A Proficient approach to enhance heat transfer using cupric oxide/silica hybrid nanoliquids

Journal of Thermal Analysis and Calorimetry - High performance cooling anticipated in smaller size heat transfer equipment is the most significant challenge in many industries including CPU...     

Nanocrystalline tin compounds/graphene nanocomposite electrodes as anode for lithium-ion battery

Nanocrystalline tin (Sn) compounds such as SnO₂, SnS₂, SnS, and graphene nanocomposites were prepared using hydrothermal method. The X-ray diffraction (XRD) pattern of the prepared nanocomposite reveals the presence of tetragonal SnO₂, hexagonal SnS₂, and orthorhombic SnS crystalline structure in the SnO₂/graphene nanosheets (GNS), SnS₂/GNS, and SnS/GNS nanocomposites, respectively. Raman spectroscopic studies of the nanocomposites confirm the existence of graphene in the nanocomposites. The transmission electron microscopy (TEM) images of the nanocomposites revealed the formation of homogeneous nanocrystalline SnO₂, SnS_2, and SnS particle. The weight ratio of graphene and Sn compound in the nanocomposite was estimated using thermogravimetric (TG) analysis. The cyclic voltammetry experiment shows the irreversible formation of Li₂O and Li₂S, and reversible lithium-ion (Li-ion) storage in Sn and GNS. The charge–discharge profile of the nanocomposite electrodes indicates the high capacity for the Li-ion storage, and the cycling study indicates the fast capacity fading due to the poor electrical conductivity of the nanocomposite electrodes. Hence, the ratio of Sn compounds (SnO₂) and GNS have been altered. Among the examined SnO₂:GNS nanocomposites ratios (35:65, 50:50, and 80:20), the nanocomposite 50:50wt% shows high Li-ion storage capacity (400 mAh/g after 25 cycles) and good cyclability. Thus, it is necessary to modify GNS and Sn compound composition in the nanocomposite to achieve good cyclability.     

Synthesis of Ge nanocrystals by atom beam sputtering and subsequent rapid thermal annealing

Ge nanocrystals embedded in an SiO₂ matrix were prepared by the atom beam co-sputtering (ABS) method from a composite target of Ge and SiO₂. The as-deposited films were rapid thermally annealed at the temperatures 700 and 800 °C in nitrogen ambience. The structure of the films was evaluated by using X-ray diffraction (XRD) and Raman spectroscopy. XRD results reveal that as-deposited films are amorphous in nature whereas annealed samples show crystalline nature. Raman scattering spectra showed a peak of Ge–Ge vibrational mode shifted downwards to 297 cm^?1, presumably caused by quantum confinement of phonons in the Ge nanocrystals. Rutherford backscattering spectrometry has been used to measure the thickness and Ge composition of the composite films. Size variation of Ge nanocrystals with annealing temperature has been discussed. The advantages of ABS over other methods are highlighted.     

Particles dispersion on fluid-liquid interfaces

This paper is concerned with the dispersion of particles on the fluid-liquid interface. In a previous study we have shown that when small particles, e.g., flour, pollen, glass beads, etc., contact an air-liquid interface, they disperse rapidly as if they were in an explosion. The rapid dispersion is due to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. In this paper we show that motion of particles normal to the interface is inertia domin...     

Synthesis of functionalized chromene and spirochromenes using l-proline-melamine as highly efficient and recyclable homogeneous catalyst at room temperature

An efficient and recyclable homogeneous catalyst is developed using commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio; 3 mol% on total weight) was found to be best catalyst to give the desired products with excellent yields (up to 99%) in very short times (1–15 min) at room temperature in DMSO as solvent. The catalyst was recovered by adding EtOAc and reused up to 5 cycles without losing the catalytic activity.     

Chemical Constituents from Alafia Barteri Oliv. Leaves with Cytotoxic Activity

Methanol extract of Alafia barteri leaves showed cytotoxic activity on leukaemia carcinoma K562, and hepatic liver cancer cells WRL (IC₅₀ values 193.1 and 225.0 μM respectively). Isolation of the extract gave ursane triterpenoid, 28‐acety‐urs‐5,20‐dien‐2β,3β,24α‐triol, 1 , together with undecanol, 2 , stigmasterol, 3 and octadecanoic acid, 4 . The structures of these compounds were identified by spectroscopic analysis, including MS, 1D and 2D NMR, and supported with literature data. Compound 1 exhibited cytotoxic activity against K‐562 at 50 and 100 μM concentrations with IC₅₀ 74.22 μM, while compounds 2 , 3 and 4 showed low inhibition of WRL, MCF‐7 and COLO cell lines.