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排序方式: 共有208条查询结果,搜索用时 46 毫秒
101.
Pillot JP Birot M Tran TT Dao TM Belin C Desbat B Lazare S 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3338-3343
Self-assembled monolayers grafted onto silicon surfaces were obtained from the hydrosilylation products by trialcoxysilanes of naturally occurring phenolic lipid allyl ethers. The as-obtained materials were characterized by various physical and physicochemical methods. Thus, contact angles of water drops showed that they possess very high hydrophobicity. Their excellent regularity was corroborated by AFM microscopy. The frequencies of the stretching CH2 infrared modes indicate the presence of alkyl chains mainly in the trans/trans conformation. Additionally, optical ellipsometry and quartz microbalance measurements enabled us to estimate the thickness of the films. The results, as a whole, are in good agreement with the formation of densely packed monolayers. 相似文献
102.
103.
Briois V Lützenkirchen-Hecht D Villain F Fonda E Belin S Griesebock B Frahm R 《The journal of physical chemistry. A》2005,109(2):320-329
Time-resolved X-ray absorption spectroscopy (Quick-XANES) has been combined with UV-vis and Raman spectroscopies to study the in situ reduction of Ce4+ to Ce3+ in ethanolic solution with a time resolution of ca. 4-5 s. For this purpose, a cam-driven oscillating double-crystal monochromator with a channel-cut crystal was combined with two spectrometers for UV-vis and Raman spectroscopies in a specialized cell which allows one to fit the optical pathways for all three spectroscopies individually. The results show that high-quality results can be obtained simultaneously, thus giving a detailed insight into the mechanisms of the investigated chemical reaction. The continuous release of nitrate and ethanol ligands from the initial Ce4+ into the solution finally leads to a trivalent cerium species which is only coordinated with water molecules after about 1800 s of reaction time. 相似文献
104.
The multiple-scattering series for depolarized light scattering from simple liquids is investigated. It is found that the leading term in the series, due to double—double scattering, is probably not large compared to double—triple (DT) scattering contributions. Existing theories, which neglect DT scattering, have concluded that the experimental data cannot be explained using the dipole—induced dipole (DID) model for the pair polarizability. It is suggested that a theory which includes DT scattering will not lead to rejection of the DID model. 相似文献
105.
Boris Kamenar Branka Korpar-Čolig Maja Penavić Marina Cindrić 《Journal of chemical crystallography》1992,22(4):391-396
In the reaction of Mo2O3 (acac)4 and Mo2O3 (OAc)4 with thioacetylacetone two new complexes of molybdenum(V), Mo2O3 (acac)2(Sacac)2 (complexI) and Mo2O3(acac)3(Sacac) (complexII), respectively, have been prepared. Their crystal structures have been determined from single crystal diffractometer data and refined to the finalR values of 0.068 and 0.044, respectively. Both complexes crystallize in the tetragonal space groupI41/a with cell dimensions, (I):a=21.646(3),c=11.627(2) Å,D
calc=1.630 g cm–3,Z=8 and (II):a=21.240(3),c=11.688(2) Å,D
clac=1.644 g cm3–,Z=8 and have essentially the same structure. In the structure of (II) half of thioacetylacetone of (I) is statistically replaced by acetylacetone causing thus an occupational disorder in this region of the structure. Both complex molecules are dinuclear and have crystallographically imposed ¯1 symmetry with the bridging oxygen atom in the center of symmetry. Molybdenum atoms exhibit distorted octahedral coordinations. Sulfur atom of the Sacac ligand in (I) shows a considerably largertrans influence than the oxo-oxygen atom. 相似文献
106.
107.
108.
Branka Viltužnik Aljoša Košak Yuriy L. Zub Aleksandra Lobnik 《Journal of Sol-Gel Science and Technology》2013,68(3):365-373
We have investigated the removal of Pb2+ ions from water using thiol-functionalized, cobalt-ferrite, magnetic nanoparticles. These magnetic nanoparticles were prepared using the co-precipitation method and their surfaces were modified with tetraethoxy silane and 3-mercaptopropyl trimethoxysilane in order to provide a sufficient surface concentration of the thiol (–SH) functional groups. The adsorption of the Pb2+ ions from the aqueous solutions onto the thiol-functionalized, cobalt-ferrite, magnetic nanoparticles was studied. The investigated parameters include the pH value of the model water, the concentration of the adsorbent, the contact time and the temperature of adsorption. The removal of the Pb2+ was found to be greater at the higher pH values and increasing the temperature was also found to increase the removal of Pb2+ ions. 相似文献
109.
Perinović Jozić Sanja Jozić Dražan Jakić Jelena Andričić Branka 《Journal of Thermal Analysis and Calorimetry》2020,142(5):1877-1889
Journal of Thermal Analysis and Calorimetry - Modification of poly(lactic acid) (PLA) was performed with the surface modified magnesium hydroxide (mMH) obtained from seawater. Surface modification... 相似文献
110.
In order to reduce the nuclear waste inventory and radiotoxicity, U(1-x)Am(x)O(2±δ) materials are promising fuels for heterogeneous transmutation. In this context, they are generally fabricated from UO(2+δ) and AmO(2-δ) dioxide powders. In the subsequent solid solution, americium is assumed to be trivalent whereas uranium exhibits a mixed-valence (+IV/+V) state. However, no formation mechanisms were ever evidenced and, more particularly, it was not possible to know whether the reduction of Am(IV) to Am(III) occurs before the solid-solution formation, or only once it is established. In this study, we used high-temperature X-ray diffraction on a UO(2±δ)/AmO(2-δ) (15 mol?%) mixture to observe in situ the formation of the U(1-x)Am(x)O(2±δ) solid solution. We show that UO(2+δ) is, at relatively low temperature (<700 K), oxidized to U(4)O(9-δ), which is likely to be caused by oxygen release from the simultaneous AmO(2-δ) reduction to cubic Am(2)O(3±δ). Cubic Am(2)O(3+δ) then transforms to hexagonal Am(2)O(3) at 1300 K. Thus, the initial Am(IV) is fully reduced to Am(III) before the solid solution starts forming at 1740 K. The UO(2) fluorite phase vanishes after 4 h at 1970 K, indicating that the formation of the solid solution is completed, which proves that this solid solution is formed after the complete reduction of Am(IV) to Am(III). 相似文献