Colin Cunningham

When is a soil remediated? Comparison of biopiled and windrowed soils contaminated with bunker-fuel in a full-scale trial.

A six month field scale study was carried out to compare windrow turning and biopile techniques for the remediation of soil contaminated with bunker C fuel oil. End-point clean-up targets were defined by human risk assessment and ecotoxicological hazard assessment approaches. Replicate windrows and biopiles were amended with either nutrients and inocula, nutrients alone or no amendment. In addition to fractionated hydrocarbon analysis, culturable microbial characterisation and soil ecotoxicological assays were performed. This particular soil, heavy in texture and historically contaminated with bunker fuel was more effectively remediated by windrowing, but coarser textures may be more amendable to biopiling. This trial reveals the benefit of developing risk and hazard based approaches in defining end-point bioremediation of heavy hydrocarbons when engineered biopile or windrow are proposed as treatment option.

Adsorption of heavy metals by agroforestry waste derived activated carbons applied to aqueous solutions

Activated carbons prepared from macadamia nut shells, baobab shells, pigeon pea husks, rice husks, Moringa oleifera husks, and marula stones were investigated for their abilities to adsorb Pb(II), Zn(II), Cu(II), Ni(II), Fe(II), Mn(II), Hg(II), Cr(III), As(III) and Cd(II) from aqueous solutions. Batch adsorption experiments were conducted at pH values of 4, 5 and 6. Metal ion adsorption generally increased as the pH was increased from 4 to 6. Percentage adsorption values were above 60% for adsorption of Hg(II) by all the activated carbons at pH 6. The adsorption of Pb(II) by carbons from Baobab shells, pigeon pea husks, Moringa oleifera husks and Marula stones was at least 22% higher than that of the commercial carbons used for comparison. Carbons derived from pigeon pea husks and baobab shells showed better metal ion adsorption compared to the other carbons and were used to determine the effects of initial metal concentration, contact time and adsorbent quantity on metal adsorption. The metal ion adsorption data fitted the Langmuir adsorption model. Keywords: Agroforestry, wastes, activated, carbon, adsorption, metals African Journal of Biotechnology , Vol 13(14), 1579-1587

ELT instrument concepts: impact on telescope and adaptive optics design

We report on the development of instrument concepts for a European ELT, expanding on studies carried out as part of the ESO OWL concept. A range of instruments were chosen to demonstrate how an ELT could meet or approach the goals generated by the OPTICON science team, and used to push the specifications and requirements of telescope and adaptive optics systems. Preliminary conclusions are presented, along with a plan for further more detailed instrument design and technology developments. This activity is supported by the European Community (Framework Programme 6, ELT Design Study, contract number 011863).

Quantitative laser Doppler anemometry measurements of the shear-stresses exerted on ultrasonic microbubbles attached to surfaces under physiological flow conditions

Ultrasonic contrast agents are currently being developed to target and attach to specific sites of interest within the body. This paper presents microbubbles which have been developed and can be attached to agar surfaces. They have been successfully imaged with high frequency intravascular ultrasound at 40 MHz. A flow chamber has been developed for imaging attached microbubbles under flow conditions. To determine the shear stresses the microbubbles were subjected to in the flow chamber, and to investigate the shear stresses the microbubbles can withstand, laser Doppler anemometry (LDA) was used to determine the flow profile within the chamber. The shear stresses at 80, 90 and 100 ml min/sup -1/ were found. It is hoped to improve the resolution of the profiles obtained from LDA and to investigate increased flow rates and shear stresses.

The OPTICON technology roadmap for optical and infrared astronomy

The Key Technology Network (KTN) within the OPTICON programme has been developing a roadmap for the technology needed to meet the challenges of optical and infrared astronomy over the next few years, with particular emphasis on the requirements of Extremely Large Telescopes. The process and methodology so far will be described, along with the most recent roadmap. The roadmap shows the expected progression of ground-based astronomy facilities and the technological developments which will be required to realise these new facilities. The roadmap highlights the key stages in the development of these technologies. In some areas, such as conventional optics, gradual developments in areas such as light-weighting of optics will slowly be adopted into future instruments. In other areas, such as large area IR detectors, more rapid progress can be expected as new processing techniques allow larger and faster arrays. Finally, other areas such as integrated photonics have the potential to revolutionise astronomical instrumentation. Future plans are outlined, in particular our intention to look at longer term development and disruptive technologies.

ELT instrumentation for seeing-limited and AO-corrected observations: a comparison

The next generation of large ground-based optical and infrared telescopes will provide new challenges for designers of astronomical instrumentation. The varied science cases for these extremely large telescopes (ELTs) require a large range of angular resolutions, from near diffraction-limited performance via correction of atmospheric turbulence using adaptive optics (AO), to seeing-limited observations. Moreover, the scientific output of the telescopes must also be optimized with the consideration that, with current technology, AO is relatively ineffective at visible wavelengths, and that atmospheric conditions will often preclude high-performance AO. This paper explores some of the issues that arise when designing ELT instrumentation that operates across a range of angular-resolutions and wavelengths. We show that instruments designed for seeing-limited or seeing-enhanced observations have particular challenges in terms of size and mass, while diffraction-limited instruments are not as straightforward as might be imagined.

TECHBREAK: a technology foresight activity for the European Space Agency points the way to future space telescopes

We report on a joint European Science Foundation-ESA “Forward Look” project called TECHBREAK aimed at identifying technological breakthroughs for space originating in the non-space sector. We show how some of the technologies highlighted may impact future space programmes, in particular novel ideas to enable future long-life large telescopes to be deployed. The study’s final report was presented to ESA’s High level Science Policy Advisory Committee (HISPAC) in late 2014. The goals of the study were to forecast the development of breakthrough technologies to enable novel space missions in the 2030-2050 timeframe, and to identify related partnerships through synergies with non-space specialists. It was not prepared to serve as a definitive guide for very specific technologies to be developed for future space missions, but to inform on and flag up the main developments in various technological and scientific areas outside space that may hold promise for use in the space domain. The report does this by identifying the current status of research for each domain, asserting the development horizon for each technology and providing some entry points, in the form of key European experts and institutions with knowledge of the domain. The identification of problems and solutions specific to the space area led us to focus the discussion around the concept of “Overwhelming Drivers” for space research and exploration, i.e. long-term goals that can be transposed into technological development goals. Two of these overwhelming drivers are directly relevant to ambitious future telescope projects, and we will show how some of the technologies we identified such as biomimetic structures, nanophotonics, novel materials and additive manufacturing could be combined to enable revolutionary new concepts for space telescopes.

Developing ultrafast laser inscribed volume gratings

Due to their high efficiency and broad operational bandwidths, volume phase holographic gratings (VPHGs) are often the grating technology of choice for astronomical instruments, but current VPHGs exhibit a number of drawbacks including limits on their size, function and durability due to the manufacturing process. VPHGs are also generally made using a dichromated gelatine substrate, which exhibits reduced transmission at wavelengths longer than ~2.2 μm, limiting their ability to operate further into the mid-infrared. An emerging alternative method of manufacturing volume gratings is ultrafast laser inscription (ULI). This technique uses focused ultrashort laser pulses to induce a localised refractive index modification inside the bulk of a substrate material. We have recently demonstrated that ULI can be used to create volume gratings for operation in the visible, near-infrared and mid-infrared regions by inscribing volume gratings in a chalcogenide glass. The direct-write nature of ULI may then facilitate the fabrication of gratings which are not restricted in terms of their size and grating profile, as is currently the case with gelatine based VPHGs. In this paper, we present our work on the manufacture of volume gratings in gallium lanthanum sulphide (GLS) chalcogenide glass. The gratings are aimed at efficient operation at wavelengths around 1 μm, and the effect of applying an anti-reflection coating to the substrate to reduce Fresnel reflections is studied.

A multi-object multi-field spectrometer and imager for a European ELT

One of the highlights of the European ELT Science Case book is the study of resolved stellar populations, potentially out to the Virgo Cluster of galaxies. A European ELT would enable such studies in a wide range of unexplored, distant environments, in terms of both galaxy morphology and metallicity. As part of a small study, a revised science case has been used to shape the conceptual design of a multi-object, multi-field spectrometer and imager (MOMSI). Here we present an overview of some key science drivers, and how to achieve these with elements such as multiplex, AO-correction, pick-off technology and spectral resolution.

High frequency ultrasonic imaging and attachment of contrast agents under flow conditions

Background: Targeting of ultrasound contrast agents is an area of research which is continuously expanding. Contrast agents can be targeted to attach to markers expressed at areas of interest within the body. Areas of inflammation and molecules expressed at these areas are associated with unstable plaque in arteries. Imaging techniques to distinguish between unstable and stable plaques are currently unavailable. Previously a flow chamber was described which allowed high frequency ultrasonic imaging of contrast agents attached to surfaces while subjected to flow. A lipid based contrast agent which can be targeted to molecules expressed at areas of inflammation has been developed and attached to agar, under static conditions, using avidin and biotin. It was shown that the contrast agent remained attached to the agar under shear stresses of up to 3.4 Pa. The work presented here has involved attaching the contrast agent under flow conditions. Aim: To determine if the variation of biotin in the contrast agent shell affects attachment under flow conditions. Methods: Streptavidin coated agar samples were placed in the flow chamber. Biotinylated lipid contrast agents, 0.5 ml in 50 ml saline, were circulated through the flow chamber for 2 hours at a flow rate of 1.65 ml min -1 . The samples were imaged with 40 MHz intravascular ultrasound. Images and RF data were captured before and after circulation of the contrast agent. Contrast microbubbles containing 1%, 3% and 5% biotin were tested. Saline and un-biotinylated contrast agent were also circulated. Results: On the circulation of saline and un-biotinylated contrast agent over the streptavidin coated agar in the flow chamber, no enhancement was seen in the IVUS images. On circulation of the 1% biotinylated agent, enhancement of the agar surface was seen. After circulation of the 3% and 5% biotinylated contrast agents, again enhancement of the agar surface was seen, however, there was better coverage across the surface of the agar than for the 1% biotin agent. The raw RF data was used to determine the mean backscatter power from the agar surface, across the surface there was no significant increase seen after circulation of 1% biotin-agent. However, there was an increase in the mean backscatter power for the 3% and 5% biotinylated contrast agents.