Experimental investigation for stability and surface properties of TiO2 and Al2O3 water-based nanofluids

Journal of Thermal Analysis and Calorimetry - Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport,...     

Development of a new catalytic and sustainable methodology for the synthesis of benzodiazepine triazole scaffold using magnetically separable CuFe2O4@MIL-101(Cr) nano-catalyst in aqueous medium

Magnetically retrieval CuFe₂O₄@MIL-101(Cr) metal–organic framework was successfully prepared from easily available starting materials and characterized using various spectroscopic and analytical techniques such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, transmission electron microscopy, elemental mapping, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, vibrating sample magnetometer, and inductively coupled plasma optical emission spectroscopy. The catalyst was then used in the synthesis of benzodiazepines containing a triazole moiety in water. The advantages of this protocol include high yields, reusability of the catalyst, and gram-scale synthesis.     

Synthesis of Cu–Cr diketo,sublimable, eutectic composite complex,rod crystals from LDH as suitable MOCVD precursor of CuCr2O4 catalysts upon ceramic preforms for N2O decomposition

Metal-acteylacetonates are important sublimable metal-organic precursors for metal-oxide thin film formation over solid preforms by MOCVD (Metal Organic Chemical Vapour Deposition) technique. Mixed-metal-acetylacetonates (MMAA) are suitable starting materials for mixed metal nano-oxidic thin film formation through such facile routes. Layered Double Hydroxides (LDH) of suitable metal ion combination can perform as appropriate starting base for neutralisation by enol form of 2,4-pentanedione or acteylacetonate tautomer ligands to obtain such MMAA. In this paper synthesis of composite crystals of Cu(II)/Cr(III) acetylacetonates (CCAA) is reported by the reaction of Cu–Cr-LDH with acetylacetone. The products were characterized by various different techniques. The surface area and pore volume analysis of the crystals showed the formation of nanopores in the compound. TEM analysis confirmed that the inner core of the nanoporous crystals of Cu(acac)₂ was covered by coating of poorly crystallised Cr(acac)₃ and they together form the composite crystals, and they together form the composite crystals. Due to eutectic mixture formation the melting point of CCAA lies in between the melting points of individual components Cu(acac)₂ and Cr(acac)₃ and shows sublimability, a property important for the formation of MOCVD films. The composite was used for CuCr₂O₄ spinel mixed oxide films formation over solid ceramic honeycomb monolithic substrates. Application prospects of the route in the field of catalysis is high as it can directly combine the benefits of mixed metal oxide catalysis and structured supports without the involvement of a third component. In this work the performance of such a catalytic device has been tested for low temperature decomposition of high Global Warming Potential (GWP) gas N₂O to N₂ and O₂.     

Coordination and Hydroboration of Ru(II)-Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

Treatment of [Cp*RuCl₂]₂, 1 , [(COD)IrCl]₂, 2 or [(p-cymene)RuCl₂]_2, 3 (Cp*=η⁵-C₅Me_5, COD= 1,5-cyclooctadiene and p-cymene=η⁶-ⁱPrC₆H₄Me) with heterocyclic borate ligands [Na[(H₃B)L], L₁ and L₂ ( L₁ : L=amt, L₂ : L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L₁ and L₂ afforded dihydridoborate species [L^AM(μ-H)₂BHL] 4 – 6 ( 4 : L^A=Cp*, M=Ru, L=amt; 5 : L^A=Cp*, M=Ru, L=mp; 6 : L^A=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L₂ yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)₂BH(mp)}₂], cis- 7 and trans- 7 . The isolation and structural characterization of fac- and mer-[Ru{(μ-H)₂BH(mp)}{(μ-H)BH(mp)₂}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans- 7 , they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a – d .     

In vitro anti-cataract evaluation of standardised Abies pindrow leaf extract using isolated goat lenses

Oxidative stress is known to spark off the pathogenesis of cataract. Antioxidant potential of Abies pindrow Royle leaf extract (APE) is well established in the literature. In this context, standard aqueous leaf extract of this plant was evaluated for its role in hydrogen peroxide-induced cataract in isolated goat lenses using varying concentrations (5, 10, 15 and 20 mg/mL). Total phenol and flavonoidal content was evaluated and found to be high in concentration. Biochemical parameters, namely superoxide dismutase (SOD), glutathione (GSH), total protein content (TPC) and malondialdehyde (MDA), were evaluated. SOD, GSH and TPC formation was found to increase proportionally with increasing concentration. However, MDA level decreased significantly as the concentration of the extract increased. The results suggest that the extract under investigation can delay the onset and/or prevent the progression of cataract. Its anti-cataract potential may be attributed to the presence of high phenolics and flavonoids in APE. Photographic evaluation, further, confirmed the observation.     

Single Crystal to Single Crystal (SC‐to‐SC) Transformation from a Nonporous to Porous Metal–Organic Framework and Its Application Potential in Gas Adsorption and Suzuki Coupling Reaction through Postmodification

A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH₂ groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m² g^?1. The material also possesses good CO₂ (8 wt %) and H₂ (1.87 wt %) adsorption capabilities.     

Solvent- and Substrate-Induced Chiroptical Inversion in Amphiphilic,Biocompatible Glycoconjugate Supramolecules: Shape-Persistent Gelation,Self-Healing,and Antibacterial Activity

We have shown solvent- and substrate-dependent chiral inversion of a few glycoconjugate supramolecules. (Z)-F-Gluco, in which d -glucosamine has been attached chemically to Cbz-protected l -phenylalanine at the C terminus, forms a self-healing hydrogel through intertwining of the nanofibers wherein the gelators undergo lamellar packing in the β-sheet secondary structures with a single chiral handedness. Dihybrid (Z)-F-gluco nanocomposite gel was prepared by in-situ formation of silver nanoparticles AgNPs in the gel; this enhances the mechanical properties of the composite gel through physical crosslinking without altering the packing pattern. In contrast, (Z)-L-gluco bearing an l -leucine moiety does not form a hydrogel but an organogel. Interestingly, the chiral handedness of the aggregates of (Z)-L-gluco can be reversed by choosing suitable solvents. In addition to self-healing behavior, (Z)-L-gluco gel revealed shape persistency. Further, (Z)-F-gluco hydrogel is benign, nontoxic, non-immunogenic, and non-allergenic in animal cells. AgNP-loaded (Z)-F-gluco hydrogel showed antibacterial activity against both Gram-positive and Gram-negative bacteria.     

Superperiodicity,chaos and coexisting orbits of ion-acoustic waves in a four-component nonextensive plasma

Superperiodicity, chaos and coexisting orbits of ion-acoustic waves (IAWs) are studied in a multi-component plasma consisting of fluid ions, q -nonextensive cold and hot electrons and Maxwellian hot positrons. The significant impacts of the system parameters on superperiodic and nonlinear periodic IAWs are presented. Considering an external periodic perturbation various types of quasiperiodic and chaotic features for IAWs are studied in different parametric ranges through time series’ plots, phase spaces and Lyapunov exponents. It has been observed that there exist some coexisting orbits for IAWs. Coexisting orbits for IAWs in a classical electron–positron–ion plasma system are reported.