University of Akron

About: University of Akron is a education organization based out in Akron, Ohio, United States. It is known for research contribution in the topics: Polymer & Polymerization. The organization has 17401 authors who have published 29127 publications receiving 702386 citations. The organization is also known as: The University of Akron.

The Form and Function of Spider Orb Webs: Evolution from Silk to Ecosystems

Abstract: Spiders are the preeminent silk craftsmen among arthropods and are best known for producing aerial orb webs that snare flying insects. Orb web spiders are ubiquitous predators in terrestrial ecosystems and are popular models for behavioural and ecological research, in part due to the ease of characterizing the shapes of orb webs. Orb webs are composite structures built from multiple types of silks, each with its own unique molecular structure and mechanical function, such that orb webs also link together evolutionary research from the genes coding for silk proteins to whole web function in the environment. Yet, orb webs are only intermediate structures in the evolutionary diversification of silk use among spiders, acting as stepping stones facilitating the origin of new web types and increased spider diversification. Here, we review the current research on the form and function of spider orb webs. We provide a comprehensive introduction to all aspects of orb web biology, suitable for any new investigation into orb web biology. While other reviews exist individually for webs, silk, and spider evolution, we hope that the synthetic nature of this review will facilitate a more integrated approach by future investigators. Finally, we explore in more detail some of the most dynamic areas of orb web biology to suggest promising venues for the next decade of research on these fascinating creatures and their silken snares. In particular, we discuss how spider webs might drive speciation, the dramatic growth in our understanding of the molecular ecology of spider silk, and the importance of a greater role for spider biology per se in silk biomimicry.

In vitro antimicrobial studies of silver carbene complexes: activity of free and nanoparticle carbene formulations against clinical isolates of pathogenic bacteria

Abstract: Methods: MIC, MBC and multidose experiments were conducted against a broad range of bacteria and fungi. Time-release and cytotoxicity studies of the compounds were also carried out. Free SCCs and SCC NPs were tested against a panel of medically important pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Acinetobacter baumannii (MRAB), Pseudomonas aeruginosa, Burkholderia cepacia and Klebsiella pneumoniae. Results: All four SCCs demonstrated strong efficacy in concentration ranges of 0.5 –90 mg/L. Clinical bacterial isolates with high inherent resistance to purified compounds were more effectively treated either with an NP formulation of these compounds or by repeated dosing. Overall, the compounds were active against highly resistant bacterial strains, such as MRSA and MRAB, and were active against the biodefence pathogens Bacillus anthracis and Yersinia pestis. All of the medically important bacterial strains tested play a role in many different infectious diseases. Conclusions: The four SCCs described here, including their development as NP therapies, show great promise for treating a wide variety of bacterial and fungal pathogens that are not easily killed by routine antimicrobial agents.

Mechanical degradation of high polymers

Abstract: A theory for the shear degradation of high polymers is presented. It assumes the molecules to exist in the rubbery or liquid state and does not include the effects of chemical reactions which might occur subsequent to chain rupture. The computation shows that the entanglements along the chains play a major part in the rupture process. Expressions for the rate of chain rupture are obtained in terms of the melt viscosity, shear rate, and molecular weight. Other factors enter also, but the sensitive variables are those listed. The variation of molecular weight distribution with shear degradation is considered. It is pointed out why oxidative scission during shear is not a random process. In general, the theoretical result agrees with the limited experimental data available.