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61.
Brajesh Pandey M. P. C. Kalita A. Perumal A. Srinivasan H. C. Verma 《Hyperfine Interactions》2008,183(1-3):147-153
Iron nitrides are attractive as they show excellent magnetic properties which can be utilized as recording and permanent magnetic materials for potential applications. Due to the high saturation magnetization and chemical stability, γ ′-Fe4N compound is widely investigated as a promising high density magnetic recording material. γ ′-Fe4N particles were synthesized by conventional gaseous nitriding in a heated atmosphere containing ammonia as a source of nitrogen. X-ray diffraction, 57Fe Mössbauer spectroscopy, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy are used for the characterization of the as prepared sample. 相似文献
62.
V. Srinivasa Rao A. B. Samui 《Journal of polymer science. Part A, Polymer chemistry》2009,47(8):2143-2155
A series of main chain photoactive liquid crystalline polyethers, containing rigid bisbenzylidene photoactive mesogen and flexible methylene spacers, were synthesized by polycondensation of bisbenzylidene diols and dibromoalkanes. The polyethers were characterized with 1H NMR, gel permeation chromatography (GPC), differential scanning calorimeter (DSC), thermo gravimetric analyzer (TGA), and polarized light optical microscopy. The individual and combined effects of spacer length and number of methoxy substituents on mesogenic and photoactive properties were investigated. Both first order and second order transition temperatures decreased with increased spacer length and the number of substituents. The combined effect of spacers and substituents drastically reduced the transition temperatures. All monomers and polymers showed mainly the smectic mesophase. In a few cases, nematic droplets along with the smectic phase were observed. The width of the liquid crystalline phase reduced with an increasing number of methoxy substituents on mesogenic unit. Variation of spacer length has a negligible effect on photocycloaddition. However, steric hinderance caused by the substituents decreased the photoactivity as the number of substituents increased. Total energies of crosslinked dimers calculated from modeling studies supported the above findings. Intermolecular photocycloaddition was also confirmed by photoviscosity measurement. The refractive index change was found to be in the range of 0.017–0.031. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2143–2155, 2009 相似文献
63.
Alfi Khatib Vikneswari Perumal Qamar Uddin Ahmed Bisha Fathamah Uzir Faridah Abas Suganya Murugesu 《Analytical letters》2017,50(12):1977-1991
Momordica charantia is widely consumed edible fruit. The food and pharmaceutical industries use it as a natural antioxidant. However, the quality control of M. charantia-based medicinal products is questionable due to the complexity of metabolites in this fruit. Hence, this study has developed a statistical model in predicting the antioxidant value through the 2, 2-diphenyl-1 picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power based on infrared spectroscopy with attenuated total reflectance. This technique was reliably used for quality control. Six ethanol extracts (0, 20, 40, 60, 80, and 100% in water) of this plant’s fruit were prepared. The radical scavenging and ferric reducing antioxidant power activities were measured and the chemical profiling of the extracts was fingerprinted by infrared spectroscopy between 4,000 and 600?cm?1 at a resolution of 4?cm?1. Statistical analysis was developed by correlating the bioactivity and infrared spectra of each extract using orthogonal partial least square discriminant analysis. The C–N, C?O, C–O, C–H, and OH infrared signals were positively correlated with biological activity. The antioxidant activity of the fruit of M. charantia may be due to the presence of several antioxidants that work synergistically. 相似文献
64.
Srinivasa Budagumpi M. P. Sathisha Naveen V. Kulkarni Gurunath S. Kurdekar Vidyanand K. Revankar 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(3-4):327-333
A series of new 24-membered macrocyclic CoII, NiII, CuII and ZnII complexes of the ligands L1H2 and L2H2 were prepared by the non-template and template methods respectively. The ligand L1H2 was formed by the condensation of pyrazole-3,5-dicarbohydrazide and glyoxal and all attempts to isolate the ligand L2H2 were unsuccessful. These, ligand and transition metal complexes were characterized on the basis of elemental analysis, IR, 1HNMR, UV–Visible, magnetic susceptibility measurements, ESR, conductivity measurements, FAB-mass and thermal analysis. The redox behavior of metal ions in the polyazamacrocyclic ligand field is also studied. Electroreduction of carbon dioxide to carbon monoxide is mainly focused on using polydentate azamacrocyclic ligands with amine and imine functionalities, based on the electrochemical behavior of nickel (II) ion in the macrocyclic territory. 相似文献
65.
Ranganathan Velu 《Tetrahedron letters》2010,51(33):4331-9264
The aza-crown ether acridinedione-functionalized gold nanoparticles (ACEADD-GNPs) 6 have been synthesized and investigated as a fluorescent chemosensor for metal ions. A blue shift along with an intensity enhancement of emission and color change are observed in the presence of both Ca2+ and Mg2+ ions. The enhanced fluorescence intensity is attributed to the photoinduced electron transfer (PET) suppression through space and color change of the suspension from red to blue due to shifted surface plasmon resonance (SPR) with aggregation of nanoparticles by the sandwich complexation. 相似文献
66.
J.S. Yadav B.V. Subba Reddy T. Srinivasa Rao K. Bhavani A. Raju 《Tetrahedron letters》2010,51(19):2622-4577
The vinyl arenes undergo smooth hydroalkylation with 1,3-diketones in the presence of 10 mol % of iodine to afford phenethyl diketones and ketoesters in good yields in short reaction times. The use of inexpensive and readily available molecular iodine makes this method quite simple, more convenient and practical. 相似文献
67.
The design and synthesis of 1,3-dithiol linked acridinedione functionalized gold nanoparticles (ADDDT-GNP) is described. ADDDT-GNP was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), UV-vis, steady-state and time-resolved fluorescence techniques. Conformational analysis of 1,3-dithiol ligands using density functional theory (DFT) reveals that they can cap on gold clusters through 1,2-capping mode, in which the two sulfur atoms of the dithiol bind covalently with two adjacent gold atoms on the surface of the cluster. The present study shows that three conformers of the ligand can cap in the 1,2-mode of capping. The triexponential fluorescence decay observed in the capped nanogold complex with fluorophore-labeled 1,3-dithiol may originate from the three conformers of the complex in the 1,2-capping mode. 相似文献
68.
Borak JB Lee HY Raghavan SR Falvey DE 《Chemical communications (Cambridge, England)》2010,46(47):8983-8985
Photorelease and photoisomerization of trans-cinnamic acid in aqueous CTAB solutions induces a bulk solution viscosity increase and decrease, respectively, triggered by orthogonal irradiation wavelengths. 相似文献
69.
Kulkarni NV Budagumpi S Kurdekar GS Revankar VK Didagi S 《Chemical & pharmaceutical bulletin》2010,58(12):1569-1575
A novel Cu(II) and Zn(II) complexes of triazolo-quinoline derivatives were synthesized by in situ method and were characterized by the spectro-analytical methods and their pharmacological properties were evaluated. The compound C3 has exhibited promising anticonvulsant activity towards the electroshock induced seizures in Wistar rats and possesses low toxicity, providing a high safety profile. 相似文献
70.
T. SrikumarM.G. Brik Ch. Srinivasa RaoN. Venkatramaiah Y. GandhiN. Veeraiah 《Physica B: Condensed Matter》2011,406(19):3592-3598
Li2O-ZrO2-SiO2: Ho3+ glasses mixed with three interesting d-block elemental oxides, viz., Nb2O5, Ta2O5 and La2O3, were prepared. Optical absorption and photoluminescence spectra of these glasses have been recorded at room temperature. The luminescence spectra of Nb2O5 and Ta2O5 mixed Li2O-ZrO2-SiO2 glasses (free of Ho3+ ions) have also exhibited broad emission band in the blue region. This band is attributed to radiative recombination of self-trapped excitons (STEs) localized on substitutionally positioned octahedral Ta5+ and Nb5+ ions in the glass network. The Judd-Ofelt theory was successfully applied to characterize Ho3+ spectra of all the three glasses. From this theory various radiative properties, like transition probability A, branching ratio βr and the radiative lifetime τr, for 5S2 emission levels in the spectra of these glasses have been evaluated. The radiative lifetime for 5S2 level of Ho3+ ions has also been measured and quantum efficiencies were estimated. Among the three glasses studied the La2O3 mixed glass exhibited the highest quantum efficiency. The reasons for such higher value have been discussed based on the relationship between the structural modifications taking place around the Ho3+ ions. 相似文献