Process studies of odour emissions from effluent ponds using machine-based odour measurement

Replicable experimental studies using a novel experimental facility and a machine-based odour quantification technique were conducted to demonstrate the relationship between odour emission rates and pond loading rates. The odour quantification technique consisted of an electronic nose, AromaScan A32S, and an artificial neural network. Odour concentrations determined by olfactometry were used along with the AromaScan responses to train the artificial neural network. The trained network was able to predict the odour emission rates for the test data with a correlation coefficient of 0.98. Time averaged odour emission rates predicted by the machine-based odour quantification technique, were strongly correlated with volatile solids loading rate, demonstrating the increased magnitude of emissions from a heavily loaded effluent pond. However, it was not possible to obtain the same relationship between volatile solids loading rates and odour emission rates from the individual data. It is concluded that taking a limited number of odour samples over a short period is unlikely to provide a representative rate of odour emissions from an effluent pond. A continuous odour monitoring instrument will be required for that more demanding task

Screen-printed potentiometric Ag/AgCl chloride sensors: Lifetime performance and their use in soil salt measurements

Silver – silver chloride electrodes (Ag/AgCl) for the detection of chloride ions were fabricated using thick-film technology. Five different formulations were prepared and chloride responses were investigated over time. Almost identical and near Nernstian responses were observed over the first 162 days with an average chloride sensitivity for all formulations of -51.12 mV ± 0.45 mV per decade change in chloride concentration compared with a value of -50.59 mV ± 0.01 mV over 388 days for the best two formulations. After 6-months continuous immersion in tap water, pastes formulated with a glass binder began to exhibit a loss in sensitivity whilst those formulated from a commercial thick-film dielectric paste remained functional for the best part of a year. This difference in lifetime performance is attributed to the inclusion of proprietary additives in the commercial paste aiding adhesion and minimising AgCl leaching. The mechanical and chemical robustness of these electrodes has been demonstrated through their ability to detect changing levels of chloride when immersed in soil columns. This particular capacity will make them an invaluable tool in the fields of hydrology, agricultural science, soil science and environmental science

Bio-energetic preservation of cones in a mouse model of retinitis pigmentosa

ARVO Annual Meeting AbstractDaniel Narayan, Glyn Chidlow, John P M Wood, Robert James Casso

Comment on 'A method to quantify regional axonal transport blockade at the optic nerve head after short term intraocular pressure elevation in mice by A. Korneva et al.' (Exp. Eye Res. doi: https://doi.org/10.1016/j.exer.2020.108035)

Letter to the EditorRobert J. Casson, Glyn Chidlow, John Woo

High-precision determination of transition amplitudes of principal transitions in Cs from van der Waals coefficient C_6

A method for determination of atomic dipole matrix elements of principal transitions from the value of dispersion coefficient C_6 of molecular potentials correlating to two ground-state atoms is proposed. The method is illustrated on atomic Cs using C_6 deduced from high-resolution Feshbach spectroscopy. The following reduced matrix elements are determined < 6S_{1/2} || D || 6P_{1/2} > =4.5028(60) |e| a0 and =6.3373(84) |e| a0 (a0= 0.529177 \times 10^{-8} cm.) These matrix elements are consistent with the results of the most accurate direct lifetime measurements and have a similar uncertainty. It is argued that the uncertainty can be considerably reduced as the coefficient C_6 is constrained further.Comment: 4 pages; 3 fig

Displaying the Heterogeneity of the SN 2002cx-like Subclass of Type Ia Supernovae with Observations of the Pan-STARRS-1 Discovered SN2009ku

SN2009ku, discovered by Pan-STARRS-1, is a Type Ia supernova (SNIa), and a member of the distinct SN2002cx-like class of SNeIa. Its light curves are similar to the prototypical SN2002cx, but are slightly broader and have a later rise to maximum in g. SN2009ku is brighter (~0.6 mag) than other SN2002cx-like objects, peaking at M_V = -18.4 mag - which is still significantly fainter than typical SNeIa. SN2009ku, which had an ejecta velocity of ~2000 kms^-1 at 18 days after maximum brightness is spectroscopically most similar to SN2008ha, which also had extremely low-velocity ejecta. However, SN2008ha had an exceedingly low luminosity, peaking at M_V = -14.2 mag, ~4 mag fainter than SN2009ku. The contrast of high luminosity and low ejecta velocity for SN2009ku is contrary to an emerging trend seen for the SN2002cx class. SN2009ku is a counter-example of a previously held belief that the class was more homogeneous than typical SNeIa, indicating that the class has a diverse progenitor population and/or complicated explosion physics. As the first example of a member of this class of objects from the new generation of transient surveys, SN2009ku is an indication of the potential for these surveys to find rare and interesting objects.Comment: 7 pages, 3 figure

Measurement of the 6s - 7p transition probabilities in atomic cesium and a revised value for the weak charge Q_W

We have measured the 6s - 7p_{1/2,3/2} transition probabilities in atomic cesium using a direct absorption technique. We use our result plus other previously measured transition rates to derive an accurate value of the vector transition polarizability \beta and, consequently, re-evaluate the weak charge Q_W. Our derived value Q_W=-72.65(49) agrees with the prediction of the standard model to within one standard deviation.Comment: 4 pages, 2 figure

Glucose metabolism in mammalian photoreceptor inner and outer segments

Photoreceptors are the first-order neurons of the visual pathway, converting light into electrical signals. Rods and cones are the two main types of photoreceptors in the mammalian retina. Rods are specialized for sensitivity at the expense of resolution and are responsible for vision in dimly lit conditions. Cones are responsible for high acuity central vision and colour vision. Many human retinal diseases are characterized by a progressive loss of photoreceptors. Photoreceptors consist of four primary regions: outer segments, inner segments, cell bodies and synaptic terminals. Photoreceptors consume large amounts of energy, and therefore, energy metabolism may be a critical juncture that links photoreceptor function and survival. Cones require more energy than rods, and cone degeneration is the main cause of clinically significant vision loss in retinal diseases. Photoreceptor segments are capable of utilizing various energy substrates, including glucose, to meet their large energy demands. The pathways by which photoreceptor segments meet their energy demands remain incompletely understood. Improvements in the understanding of glucose metabolism in photoreceptor segments may provide insight into the reasons why photoreceptors degenerate due to energy failure. This may, in turn, assist in developing bio-energetic therapies aimed at protecting photoreceptors.Daniel S Narayan, Glyn Chidlow, John PM Wood and Robert J Casso

Glucose protects cultured retinal cells from oxidative injury via pentose phosphate pathway activation and maintenance of reduced glutathione

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.Purpose : Oxidative injury has been implicated to play a role in a range of retinal neurodegenerative conditions. Thus, protecting retinal cells in vivo from such an insult is extremely beneficial. We therefore sought to investigate whether glucose, acting via the pentose phosphate pathway (PPP) was able to counteract oxidative stress to retinal cells in culture. Methods : Mixed retinal neuron-glial cultures were prepared from 2 day old rat pups and used at 7 days in vitro. Neuron-only and primary Muller cell cultures were prepared from mixed cultures, by treatment with cytosine arabinoside to kill dividing cells, or, by regular medium changes for 30 days, respectively. At appropriate stages, cultures were treated with t-butyl hydroperoxide (tbH; 100nM-10mM) in energy substrate-free DMEM to induce oxidative stress. Some cultures were co-treated with glucose (100µM-25mM) or other metabolic substrates (5mM; pyruvate, lactate, glutamine, fructose-1,6-bisphosphate). Glycolysis was inhibited with iodoacetate (IOA; 10µM) or 2-deoxy-D-glucose (2-DG; 1mM). PPP was inhibited with 6-aminonicotinamide (6NA; 500µM) and glutathione biosynthesis with buthionine sulphoxamine (BSO; 100µM). Cell viability, immunocytochemistry and Western blot were employed to assess cellular outcomes after treatments. An antioxidant assay identified which, if any, of the metabolic substrates tested had intrinsic antioxidant properties. Results : Oxidative stress resulted in loss of viability to mixed retinal cells and primary Muller cells: the EC50 for tbH was approximately 35µM in each case. Glucose dose-dependently reduced the toxicity of tbH with a maximal effect at 5mM (EC50 of tbH elevated to approximately 250µM). Pyruvate was also partially protective, but had intrinsic antioxidant properties. Glycolytic blockade had no effect on the protective effect of glucose but both 6NA and BSO inhibited the protective response. When cultured alone, neurons were equally susceptible to tbH-toxicity but could not be protected by glucose. Conclusions : Glucose prevented oxidative stress to retinal cells via the PPP and the consequent generation of reduced glutathione. Neurons were not subjected to glucose-induced protection except when glial cells were present, implying the passage of a transmissible protective factor between the two cell types.John P M Wood, Glyn Chidlow, Teresa Mammone, Robert James Casso