands of channels’, 2019.
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[7] C. Schulte et al., ‘Conversion of nanoscale topographical information of cluster-assembled zirconia surfaces into mechanotransductive events promotes neuronal differentiation’, J Nanobiotechnol, vol. 14, no. 1, p. 18, Dec. 2016, doi: 10.1186/s12951-016-0171-3.
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[10] A. Previdi et al., ‘Nanotopography and Microconfinement Impact on Primary Hippocampal Astrocyte Morphology, Cytoskeleton and Spontaneous Calcium Wave Signalling’, Cells, vol. 12, no. 2, p. 293, Jan. 2023, doi: 10.3390/cells12020293.
[11] F. Profumo, F. Borghi, A. Falqui, and P. Milani, ‘Potentiation and depression behaviour in a two-terminal memristor based on nanostructured bilayer ZrO x /Au films’, J. Phys. D: Appl. Phys., vol. 56, no. 35, p. 355301, Aug. 2023, doi: 10.1088/1361-6463/acd704.
[12] D. Cipollini, F. Profumo, L. Schomaker, P. Milani, and F. Borghi, ‘Conduction mechanisms in a planar nanocomposite resistive switching device based on cluster-assembled Au/ZrOx films’, Front. Mater., vol. 11, May 2024, doi: 10.3389/fmats.2024.1385792.
[13] I. Gupta, A. Serb, A. Khiat, R. Zeitler, S. Vassanelli, and T. Prodromakis, ‘Real-time encoding and compression of neuronal spikes by metal-oxide memristors’, Nat Commun, vol. 7, no. 1, p. 12805, Sep. 2016, doi: 10.1038/ncomms12805.
[14] M. Karsai, K. Kaski, A.-L. Barabási, and J. Kertész, ‘Universal features of correlated bursty behaviour’, Sci Rep, vol. 2, no. 1, p. 397, Dec. 2012, doi: 10.1038/srep00397.
[15] J. B. Mallinson, S. Shirai, S. K. Acharya, S. K. Bose, E. Galli, and S. A. Brown, ‘Avalanches and criticality in self-organized nanoscale networks’, Science Advances, vol. 5, no. 11, p. eaaw8438, Nov. 2019, doi: 10.1126/sciadv.aaw8438.
[16] G. Nadalini, F. Borghi, T. Košutová, A. Falqui, N. Ludwig, and P. Milani, ‘Engineering the structural and electrical interplay of nanostructured Au resistive switching networks by controlling the forming process’, Sci Rep, vol. 13, no. 1, Art. no. 1, Nov. 2023, doi: 10.1038/s41598-023-46990-4.
[17] B. D. Fulcher, M. A. Little, and N. S. Jones, ‘Highly comparative time-series analysis: the empirical structure of time series and their methods’, Journal of The Royal Society Interface, vol. 10, no. 83, p. 20130048, Jun. 2013, doi: 10.1098/rsif.2013.0048
A Florentine family in crisis: the Strozzi in the fifteenth century.
No full textPhDIn 1434 the Strozzi lineage had held a leading position in
Florentine society and government for at least one hundred and fifty
years, and was one of the largest and wealthiest of the city's
patrician lineages. The records of the catasto of 1427 and of the
scrutiny of 1433 are used to give a profile of the dominant social,
economic and political position of the Strozzi before the advent of
Medicean dominance. Their record of electoral success, and the
political and cultural leadership of influential and respected men
such as Palla di Nofri and Matteo di Simone, with other factors, put
the Strozzi amongst the greatest enemies of the victorious Medicean
regime of late 1434. The effects of political opposition and exile
on the lineage are examined both directly, through records of office-holding,
and indirectly through such indicators as marriage alliances
and household wealth. The two most prominent lines of the Strozzi
were exiled after 1434. Palla di Nofri's life and preoccupations in
his Paduan exile are examined, together with the lives of his sons;
none of these Strozzi ever returned to Florence, pursued as they were
by the enmity of the Medicean regime. The very different careers of
Filippo di Matteo and his brother Lorenzo are also examined: how they
succeeded in founding a lucrative bank in Naples, and in returning to
Florence to 'rebuild' (rifare) the position of the Strozzi lineage
there. The final decades of the century saw the Strozzi in an
economically more secure position, due substantially to the efforts
of Filippo. Except for a very small number of its members admitted
into the regime, most of the lineage is here shown to have remained
excluded from significant political office until after the fall of
the Medici regime in 1494
Photoarylation/Alkylation of Bromo-Naphthols
No full textThe photochemistry of 6-bromo-2-naphthols has been studied in acetonitrile, aqueous acetonitrile, and isopropyl alcohol in the absence and in the presence of triethylamine by product distribution analysis, laser flash photolysis (LFP), fluorescence, phosphorescence, electrochemical measurements, and DFT calculations. Hydrobromic acid loss in the presence of Et3N occurs from the triplet state of 6-bromo-2-naphthol, generating an electrophilic carbene intermediate, which has been successfully trapped by oxygen, allyltrimethylsilane, 2,3-dimethylbut-2-ene, pyrrole, acrylonitrile, 1,4-dimethoxybenzene, and also pyridine.
The generation and the reactivity of a triplet carbene intermediate has been supported by LFP, with the
detection of 2,6-naphthoquinone-O-oxide (530-650 nm) in the presence of O2. The electrophilic diradical character of the carbene has been supported by DFT calculations, using the B3LYP, PBE0, and MPWB1K functionals, with the 6-31+G(d,p) basis set and PCM solvation model
Vues présentes sur le celtique cisalpin
No full textPresent views on Cisalpine Celtic.
During the last twenty years, the knowledge of Lepontic and of Italian Gaulish has been notably enriched by very important finds, and also by numerous studies. The author proposes a synthesis of all new linguistical and cultural data provided by epigraphy in this particular resort.Dans les vingt dernières années la connaissance du lépontique et du gaulois d’Italie a été notablement enrichie par certaines trouvailles fort importantes ainsi que par de nombreuses études. Tableau synthétique des nouvelles données linguistiques et culturelles apportées par l’épigraphie de ce domaine.Motta Filippo. Vues présentes sur le celtique cisalpin. In: Etudes Celtiques, vol. 29, 1992. Actes du IXe congrès international d'études celtiques. Paris, 7-12 juillet 1991. Deuxième partie : Linguistique, littératures. pp. 311-318
Novel Naphthalene Diimides as Activatable Precursors of Bisalkylating Agents, by Reduction and Base Catalysis
No full textMild activation of water-soluble naphthalene diimides (NDIs) as bisalkylating agents has been achieved by base catalysis and by chemical and electrochemical reductions. NDI activation by a single electron reduction represents a novelty in the field of activatable electrophiles. Under mild reduction, induced by dithionite in aqueous solution, the resulting NDI radical anion undergoes a monomolecular fragmentation to yield a new transient species, where the NDI radical anion is tethered to a quinone methide moiety. The latter still retains electrophilic properties, reacting with amines, thiols, and ethyl
vinyl ether. Owing to the NDI recognition properties, these results represent the first step toward selective and bioactivatable cross-linking agents
Occhi pieni e mani vaganti. Movimenti, emozioni, astrazioni.
No full textFilippo FIMIANI, Occhi pieni e mani vaganti. Movimenti, emozioni, astrazioni, «Fata Morgana», 12/2010, pp. 147-164. ISSN 1970-5786.
ITALIANO. Una piccola sequenza da un episodio della serie televisiva Mad Men in cui la relazione sensoriale emozionale tra lo spettatore e un corpo in movimento, precisamente un corpo danzante, è l’oggetto di questo articolo, che intende così verificare la cosiddetta naturalizzazione della fenomenologia e del corpo vissuto operata dalle scienze cognitive applicate agli studi visuali. L’autore mostra anche i rapporti tra la cosiddetta simulazione incarnata e una memoria simbolica e iconografica profonda, e discute in particolare la polarità tra proiezione e introiezione, attività e passività nell’esperienza empatica delle immagini in movimento.A short filmic example from the AMC's award-winning series Mad Men in which the sensorial and emotional relationship between the spectator and a moving body, i.e., a dancing body, is explicitly put into play. The essay wants to deal with the so called naturalization of phenomenology and of the living body, trained by the cognitive sciences reading the visuality. The author shows the relationship between the so called ‘embodied Simulation’ and a symbolic and iconographic deep memory of the pictures, and he gives an in-depth attention to the polarity between projections and introjections, activity and passivity of the spectator’s body during the empathic experience of the moving pictures
Multiple political geographies
No full textThis chapter delves into the multifaceted realm of political geography within the context of the journal Political Geography. The author, who has held various editorial positions within the journal, navigates the intricate terrain of diversity and inclusion, exploring the challenges posed by linguistic and cultural biases inherent in academic publishing. The chapter critically examines efforts to mitigate barriers and broaden the scope of political geography, questioning the adequacy of current approaches. Through a reflective analysis, the author elucidates the complex dynamics of political geography as a subdiscipline, shedding light on both the impediments and possibilities it offers to researchers and students
Erratum to: Lung Tissue Damage Caused by Heat Accumulation from Adjacent Laser Application: Surgical Implications (Thoracic and Cardiovascular Surgeon (2014) DOI: 10.1055/s-0034-1389086)
No full textIt has been brought to the Publisher's attention that the author names "Filippo Lococo" and "Alfredo Cesario" were not listed correctly in the above-mentioned article, published on eFirst on September 5, 2014. DOI of the original article is DOI: 10.1055/s-0034-1389086. The names should be read as "Filippo Lococo" and "Alfredo Cesario" in place of "Lococo Filippo" and "Cesario Alfredo."
Fasti di Lodovico XIV. il Grande : esposti in versi in occasione dell'esser levato al sacro fonte il primogenito del marchese Filippo cavalier Sampieri in nome di S.M. Cristianissima.
No full textIllustrated with etchings, comprising a portrait of Louis XIV by Francesco Maria Francia, and 12 plates by Lodovico Mattioli.Each of the twelve cantos is by a different author. Names supplied in manuscript in table of contents, p. [1] at end.Dedication signed: Filippo Sampieri.Imprint from colophon.Signatures: pi⁴ A-O⁸ P⁴.Mode of access: Internet.Bound in old vellum; ink title and library shelf mark on spine
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