Wavelength Dependence of Raman Enhancement from Gold Nanorod Arrays: Quantitative Experiment and Modeling of a Hot Spot Dominated System

Surface-enhanced Raman scattering (SERS) spectra from molecules adsorbed on the surface of vertically aligned gold nanorod arrays exhibit a variation in enhancement factor (EF) as a function of excitation wavelength that displays little correlation with the elastic optical properties of the surface. The key to understanding this lack of correlation and to obtaining agreement between experimental and calculated EF spectra lies with consideration of randomly distributed, sub-10 nm gaps between nanorods forming the substrate. Intense fields in these enhancement “hot spots” make a dominant contribution to the Raman scattering and have a very different spectral profile to that of the elastic optical response. Detailed modeling of the electric field enhancement at both excitation and scattering wavelengths was used to quantitatively predict both the spectral profile and the magnitude of the observed EF.

Teaching and learning technologies in Higher Education: Applied behaviour analysis and autism.

Professionals on both international and national levels who work with children with autism are expressing the need for graduate-level training in applied behaviour analysis. The implementation of effective instruction in higher education for professionals working with children with autism and their families is a complex undertaking: the learner needs to acquire an understanding of the principles and procedures of applied behaviour analysis and also adapt this knowledge to the learning prerequisites of individuals with autism. In this paper we outline some current thinking about adult education and blended learning technologies and then describe and illustrate with examples emerging possibilities of multimedia technology in the development of teaching materials. We conclude that synergies between graduate-level curriculum requirements, knowledge of adult learning, and communication technology are necessary to establish comprehensive learning environments for professionals who specialize in autism intervention.

A Human Rights Perspective on Citizen Participation in the EU's Governance of New Technologies

This article considers the EU’s approach to citizen participation in the governance of new technologies from a human rights perspective. Noting that there is a dearth of insight on the interplay between citizen participation and human rights, the article sketches the essence of its own human rights perspective as being about empowerment. This perspective is brought to bear on EU discourse on citizen participation in the governance of new technologies. Analysis of the discourse—comprising law, citizen participation in EU governance and citizen/science relations, the ‘public understanding of science and technology’, risk and bioethics—reveals a disempowering ‘deficit model’ of citizens in need of education through their participation in governance. The analysis thus suggests that citizen participation in EU governance of new technologies is not truly informed by human rights, but is instead used as a legitimating technique.

Impact of gate-source/drain channel architecture on the performance of an operational transconductance amplifier (OTA)

In this work, we report on the significance of gate-source/drain extension region (also known as underlap design) optimization in double gate (DG) FETs to improve the performance of an operational transconductance amplifier (OTA). It is demonstrated that high values of intrinsic voltage gain (A(VO_OTA)) > 55 dB and unity gain frequency (f(T_OTA)) similar to 57 GHz in a folded cascode OTA can be achieved with gate-underlap channel design in 60 nm DG MOSFETs. These values correspond to 15 dB improvement in A(VO_OTA) and three fold enhancement in f(T_OTA) over a conventional non-underlap design. OTA performance based on underlap single gate SOI MOSFETs realized in ultra-thin body (UTB) and ultra-thin body BOX (UTBB) technologies is also evaluated. A(VO_OTA) values exhibited by a DG MOSFET-based OTA are 1.3-1.6 times higher as compared to a conventional UTB/UTBB single gate OTA. f(T_OTA) values for DG OTA are 10 GHz higher for UTB OTAs whereas a twofold improvement is observed with respect to UTBB OTAs. The simultaneous improvement in A(VO_OTA) and f(T_OTA) highlights the usefulness of underlap channel architecture in improving gain-bandwidth trade-off in analog circuit design. Underlap channel OTAs demonstrate high degree of tolerance to misalignment/oversize between front and back gates without compromising the performance, thus relaxing crucial process/technology-dependent parameters to achieve 'idealized' DG MOSFETs. Results show that underlap OTAs designed with a spacer-to-straggle (s/sigma) ratio of 3.2 and operated below a bias current (IBIAS) of 80 mu A demonstrate optimum performance. The present work provides new opportunities for realizing future ultra-wide band OTA design with underlap DG MOSFETs.

Remediation technologies for heavy metal contaminated ground water

This is a major review work on ground water remediation since the earlier work of Mulligan et al published in 2001 in Engineering Geology Journal. This work resulted from the joint research project of QUB and University of Malaya on iron removal from groundwater for public water supply.

Near-field enhancement for infrared sensor applications

A detailed investigation on planar two dimensional metallodielectric dipole arrays with enhanced near-fields for sensing applications was carried out. Two approaches for enhancing the near-fields and increasing the quality factor were studied. The reactive power stored in the vicinity of the array at resonance increases rapidly with increasing periodicity. Higher quality factors are produced as a result. The excitation of the odd mode in the presence of a perturbation gives rise to a sharp resonance with near-field enhanced by at least an order of magnitude compared to unperturbed arrays. The trade-off between near-field enhancement and thermal losses was also studied, and the effect of supporting dielectric layers on thermal losses and quality factors were examined. Secondary transmissions due to the dielectric alone were found to enhance and reduce cyclically the quality factor as a function of the thickness of the dielectric material. The performance of a perturbed frequency selective surface in sensing nearby materials was investigated. Finally, unperturbed and perturbed arrays working at infrared frequencies were demonstrated experimentally. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3604785]