Concave utility, transaction costs, and risk in measuring discounting of delayed rewards.

Research has consistently found that the decline in the present values of delayed rewards as delay increases is better fit by hyperbolic than by exponential delay-discounting functions. However, concave utility, transaction costs, and risk each could produce hyperbolic-looking data, even when the underlying discounting function is exponential. In Experiments 1 (N=45) and 2 (N=103), participants placed bids indicating their present values of real future monetary rewards in computer-based 2nd-price auctions. Both experiments suggest that utility is not sufficiently concave to account for the superior fit of hyperbolic functions. Experiment 2 provided no evidence that the effects of transaction costs and risk are large enough to account for the superior fit of hyperbolic functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emulgierf?higkeit von ?thylestern des Sonnenblumenpektins

Zusammenfassung Es wurde nachgewiesen, daß die untersuchten Äthylester (Äthylpektine) wesentlich bessere Emulgiereigenschaften als das Ausgangs-Sonnenblumenpektin haben. Die Dispersität und die Viscosität der Emulsionen erhöht sich mit der Konzentration der Äthylpektine und der Ölphase. Die Stabilität der Emulsionen wird bei steigender Konzentration von Äthylpektin und Ölphase verbessert. Es wurde festgestellt, daß die Emulgierfähigkeiten von Äthylestern des Sonnenblumenpektins auch vom Veresterungsgrad abhängen. Die besten Ergebnisse erzielt man mit Derivaten, die einen Veresterungsgrad von etwa 65% haben.

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Emulsifying properties of ethylesters of sunflower pectin

Summary It has been shown that the studied ethylesters (ethylpectins) have far better emulsifying properties than the initial sunflower pectin.The dispersity, viscosity and stability of the emulsions increase with increasing concentration of the ethylpectins and the oily phase. It has been found that the emulsifying properties of ethylesters of the sunflower pectin depend also on the degree of esterification. Best results are achieved with derivatives which have a degree of esterification of about 65%.

     

Thermal and electrical properties of nitrile‐containing polyimide/BaTiO3 composite films

Polyimide composite films were prepared by mixing the BaTiO₃ particles into poly(amic acid) solution followed by film casting and thermal imidization under controlled temperature conditions. The poly(amic acid) was synthesized by solution polycondensation reaction of 4,4′‐oxydiphthalic anhydride with 2,6‐bis(4‐aminophenoxy)benzonitrile, using N‐methyl‐2‐pyrrolidone as solvent. The surface of BaTiO₃ particles was modified by treating with an aminosilane coupling agent, 3‐aminopropyltriethoxysilane. Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy were used to characterize the structure and properties of the composites. The influence of BaTiO₃ content on the composite film properties was evidenced. The films exhibited good thermal stability having the initial decomposition temperature above 520°C. They had stable dielectric properties over large intervals of temperature and frequency. The dielectric constant and the dielectric loss increased with the increase of BaTiO₃ content. The dynamic mechanical analysis and dielectric spectroscopy revealed subglass transitions γ and β. At higher temperature an α‐relaxation that corresponds to the glass transition and a conductivity process were evidenced. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Mineral migration from stainless steel, cast iron and soapstone (steatite) Brazilian pans to food preparations

Culinary utensils may release some inorganic elements during food preparation. Mineral migration can be beneficial for as long as it occurs in amounts adequate to the needs of the consumer or no toxicological implications are involved. In this study, the migrations of Fe, Mg, Mn, Cr, Ni and Ca, along seven cooking cycles were evaluated for two food preparations (polished rice and commercial tomato sauce, the latter as an acid food), performed in unused stainless steel, cast iron and soapstone pans, taking refractory glass as a blank. Minerals were determined by inductively coupled plasma optical emission spectrometry (ICP OES). The utensils studied exhibited different rates, patterns and variability of migration depending on the type of food. Regression analysis of the data revealed that, as a function of the number of cycles, the iron pans released increasing amounts of iron when tomato sauce was cooked (y = 70.76x + 276.75; R2 = 0.77). The soapstone pans released calcium (35 and 26 mg/kg), magnesium (25 and 15 mg/kg) into the tomato sauce and rice preparations, respectively. Additionally, the commercial tomato sauce drew manganese (3.9 and 0.6 mg/kg) and some undesirable nickel (1.0 mg/kg) from the soapstone material, whereas the stainless steel pans released nickel at a lower rate than steatite and in a diminishing fashion with the number o cooking cycles, while still transferring some iron and chromium to the food. We conclude that while cast iron and glass could be best for the consumer's nutritional health, stainless steel and steatite can be used with relatively low risk, provided acid foods are not routinely prepared in those materials.     

Polysiloxane‐lignin composites

A series of composites based on polydimethylsiloxane‐α,ω‐diol (PDMS) as polymeric matrix, silica aerogel as reinforcing filler, and the lignin powder—a biomass derivative, as bulking filler, have been prepared. Different weight ratios between components were used. The composites were investigated by scanning electron microscopy, dynamic mechanical analysis, tensile strength tests, X‐ray diffraction analysis, thermogravimetric analysis, and differential scanning calorimetry. The results were compared with those obtained on a reference sample prepared by using a classical material—diatomite and a pure crosslinked PDMS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of propellant on the combustion synthesized Sr-doped LaMnO3 powders

Lanthanum strontium manganite (LSM) powders of composition La_0.7Sr_0.3MnO₃ are good candidates for cathode application in solid oxide fuel cells. This paper reports the synthesis of LSM powders from nitrate precursors by the combustion method, using two different propellants (urea and glycine) and varying the propellant/nitrate ratio. Thermogravimetric analysis (TGA) revealed two or three decomposition stages of the as-synthesized samples, with complete burn out of organics at about 850–900 °C. X-ray diffraction (XRD) patterns showed formation of only LSM phase for the sample synthesized with excess of urea, whereas SrCO₃ and MnCO₃ phases were also found for the samples prepared from glycine. The powder is better crystallized when a homogeneous gel is formed before burning. The crystallite size calculated using the Scherrer equation is in the range of 15–20 nm. Scanning electron microscopy (SEM) revealed the presence of agglomerates, formed by fine particles of different shapes.     

In situ Spinel Expansion Design by Colloidal Alumina Suspension Addition

The incorporation of nano powders into refractory castables it is not a straightforward procedure, due to their agglomeration and sintering drawbacks. Considering the alumina grain size effect on the in situ spinel formation and the associated overall volumetric expansion, alumina–magnesia refractory castables containing different alumina sources were evaluated by the assisted sintering technique. Reducing the size of fine tabular alumina (<200 μm) led to lower expansion levels, indicating the main role of alumina grain size in this property. Regarding the reactive aluminas (nano alumina powder, hydratable alumina, and colloidal alumina), the composition containing colloidal alumina performed remarkably better, leading to the lowest in situ spinel expansion level as a consequence of its high sinterability. The use of nano scaled alumina suspensions was the most suitable alternative to inhibit the shortcoming of nano powder agglomeration. Conversely, the castable containing the nano alumina powder did not behave as expected. The present work pointed out that the use of nano powders in refractory castables is only feasible if the compound is fully dispersed. Otherwise, cheaper raw materials could provide even better results than those of nano agglomerated powders.     

Investigation of the morphological changes promoted by heating of Si–C–O ceramics derived from a phenyl-rich hybrid polymer. Effect of Ni in the polymeric precursor

This study focuses on the structural and morphological changes promoted by heating of silicon oxycarbide ceramics obtained from hybrid polymeric precursors based on poly(methylsiloxane) and divinylbenzene, with or without nickel acetate, by pyrolysis under Ar at different temperatures. The increase of the temperature from 950 to 1500 °C promoted the densification and crystallization of SiC and graphite nanodomains in the ceramic bulk with or without Ni, as identified by HRTEM. Moreover, the Ni-containing precursor led to the formation of ultra-long amorphous nanowires on the surface and voids in the ceramic body obtained at 1500 °C. These nanowires presented different sizes and morphologies, but similar compositions, basically composed by silicon and oxygen, with the presence of carbon at their external layers. The growth mechanism and the nature of the nanowires are also proposed. The addition of nickel acetate in the polymeric precursor induced the formation of nanowires with different morphologies in the Si–O–C system.     

Nonstarter lactobacilli isolated from soft and semihard Argentinean cheeses: genetic characterization and resistance to biological barriers

Nonstarter lactic acid bacteria isolated from Argentinean cheeses were identified and characterized by focusing on their resistance to biological barriers, along with other physiological features of potential interest, in the search for future probiotic organisms. Lactobacilli were enumerated and isolated from semihard and soft cheeses made with multistrain Streptococcus thermophilus starters. Lactobacilli counts in 1-week-old cheeses were between 10(5) and 10(7) CFU/g and then reached 10(7) CFU/ g in all 1-month samples, while streptococci were always above 10(9) CFU/g. A total number of 22 lactobacilli isolates were retained, identified, and characterized by in vitro tests. Species identity was determined by carbohydrate metabolism and species-specific PCR assays. Genetic diversity was explored by random amplified polymorphic DNA (RAPD) PCR analysis. The Lactobacillus strains were assigned to the species L. casei, L. plantarum, L. rhamnosus, L. curvatus, L. fermentum, and L. perolens. All the strains studied tolerated 25 ppm of lysozyme, and most of them showed resistance to 0.3% bile. After incubation in gastric solution (pH 2.0), counts decreased by several log units, ranging from 3.2 to 7.0. The strains were able to grow in the presence of bile salts, but only three isolates were capable of deconjugation. The nonstarter lactobacilli that were assayed fermented the prebiotic substrates (especially lactulose and inulin). Some strains showed high cell hydrophobicity and beta-galactosidase activity, as well as inhibitory activity against pathogenic bacteria. It was concluded that most of the lactobacilli isolated in this study demonstrated resistance to biological barriers and physiological characteristics compatible with probiotic properties, which make them suitable for further research in in vivo studies aimed at identifying new probiotic organisms.     

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Frontiers of Mechanical Engineering - In recent years, the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material...