Search results for "Circulation"
showing 10 items of 1137 documents
Synthesis of Titanate Nanotubes Directly Coated with USPIO in Hydrothermal Conditions: A New Detectable Nanocarrier
2011
International audience; Abstract: For the first time, titanate nanotubes (TiONts) coated with USPIO (ultrasmall superparamagnetic iron oxide) without polymer functionalization and directly obtained during TiONts formation is reported. The coating of these tubes was performed directly during the TiONts hydrothermal synthesis. After this treatment, in strongly basic conditions, USPIO particles kept their structure and magnetic properties while their size distribution slightly increased. By coupling zeta-potential measurements and TEM observations at different pH it appeared that interactions between nanotubes and USPIO were not electrostatic. This study presents the new design of a titanate n…
Multi-spectral Reflection Photoplethysmography: Potential for Skin Microcirculation Assessment
2006
Technique for simultaneous recording of reflection photoplethysmography signals in broad spectral band (violet to NIR) has been developed, and its potential for assessment of blood microcirculation at various depths from the skin surface is discussed.
Preparation of Catalysts and Photocatalysts Used for Similar Processes
2019
Abstract This chapter reports the main techniques used to synthesize powders and films of heterogeneous catalysts and photocatalysts, often used for similar processes. Traditional preparation processes of bulky (photo)catalysts including precipitation, sol–gel technique, hydrothermal or solvothermal method, solid-state reactions, and flame syntheses were briefly described. The sonochemical method and microwave irradiation technique were also considered. The syntheses of supported catalysts by different techniques, including deposition–precipitation, impregnation, and wet coating technologies were also described. Moreover, a survey is reported of methods to deposit thin films of catalysts on…
Chromium oxide nanoparticles with controlled size prepared from hydrothermal chromium oxyhydroxide precursors
2017
Abstract This work reports the preparation of morphologically well-defined chromium oxide nanoparticles with controlled sizes of 20–30 nm. The synthetic procedure encompass two stages, the first one refers to the preparation of chromium oxyhydroxide nanoparticles by a hydrothermal approach of previously precipitated xerogels, followed by a thermal transformation of CrOOH nanoparticles to Cr2O3. The series of chromium oxyhydroxide particles sized over the range 15–50 nm were prepared through the control of the pH of precipitation of the xerogels and the water/xerogel ratio of the hydrothermal aging. Results showed the formation of non-aggregated oxyhydroxide nanoparticles with two different …
Increasing the stability of the Ge-containing extra-large pore ITQ-33 zeolite by post-synthetic acid treatments
2018
[EN] Extra-large pore ITQ-33 zeolite (ITT, 18 x 10 x 10-rings) is a very promising catalyst for the catalytic cracking of gasoil but, unfortunately, this material shows a limited hydrothermal stability due to the large germanium content present in the ITQ-33 structure. Taking this into account, the Ge-containing ITQ-33 has been post synthetically modified using different acid procedures with the aim of studying the effect of these treatments on the overall hydrothermal stability of this extra-large pore zeolite. In this sense, the as-prepared ITQ-33 has been treated with different HCl solutions in ethanol (from 0.1 to 1 M), containing also tetraethylorthosilicate (TEOS) as silicon precursor…
Microwave hydrothermal flash synthesis of nanocomposites Fe–Co alloy/cobalt ferrite
2004
Abstract The present article presents, for the first time, the last developments reported for an original microwave hydrothermal flash synthesis of Fe–Co alloys (FeyCo1−y)/cobalt ferrite (Fe3−xCoxO4) nanocomposites. Synthesis was performed in alcoholic solutions of ferrous chloride, cobalt chloride and sodium ethoxide (EtONa) using a microwave autoclave (The RAMO system) specially designed by authors. Compared with conventional synthesis, smaller grains (100 nm compared to 1 μm) can be produced in a short period (e.g. 10 s) using a less basic medium. In all the cases, the microstructure and the amount of metal inside the composite particles are very different from the product obtained via a…
Strain-dependent electrical resistance of epoxy/MWCNT composite after hydrothermal aging
2015
Abstract The electrical resistance of epoxy/multi-wall carbon nanotube (MWCNT) composites was studied under the effect of hygro- and hydrothermal aging. Tensile tests were conducted and the responses in the electrical resistance were measured during the tests for samples with different prehistory of environmental exposure. The overall pattern of the electrical resistance change versus strain for the samples tested consists of linear and nonlinear regions with a broad peak that precedes the ultimate strength of the sample and occurs at the onset of evident plastic deformation in the stress–strain curve. The composite with lower content of MWCNTs exhibits a more pronounced nonlinear behavior …
Morphological Control of Hydrothermal Ni(OH)2 in the Presence of Polymers and Surfactants: Nanocrystals, Mesocrystals, and Superstructures
2008
International audience; Polymers with different hydrophilic groups [polyvinylpyrrolidone (PVP), ammonium polyacrylate (APA), and hydroxypropylmethyl cellulose (HPMC)] and surfactants [cetyltrimethylammonium bromide (CTAB) and sodium dodecylbenzensulfonate (SDBS)] were used as additives to modify the crystallization of β-Ni(OH)2 in hydrothermal conditions. Marked morphological changes in the β-Ni(OH)2 particles were observed depending on the additive concentration and on the duration of the hydrothermal treatment. The final morphology is the result of a complex, time-dependent self-assembly and growth process. Well-defined particles with sizes from submicrometer range to a few micrometers co…
Simple New Method for the Preparation of La(IO3)3 Nanoparticles
2020
We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route, which takes a matter of hours, thereby providing an alternative to the common hydrothermal method, which takes days. Nanoparticles of pure &alpha
One step continuous hydrothermal synthesis of very fine stabilized superparamagnetic nanoparticles of magnetite
2011
International audience; Stable suspensions of citrated SPIO nanoparticles were synthesised in one step using a hydrothermal continuous process. Citrates control the crystallite size and the oxidation degree of metallic ions despite the very short reaction time (4 s). Magnetite particles, Fe2.94O4, with an average size of 4 nm and good monodispersity were obtained.