Microstructural properties of the bulk matrix and the steel/cement paste interface in reinforced concrete,maintained in conditions of corrosion and cathodic protection

Although rarely considered, especially within the investigation of steel corrosion phenomena or electrochemical protection techniques in reinforced concrete structures, the concrete bulk matrix has a significant contribution in the global performance of the system “reinforced concrete.” This is especially the case when chloride‐induced corrosion or electrical current flow [as within impressed current cathodic protection (CP)] are involved. In the latter cases, the concrete bulk matrix undergoes significant alterations in chemical composition, electrical properties, and microstructures, thus influencing the overall performance of the system. This work reports on the microstructural investigation of the bulk concrete matrix and the steel/cement paste interface in reinforced concrete, previously subjected to corrosion and CP for 460 days. The emphasis hereby is to evaluate the altered structural properties, i.e., porosity, pore size, permeability of the bulk cement matrix, and the steel/cement paste interface (translated to bond strength) as a result of chloride‐induced corrosion and two types of CP (conventional and pulse), compared to control (non‐corroding, non‐protected) conditions. The research revealed a major contribution and close dependence of all microlevel interfaces on the global performance of reinforced concrete. The electrical current flow (as in CP applications) was found to bring about unfavorable modifications to the material structure, both in the bulk matrix (reducing porosity) and at the steel/cement paste interface (enlarging interfacial gaps). The derived microstructural parameters show that the conventional CP leads to a higher level of structural heterogeneity, whereas the pulse CP exerts minimal or no effects, maintaining the material properties close to the reference (control) conditions, the underlying mechanism being a more homogeneous material microstructure.     

Effects of acute progesterone administration upon responses to acute psychosocial stress in men.

Animal studies suggest that neuroactive steroids, in particular progesterone and its metabolites, have stress-dampening effects. However, few studies have explored these effects in humans. In this study, we investigated the effects of acute progesterone administration on responses to the Trier Social Stress Test (TSST). Healthy men participated in the TSST 3.5 hrs after intramuscular injection of 0, 50, or 100 mg progesterone (N = 16, 14, and 14). We measured cardiovascular (heart rate, blood pressure), hormonal (plasma adrenocorticotrophic hormone, cortisol, and noradrenaline), and subjective (e.g., anxiety, arousal) responses to stress in the three groups. Before the TSST, progesterone injections increased plasma levels without altering physiological or subjective states. Stress produced its expected physiological and subjective effects among placebo-treated individuals. Progesterone 50 mg attenuated peak increases in plasma cortisol and reduced changes in negative mood and alertness after stress, yet it increased plasma noradrenaline and systolic blood pressure. Progesterone 100 mg also attenuated stress-induced increases in alertness and arousal, yet it potentiated stress-induced increases in diastolic pressure. Thus, progesterone dampened some of the psychological effects of stress but produced inconsistent effects on physiological stress responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Precipitation variability in the Meuse basin in relation to atmospheric circulation.

The distribution of precipitation events in the Meuse basin during the past century has been found to reflect the large-scale atmospheric circulation, as characterised by the Grosswetterlagen system. Statistical analysis of the long observation records (1911-2002) for the basin showed that although the annual (November to October) and winter half-year (November to April) frequencies of wet days > or = 1 mm/day) were nearly stable, the associated precipitation amounts have significantly increased since 1980. From 1980 onwards, the very wet days (> or = 10 mm/day) in the winter half-year have become more frequent. No obvious change was identified for the summer half-year (May to October) very wet days. Both the precipitation amounts of wet and very wet days in the winter half-year and the occurrence of associated atmospheric circulation of the types/sub-types west cyclone, southwest cyclone and northwest cyclone showed a significant increase around 1980.     

A comparative electrochemical study of commercial and model aluminium alloy (AA5050)

A comparative electrochemical study of commercially recycled AA5050 and model AA5050, in their as‐cast state, is carried out to investigate the effect of recycling and furthermore the effect of trace elements like Pb, Cu, etc on electrochemical activation and filiform corrosion (FFC) susceptibility. A systematic combination of surface analytical techniques like scanning Kelvin probe force microscopy (SKPFM), scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) is used to study the composition and electrochemical behaviour of second phase particles. These results, together with localized breakdown measurements using the electrochemical micro‐cell, elucidate the effect of recycling and the role played by trace elements in influencing the electrochemical behaviour of the alloy.     

Glucose and sucrose fermenting capacity of homofermentative lactic acid bacteria used as starters in fermented salads.

Salads, i.e., vegetables and/or meat in an oil-in-water emulsion with a low pH due to the addition of acids, are popular in western countries. The shelf life of these salads is influenced mainly by storage temperature and the use of preservatives, i.e., sorbic and benzoic acid. Lactic acid fermentation could be an interesting novel approach to salad preparation. As part of an investigation on fermented salads, lactic acid bacteria from the genera Lactobacillus, Pediococcus and Streptococcus were screened for their capacity to ferment glucose and sucrose in a model system and in a standard salad. The temperature optimum of these strains was in the range of 34-48 degrees C. Most of these strains produced about equal amounts of L(+)- and D(-)-lactic acid. To determine the specific sugar fermenting capacity (mmol lactic acid produced per min per g dry weight) of non-growing cells of lactic acid bacteria, a semi-automated model system was used, based on monitoring the pH decrease in a phosphate buffer during conversion of sugars to lactic acid. The strains tested showed acid production rates on glucose varying between 0.03 and 0.39 mmol of acid produced per min per g dry weight (average 0.23). These glucose-grown cells showed varying, but lower fermentation rates on sucrose (0-0.25 mmol/min/g d.w., average 0.04) than sucrose-grown cells (0-0.33 mmol/min/g d.w., average 0.19). Results obtained with the model system were in good agreement with those of fermentation tests, carried out with a standard salad. Inhibition of spoilage bacteria in the standard salad could be achieved by using starter cultures with high fermenting capacity.     

Minimum inhibitory concentration (MIC) of sodium lactate for pathogens and spoilage organisms occurring in meat products

Pathogens and spoilage organisms occuring in meat products were screened in laboratory media, according to a method of Eklund (1983), in order to determine the specific inhibitory effect of lactate on growth of these microorganisms under optimum growth conditions (pH 6.5, 20°C). In general, Gram-positive bacteria were more sensitive towards lactate than Gram-negative bacteria. It was shown especially, that strains that were able to grow at water activities of 0.95 and below in the presence of NaCl (Staphylococcus aureus, Listeria monocytogenes, Brochothrix thermosphacta) were inhibited by sodium lactate (NaL). It appeared, that yeasts were resistant to large amounts of NaL (> 10% w/v). However, NaL had a specific inhibitory effect on growth of these organisms when compared to the effect of NaCl. These results indicate that lactate addition to food products with a pH near neutrality offers good prospects for shelf life prolongation.     

Charles R. (Bob) Schuster (1930–2011).

Charles R. (Bob) Schuster, an internationally recognized researcher on the psychopharmacology of drugs of abuse, passed away on February 21, 2011. Bob Schuster was a pioneer in the scientific study of addiction and one of the founders of a specialized research field called behavioral pharmacology. Bob mentored many young scientists, including 15 doctoral students, 9 postdoctoral fellows, and many visiting scientists from around the world, as well as junior faculty members at the academic institutions where he had faculty appointments. Bob was active in numerous professional organizations and was the recipient of many national and international awards. Personally, Bob Schuster touched the lives of a great many people: his students, colleagues, extended family, and many friends. Bob is survived by his wife and colleague Chris-Ellyn Johanson; four children, Lyzbett, Rebecca, Robert, and Alyson; and seven grandchildren. He is also survived by his sister Bette Quemore. He was a man of many talents, a loving husband and father, and a great friend. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Adaptive control of robot manipulators via velocity estimatedfeedback

An approach for designing robot controllers using state-space feedback is presented. The robot model parameters are assumed to be unknown and velocity measurements are assumed not to be available. This asymptotically stable control scheme combines an adaptive control law with a sliding observer and does not need additional assumptions on the variation of the inertia matrix eigenvalues. State observation and parameter adaptation are performed simultaneously. The adaptation law, the observer gains, and the control law are designed on the reduced order manifold which results from the invariance of the switching surface