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121.
Jeffrey S. Fu Md. Nurunnabi Mollah Nemai C. Karmakar 《International Journal of Infrared and Millimeter Waves》2006,27(4):571-589
A microstrip transmission line on a Chebyshev distributed chirped I-D photonic bandgap structure (PBGS) is proposed. Two different approaches are utilized to realize Chirped
PBGS. Firstly, the inter-element distance of PBG elements is chirped with conventional chirping technique. Secondly, using
Chebyshev distribution varies the inter-element distance. For both the cases, the amplitude is made non-uniform by varying the amplitudes
in accordance with the co-efficient of Chebyshev distribution. It can be seen that the conventionally chirped PBGS having Chebyshev distribution in amplitude improves the over all performance. The inclusion of Chebyshev distribution in period calculation further improves the performance. It can be seen that the Chirped and non-uniform PBGS
generates excellent bandgap performances in lower valued height of substrate that are superior to the performances available
in the open literature. 相似文献
122.
Lifetime of eight levels belonging to the 4p45d configuration of singly ionized krypton have been measured by high-frequency deflection technique with a delayed coincidence single photon counting arrangement. The results have been compared with other experimental and theoretical values. The lifetimes of the 5d4P1/2, 5d′2D3/2, 5d′2F5/2, 5d2P3/2 and 5d2P1/2 levels have been measured for the first time. 相似文献
123.
124.
Sujay Mukhopadhyay Arnab BiswasRampal Pandey Rakesh Kumar GuptaDaya Shankar Pandey 《Tetrahedron letters》2014
A selective fluorescence ‘turn-on’ chemodosimeter N,N′-bis-(4-cyanobenzylidene)-2,4,6-trimethylbenzene-1,3-diamine (3) based on a Schiff base for femto-molar detection of the Hg2+ has been described. It presents the highest level of detection limit for Hg2+ through Schiff base hydrolysis. 相似文献
125.
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127.
To understand the role of electron correlation and disorder on persistent currents in isolated 1D rings threaded by magnetic flux ?, we study the behavior of persistent currents in aperiodic and ordered binary alloy rings. These systems may be regarded as disordered systems with well-defined long-range order so that we do not have to perform any configuration averaging of the physical quantities. We see that in the absence of interaction, disorder suppresses persistent currents by orders of magnitude and also removes its discontinuity as a function of ?. As we introduce electron correlation, we get enhancement of the currents in certain disordered rings. Quite interestingly we observe that in some cases, electron correlation produces kink-like structures in the persistent current as a function of ?. This may be considered as anomalous Aharonov-Bohm oscillations of the persistent current and recent experimental observations support such oscillations. We find that the persistent current converges with the size of the rings. 相似文献
128.
The photophysical behavior of a 1:1 complex between phenol and 7-azaindole (7AI) has been investigated in methylcyclohexane solutions at temperatures in the range of 27 to -50 °C. A linear Benesi-Hildebrand plot associated with changes in absorbance of the complex with phenol concentration in the solutions ensures 1:1 stoichiometry of the produced complex. Our estimate for the value of the association constant (K(a)) of the complex is ~120 M?1 at 27 °C, and it is nearly twice compared to that for 1:1 complex between 7AI and ethanol measured under the same condition. The complexation results in dramatic quenching of the normal fluorescence of 7AI and the process is accelerated upon lowering of temperature. The measured spectra show no indication that phenol promotes tautomerization of 7AI in the excited state. We have argued that the hydrogen bonding between pyridinic N and phenolic O-H (N···O-H) is a vital structural factor responsible for quenching of 7AI fluorescence, and this idea has been corroborated by showing that under same condition the fluorescence of 7AI is enhanced in the presence of anisole. As a plausible mechanism of quenching, we have invoked a proton-coupled electron transfer (PCET) process between phenol and excited 7AI, which outweighs the competing tautomerization process. An analysis in terms of Remm-Weller model reveals that the PCET process involving phenol and excited 7AI could be energetically favorable (ΔG(ET)(0) < 0). An alternative mechanism, where quenching can occur via electronic energy transfer from the excited protonated 7AI to phenoxide ion, following a proton transfer along the N···O-H hydrogen bond, is also discussed. 相似文献
129.
vic-Dibromo-, α-halo-, or α,α-dibromocarbonyl compounds can be efficiently dehalogenated using catalytic tris(2,2'-bipyridyl)ruthenium dichloride (Ru(bpy)(3)Cl(2)) in combination with 1,5-dimethoxynaphthalene (DMN) and ascorbate as sacrificial electron donor. For this process, a visible light promoted photocatalytic cycle is proposed that involves the reduction of carbon halogen bonds via free radical intermediates. 相似文献
130.
Santanu MandalTapan Kumar Karmakar Anupam GhoshMichel Fleck Debasis Bandyopadhyay 《Polyhedron》2011,30(5):790-795
Five mononuclear complexes of manganese(II) of a group of the general formula, [MnL(NCS)2] where the Schiff base L = N,N′-bis[(pyridin-2-yl)ethylidene]ethane-1,2-diamine (L1), (1); N,N′-bis[(pyridin-2-yl)benzylidene]ethane-1,2-diamine (L2), (2); N,N′-bis[(pyridin-2-yl)methylidene]propane-1,2-diamine (L3), (3); N,N′-bis[(pyridin-2-yl)ethylidene]propane-1,2-diamine (L4), (4) and N,N′-bis[(pyridin-2-yl)benzylidene]propane-1,2-diamine (L5), (5) have been prepared. The syntheses have been achieved by reacting manganese chloride with the corresponding tetradentate Schiff bases in presence of thiocyanate in the molar ratio of 1:1:2. The complexes have been characterized by IR spectroscopy, elemental analysis and other physicochemical studies, including crystal structure determination of 1, 2 and 4. Structural studies reveal that the complexes 1, 2 and 4 adopt highly distorted octahedral geometry. The antibacterial activity of all the complexes and their respective Schiff bases has been tested against Gram(+) and Gram(−) bacteria. 相似文献