Evaluation of temperature-dependent microstructural and nanomechanical properties of phase pure V<Subscript>2</Subscript>O<Subscript>5</Subscript>

Phase pure, mesoporous, and crystalline V₂O₅ is synthesized by acid hydrolysis technique and subsequently heat treatment is carried out at 450, 500, 550, and 600?°C in air. The as-synthesized and heat-treated powders are thoroughly studied by X-ray diffraction, electron microscopy, dynamic light scattering, and spectroscopic techniques. A unique morphological tuning of V₂O₅ powders from as small as ~80?nm tiny nanorod to as large as a ~2.5?μm hexagonal grain as microstructural unit blocks is observed. A qualitative mechanism is suggested for particle growth. Further, the powders are pelletized and subsequently sintered in air at the same temperatures of 450, 500, 550, and 600?°C at which the powders were heat treated. Finally, nanomechanical properties of bulk pelletized V₂O₅ such as nanohardness and Young’s modulus are also evaluated by nanoindentation technique at nine different loads e.g., 10, 30, 50, 70, 100, 300, 500, 700, and 1000?mN.

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Cu catalyzed cross-dehydrogenative coupling reaction for the synthesis of 3-hydroxy-2-pyrrolidinones

A new convenient strategy for the synthesis of 3-hydroxy-2-pyrrolidinone derivatives featuring regioselective CC coupling has been developed. This is a Cu (II) catalyzed cross dehydrogenative coupling (CDC) involving enamino-ketones of benzyl amines and di-alkyl acetylenedicarboxylate, followed by cyclization by primary amines. TBHP (tert-butyl hydroperoxide) has been used as the oxidant to promote the coupling protocol. This synthetic route principally demonstrates the scope of CDC reaction and also applicable to gram-scale synthesis.     

Magnetic field induced synthesis and self-assembly of super paramagnetic particles in a protein matrix

Aqueous solution of a globular protein named bovine serum albumin was homogeneously mixed with ferrous and ferric ions and allowed to gel at ambient conditions. Gels were then oxidized using sodium hydroxide, in the presence of magnetic field of magnitude 0.13 T. The effect of magnetic field on the above biomimetic synthesis was a reduction in particle size and a directional assembly of synthesized super paramagnetic particles into a regular pattern in the protein film. The microstructural revelation was complimentary to Mossbauer results and magnetic measurement studies, i.e., an interesting variation in the magnetic behaviour of self-assembled super paramagnetic particles as a function of dc magnetic field induced ordering.     

Spin symmetry adaptation of the one-electron propagator

A new method is proposed for spin symmetry adaptation of the open-shell one-electron propagator. Possible applications to both diagrammatic perturbation theory and algebraic superoperator approximations of the propagator equations of motion are envisaged.     

Nanomechanical sensing of DNA sequences using piezoresistive cantilevers

A microfabricated cantilever with an internal piezoresistive component has been sensitized with thiol tethered ss-DNA strands and utilized for an in situ, label-free, highly specific, and rapid DNA detection assay. The generation of a differential surface stress onto the functionalized cantilever surface upon target recognition has allowed nanomechanical identification of 12-nucleotide complementary DNA probes with single base mismatch discrimination (sensitivity of 0.2 microM). Interestingly, utilization of an overhang extension distal to the surface enhanced the sensitivity to the 0.01 microM level. The cantilever was functionalized by inkjet printing technology. Replacing the capture probe with locked nucleic acid (LNA) resulted in a faster target probe capture kinetics compared to DNA-DNA hybridization. The capabilities of the piezoresistive cantilever indicate future ergonomic convenience via miniaturization alternative to the conventional laser-based detection method for portable on-site applications.     

Extraction separation of 86Rb from 85Sr in trace level with 18-crown-6 in nitrobenzene

A liquid-liquid extraction separation procedure has been developed for the separation of trace amounts of neutron activated rubidium and strontium from their mixture in 0.1M perchloric acid medium using 0.04M 18-crown-6 in nitrobenzene as the extractant. Separation factor for Rb/Sr was found approximately 3^.10³. Gamma-radiation stability of the extractant (up to 1.5^.10⁴ Gy) as well as that of the metal-extractant complex were examined. Complete stripping of rubidium has been achieved by 8M HCl with 3–4 fold volume increase of the aqueous phase.     

Substitution of HMPT by the cyclic urea DMPU as a cosolvent for highly reactive nucleophiles and bases

The cyclic urea DMPU (N, N′-dimethyl-N, N′-propylene urea = 1,3-dimethyl-2-oxo-hexahydropyrimidine) is shown to exhibit the same effects HMPT in oxirane-opening with Li-acetylide, in a Wittig olefination, in the double deprotonation of nitroalkane, in the Michael addition of Li-dithiane to cyclohexenone, and in selective generations of certain enolates (Schemes 1–7) DMPU might therefore be as safe substitute of the carcinogenic HMPT as a cosolvent with unique properties in diverse type of reaction.     

On the mechanism of palladium-catalyzed coupling of haloaryls to biaryls in water with zinc

[reaction: see text] Kinetics and process parameters of coupling and hydro-dehalogenation reactions of chloroaryls are studied in the presence of zinc, water, and catalytic Pd/C. Good yields are obtained for the coupling of chlorobenzene, 4-chlorotoluene, and 4-chloro-1,1,1-trifluorotoluene. It is shown that water is actually one of the reagents, reacting with zinc in the presence of palladium to give zinc oxide and hydrogen gas, which then regenerates the Pd0 catalyst for the coupling reaction.