Search

Chemical systems find similarities in different sociological and biological processes, in which the entities compete or cooperate for a favorable outcome. The structural and functional adaptations leading to emergent properties, especially in catalysis, are based on factors such as abundance of substrates, stability of the transition state, and structural/functional attributes of catalysts. Proline and acid groups appended to catalytic fibers of two self-sorting hydrogelators compete for the Mannich reaction between aniline, benzaldehyde, and cyclohexanone to give low overall selectivity (anti/syn 77:23). In a sol-gel system of the same molecules, on the other hand, the soluble acid appended molecules tend to cooperate with the fibers of proline-appended catalyst to give improved selectivity (anti/syn 95:5). The available options for the catalytic molecules are to carry out the reaction independently or in cooperation. However, these options are chosen based on the efficiency, selectivity, and mobility of catalysts as a result of their abilities to self-assemble.

Fuel-driven reaction cycles are found in biological systems to control the assembly and disassembly of supramolecular materials such as the cytoskeleton. Fuel molecules can bind noncovalently to a self-assembling building block or they can react with it, resulting in covalent modifications. Overall the fuel can either switch the self-assembly process on or off. Here, a closer look is taken at artificial systems that mimic biological systems by making and breaking covalent bonds in a self-assembling motif. The different chemistries used so far are highlighted in chronological order and the pros and cons of each system are discussed. Moreover, the desired traits of future reaction cycles, their fuels, and waste management are outlined, and two chemistries that have not been explored up to now in chemically fueled dissipative self-assembly are suggested.

Self-assembly of small peptides offers unique opportunities for the bottom-up construction of supramolecular catalysts that aim to emulate the efficiency and selectivity of natural enzymes. Small, information-rich, simple molecules based on amino acids can self-organise autonomously into complex systems with emergent catalytic properties. The power of noncovalent interactions can be used to construct supramolecular peptidic tertiary structures. Moreover, specific functional groups present in amino acid side-chains may present either a catalytic activity by themselves or be able to bind cofactors such as metal ions. In this scenario, although relevant progress has been achieved in recent years, promising applications in biomaterials science are foreseen. In this review, we discuss the state-of-the-art of this approach at the interface between supramolecular chemistry and peptide science. Funded by: Ministry of Economy and Competitiveness of Spain. Grant Number: CTQ2012-37735 ; Universitat Jaume I. Grant Number: P1-1B2013-57 ; EU Marie Curie ITN program ; Ministry of Education, Culture and Sport of Spain

Self-assembly of biomolecules catalytically controls the formation of natural supramolecular structures, giving highly ordered complex materials. Such desirable hybrid systems are very difficult to design and construct synthetically. A hybrid double-network hydrogel with a maximum storage modulus (G'max ) of up to 55 kPa can be synthesized by using a self-assembled hydrogel that catalyses the formation of another kinetically arrested hydrogel network. Tuning of the catalytic efficiency of the first network allowed spatiotemporal control over the evolution of the second network and the resulting mechanical properties. The distribution of active catalytic sites was optimal for catalytic fibres prepared at the minimum gelation concentration (MGC) to give the double-network hydrogel with highest storage modulus. This approach could be very useful in preparing complex hierarchical structures with tailor-made properties.

The presence or absence of social counterparts can be instrumental in shaping both individual and collective behaviors. Furthermore, factors of the social environment may safeguard individuals from environmental stressors. In the study reported here, we tested the effects of moving into a new habitat on the mean, variance, and repeatability of individual behavioral tendencies between two social contexts (isolated vs. in a social group). Using the arid social spider, Stegodyphus dumicola (Araneae: Eresidae), we tested whether individuals' boldness was influenced by either (i) their time spent in a social group or (ii) their latency since having moved into a new habitat. We found that the effect of moving into a new habitat on individuals' boldness depended on whether spiders entered the novel environment in isolation or as part of a social group. Spiders that experienced a habitat shift with a social group showed no change in their average boldness, whereas individuals that shifted environments in isolation showed an increase in their mean boldness. Interestingly, neither of these trends was influenced by the time which had elapsed since the habitat shift, suggesting that shifting habitats has a lasting effect on isolated spiders' behavioral tendencies. Finally, we assessed how time spent in a new environment influenced colonies' collective foraging behavior. Here, we found that the longer social groups remained in a new environment, the faster the group responded to prey. Taken together, our data demonstrate that the effects of shifting physical environments on individuals' boldness may depend on individuals' social context, and that group tenure is associated with subtle shifts in colonies' collective foraging behavior.

In recent decades fiber-reinforced polymer (FRP) materials have revolutionized the world of engineering material. It has emerged as a substitute to traditional engineering material because of its aspect ratio. The increase in demand of FRP in various areas such as automotive and aerospace increases the need to do deep and diversified impact analysis of FRP composites. This article is an attempt to review literatures on the impact analysis of FRP composite validated by LS-DYNA. The effect of projectile characterization, fiber orientation, and cores on the impact behavior of FRP composite has been discussed. An attempt is done to view literature from 1990s to present days. Because of insufficiency of relevant paper (using LS-DYNA) in 1990s, this review article includes work done from 2000s to present days. Temperature dependency, energy absorbed, contact time, and damage pattern of the FRP laminates, along with future trend of research work in the area of composite are also discussed. POLYM. COMPOS., 36:1786–1798, 2015. © 2014 Society of Plastics Engineers

Precopulatory sexual cannibalism is an extreme form of sexual conflict that can entail significant costs to the cannibalized individual and a variety of costs and benefits to the cannibal itself. Characterizing these costs and benefits is fundamental to our understanding of how this behavior evolves. Using the spider Agelenopsis pennsylvanica, we tested the reproductive consequences of precopulatory sexual cannibalism by staging cannibalization events and comparing the performance of experimental cannibals against natural cannibals (i.e., those that cannibalized on their own) and non-cannibals. We found two performance benefits associated with precopulatory sexual cannibalism: first, experimental cannibals were more likely to produce egg cases than non-cannibals, and second, egg cases from experimental cannibals and natural cannibals were significantly more likely to hatch than those produced by non-cannibals. We then tested whether males were more likely to approach the webs of experimental cannibals vs. non-cannibalistic control females. Our data demonstrate that sexual cannibalism increases female attractiveness to males. Although this result seems counterintuitive, in fact, rates of precopulatory sexual cannibalism were much lower in females that had already cannibalized their first male: 38% of sexually naive females engaged in precopulatory sexual cannibalism, whereas only 5% of females engaged in cannibalism a second time. Thus, males that approach cannibals receive two benefits: they are less likely to be cannibalized precopula, and they have the possibility of mating with females that have a higher probability of producing viable egg cases. Taken together, our data suggest that precopulatory sexual cannibalism affords females numerous benefits and may have a hand in shaping male mate choice decisions.

In the present investigation, polysulfone (PSu) nanocomposites were successfully prepared by solvent casting method. Layered silicates, viz., sodium montmorillonite (NaMMT), Cloisite 93A, and Cloisite 30B were dispersed in PSu to obtain nanocomposite membranes. PSu nanocomposite membranes were tested for mechanical performance, water uptake, thermal properties, X-ray diffraction, and scanning electron microscopy (SEM). The nanocomposite membranes showed an increment in tensile properties, whereas a reduction was observed in water uptake. X-ray diffraction studies confirmed the intercalation of PSu within the silicate galleries. SEM analysis confirmed an increase in the porosity of the membrane with the incorporation of nanoclays. Thermo gravimetric analysis (TGA) thermograms indicated an increase in the thermal stability of PSu nanocomposites. Evaluation of conductivity characteristics and single cell performance revealed improved output for organomodified clay nanocomposites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The formal synthesis of aplykurodinone-1 is accomplished starting from a suitably functionalized bicyclic lactone having the requisite cis-fused ring junction with a quaternary chiral center that was assembled following a Cp2TiCl-mediated radical cyclization protocol. Our synthetic route further elaborates implementation of Grubbs ring closing metathesis (RCM), Eschenmoser-Claisen rearrangement and iodo-lactonization reactions for the synthesis of the final tricyclic precursor of the target molecule. (C) 2015 Elsevier Ltd. All rights reserved.

Self-assembly of small peptides offers unique opportunities for the bottom-up construction of supramolecular catalysts that aim to emulate the efficiency and selectivity of natural enzymes. Small, information-rich, simple molecules based on amino acids can self-organise autonomously into complex systems with emergent catalytic properties. The power of noncovalent interactions can be used to construct supramolecular peptidic tertiary structures. Moreover, specific functional groups present in amino acid side-chains may present either a catalytic activity by themselves or be able to bind cofactors such as metal ions. In this scenario, although relevant progress has been achieved in recent years, promising applications in biomaterials science are foreseen. In this review, we discuss the state-of-the-art of this approach at the interface between supramolecular chemistry and peptide science.