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排序方式: 共有453条查询结果,搜索用时 10 毫秒
91.
Parambath Anilkumar Edmond Gravel Ioanna Theodorou Karine Gombert Benoit Thézé Frédéric Ducongé Eric Doris 《Advanced functional materials》2014,24(33):5246-5252
The development of a photo‐responsive micellar system capable of triggering cell death is reported. Precursors of the micelles are synthesized by connecting a lipophilic chain to a hydrophilic polyethylene glycol via a photo‐labile nitrobenzyl group. The resulting amphiphilic units are self‐assembled in water forming 12 nm micelles that are readily internalized into cells. Upon photo‐irradiation, micelles undergo cleavage and yield a cytotoxic nitrosobenzaldehyde derivative, which significantly inhibits the proliferation of MDA‐MB‐231 cells under standard in vitro conditions. 相似文献
92.
Guillaume Plazenet Catherine Martin Edmond Payen Bernadette Rebours John Lynch 《Microporous and mesoporous materials》2005,80(1-3):275-278
Mo/Ze catalysts prepared by incipient wetness impregnation of a Faujasite zeolite with ammonium heptamolybdate solutions have been characterized after calcination at 500 °C and transfer in wet atmosphere. Raman spectroscopy clearly evidences the formation of [SiMo12O40]4− heteropolyanions. This formation, through extraction of Si atoms, is not observed before the calcination, the Anderson [AlMo6O24H6]3− entity being the main species formed during the impregnation–maturation. 相似文献
93.
AJ Gamboa-Pinto CL Rock MG Ferruzzi AB Schowinsky SJ Schwartz 《Canadian Metallurgical Quarterly》1998,128(11):1933-1936
Results from epidemiologic studies suggest that a carotenoid-rich diet may reduce risk for cervical cancer, possibly by inhibiting the progression of cervical intraepithelial neoplasia, a preneoplastic lesion of the cervical tissue. Laboratory studies suggest that the mechanism may be linked to the metabolism of carotenoids to retinoic acid or retinoic acid-like compounds, which has been hypothesized to occur in the cervical tissue. The purpose of this study was to demonstrate the presence of provitamin A carotenoids in biopsied samples of this peripheral tissue in human subjects and to examine the relationship between baseline concentrations of these carotenoids in plasma and normal cervical tissue in subjects who were being evaluated for possible participation in a diet intervention trial. Subjects were 13 women aged 19-41 y. With the use of HPLC methodology, plasma concentrations of alpha-carotene, beta-carotene and beta-cryptoxanthin were determined with UV/visible light detection for plasma and electrochemical detection for cervical tissue. Relationships between plasma and cervical tissue were evaluated with Pearson correlation analysis. Adjusted for plasma cholesterol concentration, plasma alpha-carotene and beta-carotene were correlated with cervical tissue concentrations (r = 0.91, P < 0.001; r = 0.90, P < 0.001; respectively). Adjusted for plasma cholesterol concentration, plasma beta-cryptoxanthin tended to be correlated with cervical tissue concentrations (r = 0.62, P = 0.058). These findings suggest that plasma concentrations of alpha-carotene and beta-carotene are good predictors of cervical tissue concentrations of these compounds in human subjects and describe a first step toward demonstrating a biological link between provitamin A carotenoids and cervical cancer in vivo. 相似文献
94.
By conjugation of proteins to beads, Ags can be selectively targeted into the MHC class I pathway of phagocytes in vivo and can stimulate CTL responses. Because phagocytes also present particulate Ag on MHC class II molecules, we examined whether these Ags stimulated concomitant CD4 T cell immunity. Although the priming of CD4 T cells with soluble OVA required adjuvants, particulate Ag was stimulatory when injected in saline. We next examined whether CD4 T cell responses played a role in the generation of CTL to particulate Ag. At low concentrations of Ag, OVA primed CTLs in wild-type mice but not in MHC class II-deficient animals, indicating that MHC class II presentation of Ag was essential for CTL generation. These data both support a model where CD4 T cells collaborate with CTLs as part of a three-cell interaction and identify a phagocyte as the third cell in this reaction. Interestingly, injection of higher concentrations of the same Ag primed equivalent CTL responses in both wild-type and MHC class II-deficient mice. These results indicate that a key variable in determining whether CTL generation is helper cell dependent or independent is the dose of immunogen. This may explain in part why CTL responses to abundant Ags, such as viruses, tend to be helper independent, while responses to less abundant Ags, such as minor histocompatibility Ags, require T helper cells. In addition, these results also point to the potential of using particulate Ags to prime or boost responses in settings with CD4 immunodeficiency. 相似文献
95.
Proffitt Dennis R.; Rock Irvin; Hecht Heiko; Schubert Jim 《Canadian Metallurgical Quarterly》1992,18(1):3
The stereokinetic effect (SKE) has been defined and studied by nested circular patterns rotating on a turntable. Circles must appear not to rotate as they revolve, which in turn results in their appearing to translate relative to one another. A powerful illusion of object depth results even though the individual circles do not undergo an appropriate foreshortening consistent with their apparent changes in slant. It is suggested and tested that the SKE is based on the changing positions between the nested contours despite the absence of any change within each contour, whereas the kinetic depth effect (KDE) entails both kinds of change. It follows that a turntable method of presentation is not necessary, and between-contour transformations can be stimulated by computer animation. Displays consisting of simple translations were shown to evoke robust depth impressions as were patterns consisting of contours of varying shapes. Comparisons of the depth, compellingness, and rigidity of matched SKE and KDE displays are reported. The SKE is taken to be paradigmatic for how the visual system perceives depth when observing small object rotations that occur in everyday situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
97.
Seung Hyun Cho Young Rock Kwon Seok Ki Kim Chang Ho Noh Jun Young Lee 《Polymer Bulletin》2007,59(3):331-338
Summary Electrophoretic display system was fabricated to investigate the effectiveness of transparent polymer electrode using Poly
(3,4-ethylenedioxythiophene) (PEDOT). The electrophoretic TiO2 nanoparticles were coated to modify the surface. As a transparent polymer electrode, 3,4-ethylenedioxythiophene (EDOT) was
in-situ polymerized into PEDOT. When the reducing agent (N-dimethylacetamide, DMAc) was added, surface resistivity of PEDOT
was dominantly reduced. With the DMAc addition of 40 wt % to the monomer content, surface resistivity was as low as 100 Ω/□,
and transmittance was almost 80% in visible ray region. 相似文献
98.
Carmen I. Cabello Mercedes Muñoz Edmond Payen Horacio J. Thomas 《Catalysis Letters》2004,92(1-2):69-73
The influence of Co content in the catalytic activity in hydrotreatment reactions (hydrodesulfurization (HDS) of thiophene and hydrogenation (HYD) of cyclohexene) using CoMo6/γ-Al2O3-type catalysts, where the precursor is Co(III) heteropolymolybdate of (NH4)3[CoMo6O24H6?7H2O formula and Anderson-type planar structure, (hereafter CoMo6) was investigated. The preparation of catalysts was carried out by the coimpregnation of γ-alumina with CoMo6 and (NH4)6[TeMo6O24]?]7H2O (TeMo6) in order to obtain catalysts with variable amounts of Co(III) keeping about the same Mo amount. The Anderson phase of Te(VI), (TeMo6) was chosen because of its good solubility and because no promoting effect of the Te was observed in hydrotreatment. Five catalysts were prepared by coimpregnation of γ-Al2O3 by using aqueous solutions of both phases in different proportions. Catalysts with a ratio [Co]/([Co] + [Mo]) between 0 and ~0.14 and a Mo loading (wt% Mo) between 8 and 10 were obtained. The Raman and diffuse reflectance (DR) spectroscopies were used for the characterization of bulk and supported CoMo6 phase. By analyzing the respective adsorption isotherms and parameters and according to the catalytic tests, it could be established that HDS as well as HYD activities of the catalysts increase as a function of the added Co. 相似文献
99.
Jihane Abou Rached Christelle El Hayek Eliane Dahdah Cédric Gennequin Samer Aouad Haingomalala Lucette Tidahy Jane Estephane Bilal Nsouli Antoine Aboukaïs Edmond Abi-Aad 《International Journal of Hydrogen Energy》2017,42(17):12829-12840
NixMg6?xAl1.8Ce0.2 (with 0 ≤ x ≤ 6) mixed oxides catalysts were prepared by hydrotalcite route. All the oxides were calcined at 800 °C and characterized by different physico-chemical methods. The catalysts are then reduced before their use in the steam reforming of toluene. The XRD and TG/DTA confirmed the formation of the hydrotalcite structure for the non-calcined samples. The N2 adsorption/desorption results revealed that all catalysts correspond to mesoporous materials. The study by temperature programmed reduction (H2-TPR) showed that the reducibility of the catalysts is influenced by the nickel content. The CO2-TPD results showed that the catalyst with high magnesium content present the highest basicity. The Ni2Mg4Al1.8Ce0.2 shows the best toluene conversion among all the catalysts and it was then compared to a non-promoted catalyst. The spent catalysts were characterized by TPO, TG/DTA and XRD and they didn't reveal any coke formation. 相似文献
100.
The importance of n−6 and n−3 polyunsaturated fatty acids (PUFA) in neonatal development, particularly with respect to the
developing brain and retina, is well known. This review combines recent information from basic science and clinical studies
to highlight recent advances in knowledge on PUFA metabolism and areas where research is still needed on infant n−6 and n−3
fatty acid requirements. Animal, cell culture, and infant studies are consistent in demonstrating that synthesis of 22∶6n−3
involves C24 PUFA and that the amounts of 18∶2n−6 and 18∶3n−3 influence PUFA metabolism. Studies to show that addition of
n−6 fatty acids beyond Δ6-desaturase alters n−6 fatty acid metabolism with no marked increase in tissue 20∶4n−6 illustrate
the limitations of analyses of tissue fatty acid compositions as an approach to study the effects of diet on fatty acid metabolism.
New information to show highly selective pathways for n−6 and n−3 fatty acid uptake in brain, and efficient path-ways for
conservation of 22∶6n−3 in retina emphasizes the differences in PUFA metabolism among different tissues and the unique features
which allow the brain and retina to accumulate and maintain high concentrations of n−3 fatty acids. Further elucidation of
the Δ6-desaturases involved in 24∶5n−6 and 22∶6n−3 synthesis; the regulation of fatty acid movement between the endoplasmic
reticulum and peroxisomes; partitioning to acylation, desaturation and oxidation; and the effects of dietary and hormonal
factors on these pathways is needed for greater understanding of neonatal PUFA metabolism. 相似文献