Confined Ionic Environments Tailoring the Reactivity of Molecules in the Micropores of BEA-Type Zeolite.

In the presence of water, hydronium ions formed within the micropores of zeolite H-BEA significantly influence the surrounding environment and the reactivity of organic substrates. The positive charge of these ions, coupled with the zeolite's negatively charged framework, results in an ionic environment that causes a strongly nonideal solvation behavior of cyclohexanol. This leads to a significantly higher excess chemical potential in the initial state and stabilizes at the same time the charged transition state in the dehydration of cyclohexanol. As a result, the free-energy barrier of the reaction is lowered, leading to a marked increase in the reaction rates. Nonetheless, there is a limit to the reaction rate enhancement by the hydronium ion concentration. Experiments conducted with low concentrations of reactants show that beyond an optimal concentration, the required spatial rearrangement between hydronium ions and cyclohexanols inhibits further increases in the reaction rate, leading to a peak in the intrinsic activity of hydronium ions. The quantification of excess chemical potential in both initial and transition states for zeolites H-BEA, along with findings from HMFI, provides a basis to generalize and predict rates for hydronium-ion-catalyzed dehydration reactions in Brønsted zeolites.

Survey-Based Assessment of the Quality of Reporting Guidelines of Carotid Artery Stenosis.

BACKGROUND: No evaluation of the quality of different carotid guidelines using validated scales has been performed to date. The present study aims to analyze 3 carotid stenosis guidelines, apprizing their quality and reporting using validated tools. METHODS: A survey-based assessment of the quality of the European Society for Vascular Surgery (ESVS) 2023, European Stroke Organisation (ESO) 2021, and the Society for Vascular Surgery (SVS) 2021 carotid stenosis guidelines, was performed by 43 vascular surgeons, cardiologists, neurologist or interventional radiologists using 2 validated appraisal tools for quality and reporting guidelines, the AGREE II instrument and the RIGHT statement. RESULTS: Using the AGREE II tool, the ESVS, SVS, and ESO guidelines had overall quality scores of 87.3%, 79.4%, and 82.9%, respectively (P = 0.001) The ESVS and ESO had better scores in the scope and purpose domain, and the SVS in the clarity of presentation domain. In the RIGHT statement, the ESVS, SVS, and ESO guidelines had overall quality scores of 84.0.7%, 74.3%, and 79.0%, respectively (P = 0.001). All 3 guidelines stood out for their methodology for search of evidence and formulating evidence-based recommendations. On the contrary, were negatively evaluated mostly in the cost and resource implications in formulating the recommendations. CONCLUSIONS: The 2023 ESVS carotid stenosis guideline was the best evaluated among the 3 guidelines, with scores over 5% higher than the other 2 guidelines. Efforts should be made by guideline writing committees to take the AGREE II and RIGHT statements into account in the development of future guidelines to produce high-quality recommendations.

Active species in chloroaluminate ionic liquids catalyzing low-temperature polyolefin deconstruction.

Chloroaluminate ionic liquids selectively transform (waste) polyolefins into gasoline-range alkanes through tandem cracking-alkylation at temperatures below 100 °C. Further improvement of this process necessitates a deep understanding of the nature of the catalytically active species and the correlated performance in the catalyzing critical reactions for the tandem polyolefin deconstruction with isoalkanes at low temperatures. Here, we address this requirement by determining the nuclearity of the chloroaluminate ions and their interactions with reaction intermediates, combining in situ 27Al magic-angle spinning nuclear magnetic resonance spectroscopy, in situ Raman spectroscopy, Al K-edge X-ray absorption near edge structure spectroscopy, and catalytic activity measurement. Cracking and alkylation are facilitated by carbenium ions initiated by AlCl3-tert-butyl chloride (TBC) adducts, which are formed by the dissociation of Al2Cl7- in the presence of TBC. The carbenium ions activate the alkane polymer strands and advance the alkylation cycle through multiple hydride transfer reactions. In situ 1H NMR and operando infrared spectroscopy demonstrate that the cracking and alkylation processes occur synchronously; alkenes formed during cracking are rapidly incorporated into the carbenium ion-mediated alkylation cycle. The conclusions are further supported by ab initio molecular dynamics simulations coupled with an enhanced sampling method, and model experiments using n-hexadecane as a feed.

Síndrome de Lemierre / Lemierre syndrome

La sepsis postanginal o síndrome de Lemierre es una enfermedad rara en nuestros tiempos que ocurre después de una infección orofaríngea y se manifiesta por una tromboflebitis séptica de la vena yugular interna e infecciones metastásicas. Es producida por microorganismos anaerobios, siendo el Fusobacterium necrophorum el más frecuente. Para su diagnóstico, a parte del aislamiento microbiológico del germen, son fundamentales las pruebas de imagen como la ecografía doppler y la tomografía axial computarizada (TAC). El tratamiento consiste en antibioterapia precoz, prolongada, a dosis altas y en ocasiones la excisión quirúrgica de las venas yugulares

Postanginal sepsis or Lemierre syndrome is a rare disease in our times that occurs after an oropharyngeal infection and is manifested by septic thrombophlebitis of the internal jugular vein and metastatic infections. It is produced by anaerobic germs, Fusobacterium necrophorum being the most frequent. Besides the microbiological isolation of the germ, image tests such as Doppler ultrasound and computed-tomography (CT) scan are fundamental for its diagnosis. Treatment consists in early, prolonged antibiotic treatment at high doses and sometimes surgical excision of the jugular veins. We present the case of an adolescent who had serious septic shock that evolved to multiorganic failure after being diagnosed of this syndrome. As a special finding, we discovered the presence of thrombosis in the left external jugular vein

Neumonía grave por varicela / Severe chickenpox pneumonia

Objetivo. Estudio retrospectivo de los datos epidemiológicos, clínicos, diagnósticos y terapéuticos de los pacientes adultos con neumonía por varicela que precisaron ingreso en la Unidad de Medicina Intensiva (UMI) en los últimos 10 años. Material y métodos. El diagnóstico se estableció por criterios clinicorradiológicos en el curso de una varicela. Se valoraron datos como enfermedades de base, embarazo, hábito tabáquico, datos analíticos, evolución a síndrome de distrés respiratorio del adulto (SDRA), necesidad de ventilación mecánica y tratamiento farmacológico. Resultados. Se estudiaron 8 pacientes (7 mujeres y 1 hombre) con una edad media de 30 años (rango: 25-38). Sólo uno de los pacientes presentaba patología subyacente (hepatitis B crónica y alcoholismo) y otra estaba embarazada de 24 semanas. Todos eran fumadores. Los síntomas respiratorios aparecieron entre el segundo y cuarto día de iniciarse el exantema. Todos presentaron disnea y en 7 de ellos se asoció tos seca. La radiografía de tórax al ingreso presentaba en todos los pacientes un infiltrado intersticial de predominio bibasal. En 7 de los 8 casos se observó menos de 150.000 plaquetas/mm3, en 5 aumento de transaminasas y en todos elevación de la deshidrogenasa láctica (LDH). En 6 pacientes se objetivó hipoxemia (PaO2 < 60 mmHg), precisando 3 de ellos intubación orotraqueal y ventilación mecánica. Estos 3 pacientes evolucionaron a SDRA. Todos los casos estudiados fueron tratados con aciclovir intravenoso. No falleció ninguno de los pacientes ingresados. Conclusiones. La neumonía por varicela es una complicación grave que puede precisar ingreso en UMI. La gravedad de la enfermedad puede variar desde anormalidades radiológicas asintomáticas hasta SDRA. La mortalidad es alta, pero está disminuyendo en los últimos años probablemente debido al tratamiento antivírico precoz y a las adecuadas medidas de soporte (AU)