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     

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.     

Molecular structure, spectroscopic studies and first-order molecular hyperpolarizabilities of p-amino acetanilide

The infrared absorption, Raman spectra and SERS spectra of p-amino acetanilide have been analyzed with the aid of density functional theory calculations at B3LYP/6-311G(d,p) level. The electric dipole moment (mu) and the first hyperpolarizability (beta) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the synthesized molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. Computed geometries reveal that the PAA molecule is planar, while secondary amide group is twisted with respect to the phenyl ring is found, upon hydrogen bonding. The hyperconjugation of the C=O group with adjacent C-C bond and donor-acceptor interaction associated with the secondary amide have been investigated using computed geometry. The carbonyl stretching band position is found to be influenced by the tendency of phenyl ring to withdraw nitrogen lone pair, intermolecular hydrogen bonding, conjugation and hyperconjugation. The existence of intramolecular C=O...H hydrogen bonded have been investigated by means of the natural bonding orbital (NBO) analysis. The influence of the decrease of N-H and C=O bond orders and increase of C-N bond orders due to donor-acceptor interaction has been identified in the vibrational spectra. The SERS spectral analysis reveals that the large enhancement of in-plane bending, out of plane bending and ring breathing modes in the surface-enhanced Raman scattering spectrum indicates that the molecule is adsorbed on the silver surface in a 'atleast vertical' configuration, with the ring perpendicular to the silver surface.     

Antiacetylcholinesterase and antioxidant ent-Kaurene diterpenoid, melissoidesin from Isodon wightii (Bentham) H. Hara

The ent kaurene diterpenoid, melissoidesin was isolated from the acetone extract of the leaves of Isodon wightii and the structure was designated as 3beta, 11beta, 15beta-trihydroxy-6alpha-acetoxy-ent-kaur-16-ene based on spectral data and previous reports. Melissoidesin isolated from the acetone extract of leaves showed potent antiacetylcholinesterase activity and the IC(50) value was observed as 215 microg mL(-1). DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical scavenging activity of melissoidesin was significant and the IC(50) value was 138 microg mL(-1). The significant reducing property of the melissoidesin was stronger in high concentration. IC(50) value of melissoidesin on hydroxyl radicals and metal chelation was observed as 99 and 143 microg mL(-1), respectively. The 50% inhibitory concentration of melissoidesin on lipid peroxidation was calculated as 133 microg mL(-1). These findings indicate that ent kaurene diterpenoid, melissoidesin was promising antiacetylcholinesterase and antioxidant which can be used as food and drug preparations.     

Direct Synthesis of Protoberberine Alkaloids by Rh‐Catalyzed C−H Bond Activation as the Key Step

A one‐pot reaction of substituted benzaldehydes with alkyne–amines by a Rh‐catalyzed C?H activation and annulation to afford various natural and unnatural protoberberine alkaloids is reported. This reaction provides a convenient route for the generation of a compound library of protoberberine salts, which recently have attracted great attention because of their diverse biological activities. In addition, pyridinium salt derivatives can also be formed in good yields from α,β‐unsaturated aldehydes and amino–alkynes. This reaction proceeds with excellent regioselectivity and good functional group compatibility under mild reaction conditions by using O₂ as the oxidant.     

Synthesis and characterization of stoichiometric NiCo nano particles dispersible in both aqueous and non aqueous media

Oleic acid (OA) coated stoichiometric NiCo (50:50) nanoparticles, with and without polyvinylpyrrolidone (PVP) coating, dispersible in aqueous and non aqueous media have been synthesized by a polyol process for the first time. Structural studies by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed the formation of an impurity free face centred cubic phase NiCo alloy. EDS analysis confirmed nearly 50:50 alloy composition. The magnetization, as a function of field and temperature, of these samples showed a soft ferromagnetic nature. The novelty of our method is that the particles are dispersible in non aqueous and aqueous media, which will facilitate preparation of films of these particles.     

Nonlinear free vibration analysis of simply supported piezo-laminated plates with random actuation electric potential difference and material properties

Studies are made on nonlinear free vibrations of simply supported piezo-laminated rectangular plates with immovable edges utilizing Kirchoff’s hypothesis and von Kármán strain–displacement relations. The effect of random material properties of the base structure and actuation electric potential difference on the nonlinear free vibration of the plate is examined. The study is confined to linear-induced strain in the piezoelectric layer applicable to low electric fields. The von Kármán’s large deflection equations for generally laminated elastic plates are derived in terms of stress function and transverse deflection function. A deflection function satisfying the simply supported boundary conditions is assumed and a stress function is then obtained after solving the compatibility equation. Applying the modified Galerkin’s method to the governing nonlinear partial differential equations, a modal equation of Duffing’s type is obtained. It is solved by exact integration. Monte Carlo simulation has been carried out to examine the response statistics considering the material properties and actuation electric potential difference of the piezoelectric layer as random variables. The extremal values of response are also evaluated utilizing the Convex model as well as the Multivariate method. Results obtained through the different statistical approaches are found to be in good agreement with each other.