Protein clustering in chemically stressed HeLa cells studied by infrared nanospectroscopy

Photo-Thermal Induced Resonance (PTIR) nanospectroscopy, tuned towards amide-I absorption, was used to study the distribution of proteic material in 34 different HeLa cells, of which 18 were chemically stressed by oxidative stress with Na3AsO3. The cell nucleus was found to provide a weaker amide-I signal than the surrounding cytoplasm, while the strongest PTIR signal comes from the perinuclear region. AFM topography shows that the cells exposed to oxidative stress undergo a volume reduction with respect to the control cells, through an accumulation of the proteic material around and above the nucleus. This is confirmed by the PTIR maps of the cytoplasm, where the pixels providing a high amide-I signal were identified with a space resolution of ∼300 × 300 nm. By analyzing their distribution with two different statistical procedures we found that the probability to find protein clusters smaller than 0.6 μm in the cytoplasm of stressed HeLa cells is higher by 35% than in the control cells. These results indicate that it is possible to study proteic clustering within single cells by label-free optical nanospectroscopy

Didattica a Distanza e Online Learning: rischi e opportunità d'innovazione

In this paper we discuss the results of an exploratory research conducted with the aim of investigating the practices of teachers during the interruption of face- to-face school activities and the provision of online training. To deliver online courses it is necessary to have specific skills for which teachers were not evenly prepared. Far from considering remote teaching a simple parenthesis with no long-term consequences on the educational institutions, it is rather believed that it can lay the foundations for a conscious rethinking of the ways of doing school from which innovation processes can arise.Il presente contributo discute gli esiti di una ricerca esplorativa condotta con lo scopo di indagare le pratiche dei docenti durante la sospensione delle attività scolastiche in presenza e l’erogazione della formazione online. Per erogare corsi online è necessario possedere skills specifiche rispetto alle quali la classe docente non era uniformemente preparata. Lungi dal considerare la Didattica a Distanza una parentesi priva di conseguenze a lungo termine, si ritiene, piuttosto, che essa possa porre le basi per un ripensamento consapevole dei modi di fare scuola da cui possano scaturire processi di innovazione

Come possiamo farlo succedere? Dalla descrizione alla previsione negli ambienti di apprendimento on line

This paper proposes a Learning Analytics approach aimed at the study of event-driven data coming from 18 courses activated within a Moodle platform concerning two categories: post-graduate training courses and courses activated in the context of larger research projects. The objective is to identify possible patterns of interaction on the part of users enrolled in the two course categories in order to give useful indications for aneffective Learning Design of future courses.The context of higher education, in particular the post-graduate one, is the field in which research on the field can find more fertile ground: training is often provided in e-learning mode, consistently with the need to make the training flexibly responding to the needs of an adult user, inserted in a context of lifelong learning.Il presente contributo propone un approccio di Learning Analytics rivolto allo studio di event-driven data provenienti da 18 corsi attivati all’interno di una piattaforma Moodle afferenti a due categorie: corsi di formazione post-lauream e corsi attivati nell’ambito di progetti di ricerca. L’obiettivo è quello di individuare possibili pattern d’interazione da parte degli utenti iscritti alle due categorie di corso al fine di dare indicazioni utili alla progettazione efficace di futuri corsi.Il contesto della formazione superiore, in particolare quella post-lauream, è il campo in cui la ricerca sul tema dei Learning Analytics può trovare maggiore terreno fertile: la formazione è sovente erogata in modalità e-learning, coerentemente alla necessità di rendere la didattica flessibilmente rispondente ai bisogni di un’utenza adulta, inserita in un contesto di lifelong learning

Benchmarking the Use of Heavily-Doped Ge Against Noble Metals for Plasmonics and Sensing in the Mid-Infrared

Despite the recent introduction of heavily-doped semiconductors for mid-infrared plasmonics, it still remains an open point whether such materials can compete with noble metals. We employ a whole set of figures of merit to thoroughly assess the use of heavily-doped Ge on Si as a mid-infrared plasmonic material and benchmark it against standard noble metals such as Au. In doing this, we design and model high-performance, CMOS compatible mid-infrared plasmonic sensors based on experimental material data reaching plasma frequencies up to about 1950 cm−1. We demonstrate that plasmonic Ge sensors can provide signal enhancements for vibrational spectroscopy above 3 orders of magnitude, thus representing a viable alternative to noble metals

Integrated Germanium-on-silicon Waveguides for Mid-infrared Photonic Sensing Chips

Germanium-on-silicon waveguides are designed, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the in-coupling efficiency. On-chip propagation along bends and straight sections up to 0.8 mm is demonstrated around λ = 6 μm

Humanoid Robotics: a teaching/learning challenge Robotica umanoide: una sfida per insegnamento e apprendimento

Humanoid robotics will help us to live better (Cingolani, 2018): human-like robots able to inter- act with their surroundings are no longer science fiction, but they can be purchased by e- commerce platforms. Dealing with the new evolutionary paradigm based on artificial intelligence and machine learning is a challenge that every education system must take up. A humanoid robot ad school can be considered a generator of innovation in teaching and learning: in this paper we describe a teaching experience with humanoid robot Nao in a Scientific High School with Italian Croce Rossa. The aim is to investigate how to introduce the artificial intelligence in school curriculum. Using humanoid robotics in teaching practices facilitates creative dynamics, that is distinctive of divergent thinking. So, within a conscious learning design, Nao becomes a tool useful to mediate through know-how and know-how-to-be.La robotica umanoide ci aiuterà a vivere meglio (Cingolani, 2018): macchine con sembianze umane, capaci di interagire con l’ambiente circostante, non sono più fantascienza, ma acquistabili sulle piattaforme di e-commerce. Confrontarsi con il nuovo paradigma evolutivo, basato su intelligenza artificiale e machine learning, è una sfida che ogni sistema di istruzione deve cogliere. Un robot umanoide a scuola può essere considerato un generatore di innovazione nell’insegnamento e nell’apprendimento: il presente contributo mira a descrivere un’esperienza didattica con il robot umanoide Nao condotta in un Liceo Scientifico con la collaborazione della Croce Rossa Italiana, per indagare come si può inserire l’intelligenza artificiale nel curricolo scolastico. L’introduzione della robotica umanoide nelle prassi educative facilita dinamiche creative tipiche del pensiero divergente. Quindi, inserito all’interno di una sapiente progettazione educativa, questo dispositivo diviene strumento di mediazione tra sapere e saper essere

Germanium-on-silicon Waveguides for Mid-infrared Photonic Sensing Chips

Germanium-on-silicon rib waveguides are modelled, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the waveguide losses at 5.8 μm wavelength

Time-resolved investigation of nanometric cell membrane patches with a mid-infrared laser microscope

The proton pump Bacteriorhodopsin (BR) undergoes repeated photocycles including reversible conformational changes upon visible light illumination. Exploiting the sensitivity of infrared (IR) spectra to the conformation, we have determined the reaction kinetic parameters of the conductive intermediate M for the wild-type protein and for its slow mutant D96N during its photocycle. Time-resolved IR micro-spectroscopy using an in-house developed confocal laser microscope operating in the mid-IR is employed to record absorption changes of 10−4 at wavelengths λ1 = 6.08 μm and λ2 = 6.35 μm, assigned to backbone and retinal structural modifications, respectively. Protein samples were embedded in dried lipid bilayers deposited on ultraflat gold supports to enhance the surface field. The signals were analyzed according to a simplified photocycle model with only two dominant states: the dark-adapted state BR* and the intermediate M. We obtained the excitation and relaxation times of the intermediate M from exponential fits to the absorption change time traces. Our results constitute a first step towards future plasmonic-assisted nanoscale time-resolved mid-IR spectrometers for the characterization of bioelectronic and light-harvesting nanodevices based on BR

Group-IV midinfrared plasmonics

The use of heavily doped semiconductors to achieve plasma frequencies in the mid-IR has been recently proposed as a promising way to obtain high-quality and tunable plasmonic materials. We introduce a plasmonic platform based on epitaxial n-type Ge grown on standard Si wafers by means of low-energy plasma-enhanced chemical vapor deposition. Due to the large carrier concentration achieved with P dopants and to the compatibility with the existing CMOS technology, SiGe plasmonics hold promises for mid-IR applications in optoelectronics, IR detection, sensing, and light harvesting. As a representative example, we show simulations of mid-IR plasmonic waveguides based on the experimentally retrieved dielectric constants of the grown materials

Mid-infrared n-Ge on Si Plasmonic Based Microbolometer Sensors

The detection and amplification of molecular absorption lines from a chemical weapons simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. A free-standing Si0.25Ge0.75 microbolometer detector with n-Ge plasmonic antenna is demonstrated as an integrated mid-infrared plasmonic sensor