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21.
Investigation of the role of NaBH<Subscript>4</Subscript> in the chemical synthesis of gold nanorods
Akshaya K. Samal Theruvakkattil S. Sreeprasad Thalappil Pradeep 《Journal of nanoparticle research》2010,12(5):1777-1786
An improvement in the previously reported seed-mediated chemical synthesis of gold nanorods (GNRs) is reported. Monodisperse
GNRs have been synthesized in a one-step protocol. The addition of controlled quantity of sodium borohydride (NaBH4) directly into the growth solution produced uniform GNRs, formed by in situ nucleation and growth. In order to arrive at
the conclusion, we studied the formation of GNRs with various seeds, of metals of widely differing crystal structures, and
there were no variations in the properties of the GNRs formed. The role of NaBH4 in the growth of GNR, which has not been covered in previous reports, is discussed in detail. The dependence of longitudinal
plasmon peak on the concentration of NaBH4 is compared with the dependence of residual concentration of NaBH4 in the seed solution, which is added to the growth solution in seed-mediated synthesis. The study shows that NaBH4 plays an important role in the formation of GNRs. This proposed protocol offers a number of advantages: one-step preparation
of GNRs, significant reduction in the preparation time to 10 min, high monodispersity of GNRs, and tailorability of the aspect
ratio depending on NaBH4 concentration. It is suggested that NaBH4 added to the growth solution leads to in situ formation of the seed particles of the size of 3–5 nm which enables the growth
of GNRs. The growth of GNRs suggested here is likely to have an impact on the preparation of other anisotropic structures.
Our single-pot methodology makes the procedure directly adaptable for commercial-scale production of GNRs and for their synthesis
even in undergraduate laboratories. 相似文献
22.
We study the dynamics of the structure of a formal neural network wherein the strengths of the synapses are governed by spike-timing-dependent plasticity (STDP). For properly chosen input signals, there exists a steady state with a residual network. We compare the motif profile of such a network with that of a real neural network of C. elegans and identify robust qualitative similarities. In particular, our extensive numerical simulations show that this STDP-driven resulting network is robust under variations of the model parameters. 相似文献
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Sreeprasad TS Samal AK Pradeep T 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):4589-4599
A method is described for assembling gold nanorods into one-, two-, and three-dimensional superstructures. The addition of dimercaptosuccinic acid (DMSA) into the nanorod solution was found to induce self-assembly of the latter to one-dimensional "tapelike", two-dimensional "sheetlike" and three-dimensional "superlattice-like" structures depending on the DMSA concentration. The assembly was found to follow a smectic structure, where the nanorod long axes are parallel to each other. The rods are spaced 8.5 +/- 0.3 nm apart in the resulting structures, which extend over several micrometers in length. Organizations perpendicular to the grid were also found. The nanorod tapes were found to bend, and they form circular assemblies as well. The assembly and morphology of the nanorod structures were characterized by transmission electron microscopy and UV-vis spectroscopy. The effect of the DMSA concentration as well as the pH of the medium was also studied. On the basis of several control experiments utilizing similar molecules, charge neutralization of the nanorods by the carboxylic group of DMSA was found to be the principal reason for such an assembly, while the mercapto groups render additional stability to its structure. A mechanistic model of the assembly is proposed. This type of assembly would plausibly function as a plasmonic waveguide in potential nanodevices. 相似文献
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26.
Rupasree R. Das Shashadhar Samal Seok‐Ju Choi Kurt E. Geckeler 《Macromolecular rapid communications》2001,22(11):850-854
The synthesis of a novel highly swelling, macroporous hydrogel from poly(allylamine) using 3‐chloropentan‐2,4‐dione as a crosslinker is reported. The swelling of the hydrogel was sensitive to changes in pH, temperature, and the extent of crosslinking. The dry gel exhibited a regular honeycomb network with smooth macropores. The hydrogel was inherently luminescent, and so was a metal polychelate. 相似文献
27.
Vishnu Shanker Saroj L. Samal Gopal K. Pradhan Chandrabhas Narayana Ashok K. Ganguli 《Solid State Sciences》2009,11(2):562-569
Nanocrystalline NaNbO3 and NaTaO3 have been synthesized by the reverse micellar technique for the first time. The particle size of NaNbO3 was found to be 18 nm while that of NaTaO3 was found to be 40 nm (much smaller size than most of the earlier reports on NaTaO3). Rietveld refinement of X-ray diffraction data and Raman spectroscopy confirm that the nanoparticles of NaNbO3 and NaTaO3 have orthorhombically distorted structures with Pmc21 and Pbnm space groups, respectively. The dielectric constant at 25 °C of NaNbO3 and NaTaO3 was found to be 209 and 147 at 1 kHz, respectively. The antiferroelectric transition in NaNbO3 shifts to lower temperature (325 °C) in the nanocrystalline solid. 相似文献
28.
Bibhuti B. Samal Sagarika Sahu Braja B. Chinara S. Nanda P. K. Otta L. M. Mohapatro Trijama R. Mohanty A. R. Ray K. C. Singh 《Journal of polymer science. Part A, Polymer chemistry》1988,26(12):3159-3166
Graft copolymerization of acrylonitrile (AN) onto sisal fibers (chemically modified) was studied using the Mn(III)/EDTA redox system in aqueous solution. The effects of time, monomer (AN), metal ion [Mn(III)] substrate [ethylene diamine tetraacetic acid (EDTA)], temperature, and acid concentration on graft yield have been studied. The effects of thiourea on the graft yield has also been studied. A suitable mechanism is proposed. 相似文献
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Shahram Mehdipour-Ataei Samal Babanzadeh Ebrahim Abouzari-Lotf Samaneh Khodami 《Soft Materials》2018,16(4):265-274
A new diamine was prepared via reaction between 8-hydroxy-5-nitroquinoline and 4-nitrobenzoyl chloride, followed by reduction of the nitro groups of the resulted compound. Novel quinoline-based poly(ester-amide)s were produced through polycondensation reactions of the prepared diamine with different diacid chlorides. The monomer and poly(ester-amide)s were characterized and properties of the polymers including solution viscosity, thermal behavior and stability, solubility, and crystallinity were studied.High thermal stability and improved solubility was observed for the polymers, indicating successful designing of monomer and related polymers for overcoming the main issue of thermally stable polymers, i.e. the problem of increasing solubility versus high thermal stability.Also, by changing the diacid chlorides for the preparation of poly(ester-amide)s, the structure-property relations were investigated. 相似文献