In the present investigation, a glassing process for galvanic waste (GW) incorporation with a high chemical stability is presented. Glasses with up to 50 wt% of galvanic solid waste by modifications in the basic composition of soda–lime–borosilicate glasses were prepared. After fusing at temperatures up to 1300°C, the glasses were characterized by inductively coupled plasma, scanning electron microscopy/energy-dispersive X-ray spectroscopy, high-temperature microscopy, transmission and reflected light microscopy, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and X-ray diffraction methods. The chemical stability was evaluated by hydrolytic attack assays. Glasses containing up to 40 wt% of GW with a very high chemical stability, similar to bottle glasses, were obtained. 相似文献
Ferritic stainless steels have become promising candidate materials for interconnects in tubular metal-supported solid oxide fuel cell stacks. A number of ferritic alloys containing between 18 and 26 mass% Cr and discrete changes in minor alloying elements and reactive elements were isothermally oxidized at 800 °C in air and their electrical resistance was measured with the objective of obtaining an overview of the properties relevant for applications for cathode side interconnect. The alloys containing Mn showed a (Mn,Cr)3O4 spinel layer on top of a Cr2O3 oxide. The electrical conductivity of the steels forming this kind of oxide layer was higher than the measured for only Cr2O3 former or oxide dispersion strengthened alloys and increased when the alloy contained Ti or Nb. Oxide scale spallation was observed for F18TNb and E-Brite, both containing Si. The influence of different cyclic oxidations was studied for the Crofer22APU steel, showing an irregular oxide growth as well as an increase in conductivity of the oxide scale formed when 12-h cycles were applied. 相似文献
Both cis‐ and trans‐but‐2‐ene‐1,4‐diamines have been prepared and efficiently applied as sacrificial cosubstrates in enzymatic transamination reactions. The best results were obtained with the cis‐diamine. The thermodynamic equilibrium of the stereoselective transamination process is shifted to the amine formation due to tautomerization of 5H‐pyrrole into 1H‐pyrrole, achieving high conversions (78–99%) and enantiomeric excess (up to >99%) by using a small excess of the amine donor. Furthermore, when the reaction proceeded, a strong coloration was observed due to polymerization of 1H‐pyrrole. A structurally related compound, cis‐but‐2‐ene‐1,4‐diol, has been utilized as cosubstrate in different alcohol dehydrogenase (ADH)‐mediated bioreductions. In this case, high conversions (91–99%) were observed due to a lactonization process. Both strategies are convenient from both synthetic and atom economy points of view in the production of valuable optically active products.
In previous works, many authors have widely used mass consistent models for wind field simulation by the finite element method. On one hand, we have developed a 3-D mass consistent model by using tetrahedral meshes which are simultaneously adapted to complex orography and to terrain roughness length. In addition, we have included a local refinement strategy around several measurement or control points, significant contours, as for example shorelines, or numerical solution singularities. On the other hand, we have developed a 2.5-D model for simulating the wind velocity in a 3-D domain in terms of the terrain elevation, the surface temperature and the meteorological wind, which is consider as an averaged wind on vertical boundaries. Using the meteorological wind as datum, the 2.5-D model provides a 3-D local wind modified by topography and thermal gradients on the surface by solving only a 2-D optimal control problem where the boundary condition is the control. In this case, the finite element discretization consists on a triangular mesh adapted to the terrain topography and roughness length. In both models, the wind field adjusts to several wind speed measurements at several points in the 3-D domain and eventually to an average wind flux on the boundary.In this paper we introduce several advances in the 2.5-D and 3-D wind models and we compare their results on a region located in the Province of Lugo (Spain) with realistic data that have been provided by the company Desarrollos Eólicos S.A. (DESA). In order to obtain the best adjustment of models results to the measurements, the main parameters governing the models are estimated by using genetic algorithms with a parallel implementation. 相似文献
A method for the determination of the intrinsic electrocatalytic activity of metal nanoparticles for reactions under mixed diffusion-activation control is proposed. The working electrode consists of a nanoparticle array supported on a rotating disc of an inert conducting substrate. This electrode configuration reduces significantly the contribution of the reactant diffusion to the experimental current-potential curves and consequently, the kinetic parameters of the reaction can be evaluated more accurately. A model was developed for the diffusion process in the proposed configuration, which includes a parameter related to the degree of dispersion of the nanoparticles on the electrode surface (active area factor). It allows one to evaluate changes in the current-potential plot under conditions of constant particle diameter, which is essential for the appropriate analysis of the electrocatalytic activity of nanoparticles. On this basis the dependences of the current and current density for the hydrogen oxidation reaction on overpotential, rotation rate, particle size and active area factor were derived. The validity of these expressions was verified through the analysis of experimental results. 相似文献
Gelatin obtained from giant squid (Dosidicus gigas) inner and outer tunics was hydrolyzed by seven commercial proteases (Protamex, Trypsin, Neutrase, Savinase, NS37005, Esperase and Alcalase) to produce bioactive hydrolysates. The Alcalase hydrolysate was the most potent angiotensin-converting enzyme (ACE) inhibitor (IC50 = 0.34 mg/mL) while the Esperase hydrolysate showed the highest cytotoxic effect on cancer cells, with IC50 values of 0.13 and 0.10 mg/mL for MCF-7 (human breast carcinoma) and U87 (glioma) cell lines, respectively. The radical scavenging capacity of gelatin increased approximately 3-fold for Protamex, Neutrase and NS37005 hydrolysates and between 7 and 10-fold for Trypsin, Savinase, Esperase and Alcalase hydrolysates. Trypsin, Savinase, Esperase and Alcalase hydrolysates had a metal chelating capacity above 80% whereas Protamex, Neutrase and NS37005 hydrolysates registered less than 25%. The antioxidant activity measured by FRAP (ferric ion reducing power) was largely unaffected by the enzyme used, increasing approximately 2-fold for all hydrolysates. The most active hydrolysates (Alcalase and Esperase) were comprised mostly of peptides with molecular weights ranging from 500 to 1400 Da, however, a clear relationship between bioactive properties and molecular weight distribution of all the hydrolysates was not fully established. 相似文献
Microbiological, rheological and chemical characteristics were examined in gels made from the muscle of blue whiting (Micromesistius poutassou) and subjected to three different combinations of pressure, temperature and time: 200 MPa at 3 °C for 10 min (lot L), 375
MPa at 38 °C for 20 min (lot H) and atmospheric pressure at 37 °C for 30 min followed by 90 °C for 50 min (lot T), and
kept in chilled storage for 20 days. The microorganism content dropped at the outset as pressurizing took effect, the highest
microbial content being found in lot L; however as the effect was not lethal, the total load increased over the following
days. Microbial load was significantly lower in lot T. During chilled storage, the values of breaking deformation, breaking
force and cohesiveness of lot L were higher than those of the other lots, although they did decrease with storage. The heat-induced
gel was much harder, had greater water-holding capacity and was considerably more stable than the high-pressure-induced gels.
The lightness value was higher in lot H than in the other two lots. In general, changes in protein solubility tended towards
the cleavage of strong bonds as a result of microbial action. The electrophoretic profiles evolved differently in each of
the lots over the chilled storage period. However, all of them exhibited large numbers of bands of lower molecular mass which
could have been the result of degradation. This was particularly evident in lot H. The heat-induced gels exhibited a highly
porous ultrastructure, quite different from the high-pressure-induced gels; these had a more compact matrix which expanded
as storage progressed.
Received: 26 May 1997 相似文献