Green Machining to Net Shape Alumina Ceramics Prepared Using Different Processing Routes

In the present study, the net shape manufacturing of alumina ceramics was carried out using computer numerically controlled (CNC) machining of differently processed alumina green bodies using different tool materials and geometries. In case of a carbide-coated tool, severe wear was observed; on the contrary, a diamond-coated tool was used successfully. The profile of the as-machined surface was found to be smooth using diamond-coated flat tool. Near net shape alumina was demonstrated using CNC green machining from optimized machining conditions. Optical micrograph and the surface roughness of the as-machined samples showed good surface finish for the green bodies with higher binder content.     

Anomalous quantum transport through a thin film of varying impurity density with the distance from the film surface

We explore a novel transport phenomenon by studying the effect of disorder on electron transport through a thin film of varying disorder strength with the distance from its surface. A simple tight-binding model is used to describe the film which is attached to two metallic electrodes, where the coupling of this film to the electrodes is treated through the use of Newns-Anderson chemisorption theory. It is found that, in the strong disorder regime the current amplitude through the film increases with the increase of the disorder strength, while it decreases in the weak disorder regime. This strange behavior is completely opposite to that of a conventional disordered system. Our results also predict that the electron transport is significantly influenced by the finite size of the thin film.     

Epoxidation of Canola Oil with Hydrogen Peroxide Catalyzed by Acidic Ion Exchange Resin

Canola oil with an iodine value of 112/100 g, and containing 60% oleic acid and 20% linoleic acid, was epoxidised using a peroxyacid generated in situ from hydrogen peroxide and a carboxylic acid (acetic or formic acid) in the presence of an acidic ion exchange resin (AIER), Amberlite IR 120H. Acetic acid was found to be a better oxygen carrier than formic acid, as it produced about 10% more conversion of ethylenic unsaturation to oxirane than that produced by formic acid under otherwise identical conditions. A detailed process developmental study was then performed with the acetic acid/AIER combination. The parameters optimised were temperature (65 °C), acetic acid to ethylenic unsaturation molar ratio (0.5), hydrogen peroxide to ethylenic unsaturation molar ratio (1.5), and AIER loading (22%). An iodine conversion of 88.4% and a relative conversion to oxirane of 90% were obtained at the optimum reaction conditions. The heterogeneous catalyst, AIER, was found to be reusable and exhibited a negligible loss in activity.     

Role of V2O5 on the formation of chemical mullite from aluminosilicate precursor

Aluminosilicate precursor for the processing of mulite ceramics was synthesized chemically from inorganic salts following colloidal route. V₂O₅ was used as a sintering additive in different ratios with the precursor powder. The powder mixes were compacted and sintered at different elevated temperatures. The sintered masses were characterized by measuring the bulk density, porosity, flexural strength and fracture toughness. The extent of mullitization and final microstructure of the sintered masses were investigated by scanning electron microscopy and XRD analysis. It was observed that V₂O₅ exhibited favourable effect on the formation of properly crystallized mullite and in the improvement of different mechanical properties.     

Removal of p-nitrophenol using hydrodynamic cavitation and Fenton chemistry at pilot scale operation

In the current work removal of p-nitrophenol has been investigated using hydrodynamic cavitation, either operated individually or in combination with H₂O₂ and conventional Fenton process. In hydrodynamic cavitation, two different cavitating devices viz. orifice plate and venturi have been used. Effect of different operating parameters such as initial concentration (5 g/l and 10 g/l), inlet pressure (over a range 5.7–42.6 psi) and pH (over a range 2–8) on the extent of removal has been investigated. In conventional Fenton process two loadings of FeSO₄, 0.5 g/l and 1 g/l were investigated and three ratios of FeSO₄:H₂O₂ viz. 1:5, 1:7.5 and 1:10 were used. Removal observed with venturi was higher than with orifice plate in combination with Fenton chemistry. For 5 g/l initial concentration of p-nitrophenol, maximum removal of 63.2% was observed whereas for 10 g/l solution it was 56.2%.     

Design and Synthesis of Xanthone Analogues Conjugated with Aza-aromatic Substituents as Promising G-Quadruplex Stabilizing Ligands and their Selective Cancer Cell Cytotoxic Action

We have examined the stabilization of higher-order noncanonical G-quadruplex (G4) DNA structures formed by the G-rich sequences in the promoter region of oncogenes such as c-MYC, c-KIT, VEGF and BCl2 by newly synthesized, novel nitrogen-containing aromatics conjugated to xanthone moiety. Compounds with N-heterocyclic substituents such as pyridine (XNiso), benzimidazole (XBIm), quinoxaline (XQX) and fluorophore dansyl (XDan) showed greater effectiveness in stabilizing the G4 DNA as well as selective cytotoxicity for cancer cells (mainly A549) over normal cells both in terms of UV-Vis spectral titrations and cytotoxicity assay. Both fluorescence spectral titrimetric measurements and circular dichroism (CD) melting experiments further substantiated the G4 stabilization phenomenon by these small-molecular ligands. In addition, these compounds could induce the formation of parallel G4 structures in the absence of any added salt condition in Tris ⋅ HCl buffer at 25 °C. In a polymerase stop assay, the formation of stable G4 structures in the promoter of oncogenes and halting of DNA synthesis in the presence of the above-mentioned compounds was demonstrated by using oncogene promoter as the DNA synthesis template. Apoptosis-mediated cell death of the cancer cells was proved by Annexin V-PI dual staining assay and cell-cycle arrest occurred in the S phase of the cell cycles. The plausible mode of binding involves the stacking of the xanthone core on the G4 DNA plane with the possibility of interaction with the 5’-overhang as indicated by molecular dynamics simulation studies.     

Impact of Stone-Wales and lattice vacancy defects on the electro-thermal transport of the free standing structure of metallic ZGNR

We report the effect of topological as well as lattice vacancy defects on the electro-thermal transport properties of the metallic zigzag graphene nano ribbons at their ballistic limit. We employ the density function theory–Non equilibrium green’s function combination to calculate the transmission details. We then present an elaborated study considering the variation in the electrical current and the heat current transport with the change in temperature as well as the voltage gradient across the nano ribbons. The comparative analysis shows, that in the case of topological defects, such as the Stone-Wales defect, the electrical current transport is minimum. Besides, for the voltage gradient of 0.5 Volt and the temperature gradient of 300 K, the heat current transport reduces by \({\sim }62\,\%\) and \({\sim }50\,\%\) for the cases of Stones-Wales defect and lattice vacancy defect respectively, compared to that of the perfect one.