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991.
Ulises Morales-Ortiz Alejandro Avila-García V. Hugo Lara C. 《Solar Energy Materials & Solar Cells》2006,90(6):832-840
Although commercial selective surfaces are already available, investigation on different deposition methods and materials still goes on at many laboratories. In this work, ruthenium oxide films upon metallic substrates are assessed for this usage. Deposition of the films was made at room temperature by either spraying or dipping method in a ruthenium chloride alcoholic solution. After deposited on titanium substrates, the films were heat-treated at temperatures between 450 and 500 °C. When deposited on no-polished substrates, such films not only exhibit a high solar absorptance (α0.98), but also a high infrared emittance (ε0.8), which yield a low selectivity (S=α/ε=1.2). By deposition of similar films on polished substrates, absorptance decreases (α0.74), but emittance significantly decreases as well (ε0.12), resulting in a net selectivity increase (S6). On the other hand, evaporating a thin (20 nm) gold film upon the surface of a coating on a no-polished substrate also improves noticeably its emittance value (ε0.16) and a lower decrease in absorptance is achieved (α0.91), resulting in a selectivity increase (S5.7). These preliminary promising results indicate the high potential for using these films as solar selective coatings, but in order to optimize such selectivity values, further work to establish a close control on the deposition parameters and the substrate roughness value, should be done. 相似文献
992.
We consider a semilinear transmission problem for a coupling of an elastic and a thermoelastic material. The heat conduction is modeled by Cattaneo's law removing the physical paradox of infinite propagation speed of signals. The damped, totally hyperbolic system is shown to be exponentially stable, and the existence of a global attractor is shown. 相似文献
993.
994.
Hugo R. Fernandes Dilshat U. Tulyaganov José M. F. Ferreira 《Journal of Materials Science》2013,48(2):765-773
The aim of this study was to investigate the effects of different nucleating agents (P2O5, TiO2 and ZrO2) on the crystallization behaviour and the properties of a parent glass with composition 23.7 Li2O–2.63 K2O–2.63 Al2O3–71.78 SiO2 (mol%) and SiO2/Li2O molar ratio far beyond that of stoichiometric lithium disilicate (LD, Li2Si2O5). The scanning electron microscopy examination of the as-cast non-annealed glasses revealed the occurrence of liquid–liquid phase separation for all the compositions. P2O5 revealed to be effective in promoting bulk crystallization of LD, while TiO2 and ZrO2 led to surface crystallization. Moreover, ZrO2 enhances the glass polymerization and shifts T p to higher temperatures, hindering crystallization. At 900 °C, TiO2-containing glasses feature LD and lithium metasilicate (LMS, Li2SiO3), while P2O5- and ZrO2-containing ones present monophasic LD and LMS glass–ceramics, respectively. 相似文献
995.
A study on the isothermal crystallization of water in aqueous solutions of poly(vinyl methyl ether) (PVME) was carried out by the differential scanning calorimetry (DSC). The influence of PVME concentration (49.5, 44.5 and 39.5 v%) and the crystallization temperature (Tc) on crystallization rate G, crystallization enthalpy (ΔHc) and melting enthalpy (ΔHm) was investigated. Avrami equation cannot be used to describe the crystallization process of water in aqueous PVME solution. Within the measured temperature range, the crystallization rate G increases with the crystallization temperature Tc and with the decreasing PVME content. The crystallization enthalpy ΔHc linearly increases with the degree of supercooling. The influence of Tc on the ΔHc becomes more marked with increasing PVME concentration. For 49.5 and 44.5 v% PVME solutions, the amount of water arrested in solution during the isothermal crystallization and the final concentration of PVME-rich phase increase linearly with the Tc, whereas for 39.5 v% PVME solution, these two values almost do not change with Tc. The amount of frozen water in the subsequent cold crystallization is approximately proportional to the initial Tc. The approximately constant ΔHm for a given concentration at the different initial isothermal crystallization temperatures suggests that the total amount of ice from the first isothermal crystallization and the second cold crystallization is same. The quantitative relation of the amount of frozen water in the cold crystallization and the initial Tc demonstrates that PVME/water complexes are thermodynamically unstable. 相似文献
996.
997.
Effect of cooking on physicochemical and structural properties of jumbo squid (Dosidicus gigas) muscle 下载免费PDF全文
998.
Ferro CA Jupp TE Lambert FH Huntingford C Cox PM 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2012,370(1962):1087-1099
A perennial question in modern weather forecasting and climate prediction is whether to invest resources in more complex numerical models or in larger ensembles of simulations. If this question is to be addressed quantitatively, then information is needed about how changes in model complexity and ensemble size will affect predictive performance. Information about the effects of ensemble size is often available, but information about the effects of model complexity is much rarer. An illustration is provided of the sort of analysis that might be conducted for the simplified case in which model complexity is judged in terms of grid resolution and ensemble members are constructed only by perturbing their initial conditions. The effects of resolution and ensemble size on the performance of climate simulations are described with a simple mathematical model, which is then used to define an optimal allocation of computational resources for a range of hypothetical prediction problems. The optimal resolution and ensemble size both increase with available resources, but their respective rates of increase depend on the values of two parameters that can be determined from a small number of simulations. The potential for such analyses to guide future investment decisions in climate prediction is discussed. 相似文献
999.
Hugo Cortina Claudia Martínez-Alonso Mónica Castillo-Ortega Hailin Hu 《Materials Science and Engineering: B》2012,177(16):1491-1496
In this work cellulose acetate (CA) fibers with a diameter of approximately 1 μm were immersed in a cadmium sulfide (CdS) precursor solution. After 3 h the original white color CA fibers became yellow and maintained the same form, suggesting the deposition of CdS on fiber surface. SEM images showed that CA fibers were covered by uniformly sized CdS nanoparticles of approximately 100 nm. XRD and optical absorption spectra indicated that they contained mostly cubic crystalline phase with the optical band gap of 2.43 eV. CdS coated CA fibers, called CdS(CA) fibers, were dispersed in a polar dispersant (dimethyl sulfoxide, DMSO) and then mixed with a poly(3-hexylthiophene) (P3HT) solution in a non-polar solvent (dichlorobenzene, DCB). The mixture was cast onto a transparent conductive glass substrate (Indium–Tin–Oxide, ITO), and after solvent evaporation a thin layer of CdS(CA)–P3HT composite was formed. It is observed that the volume relation between the polar dispersant and non-polar solvent influences the solubility of the P3HT product in the composite coating and the photovoltaic performance of the corresponding cell as well. The mass ratio between CdS(CA) fibers and P3HT in the composite layer affects the optical absorption of the composite. The best photovoltaic performance was obtained in CdS(CA)–P3HT based cells with a volume relation between DCB and DMSO of 3.5–1, a mass ratio between CdS(CA) and P3HT of 1:1, and a rapid drying process for composite coatings. 相似文献
1000.
Dimitra Mastorakou Angelica Ruark Hugo Weenen Bernd Stahl Markus Stieger 《Journal of dairy science》2019,102(2):1116-1130
It is unknown how consumption of bitter foods and beverages in the maternal diet influences sensory properties of fresh human milk. The aims of this study were (1) to determine the sensory characteristics of fresh human fore and hind milk, (2) to establish relationships between sensory properties and composition of fresh human milk, and (3) to assess the relationship between bitterness of the maternal diet and human milk. Twenty-two lactating mothers generated sensory terms to describe perception of their milk and received training on sensory attribute intensity rating. Mothers kept a 24-h food diary followed by a sensory self-assessment of their fore and hind milks. The odor of human fresh milk was described as neutral, creamy, and sweet, taste as sweet and bitter, and mouthfeel as thin, watery, smooth, and fatty. Sweetness was equivalent to 1.53 g of sucrose/100 mL and was not significantly different between fore and hind milk. Fore milk was significantly less creamy, less fatty, thinner, more watery, and lower in vanilla flavor intensity than hind milk. Carbohydrate content of human milk was positively correlated with sweetness and glutamic acid content with umami. The bitterness of the diet consumed 24 h before lactation was moderately positively correlated with bitterness of fore milk, but not hind milk. We conclude that the consumption of bitter foods may influence the bitterness of human fore milk, which may be another way for?breastfed children to learn to accept bitter vegetables and, hence, develop healthier food preferences. 相似文献