Recommendations for nomenclature of ionselective electrodes (IUPAC Recommendations 1994)

The rapid growth of interest in the field of ion-selective electrodes (ISEs), within the larger field of electrochemical sensors based on potentiometric, amperometric, and conductometric principles, makes it highly desirable to achieve improved standardization of nomenclature in this area. The previous document, WAC Recommendations 1975 (1) has been corrected using recent experimental and theoretical findings. This report does not define or recommend activity standards or calibration procedures using activity standard

Isomorphic classical molecular dynamics model for an excess electron in a supercritical fluid

Ring polymer molecular dynamics (RPMD) is used to directly simulate the dynamics of an excess electron in a supercritical fluid over a broad range of densities. The accuracy of the RPMD model is tested against numerically exact path integral statistics through the use of analytical continuation techniques. At low fluid densities, the RPMD model substantially underestimates the contribution of delocalized states to the dynamics of the excess electron. However, with increasing solvent density, the RPMD model improves, nearly satisfying analytical continuation constraints at densities approaching those of typical liquids. In the high density regime, quantum dispersion substantially decreases the self-diffusion of the solvated electron. In this regime where the dynamics of the electron is strongly coupled to the dynamics of the atoms in the fluid, trajectories that can reveal diffusive motion of the electron are long in comparison to $\beta\hbar$.Comment: 24 pages, 4 figure

alpha-nucleus potentials for the neutron-deficient p nuclei

alpha-nucleus potentials are one important ingredient for the understanding of the nucleosynthesis of heavy neutron-deficient p nuclei in the astrophysical gamma-process where these p nuclei are produced by a series of (gamma,n), (gamma,p), and (gamma,alpha) reactions. I present an improved alpha-nucleus potential at the astrophysically relevant sub-Coulomb energies which is derived from the analysis of alpha decay data and from a previously established systematic behavior of double-folding potentials.Comment: 6 pages, 3 figures, accepted for publication in Phys. Rev.

Characterization of Knots and Links Arising From Site-specific Recombination on Twist Knots

We develop a model characterizing all possible knots and links arising from recombination starting with a twist knot substrate, extending previous work of Buck and Flapan. We show that all knot or link products fall into three well-understood families of knots and links, and prove that given a positive integer $n$, the number of product knots and links with minimal crossing number equal to $n$ grows proportionally to $n^5$. In the (common) case of twist knot substrates whose products have minimal crossing number one more than the substrate, we prove that the types of products are tightly prescribed. Finally, we give two simple examples to illustrate how this model can help determine previously uncharacterized experimental data.Comment: 32 pages, 7 tables, 27 figures, revised: figures re-arranged, and minor corrections. To appear in Journal of Physics

Short-term rotations using the forage legume Lablab have a place in Central Queensland farming systems

Soil nitrogen fertility decline is a problem for the farmers of Central Queensland (CQ). Nitrogen fertilisers are now widely used, but an erratic climate means that economic returns are not always achieved. Two farmer groups in CQ have ongoing experiments to make economic comparisons between a lablab/cereal rotation and conventional grain cropping regimes. At Fernlees, a sequence of lablab/sorghum/wheat is being compared with wheat/sorghum/chickpea on a low fertility open downs soil. At Theodore, an unfertilised lablab/sorghum rotation is being compared with continuous fertilised sorghum. Results after three seasons indicate that the nitrogen benefit to subsequent crops plus returns from a ley legume phase can offset the opportunity cost of not growing a grain crop on a low fertility soil

Evaluation of Machine Learning Tools for Inspection of Steam Generator Tube Structures using Pulsed Eddy Current

Inspection of multi-component systems, such as nuclear steam generator (SG) tube support structures, is complicated by multiple overlapping degradation modes. The simultaneous and precise measurement of more than two interdependent parameters is challenging when standard statistical regression analysis tools are used. Artificial neural networks (ANNs) have recently been applied to pulsed eddy current (PEC) data for inspection of Alloy 800 SG tube fretting, in the presence of tube off-set within a corroded ferromagnetic support structure. Signals were analyzed using modified principal component analysis (MPCA) followed by an ANN analysis, which simultaneously targeted four parameters associated with the support structure. These were hole diameter, tube off-centering in two mutually orthogonal directions and fret depth. In this work, the ANN analysis is compared with that performed by a Support Vector Machine (SVM) analysis of the same data. Comparable results are achieved for some parameters with both machine learning analysis tools. However, parameters with changing signal variance, such as those associated with support structure diameter, are not as easily compensated for using standard SVM analysis. Both techniques also rely on the availability of a representative training data set that may be difficult to come by for general inspection conditions

Physiological effects of environmental acidification in the deep-sea urchin <i>Strongylocentrotus fragilis</i>

Anthropogenic CO₂ is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of elevated <i>p</i>CO₂ and variable O₂ on the deep-sea urchin <i>Strongylocentrotus fragilis</i>, a species whose range of 200–1200 m depth includes the OMZ and spans a <i>p</i>CO₂ range of approx. 600–1200 μatm (approx. pH 7.6 to 7.8). Individuals were evaluated during two exposure experiments (1-month and 4 month) at control and three levels of elevated <i>p</i>CO₂ at in situ O₂ levels of approx. 10% air saturation. A treatment of control <i>p</i>CO₂ at 100% air saturation was also included in experiment two. During the first experiment, perivisceral coelomic fluid (PCF) acid-base balance was investigated during a one-month exposure; results show <i>S. fragilis</i> has limited ability to compensate for the respiratory acidosis brought on by elevated <i>p</i>CO₂, due in part to low non-bicarbonate PCF buffering capacity. During the second experiment, individuals were separated into fed and fasted experimental groups, and longer-term effects of elevated <i>p</i>CO₂ and variable O₂ on righting time, feeding, growth, and gonadosomatic index (GSI) were investigated for both groups. Results suggest that the acidosis found during experiment one does not directly correlate with adverse effects during exposure to realistic future <i>p</i>CO₂ levels

State-to-State Differential and Relative Integral Cross Sections for Rotationally Inelastic Scattering of H2O by Hydrogen

State-to-state differential cross sections (DCSs) for rotationally inelastic scattering of H2O by H2 have been measured at 71.2 meV (574 cm-1) and 44.8 meV (361 cm-1) collision energy using crossed molecular beams combined with velocity map imaging. A molecular beam containing variable compositions of the (J = 0, 1, 2) rotational states of hydrogen collides with a molecular beam of argon seeded with water vapor that is cooled by supersonic expansion to its lowest para or ortho rotational levels (JKaKc= 000 and 101, respectively). Angular speed distributions of fully specified rotationally excited final states are obtained using velocity map imaging. Relative integral cross sections are obtained by integrating the DCSs taken with the same experimental conditions. Experimental state-specific DCSs are compared with predictions from fully quantum scattering calculations on the most complete H2O-H2 potential energy surface. Comparison of relative total cross sections and state-specific DCSs show excellent agreement with theory in almost all detailsComment: 46 page