Search results for "Reactivity"
showing 10 items of 880 documents
Interface reactivity study between La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode material and metallic interconnect for fuel cell
2011
Abstract Interface reactivity between La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode material and metallic interconnect (Crofer22APU) was investigated in laboratory air at 700 °C. Due to the interconnect geometry, two interfaces have been analysed: (i) interconnect rib/cathode interface (physically in contact); (ii) the interface under the channel of interconnect. In both cases, formation of a parasite phase was observed after various ageing treatments (20 h, 100 h and 200 h). However, the growth of the determined SrCrO4 parasite phase depends on interface type and on ageing time. Two different mechanisms have been established in function of interface type: (i) SrCrO4 phase was formed after solid …
Integrating psychological and neurobiological considerations regarding the development and maintenance of specific Internet-use disorders: An Interac…
2016
Within the last two decades, many studies have addressed the clinical phenomenon of Internet-use disorders, with a particular focus on Internet-gaming disorder. Based on previous theoretical considerations and empirical findings, we suggest an Interaction of Person-Affect-Cognition-Execution (I-PACE) model of specific Internet-use disorders. The I-PACE model is a theoretical framework for the processes underlying the development and maintenance of an addictive use of certain Internet applications or sites promoting gaming, gambling, pornography viewing, shopping, or communication. The model is composed as a process model. Specific Internet-use disorders are considered to be the consequence …
Diels-Alder Reactions of (1H-Indol-3-yl)-enacetamides and -endiacetamides: A Selective Access to Acetylamino-Functionalized [b]Annelated Indoles and …
1991
Diels-Alder reactions of the (1H-indol-3-yl)-enacetamides and -endiacetamides 1a–d with some carbodieno-philes and 4-phenyl-3H-1,2,4-triazole-3,5(4H)-dione give rise to the novel amino-functionalized carbazole; 4–6 and 8 (Scheme 3). Ethenetetracarbonitrile reacts with 1b to furnish the Michael-type adduct 7 (Scheme 3). Structural aspects of the starting materials 1, which exhibit above all 3-vinyl-1H-indole reactivity, are discussed with regard to the prediction of a Diels-Alder process.
A Synthetic Model for the [4+2] Cycloaddition in the Biosynthesis of the Brevianamides, Paraherquamides, and Related Compounds
2000
Abstract The reactivity of model systems for the proposed [4+2] cycloaddition in the biosynthesis of the brevianamides, paraherquamides, and marcfortines is explored. The model for the intermolecular reaction reveals that the cycloaddition takes place under mild conditions only if activated, very reactive dienophiles are used. When relatively unreactive dienophiles such as cyclopentene and cyclohexene are used, harsh reaction conditions and/or a Lewis acid catalyst are necessary for the reaction. In contrast, the model for the intramolecular reaction demonstrates that the cycloaddition takes place within a few hours at room temperature, even in the absence of a Lewis acid catalyst. Conclusi…
N-heterocyclic carbenes and parent cations: acidity, nucleophilicity, stability, and hydrogen bonding-Electrochemical Study and ab initio calculations
2016
N-Heterocyclic carbenes (NHCs) are widely used as organocatalysts. Their reactivity (and instability) is related to their basicity and nucleophilicity, which, in turn, are linked to their scaffold. NHCs can be generated by chemical deprotonation or electrochemical reduction of the parent azolium cations, NHCH+s. Cyclic voltammetry enabled the reduction potential of the NHCH+s to be determined; the reduction potential is related to the acidity of the NHCH+s and the oxidation potential of the NHCs, which is related to the nucleophilicity of the NHCs. It was thus possible to order different NHCH+s and NHCs by their acidity and nucleophilicity, respectively. A study on the stability of NHCs was…
Radiation-Engineered Functional Nanoparticles in Aqueous Systems.
2015
Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic rout…
Effect of pistachio on brachial artery diameter and flow-mediated dilatation: A systematic review and meta-analysis of randomized, controlled-feeding…
2017
Background: Results of previous clinical trials evaluating the effect of pistachio supplementation on endothelial reactivity (ER) are controversial. Aims: We aimed to assess the impact of pistachio on ER through systematic review of literature and meta-analysis of available randomized, controlled-feeding clinical studies (RCTs). Methods: The literature search included SCOPUS, PubMed-Medline, ISI Web of Science and Google Scholar databases up to 1st August 2017 to identify RCTs investigating the impact of pistachio on ER. Two independent reviewers extracted data on study characteristics, methods and outcomes. Overall, the impact of pistachio on ER was reported in 4 trials. Results: The meta-…
Mechanisms and parameters controlling the tricalcium aluminate reactivity in the presence of gypsum.
2007
International audience; To understand the mechanisms and the parameters controlling the reactivity of tricalcium aluminate in the presence of gypsum at an early age, a study of the hydration of the “C3A–sulphate” system by isothermal microcalorimetry, conductimetry and a monitoring of the ionic concentrations of diluted system suspensions have been carried out with various gypsum quantities. The role of C3A source and its fineness were also studied. This work shows the fast initial formation of AFm phase followed by ettringite formation during the period when the sulphate is consumed. It has been highlighted that the time necessary to consume all the gypsum varies with the type of C3A and i…
The Role of Personal Biological Resource in the Job Demands-Control-Support Model: Evidence From Stress Reactivity.
2021
Job resources can buffer the deleterious effect of adverse work environments. Extant studies on the interaction pattern between job resources and adverse environments were confined to the diathesis stress model. This traditional perspective has received the challenge from the differential susceptibility model and the vantage sensitivity model. Additionally, stress reactivity may be one of the important job resources at the personal biological level, but its moderating role was short of empirical research. This study aimed to examine how stress reactivity interacts with work environments in predicting job burnouts among 341 Chinese hospital female nurses. This study selected job control and …
Protein Conformational Landscapes and Catalysis. Influence of Active Site Conformations in the Reaction Catalyzed by L-Lactate Dehydrogenase
2015
In the past decade, L-Lactate Dehydrogenase (LDH) has become an extremely useful marker in both clinical diagnosis and in monitoring the course of many human diseases. It has been assumed since the 1980s that the full catalytic process of LDH starts with the binding of the cofactor and the substrate followed by the enclosure of the active site by a mobile loop of the protein before the reaction takes place. In this paper, we show that the chemical step of the LDH-catalyzed reaction can proceed within the open loop conformation, and the different reactivity of the different protein conformations would be in agreement with the broad range of rate constants measured in single-molecule spectrom…