Search results for "Scientific"
showing 10 items of 1193 documents
Process parameters of microsphere preparation based on propylene carbonate emulsion-precursors.
2020
This study aimed for a detailed understanding of the impact of different process parameters involved during celecoxib-loaded microsphere preparation based on propylene carbonate emulsion-precursors.Microspheres were prepared by a modified emulsification-solvent extraction method. Performed investigations included polymer solubility and viscosity, microsphere size, morphology and stability, propylene carbonate content as well as celecoxib solid state, content and release.Rough-walled round microspheres with sizes between 21 µm and 122 µm and an internal sponge-like structure filled with residual propylene carbonate (content between 1.9 ± 0.1% and 6.7 ± 0.5% w/w) were obtained. Encapsulation …
Opaline effect pigments by spray induced self‐assembly on porous substrates
2005
Self‐assembling of opaline materials on porous substrates like paper requires a very fast crystallization, which can be realized with highly monodisperse colloids. This opens the possibility of applying effect pigments to such substrates not by spraying the rather large effect pigments themselves, but by spraying their building blocks, which self‐assemble later on. The feasibility of this approach is presented here for monodisperse polymethyl methacrylate (PMMA) spheres. This process tolerates additives used for ink‐jet printing.
Applications of spray-drying in microencapsulation of food ingredients: An overview
2007
International audience; Spray-drying process has been used for decades to encapsulate food ingredients such as flavors, lipids, and carotenoids. During this drying process, the evaporation of solvent, that is most often water, is rapid and the entrapment of the interest compound occurs quasi-instantaneously. This required property imposes a strict screening of the encapsulating materials to be used in addition to an optimization of the operating conditions. Likewise, if the encapsulated compound is of hydrophobic nature, the stability of the feed emulsion before drying should also be considered. Thus, spray-drying microencapsulation process must rather be considered as an art than a science…
Solvent hydrodynamics speed up crystal nucleation in suspensions of hard spheres
2014
We present a computer simulation study on the crystal nucleation process in suspensions of hard spheres, fully taking into account the solvent hydrodynamics. If the dynamics of collodial crystallization were purely diffusive, the crystal nucleation rate densities would drop as the inverse of the solvent viscosity. However, we observe that the nucleation rate densities do not scale in this way, but are enhanced at high viscosities. This effect might explain the large discrepancy between the nuclation rate densities obtained by simulation and experiment that have reported in the literature so far.
A model of biomass char gasification describing the change in catalytic activity of ash
2012
A comprehensive description of catalytic effects during char gasification under various conditions relevant to biomass gasification was made. A three-parallel reaction model was proposed to describe the dynamic change in catalytic activity of ash during gasification of biomass char particles. Three different regimes of conversion were identified by analyzing char reactivity experiments conducted in a vertical TGA with nine biomasses under a wide range of operating conditions (temperature: 1023–1123 K, pressure: 0.1–3.0 MPa and gasification mixtures of CO2–CO–H2O–H2): (1) catalytic char gasification with deactivation of catalyst, (2) non-catalytic char gasification, and (3) catalytic char ga…
Seed- and wall-induced heterogeneous nucleation in charged colloidal model systems under microgravity
2011
Understanding the process that drives an undercooled fluid to the crystal state is still a challenging issue for condensed matter physics and plays a key role in designing new materials. The crystallization kinetics and the resulting polycrystalline morphology are given by a complex interplay of crystal nucleation, growth, and ripening. A great deal of progress has been made in recent years using colloidal suspensions as model systems in the study of crystallization. Close analogies to atomic systems are observed which can be exploited to address questions not accessible in atomic solidification. Here we present systematic measurements of the crystallization kinetics of a charged colloidal …
Colloidal lithography and Metal-Organic Chemical Vapor Deposition process integration to fabricate ZnO nanohole arrays
2010
A complete set up of optimal process conditions for an effective colloidal lithography/catalyst assisted MOCVD process integration is presented. It mainly focuses on the determination of the deposition temperature threshold for ZnO Metal-Organic Chemical Vapour Deposition (MOCVD) as well as the concentration of metal-organic silver (Ag) catalyst. Indeed, the optimization of such process parameters allows to tailor the ZnO film morphology in order to make the colloidal lithography/catalyst assisted MOCVD approach a valuable bottom up method to fabricate bi-dimensional ordered ZnO nanohole arrays. (C) 2010 Elsevier B.V. All rights reserved.
Numerical model of macro-segregation during directional crystallization process
1998
Abstract In the paper the mathematical model of macro-segregation proceeding during the directional crystallization process is presented. The boundary-initial problem considered is discussed. Next the numerical approximation constructed on the basis of the boundary element method supplemented by a procedure called the artificial heat source method is described. The boundary condition on the solidification front resulting from the alloy component balance is introduced, while in finally the practical aspects of computations concerning the course of the process are discussed.
Cuarenta años de difusión científica
2016
Editorial.
Medical English textbooks for Italian university students. Do they meet the Miur educational instructions about scientific English learning? Three wo…
2011
The ever increasing diffusion of English as the language of communication and scientific literature worldwide has made EMP (English for Medical Purposes) learning an integral part of medical students’ syllabuses. In medical English courses, teachers generally make use of textbooks which through a variety of activities usually involve all linguistic skills and provide students with the necessary means to communicate effectively and properly in their professional field. If we agree that a basic knowledge of general English should be assumed when undertaking any EMP course, then it follows that this specialist learning requires familiarity with a) specialised lexis and b) the morphosyntactic s…