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21.
22.
Rafael Dias do Espírito Santo Rosineide Costa Simas Alviclér Magalhães Vanessa Gonçalves dos Santos Thais Regiani Ana Cristina Isler Natiza Graziele Martins Marcos Nogueira Eberlin Eduardo René Pérez González 《Journal of Physical Organic Chemistry》2013,26(4):315-321
Molecules containing the guanidinic nuclei possess several pharmacological applications, and knowing the preferred isomers of a potential drug is important to understand the way it operates pharmacologically. Benzoylguanidines were synthesized in satisfactory to good yields and characterized by NMR, Electrospray Ionization Mass Spectrometry (ESI‐MS) and Fourrier Transform InfraRed Spectroscopy techniques (FTIR). E/Z isomerism of the guanidines was studied and confirmed by NMR analysis in solution (1H‐13C Heteronuclear Single Quantum Coherence (HSQC) and Heteronuclear Multiple‐Bond Correlation (HMBC), 1H‐15N HMBC, 1H‐1H Correlation Spectroscopy (COSY) and Nuclear Overhauser Effect Spectroscopy (NOESY) experiments) at low temperatures. Compounds with p‐Cl and p‐Br aniline moiety exist mainly as Z isomer with a small proportion of E isomer, whereas compounds with p‐NO2 moiety showed a decrease in proportion of isomer Z. The results are important for the application of these molecules as enzymatic inhibitors. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
23.
Sandra Même Nicolas Joudiou Frédéric Szeremeta Joël Mispelter Fanny Louat Martine Decoville Daniel Locker Jean-Claude Beloeil 《Magnetic resonance imaging》2013
In preclinical research, genetic studies have made considerable progress as a result of the development of transgenic animal models of human diseases. Consequently, there is now a need for higher resolution MRI to provide finer details for studies of small animals (rats, mice) or very small animals (insects). One way to address this issue is to work with high-magnetic-field spectrometers (dedicated to small animal imaging) with strong magnetic field gradients. It is also necessary to develop a complete methodology (transmit/receive coil, pulse sequence, fixing system, air supply, anesthesia capabilities, etc.). In this study, we developed noninvasive protocols, both in vitro and in vivo (from coil construction to image generation), for drosophila MRI at 9.4 T. The 10*10*80-μm resolution makes it possible to visualize whole drosophila (head, thorax, abdomen) and internal organs (ovaries, longitudinal and transverse muscles, bowel, proboscis, antennae and optical lobes). We also provide some results obtained with a Drosophila model of muscle degeneration. This opens the way for new applications of structural genetic modification studies using MRI of drosophila. 相似文献
24.
Repetitive DNAs have been extensively applied as physical chromosome markers on comparative studies, identification of chromosome rearrangements and sex chromosomes, chromosome evolution analysis, and applied genetics. Here we report the characterization of repetitive DNA sequences from the Nile tilapia (Oreochromis niloticus) genome by construction and screening of plasmid library enriched with repetitive DNAs, analysis of a BAC-based physical map, and hybridization to chromosomes. The physical mapping of BACs enriched with repetitive sequences and C(o)t-1 DNA (DNA enriched for highly and moderately repetitive DNA sequences) to chromosomes using FISH showed a predominant distribution of repetitive elements in the centromeric and telomeric regions and along the entire length of the largest chromosome pair (X and Y sex chromosomes) of the species. The distribution of repetitive DNAs differed significantly between the p arm of X and Y chromosomes. These findings suggest that repetitive DNAs have had an important role in the differentiation of sex chromosomes. 相似文献
25.
In this paper we study isotropic integrable systems based on the braid-monoid algebra. These systems constitute a large family of rational multistate vertex models and are realized in terms of the Bn, Cnand Dn Lie algebra and by the superalgebra Osp(n||2m). We present a unified formulation of the quantum inverse scattering method for many of these lattice models. The appropriate fundamental commutation rules are found, allowing us to construct the eigenvectors and the eigenvaluesof the transfer matrix associated to the Bn, Cn, Dn, Osp(2nt-1||2), Osp(2||2nt-2), Osp(2nt-2||2) and Osp(1||2n) models. The corresponding Bethe ansatz equations can be formulated in terms of the root structure of the underlying algebra. 相似文献
26.
Y. A. Coutinho J. A. Martins Simões C. M. Porto 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):705-709
In this paper we investigate the effects of heavy Majorana neutrinos in the reaction e + e ? → W + W ?. We consider neutrino masses in the 1–10 TeV region. We show that at LEP II and NLC energies it is possible to use this processes to verify indirect evidence of heavy neutral particles with mixing angles of the order sin2 α = 0.01. We discuss the unitarity restrictions that can be obtained for vector singlet and fermion-mirror-fermion models. 相似文献
27.
The linear conductance of a molecular conductor oscillating between two metallic leads is investigated numerically both for Hubbard interacting and noninteracting electrons. The molecule-leads tunneling barriers depend on the molecule displacement from its equilibrium position. The results present an interesting interference which leads to a conductance dip at the electron-hole symmetry point that could be experimentally observable. It is shown that this dip is caused by the destructive interference between the purely electronic and phonon-assisted tunneling channels, which are found to carry opposite phases. When an internal vibrational mode is also active, the electron-hole symmetry is broken but a Fano-like interference is still observed. 相似文献
28.
Jos Roberto Berretta Wagner de Rossi Maurício David Martins das Neves Ivan Alves de Almeida Nilson Dias Vieira Junior 《Optics and Lasers in Engineering》2007,45(9):960-966
The technique to weld AISI 304 stainless steel to AISI 420 stainless steel with a pulsed Nd:YAG laser has been investigated. The main objective of this study was to determine the influence of the laser beam position, with respect to the joint, on weld characteristics. Specimens were welded with the laser beam incident on the joint and moved 0.1 and 0.2 mm on either side of the joint. The joints were examined in an optical microscope for cracks, pores and to determine the weld geometry. The microstructure of the weld and the heat affected zones were observed in a scanning electron microscope. An energy dispersive spectrometer, coupled to the scanning electron microscope, was used to determine variations in (weight %) the main chemical elements across the fillet weld. Vickers microhardness testing and tensile testing were carried out to determine the mechanical properties of the weld. The results of the various tests and examinations enabled definition of the best position for the incident laser beam with respect to the joint, for welding together the two stainless steels. 相似文献
29.
Spatial distribution of AT- and GC-rich DNA within interphase cell nuclei of Triatoma infestans Klug
Alvarenga EM Mondin M Martins JA Rodrigues VL Vidal BC Rincones J Carazzolle MF Andrade LM Mello ML 《Micron (Oxford, England : 1993)》2011,42(6):568-578
Heterochromatin bodies in single- and multichromocentered interphase cell nuclei of Triatoma infestans, a vector of Chagas disease, have been suggested to contain AT-rich DNA, based on their positive response to Q-banding and Hoechst 33248 treatment. No information exists on whether GC-rich DNA is also present in these nuclei and whether it plays a role on chromatin condensation. Considering that methodologies more precise than those previously used to determine DNA base composition in situ are currently available, and that the spatial distribution of chromatin areas differing in composition in interphase cell nuclei of different species is a matter of interest, the localization of AT- and GC-rich DNA in T. infestans nuclei is revisited here. The methodologies used included DAPI/AMD and CMA(3)/Distamycin differential staining, Feulgen-DNA image analysis following Msp I and Hpa II enzymatic digestion, 5-methylcytidine immunodetection, AgNOR response, confocal microscopy, and the 5-aza-2'-deoxycytidine (5-AZA) demethylation assay. The results identified the presence of AT-rich/GC-poor DNA in chromocenters and evenly distributed AT and GC sequences in euchromatin. A GC-rich DNA zone encircling the chromocenters was also found but it could not be associated with NOR regions. To corroborate the DNA AT-richness in T. infestans nuclei, bioinformatic analyses were also performed. Methylated cytosine was evident at some points of the chromocenters' edge in single- and multichromocentered nuclei and at the euchromatin of multichromocentered nuclei and could be transiently affected by the 5-AZA treatment. The present results suggest that in the particular case of chromocenters of the hemipteran T. infestans, cytosine methylation is not a relevant factor involved in chromatin condensation. 相似文献
30.
L. de Arcangelis H. J. Herrmann M. Kolb René Thomas C. Amitrano L. Peliti M. Saber G. Weisbuch Sara A. Solla F. Bagnoli A. Francescato R. Livi S. Ruffo Pablo Tamayo Michel Droz Peter Jörg Plath S. Romano Yves Pomeau Stéphane Zaleski D. Stauffer Luciano R. da Silva Alex Hansen Stéphane Roux Antonio Coniglio B. Derrida Henrik Flyvbjerg Naeem Jan Dietrich Stauffer Peter Grassberger A. Zippelius K. E. Kurten Werner Krauth Jean -Pierre Nadal Marc Mézard Per Bak Chao Tang Itzhak Webman M. L. Martins H. F. V. Resende C. Tsallis A. C. N. Magalhaes 《Journal of statistical physics》1989,55(5-6):1333-1359