Engaging rural Australian communities in National Science Week helps increase visibility for women researchers

During a week-long celebration of science, run under the federally-supported National Science Week umbrella, the Catch a Rising Star: women in Queensland research (CaRS) program flew scientists who identify as women to regional and remote communities in the Australian State of Queensland. The aim of the project was twofold: first, to bring science to remote and regional communities in a large, economically diverse state; and second, to determine whether media and public engagement provide career advancement opportunities for women scientists. This paper focuses on the latter goal. The data show: 1) a substantial majority (> 80%) of researchers thought the training and experience provided by the program would help develop her career as a research scientist in the future; 2) the majority (65%) thought the program would help relate her research to end users, industry partners, or stakeholders in the future; and, 3) analytics can help create a compelling narrative around engagement metrics and help to quantify influence. During the weeklong project, scientists reached 600,000 impressions on one social media platform (Twitter) using a program hashtag. The breadth and depth of the project outcomes indicate funding bodies and employers could use similar data as an informative source of metrics to support hiring and promotion decisions. Although this project focused on researchers who identify as women, the lessons learned are applicable to researchers representing a diverse range of backgrounds. Future surveys will help determine whether the CaRS program provided long-term career advantages to participating scientists and communities

Two-Photon Fluorescence Microscopy Imaging of Cellular Oxidative Stress Using Profluorescent Nitroxides

A range of varying chromophore nitroxide free radicals and their nonradical methoxyamine analogues were synthesized and their linear photophysical properties examined. The presence of the proximate free radical masks the chromophore’s usual fluorescence emission, and these species are described as profluorescent. Two nitroxides incorporating anthracene and fluorescein chromophores (compounds 7 and 19, respectively) exhibited two-photon absorption (2PA) cross sections of approximately 400 G.M. when excited at wavelengths greater than 800 nm. Both of these profluorescent nitroxides demonstrated low cytotoxicity toward Chinese hamster ovary (CHO) cells. Imaging colocalization experiments with the commercially available CellROX Deep Red oxidative stress monitor demonstrated good cellular uptake of the nitroxide probes. Sensitivity of the nitroxide probes to H2O2-induced damage was also demonstrated by both one- and two-photon fluorescence microscopy. These profluorescent nitroxide probes are potentially powerful tools for imaging oxidative stress in biological systems, and they essentially “light up” in the presence of certain species generated from oxidative stress. The high ratio of the fluorescence quantum yield between the profluorescent nitroxide species and their nonradical adducts provides the sensitivity required for measuring a range of cellular redox environments. Furthermore, their reasonable 2PA cross sections provide for the option of using two-photon fluorescence microscopy, which circumvents commonly encountered disadvantages associated with one-photon imaging such as photobleaching and poor tissue penetration

The synthesis and evaluation of polyaromatic profluorescent nitroxide probes for the detection of photo-oxidative polymer degradation

This study focused on the synthesis and evaluation of novel photo-stable profluorescent nitroxide probes. The stability and performance of the newly synthesised probes were assessed under harsh environmental environments and compared with previously synthesised PFN probes. Analysis of their physical characteristics revealed that the nitroxide-fluorophore probes displayed strongly suppressed fluorescence in comparison to their corresponding non-radical derivatives. Evaluation of these probes confirmed their enhanced ability to detect radical polymer degradation in the laboratory and in true weathering conditions over any previously synthesized profluorescent nitroxides or other laboratory techniques

Profluorescent nitroxide sensors for monitoring photo-induced degradation in polymer films

A range of profluorescent nitroxides (PFNs) were tested as probes to monitor photo-induced radical-mediated damage in polymer materials. The most stable and sensitive probe of the PFNs tested was an alkyne-linked perylenediimide PFN, 6b, with napthalimide and 9,10-bis(phenylethnyl)anthranene-based versions giving lower stability and sensitivity. Results from photo-ageing of poly(1-trimethylsilyl)-1-propyne (PTMSP) and the ethylene norbornene copolymer (TOPAS®) films doped with PFN probes demonstrated that sensors employing these support materials deliver significantly enhanced sensitivity compared to traditional techniques used to monitor photo-oxidative degradation of polymers, such as infrared spectroscopy. This enhanced sensitivity for detecting polymer damage improved methods for the determination of the serviceable application lifetime of polymers

Two-Photon Fluorescence Microscopy Imaging Of Cellular Oxidative Stress Using Profluorescent Nitroxides

E-2-Tricyanovinyl-3-n-hexyl-5-[4-{bis(4-n-butylphenyl)amino} -2-methoxystyryl]-thiophene, 1, has previously been used to demonstrate applications relying on frequency tripling of 1.55 μm light. Here we report the synthesis and chemical characterisation of 1, along with quantum-chemical calculations and additional experimental investigations of its third-order nonlinear properties that give more insight into its frequency tripling properties. Although 1 can be processed into amorphous films, crystals can also be grown by slow evaporation of solutions; the crystal structure determined by X-ray diffraction shows evidence of significant contributions from zwitterionic resonance forms to the ground-state structure, and reveals centrosymmetric packing exhibiting π-π and C-H⋯NC interactions. Both solutions and films of 1 exhibit near-infrared two-photon absorption into the low-lying one-photon-allowed state with a peak two-photon cross-section of ca. 290 GM (measured using the white-light continuum method with a pump wavelength of 1800 nm) at a transition energy equivalent to degenerate two-photon absorption at ca. 1360 nm; two related chromophores are also found to show comparable near-IR two-photon cross-sections. Closed-aperture Z-scan measurements and quantum-chemical calculations indicate that the nonlinear refractive index and third-harmonic generation properties of 1 are strongly dependent on frequency in the telecommunications range, due the aforementioned two-photon resonance. © 2012 The Royal Society of Chemistry

Profluorescent nitroxide sensors for monitoring the natural aging of polymer materials

The utility of profluorescent nitroxides (PFNs) as sensitive probes to detect early stage photodegradation in a cyclic olefin copolymer, TOPAS®, during both natural aging and accelerated aging under laboratory conditions is reported. PFN additives in TOPAS® capture radicals to form fluorescent adducts as the material degrades. The levels of fluorescence detectable from the polymer reflect the degree of free-radical degradation in the material, with the PFN probes delivering enhanced sensitivity over traditional analytical methods for the detection of photodegradation of TOPAS®. The probes are able to highlight polymer degradation occurring within the oxidation “induction” period, where little change can be observed using infrared spectroscopy; however, their efficacy does not extend far beyond this period. The effective probe lifetime however can be significantly extended through the use of common additives such as the UV absorber (Tinuvin P) and a hindered amine stabiliser analogue (1,1,3,3-tetramethylisoindol-2-yloxyl, TMIO).</p

Synergic bactericidal effects of reduced graphene oxide and silver nanoparticles against Gram-positive and Gram-negative bacteria

Reduced graphene oxide (rGO) is a promising antibacterial material, the efficacy of which can be further enhanced by the addition of silver nanoparticles (nAg). In this study, the mechanisms of antibacterial activity of rGO–nAg nanocomposite against several important human pathogenic multi-drug resistant bacteria, namely Gram-positive coccal Staphylococcus aureus and Gram-negative rod-shaped Escherichia coli and Proteus mirabilis are investigated. At the same concentration (100 µg/ml), rGO–nAg nanocomposite was significantly more effective against all three pathogens than either rGO or nAg. The nanocomposite was equally active against P. mirabilis and S. aureus as systemic antibiotic nitrofurantoin, and significantly more effective against E. coli. Importantly, the inhibition was much faster in the case of rGO–nAg nanocomposite compared to nitrofurantoin, attributed to the synergistic effects of rGO–nAg mediated contact killing and oxidative stress. This study may provide new insights for the better understanding of antibacterial actions of rGO–nAg nanocomposite and for the better designing of graphene-based antibiotics or other biomedical applications

New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting

Flexible piezoelectric generators (PEGs) have recently attracted significant interest, as they are able to harvest mechanical energy and convert it to electricity, decreasing reliance on conventional energy sources. These devices enable innovative applications including smart clothing, wearable electronics, on-skin and implantable sensors, as well as harvesting energy from the movement of vehicles, water and wind. Poly(vinylidene fluoride) and related fluoropolymers are the most common flexible piezoelectric materials, widely utilized for their high electromechanical conversion efficiencies, optimal mechanical flexibility, processability and biocompatibility. This critical review covers the processing of fluoropolymers towards the maximization of piezoelectric conversion parameters. Particular emphasis is placed on the correlation between synthetic routes, inclusion of further co-monomers, addition of additives and nanomaterials, as well as processing techniques and the optimized electricity generation in the resultant PEGs, providing an important analysis to complement existing literature. The importance of novel polymer deposition techniques, which reduce reliance on the conventional, highly energetic post-processing steps, is highlighted. Recent advances in fluoropolymer-based flexible PEGs open an array of exciting applications, which rapidly progress towards commercialization. This review provides a timely analysis of this increasingly important field to the cross-disciplinary community of polymer chemists, materials scientists, nanotechnologists, engineers, and industry practitioners

3D printing of poly(vinylidene fluoride-trifluoroethylene): a poling-free technique to manufacture flexible and transparent piezoelectric generators

Flexible piezoelectric generators (PEGs) present a unique opportunity for renewable and sustainable energy harvesting. Here, we present a low-temperature and low-energy deposition method using solvent evaporation-assisted three-dimensional printing to deposit electroactive poly(vinylidene fluoride) (PVDF)-trifluoroethylene (TrFE) up to 19 structured layers. Visible-wavelength transmittance was above 92%, while ATR-FTIR spectroscopy showed little change in the electroactive phase fraction between layer depositions. Electroactivity from the fabricated PVDF-TrFE PEGs showed that a single structured layer gave the greatest output at 289.3 mV peak-to-peak voltage. This was proposed to be due to shear-induced polarization affording the alignment of the fluoropolymer dipoles without an electric field or high temperature

Two-Photon Fluorescence Microscopy Imaging of Cellular Oxidative Stress Using Profluorescent Nitroxides

A range of varying chromophore nitroxide free radicals and their nonradical methoxyamine analogues were synthesized and their linear photophysical properties examined. The presence of the proximate free radical masks the chromophore’s usual fluorescence emission, and these species are described as profluorescent. Two nitroxides incorporating anthracene and fluorescein chromophores (compounds <b>7</b> and <b>19</b>, respectively) exhibited two-photon absorption (2PA) cross sections of approximately 400 G.M. when excited at wavelengths greater than 800 nm. Both of these profluorescent nitroxides demonstrated low cytotoxicity toward Chinese hamster ovary (CHO) cells. Imaging colocalization experiments with the commercially available CellROX Deep Red oxidative stress monitor demonstrated good cellular uptake of the nitroxide probes. Sensitivity of the nitroxide probes to H₂O₂-induced damage was also demonstrated by both one- and two-photon fluorescence microscopy. These profluorescent nitroxide probes are potentially powerful tools for imaging oxidative stress in biological systems, and they essentially “light up” in the presence of certain species generated from oxidative stress. The high ratio of the fluorescence quantum yield between the profluorescent nitroxide species and their nonradical adducts provides the sensitivity required for measuring a range of cellular redox environments. Furthermore, their reasonable 2PA cross sections provide for the option of using two-photon fluorescence microscopy, which circumvents commonly encountered disadvantages associated with one-photon imaging such as photobleaching and poor tissue penetration