Atmospheric-pressure plasma jets : effect of gas flow, active species, and snake-like bullet propagation

Cold atmospheric-pressure plasma jets have recently attracted enormous interest owing to numerous applications in plasma biology, health care, medicine, and nanotechnology. A dedicated study of the interaction between the upstream and downstream plasma plumes revealed that the active species (electrons, ions, excited OH, metastable Ar, and nitrogen-related species) generated by the upstream plasma plume enhance the propagation of the downstream plasma plume. At gas flows exceeding 2 l/min, the downstream plasma plume is longer than the upstream plasma plume. Detailed plasma diagnostics and discharge species analysis suggest that this effect is due to the electrons and ions that are generated by the upstream plasma and flow into the downstream plume. This in turn leads to the relatively higher electron density in the downstream plasma. Moreover, high-speed photography reveals a highly unusual behavior of the plasma bullets, which propagate in snake-like motions, very differently from the previous reports. This behavior is related to the hydrodynamic instability of the gas flow, which results in non-uniform distributions of long-lifetime active species in the discharge tube and of surface charges on the inner surface of the tube.

Thermal effect of plasmon oscillations on the tunnel current in gold nanoisland thin film at low laser intensity

The effect of plasmon oscillations on the DC tunnel current in a gold nanoisland thin film (GNITF) is investigated using low intensity P~1W/cm2 continuous wave lasers. While DC voltages (1–150 V) were applied to the GNITF, it was irradiated with lasers at different wavelengths (k¼473, 532, and 633 nm). Because of plasmon oscillations, the tunnel current increased. It is found that the tunnel current enhancement is mainly due to the thermal effect of plasmon oscillations rather than other plasmonic effects. The results are highly relevant to applications of plasmonic effects in opto-electronic devices.

Effect of a floating electrode on a plasma jet

Two kinds of floating electrode, floating dielectric barrier covered electrode (FDBCE) and floating pin electrode (FPE), which can enhance the performance of plasma jet are reported. The intense discharge between the floating electrode and power electrode decreased the voltage to trigger the plasma jet substantially. The transition of plasma bullet from ring shape to disk shape in the high helium concentration region happened when the floating electrode was totally inside the powered ring electrode. The enhanced electric field between propagating plasma bullet and ground electrode is the reason for this transition. The double plasma bullets happened when part of the FDBCE was outside the powered ring electrode, which is attributed to the structure and surface charge of FDBCE. As part of the FPE was outside the powered ring electrode, the return stroke resulted in a single intensified plasma channel between FPE and ground electrode.

Efficiently capturing large, complex cultural heritage sites with a handheld mobile 3D laser mapping system

Accurate three-dimensional representations of cultural heritage sites are highly valuable for scientific study, conservation, and educational purposes. In addition to their use for archival purposes, 3D models enable efficient and precise measurement of relevant natural and architectural features. Many cultural heritage sites are large and complex, consisting of multiple structures spatially distributed over tens of thousands of square metres. The process of effectively digitising such geometrically complex locations requires measurements to be acquired from a variety of viewpoints. While several technologies exist for capturing the 3D structure of objects and environments, none are ideally suited to complex, large-scale sites, mainly due to their limited coverage or acquisition efficiency. We explore the use of a recently developed handheld mobile mapping system called Zebedee in cultural heritage applications. The Zebedee system is capable of efficiently mapping an environment in three dimensions by continually acquiring data as an operator holding the device traverses through the site. The system was deployed at the former Peel Island Lazaret, a culturally significant site in Queensland, Australia, consisting of dozens of buildings of various sizes spread across an area of approximately 400 × 250 m. With the Zebedee system, the site was scanned in half a day, and a detailed 3D point cloud model (with over 520 million points) was generated from the 3.6 hours of acquired data in 2.6 hours. We present results demonstrating that Zebedee was able to accurately capture both site context and building detail comparable in accuracy to manual measurement techniques, and at a greatly increased level of efficiency and scope. The scan allowed us to record derelict buildings that previously could not be measured because of the scale and complexity of the site. The resulting 3D model captures both interior and exterior features of buildings, including structure, materials, and the contents of rooms.

The effects of exercise and adipose tissue lipolysis on plasma adiponectin concentration and adiponectin receptor expression in human skeletal muscle

Objective It has been suggested that adiponectin regulates plasma free fatty acid (FFA) clearance by stimulating FFA uptake and/or oxidation in muscle. We aimed to determine changes in plasma adiponectin concentration and adiponectin receptor 1 and 2 mRNA expression in skeletal muscle during and after prolonged exercise under normal, fasting conditions (high FFA trial; HFA) and following pharmacological inhibition of adipose tissue lipolysis (low FFA trial; LFA). Furthermore, we aimed to detect and locate adiponectin in skeletal muscle tissue. Methods Ten subjects performed two exercise trials (120 min at 50% VO2max). Indirect calorimetry was used to determine total fat oxidation rate. Plasma samples were collected at rest, during exercise and during post-exercise recovery to determine adiponectin, FFA and glycerol concentrations. Muscle biopsies were taken to determine adiponectin protein and adiponectin receptor 1 and 2 mRNA expression and to localise intramyocellular adiponectin. Results Basal plasma adiponectin concentrations averaged 6.57±0.7 and 6.63±0.8 mg/l in the HFA and LFA trials respectively, and did not change significantly during or after exercise. In the LFA trial, plasma FFA concentrations and total fat oxidation rates were substantially reduced. However, plasma adiponectin and muscle adiponectin receptor 1 and 2 mRNA expression did not differ between trials. Immunohistochemical staining of muscle cross-sections showed the presence of adiponectin in the sarcolemma of individual muscle fibres and within the interfibrillar arterioles. Conclusion Plasma adiponectin concentrations and adiponectin receptor 1 and 2 mRNA expression in muscle are not acutely regulated by changes in adipose tissue lipolysis and/or plasma FFA concentrations. Adiponectin is abundantly expressed in muscle, and, for the first time, it has been shown to be present in/on the sarcolemma of individual muscle fibres.

Circulating fragments of N-Terminal Pro-B-Type Natriuretic Peptides in plasma of heart failure patients

BACKGROUND: The use of nonstandardized N-terminal pro-B-type natriuretic peptide (NT-proBNP) assays can contribute to the misdiagnosis of heart failure (HF). Moreover, there is yet to be established a common consensus regarding the circulating forms of NT-proBNP being used in current assays. We aimed to characterize and quantify the various forms of NT-proBNP in the circulation of HF patients. METHODS: Plasma samples were collected from HF patients (n = 20) at rest and stored at -80 degrees C. NT-proBNP was enriched from HF patient plasma by use of immunoprecipitation followed by mass spectrometric analysis. Customized homogeneous sandwich AlphaLISA (R) immunoassays were developed and validated to quantify 6 fragments of NT-proBNP. RESULTS: Mass spectrometry identified the presence of several N- and C-terminally processed forms of circulating NT-proBNP, with physiological proteolysis between Pro2-Leu3, Leu3-Gly4, Pro6-Gly7, and Pro75-Arg76. Consistent with this result, AlphaLISA immunoassays demonstrated that antibodies targeting the extreme N or C termini measured a low apparent concentration of circulating NT-proBNP. The apparent circulating NT-proBNP concentration was increased with antibodies targeting nonglycosylated and nonterminal epitopes (P < 0.05). CONCLUSIONS: In plasma collected from HF patients, immunoreactive NT-proBNP was present as multiple N- and C-terminally truncated fragments of the full length NT-proBNP molecule. Immunodetection of NT-proBNP was significantly improved with the use of antibodies that did not target these terminal regions. These findings support the development of a next generation NT-proBNP assay targeting nonterminal epitopes as well as avoiding the central glycosylated region of this molecule. (c) 2013 American Association for Clinical Chemistry

Studies of Brisbane municipal water quality using Inductively Coupled Plasma - Mass Spectrometry and Chemometrics

This research established innovative methods and a predictive model to evaluate water quality using the trace element and heavy metal concentrations of drinking water from the greater Brisbane area. Significantly, the combined use of Inductively Coupled Plasma - Mass Spectrometry and Chemometrics can be used worldwide to provide comprehensive, rapid and affordable analyses of elements in drinking water that can have a considerable impact on human health.

Reduction of diesel engine exhaust emissions using non-thermal plasma technology

Non-thermal plasma (NTP) is a promising candidate for controlling engine exhaust emissions. Plasma is known as the fourth state of matter, where both electrons and positive ions co-exist. Both gaseous and particle emissions of diesel exhaust undergo chemical changes when they are exposed to plasma. In this project diesel particulate matter (DPM) mitigation from the actual diesel exhaust by using NTP technology has been studied. The effect of plasma, not only on PM mass but also on PM size distribution, physico-chemical structure of PM and PM removal mechanisms, has been investigated. It was found that NTP technology can significantly reduce both PM mass and number. However, under some circumstances particles can be formed by nucleation. Energy required to create the plasma with the current technology is higher than the benchmark set by the commonly used by the automotive industry. Further research will enable the mechanism of particle creation and energy consumption to be optimised.