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851.
The ozone molecule possesses a unique and distinctive (17)O excess (Δ(17)O), which can be transferred to some of the atmospheric molecules via oxidation. This isotopic signal can be used to trace oxidation reactions in the atmosphere. However, such an approach depends on a robust and quantitative understanding of the oxygen transfer mechanism, which is currently lacking for the gas-phase NO(2) + O(3) reaction, an important step in the nocturnal production of atmospheric nitrate. In the present study, the transfer of Δ(17)O from ozone to nitrate radical (NO(3)) during the gas-phase NO(2) + O(3) → NO(3) + O(2) reaction was investigated in a series of laboratory experiments. The isotopic composition (δ(17)O, δ(18)O) of the bulk ozone and the oxygen gas produced in the reaction was determined via isotope ratio mass spectrometry. The Δ(17)O transfer function for the NO(2) + O(3) reaction was determined to be: Δ(17)O(O(3)?) = (1.23 ± 0.19) × Δ(17)O(O(3))(bulk) + (9.02 ± 0.99). The intramolecular oxygen isotope distribution of ozone was evaluated and results suggest that the excess enrichment resides predominantly on the terminal oxygen atoms of ozone. The results obtained in this study will be useful in the interpretation of high Δ(17)O values measured for atmospheric nitrate, thus leading to a better understanding of the natural cycling of atmospheric reactive nitrogen. 相似文献
852.
We study the dynamics of driven polymer translocation using both molecular dynamics (MD) simulations and a theoretical model based on the non-equilibrium tension propagation on the cis side subchain. We present theoretical and numerical evidence that the non-universal behavior observed in experiments and simulations are due to finite chain length effects that persist well beyond the relevant experimental and simulation regimes. In particular, we consider the influence of the pore-polymer interactions and show that they give a major contribution to the non-universal effects. In addition, we present comparisons between the theory and MD simulations for several quantities, showing extremely good agreement in the relevant parameter regimes. Finally, we discuss the potential limitations of the present theories. 相似文献
853.
Gourhari Maiti Utpal Kayal Rajiv Karmakar Rudraksha N. Bhattacharya 《Tetrahedron letters》2012,53(12):1460-1463
Mercuric triflate catalyzes the reaction between 1,2-diaminobenzene and terminal alkynes to afford 2,4-disubstituted 2-methyl-2,3-dihydro-1H-benzo[b][1,4]diazepine in an excellent yield. The terminal alkynes function as a source of keto-methyl equivalent. 相似文献
854.
Dr. Suman K. Samanta Prof. Dr. Santanu Bhattacharya 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(49):15875-15885
We have synthesized two new low‐molecular‐mass organogelators based on tri‐p‐phenylene vinylene derivatives, one of which could be designated as the donor whereas the other one is an acceptor. These were prepared specifically to show the intergelator interactions at the molecular level by using donor–acceptor self‐assembly to achieve appropriate control over their macroscopic properties. Intermolecular hydrogen‐bonding, π‐stacking, and van der Waals interactions operate for both the individual components and the mixtures, leading to the formation of gels in the chosen organic solvents. Evidence for intergelator interactions was acquired from various spectroscopic, microscopic, thermal, and mechanical investigations. Due to the photochromic nature of these molecules, interesting photophysical properties, such as solvatochromism and J‐type aggregation, were clearly observed. An efficient energy transfer was exhibited by the mixture of donor–acceptor assemblies. An array of four chromophores was built up by inclusion of two known dyes (anthracene and rhodamine 6G) for the energy‐transfer studies. Interestingly, an energy‐transfer cascade was observed in the assembly of four chromophores in a particular order (anthracene‐donor‐acceptor‐rhodamine 6G), and if one of the components was removed from the assembly the energy transfer process was discontinued. This allowed the build up of a light‐harvesting process with a wide range. Excitation at one end produces an emission at the other end of the assembly. 相似文献
855.
In the present work we have made use of polarization phase shifting in digital holographic microscopy (DHM) for three dimensional phase profiling of transmissive and reflecting microscopic samples. The Mach–Zehnder arrangement with proper polarizing elements (polarizer-masked cube beam splitter, quarter wave plate and a linear polarizer) is used for recording the phase-shifted digital holograms. The suggested procedure is simple and accurate and obviates the need of piezo devices for phase shifting. The phase profile of the specimen is reconstructed from the holograms by using standard phase shifting algorithms. 相似文献
856.
Ray AK Bhattacharya S Banerjee M Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(7):1375-1378
o-Chloranil has been shown to form 1:1 molecular complexes with pyridine and 2-, 3- and 4-picolines in CCl4 medium. Isosbestic points have been found but charge-transfer bands could not be detected. The formation constants of the complexes exhibit a very good linear free energy relationship from which the Hammett p parameter for the complexation reaction is found to be -3.67. 相似文献
857.
The fundamental physics of the resonant tunnelling lifetime (RTL) in superlattices have been theoretically studied. The modelling of this RTL is based on a relationship between the resonant tunnelling and the half-width at half-maximum of the transmission peak. The lifetime of resonant states and the current density accompany the resonant tunnelling change as a function of mole fraction of the barrier layer, well width and barrier width. The energies and the lifetime of the electrons at the resonant states are correlated with the band structure of the superlattices. It is seen that the variation in RTL with resonance energy has a special minima, and that these minima occur around the centre of the allowed bands. 相似文献
858.
B. Bhattacharya 《哲学杂志》2013,93(17):2227-2247
859.
Sputtering yields of monocrystalline silver under irradiation with 7-30 keV Ar+, Kr+ and Xe+ ions, not reported earlier, have been determined. The yield has been found to depend strongly on the orientation of the crystal and mass of the impinging ion. Onderdelinden's model based on Lindhard's theory of Channeling is found to describe satisfactorily, the observed orientation and ion-mass dependence of the yields for the ions of energy ~10 keV or above. The role of the barrier potential approximated in the model in predicting the experimental results is discussed. 相似文献
860.
Yuan Luo Vijay Raj Singh Dipanjan Bhattacharya Elijah Y. S. Yew Jui‐Chang Tsai Sung‐Liang Yu Hsi‐Hsun Chen Jau‐Min Wong Paul Matsudaira Peter T. C. So George Barbastathis 《Laser \u0026amp; Photonics Reviews》2014,8(5):L71-L75
Optical sectioning techniques offer the ability to acquire three‐dimensional information from various organ tissues by discriminating between the desired in‐focus and out‐of‐focus (background) signals. Alternative techniques to confocal, such as active structured illumination, exist for fast optically sectioned images, but they require individual axial planes to be imaged consecutively. In this article, an imaging technique (THIN), by utilizing active Talbot illumination in 3D and multiplexed holographic Bragg filters for depth discrimination, is demonstrated for imaging in vivo 3D biopsy without mechanical or optical axial scanning. 相似文献