Estimation of dynamic properties of attractors observed in hollow copper electrode atmospheric pressure arc plasma system

Understanding of the basic nature of arc root fluctuation is still one of the unsolved problems in thermal arc plasma physics. It has direct impact on myriads of thermal plasma applications being implemented at present. Recently, chaotic nature of arc root behavior has been reported through the analysis of voltages, acoustic and optical signals which are generated from a hollow copper electrode arc plasma torch. In this paper we present details of computations involved in the estimation process of various dynamic properties and show how they reflect chaotic behavior of arc root in the system.     

Ellagitannin chemistry. Evolution of a three-component coupling strategy for the synthesis of the dimeric ellagitannin coriariin A and a dimeric gallotannin analogue

The total synthesis of the dimeric ellagitannin coriariin A is reported. The key reaction to access the dimeric framework was realized early in the synthesis pathway via a bis acylation reaction of a dehydrodigalloyl diacid with 2 equiv of a glucopyranose trichloroacetimidate. The glucose rings were subsequently functionalized, culminating in a double oxidative cyclization to form stereoselectively both (S)-HHDP ester units. This bis acylation strategy was also employed to prepare a gallotannin analogue of coriariin A whose earlier synthesis by orthoquinone dimerization was plagued by yield-limiting side reactions.     

Recent progress in insertion and cyclopropanation reactions of metal carbenoids from α-diazocarbonyl compounds

Research on Chemical Intermediates - Metal–carbenoids from α-diazocarbonyl compounds are well-known reactive intermediates with a long history of useful applications in synthetic organic...     

Spectroscopic investigations (FTIR,UV-VIS,NMR) and DFT calculations on the molecular structure of Nω-Nitro-L-arginine

The spectroscopic properties of N_ω-nitro-l-arginine were investigated by FT-IR, UV-VIS, and ¹H NMR spectra. Geometrical parameters and energies were calculated using the density functional theory (DFT) B3LYP method with the 6-311G basis set. Geometrical optimization of the molecule has been performed, vibrational spectra have been calculated, and fundamental vibrations have been determined from the total energy distribution (TED) of the vibrational modes. The HOMO-LUMO analysis is carried out for various electric fields (0.0–0.025 A^?1). The HOMO-LUMO gap is decreased while increasing the electric field. The calculated quantum chemical parameters are calculated and correlated to the inhibition efficiency, A Mullliken population was also important for determining local reactivity by indicating reactive centers and identifying potential nucleophilic and electrophilic attack sites. Charge transfer occurs inside the compound based on the HOMO LUMO gap. Calculations of DFT were evaluated in their ability to predict inhibition efficiency.     

A Novel Green Synthesis of Silver Nanoparticles Using Gum Karaya: Characterization,Antimicrobial and Catalytic Activity Studies

Stable silver nanoparticles have been synthesized using gum karaya acting as both reducing and stabilizing agent without using any synthetic reagent. The reaction is performed using water, which is an environmentally safe solvent. This reaction was carried out in an autoclave at a pressure of 15 psi and 120 °C temperature by varying the time. The influence of different parameters such as time, change of concentration of silver nitrate and concentration of gum karaya on the formation of silver nanoparticles has been studied. The synthesized silver nanoparticles are characterized by UV–Vis spectroscopy, FTIR, XRD and TEM. UV–Vis analysis of the sample confirmed the formation of silver nanoparticles exhibiting a sharp peak at a wavelength of 420 nm. TEM micrographs showed the formation of well-dispersed silver nanoparticles of size 2–4 nm. The antimicrobial activity of silver nanoparticles stabilized in gum karaya is tested against Escherichia coli, Micrococcus luteus and is found to be possessing inhibiting property. The silver nanoparticles stabilized in gum karaya exhibited very good catalytic activity and the kinetics of the reaction was found to be pseudo first order with respect to the 4-nitrophenol.     

Asymmetric total synthesis of dendrobatid alkaloid 251F

The dendrobatid alkaloid (-)-251F was synthesized. The key steps of the synthesis were (1) an asymmetric Diels-Alder reaction to establish four of the necessary stereocenters in the target, (2) a ring-opening/ring-closing metathesis reaction to establish a key [3.3.0] bicyclic intermediate, and (3) an intramolecular Schmidt reaction.     

Synthesis of novel spiroazetidinones by selective lactam‐carbonyl cleavage in 1‐aryl/cyclohexyl‐3,3‐diphenyl‐1′‐(diphenylacetyl)spiro[azetidin‐2,3′‐indoline]‐2′,4‐diones

Titled compounds undergo selective N‐C cleavage on treatment with sodium hydroxide in ethanol affording a series of novel isatin‐based spiroazetidinones.     

Features of electron density and temperature in the 500–3500 km region of the plasmasphere—(1) Dawn and dusk sectors

Dawn-dusk features of the plasmasphere are examined for intervals in February and September 1969, using electrostatic probe data ofN _e andT _e from the ISIS-I satellite. Clear plasmatrough formation is seen in the vicinity of 70° geomagnetic latitude in both dawn and dusk sectors in the 1500–3500 km region, but the plasmatrough is absent in the altitude range 500–1500 km. The plasmatrough minimum near 70°φ exhibits no asymmetry between dawn and dusk sectors in its latitudinal position. TheT _e peak associated with the plasmatrough is more pronounced in the dawn sector. DawnN _e is less than duskN _e, but dawnT _e exceeds duskT _e. The influence of processes in the magnetosphere in causing these features is examined.     

Flow of a micropolar fluid in a tube with sinusoidal deformation

Summary The flow of a micropolar fluid for sinusoidally deforming boundaries is discussed in detail. The velocity and microrotation fields and the streamfunction are determined and plotted under the assumption of small deformations.

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Zusammenfassung Die Strömung einer mikropolaren Flïssigkeit mit sinusoidaler Verformung der Begrenzung wird ausführlich diskutiert. Die Geschwindigkeits- und Mikrorotationsfelder und die Stromfunktion werden mit der Annahme einer kleinen Verformung bestimmt und graphisch dargestellt.