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131.
132.
Free-radical-induced DNA damage by ionizing radiation leads to a number of oxidized purines, of which 7H-8-oxoguanine (8OG) and 7H-8-oxoadenine (8OA) are predominant and known to cause an appreciable amount of cellular damage. A detailed quantum mechanical study at various levels of theory in both the gas phase and in an aqueous solution has been carried out in order to assess the tautomeric preferences of the bases. The calculated energies of various plausible tautomers suggest that at higher levels of ab initio theory with inclusion of electron correlation, the 8-keto-6-enolic form of 8-oxoguanine (8OG2) would predominate over the 6,8-diketo form (8OG1) in the gas phase whereas the 6-amino-8-keto form (8OA1) predominates over the other possible tautomers of 8-oxoadenine. Aqueous solvation, however, changes the gas-phase order for 8-oxoguanine, 8OG1 turning out to be the major tautomeric species in an aqueous medium. The estimated free energies of hydration by polarized continuum models are indicative that the mutagenically significant amounts of minor tautomeric forms of 8-oxoguanine and 8-oxoadenine exist in the aqueous phase and might be held responsible for inducing transversional as well as transitional mutations. 相似文献
133.
Y Ramakrishna K Ramachandra Rao G J Naga Raju K Bhaskara Rao V Seshagiri Rao P Venkateswarlu S Bhuloka Reddy 《Pramana》2002,59(4):685-691
The energy shifts and intensity ratios of different L X-ray components in tantalum element due to 10 MeV carbon and 12 MeV
nitrogen ions are estimated. From the observed energy shifts, the possible number of simultaneous vacancies in M shell are
estimated. A comparison of L
α
/L
β2.15, L
β1/L
γ1 and L
γ2.3/L
γ4.4 with the ratios due to Scofield theoretical transition rates indicate that the number of multiple vacancies in N shell are
higher than the vacancies in M and O shell. Employing Larkin’s statistical scaling procedure, the number of possible multiple
vacancies in N and O shells are estimated quantitatively. 相似文献
134.
135.
M. Dattatreya Sastry Putcha Venkateswarlu F.A.Sc. 《Proceedings Mathematical Sciences》1967,66(4):208-221
Electron Paramagnetic Resonance studies of Cu2+ doped in NH4Br single crystals have been carried out for the first time. The room temperature data reveal that Cu2+ ions go predominantly to interstitial sites having square planar co-ordination of four Br? ions. For this type of complexes the bromine: superhyperfine structure: is observed on the normal hyperfine structure lines of copper. Existence of other weak spectra indicates that a relatively few Cu++ ions go substitutionally to (NH4)+ ions, and are probably associated with a first or a second nearest neighbour cation vacancy, among the two, the latter being more predominant. However, the low temperature studies corresponding to the tetragonal phase of NH4Br indicate that a number of Cu2+ ions at interstitial sites get readjusted to the lattice sites after phase transformation. The spectra in both the phases are analysed by the usual spin Hamiltonian method. 相似文献
136.
The theory of mean-square amplitude matrices is applied to the bent XYZ molecules. The principal mean amplitudes of vibration for the molecules investigated here are reported for 300° K. 相似文献
137.
By the condensation of embelin (I) with various nitroso compounds, the corresponding N-bis-anhydrobenzoquinones (II) have been synthesized and their properties recorded. 相似文献
138.
Biswanath Das Maddeboina Krishnaiah Katta Venkateswarlu Vtukuri Saidi Reddy 《Helvetica chimica acta》2007,90(1):110-113
Oxiranes and aziridines efficiently undergo ring opening with bismuth nitrate at room temperature to furnish the corresponding β‐(nitrooxy)‐substituted alcohols and amines respectively. The conversions are highly regio‐ and stereoselective and afford the nitrooxy‐compounds in excellent yields within a short period of time. 相似文献
139.
Somepalli Venkateswarlu Gandrotu Narasimha Murty Meka Satyanarayana Vidavalur Siddaiah 《合成通讯》2020,50(15):2347-2354
AbstractA new and efficient approach for the synthesis of thioflavones and thioaurones by competitive cascade cyclization of 2′-tosyloxychalcones has been developed. 2′-Tosyloxychalcones were smoothly converted into thioflavones and thioaurones by incorporation of sulfur atom using elemental sulfur and triethylamine in DMSO with good yields. The advantages of the methodology are the formation of both thioflavones and thioaurones in a single step. Easily accessible substrates, mild reaction conditions and compatibility with a broad range of functional groups make this protocol clean and inexpensive. 相似文献
140.
Generalizing the theory of k-error linear complexity for single sequences over a finite field, Meidl et al. (J. Complexity 23(2), 169–192 (2007)) introduced three possibilities of defining error linear complexity measures for multisequences. A good keystream sequence must possess a large linear complexity and a large k-error linear complexity simultaneously for suitable values of k. In this direction several results on the existence, and lower bounds on the number, of single sequences with large k-error linear complexity were proved in Meidl and Niederreiter (Appl. Algebra Eng. Commun. Comput. 14(4), 273–286 (2003)), Niederreiter (IEEE Trans. Inform. Theory 49(2), 501–505 (2003)) and Niederreiter and Shparlinski (In: Paterson (ed.) 9th IMA International Conference on Cryptography and Coding (2003)). In this paper we discuss analogous results for the case of multisequences. We also present improved bounds on the error linear complexity and on the number of sequences satisfying such bounds for the case of single sequences. 相似文献