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Carbon-based ionogels tuning the properties of the ionic liquid via carbon-ionic liquid interaction
(2012)
The behavior of two ionic liquids (ILs), 1-ethyl-3-methylimidazolium dicyanamide [Emim][DCA] and 1-ethyl-3-methylimidazolium triflate [Emim][TfO], in (meso) porous carbonaceous hosts was investigated. Prior to IL incorporation into the host, the carbon matrix was thermally annealed between 180 and 900 degrees C to control carbon condensation and surface chemistry. The resulting materials have an increasing "graphitic'' carbon character with increasing treatment temperature, reflected in a modified behavior of the ILs when impregnated into the carbon host. The two ILs show significant changes in the thermal behavior as measured from differential scanning calorimetry; these changes can be assigned to anion-pi interaction between the IL anions and the pore wall surfaces of these flexible carbonaceous support materials.
Hybrid magnetic nanoparticles (mgNP) with a magnetite core diameter of 10 +/- 1 nm surface functionalized with oligo(omega-pentadecalactone) (OPDL) oligomers with M-n between 1300 and 3300 g mol(-1) could be successfully prepared having OPDL grafted from 200 mg g(-1) to 2170 mg g(-1). The particles are dispersible in chloroform resulting in stable suspensions. Magnetic response against an external magnetic field proved the superparamagnetic nature of the particles with a low coercivity (B-c) value of 297 mu T. The combination of the advantageous superparamagnetism of the mgNP with the exceptional stability of OPDL makes these novel hybrid mgNP promising candidates as multifunctional building blocks for magnetic nanocomposites with tunable physical properties.
Mesoporous, highly structured silicon carbide (beta-SiC) was synthesised from renewable plant materials (two Equisetaceae species) in a one-step carbothermal process at remarkably low temperatures down to 1200 degrees C. The SiC precursor is a silicon-carbon mixture with finely dispersed carbon prepared by pyrolysis of the organic plant matrix. Yields are 3 to 100% (omega(Si/Si) related to the silicon deposited in the plant material), depending on reaction temperature and time. IR spectroscopy, X-ray diffraction, and nitrogen sorption prove the formation of high-purity beta-SiC with minor inorganic impurities after purification and a high specific surface area of up to 660 m(2) g(-1). Scanning electron microscopy shows that the plant morphology is maintained in the final SiC. Sedimentation analysis finds a mean particle size (diameters d(50)) of 20 mu m.
It is well known that the spacetime diagrams of some cellular automata have a self-similar fractal structure: for instance Wolfram's rule 90 generates a Sierpinski triangle. Explaining the self-similarity of the spacetime diagrams of cellular automata is a well-explored topic, but virtually all of the results revolve around a special class of automata, whose typical features include irreversibility, an alphabet with a ring structure, a global evolution that is a ring homomorphism, and a property known as (weakly) p-Fermat. The class of automata that we study in this article has none of these properties. Their cell structure is weaker, as it does not come with a multiplication, and they are far from being p-Fermat, even weakly. However, they do produce self-similar spacetime diagrams, and we explain why and how.
This editorial introduces a set of papers on differential embodiment in spatial tasks. According to the theoretical notion of embodied cognition, our experiences of acting in the world, and the constraints of our sensory and motor systems, strongly shape our cognitive functions. In the current set of papers, the authors were asked to particularly consider idiosyncratic or differential embodied cognition in the context of spatial tasks and processes. In each contribution, differential embodiment is considered from one of two complementary perspectives: either by considering unusual individuals, who have atypical bodies or uncommon experiences of interacting with the world; or by exploring individual differences in the general population that reflect the naturally occurring variability in embodied processes. Our editorial summarizes the contributions to this special issue and discusses the insights they offer. We conclude from this collection of papers that exploring differences in the recruitment and involvement of embodied processes can be highly informative, and can add an extra dimension to our understanding of spatial cognitive functions. Taking a broader perspective, it can also shed light on important theoretical and empirical questions concerning the nature of embodied cognition per se.
The switching kinetics of thin thermo-responsive hydrogel films of poly(monomethoxy-diethyleneglycol-acrylate) (PMDEGA) are investigated. Homogeneous and smooth PMDEGA films with a thickness of 35.9 nm are prepared on silicon substrates by spin coating. As probed with white light interferometry, PMDEGA films with a thickness of 35.9 nm exhibit a phase transition temperature of the lower critical solution temperature (LCST) type of 40 degrees C. In situ neutron reflectivity is performed to investigate the thermo-responsive behavior of these PMDEGA hydrogel films in response to a sudden thermal stimulus in deuterated water vapor atmosphere. The collapse transition proceeds in a complex way which can be seen as three steps. The first step is the shrinkage of the initially swollen film by a release of water. In the second step the thickness remains constant with water molecules embedded in the film. In the third step, perhaps due to a conformational rearrangement of the collapsed PMDEGA chains, water is reabsorbed from the vapor atmosphere, thereby giving rise to a relaxation process. Both the shrinkage and relaxation processes can be described by a simple model of hydrogel deswelling.
The trade-off between predation risk and the need to feed is one of the major constraints animals have to cope with. Virtually all animals have a higher risk of being preyed upon when being active (e.g., searching for food or mating partners), compared with being inactive (e.g., staying at their burrows, nests, etc.). Yet, staying safe leads to a higher risk of starvation and may reduce reproductive success and body growth. Hence selection on behaviour optimizing the search, handling and digestion of food while avoiding the risk of predation is strong and should lead to strategies maximising survival chances and inclusive fitness. These facts call for integrative studies manipulating both, abundance of food and predation risk in a factorial set up, analysing the effects of both factors on behaviour and physiological parameters. We present results of a 2 x 2 factorial experiment, manipulating risk of predation and food abundance in guppies. We found that the two factors have an additive effect on body growth, but that predation risk by a pike cichlid is the main factor affecting the expression of behavioural strategies in guppies. Low food availability and high predation risk led to lower body growth. High predation risk affected swimming depth and risk sensitivity of guppies and might represent adaptive behavioural changes to the environmental context experienced in early life. Our study shows that integrative studies, analysing multiple interdependent and interconnected factors in the wild and in the lab are needed to further understand animal behaviour and development.
Today, serious health problems as overweight and obesity are not just constricted to the developed world, but also increase in the developing countries (Prentice 2006, Ramachandram et al. 2002). Focusing on this issue, BMI and percentage of body fat were compared in 2094 schoolchildren from two cross-sectional studies from India and Germany investigated in 2008 and 2009. The German children are in all age groups significantly taller, whereas the Indian children show higher values in BMI (e.g. 12 years: Indian: around 22 kg/m(2); German: around 19 kg/m(2)) and in the percentage of body fat (e.g. 12 years: Indian: around 27 %; German: around 18-20%) in most of the investigated age groups. The Indian children have significantly higher BMI between 10 and 13 (boys) respectively 14 years (girls). Indian children showed significant higher percentage of body fat between 10 and 15 years (boys) and between 8 and 16 years (girls). The difference in overweight between Indian and German children was strongest at 11 (boys) and 12 (girls) years: 70 % of the Indian but 20% of the German children were classified as overweight. In countries such as India that undergo nutritional transition, a rapid increase in obesity and overweight is observed. In contrast to the industrialized countries, the risk of overweight in developing countries is associated with high socioeconomic status. Other reasons of the rapid increase of overweight in the developing countries caused by different environmental or genetic factors are discussed.