57Fe Mössbauer studies in a new cluster spin glass system RuxFeGa (0.5≦x≦1.5)

⁵⁷Fe Mössbauer and bulk magnetization studies have been carried out in a new magnetic system Ru_xFeGa for 0.5x1.5. The system is seen to freeze into a cluster spin glass phase at 70 K. The freezing temperature and the hyperfine field at Fe at the lowest measured temperature, 190 kOe, is essentially same for all values of x investigated.     

A comparative study of vibrational dynamics of α- and β-forms of poly(β-hydroxybutyrate)

Normal modes and their dispersion are obtained for planar zig-zag form of poly(β-hydroxybutyrate) using Urey-Bradley force field. A comparison is made with the spectra of its helical form. Apart from detailed assignment of modes, various characteristic features of dispersion curves have been explained as arising due to internal symmetry in energy momentum space. The density-of-states have been used to calculate heat capacity in the temperature range 10-450 K using Debye's formalism.     

Ion-exchangers in radioactive waste management Part XIV: Removal behavior of hydrous titanium oxide and sodium titanate for Cs(I)

The removal behavior of hydrous titanium oxide and sodium titanate for Cs(I) from aqueous solutions by radiotracers was studied. Batch experiments revealed that an increase in Cs concentration (10^–8 to 10^–2 mol·dm^–3), temperature (298 to 328 K) and pH (2.50 to 10.20) apparently enhanced the uptake of Cs(I) on hydrous titanium oxide whereas a high degree of uptake of Cs(I) on sodium titanate was almost unaffected by a change in adsorption temperature (298 to 328 K) and pH (2.50 to 10.20). Both systems follow Freundlich adsorption isotherm. Uptake of Cs(I) on hydrous titanium oxide obeys first order rate law. According to thermodynamic data the uptake is endothermic and apparently irreversible in nature.This revised version was published online in November 2005 with corrections to the Cover Date.     

Selective photodissociation of O-H and O-D bonds from ground vibrational state of HOD using simple UV pulses

Selective cleaving of both O-H and O-D bonds in HOD is achieved using reasonably simple UV pulses to excite the HOD molecule in its ground vibrational state to the repulsive first excited A ((1)B(1)) surface. Detailed theoretical analysis of population transfer and flux in the H+O-DH-O+D channels reveals an important preparatory role for the cross-talk between the participating levels and a possible role for the beat structure of the population transfer oscillations in facilitating selective dissociation. Excitation using a 50 fs single color 67,169 cm(-1) laser pulse achieves a branching ratio H+O-DH-O+D=5.64 with 82% flux in the H+O-D channel and 15% in the H-O+D channel. A two color 50 fs laser pulse with frequencies of 54 920 and 52 303 cm(-1) provides a branching ratio of H-O+DH+O-D=2.83 and 52% flux in the H-O+D channel and 18% in the H+O-D channel.     

Copper(II) complexes with bioactive carboxyamide: synthesis, characterization and biological activity

Complexes of Cu(II) with bioactive carboxyamide ligands N',N'-bis(3-carboxy-1-oxoprop-2-enyl)2-amino-N-arylbenzamidine, N',N'-bis(3-carboxy-1-oxopropanyl)2-amino-N-arylbenzamidine and N',N'-bis(3-carboxy-1-oxophenelenyl)2-amino-N-arylbenzamidine have been synthesized and characterized by various physico-chemical techniques. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML complexes. Vibrational spectra indicate coordination of amide and carboxylate oxygen of the ligands along with water molecules. Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for Cu(II) complexes. The EPR of the reported complex show g( parallel)>g( perpendicular)>2.0023 and G value within the range 2.08-4.49 are consistent with [Formula: see text] ground state in an octahedral geometry. The voltammogram of the copper(II) complex shows a quasi-reversible redox process and a simple one electron process assignable to the Cu(II)/Cu(I) couple. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The bio-efficacy of the ligands and its copper complexes have been examined against the growth of bacteria and pathogenic fungi in vitro to evaluate their antimicrobial potential. The results indicate that the ligand and its metal complexes possess notable antimicrobial properties.     

Inorganic ion-exchangers in radioactive waste management</p> </p>

Summary The uptake of indigenously synthesized amorphous stannic and zirconium phosphate was assessed for, one of the important fission fragment, cesium from aqueous solutions using a radiotracer technique. A virtual increase in sorptive concentration (from 1.0 ^. 10^-8 to 1.0 ^. 10^-2 mol ^. dm^-3) and pH (from 2.4 to 10.2) and temperature (from 303 to 333 K) enhanced the uptake of cesium on stannic phosphate. However, the extremely high degree of uptake of cesium on zirconium phosphate was almost unaffected with the dilution beyond 10^-5 mol ^. dm^-3 and pH (i.e., from 2.4 to 10.2) and temperature (from 303 to 323 K). Irreversible uptake occurring for these solids follow the Freundlich adsorption isotherm and the presence of several complexing agents viz., sulphate, phosphate, glycine and EDTA did not affect appreciably the uptake of cesium on zirconium phosphate but it did affect for stannic phosphate system. Both these solids showed good radiation stability towards a 11.1 GBq Ra-Be neutron source having neutron flux ca. 3.2 ^. 10⁶ n ^. cm^{-2 .} s^-1 and associated with a nominalg-dose of ca. 1.72 Gy/h, at least for the uptake of cesium.</p> </p>     

Pd-gate MOS sensor for detection of methanol and propanol

The present paper focused on the detection of methanol and propanol using Pd-gate metal-oxide-semiconductor (MOS) sensor. Surface mor- phology and composition of the gate film were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The response of the sensor for propanol and methanol was measured as shift in capacitance-voltage (C-V) and conductance-voltage (G-V) curves of the MOS structure. The sensitivity of the sensor towards methanol was found to be greater than that towards propanol. It was 58.2% for methanol and 32% for propanol (at 0.6 V, 1 MHz) in terms of capacitance measurements, while in terms of conductance results the sensitivity was found to be 57.2% for methanol and 38.9% for propanol at 1 kHz. The discontinuities or cracks present in the microstructure of the gate material are believed to be mainly responsible for the high sensitivity of the sensor, going with the decomposition of gas molecules and subsequent hydrogen permeation through Pd.     

Effect of the coupling agent's reactivity on the shrinkability of the blends consisting of grafted low‐density polyethylene and ethylene acrylic elastomer

Blends prepared by melt mixing of thermoplastic elastomer have gained considerable attention in recent years from a heat shrinkability point of view. Our present study deals with the measurement of heat shrinkability of the maleic anhydride grafted low‐density polyethylene and ethylene acrylic elastomer. Two samples have been prepared to study the effect of coupling agent's reactivity on the shrinkability of the blends. The coupling agents used are 4,4′‐diamino diphenyl sulphone, and 4,4′‐diamino diphenyl methane. Shrinkability was measured at room temperature, 120 °C, 150 °C, and 180 °C. Shrinkability is found to be greater in high temperature stretched sample rather than that of room temperature stretched sample. It is observed that reactivity as well as heat shrinkability is more when 4,4′‐diamino diphenyl methane is used as a coupling agent. The mechanism of interchain crosslinking reaction has been confirmed by IR spectroscopy. Differential scanning calorimetry was performed to study the thermal stability of the sample. Copyright © 2002 John Wiley & Sons, Ltd.     

Analysis of Thermodynamic Parameters of Glass Forming Polymeric Melts

The temperature dependence of the Gibbs free energy difference (ΔG), enthalpy difference (ΔH) and entropy difference (ΔS) between the undercooled meltand the corresponding equilibrium solid has been analysed for glass forming polymeric materials by calculating ΔG, ΔH and ΔS within the framework of the hole theory of liquids. The study is made for nine samples of glass forming polymeric melts; polypropylene oxide (PPO), polyamid-6 (PA-6), polytetramethylene oxide (PTMO), polyethylene oxide (PEO), polystyrene (PS), polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET) and polybutadiene (PB) and three simple organic liquids: tri-α-naphthyl benzene (tri-α-NB), o-terphenyl (o-ter) and phenyl salicylate (salol) in the entire temperature range T _m (melting temperature) to T _g (glass transition temperature). The ideal glass transition temperature (T _K) and the residual entropy (ΔS _R) of these samples have also been studied due to their important role in the study of the glass forming ability of materials. This revised version was published online in August 2006 with corrections to the Cover Date.