Manufacture of Multilayered Artificial Cell Membranes through Sequential Bilayer Deposition on Emulsion Templates

Efforts to manufacture artificial cells that replicate the architectures, processes and behaviours of biological cells are rapidly increasing. Perhaps the most commonly reconstructed cellular structure is the membrane, through the use of unilamellar vesicles as models. However, many cellular membranes, including bacterial double membranes, nuclear envelopes, and organelle membranes, are multilamellar. Due to a lack of technologies available for their controlled construction, multilayered membranes are not part of the repertoire of cell-mimetic motifs used in bottom-up synthetic biology. To address this, we developed emulsion-based technologies that allow cell-sized multilayered vesicles to be produced layer-by-layer, with compositional control over each layer, thus enabling studies that would otherwise remain inaccessible. We discovered that bending rigidities scale with the number of layers and demonstrate inter-bilayer registration between coexisting liquid–liquid domains. These technologies will contribute to the exploitation of multilayered membrane structures, paving the way for incorporating protein complexes that span multiple bilayers.     

Book reviews

Nationality and Planning in Scotland and Wales. R. Macdonald & H. Thomas (Eds). Cardiff, University of Wales Press, 1997, 312 pp., hb £35.00, ISBN 0–7083–1398–1.

Urban Land and Property Markets in Sweden. Thomas Kalbro & Hans Mattsson. London, UCL Press, 1995, 208 pp., £48.00 hb, ISBN 1–85728–052–0.

Contested Countryside Cultures: Otherness, Marginalisation and Rurality. P. Cloke & J. Little (Eds). London, Routledge, 1997, 304 pp., £15.99 hb, ISBN 0–415–14075–7.     

Disinfection by-product formation after biologically assisted GAC treatment of water supplies with different bromide and DOC content

Chlorination of drinking water in the presence of bromide and dissolved organic carbon (DOC) leads to the formation of brominated and chlorinated disinfection by-products (DBP). The concentration of bromide ions in the raw water is a significant factor in the speciation of DBP formed, and causes shifts in trihalomethane (THM) formation from chlorinated to brominated species. Drinking water treatment techniques that remove organic contaminants without affecting bromide ion concentrations cause increases in the brominated THM. For the present study, three water supplies containing different DOC and ambient bromide concentrations were filtered through biologically assisted granular activated carbon (BGAC). Similar to adsorption and coagulation treatment, this treatment does not remove bromide from drinking water; also, THMFP (trihalomethane formation potential) analysis indicated that the chlorinated effluent contained higher concentrations of brominated THM in comparison to the influent. Although BGAC may increase the brominated THM, which may be more toxic than the chlorinated THM, the overall reduction of THMFP by DOC removal far exceeds this negative change, thereby producing a much less toxic finished drinking water. This work is part of a study to make high DOC surface waters on the Canadian prairie safe and palatable for small volume users (individuals or small communities).     

Review

THE EXPERIENCE OF NATURE: A PSYCHOLOGICAL PERSPECTIVE by Rachel Kaplan & Stephen Kaplan, Cambridge University Press, 1989, 337pp, £10.95 (p/b), 0-521-34939-7.

THE ECOLOGY OF URBAN HABITATS by 0. L. Gilbert, Chapman & Hall, London, 1989, 369pp, 0-412-28270-4, £35.00.

DIRECTORY FOR THE ENVIRONMENT: ORGANISATIONS IN BRITAIN AND IRELAND 1986-7, Michael J. C. Barker, ed., London: Routledge & Kegan Paul, 1986. Second edition, pp. xviii + 278, £18.99, PB, ISBN 0-7102-0961-4.

THE URBAN ENVIRONMENT: A SOURCEBOOK FOR THE 1990s, Gerald Dawe, ed., Birmingham: Centre for Urban Ecology, 1990, pp. 636, £55.00, PB, ISBN 0-907272-07-X.

PLANTS IN THE LANDSCAPE (2nd Edn.), by Philip L. Carpenter and Theodore D. Walker, W. H. Freeman, New York and Oxford, 1990, 401 pp., ISBN 0-7167-1808-1, £29.95 HB.

SPORTS GEOGRAPHY by John Bale, E. & F. N. Spon, 1989, 0-419-14390-4, £16.95 PB.

THE POLITICS OF PARK DESIGN: A HISTORY OF URBAN PARKS IN AMERICA by Galen Cranz, ISBN 0 262 53084 8, 347pp, London: M.I.T. Press, 1989, £11.25, P.B.     

Book reviews

Managing Cities. The New Urban Context. P. Healey, S. Cameron, S. Davoudi, S. Graham & A. Madani‐Pour (Eds) Chichester, John Wiley and Sons, 1995, £14.95 pb, ISBN 0–471–95533–7

Industrial Property: Policy and Economic Development. Rick Ball & Andy Pratt (Eds). London, Routledge, 1994, £45.00 hb, ISBN 0–415–09152–7

Grassroots Environmental Action: People's Participation in Sustainable Development. Dharam P. Ghai & Jessica M. Vivian (Eds). London and New York, Routledge, 1995 (pb), 347 pp., ISBN 0–415–12703–3

Services and Space: Key Aspects of Urban and Regional Development. N. Marshall & P. Wood. Essex, Longman Scientific and Technical, 1995, 294 pp., £17.99 pb, ISBN 0–582–25162–1

Servicing The Middle Classes: Class, Gender and Waged Domestic Labour in Contemporary Britain. Nicky Gregson & Michelle Lowe. Routledge, 1994, vii + 327 pp., £13.99 pb, ISBN 0–419–08531–4

Urban Development Planning: Lessons for the Economic Reconstruction of South Africa's Cities. Richard Tomlinson. Johannesburg, Witwatersrand University Press, 1994, 277 pp., £14.95 pb, ISBN 1–868–14258–2     

The Columnar-to-Equiaxed Transition in Melt Pools During Laser Powder Bed Fusion of M2 Steel

Metallurgical and Materials Transactions A - This work integrates experimental and numerical methods to determine the process conditions under which the columnar-to-equiaxed transition (CET)...     

Benefit evaluation for off‐site production in construction

Evaluating to what extent a component or building system should be produced off‐site is inadequate within the industry. The potential benefits of off‐site production (OSP) are commonly cited when justifying an OSP approach, yet holistic and methodical assessments of the applicability and overall benefit of these solutions, to a particular project, have been found to be deficient. Common methods of evaluation simply take material, labour and transportation costs into account when comparing various options, often disregarding other cost‐related items such as site facilities, crane use and rectification of works. These cost factors are usually buried within the nebulous preliminaries figure, with little reference to the building approach taken. Further, softer issues such as health and safety, effects on management and process benefits are either implicit or disregarded within these comparison exercises. Yet it is demonstrated that these issues are some of the most significant benefits of OSP. A series of case studies demonstrated that evaluation focus is almost solely on direct material and labour costs of components, without explicit regard for the wider cost or soft issue implications of OSP on a project. The paper argues that until evaluation is more holistic and value‐based rather than cost‐based, OSP uptake in construction will be slow.     

Motivation,commitment and the use of incentives in partnerships and alliances

The use of incentives in partnering and alliancing has been seen as an important way of reinforcing collaboration in the short term and helping to build trust between clients and contractors in the long term. Yet only rarely has the impact of incentives on such relationships been discussed, let alone subjected to systematic investigation. This is despite a wealth of theory and research which brings into question the use of incentives and reinforcers as ways of generating motivation and commitment. Drawing upon this theoretical knowledge base and using evidence from a number of case studies of partnerships and alliances, this paper demonstrates how a number of important cognitive and social dimensions affect the use and impact of incentives, sometimes in ways contrary to those intended. The conclusion drawn is that there are important limitations to the use of incentives as means of reinforcing collaboration and developing commitment and trust, and that this raises questions more generally about the assumptions that underlie many of the practical ‘tools and techniques’ commonly associated with partnering and alliancing.     

Designing for construction workers’ occupational health and safety: a case study of socio-material complexity

Drawing upon an empirical analysis of the design and construction of a food processing facility, a theoretical understanding of the impact of design decision-making on the occupational health and safety (OHS) of construction workers is developed. It is argued that current policy and legislative approaches to Construction Hazard Prevention through Design (CHPtD) are inherently limited because they do not adequately reflect the socio-material complexity of decision-making in construction design. Specifically, the simplistic attribution of responsibility to a single socio-technical actor, ‘the designer’, does not reflect the multiple and disparate influences that impact upon OHS outcomes. Nor do existing CHPtD policy frameworks, management processes and tools recognize the manner in which the interactions and associations between relevant project stakeholders and various non-human artefacts shape (and are also influenced by) the evolution of design decisions. Drawing on actor-network theory (ANT) and using embedded units within a case study approach, the interactions between human actors and non-human artefacts are explored in relation to the design of four components of the food processing facility. The way in which design decisions unfolded and shaped OHS experiences during the construction stage of the project is revealed. The research highlights limitations inherent in current approaches to the management of CHPtD and the need to develop a more robust theoretically based approach to integrating OHS considerations into construction design practice.     

Tunnel vision? Brunel's Thames Tunnel and project narratives

Looking at historical projects has much to offer our understanding of project management, for both research and practice. However, there are important challenges in how alternative narratives about such projects are reconstructed and related to each other. To explore these challenges, this paper uses the example of the Thames Tunnel project, completed under the direction of Marc Brunel in 1843, and reputed to be the first tunnel to be built under a major river. In telling the story of the project, we focus on five alternative discourses: technico-rational; practice; networks of people, things, and ideas; politics; and society. The common response to such variety is either to attempt to construct an overarching meta-narrative, or to explore the differences as a way of highlighting the localized and contingent nature of knowledge about projects, or adopt some intermediate position somewhere on the spectrum between these two extremes. Instead we seek a different route grounded in a sociology of knowledge that acknowledges simultaneous, provisional, and contested processes of division and stabilization in the ways that epistemic communities constitute knowledge through their own narratives and practices. These have implications for the stories that are told about project management and, crucially, the activities and interests that both shape and are shaped by such narratives.