Peaceful pyrolysis-a novel method for the decomposition of metal-perchlorate complexes of organic ligands

Perchlorate complexes of vanadium(IV), iron(III), dysprosium, yttrium, copper(II) and nickel with the organic ligands dimethyl sulphoxide, antipyrine, 4-aminoantipyrine, 4-(2-hydroxynaphthyl)-azoantipyrine, and 4-(2,4-dihydroxyphenyl)azoantipyrine have been prepared and analysed for their metal content after decomposition by a non-explosive pyrolytic technique, viz. heating with ammonium chloride. The results obtained agree with those obtained by the standard methods. This pyrolytic technique is found to be very convenient, rapid and accurate.     

Magnetic and Mössbauer properties of Fe doped VN nanoparticles

Nanoparticles of iron doped vanadium nitride are synthesized by simultaneous thermal decomposition and nitridation of [V_(1???x)Fe _x O(NH₂O)₂Gly]·H₂O in NH₃ atmosphere at 973 K for 4 h. Pure VN shows cubic NaCl structure with lattice parameter of a?=?4.126 Å. Lattice parameter increases with Fe-doping. Magnetization increases with increase of Fe amount in VN. Coercivity values are in the range 30–80 Oe, which is relatively so small, compared to pure Fe. From Mössbauer study, it is inferred that single resonance line is due to the high diamagnetic contribution and doublet peaks are due to the paramagnetic contribution, which is assigned to the presence of ζ-Fe₂N phase.     

Pillared clays as efficient catalysts for cyclohexanol oxidation

Summary Iron, aluminium and mixed iron aluminium pillared clays were prepared by partial hydrolysis method and doped with 10% V and Mo. The samples were characterised by XRD, FTIR and surface area and pore volume measurements. Oxidation of cyclohexanol with hydrogen peroxide was done as probe reaction to test catalytic activity. Iron pillared systems exhibited maximum activity. The effects of various reaction variables on the reaction were studied.     

Designing high performance Pt monolayer core–shell electrocatalysts for fuel cells

In proton exchange membrane fuel cells, platinum (Pt) has been the dominant choice for both the cathode and the anode catalysts. The high Pt content and high associated costs particularly at the cathode, and sluggish oxygen reduction reaction (ORR) kinetics and poor stability, remain a challenge. Pt monolayer (ML) catalysts offer a distinctively reduced Pt content while providing considerable possibilities for enhancing their catalytic activity and stability for the ORR. In this opinion, we first review the achievement in active and stable Pt ML on palladium (Pd) nanoparticle catalysts for the ORR. We then describe the mechanisms that rationalize their high activity and durability. Recently, we developed several novel nanostructured cores to further improve the ORR activity and stability by optimizing their surface orientation, composition, and morphology. The results from the Pt ML catalysts significantly impact the research of electrocatalysis and fuel-cell technology, as they demonstrate an exceptionally effective way of design and syntheses of catalysts.     

Determination of repaglinide in pharmaceutical formulations by HPLC with UV detection.

A simple, precise and rapid RP-HPLC method was developed for the determination of repaglinide in pharmaceutical dosage forms. The method was carried out on a Shim-pack, RP-C18 column using a mixture of methanol: 0.1% v/v triethylamine (pH adjusted to 7 with orthophosphoric acid) and detection was done at 235 nm using nimesulide as internal standard. The linearity range was 0.1 to 0.5 microg/ml. The intra-day and inter-day precision were in the range of 0.48 to 1.01 and 0.15 to 1.15, respectively.     

Nonlinear aspects of supersonic flow past a cavity

Study of supersonic flow over wall-mounted cavities for two different length/depth (L/D) ratios is carried out experimentally. Unsteady pressure measurements were made on the front and aft walls of the cavity. Data analysis was performed on the experimental results so obtained. Spectra of the unsteady pressure data exhibit multiple tones. Higher-order spectral technique is implemented on the unsteady pressure data to ascertain whether these multiple tones are due to possible nonlinear interactions between the primary cavity modes (Rossiter modes) or not. Significant nonlinear interactions in the form of both sum and difference frequencies between the cavity modes are observed in both the cavities. The spectra of the cavity with L/D ratio 2 show distinct peaks due to nonlinear interactions while the cavity with L/D ratio 3 does not exhibit observable peaks in the spectra. The spectra of both the cavities show presence of low-frequency peaks of significant amplitudes. These low-frequency modes interact with the primary cavity modes to produce significant bicoherence values. The reasons for their existence could not be predicted. It is identified that the dominant mode in the spectra of the cavities is critical for most of the interactions observed.     

Acoustic and velocity field over 3D cavities

Effects of wall mounted cavity on a Mach 1.7 freestream flow over it are investigated experimentally and numerically. Three different three dimensional (3D) cavity configurations have been used in the study. The results are compared with those of a two dimensional (2D) cavity. Flow field over the cavity is observed to depend intensely on the cavity width and on the allied aerodynamic flow structure in the vicinity of the cavity. Pressure oscillations generated by presence of wall mounted cavity in supersonic freestream was also observed to affect the fluid motion over cavities.