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61.
C. Alvarez-Ibarra E. Dvila A. Mateo P. Ortiz M. L. Quiroga 《Tetrahedron letters》1987,28(52):6667-6670
We report a new synthesis of thiazoles from a cyclocondensation reaction between dimethyl N-(ethoxycarbonylmethyl)iminodithiocarbonate (EMIC), carbon disulfide and alkylation of intermediate thiazole-2-thiolate with alkyl halides. 相似文献
62.
63.
Juan Manuel Ortiz‐Sánchez Ricard Gelabert Dr. Miquel Moreno Dr. José M. Lluch Prof. 《Chemphyschem》2008,9(14):2068-2076
The two isoelectronic bipyridyl derivatives [2,2′‐bipyridyl]‐3,3′‐diamine and [2,2′‐bipyridyl]‐3,3′‐diol are experimentally known to undergo very different excited‐state double‐proton‐transfer processes, which result in fluorescence quantum yields that differ by four orders of magnitude. In a previous study, these differences were explained from a theoretical point of view, because of topographical features in the potential energy surface and the presence of conical intersections (CIs). Here, we analyze the photochemical properties of a new molecule, [2,2′‐bipyridyl]‐3‐amine‐3′‐ol [BP(OH)(NH2)], which is, in fact, a hybrid of the former two. Our density functional theory (DFT), time‐dependent DFT (TDDFT), and complete active space self‐consistent field (CASSCF) calculations indicate that the double‐proton‐transfer process in the ground and first singlet π→π* excited state in BP(OH)(NH2) presents features that are between those of their “parents”. The presence of two CIs and the role they may play in the actual photochemistry of BP(OH)(NH2) and other bipyridyl derivatives are also discussed. 相似文献
64.
We propose a picture of Wigner function scars as a sequence of concentric rings along a two-dimensional surface inside a periodic orbit. This is verified for a two-dimensional plane that contains a classical hyperbolic orbit of a Hamiltonian system with 2 degrees of freedom. The stationary wave functions are the familiar mixture of scarred and random waves, but the spectral average of the Wigner functions in part of the plane is nearly that of a harmonic oscillator and individual states are also remarkably regular. These results are interpreted in terms of the semiclassical picture of chords and centers. 相似文献
65.
KM Varier AM Vinodkumar NVSV Prasad PV Madhusudhana Rao DL Sastry Lagy T Baby MC Radhakrishna NG Puttaswamy JJ Das P Sugathan N Madhavan AK Sinha DO Kataria 《Pramana》1999,53(3):529-533
Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies.
Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements
had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer
were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies. 相似文献
66.
Ortiz M Torréns M Fragoso A O'Sullivan CK 《Analytical and bioanalytical chemistry》2012,403(1):195-202
In this paper, we describe the development of an enzyme-linked oligonucleotide assay for the detection of a human leukocyte
antigen allele associated with celiac disease based on cyclodextrin-modified polymeric surfaces. The surface of maleimide-pre-coated
plates was modified with a layer of thiolated cyclodextrin polymer and used for the supramolecular capture of adamantane or
ferrocene-modified carboxymethylcellulose polymers bearing DNA probes. The assay was optimised in terms of incubation time,
temperature, and surface chemistry and applied to the highly sensitive and selective detection of HLA sequences with a limit
of detection of 0.7 nM. A real sample analysed using this platform showed an excellent correlation with maleimide-activated
plates using thiolated DNA probes. 相似文献
67.
T. Galeano Diaz A. Guiberteau J. M. Ortiz M. D. López F. Salinas 《Chromatographia》2001,53(1-2):40-46
Summary We have used an artificial neural network to optimize the composition of the mobile phase for an isocratic HPLC method for
the analysis of nitrophenol pesticides and related compounds, on the basic of different response functions, and have compared
the results with those obtained by application of response-surface methodology. These studies resulted in the selection the
mobile phase 10:30:15:45 methanol-acetonitrile-tetrahydrofuran-buffer solution (0.1m acetic acid and 0.1m sodium perchlorate); the flow-rate was 1 mL min−1. Under these conditions a chromatogram showing twelve well-resolved peaks was obtained in 14 min. Although the peaks corresponding
to ethylparathion and medinoterb acetate overlapped severely, it was possible, by use, of a diode-array spectrophotometer
for detection, and by combining the absorbance measured at different wavelengths as the signal, to separate the peaks corresponding
to one or other of the compounds. Calibration plots were constructed for the concentration range 2–10 ppm. Detection limits,
calculated by the method of Clayton et al., were approximately 0.32–0.69 ppm. The method has been applied to the analysis
of these compounds in fortified river water samples, after previous preliminary preconcentration by solid-liquid extraction
on a C18 cartridge. 相似文献
68.
69.
Mogolloń L. Rodríguez R. Larrota W. Ortiz C. Torres R. 《Applied biochemistry and biotechnology》1998,(1):765-777
Asphaltenes from a crude oil rich in heavy metals (Castilla crude oil) were fractionated and partially characterized. Biocatalytic
modifications of these fractionated asphaltenes by three different hemoproteins: chloro-peroxidase (CPO), cytochrome C peroxidase
(Cit-C), and lignin peroxi-dase (LPO) were evaluated in both aqueous buffer and organic solvents. The reactions were carried
out in aqueous buffers, ternary systems of toluene: isopropanol: water, and aqueous-miscible organic solvent solutions with
petroporphyrins as substrate. The petroporphyrins were more soluble in the ternary systems and aqueous miscible-organic solvent
systems than in the aqueous buffer systems. However, only the CPO-mediated reactions were effective in eliminating the Soret
peak in both aqueous and organic solvent systems. The effects of CPO-mediated reactions on the release of the metals complexed
with the porphyrins and asphaltenes were also determined. Chloroperoxidase was able to alter components in the heavy fractions
of petroleum and remove 53 and 27% of total heavy metals (Ni and V, respectively) from petroporphyrin-rich fractions and asphaltenes 相似文献
70.