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101.
Ganesh P. Sanganwar Ram B. Gupta Alexandre Ermoline James V. Scicolone Rajesh N. Dave 《Journal of nanoparticle research》2009,11(2):405-419
Due to the increased use of nanocomposites, mixing at nanoscale has become important. Current mixing techniques can be classified
into: (a) dry mixing (mechanical mixing), (b) wet mixing, and (c) simultaneous production of mixed nanoparticles (when possible).
Dry mixing is in general not effective in achieving desired mixing at nanoscale, whereas wet mixing suffers from different
disadvantages like nanomaterial of interest should be insoluble, has to wet the liquid, and involves additional steps of filtration
and drying. This paper examines the use of pressurized carbon dioxide having high density and low viscosity to replace the
liquids (e.g., n-hexane, toluene). Ultrasound is applied to the suspension of nanopowders in gaseous and supercritical carbon dioxide where
high impact collisions during sonication help mixing and the final mixture is obtained by simple depressurization. The method
is tested for binary mixture of alumina/silica, silica/titania, MWNT (multiwalled carbon nanotubes)/silica, and MWNT/titania.
The effects of sonication intensity and pressure on the degree of mixing are studied. Comparative study is also done with
liquid n-hexane as a mixing media. Quantitative characterization (e.g., mean composition standard deviation, intensity of segregation)
of mixing of alumina/silica and silica/titania is done with energy-dispersive X-ray spectroscopy, and that of MWNT/silica
and MWNT/titania is done using field-emission scanning electron microscopy and day-light illumination spectrophotometry. Results
show that mixing in carbon dioxide at higher ultrasound amplitudes is as good as in liquid n-hexane, and the final mixed product does not contain any residual media as in the case of liquid n-hexane. 相似文献
102.
Hawking radiation is studied for arbitrary scalars, fermions and spin-1 bosons, using a tunneling approach, to every order in ? but ignoring back-reaction effects. It is shown that the additional quantum terms yield no new contribution to the Hawking temperature. Indeed, it is found that the limit of small ? in the standard quantum WKB approximation is replaced by the near-horizon limit in the gravitational WKB approach. 相似文献
103.
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105.
Larisa Petrovna Demyanova Viaseslav S. Rimkevich Alexandre S. Buynovskiy 《Journal of fluorine chemistry》2011,132(12):1067-1071
A method of elaboration of nanometric amorphous silica is proposed using a rational processing of quartz-based ores with the help of a fluorination method. The different steps of the process are described, including the kinetics of the interaction mechanism of ammonium bifluoride with the initial raw materials, the sublimation of ammonium fluorosilicate and the formation of nanometric amorphous silica. Rate constants and activation energy of the chemical reactions are calculated. 相似文献
106.
107.
Alexandre Marletta M.L. Vega Y. Galvão Gobato R.M. Faria 《Applied Surface Science》2010,256(10):3018-213
In this work, we have studied the surface morphology of photo-irradiated poly(p-phenylene vinylene) (PPV) thin films by using atomic force microscopy (AFM). We have analyzed the first-order statistical parameters, the height distribution and the distance between selected peaks. The second-order statistical analysis was introduced calculating the auto-covariance function to determine the correlation length between heights. We have observed that the photo-irradiation process produces a surface topology more homogeneous and isotropic such as a normal surface. In addition, the polymer surface irradiation can be used as a new methodology to obtain materials optically modified. 相似文献
108.
Back Cover: Formal Total Synthesis of Diazonamide A by Indole Oxidative Rearrangement (Chem. Eur. J. 31/2016) 下载免费PDF全文
109.
We reduce the problem on multiplicities of simple subquotients in an -stratified generalized Verma module to the analogous problem for classical Verma modules. 相似文献
110.
Alexandre Turull 《Proceedings of the American Mathematical Society》2002,130(2):367-370
It has been noticed by many authors that the Schur indices of the irreducible characters of many quasi-simple finite groups are at most . A conjecture has emerged that the Schur indices of all irreducible characters of all quasi-simple finite groups are at most . We prove that this conjecture cannot be extended to the set of all finite perfect groups. Indeed, we prove that, given any positive integer , there exist irreducible characters of finite perfect groups of chief length which have Schur index .