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71.
Mari Annadhasan Durga Prasad Karothu Ragaverthini Chinnasamy Luca Catalano Ejaz Ahmed Soumyajit Ghosh Pan
e Naumov Rajadurai Chandrasekar 《Angewandte Chemie (International ed. in English)》2020,59(33):13821-13830
Flexible organic single crystals are evolving as new materials for optical waveguides that can be used for transfer of information in organic optoelectronic microcircuits. Integration in microelectronics of such crystalline waveguides requires downsizing and precise spatial control over their shape and size at the microscale, however that currently is not possible due to difficulties with manipulation of these small, brittle objects that are prone to cracking and disintegration. Here we demonstrate that atomic force microscopy (AFM) can be used to reshape, resize and relocate single‐crystal microwaveguides in order to attain spatial control over their light output. Using an AFM cantilever tip, mechanically compliant acicular microcrystals of three N‐benzylideneanilines were bent to an arbitrary angle, sliced out from a bundle into individual crystals, cut into shorter crystals of arbitrary length, and moved across and above a solid surface. When excited by using laser light, such bent microcrystals act as active optical microwaveguides that transduce their fluorescence, with the total intensity of transduced light being dependent on the optical path length. This micromanipulation of the crystal waveguides using AFM is non‐invasive, and after bending their emissive spectral output remains unaltered. The approach reported here effectively overcomes the difficulties that are commonly encountered with reshaping and positioning of small delicate objects (the “thick fingers” problem), and can be applied to mechanically reconfigure organic optical waveguides in order to attain spatial control over their output in two and three dimensions in optical microcircuits. 相似文献
72.
Kolli Murali Krishna Palani Elamathi Govindasamy Chandrasekar Katta Vishweshwar Rao 《Research on Chemical Intermediates》2020,46(2):1047-1064
Research on Chemical Intermediates - Nanoporous AlSBA-15 catalysts with different nSi/nAl ratios (41, 129, and 210) were synthesized using a hydrothermal method. These catalysts were characterized... 相似文献
73.
The influence of 3-methyl-2,6-diphenyl piperidin-4-one (MDPO) and 2-phenyl decahydroquinoline-4-one (PDQO) synthesised in
the laboratory on hydrogen permeation and corrosion inhibition of mild steel in 1N H2SO4 has been studied using weight loss and various electrochemical AC and DC corrosion-monitoring techniques. Both the compounds
inhibit the corrosion of mild steel in H2SO4. Potentiodynamic polarisation studies clearly reveal that they behave predominantly as cathodic inhibitors. The extent of
decrease in hydrogen permeation current through steel surfaces has been studied by the hydrogen electropermeation technique.
Double layer capacitance (C
dl
) and charge transfer resistance (R
t
) values are derived from Nyquist plots obtained from AC impedance studies. The adsorption of these compounds on mild steel
surfaces from H2SO4 obeys Temkin’s adsorption isotherm. 相似文献
74.
K. Chandrasekar Geetha Baskar 《Journal of polymer science. Part A, Polymer chemistry》2008,46(10):3257-3271
Two sets of terpolymers, polymer A and polymer B consisting of almost same level of 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) component at 0.635 ± 0.005 m and varying dodecyl methacrylate (DoDMAc) and monomethoxy poly(ethylene glycol) acrylate (PEGAc) components have been designed. Polymer A, consisting of less C12 component, has been shown to promote intermolecular aggregated structures wherein C12 domains exhibit compact packing characteristics. It is demonstrated that in polymer B, AMPS segments are predominantly present as ionic clusters contributing to a high pKa at about 9.50 for a low α of 0.20. From the results of interfacial adsorption estimations at air/solution and water/hexane interface, it is shown that open coil structures provided under high pH (>9.0) conditions promote efficiency of adsorption. This is shown from higher surface excess concentration (Γ) and lower interfacial area (a) estimated using Gibbs adsorption isotherm equation. For example, at water/hexane interface, polymer A exhibits Γ of 1.20 × 10?3 moles/1000 m2 at pH 3.2 and 1.97 × 10?3 moles/1000 m2 at pH 10.0. Significantly, in case of polymer B consisting of ionic clusters of AMPS, adsorption at the liquid/liquid interface is more efficient in comparison to polymer A at all pH. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 3257–3271, 2008 相似文献
75.
Govindasamy Chandrasekar Karine MouginHamidou Haidara Loïc VidalEnrico Gnecco 《Applied Surface Science》2011,257(9):4175-4179
The anisotropic shape transformation of gold nanorods (GNRs) with H2O2 was observed in the presence of “cethyl trimethylammonium bromide” (CTAB). The adequate oxidative dissolution of GNR is provided by the following autocatalytic scheme with H2O2: Au0 → Au+, Au0 + Aun+ → 2Au3+, n = 1 and 3. The shape transformation of the GNRs was investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). As-synthesised GNRs exhibit transverse plasmon band (TPB) at 523 nm and longitudinal plasmon band (LPB) at 731 nm. Upon H2O2 oxidation, the LPB showed a systematic hypsochromic (blue) shift, while TPB stays at ca. 523 nm. In addition, a new emerging peak observed at ca. 390 nm due to Au(III)-CTAB complex formation during the oxidation. TEM analysis of as-synthesised GNRs with H2O2 confirmed the shape transformation to spherical particles with 10 nm size in 2 h, whereas centrifuged nanorod solution showed no changes in the aspect ratio under the same condition. Au3+ ions produced from oxidation, complex with excess free CTAB and approach the nanorods preferentially at the end, leading to spatially directed oxidation. This work provides some information to the crystal stability and the growth mechanism of GNRs, as both growth and shortening reactions occur preferentially at the edge of single-crystalline GNRs, all directed by Br− ions. 相似文献
76.
Abstract Heat transfer characteristics of water-based nanocrystalline alumina (Al2O3) nanofluids flowing through a uniformly heated tube under a fully developed laminar and turbulent flow regime is investigated experimentally in the present work to explore the heat transfer mechanism in nanofluids. In a laminar flow, the increase in Nusselt number was attributed to the thermophysical properties of the nanofluid. The movement of nanoparticles, along with the turbulent eddies in the turbulent core region and diffusion mechanism, such as thermophoresis, in the laminar sublayer are believed to be the reasons for enhanced heat transfer in turbulent region. The compatibility of Al2O3/water nanofluids was also examined by monitoring its color. 相似文献
77.
Structure (I) assigned to tylophorine has been confirmed by a total synthesis. 相似文献
78.
Chandrasekar R Calabraro R Myer LJ Phillippo T King JW Eller FJ 《Journal of AOAC International》2001,84(2):466-471
Meat samples are prepared by passing meat through a food chopper, bowl cutter, or food processor, subsampling the meat, and mixing the meat with granular diatomaceous earth. No drying step is necessary. Supercritical CO2 is then used to extract crude fat (which is defined as the components of meat that are extractable with petroleum ether, without digestion of the sample). Extracted material is deposited on glass wool contained in collection vials. After removal of any residual moisture from the extracts, percent crude fat is determined by weight gain of the collection vial. This method has been peer-verified by 3 laboratories, for a wide variety of raw and processed meat products containing 6-28% crude fat. Samples were prepared at the submitting laboratory. Ground samples were split into 4 portions, packed in Whirlpack bags, and immediately frozen. Frozen samples were sent by overnight room temperature, and percent fat was determined (in triplicate), without further processing of the samples. Analysis of the samples was completed within 1 week of sample prepara. tion. On the basis of this study, it can be estimated that all repeatability and reproducibility values are <3.0. Mean accuracy of the direct gravimetric supercritical fluid extraction method for meat samples ranged from +0.22 to -1.41 when the method was compared with AOAC Method 960.39. Interferences are unlikely but would include any nonfat substance that is added to (processed) meat, is soluble in nonpolar solvents, and is present in a quantity that would alter results. This method is expected to perform equally well for all meats with fat content within the stated range of applicability. 相似文献
79.
D. Mohan Ganga Radhakrishnan S. Rajadurai 《Journal of polymer science. Part A, Polymer chemistry》1983,21(11):3041-3053
Poly(vinyl acetate) was graft-copolymerized onto casein in the presence of potassium peroxydisulfate-ascorbic acid. The effect of synthetic variables on the rates of conversion of monomer (Rp), graft copolymerization (Rg), and homopolymerization (Rh), percent grafting, and grafting efficiency were investigated and the results, compared with the system initiated by peroxydisulfate alone. 相似文献
80.