Hydrogen sensing by sol-gel grown NiO and NiO:Li thin films

Hydrogen sensors have been prepared using nickel oxide (NiO) and lithium-doped nickel oxide (NiO:Li) thin films, deposited on glass substrates by the sol-gel spin coating technique. The surface morphology, structure, optical and electrical properties of the obtained films were studied. Hydrogen sensing results are presented for three operating temperatures (140, 160, and 180 {\deg}C) and for hydrogen concentrations ranging from 1000 to 15000 ppm in synthetic air. The NiO and NiO:Li (2% and 8% doping concentrations) sensors show maximum responses for the operating temperature of 180 {\deg}C. When tested at different hydrogen concentrations in air, the lithium-doped NiO sensors showed a higher response than the undoped NiO films

Le marché de bestiaux du gouvernorat de Sidi Bouzid: un levier de développement rural du Centre tunisien

L’élevage ovin est une activité traditionnelle dans toutes les régions de la Tunisie et surtout le Centre et le Sud. Sur le plan national et jusqu'à une date récente seule la viande bovine retenait l'attention des pouvoirs publics et les opérateurs privés. Face aux enjeux actuels de satisfaction des besoins du pays en viandes rouges et la mise à niveau de la filière des ovins, on assiste à un processus de développement du secteur qui connaît une restructuration du cheptel et une intensification de la production en intégrant les cultures fourragères ainsi qu’une mise à niveau des marchés de bestiaux. Dans le gouvernorat de Sidi Bouzid où l’élevage ovin occupe une place de choix dans l’économie régionale, les systèmes de production agricole connaîssent une mutation profonde. Le développement du secteur irrigué et la diversification des systèmes de cultures et d'élevage expliquent la croissance de l’agriculture et le développement de la région. Cette mutation a touché aussi la structure du marché et les circuits de commercialisation des animaux. La commercialisation des viandes rouges est étroitement liée à l’élevage de bétail qui reste encore très dépendant des conditions climatiques et des politiques suivies. Dans la région de Sidi Bouzid, on dénombre des circuits différenciés de distribution des animaux et la concurrence est relativement forte. La performance du marché est caractérisée par la faiblesse des marges bénéficiaires dégagées par les éleveurs et les bouchers en comparaison avec les intermédiaires. Ce travail cherche à analyser la structure, les comportements des acteurs et la performance du marché de bestiaux de Sidi Bouzid –l’un des plus grands et connus des marchés du pays- et son rôle dans la dynamique de la filière ovine et dans le développement régional.Agricultural and Food Policy, Community/Rural/Urban Development, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Institutional and Behavioral Economics, International Relations/Trade, Marketing, Production Economics, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,

Anonymous Feedback Using Digital Walls: A Case Study

A common problem faced by many language teachers is students’ fear from speaking in front of the whole class and making mistakes. Research showed that reticence to participate in class may influence students’ language learning who may miss important opportunities for correction. This paper reports on students’ reactions to the use of digital walls to provide anonymous oral feedback and to maximize students’ participation. The students engaged in answering three-minute instructor-posed questions on their mobile devices using an application called Quick fire as found on www.spiral.ac. The anonymous answers were displayed instantaneously on the smartboard which allowed the instructor to provide the students with real-time feedback. The students answered 14 questions after eight weeks of instruction. At the end of the project, the students were invited to focus group discussions in order to delve into their opinions about using digital walls for providing feedback and encouraging class participation. Qualitative analysis of the students’ comments indicated that they had a generally positive experience and that anonymous posting can foster students’ engagement

Hungry for content: How the COVID-19 pandemic changed media usage in the Middle East and North Africa

While the uprisings during the Arab Spring had a significant influence on the adoption of technology and its insertion into peoples' daily lives, the COVID-19 pandemic has been paramount to the new disruptions in the media landscape, provoking accelerated changes as well as novel relations between social actors on mediatised platforms. Whereas the first paradigm shift with media usage can be found in the adoption of the internet and user-generated content on media platforms, the second paradigm shift observed at the time of the pandemic is an acceleration of media consumption, as well as interwoven relations between work and play on mediatised platforms, creating both solidarity and distance between the users of digital content. The pandemic marks a new technological milestone in audiences’ media usage and habits, one that has thus far been both positive - through the interconnectedness and agency - and negative - because of a lack of access for some - for cultural diversity and intercultural relations. The adoption of mobile internet skyrocketed in the region, and some countries, particularly Egypt and Saudi Arabia, have ranked among the countries with the highest penetration rates globally for platforms such as Facebook and YouTube

Earth-Abundant Tin Sulfide-Based Photocathodes for Solar Hydrogen Production.

Tin-based chalcogenide semiconductors, though attractive materials for photovoltaics, have to date exhibited poor performance and stability for photoelectrochemical applications. Here, a novel strategy is reported to improve performance and stability of tin monosulfide (SnS) nanoplatelet thin films for H2 production in acidic media without any use of sacrificial reagent. P-type SnS nanoplatelet films are coated with the n-CdS buffer layer and the TiO2 passivation layer to form type II heterojunction photocathodes. These photocathodes with subsequent deposition of Pt nanoparticles generate a photovoltage of 300 mV and a photocurrent density of 2.4 mA cm-2 at 0 V versus reversible hydrogen electrode (RHE) for water splitting under simulated visible-light illumination (λ > 500 nm, Pin = 80 mW cm-2). The incident photon-to-current efficiency at 0 V versus RHE for H2 production reach a maximum of 12.7% at 575 nm with internal quantum efficiency of 13.8%. The faradaic efficiency for hydrogen evolution remains close to unity after 6000 s of illumination, confirming the robustness of the heterojunction for solar H2 production

Procedure for Obtaining the Analytical Distribution Function of Relaxation Times for the Analysis of Impedance Spectra using the Fox HH-function

The interpretation of electrochemical impedance spectroscopy data by fitting it to equivalent circuit models has been a standard method of analysis in electrochemistry. However, the inversion of the data from the frequency domain to a distribution function of relaxation times (DFRT) has gained considerable attention for impedance data analysis, as it can reveal more detailed information about the underlying electrochemical processes without requiring a priori knowledge. The focus of this paper is to provide a general procedure for obtaining analytically the DFRT from an impedance model, assuming an elemental Debye relaxation model as the kernel. The procedure consists of first representing the impedance function in terms of the Fox $H$-function, which possesses many useful properties particularly that its Laplace transform is again an $H$-function. From there the DFRT is obtained by two successive iterations of inverse Laplace transforms. In the passage, one can easily obtain an expression for the response function to a step excitation. The procedure is tested and verified on some known impedance models

Information Encoding/Decoding using the Memory Effect in Fractional-order Capacitive Devices

In this study, we show that the discharge voltage pattern of a fractional-order supercapacitor from the same initial steady-state voltage into a constant resistor is dependent on the past charging voltage profile. The charging voltage was designed to follow a power-law function, i.e. $v_c(t)=V_{cc} \left( {t}/{t_{ss}}\right)^p \;(0<t \leqslant t_{ss})$, in which $t_{ss}$ (charging time duration between zero voltage to the terminal voltage $V_{cc}$) and $p$ ($0<p<1$) act as two variable parameters. We used this history-dependence of the dynamic behavior of the device to uniquely retrieve information pre-coded in the charging waveform pattern. Furthermore, we provide an analytical model based on fractional calculus that explains phenomenologically the information storage mechanism. The use of this intrinsic material memory effect may lead to new types of methods for information storage and retrieval.Comment: 5 pages, 3 figures, Submitted on Jan 28, 2021 to ACS Applied Electronic Materials - Manuscript ID: el-2021-00092

Possibility of information encoding/decoding using the memory effect in fractional-order capacitive devices

In this study, we show that the discharge voltage pattern of a supercapacitor exhibiting fractional-order behavior from the same initial steady-state voltage into a constant resistor is dependent on the past charging voltage profile. The charging voltage was designed to follow a power-law function, i.e. [Formula: see text], in which [Formula: see text] (charging time duration between zero voltage to the terminal voltage [Formula: see text]) and p ([Formula: see text]) act as two variable parameters. We used this history-dependence of the dynamic behavior of the device to uniquely retrieve information pre-coded in the charging waveform pattern. Furthermore, we provide an analytical model based on fractional calculus that explains phenomenologically the information storage mechanism. The use of this intrinsic material memory effect may lead to new types of methods for information storage and retrieval

Novas tecnologias, ferramentas inovadoras na promoção de um serviço : o caso da Meet West

Este relatório apresenta meu estágio efetuado na empresa de eventos Meet West, em Lisboa. Falaremos sobre o papel dos media sociais, as novas tecnologias, mas também da empresa em si e dos seus concorrentes. Em seguida, tentaremos responder à pergunta: ‘Em que medida as redes sociais ajudam a comunicação de uma empresa? ’. Serão utilizados dados recolhidos e analisados para chegar à algumas conclusões ou hipóteses.This report presents my internship in the event company West Meet in Lisbon. We will talk about the role of social media, new technologies, but also about the company itself and its competitors. We will then try to answer the question: 'To what extent social networks help the communication of a company? '. Collected data will be used and analyzed to have some conclusions or hypotheses