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61.
62.
In this paper, we present a theoretical study of the nonlinear optical response of the newly discovered conjugated polymer poly(diphenyl)polyacetylene (PDPA). In particular, we compute the third-order nonlinear susceptibility corresponding to two-photon absorption process in PDPA using: (a) independent-particle Hückel model, and (b) using the correlated-electron Pariser-Parr-Pople (P-P-P) model coupled with various configuration-interaction methodologies such as the singles-configuration-interaction (SCI), the multi-reference-singles-doubles CI (MRSDCI), and the quadruples-CI (QCI) method. At all levels of theory, the polymer is found to exhibit highly anisotropic nonlinear optical response, distributed over two distinct energy scales. The low-energy response is predominantly polarized in the conjugation direction, and can be explained in terms of chain-based orbitals. The high-energy response of the polymer is found to be polarized perpendicular to the conjugation direction, and can be explained in terms of orbitals based on the side phenylene rings. Moreover, the intensity of the nonlinear optical response is also enhanced as compared to the corresponding polyenes, and can be understood in terms of reduced optical gap. 相似文献
63.
Alok Rout Satyabrata Mishra K. A. Venkatesan M. P. Antony N. K. Pandey 《Journal of solution chemistry》2018,47(2):373-386
Tri-n-butylphosphate (TBP) in an ionic liquid (IL) has been proposed as a suitable alternative for the solvent extraction of actinides from nitric acid solutions. This paper reports the detailed investigations on the physicochemical and hydrodynamic properties of the solvent system containing TBP in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) IL. The properties such as density, viscosity, phase separation time (PST), etc., were measured for irradiated and unirradiated solvent phases composed of TBP, [C4mim][NTf2] and 1.1 mol·L–1 TBP in [C4mim][NTf2]. The results are compared with the values obtained in acid-equilibrated IL phases. ATR–FTIR spectroscopy and dynamic light scattering measurement of the IL phase were employed to characterize the interactions among the IL, TBP and nitric acid medium, and the aggregate size of the adduct formed in the IL phase. 相似文献
64.
Feng Jun Chernova Natasha A. Omenya Fredrick Tong Lingyue Rastogi Alok C. Stanley Whittingham M. 《Journal of Solid State Electrochemistry》2018,22(4):1063-1078
Journal of Solid State Electrochemistry - Hybrid supercapacitors using asymmetric, LiFePO4 (LFP) lithium intercalation and electric double layer activated carbon (AC) electrodes combining the high... 相似文献
65.
Control of Luminescence by Tuning of Crystal Symmetry and Local Structure in Mn4+‐Activated Narrow Band Fluoride Phosphors
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Mu‐Huai Fang Wei‐Lun Wu Prof. Dr. Ye Jin Tadeusz Lesniewski Dr. Sebastian Mahlik Prof. Dr. Marek Grinberg Prof. Dr. Mikhail G. Brik Dr. Alok M. Srivastava Dr. Chang‐Yang Chiang Prof. Dr. Wuzong Zhou Dr. Donghyuk Jeong Prof. Dr. Sun Hee Kim Dr. Grzegorz Leniec Prof. Dr. Slawomir M. Kaczmarek Dr. Hwo‐Shuenn Sheu Prof. Dr. Ru‐Shi Liu 《Angewandte Chemie (International ed. in English)》2018,57(7):1797-1801
Mn4+‐doped fluoride phosphors have been widely used in wide‐gamut backlighting devices because of their extremely narrow emission band. Solid solutions of Na2(SixGe1?x)F6:Mn4+ and Na2(GeyTi1?y)F6:Mn4+ were successfully synthesized to elucidate the behavior of the zero‐phonon line (ZPL) in different structures. The ratio between ZPL and the highest emission intensity υ6 phonon sideband exhibits a strong relationship with luminescent decay rate. First‐principles calculations are conducted to model the variation in the structural and electronic properties of the prepared solid solutions as a function of the composition. To compensate for the limitations of the Rietveld refinement, electron paramagnetic resonance and high‐resolution steady‐state emission spectra are used to confirm the diverse local environment for Mn4+ in the structure. Finally, the spectral luminous efficacy of radiation (LER) is used to reveal the important role of ZPL in practical applications. 相似文献
66.
Azithromycin is a broad spectrum antimicrobial agent that is approved in the United States for use in humans. Due to azithromycin's low rate of metabolism it is likely to be found in wastewater treatment plants, where its broad spectrum of antimicrobial activity could lead to development of resistance in bacteria. A liquid-liquid extraction using K2CO3 and methyl-t-butyl ether (MTBE) was used to extract azithromycin from 10 ml aliquots of wastewater. Liquid chromatography was performed using a Luna C18(2) (30 mm x 2.0 mm) column with a mass spectrometer friendly mobile phase containing 50:24:2:24 acetonitrile, methanol, tetrahydrofuran, and 0.04 M ammonium hydroxide. The mass spectrometer used an electrospray source with positive ionization and an ion trap detector. A linear standard curve from 5 to 200pg/ml was validated and used to quantitate azithromycin in wastewater. 相似文献
67.
Rajatendu Sengupta V. K. Tikku Alok K. Somani Tapan K. Chaki Anil K. Bhowmick 《Radiation Physics and Chemistry》2005,72(6):751-757
Electron beam irradiation of poly(iminohexamethylene-iminoadipoyl) (Polyamide-6,6) films was carried out over a range of irradiation doses (20–500 kGy) in air. The mechanical properties were studied and the optimum radiation dose was 200 kGy, where the ultimate tensile stress (UTS), 10% modulus, elongation at break (EB) and toughness showed significant improvement over the unirradiated film. At a dose of 200 kGy, the UTS was improved by 19%, the 10% modulus by 9% and the EB by 200% over the control. The dynamic mechanical properties of the films were studied in the temperature region 303–473 K to observe the changes in the glass transition temperature (Tg) and loss tangent (tan δ) with radiation dose. The storage modulus of the film receiving a radiation dose of 200 kGy was higher than the unirradiated film. The water uptake characteristics of the Polyamide-6,6 films were investigated. The water uptake was less for the films that received a radiation dose of 200 and 500 kGy than the unirradiated film. The role of crystallinity, crosslinking and chain scission in affecting the tensile, dynamic mechanical and water absorption properties was discussed. 相似文献
68.
Alok Aggarwal Leonidas J. Guibas James Saxe Peter W. Shor 《Discrete and Computational Geometry》1989,4(1):591-604
We present an algorithm for computing certain kinds of three-dimensional convex hulls in linear time. Using this algorithm, we show that the Voronoi diagram ofn sites in the plane can be computed in (n) time when these sites form the vertices of a convex polygon in, say, counterclockwise order. This settles an open problem in computational geometry. Our techniques can also be used to obtain linear-time algorithms for computing the furthest-site Voronoi diagram and the medial axis of a convex polygon and for deleting a site from a general planar Voronoi diagram.This research began while the first and fourth authors were visiting the Mathematical Sciences Research Institute in Berkeley, California. Work by the fourth author was supported in part by NSF Grant No. 8120790. 相似文献
69.
70.
Alok Kumar Maloo 《代数通讯》2013,41(12):6123-6126
It is shown that if A is a ring and A is a regular local k-algebra such that Derk(A) is finitely generated, then it is free under some conditions. 相似文献