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991.
Ilija Najdovski Anthony P. O'Mullane Suresh K. Bhargava 《Electrochemistry communications》2010,12(11):1535-1538
The galvanic replacement reaction has received considerable interest due to the creation of novel bimetallic nanomaterials that minimise the use of expensive metals while maintaining enhanced electrocatalytic properties for certain reactions. In this work we investigate the galvanic replacement of electrochemically synthesised iron nanocubes on glassy carbon, with gold and palladium. The resultant nanomaterials demonstrate quite a difference in morphology; the original cuboid like template is maintained in the case of gold but destroyed when palladium is used. The electrochemical and electrocatalytic behaviours of these materials are reported for reactions such as methanol oxidation, hydrogen evolution and oxygen reduction. 相似文献
992.
Sangeeta Sharma Suresh Magotra Sushil K. Pandey 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):2140-2151
Reactions of (m- and p-ClC 6 H 4 NH 2 ), (p-BrC 6 H 4 NO 2 ), and (p-ClCOC 6 H 4 NO 2 ) with sodium O,O′-ditolyl/dibenzylphosphorodithionates, (ArO) 2 PS 2 Na, (Ar = o?, m?, and p?CH 3 C 6 H 4 or –C 6 H 5 CH 2 ) in 1:1 molar ratio in refluxing toluene under anhydrous conditions resulted in the formation of the compounds (ArO) 2 PS 2 C 6 H 4 L and (ArO) 2 PS 2 COC 6 H 4 L (L = NH 2 or NO 2 ) in 87–94% yield. These viscous compounds were characterized by elemental analyses, molecular weight determination, and IR and NMR ( 1 H, 13 C, and 31 P) spectroscopic studies, which revealed a monodentate mode of bonding of the dithiophosphate moiety with the carbon of the phenyl ring of the organic moiety leading to a P–S–C linkage. 相似文献
993.
The purpose of this paper is to review and summarize the literature on the joint replenishment problem (JRP) since 1989. Our review indicates that while research on the basic form of the JRP under the original classic assumptions may have slowed, there is much interest in new versions of the problem with relaxed assumptions, including dynamic or stochastic demand. Furthermore, recent research on the problem has focused on finding faster algorithms to the classic JRP rather than on improving the solution quality. 相似文献
994.
M. Chandrasekar S. Suresh A. Chandra Bose 《Experimental Thermal and Fluid Science》2010,34(2):122-130
In this paper, fully developed laminar flow convective heat transfer and friction factor characteristics of Al2O3/water nanofluid flowing through a uniformly heated horizontal tube with and without wire coil inserts is presented. For this purpose, Al2O3 nanoparticles of 43 nm size were synthesized, characterized and dispersed in distilled water to form stable suspension containing 0.1% volume concentration of nanoparticles. The Nusselt number in the fully developed region were measured and found to increase by 12.24% at Re = 2275 for plain tube with nanofluid compared to distilled water. Two wire coil inserts made of stainless steel with pitch ratios 2 and 3 were used which increased the Nusselt numbers by 15.91% and 21.53% respectively at Re = 2275 with nanofluid compared to distilled water. The better heat transfer performance of nanofluid with wire coil insert is attributed to the effects of dispersion or back-mixing which flattens the temperature distribution and make the temperature gradient between the fluid and wall steeper. The measured pressure loss with the use of nanofluids is almost equal to that of the distilled water. The empirical correlations developed for Nusselt number and friction factor in terms of Reynolds/Peclet number, pitch ratio and volume concentration fits with the experimental data within ±15%. 相似文献
995.
996.
This paper investigates the nature of information contained in scatter correction parameters. The study had two objectives. The first objective was to examine the nature and extent of information contained in scatter correction parameters. The second objective is to examine whether this information can be effectively extracted by proposing a method to obtain particularly the mean particle diameter from the scatter correction parameters. By using a combination of experimental data and simulated data generated using fundamental light propagation theory, a deeper and more fundamental insight of what information is removed by the multiplicative scatter correction (MSC) method is obtained. It was found that the MSC parameters are strongly influenced not only by particle size but also by particle concentration as well as refractive index of the medium. The possibility of extracting particle size information in addition to particle concentration was considered by proposing a two-step method which was tested using a 2-component and 4-component data set. This method can in principle, be used in conjunction with any scatter correction technique provided that the scatter correction parameters exhibit a systematic dependence with respect to particle size and concentration. It was found that the approach which uses the MSC parameters gave a better estimate of the particle diameter compared to using partial least squares (PLS) regression for the 2-component data. For the 4 component data it was found that PLS regression gave better results but further examination indicated this was due to chance correlations of the particle diameter with the two of the absorbing species in the mixture. 相似文献
997.
M Rajasekhar KU Maheswara Rao CS Sundar NB Reddy SK Nayak CS Reddy 《Chemical & pharmaceutical bulletin》2012,60(7):854-858
A simple and efficient one pot synthesis of 2-amino-4H-chromen-4-yl phosphonate derivatives has been accomplished by the condensation of salicylaldehyde, malononitrile/ethylcyanoacetate and triethyl phosphite/trimethyl phosphite in the presence of molecular iodine as catalyst in water at room temperature. All the reactions were very clean and the products were obtained in very good to excellent yields. The title compounds are characterized by IR, 1H-, 13C-, 31P-NMR and mass spectra, also studied their antimicrobial and antioxidant activity. 相似文献
998.
Kunda UM Balam SK Nemallapudi BR Chereddy SS Nayak SK Cirandur SR 《Chemical & pharmaceutical bulletin》2012,60(1):104-109
A green and efficient preparation method for the amino bisphosphonates is accomplished by simple mixing and stirring of diethylphosphite, triethylorthoformate and various amines in the presence of amberlyst-15 as catalyst at room temperature under solvent free conditions. The title compounds are characterized by IR, (1)H-, (13)C-, (31)P-NMR and mass spectra, also studied their antimicrobial and antioxidant activity. 相似文献
999.
Saha S Mahato P Reddy G U Suresh E Chakrabarty A Baidya M Ghosh SK Das A 《Inorganic chemistry》2012,51(1):336-345
A new rhodamine-based receptor, derivatized with an additional fluorophore (quinoline), was synthesized for selective recognition of Hg(2+) and Cr(3+) in an acetonitrile/HEPES buffer medium of pH 7.3. This reagent could be used as a dual probe and allowed detection of these two ions by monitoring changes in absorption and the fluorescence spectral pattern. In both instances, the extent of the changes was significant enough to allow visual detection. More importantly, the receptor molecule could be used as an imaging reagent for detection of Hg(2+) and Cr(3+) uptake in live human cancer cells (MCF7) using laser confocal microscopic studies. Unlike Hg(ClO(4))(2) or Hg(NO(3))(2) salts, HgCl(2) or HgI(2) failed to induce any visually detectable change in color or fluorescence upon interaction with L(1) under identical experimental conditions. Presumably, the higher covalent nature of Hg(II) in HgCl(2) or HgI(2) accounts for its lower acidity and its inability to open up the spirolactam ring of the reagent L(1). The issue has been addressed on the basis of the single-crystal X-ray structures of L(1)·HgX(2) (X(-) = Cl(-) or I(-)) and results from other spectral studies. 相似文献
1000.
Loganathan R Ramakrishnan S Suresh E Riyasdeen A Akbarsha MA Palaniandavar M 《Inorganic chemistry》2012,51(10):5512-5532
A series of mononuclear mixed ligand copper(II) complexes [Cu(bba)(diimine)](ClO(4))(2)1-4, where bba is N,N-bis(benzimidazol-2-ylmethyl)amine and diimine is 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp) (3), or dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) (4), have been isolated and characterized by analytical and spectral methods. The coordination geometry around copper(II) in 2 is described as square pyramidal with the two benzimidazole nitrogen atoms of the primary ligand bba and the two nitrogen atoms of phen (2) co-ligand constituting the equatorial plane and the amine nitrogen atom of bba occupying the apical position. In contrast, the two benzimidazole nitrogen atoms and the amine nitrogen atom of bba ligand and one of the two nitrogen atoms of 5,6-dmp constitute the equatorial plane of the trigonal bipyramidal distorted square based pyramidal (TBDSBP) coordination geometry of 3 with the other nitrogen atom of 5,6-dmp occupying the apical position. The structures of 1-4 have been optimized by using the density functional theory (DFT) method at the B3LYP/6-31G(d,p) level. Absorption spectral titrations with Calf Thymus (CT) DNA reveal that the intrinsic DNA binding affinity of the complexes depends upon the diimine co-ligand, dpq (4) > 5,6-dmp (3) > phen (2) > bpy (1). The DNA binding affinity of 4 is higher than 2 revealing that the π-stacking interaction of the dpq ring in between the DNA base pairs with the two bzim moieties of the bba ligand stacked along the DNA surface is more intimate than that of phen. The complex 3 is bound to DNA more strongly than 1 and 2 through strong hydrophobic interaction of the methyl groups on 5,6-positions of the phen ring in the DNA grooves. The extent of the decrease in relative emission intensities of DNA-bound ethidium bromide (EB) upon adding the complexes parallels the trend in DNA binding affinities. The large enhancement in relative viscosity of DNA upon binding to 3 and 4 supports the DNA binding modes proposed. Interestingly, the 5,6-dmp complex 3 is selective in exhibiting a positive induced CD band (ICD) upon binding to DNA suggesting that it induces a B to A conformational change. In contrast, 2 and 4 show induced CD responses indicating their involvement in strong DNA binding. Interestingly, only the dpq complex 4, which displays the strongest DNA binding affinity and is efficient in cleaving DNA in the absence of an activator with a rate constant of 5.8 ± 0.1 h(-1), which is higher than the uncatalyzed rate of DNA cleavage. All the complexes exhibit oxidative DNA cleavage ability, which varies as 4 > 2 > 3 > 1 (ascorbic acid) and 3 > 2 > 4 > 1 (H(2)O(2)). Also, the complexes cleave the protein bovine serum albumin in the presence of H(2)O(2) as an activator with the cleavage ability varying in the order 3 > 4 > 2 > 1. The highest efficiency of 3 to cleave both DNA and protein in the presence of H(2)O(2) is consistent with its strong hydrophobic interaction with the biopolymers. The IC(50) values of 1-4 against cervical cancer cell lines (SiHa) are almost equal to that of cisplatin, indicating that they have the potential to act as effective anticancer drugs in a time-dependent manner. The morphological assessment data obtained by using acridine orange/ethidium bromide (AO/EB) and Hoechst 33258 staining reveal that 3 induces apoptosis much more effectively than the other complexes. Also, the alkaline single-cell gel electrophoresis study (comet assay) suggests that the same complex induces DNA fragmentation more efficiently than others. 相似文献