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101.
I. Belitchenko V. Melnikova L. Bezdetnaya H. Rezzoug J.L. Merlin A. Potapenko F. Guillemin 《Photochemistry and photobiology》1998,67(5):584-590
The photobleaching of meta -tetra(hydroxyphenyl)chlorin m THPC) (irradiation wavelength 413 nm) in protein-containing solution was evaluated by decay in absorbance in Soret band and in fluorescence (λexc = 423 nm, λem = 655 nm). Light exposure resulted in a decrease in absorption throughout the spectrum and simultaneous appearance of new absorption bands in the spectral region 325–450 nm. The rate of m THPC photodegradation, followed by decay in absorbance, was 15-fold lower than that observed in fluorescence. This fact reflects the photobleaching of presumably monomeric, fluorescing species of m THPC. In order to determine the consequences of photobleaching of fluorescing m THPC material on cellular uptake and photocytotoxicity, human HT29 colon adenocarcinoma cells were incubated with photobleached m THPC during 5 h with or without following irradiation with the fixed fluence. Surprisingly, but up to the time when the fluorescence decreased by 50%, only a slight decrease in photocytotoxicity was detected. Either aggregated forms that have been taken up undergo intracellular monomerization (but we did not observe increase in fluorescence in living cells) or the photodynamic activity is mostly due to aggregates. The discrepancy of m -THPC-photodynamic therapy (PDT) effect and fluorescence measurements may suggest that aggregated m -THPC plays an important role in m THPC-PDT. 相似文献
102.
International Journal of Game Theory - This article is devoted to the analysis of electoral systems involving two step procedures. It appears that designers are able to manipulate the result of... 相似文献
103.
Due to their advantages from an environmental point of view (i.e. reduction of volatile organic compounds (VOC)), photocurable
finishes should be extensively used for industrial wood joinery in the near future. However, several problems are reported,
particularly the poor durability of the finishing system. In the present work, the curing reaction of acrylic resins containing
some improved photoinitiators was studied by means of photocalorimetry under monochromatic irradiation from 366 to 450 nm.
The results show that finishes can be cured even under daylight so that they could be directly applied on site in case of
restoration. 相似文献
104.
K. Bajema R. Merlin F.-Y. Juang S.-C. Hong J. Singh P.K. Bhattacharya 《Superlattices and Microstructures》1987,3(6)
We report on a Raman scattering study of the electric-field dependence of c0 → c1 intersubband transitions of
electrons in a 264 Å GaAs- Al0.3Ga0.7As quantum-well structure. The measured Stark shifts are in very good agreement with theoretical predictions. The intensity of the intersubband peak increases rapidly with applied field due to parity-mixing. In contrast to the enhanced broadening shown by excitation resonances, the width of c0 → c1 is nearly independent of the field. This feature is attributed to effects of structural disorder. 相似文献
105.
Time-resolved microfocused small-angle X-ray scattering investigation of the microfluidic concentration of charged nanoparticles 总被引:1,自引:0,他引:1
We describe the concentration process of a dispersion of silica nanoparticles undergoing evaporation in a dedicated microfluidic device. Using microfocused small-angle X-ray scattering, we measure in time and space both the concentration field of the dispersion and its structure factor. We show that the electrostatic interactions affect the concentration rate by strongly enhancing the collective diffusion coefficient of the nanoparticle dispersion. En route towards high concentrations, the nanoparticles eventually undergo a liquid-solid phase transition in which we evidence crystallites of micron size. 相似文献
106.
Pablo J. Baricelli Luis G. Melean Santiago Ricardes Victor Guanipa Mariandry Rodriguez Carlos Romero Alvaro J. Pardey Sergio Moya Merlin Rosales 《Journal of organometallic chemistry》2009,694(21):3381-3385
The complex Mo(CO)3(NCMe)(PPh3)2, was synthesized by the reaction of Mo(NCMe)3(CO)3 with two equivalents of PPh3 and characterized by UV–Vis, IR, NMR and X-ray diffraction. This complex was used as a catalyst precursor for the hydrogenation of 1-hexene, styrene, cyclohexene and 2,3-dimethyl-1-butene and their mixtures under moderate conditions in homogeneous media. Under mild reaction conditions (T = 373 K, P = 60 atm), the substrates showed the following reactivity order: styrene > 1-hexene > cyclohexene > 2,3-dimethyl-1-butene. A quaternary equimolar mixture showed a different hydrogenation order: 1-hexene > cyclohexene > styrene > 2,3-dimethyl-1-butene; the presence of dibenzothiophene or mercury does not interfere with the activity of the catalyst. 相似文献
107.
DeCamp MF Reis DA Cavalieri A Bucksbaum PH Clarke R Merlin R Dufresne EM Arms DA Lindenberg AM MacPhee AG Chang Z Lings B Wark JS Fahy S 《Physical review letters》2003,91(16):165502
We measure transient strain in ultrafast laser-excited Ge by time-resolved x-ray anomalous transmission. The development of the coherent strain pulse is dominated by rapid ambipolar diffusion. This pulse extends considerably longer than the laser penetration depth because the plasma initially propagates faster than the acoustic modes. X-ray diffraction simulations are in agreement with the observed dynamics. 相似文献
108.
Raman scattering by phonons and by magnon pairs has been observed in Fe3BO6. Of the predicted 60 Raman-active modes, 39 have been identified and classified according to their symmetries. The two-magnon band shows a strong decrease in intensity with increasing temperature, and almost vanishes close to TN = 508 K. The origin of this effect is attributed to the existence of a nearly dispersionless magnon branch. 相似文献
109.
Rosales Merlin González Ángel Mora Milagros Nader Nidal Navarro Janeth Sánchez Ligbel Soscún Humberto 《Transition Metal Chemistry》2004,29(2):205-211
Kinetic and mechanistic studies of the homogeneous hydrogenation of cyclohexanone were carried out using the cationic complexes [MH(CO)(NCMe)2(PPh3)2]BF4 (M = Ru, Os) as the catalyst precursors, which were very efficient under mild reaction conditions in 2-methoxyethanol solution. For both complexes, the catalytic hydrogenation of cyclohexanone proceeds according to the rate law r = k[M][H2]. The activation parameters were also calculated, the activation energy for the osmium catalyst being higher than for the ruthenium(I). All experimental data are consistent with a mechanism involving the oxidative addition of hydrogen as the rate-determining step of the catalytic cycle. Finally, the [MH(CO)(NCMe)2(PPh3)2]BF4 complexes were efficient precatalysts for the selective reduction of 2-cyclohexen-1-one to cyclohexanone; the reduction of the CO group of cyclohexanone only begins to take place when the ,-unsaturated ketone has been consumed. 相似文献
110.
We report the first experimental demonstration of quantum squeezing of a collective spin-wave excitation (magnon) using femtosecond optical pulses to generate correlations involving pairs of spins in an antiferromagnetic insulator MnF2. In the squeezed state, the fluctuations of the magnetization of a crystallographic unit cell vary periodically in time and are reduced below that of the ground-state quantum noise. 相似文献