Geosynthetics in Antarctica: performance of a composite barrier system to contain hydrocarbon-contaminated soil after three years in the field

An overview of the design and performance of geosynthetics in composite barrier systems for biopiles used to remediate hydrocarbon-contaminated soil at Casey Station, Antarctica, is presented. Seven instrumented biopiles were constructed over three field seasons. To minimize the risk of hydrocarbon migration to groundwater, composite barrier systems were used (each using different combinations of geosynthetic clay liners (GCLs), high density polyethylene (HDPE) geomembranes (GMB), and geotextiles (GTXs)). One biopile used a co-extruded geomembrane (HDPE with an ethylene vinyl alcohol (EVOH) core). The liner system was subject to a combination of coupled phenomena that could interact and affect the GMB-GCL composite barrier performance. The exposure conditions involved potential freeze-thaw cycling, hydration-desiccation cycles, cation exchange, direct and diffusive exposure to hydrocarbons. The effect of these phenomena was investigated by monitoring GCL and GMB sacrificial coupons. GCL coupons were placed between the main GCL component and the main geomembrane component of the composite liner and GMB coupons placed between the main GMB sheet and the GTX protection layer. Coupons were exhumed from the biopiles each year. The exhumed GCL field moisture content values ranged from 162% to 22%. After three (3) years in the field, GCL coupons that had undergone at least one hydration/desiccation cycle showed no significant change in swell index values or fluid loss values. The measured hydraulic conductivity of exhumed GCL coupons from Biopiles 1 and 2 (3 × 10-11 m s-1) was within the expected range and not significantly different from the values for virgin GCL. GMB coupons exhumed after three years from Biopiles 1 and 2 showed no significant change in oxidative induction time (OIT), melt flow index or tensile properties. Diffusion tests were performed as an index test for establishing the performance of the GMBs as a diffusive barrier to hydrocarbons, with permeation parameters for BTEX contaminants ranging from P g = 0.9-9.2 × 10-13 m2 s-1 for the exhumed GMB (with values depending on the contaminant and GMB). These values were similar to the parameters obtained for virgin GMBs and there was no significant change with field exposure, with GMBs appearing to be performing well.

Urban codes : abstraction and case-based approaches to algorithmic design and implications for the design of contemporary cities

This paper reports on a comparative study that evaluates two approaches to support the learning and use of algorithmic design in architecture, and extrapolates from this to consider applications for the algorithmic design of cities. The study explored two methods to reduce the barriers of using programming and potentially improve design performance. The first is the reuse of abstract algorithmic ‘patterns’. The second approach is the reuse of algorithmic solutions from specific design cases (case-based design). Reflecting on this research we outline how our findings discussed in relation to alternate thinking on the use of pattern, might inform a hybrid approach to the algorithmic design of cities.

A research agenda for design-based learning in engineering education

It is often argued that ‘design’ is an (perhaps the) essential characteristic of engineering practice; that, “Design requires unique knowledge, skills, and attitudes common to all engineering disciplines, and it is these attributes that distinguish engineering as a profession.” Hence, it is not surprising to see engineering design identified as a key element of engineering education. There are a range of pedagogical models described, badged with a range of names, that are suggested as approaches to teaching engineering design, for example: project-based learning, problem-based learning, design-based learning, conceive-design-implement-operate (CDIO), problem-oriented project-based learning, social design based learning and project-oriented, design-based learning. While significant literature on engineering design education generally exists, many authors note open questions regarding optimal pedagogical approaches, and opportunities for further evaluation and research. In this paper we draw on literature about design education and DBL in engineering education, and synthesise themes that present a potential research agenda for those educators involved in DBL in engineering education.A search of the research literature was conducted using terms related to DBL in engineering education, including ‘Engineering Design’, ‘Design Education’, ‘Engineering + Project Based Learning’, ‘Engineering + Problem Based Learning’ and ‘Engineering + Design Based Learning’. The literature thus collected was expanded by inspecting the lists of references in the initially identified literature set for further potentially relevant literature. This process was repeated until no further related literature was identified, and resulted in 124 items. All collected literature was carefully reviewed for explicitly identified suggestions for future research. The authors also considered the literature set as a whole to identify additional research possibilities implied by aspects of DBL practice commonly addressed weakly, or not at all, in the available published research. From the results of this review, a set of themes was synthesised by grouping related research recommendations and possibilities. In the following section the identified research themes are presented and, for each, a summary of the supporting literature is given and a central research question is formulated by the authors.

Towards enhanced performance thin-film composite membranes via surface plasma modification

Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

Investigating the issue of pollution in the micro-scale design of mega-cities : a case study of Enghelab Street, Tehran

Today there is a growing concern about urbanization and its impact on environmental pollution, which threatens human health and quality of life especially in mega cities. The mega city of Tehran, the capital of Iran, deals with various types of pollution. Although a large body of research has highlighted the significance of study on urban pollution in mega cities, only a few studies have addressed the issue at the micro scale. However, most of the research is restricted to air and noise pollution, whereas visual pollution as an important type of pollution that can be interpreted more deeply on a micro-scale, has been neglected. This study aims to evaluate some of the major issues of environmental pollution in Tehran by focusing on the micro-scale of the street. Therefore, as the central part of Tehran is one of the most affected divisions in the city, Enghelab Street has been selected as the case study for this research. This paper argues that identification and implementation of pollution mitigating strategies in Tehran’s master plan is not responsive enough to the whole city. This study of Enghelab Street reveals that policy making strategies for decreasing pollution should be initiated from micro-scale with further emphasis on psychological health. In the future, the lessons learned from the case study of Enghelab will help other major cities in developing countries to combat pollution through initiating from most affected districts in small scale.

Effectiveness of a care bundle to reduce central line-associated bloodstream infections

OBJECTIVE: To determine the effectiveness of a care bundle, with a novel line maintenance procedure, in reducing the rate of central line-associated bloodstream infection (CLABSI) in the intensive care unit (ICU).

DESIGN, PARTICIPANTS AND SETTING: Before-and-after study using CLABSI data reported to the Victorian Healthcare Associated Infection Surveillance System (VICNISS), in adult patients admitted to a tertiary adult ICU in regional Victoria between 1 July 2006 and 30 June 2014. VICNISS-reported CLABSI cases were reviewed for verification. An intervention was implemented in 2009.

INTERVENTION: The care bundle introduced in 2009 included a previously established line insertion procedure and a novel line maintenance procedure comprising Biopatch, daily 2% chlorhexidine body wash, daily ICU central line review, and liaison nurse follow-up of central lines.

MAIN OUTCOME MEASURES: CLABSI rate (cases per 1000 central line days). RESULTS: The average CLABSI rate fell from 2.2/1000 central line days (peak of 5.2/1000 central line days in quarter 4, 2008) during the pre-intervention period to 0.5/1000 central line days (0/1000 central line days from July 2012 to July 2014) during the post-intervention period.

CONCLUSION: Our study suggests that this care bundle, using a novel maintenance procedure, can effectively reduce the CLABSI rate and maintain it at zero out to 2 years.

Introduction to perspectives on architectural design research

If something called ‘design research’ was to begin tomorrow, what might we want it to encompass: how designers design, how they learn to design, what the limits and shapers of design might be? What other aspects of architectural activity should it deal with? Minimally, there is a range of possible social, cultural and environmental matters which could be considered and which certainly impinge on questions of why designing is undertaken and who, or what, it is for. But, such issues were central prior to there being something called ‘design research’. In grumpier moments over two decades it has been tempting to suspect some architects of using the term to fashionably relabel what they do. Enriched accounts, such as the range offered in this book, are required to clarify whether or not it is a useful construct. Since I am a fabricator and make things (up) as a way of designing, let me engage in a little fabricating around design research: tales of its history, present context, and of ideas for its future.

Graphene quantum dots and Nafion composite as an ultrasensitive electrochemical sensor for the detection of dopamine

A novel electrochemical sensor for highly sensitive and selective detection of dopamine (DA) was developed based on a graphene quantum dots (GQDs) and Nafion composite modified glassy carbon electrode (GCE). GQDs were synthesized by a hydrothermal approach for cutting graphene sheets into GQDs and characterized by TEM, UV-vis, photoluminescence, and FT-IR spectra. The GQDs had carboxyl groups with a negative charge, which not only provided good stability, but also enabled interaction with amine functional groups in DA through electrostatic interaction to enhance the specificity of DA. The interaction and electron communication between GQDs and DA can be further strengthened via π-π stacking force. Nafion was used as an anchoring agent to increase the robustness of GQDs on the electrode surface and sensor stability and reproducibility. The GQDs-Nafion composite exhibits a good linear range of 5 nM to 100 μM and a limit of detection as low as 0.45 nM in the detection of DA. The proposed electrochemical sensor also displays good selectivity and high stability and could be used for the determination of DA in real samples with satisfactory results. The present study provides a powerful avenue for the design of an ultrasensitive detection method for clinical application.