Fizik Bölümü / Department of Physics

Permanent URI for this collectionhttps://hdl.handle.net/11413/6785

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Open Access
Semi-Quantitative Chemometric Models for Characterization of Mixtures of Sugars Using Infrared Spectral Data
(Elsevier B.V., 2024) Brito, Anna Luiza B.; Cardoso, Inês F.; Viegas, Luís P.; FAUSTO, RUI
Sugars (saccharides) are sweet-tasting carbohydrates that are abundant in foods and play very important roles in living organisms, particularly as sources and stores of energy, and as structural elements in cellular membranes. They are desirable therapeutic targets, as they participate in multiple metabolic processes as fundamental elements. However, the physicochemical characterization of sugars is a challenging task, mostly due to the structural similarity shared by the large diversity of compounds of this family. The need for fast, accurate enough, and cost-effective analytical methods for these substances is of extreme relevance, in particular because of the recently increasing importance of carbohydrates in Medicine and food industry. With this in view, this work focused on the development of chemometric models for semi-quantitative analysis of samples of different types of sugars (glucose, galactose, mannitol, sorbose and fructose) using infrared spectra as data, as an example of application of a novel approach, where the Principal Component Analysis (PCA) score plots are used to estimate the composition (weight-%) of the mixtures of the sugars. In these plots, polygonal geometric shapes emerge in the vectorial space of the most significant principal components, that allow grouping different types of samples on the vertices, edges, faces and interior of the polygons according to the composition of the samples. This approach was applied successfully to mixtures of up to 5 sugars and shown to appropriately extract the compositional information from the hyper-redundant complex spectral data. Thought the method has been applied here to a specific problem, it shall be considered as a general procedure for the semi-quantitative analysis of other types of mixtures and applicable to other types of data reflecting their composition. In fact, the methodology appears as an efficient tool to solve three main general problems: (i) use hyper-redundant (in variables) data, as spectral information, directly and with minimum pre-treatment, to evaluate semi-quantitatively the composition of mixtures; (ii) do this for systems which produce data that can be considered rather similar; and (iii) do it for a number of substances present in the mixtures that might be greater than that usually considered in chemistry, which in general is limited to 3 components. In addition, this work also demonstrates that, similarly to the developed analysis based on the PCA score plots, the Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS) chemometric method can also be used successfully for the qualitative (when used without any previous knowledge of the components present in the samples) or semi-quantitative (when the pure components spectral profiles are provided as references) analyses of mixtures of (at least) up to 5 distinct sugars.
Open Access
Reversal in Solvatochromism, Photochromism and Thermochromism in a New Bis-azo Dye Based on Naphthalen-1-amine
(Elsevier B.V., 2024) Sıdır, İsa; Kara, Yunus Emre; Sıdır, Yadigar Gülseven; Berber, Halil; FAUSTO, RUI
A novel bis-azo dye, 4,4′-((1E,1′E)-(oxybis(4,1-phenylene))bis(diazene-2,1-diyl))bis(naphthalen-1-amine) (abbreviated as 4odna) was synthesized and characterized by IR and 1H, 13C and 2D COSY-NMR spectroscopies, and mass spectrometry. Optical properties were evaluated using UV–vis absorption spectroscopy. The observed solvatochromism was ascribed to the presence of different azo or/and hydrazone forms in solution. The azo forms show both positive and negative solvatochromism, with the reversal occurring for solvents with ET(30) ∼45 kcal mol−1, while the hydrazone tautomer shows negative solvatochromism. Application of the multiparametric Catalán and Kamlet-Taft linear solvation energy models allowed to evaluate the dependence of the solvatochromism exhibited by 4odna on the hydrogen bond donating (HBD) and accepting (HBA) abilities of the solvent, as well as on their dipolarity (SdP) and polarizability (SP). Upon UV (λ = 311 nm) irradiation at room temperature, the compound was found to exhibit similar photochromic behavior in the polar-protic solvents methanol and ethanol, which is distinct from that observed in the polar-aprotic solvents dichloromethane, chloroform and chlorobenzene, with the hydrazone tautomer being photoconverted into the azo tautomer in the first group of solvents and vice-versa in the second group. In acetone, UV irradiation extensively transforms the compound into species with no absorption in the visible range, leading to fast discoloration of the solution. Temperature dependence of the color of the solutions of 4odna in ethanol and chlorobenzene was also evaluated, and reversible thermochromic behavior was observed in the first solvent. In chlorobenzene, no thermochromism was observed, but a change of color of the solution was promptly induced by the UV–vis broadband source beam of the spectrometer when the absorbance spectrum of the solution was being recorded at T = 115 °C, which demonstrates that the azo forms of 4odna undergo easy phototransformation into the hydrazone forms in this solvent at high temperature. © 2023 Elsevier B.V.
Open Access
In Silico Evaluation of ERQ Bioactive Tripeptide as an Anticancer Agent and an Inhibitor of SARS-CoV-2 Enzymes
(Istanbul University Press, 2024) Yılmaz, Gözde; Çelik, Sefa; Özel, Ayşen Erbölükbaş; AKYÜZ, SEVİM
Objective: Short peptides play a significant role in exploring drugs with higher selectivity and fewer side effects in cancer and COVID-19 therapies. This study evaluated the anticancer and anti-COVID-19 activities of Glu-Arg-Gln (ERQ) tripeptide for the first time. To discover the potentiality of the tripeptide as an anticancer and as a SARS-CoV-2 inhibitor, molecular docking analysis of ERQ tripeptide with DNA (PDB ID: 1BNA) and a variety of SARS-CoV-2 enzymes, namely. Main protease (PDB IDs: 6M03, 6LU7) and Spike glycoprotein (PDB ID: 6VXX) were performed. Materials and Methods: To determine the binding efficiency of ERQ to target DNA and proteins, molecular docking processes were carried out using the Autodock Vina program. The sorts of bonds and interacting residues in ERQ/DNA and ERQ/protein complexes were determined. Results: Molecular docking simulations of ERQ tripeptide against 1BNA, 6M03, 6LU7, and 6VXX were performed, and the interactions between the docked ligand and target residues were determined. The binding mechanisms of ERQ with the receptors were clarified. The binding affinities of ERQ towards the targets were predicted to be between -6.3 and -6.7 kcal/mol. ERQ showed the highest binding affinity to Spike glycoprotein (6VXX), with an estimated binding energy of -6.7 kcal/mol. Conclusion: Molecular docking simulations revealed the potential of ERQ tripeptide as an anticancer and anti-COVID-19 agent. High binding affinity against 1BNA (-6.4 kcal/mol), 6M03 (-6.3 kcal/mol), 6LU7 (-6.6 kcal/mol), and 6VXX (-6.7 kcal/mol) indicated that ERQ could be an excellent new natural therapy for the treatment of cancer and COVID-19. © 2024 Istanbul University Press. All rights reserved.
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Revisiting Structural, Vibrational, and Photochemical Data of Matrix-Isolated Simple Hydantoins — Common Features and Substituent Effects
(American Institute of Physics, 2024) FAUSTO, RUI; ILDIZ, GÜLCE ÖĞRÜÇ; Nogueira, Bernardo A.
Characteristic features of the structure (geometries, electronic structures), vibrational spectra (infrared), and photochemistry of a series of simple hydantoins (parent hydantoin, 1-methylhydantoin, 5-methylhydantoin, and 5-acetic acid hydantoin), and effects of substituent on these properties, are reviewed in a comparative comprehensive perspective taken as a basis the low-temperature matrix isolation infrared spectroscopy and electronic structure quantum chemistry data we have reported before for the individual compounds. It is shown that the hydantoin moiety shows a general tendency towards planarity (or quasi-planarity), mostly determined by the π-electron delocalization in the system, in which the two nitrogen atoms are extensively involved and, in the molecules studied, also counts with the involvement of the π-type orbitals of the -C5H2- or -C5HR- (with R ˭ CH3 or CH2COOH in 5-methylhydantoin and 5-acetic acid hydantoin, respectively) fragment (hyperconjugation). The geometries and charge density analyses of the compounds also show that the main electronic effects in the hydantoin ring are the N-to-(C ˭ O) π-electron donation, and the σ system back-donation from the σ-lone electron pairs of the oxygen atoms to the ring. The frequencies of the bands observed in the matrix-isolation infrared spectra (Ar; 10 K) of the different compounds that are assigned to the carbonyl and amine fragments are discussed comparatively, and substituent effects are assessed. Finally, the UV-induced (λ = 320 nm) photochemistry of the hydantoins is shown to share a common pattern, leading to the concerted extrusion of isocyanic acid and carbon monoxide, accompanied by an imine derivative that depends upon the specific hydantoin reactant. An additional photofragmentation pathway, most probably involving nitrene intermediacy, also takes place for 1-methylhydantoin, indicating a specific effect of the substitution at position 1 of the hydantoin ring on the photofragmentation of hydantoins. © 2024 Author(s).
Open Access
A New Azide-Bridged Polymeric Manganese (III) Schiff Base Complex with an Allylamine-Derived Ligand: Structural Characterization and Activity Spectra
(MDPI, 2024) Talebi, Aynaz; Salehi, Mehdi; Jesus, A. J. Lopes; Kubicki, Maciej; FAUSTO, RUI; Golbedaghi, Reza
This paper reports the synthesis and structural characterization of a novel azide-bridged polymeric manganese (III) Schiff base complex, using 2-((allylimino)methyl)-6-ethoxyphenol as a ligand. The crystal structure of the synthesized compound, elucidated by single-crystal X-ray diffraction analysis, indicates that it crystallizes in the monoclinic space group P21/c. The complex is found to display an octahedral geometry in which the central manganese Mn(III) coordinates with two bidentate donor Schiff base ligands via oxygen and nitrogen atoms. In addition, the metallic centers are linked together to form a one-dimensional chain bridged by end-to-end azide ligands. To offer a more thorough characterization of the synthesized compound, the study incorporates experimental data from FT-IR, UV-Vis, and cyclic voltammetry, alongside computational results from Hirshfeld surface analysis and DFT calculations conducted for both the ligand and complex. The computational analyses provided valuable insights into the intrachain and interchain interactions within the crystal structure, clarified the conformational characteristics of the isolated ligand molecule, and aided in the interpretation of the experimental IR spectra. Furthermore, an assessment of the compound’s drug-like properties was conducted using activity spectra for substances (PASS) predictions, revealing potential pharmacological activities. © 2024 by the authors.
Open Access
Solid-Liquid Phase Equilibrium of the n-Nonane plus n-Undecane System for Low-Temperature Thermal Energy Storage
(Springer/Plenum Publishers, 2024) Sequeira, Maria C. M.; Nikitin, Timur; Caetano, Fernando J. P.; Diogo, Herminio P.; Fareleira, Joao M. N. A.; FAUSTO, RUI
The current article presents an exploration of the solid-liquid phase diagram for a binary system comprising n-alkanes with an odd number of carbon atoms, specifically n-nonane (n-C-9) and n-undecane (n-C-11). This binary system exhibits promising characteristics for application as a phase change material (PCM) in low-temperature thermal energy storage (TES), due to the fusion temperatures of the individual components, thereby motivating an in-depth investigation of the solid-liquid phase diagram of their mixtures. The n-nonane (n-C-9) + n-undecane (n-C-11) solid-liquid phase equilibrium study herein reported includes the construction of the phase diagram using Differential Scanning Calorimetry (DSC) data, complemented with Hot-Stage Microscopy (HSM) and low-temperature Raman Spectroscopy results. From the DSC analysis, both the temperature and the enthalpy of solid-solid and solid-liquid transitions were obtained. The binary system n-C-9 + n-C-11 has evidenced a congruent melting solid solution at low temperatures. In particular, the blend with a molar composition x(undecane) = 0.10 shows to be a congruent melting solid solution with a melting point at 215.84 K and an enthalpy of fusion of 13.6 kJmol(-1). For this reason, this system has confirmed the initial signs to be a candidate with good potential to be applied as a PCM in low-temperature TES applications. This work aims not only to contribute to gather information on the solid-liquid phase equilibrium on the system n-C-9 + n-C-11, which presently are not available in the literature, but especially to obtain essential and practical information on the possibility to use this system as PCM at low temperatures. The solid-liquid phase diagram of the system n-C-9 + n-C-11 is being published for the first time, as far as the authors are aware.
Open Access
Experimental Characterization and Finite Element Investigation of SiO2 Nanoparticles Reinforced Dental Resin Composite
(Nature Portfolio, 2024) Jaleh, Babak; Kashfi, Mohammad; Mohazzab, Behnaz Feizi; Niaee, Morteza Shakhsi; Vafaee, Fariborz; Fakhri, Parisa; Golbedaghi, Reza; FAUSTO, RUI
In this study, a commercial dental resin was reinforced by SiO2 nanoparticles (NPs) with different concentrations to enhance its mechanical functionality. The material characterization and finite element analysis (FEA) have been performed to evaluate the mechanical properties. Wedge indentation and 3-point bending tests were conducted to assess the mechanical behavior of the prepared nanocomposites. The results revealed that the optimal content of NPs was achieved at 1% SiO2, resulting in a 35% increase in the indentation reaction force. Therefore, the sample containing 1% SiO2 NPs was considered for further tests. The morphology of selected sample was examined using field emission scanning electron microscopy (FE-SEM), revealing the homogeneous dispersion of SiO2 NPs with minimal agglomeration. X-ray diffraction (XRD) was employed to investigate the crystalline structure of the selected sample, indicating no change in the dental resin state upon adding SiO2 NPs. In the second part of the study, a novel approach called iterative FEA, supported by the experiment wedge indentation test, was used to determine the mechanical properties of the 1% SiO2-dental resin. Subsequently, the accurately determined material properties were assigned to a dental crown model to virtually investigate its behavior under oblique loading. The virtual test results demonstrated that most microcracks initiated from the top of the crown and extended through its thickness.
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Optical and Electric Properties of the Organic-Inorganic Hybrid bis(2-amino-5-picolinium) Tetrachlorocobaltate(II) [(C6H9N2)2CoCl4]
(Elsevier, 2024) Ghoudi, A.; Chaabane I.; Naouari, Raja; Aydi A.; Oueslati A.; Dhahri E.; Costa B.F.O.; Nikitin T.; Paixão J.A.; FAUSTO, RUI
Organic-inorganic hybrid materials have garnered considerable interest due to their unique physical and chemical properties, enabling their use in diverse applications. This study explores the synthesis and characterization of the organic-inorganic hybrid compound (C6H9N2)2CoCl4. The compound was successfully synthesized via the slow evaporation method at room temperature. The X-ray diffraction on a single crystal indicated a monoclinic structure in the P21/c space group. Various analytical techniques were employed to ensure the material's high purity and to investigate its properties. Powder X-ray diffraction and SEM/EDX analysis confirmed the compound's crystalline structure and elemental composition. Raman spectroscopy provided insights into the vibrational characteristics. In contrast, UV-visible absorption and luminescence spectroscopy were used to explore its optical properties, indicating its potential as a semiconductor. The electrical and dielectric properties were studied using complex impedance spectroscopy (CIS), revealing significant frequency and temperature dependence. Additionally, Kohlrausch-Williams-Watts analysis was employed to examine the electric modulus, further elucidating the compound's non-Debye behavior. These methods collectively demonstrate the compound's potential applications in electronic and optical devices.
Open Access
Indigo Carmine Binding to Cu(II) in Aqueous Solution and Solid State: Full Structural Characterization Using NMR, FTIR and UV/Vis Spectroscopies and DFT Calculations
(MDPI, 2024) Braz, Sofia; Justino, Licinia L. G.; Ramos, M. Luisa; FAUSTO, RUI
The food industry uses indigo carmine (IC) extensively as a blue colorant to make processed food for young children and the general population more attractive. Given that IC can act as a ligand, this raises concerns about its interactions with essential metal ions in the human body. In view of this interest, in the present investigation, the copper(II)/indigo carmine system was thoroughly investigated in aqueous solution and in the solid state, and the detailed structural characterization of the complexes formed between copper(II) and the ligand was performed using spectroscopic methods, complemented with DFT and TD-DFT calculations. NMR and UV/Vis absorption spectroscopy studies of the ligand in the presence of copper(II) show changes that clearly reveal strong complexation. The results point to the formation of complexes of 1:1, 1:2 and 2:1 Cu(II)/IC stoichiometry in aqueous solution, favored in the pH range 6-10 and stable over time. DFT calculations indicate that the coordination of the ligand to the metal occurs through the adjacent carbonyl and amine groups and that the 1:1 and the 2:1 complexes have distorted tetrahedral metal centers, while the 1:2 structure is five-coordinate with a square pyramidal geometry. FTIR results, together with EDS data and DFT calculations, established that the complex obtained in the solid state likely consists of a polymeric arrangement involving repetition of the 1:2 complex unit. These results are relevant in the context of the study of the toxicity of IC and provide crucial data for future studies of its physiological effects. Although the general population does not normally exceed the maximum recommended daily intake, young children are highly exposed to products containing IC and can easily exceed the recommended dose. It is, therefore, extremely important to understand the interactions between the dye and the various metal ions present in the human body, copper(II) being one of the most relevant due to its essential nature and, as shown in this article, the high stability of the complexes it forms with IC at physiological pH.
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The ROY Family's Growing Palette: Insights Into Recent Compound Additions and Color Range Expansion - A Short Review
(Elsevier, 2024) Nogueira, Bernardo A.; FAUSTO, RUI
The ROY (systematic name: 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophene-carbonitrile) molecule family stands as the most renowned group of color polymorphic organic compounds. This article offers a concise overview of the main structural characteristics of the 13 known polymorphs of ROY, systematizing their diverse colors in a context where recent data (2022-2024) obtained for novel members of the family are also taken into account, in particular information extracted from our own studies on AcROY, ROY-ol and ROY-CAM. The new findings have extended the spectrum of ROY-based polymorphs' colors to include burgundy and, notably, green tones.
Open Access
Photochemical Generation and Characterization of C-Aminophenyl-Nitrilimines: Insights on Their Bond-Shift Isomers by Matrix-Isolation IR Spectroscopy and Density Functional Theory Calculations
(MDPI, 2024) Jesus, A. J. Lopes; Nunes, Claudio M.; Ferreira, Gil A.; Keyvan, Kiarash; FAUSTO, RUI
The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH substitution, here we extended this investigation to explore the effect of the NH2 substitution. For this purpose, C-(4-aminophenyl)- and C-(3-aminophenyl)-nitrilimines were photogenerated in an argon matrix at 15 K by narrowband UV-light irradiation (lambda = 230 nm) of 5-(4-aminophenyl)- and 5-(3-aminophenyl)-tetrazole, respectively. The produced nitrilimines were further photoisomerized to carbodiimides via 1H-diazirines by irradiations at longer wavelengths (lambda = 380 or 330 nm). Combining IR spectroscopic measurements and DFT calculations, it was found that the para-NH2-substituted nitrilimine exists as a single isomeric structure with a predominant allenic character. In contrast, the meta-NH2-substituted nitrilimine coexists as two bond-shift isomers characterized by propargylic and allenic structures. To gain further understanding of the effects of phenyl substitution on the bond-shift isomerism of the nitrilimine fragment, we compared geometric and charge distribution data derived from theoretical calculations performed for C-phenyl-nitrilimine with those performed for the derivatives resulting from NH2 (electron-donating group) and NO2 (electron-withdrawing group) phenyl substitutions.
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Molecular Docking and Molecular Dynamics Studies of Glu-Glu-Arg, Glu-Pro-Arg, and Pro-Arg-Pro Tripeptides to Reveal Their Anticancer and Antiviral Potentials
(Wiley - VCH Verlag GmbH, 2024) Yılmaz, Gözde; Çelik, Sefa; Özel, Ayşen Erbölükbaş; AKYÜZ, SEVİM
Bioactive peptides have been emerging as drug candidates with increasing importance in the last few decades. In this study, to evaluate the anticancer and antiviral properties of EER (Glu-Glu-Arg), EPR (Glu-Pro-Arg), and PRP (Pro-Arg-Pro) tripeptides, firstly their conformation preferences were searched, and the most stable optimized structure of each tripeptide was determined, using the molecular mechanics force field (MMFF) method and the Spartan06 program. Afterwards, each tripeptide was docked to SARS-CoV-2 spike protein receptor-binding domain (6M0J), SARS-CoV-2 main protease (6M03, 6LU7), spike glycoprotein (6VXX), DNA (1BNA), integrins (4WK0, 3ZDX, 1JV2) and epidermal growth factor receptor tyrosine kinase (4HJO). Moreover, molecular dynamics (MD) simulations were performed to validate the stability of the EER, EPR and PRP tripeptides docked to SARS-CoV-2 main protease, MPro (6M03) and epidermal growth factor receptor tyrosine kinase (4HJO) within 100 ns time scale and ligand-receptor interactions were evaluated. The metrics root-mean-square deviation, root-mean-square fluctuation, intermolecular hydrogen bonding, and radius of gyration revealed that the EER, EPR, and PRP tripeptides form energetically stable complexes with the target proteins. The binding free energies were calculated by the combination of Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) methods (MM/PB(GB)SA). Principal Component Analysis on MD data was performed to evaluate the energy and structural information of the tripeptide-protein complexes. Additionally, in-silico structure-based pharmacological predictions were made and the anticancer and antibacterial activities of the tripeptides were predicted.
Open Access
Results on Molecular Spectroscopy
(Elsevier, 2024) FAUSTO, RUI
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Preface "Molecular Structure and Mechanisms of Action of Antioxidants"
(Elsevier, 2024) ILDIZ, GÜLCE ÖĞRÜÇ; de Azevedo Jr, Walter F.; FAUSTO, RUI
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4-Hydroxyquinolin-2(1H)-One Isolated in Cryogenic Argon and Xenon Matrices: Tautomers and Photochemistry
(Elsevier, 2024) Secrieru, A.; Lopes, S.; Nikitin, T.; Cristiano, Maria L. S.; FAUSTO, RUI
4-Hydroxyquinolin-2(1H)-one (4HQ2O) was synthesized, isolated in cryogenic matrices (argon and xenon), and studied by infrared spectroscopy. Quantum chemical calculations carried out at the DFT(B3LYP)/6-311++G (3df,3pd) level of theory were used to determine the conformational and tautomeric properties of the molecule. Two tautomeric forms were identified in the as-deposited matrices with the help of the theoretical data. To investigate the photochemistry of the compound, in situ broadband ultraviolet (lambda > 283 nm) irradiation of the asdeposited argon matrix was performed. This irradiation led to the generation of an additional tautomer, together with the products of fragmentation of the heterocyclic ring of the molecule, specifically isocyanic acid and carbon monoxide. Photoproducts such as 1,3-dihydro-2H-indol-2-one and cyclohepta-1,2,4,6-tetraene were also observed in the photolyzed argon matrix. A comprehensive assignment of the infrared spectra of all the species observed experimentally is presented.
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Hydrogen Tunneling Exhibiting Unexpectedly Small Primary Kinetic Isotope Effects
(Wiley - VCH Verlag GmbH, 2024) Roque, Jose P. L.; Nunes, Claudio M.; Schreiner, Peter R.; FAUSTO, RUI
Probing quantum mechanical tunneling (QMT) in chemical reactions is crucial to understanding and developing new transformations. Primary H/D kinetic isotopic effects (KIEs) beyond the semiclassical maximum values of 7–10 (room temperature) are commonly used to assess substantial QMT contributions in one-step hydrogen transfer reactions, because of the much greater QMT probability of protium vs. deuterium. Nevertheless, we report here the discovery of a reaction model occurring exclusively by H-atom QMT with residual primary H/D KIEs. 2-Hydroxyphenylnitrene, generated in N2 matrix, was found to isomerize to an imino-ketone via sequential (domino) QMT involving anti to syn OH-rotamerization (rate determining step) and [1,4]-H shift reactions. These sequential QMT transformations were also observed in the OD-deuterated sample, and unexpected primary H/D KIEs between 3 and 4 were measured at 3 to 20 K. Analogous residual primary H/D KIEs were found in the anti to syn OH-rotamerization QMT of 2-cyanophenol in a N2 matrix. Evidence strongly indicates that these intriguing isotope-insensitive QMT reactivities arise due to the solvation effects of the N2 matrix medium, putatively through coupling with the moving H/D tunneling particle. Should a similar scenario be extrapolated to conventional solution conditions, then QMT may have been overlooked in many chemical reactions.
Open Access
Recycling Ophthalmic Lens Wastewater in a Circular Economy Context: A Case Study with Microalgae Integration
(MDPI, 2024) FAUSTO, RUI
Water pollution poses a global threat to ecosystems and human health and is driven by the presence of various contaminants in wastewater, including nano- and microplastics. Despite the magnitude of this problem, the majority of global wastewater is released untreated into water bodies. To combat this issue, a multi-strategy approach is needed. This study explores a circular economy-based solution for treating emerging pollutants, particularly wastewater from ophthalmic spectacle lens production. Our approach integrates solid waste materials into polymeric and cement matrices while also utilising wastewater for microalgae cultivation. This innovative strategy focuses on biomass generation and economic valorisation. By adopting a circular economy model, we aim to transform environmental pollutants from wastewater into valuable organic products. A key component of our approach is the utilisation of microalgae, specifically Nannochloropsis sp., known for its high lipid content and resilience. This microalgae species serves as a promising biobased feedstock, supporting the production of innovative biobased products, such as biopolymers, for ophthalmic lens manufacturing. Our interdisciplinary approach combines microalgae technology, analytical chemistry, cement production, and polymer processing to develop a sustainable circular economy model that not only addresses environmental concerns, but also offers economic benefits. This study underscores the potential of harnessing high-value products from waste streams and underscores the importance of circular economy principles in tackling pollution and resource challenges.
Open Access
Solid-Liquid Phase Equilibrium: Alkane Systems for Low-Temperature Energy Storage
(Springer/Plenum Publishers, 2024) Sequeira, Maria C. M.; Nogueira, Bernardo A.; Caetano, Fernando J. P.; Diogo, Herminio P.; Fareleira, Joao M. N. A.; FAUSTO, RUI
The thermal characterization of two binary systems of n-alkanes that can be used as Phase Change Materials (PCMs) for thermal energy storage at low temperatures is reported in this work. The construction of the solid-liquid binary phase diagrams was achieved using differential scanning calorimetry (DSC) and Raman spectroscopy. The solidus and liquidus equilibrium temperatures were determined using DSC for thirty-nine different samples, three for the pure n-alkanes and the remaining for binary mixtures at selected molar compositions and used to acquire the corresponding solid-liquid phase diagrams. The two binary systems of n-octane/n-decane (C8/C10) and n-decane/n-dodecane (C10/C12) are characterized by a eutectic behavior at low temperatures. The eutectic temperature for the system C8/C10 was found at 211.95 K and the eutectic composition appeared at the molar fraction xoctane = 0.87. For the system C10/C12, the eutectic temperature was found at 237.85 K, and the eutectic composition appeared for the molar fraction xdecane = 0.78. This work aims to fulfill the lack of available data in the existing literature, considering the potential application of these systems for low-temperature thermal energy storage. Raman spectroscopy was used to complement the DSC data for the construction of the solid-liquid phase equilibrium diagrams, enabling the identification of the solid and liquid phases of the system. Additionally, the liquidus curve of the phase diagram was successfully described using a modified freezing point depression curve as fitting equation, the absolute root mean square deviation for the data correlation of the C8/C10 and C10/C12 systems being 2.56 K and 1.22 K, respectively. Ultimately, the fitting procedure also enabled a good prediction of the eutectic point for both studied systems.
Open Access
Graphene-Assisted Chemical Stabilization of Liquid Metal Nano Droplets for Liquid Metal Based Energy Storage
(Wiley, 2024) Sanati, Afsaneh L.; Nikitin, Timur; FAUSTO, RUI; Majidi, Carmel; Tavakoli, Mahmoud
Energy storage devices with liquid-metal electrodes have attracted interest in recent years due to their potential for mechanical resilience, self-healing, dendrite-free operation, and fast reaction kinetics. Gallium alloys like Eutectic Gallium Indium (EGaIn) are appealing due to their low melting point and high theoretical specific capacity. However, EGaIn electrodes are unstable in highly alkaline electrolytes due to Gallium oxide dissolution. In this letter, this bottleneck is addressed by introducing chemically stable films in which nanoscale droplets of EGaIn are coated with trace amounts of graphene oxide (GO). It is demonstrated that a GO to EGaIn weight ratio as low as 0.01 provides enough protection for a thin film formed by GO@EGaIn nanocomposite against significantly acidic or alkaline environments (pH 1-14). It is shown that GO coating significantly enhances the surface stability in such environments, thus improving the energy storage capacity by over 10x. Microstructural analysis confirms GO@EGaIn composite stability and enhanced electrochemical performance. Utilizing this, a thin-film supercapacitor is fabricated. Results indicate that when coating the EGaIn with GO to EGaIn ratio of 0.001, the areal capacitance improves by 10 times, reaching 20.02 mF cm(-2). This breakthrough paves the way for advanced liquid metal-based thin-film electrodes, promising significant improvements in energy storage applications.
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Conformational Analysis of Milk Derived Tripeptides, IPP, VPP and LPP, and Investigation of Their Anti-COVID-19 Potentials by Molecular Docking and Molecular Dynamics Studies
(Taylor & Francis Ltd., 2024) Çelik, Sefa; AKYÜZ, SEVİM; Agaeva, Gulshen; E. Özel, Ayşen; Qocayev, Niftali M.; Agaeva, Ulker
Milk derived tripeptides IPP(Ile-Pro-Pro), VPP(Val-Pro-Pro) and LPP(Leu-Pro-Pro) have inhibitory effects on angiotensin converting enzyme, which plays a fundamental role in blood pressure systems. To discover the potentiality of the tripeptides as SARS-CoV-2 inhibitors, molecular docking analyses of IPP, VPP and LPP tripeptides with variety of SARS-CoV-2 enzymes, namely with Main protease, papain-like protease and Spike glycoprotein, were performed. Molecular dynamics simulations were performed to validate the stability of the IPP, LPP and VPP tripeptides docked into SARS-CoV-2 main protease within 50 ns time scale and ligand-receptor interactions were evaluated. Molecular docking and molecular dynamics studies showed that these food-derived tripeptides may be effective against COVID-19.