Catalysis by Metal-Oxide Nanostructures

Funding Information: This work received support from Portuguese national funds (FCT/MCTES, Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through projects DOIs: 10.54499/LA/P/0008/2020, 10.54499/UIDP/50006/2020, 10.54499/UIDB/50006/2020. SACC also acknowledges FCT for the Scientific Employment Stimulus—Institutional Call (DOI 10.54499/CEECINST/00102/2018/CP1567/CT0026).publishersversionpublishe

Advances in Supported Nanoparticle Catalysts

Associate Laboratory for Green Chemistry- LAQV financed by national funds from FCT/MCTES (UIDP/5006/2020).publishersversionpublishe

Catalytic Oxidation of Hydrocarbons

SACC is grateful to Fundação para a Ciência e a Tecnologia (FCT), Portugal for Scientific Employment Stimulus-Institutional Call (DOI 10.54499/CEECINST/00102/2018/CP1567/CT0026) and to the Associate Laboratory for Green Chemistry-LAQV financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/5006/2020).publishersversionpublishe

Complex Visual Querying without SQL: Mashup in-memory data and persistent data

This dissertation has the intent of increasing the level of expressiveness of a visual interface that allows users to query data without resorting to textual query languages. Although it was in the 1970s that Relational Database Management Systems appeared, the standard way to interact with them remains to be through SQL, a textual query language. One of the main problems with these kinds of languages is that they require technical skills and knowledge of query language, syntax and domain schema. Consequently, database man- agement was considered only accessible to experienced users for a long time. In recent years, with the explosion of the Web, the volume of data available to everyone grew exponentially. This way, it became necessary to make data retrieval accessible not only to expert users but also to users without database knowledge. Visual Query Systems emerged in the late 1970s to hide the complexity of query languages behind a visual interface and improving the effec- tiveness of human-computer communication. Since then, many different approaches have been proposed and studied. The OutSystems platform provides a graphical query interface called Aggregates that allows its users to formulate queries through the manipulation of visual components. However, this tool does not yet support the same level of expressiveness as SQL. This dissertation aims at increasing the level of expressiveness of the Aggregates by propos- ing different solutions for the implementation of the IN and NOT IN clauses without compro- mising the global experience for any kind of user. In order to achieve this, an iterative devel- opment process was used, including the design, implementation and evaluation of prototypes. In this dissertation, we present a functional solution, integrated into the OutSystems platform. The results show that we were able to turn the filtering of persistent data by in-memory data very accessible to OutSystems Developers and also to regular Developers with no or very little experience using the OutSystems platform.Esta dissertação tem como objetivo aumentar o nível de expressividade de uma interface visual que permite aos seus utilizadores consultar dados sem recorrer a linguagens de consulta tex- tuais. Apesar de ter sido na década de 1970 que surgiram os Sistemas de Gestão de Bases de Dados Relacionais, a forma mais usual de interagir com esses sistemas continua a ser através de SQL, uma linguagem textual de consulta de dados. Um dos principais problemas da utilização deste tipo de linguagens é que requerem habili- tações técnicas e conhecimento sobre linguagens de consulta, sintaxes específicas e esquemas de domínio. Consequentemente, a gestão de bases de dados foi, durante muito tempo, consi- derada apenas acessível a utilizadores experientes. Recentemente, com a explosão da Web, a quantidade de dados disponíveis para toda a gente cresceu exponencialmente. Deste modo, tornou-se necessário tornar o acesso a esses dados possível tanto para utilizadores experientes como para utilizadores sem conhecimentos de bases de dados. Os Sistemas Gráficos de Con- sulta de Dados emergiram no final da década de 1970 com o objetivo de ocultar a complexidade das linguagens de consulta por detrás de uma interface visual e melhorar a eficácia da intera- ção pessoa-máquina. Desde então, muitas abordagens diferentes foram propostas e estudadas. A plataforma da OutSystems fornece uma interface gráfica de consulta chamada Aggregates que permite aos seus utilizadores formular consultas através da manipulação de componentes visuais. No entanto, esta ferramenta ainda não suporta o nível de expressividade do SQL. Esta dissertação visa, assim, aumentar o nível de expressividade dos Aggregates, propondo diferentes soluções para a implementação das cláusulas IN e NOT IN sem comprometer a experiência global para qualquer tipo de utilizador. Para tal, foi utilizado um processo de desen- volvimento iterativo, incluindo a concepção, implementação e avaliação de protótipos. Nesta dissertação apresentamos uma solução funcional, integrada na plataforma OutSystems. Os re- sultados mostram que fomos capazes de tornar a filtragem de dados persistentes por dados em memória muito acessível tanto para programadores OutSystems como para programadores regulares com nenhuma ou muito pouca experiência de uso com a plataforma OutSystems

Kinetics versus Thermodynamics

Thermodynamics must be favorable for the growth of carbon nanotubes (CNTs) and graphene to take place, but a kinetic study is required to find the operating mechanism. In fact, thermodynamics indicates whether a reaction is possible; however, the route prevailing is not necessarily the most thermodynamically favorable, but the fastest one. Detailed kinetic studies state that there are three alternative routes operating under different temperature and pressure rates. The modes and rates of diffusion of carbon (C) atoms and noble metals have been known since the 1930s, but proof of C bulk diffusion operating in CNT growth came from detailed kinetic studies performed in the early 1970s, when reversible versus irreversible C formation was discussed with examples. The reason for interstitial C bulk diffusion in transition metals is evidenced based on the values of covalent radius. The reason for operating under steady-state conditions (linearity of the weight versus time) when searching for the operating mechanism is discussed herein. The steady-state C formation process operates sometimes with two different solid phases at each side of the catalyst particle (e.g., Ni and Ni3C), with thicknesses proportional to 1/D of the respective C bulk diffusivities when the carbon bulk diffusion step is the rate-determining one.publishersversionpublishe

Carbon formation at high temperatures (550–1400 ◦c): Kinetics, alternative mechanisms and growth modes

UIDB/50006/2020This Note aims at clarifying the alternative mechanisms of carbon formation from gases at temperatures above 550 ◦C. Both the growth of carbon nanotubes (CNTs) by a hybrid route, and of graphene layers deposition by a pyrolytic route are analyzed: The transition had no influence in apparent kinetics, but the carbon structure was totally different. The transition temperature from hybrid to pyrolytic growth varies with the gas pressure: Higher temperature transition was possible using lower active gas pressures. The rate-determining step concept is essential to understanding the behavior. In catalytic and hybrid carbon formation, the slower step controls and determines kinetics. In the pyrolytic region, the faster step dominates, and carbon bulk diffusion is blocked: Layers of graphene cover the external catalyst surface. It is easier to optimize CNTs growth (rate, shape, properties) knowing the details of the alternative mechanisms operating.publishersversionpublishe

Kinetics of carbon nanotubes and graphene growth on iron and steel: Evidencing the mechanisms of carbon formation

This work was supported by national funds through FCT-Fundacao para a Ciencia e a Tecnologia, I.P., under the Scientific Employment Stimulus-Institutional Call Partially supported by the Associate Laboratory for Green Chemistry-LAQV, financed by national funds from FCT/MCTES (UIDB/50006/2020).Carbon formation on steel has recently become an active research area with several important applications, using either carbon nanotubes (CNTs) or graphene structures. The production of vertically aligned CNT (VACNT) forests with combined metals has been explored with important results. Detailed kinetics is the best approach to understand a mechanism. The growth behavior seems complex but can be simplified through the knowledge of the three more common alternative reaction mechanisms/routes. The time required to optimize the production and properties might be reduced. The mechanistic proposal reported in 1971 was better explained recently. The volcano shape Arrhenius plot reported is observed only when Fe, Co, and Ni are used as reaction catalysts. Other metals are catalytically active at higher temperatures, following a different route, which does not require surface catalysis decomposition of the reactive gas. C2H2 and low olefins react well, but CH4 is not reactive via this surface catalysis route. Optimizing production of CNTs, research work is usually based on previous experience, but solid-state science-based studies are available.publishersversionpublishe

Gum-based nanocomposites for the removal of metals and dyes from waste water

Funding Information: Open access funding provided by FCT|FCCN (b-on). M.B.T acknowledges support from HEC (Higher Education Commission) of Pakistan. S.A.C.C. acknowledges support from FCT/MCTES (Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through projects UIDB/50006/2020 and UIDP/50006/2020 and for the Scientific Employment Stimulus—Institutional Call (CEECINST/00102/2018). Publisher Copyright: © 2023, The Author(s).The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved.publishersversionpublishe

The Ca2+-ATPase inhibition potential of gold (I, III) compounds

The therapeutic applications of gold are well-known for many centuries. The most used gold compounds contain Au(I). Herein, we report, for the first time, the ability of four Au(I) and Au(III) complexes, namely dichloro (2-pyridinecarboxylate) Au(III) (abbreviated as1), chlorotrimethylphosphine Au(I) (2), 1,3-bis(2,6-diisopropylphenyl) imidazole-2-ylidene Au(I) chloride (3), and chlorotriphenylphosphine Au(I) (4), to affect the sarcoplasmic reticulum (SR) Ca2+-ATPase activity. The tested gold compounds strongly inhibit the Ca2+-ATPase activity with different effects, being Au(I) compounds2and4the strongest, with half maximal inhibitory concentration (IC50) values of 0.8 and 0.9 mu M, respectively. For Au(III) compound1and Au(I) compound3, higher IC(50)values are found (4.5 mu M and 16.3 mu M, respectively). The type of enzymatic inhibition is also different, with gold compounds1and2showing a non-competitive inhibition regarding the native substrate MgATP, whereas for Au compounds3and4, a mixed type of inhibition is observed. Our data reveal, for the first time, Au(I) compounds with powerful inhibitory capacity towards SR Ca(2+)ATPase function. These results also show, unprecedently, that Au (III) and Au(I) compounds can act as P-type ATPase inhibitors, unveiling a potential application of these complexes.FCT: UIDB/04326/2020/ UIDB/50006/2020info:eu-repo/semantics/publishedVersio