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Wilton, United Kingdom

Byrne J.M.,University of Manchester | Byrne J.M.,University of Tubingen | Muhamadali H.,University of Manchester | Coker V.S.,University of Manchester | And 2 more authors.
Journal of the Royal Society Interface | Year: 2015

Although there are numerous examples of large-scale commercial microbial synthesis routes for organic bioproducts, few studies have addressed the obvious potential for microbial systems to produce inorganic functional biomaterials at scale. Here we address this by focusing on the production of nanoscale biomagnetite particles by the Fe(III)-reducing bacterium Geobacter sulfurreducens, which was scaled up successfully from laboratory- to pilot plant-scale production, while maintaining the surface reactivity and magnetic properties which make this material well suited to commercial exploitation. At the largest scale tested, the bacterium was grown in a 50 l bioreactor, harvested and then inoculated into a buffer solution containing Fe(III)-oxyhydroxide and an electron donor and mediator, which promoted the formation of magnetite in under 24 h. This procedure was capable of producing up to 120 g of biomagnetite. The particle size distribution was maintained between 10 and 15 nm during scale-up of this second step from 10 ml to 10 l, with conserved magnetic properties and surface reactivity; the latter demonstrated by the reduction of Cr(VI). The process presented provides an environmentally benign route to magnetite production and serves as an alternative to harsher synthetic techniques, with the clear potential to be used to produce kilogram to tonne quantities. © 2015 The Authors. Source

O'Malley M.A.,Massachusetts Institute of Technology | Theodorou M.K.,Durham University | Theodorou M.K.,Center for Process Innovation | Kaiser C.A.,Massachusetts Institute of Technology
Environmental Progress and Sustainable Energy | Year: 2012

The development of efficient methods to convert plant material (lignocellulose) to fermentable sugars is a promising avenue towards the development of renewable biofuels. Anaerobic fungi that reside within the digestive tract of large herbivores are among the most efficient and robust digesters of lignocellulosic material known in nature. Despite the powerful cellulose degrading capacity of gut fungi, remarkably little is known about the cellulolytic enzymes from these organisms due to the difficulties associated with their isolation and culture. We have cloned five such saccharolytic enzymes (bglA, cel48A, celpin, xylA, and xylB) from a cDNA library prepared from the anaerobic fungus Piromyces sp E2 for expression and extracellular secretion in the model eukaryote Saccharomyces cerevisiae. All enzymes were readily produced, but only low-molecular weight proteins (xylA and xylB) were secreted efficiently into the extracellular medium. Piromyces sp E2 enzymes were posttranslationally modified in S. cerevisiae according to their sequence prediction, suggesting compatibility between the two systems, yet not all of the recombinant proteins were catalytically active. Activation of cellular stress mechanisms in the secretory pathway suggest enzyme misfolding during the production of cel48A and bglA, which likely limits activity. However, bglA, exhibited moderate reactivity against pNPG when produced in S. cerevisiae. Furthermore, since we aim to understand how the cellulolytic enzymes of anaerobic fungi are produced in their native system, we have implemented methods to isolate and culture anaerobic fungi obtained from the digestive tract of a horse. © 2011 American Institute of Chemical Engineers. Source

Smith A.,Center for Process Innovation
Association of Industrial Metallizers, Coaters and Laminators Fall Technical Conference and 24th International Vacuum Web Coating Conference 2010 | Year: 2010

Flexible substrates with high mositure barrier performance are required for a wide range of devices, from flexible photovolatics through to flexible OLED displays. Atomic Layer Deposition (ALD) and sputtering techniques for the production of these barriers on plastic webs will be discussed and compared. Considerations to the barrier laminate structure and the effect on performance and the lifetime of it will be discussed. Source

Becker J.-M.,University of Cologne | Rai A.,Center for Process Innovation | Ringle C.M.,University of Management and Technology | Ringle C.M.,University of Newcastle | Volckner F.,University of Cologne
MIS Quarterly: Management Information Systems | Year: 2013

A large proportion of information systems research is concerned with developing and testing models pertaining to complex cognition, behaviors, and outcomes of individuals, teams, organizations, and other social systems that are involved in the development, implementation, and utilization of information technology. Given the complexity of these social and behavioral phenomena, heterogeneity is likely to exist in the samples used in IS studies. While researchers now routinely address observed heterogeneity by introducing moderators, a priori groupings, and contextual factors in their research models, they have not examined how unobserved heterogeneity may affect their findings. We describe why unobserved heterogeneity threatens different types of validity and use simulations to demonstrate that unobserved heterogeneity biases parameter estimates, thereby leading to Type I and Type II errors. We also review different methods that can be used to uncover unobserved heterogeneity in structural equation models. While methods to uncover unobserved heterogeneity in covariance-based structural equation models (CB-SEM) are relatively advanced, the methods for partial least squares (PLS) path models are limited and have relied on an extension of mixture regression-finite mixture partial least squares (FIMIX-PLS) and distance measure-based methods-that have mismatches with some characteristics of PLS path modeling. We propose a new method-prediction-oriented segmentation (PLSPOS)- to overcome the limitations of FIMIX-PLS and other distance measure-based methods and conduct extensive simulations to evaluate the ability of PLS-POS and FIMIX-PLS to discover unobserved heterogeneity in both structural and measurement models. Our results show that both PLS-POS and FIMIX-PLS perform well in discovering unobserved heterogeneity in structural paths when the measures are reflective and that PLS-POS also performs well in discovering unobserved heterogeneity in formative measures. We propose an unobserved heterogeneity discovery (UHD) process that researchers can apply to (1) avert validity threats by uncovering unobserved heterogeneity and (2) elaborate on theory by turning unobserved heterogeneity into observed heterogeneity, thereby expanding theory through the integration of new moderator or contextual variables. Source

Hsieh J.J.P.-A.,Hong Kong Polytechnic University | Rai A.,Center for Process Innovation | Petter S.,University of Nebraska at Omaha | Zhang T.,Xian Jiaotong University
MIS Quarterly: Management Information Systems | Year: 2012

An increasing number of organizations are now implementing customer relationship management (CRM) systems to support front-line employees' service tasks. With the belief that CRM can enhance employees' service quality, management often mandates employees to use the implemented CRM. However, challenges emerge if/when employees are dissatisfied with using the system. To understand the role of front-line employee users' satisfaction with their mandated use of CRM in determining their service quality, we conducted a field study in one of the largest telecommunications service organizations in China and gathered time-lagged data from self-reported employee surveys, as well as from the firm's archival data sources. Our results suggest that employees' overall user satisfaction (UserSat) with their mandated use of CRM has a positive impact on employee service quality (ESQ) above and beyond the expected positive impacts that job dedication (JD) and embodied service knowledge (ESK) have on ESQ. Interestingly, the positive effect of UserSat on ESQ is comparable to the positive effects of JD and ESK, respectively, on ESQ. Importantly, UserSat and ESK have a substitutive effect on ESQ, suggesting that the impact of UserSat on ESQ is stronger/weaker for employees with lower/higher levels of ESK. Finally, ESQ predicts customer satisfaction with customer service employees (CSWCSE); ESQ also fully mediates the impacts of UserSat and ESK, and partially mediates the impact of JD, on CSWCSE. The results of this study emphasize the importance of user satisfaction in determining employees' task outcomes when use of an information system is mandated. Source

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