Polyoxometalates (POMs) and their hybrid systems are green and efficient catalysts which have found a wide range of application, due to their outstanding properties such as high thermal stability, Redox potential, strong Bronsted acidity, non-corrosive nature and sensitivity to electricity and light. They are able to catalyze various organic reactions as well as being involved in photocatalytic processes. In this review, we try to highlight the recent advances (2009)(2010)(2011)(2012)(2013)(2014)(2015) in the applications of POMs both in their actual structural forms and in the form of hybrid/ composite as catalysts in divergent chemical processes including, organic synthesis,biomass conversion, petrochemical processes, fuel cell, photocatalytic degradation.

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Using natural materials, i.e. halloysite nanoclay that is a biocompatible naturally occurring clay and Heracleum persicum extract that can serve as a green reducing agent, a novel magnetic catalyst, fe 3 o 4 / Hal-Mel-TEA(IL)-Pd, has been designed and fabricated. To prepare the catalyst, halloysite was first magnetized (magnetic particles with mean diameter of 13.06 ± 3.1 nm) and then surface functionalized with melamine, 1,4 dibromobutane and triethanolamine to provide ionic liquid on the halloysite surface (5 wt%). The latter was then used as a support to immobilize Pd nanoparticles that were reduced by Heracleum persicum extract. The characterization of the catalyst established that the loading of Pd in fe 3 o 4 /Hal-Mel-TEA(IL)-Pd was very low (0.93 wt%) and its specific surface area was 63 m 2 g −1 . Moreover, the catalyst showed magnetic property (Ms = 19.75 emu g −1 ) and could be magnetically separated from the reaction. The catalytic performance of the magnetic catalyst for reductive degradation of methyl orange and rhodamine B in the presence of NaBH 4 in aqueous media was investigated. The activation energy, enthalpy, and entropy for the reduction of methyl orange were estimated as 42.02 kJ mol −1 , 39.40 kJ mol −1 , and −139.06 J mol −1 K −1 , respectively. These values for rhodamine B were calculated as 39.97 kJ mol −1 , 34.33 kJ mol −1 , and −155.18 Jmol −1 K −1 , respectively. notably, fe 3 o 4 /Hal-Mel-TEA(IL)-Pd could be reused for eight reaction runs with negligible loss of the catalytic activity (~3%) and Pd leaching (0.01 wt% of the initial loading).Application of low-cost, biocompatible and available natural compounds for the catalytic purposes has attracted tremendous attention. In this regard, use of halloysite (Hal) that is a dioctahedral 1:1 clay of the kaolin group has received growing interest 1-3 . Apart from high thermal, chemical and mechanical stability, the cylindrical morphology and opposite chemical and electrical properties of inner and outer surfaces of Hal, make it distinguished from other clays and broaden its utility for many applications such as cleaning 4 , adsorbents 5,6 , energy storage, catalysis, flame retardancy 1 , sustainable release of drugs etc. Regarding catalysis, Hal not only can be utilized as a catalyst, but also can be applied as a support for the development of reusable catalysts. To date, various chemical, photochemical and electrochemical transformations such as coupling reactions 7,8 , hydrogenation 9,10 , oxidation have been promoted by using Hal-based catalysts [11][12][13][14][15] . Organic dyes such as methylene blue, rhodamine B (RhB) and methyl orange (MO) are toxic chemicals with potential health threat 16 . The release of these compounds in the industrial waste water has raised many concerns and motivated many studies for the efficient removal of these hazardous pollutants or their conversion into less toxic compounds 17,18 . In this context, several approaches, such as use of adsorbents, photodegradation, electrochemical degradations, membrane p...

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Social media has grown very quickly and has affected all dimensions of the world's community. The purpose of this article is to review valid articles on the relationship between social media and promotion using manual and bibliometrics analysis methods and identify top themes in these articles. We review the papers published between 2007 and the first month of 2019 in Scopus. 1,840 articles were published in the mentioned period. In this article, we review various charts including word dynamics, the contributions of different countries, country scientific production, corresponding author's country, the frequency distribution of sources, collaboration network and country collaboration map. The study indicates that Canada, Australia and France were the most productive countries in this area.

Cyclotriphosphazen-hexa imine ligand was prepared through successive reactions of phosphonitrilchloride trimer with 4-hydroxybenzaldehyde and (3-aminopropyl) triethoxy silane. The as-prepared ligand was then covalently grafted on boehmite to furnish an efficient support for the immobilization of Pd nanoparticles and synthesis of a novel heterogeneous catalyst for hydrogenation of nitro arenes. The catalytic tests revealed that the catalyst had excellent catalytic activity for hydrogenation of various nitro arenes with different steric and electronic features under mild reaction condition in aqueous media. Noteworthy, the catalyst was highly selective and in the substrates with ketone or aldehyde functionalities, reduction of nitro group was only observed. The catalyst was also recyclable and only slight loss of activity was detected after each recycling run. Hot filtration test also approved true heterogeneous nature of catalysis.

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