Scalable Synthesis of Norbornadienes via in situ Cracking of Dicyclopentadiene Using Continuous Flow Chemistry

The norbornadiene (NBD)-quadricyclane (QC) photoswitch has recently attracted attention due to its use in molecular solar thermal energy systems (MOST). Normally for device testing, several grams are needed. One way of synthesizing NBDs efficiently is through the Diels-Alder reaction between alkynes and cyclopentadiene. However, scaling up the reaction can be troublesome in a research lab environment. Also, dicyclopentadiene needs cracking before utilization which is a time-consuming step. Here, we developed a method where we both scale up the synthesis in a single reaction step that involves both in situ cracking of dicyclopentadiene and the direct reaction of cyclopentadiene with acetylene derivatives using a tubular coiled stainless steel flow reactor. As a proof-of-concept, we synthesized six different NBD compounds and scaled the synthesis to produce 87 g of a novel NBD in 9 h. The NBD is further characterized, showing promising properties for MOST applications. Our new method shows that flow chemistry is an attractive technique for the fast and efficient synthesis of large quantities of NBDs, needed to develop future real-life devices and applications

High Stabilization of Enzymes Immobilized on Rigid Hydrophobic Glyoxyl-Supports: Generation of Hydrophilic Environments on Support Surfaces

© 2020 by the authors.Very rigid supports are useful for enzyme immobilization to design continuous flow reactors and/or to work in non-conventional media. Among them, epoxy-methacrylic supports are easily functionalized with glyoxyl groups, which makes them ideal candidates for enzyme stabilization via multipoint covalent immobilization. However, these supports present highly hydrophobic surfaces, which might promote very undesirable effects on enzyme activity and/or stability. The hydrophilization of the support surface after multipoint enzyme immobilization is proposed here as an alternative to reduce these undesirable effects. The remaining aldehyde groups on the support are modified with aminated hydrophilic small molecules (glycine, lysine or aspartic acid) in the presence of 2-picoline borane. The penicillin G acylase from Escherichia coli (PGA) and alcohol dehydrogenase from Thermus thermophilus HB27 (ADH2) were immobilized on glyoxyl-functionalized agarose, Relizyme and Relisorb. Despite the similar density of aldehyde groups displayed by functionalized supports, their stabilization effects on immobilized enzymes were quite different: up to 300-fold lower by hydrophobic supports than by highly hydrophilic glyoxyl-agarose. A dramatic increase in the protein stabilities was shown when a hydrophilization treatment of the hydrophobic support surface was done. The PGA immobilized on the glyoxyl-Relisorb hydrophilized with aspartic acid becomes 280-fold more stable than without any treatment, and it is even more stable than the PGA immobilized on the glyoxyl agarose.This research was funded by the Spanish Ministry of Economy, Industry and Competitiveness (projects BIO2012-36861 and CTQ2015-70348) and the EU FP7 project SuSy (Sucrose Synthase as Cost-Effective Mediator of Glycosylation Reactions, C-KBBE/3293). Javier Rocha-Martin is grateful for the Juan de la Cierva fellowship (IJCI-2014-19260) funded by the Spanish Ministry of Economy, Industry and Competitiveness.Peer reviewe

Prevalencia de bovinos reactores a la prueba de Bang en Aguadas.

Un estudio de prevalencia de reactores positivos a la seroaglutinación de Bang, fue llevado a cabo en bovinos del municipio de Aguadas (Caldas), en una zona donde la ganadería es de tipo carne, en áreas extensas con buena calidad de ganado, y donde nunca se ha vacunado contra brucelosis. El tamaño de la muestra se determinó mediante la utilización del modelo 3 del Centro Panamericano de Zoonosis, para el estudio de prevalencia de enfermedades crónicas. El tamaño n de la muestra fue 322, presumiendo una prevalencia crítica del 1 por ciento y un nivel de confianza del 95 por ciento. La prevalencia obtenida fue de 2.79 por ciento con una desviación standar del 0.918 por ciento. Se concluyó que la prevalencia de reactores positivos a la seroaglutinación de Bang en el área estudiada fue superior al establecido en la hipótesis principal del proyecto, y que se debe establecer un programa de control de brucelosis a largo plazo con miras a su erradicaciónGanadería bovin

Synthesis of highly monodisperse Pd nanoparticles using a binary surfactant combination and sodium oleate as a reductant

This study presents the synthesis of monodisperse Pd nanoparticles (NPs) stabilized by sodium oleate (NaOL) and hexadecyltrimethylammonium chloride (CTAC). The synthesis was conducted without traditional reductants and Pd-precursors are reduced by NaOL. It was confirmed that the alkyl double bond in NaOL is not the only explanation for the reduction of Pd-precursors since Pd NPs could be synthesized with CTAC and the saturated fatty acid sodium stearate (NaST). A quantitative evaluation of the reduction kinetics using UV-Vis spectroscopy shows that Pd NPs synthesized with both stabilizer combinations follow pseudo first-order reaction kinetics, where NaOL provides a faster and more effective reduction of Pd-precursors. The colloidal stabilization of the NP surface by CTAC and NaOL is confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analysis

Thermo-optical performance of molecular solar thermal energy storage films

Due to their potential for solar energy harvesting and storage, molecular solar thermal energy storage (MOST) materials are receiving wide attention from both the research community and the public. MOST materials absorb photons and convert their energy to chemical energy, which is contained within the bonds of the MOST molecules. Depending on the molecular structure, these materials can store up to 1 MJ/kg, at ambient temperature and with storage times ranging from minutes to several years. This work is the first to thoroughly investigate the potential of MOST materials for the development of energy saving windows. To this end, the MOST molecules are integrated into thin, optically transparent films, which store solar energy during the daytime and release heat at a later point in time. A combined experimental and modeling approach is used to verify the system\u27s basic functionality and identify key parameters. Multi-physics modeling and simulation were conducted to evaluate the interaction of MOST films with light, both monochromatic and the entire solar spectrum, as well as the corresponding dynamic energy storage. The model was experimentally verified by studying the optical response of thin MOST films containing norbornadiene derivatives as a functional system. We found that the MOST films act as excellent UV shield and can store up to 0.37 kWh/m2 for optimized MOST molecules. Further, this model allowed us to screen various material parameters and develop guidelines on how to optimize the performance of MOST window films

Las clases de ciencias e intereses de aprendizaje, estudiantes de octavo grado de la educación básica secundaria

Esta comunicación expone los resultados del trabajo de investigación “Interés sobre la ciencia que manifiestan los estudiantes del nivel octavo de la básica secundaria, de una Institución Educativa oficial, la investigación busca indagar cuáles son los intereses de esta población. Utiliza como técnica de investigación los cuestionarios tipo Likert del estudio comparativo ROSE: Mis clases de ciencias y ¿sobre qué me gustaría aprender? La metodología del trabajo es descriptiva exploratoria, participaron 162 estudiantes – hombres. Algunos de los resultados indican que, a pesar de mostrar tendencia a estar de acuerdo con los ítems que caracterizan las clases de ciencia, marcan un mayor desacuerdo por el gusto de convertirse en científico; en cuanto a intereses de aprendizaje hay variaciones significativas incluso en la población de la misma edad