On the thermal and thermodynamic (In)stability of methylammonium lead halide perovskites

The interest of the scientific community on methylammonium lead halide perovskites (MAPbX3, X = Cl, Br, I) for hybrid organic-inorganic solar cells has grown exponentially since the first report in 2009. This fact is clearly justified by the very high efficiencies attainable (reaching 20% in lab scale devices) at a fraction of the cost of conventional photovoltaics. However, many problems must be solved before a market introduction of these devices can be envisaged. Perhaps the most important to be addressed is the lack of information regarding the thermal and thermodynamic stability of the materials towards decomposition, which are intrinsic properties of them and which can seriously limit or even exclude their use in real devices. In this work we present and discuss the results we obtained using non-ambient X-ray diffraction, Knudsen effusion-mass spectrometry (KEMS) and Knudsen effusion mass loss (KEML) techniques on MAPbCl3, MAPbBr3 and MAPbI3. The measurements demonstrate that all the materials decompose to the corresponding solid lead (II) halide and gaseous methylamine and hydrogen halide, and the decomposition is well detectable even at moderate temperatures (~60 °C). Our results suggest that these materials may be problematic for long term operation of solar devices

Digital making as a means to improve education

Contemporary education faces the challenge of teaching and learning key competences for students to strive as the next generation workers in the contemporary world characterised by rapid and profound transformation. In particular, the current societal trend of ‘making’ for laypeople especially enabled by rapid manufacturing and digital technologies is questioning the role of professional designers in a word where – as also design literature reports – ‘everybody is a designer’ (Manzini 2015; Cross 2011). The objective of this paper is presenting our preliminary reflections about the digitally enabled self-production trend (aka digital DIY) as a means for students to develop and improve the key competences to face the complexity of contemporary age This set of cognitive, interpersonal and intrapersonal skills generally recognised of fundamental importance for the next generation labour market, social cohesion and active citizenship comprises not only technical and engineering knowledge, but also creativity and critical thinking, effective communication and collaboration, plus a range of personal qualities such as motivation, curiosity, self-development and -management. Such key competences have been widely defined and work programmes have been activated to promote their application among the educational and work fields. In Europe, key competences represent the pillars of the Lifelong Learning programme edited by the European Commission (2006/962/EC). Across the United States some promoter (i.e. the Partnership for the 21st century skills, National Research Council) are trying to merge education, business, community and government leaders around these competences, mainly known as 21st century skills (The Partnership for 21st Century Skills, 2008). Since the last decades of the 20th century, research in learning processes have suggested the importance of making and doing as a means to foster the acquisition of these skills, especially the creative ones. Digital DIY is here envisaged as a creative practice in which people – including design students – may increase their self-confidence and empowerment. Rooted in design and construction, these digital making activities often emphasise the acquisition of problem-solving, critical thinking, creativity, cross disciplinarity and collaboration. Within the framework of the EU funded project ‘Digital Do-It-Yourself (DiDIY), we are going to explore the dynamics facilitating the acquisition of the key competences in this practice.We introduce a model representing the dynamics (over three levels; social innovation, social practice and creative process) and factors (i.e. technology, motivation and collaboration) for learning and skilling in this context. As design researchers, we aim at contributing by developing (co)design-driven tools facilitating the identification of the skilling dynamics in place where digital DIY practice takes place. In this specific paper we will firstly define such competencies as a result of a comparative study from literature analysis and then argue why they are developed through digital DIY. Finally, we will conclude with the proposal of transferring the skilling dynamics identified in digital DIY to education system

Skilling and Learning Through Digital Do-It-Yourself: The Role of (Co-)Design

The current trend of digitally enabled self-production (i.e. digital DIY) is emblematic of the contemporary attitude to making. Its investigation represents an opportunity for better understanding the dynamics underpinning the acquisition of competences for the next century citizens through making. The objective of this paper is presenting our preliminary reflections on the factors characterising the current trend of digital DIY, envisaged as a phenomenon of social innovation empowering people by developing skills through making collaboratively. We introduce a model representing the dynamics (over the three levels of social innovation, social practice and creative process) and factors (i.e. technology, motivation and collaboration) for learning and skilling in this context. The concluding section describes future developments based on co-design for the delivery of tools enabling designers and key players in four main areas of intervention in which the model can be transferred

Designing the drivers to boost Digital Creativity and enable Digital Maturity

With the world rapidly changing and the accelerated growth of emerging digital technologies, creativity has become more fundamental than ever before (Corazza, 2017). Digital Creativity is the ability to creatively and strategically apply digital technologies to innovate, thereby harnessing human-centered technological innovation to solve complex problems (Bruno and Canina, 2019). In this transitional era, design enables and empowers people’s creative design skills and mindsets. As educators, how can we concretely support learners in training and developing these creative abilities to face contemporary challenges and harness digital transformation opportunities? Within the framework of the DC4DM European project, the paper will describe the steps that led to the collection, selection and clustering of the essential Digital Creative Abilities considered as actual “drivers” that would enable creators to face Digital Transformation

Effective tunneling processes in an interferometer of helical edge states with an antidot

We consider an interferometer of edge states of a two-dimensional topological insulator with an antidot. We analyze the mechanisms leading to an effective tunneling with spin flip between different helical states.Fil: Rizzo, Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Camjayi, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Arrachea, Liliana del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Integrated AlGaAs source of highly indistinguishable and energy-time entangled photons

The generation of nonclassical states of light in miniature chips is a crucial step towards practical implementations of future quantum technologies. Semiconductor materials are ideal to achieve extremely compact and massively parallel systems and several platforms are currently under development. In this context, spontaneous parametric down conversion in AlGaAs devices combines the advantages of room temperature operation, possibility of electrical injection and emission in the telecom band. Here we report on a chip-based AlGaAs source, producing indistinguishable and energy-time entangled photons with a brightness of $7.2\times10^6$ pairs/s and a signal-to-noise ratio of $141\pm12$. Indistinguishability between the photons is demonstrated via a Hong-Ou-Mandel experiment with a visibility of $89\pm3\%$, while energy-time entanglement is tested via a Franson interferometer leading to a value for the Bell parameter $S=2.70\pm0.10$

Apresentação da Informação sobre os Alergénios Alimentares em Restauração Colectiva

Introdução: Apesar de inofensivos para a maioria da população, os produtos ou substâncias passíveisde causar alergias e ou intolerâncias alimentares podem ser fatais para os indivíduos susceptíveis. Coma entrada em vigor do Regulamento (UE) n.º 1169/2011, todos os operadores das empresas do sectoralimentar serão obrigados a disponibilizar esta informação, incluindo nos produtos não embalados.Objectivos: Apresentação da informação sobre os alergénios alimentares presentes em refeiçõesservidas numa empresa de restauração colectiva.Metodologia: Os alergénios incluídos no estudo foram os de menção obrigatória no Regulamento. Foifeita a análise das fichas informativas fornecidas pelos fabricantes e dos rótulos dos géneros alimentíciose os dados tratados no software Predictive Analytics SoftWare, tendo os géneros alimentíciossido divididos em 15 grupos e em alimentos processados e não processados.Resultados: Conseguiu-se recolher informação de 68,1% dos géneros alimentícios e a maioria tinhapelo menos um alergénio. Mais de metade da amostra era constituída por alimentos processados, osquais continham, em média, mais alergénios, à excepção de peixe e moluscos. Do total de génerosalimentícios em estudo, cerca de 20% contêm leite e glúten, 15% sulfitos e 10% soja e peixe, sendoestes os únicos alergénios para os quais se encontraram diferenças com significado estatístico.Conclusões: Foi possível recolher e disponibilizar a informação necessária para cumprir o dever de informaro consumidor. No entanto, apesar do fabricante de géneros alimentícios pré-embalados ser obrigadoactualmente a apresentar esta informação na rotulagem, registaram-se dificuldades e limitaçõesna recolha da mesma. Este estudo assume relevância tanto a nível da restauração colectiva, como daindústria alimentar, pois demonstra que há ainda muito trabalho a fazer para alargar a oferta alimentardos indivíduos susceptíveis, constituindo um campo de actuação a ser explorado pelos nutricionistas.Introduction: Although inoffensive for the majority of the population, products likely to causing food allergies and or intolerancesmay be fatal to susceptible individuals. With the introduction of Regulation (UE) n.º 1169/2011, contract cateringcompanies are forced to disclose this information, even on non packed foods.Objectives: Presentation of the information about food allergens present on meals served in a contract catering company.Methodology: The allergens included in the study were the mandatory by Regulation (UE) n.º 1169/2011. The foods factsheets provided by suppliers and labels were analyzed and their data was treated with the Predictive Analytics SoftWare.The foods were divided into 15 groups and into processed and non processed foods.Results: We were able to collect information on 68,1% of the foods and the majority had, at least, one allergen. More thanhalf of the sample was comprised of processed foods which, on average, had more allergens, with the exception of fish andmollusks. Of the total of foods in study, about 20% contain milk and gluten, 15% sulfites and 10% soy and fish. It was onlyfor these allergens that statistically significant differences were found.Conclusions: It was possible to gather and provide the necessary information to fulfill the duty of informing the customer.However, although the manufacturer of pre-packed foods is nowadays obligated to present this information on thelabel, there were difficulties and limitations collecting it. This study is relevant both to contract catering and food industry,because it shows that there's still a lot of work to be done broadening food offer to susceptible individuals. Therefore is anactuation field to be explored by nutritionists

Ordered-disordered domain coexistence in ternary lipid monolayers activates sphingomyelinase by clearing ceramide from the active phase

We explored the action of sphingomyelinase (SMase) on ternary monolayers containing phosphatidylcholine, sphingomyelin (SM) and dihydrocholesterol, which varied along a single tie line of phase coexistence. SMase activity exhibited a higher rate and extent of hydrolysis when the film is within the liquid-expanded (LE)/liquid-ordered (LO) coexistence range, compared to monolayers in the full LO phase. Since Alexa-SMase preferably adsorbs to the LE phase and there was no direct correlation found between enzymatic activity and domain borders, we postulate that the LE phase is the active phase for ceramide (Cer) generation. The enzymatically generated Cer was organized in different ways depending on the initial LE/LO ratio. The action of SMase in Chol-poor monolayers led to the formation of Cer-enriched domains, while in Chol-rich monolayers it resulted in the incorporation of Cer in the LO phase and the formation of new Chol- and Cer-enriched domains. The following novel mechanism is proposed to provide an explanation for the favored action of SMase on interfaces that exhibit an LE-LO phase coexistence: the LO phase sequesters the product Cer causing its depletion from the more enzyme-susceptible LE phase, thus decreasing inhibition by the reaction product. Furthermore, LO domains function as a substrate reservoir by allowing a rapid exchange of the substrate from this phase to the SM-depleted LE phase.Fil: Ale, Elisa Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; ArgentinaFil: Maggio, Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Fanani, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentin

High Quality, Equity, and Assessment: An Analysis of Variables Impacting English Learner Standardized Science Test Performance and Implications for Construct Validity

In the United States, assessment is seen as a lever that can facilitate high-quality education. This study on English learners, students whose native language is not English, was based on data from eighth-grade English learners’ performance on science general and content-specific (physical, life, and earth science) standardized exams and an English language proficiency exam. The researchers utilized regression analysis to examine factors (i.e., socioeconomic status, home language, English language proficiency, and receptive and productive elements of language) that are predictive of English learner performance in general and content-specific science standardized assessments to identify implications for construct validity of high-stakes science assessments. The research question is as follows: What factors influence the performance of English learners on a standardized science assessment, including overall performance and content-specific domains? Three main findings emerged from this research study. First, this study confirms previous research indicating that socioeconomic status and English language proficiency are predictive of English learners’ achievement on content-based standardized tests. Second, this study adds to current research by providing evidence that productive language scores are the most significant predictors of English learner science achievement, in comparison to receptive language scores, overall English language proficiency scores, home language, and socioeconomic status. Third, this study adds to the body of evidence needed to challenge the validity of standardized science tests for English learner populations. The findings of this study challenge the construct validity of science content-based assessments for English learners, emphasizing the importance of productive language in academic performance