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61.
S. Aravamudhan K. Luongo P. Poddar H. Srikanth S. Bhansali 《Applied Physics A: Materials Science & Processing》2007,87(4):773-780
We report the fabrication and characterization of porous silicon templates for electrodeposition of high aspect ratio one-dimensional
metallic nanostructures (nanowires/nanoparticles) in them. Even though nanostructures/nanowires in the past have been fabricated
in alumina, polymer or silica templates, the advantages of this approach are the possibility for seamless integration of nanostructures
with other silicon components, and silicon based sensors because of better physical and electrical interconnection between
the nanostructure and the silicon substrate. In this work, fabrication and characterization of nanowires/nanostructures such
as single-segment Ni–Fe and Au and two-segment Ni–Fe/Au electrodeposited in the porous silicon template are presented. The
templates with ordered and controlled nanometer-sized pores, 40 nm and 290 nm in diameter, were created through porous Si
etching. The morphology, composition and structural characteristics of the template and of the single-segment Ni–Fe and Au
and two-segment Ni–Fe/Au nanostructures of diameter 275±25 nm, length up to 100 μm and pitch of 1 μm were analyzed using scanning
electron microscopy and X-ray diffraction techniques. The micrographs confirm that the plating parameters have a strong influence
on morphology and composition of the structures. Further, the Ni–Fe images show the formation of both vertical and branched
nanowires along with nanoparticles, from breakage/discontinuous growth of nanowires. Ni–Fe nanostructures were further analyzed
for temperature-dependent magnetization and magnetization vs. magnetic field measurements using a commercial physical property
measurement system. They reveal no magnetic anisotropy of the nanostructures probably due to a balance between ‘reduced’ shape
anisotropy from branched and rough pore surfaces and magnetocrystalline anisotropy.
PACS 61.46.+w; 75.75.+a; 81.07.-b; 81.16.Be 相似文献
62.
63.
Liu Y Kravtsov V Walsh RD Poddar P Srikanth H Eddaoudi M 《Chemical communications (Cambridge, England)》2004,(24):2806-2807
A novel anionic metal-organic cube (MOC-1), [Ni(8)(HImDC)(12)](8-), has been synthesized by metal-ligand directed assembly of eight tri-connected Ni nodes and twelve doubly deprotonated bis(bidentate) imidazoledicarboxylic acid ligands (HImDC). 相似文献
64.
65.
Golam Mohiuddin Sharmistha Ghosh Nazma Begum Somen Debnath Srikanth Turlapati Doddamane Sreenivasamurthy Shankar Rao 《Liquid crystals》2018,45(10):1549-1566
Here, we report the first examples of achiral unsymmetrical three-ring bent-shaped liquid crystals comprising amide and imine linkages with transverse substituents of methyl and chloro moieties on the central phenyl ring in the core, exhibiting polar banana phases. The extensive intra and inter molecular H-bonding induced novel banana mesomorphic phases. One-dimensional stacking in the mesomorphic phase as well as ferroelectric polar order promoted by intermolecular H-bonding of amide linkage is demonstrated. The compounds exhibit multifunctional properties viz., the enantiotropic liquid crystalline (LC) phase at ambient temperatures, electro-optical response, spontaneous polarisation, emission characteristics with large Stokes shift, and even charge distribution with large voltage holding ratio (VHR) values. The smectic type phase was confirmed by XRD studies and polar order was established by switching current and dielectric investigations. DFT studies revealed the importance of their suitability for display applications. 相似文献
66.
Singularly perturbed elliptic equations with superlinear nonlinearities of polynomial type are considered on an annulus in Rn, n≥4. It is shown that for small parameters there exist solutions which concentrate on manifolds of dimensions one, three and seven, which are given as Hopf-fibres. 相似文献
67.
We show that any general semilinear elliptic problem with Dirichlet or Neumann boundary conditions in an annulus A⊆R2m, m?2, invariant by the action of a certain symmetry group can be reduced to a nonhomogeneous similar problem in an annulus D⊂Rm+1, invariant by another related symmetry. We apply this result to prove the existence of positive and sign changing solutions of a singularly perturbed elliptic problem in A which concentrate on one or two (m−1) dimensional spheres. We also prove that the Morse indices of these solutions tend to infinity as the parameter of concentration tends to infinity. 相似文献
68.
Srikanth S. Kamath 《Journal of Dispersion Science and Technology》2013,34(9):1304-1310
A spray drying technique was applied to prepare composite microparticles of a water-insoluble herbicide, atrazine(AT) and a water-soluble herbicide 2,4-dichloro phenoxy acetic acid (2,4-D) for the purpose of improving the water solubility of AT. A homogenous mixture of an ethanol solution of AT and an aqueous 2,4-D solution at different ratios were spray dried using a laboratory scale spray drier. Quantitative elemental analysis suggested that the AT/2,4-D ratio in each composite microparticle was nearly the same as the desired formulation ratio. The resulting samples were characterized by powder x-ray diffractometry (XRD), differential scanning calorimetry (DSC), Fourier transform infra red (FT-IR) and scanning electron microscopy (SEM). It was found that the crystallinity of AT and 2,4-D were maintained in the composite particles. Moreover, the release of AT from dissolved composite microparticles was markedly improved because of an increase in the effective surface area following rapid dissolution of 2, 4 D. Hence, this study shows that it is possible to prepare AT-2,4-D composite microparticles using a laboratory scale spray drier and that this can improve the ability of AT to dissolve in water. 相似文献
69.
K. V. Nagalakshmi M. Padma P. Shyamala V. Srikanth A. Satyanarayana P. V. SubbaRao 《Transition Metal Chemistry》2013,38(5):523-527
The kinetics of dissociation of bis(2,4,6–tripyridyl-s-triazine) iron(II), ([Fe(TPTZ)2]2+) has been studied in CTAB/chloroform/hexane reverse micellar medium. In the absence of acid, the reaction is immeasurably slow and does not go to completion in conventional aqueous medium but is markedly accelerated and takes place with a rate constant equal to 55.3 × 10?3 s?1 and goes to completion in reverse micelles. The significant increase in rate is attributed to the special properties of the water pool in the reverse micelles like low dielectric constant, nucleophilic effect of Br- ion, and favorable partitioning of TPTZ in the organic phase. The rate of the reaction decreases with increase in W (=[H2O]/[CTAB]) at constant CTAB concentration and remains constant with increase in CTAB at fixed W. The results are compared with other closely related systems. 相似文献
70.
Hongwei Yang Yahui Wang Yanli Cao Chunbao Zheng Lu Liu Likun Liu Keqiang Ding Sowjanya B. Rapole Yiran Wang Zhanhu Guo 《中国化学会会志》2013,60(9):1135-1143
Multi‐walled carbon nanotubes (MWCNTs) decorated with PdxCoy (the nominal atomic ratios of Pd to Co were 3:1, 3:1.5, 3:2, 3:3, respectively) nanoparticles (denoted as PdxCoy/MWCNTs ) were fabricated by a simple pyrolysis process, in which room temperature ionic liquids (RTILs) of butyl‐3‐methylimidazolium hexafluorophosphate (denoted as [BMIM]PF6) was used as the solvent. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) were all used to characterize the PdxCoy/MWCNTs catalysts, showing that the PdxCoy particles were dispersed on the surface of the MWCNTs with an average particle size of ~25.0 nm. The electro‐catalytic activity of the PdxCoy/MWCNTs catalysts toward ethanol oxidation reaction (EOR) was examined by cyclic voltammetry (CV). It was revealed that the onset potential was ~90 mV lower and the peak current was about four times higher for ethanol oxidation for Pd3Co1.5/MWCNTs compared to those of Pd3Co1/MWCNTs. The possible catalysis mechanisms of the Pd3Co1.5/MWCNTs toward EOR were also discussed. 相似文献