Développement de nouveaux sels d’imidazolium : application du milieu cristal liquide ionique pour la réaction de Diels-Alder Intramoléculaire et à la préparation des nanoparticules d’Or Anisotropes

Les liquides ioniques à base de sels d’imidazolium sont une classe très importante de composés, compatibles avec de nombreuses réactions organiques et largement employés dans la synthèse organique en tant que solvants, catalyseurs ou ligands. En particulier, les liquides ioniques peuvent être récupérés à la fin de la réaction. Les sels d’imidazolium présentent également des propriétés d’organisation intéressantes, aussi bien en phase solide, liquide et en solution. Cependant, les liquides ioniques traditionnels présentent certains désavantages lorsqu’utilisés comme solvant dans des réactions intramoléculaires, surtout dans le cas où le réactif est apolaire. La faible solubilité de ce dernier dans le milieu ionique conduit à la formation des produits intermoléculaires. Les travaux présentés dans cette thèse portent sur l’utilisation des propriétés d’organisation des sels d’imidazolium, tout d’abord pour le développement des nouveaux cristaux liquides ioniques, comme le milieu réactionnel pour la réaction de Diels-Alder intramoléculaire, et ensuite pour la préparation des nanparticules d’or anisotropes. Dans un premier temps, le développement des sels d’imidazolium dicationiques portant des chaînes alkyles flexibles et un cœur rigide, avec des unités imidazolium attachées directement à un noyau naphthalène est rapporté. Par la suite, leurs propriétés thermiques et mésomorphes ont été étudiées. Ces sels sont stables thermiquement et forment une phase cristal liquide de type Smectique T, sur une plage de températures appropriées pour des réactions organiques. En utilisant le milieu cristal liquide comme milieu réactionnel dans la réaction de Diels-Alder, le réactif a été piégé dans la structure organisée de cette phase, ce qui a empêché l’interaction entre deux molecules de réactifs, limitant la formation du produit intermoléculaire. D’ailleurs, le milieu cristal liquide ionique a pu être récupéré et reutilisé à la fin de la réaction. Dans un deuxième temps, l’influence de la structure de la mésophase sur la réaction de Diels-Alder intramoléculaire a été étudiée. Des sels d’imidazolium tricationiques ayant une symétrie C3 ont ete développés dans le but d’obtenir des phases colonnaires. Ces sels possèdent un cœur rigide formé par trois cations imidazolium liés à un noyau benzène et des chaînes alkyles flexibles. Des études thermiques et mésomorphes sur ces composés ont été ensuite réalisées. Ces composés possèdent une haute stabilité thermique et forment une phase colonnaire rectangulaire, stable sur une large gamme de températures. L’influence de cette phase sur la réaction de Diels-Alder a ete étudiée. L’utilisation de la phase colonnaire favorise également la réaction intramoléculaire. En particulier, elle s’est avèree plus efficace que la phase Smectique T, probablement dû à sa structure plus organisée, indiquée par une enthalpie de tranisition cristal liquide – liquide isotrope plus élevée. Dans un dernier temps, nous nous sommes intéressés à l’utilisation des propriétés d’organisation des sels d’imidazolium dans la préparation des nanoparticules d’or anisotropes. Dans cette optique, différents mélanges binaires, composés d’un sel d’imidazolium et le diméthylformamide (DMF), ont été préparés et utilisés comme solvants et stabilisants, dans la synthèse des nanoparticules d’or à température ambiante. L’utilisation de ces milieux nous a permis d’obtenir des particules d’or avec différentes géométries. La forme des nanoparticules d’or obtenus dépend de la structure des sels d’imidazolium utilisés et de la concentration du mélange binaire, à la fois.Ionic liquids based on imidazolium salts are an important class of compounds, possessing a very good compatibility with various organic reactions, and are widely used as solvents, catalysts and ligands in organic synthesis. Moreover, imidazolium salts possess interesting supramolecular organization in the solid, liquid and solution state. However, ionic liquids present some disadvantages when used as solvents for intramolecular reactions, especially in the case of apolar reactants. The low solubility of ionic compounds in ionic media promote the formation of intermolecular products. The main goal of the research presented in this thesis is to explore the supramolecular organization of imidazolium salts, first in the development of ionic liquid crystals as reaction media for intramolecular Diels-Alder reactions and secondly for the preparation of anisotropic gold nanoparticles. First, the development of dicationic imidazolium salts having a rigid core and flexible alkyl chains is reported. The rigid core is forned by direct attachment of two imidazoliums on a naphthalene moiety. Their thermal and mesomorphic analyses were then carried out. These dicationic salts show a high thermal stability and form a very ordered smectic T phase, over a wide range of temperatures. This mesophase was subsequently used as reaction medium for intramolecular Diels-Alder reactions. In this phase, reactants are trapped in the highly organized structure of the liquid crystal medium, limiting the formation of intermolecular products. Moreover, the ionic liquid crystal, was recoved at the end of reaction by simple extraction. Secondly, the influence of the mesophase’s structure on the Diels-Alder reaction was explored. Tricationic imidazolium satls having a C3 symmetry were developed in order to obtain columnar phases. The rigid core of these salts is composed of three imidazolium units directly attached to the benzene ring. Their thermal stabilities and mesomorphic properties were investigated. The columnar phase formed by these salts was then used as reaction media for Diels-Alder reactions, and it proved to be more efficient than the previously used smectic T phase, due to their more organized structure, as indicated by the higher enthalpy value of the liquid crystal - isotropic liquid transition. iv Finally, the supramolecular organization in solution of two imidazolium salts was explored with the aim to prepare anisotropic gold nanoparticles. Different binary mixtures composed of an imidazolium salt and dimethylformamide (DMF) were prepared and used both as solvent and capping agent in the synthesis of gold nanoparticles, at room temperature. The use of these binary mixture allowed us to synthesize nanoparticles with various geometries. The form of the gold nanoparticles prepared in these binary mixtures was influenced by both, the structre and the concentration of the imidazolium salt used

Drama with Unique Setting and Profession based on the Point of View of Korean Drama Connoisseurs

This article aims to discuss K-Drama with a unique work profession background through the abstinence point of k-drama fans. The modern Korean entertainment landscape would not be complete without K-drama. Millions of people around the world enjoy watching Korean dramas. Many parallels are made between the characters, allowing viewers to gain a better understanding of Korean culture. K-drama fans will be paired with Korean drama works to write here. They are not your ordinary doctors, lawyers or professors, but people from all walks of lif

HOMOE: A Memory-Based and Composition-Aware Framework for Zero-Shot Learning with Hopfield Network and Soft Mixture of Experts

Compositional Zero-Shot Learning (CZSL) has emerged as an essential paradigm in machine learning, aiming to overcome the constraints of traditional zero-shot learning by incorporating compositional thinking into its methodology. Conventional zero-shot learning has difficulty managing unfamiliar combinations of seen and unseen classes because it depends on pre-defined class embeddings. In contrast, Compositional Zero-Shot Learning uses the inherent hierarchies and structural connections among classes, creating new class representations by combining attributes, components, or other semantic elements. In our paper, we propose a novel framework that for the first time combines the Modern Hopfield Network with a Mixture of Experts (HOMOE) to classify the compositions of previously unseen objects. Specifically, the Modern Hopfield Network creates a memory that stores label prototypes and identifies relevant labels for a given input image. Following this, the Mixture of Expert models integrates the image with the fitting prototype to produce the final composition classification. Our approach achieves SOTA performance on several benchmarks, including MIT-States and UT-Zappos. We also examine how each component contributes to improved generalization

Free vibration of functionally graded sandwich plates with stiffeners based on the third-order shear deformation theory

In this paper, the free vibration of functionally  sandwich grades plates with stiffeners is investigated by using the finite  element method. The material properties are assumed to be graded in the  thickness direction by a power-law distribution. Based on the third-order  shear deformation theory, the governing equations of motion are derived from  the Hamilton's principle. A parametric study is carried out to highlight the  effect of material distribution, stiffener parameters on the free  vibration characteristics of the plates

Extracting Conditions Optimization and Bioactivity of Polysaccharides from the Pods of Haricot Vert

Polysaccharides from the pods of haricot vert (Phaseolus vulgaris L.) were extracted using a simple heating method, by varying extracting temperature, heating time, solid-to-liquid ratio, and solvent compositions. The obtained results were processed using statistical analysis that helped to identify the optimal conditions for the polysaccharides’ extraction process. This study represents a promising production method of bioactive polysaccharides extract in the food and pharmaceutical industry

Investigation of anti-inflammatory lignans from the leaves of Symplocos sumuntia Buch-Ham ex D Don (Symplocaceae)

Purpose: To investigate the anti-inflammatory activity of Symplocos sumuntia Buch.-Ham. ex D. Don and identify the main secondary metabolites responsible for this effect.Methods: The in vitro anti-inflammatory activity of the plant extract and isolated compounds was determined in terms of the ability to inhibit the production of nitric oxide (NO), and expressions of iNOS and COX-2 proteins in RAW264.7 cells stimulated by lipopolysaccharide (LPS). Compounds were isolated and identified by spectroscopic methods.Results: The methanol extract of S. sumuntia leaves showed strong inhibitory effects on nitric oxide (NO) production and expression of iNOS and COX-2 in LPS-induced RAW264.7 cells. A phytochemical assay-guided fractionation of the methanol extract of S. sumuntia leaves led to the isolation of four lignans which are arctigenin (1), matairesinol (2), monomethylpinoresinol (3) and pinoresinol (4). These compounds were identified for the first time from S. sumuntia. All four compounds inhibited the production of nitric oxide (NO), with arctigenin showing the most potent activity with half-maximal inhibitory concentration (IC50) value of 4.08 μM.Conclusion: S. sumuntia is a promising source of anti-inflammatory agents, which may clarify to the therapeutic use of this plant in Vietamese traditional medicine.Keywords: Symplocos sumuntia, Symplocos caudata, Lignan, Arctigenin, Anti-inflammator

Fractional flow reserve in assessment of intermediate non-culprit lesions in acute myocardial infarction

Context: Percutaneous coronary intervention (PCI) of intermediate non-culprit arteries can reduce death or heart attack risk in patients with acute myocardial infarction and multivessel coronary artery disease. Aims: To compare the effectiveness of fractional flow reserve (FFR)-guided PCI with angiography-guided PCI for intermediate non-culprit lesions in patients with acute myocardial infarction and multivessel coronary artery disease. Methods: In this cohort study, acute myocardial infarction patients with multivessel coronary artery disease who had successful percutaneous coronary intervention of the culprit artery were divided into group of patients receiving FFR-guided PCI (FFR≤0.80, n = 31) and group of patients receiving angiography-guided PCI (diameter stenosis of 50-90%, n = 62) for lesions in non-culprit arteries. These two groups were followed for at least 1 year for major adverse cardiovascular events. Results: There was no statistically significant difference in major cardiovascular events between FFR-guided percutaneous coronary intervention group and angiography-guided percutaneous coronary intervention group. However, FFR-guided percutaneous coronary intervention group had a lower mortality rate compared to the angiography-guided percutaneous coronary intervention group (3.2% vs. 4.8%). Additionally, there were no reported cases of myocardial infarction in angiography-guided PCI group, while angiography-guided PCI group had a rate of 1.6%. Conclusions: This study found that it remains uncertain whether FFR-guided PCI is superior than angiography-guided PCI for intermediate non-culprit lesions in patients with acute myocardial infarction and multivessel coronary artery disease

PSSA- INTERNATIONAL SOLUTION TO PROTECT THE BIODIVERSITY IN HA LONG BAY - CAT BA MARINE AREA

A Particularly Sensitive Sea Area (PSSA) is an important management tool for biodiversity protection of a marine area. At the time of designation of a Particularly Sensitive Sea Area, an associated protective measure, which meets the requirements of the appropriate legal instrument establishing such measure, must have been approved or adopted by IMO to prevent, reduce, or eliminate the threat or identified vulnerability. Information on each of the Particularly Sensitive Sea Areas (PSSAs) that has been designated by IMO is available on the nautical chart. The Vietnam’s coastal zones and islands are the isolated oceanic habitat of extremely rich marine life in very good condition which is important to the maintenance and dispersal of the marine life of the western tropical Pacific. Vietnam coastal areas are very high risk areas affected by maritime activities, particularly international shipping, therefore in the future identification of some Particularly Sensitive Sea Areas (PSSAs) is necessary. The first Particularly Sensitive Sea Area for Vietnam in Ha Long - Cat Ba was initially proposed in this paper

Chemical composition and cytotoxic activity of the essential oils of Cymbopogon citratus L. Grown in phu tho province

Culms and leaves of Cymbopogon citratus L. were collected from two regions of Phu Tho province (Thanh Son and Phu Ninh) and used as materials for essential oil extraction. Oils obtained were steam-distilled, analyzed for chemical composition and evaluated for cytotoxic activity against three different cancer cell lines. The GC/MS analysis showed that citral is the major content of the steam-distilled essential oils which was found in the range of 64.15-76.22%. Camphene was found only in culm oils of both regions but it was not detected in the leaf oils. Interestingly, the isomer forms of ocimene present at higher content in the culm oils than in the leaf oils whereas myrcene content in the leaf oils is higher than that in the culm oils. In a cytotoxicity test, four essential oils of culms and leaves of C. citratus from Thanh Son and Phu Ninh showed potent activity against A549 (human lung carcinoma) cell line with the IC50 values ranging from 4.01±0.39 to 6.3±0.54 µg/ml. The essential oils (culms and leaves) from Phu Ninh exhibited moderate effects on the Hela (human cervical adenocarcinoma) cells with the IC50 values of 19.43±1.16 and 42±2.41 µg/ml, respectively. However, they were inactive against the human hepatocellular carcinoma Hep3B cell line. The essential oils from Thanh Son exhibited potent cytotoxic activity against Hela and Hep3B cell lines with the IC50 values ranging from 1.18±0.26 to 8.91±0.32 µg/ml. The results indicated that the essential oils of C. citratus from Thanh Son, Phu Tho could be considered as a promising candidate for the natural sources of anticancer agents

Penicillium digitatum as a Model Fungus for Detecting Antifungal Activity of Botanicals: An Evaluation on Vietnamese Medicinal Plant Extracts.

peer reviewedMedicinal plants play important roles in traditional medicine, and numerous compounds among them have been recognized for their antimicrobial activity. However, little is known about the potential of Vietnamese medicinal plants for antifungal activity. In this study, we examined the antagonistic activity of twelve medicinal plant species collected in Northern Vietnam against Penicillium digitatum, Aspergillus flavus, Aspergillus fumigatus, and Candida albicans. The results showed that the antifungal activities of the crude extracts from Mahonia bealei, Ficus semicordata, and Gnetum montanum were clearly detected with the citrus postharvest pathogen P. digitatum. These extracts could fully inhibit the growth of P. digitatum on the agar medium, and on the infected citrus fruits at concentrations of 300-1000 µg/mL. Meanwhile, the other tested fungi were less sensitive to the antagonistic activity of the plant extracts. In particular, we found that the ethanolic extract of M. bealei displayed a broad-spectrum antifungal activity against all four pathogenic fungi. Analysis of this crude extract by enrichment coupled with high-performance liquid chromatography revealed that berberine and palmatine are major metabolites. Additional inspections indicated berberine as the key compound responsible for the antifungal activity of the M. bealei ethanolic extract. Our study provides a better understanding of the potential of Vietnamese medicinal plant resources for combating fungal pathogens. This work also highlights that the citrus pathogen P. digitatum can be employed as a model fungus for screening the antifungal activity of botanicals