Cascade One‐Pot Synthesis of Orange‐Red‐Fluorescent Polycyclic Cinnolino[2,3‐f]phenanthridin‐9‐ium Salts by Palladium(II)‐Catalyzed C−H Bond Activation of 2‐Azobiaryl Compounds and Alkenes

Quaternary ammonium salts were synthesized in moderate to good yields through double oxidative C?H bond activation on azobenzenes. The mechanism of the highly regioselective reaction of 2‐azobiaryls with alkenes to give orange‐red‐fluorescent cinnolino[2,3‐f]phenanthridin‐9‐ium salts and 15H‐cinnolino[2,3‐f]phenanthridin‐9‐ium‐10‐ide is proposed to involve ortho C?H olefination of the 2‐azobiaryl compound with the alkene, intramolecular aza‐Michael addition, concerted metalation–deprotonation (CMD), reductive elimination, and oxidation.     

Synthesis and aggregational behavior of acidic proteinoid

Polypeptide-based acidic proteinoid containing L -glutamic acid and L -aspartic acid in excess and five other neutral and basic amino acids in minor proportions have been synthesized and found that it forms organized aggregates in an aqueous solution. The proteinoid aggregate has been characterized using ¹³C-NMR, IR, and fluorescence spectroscopic techniques. The c.m.c. of the proteinoid has been determined by conductometric and pH metric methods. The aggregation studies were carried out at different temperatures and varying ionic strengths of the medium. The phase transition of the proteinoid aggregate has been determined using the fluorescence absorbance method. The aggregation behavior is shown to be dependent on the pH of the solution. This was also supported by conductivity measurements. Using methylene blue as a model drug, the drug delivery property of the proteinoid micelles were studied in acidic (pH 4.5) and neutral (pH 7.4) mediums. Using biphasic model thermochemical parameters, ΔG, ΔH, ΔS, and ΔC_p have been evaluated. © 1996 John Wiley & Sons, Inc.     

Template-based fabrication of Ag–ZnO core–shell nanorod arrays

We report a simple, versatile, two-step fabrication technique for synthesizing a core–shell nanorod array whose architecture is specifically suited for use as an electrode in a dye sensitized solar cell (DSSC). The particular structure fabricated by us consists of a parallel array of 5 μm long and 150–200 nm wide Ag nanorod cores, each coated with a 15–20 nm thick ZnO shell. Importantly, the shell thickness is roughly uniform throughout the length of the rods, which are free standing but distinctly separated from each other. This would allow the dye to penetrate freely and cover the ZnO surface completely in a DSSC.     

Droplet synthesis of well-defined block copolymers using solvent-resistant microfluidic device

Well-defined diblock copolymers were synthesized via an exothermic RAFT route by a droplet microfluidic process using a solvent-resistant and thermally stable fluoropolymer microreactor fabricated by a non-lithographic embedded template method. The resulting polymers were compared to products obtained from continuous flow capillary reactor and conventional bulk synthesis. The droplet based microreactor demonstrated superior molecular weight distribution control by synthesizing a higher molecular weight product with higher conversion and narrow polydispersity in a much shorter reaction time. The high quality of the as-synthesized block copolymer PMMA-b-PS led to a generation of micelles with a narrow size distribution that could be used as a template for well-ordered mesoporous silica with regular frameworks and high surface areas.     

Calcium‐containing poly(urethane‐urea)s: Synthesis,spectral, and thermal studies

A calcium salt of mono(hydroxypentyl)phthalate [Ca(HPP)₂] was synthesized by the reaction of 1,5‐pentanediol, phthalic anhydride, and calcium acetate. Four different bisureas such as hexamethylene bis(ω,N‐hydroxyethylurea), tolylene 2,4‐bis(ω,N‐hydroxyethylurea), hexamethylene bis(ω,N‐hydroxypropylurea), and tolylene 2,4‐bis(ω,N‐hydroxypropylurea) were prepared by reacting ethanolamine or propanolamine with hexamethylene diisocyanate (HMDI) or tolylene 2,4‐diisocyanate (TDI). Calcium‐containing poly(urethane‐urea)s (PUUs) were synthesized by reacting HMDI or TDI with 1:1 mixtures of Ca(HPP)₂ and each of the bisureas with di‐n‐butyltin dilaurate as a catalyst. The PUUs were well characterized by Fourier transform infrared spectroscopy, ¹H and ¹³C NMR, solid‐state ¹³C–cross‐polarization/magic‐angle spinning NMR, viscosity, solubility, elemental analysis, and X‐ray diffraction studies. Thermal properties of the polymers were also examined with thermogravimetric analyses and differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1809–1819, 2004     

Multitude of core-localized shear Alfvén waves in a high-temperature fusion plasma

Evidence is presented for a multitude of discrete frequency Alfvén waves in the core of magnetically confined high-temperature fusion plasmas. Multiple diagnostic instruments confirm wave excitation over a wide spatial range from the device size at the longest wavelengths down to the thermal ion Larmor radius. At the shortest scales, the poloidal wavelengths are comparable to the scale length of electrostatic drift wave turbulence. Theoretical analysis confirms a dominant interaction of the modes with particles in the thermal ion distribution traveling well below the Alfvén velocity.     

A new methodology for identification of β-transus temperature in α + β and β titanium alloys using ultrasonic velocity measurement

A new methodology has been established for identification of β-transus temperature in α + β and β titanium alloys by ultrasonic velocity measurements in a single specimen in one microstructural condition only. This methodology is based on a linear correlation obtained for the variation in β-transus temperature with ultrasonic longitudinal wave velocity in various titanium alloys specimens, β-heat-treated followed by water quenching. Furthermore, it has been demonstrated for the first time that ultrasonic velocity in α′ martensitic structure increases with the addition of α-stabilizing elements and decreases with the addition of β-stabilizing elements for α + β titanium-alloys.     

Nondestructive characterization of musical pillars of Mahamandapam of Vitthala Temple at Hampi, India

This paper presents the first scientific investigation on the musical pillars of the Vitthala Temple at Hampi, India. The solid stone columns in these pillars produce audible sound, when struck with a finger. Systematic investigations on the acoustic characteristics of the musical pillars of mahamandapam (great stage) of the Vitthala Temple have been carried out. The 11 most popular pillars that produce sounds of specific musical instruments are considered for the investigations. The sound produced from these 11 most popular musical pillars was recorded systematically and different nondestructive testing techniques such as low frequency ultrasonic testing, impact echo testing, and in situ metallography were employed on the musical columns of these pillars. The peak frequencies in the amplitude spectrum of the sound produced from various columns in these pillars are correlated with the dimensional measurements and ultrasonic velocity determined using impact echo technique. The peak frequencies obtained experimentally have been found to have excellent correlation with the calculated flexural frequencies based on the dimensional measurements and ultrasonic velocities of the columns.     

Magnetization and structural studies of Mn doped ZnO nanoparticles: Prepared by reverse micelle method

Single phase Mn (2.5 at%) doped ZnO nanocrystalline samples were synthesized by reverse micelle method as characterized by Rietveld refinement analysis of X-ray diffraction data, high resolution transmission electron microscopy and selected area electron diffraction analyses. The X-ray photoelectron spectroscopy and electron paramagnetic resonance (EPR) studies indicated that manganese exist as Mn²⁺ in ZnO lattice. DC magnetization measurements as a function of field and temperature, of 2.5 at% Mn doped ZnO nanoparticles annealed at 675 K, showed room temperature ferromagnetism (RTF). This observation is further confirmed by the EPR spectrum of the sample, which shows a distinct ferromagnetic resonance signal at room temperature. These results indicate that the observed RTF in Mn-doped ZnO may be attributed to the substitutional incorporation of Mn at Zn sites.     

Quantum chemical computations and Fourier transform infrared spectral studies of a nonlinear food dye E110

Fourier transform infrared (FTIR) spectrum of a well-known food dye sunset yellow FCF (E110) has been recorded and analysed. Assignments of the vibrational spectrum has been facilitated by density functional theory (DFT) calculations. The results of the optimized molecular structure obtained on the basis of B3LYP with 6-31G(d) along with the 'LANL2DZ' basis sets give clear evidence for the intramolecular charge transfer (ICT) and strong hydrogen bonding enhancing the optical nonlinearity of the molecule. The first hyperpolarizability of the acidic monoazo dye 'E110' is computed. Azo stretching frequencies have been lowered due to conjugation and pi-electron delocalization. Hydroxyl vibrations with intramolecular H-bonding are analyzed, supported by the computed results. The natural bond orbitals (NBO) analysis confirms this strong hydrogen bond between the hydrogen of the hydroxyl group and nitrogen of the azo group of the molecule. Assignments of benzene and naphthalene ring vibrations are found to agree well with the theoretical wave numbers.