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1.
K. Porsezian K. Nithyanandan R. Vasantha Jayakantha Raja R. Ganapathy 《The European physical journal. Special topics》2013,222(3-4):625-640
The supercontinuum generation (SCG) in liquid core photonic crystal fiber (LCPCF) with versatile nonlinear response and the spectral broadening in dual core optical fiber is presented. The analysis is presented in two phase, phase I deals with the SCG in LCPCF with the effect of saturable nonlinearity and re-orientational nonlinearity. We identify and discuss the generic nature of the saturable nonlinearity and reorientational nonlinearity in the SCG, using suitable model. For the physical explanation, modulational instability and soliton fission techniques is implemented to investigate the impact of saturable nonlinear response and slow nonlinear response, respectively. It is observed that the saturable nonlinearity inevitably suppresses the MI and the subsequent SCG. On the other hand, the re-orientational nonlinearity contributes to the slow nonlinear response in addition to the conventional fast response due to the electronic contribution. The phase II features the exclusive investigation of the spectral broadening in the dual core optical fiber. 相似文献
2.
Sthanumoorthy Regupathy Madhavan Sivasankaran Nair 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):656-663
Equilibrium studies on the ternary complex systems involving ampicillin (amp) as ligand (A) and imidazole containing ligands viz., imidazole (Him), benzimidazole (Hbim), histamine (Hist) and histidine (His) as ligands (B) at 37 °C and I = 0.15 mol dm?3 (NaClO4) show the presence of CuABH, CuAB and CuAB2. The proton in the CuABH species is attached to ligand A. In the ternary complexes the ligand, amp(A) binds the metal ion via amino nitrogen and carbonyl oxygen atom. The CuAB (B = Hist/His)/CuAB2 (B = Him/Hbim) species have also been isolated and the analytical data confirmed its formation. Non-electrolytic behavior and monomeric type of chelates have been assessed from their low conductance and magnetic susceptibility values. The electronic and vibrational spectral results were interpreted to find the mode of binding of ligands to metal and geometry of the complexes. This is also supported by the g tensor values calculated from ESR spectra. The thermal behaviour of complexes were studied by TGA/DTA. The redox behavior of the complexes has been studied by cyclic voltammetry. The antimicrobial activity and CT DNA cleavage study of the complexes show higher activity for ternary complexes. 相似文献
3.
The effect of density inversion on transient natural convection heat transfer of cold water in a square cavity with partially
active vertical walls is studied numerically. The governing equations are solved by control volume method with power law scheme.
In the hot location the temperature is varied sinusoidally and in the cold location uniform temperature is maintained. Nine
different positions of the active zones are considered. Results are discussed for various values of the amplitude, period
and different Grashof numbers and presented graphically in the form of isotherms, streamlines, mid-height velocity profile
and average Nusselt number. It is found that density inversion of water affects natural convection flow and heat transfer.
Heat transfer rate is enhanced upto 80% when the heating location is in the middle of the hot wall. 相似文献
4.
Neelakantan MA Sundaram M Nair MS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1693-1703
Several mixed ligand Ni(II), Cu(II) and Zn(II) complexes of 2-amino-3-hydroxypyridine (AHP) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) have been synthesized and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as by magnetic moment values. On the basis of elemental analysis and molar conductance values, all the complexes can be formulated as [MAB]Cl except histidine complexes as MAB. Thermogravimetric studies reveal the presence of coordinated water molecules in most of the complexes. From the magnetic measurements and electronic spectral data, octahedral structure was proposed for Ni(II) and Cu(II)-AHP-his, tetrahedral for Cu(II)-AHP-him/bim/hist, but square planar for the Cu(II)-AHP complex. The g∥/A∥ calculated supports tetrahedral environment around the Cu(II) in Cu(II)-AHP-him/bim/hist and distorted octahedral for Cu(II)-AHP-his complexes. The morphology of the reported metal complexes was investigated by scanning electron micrographs (SEM). The potentiometric study has been performed in aqueous solution at 37 °C and I=0.15 mol dm(-3) NaClO4. MABH, MAB and MAB2 species has been identified in the present systems. Proton dissociation constants of AHP and stability constants of metal complexes were determined using MINIQUAD-75. The most probable structure of the mixed ligand species is discussed based upon their stability constants. The in vitro biological activity of the complexes was tested against the Gram positive and Gram negative bacteria, fungus and yeast. The oxidative DNA cleavage studies of the complexes were performed using gel electrophoresis method. Cu(II) complexes have been found to promote DNA cleavage in presence of biological reductant such as ascorbate and oxidant like hydrogen peroxide. 相似文献
5.
Numerical study on magneto-convection of cold water in an open cavity with variable fluid properties
S. Sivasankaran M. Bhuvaneswari Y.J. Kim C.J. Ho K.L. Pan 《International Journal of Heat and Fluid Flow》2011,32(5):932-942
The aim of the present study is to understand the problem of buoyancy and thermocapillary induced convection of cold water near its density maximum in an open cavity with temperature dependent properties in the presence of uniform external magnetic field. The governing equations are solved by the finite volume method. The results are discussed for various values of reference temperature parameter, density inversion parameter, Rayleigh, Hartmann and Marangoni numbers. It is observed that the temperature of maximum density leaves strong effects on fluid flow and heat transfer due to the formation of bi-cellular structure. Convection heat transfer is enhanced by thermocapillary force when buoyancy force is weakened. 相似文献
6.
Madhavan Sivasankaran Nair Dasan Arish Raphael Selwin Joseyphus 《Journal of Saudi Chemical Society》2012,16(1):83-88
Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from indole-3-carboxaldehyde and m-aminobenzoic acid were synthesized and characterized by elemental analysis, molar conductance, IR, UV–Vis, magnetic moment, powder XRD and SEM. The IR results demonstrate the bidentate binding mode of the ligand involving azomethine nitrogen and carboxylato oxygen atoms. The electronic spectral and magnetic moment results indicate that Co(II) and Ni(II) complexes have tetrahedral geometry, while Cu(II) complex is square planar. Powder XRD and SEM indicate the crystalline state and surface morphology studies of the complexes. The antimicrobial activity of the synthesized ligand and its complexes were screened by disc diffusion method. The results show that the metal complexes were found to be more active than the ligand. The nuclease activity of the ligand and its complexes were assayed on CT DNA using gel electrophoresis in the presence of H2O2. The Cu(II) complex showed increased nuclease activity in the presence of an oxidant when compared to the ligand and other complexes. 相似文献
7.
Prabakaran Rajendran Prasanna Naveen Kumar J. Mohan Lal Dhasan Selvam C. Harish Sivasankaran 《Journal of Thermal Analysis and Calorimetry》2020,139(2):941-952
Journal of Thermal Analysis and Calorimetry - In the present work, the melting behavior of a fatty acid-based phase change material (PCM) with the addition of functionalized graphene nanoplatelets... 相似文献
8.
M. Sivasankaran Nair P. Thillai Arasu M. Sankaranarayana Pillai C. Natarajan 《Transition Metal Chemistry》1995,20(2):132-135
Summary Stability constants for mixed-ligand complexes of the types [NiABH2], [NiABH] and [NiAB] formed by NiII with l-cysteine (cys), d-penicillamine (pen) or l-cysteic acid (cya) as ligand A and dl-2,3-diaminopropionic acid (dapa), dl-2,4-diaminobutyric acid (daba) or dl-ornithine (orn) as ligand B have been determined by the computerbased analysis of pH titration data obtained at 37 °C and I = 0.15 mol dm–3 (NaClO4). In the [NiABH] species, for all three secondary ligands (B), when A = pen or cya the labile proton appears to be attached to the terminal amino group of ligand B, whereas when A = cys it is not clear where the proton is located. In all the systems in the [NiABH2] species, one proton resides with the primary ligand (A) and the other with the secondary ligand (B). In the [NiAB]-type complexes, cys and pen chelate through the amino and thiolato groups, while cya binds in a glycine-like mode and the secondary ligands (B) coordinate in a terdentate manner.Author to whom all correspondence should be directed. 相似文献
9.
The Schiff base ligand derived from indole-3-carboxaldehyde(indal) and glycylglycine(glygly) were synthesized and characterized by elemental analysis, IR, electronic spectrum, 1H NMR and mass spectrum. Co(II), Ni(II) and Cu(II)–indal-glygly Schiff base complexes were synthesized and characterized by elemental analysis, molar conductance, IR, electronic spectra, magnetic measurements, ESR, electrochemical studies, TGA, DSC analysis, XRD and SEM. Conductance measurements indicate that the above complexes are 1:1 electrolytes. IR spectral data show that the ligand is tridentate and the binding sites are azomethine nitrogen, peptide nitrogen and carboxylato oxygen atoms. Electronic spectral measurements indicate tetrahedral geometry for Co(II) and Ni(II) complexes and square planar geometry for Cu(II) complex. Magnetic measurements show weak ferromagnetic behaviour for Co(II) and Ni(II) complexes and paramagnetic behaviour for Cu(II) complex. ESR spectral data shows the ionic link between metal and the Schiff base ligand. The metal complexes are found to be stabilized in the unusual oxidation states of the metal ion during electrolysis. Thermal analysis of the complex indicates that the decomposition takes place in three steps. IR and thermal studies indicate that the fourth position would be occupied by a water molecule in complexes. XRD shows that the complexes have the crystallite size of 31, 40 and 67 nm, respectively. The surface morphology of the complexes was studied by SEM. The antimicrobial activity of the ligand and its complexes were screened by Kirby Bayer Disc Diffusion method. DNA cleavage studies were performed for metal–Schiff base complexes in presence of hydrogen peroxide as oxidant. 相似文献
10.
A numerical study has been performed to analyze the combined effect of temperature and species gradients on the buoyancy-driven
natural convection flow of cold water near its density extremum contained in a porous cavity. The governing equations are
descretized using the finite volume method. The results of the investigation are presented in the form of steady-state streamlines,
velocity vectors, isotherms, and isoconcentrationlines. The results are discussed for different porosities, Darcy numbers,
and Grashof numbers. The heat and mass transfer rates calculated are found to behave nonlinearly with hot wall temperature.
The heat and mass transfer are increased with increasing Darcy number and porosity. It is found that the convective heat and
mass transfer rate are greatly affected by the presence of density maximum. 相似文献