Synthesis of Highly Porous Yttria-Stabilized Zirconia by Tape-Casting Methods

Porous ceramics of Y₂O₃-stabilized ZrO₂ (YSZ) were prepared by tape-casting methods using both pyrolyzable pore formers and NiO followed by acid leaching. The porosity of YSZ wafers increased in a regular manner with the mass of graphite or polymethyl methacrylate (PMMA) to between 60% and 75% porosity. SEM indicated that the shape of the pores in the final ceramic was related to the shape of the pore formers, so that the pore size and microstructure of YSZ wafers could be controlled by the choice of pore former. Dilatometry measurements showed that measurable shrinkage started at 1300 K, and a total shrinkage of 26% was observed, independent of the amount or type of pore former used. Temperature-programmed oxidation (TPO) measurements on the green tapes demonstrated that the binders and dispersants were combusted between 550 and 750 K, that PMMA decomposed to methyl methacrylate between 500 and 700 K, and that graphite combusted above 900 K. The porosity of YSZ ceramics prepared by acid leaching of nickel from NiO–YSZ, with 50 wt% NiO, was studied as a function of NiO and YSZ particle size. Significant changes in pore dimension were found when NiO particle size was changed.     

Versatile Nanocomposite Coatings with Tunable Cell Adhesion and Bactericidity

TiO₂‐Ag nanocomposites are known for their bactericidal effect during exposure to appropriate UV radiation. While involving hazardous radiation, and limited to accessible areas, the bactericidity of these coatings is not persistent in the absence of UV light, which impedes their commercial application. Herein it is shown that TiO₂‐Ag nanocomposites can be made highly bactericidal without the need of irradiation. Beyond this, bactericidity can even be mitigated in the presence of pre‐irradiated coatings. Biocompatibility and cell adhesion are also negligibly small for the as‐processed, non‐irradiated coatings, and become fairly high when the coatings are irradiated prior to testing. This opens the possibility to pattern the coatings into areas with high and low cell adhesion properties. Indeed by irradiating the coating through a mechanical mask it is shown that fibroblast cell adherence is sharply confined to the irradiated area. These properties are achieved using TiO₂‐Ag thin films with high silver loadings of 50 wt%. The films are processed on stainless steel substrates using solution deposition. Microstructural characterization by means of X‐ray diffraction, Raman, and X‐ray photoelectron spectroscopy, high‐resolution scanning electron microscopy, and atomic force microscopy show a highly amorphous TiO₂‐Ag_xO nanocomposite matrix with scattered silver nanoparticles. UV irradiation of the films results in the precipitation of a high density of silver nanoparticles at the film surface. Bactericidal properties of the films are tested on α‐haemolyzing streptococci and in‐vitro biocompatibility is assessed on primary human fibroblast cultures. The results mentioned above as to the tunable bactericidity and biocompatibility of the TiO₂‐Ag coatings developed herein, are amenable to silver ion release, to catalytic effects of silver nanoparticles, and to specific wettabilities of the surfaces.     

Improved Lead—acid Cells Employing Tin Oxide Coated Dynel Fibres with Positive Active-Material

A rapid-thermally-activated chemical reaction process has been employed to coat tin oxide onto Dynel fibres. Positive-limited 2 V/1.5 Ah lead-acid cells employing tin-oxide coated Dynel fibres as additive to positive active mass have been assembled and characterized under various operational conditions. In this manner, it has been possible to improve the positive active material utilization and particularly at higher discharge rates.     

Fathers' participation in family research: Is there a self-selection bias?

The representativeness of fathers who participate in family research was examined among 661 families. Approximately two thirds of eligible fathers participated. Mothers' and observers' reports on families of participating and nonparticipating fathers were compared. Participating fathers underrepresented fathers with less education, later-born children, more ambivalent marriages, partners with more traditional child-rearing beliefs, families with less optimal parenting environments, and infants who were unplanned, had more difficult temperaments, and were less healthy. Also underrepresented were ethnic minority families and working-class fathers. However, no differences were found in regard to child gender, family income, mothers' psychosocial functioning, either parent's employment experiences, or child-care arrangements. Implications for the generalizability of findings and the recruitment of fathers are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New vinyl ester monomers for emulsion polymers

New vinyl ester monomers are now available for the preparation of emulsion copolymers with improved hydrolytic stability and water resistance. These improved properties are the result of uniform copolymerization of hydrophobic monomers having approximately the same reactivity as vinyl acetate. Latex coatings with excellent gloss, water spot resistance, blocking and other desirable performance properties can now be obtained with vinyl acetate copolymers.     

Reducing air-pollution: A new argument for getting drivers to abide by the speed limit?

Speeding is one of the main factors of car crash-risk, but it also contributes to increasing air-pollution. In two studies we attempted to lead drivers to abide by speed limits using “reducing air-pollution” as a new argument. We presented prevention messages that highlighted the role of speeding in increasing “crash-risk”, “air-pollution”, or both (Studies 1 and 2). The messages were also positively or negatively framed (Study 2). Given that women are more concerned with environmental issues than are men, we expected the following hypotheses to be validated for women. The message with the “air-pollution” argument was expected to be evaluated more positively than the “crash-risk” message (H1). The “air-pollution” and “crash-risk and air-pollution” messages were expected to be more effective than the “crash-risk” message on the behavioral intention to observe speed limits (H2a) and on the perceived efficacy of speed-limit observance in reducing air-pollution (H2b; Studies 1 and 2). Furthermore, positive framing was expected to be more effective than negative framing (H3), and presenting a message to be more effective than presenting no message (H4; Study 2).Broadly, our results argue in favor of our hypotheses. However in Study 2, the effects of message framing did not allow us to conclude that negative or positive framing was superior. All in all, messages with the “air-pollution” argument were more effective at leading drivers to observe speed limits. Thus, environmental protection may be a fruitful route to explore for increasing road safety.     

Effect of timing of dialysis on mortality in critically ill, septic patients with acute renal failure

Acute renal failure with concomitant sepsis in the intensive care unit is associated with significant mortality. The purpose of this study was to determine if the timing of initiation of renal replacement therapy (RRT) in septic patients had an effect on the 28-day mortality. Retrospective data on medical intensive care unit patients with sepsis and acute renal failure requiring RRT were included. Renal replacement therapy started with a blood urea nitrogen (BUN) of <100 mg/dL was defined as early initiation, and initiation with a BUN ≥100 mg/dL was defined as late. Multivariate logistic regression analysis with the primary outcome of death at 14, 28, and 365 days following the initiation of RRT was performed. One hundred thirty patients were studied. The early dialysis (mean BUN 66 mg/dL) group had 85 patients; the late group (mean BUN 137 mg/dL) had 62 patients. The mean acute physiology and chronic health evaluation II score was 24.5 in both groups. The overall 14, 28, and 365-day survival rates were 58.1%, 41.9%, and 23.6%. Survival rates for the early group were 67%, 47.7%, and 30.7% at 14, 28, and 365 days. Survival rates for the late group were 46.7%, 31.7%, and 13.3% at 14, 28, and 365 days. Upon logistic regression analysis, initiating dialysis with a BUN >100 mg/dL predicted death at 14 days (odds ratio [OR] 3.6, 95% confidence interval [CI] 1.7–7.6, P=0.001), 28 days (OR 2.6, 95% CI 1.2–5.7, P=0.01), and 365 days (OR 3.5, 95% CI 1.2–10, P=0.02). Septic patients who started dialysis with a BUN <100 mg/dL had improved mortality rates up to 1 year after initiation of dialysis in this single-center, retrospective analysis.     

A is for apple: Mnemonic symbols hinder the interpretation of algebraic expressions.

This study examined how literal symbols affect students' understanding of algebraic expressions. Middle school students (N = 322) were randomly assigned to 1 of 3 conditions in which they were asked to interpret an expression (e.g., 4c + 3b) in a story problem. Each literal symbol represented the price of an item. In the c-and-b condition, the symbols used were the 1st letters of the items (e.g., price of a cake in dollars = c; price of a brownie in dollars = b). In the other 2 conditions, c and b were replaced with nonmnemonic English letters (x and y) or Greek letters (Φ and Ψ). Incorrect interpretations of the expression were most common among students in the c-and-b condition. Moreover, students in this condition were more likely than students in the other conditions to misinterpret the symbols as labels for objects (e.g., c stands for cake). An analysis of participating students' textbooks revealed that mnemonic symbols were used correctly and were not uncommon. Results suggest that the use of mnemonic symbols may hinder students' interpretation of algebraic expressions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of a fermented goats' milk containing Lactobacillus rhamnosus: in vivo study of health benefits

BACKGROUND: Lactobacillus rhamnosus CRL1505, a strain of goats' milk origin, is able to stimulate mucosal immunity and protect immunocompetent mice from intestinal and respiratory infections. RESULTS: In this work we developed and characterized a fermented goats' milk containing L. rhamnosus CRL1505, and we demonstrated in a model of immunosuppression in mice that the final dairy product preserves the immunomodulatory properties of the strain. L. rhamnosus CRL1505 survived the manufacturing process of fermented milk and maintained a viability of 10⁶ cfu g^?1 during storage. The fermented goats' milk was accepted by 90.48% of the panelists and was considered as having an acid taste and pleasant aroma. We also demonstrated that the developed product, used as a supplement during the repletion of immunocompromised malnourished mice, was effective in accelerating the recovery of clinical parameters altered by malnutrition and to induce increased resistance against intestinal and respiratory infections. CONCLUSION: Goats' milk fermented with L. rhamnosus CRL1505 could be manufactured as an alternative probiotic dairy product since this new food has the ability to stimulate the common mucosal immune system and to improve defenses against respiratory and intestinal infections. Copyright © 2011 Society of Chemical Industry     

Potential options to reduce GHG emissions in Venezuela

This paper presents a summary of the technologies and practices that could be implemented in Venezuela in order to contribute to both climate change mitigation and national development efforts. The mitigation analysis concentrates on options to reduce CO₂ emissions generated from the energy sector and land-use change.

From the mitigation options analyzed for the energy sector it was determined that the most effective are those in the transportation sector (switching to larger capacity vehicles, reduced private vehicle share, and switching fuels for public transportation from gasoline to natural gas), both in terms of contribution to emissions reduction and costs. Regarding the options for industry, boilers conversion from liquids to natural gas shows negative cost, but to a considerably lower extent that for the transportation sector. Efficiency improvements of natural gas boilers, which presents close to zero cost, is more effective in reducing emissions than boiler conversion. Increase in hydro power generation is the alternative with the highest total cost but it is very effective in reducing emissions.

From the mitigation options analyzed for land-use change, it was established that the forest sector has a considerable potential for reducing CO₂ emissions through the adoption of sustainable forest practices, especially by slowing the rate of forest loss and degradation. Maintenance of already existing biomass in natural forests should be the first priority of forest measures to reduce the amount of carbon released to the atmosphere. Forest protection and management of native forest represent the two options with the highest carbon conservation potential and the lowest carbon unit cost. Expansion of the forest cover through the development of intensive forest plantations also presents a high potential to offset carbon emissions in Venezuela.

An analysis of the barriers to mitigation options implementation shows that in the energy sector, low energy prices represent the main barrier to any mitigation program. Another important limitation to mitigation strategies implementation is the lack of institutional capacity and legal instruments for developing the mitigation measures. In the forest sector the primary causes of forest clearing in the country are not related to forest activities, so the definition of feasible mitigation options will depend upon a good understanding of other economic sectors and how they account for land-use change. Land tenure, rural poverty, political interests, and weak implementation of land-use planning instruments and environmental laws are considered to be the key limitations to any effort dealing with forest conservation. Land tenure, economic factors, and lack of incentives represent some of the most important barriers to the development of forest plantations and agroforestry systems in the country.