scholarly journals Miscible displacement of copper in soil columns using increasing doses of bentonite

2019 ◽  
pp. 1126-1130
Author(s):  
Gilvanise Alves Tito ◽  
Lucia Helena Garófalo Chaves ◽  
Hugo Orlando Carvallo Guerra ◽  
Josely Dantas Fernandes ◽  
Jacqueline da Silva Mendes ◽  
...  
Keyword(s):  
Steady State ◽  
Experimental Design ◽  
Flux Density ◽  
Environmental Contamination ◽  
Breakthrough Curves ◽  
Miscible Displacement ◽  
Soil Columns ◽  
Steady State Flux ◽  
Potential Risks ◽  
Leaching Columns

The objective of this research was to evaluate the effect of applying increasing doses of bentonite to the soil on the miscible displacement of copper, quantifying copper retention in the soil and elimination by leachate, in order to prevent potential risks for environmental contamination. The experiment was conducted on a laboratory using leaching columns filled by a sandy texture soil contaminated with 250 mg kg-1 of copper each. The experimental design was a completely randomized with four doses of bentonite, 0; 30; 60 and 90 t ha-1, and three replications totalizing 12 experimental units. The leaching columns were made with PVC tubes constituted by three rings, overlaid and joined with silicone glue. Each column was filled with 4 kg of Cu contaminated soil, mixed with the doses of bentonite specified by the treatments (0; 45; 90 and 135 g). After the filling of the columns, each one received five pore volumes of distillated water, and left to percolation under a steady state flux. After percolation, the Cu concentrations in the soil and in the percolate, the breakthrough curves of the flux density and the percolation velocity were determined. The results were submitted to variance analyses using the F test and regressions. The increasing doses of bentonite until 90 t ha-1 increased the adsorption of copper by the soil, reducing the percolation of this element around 72%. Bentonite application to the soil decreased the flux density and flux velocity of the copper percolation, diminishing the potential risks for the environment contamination.

scholarly journals Imazapic interaction and mobility in soil cultivated with sugarcane in northeast Brazil

RBRH ◽  
2021 ◽  
Vol 26 ◽  
Author(s):  
Fernando Xavier de Assis ◽  
André Maciel Netto ◽  
Bruno Toríbio de Lima Xavier ◽  
Valmir Felix de Lima ◽  
João Paulo Siqueira da Silva
Keyword(s):  
Partition Coefficients ◽  
Biological Effects ◽  
Clay Content ◽  
Breakthrough Curves ◽  
Northeastern Brazil ◽  
Adsorption Potential ◽  
Soil Columns ◽  
Leaching Potential ◽  
Physical Chemical ◽  
Sorption Leaching

ABSTRACT In the plantation of sugarcane, Imazapic has used pre- or post-emergence, alone or in combination with other herbicides. When applied to the soil in pre-emergence, Imazapic can undergo the sorption, leaching and/or degradation processes due to physical, chemical and biological effects, besides being absorbed by weeds. The objective of this work was to evaluate the interaction and mobility of the Imazapic herbicide in the soil where the soil columns with a dystrophic Yellow Ultisol (YUd) and a dystrophic Red-Yellow Oxisol (RYOd) from northeastern Brazil were used. The higher adsorption potential of the RYOd is associated with higher clay content, higher Fed and Feo concentrations, and soil acidic pH. The CDE – 2 sorption sites model adequately represented the experimental data from the Imazapic breakthrough curves to the RYOd and YUd soils. From the Kd partition coefficients for RYOd and YUd, high values of the GUS index (5.94 and 7.04, respectively) were calculated, confirming the high leaching potential of the Imazapic molecule in these soils.

scholarly journals Improving the Antitumor Activity and Bioavailability of Sonidegib for the Treatment of Skin Cancer

Pharmaceutics ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1560
Author(s):  
Amr Gamal ◽  
Haitham Saeed ◽  
Fatma I. Abo El-Ela ◽  
Heba F. Salem
Keyword(s):  
Steady State ◽  
Skin Cancer ◽  
Entrapment Efficiency ◽  
The United States ◽  
Relative Bioavailability ◽  
Passive Targeting ◽  
Therapeutic Benefits ◽  
Steady State Flux

Throughout the United States and the world, skin cancer is the most frequent form of cancer. Sonidegib (SNG) is a hedgehog inhibitor that has been used for skin cancer treatment. However, SNG has low bioavailability and is associated with resistance. The focus of this work is to enhance bioavailability, anti-tumor efficacy and targeting of SNG via developing ethosome gel as a potential treatment for skin cancer. SNG-loaded ethosomes formulation was prepared and characterized in vitro by %entrapment efficiency (%EE), vesicle size, morphology, %release and steady-state flux. The results showed that the prepared formulation was spherical nanovesicles with a %EE of 85.4 ± 0.57%, a particle size of 199.53 ± 4.51 nm and a steady-state flux of 5.58 ± 0.08 µg/cm2/h. In addition, SNG-loaded ethosomes formulation was incorporated into carbopol gel to study the anti-tumor efficacy, localization and bioavailability in vivo. Compared with oral SNG, the formulation showed 3.18 times higher relative bioavailability and consequently significant anti-tumor activity. In addition, this formulation showed a higher rate of SNG penetration in the skin’s deep layers and passive targeting in tumor cells. Briefly, SNG-loaded ethosome gel can produce desirable therapeutic benefits for treatment of skin cancer.

Theory of production rate calculations in steady and non-steady states and its application to glucose metabolism

1992 ◽  
Vol 262 (6) ◽  
pp. E779-E790 ◽  
Author(s):  
J. A. Jacquez
Keyword(s):  
Steady State ◽  
Experimental Design ◽  
Specific Activity ◽  
Glucose Production ◽  
Central Compartment ◽  
Correct Equation ◽  
Endogenous Production ◽  
Correction Terms ◽  
Theory Of Production ◽  
Constant Specific Activity

I present a review and synthesis of the basic theory, steady state, and non-steady state for the calculation of metabolite production rates for systems that have a central well-mixed compartment that is the site of tracer input and sampling. The theory is then applied to the calculation of glucose production. If the only inputs are into the central compartment, an experimental design that involves varying tracer infusion rates to maintain constant specific activity in the central compartment and the same constant specific activity in the peripheral compartments allows calculation of the endogenous production. That holds even if the models are unidentifiable. The correct equation and Steele's pool fraction approximation reduce to the same result for this experimental design. However, that does not justify the use of Steele's equation when there are deviations from the exact experimental design. When the specific activity in the central compartment is not constant, model-dependent correction terms to Steele's equation are needed.

Miscible Displacement of Zinc in Soil Columns: Linear and Nonlinear Modeling

2013 ◽  
Vol 77 (2) ◽  
pp. 391-402 ◽  
Author(s):  
H. M. Selim ◽  
Tamer A. Elbana ◽  
Keli Zhao ◽  
Jianming Xu ◽  
Eric L. Fergusson
Keyword(s):  
Nonlinear Modeling ◽  
Miscible Displacement ◽  
Soil Columns ◽  
Linear And Nonlinear

scholarly journals Accelerating Kinetic Parameter Identification by Extracting Information from Transient Data: A Hydroprocessing Study Case

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 361
Author(s):  
Ngoc-Yen-Phuong Cao ◽  
Benoit Celse ◽  
Denis Guillaume ◽  
Isabelle Guibard ◽  
Joris W. Thybaut
Keyword(s):  
Steady State ◽  
Experimental Design ◽  
Kinetic Model ◽  
Kinetic Modeling ◽  
Sufficient Data ◽  
Design Algorithm ◽  
State Data ◽  
Transient Data ◽  
Study Case ◽  
The One

Hydroprocessing reactions require several days to reach steady-state, leading to long experimentation times for collecting sufficient data for kinetic modeling purposes. The information contained in the transient data during the evolution toward the steady-state is, at present, not used for kinetic modeling since the stabilization behavior is not well understood. The present work aims at accelerating kinetic model construction by employing these transient data, provided that the stabilization can be adequately accounted for. A comparison between the model obtained against the steady-state data and the one after accounting for the transient information was carried out. It was demonstrated that by accounting for the stabilization, combined with an experimental design algorithm, a more robust and faster manner was obtained to identify kinetic parameters, which saves time and cost. An application was presented in hydrodenitrogenation, but the proposed methodology can be extended to any hydroprocessing reaction.

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