Thermal aging of Pd/Pt/Rh automotive catalysts under a cycled oxidizing–reducing environment

Mono- and multi-metallic (bi- and tri-) Pt, Pd and Rh supported on cerium-promoted alumina (La Roche, SAS-1/16) catalysts were tested for activity as TWC, both fresh [G.C. Koltsakis, and A.M. Stamatelos, Progr. Energy Combust. Sci. 23 (1997) 1] and after accelerated aging. Aging consisted of a treatment at 900°C for 5 h during which an oxidizing (2.5% O₂, 10% H₂O, in N₂) and a reducing (5.0% CO, 10% H₂O, in N₂) feedstream were cycled at 0.017 Hz through the catalyst. Activity tests were carried out by increasing temperature from 100 to 600°C at 3°C min⁻¹, while two oxidizing and reducing (±0.5 A/F) feedstreams were alternately (1 Hz) fed through the reactor at 125 000 h⁻¹ (STP). Conversion was continuously analyzed. Light-off temperature, T₅₀, conversion at 500°C (normal running temperature), X₅₀₀, and the stoichiometric window (A/F from 14.13 to 15.13) for stationary feedstreams, were determined.     

Mental health professionals' adaptive responses to racial microaggressions: An exploratory study.

This study examines adaptive responses that mental health professionals of color use to cope with racial microaggressions in their professional lives. Twenty-four mental health professionals from diverse ethnic backgrounds in the United States and Canada participated in focus groups discussing their experiences with racial microagressions and how they cope with them. Results of the analysis indicated that 8 primary coping themes illustrated strategies used by the participants. These include: identifying key issues in responding to racial microaggressions, self-care, spirituality, confrontation, support, documentation, mentoring, and collective organizing. Suggestions for mentoring professionals of color are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of phenoloxidase activity of carapace and viscera from cephalothorax of Norway lobster (Nephrops norvegicus)

The characterization of phenoloxidase activity was performed in both carapace and viscera extracts of Norway lobster. Phenoloxidase activity rose with increasing temperature up to 60 °C. The carapace enzymatic extract showed the highest themostability, retaining about 80% of maximum activity at 45 °C and 40% at 65 °C. On the other hand, both enzymatic extracts showed a single peak activity at neutral-slightly alkaline pH and were quite resistant to inactivation at alkaline pH (pH > 8), but phenoloxidase activity became unstable at pH lower than 5.5. The enzymatic extract obtained from viscera showed a higher affinity for catechol (K_M 5.97 mM) than carapace extract (K_M 19.40 mM). Both mono- and diphenoloxidase activities were found in carapace and viscera. Polyphenoloxidase and converted-hemocyanin into PPO-like enzyme could be the main responsible for these activities.     

Reinforcing effect of a kaolin surface-treated with diallyldimethylammonium in SBR vulcanizates

This paper examines the physico-chemical characteristics of a natural kaolin, its textural properties, pores, morphology, chemical surface, as well as chemical surface modification through treatment with quaternary ammonium salts in SBR mixes. Diallyldimethylammonium chloride was used as a quaternary alkali for surface modification of the kaolin, thus allowing the unsaturated allyl portion to covulcanize with the rubber. This achieved strong rubber-filler bonds with consequential enhancement of the technological properties of the vulcanizate.     

Response surface methodology multivariate analysis of properties of high-pressure-induced fish mince gel

 Factorial analyses were performed to determine the effect of high-pressure treatment on the characteristics of blue whiting mince of good gel-forming quality. Pressure, time and temperature independently influenced gel characteristics. Temperature had the greatest influence of the three. High-pressure gels were generally distinguished by lower adhesiveness, higher water-holding capacity and less yellowness than heat-induced gels. The combination of pressure and temperature produced more elastic gels, whereas gels made under high pressure at chilling temperatures were much harder, more deformable and more cohesive. There was no correlation between elasticity and deformability.     

Effects of a citrus based juice on biomarkers of oxidative stress in metabolic syndrome patients

Bioactive substances found in numerous foods can be successfully and safely used to modify various cellular functions and affect the oxidative stress. The aim of this study was to analyze the effect of a citrus-based juice (juice citrus (95%) with 5% of aronia extract (Aronia melanocarpa)) on biomarkers of oxidative stress in patients with metabolic syndrome compared with healthy individuals. The study comprised 20 healthy subjects and 33 patients with metabolic syndrome. Eighteen patients consumed daily 300 mL of a citrus-based juice during 6 months and 15 patients consumed 300 mL of a placebo beverage. The control group consumed a citrus-based juice (CJ). Before, and at sixth months after consuming of a citrus-based juice the following parameters were determined: 15-isoprostane F₂, 8-hydroxydeoxyguanosine (8-OHdG), reduced and oxidized glutathione (GSH/GSSH), carbonyl groups and oxidized LDL (ox-LDL). After consuming CJ during 6 months the values of 8-OHdG, carbonyl groups and LDL-ox decreased in both analyzed groups and the values of GSH/GSSH increased. Significant differences were observed in both groups. Thus consumption of citrus-based juice improved the biomarkers of oxidative stress in metabolic syndrome patients.     

On the Effect of Reduction and Ageing on the TWC Activity of Pt/Ce0.68Zr0.32O2 under Simulated Automotive Exhausts

The three-way activity under complex feed-streams of a series of Pt/Ce_0.68Zr_0.32O₂ catalysts, either fresh or submitted to different ageing treatments, both before and after reduction, has been studied and related to the species present on the catalysts in view of their characteristics and TPR behaviour.     

Adhesion of Listeria monocytogenes to materials commonly found in domestic kitchens

The aim of this work was to investigate the adhesion of Listeria monocytogenes ATCC 15313 to glass, granite, marble, polypropylene from a bowl (PPb), polypropylene from a cutting board (PPcb) and stainless steel (SS), which are materials commonly used in kitchens. Marble and granite were chosen because they are applied as kitchen bench covers and pavements in many countries and there are no literature reports on their behaviour in terms of microbial adhesion. The effect of surface hydrophobicity and roughness on the adhesion process was also analysed. The results showed that the highest extent of adhesion of L. monocytogenes occurred to stainless steel, followed by glass and in less extent to the other materials studied. However, it was not possible to establish a correlation between surface hydrophobicity or roughness and the extent of adhesion of L. monocytogenes . The adherence of L. monocytogenes should be dependent on other factors, like the presence of exopolymers and surface charge.     

Albumin causes a synergistic increase in the antioxidant activity of green tea catechins in oil-in-water emulsions

Model oil-in-water emulsions containing epicatechin (EC) and epigallocatechin gallate (EGCG) showed a synergistic increase in stability in emulsions containing added albumin. EGCG showed a stronger synergy (35%) with ovalbumin than did EC. Oxidation of the oil was monitored by determining peroxide values and hexanal contents. The effect of bovine serum albumin (BSA) on model oil-in-water emulsions containing each of the green tea catechins [epicatechin gallate (ECG), EGCG, EC and epigallocatechin (EGC)] was studied during storage at 30 °C. The green tea catechins showed moderate antioxidant activity in the emulsions with the order of activity being ECG ≈ EGCG > EC > EGC. Although BSA had very little antioxidant activity in the absence of phenolic antioxidants, the combination of BSA with each of the catechins showed strong antioxidant activity. BSA, in combination with EC, EGCG or EGC, showing the strongest antioxidant activity with good stability after 45 days storage. Model experiments with the catechins stored with BSA in aqueous solutions confirmed that protein–catechin adducts with antioxidant activity were formed between the catechins and protein. The antioxidant activity of the separated protein–catechin adducts increased strongly with storage time and was stronger for EGCG and ECG than for EC or EGC.     

Structural changes in sardine (Sardina pilchardus) muscle during iced storage: Investigation by DRIFT spectroscopy

Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy has been used for the first time to evaluate the postmortem changes in structure of components from sardine muscle in relation to quality loss. Sardines (Sardina pilchardus) were stored in ice for up to thirteen days. The spectroscopic study was focussed on the structural changes produced on the lipids and proteins.