429 research outputs found

    Novel organotin-PTA complexes supported on mesoporous carbon materials as recyclable catalysts for solvent-free cyanosilylation of aldehydes

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    The work was also funded by national funds through FCT, under the Scientific Employment Stimulus-Institutional Call (CEEC-INST/00102/2018). AGM is grateful to Associa√ß√£o do Instituto Superior T√©cnico para a Investiga√ß√£o e Desenvolvimento ( IST-ID ) for his post-doctoral fellowship through grant no. BL133/2021-IST-ID . AP and AMF are grateful to FCT and Instituto Superior T√©cnico (IST), Portugal through DL/57/2017 (Contract no. IST-ID/197/2019 and IST-ID/131/2018). This publication is also supported by the RUDN University Strategic Academic Leadership Program (recipient AJLP, preparation). The authors also acknowledge the Portuguese NMR Network (IST-UL Centre) for access to the NMR facility. Publisher Copyright: ¬© 2023 Elsevier B.V.New organotin compounds with general formula [(PTA-CH2-C6H4-p-COO)SnR3]Br (where R is Me for 3 and Ph for 4; PTA = 1,3,5-triaza-7-phosphaadamantane), bearing the methylene benzoate PTA derivative, were synthesized through a mild two-step process. The compounds were characterized by Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry, elemental analysis and nuclear magnetic resonance spectroscopy (NMR). They were heterogenized on commercially available activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on their chemically modified analogues. The obtained materials were characterized by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Complex 3 supported on activated carbon (3-AC) was found to be an active and recyclable catalyst for the cyanosilylation of several aromatic and aliphatic aldehydes. Using 3-AC with a low loading of 0.1 mol% several substrates were quantitatively converted, within just 5 min at 50 ¬įC and under microwave irradiation in solvent-free conditions. Multinuclear NMR analysis suggested a mechanism that potentially involves a double activation process, where the nucleophilic phosphorus at the PTA derivative acts as a Lewis base and the Sn(IV) metal centre as a Lewis acid.publishersversionpublishe

    Elucidating the concentration-dependent effects of thiocyanate binding to carbonic anhydrase

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    Funding Information: This work has been supported by the Fondazione Cassa di Risparmio di Firenze. NMR measurements performed at 1200 MHz spectrometer were done with the support and the use of resources of Instruct-ERIC, a landmark ESFRI project, and specifically the CERM/CIRMMP Italy center. The authors also thank FCT-Portugal for the Ph.D. grant awarded to Jos√© Malanho Silva under the PTNMRPhD Program - NMR applied to chemistry, materials, and biosciences (PD/00065/2013). The authors acknowledge the ALBA synchrotron facility (Barcelona, Spain) for access to the BL-13 XALOC beamline. The 500 MHz NMR spectrometer used in the experiments is part of the National NMR Facility supported by FCT-Portugal (ROTEIRO/0031/2013‚ÄďPIN-FRA/22161/2016, co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC). Publisher Copyright: ¬© 2023Many proteins naturally carry metal centers, with a large share of them being in the active sites of several enzymes. Paramagnetic effects are a powerful source of structural information and, therefore, if the native metal is paramagnetic, or it can be functionally substituted with a paramagnetic one, paramagnetic effects can be used to study the metal sites, as well as the overall structure of the protein. One notable example is cobalt(II) substitution for zinc(II) in carbonic anhydrase. In this manuscript we investigate the effects of sodium thiocyanate on the chemical environment of the metal ion of the human carbonic anhydrase II. The electron paramagnetic resonance (EPR) titration of the cobalt(II) protein with thiocyanate shows that the EPR spectrum changes from A-type to C-type on passing from 1:1 to 1:1000-fold ligand excess. This indicates the occurrence of a change in the electronic structure, which may reflect a sizable change in the metal coordination environment in turn caused by a modification of the frozen solvent glass. However, paramagnetic nuclear magnetic resonance (NMR) data indicate that the metal coordination cage remains unperturbed even in 1:1000-fold ligand excess. This result proves that the C-type EPR spectrum observed at large ligand concentration should be ascribed to the low temperature at which EPR measurements are performed, which impacts on the structure of the protein when it is destabilized by a high concentration of a chaotropic agent.publishersversionpublishe

    A many-analysts approach to the relation between religiosity and well-being

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    Modeling Gd 3+ Complexes for Molecular Dynamics Simulations: Toward a Rational Optimization of MRI Contrast Agents

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    The correct parametrization of lanthanide complexes is of the utmost importance for their characterization using computational tools such as molecular dynamics simulations. This allows the optimization of their properties for a wide range of applications, including medical imaging. Here we present a systematic study to establish the best strategies for the correct parametrization of lanthanide complexes using [Gd(DOTA)]‚ąí as a reference, which is used as a contrast agent in MRI. We chose the bonded model to parametrize the lanthanide complexes, which is especially important when considering the study of the complex as a whole (e.g., for the study of the dynamics of its interaction with proteins or membranes). We followed two strategies: a so-called heuristic approach employing strategies already published by other authors and another based on the more recent MCPB.py tool. Adjustment of the Lennard-Jones parameters of the metal was required. The final topologies obtained with both strategies were able to reproduce the experimental ion to oxygen distance, vibrational frequencies, and other structural properties. We report a new strategy to adjust the Lennard-Jones parameters of the metal ion in order to capture dynamic properties such as the residence time of the capping water (ŌĄm). For the first time, the correct assessment of the ŌĄm value for Gd-based complexes was possible by recording the dissociative events over up to 10 őľs all-atom simulations. The MCPB.py tool allowed the accurate parametrization of [Gd(DOTA)]‚ąí in a simpler procedure, and in this case, the dynamics of the water molecules in the outer hydration sphere was also characterized. This sphere was divided into the first hydration layer, an intermediate region, and an outer hydration layer, with a residence time of 18, 10 and 19 ps, respectively, independent of the nonbonded parameters chosen for Gd3+. The Lennard-Jones parameters of Gd3+ obtained here for [Gd(DOTA)]‚ąí may be used with similarly structured gadolinium MRI contrast agents. This allows the use of molecular dynamics simulations to characterize and optimize the contrast agent properties. The characterization of their interaction with membranes and proteins will permit the design of new targeted contrast agents with improved pharmacokinetics

    Can space-for-time-substitution surveys represent zooplankton biodiversity patterns and their relationship to environmental drivers?

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    Space-for-Time-Substitution surveys (SFTS) are commonly used to describe zooplankton community dynamics and to determine lake ecosystem health. SFTS surveys typically combine single point observations from many lakes to evaluate the response of zooplankton community structure and dynamics (e.g., species abundance and biomass, diversity, demographics and modeled rate processes) to spatial gradients in hypothesized environmental drivers (e.g., temperature, nutrients, predation), in lieu of tracking such responses over long time scales. However, the reliability and reproducibility of SFTS zooplankton surveys have not yet been comprehensively tested against empirically-based community dynamics from longterm monitoring efforts distributed worldwide. We use a recently compiled global data set of more than 100 lake zooplankton time series to test whether SFTS surveys can accurately capture zooplankton diversity, and the hypothesized relationship with temperature, using simulated SFTS surveys of the time series data. Specifically, we asked: (1) to what degree can SFTS surveys capture observed biodiversity dynamics; (2) how does timing and duration of sampling affect detected biodiversity patterns; (3) does biodiversity ubiquitously increase with temperature across lakes, or vary by climate zone or lake type; and (4) do results from SFTS surveys produce comparable biodiversity-temperature relationship(s) to empirical data within and among lakes? Testing biodiversity-ecosystem function (BEF) relationships, and the drivers of such relationships, requires a solid data basis. Our work provides a global perspective on the design and usefulness of (long-term) zooplankton monitoring programs and how much confidence we can place in the zooplankton biodiversity patterns observed from SFTS surveys

    A many-analysts approach to the relation between religiosity and well-being

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    The relation between religiosity and well-being is one of the most researched topics in the psychology of religion, yet the directionality and robustness of the effect remains debated. Here, we adopted a many-analysts approach to assess the robustness of this relation based on a new cross-cultural dataset (N = 10, 535 participants from 24 countries). We recruited 120 analysis teams to investigate (1) whether religious people self-report higher well-being, and (2) whether the relation between religiosity and self-reported well-being depends on perceived cultural norms of religion (i.e., whether it is considered normal and desirable to be religious in a given country). In a two-stage procedure, the teams first created an analysis plan and then executed their planned analysis on the data. For the first research question, all but 3 teams reported positive effect sizes with credible/confidence intervals excluding zero (median reported beta = 0.120). For the second research question, this was the case for 65% of the teams (median reported beta = 0.039). While most teams applied (multilevel) linear regression models, there was considerable variability in the choice of items used to construct the independent variables, the dependent variable, and the included covariates

    A Many-analysts Approach to the Relation Between Religiosity and Well-being

    Get PDF
    The relation between religiosity and well-being is one of the most researched topics in the psychology of religion, yet the directionality and robustness of the effect remains debated. Here, we adopted a many-analysts approach to assess the robustness of this relation based on a new cross-cultural dataset (N = 10, 535 participants from 24 countries). We recruited 120 analysis teams to investigate (1) whether religious people self-report higher well-being, and (2) whether the relation between religiosity and self-reported well-being depends on perceived cultural norms of religion (i.e., whether it is considered normal and desirable to be religious in a given country). In a two-stage procedure, the teams first created an analysis plan and then executed their planned analysis on the data. For the first research question, all but 3 teams reported positive effect sizes with credible/confidence intervals excluding zero (median reported ő≤ = 0.120). For the second research question, this was the case for 65% of the teams (median reported ő≤ = 0.039). While most teams applied (multilevel) linear regression models, there was considerable variability in the choice of items used to construct the independent variables, the dependent variable, and the included covariates

    2022 American College of Rheumatology/European Alliance of Associations for Rheumatology Classification Criteria for Eosinophilic Granulomatosis With Polyangiitis

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    Objective: To develop and validate revised classification criteria for eosinophilic granulomatosis with polyangiitis (EGPA). Methods: Patients with vasculitis or comparator diseases were recruited into an international cohort. The study proceeded in 5 phases: 1) identification of candidate criteria items using consensus methodology, 2) prospective collection of candidate items present at the time of diagnosis, 3) data-driven reduction of the number of candidate items, 4) expert panel review of cases to define the reference diagnosis, and 5) derivation of a points-based risk score for disease classification in a development set using least absolute shrinkage and selection operator logistic regression, with subsequent validation of performance characteristics in an independent set of cases and comparators. Results: The development set for EGPA consisted of 107 cases of EGPA and 450 comparators. The validation set consisted of an additional 119 cases of EGPA and 437 comparators. From 91 candidate items, regression analysis identified 11 items for EPGA, 7 of which were retained. The final criteria and their weights were as follows: maximum eosinophil count ‚Č•1 √ó 109/liter (+5), obstructive airway disease (+3), nasal polyps (+3), cytoplasmic antineutrophil cytoplasmic antibody (ANCA) or anti‚Äďproteinase 3 ANCA positivity (‚ąí3), extravascular eosinophilic predominant inflammation (+2), mononeuritis multiplex/motor neuropathy not due to radiculopathy (+1), and hematuria (‚ąí1). After excluding mimics of vasculitis, a patient with a diagnosis of small- or medium-vessel vasculitis could be classified as having EGPA if the cumulative score was ‚Č•6 points. When these criteria were tested in the validation data set, the sensitivity was 85% (95% confidence interval [95% CI] 77‚Äď91%) and the specificity was 99% (95% CI 98‚Äď100%). Conclusion: The 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for EGPA demonstrate strong performance characteristics and are validated for use in research

    High spin Fe(III)-doped nanostructures as T1 MR imaging probes

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    Magnetic Resonance Imaging (MRI) T1 contrast agents based on Fe(III) as an alternative to Gd-based compounds have been under intense scrutiny in the last 6-8‚ÄČyears and a number of nanostructures have been designed and proposed for in vivo diagnostic and theranostic applications. Excluding the large family of superparamagnetic iron oxides widely used as T2 -MR imaging agents that will not be covered by this review, a considerable number and type of nanoparticles (NPs) have been employed, ranging from amphiphilic polymer-based NPs, NPs containing polyphenolic binding units such as melanin-like or polycatechols, mixed metals such as Fe/Gd or Fe/Au NPs and perfluorocarbon nanoemulsions. Iron(III) exhibits several favorable magnetic properties, high biocompatibility and improved toxicity profile that place it as the paramagnetic ion of choice for the next generation of nanosized MRI and theranostic contrast agents. An analysis of the examples reported in the last decade will show the opportunities for relaxivity and MR-contrast enhancement optimization that could bring Fe(III)-doped NPs to really compete with Gd(III)-based nanosystems. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease

    Evidence confirms an anthropic origin of Amazonian Dark Earths.

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    Arising from: Silva et al. Nature Communications https://doi.org/10.1038/s41467-020-20184-2 (2021
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