Publications by authors named "Moncada F"

In this work, we present a non-orthogonal configuration interaction (NOCI) approach to address the rotational corrections in multicomponent quantum chemistry calculations where hydrogen nuclei and electrons are described with orbitals under Hartree-Fock (HF) and density functional theory (DFT) frameworks. The rotational corrections are required in systems such as diatomic (HX) and nonlinear triatomic molecules (HXY), where localized broken-symmetry nuclear orbitals have a lower energy than delocalized orbitals with the correct symmetry. By restoring rotational symmetry with the proposed NOCI approach, we demonstrate significant improvements in proton binding energy predictions at the HF level, with average rotational corrections of 0.

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Article Synopsis
  • The study investigates the stability and properties of complexes formed by halide anions and positrons using advanced computational methods to analyze their energetic configurations.
  • Findings show that these positronic complexes are globally stable due to the formation of two-positron bonds, which contrasts with some less stable configurations like PsH that can easily emit positrons.
  • The research also highlights similarities between two-positron dihalides and traditional two-electron dialkali molecules, suggesting notable trends in bonding properties, with the positron-containing complexes exhibiting unique characteristics such as shorter bond lengths and higher bond energies compared to their electron counterparts.
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Positronium (Ps) exhibits the ability to form energetically stable complexes with atoms and molecules before annihilation occurs. In particular, F, a halogen, shows the highest reported positronium binding energy (2.95 eV) in the periodic table.

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Purpose: X-ray scatter significantly affects the image quality of cone beam computed tomography (CBCT). Although convolutional neural networks (CNNs) have shown promise in correcting x-ray scatter, their effectiveness is hindered by two main challenges: the necessity for extensive datasets and the uncertainty regarding model generalizability. This study introduces a task-based paradigm to overcome these obstacles, enhancing the application of CNNs in scatter correction.

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We provide experimental evidence that is inconsistent with often proposed Langmuir-Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au-FeO. Passing CO and HO, but no O, over Au-γ-FeO at 25 °C, we observe significant CO production, inconsistent with LH mechanistic hypotheses. Experiments with HO further show that previous LH mechanistic proposals cannot account for water-promoted CO oxidation over Au-γ-FeO.

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We introduce a non-orthogonal configuration interaction approach to investigate nuclear quantum effects on energies and densities of confined fermionic nuclei. The Hamiltonian employed draws parallels between confined systems and many-electron atoms, where effective non-Coulombic potentials represent the interactions of the trapped particles. One advantage of this method is its generality, as it offers the potential to study the nuclear quantum effects of various confined species affected by effective isotropic or anisotropic potentials.

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This work presents an extension of the projector operator embedding scheme of Manby et al. [J. Chem.

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Article Synopsis
  • Researchers investigated how two positrons can help stabilize three hydride anions by forming unique bonds, highlighting the potential of positronic compounds.
  • Their study involved advanced computational methods, including Multi-Component MP2 and Monte Carlo calculations, to explore the energy and stability of the 2e[H ] system.
  • Findings revealed notable similarities between 2e[H ] and trilithium cation, supporting the idea of a new type of bonding in positronic molecules that differs from traditional electron-based bonds.
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Glial cells constitute half the population of the human brain and are essential for normal brain function. Most, if not all, brain diseases are characterized by reactive gliosis, a process by which glial cells respond and contribute to neuronal pathology. Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease characterized by a severe degeneration of cerebellar Purkinje cells (PCs) and cerebellar gliosis.

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  • Pyrazole-fused phenanthroline compounds were synthesized and characterized using various techniques like NMR and X-ray diffraction.
  • Compounds were tested as inhibitors for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), with compound 5c showing the best activity against AChE and compound 5l against BChE.
  • Additionally, several compounds demonstrated effective cationic radical scavenging abilities, particularly compounds 5e, 5f, and 5g, while 71% of the compounds exhibited good oral bioavailability based on Lipinski's rules.
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Despite the globally ascertained success of Total Knee Arthroplasty (TKA) procedure, 20% of patients are still unsatisfied with the surgery results. The purpose of the study is to identify the functional and radiological outcomes of the computer-assisted (CAS) TKA compared to the conventional technique. The clinical databases and medical records of both clinical sites were retrospectively analyzed, and then according to study time-lapse, inclusion, and exclusion criteria, eligible patients were retrieved and included.

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We report a computational study on homo- and heteronuclear e[XY] compounds formed by two halide anions (X, Y = F, Cl, Br) and one positron. Our results indicate the formation of energetically stable positronic molecules in all cases. Analysis of the electron and positron densities points out that the formation of positron covalent bonds underlies the stabilization of the otherwise repelling dihalides, revealing that positronic bonding can reach far beyond the previously addressed e[HH] molecule [J.

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  • Hexavalent chromium (Cr(VI)) levels in Honduran cement were measured at 5-8 mg/kg, higher than older Swedish samples which had 0.4 to 4.7 mg/kg of Cr(VI).
  • Many countries lack mandatory regulations to limit Cr(VI) content in cement, raising health and safety concerns.
  • Various strategies exist to mitigate the risks associated with Cr(VI) in cement production and usage.
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In this contribution, we examine the photophysical properties of 15 totally 1,4-distyrylbenzene derivatives (DSBs) functionalized with different electron-donating (ED) and electron-withdrawing (EW) groups by experimental and computational methodologies. We use UV-vis and fluorescence spectroscopies to determine the experimental optical properties such as the maximum absorption (λ) and emission (λ) wavelengths, the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gaps (Δ), the molar extinction coefficients (ε), the fluorescence quantum yields (Φ), and the fluorescence lifetimes (τ). We also calculate the experimental spontaneous emission decay rate () and correlate all of these magnitudes to the corresponding calculated properties, maximum absorption (λ) and emission (λ) wavelengths, vertical transition energies (Δ), oscillator strength (), and spontaneous emission decay rate (), obtained by the time-dependent density functional theory method.

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Existing frameworks of community-based early warning systems (CBEWS) lack focus on its actual implementation. Furthermore, they do not describe how a top-down early warning system (EWS) can be transformed into a CBEWS. Hence, to support the establishment of a community-based early warning system for deep-seated landslides (CBEWS-L), this study aimed to assess the capacities and vulnerabilities of five in the Philippines.

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The any particle molecular orbital grid-based Hartree-Fock approach (APMO-GBHF) is proposed as an initial step to perform multi-component post-Hartree-Fock, explicitly correlated, and density functional theory methods without basis set errors. The method has been applied to a number of electronic and multi-species molecular systems. Results of these calculations show that the APMO-GBHF total energies are comparable with those obtained at the APMO-HF complete basis set limit.

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We propose a scheme to estimate hydrogen isotope effects on molecular polarizabilities. This approach combines the any-particle molecular orbital method, in which both electrons and H/D nuclei are described as quantum waves, with the auxiliary density perturbation theory, to calculate analytically the polarizability tensor. We assess the performance of method by calculating the polarizability isotope effect for 20 molecules.

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The any-particle molecular orbital method at the full configuration interaction level has been employed to study atoms in which one electron has been replaced by a negative muon. In this approach electrons and muons are described as quantum waves. A scheme has been proposed to discriminate nuclear mass and quantum muon effects on chemical properties of muonic and regular atoms.

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We report the case of a patient with congenital toxoplasmosis and submacular hemorrhage caused by a neovascular membrane who underwent an intravitreal injection of C3F8 and bevacizumab, and had a good visual recovery.

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