The future of manufacturing

Anyone who looks at the title of this special issue will agree that the intent behind the preparation of this volume was ambitious: to predict and discuss “The Future of Manufacturing”. Will manufacturing be important in the future? Even though some sceptics might say not, and put on the table some old familiar arguments, we would strongly disagree. To bring subsidies for the argument we issued the call-for-papers for this special issue of Journal of Manufacturing Technology Management, fully aware of the size of the challenge in our hands. But we strongly believed that the enterprise would be worthwhile. The point of departure is the ongoing debate concerning the meaning and content of manufacturing. The easily visualised internal activity of using tangible resources to make physical products in factories is no longer a viable way to characterise manufacturing. It is now a more loosely defined concept concerning the organisation and management of open, interdependent, systems for delivering goods and services, tangible and intangible, to diverse types of markets. Interestingly, Wickham Skinner is the most cited author in this special issue of JMTM. He provides the departure point of several articles because his vision and insights have guided and inspired researchers in production and operations management from the late 1960s until today. However, the picture that we draw after looking at the contributions in this special issue is intrinsically distinct, much more dynamic, and complex. Seven articles address the following research themes: 1.new patterns of organisation, where the boundaries of firms become blurred and the role of the firm in the production system as well as that of manufacturing within the firm become contingent; 2.new approaches to strategic decision-making in markets characterised by turbulence and weak signals at the customer interface; 3.new challenges in strategic and operational decisions due to changes in the profile of the workforce; 4.new global players, especially China, modifying the manufacturing landscape; and 5.new techniques, methods and tools that are being made feasible through progress in new technological domains. Of course, many other important dimensions could be studied, but these themes are representative of current changes and future challenges. Three articles look at the first theme: organisational evolution of production and operations in firms and networks. Karlsson's and Skold's article represent one further step in their efforts to characterise “the extraprise”. In the article, they advance the construction of a new framework, based on “the network perspective” by defining the formal elements which compose it and exploring the meaning of different types of relationships. The way in which “actors, resources and activities” are conceptualised extends the existing boundaries of analytical thinking in operations management and open new avenues for research, teaching and practice. The higher level of abstraction, an intrinsic feature of the framework, is associated to the increasing degree of complexity that characterises decisions related to strategy and implementation in the manufacturing and operations area, a feature that is expected to become more and more pervasive as time proceeds. Riis, Johansen, Englyst and Sorensen have also based their article on their previous work, which in this case is on “the interactive firm”. They advance new propositions on strategic roles of manufacturing and discuss why the configuration of strategic manufacturing roles, at the level of the network, will become a key issue and how the indirect strategic roles of manufacturing will become increasingly important. Additionally, by considering that value chains will become value webs, they predict that shifts in strategic manufacturing roles will look like a sequence of moves similar to a game of chess. Then, lastly under the first theme, Fleury and Fleury develop a conceptual framework for the study of production systems in general derived from field research in the telecommunications industry, here considered a prototype of the coming information society and knowledge economy. They propose a new typology of firms which, on certain dimensions, complements the propositions found in the other two articles. Their telecoms-based framework (TbF) comprises six types of companies characterised by distinct profiles of organisational competences, which interact according to specific patterns of relationships, thus creating distinct configurations of production networks. The second theme is addressed by Kyläheiko and SandstroÍm in their article “Strategic options based framework for management of dynamic capabilities in manufacturing firms”. They propose a new approach to strategic decision-making in markets characterised by turbulence and weak signals at the customer interface. Their framework for a manufacturing firm in the digital age leads to active asset selection (strategic investments in both tangible and intangible assets) and efficient orchestrating of the global value net in “thin” intangible asset markets. The framework consists of five steps based on Porter's five-forces model, the resources-based view, complemented by means of the concepts of strategic options and related flexibility issues. Thun, GroÍssler and Miczka's contribution to the third theme brings the human dimension to the debate regarding the future of manufacturing. Their article focuses on the challenges brought to management by the ageing of workers in Germany but, in the arguments that are raised, the future challenges associated to workers and work organisation in every production system become visible and relevant. An interesting point in the approach adopted by the authors is that not only the factual problems and solutions are taken into account but the perception of the managers is brought into the picture. China cannot be absent in the discussion of the future of manufacturing. Therefore, within the fourth theme, Vaidya, Bennett and Liu provide the evidence of the gradual improvement of Chinese companies in the medium and high-tech sectors, by using the revealed comparative advantage (RCA) analysis. The Chinese evolution is shown to be based on capabilities developed through combining international technology transfer and indigenous learning. The main implication for the Western companies is the need to take account of the accelerated rhythm of capability development in China. For other developing countries China's case provides lessons of great importance. Finally, under the fifth theme, Kuehnle's article: “Post mass production paradigm (PMPP) trajectories” provides a futuristic scenario of what is already around us and might become prevalent in the future. It takes a very intensive look at a whole set of dimensions that are affecting manufacturing now, and will influence manufacturing in the future, ranging from the application of ICT to the need for social transparency. In summary, this special issue of JMTM presents a brief, but undisputable, demonstration of the possible richness of manufacturing in the future. Indeed, we could even say that manufacturing has no future if we only stick to the past perspectives. Embracing the new is not easy. The new configurations of production systems, the distributed and complementary roles to be performed by distinct types of companies in diversified networked structures, leveraged by the new emergent technologies and associated the new challenges for managing people, are all themes that are carriers of the future. The Guest Editors of this special issue on the future of manufacturing are strongly convinced that their undertaking has been worthwhile.

Rough-terrain groundspeed measurement:a radar-based commercial solution

Off-highway motive plant equipment is costly in capital outlay and maintenance. To reduce these overheads and increase site safety and workrate, a technique of assessing and limiting the velocity of such equipment is required. Due to the extreme environmental conditions met on such sites, conventional velocity measurement techniques are inappropriate. Ogden Electronics Limited were formed specifically to manufacture a motive plant safety system incorporating a speed sensor and sanction unit; to date, the only such commercial unit available. However, problems plague the reliability, accuracy and mass production of this unit. This project assesses the company's exisiting product, and in conjunction with an appreciation of the company history and structure, concludes that this unit is unsuited to its intended application. Means of improving the measurement accuracy and longevity of this unit, commensurate with the company's limited resources and experience, are proposed, both for immediate retrofit and for longer term use. This information is presented in the form of a number of internal reports for the company. The off-highway environment is examined; and in conjunction with an evaluation of means of obtaining a returned signal, comparisons of processing techniques, and on-site gathering of previously unavailable data, preliminary designs for an alternative product are drafted. Theoretical aspects are covered by a literature review of ground-pointing radar, vehicular radar, and velocity measuring systems. This review establishes and collates the body of knowledge in areas previously considered unrelated. Based upon this work, a new design is proposed which is suitable for incorporation into the existing company product range. Following production engineering of the design, five units were constructed, tested and evaluated on-site. After extended field trials, this design has shown itself to possess greater accuracy, reliability and versatility than the existing sensor, at a lower unit cost.

Isolation, characterisation and application of novel microbial protein cross-linking enzymes

Microbial transglutaminase is favoured for use in industry over the mammalian isoform, and hence has been utilized, to great effect, as an applied biocatalyst in many industrial areas including the food and textiles industries. There are currently only a limited number of microbial TGase sources known. A number of organisms have been screened for transglutaminase activity using biochemical assays directed towards TGase catalyzed reactions (amine incorporation and peptide cross-linking assay). Of those organisms screened, TGase was identified in a number of isolates including members of the Bacillus and Streptomyces families. In addition, a protein capable of performing a TGase-like reaction was identified in the organism Pseudomonas putida that was deemed immunologically distinct from previously described TGase isoforms, though further work would be required to purify the protein responsible. The genuses Streptoverticillium and Streptomyces are known to be closely related. A number of micro-organisms relating to Streptomyces mobaraensis (formerly Streptoverticillium mobaraensis) have been identified as harboring a TGase enzyme. The exact biological role of Streptomyces TGase is not well understood, though from work undertaken here it would appear to be involved in cell wall growth. Comparison of the purified Streptomyces TGase proteins showed them to exhibit marginally different characteristics in relation to enzymatic activity and pH dependency upon comparison with Streptomyces mobaraensis TGase. In addition, TGase was identified in the organism Saccharomonospora viridis that was found to be genetically identical to that from S. mobaraensis raising questions about the enzymes dissemination in nature. TGase from S. baldaccii was found to be most diverse with respect to enzymatic characteristics whilst still retaining comparable E(y-glutamyl) lysine bond formation to S. mobaraensis TGase. As such S. baldaccii TGase was cloned into an expression vector enabling mass production of the enzyme thereby providing a viable alternative to S. mobaraensis TGase for many industrial processes.

Singapore's online retail deviants:analyzing the rise of blogshops' power

Geography, retailing, and power are institutionally bound up together. Within these, the authors situate their research in Clegg's work on power. Online shopping offers a growing challenge to the apparent hegemony of traditional physical retail stores' format. While novel e-formats appear regularly, blogshops in Singapore are enjoying astonishing success that has taken the large retailers by surprise. Even though there are well-developed theoretical frameworks for understanding the role of institutional entrepreneurs and other major stakeholders in bringing about change and innovation, much less attention has been paid to the role of unorganized, nonstrategic actors-such as blogshops-in catalyzing retail change. The authors explore how blogshops are perceived by consumers and how they challenge the power of other shopping formats. They use Principal Components Analysis to analyze results from a survey of 349 blogshops users. While the results show that blogshops stay true to traditional online shopping attributes, deviations occur on the concept of value. Furthermore, consumer power is counter intuitively found to be strongly present in the areas related to cultural ties, excitement, and search for individualist novelty (as opposed to mass-production), thereby encouraging researchers to think critically about emerging power behavior in media practices.

Holonic supply chain:a study from family-based manufacturing perspective

In the contemporary business environment, to adhere to the need of the customers, caused the shift from mass production to mass-customization. This necessitates the supply chain (SC) to be effective flexible. The purpose of this paper is to seek flexibility through adoption of family-based dispatching rules under the influence of inventory system implemented at downstream echelons of an industrial supply chain network. We compared the family-based dispatching rules in existing literature under the purview of inventory system and information sharing within a supply chain network. The dispatching rules are compared for Average Flow Time performance, which is averaged over the three product families. The performance is measured using extensive discrete event simulation process. Given the various inventory related operational factors at downstream echelons, the present paper highlights the importance of strategically adopting appropriate family-based dispatching rule at the manufacturing end. In the environment of mass customization, it becomes imperative to adopt the family-based dispatching rule from the system wide SC perspective. This warrants the application of intra as well as inter-echelon information coordination. The holonic paradigm emerges in this research stream, amidst the holistic approach and the vital systemic approach. The present research shows its novelty in triplet. Firstly, it provides leverage to manager to strategically adopting a dispatching rule from the inventory system perspective. Secondly, the findings provide direction for the attenuation of adverse impact accruing from demand amplification (bullwhip effect) in the form of inventory levels by appropriately adopting family-based dispatching rule. Thirdly, the information environment is conceptualized under the paradigm of Koestler's holonic theory.

Synthesis and characterisation of polyacrylonitrile and its derived carbon materials

Carbon is a versatile material which is composed of different allotropes, and also come in with different structures. Carbon nanofibres (CNFs) is one dimensional carbon nanomaterials, which have exhibited superior mechanical properties, great specific area, good electrical conductivity, good biocompatibility, and ease of modification. In addition to the lower cost associated to compare with carbon nanotubes (CNTs), CNFs have been attracted in numerous applications, such as reinforcement materials, filtrations, Li-ion battery, supercapacitor as well as tissue engineering, just to list a few. Therefore, it is a great deal to understand the relationship between the fabrication conditions and the characteristics of the resulted CNFs. In this project, electrospun PAN NFs were used as precursor material to fabricate carbon nanofibres. In order to produce CNFs with good morphology, the processing parameters of PAN nanofibres by electrospinning was optimized toward to the morphology at solution concentration of 12 wt%. The optimized processing parameters at given concentration were 16 kV, 14 cm and 1.5 mL/h, which led to the formation of PAN NFs with average fibre diameter of approximately 260 nm. Along with the effect of processing parameter study, the effect of concentration on the morphology was also carried out at optimized processing parameters. It was found that by increasing concentration of PAN solution from 2 to 16%, the resulted PAN transformed from beads only, to beaded fibres and finally to smooth fibres. With further increasing concentration the morphology of smooth fibres remain with increase in the fibre diameter. Electrospun PAN NFs with average fibre of 306 nm was selected to be converted into CNFs by using standard heating procedures, stabilisation in air at 280 °C and carbonization in N2. The effect of carbonization temperature ranging from 500 to 1000 °C was investigated, by using SEM, FTIR, Raman, and Impedance spectroscopy. With increasing carbonization temperature from 500 to 1000 °C, the diameter of NFs was decreased from 260 to 187, associated with loss of almost all functional groups of NFs. It was indicated by Raman results, that the graphitic crystallite size was increased from 2.62 to 5.24 nm, and the activation energy obtained for this growth was 7570 J/mol. Furthermore, impedance results (i.e. Cole-Cole plot) revealed that the electrical characteristic of CNFs transitioned from being insulating to electrically conducting in nature, suggested by the different electrical circuits extracted from Cole-Cole plots with carbonization temperature from 500 to 800 °C. The carbonization on PAN NFs with diameter of ~431nm was carried out by using novel route, microwave plasma enhance chemical vapour deposition (MPECVD) process. To compare with carbonized PAN NFs by using conventional route, MPECVD was not only able to facilitate carbonization process, but more interestingly can form carbon nanowalls (CNWs) grown on the surfaces of carbonized PAN NFs. Suggested by the unique morphology, the potential applications for the resulted carbon fibrous hybrid materials are supercapacitor electrode material, filtrations, and etc., The method developed in this project required one step less, compared with other literature. Therefore, using MPECVD on stabilised PAN NFs is proposed as economical, and straightforward approach towards mass production of carbon fibrous hybrid materials containing CNWs.

Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs. © 2013 American Institute of Physics.

The development and optimisation of a fast pyrolysis process for bio-oil production

A two-tier study is presented in this thesis. The first involves the commissioning of an extant but at the time, unproven bubbling fluidised bed fast pyrolysis unit. The unit was designed for an intended nominal throughput of 300 g/h of biomass. The unit came complete with solids separation, pyrolysis vapour quenching and oil collection systems. Modifications were carried out on various sections of the system including the reactor heating, quenching and liquid collection systems. The modifications allowed for fast pyrolysis experiments to be carried out at the appropriate temperatures. Bio-oil was generated using conventional biomass feedstocks including Willow, beechwood, Pine and Miscanthus. Results from this phase of the research showed however, that although the rig was capable of processing biomass to bio-oil, it was characterised by low mass balance closures and recurrent operational problems. The problems included blockages, poor reactor hydrodynamics and reduced organic liquid yields. The less than optimal performance of individual sections, particularly the feed and reactor systems of the rig, culminated in a poor overall performance of the system. The second phase of this research involved the redesign of two key components of the unit. An alternative feeding system was commissioned for the unit. The feed system included an off the shelf gravimetric system for accurate metering and efficient delivery of biomass. Similarly, a new bubbling fluidised bed reactor with an intended nominal throughput of 500g/h of biomass was designed and constructed. The design leveraged on experience from the initial commissioning phase with proven kinetic and hydrodynamic studies. These units were commissioned as part of the optimisation phase of the study. Also as part of this study, two varieties each, of previously unreported feedstocks namely Jatropha curcas and Moringa olifiera oil seed press cakes were characterised to determine their suitability as feedstocks for liquid fuel production via fast pyrolysis. Consequently, the feedstocks were used for the production of pyrolysis liquids. The quality of the pyrolysis liquids from the feedstocks were then investigated via a number of analytical techniques. The oils from the press cakes showed high levels of stability and reduced pH values. The improvements to the design of the fast pyrolysis unit led to higher mass balance closures and increased organic liquid yields. The maximum liquid yield obtained from the press cakes was from African Jatropha press cake at 66 wt% on a dry basis.

The effect of antifoams upon recombinant protein production in yeast

Foaming during fermentation reduces the efficiency of the process leading to increased costs and reduced productivity. Foaming can be overcome by the use of chemical antifoaming agents, however their influence upon the growth of organisms and protein yield is poorly understood. The objective of this work was to evaluate the effects of different antifoams on recombinant protein production. Antifoam A, Antifoam C, J673A, P2000 and SB2121 were tested at different concentrations for their effect on the growth characteristics of Pichia pastoris producing GFP, EPO and A2aR and the yield of protein in shake flasks over 48 h. All antifoams tested increased the total GFP in the shake flasks compared to controls, at higher concentrations than would normally be used for defoaming purposes. The highest yield was achieved by adding 1 % P2000 which nearly doubled the total yield followed by 1 % SB2121, 1 % J673A, 0.6 % Antifoam A and lastly 0.8 % Antifoam C. The antifoams had a detrimental effect upon the production of EPO and A2aR in shake flasks, suggesting that their effects may be protein specific. The mechanisms of action of the antifoams was investigated and suggested that although the volumetric mass oxygen transfer coefficient (kLa) was influenced by the agents, their effect upon the concentration of dissolved oxygen did not contribute to the changes in growth or recombinant protein yield. Findings in small scale also suggested that antifoams of different compositions such as silicone polymers and alcoxylated fatty acid esters may influence growth characteristics of host organisms and the ability of the cells to secrete recombinant protein, indirectly affecting the protein yield. Upon scale-up, the concentration effects of the antifoams upon GFP yield in bioreactors was reversed, with lower concentrations producing a higher yield. These data suggest that antifoam can affect cells in a multifactorial manner and highlights the importance of screening for optimum antifoam types and concentrations for each bioprocesses.

Fast pyrolysis and nitrogenolysis of biomass and biogenic residues:production of a sustainable slow release fertiliser

The production of agricultural and horticultural products requires the use of nitrogenous fertiliser that can cause pollution of surface and ground water and has a large carbon footprint as it is mainly produced from fossil fuels. The overall objective of this research project was to investigate fast pyrolysis and in-situ nitrogenolysis of biomass and biogenic residues as an alternative route to produce a sustainable solid slow release fertiliser mitigating the above stated problems. A variety of biomasses and biogenic residues were characterized by proximate analysis, ultimate analysis, thermogravimetric analysis (TGA) and Pyrolysis – Gas chromatography – Mass Spectroscopy (Py–GC–MS) for their potential use as feedstocks using beech wood as a reference material. Beech wood was virtually nitrogen free and therefore suitable as a reference material as added nitrogen can be identified as such while Dried Distillers Grains with Solubles (DDGS) and rape meal had a nitrogen content between 5.5wt.% and 6.1wt.% qualifying them as high nitrogen feedstocks. Fast pyrolysis and in-situ nitrogenolysis experiments were carried out in a continuously fed 1kg/h bubbling fluidized bed reactor at around 500°C quenching the pyrolysis vapours with isoparaffin. In-situ nitrogenolysis experiments were performed by adding ammonia gas to the fast pyrolysis reactor at nominal nitrogen addition rates between 5wt.%C and 20wt.%C based on the dry feedstock’s carbon content basis. Mass balances were established for the processing experiments. The fast pyrolysis and in-situ nitrogenolysis products were characterized by proximate analysis, ultimate analysis and GC– MS. High liquid yields and good mass balance closures of over 92% were obtained. The most suitable nitrogen addition rate for the in-situ nitrogenolysis experiments was determined to be 12wt.%C on dry feedstock carbon content basis. However, only a few nitrogen compounds that were formed during in-situ nitrogenolysis could be identified by GC–MS. A batch reactor process was developed to thermally solidify the fast pyrolysis and in-situ nitrogenolysis liquids of beech wood and Barley DDGS producing a brittle solid product. This was obtained at 150°C with an addition of 2.5wt% char (as catalyst) after a processing time of 1h. The batch reactor was also used for modifying and solidifying fast pyrolysis liquids derived from beech wood by adding urea or ammonium phosphate as post processing nitrogenolysis. The results showed that this type of combined approach was not suitable to produce a slow release fertiliser, because the solid product contained up to 65wt.% of highly water soluble nitrogen compounds that would be released instantly by rain. To complement the processing experiments a comparative study via Py–GC–MS with inert and reactive gas was performed with cellulose, hemicellulose, lignin and beech wood. This revealed that the presence of ammonia gas during analytical pyrolysis did not appear to have any direct impact on the decomposition products of the tested materials. The chromatograms obtained showed almost no differences between inert and ammonia gas experiments indicating that the reaction between ammonia and pyrolysis vapours does not occur instantly. A comparative study via Fourier Transformed Infrared Spectroscopy of solidified fast pyrolysis and in-situ nitrogenolysis products showed that there were some alterations in the spectra obtained. A shift in frequencies indicating C=O stretches typically related to the presence of carboxylic acids to C=O stretches related to amides was observed and no double or triple bonded nitrogen was detected. This indicates that organic acids reacted with ammonia and that no potentially harmful or non-biodegradable triple bonded nitrogen compounds were formed. The impact of solid slow release fertiliser (SRF) derived from pyrolysis and in-situ nitrogenolysis products from beech wood and Barley DDGS on microbial life in soils and plant growth was tested in cooperation with Rothamsted Research. The microbial incubation tests indicated that microbes can thrive on the SRFs produced, although some microbial species seem to have a reduced activity at very high concentrations of beech wood and Barley DDGS derived SRF. The plant tests (pot trials) showed that the application of SRF derived from beech wood and barley DDGS had no negative impact on germination or plant growth of rye grass. The fertilizing effect was proven by the dry matter yields in three harvests after 47 days, 89 days and 131 days. The findings of this research indicate that in general a slow release fertiliser can be produced from biomass and biogenic residues by in-situ nitrogenolysis. Nevertheless the findings also show that additional research is necessary to identify which compounds are formed during this process.

Age-related macular degeneration and modification of systemic complement factor H production through liver transplantation

Purpose: To investigate whether modification of liver complement factor H (CFH) production, by alteration of liver CFH Y402H genotype through liver transplantation (LT), influences the development of age-related macular degeneration (AMD). Design: Multicenter, cross-sectional study. Participants: We recruited 223 Western European patients ≥55 years old who had undergone LT ≥5 years previously. Methods: We determined AMD status using a standard grading system. Recipient CFH Y402H genotype was obtained from DNA extracted from recipient blood samples. Donor CFH Y402H genotype was inferred from recipient plasma CFH Y402H protein allotype, measured using enzyme-linked immunosorbent assays. This approach was verified by genotyping donor tissue from a subgroup of patients. Systemic complement activity was ascertained by measuring levels of plasma complement proteins using an enzyme-linked immunosorbent assay, including substrates (C3, C4), activation products (C3a, C4a, and terminal complement complex), and regulators (total CFH, C1 inhibitor). Main Outcome Measures: We evaluated AMD status and recipient and donor CFH Y402H genotype. Results: In LT patients, AMD was associated with recipient CFH Y402H genotype (P = 0.036; odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.4) but not with donor CFH Y402H genotype (P = 0.626), after controlling for age, sex, smoking status, and body mass index. Recipient plasma CFH Y402H protein allotype predicted donor CFH Y402H genotype with 100% accuracy (n = 49). Plasma complement protein or activation product levels were similar in LT patients with and without AMD. Compared with previously reported prevalence figures (Rotterdam Study), LT patients demonstrated a high prevalence of both AMD (64.6% vs 37.1%; OR, 3.09; P<0.001) and the CFH Y402H sequence variation (41.9% vs 36.2%; OR, 1.27; P = 0.014). Conclusions: Presence of AMD is not associated with modification of hepatic CFH production. In addition, AMD is not associated with systemic complement activity in LT patients. These findings suggest that local intraocular complement activity is of greater importance in AMD pathogenesis. The high AMD prevalence observed in LT patients may be associated with the increased frequency of the CFH Y402H sequence variation. © 2013 by the American Academy of Ophthalmology Published by Elsevier Inc.

Evidence of lipid degradation during overnight contact lens wear:gas chromatography mass spectrometry as the diagnostic tool

Purpose. We investigated structural differences in the fatty acid profiles of lipids extracted from ex vivo contact lenses by using gas chromatography mass spectrometry (GCMS). Two lens materials (balafilcon A or lotrafilcon A) were worn on a daily or continuous wear schedule for 30 and 7 days. Methods. Lipids from subject-worn lenses were extracted using 1:1 chloroform: methanol and transmethylated using 5% sulfuric acid in methanol. Fatty acid methyl esters (FAMEs) were collected using hexane and water, and analyzed by GCMS (Varian 3800 GC, Saturn 2000 MS). Results. The gas chromatograms of lens extracts that were worn on a continuous wear schedule showed two predominant peaks, C16:0 and C18:0, both of which are saturated fatty acids. This was the case for balafilcon A and lotrafilcon A lenses. However, the gas chromatograms of lens extracts that were worn on a daily wear schedule showed saturated (C16:0, C18:0) and unsaturated (C16:1 and C18:1) fatty acids. Conclusions. Unsaturated fatty acids are degraded during sleep in contact lenses. Degradation occurred independently of lens material or subject-to-subject variability in lipid deposition. The consequences of lipid degradation are the production of oxidative products, which may be linked to contact lens discomfort. © 2014 The Association for Research in Vision and Ophthalmology, Inc.

Hierarchical porous catalysts tailored for biodiesel production

There is a pressing need for sustainable transportation fuels to combat both climate change and dwindling fossil fuel reserves. Biodiesel, synthesised from non-food plant (e.g., Jatropha curcas) or algal crops is one possible solution, but its energy efficient production requires design of new solid catalysts optimized for the bulky triglyceride and fatty acid feedstocks. Here we report on the synthesis of hierarchical macroporous-mesoporous silica and alumina architectures, and their subsequent functionalization by propylsulfonic acid groups or alkaline earth oxides to generate novel solid acid and base catalysts. These materials possess high surface areas and well-defined, interconnected macro-mesopore networks with respective narrow pore size distributions tuneable around 300 nm and 5 nm. Their high conductivity and improved mass transport characteristics enhance activity towards transesterification of bulky tricaprylin and palmitic acid esterification, over mesoporous analogues. This opens the way to the wider application of hierarchical catalysts in biofuel synthesis and biomass conversion.

Hydrogen production by steam reforming of DME in a large scale CFB reactor. Part I:computational model and predictions

This study presents a computational fluid dynamic (CFD) study of Dimethyl Ether steam reforming (DME-SR) in a large scale Circulating Fluidized Bed (CFB) reactor. The CFD model is based on Eulerian-Eulerian dispersed flow and solved using commercial software (ANSYS FLUENT). The DME-SR reactions scheme and kinetics in the presence of a bifunctional catalyst of CuO/ZnO/Al2O3+ZSM-5 were incorporated in the model using in-house developed user-defined function. The model was validated by comparing the predictions with experimental data from the literature. The results revealed for the first time detailed CFB reactor hydrodynamics, gas residence time, temperature distribution and product gas composition at a selected operating condition of 300 °C and steam to DME mass ratio of 3 (molar ratio of 7.62). The spatial variation in the gas species concentrations suggests the existence of three distinct reaction zones but limited temperature variations. The DME conversion and hydrogen yield were found to be 87% and 59% respectively, resulting in a product gas consisting of 72 mol% hydrogen. In part II of this study, the model presented here will be used to optimize the reactor design and study the effect of operating conditions on the reactor performance and products.