2,700 research outputs found
H/C, Vivienda y Ciudad: Concurso Internacional de Proyectos
No full textAbbordaggio critico sulla condizione contemporanea del progetto architettonico e lo spazio urbano in relazione al social housing
Electrocatalytic CO2 reduction by aminopyridine cobalt complexes: electronic effect of substituents on the pyridyl ring and mechanistic insights
No full textIn the last decade, several earth-abundant metal-based molecular catalysts have been found highly active for the photochemical or electrochemical CO2 reduction. However, despite their efficiency for the light-driven CO2-to-CO process,1 the electrocatalytic performances of Co complexes containing N4 or N5 ligands are still generally affected by catalyst deactivation,2 large overpotentials3 and low faradaic yields, due to either ligand decomposition or a preferential H2 evolution pathway under acidic conditions.4 To overcome these barriers, design of novel Co catalysts should be coupled to a deep understanding of the electrocatalytic mechanism, based on the characterization of key intermediates formed during the process. 5
Herein, we present a series of novel synthesized [CoII(Y,XPyMetacn)(OTf)2] complexes (1R, Scheme 1) containing N4 tetradentate ligands with general formula Y,XPyMetacn (1-[2′-(4-Y-6-X-pyridyl)methyl]-4,7-dialkyl-1,4,7-triazacyclononane),6 employed as catalysts for the electrochemical reduction of CO2. The introduction of different substituents at the - and -positions of the pyridine allowed us to systematically evaluate the effect of the electronic properties of the ligand on the catalytic activity. As highlighted by the electrochemical data, the redox non-innocent character of the Y,XPyMetacn ligand is extremely sensitive to the substitution at the pyridyl ring, and influences not only the E1/2(CoII/I) value, but also the nature of the reduction event itself, thus leading to different reactivity of the electrochemically generated CoI species towards CO2. Moreover, extensive spectroscopic (NMR) and spectroelectrochemical (IR and UV-Vis) studies were carried out to investigate the intermediates produced in the course of the catalytic process. Theoretical modelling provided also key mechanistic details for the CO2 reduction reaction.
Scheme 1. General structures of the 1R complexes under study
References
1 Z. Guo, S. Cheng, C. Cometto, E. Anxolabéhère-Mallart, S.-M. Ng, C.-C. Ko, G. Liu, L. Chen, M. Robert,T.-C. Lau, J. Am. Chem. Soc. 2016, 138, 9413−9416
2 K.-M. Lam, K.-Y. Wong, S.-M. Yang, C.-M. Che, Dalton Trans. 1995, 1103−1107
3 A. Chapovetsky, T. H. Do, R. Haiges, M. K. Takase, S. C. Marinescu, J. Am. Chem. Soc. 2016, 138, 5765−5768
4 D. C. Lacy, C. C. L. McCrory, J. C. Peters, Inorg. Chem. 2014, 53, 4980−4988
5 H. Sheng, H. Frei, J. Am. Chem. Soc. 2016, 138, 9959−9967
6 a) A. Call, F. Franco, S. Fernandez, N. Kandoth, J. M. Lluis J. Lloret-Fillol, Chem. Sci. 2016, submitted; b) A. Call, Z. Codola, F. Acuna-Pares, J. Lloret-Fillol, Chem. Eur. J. 2014, 20, 6171 – 618
La reconstrucción del compás del Duque de Béjar (1677)
No full text[ES] En el manuscrito matemático Observationes diversarum artium (1664-1677) de Fray Ignacio Muñoz, se aborda un capítulo sobre Instrumentos Geometricos que detalla el compás de proporción reducción del Duque de Béjar de 1677. La investigación se enfoca en la reconstrucción del instrumento y el análisis de las 16 operaciones descritas. De las 10 operaciones susceptibles de análisis estadístico, se encuentra una dispersión del 1,574% ±1,509%. Como conclusión, se estable que el error de la construcción del instrumento y sus seis líneas de cálculo es del 1,416%.[EN] In Fray Ignacio Muñoz's mathematical manuscript "Observationes diversarum artium" (1664-1677), a chapter on Geometric Instruments details the 1677 Duque de Béjar's compass of reduction. The study focuses on reconstructing the instrument and analyzing the 16 described operations. Of the 10 operations amenable to statistical analysis, a dispersion of 1.574% ±1.509% is found. In conclusion, the error in the construction of the instrument and its six calculation lines is determined to be 1.416%.Lluis-Teruel, C.;Lluis I Ginovart, J. (2025). The reconstruction of the compass of the Duke of Béjar (1677). EGA Expresión Gráfica Arquitectónica. 30(54):240-255. https://doi.org/10.4995/ega.2025.20906OJS240255305
More than an adaptor molecule: The emerging role of tRNA in cell signaling and disease
No full textThis FEBS Letters ‘FOCUS ON’ series of short reviews on tRNA captures the essence of the Barcelona BioMed Conference on Gene Translation: Fidelity and Quality Control, which was held at the Institut d’Estudis Catalans in Barcelona on December 2–4, 2013. This meeting was powered by the dramatic resurgence of interest in tRNA biochemistry following the realization that tRNA is much more than a simple adaptor of the genetic code
Immunolocalization of A1 adenosine receptors in mammalian spermatozoa
No full textThe presence of A1 adenosine receptors (A1AR) in mammalian spermatozoa was previously demonstrated by radiochemical and immunochemical detection. This study was performed to investigate the cellular location of the A1AR to determine whether these receptors were somehow connected with ecto-adenosine deaminase and to evaluate their function in calcium uptake. By immunofluorescence staining we showed that in mammalian spermatozoa A1AR were constantly localized in the acrosomal region. This finding was confirmed by immunogold detection. Confocal analyses with anti-A1 and anti-ADA antibodies showed a high degree of colocalization. Calcium loading assay showed that this association was functional and affected calcium accumulation in mammalian spermatozoa. Therefore, we concluded that the acrosomal localization of A1AR was a constant feature in mammalian sperm. Moreover, these A1 receptors were functionally coupled to ecto-ADA and were able to modulate calcium uptake into an IP3-gated store
Dual role of mitochondrial reactive oxygen species in hypoxia signaling: Activation of nuclear factor-κB via c-SRC- and oxidant-dependent cell death
No full textHypoxia is a prominent feature of solid tumor development and is known to stimulate mitochondrial ROS (mROS), which, in turn, can activate hypoxia-inducible transcription factor-1α and nuclear factor-κB (NF-κB). Because NF-κB plays a central role in carcinogenesis, we examined the mechanism of mROS-mediated NF-κB activation and the fate of cancer cells during hypoxia after mitochondrial reduced glutathione (mGSH) depletion. Hypoxia generated mROS in hepatoma (HepG2, H35), neuroblastoma (SH-SY5Y), and colon carcinoma (DLD-1) cells, leading to hypoxia-inducible transcription factor-1α-dependent gene expression and c-Src activation that was prevented in cells expressing a redox-insensitive c-Src mutant (C487A). c-Src stimulation activated NF-κB without IκB-α degradation due to IκB-α tyrosine phosphorylation that was inhibited by rotenone/TTFA or c-Src antagonism. The c-Src-NF-κB signaling contributed to the survival of cells during hypoxia as c-Src inhibition or p65 down-regulation by small interfering RNA-sensitized HepG2 cells to hypoxia-induced cell death. Moreover, selective mGSH depletion resulted in an accelerated and enhanced mROS generation by hypoxia that killed SH-SY5Y and DLD-1 cells without disabling the c-Src-NF-κB pathway. Thus, although mROS promote cell survival by NF-κB activation via c-Src, mROS overgeneration may be exploited to sensitize cancer cells to hypoxia. ©2007 American Association for Cancer Research.Grant support: Research Center for Liver and Pancreatic Diseases grant P50-AA11999 funded by the National Institute on Alcohol Abuse and Alcoholism; Plan Nacional de I+D Grant SAF 2006-6780; Fondo de Investigaciones Sanitarias, FISS 06/0495 and FISS 03/0426; and CIBEREHD supported by Instituto de Salud Carlos III. J.M. Lluis and A. Morales are Juan de la Cierva and Ramon y Cajal Investigators, respectively.Peer Reviewe
From text to knowledge: multilingual information extraction for knowledge graph construction
No full textIn the era of Large Language Models (LLMs), Information Extraction (IE) may
seem like a “Chronicle of a Death Foretold”. Between 2020 and 2023, it ranked
among the top three most popular topics at conferences like ACL, yet by 2024, it
had dropped to tenth place. The advent of Transformer Language Models (LMs),
emerging just before work on this dissertation began, has transformed the field of
Natural Language Processing (NLP), enabling unprecedented performance across a
broad range of Natural Language Understanding (NLU) tasks. Surprisingly, scaling
these models into LLMs has not led to diminishing returns but has instead further
expanded their capabilities.
However, there remains a need for efficient methods suitable for real-world
applications that require low latency or the ability to process large volumes of
real-time data—domains where large models are often impractical. Additionally,
tasks reliant on LLMs’ parametric memory face limitations due to neural inference,
where accuracy and recency of information cannot always be guaranteed. While
LLMs show great promise, they increasingly require grounding in external knowledge
sources for reliable results.
This is where IE becomes indispensable. Rather than being replaced, IE
complements and strengthens LLMs, supporting their reasoning with accurate,
grounded information. Knowledge Graphs (KGs) serve as structured frameworks that
bridge unstructured text and structured knowledge, enabling scalable, interpretable
organization of vast amounts of information. Essential for applications like semantic
search, recommendation systems, and question-answering, KGs rely heavily on robust
IE techniques. In this thesis, we focus on advancing multilingual IE methods to
enhance KG construction and address limitations in existing IE systems
The C terminus of initiation factor 4E-binding protein 1 contains multiple regulatory features that influence its function and phosphorylation
No full textEukaryotic initiation factor 4E (eIF4E) binds the mRNA cap structure and forms eIF4F complexes that recruit 40S subunits to the mRNA. Formation of eIF4F is blocked by eIF4E-binding proteins such as 4E-BP1, which interacts with eIF4E via a motif in the center of its 118-residue sequence. 4E-BP1 plays key roles in cell proliferation, growth, and survival. Binding of 4E-BP1 to eIF4E is regulated by hierarchical multisite phosphorylation. Here we demonstrate that three different features in the C terminus of 4E-BP1 play distinct roles in regulating its phosphorylation and function. Firstly, we identify a new phosphorylation site in its C terminus (S101). A serine or glutamate at this position is required for efficient phosphorylation at Ser65. A second C-terminal site, S112, directly affects binding of 4E-BP1 to eIF4E without influencing phosphorylation of other sites. Thirdly, a conserved C-terminal motif influences phosphorylation of multiple residues, including rapamycin-insensitive sites. These relatively long-range effects are surprising given the reportedly unstructured nature of 4E-BP1 and may imply that phosphorylation of 4E-BP1 and/or binding to eIF4E induces a more-ordered structure. 4E-BP2 and -3 lack phosphorylatable residues corresponding to both S101 and S112. However, in 4E-BP3, replacement of the alanine at the position corresponding to S112 by serine or glutamate did not confer the ability to be released from eIF4E in response to insulin
- …
