Review—Concentration Measurements In Molten Chloride Salts Using Electrochemical Methods

The electrochemical measurement of concentration in molten chloride salts is a valuable tool for the control of existing and potential industrial processes, recycling of precious materials and energy production. The electrochemical techniques commonly used to measure concentration and each techniques’ associated theory are discussed. Practices which improve measurement accuracy and precision are set forth. Exceptionally accurate and precise measurements published in the literature are evaluated based on their performance in specified concentration ranges. The strengths and weaknesses of the most accurate measurements are briefly explored. Chronopotentiometry (CP) and square wave voltammetry (SWV) are accurate and precise with low concentration measurements. SWV was accurate at low concentrations, even in multi-analyte mixtures. CP was accurate for only single analyte mixtures. Open-circuit potentiometry (OCP) is accurate and precise in single-analyte mixtures but yields large errors in multianalyte mixtures. Cyclic voltammetry (CV), chronoamperometry (CA) and normal pulse voltammetry (NPV) are accurate and precise across all concentration ranges. NPV is exceptionally well suited for measurements in melts with multiple electroactive species.

Localization in Stationary Non-equilibrium Solutions for Multicomponent Coagulation Systems

We consider the multicomponent Smoluchowski coagulation equation under non-equilibrium conditions induced either by a source term or via a constant flux constraint. We prove that the corresponding stationary non-equilibrium solutions have a universal localization property. More precisely, we show that these solutions asymptotically localize into a direction determined by the source or by a flux constraint: the ratio between monomers of a given type to the total number of monomers in the cluster becomes ever closer to a predetermined ratio as the cluster size is increased. The assumptions on the coagulation kernel are quite general, with isotropic power law bounds. The proof relies on a particular measure concentration estimate and on the control of asymptotic scaling of the solutions which is allowed by previously derived estimates on the mass current observable of the system.

Beef cattle methane emissions measured with tracer-ratio and inverse dispersion modelling techniques

The development and validation of management practices to mitigate greenhouse gas (GHG) emissions from livestock require accurate emission measurements. This study assessed the accuracy of a practical inverse dispersion modelling (IDM) technique to quantify methane (CH4) emitted from a small cattle herd (16 animals) confined to a 63 m × 60 m experimental pen. The IDM technique calculates emissions from the increase in the CH4 concentration measured downwind of the animals. The measurements were conducted for 7 d. Two types of open-path (OP) gas sensors were used to measure concentration in the IDM calculation: a Fourier transform infrared spectrometer (IDM-FTIR) or a CH4 laser (IDM-Laser). The actual cattle emission rate was measured with a tracer-ratio technique using nitrous oxide (N2O) as the tracer gas. We found very good agreement between the two IDM emission estimates (308.1 ± 2.1 – mean ± SE – and 304.4 ± 8.0 g CH4 head−1 d−1 for the IDM-FTIR and IDM-Laser respectively) and the tracer-ratio measurements (301.9 ± 1.5 g CH4 head−1 d−1). This study suggests that a practical IDM measurement approach can provide an accurate method of estimating cattle emissions.

Concentration and velocity measurements in experimental turbidity currents

<p>Turbidity currents are in the range of highly sediment concentrated flows, challenging traditional (i.e. optical and acoustic) techniques that aim to measure concentration and velocity quantities. In typical laboratory conditions, difficulties increase in the presence of highly non-uniform and unsteady flows. However, the measurement of those quantities along with a longitudinal profile is necessary to quantify and depict key mechanisms of mass and momentum transport, related to the mean and turbulent flow fields. The possible solutions often require prohibitive costs or resources. In this work, visual, acoustic, electrical, and statistical tools are tested. The aim of these tests is to find appropriate techniques and strategies for measuring concentration and velocity quantities in the broader research scope involving turbidity currents triggered by a 2D water jet. The outcomes will be applied in the quantification of turbidity currents with various boundary and initial conditions in a flume 4 m long, 2 m deep, and 22 cm wide. Additionally, the findings can potentially be transferred to other laboratory applications involving turbidity currents or other types of sediment-laden flows.</p><p>Acknowledgements: CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, a Foundation within the Ministry of Education in Brazil), grant number 88881.174820/2018-01.</p>

Distributionally Robust Conditional Quantile Prediction with Fixed Design

Conditional quantile prediction involves estimating/predicting the quantile of a response random variable conditioned on observed covariates. The existing literature assumes the availability of independent and identically distributed (i.i.d.) samples of both the covariates and the response variable. However, such an assumption often becomes restrictive in many real-world applications. By contrast, we consider a fixed-design setting of the covariates, under which neither the response variable nor the covariates have i.i.d. samples. The present study provides a new data-driven distributionally robust framework under a fixed-design setting. We propose a regress-then-robustify method by constructing a surrogate empirical distribution of the noise. The solution of our framework coincides with a simple yet practical method that involves only regression and sorting, therefore providing an explanation for its empirical success. Measure concentration results are obtained for the surrogate empirical distribution, which further lead to finite-sample performance guarantees and asymptotic consistency. Numerical experiments are conducted to demonstrate the advantages of our approach. This paper was accepted by Hamid Nazerzadeh, Special Issue on Data-Driven Prescriptive Analytics.

Effect of formalin fixation on measured concentrations of deposited gadolinium in human tissue: an autopsy study

Background Generally, studies of gadolinium (Gd) deposition in humans measure concentration by analyzing formalin fixed postmortem tissue. However, the effect of formalin fixation on measured Gd concentration has not been well investigated. Purpose To evaluate the effect of fixation by comparing Gd concentration in fresh versus formalin-fixed postmortem human tissues. Material and Methods Fresh samples of bone and skin were collected from autopsy cases with previous exposure to Gd-based contrast agents (GBCAs). The type of GBCA administered, dose, and estimated glomerular filtration rate were recorded. Each tissue sample was cut into three aliquots. Paired samples were stored fresh frozen while the remaining two were stored in 10% neutral buffered formalin for one and three months, respectively. Gd concentration was measured using ICP-MS. Results Of 18 autopsy cases studied, 12 were exposed to only macrocyclic GBCA, one to only linear agents, and five received both macrocyclic and linear agents. On average, Gd concentration for bone decreased 30.7% after one month of fixation ( P = 0.043) compared to non-fixed values. There was minimal, if any, change in concentration between one and three months (average decrease 1.5%; P = 0.89). The findings were numerically similar for skin tissue with an average decrease of 36.9% after one month ( P = 0.11) and 6.0% ( P = 0.73) between one and three months. Conclusion Formalin fixation appears to decrease Gd concentration in bone and skin by approximately 30%–40% on average. The largest decrease occurs within the first 30 days of fixation followed by a considerably smaller decrease at 60 days.

Shooting Athlete Mental Training

This study aims to determine the effect of meditation practice and internal imagery on the concentration and shooting accuracy of the 10-meter category in the Perbakin Bantul branch. The research method was experimental with a two-group pretest-posttests design. The population investigated 16 athletes using the purposive sampling technique so that the sample became 12 athletes. The research instrument used the Grid Concentration Exercise to measure concentration and measurement of firing accuracy using ISSF standard target targets. The data analysis technique used was paired t-test and independent t-test. The results showed an effect of training between autogenic meditation and internal images on concentration and shooting accuracy. When viewed from the percentage increase, the meditation practice method showed better results than internal imagery, while internal imagery training showed better results in increasing concentration.

On-farm beef cattle methane emissions measured with tracer-ratio and inverse-dispersion modelling techniques

The development and validation of management practices to mitigate greenhouse gas (GHG) emissions from livestock requires accurate emission measurements. This study assessed the accuracy of a practical inverse dispersion (IDM) micrometeorological technique to quantify methane (CH4) emitted from a small cattle herd (16 animals) confined to a 63 × 60 m pen. The IDM technique calculates emissions from the increase in CH4 concentration measured downwind of the animals. Two types of open-path (OP) gas sensors were used to measure concentration in the IDM calculation: a Fourier transform infrared spectrometer (IDM-FTIR) or a CH4 Laser (IDM-Laser). The actual cattle emission rate was given by a tracer-ratio technique using nitrous oxide as the tracer gas. We found very good agreement between the two IDM emission estimates (316 and 322 g CH4 head−1 d−1 for the IDM-FTIR and IDM-Laser, respectively) and the tracer-ratio measurements (315 g CH4 head−1 d−1). This study shows that a practical IDM measurement approach can provide an accurate method of estimating cattle emissions.