Iodine‐Catalyzed Conversion of β‐Dicarbonyl Compounds into β‐Enaminones Within a Minute Under Solvent‐Free Conditions

Synthesis of β‐enaminones from β‐dicarbonyl compounds has been achieved in high yields within a minute using primary and aromatic amines and catalytic amounts of iodine under solvent‐free conditions at room temperature.     

Intramolecular 1,3-dipolar cycloaddition reactions in the synthesis of complex annelated quinolines, α-carbolines and coumarins

In this study, we report the synthesis of several novel dihydroisoxazole-, tetrahydroisoxazole- and dihydropyrazole-fused pyrido[2,3-b]quinolines, α-carbolines, and pyrido[2,3-c]coumarins, respectively, from simple precursors and by exploring intramolecular 1,3-dipolar cycloaddition reactions involving nitrile oxides, nitrones, and nitrile imines as 1,3-dipoles.     

Effect of ambient gas species on the formation of Cu nanoparticles in wire explosion process

In this paper, the effect of ambient gas species on the characteristics of the produced nanoparticles in wire explosion process is reported. Cu wires with a diameter of 125 μm and length of 6.1 cm were exploded in different ambiances of Ar and admixtures of Ar and N₂ at 500 mbar pressure. Immediate formation of arc plasma is observed for Ar ambiance. On the other hand, considerable delay in formation of arc plasma is observed for the admixtures of Ar and N₂. The arc plasma formation time is found to increase with increasing N₂ concentration in the admixture. Transmission electron microscope and X-ray diffraction were used to characterize the produced nanoparticles. Among the nanoparticles produced in different ambient gas species, the nanoparticles produced in Ar ambiance have higher particle size compared to admixtures of Ar and N₂. The particle size is found to reduce with increasing N₂ concentration in the ambiance. Difference in arc plasma formation time is probably the factor that gives rise to the difference in the particle sizes.     

Bioinorganic and medicinal chemistry: aspects of gold(I)-protein complexes

Gold(I)-based drugs have been used successfully for the treatment of rheumatoid arthritis (RA) for several years. Although the exact mechanism of action of these gold(I) drugs for RA has not been clearly established, the interaction of these compounds with mammalian enzymes has been extensively studied. In this paper, we describe the interaction of therapeutic gold(I) compounds with mammalian proteins that contain cysteine (Cys) and selenocysteine (Sec) residues. Owing to the higher affinity of gold(I) towards sulfur and selenium, gold(I) drugs rapidly react with the activated cysteine or selenocysteine residues of the enzymes to form protein-gold(I)-thiolate or protein-gold(I)-selenolate complexes. The formation of stable gold(I)-thiolate/selenolate complexes generally lead to inhibition of the enzyme activity. The gold-thiolate/selenolate complexes undergo extensive ligand exchange reactions with other nucleophiles and such ligand exchange reactions alter the inhibitory effects of gold(i) complexes. Therefore, the effect of gold(I) compounds on the enzymatic activity of cysteine- or selenocysteine-containing proteins may play important roles in RA. The interaction of gold(I) compounds with different enzymes and the biochemical mechanism underlying the inhibition of enzymatic activities may have broad medicinal implications for the treatment of RA.     

Observation of B(s)⁰→J/ψf₀(980) and evidence for B(s)⁰→J/ψf₀(1370)

We report the observation of B(s)?→J/ψf?(980) and evidence for B(s)?→J/ψf?(1370), which are CP eigenstate decay modes. These results are obtained from 121.4 fb?1 of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e(+)e? collider. We measure the branching fractions B(B(s)?→J/ψf?(980); f?(980)→π(+)π?)=(1.16(-0.19)(+0.31)(stat)(-0.17)(+0.15)(syst)(-0.18)(+0.26)(N(B(s)((*))B(s)((*)))))×10?? with a significance of 8.4σ, and B(B(s)?→J/ψf?(1370); f?(1370)→π(+)π?)=(0.34(-0.14)(+0.11)(stat)(-0.02)(+0.03)(syst)(-0.05)(+0.08)(N(B(s)((*))B(s)((*)))))×10?? with a significance of 4.2σ. The last error listed is due to uncertainty in the number of produced B(s)((*))B(s)((*)) pairs.     

Dielectric and impedance properties of Bi(Zn2/3V1/3)O3 electronic material

A polycrystalline vanadium doped lead free dielectric material of Bi(Zn_2/3V_1/3)O₃ (BZV) has been prepared using a standard high-temperature solid state reaction technique. Its temperature and frequency dependent capacitive, conductive and resistive characteristics are outlined though experimental investigation. The formation of single phase compound of BZV material with orthorhombic crystal symmetry is identified through X-ray diffraction data analysis, and the homogeneous distribution of grains are realized through scanning electron micrograph. The acquaintance of frequency–temperature dependent electrical parameters with the obtained micrograph provides the experimental evidence of contributions of grain as well as grain boundary in its capacitive and resistive characteristics. The negative temperature coefficient of resistance behaviour of the material is revealed from impedance characteristic, and non-Debye type relaxation has been realized from the Nyquist plot. The charge carriers of this electronic compound have both long & short range order that has been validated from the complex modulus and impedance analysis. The prepared electronic material substantiate some important dielectric features which props up the material as promising component for electronic devices.     

Probable Decay Modes at Limits of Nuclear Stability of the Superheavy Nuclei

The modes of decay for the even–even isotopes of superheavy nuclei of Z = 118 and 120 with neutron number 160 ≤ N ≤ 204 are investigated in the framework of the axially deformed relativistic mean field model. The asymmetry parameter η and the relative neutron–proton asymmetry of the surface to the center (R _η ) are estimated from the ground state density distributions of the nucleus. We analyze the resulting asymmetry parameter η and the relative neutron–proton asymmetry R _η of the density play a crucial role in the mode(s) of decay and its half-life. Moreover, the excess neutron richness on the surface, facets a superheavy nucleus for β^? decays.     

Fast ion beams from intense,femtosecond laser irradiated nanostructured surfaces

We present results on hot electron and energetic ion (keV–MeV) generation from polished and nanostructured metallic surfaces excited by p-polarized, femtosecond laser pulses in the intensity range of 1×10¹⁵–1.5×10¹⁷ W cm^-2. A clear enhancement in the hard X-ray spectrum from nanoparticle-coated surfaces is observed, indicating ‘hotter’ electron production in nanoparticle-produced plasma until the intensity of 2×10¹⁶ W cm^-2 is reached. Contrary to the existing perception, we find that the hotter electrons do not lead to hotter ion emission. The total ion flux and the ion energy integrated over the 4–1400 keV energy range are found to be enhanced by 50% and 16%, respectively, for nanostructured targets in comparison to those from polished targets. 55% enhancement in yield is observed for ions at the lower end of the energy range, while hotter ions are actually found to be suppressed by ∼40%. The surface modulations present on the nanoparticle-coated targets are observed to reduce the maximum energy of the ions and showed an intensity-dependent increase in the divergence of the ion beam. PACS 79.20.Ds; 68.47.De; 61.80.Ba; 61.82.Bg; 42.65.Re     

Zinc triflate: a highly efficient reusable catalyst in the synthesis of functionalized quinolines via Friedlander annulation

An environmentally friendly and highly efficient procedure for the preparation of quinolines and fused polycyclic quinolines has been developed by a simple Friedlander annulation reaction of 2-aminoaryl ketone with carbonyl compounds in presence of zinc triflate under microwave irradiation and solvent-free conditions. The reaction also proceeds effectively when In(OTf)₃ was used in lieu of Zn(OTf)₂ as the catalyst. The catalyst can be recovered after the reaction and reused efficiently in subsequent runs.