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- A 3D MOF with Cu20/Cu6 clusters: self-assembly, CO2 encapsulation, structural features, and magnetic propertiesPublication . Sliwa, Ewelina I.; Nesterov, Dmytro S.; Klak, Julia; Kirillov, Alexander M.; Smolenski, PiotrAbstract Molecular design of multicopper clusters has been of increasing importance in inorganic chemistry, biomedical science, and functional materials. Herein, two new copper compounds were self-assembled from copper(II) monofluoroacetate or trifluoroacetate, elemental copper, and 1,3,5-triaza-7-phosphaadamantane (PTA). The reaction starting from copper(II) monofluoroacetate yielded a tetranuclear cluster, [Cu4II(μ3-OH)2(μ-L)6(PTA=O)2] (1), where L is monofluoroacetate(1−) and PTA=O is the oxide of PTA. Formation of 1 involves the oxidation of PTA and the incorporation of μ3-OH– ligands. In contrast, a similar reaction with copper(II) trifluoroacetate produced a unique three-dimensional metal–organic framework (3D MOF), formulated as [{Cu20II(CO3)(μ3-O)2(μ3-OH)22(μ-L′)12}{Cu6I(μ3-PTA)6(CH3CN)12}]n·6n(L′)·3n(H2O)·2n(CH3CN) (2), where L′ is trifluoroacetate. It comprises Cu20 clusters, with an encapsulated carbonate anion fixed from atmospheric CO2, which are bridged by {Cu6I(PTA)6} units into a 3D MOF. Control experiments confirmed that carbonate originates from ambient CO2 rather than from added carbonate salts. Both 1 and 2 were fully characterized, and their magnetic properties were investigated, revealing dominant antiferromagnetic interactions within the Cu4 and Cu20 clusters, respectively. Density functional theory (DFT) calculations confirmed the antiferromagnetic ground spin state of 1 and disclosed the stability of the Cu20 core in 2. This work highlights the influence of fluorinated carboxylates and atmospheric conditions on the assembly and architecture of multicopper clusters, and extends their family to new examples.
- a-fractal function with variable parameters: an explicit representationPublication . Priyanka, T. M. C.; Serpa, Cristina; Gowrisankar, A.In this paper, new results on the alpha-fractal function with variable parameters are presented. The Weyl-Marchaud variable order fractional derivative of an alpha-fractal function with variable parameters is examined by imposing certain conditions on the scaling factors. Following the investigation of fractional derivative, the definite integral of the alpha-fractal function with variable parameters is evaluated for various intervals in the prescribed domain. Finally, an explicit structure for the alpha-fractal function is provided using the base q representation of numbers.
- Adenine tagged Mn-based coordination polymer for conversion of carbon dioxide to cyclic carbonates under atmospheric pressurePublication . Eskemech, Alehegn; Bhakhar, Rubi; Biswas, Pritam; Karmakar, Anirban; Krishnan, Venkata; Koner, Rik RaniAbstract Natural processes collectively balance the global carbon cycle, effectively controlling atmospheric carbon dioxide (CO2) levels. However, excessive CO2 emissions due to industrialization and population growth have disrupted natural processes by increasing the atmospheric CO2 concentration. To address this issue, CO2 capture and conversion have been implemented. Metal–organic frameworks (MOFs)/coordination polymers (CPs) with bioligands, such as amino acids and nucleobases, are receiving much interest. However, bio-MOFs are not much reported due to the lack of control over their coordination with metal ions. In this work, we have developed an adenine-tagged Mn-CP with dominant basic sites, [Mn(IPT2–)(Ade)(DMF)]n (IPT2– = isophthalate; Ade = adenine; DMF = N,N′-dimethylformamide). The analysis of isosteric heat (Qst) of CO2 adsorption supported the presence of strong interactions between CO2 and Mn-CP. Mn-CP demonstrated moderate to outstanding performance in coupling CO2 with smaller and larger epoxides at ambient pressure under neat conditions. The thermodynamic activation parameters indicate that Mn-CP operates through an associative mechanism (ΔS⧧ = −283.4 J mol−1 K−1), with a reduced kinetic barrier characterized by ΔH⧧ of 17.28 kJ mol–1 and Ea of 20.5 kJ mol–1. The catalytic efficiency of Mn-CP was particularly notable in the coupling reaction of epichlorohydrin and CO2, yielding 92% of the corresponding cyclic carbonate under atmospheric pressure.
- Advanced double-flush riveting for multistage forming toolsPublication . Silva, Carlos M. A.; Pragana, João P. M.; Sampaio, Rui F. V.; Bragança, Ivo M. F.; Martins, Paulo A. F.; Bragança, IvoThis paper presents a novel double-flush riveting process for creating lap joints in sheet metal parts. The process involves punching, forging, and shaving to produce countersunk holes with precise geometry, followed by compression of cylindrical rivets into the holes of two overlapped sheet parts to create form-closed mechanical interlocks. Experimental and numerical analyses examine the influence of the primary process parameters on interlock quality and required forming and destructive forces. The investigation is a step forward in joining technology by offering a simple alternative to welding, bonding, and mechanical joining, with seamless integration into multistage forming tools.
- Age dependent variation of the magnetic fabric of dike swarms and implications for the volcanic structure of ocean islands: the example of the Maio Island, Cabo Verde archipelagoPublication . Moreira, Mário; Mata, João; Madeira, José; Represas, Patricia; Martins, SofiaMagnetic fabric analysis of dikes is a powerful technique when assessing magma transfer processes. This study presents an integrated analysis combining magnetic susceptibility and anisotropy of magnetic susceptibility, magnetic mineralogy, geochemistry and new 40Ar/39 Ar dating of dikes intruding formations ranging from the Lower Cretaceous to the Miocene on the island of Maio, in the Cabo Verde archipelago. We show that the dikes, dated at approximate to 9.2 Ma, intruding the younger Miocene Casas Velhas formation, display a Ti-rich titanomagnetite composition, higher whole-rock TiO2 content and very high magnetic anisotropy. They are clearly distinguished from the dikes, ranging in age from approximate to 9.3 to 11.3 Ma, intruding older formations, which show a predominantly Ti-poor titanomagnetite composition with multiple magnetic phases, lower whole-rock TiO2 concentration, higher range of magnetic susceptibilities and very low anisotropy. Magnetic fabric is predominantly normal with no significant imbrication relative to the dike margins. Numerical analysis of fabric shows a dominant coaxiality between the magnetic lineation and the preferred orientation of opaques and phenocrystals suggesting that magnetic lineation is, therefore, the proxy of the magmatic flow axis orientation. Based on the orientation of the magnetic fabric, we infer that magmatic flow within the studied dikes is predominantly vertical. The differences observed between the younger dikes and all other dikes may be related to magma sourced from distinct magma chambers. One, probably shallow, underneath the Casas Velhas fm in the southwest of the island, which would explain the very high values of magnetic anisotropy and the inferred vertical flow, and another located in a central position in the island, responsible for the dikes intruding the older formations. The location of such magma reservoirs and the dikes ages suggest a hypothetical migration with age of the magmatic sources that fed the dikes from the central part of the island to the southwest region. The magnetic and mineralogical heterogeneities of the dikes intruding older Lower Cretaceous formations may also be a result of a wider age range of the intrusions.
- Analysis of integrated calcium looping alternatives in a cement plantPublication . Amorim, Ana; Filipe, Rui; Matos, Henrique A.Calcium looping is a promising post-combustion CO2 capturing technology, highly compatible with the cement industry, one of the major industrial sources of CO2 emissions. Limestone, a raw material for clinker, forms lime, a calcium looping adsorbent. Thus, it is possible to maximize the synergies between a cement plant and a calcium looping unit by establishing an integrated configuration. Nevertheless, the integration of calcium looping in cement plants has not yet been thoroughly studied. This study examines different integration alternatives, developing models for the preheater and calciner using Aspen Plus, validated with operational data, alongside an entrained-flow carbonator model considering adsorbent deactivation. By combining these models, six integrated configurations are proposed and compared with the tail-end calcium looping configuration. The integrated configurations show a reduction in fuel consumption and net energy consumption for the same CO2 avoided emissions. The most promising configuration was identified and a comparative techno-economic analysis was conducted.
- Anti-hypercholesterolemia effects of edible seaweed extracts and metabolomic changes in Hep-G2 and Caco-2 cell linesPublication . Coelho, Mariana; Pacheco, RitaHypercholesterolemia is a major risk for the development of cardiovascular diseases (CVDs), the main cause of mortality worldwide, and it is characterized by high levels of circulating cholesterol. The drugs currently available for hypercholesterolemia control have several side effects, so it is necessary to develop new effective and safer therapies. Seaweeds serve as sources of several bioactive compounds with claimed beneficial effects. Eisenia bicyclis (Aramé) and Porphyra tenera (Nori) are edible seaweeds that were previously recognized as rich in bioactive compounds. In the present study, we aim to evaluate the anti-hypercholesterolemia effect of these two seaweed extracts and their health potential. Both extracts, but more efficiently Aramé extract, have liver 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) inhibitory activity as well as the capability to reduce approximately 30% of cholesterol permeation through human Caco-2 cells by simulating the intestinal lining, which is a target for hypercholesterolemia treatments. An untargeted metabolomic assay on human intestinal Caco-2 and liver Hep-G2 cell lines exposed to Aramé and Nori extracts revealed changes in the cells’ metabolism, indicating the extracts’ health beneficial effects. The metabolic pathways affected by exposure to both extracts were associated with lipid metabolism, such as phospholipids, and fatty acid metabolism, amino acid pathways, cofactors, vitamins, and cellular respiration metabolism. The effects were more profound in Aramé-treated cells, but they were also observed in Nori-exposed cells. The metabolite modifications were associated with the protection against CVDs and other diseases and to the improvement of the cells’ oxidative stress tolerance. The results obtained for the anti-hypercholesterolemia properties, in addition to the revelation of the positive impact on cell metabolism, offer an important contribution for further evaluation of these seaweed extracts as functional foods or for CVD prevention.
- Anti-Hypercholesterolemia Effects of Edible Seaweed Extracts and Metabolomic Changes in Hep-G2 and Caco-2 Cell LinesPublication . Coelho, Mariana; Pacheco, Rita
- Application of 3D Modelling in The Field of Biomedical Applications for The Construction of Prosthetic FootPublication . Alvarinho, Júlia Inês Garrido; Domingues, Nuno Soares
- Aprender a ensinar: o percurso formativo visto por professores do 1.º e 2.º CEB recém diplomadosPublication . Valente, Bianor; Leite, Teresa; Maurício, Paulo; Ascenso, LaraEste estudo analisa as perspetivas de professores recém-diplomados do 1.º e do 2.º ciclo do ensino básico sobre a formação recebida no mestrado. A partir de entrevistas a 37 participantes, identificou-se um balanço ambivalente: apesar da satisfação global, apontam mais fragilidades do que pontos fortes. Entre os aspetos valorizados destacam--se as unidades curriculares de PES e de didática; entre as críticas, referem a escassa preparação para a prática, a repetição de conteúdos, a fraca articulação entre teoria e prática, o excesso de trabalhos e a falta de feedback. As sugestões de melhoria incluem o prolongamento dos estágios, uma maior aproximação à realidade escolar e a reorganização das estratégias formativas. Os resultados reforçam a necessidade de uma formação mais integrada, reflexiva e alinhada com as exigências da prática profissional.