Magnetic study of Mg0.95Mn0.05Fe2O4 ferrite nanoparticles

The magnetic properties of Mg_0.95Mn_0.05Fe₂O₄ ferrite samples with an average particle size of ∼6.0±0.6 nm have been studied using X-ray diffraction, Mössbauer spectroscopy, dc magnetization and frequency dependent real χ^′(T) and imaginary χ^″(T) parts of ac susceptibility measurements. A magnetic transition to an ordered state is observed at about 195 K from Mössbauer measurements. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization have been recorded at low field and show the typical behavior of a small particle system. The ZFC curve displays a broad maximum at , a temperature which depends upon the distribution of particle volumes in the sample. The FC curve was nearly flat below , as compared with monotonically increasing characteristics of non-interacting superparamagnetic systems indicating the existence of strong interactions among the nanoparticles. A frequency-dependent peak observed in χ^′(T) is well described by Vogel-Fulcher law, yielding a relaxation time and an interaction parameter . Such values show the strong interactions and rule out the possibility of spin-glass (SG) features among the nanoparticle system. On the other hand fitting with the Néel-Brown model and the power law yields an unphysical large value of τ₀ (∼6×10⁻⁶⁹ and 1.2×10⁻²² s respectively).     

Yb(OTf)3 catalyzed new cascade reaction: a facile assembly of fused quinazolinones

A one-pot Yb(III)-mediated cascade reaction has been developed leading to small molecules based on a novel structural motif, i.e. quinazolin-4-one moiety fused with an isoquinoline ring, for potential inhibition of TNF-α.     

Label-free flow cytometry using multiplex coherent anti-Stokes Raman scattering (MCARS) for the analysis of biological specimens

We present the first demonstration, to our knowledge, of a label-free flow cytometer for the analysis of biological specimens using multiplex coherent anti-Stokes Raman scattering (MCARS) and elastic scatter measurements. The MCARS system probes the Raman vibrational energy levels and the elastic scatter provides morphological information. We demonstrate these capabilities by probing a culture of Saccharomyces cerevisiae at 100 spectra/s and constructing a background-free Raman reconstruction using a Kramers-Kronig relation. A theoretical analysis shows that this system could operate at speeds of 10 kHz with appropriate hardware; thus facilitating integration into commercial flow cytometers or use as a high-speed, stand-alone device.     

Synthesis of Novel Isoxazolyl 1,6-Dithia-4,9-diazaspiro[4,4]nonane-3,8-diones and 1-Oxa-6-thia-2,4,9-triazaspiro[4,4]non-2-ene-8-ones

The key intermediates, 3-(5-methyl-3-isoxazolyl)-2-arylimino-1,3-thiazolan-4-ones (3), were obtained from 3-amino-5-methylisoxazole (1) by reaction with chloroacetyl chloride followed by treatment with aryl isothiocyanates. Cyclocondensation of 3 with mercapto acetic acid furnished novel isoxazolyl 1,6-dithia-4,9-diazaspiro[4,4]nonane-3,8-diones (4). Cycloaddition of 3 with benzonitrile oxides afforded novel isoxazolyl 1-oxa-6-thia-2,4,9-triazaspiro[4,4]non-2-ene-8-ones (5).     

Polyaniline nanostructures expedient as working electrode materials in supercapacitors

Granular type polyaniline (PANi), PANi nanofibers (NFs), and PANi nanotubes (NTs) expedient as working electrode materials for supercapacitors are synthesized. The synthesis procedure used in this work facilitates not only the synthesis of solid powders of the PANi nanostructures, but also thin films constituted by the same PANi nanostructures in the same experiment. PANi NFs are found to exhibit faster electrode kinetics and better capacitance when compared to PANi NTs and granular PANi. Specific capacitance and energy storage per unit mass of PANi NFs are 239.47 Fg^?1 (at 0.5 Ag^?1) and 43.2 Wh?kg^?1, respectively. Electrical conductivity of PANi NFs is also better when compared to the other two nanostructures. Properties of the three PANi nanostructures are explicated in correlation with crystallinity, intrinsic oxidation state, doping degree, BET surface area, and ordered mesoporosity pertaining to the nanostructures.     

Stereoselective total synthesis of almorexant

A highly stereoselective synthesis of almorexant has been achieved using (R)-tert-butanesulfinamide as a chiral source. The chiral tetrahydroisoquinoline core was constructed through allylation of chiral N-sulfinyl imine followed by ring closure of the secondary amide with a tethered halide. The chiral α-phenyl amide was introduced by means of S_N2 substitution of (S)-methyl 2-phenyl-2-(tosyloxy)acetate with chiral tetrahydroisoquinoline.     

New benzotriazole-based reagents for the phosphonylation of various N-, O-, and S-nucleophiles

Benzotriazole surrogates showing higher stabilities than the corresponding chlorophosphates, allow phosphonylation of a variety of N-, O-, and S-nucleophiles in good yields.     

Hypervalent iodine(III)-mediated regioselective N-acylation of 1,3-disubstituted thioureas

Reaction of asymmetrical 1,3-disubstituted thioureas with diacetoxyiodobenzene (DIB) produces regioselectively N-acetylurea in shorter time. Regioselectivity is dependent on the pKa's of the amine attached to the thiourea moiety with acylation taking place toward the amine having a lower pKa. This is the first example of DIB being employed as an N-acetylating agent. A mechanism for this novel transformation is also proposed. Mild reaction conditions, shorter reaction times, high efficiencies, environmentally benign methods, and facile isolation of the desired product make the present methodology a most suitable alternative.     

A new cascade reaction: concurrent construction of six and five membered rings leading to novel fused quinazolinones

A one-pot cascade reaction has been developed leading to the concurrent construction of six and five membered fused N-heterocyclic rings of indazolo[3,2-b]quinazolinones. The methodology involved the reaction of isatoic anhydride, a hydrazine and o-iodo benzaldehyde in the presence of Pd(PPh(3))(4) and BINAP in MeCN. The mechanism of this cascade reaction is discussed. A variety of indazolo[3,2-b]quinazolinone derivatives were prepared by using this methodology in good yields, some of which were tested for their PDE4 inhibitory properties in vitro. The dose response and docking study performed using a representative compound is presented.     

Characterization and Enhanced Production of Prodigiosin from the Spoiled Coconut

Many bacterial secondary products are bioactive substances that play an important role in biotechnology and pharmacology (e.g., as antibiotics or antitumor agents). Over the past few years interest in prodigiosin has been increased due to its promising anti-cancer activity. Prodigiosin is also of potential clinical interest because it is reported to have anti-fungal, anti-bacterial, anti-protozoal/anti-malarial, and immunosuppressive activity. Thus there is a need to develop a high-throughput and cost-effective bioprocess for the production of prodigiosin. In the present study, Serratia rubidaea was isolated from colored portion of a spoiled coconut and further it was authenticated by MTCC, India. The various parameters like temperature, pH, salt concentration, and precursors were optimized for the production of prodigiosin. We now report that the pigment production was higher in our isolated strain than S. marcescens. It was observed that prodigiosin binds with plastic, paper, and fibers and thus in near future, it can also be used as a natural dye.