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Missense mutations in MMACHC protein from cblC disease affect its conformational stability and vitamin B12-binding activity: The example of R161Q mutation
Full text linkMMACHC protein plays a crucial role in the metabolism of vitamin B12 (cobalamin, Cbl) by catalyzing its conversion into the active forms adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl), which serve as essential cofactors in key cellular reactions. Mutations in the gene encoding MMACHC lead to the rare metabolic disorder known as methylmalonic aciduria and homocystinuria, cblC type. This condition predominantly affects children and is characterized by cardiovascular dysfunction, intellectual disability, and a severe form of maculopathy. The most common missense mutation, R161Q, impairs enzymatic activity despite not being directly involved in cobalamin binding. Here, using a comprehensive set of biophysical techniques, we demonstrate that this pathogenic variant compromises MMACHC structural stability, alters the thermal unfolding cooperativity and pathway, as well as the populations of conformational intermediates. Moreover, we show that the R161Q mutation decreases AdoCbl binding affinity and impairs the protein's ability to form homodimers, which are supposed to have a functional role. A partial recovery in protein activity upon treatment with betaine, an osmolyte known for its stabilizing effect on proteins, was observed. This suggests a direct correlation between the energetics of MMACHC thermal unfolding and its functional activity. These findings contribute to a deeper understanding of the molecular mechanisms underlying MMACHC function and open avenues for potential therapeutic interventions
<i>Operando</i> Raman and <i>ex situ</i> characterization of an iron-based conductive MOF as a negative electrode in Li-ion batteries
No full textAn iron-based electrically conductive metal–organic framework (MOF), Fe-HHTP, formed by the coordination of Fe cations and the organic ligand HHTP (2,3,6,7,10,11-hexahydroxytriphenylene), has been synthesized, characterized, and explored as a potential negative electrode for lithium-ion batteries (LIBs). Galvanostatic cycling experiments, with a lower cut-off voltage of 0.1 V vs. Li/Li+, reveal that Fe-HHTP undergoes a significant activation process, resulting in an increase in specific capacity up to 1142 mAh g−1 after ∼220 cycles at a current of 355 mA g−1. Operando Raman spectroscopy during the first lithiation, complemented by ex situ techniques at different cycling stages, demonstrates that both the organic ligands and metal centers actively contribute to Li+ storage. Initially, lithiation occurs primarily at the MOF boundaries, while continuous cycling induces a structural transformation that allows greater accessibility to the inner regions of Fe-HHTP. These results provide a better understanding of the electrochemical and structural behavior of pristine MOFs that allow tailoring their properties for direct application in energy storage devices without the need for high-temperature processes
Factorizations and Accurate Computations with Min and Max Matrices
Full text linkMin and max matrices are structured matrices that appear in diverse mathematical and computational applications. Their inherent structures facilitate highly accurate numerical solutions to algebraic problems. In this research, the total positivity of generalized Min and Max matrices is characterized, and their bidiagonal factorizations are derived. It is also demonstrated that these decompositions can be computed with high relative accuracy (HRA), enabling the precise computations of eigenvalues and singular values and the solution of linear systems. Notably, the discussed approach achieves relative errors on the order of the unit roundoff, even for large and ill-conditioned matrices. To illustrate the exceptional accuracy of this method, numerical experiments on quantum extensions of Min and L-Hilbert matrices are presented, showcasing their superior precisions compared to those of standard computational techniques
Variability in infection dynamics emerges from the interplay between unique host and pathogen characteristics
Full text linkVariation in infection dynamics across host species can profoundly influence parasite epidemiology, ecology, and evolution. However, because experiments involving multiple hosts and multiple parasite species that capture the full infection dynamics within hosts are rare, the underlying mechanisms of host heterogeneity effects across different parasite species remain largely unknown. We dissected the specific roles of host and pathogen effects in shaping within-host infection dynamics using a model system comprising three coexisting rodent species from Israel’s northwestern Negev Desert and their predominant bacterial pathogens, Bartonella krasnovii A2 and Mycoplasma haemomuris-like bacterium. To test whether the effects of host species heterogeneity on parasite dynamics mainly derive from host trait variation (“host trait variation hypothesis”) or rather reflect a unique host-parasite interaction (“specific host-parasite interaction” hypotheses), we inoculated rodents of the three species (Gerbillus andersoni, G. pyramidum, and G. gerbillus) with either Bartonella or Mycoplasma and compared their infection dynamics during primary infection and upon reinfection. According to the “host trait variation” hypothesis, host heterogeneity effects would be consistent across parasite species. Supporting this hypothesis, both bacterial pathogens exhibited reduced performance in G. gerbillus compared to the other rodent species. However, consistent with the alternative “specific host-parasite interaction” hypothesis, all other aspects of the infection dynamics of these two pathogens exhibited varying trends across the three hosts, indicating the uniqueness of each pathogen-host interaction. Our findings support the notion that the variability in infection dynamics is not solely attributable to host heterogeneity, but rather emerges from the interplay between specific host characteristics and parasite traits. We discuss potential directions for future research to deepen our understanding of within-host dynamics in multispecies communities. We stress the necessity of analyzing each distinct host-parasite interaction independently when making inferences about community patterns based on infection dynamics within hosts until more experimental data on natural systems are accumulated
Strong In-plane Magnetic Anisotropy in Semiconducting Monolayer CoCl2
Full text linkTransition-metal dihalides (TMDH) are emerging as a highly promising class of 2D magnetic materials due to their simplicity, stability, and compatibility with nanofabrication techniques. In this work, we explore the structural, electronic, and magnetic properties of monolayer CoCl2 grown epitaxially on Au(111) using a multitechnique approach. Our results reveal that epitaxial CoCl2 exhibits ferromagnetic order below 24 K with strong in-plane magnetic anisotropy, setting it apart from other TMDH materials. Additionally, we identify in-gap states arising from the CoCl2–Au(111) interface, which provide insights into its electronic behavior. These findings position CoCl2 as a versatile 2D material for spintronic applications and nanoscale devices, bridging the gap between fundamental research and real-world technological solutions
Comparative operational carbon footprints of a vehicle in Brazil: Electric, ethanol, and gasoline
Full text linkThis study quantifies the operational carbon footprint of the Renault Kwid E-Tech (electric vehicle) and Renault Kwid Intense flex (gasoline and ethanol internal combustion engine vehicle) under a Well-to-Wheel approach within the Brazilian context. With a functional unit of 100,000 km, this analysis evaluates greenhouse gas (GHG) emissions associated with fuel consumption and considers different electric mixes across Brazilian regions, along with the periodic maintenance of each vehicle type. The results reveal significant environmental benefits in regions such as the Northeast, where renewable energy sources predominate, reducing the carbon footprint of the electric model, with a carbon footprint of 0.071 kg CO2-eq/kWh. By contrast, the higher carbon intensity of the South’s electricity mix reliant on coal, with a carbon footprint of 0.281 kg CO2-eq/kWh, presents limitations in achieving emissions reductions with electric vehicles. Ethanol, a renewable biofuel in the Brazilian market, demonstrated a 46 % reduction in GHG emissions compared to gasoline. This study contributes to the sustainable mobility discourse, highlighting the critical role of regional energy sources, fuel choices, and sustainable production practices in emissions outcome. These insights support the development of policies encouraging cleaner energy matrices and biofuel use, contributing to Brazil's emissions reduction goals
Epidemiology and factors associated with the perioperative course of patients undergoing hip fracture during the initial phase of the state of emergency declared in 2020
Full text linkIntroductionCurrently, there is no gold standard anesthetic plan for elderly patients with hip fractures who must undergo surgery. The state of alarm during 2020 due to the COVID-19 pandemic changed certain hospital paradigms, prompting an investigation into differences in anesthetic management and patient survival for hip fracture surgeries using gamma nail osteosynthesis in 2020 compared to 2019.Materials and methodsA historical cohort study was conducted to assess morbidity and mortality, with data obtained from anonymized medical records.ResultsStatistically significant differences were found, notably an increase in Body Mass Index during confinement. A statistically significant decrease in leukocyte and hemoglobin levels was observed after surgery. However, there were no statistically significant differences in mortality between 2019 and 2020. Patients who did not require vasoactive drugs during surgery to maintain blood pressure levels above 90/60 mmHg had a better survival rate.ConclusionDespite the reduction in postoperative hospital surveillance time, no increase in complications was found. This allowed for early patient reintegration into daily life, early functional rehabilitation, and the minimization of economic costs
Formulation of Urban Growth Scenarios for Middle-Sized Cities Towards Metropolization: The Case of Puerto Montt, Los Lagos Region
Full text linkThis study models changes in land cover and land use in the intermediate city of Puerto Montt, Chile, up to 2050. Three distinct time periods—1988, 2005, and 2020—were used to examine Puerto Montt’s urban growth during these years. These periods were described using the Local Climate Zones (LCZ) technique. Urban growth scenarios were simulated using the Patch-generating Land Use Simulation (PLUS) model. Using Machine Learning (ML) techniques, this model has been widely utilized to explain how urban growth patterns have evolved based on the dynamics that drive changes in land use and land cover. Three scenarios were developed for this study: Business-As-Usual (BAU) (S1), Urban-Regional Planning (S2), and Conservationist (S3). According to the findings, Puerto Montt is predicted to undergo morphological changes by 2050, shifting from rural areas primarily composed of woods and agricultural land to open, low-density, low-rise areas outside the municipal limits set by the Communal Regulatory Plans. According to this study, Puerto Montt’s relative entropy level was high, ranging from 0.87 to 0.96, with a maximum value of 1.00 by 2050. These findings are anticipated to provide planners and decision-makers with further knowledge on the territorial design of upcoming urban areas
Enhanced glycerol steam reforming using Ni-doped CaZrO3, SrZrO3, and BaZrO3 perovskite oxides
No full textThis study investigates the catalytic activity and time-on-stream stability of Ni catalysts supported on CaZrO3, SrZrO3, and BaZrO3 perovskite oxides for the glycerol steam reforming (GSR) reaction, which aims to convert the crude glycerol obtained from the transesterification of vegetable and microalgae oils (during bio-diesel production) into hydrogen gas. We employed XRD, N2 physisorption, H2-TPR, H2 pulse chemisorption, CO2-TPD, Raman, TPO, and TEM/HAADF-STEM to examine the surface and bulk properties of the catalysts before and after the reaction. Regarding catalytic activity evaluation, the Ni catalysts supported on CaZrO3 and SrZrO3 can effectively eliminate all liquid products (acetol, acetone, allyl alcohol, acetaldehyde, and acetic acid) at reaction temperatures higher than 500 °C, converting all glycerol to gaseous products (>6 mol H2/mol of glycerol for the best performing Ni/SrZrO3). This is due to a higher Ni dispersion, increased availability of active sites for the dissociation of C3H8O and H2O molecules, and a more favorable and stronger Ni-support interaction. Notably, the activity of Ni supported on SrZrO3 is among the highest reported in the literature. Furthermore, due to its unique Ni-support interaction, the Ni catalyst supported on SrZrO3 demonstrated remarkable catalytic stability. Apparently, some Ni2+ cations are solubilized into the perovskite lattice following high-temperature calcination. After being incorporated into the perovskite lattice, these cations then migrate to the surface via the exsolution process upon high-temperature reduction. During the glycerol steam reforming reaction, this helps prevent carbon growth on the exposed metallic Ni surface, thereby prolonging the catalyst lifetime and ensuring reliable H2 production during long-term operation and under harsh reaction conditions
Explorando oportunidades de alfa en la inversión ASG
Full text linkEste trabajo pretende desarrollar un marco teórico analítico para examinar la influencia de los factores ambientales, sociales y de gobernanza (ASG) sobre diferentes métricas financieras clave, con especial atención a la rentabilidad sobre recursos propios (ROE). La elección del ROE como variable dependiente se considera especialmente adecuada, ya que es una métrica más realista del desempeño financiero y, además, suele arrojar mejores resultados estadísticos en modelos empíricos. Mediante modelos de regresión aplicados a empresas de diferentes sectores, se analiza si existe una relación significativa entre el desempeño ASG y el ROE, lo que permitiría identificar patrones sectoriales y posibles ventajas competitivas asociadas a prácticas sostenibles. El estudio contribuye a la literatura sobre finanzas sostenibles evaluando si las empresas con mejores indicadores ASG tienen un rendimiento financiero superior. Se espera que los resultados proporcionen información e ideas prácticas para los inversores que buscan integrar criterios de sostenibilidad en la toma de decisiones financieras. <br /