Electrochemical properties and electrochemical impedance spectroscopy of polypyrrole-coated platinum electrodes

Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical properties studied by cyclic voltammetry. Impedance spectra were obtained at potentials ranging from 0 to 0.8 V/SCE. The EIS data were fitted using two different equivalent electrical circuits (depending on the nature of the dopant). They involve a diffusive capacitance, which increased with the passing charge during electrosynthesis (i.e. film thickness) for ClO4--doped PPy, but was practically unaffected by the film thickness in the case of SDS-doped PPy. Also, a double-layer capacitance was found only in the circuit of ClO4--doped PPy. It increased with the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance (Rct) obtained with SDS is nearly 200-fold higher than that obtained with ClO4- in the same solvent (H2O). With the same dopant (ClO4-), Rct is about five times higher in acetonitrile relative to water. All these EIS results of the different types of PPy suggest a relation with the wettability of the polymer.KEY WORDS: Conducting polymers, Polypyrrole, Electrochemical impedance spectroscopy, Equivalent-electrical circuit, Micellar mediaBull. Chem. Soc. Ethiop. 2006, 20(2), 279-293

Gold oxide films grown in the confined aqueous layer between gold and organic solvents

The properties of anodic passive films potentiostatically formed on polycrystalline gold in aqueous phosphate solutions were studied using voltammetry, electrochemical impedance spectroscopy, and contact angle measurements. The nature of the gold oxide layer was analyzed as a function of a potential holding in the aqueous double layer charge region at the interface between gold and the aqueous layer confined by insoluble organic solvents (hexane, chloroform, anisole, butyl acetate, xylene, and isopropyl ether). Different growth conditions change the homogeneity of the oxide layer leading to different passive properties. A synergetic effect on the gold oxidation of hydrogen dissolved in both the bulk metal and the confined aqueous layer is discussed.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasInstituto de Física de Líquidos y Sistemas Biológico

SENSE: A comparison of photon detection efficiency and optical crosstalk of various SiPM devices

This paper describes a comparison of photon detection efficiency and optical crosstalk measurements performed by three partners: Geneva University, Catania Observatory and Nagoya University. The measurements were compared for three different SiPM devices with different active areas: from 9 $mm^2$ up to 93.6 $mm^2$ produced by Hamamatsu. The objective of this work is to establish the measurements and analysis procedures for calculating the main SiPM parameters and their precision. This work was done in the scope of SENSE project which aims to build roadmap for the last developments in field of sensors for low light level detection

Lightweight Model for Session-Based Recommender Systems with Seasonality Information in the Fashion Domain

This paper presents the solution designed by the team "Boston Team Party"for the ACM RecSys Challenge 2022. The competition was organized by Dressipi and was framed under the session-based fashion recommendations domain. Particularly, the task was to predict the purchased item at the end of each anonymous session. Our proposed two-stage solution is effective, lightweight, and scalable. First, it leverages the expertise of several strong recommendation models to produce a pool of candidate items. Then, a Gradient-Boosting Decision Tree model aggregates these candidates alongside several hand-crafted features to produce the final ranking. Our model achieved a score of 0.18800 in the public leaderboard. To aid in the reproducibility of our findings, we open-source our materials

The effects of oral supplements with sambucus nigra, Zinc, Tyndallized Lactobacillus acidophilus (H122), Arabinogalactans, Vitamin D, vitamin E and Vitamin C in otitis media with effusion in children: a randomized controlled trial

– OBJECTIVE: To evaluate the ability of oral supplements with immune-stimulating molecules (Sambucus nigra, Zinc, Tyndallized Lactobacillus acidophilus (H122), Arabinogalactans, vitamin D, vitamin E and vitamin C) to reduce the inflammation of the upper airway tract and improve the outcome of otitis media with effusion (OME) in children. PATIENTS AND METHODS: Randomized controlled trial. One-hundred ninety-eight children (CI 95%: 12-96 months) were divided into four groups. Group 1 (48 subjects) received 10 ml of oral supplements (OS) with immune-stimulating molecules for three months (20 days consecutively, then 10 days of suspension – the therapeutic scheme was repeated three times); Group 2 (54 children) underwent treatment with 10 ml of OS for 90 consecutive days; Group 3 (48 subjects) received 15 ml of OS for 45 consecutive days; a control group (48 children) underwent the standard treatment for rhinitis and OME. Outcome measures included otoscopy, tympanometry, fibroendoscopy, and the pure tone audiometry (PTA) at T0 (before treatment), T1 (45 days after treatment), and T2 (90 days after treatment). RESULTS: All children treated with OS showed a reduction of Upper Airway Infection (UAI) episodes and OME compared to the control group independent of the administration method and posology. The three groups treated with OS showed statistically significant differences between T0 and T2 for otoscopy, tympanometry, fibroendoscopy, and PTA. In Group 2, the otoscopy and the tympanometry scores improved at T1. Group 2 and 3 had better PTA results than Group 1. CONCLUSIONS: OS with immune-stimulating molecules should be considered as a supporting therapy in children affected by recurrent episodes of UAI associated with OME due to their capacity to improve the immune response and reduce the inflammatory phenomena. OS can improve the fibroendoscopic findings by restoring middle ear ventilation, in addition to their ability to reduce inflammation in the middle ear

Electrochemical and optical study of the confined aqueous layer adsorbed on gold electrodes cycled in phosphate and dodecylsulphate solutions

The properties of the confined aqueous layer potentiodynamically formed on polycrystalline gold in aqueous phosphate and sodium dodecylsulphate solutions were studied using voltammetry, ellipsometry, and contact angle measurements. The nature of the incipient oxide layer was analyzed as a function of the cycling time in the double layer-oxide monolayer potential region. The replacement of the electrolyte by hexane allows the increase of the optical signal. Different potential cycling conditions change the homogeneity of the confined aqueous incipient oxide layer leading to different structural characteristics.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

The effect of social media and infodemic on mental health during the COVID-19 pandemic: results from the COMET multicentric trial

On January 30, 2020, the World Health Organization (WHO) declared the status of pandemic due to the COVID-19 infection. The initial phases of the pandemic were characterized by uncertainty and public fears. In order to cope with such unexpected conditions, people adopted different coping strategies, including search for information, accessing Internet, and using social media. The present study based on the COMET collaborative research network aims to: (1) assess use of Internet and of social media among the Italian general population; (2) explore differences in web usage between people with pre-existing mental disorders and the general population; (3) identify changes over time in social media usage along the phase 1 of the pandemic; (4) identify the clinical, socio-demographic and contextual predictors of excessive use of social media. A significant increase in time spent on Internet, with an average time of 4.8 & PLUSMN; 0.02 h per day, was found in the global sample of 20,720 participants. Compared with the general population, Internet use was significantly higher in people with pre-existing mental disorders (5.2 & PLUSMN; 0.1 h vs. 4.9 & PLUSMN; 0.02; p < 0.005). According to the multivariate logistic regression model, the risk of excessive use of social media and Internet was significantly higher in people with moderate levels of depressive symptoms (OR: 1.26, CI 95%: 0.99 to 1.59, p < 0.0.005); while protective factors were being students (OR: 0.72, CI 95%: 0.53 to 0.96, p < 0.0029) and living in central Italy (OR: 0.46, CI 95%: 0.23 to 0.90, p < 0.002). The evaluation of social media and Internet use by the general population represents a first step for developing specific protective and supportive interventions for the general population, including practical suggestions on how to safely use Internet and social media