The absorption of gold cyanide onto activated carbon. III. Factors influencing the rate of loading and the equilibrium capacity

The results are reported of experiments on the influence of a number of variables on the rate of loading of gold cyanide onto activated carbon and the equilibrium capacity of the carbon. These variables include the concentrations of gold and free cyanide in solution, the pH value and ionic strength of the solution, the concentration of organic compounds in the solution, the temperature, the particle size of the carbon, and the mixing efficiency. The experiments were carried out under approximately steady-state conditions to simulate the conditions in a countercurrent carbon-in-pulp absorption plant. In addition, the results are reported of experiments to establish whether the absorption of gold cyanide onto activated carbon is a reversible process

The absorption of gold cyanide onto activated carbon. II. Application of the kinetic model to multistage absorption circuits

A relatively simple rate equation for the kinetics of the absorption of gold from cyanide solutions onto activated carbon was used as the basis in the development of a model for multistage carbon-in-pulp and carbon-in-leach absorption circuits. The model was used in the prediction of both the steady-state and the transient behaviour of the absorption process, and the results were found to be in reasonable agreement with those observed in an extended pilot-plant campaign. A number of practical implications of the model are discussed, and an assessment is made of the economic consequences of the various process options available for the design of a carbon-in-pulp plant

The absorption of gold cyanide onto activated carbon. I. The kinetics of absorption from pulps

An account is given of the development of a relatively simple model that describes the kinetics of the absorption of gold cyanide on activated carbon. The model is based on the treatment of the carbon-solution interface as a homogeneous boundary across which gold is transported at a rate determined by the rate of mass transport to and from the interface. Rate equations derived from this model describe the results of various kinetic experiments under continuous or batch conditions in the laboratory and on operating pilot and full-scale plants

The contribution of qualitative behavioural assessment to appraisal of livestock welfare

Animal welfare is increasingly important for the Australian livestock industries, to maintain social licence to practice as well as ensuring market share overseas. Improvement of animal welfare in the livestock industries requires several important key steps. Paramount among these, objective measures are needed for welfare assessment that will enable comparison and contrast of welfare implications of husbandry procedures or housing options. Such measures need to be versatile (can be applied under a wide range of on- and off-farm situations), relevant (reveal aspects of the animal’s affective or physiological state that is relevant to their welfare), reliable (can be repeated with confidence in the results), relatively economic to apply, and they need to have broad acceptance by all stakeholders. Qualitative Behavioural Assessment (QBA) is an integrated measure that characterises behaviour as a dynamic, expressive body language. QBA is a versatile tool requiring little specialist equipment suiting application to in situ assessments that enables comparative, hypothesis-driven evaluation of various industry-relevant practices. QBA is being increasingly used as part of animal welfare assessments in Europe, and although most other welfare assessment methods record ‘problems’ (e.g. lameness, injury scores, and so on), QBA can capture positive aspects of animal welfare (e.g. positively engaged with their environment, playfulness). In this viewpoint, we review the outcomes of recent QBA studies and discuss the potential application of QBA, in combination with other methods, as a welfare assessment tool for the Australian livestock industries

Morphology of Gambierdiscus excentricus (Dinophyceae) with emphasis on sulcal plates

Gambierdiscus excentricus is an epibenthic dinoflagellate able to produce ciguatoxin and maitotoxin-like compounds that are responsible for ciguatera fish poisoning. Morphological descriptions and molecular characterization of two G. excentricus strains isolated from Brazil and maintained in culture were provided. The most complete description of the morphology of the sulcal region of Gambierdiscus based on light and scanning electron microscopy was presented. The sulcal area morphology and nomenclature used by different authors to name the sulcal plates in Gambierdiscus were reviewed. Two small sulcal plates (S.m.a. and S.m.p.) were shown for the first time. Phylogenetic trees based on D1–D3 and D8–D10 large subunits of ribosomal RNA gene sequences showed that the strains of G. excentricus from Brazil clustered with strains of G. excentricus isolated from its type locality, the Canary Islands. Both phylogenetic trees reconstructed the same relationships among all the formally described Gambierdiscus species and Gambierdiscus sp. ribotype 2 and Gambierdiscus sp. type 2.Versión del editor2,080

Exogenous NG-hydroxy-l-arginine causes nitrite production in vascular smooth muscle cells in the absence of nitric oxide synthase activity

AbstractNitric oxide (NO) production from exogenous NG-hydroxy-l-arginine (OH-l-Arg) was investigated in rat aortic smooth muscle cells in culture by measuring nitrite accumulation in the culture medium. As well, the interaction between OH-l-Arg and l-arginine uptake via the y+ cationic amino acid transporter was studied. In cells without NO-synthase activity, OH-l-Arg (1–1000 μM) induced a dose-dependent nitrite production with a half-maximal effective concentration (EC50) of 18.0 ± 1.5 μM (n = 4–7). This nitrite accumulation was not inhibited by the NO-synthase inhibitor NG-nitro-l-arginine methyl ester, l-NAME (300 μM). In contrast, it was abolished by miconazole (100 μM), an inhibitor of cytochrome P450. Incubation of vascular smooth muscle cells with LPS (10 μgml) induced an l-name inhibited nitrite accumulation, but did not enhance the OH-l-Arg induced nitrite production. OH-l-Arg and other cationic amino acids, L-lysine and l-ornithine, competitively inhibited [3H]-l-arginine uptake m rat aortic smooth muscle cells, with inhibition constants of 195 ± 23 μM(n = 12), 260 ± 40 μM(n= 5) and 330 ± 10 μM(n = 5), respectively. These results show that OH-l-Arg is recognized by the cationic l-amino acid carrier present in vascular smooth muscle cells and can be oxidized to NO and nitrite in these cells in the absence of NO-synthase, probably by cytochrome P450 or by a reaction involving a cytochrome P450 byproduct

Use of Z-pinch radiation sources for high-pressure shock wave studies

The authors are developing a new shock wave diagnostic using Z pinch sources for high-pressure equation of state (EOS) measurements. Specifically, they are employing VISAR interferometry to measure the particle velocity of shocked materials and fiber optic probes to measure the shock speed. Combination of these measurements will allow absolute EOS data with Z accelerators. This report is a progress report on the development of this new approach to EOS measurements; however, preliminary data obtained with the diagnostics are encouraging. With further development of Z pinch sources, it is envisioned that a variety of EOS and constitutive property measurements can be made. Time-resolved wave profile measurements will then provide a variety of EOS and material property data, such as isentropic EOS, initial compressive strength and shock-induced compressive strength, dynamic tensile strength, kinetics of phase transitions, and surface stability studies

Downscaling of real-time coastal flooding predictions for decision support

During coastal storms, forecasters and researchers use numerical models to predict the magnitude and extent of coastal flooding. These models must represent the large regions that may be affected by a storm, and thus, they can be computationally costly and may not use the highest geospatial resolution. However, predicted flood extents can be downscaled (by increasing resolution) as a post-processing step. Existing downscaling methods use either a static extrapolation of the flooding as a flat surface, or rely on subsequent simulations with nested, full-physics models at higher resolution. This research explores a middle way, in which the downscaling includes simplified physics to improve accuracy. Using results from a state-of-the-art model, we downscale its flood predictions with three methods: (1) static, in which the water surface elevations are extrapolated horizontally until they intersect the ground surface; (2) slopes, in which the gradient of the water surface is used; and (3) head loss, which accounts for energy losses due to land cover characteristics. The downscaling methods are then evaluated for forecasts and hindcasts of Hurricane Florence (2018), which caused widespread flooding in North Carolina. The static and slopes methods tend to over-estimate the flood extents. However, the head loss method generates a downscaled flooding extent that is a close match to the predictions from a higher-resolution, full-physics model. These results are encouraging for the use of these downscaling methods to support decision-making during coastal storms

Optimized workflow for on-line derivatization for targeted metabolomics approach by gas chromatography-mass spectrometry

Using manual derivatization in gas chromatography-mass spectrometry samples have varying equilibration times before analysis which increases technical variability and limits the number of potential samples analyzed. By contrast, automated derivatization methods can derivatize and inject each sample in an identical manner. We present a fully automated (on-line) derivatization method used for targeted analysis of different matrices. We describe method optimization and compare results from using off-line and on-line derivatization protocols, including the robustness and reproducibility of the methods. Our final parameters for the derivatization process were 20 µL of methoxyamine (MeOx) in pyridine for 60 min at 30 °C followed by 80 µL N-Methyl-N-trimethylsilyltrifluoracetamide (MSTFA) for 30 min at 30 °C combined with 4 h of equilibration time. The repeatability test in plasma and liver revealed a median relative standard deviation (RSD) of 16% and 10%, respectively. Serum samples showed a consistent intra-batch median RSD of 20% with an inter-batch variability of 27% across three batches. The direct comparison of on-line versus off-line demonstrated that on-line was fit for purpose and improves repeatability with a measured median RSD of 11% compared to 17% using the same method off-line. In summary, we recommend that optimized on-line methods may improve results for metabolomics and should be used where available

Thin-film cryogenic accelerator targets

Thin-film accelerator targets (0.1 mg/cm2 x 2) produced by condensation of various gases (Ar, Kr, Xe, N2, etc.) onto thin, cryogenically cooled substrates (T = 20 K to 80 K) have been developed and tested in-beam with 35 MeV 4He.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23775/1/0000013.pd