Comparison of surface-enhanced resonance Raman scattering from unaggregated and aggregated nanoparticles

The effect of excitation frequency and state of aggregation on the sensitivity obtained in ultratrace analysis using colloidal suspensions of silver nanoparticles and surface-enhanced resonance Raman scattering (SERRS) detection is explored to define suitable conditions for quantitative analysis. Two structurally similar dyes, only one of which causes aggregation, were used as analytes without the use of external aggregating agents, thus simplifying the surface chemistry and removing a major source of error. Addition of the nonaggregating dye caused no change in particle charge or size and no time-dependent aggregation as measured by zeta potential and particle size analysis. The most intense single-particle scattering was obtained using excitation at the wavelength of the plasmon resonance. Molecular resonance added approximately 2 orders of magnitude in sensitivity. Addition of the aggregating dye caused a reduction in surface charge of the particles and initiated a time-dependent aggregation process. However, constant SERRS with time is obtained at some excitation wavelengths probably because a constant number of clusters active at these wavelengths is maintained in the dynamic aggregation process. The additional enhancement caused by aggregation and molecular resonance is spread over a range of excitation frequencies. However, electronic spectra suggested that plasmon resonance enhancement would be effective at the longest wavelength of excitation used (785 nm), but there was a significant drop in intensity this far away from the absorbance maximum of the dye (429 nm). Thus, sensitive analysis using suspensions of single nanoparticles is feasible provided the excitation frequency used is close to that of the plasmon resonance frequency. Aggregation adds only an enhancement of approximately 6 in the experiments performed since only some particles in aggregates will have an active plasmon at any one wavelength, but the range of excitation wavelengths at which good enhancement is obtained is wider giving more flexibility if more complexity.     

The Emotional Wardrobe

Since the industrial revolution, fashion and technology have been linked through the textile and manufacturing industries, a relationship that has propelled technical innovation and aesthetic and social change. Today, a new alliance is emerging through the integration of electronic technology and smart materials on the body. This study addresses the integration of technology with clothing from a fashion perspective, and examines its expressive and interactive potential. It proposes the concept of The Emotional Wardrobe: clothing that represents and stimulates emotional response through the interface of technology. It asks if fashion can offer a more personal and provocative definition of self, which actively involves the wearer in a mutable aesthetic identity. A multi-disciplinary framework combines fashion, material science and the real-time, affective computing platform, called AffectiveWare. By merging technology and fashion, The Emotional Wardrobe becomes a poetic interface, shifting emphasis from human–computer interaction to computer-aided, human–human communication.     

Assessing forest fire as a potential PCDD/F source in Queensland, Australia

Forest fires are suggested as a potential and significant source of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), even though no studies to date provide sufficient evidence to confirm forest fires as a source of PCDD/Fs. Recent investigations in Queensland, Australia have identified a widespread contamination of PCDDs (in particular OCDD) in soils and sediments in the coastal region from an unknown source of PCDD/Fs. Queensland is predominately rural; it has few known anthropogenic sources of PCDD/Fs, whereas forest fires are a frequent occurrence. This study was conducted to assess forest fires as a potential source of the unknown PCDD/F contamination in Queensland. A combustion experiment was designed to assess the overall mass of PCDD/Fs before and after a simulated forest fire. The results from this study did not identify an increase in sigmaPCDD/Fs or OCDD after the combustion process. However, specific non-2,3,7,8 substituted lower chlorinated PCDD/Fs were elevated after the combustion process, suggesting formation from a precursor. The results from this study indicate that forest fires are unlikely to be the source of the unknown PCDD contamination in Queensland, rather they are a key mechanism for the redistribution of PCDD/Fs from existing sources and precursors.     

Resonance Raman spectroscopy of photolabile transition metal carbonyls: controlled photoalteration with continuous wave lasers to record spectra of reactants or transient species

A method has been developed that enables resonance Raman spectra of photolabile species in solution to be recorded under conditions where the level of photoalteration is controlled: a low level enables reactant spectra to be recorded, whereas a high level enables the spectra of short-lived transient species to be recorded in real time using continuous-wave (CW) lasers and standard Raman detection equipment. The design includes a sealed flow system, enabling air-sensitive species to be studied under an inert atmosphere. A simple theoretical model has been developed to aid the interpretation of experimental results, and its applicability is demonstrated. Controlled photoalteration and its theory are demonstrated with 413.1-nm excitation of carbonmonoxymyoglobin (MbCO), which generates deoxymyoglobin (deoxy-Mb) on photolysis, and for which the spectra of both species are well established. The methods have also been applied to two air-sensitive, photolabile transition metal carbonyls using 514.5-nm wavelength excitation: for Cp2Mo2(CO)6 (Cp = eta5-C5H5), increasing levels of photoalteration result only in a decrease in the parent band intensities, relative to the solvent bands; for Cp2Fe2(CO)4, increasing levels of photoalteration result in the appearance of additional bands that are assigned to the transient species CpFe(mu-CO)3FeCp, formed following the loss of a CO ligand.     

Dietary α-linolenic acid increases the n−3 PUFA content of sow's milk and the tissues of the suckling piglet

alpha-Linolenic acid (18:3n-3) is a precursor to DHA (22:6n-3), which is essential for normal growth and development in the infant. This study was undertaken to assess how a raised 18:3n-3 intake in sows affects the n-3 PUFA content of the suckling piglet. Sows consumed a high-18:3n-3 or control diet (n-3 PUFA/n-6 PUFA, 0.5 vs. 0.05, respectively) for 10 d prior to parturition and for 14 d postpartum. Piglets suckled from their mothers until 14 d of age, when they were sacrificed. Sows consuming the high-18:3n-3 diet had 141% more 18:3n-3 and 86% more 22:6n-3 in their milk compared to control sows. There was no difference in the proximate composition of the piglets. The n-3/n-6 PUFA ratio was 82% higher in the milk of sows consuming the high-18:3n-3 diet compared to controls. Piglets suckling from sows consuming the high-18:3n-3 diet had 423% more 18:3n-3 in the carcass as well as a 460% higher n-3/n-6 PUFA ratio than controls. The piglets suckling from sows consuming the high-18:3n-3 diet had 333% more 18:3n-3 and 54% more 22:6n-3 in the liver, as well as a 114% higher n-3/n-6 ratio than control piglets. Piglets suckling from sows consuming a high-18:3n-3 diet also had 24% more 22:6n-3 and a 33% higher n-3/n-6 ratio in the brain compared to control piglets. A high 18:3n-3 intake in the sow increases not only the 18:3n-3 but also the 22:6n-3 content of sow's milk and the tissues of the suckling piglet.     

Move to get moved: a search for methods,tools and knowledge to design for expressive and rich movement-based interaction

The world is inherently meaningful for us, i.e. we perceive the world in terms of what we can do with it, and by physically interacting with it we access this meaning and express the meaning. We believe that this is the core reason and foundation for turning to movement-based interaction. ‘Interaction creates meaning’ does not only hold for users during interaction but also for designers when generating ideas and developing concepts. Therefore, we postulate that if one truly likes to design for movement-based interaction, one has to be or become an expert in movement, not just theoretically, by imagination or on paper, but by doing and experiencing while designing. In order to do so, we believe that designers need design tools, techniques, knowledge, awareness and skills that support their search for expressive, rich behaviour. Our search for this support resulted in several methods, tools and knowledge that help designers exploring, visualising and reflecting on interactions. Our developed methods and tools such as the Design Movement approach with its choreography of interaction, gestural design tools, interactive installations and interactive tangible sketching, have not only supported and inspired designers to design for movement-based interaction, but also resulted in surprising, fresh designs in comparison with the limited scope of rather uniform and traditional electronic consumer products. This paper discusses the possibilities and limitations of our approach.     

A framework for testing first-order logic axioms in program verification

Program verification systems based on automated theorem provers rely on user-provided axioms in order to verify domain-specific properties of code. However, formulating axioms correctly (that is, formalizing properties of an intended mathematical interpretation) is non-trivial in practice, and avoiding or even detecting unsoundness can sometimes be difficult to achieve. Moreover, speculating soundness of axioms based on the output of the provers themselves is not easy since they do not typically give counterexamples. We adopt the idea of model-based testing to aid axiom authors in discovering errors in axiomatizations. To test the validity of axioms, users define a computational model of the axiomatized logic by giving interpretations to the function symbols and constants in a simple declarative programming language. We have developed an axiom testing framework that helps automate model definition and test generation using off-the-shelf tools for meta-programming, property-based random testing, and constraint solving. We have experimented with our tool to test the axioms used in Auto-Cert, a program verification system that has been applied to verify aerospace flight code using a first-order axiomatization of navigational concepts, and were able to find counterexamples for a number of axioms.