Changes In Saturation Levels Research Articles

Collaborative pollution and carbon reduction behaviors of carbonated Pb-contaminated soil stabilized with a low-carbon binder derived from waste concrete

Due to the limited hydration capacity, solidification/stabilization (S/S) with waste concrete powder (WCP) has a low strength. Carbonation can reduce carbon dioxide (CO2) emissions and improve strength of lead-contaminated soil, but its mechanism and environmental behaviors are unclear. In light of this, a comprehensive study was conducted on the compressive strength, lead immobilization, conductivity characteristics, and carbonation mechanism of carbonated Pb-contaminated soils stabilized with WCP compared to calcining 600 °C WCP. Results indicated that with carbonation, the compressive strength of the samples was significantly improved at the early stage (1 d), resulting in increased unconfined compressive strength (UCS) by 2.5-5.2 times due to the filling of pores by calcite. It negatively affected the lead immobilization capacity of highly doped (30%) samples, while this effect reversed after 3 d of carbonating due to the reduced alkaline environment. The lead immobilization capacity decreased after 28 d of carbonating due to the cracking of samples and the influence of a lower pH on the solubility of lead-carbonated hydroxide ((PbCO3)2Pb(OH)2). The water evaporation (saturation <16.8%) led to dry shrinkage cracking and decreased UCS of the samples. Based on this finding, a conductivity model was developed for carbonated and cured samples, accurately predicting changes in saturation levels (R2 = 0.98). A relationship between conductivity and UCS or lead immobilization capacity was proposed. This research proposed an innovative method for the reduction of CO2 emission as well as laid down a theoretical basis for the recovery of WCP and lead-contaminated soils through carbonation.

Development of a method for differential analysis of data on the arterial blood oxygenation in healthy adults

Monitoring of arterial blood saturation with oxygen (oxygenation) has gained special significance as a result of the COVID-19 pandemic. A new method for computer processing of saturation records (so-called SaO2 signals), based on the study of differentials (increments) from signals, was proposed. Finding a differential for a time series involves calculating the difference between the pairs of its adjacent elements. The differential is non-zero only if the elements in a pair are different. The study of differentials together with primary signals for a set of records (20 subjects) shows that the spectrum of observed levels of blood saturation is discrete and limited (from 2 to 10 levels). In addition, changes in saturation levels (switches) occur only between the nearest levels. New indicators of the variability of blood saturation were proposed. These are the frequencies of saturation level switches (event intensities) and the intervals between them. It was established that these indicators are described by statistical distributions of Poisson and Erlang, respectively. Comparison of new variability indicators with the most reliable statistical – inter-quartile range – indicates that the new indicators also provide for the division of the data set into three subgroups according to the magnitude of variability. This division is statistically significant at a confidence level of 0.99 in both approaches, however, the division into sub-groups is slightly different in these methods. It was shown that the proposed indicators of the variability of SaO2 signals are scale-invariant, that is, they do not depend on the length of observation interval. This is a consequence of the fractality of the positions of differentials in the observation interval. The established switch frequencies for subgroups in order of increasing variability are (0.06, 0.11, and 0.20) Hz. These frequencies are manifested on Fourier spectra of differentials of SaO2

Role of stable eigenmodes in saturated local plasma turbulence

The excitation of stable eigenmodes in unstable plasma turbulence, previously documented in collisionless trapped electron mode turbulence, is shown to be a generic behavior of local (quasihomogeneous) systems. A condition is derived to indicate when such excited eigenmodes achieve a sufficient level in saturation to affect the turbulence, and produce changes in saturation levels, instability drive, and transport. The condition is shown to be consistent with the results of collisionless and dissipative trapped electron turbulence, and is further illustrated by an entirely different model describing simple ion turbulence driven by the ion temperature gradient. The condition suggests that all eigenmodes of the ion model affect saturation, but none dominates. This is consistent with the results of simulations, which show nonlinear modifications to eigenmode structure, growth rate, and transport that occur intermittently in time, despite fixed driving gradients.

Changes of lipid composition and saturation level in leaves and roots for heat-stressed and heat-acclimated creeping bentgrass ( Agrostis stolonifera)

Changes in membrane lipid compositions and saturation levels during high temperature acclimation and heat stress were investigated in leaf and root tissues for three cultivars of creeping bentgrass ( Agrostis stolonifera) that differ in heat tolerance. ‘L-93’ (heat tolerant), ‘Penncross’ (heat sensitive) and ‘Crenshaw’ (intermediate) showed differential decreases in grass visual quality (leaf color and shoot density), increases in TBARS (a measure of oxidative damage), increases in membrane leakage and decreases in chlorophyll content of leaves during 28 days of heat stress (35 °C) in a growth chamber study. Total lipid extracts from the leaves of all three cultivars showed that the lipid saturation level increased over time under heat stress, with the change being predominantly due to decreases in linolenic acid and increases in linoleic and palmitic acids. The only significant difference in leaf lipid saturation between the three cultivars was that L-93 extracts contained a higher proportion of saturated lipids prior to heat stress than the other two cultivars. No cultivar differences in lipid composition were detected during heat stress. Penncross plants given a mild heat pre-treatment (30 °C) (heat acclimated) prior to being exposed to heat stress (35 °C) showed increased saturation of leaf lipids at the initiation of heat stress. There were no significant differences in root lipid composition between heat-acclimated and non-acclimated plants. Penncross plants which had acquired thermotolerance through heat acclimation, and heat tolerant L-93 plants showed similar leaf lipid composition at the initiation of heat stress, and similar levels of thermotolerance during heat stress. These results imply that there may be some connection between the degree of saturation of leaf membrane lipids prior to heat stress and the ability of that plant to limit heat-induced damages during the stress period. Root lipid extracts from the three cultivars showed no change in saturation levels during heat stress. However, Penncross root extracts contained a lower proportion of saturated lipids than L-93 or Crenshaw. These results suggest that lipid composition or saturation level of roots could be an important factor in controlling plant tolerance to heat stress.

Moisture diffusion in epoxy systems

The moisture diffusion process of an epoxy system is studied as a function of epoxy-amine stoichiometry and the resulting microstructure. Differences in diffusion behavior are related to the relative importance of diffusion through the low-density and high-density microstructural phases for different stoichiometries. Also, changes in saturation level with stoichiometry are explained by competing effects of free volume versus the content of the low-density phase. Increasing the humidity level causes a corresponding increase in saturation level, while increasing the temperature causes more pronounced non-Fickian behavior. The effects of absorbed moisture on the thermomechanical properties of the epoxies are also investigated. Reductions in the glass transition temperature, Tg, and moisture-induced swelling strains are measured after exposure of samples to the three conditioning environments. Moisture-induced swelling strains increase with increasing moisture content. The reductions in Tg range from 5 to 20°C and are generally larger for amine-rich samples than for epoxy-rich and stoichiometric samples. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 787–798, 1999

Field-oriented control of saturated induction machines

A nonlinear, field-oriented model is described for saturated induction machines. The model is an extended version of the rotor-flux-oriented dynamic model developed by W. Leonhard (1985), which is valid under linear magnetic conditions and is used in a wide range of applications. The effects of main flux saturation are discussed. The theory is applied to an induction machine subjected to field-oriented control which operates in the field-weakening region where the changes of saturation level play an important role in the dynamic behavior. It is also shown that, with the implemented current control, the control response is seriously distorted by the effects of variable saturation during field weakening. >