The activity and stability of niobia supported
on silica catalyst have been tested in continuous
micro-pilot reactors, for biodiesel production starting
from acid vegetable oils. A catalyst was ...prepared
by the impregnation of silica pellets with a loading
of 12% of Nb and was extensively characterized.
The activity of this catalyst in both esterification and
transesterification was tested in a continuous micro-pilot
laboratory plant in which acid oil was fed (FFA 10% w/w)
at a temperature of 220°C and at a pressure of 60 bar.
The niobia based catalyst resulted in a very active
catalyst in both esterification (FFA conversion =
95-90%) and transesterification reactions (FAME
yield = 80-90%), and the activity remained
quite constant for more than 100 h on stream.
Notwithstanding this stability, a non-negligible leaching
phenomena has been detected, in the case of long-time
continuous runs, as the Nb concentration on the spent
catalyst resulted lower than that on the fresh one. The
obtained result confirms that the leaching of the active
specie is one of the most strong problem in heterogeneous
catalysis for biodiesel production.
Gold nanoparticles have been prepared by alcoholic reduction of Au(III) ions in presence of a polymeric stabilizer (poly(
N-vinyl pyrrolidone), PVP).
On-line UV–vis spectroscopic characterization and ...transmission electron microscopy (TEM) analysis are presented. Optical spectroscopy data show that the temporal evolution of absorption spectra and the absorbance peak properties are correlated to the
off-line size measurements obtained at chemical reaction end by TEM micrographs. The Au cluster size behaves linearly with time above a threshold temperature (70
°C), according to a deposition-controlled growth mechanism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
As advanced technologies are expanding, the need for novel functional materials significantly increases. Nowadays, materials with special combinations of properties (like, for example, ...magnetictransparent, conductive-transparent, catalytic-magnetic, etc.) are strictly required. Nano-structured materials will surely represent an adequate solution to many present and future technological demands, because they exhibit both novel properties (e.g., plasmon resonance, superparamagnetism, superplasticity) and unique properties combinations. Applications of metal/polymer nanocomposites have already been made in different technological fields; however, the use of a much larger number of devices based on these materials can be predicted for the future. A short description of some polymer-embedded metal clusters applications follows.
In the dentistry field, synthetic hydroxyapatite can be conveniently used as semiabsorbable alloplastic material to solve a number of clinical problems. The hydroxyapatite structure influences bone ...ingrowth as well as its resorption. In particular, pore size must exceed 100 microm to allow new bone ingrowth. Because of its brittleness, highly porous hydroxyapatite is difficult to handle without causing damage, and, therefore, its mechanical performance has to be improved placing the material on a dense hydroxyapatite substrate. Dense/porous hydroxyapatite laminates can be obtained by slip casting technology. The method starts with the preparation of a ceramic powder-binder-solvent system. This slurry produces, after solvent evaporation, a soft green tape, that is successively baked at 300 degrees C to remove all organic component, and finally sintered at high temperature (1200 degrees C). The material porosity cannot be significantly modified by changes in the slurry composition and sintering temperature; therefore, the macroporous hydroxyapatite layer must be obtained using a porous hydroxyapatite powder. The powder is prepared by grinding of green tape pieces and the resulting coarse material is successively baked at 300 degrees C. Such material is mixed with a polymer solution and cast on a green tape substrate. Layer fractures are not observed in both film bulks and interface, because during sintering the consolidation of two layers happens simultaneously. In the resulting material, the first layer consisted of macroporous hydroxyapatite with high osteoconductive properties, and the second layer was a dense hydroxyapatite substrate able to improve the laminate mechanical properties.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Coronary artery disease is the leading cause of death in western countries, and its association with lower extremity peripheral artery disease (LE-PAD) represents an independent predictor of worse ...outcome. However, the molecular mechanisms underlying these effects are currently unknown.
To investigate these processes, we used in vitro approaches and several mouse models: (i) unilateral limb ischaemia by left common femoral artery ligation peripheral ischaemia (PI), n = 38; (ii) myocardial infarction by permanent ligation of the left descending coronary artery (MI, n = 40); (iii) MI after 5 weeks of limb ischaemia (PI + MI, n = 44); (iv) sham operation (SHAM, n = 20). Compared with MI, PI + MI hearts were characterized by a significant increase in cardiomyocyte apoptosis, larger infarct areas, and decreased cardiac function. By using a proteomic approach, we identified a ≅ 8 kDa circulating peptide, Dermcidin (DCD), secreted by ischaemic skeletal muscles, enhancing cardiomyocytes apoptosis under hypoxic conditions and infarct size after permanent coronary artery ligation. siRNA interference experiments to reduce DCD circulating levels significantly reduced infarct size and ameliorated cardiac function after MI.
Our data demonstrate that chronic limb ischaemia activates detrimental pathways in the ischaemic heart through humoral mechanisms of remote organ crosstalk. Thus, DCD may represent a novel important myokine modulating cardiomyocyte survival and function.
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