Contribution to the special issue on reptile cognition: Context-specific cue use in the Eastern painted turtle (Chrysemys picta) and its effects on decision making

Many species consider both prior experiences and the context of current stimuli when making behavioural decisions. Herein, we explore the influence of prior experience and novel incoming stimuli on the decision-making in the Eastern painted turtle (Chrysemys picta). We used a free-choice Y-maze to assess the preferences of turtles wavelength and intensity of light. We then trained naïve turtles to associate one arm of a maze with a food reward, and then tested the relevance of light colour and intensity on the turtles’ decision-making regarding arm choice. Turtles avoided bright light, even when presented on the side of the maze with which they had learned to associate a food. When light intensities of both sides were the same — irrespective of intensity — turtles chose the side they had previously learned to associate with the food reward. C. picta in our study showed a weak attraction to blue light and a strong avoidance of yellow light, a response generally consistent with previous work in sea turtles. Future studies should examine the ecological and evolutionary relevance of these decisions in field-oriented tests.

Revisiting the Dissolution of Cellulose in NaOH as “Seen” by X-rays

Cotton production is reaching a global limit, leading to a growing demand for bio-based textile fibers produced by other means. Textile fibers based on regenerated cellulose from wood holds great potential, but in order to produce fibers, the components need to be dissolved in suitable solvents. Furthermore, the dissolution process of cellulose is not yet fully understood. In this study, we investigated the dissolution state of microcrystalline cellulose in aqueous NaOH by using primarily scattering methods. Contrary to previous findings, this study indicated that cellulose concentrations of up to 2 wt % are completely molecularly dissolved in 8 wt % NaOH. Scattering data furthermore revealed the presence of semi-flexible cylinders with stiff segments. In order to improve the dissolution capability of NaOH, the effects of different additives have been of interest. In this study, scattering data indicated that the addition of ZnO decreased the formation of aggregates, while the addition of PEG did not improve the dissolution properties significantly, although preliminary NMR data did suggest a weak attraction between PEG and cellulose. Overall, this study sheds further light on the dissolution of cellulose in NaOH and highlights the use of scattering methods to assess solvent quality.

Floral Odors and the Interaction between Pollinating Ceratopogonid Midges and Cacao

Most plant species depend upon insect pollination services, including many cash and subsistence crops. Plants compete to attract those insects using visual cues and floral odor which pollinators associate with a reward. The cacao tree, Theobroma cacao, has a highly specialized floral morphology permitting pollination primarily by Ceratopogonid midges. However, these insects do not depend upon cacao flowers for their life cycle, and can use other sugar sources. To understand how floral cues mediate pollination in cacao we developed a method for rearing Ceratopogonidae through several complete lifecycles to provide material for bioassays. We carried out collection and analysis of cacao floral volatiles, and identified a bouquet made up exclusively of saturated and unsaturated, straight-chain hydrocarbons, which is unusual among floral odors. The most abundant components were tridecane, pentadecane, (Z)-7-pentadecene and (Z)-8-heptadecene with a heptadecadiene and heptadecatriene as minor components. We presented adult midges, Forcipomyia sp. (subgen. Forcipomyia), Culicoides paraensis and Dasyhelea borgmeieri, with natural and synthetic cacao flower odors in choice assays. Midges showed weak attraction to the complete natural floral odor in the assay, with no significant evidence of interspecific differences. This suggests that cacao floral volatiles play a role in pollinator behavior. Midges were not attracted to a synthetic blend of the above four major components of cacao flower odor, indicating that a more complete blend is required for attraction. Our findings indicate that cacao pollination is likely facilitated by the volatile blend released by flowers, and that the system involves a generalized odor response common to different species of Ceratopogonidae.

Crystal structure of the layered arsenide Rb3Cu3As2

The crystal structure of a new arsenide, Rb3Cu3As2 (trirubidium tricopper diarsenide), has been established from single-crystal X-ray diffraction data. This compound crystallizes in the K3Cu3P2 type, with layers of interlinked CuAs2 units. The partitioning of the available valence electrons yields the charge-balanced composition (Rb+)3(Cu+)3(As3–)2, placing this phase in a broad field of transition-metal-containing Zintl phases. First-principles calculations confirm a semiconducting ground state, in accordance with electron-counting considerations. Chemical bonding analysis reveals strong covalent Cu—As bonds and ionic Rb...As interactions. In addition, a weak attraction is found between the Cu atoms, possibly pointing toward cuprophilic interactions.

Understanding the microstructure of particle dispersion in confined copolymer nanocomposites

Innovation: confinement enhances the dispersion of particles with weak attraction in copolymers, while the effect can be reversed as the attraction increases.