The sources of normativity: Young children's awareness of the normative structure of games.

In two studies, the authors investigated 2- and 3-year-old children's awareness of the normative structure of conventional games. In the target conditions, an experimenter showed a child how to play a simple rule game. After the child and the experimenter had played for a while, a puppet came (controlled by a 2nd experimenter), asked to join in, and then performed an action that constituted a mistake in the game. In control conditions, the puppet performed the exact same action as in the experimental conditions, but the context was different such that this act did not constitute a mistake. Children's normative responses to the puppet's acts (e.g., protest, critique, or teaching) were scored. Both age groups performed more normative responses in the target than in the control conditions, but the 3-year-olds did so on a more explicit level. These studies demonstrate in a particularly strong way that even very young children have some grasp of the normative structure of conventional activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stabilization of polyacetals

A brief introduction describes the main differences between homo, and copolymer polyacetals and their main degradation mechanisms. A short overview describes the importance of stabilization and the necessity of using antioxidants and costabilizers during manufacturing, processing and end use of polyoxymethylene(polyacetals). Various stabilizer systems are presented and studies on the interaction of antioxidants with costabilizers added. The criteria for testing the performance of these additives are discussed and demonstrated by many examples. In a second part the increasing importance of light stabilized polyacetal is mentioned and investigations on the performance of light stabilizer systems are highlighted.     

Glycerolysis of Fatty Acid Methyl Esters: 1. Investigations in a Batch Reactor

The present work focused on the glycerolysis of fatty acid methyl esters. The aim was to develop and test a kinetic model that could be used to reliably simulate different process alternatives for this reaction. A prerequisite was the identification and characterization of the factors that affect the reaction kinetics. Experiments were carried out in a batch reactor with and without forced removal of methanol, which is one of the reaction products. Concentrations of all components in the two-phase system were measured. It was found that the methanol concentration has a strong effect on the reaction rate and equilibrium conversion. Near-complete conversions were obtained by stripping methanol with an inert gas. The glycerol concentration in the ester phase was found to increase as the reaction proceeds, which also accelerates the reaction. Effects of mass transfer on the reaction rate were not found to control the reaction rate under well-agitated conditions. A semi-empirical model was used to simulate the reaction. The results from the semi-empirical model show good agreement with experimental results.     

A viscosity model for technical polymers describing chemical and physical aging

Rheological techniques, like oscillating rheometry and high‐pressure capillary rheometry were used to measure and to describe chemical and physical aging influences on the rheology of polyamide and polybutylene terephthalate in an advanced viscosity model. Viscosity drop was found as cause of combined time and temperature effects and understood as chemical aging that was reduced to a thermally induced degradation. The influence of chemical aging on viscosity was described based on a novel structural change shift factor a_SC. In addition, viscosity drop was found as cause of residual moisture. Its influence was described by a novel physical change shift factor a_PC. The functional relationships for both factors were derived from measured data. Moreover, both factors contain additional parameters that were optimized with respect to specific processing and boundary conditions. The consideration of chemical and physical aging by means of a_SC and a_PC provides a better understanding with respect to rheological changes and thus a better control of process variations and an enhanced product quality. POLYM. ENG. SCI., 55:1628–1633, 2015. © 2014 Society of Plastics Engineers     

Antivitamins for Medicinal Applications

Antivitamins represent a broad class of compounds that counteract the essential effects of vitamins. The symptoms triggered by such antinutritional factors resemble those of vitamin deficiencies, but can be successfully reversed by treating patients with the intact vitamin. Despite being undesirable for healthy organisms, the toxicities of these compounds present considerable interest for biological and medicinal purposes. Indeed, antivitamins played fundamental roles in the development of pioneering antibiotic and antiproliferative drugs, such as prontosil and aminopterin. Their development and optimisation were made possible by the study, throughout the 20th century, of the vitamins' and antivitamins' functions in metabolic processes. However, even with this thorough knowledge, commercialised antivitamin‐based drugs are still nowadays limited to antagonists of vitamins B₉ and K. The antivitamin field thus still needs to be explored more intensely, in view of the outstanding therapeutic success exhibited by several antivitamin‐based medicines. Here we summarise historical achievements and discuss critically recent developments, opportunities and potential limitations of the antivitamin approach, with a special focus on antivitamins K, B₉ and B₁₂.     

Short-term exposure to the environmentally relevant estrogenic mycotoxin zearalenone impairs reproduction in fish

Zearalenone (ZON) is one of the worldwide most common mycotoxins and exhibits estrogenic activity in the range of natural steroid estrogens such as 17β-estradiol (E2). The occurrence of ZON has been reported in drainage water, soil, wastewater effluents and rivers, but its ecotoxicological effects on fish have hardly been investigated.In this study the estrogenic potency of the ZON was compared to E2 in a recombinant yeast estrogen screen (rYES) and the effects of waterborne ZON exposure on reproduction, physiology and morphology of zebrafish (Danio rerio) were investigated in a 42-day reproduction experiment. E2 as well as ZON evoked a sigmoid concentration-response curve in the rYES with a mean EC₅₀ of 2 and 500 μg/L, respectively, resulting in an E2:ZON EC₅₀ ratio of 1:250. Exposure to ZON for 21 days reduced relative spawning frequency at 1000 and 3200 ng/L to 38.9 and 37.6%, respectively, and relative fecundity at 100, 320, 1000 and 3200 ng/L to 74.2, 41.7, 43.8 and 16.7%, respectively, in relation to the 21-day pre-exposure period. A 4.4 and 8.1 fold induction of plasma vitellogenin (VTG) was observed in male zebrafish at 1000 and 3200 ng/L ZON, respectively. Exposure to ZON did not affect fertility, hatch, embryo survival and gonad morphology of zebrafish.The results of this study demonstrate that although ZON possesses a moderate estrogenic potency in vitro, it exhibits a comparably strong effect on induction of VTG and reproduction in vivo. This indicates that ZON might contribute to the overall estrogenic activity in the environment and could therefore pose a risk for wild fish in their natural habitat.