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41.
Bureau R Daveu C Lancelot JC Rault S 《Journal of chemical information and computer sciences》2002,42(2):429-436
A first definition of a pharmacophore for the serotonin reuptake inhibitors was carried out by considering a three-dimensional model which correlates the chemical structures of series of reuptake inhibitors with their biological affinities. A molecular design was described by analyzing two different 3D serotonin pharmacophores. This successful approach enabled us to consider the design of new serotonin ligands by the same method. 相似文献
42.
Jean-Jacques Aaron Zouhair Mechbal Alain Adenier Cyril Parkanyi Vaclav Kozmik Jiri Svoboda 《Journal of fluorescence》2002,12(2):231-239
The structural and solvent effects on the electronic absorption and fluorescence spectra, and fluorescence quantum yields, of four new fused benzothiophene derivatives, including benzothieno[3,2b]-thiophene (BTT), benzothieno[3,2-b]benzothiophene (BTBT), 6-methoxy[1]benzothieno[3,2b]-thiophene (MeOBTT), and benzothieno[3,2-b]indole (BTI) were investigated at 295 K. The luminescence properties of the corresponding conductive oligomers, poly(BTT) and poly (MeOBTT), electrosynthesized in acetonitrile, were also studied. Satisfactory McRae, Suppan, and Kawski-Chamma-Viallet solvatochromic correlations were established for the four monomers in most solvents. A weak negative solvatochromic behavior was found for these compounds, indicating that their dipole moments are slightly lower in the excited singlet state than in the ground state. Kamlet-Abboud-Taft multiparametric correlations were also obtained for absorption and fluorescence wave numbers and quantum yields, demonstrating the existence of specific solute-solvent interactions. In the case of the oligomers, important red-shifts of the fluorescence emission maxima ( 90–110 nm) relative to the corresponding monomers were observed, which shows the extent of conjugated segments in the oligomer chains. 相似文献
43.
Cyril T. Langlois Tetsuo Oikawa Pascale Bayle-Guillemaud Christian Ricolleau 《Journal of nanoparticle research》2008,10(6):997-1007
CuAg core–shell nanoparticles are synthesized by ultra-high vacuum thermal evaporation. We show on this system how the Energy-Filtered
Transmission Electron Microscopy (EFTEM) technique allows one to improve the characterization by precisely pointing out the
formation of core–shell arrangements in bimetallic nanoparticle assemblies. A criterion to measure the shell thickness from
EFTEM images on unique core–shell nanoparticles is defined, that can be used for core–shell nanoparticles of any sizes, with
shell thicknesses over 1 nm. It is based on the intensity variation along a line drawn across a core–shell nanoparticle on
a EFTEM image. This criterion has been validated by a close comparison of the shell thickness measurements performed in this
work and the ones obtained by acoustic micro-Raman spectroscopy. Using this criterion, we report a strong correlation between
the size of the Cu cores and the formation of the core–shell arrangements in the nanoparticle assembly studied in this work.
The influence of the Cu core shape is also evidenced. The characterisation of such systems using High Resolution TEM (HRTEM)
is also discussed. 相似文献
44.
Photoprotection of Mammalian Acid-Soluble Collagen by Cuttlefish Sepia Melanin In Vitro 总被引:1,自引:0,他引:1
Julian M. Menter Abrienne M. Patta Thomas D. Hollins Cyril L. Moore Isaac Willis 《Photochemistry and photobiology》1998,68(4):532-537
Several important clinical conditions can result in close association between the pigment melanin and dermal collagen. Because melanin and its precursors can be chemically reactive in ground and excited states, it is important to know whether the resulting melanin-collagen interaction results in photoprotection or photoaggression. Acidic and neutral air-saturated collagen suspensions (0.033%) were irradiated with0–2.6 times 104 J/m2 UVC or with0–83 times 104 J/m2 solar-simulating UV radiation (SSR). Photochemical destruction of a photolabile collagen fluorophore (δem 360 nm) and collagen chain degradation were monitored as functions of irradiation time in the presence and absence of added (0–100μg) sepia eumelanin. Melanin retarded collagen photodamage but did not qualitatively alter the fluorescence fading kinetics. Both H202 and 02 can be produced by UV irradiation of eumelanin. Added H202 and K02 destroyed collagen fluorescence and caused 50% chain degradation at ca10–20-fold molar excess. Previous studies have demonstrated that eumelanins efficiently scavenge 02 . We demonstrated that eumelanin also efficiently scavenges H202 as evidenced by its ability to (a) compete with scopoletin for peroxide uptake and (b) directly take up H202 through a dialysis bag. The latter observation suggests that peroxide scavenging could occur in vivo by melanin sequestered in melanophages. Thus, neither UV-generated 02 nor H202 are likely to be present in concentrations high enough to cause measurable collagen damage. Absorption and/or scattering of excitation radiation away from the target chromophore appears to be the primary photoprotection mechanism, although scavenging of active 02 intermediates may play an important, if subtle role. 相似文献
45.
5-Aroylamino-3H-1,3,4-thiadiazole-2-thiones 2 have been synthesized by acylation of 5-amino-3H-1,3,4-thiadiazole-2-thione 1 . 5-Aroylamino-3H-1,3,4-thiadiazole-2-thiones can exist in two tautomeric forms — a thiol form and a thione form. On the basis of the 13C nmr spectra and additional experimental information, it has been established that the thione form is the stable form in which these compounds exist. 相似文献
46.
Bel R Behnia K Proust C van der Linden P Maude D Vedeneev SI 《Physical review letters》2004,92(17):177003
We present a study of heat and charge transport in Bi(2+x)Sr(2-x)CuO(6+delta) focused on the size of the low-temperature linear term of the thermal conductivity at optimal-doping level. In the superconducting state, the magnitude of this term implies a d-wave gap with an amplitude close to what has been reported. In the normal state, recovered by the application of a magnetic field, measurement of this term and residual resistivity yields a Lorenz number L=kappa(N)rho(0)/T=1.3+/-0.2L(0). The departure from the value expected by the Wiedemann-Franz law is thus slightly larger than our estimated experimental resolution. 相似文献
47.
This study was designed to evaluate changes in erythrocyte contents during endurance moderate intensity exercise, a model of physiological oxidative stress. 16 endurance-trained subjects cycled 2 h at 55% of maximal aerobic capacity and blood was collected every 15 min. Transmission FT-IR spectrometry was used to analyze separately plasma and erythrocyte content changes during oxidative stress. Erythrocyte FT-IR spectra were corrected for hemoconcentration (Hc) before spectral areas integration of main IR absorbances belonging to phospholipids [nu(as)(CH(3)), [nu(as)(CH(2)), and nu(P=O)], proteins [nu(C=O) and delta(N-H)], and lactate [nu(C-O)] were used to determine erythrocyte content changes. Changes in nu(as)(CH(2)) and nu(P=O) absorbances while nu(as)(CH(3)) remained stable showed the magnitude of free radical attacks on phospholipids bilayer. Decrease in nu(C=O) and delta(N-H) absorbances while plasma and intracellular lactate, O(2) consumption, and Hc rose were linked to hemoglobin, and possibly spectrin, denaturation. Finally, the synergistic changes found between physiological, plasmatic and erythrocyte parameters showed that FT-IR spectrometry was a sufficiently accurate and sensitive method to determine acute changes in erythrocytes during moderate, physiological, oxidative stress. 相似文献
48.
Poriel C Ferrand Y Le Maux P Rault-Berthelot J Simonneaux G 《Inorganic chemistry》2004,43(16):5086-5095
Anodic oxidation of free base and manganese complexes of tetraspirobifluorenylporphyrins leads to the coating of the working electrode by insoluble electroactive poly(9,9'-spirobifluorene-free and manganese porphyrin) films which electrochemical behavior and physicochemical properties are described. After removal from the electrode, the manganese-complexed polymers were evaluated as catalysts for the oxidation of alkenes by iodobenzene diacetate or iodosylbenzene. The results show that the reactions proceeded very efficiently at room temperature with good yields. The electrosynthesized polymer catalysts can be recycled by simple filtration and reused even up to the eighth cycle without loss of activity and selectivity. These results represent an important improvement over those previously described for manganese-porphyrin-catalyzed epoxidation reactions. 相似文献
49.
Solladié N Walther ME Gross M Duarte TM Bourgogne C Nierengarten JF 《Chemical communications (Cambridge, England)》2003,(19):2412-2413
In addition to the ammonium-crown ether recognition, pi-stacking interactions between the C60 sphere and the porphyrin moiety have been evidenced in a supramolecular complex obtained from a porphyrin-crown ether conjugate and a fullerene derivative bearing an ammonium unit. 相似文献
50.
Godard C Duckett SB Parsons S Perutz RN 《Chemical communications (Cambridge, England)》2003,(18):2332-2333
UV irradiation of a solution of (eta5-C5H5)bis(ethene)rhodium in the presence of 2,2'-dipyridylketone yields (eta5-C5H5)Rh(kappa2-N,O-2,2'-dipyridylketone) which inserts ethene to yield a bicyclic oxametallacyclopentane. 相似文献