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2 3Sustainable development is subjective and value laden, and achieving it involves balancing a complex system of issues. Most existing approaches to assessing and managing sustainability fail to address sustainability in the particular context of a project and its stakeholders. A more holistic, 'systems approach' is required to address sustainability effectively. The Halcrow sustainability toolkit and rating (Halstar) system has been designed to provide a truly holistic methodology, incorporating many of the features of existing approaches, while attempting to mitigate their disadvantages. Halstar provides a common framework to support decision-making, enabling the comprehensive assessment and management of sustainable development issues. The technique works to improve sustainability on projects and programmes by guiding decision-making and appraisal within unique contexts and priorities. It ensures that sustainability, rather than being an add-on to the development process, becomes a source of added value. This paper outlines the rationale behind the development of Halstar and includes a case study demonstrating one of the ways it can be applied.

The rise of multidrug-resistant bacteria is the biggest threat to human health globally, as described by the World Health Organization. Mechanobactericidal surfaces provide a sustainable approach to addressing this concern by eradicating pathogens, especially bacteria, “right-at-the-point” of contacting the surface. However, the lack of a “design to manufacture” approach due to our limited understanding of the mechanobactericidal mechanism has impeded engineering optimization to develop scalable exploitation routes in various healthcare applications. It can be argued that the reason, most particularly, is the limitations and uncertainties associated with the current instrumentation and simulation capabilities, which has led to several streams of test protocols. This review highlights the current understanding on the mechanobactericidal mechanisms in light of the contributing factors and various techniques that are used to postulate these mechanisms. The review offers a critique on the variations observed on how nanostructured surfaces found in the literature have been evaluated such that the test protocols and outcomes are incomparable. The review also shows a strong need for developing more accurate models of a bacterium because the currently reported experimental data are insufficient to develop bacterial material models (constitutive equations). The review also alludes to the scarcity of direct experimental evidence of the mechanobactericidal mechanism, suggesting a strong need for further in situ monitoring as a future research direction.

Progress made by materials scientists in recent years has greatly helped the field of ultra-precision manufacturing. Ranging from healthcare to electronics components, phenomena such as twinning, dislocation nucleation, and high-pressure phase transformation have helped to exploit plasticity across a wide range of metallic and semiconductor materials. One current problem at the forefront of the healthcare sector that can benefit from these advances is that of bacterial infections in implanted prosthetic devices. The treatment of implant infections is often complicated by the growth of bacterial biofilms on implant surfaces, which form a barrier that effectively protects the infecting organisms from host immune defenses and exogenous antibiotics. Further surgery is usually required to disrupt the biofilm, or to remove the implant altogether to permit antibiotics to clear the infection, incurring considerable cost and healthcare burdens. In this review, we focus on elucidating aspects of bactericidal surfaces inspired by the biological world to inform the design of implant surface treatments that will suppress bacterial colonization. Alongside manufacturing and materials related challenges, the review identifies the most promising natural bactericidal surfaces and provides representative models of their structure, highlighting the importance of the critical slope presented by these surfaces. The scalable production of these complex hierarchical structures on freeform metallic implant surfaces has remained a scientific challenge to date and, as identified by this review, is one of the many 21 st -century puzzles to be addressed by the field of applied physics.

Extreme weather events, such as the UK floods of 2007 and cold snap of 2010–2011, stress the importance of infrastructure systems' resilience for business continuity. The interconnected nature of critical national infrastructure and its component parts places demands on the approach used to deal with its subsequent complexity. Recognition of infrastructure as a complex adaptive system has led to the development of an innovative, systems-based methodology for sustainability assessment in the built environment. The methodology consists of a database of causal interactions which, when combined with a process, allows users to produce causal loop diagrams that identify unanticipated systemic behaviour, communicate risks, share knowledge, and identify systemic intervention points that minimise negative consequences and add value in a project context. The approach is applied to highlight the key characteristics of complex adaptive systems that critical national infrastructure exhibits and show how the technique can be used to increase infrastructure resilience and sustainability.