Determination of methylmercury using liquid chromatography – photochemical vapour generation – atomic fluorescence spectroscopy (LC-PVG-AFS) : a simple, green analytical method

Acknowledgements The authors thank P S Analytical for financial support for the project. In addition, the author would like to thank Dr Nick Ralston for providing the tuna samples used in the method validation, as well as Jonas Kunigkeit and Jasmina Allen for their help in the lab.Peer reviewedPostprin

Tobacco Use, Exposure to Secondhand Smoke, and Training on Cessation Counseling Among Nursing Students: Cross-Country Data from the Global Health Professions Student Survey (GHPSS), 2005–2009

The Nursing Global Health Professions Student Survey (GHPSS) has been conducted in schools in 39 countries and the Gaza Strip/West Bank (identified as “sites” for the remainder of this paper). In half the sites, over 20% of the students currently smoked cigarettes, with males having higher rates than females in 22 sites. Over 60% of students reported having been exposed to secondhand smoke in public places in 23 of 39 sites. The majority of students recognized that they are role models in society, believed they should receive training on counseling patients to quit using tobacco, but few reported receiving any formal training. Tobacco control efforts must discourage tobacco use among health professionals, promote smoke free workplaces, and implement programs that train health professionals in effective cessation-counseling techniques

Inner- and outer-sphere metal coordination in blue copper proteins

Blue copper proteins (BCPs) comprise classic cases of Nature's profound control over the electronic structures and chemical reactivity of transition metal ions. Early studies of BCPs focused on their inner coordination spheres, that is, residues that directly coordinate Cu. Equally important are the electronic and geometric perturbations to these ligands provided by the outer coordination sphere. In this tribute to Hans Freeman, we review investigations that have advanced the understanding of how inner-sphere and outer-sphere coordination affects biological Cu properties

High temperature stability of femtosecond written ablation Fiber Bragg gratings in microstructured optical fibers

We examine the thermal lifespan of FBGs written in pure-silica microstructured optical fibers at temperatures of up to 1260°C, demonstrating that they are capable of performing measurements at this temperature for an extended duration.E.P. Schartner, S.C. Warren-Smith, L. Viet Nguyen, D.E. Otten, D. Lancaster, and H. Ebendorff-Heideprie

Multi-point optical fiber pressure sensor

Conference 11200 - AOS Australian Conference on Optical Fibre Technology (ACOFT) and Australian Conference on Optics, Lasers, and Spectroscopy (ACOLS) 2019This paper reports on a multi-point optical fiber pressure sensor using fiber Bragg gratings (FBGs) written on an exposed core optical fiber (ECF) by femtosecond laser. The pressure sensing elements were constructed as Fabry-Perot (FP) interferometers of different cavity lengths using pairs of FBGs with identical resonant wavelength. In this fashion an interference pattern was formed within the FBG bandwidth with much narrower fringes, leading to better detection limit. Fast Fourier transform (FFT) was used to calculate the phase change of the FP interference pattern with respect to applied pressure. The pressure sensitivity was proportional to the cavity FP cavity length, and reached -0.672 rad/MPa for the case of FP with 9 mm cavity length. The proposed sensor has potential to measure pressure at very high temperature thanks to its single material configuration.Linh V. Nguyen, Erik P. Schartner, Dale Otten, Zheng Yu, David Lancaster, Heike Ebendorff- Heidepriem, and Stephen C. Warren-Smit

Stability of grating-based optical fiber sensors at high temperature

We present a comparison of four different grating-based optical fiber high temperature sensors. Three of the sensors are commercially available and include a heat treated, twisted (chiral) pure-silica microstructured optical fiber, a femtosecond laser written Bragg grating in a depressed cladding single mode fiber and a regenerated fiber Bragg grating. We compare these to an in-house fabricated femtosecond laser ablation grating in a pure-silica microstructured optical fiber. We have tested the sensors in increments of 100°C up to 1100°C for durations of at least 24 hours each. All four sensors were shown to be operational up to 900°C, however the two sensors based on pure-silica microstructured fiber displayed higher stability in the reflected sensor wavelength compared to the other sensors at temperatures of 700°C and higher. We further investigated high temperature stability of silica suspended-core fibers with femtosecond laser inscribed ablation gratings, which show improved stability up to 1050°C following thermal annealing. This investigation can be used as a guide for selecting fiber types, packaging, and grating types for high temperature sensing applications.Stephen C. Warren-Smith, Erik P. Schartner, Linh V. Nguyen, Dale E. Otten, Zheng Yu, David G. Lancaster, and Heike Ebendorff-Heideprie

Multi-point high temperature optical fiber sensor

ANZCOP, 2019, Melbourne, AustraliaAbstract not availableErik P. Schartner, Linh V. Nguyen, Dale Otten, Zheng Yu, David G. Lancaster, and Heike Ebendorff-Heidepriem, and Stephen C. Warren-Smit

Single-peak fiber Bragg gratings in suspended-core optical fibers

Femtosecond laser inscribed fiber Bragg gratings in pure-silica suspended-core optical fibers have previously been demonstrated as a promising platform for high temperature sensing. However, the density of gratings that could be written on a single fiber was limited by undesired reflections associated with higher order modes in these high numerical aperture fibers. This resulted in a complex, broadband reflection spectrum with limited multiplexing capability. In this work we utilize modifications to the fine structure of the suspended core optical fibers to fine tune the relative confinement loss of the optical fiber modes, thus reducing the contribution from such higher order modes. The effects of these changes on mode propagation are modeled, giving a range of fibers with different confinement loss properties which can be tailored to the specific length scale of a desired application. We achieve single-peak reflections from individual fiber Bragg gratings, significantly improving performance for multipoint sensing and demonstrate this technique by writing 20 gratings onto a single fiber.Erik P. Schartner, Stephen C. Warren-Smith, Linh V. Nguyen, Dale Otten, Zheng Yu, David G. Lancaster and Heike Ebendorff-Heideprie

Two-dimensional mapping of surface scatterers on an optical fiber core using selective mode launching

The tracking of small particles is an important but challenging task for biological applications such as disease diagnostics and medical research. Current methods are limited to the use of bulky instruments such as flow cytometers and microscopes. Here, a novel technique for the detection and measurement of micron-scale optical scatterers using a few-mode exposed-core microstructured optical fiber is proposed. Through selective mode launching combined with optical frequency domain reflectometry, scatterers located on the fiber core surface can be simultaneously mapped with both longitudinal and transverse information. This technique is demonstrated by detecting the two-dimensional positions of several femtosecond-laser-inscribed micron-scale ablations written at different locations on the fiber core surface. Due to the compact nature of the optical fiber and its local sensitivity to scatterers that are in close proximity to it, this technique has the potential for the measurement and detection of micron-scale particles in difficult to reach biological environments for in vivo applications.Lu Peng, Linh Viet Nguyen, Jiawen Li, Nicolas Riesen, Dale Otten, David G. Lancaster ... et al

Bridging Time Scales in Cellular Decision Making with a Stochastic Bistable Switch

Cellular transformations which involve a significant phenotypical change of the cell's state use bistable biochemical switches as underlying decision systems. In this work, we aim at linking cellular decisions taking place on a time scale of years to decades with the biochemical dynamics in signal transduction and gene regulation, occuring on a time scale of minutes to hours. We show that a stochastic bistable switch forms a viable biochemical mechanism to implement decision processes on long time scales. As a case study, the mechanism is applied to model the initiation of follicle growth in mammalian ovaries, where the physiological time scale of follicle pool depletion is on the order of the organism's lifespan. We construct a simple mathematical model for this process based on experimental evidence for the involved genetic mechanisms. Despite the underlying stochasticity, the proposed mechanism turns out to yield reliable behavior in large populations of cells subject to the considered decision process. Our model explains how the physiological time constant may emerge from the intrinsic stochasticity of the underlying gene regulatory network. Apart from ovarian follicles, the proposed mechanism may also be of relevance for other physiological systems where cells take binary decisions over a long time scale.Comment: 14 pages, 4 figure