Q. Li, A. L. Woodhead, J. S. Church, M. Naebe

Contamination caused by inappropriate carbon fibre (CF) storage may have an impact on their end use in reinforced composite materials. Due to the chemical complexity of CFs it is not easy to detect potential contaminants, especially at the early stage during manufacturing and handling. In this paper, X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FTIR) spectroscopy and Surface Energy Analysis (IGC-SEA) were used to assess the surfaces of CFs stored in polyolefin zip-lock bags for possible contamination. Only after over 2 months in-bag storage, was XPS capable of detecting a minor increase in nitrogen on the CF surface while FTIR revealed the presence of fatty acid amides and fatty acids, both associated with the storage media. However neither of these techniques were sensitive enough to show significant evolution of the amount of contamination as a function of storage time. In contrast, IGC-SEA distinguished surface energy differences between CFs before and after storage. These differences were found to change as a function of storage time, which were attributed to increases in contamination amounts. Single fibre fragmentation tests indicated that the surface contamination had potential to disrupt the fibre-matrix interface. These findings provide a new method for assessing the surface contamination of CFs with potential application to other materials.

A. L. Woodhead, A. T. Church, T. D. Rapson, H. E. Trueman, J. S. Church, T. D. Sutherland

Honeybee larvae produce a silk made up of proteins in predominantly a coiled coil molecular structure. These proteins can be produced in recombinant systems, making them desirable templates for the design of advanced materials. However, the atomic level structure of these proteins is proving difficult to determine: firstly, because coiled coils are difficult to crystalize; and secondly, fibrous proteins crystalize as fibres rather than as discrete protein units. In this study, we synthesised peptides from the central structural domain, as well as the N- and C-terminal domains, of the honeybee silk. We used circular dichroism spectroscopy, infrared spectroscopy, and molecular dynamics to investigate the folding behaviour of the central domain peptides. We found that they folded as predicted by bioinformatics analysis, giving the protein engineer confidence in bioinformatics predictions to guide the design of new functionality into these protein templates. These results, along with the infrared structural analysis of the N- and C-terminal domain peptides and the comparison of peptide film properties with those of the full-length AmelF3 protein, provided significant insight into the structural elements required for honeybee silk protein to form into stable materials.

N. Hameed, L. F. Dumée, F-M. Allioux, M. Reghat, J. S. Church, M. Naebe, K. Magniez, J. Parameswaranpillai, B. L. Fox

Graphene based room temperature flexible nanocomposites were prepared using epoxy thermosets for the first time. Flexible behavior was induced into the epoxy thermosets by introducing charge transfer complexes between functional groups within cross linked epoxy and room temperature ionic liquid ions. The graphene nanoplatelets were found to be highly dispersed in the epoxy matrix due to ionic liquid cation–π interactions. It was observed that incorporation of small amounts of graphene into the epoxy matrix significantly enhanced the mechanical properties of the epoxy. In particular, a 0.6 wt% addition increased the tensile strength and Young’s modulus by 125% and 21% respectively. The electrical resistance of nanocomposites was found to be increased with graphene loading indicating the level of self-organization between the ILs and the graphene sheets in the matrix of the composite. The graphene nanocomposites were flexible and behave like ductile thermoplastics at room temperature. This study demonstrates the use of ionic liquid as a compatible agent to induce flexibility in inherently brittle thermoset materials and improve the dispersion of graphene to create high performance nanocomposite materials.

A. L. Woodhead, M. L. de Souza, J. S. Church

The carbon fiber surface plays a critical role in the performance of carbon fiber composite materials and, thus it is important to have a thorough understanding of the fiber surface. A series of nitric acid treated intermediate modulus carbon fibers with increasing treatment level was prepared and characterized using a range of surface sensitive techniques including Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The results, which were found to be consistent with increasing treatment levels, were compared to the literature. Raman spectral mapping has been used to investigate the heterogeneity of the carbon fiber surface after nitric acid oxidation. The mapping enabled the effects of surface treatment on carbon fiber to be investigated at a spatial resolution unattainable by XPS and provided chemical structure information not provided by SEM or AFM. The highest level of treatment resulted in the most heterogeneous surface. Raman mapping, while time consuming, can provide valuable information which can lead to an enhanced understanding of the heterogeneity of the carbon fiber surface.

T. D. Rapson, J-W. Liu, A. Sriskantha, M. Musameh, C. J. Dunn, J. S. Church, A. Woodhead, A. C. Warden, M. J. Riley, J. R. Harmer, C. J. Noble, T. D. Sutherland

In our previous studies, heme was bound into honeybee silk to generate materials that could function as nitric oxide sensors or as recoverable heterogeneous biocatalysts. In this study, we sought to increase the heme-binding capacity of the silk protein by firstly redesigning the heme binding site to contain histidine as the coordinating residue and secondly, by adding multiple histidine residues within the core of the coiled coil core region of the modified silk protein. We used detergent and a protein denaturant to confirm the importance of the helical structure of the silk for heme coordination. Aqueous methanol treatment, which was used to stabilize the materials, transformed the low-spin, six-coordinate heme to a five-coordinate high-spin complex, thus providing a vacant site for ligand binding. The optimal aqueous methanol treatment time that simultaneously maintains the helical protein structure and stabilizes the silk material without substantial leaching of heme from the system was determined.

T. D. Rapson, R. Kusuoka, J. Butcher, M. Musameh, C. J. Dunn, J. S. Church, A. Warden, C. F. Blanford, N. Nakamura, T. D. Sutherland

Fuel cells are a promising avenue for renewable energy production. While oxygen remains the preferred oxidant, its slow reduction kinetics has limited fuel cell performance and it currently requires the use of platinum as the cathode catalyst. In the search for non-platinum cathodes, inspiration has been sought from biological oxygen reduction processes which use heme proteins for respiration. Here, we describe the use of recombinant honeybee silk protein, which can be produced at high scale in E. coli, to generate a heme–protein material. In these solid-state silk materials, a tyrosine residue oordinates directly to the heme iron center. This axial coordination promotes heterolytic O–O bond cleavage,rather than homolytic cleavage, avoiding the generation of destructive hydroxyl radicals. The heme–silk materials can fully reduce oxygen to water with 3.7 electrons transferred to oxygen and only 14% hydrogen peroxide produced. Importantly, the films demonstrate remarkable stability. The films retained activity when used under continuous operation for over 16 hours and retained 85% of their catalytic activity when used at pH 3 for two hours.

G. Golkarnarenji, M. Naebe, J. S. Church, K. Badii, A. Bab-Hadiashar, S. Atkiss, H. Khayyam

analysis of a chemical process. In this article, the skin core morphology has been analyzed by optical microscopic (OM) images and Fourier transform infrared attenuated total reflectance mapping (FTIR-ATR mapping). The results of FTIR-ATR mapping showed that the fiber is almost uniform in the core area while OM images are accurate enough to be used for skin-core analysis. Using OM images, the core ratio of samples were measured to quantify the skin-core structure. Non-parametric kernel density estimation methods have then been compared with conventional parametric distribution models using these data. The results reveal that the parametric methods cannot adequately describe the skin-core phenomenon and that the non-parametric distributions are more appropriate for the quantification of skin-core morphology. By applying the non-parametric distributions, a model has been developed, which describes the relationship between the skin-core defect and the operation parameters of the fiber production. This approach can be used to predict the probability of skin-core occurrence and can be used to decrease the presence of this phenomenon in the carbon fibers production industry. Our results show that temperature is one of the most significant operational parameter at a typical oxygen concentration (in air at atmospheric pressure) governing the skin-core formation.

P. Church, H. Mueller, C. Ryan, S. Gogouvitis, A. Goscinski, Z. Tari

SCADA systems allow users to monitor and/or control physical devices, processes, and events remotely and in real-time. As these systems are critical to industrial processes, they are often run on highly reliable and dedicated hardware. Moving these SCADA systems to an Infrastructure as a Service (IaaS) cloud allows for: cheaper deployments, system redundancy support, and increased uptime. The goal of this work was to present the results of our experimental study of moving/migrating a selected SCADA system to a cloud environment and present major lessons learned. To this end, EclipseSCADA was deployed to the NeCTAR research cloud using the “lift and shift” approach. Performance metrics of a unique nature and large scale of experimentation were collected from the deployed EclipseSCADA system under different loads to examine the effects cloud resources and public networks have on SCADA behavior.