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931.
932.
Byeong Hwa Yun Peter C. Dedon Nicholas E. Geacintov Vladimir Shafirovich 《Photochemistry and photobiology》2010,86(3):563-570
The photosensitized hole injection and guanine base damage phenomena have been investigated in the DNA sequence, 5′-d(CAT G 1 Py C G 2 TCCTAC) with a site-specifically positioned pyrene-like (Py) benzo[ a ]pyrene 7,8-diol 9,10-epoxide-derived N2 -guanine adduct (G1 Py ). Generation of the Py radical cation and subsequent hole injection into the DNA strand by a 355 nm nanosecond laser pulses (∼4 mJ cm−2) results in the transformation of G1 Py to the imidazolone derivative Iz1 Py and a novel G1 Py * photoproduct that has a mass larger by 16 Da (M+16) than the mass (M) of G1 Py . In addition, hole transfer and the irreversible oxidation of G2, followed by the formation of Iz2 was observed (Yun et al. [2007], J. Am. Chem. Soc., 129, 9321). Oxygen-18 and deuterium isotope labeling methods, in combination with an extensive analysis of the MS/MS fragmentation patterns of the individual dG Py * nucleoside adduct and other data show that dG Py * has an unusual structure with a ruptured cyclohexenyl ring with a carbonyl group at the rupture site and intact guanine and pyrenyl residues. The formation of this product competes with hole injection and thus diminishes the efficiency of oxidation of guanines within the oligonucleotide strand by at least 15% in comparison with that in the dG Py nucleoside adduct. 相似文献
933.
R. A. Castro N. I. Anisimova V. A. Bordovsky G. I. Grabko 《Physics of the Solid State》2011,53(3):458-461
A comparative analysis has been performed for the specific features of the dispersion of the components of the complex permittivity
for pure and bismuth-doped thin films of amorphous arsenic triselenide. A correlation between the experimental data and theoretical
calculations of similar characteristics obtained in previous studies has been found. The mechanisms of the effects observed
have been discussed. 相似文献
934.
Ivan V. Skovpin Vladimir V. Zhivonitko Igor V. Koptyug 《Applied magnetic resonance》2011,41(2-4):393-410
The use of heterogeneous catalysts for parahydrogen-induced polarization (PHIP) of nuclear spins opens new horizons for production of hyperpolarized substances. Immobilization of homogeneous hydrogenation catalysts is a promising approach for designing the efficient heterogeneous catalytic systems capable of PHIP generation. Herein, we study the formation of PHIP in the gas-phase and in the liquid-phase hydrogenations of propyne and propylene catalyzed by silica-immobilized Rh complexes synthesized by the ligand-exchange anchoring of the Wilkinson’s complex RhCl(PPh3)3, the binuclear complex Rh2Cl2(C8H12)2 and the cationic complex [Rh(C8H12)2]+[BF4]? to the phosphine-modified silica gel. We consider the stability and the mechanistic aspects of the hydrogenation over the immobilized Wilkinson’s catalyst in terms of PHIP observation. Using a PASADENA (parahydrogen and synthesis allow dramatically enhanced nuclear alignment) effect, it is found, in particular, that liquid-phase propyne hydrogenation over the immobilized Wilkinsons’s catalyst at 70°C proceeds in a stable regime with a stereoselective cis addition of a hydrogen molecule, while in the gas phase at the same temperature the hydrogenation stereoselectivity is observed only for a short time after the reaction is started, and then the catalyst rapidly loses its activity. The reasons of the catalyst deactivation are discussed based on the literature data, the results of infrared spectroscopy study, and the comparison to the behavior of the immobilized binuclear and cationic Rh complexes. In addition, it is shown that the immobilized Wilkinson’s catalyst is reduced as temperature increases in the range of 90–130°C, as confirmed by X-ray photoelectron spectroscopy. 相似文献
935.
Roberto Laridondo Lui Daniel Rodrigues Blanco Vladimir Pavan Margarido Orlando Moreira Filho 《Micron (Oxford, England : 1993)》2009,40(5-6):552-559
B chromosomes are considered additional and non-essential; they likely originate from A chromosomes and follow a distinct evolution. In fish, approximately half of the Neotropical species with B chromosomes are Characiformes and 35% are Siluriformes. There has been no report of B chromosomes in Auchenipteridae until this moment. B chromosomes found in a population of Parauchenipterus galeatus from the São Francisco River basin in the state of Minas Gerais (Brazil) were small, metacentric, totally heterochromatic and exhibited intra-individual and inter-individual variation. The diploid number was 58 chromosomes (22 metacentric, 16 submetacentric, 12 subtelocentric and 8 acrocentric). The nucleolar organizing regions were simple and the heterochromatin intercalated in the ribosomal sites, characterized by CMA3 and DAPI fluorochromes, was of a GC-rich constitution. The 5S rDNA genes were located in an intercalary position in only one chromosome pair. An hypothesis about the origin of the B chromosomes in P. galeatus and a review on B chromosomes in catfish are also presented in this study. 相似文献
936.
937.
Vladimir Ćirić Jelena Kolokotronis Ivan Milentijević 《AEUE-International Journal of Electronics and Communications》2009,63(5):398-405
Whereas some applications require correct computation many others do not. A large domain where perfect functional performance is not always required is multimedia and DSP systems. Relaxing the requirement of 100% correctness for devices and interconnections may dramatically reduce costs of manufacturing, verification, and testing. The goal of this paper is to develop a method for trading computational correctness for an additional chip area involved by fault-tolerance implementation. The method is demonstrated for the BP array in the following way: only the most significant bits of the output word are made fault-tolerant. By introducing the concept of partially error-tolerant BP array, designers achieve one more degree of tradeoff freedom. Formal definitions of the proposed terms are given. A mathematical path based on transitive closure that generates an error significance map for the BP array is proposed. The design tradeoff is demonstrated through FPGA implementation. The achieved area savings are presented as a function of a number of most significant fault-tolerant bits. 相似文献
938.
939.
940.
Sabir Jacquir Stéphane Binczak Jean-Marie Bilbault Viktor Kazantsev Vladimir Nekorkin 《Nonlinear dynamics》2006,44(1-4):29-36
An electrical circuit is proposed to realize an unidirectional coupling between two cells, mimicking chemical synaptic coupling.
Each cell represents the FitzHugh–Nagumo (FHN) model of neuron with a modified exitability (MFHN). We present experimental
results on frequency doublings and on the chaotic dynamics depending on the coupling strength in a master–slave configuration.
In all experiments, we stress the influence of the coupling strength on the control of the slave neuron. 相似文献