Repositorio Institucional UCSC (Univ. Católica de la Santísima Concepción)
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Lignin and functional polymer-based materials: Synthesis, characterization and application for Cr (VI) and As (V) removal from aqueous media
No full textIn this study, lignin derived from corncobs was chemically modified by substituting the hydroxyl groups present in its structure with methacrylate groups through a catalytic reaction using methacrylic anhydride, resulting in methacrylated lignin (ML). These MLs were incorporated in polymerization reaction of the monomer 2-[(acryloyloxy)ethyl trimethylammonium] chloride (Cl-AETA) and Cl-AETA, Cl-AETA/ML polymers were obtained, characterized (spectroscopic, thermal and microscopic analysis), and evaluated for removing Cr (VI) and As (V) from aqueous media in function of pH, contact time, initial metal concentrations and adsorbent amount.
The Cl-AETA/ML polymers followed the Langmuir adsorption model for the evaluated metal anions and were able to remove up to 91 % of Cr (VI) with a qmax (maximum adsorption capacity) of 201 mg/g, while for As (V), up to 60 % could be removed with a qmax of 58 mg/g. The results demonstrate that simple modifications in lignin enhance its functionalization and properties, making it suitable for removing contaminants from aqueous media, showing promising results for potential future applications
Author Correction: Mode of action, chemistry and defensive efficacy of the osmeterium in the caterpillar Battus polydamas archidamas
Get PDFZ-scheme driven charge transfer in g-C3N4/α-Fe2O3 nanocomposites enabling photocatalytic degradation of crystal violet and chromium reduction
No full textIn this study, we demonstrated the design and fabrication of iron oxide-embedded protonated graphitic carbon nitride (α-Fe2O3/p-g-C3N4) nanocomposites for photocatalytic dye degradation and heavy metal reduction applications under sunlight irradiation. The developed nanocomposites, with varying weight percentages of α-Fe2O3, were characterized for their structural (XRD, FTIR, XPS), optical (absorption and photoluminescence), morphological (FE-SEM, TEM), and electrochemical (EIS) properties to elucidate their structure-property relationships. The synthesis method ensures the uniform dispersion of α-Fe2O3 nanoparticles, with a particle size range of 50–60 nm, onto p-g-C3N4. XPS analysis suggests the formation of an electrical layer at the interface of α-Fe2O3/p-g-C3N4, facilitating the formation of a Z-scheme heterojunction. The photoluminescence and EIS spectra of the nanocomposite indicated effective separation and transfer of photo-induced charge carriers, aided by a reduced bandgap energy of ∼2.63 eV. Notably, the optimized 10 wt% α-Fe2O3/p-g-C3N4 nanocomposite exhibited superior photocatalytic activity, degrading nearly 100 % of crystal violate dye and reducing 98 % of Cr(VI) ions, compared to bare p-g-C3N4, which degraded around 43 % of the dye and reduced 39 % of Cr(VI) ions under sunlight irradiation. Scavenger studies indicated that α-Fe2O3/p-g-C3N4 nanocomposites produce adequate superoxide anions and hydroxyl radicals for dye degradation and heavy metal ion reduction. The composite also demonstrated consistent recyclability up to 5 cycles with around 100 % cyclical efficiency. The pH-dependent photoreduction and cyclic dye degradation by the 10 wt% α-Fe2O3/p-g-C3N4 photocatalyst indicated excellent stability, making it suitable for the treatment of multi-pollutant wastewater
Use of inclusive teaching and learning strategies in mathematics education
Get PDFLa implementación de estrategias didácticas en el aula es esencial para hacer que las clases sean interesantes y atractivas a los estudiantes, fomentando un ambiente inclusivo y de participación. Un profesor comprometido con la innovación y la comprensión absoluta promueve un ambiente de aprendizaje vibrante y desafiante, permitiendo a cada estudiante encontrar su lugar y desarrollar habilidades individuales. La didáctica de la matemática se convierte en una herramienta clave para promover el pensamiento crítico, la resolución de problemas y la inclusión educativa. Las estrategias de enseñanza y aprendizaje en matemática son fundamentales para poder garantizar un proceso educativo efectivo y lograr los aprendizajes significativos en nuestros estudiantes. La variedad y adaptación de las estrategias son claves para atender las necesidades individuales de los estudiantes y promover un ambiente de aprendizaje enriquecedor. Es fundamental reconocer la necesidad de implementar estrategias inclusivas en el aprendizaje matemático para asegurar que todos los estudiantes tengan igualdad de oportunidades. Estas estrategias buscan eliminar barreras y garantizar que todos los estudiantes, independientemente de sus características o habilidades, puedan participar y tener éxito en el aprendizaje de las matemáticas
El principio de reparación integral del daño y la (mal) denominada responsabilidad por acto lícito
No full textLa (mal) denominada “responsabilidad por acto lícito” agrupa una serie de supuestos que generan ciertos daños, pérdidas o menoscabos patrimoniales originados en acciones o conductas ajustadas a derecho, en que no existe transgresión a un deber jurídico alguno y, no obstante, se concede una indemnización. A través del presente trabajo concluiremos que en esta materia no rige el principio de reparación integral del daño, pues las compensaciones económicas que se conceden por tal causa sólo persiguen restablecer el equilibrio patrimonial roto por la disposición normativa que autoriza el comportamiento dañoso, el que se entiende cumplido pagando el valor objetivo o de cambio del derecho o interés sacrificado o perturbado
Motivation and Mathematical Performance Using Digital Game-Based Learning in Kindergarten
No full textThis study investigates the relationship between intrinsic motivation, mathematics performance, and digital game-based learning (DGBL) in kindergarten students. The research sample comprised 292 children aged 5 to 6 years from diverse socioeconomic backgrounds. Instruments included an adapted Children’s Basic Psychological Need Satisfaction Scale for measuring motivation and the Woodcock-Muñoz IV battery for mathematical assessment. DGBL was implemented using software designed for training early numeracy skills. Descriptive and correlational analyses revealed significant positive correlations between intrinsic motivation and general mathematical knowledge. However, no significant correlations were found between motivation and early numeracy skills in the DGBL environment. The findings highlight the importance of intrinsic motivation in early mathematical learning and suggest the potential effectiveness of DGBL in promoting mathematical skills, contributing to reducing the gap of knowledge at this educational level. This study provides valuable insights for educators seeking to enhance mathematical learning through intrinsic motivation and DGBL strategies in kindergarten education
Use of Intersectionality as a tool in the development of interventions, protocols and advanced health analyzes associated with people living with HIV. A Scoping Review
Get PDFIntroducción: la interseccionalidad se ha utilizado como herramienta para comprender y abordar las inequidades y desigualdades en salud, especialmente en el contexto de la atención médica a personas con VIH. Sin embargo, su aplicación en el desarrollo de estrategias de intervención y protocolos de atención es escasa.
Método: se realizó una revisión bibliográfica sistemática de alcance para identificar estudios que utilizan la interseccionalidad en el ámbito de la salud, como una herramienta para el desarrollo de análisis avanzados de información, desarrollo de instrumentos y protocolos asociados a personas con VIH. Se utilizaron bases de datos como Scopus, PubMed y Clarivate Analytics Wos of Science.
Resultados: la interseccionalidad se ha utilizado como herramienta para la elaboración de marcos bases para el desarrollo de protocolos e instrumento de medición, su uso en el desarrollo de programas de intervención es escasa.
Conclusiones: la interseccionalidad es una herramienta valiosa para comprender las desigualdades en salud, pero su aplicación en el desarrollo de estrategias de intervención y protocolos de atención es limitada. Es necesario desarrollar investigaciones que utilicen la interseccionalidad para crear programas de intervención y capacitación profesional en salud que aborden las desigualdades en salud y reduzcan el estigma asociado al VIH
Regulatory T cells administration reduces anxiety-like behavior in mice submitted to chronic restraint stress
Get PDFBackground: Major depression disorder (MDD) and anxiety are common mental disorders that significantly affect the quality of life of those who suffer from them, altering the person’s normal functioning. From the biological perspective, the most classical hypothesis explaining their occurrence relies on neurotransmission and hippocampal excitability alterations. However, around 30% of MDD patients do not respond to medication targeting these processes. Over the last decade, the involvement of inflammatory responses in depression and anxiety pathogenesis has been strongly acknowledged, opening the possibility of tackling these disorders from an immunological point of view. In this context, regulatory T cells (Treg cells), which naturally maintain immune homeostasis by suppressing inflammation could be promising candidates for their therapeutic use in mental disorders.
Methods: To test this hypothesis, C57BL/6 adult male mice were submitted to classical stress protocols to induce depressive and anxiety-like behavior; chronic restriction stress (CRS), and chronic unpredictable stress (CUS). Some of the stressed mice received a single adoptive transfer of Treg cells during stress protocols. Mouse behavior was analyzed through the open field (OFT) and forced swim test (FST). Blood and spleen samples were collected for T cell analysis using cell cytometry, while brains were collected to study changes in microglia by immunohistochemistry.
Results: Mice submitted to CRS and CUS develop anxiety and depressive-like behavior, and only CRS mice exhibit lower frequencies of circulating Treg cells. Adoptive transfer of Treg cells decreased anxiety-like behavior in the OFT only in CRS model, but not depressive behavior in FST in neither of the two models. In CRS mice, Treg cells administration lowered the number of microglia in the hippocampus, which increased due this stress paradigm, and restored its arborization. However, in CUS mice, Treg cells administration increased microglia number with no significant effect on their arborization.
Conclusion: Our results for effector CD4+ T cells in the spleen and microglia number and morphology in the hippocampus add new evidence in favor of the participation of inflammatory responses in the development of depressive and anxiety-like behavior and suggest that the modulation of key immune cells such as Treg cells, could have beneficial effects on these disorders
Casein kinase 2 phosphorylates and induces the SALL2 tumor suppressor degradation in colon cancer cells
Get PDFSpalt-like proteins are Zinc finger transcription factors from Caenorhabditis elegans to vertebrates, with critical roles in development. In vertebrates, four paralogues have been identified (SALL1-4), and SALL2 is the family’s most dissimilar member. SALL2 is required during brain and eye development. It is downregulated in cancer and acts as a tumor suppressor, promoting cell cycle arrest and cell death. Despite its critical functions, information about SALL2 regulation is scarce. Public data indicate that SALL2 is ubiquitinated and phosphorylated in several residues along the protein, but the mechanisms, biological consequences, and enzymes responsible for these modifications remain unknown. Bioinformatic analyses identified several putative phosphorylation sites for Casein Kinase II (CK2) located within a highly conserved C-terminal PEST degradation motif of SALL2. CK2 is a serine/threonine kinase that promotes cell proliferation and survival and is often hyperactivated in cancer. We demonstrated that CK2 phosphorylates SALL2 residues S763, T778, S802, and S806 and promotes SALL2 degradation by the proteasome. Accordingly, pharmacological inhibition of CK2 with Silmitasertib (CX-4945) restored endogenous SALL2 protein levels in SALL2-deficient breast MDA-MB-231, lung H1299, and colon SW480 cancer cells. Silmitasertib induced a methuosis-like phenotype and cell death in SW480 cells. However, the phenotype was significantly attenuated in CRISPr/Cas9-mediated SALL2 knockout SW480 cells. Similarly, Sall2-deficient tumor organoids were more resistant to Silmitasertib-induced cell death, confirming that SALL2 sensitizes cancer cells to CK2 inhibition. We identified a novel CK2-dependent mechanism for SALL2 regulation and provided new insights into the interplay between these two proteins and their role in cell survival and proliferation