Los diferentes ámbitos sociales y profesionales conllevan experiencias emocionales específicas ligadas a situaciones interaccionales particulares. En este artículo me propongo analizar el repertorio ...emocional que experimentan los agentes de Policía. Preguntándome por las experiencias de vulnerabilidad que operan por debajo del poder policial, he revisado los materiales etnográficos procedentes de distintas investigaciones en el campo securitario y policial en Madrid en las que he participado. Entre los hallazgos, desarrollo de un lado las experiencias de vulnerabilidad más comunes en el trabajo policial, las cuales se relacionan con tres tipos de situaciones: de tensión, de presión y de juicio crítico. De otro lado, analizo las diferentes estrategias desplegadas para afrontar esa vulnerabilidad: aquellas que refuerzan el espíritu de Cuerpo y que transmutan las críticas en sentimiento de orgullo policial, y aquellas otras que implican una cierta transformación subjetiva a través de la aproximación a metodologías “blandas” propias del trabajo social y del contacto con referentes académicos.
Manuel Vázquez Montalbán y Paco Ignacio Taibo II iniciaron casi simultáneamente una renovación de la novela policíaca escrita en español a mediados de los años setenta tanto en España como en México ...con sus obras Tatuaje (1974) y Días de combate (1976), respectivamente. Este estudio tiene como objetivo principal la elaboración de un acercamiento conjunto a las producciones policíacas de ambos escritores, ampliando una serie de correspondencias entre ellos ya advertida por críticos como William J. Nichols y José Colmeiro. Si bien sus obras se fundamentan en la representación realista de un contexto nacional específico, apoyándose en el empleo de ciertas claves de la novela negra estadounidense, algunas de las características y de los antecedentes de esta nueva novela policíaca hispánica de Vázquez Montalbán y Taibo adquieren un carácter transnacional, lo que permite aplicar a sus obras un enfoque desde los estudios transatlánticos para trazar nexos y elaborar comparaciones. En este sentido, proponemos una muestra de los rasgos comunes identificables tanto en las producciones policíacas de ambos escritores como en sus propias figuras: unos adscritos a determinados procedimientos literarios, como el tratamiento del personaje protagonista detectivesco y el empleo de la metaficción, y otros de naturaleza transatlántica, como el mestizaje, los movimientos migratorios y la atención hacia la guerra civil española.
Branched-chain amino acid (BCAA) metabolism fulfills numerous physiological roles and can be harnessed to produce valuable chemicals. However, the lack of eukaryotic biosensors specific for ...BCAA-derived products has limited the ability to develop high-throughput screens for strain engineering and metabolic studies. Here, we harness the transcriptional regulator Leu3p from Saccharomyces cerevisiae to develop a genetically encoded biosensor for BCAA metabolism. In one configuration, we use the biosensor to monitor yeast production of isobutanol, an alcohol derived from valine degradation. Small modifications allow us to redeploy Leu3p in another biosensor configuration that monitors production of the leucine-derived alcohol, isopentanol. These biosensor configurations are effective at isolating high-producing strains and identifying enzymes with enhanced activity from screens for branched-chain higher alcohol (BCHA) biosynthesis in mitochondria as well as cytosol. Furthermore, this biosensor has the potential to assist in metabolic studies involving BCAA pathways, and offers a blueprint to develop biosensors for other products derived from BCAA metabolism.
The electroreduction of carbon dioxide using renewable electricity is an appealing strategy for the sustainable synthesis of chemicals and fuels. Extensive research has focused on the production of ...ethylene, ethanol and n‐propanol, but more complex C4 molecules have been scarcely reported. Herein, we report the first direct electroreduction of CO2 to 1‐butanol in alkaline electrolyte on Cu gas diffusion electrodes (Faradaic efficiency=0.056 %, j1‐Butanol=−0.080 mA cm−2 at −0.48 V vs. RHE) and elucidate its formation mechanism. Electrolysis of possible molecular intermediates, coupled with density functional theory, led us to propose that CO2 first electroreduces to acetaldehyde‐a key C2 intermediate to 1‐butanol. Acetaldehyde then undergoes a base‐catalyzed aldol condensation to give crotonaldehyde via electrochemical promotion by the catalyst surface. Crotonaldehyde is subsequently electroreduced to butanal, and then to 1‐butanol. In a broad context, our results point to the relevance of coupling chemical and electrochemical processes for the synthesis of higher molecular weight products from CO2.
Carbon dioxide was electroreduced to 1‐butanol on oxide‐derived copper. The reaction mechanism was determined to proceed through a combination of electrochemical and chemical steps, some of which require contrasting conditions. This example highlights limitations in one‐pot synthesis and provides a case for utilizing independently optimized sequential reactors in a tandem system to build complex molecules from low molecular‐weight feedstocks.
Single atoms and nanoclusters of Fe, Ni, Co, Cu, and Mn are systematically designed and embedded in a well‐defined C1N1‐type material that has internal cavities of ≈0.6 nm based on four N atoms. ...These N atoms serve as perfect anchoring points for the nucleation of small nanoclusters of different metal natures through the creation of metal‐nitrogen (TM‐N4) bonds. After pyrolysis at 800 °C, TM@CNx‐type structures are obtained, where TM is the transition metal and x < 1. Fe@CNx and Co@CNx are the most promising for oxygen reduction reaction and hydrogen evolution reaction, respectively, with a Pt‐like performance, and Ni@CNx is the most active for oxygen evolution reaction (OER) with an EOER of 1.59 V versus RHE, far outperforming the commercial IrO2 (EOER = 1.72 V). This systematic and benchmarking study can serve as a basis for the future design of advanced multi‐functional electrocatalysts by modulating and combining the metallic nature of nanoclusters and single atoms.
Single atoms and nanoclusters of transition metals are embedded in a 2D carbon material (TM@CNx) through the introduction of the metal precursor in the well‐defined cavities of C1N1, followed by heat treatment. The TM@CNx exhibits high electrocatalytic performance for the oxygen reduction reaction, oxygen evolution reaction, or hydrogen evolution reaction, depending on the nature of the transition metal.
Challenging conventional wisdom that s‐block organometallic reagents such as Grignard or organolithiums need to be used under protecting inert atmosphere (N2 or Ar), employing dry organic solvents ...with a strict temperature control, this Minireview focusses on recent advances on the use of these commodity reagents while operating under air, at room temperature and in the presence of moisture. Key for the success of these approaches has been the use of the following sustainable solvents: i) water; ii) Deep Eutectic Solvents (DESs); or iii) biomass‐derived polyols (like glycerol) or ethereal solvents i. e., 2‐MeTHF or cyclopentyl methyl ether (CPME). The versatility of these air and moisture compatible synthetic protocols has been demonstrated for a myriad of key organic transformations, including nucleophilic additions of RLi/RMgX reagents to unsaturated organic molecules (i. e., ketones, imines, esters, amides or nitriles) as well as ortho‐ and lateral lithiation of aromatic substrates, Pd catalysed cross‐couplings and anionic polymerisation of styrenes. Extension of these studies to lithium amides (LiNR2) or phosphides (LiPPh2) has enabled the development of more sustainable and efficient methods for C−N and C−P bond forming processes. These unconventional s‐block metal mediated transformations have also been successfully incorporated in one‐pot tandem processes in combination with transition‐metal and organo‐catalysis. Remarkably, in some cases the conversions and chemoselectivities observed are superior to those detected in common toxic organic solvents, while working under inert atmosphere conditions with strict temperature control. The key role played by the choice of solvent in these transformations and how it can affect the constitution of the s‐block organometallic species present in solution is also discussed.
This Minireview showcases key advances on the use of polar s‐block organometallic reagents in bioinspired solvents water, glycerol and Deep Eutectic Solvents (DESs), under air, at room temperature and in the presence of moisture, a trio of conditions that for decades has been considered incompatible with the manipulation of these reagents.
This critical review covers advances in anion complexation chemistry related to receptors based on organic frameworks in the years 2005-2006. The review covers anion receptors that employ amides and ...thioamides, pyrroles and indoles, ureas and thioureas, ammonium, guanidinium, imidazolium, and receptors containing hydroxyl groups. There is a discussion of anion templated assembly, followed by a short section outlining modelling studies of these systems. (226 references.)
Aim
To assess the cytocompatibility and bioactive potential of the new calcium silicate cement‐based sealer AH Plus Bioceramic Sealer (AHPbcs) on human periodontal ligament stem cells (hPDLSCs) ...compared with the epoxy resin‐based sealer AH Plus (AHP) and the calcium silicate cement‐based sealer Endosequence BC Sealer (ESbcs).
Methodology
Standardized sample discs and 1:1, 1:2 and 1:4 eluates of the tested materials were prepared. The following assays were performed: surface element distribution via SEM–EDX, cell attachment and morphology via SEM, cell viability via a MTT assay, cell migration/proliferation via a wound‐healing assay, osteo/cemento/odontogenic marker expression via RT‐qPCR and cell mineralized nodule formation via Alizarin Red S staining. HPDLSCs were isolated from extracted third molars. Comparisons were made with hPDLSCs cultured in unconditioned (negative control) or osteogenic (positive control) culture media. Statistical significance was established at p < .05.
Results
A higher peak of Ca2+ was detected from ESbcs compared with AHPbcs and AHP in SEM–EDX. Both AHPbcs and ESbcs showed significantly positive results in the cytocompatibility assays (cell viability, migration/proliferation, attachment and morphology) compared with a negative control group, whilst AHP showed significant negative results. Both AHPbcs and ESbcs exhibited an upregulation of at least one osteo/odonto/cementogenic marker compared with the negative and positive control groups. Both ESbcs and AHPbcs showed a significantly higher calcified nodule formation than the negative and positive control groups, indicative of their biomineralization potential and were also significantly higher than AHP group.
Conclusion
AH Plus Bioceramic Sealer exhibited a significantly higher cytocompatibility and bioactive potential than AH Plus and a similar cytocompatibility to that of Endosequence BC Sealer. Endosequence BC Sealer exhibited a significantly higher mineralization potential than the other tested sealers. The results from this in vitro study act as supporting evidence for the use of AH Plus Bioceramic Sealer in root canal treatment.
The mechanistic analysis in heterogeneous catalysis is based on listing all elementary steps and evaluating explicitly their energies. To this end, computational models based on Density Functional ...Theory have become a standard to estimate the information needed in mechanistic studies. Typically, either the minimum energy paths or those with the smaller span are summarized in reaction profiles. Such simplifications gather a lot of information, although further dimensionality reduction is required to obtain the most relevant descriptors of catalytic activity and generate the so‐called volcano plots. The selection of descriptors has been traditionally based on simple intermediates, such as central atoms in small molecules (as C in CH4), which have good thermodynamic correlations to other fragments containing them. Yet, in emerging processes (recent studies), the number of intermediates involved increase, configurational effects and lateral interactions become significant, and complex materials with low symmetry are employed, thus the simple rules encapsulated in linear scaling relationships lose their predictive power due to error accumulation. At the same time, large datasets generated for the intermediates call for statistical analysis and thus these techniques are being leveraged to chemical systems, particularly to reduce their dimensionality.
This article is categorized under:
Structure and Mechanism > Reaction Mechanisms and Catalysis
Structure and Mechanism > Computational Materials Science
Electronic Structure Theory > Ab Initio Electronic Structure Methods
Summary of the new approaches needed in chemical network exploration to successfully process Density Functional Theory with statistical methods.
Computational chemistry is an indispensable tool for understanding molecules and predicting chemical properties. However, traditional computational methods face significant challenges due to the ...difficulty of solving the Schrödinger equations and the increasing computational cost with the size of the molecular system. In response, there has been a surge of interest in leveraging artificial intelligence (AI) and machine learning (ML) techniques to in silico experiments. Integrating AI and ML into computational chemistry increases the scalability and speed of the exploration of chemical space. However, challenges remain, particularly regarding the reproducibility and transferability of ML models. This review highlights the evolution of ML in learning from, complementing, or replacing traditional computational chemistry for energy and property predictions. Starting from models trained entirely on numerical data, a journey set forth toward the ideal model incorporating or learning the physical laws of quantum mechanics. This paper also reviews existing computational methods and ML models and their intertwining, outlines a roadmap for future research, and identifies areas for improvement and innovation. Ultimately, the goal is to develop AI architectures capable of predicting accurate and transferable solutions to the Schrödinger equation, thereby revolutionizing in silico experiments within chemistry and materials science.
This review examines the use of artificial intelligence (AI) and machine learning (ML) applications for computational chemistry, categorized by the degree of physical information deployed. It discusses the advantages, limitations, and future prospects for each model category toward the ultimate goal of defining the optimal architecture for AI to predict accurate, transferable, and reproducible solutions of the Schrödinger equations.
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