Enhancing Light Harvesting by Hierarchical Functionally Graded Transparent Conducting Al-doped ZnO Nano- and Mesoarchitectures

A functionally graded Al-doped ZnO structure is presented which combines conductivity, visible transparency and light scattering with mechanical flexibility. The nano and meso-architecture, constituted by a hierarchical, large surface area, mesoporous tree-like structure evolving in a compact layer, is synthesized at room temperature and is fully compatible with plastic substrates. Light trapping capability is demonstrated by showing up to 100% improvement of light absorption of a low bandgap polymer employed as the active layer.Comment: 21 pages, 6 figures, submitted to Solar Energy Materials and Solar Cell

Skeletal muscle characteristics and motor performance after 2-year growth hormone treatment in adults with prader-willi syndrome.

Context:In adults with Prader-Willi syndrome (PWS), abnormal body composition with decreased lean body mass and skeletal muscle (SM) volume has been related to altered GH secretion and may possibly contribute to greatly reduced motor capacity.Objective:The scope of the study was to test the hypothesis that GH treatment has favorable effects on SM characteristics and motor performance in adults with PWS.Design, Setting, and Participants:Fifteen obese PWS subjects (nine males and six females; age range, 19–35 y; body mass index, 37.7–59.9 kg/m2) were investigated before and after 12 (GH12) and 24 (GH24) months of GH treatment.Main Outcome Measures:SM cross-sectional area and SM attenuation were determined with computed tomography at the lumbar and midthigh levels. Maximal isometric handgrip strength and isokinetic knee extension peak torque were measured. Motor performance was evaluated with different indoor walking tests, whereas exercise endurance was assessed with a treadmill incremental test to exhaustion.Results:A condition of severe GH deficiency was found in six patients (40%). GH treatment significantly increased lean body mass (GH12, P < .05; GH24, P < .05), reduced percentage of body fat (GH12, P < .05; GH24, P < .05), and augmented SM cross-sectional area and SM attenuation of both lumbar (GH12, P < .01; GH24, P < .001) and thigh muscles (GH24, P < .05). Handgrip strength increased by 7% at GH12 (P < .05) and by 13% at GH24 (P < .001). Peak torque of knee extension extrapolated at zero angular velocity was significantly higher at GH24 (P < .01), and exercise endurance rose by 13% (P < .05) and 17% (P < .05) before exhaustion at GH12 and GH24, respectively, whereas no change was detected with walking tests. No significant difference in the response to GH treatment was detected between patients with and without GH deficiency.Conclusion:Long-term GH treatment in adult PWS patients improves body composition and muscle size and quality and increases muscle strength and exercise tolerance independently from the GH secretory status

Tuning electrical properties of hierarchically assembled Al-doped ZnO nanoforests by room temperature Pulsed Laser Deposition

Large surface area, 3D structured transparent electrodes with effective light management capability may represent a key component in the development of new generation optoelectronic and energy harvesting devices. We present an approach to obtain forest-like nanoporous/hierarchical Al-doped ZnO conducting layers with tunable transparency and light scattering properties, by means of room temperature Pulsed Laser Deposition in a mixed Ar:O2 atmosphere. The composition of the background atmosphere during deposition can be varied to modify stoichiometry-related defects, and therefore achieve control of electrical and optical properties, while the total background pressure controls the material morphology at the nano- and mesoscale and thus the light scattering properties. This approach allows to tune electrical resistivity over a very wide range (10^-1 - 10^6 Ohm*cm), both in the in-plane and cross-plane directions. Optical transparency and haze can also be tuned by varying the stoichiometry and thickness of the nano-forests

Integrating MOOCs in physics preliminary undergraduate education: beyond large size lectures

In this paper, the authors discuss the effectiveness of MOOCs as part of a pedagogical strategy aimed at supporting Physics’ preliminary undergraduate students in large-size lectures. Our study is based on an experimental activity based on a blended course, which integrated a parallel MOOC delivered through the POK (PoliMi Open Knowledge, http://www.pok.polimi.it), the Politecnico di Milano’s MOOC portal. The blended model also delivered face-to-face activities that included intensive technology enhanced learning, like feedback based on clickers. Specifically, we introduce the several elements of the approach (the tutors’ pedagogy, the adoption of clickers, the diversity amongst learning groups) and its process of implementation. The findings in this study highlight that the integrated model is effective in terms’ of students’ learning both for small and large size lectures. More importantly, it was found that the students in large size lectures demonstrated similar or even better performance than students in a small size group. Moreover, the students in all sizes lectures showed higher satisfaction with the MOOCs’ against other factors adopted within the learning design

Un approccio misto alla didattica digitale integrata per i corsi di ripasso di Fisica al Politecnico di Milano

Il Politecnico di Milano organizza da anni i corsi di ripasso in fisica per le matricole dei corsi di ingegneria, con l’obiettivo di sanare eventuali lacune o misconcetti e favorire il successo formativo. Nell’ultimo anno accademico le limitazioni dovute all’emergenza sanitaria hanno portato a riprogettare completamente tali corsi per portarli in modalità a distanza adottando forme didattiche diversificate. La struttura del corso, diviso in 8 moduli per nuclei fondamentali, si è articolata in quattro tipi di attività: - lezioni frontali in streaming non interattive di circa un’ora, fruibili in modo sincrono o asincrono per tutti i circa 1000 iscritti - attività di circa tre ore, in gruppi virtuali di circa 100 studenti, con esempi ed esercizi svolti da tutor che stimolavano l’interazione tra pari - quiz proposti dai tutor nelle attività di gruppo, con raccolta delle risposte e discussione successiva - forum per interazioni totalmente asincrone con i tutor o il docente referente Al termine del corso gli studenti hanno espresso un grado di soddisfazione superiore al 75%. Il loro percorso universitario viene monitorato in forma anonima per valutare gli effetti a lungo termine del corso

A blended approach to online Physics refresher courses at Politecnico di Milano

The limitations posed by the Covid-19 pandemic require to explore different teaching methods when traditional lectures are not viable, especially in the case of large amounts of students and long online lecturing times. A novel approach to a remote Physics refresher course for perspective freshmen was devised at Politecnico di Milano. The course was delivered as a blend of streamed lectures, tutored lessons, group activities and forum-based discussions. A pool of approximately 1000 students took part in the course, experiencing different teaching styles and formats and indicating a satisfaction rate above 75%

Physics experiments and peer-assessment: an High-school – University project

In agreement with the latest EU recommendations in terms of key competences for lifelong learning, we present an example of close cooperation between students and teachers from secondary school, and professors and researchers from the Department of Physics of Politecnico di Milano. One of the general aims of school is to enhance the capability of students of making choices impacting their future, in a coherent manner with respect to their own attitudes and competences. For these purposes, the Italian secondary school system has introduced a dual system of vocational training Percorsi per le Competenze Trasversali e l’Orientamento, a mandatory project which helps students to discover their abilities and competences in relation with the professional world or with the academic world. Our activity is an example of this kind of project, involving 50 students of a fourth class and a fifth class (age 17-19) from two different scientific high schools. Each class participated in the project for an amount of 20 hours. The detailed plan of the project included four in-depth meetings on the topic of wave mechanics held by professors of the Politecnico di Milano, an experimental part carried out by students in groups of peers, their presentation of the experiment and a formative evaluation of the proposed work. The steps mentioned above were all closely linked to one another, in order to highlight peculiar features, attitudes and competences of each student. In the part of active involvement, students were asked to work in groups and build a real experiment concerning acoustic interferometry, collect and analyze the experimental data obtained and present them in two forms: a scientific report and a presentation. As a final step, students were involved in a peer evaluation process. Each group assessed the work and the presentation of the other classmates with the same rubric used by all the teachers involved in the project. In this work we present the activity, the results of peer evaluation and the feedback provided by students about the entire project

Didattica emergenziale/innovativa nei corsi di Fisica. Tra scuola e università

La necessità di adeguare la didattica alle nuove esigenze subentrate con la pandemia da Covid-19 ha portato alla riprogettazione di alcuni progetti dedicati alla didattica della Fisica organizzati dal Politecnico di Milano. I corsi di ripasso di Fisica dedicati alle matricole dell’anno accademico 2020-2021 si sono svolti da remoto con una modalità blended tra lezioni frontali, attività di gruppo con tutor e quiz in modalità telematica, mentre il progetto dei PCTO (Percorsi per le Competenze Trasversali e l'Orientamento, ex alternanza scuola-lavoro) per i licei scientifici ha visto l’alternarsi di seminari online ed esperimenti progettati e svolti autonomamente dagli studenti in gruppi. Il grado di soddisfazione espresso dagli studenti in merito a entrambi i progetti è risultato elevato, lasciando aperta la strada alla possibilità di ripetere esperienze di questo genere in futuro

Growth hormone therapy improves exercise capacity in adult patients with Prader-Willi syndrome

none6BACKGROUND: Prader-Willi syndrome (PWS) is associated with an inappropriate proportion of fat mass (FM) to non-FM compared to simple obesity. Altered body composition in PWS resembles that seen in subjects with GH deficiency, in which a reduction of lean body mass (LBM) is observed. The low LBM may contribute to the reduced motor skills seen in PWS patients. AIM: The objective of the study was to investigate the effects of GH therapy on exercise capacity and body composition in a group of adult subjects with PWS. SUBJECTS AND METHODS: Twelve PWS adults (7 males and 5 females, aged 26.4+/-4.4 yr, body mass index 44.3+/-4.6 kg/m2) participated in the study. Body composition analysis and exercise stress test were carried out throughout the 12 months GH therapy. Body composition was measured by Dual Energy X-ray Absorptiometry. Physical performance was evaluated using treadmill exercise test. Exercise intensity was expressed as metabolic equivalents (MET, 1 MET= 3.5 ml O2 kg(-1) min(-1)). Statistical analysis was performed by repeated-measures analysis of variance followed by post-hoc analysis with t test for paired data for comparisons among the different follow ups. RESULTS: Compared to baseline GH therapy increased LBM at 6 (p<0.0001) and 12 months (p<0.005) (45.3+/-7.7 kg vs 48.6+/-6.7 kg vs 48.2+/-7.5 kg). FM% was significantly reduced both after 6 and 12 months (p<0.02) (56.1+/-4.8% vs 53.7+/-4.2% vs 53.3+/-4.8%). Attained MET were found to be improved by 16% after 6 months and by 19% after 12 months of GH (p<0.001), while the small further rise between 6 and 12 months was not significant. CONCLUSIONS: Our findings seem to support the view that GH therapy has beneficial effects on physical activity and agility as well as on body composition of adult patients with PWS.noneGONDONI LA; VISMARA L; MARZULLO P; VETTOR R.; LIUZZI A; GRUGNI GGondoni, La; Vismara, L; Marzullo, P; Vettor, Roberto; Liuzzi, A; Grugni, G

Exploring Effective Physics Teaching Strategies in High Schools during the COVID-19 Pandemic

The need for educational approaches that comply with the restrictions arising from the COVID-19 pandemic has raised a number of critical issues for students of different age groups. The delicate transition between high school and university has become a key point to focus on, leading many institutions to replan projects dedicated to students involved in this transition. A Physics vocational training project for high school students was carried out in the school year 2020–2021, and it was replicated in the school year 2021–2022. The project included webinars, self-assembled laboratory group experiences, and peer evaluation. The starting point on which we designed our project is that learning is an experience; thus, we built the entire project by particularly focusing on two peculiarities. One peculiarity is the assessment methods: student presentations describing their own experiences were evaluated by teachers and their peers. The second peculiarity is the open approach with respect to how students handle experimental activities. We present a description of these projects along with the results of an evaluation survey filled out by the participants and a descriptive analysis of the assessment strategies. Students appreciated the design of the entire project and, better still, the peer evaluation process. Moreover, we discovered that the evaluation provided by the teachers is lower compared to the assessment reported by the students. This disparity holds potential significance from a statistical perspective and warrants further investigation