Recreation and terrain effect on the spatial variation of the apparent soil electrical conductivity in an urban park

Recreation is an important cultural ecosystem service and is able to significantly affect soil heterogeneity and vegetation func-tioning. This study investigated the role of the relief and tree stand density in the apparent soil electrical conductivity variation within an urban park. The most suitable variogram models were assessed to evaluate the autocorrelation of the regression models. The map of the spatial variability of apparent soil electrical conductivity was built on the basis of the most suitable variogram. The experimen-tal polygon was located in the Botanical Garden of Oles Honchar Dnipro National University (Dnipro City, Ukraine). The experi-mental polygon was formed by a quasi-regular grid of measurement locations located about 30 m apart. The measurements of the apparent electrical conductivity of the soil in situ were made in May 2018 at 163 points. On average, the value of soil apparent elec-tric conductivity within the investigated polygon was 0.55 dSm/m and varied within 0.17–1.10 dSm/m. Such environment predictors as tree stand density, relief altitude, topographic wetness index, and potential of relief to erosion were able to explain 48% of the observed variability of soil electrical conductivity. The relief altitude had the greatest influence on the variation of soil electrical con-ductivity, which was indicated with the highest values of beta regression coefficients. The most important trend of the electric con-ductivity variation was due to the influence of relief altitude and this dependence was nonlinear. The smallest values of the soil elec-trical conductivity were recorded in the highest and in lowest relief positions, and the largest values were detected in the relief slope. Recreational load can also be explained by the geomorphology predictors and tree stand density data. These predictors can explain 32% of the variation of recreational load. The variogram was built both for the soil apparent electrical conductivity dataset and for the residuals of the regression model. As a result of the procedure of the models’ selection on the basis of the AIC we obtained the best estimation of the variogram models parameters for the electrical conductivity and for the regression residuals of the electrical conduc-ti vity. The level of recreation was correlated statistically significantly with the apparent soil electrical conductivity. The residuals of regression models in which geomorphological indicators and tree stand density were used as predictors have a higher correlation level than the original variables. The soil electrical conductivity may be a sensitive indicator of the recreation loa

Electrochemical Determination of Sudan Dyes and Two Manner to Realise it a Theoretical Investigation

In this work, a general theoretical description of the electrochemical determination of Sudan dyes by cathodic and anodic route has been made. Two mathematical models have been developed for each case, being, afterward, analyzed by means of linear stability theory and bifurcation analysis. It has been shown that in both cases, the systems are efficient from the electroanalytical point of view. The possibility for the oscillatory and monotonic instability has also been verified

A descrição matemática da detecção eletroquímica da tetrodoxina, assistida pelo íon amavadina

Tetrodoxina (Fig. 1) é uma neurotoxina, que se produz em alguns organismos aquáticos como peixes, polvos e alguns caranguejos [1]. Estes organismos produzem-na para fins de proteção. A sua ação sobre o sistema nervoso inclui o bloqueio dos canais de sódio, o que leva ao enfraquecimento das paredes celulares do sistema nervoso. Os sintomas da intoxicação são enxaqueca, aumento de parestesia de face e extremidades, dor epigástrica, diarreia e vômito, cianose, convulsões e hipotensão. A morte pode ocorrer no período entre 20 minutos e 8 horas depois da ingestão, a depender da dose e das características do organismo. Destarte, o desenvolvimento de um método da determinação da tetrodoxina é, sem dúvida, atua

Theoretical Description for Anti-COVID-19 Drug Remdesivir Electrochemical Determination, Assisted by Squaraine Dye – Ag2O2 Composite

For the first time, the remdesivir anti-COVID-19 drug electrochemical determination has been evaluated theoretically. In this work, an anodic process involving the Squaraine Dye – Ag2O2 composite has been evaluated. The mechanism of the electroanalytical process is branched, which implies relatively dynamic behavior. Nevertheless, the correspondent mathematical model analysis, made by linear stability theory and bifurcation analysis, confirms the composite electroanalytical efficiency as an electrode modifie