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Tarek M. Trad Kyle B. Donley David C. Look Kurt G. Eyink David H. Tomich Curtis R. Taylor 《Journal of Crystal Growth》2010,312(24):3675-3679
ZnO nanoparticles as small as 80 nm were successfully synthesized using a modified vapor phase transport (VPT) process at substrate temperatures as low as 222 °C. Particle size distribution and morphology were characterized by scanning electron microscopy and atomic force microscopy. Energy dispersive X-ray spectroscopy and X-ray diffraction indicate the synthesis of high quality crystalline ZnO structures. Low temperature (4.2 K) photoluminescence (PL) spectroscopy was used to characterize the optical quality of the nanoparticles. Ultraviolet emission and a nanostructure specific feature at 3.366 eV are strong in the PL spectra. The 3.366 eV feature is observed to predominate the spectrum with decrease in particle size. This size effect corroborates the luminescence as a nanostructure-specific surface related exciton feature as previously speculated in the literature. In addition, self-assembled ZnO mesoparticles (>100 nm) were realized by increasing the growth time. Low growth temperatures of the particles allow for their potential utilization in flexible organic hybrid optoelectronics. However, this work focuses mainly on the modified synthesis and optical characterization of nanoparticles. 相似文献
95.
Tarek Hamdi 《Complex Analysis and Operator Theory》2018,12(7):1697-1705
The present paper provides a proof of \(i^*(\mathbb {C}P+\mathbb {C}(I-P); \mathbb {C}Q+\mathbb {C}(I-Q))=-\chi _{{ orb}}(P,Q)\) for two projections P, Q without any extra assumptions. An analytic approach is adopted to the proof, based on a subordination result for the liberation process of symmetries associated with P, Q. 相似文献
96.
Tarek Sayed Ahmed 《Algebra Universalis》2010,63(1):17-36
This is a survey article on the concept of neat reducts. An old venerable idea in algebraic logic, in this paper we show why it is regaining momentum. 相似文献
97.
As a first approximation, asset and liability management issues faced by life insurance companies originate from the sale of with-profits contracts. These contracts are bond-type products with several rate guarantees and other interestsensitive embedded options. Benefits paid out to policyholders mostly depend on the investment performance of a given asset portfolio in which premiums are invested. Thus, guarantees and options granted to policyholders may become effective when the investment performance of the asset portfolio is poor. Issuing a with-profits contract is therefore not equivalent to issuing plain-vanilla debt. The purpose of this paper is to value with-profits liabilities in a consistent option-pricing framework and to develop efficient asset or liability strategies to manage profitability and variability of shareholder value. 相似文献
98.
Mark E T Horn Tarek Elgindy Antonio Gomez-Iglesias 《The Journal of the Operational Research Society》2016,67(4):664-675
This paper presents a mixed integer linear programming (MILP) model to aid in planning a large, hierarchically structured workforce. The workforce (eg, all Army commissioned officers) is classified by occupational group and rank and modelled in yearly intervals. Personnel and their movements are modelled as stocks and flows, subject to constraints representing employment conditions and resource limitations. The task is to estimate personnel numbers and flows so as to minimize a composite cost function. The model’s detailed fidelity to actual conditions, and hence its value in practice, clearly exceed previous efforts in the workforce planning domain. To overcome computational challenges that arose when an MILP solver was applied directly, the authors developed an iterative solution approach, which has yielded an attractive combination of solution quality and computational performance. 相似文献
99.
Tarek M. Abu Elmaati 《Journal of heterocyclic chemistry》2004,41(6):947-950
Treating 5‐(4‐phenylcarboxamido)‐3‐cyano‐4‐methylpyridin‐2(1H)thione ( 3 ) with elemental sulfur yielded thienopyridine 4 . Compound 4 reacts with acrylonitrile to give isoquinoline 7 . Compound 7 was also, prepared from 3 and methylenemalononitrile. Reaction of 3 with dimethylacetylene dicarboxylate (DMAD) gave the pyridothiazole 9 . Also, 3 reacted with N,N‐dimethylchloroacetamide ( 10 ) to afford compound 11 which further reacted with the reagents 12 , 13 and 14 providing the thieno[2,3‐b]pyridine derivatives 15 , 16 and 17 respectively. 相似文献
100.
Shafeek A.R. Mulla Tarek A. Salama Mohsinkhan Y. Pathan Suleman M. Inamdar Santosh S. Chavan 《Tetrahedron letters》2013,54(7):672-675
A solvent-free, environmentally clean, mild, and simple one-pot multi-component protocol has been developed for the efficient synthesis of 1-amido- and 1-carbamato-alkyl naphthols/phenols in excellent yields via one-pot three-component condensation of various aldehydes, amides/carbamates/urea, and naphthols/phenols using ethylammonium nitrate (EAN) as a reusable ionic liquid catalyst under neat reaction condition at ambient temperature. 相似文献