41 research outputs found

    Ionospheric Plasma Depletions at Mars Observed by the MAVEN spacecraft

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    The contents of the data files are linked to the plots of the manuscript, "Ionospheric Plasma Depletions at Mars Observed by the MAVEN spacecraft" by Praveen Basuvaraj, František Němec, Zdeněk Němeček and Jana Šafránková. A detailed description of the dataset is given in manuscript #2022JE007302 and the readme.txt in the repository. This includes the list of Plasma Depletion Events (PDEs) identified in the ionosphere of Mars from MAVEN NGIMS datasets between October 2014 and May 2021.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

    Mesoporous Microcapsules through d‑Glucose Promoted Hydrothermal Self-Assembly of Colloidal Silica: Reusable Catalytic Containers for Palladium Catalyzed Hydrogenation Reactions

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    A facile methodology is reported to fabricate hierarchically ordered silica nanoassembled microcapsules (SiO<sub>2</sub> NACs) with tailored mesopores by combining polymerization of d-glucose with self-assembly of colloidal silica nanoparticles (SiO<sub>2</sub> NPs). This controlled self-assembly of SiO<sub>2</sub> NPs during a hydrothermal process enables the formation of core–shell (organic/inorganic) hybrid microspheres of carbon and SiO<sub>2</sub> NPs. After removal of carbon, spherical hollow SiO<sub>2</sub> NACs are formed having mesopores and their surface area was observed as 248 m<sup>2</sup>/g. The synthesized mesoporous SiO<sub>2</sub> NACs can be effectively used to encapsulate palladium nanoparticles (Pd NPs) to act as a heterogeneous catalyst in hydrogenation reactions. The position of Pd NPs in SiO<sub>2</sub> NACs (either inside the nanopores or throughout the wall of the capsules) can be dictated by the method of encapsulation which can impart selectivity in hydrogenation of various nitroaromatic compounds, alkyne, and alkenes. The advantages of our catalytic system are greener synthesis of catalyst, that lower Pd content (0.3 mol %) was utilized for the catalytic hydrogenation reaction, heterogeneous nature and reusability

    Fabrication of Pd Nanoparticles Embedded C@Fe<sub>3</sub>O<sub>4</sub> Core–Shell Hybrid Nanospheres: An Efficient Catalyst for Cyanation in Aryl Halides

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    Isolated chemical reactors were fabricated by integrating catalytically active sites (Pd) with magnetic functionality (Fe<sub>3</sub>O<sub>4</sub>) along with carbon while preserving the constituents functional properties to realize the structure–property relationship of Pd by comparing the catalytic activity of spherical Pd NPs with cubical Pd NPs for cyanation in aryl halides using K<sub>4</sub>[Fe­(CN)<sub>6</sub>] as a green cyanating agent to yield corresponding nitriles. The superior catalytic reactivity of the cubical Pd NPs is attributed to the larger number of {100} surface facets. The TEM images of reused catalyst shows the change in structure from cubical to spherical nanoparticles, attributed to the efficient leaching susceptibility of Pd {100} surface facets. The cubical Pd NPs on carbon@Fe<sub>3</sub>O<sub>4</sub> is attractive in view of its high catalytic efficiency, easy synthesis, magnetic separability, environmental friendliness, high stability, gram scale applicability, and reusability

    Synthesis, Characterization, and DNA Binding Studies of Nanoplumbagin

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    The traditional anticancer medicine plumbagin (PLN) was prepared as nanostructured material (nanoplumbagin, NPn1) from its commercial counterparts, simultaneously coencapsulating with cetyltrimethylammonium bromide or cyclodextrin as stabilizers using ultrasonication technique. Surface morphology of NPn analysed from atomic force microscopy (AFM) indicates that NPn has tunable size between 75 nm and 100 nm with narrow particle size distribution. Its binding efficiency with herring sperm DNA was studied using spectral and electrochemical techniques and its efficiency was found to be more compared to the commercial microcrystalline plumbagin (PLN). DNA cleavage was also studied by gel electrophoresis. The observed results indicate that NPn1 has better solubility in aqueous medium and hence showed better bioavailability compared to its commercial counterparts

    Ultrafine Bimetallic PdCo Alloy Nanoparticles on Hollow Carbon Capsules: An Efficient Heterogeneous Catalyst for Transfer Hydrogenation of Carbonyl Compounds

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    Monodispersed ultrafine bimetallic palladium–cobalt alloy nanoparticles (Pd<sub><i>x</i></sub>Co<sub><i>y</i></sub>) are prepared and immobilized on hollow carbon capsules (HCCs). Studies on the effect of metal composition on the catalytic activity of the Pd<sub><i>x</i></sub>Co<sub><i>y</i></sub> reveal that the nanoparticulate alloy with the atomic composition of Pd<sub>36</sub>Co<sub>64</sub> is more active than the Co and Pd monometallic nanoparticles in the transfer hydrogenation of carbonyl compounds. The composition of the catalyst and its alloy formation are extensively characterized, and a variety of ketones and aldehydes are hydrogenated successfully with excellent yield and high turnover number (TON), displaying the ability of the synthesized ultrafine Pd<sub>36</sub>Co<sub>64</sub> bimetallic nanoalloy to attain and retain both high catalytic activity and stability. This catalytic system is heterogeneous, stable and does not require additives for activation. Other advantages include milder reaction conditions (does not use gaseous hydrogen), low metal content (0.17 mol %) for a catalytic transfer hydrogenation reaction, functional group tolerance, environmentally benign nature, and reusability
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