Showing: 10 from total: 2524 publications
361.
Combining metal nanoclusters and carbon nanomaterials: Opportunities and challenges in advanced nanohybrids
Lopes, RCFG
; Rocha, BGM
; Macoas, EMS
; Marques, EF
; Martinho, JMG
in ADVANCES IN COLLOID AND INTERFACE SCIENCE, 2022, ISSN: 0001-8686, Volume: 304,
Article, Indexed in: crossref, scopus, wos
Abstract
The development of functional materials with uniquely advanced properties lies at the core of nanoscience and nanotechnology. From the myriad possible combinations of organic and/or inorganic blocks, hybrids combining metal nanoclusters and carbon nanomaterials have emerged as highly attractive colloidal materials for imaging, sensing (optical and electrochemical) and catalysis, among other applications. While the metal nanoclusters provide extraordinary luminescent and electronic properties, the carbon nanomaterials (of zero, one or two dimensions) convey versatility, as well as unique interfacial, electronic, thermal, optical, and mechanical properties, which altogether can be put to use for the desired application. Herein, we present an overview of the field, for experts and non-experts, encompassing the basic properties of the building blocks, a systematic view of the chemical preparation routes and physicochemical properties of the hybrids, and a critical analysis of their ongoing and emerging applications. Challenges and opportunities, including directions towards green chemistry approaches, are also discussed.
362.
Drug-Derived Surface-Active Ionic Liquids: A Cost-Effective Way To Expressively Increase the Blood-Stage Antimalarial Activity of Primaquine
Silva, AT
; Oliveira, IS
; Gomes, J
; Aguiar, L
; Fontinha, D
; Duarte, D
; Nogueira, F
; Prudencio, M
; Marques, EF
; Teixeira, C
; Ferraz, R
; Gomes, P
in CHEMMEDCHEM, 2022, ISSN: 1860-7179, Volume: 17,
Article, Indexed in: crossref, scopus, wos
Abstract
Inspired by previous disclosure of room-temperature ionic liquids derived from primaquine and cinnamic acids, which displayed slightly enhanced blood-stage activity compared to the parent drug, we have now combined this emblematic antimalarial with natural fatty acids. This affords surface-active ionic liquids whose liver-stage antiplasmodial activity is either retained or slightly enhanced, while revealing blood-stage antiplasmodial activity at least one order of magnitude higher than that of the parent compound. These findings open new perspectives towards the cost-effective recycling of classical drugs that are either shelved or in decline, and which is not limited to antimalarial agents.
363.
A critical assessment of the role of ionic surfactants in the exfoliation and stabilization of 2D nanosheets: The case of the transition metal dichalcogenides MoS2, WS2 and MoSe2
Abreu, B
; Almeida, B
; Ferreira, P
; Fernandes, RMF
; Fernandes, DM
; Marques, EF
in JOURNAL OF COLLOID AND INTERFACE SCIENCE, 2022, ISSN: 0021-9797, Volume: 626,
Article, Indexed in: crossref, scopus, unpaywall, wos
Abstract
Transition metal dichalcogenides (TMDs), like other two-dimensional layered materials beyond graphene, have gained enormous interest in recent years owing to their distinct electronic and optical properties, and potential applicability in areas such as sensing, nanoelectronics and catalysis. Surfactant -assisted exfoliation is commonly used to prepare aqueous dispersions of TMD nanosheets, but a clear picture of the TMD and surfactant features that influence the dispersion process is still lacking. In this work, we present a systematic study of the dispersibility of MoS2, WS2 and MoSe2 in aqueous medium using a cationic (cetyltrimethylammonium bromide, CTAB) and an anionic (sodium cholate, SC) dispersant, in a wide concentration range (seven orders of magnitude) and resorting to a carefully controlled sonication-centrifugation procedure. We present detailed, high precision dispersibility curves (concentration of dis-persed TMD versus concentration of surfactant used), together with zeta potential and pH measurements, allowing insight on the influence of the type of metal and chalcogen, surfactant charge and surfactant concentration, on the effectiveness of the exfoliation and stabilization. The metal (Mo vs. W) influences the dispersibility at low surfactant concentrations, while the chalcogen (S vs. Se) plays a more significant role as the surfactant concentration is increased, alongside the surfactant charge. Structural characterization by scanning electron microscopy (SEM), Raman spectroscopy and atomic force microscopy (AFM) shows that the methodology applied yields well-exfoliated nanosheets with controlled mean lateral dimension (asymptotic to 100 nm) and thickness (<= 5 layers). Finally, the type of ionic surfactant (cationic vs. anionic) and its concentration play a pivotal role in the profile of the dispersibility curves, leading us to propose two types of master curves with distinct regions of phase behavior.
364.
Citizen Science as a Pedagogical Tool in Chemistry Education: Students’ Attitudes and Teachers’ Perceptions
Araújo, JL
; Morais, C
; Paiva, JC
in Interdisciplinary Journal of Environmental and Science Education, 2022, Volume: 18,
Article, Indexed in: crossref
365.
Recycling of textile wastes, by acid hydrolysis, into new cellulosic raw materials
Costa, C
; Viana, A
; Silva, C
; Marques, EF
; Azoia, NG
in WASTE MANAGEMENT, 2022, ISSN: 0956-053X, Volume: 153,
Article, Indexed in: crossref, scopus, unpaywall, wos
Abstract
Chemical recycling can be used to separate fibers that are constituents of different types of fabrics. This type of process can be considered one of the most effective forms of recycling, given that a large part of fabrics is made up of fiber mixtures. As part of an innovative circular strategy, the main goal of this work was to study the conditions for extracting cellulose from mixed textile wastes by acid hydrolysis and further transform it into cellulose derivatives, thus contributing to reduce such wastes and expanding the possible sources of cellulose. Our work covers a wide range of textile wastes and addresses the main technical challenges of this recycling methodology. The percentage of recovered cellulose powder varies between 65 and 88%. To evaluate the feasibility of using the extracted cellulose as raw material to produce cellulose derivatives, two strategies were applied: etherification to obtain sodium carboxymethylcellulose (with degree of substituion between 0.27 and 0.61) and esterification, to obtain cellulose acetate (with degree of substituion of 2.59). The cellulose derivatives obtained are very useful as additives in the textile industry, and hence the concept and practice of a circular economy are promoted.
366.
Visitors come to experience science: towards a non-obtrusive evaluation method based on immersive virtual reality
Morais, C
; Moreira, L
; Teixeira, A
; Aguiar, T
; Coelho, A
; Pereira, V
; Jacinto, A
; Varzim, M
; Paiva, JC
; Rosa, M
in JCOM-JOURNAL OF SCIENCE COMMUNICATION, 2022, ISSN: 1824-2049, Volume: 21,
Article, Indexed in: crossref, handle, scopus, wos
Abstract
This paper focuses on developing and assessing a non-obtrusive and transformative method, based on virtual reality, to evaluate science communication projects in science centres. The method was tested using deep-sea cutting-edge scientific content. We applied a mixed design, with 72 adult participants randomly assigned to experimental conditions (with/without exhibition exposure). Results showed that the exhibition promoted a better understanding of science. The non-obtrusive measures on awareness and engagement were positively related with questions posed via questionnaire and interview. The study adds theoretical and empirical support to the design and implementation of non-obtrusive and transformative evaluation experiences in science exhibitions in science centres and museums.
367.
Science-Religion Dialogue in Education: Religion Teachers' Perceptions in a Roman-Catholic Context
Paiva, JC
; Rosa, M
; Moreira, JR
; Morais, C
; Moreira, L
in RESEARCH IN SCIENCE EDUCATION, 2022, ISSN: 0157-244X, Volume: 52,
Article, Indexed in: authenticus, crossref, handle, scopus, wos
Abstract
This paper examines the relationship between science and religion in the education system of Roman-Catholic Portuguese society. In particular, we explored perceptions of the relationship between science and religion for religious education teachers. We surveyed 198 Portuguese religious education teachers about how they view science and religion. The questionnaires' results revealed a number of similarities: religious education teachers are highly involved in religious practices and exposed to science; they perceived a compatibility between science and religion; and they have an openness to dialogue between both. They do not adhere to anti-scientific perspectives, but they simultaneously try to limit what can be explained by science. Thus, an interpretative view of dialogue and/or integration seems to best explain the perceptions of religious education teachers of the relationship between science and religion. These findings allow a space of discussion, enabling teachers to possibly foster the science-religion dialogue in their contexts of pedagogical activity.
368.
Thermodynamic properties of 2-mercapto-, 2,5-dimethyl- and 2-mercapto-5-methyl-1,3,4-thiadiazole
Silva, ALR
; Goncalves, JM
; Morais, VMF
; da Silva, MDMCR
in JOURNAL OF CHEMICAL THERMODYNAMICS, 2022, ISSN: 0021-9614, Volume: 165,
Article, Indexed in: crossref, scopus, wos
Abstract
The focus of this work is the establishment of energetic-structural correlations of compounds containing a pentagonal heterocyclic ring with different substituents, and consequent contribution on the assessment of their thermodynamic stability and a thorough insight on the thiol-thione tautomeric equilibrium. In this work we report an experimental and computational thermochemical study of three mercaptothiadiazoles: 2-mercapto-1,3,4-thiadiazole, 2-mercapto-5-methyl-1,3,4-thiadiazole and 2,5-dimethyl1,3,4-thiadiazole. The experimental data were determined mainly from calorimetric techniques and from effusion method. Thermochemical properties such as the enthalpies of formation, both in crystalline and gaseous phases, the enthalpies of fusion and of sublimation of each compound, as well as the Gibbs energies of formation were derived. Thus, the methyl-substituted thiadiazole is the more stable species in both gaseous and crystalline phases. In addition, quantum chemical calculations were carried out for those isolated molecules. This approach confirms the thione form as the predominant tautomer for the mercaptothiadiazoles. Finally, the activation energies of the tautomeric equilibrium of the mercaptothiadiazoles were calculated in the gas-phase, aqueous and dimethylsulfoxide solutions, showing that the thiol ? thione single hydrogen transfers are quite unfavourable reactions in gas phase and in a presence of polar solvents. (c) 2021 Elsevier Ltd.
369.
The game pentade: A design model proposal for games for education
Raposo, L
; Guerra, H
; Morais, C
; Coelho, A
in Handbook of Research on the Influence and Effectiveness of Gamification in Education, 2022, ISSN: 2327-1825,
Book Chapter, Indexed in: crossref, scopus, unpaywall
Abstract
<jats:p>The use of digital games as support tools for education has proven to be effective. To explore their potential, it is crucial to design them carefully. This chapter considers the design of games for education, where players cultivate their knowledge and practice their skills by multiplying numerous hindrances during gaming. Educational elements are integrated into the gameplay, which players acquire while playing. The game's effectiveness depends on the players' ability to form a cheerful and encouraging environment to continue playing while increasing their interest in gameplay and improving academic performance. Following a design-first development approach, an innovative proposal for this design is presented, adding a new dimension to the game's tetrad: learning dynamics. Benefiting from years of professional practice, this game pentad design framework fulfills the learning and user experience requirements while overcoming the design limitations of more conventional approaches not based on an educational purpose. </jats:p>
370.
No waves from surface knowledge: diving into the social representations of the deep sea
Morais, C
; Moreira, L
; Teixeira, AS
; Aguiar, T
in INTERNATIONAL JOURNAL OF SCIENCE EDUCATION PART B-COMMUNICATION AND PUBLIC ENGAGEMENT, 2022, ISSN: 2154-8455, Volume: 12,
Article, Indexed in: crossref, scopus, wos
Abstract
Recently, new data about deep-sea ecosystems has stirred scientific, economic, and ecological agendas, but little is known about the public’s perspectives of the deep sea. Our goal is to explore the public’s common sense knowledge of the deep sea, with a view to inform science communication efforts. Based on social representations theory, we investigated the relationship between the public’s meanings associated with the deep sea and psychosocial and positional variables, such as attitudes and education level, and reflected on the implications of the findings for science communication. The study was conducted in Portugal, a coastal, sea-connected country. The sample consisted of 315 adults from different age groups and social strata. Participants were asked to elicit and rank their thoughts about the deep sea using a ranked association technique and fill in questions about sociodemographic information, perceptions, and attitudes concerning the deep sea. Results showed that the social representations of the deep sea were structured as emotional versus rational views and as superficial ocean knowledge versus novel or unusual views. Moreover, results evinced a relationship between representations and psychosocial and positional variables. The gap between scientific and common sense knowledge was evident amongst participants with a low education level and low science engagement, whilst highly educated and science-engaged participants’ representations seemed to be narrowed by instrumental views on science. This research is significant to better directing science communication to increase well-informed public participation in decision-making related to deep sea management and other socio-scientific issues by responding to audience’s background knowledge.