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.     

Studies on the complexation of neodymium(III) ion with 1,2,4-1H-triazole and 1,2,3-benzotriazole in absence and presence of calcium(II) ion in aqueous and some selected different aquated organic solvents by an absorption spectroscopy involving 4f-4f transitions

The absorption spectra of trivalent neodymium ion with 1,2,4-1H-triazole and 1,2,3-benzotriazole in absence and presence of calcium(II) ion in aqueous and some selected different aquated organic solvents have been recorded in the visible and near infrared regions. From the data available in the absorption spectra, various spectroscopic parameters such as Slator-Condon (F(k)), Lande spin-orbit coupling constant (ξ(4f)), nephelauxetic ratio (β), bonding parameter (b(1/2)), percent covalency (δ), oscillator strength (P) and Judd-Ofelt intensity (T(λ)) parameters have been evaluated. The Judd-Ofelt intensity, T(λ) (λ=2, 4, 6) parameters are utilized in evaluating the P(cal) from various excited states of trivalent neodymium ions and ratifying as an inner sphere complexations.     

Hypervalent iodine oxidation of benzil-α-arylimino oximes: an efficient synthesis of 2,3-diphenylquinoxaline-1-oxides

A mild and efficient synthetic protocol for the oxidation of benzil-α-arylimino oximes 3 utilizing iodobenzene diacetate (IBD) as an oxidizing agent has been developed. Oximes 3, obtained by the condensation of (E)-benzil monoxime 2 with various appropriately substituted anilines 1, on treatment with iodobenzene diacetate in dichloromethane at room temperature underwent oxidative cyclization to afford 2,3-diphenylquinoxaline-1-oxide 4 in excellent yields.     

Construction of spatial-coherence spectral filters using a Fourier-achromat system

Theoretical investigations made not long ago regarding the construction of spatial-coherence spectral filters (SCSFs) are rendered into experiments by designing and fabricating a Fourier-achromat experimental setup analyzed in the theoretical studies. It is shown that the phenomenon of spectral shift due to spatial coherence also known as the Wolf effect can be exploited to make special types of low-pass and band-pass spectral filters with special spectral characteristics that are not shown by the conventional filters. A Fourier-achromat is employed to construct the SCSFs. The experimental results within the experimental limitations and measurement uncertainty agree well with the theory. These filters might find applications in (i) astronomy (in the search of particular spectral lines) (ii) developing spectrum-selective optical interconnects or (iii) in cryptography.     

Facile and Efficient Regioselective Synthesis of 1-(3′-Substituted Quinoxalin-2′-yl)-3-aryl/heteroaryl-5-methylpyrazoles

This report describes an efficient and practical approach for regioselective synthesis of 1-(3′-substituted quinoxalin-2′-yl)-3-aryl/heteroaryl-5-methylpyrazoles (3a–j). Reaction of 2-chloro-3-substituted quinoxalines (1) with 3(5)-methyl-5(3)-aryl-1H-pyrazoles (2) in the presence of sodium hydride furnished the title compounds in excellent yields with good levels of regioselectivity. The present protocol is superior to the existing method, which yielded a mixture of regioisomeric pyrazoles (I, II) and triazolo[4,3-a]quinoxalines (III).

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Novel and Expedient Regioselective Synthesis of 2-Imino-3-methyl-2,3-dihydrothiazoles

Cyclization of α-tosyloxyacetophenones 1 and N-methylthiourea 2 in acidic medium affords a novel and expedient method to synthesize 2-imino-3-methyl-2,3-dihydrothiazoles 3 with excellent level of regiocontrol.     

Synthesis of Some Novel 2,3,4,8,9‐Pentahydro‐7‐(4‐haloaryl)‐pyrazolo[5,1‐e]benzo[1,5]oxazocines and 2,3(erythro), 7,8‐Tetrahydro‐2‐aryl‐3‐(4‐fluoro‐3‐methylbenzoyl)‐6‐(4‐haloaryl)pyrazolo[5,1‐d] Benzo[1,4]oxazepines via Solid–Liquid PTC

In this communication, a simple and straightforward procedure for the heterocyclization of 1H‐4,5‐dihydro‐3‐(4‐haloaryl)‐5‐substituted phenylpyrazoles (4) with 1‐bromo‐3‐chloropropane and 2,3‐dibromo‐1‐(4‐fluoro‐3‐methylphenyl)‐3‐phe‐ nylpropanone affording 2,3,4,8,9‐pentahydro‐7‐(4‐haloaryl)pyrazolo[5,1‐e]benzo[1,5] oxazocines 5 and regioselective synthesis of 2,3(erythro),7,8‐tetrahydro‐2‐ aryl‐3‐(4‐fluoro‐3‐methylbenzoyl)‐6‐(4‐halophenyl)pyrazolo[5,1‐d]benzo[1,4]oxa‐ zepines 6, respectively, via solid–liquid PTC is reported. All the synthesized compounds have been characterized on the basis of their spectral studies (IR, PMR, and MS) and analytical data.     

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.