Effect of Humic Substances and Silicon Ions on Stability of Iron Hydroxide (III) Nanoparticles

2013 ◽  
Vol 872 ◽  
pp. 237-240 ◽  
Author(s):  
Ludmila N. Shiyan ◽  
Ksenia I. Machekhina ◽  
Elena A. Tropina ◽  
Elena N. Gryaznova ◽  
Vladimir V. An
Keyword(s):  
Steady State ◽  
Humic Substances ◽  
Organic Substance ◽  
Iron Hydroxide ◽  
Molar Ratio ◽  
Colloidal System ◽  
Colloid System ◽  
System Composition ◽  
Silicon Ions ◽  
The Stability

The paper reports on experimental modeling of the colloid system composition in natural groundwater. It is shown that the stability of iron hydroxide nanoparticles relates to the presence of silica and humic substances. It was found out the molar ratio of iron/silicon/organic substance is equal to 1/7/2, where stable iron (III) hydroxide nanoparticles form. The iron hydroxide nanoparticle size ranging from 30 to 600 nm was determined. It characterizes the steady state of the colloidal system.

The Forming of Model Colloid System

2014 ◽  
Vol 971-973 ◽  
pp. 266-269 ◽  
Author(s):  
Denis A. Voyno ◽  
Ksenia I. Machekhina ◽  
Ludmila N. Shiyan
Keyword(s):  
Water Treatment ◽  
Zeta Potential ◽  
Electrostatic Interaction ◽  
Organic Substance ◽  
Test System ◽  
Molar Ratio ◽  
Organic Substances ◽  
Mechanism Of Formation ◽  
Iron Silicon ◽  
Colloid System

The paper reports on the creation of a model colloid test system which is similar to groundwater and it can be used as a test system in the water treatment. It is found that at the molar ratio iron/silicon/organic substance is equal to1/7/2 and two orders such as organic substances-Si-Fe and Si-organic substances-Fe, stable colloid system is formed. The mechanism of formation of iron colloid system is described by three steps. The first is the formation of the organosilicon complexes. The second is oxidation of the iron and forming of Fe (OH)3. The last is forming a sol at zeta potential is - 35 mV with electrostatic interaction.

scholarly journals Microemulsion Stability of Virgin Coconut Oil Based on Tradition of Melala Sumbawa's Society

2021 ◽  
Vol 4 (2) ◽  
pp. 120-126
Author(s):  
Devi Ayu Septiani ◽  
Jono Irawan ◽  
Hermansyah Hermansyah ◽  
Yayuk Andayani
Keyword(s):  
Laboratory Experiments ◽  
Physical Stability ◽  
Coconut Oil ◽  
Coconut Milk ◽  
Colloidal System ◽  
Virgin Coconut Oil ◽  
Colloid System ◽  
Oil In Water ◽  
Isolation Methods ◽  
The Stability

The Melala is a tradition of the Sumbawa people who use coconut milk to obtain Sumbawa oil for traditional medicine. Coconut milk is a colloidal system of stable oil in water (O/W) microemulsion. Within a particular time, the emulsion will split to produce oil (VCO), protein, and water due to the colloid equilibrium on the stability of the coconut milk emulsion. The purpose of this study was to compare the microemulsion stability of the coconut milk colloid system. The VCO was isolated by heating, enzymatically, acidifying, and adding whiting methods for comparison. The physical stability of the O/W microemulsion was measured by the volume of VCO produced from various isolation methods in simple laboratory experiments. The results showed that the physical stability of the O/W microemulsion on VCO isolation by enzymatic method using papain enzyme was the least.

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

The Stability of Steady-State Depth Distributions of Marine Phytoplankton

1974 ◽  
Vol 108 (963) ◽  
pp. 679-687 ◽  
Author(s):  
W. O. Criminale, ◽  
D. F. Winter
Keyword(s):  
Steady State ◽  
Marine Phytoplankton ◽  
The Stability ◽  
Depth Distributions

scholarly journals Steady-state $$\dot{V}{\text{O}}_{2}$$ above MLSS: evidence that critical speed better represents maximal metabolic steady state in well-trained runners

2021 ◽  
Author(s):  
Rebekah J. Nixon ◽  
Sascha H. Kranen ◽  
Anni Vanhatalo ◽  
Andrew M. Jones
Keyword(s):  
Steady State ◽  
Critical Speed ◽  
Lactate Concentration ◽  
Practical Interest ◽  
Blood Lactate Concentration ◽  
Distance Runners ◽  
Severe Intensity ◽  
The Stability ◽  
Trained Runners ◽  
Over Time

AbstractThe metabolic boundary separating the heavy-intensity and severe-intensity exercise domains is of scientific and practical interest but there is controversy concerning whether the maximal lactate steady state (MLSS) or critical power (synonymous with critical speed, CS) better represents this boundary. We measured the running speeds at MLSS and CS and investigated their ability to discriminate speeds at which $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 was stable over time from speeds at which a steady-state $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 could not be established. Ten well-trained male distance runners completed 9–12 constant-speed treadmill tests, including 3–5 runs of up to 30-min duration for the assessment of MLSS and at least 4 runs performed to the limit of tolerance for assessment of CS. The running speeds at CS and MLSS were significantly different (16.4 ± 1.3 vs. 15.2 ± 0.9 km/h, respectively; P < 0.001). Blood lactate concentration was higher and increased with time at a speed 0.5 km/h higher than MLSS compared to MLSS (P < 0.01); however, pulmonary $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 did not change significantly between 10 and 30 min at either MLSS or MLSS + 0.5 km/h. In contrast, $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 increased significantly over time and reached $$\dot{V}{\text{O}}_{2\,\,\max }$$ V ˙ O 2 max at end-exercise at a speed ~ 0.4 km/h above CS (P < 0.05) but remained stable at a speed ~ 0.5 km/h below CS. The stability of $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 at a speed exceeding MLSS suggests that MLSS underestimates the maximal metabolic steady state. These results indicate that CS more closely represents the maximal metabolic steady state when the latter is appropriately defined according to the ability to stabilise pulmonary $$\dot{V}{\text{O}}_{2}$$ V ˙ O 2 .

scholarly journals Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2039
Author(s):  
Gamal A. E. Mostafa ◽  
Ahmed Bakheit ◽  
Najla AlMasoud ◽  
Haitham AlRabiah
Keyword(s):  
Charge Transfer ◽  
Spectroscopic Characterization ◽  
Molar Ratio ◽  
Charge Transfer Complexes ◽  
Physical Parameters ◽  
Spectrophotometric Methods ◽  
Theoretical Approaches ◽  
The Stability ◽  
Ct Complexes

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.

scholarly journals Nonlinear Dynamics and Stability Analysis of a Three-Cell Flying Capacitor DC-DC Converter

2021 ◽  
Vol 11 (4) ◽  
pp. 1395
Author(s):  
Abdelali El Aroudi ◽  
Natalia Cañas-Estrada ◽  
Mohamed Debbat ◽  
Mohamed Al-Numay
Keyword(s):  
Steady State ◽  
Stability Analysis ◽  
Monodromy Matrix ◽  
Dynamical Behavior ◽  
Period Doubling ◽  
Simple Expression ◽  
Buck Converter ◽  
State Variables ◽  
Bifurcation Phenomena ◽  
The Stability

This paper presents a study of the nonlinear dynamic behavior a flying capacitor four-level three-cell DC-DC buck converter. Its stability analysis is performed and its stability boundaries is determined in the multi-dimensional paramertic space. First, the switched model of the converter is presented. Then, a discrete-time controller for the converter is proposed. The controller is is responsible for both balancing the flying capacitor voltages from one hand and for output current regulation. Simulation results from the switched model of the converter under the proposed controller are presented. The results show that the system may undergo bifurcation phenomena and period doubling route to chaos when some system parameters are varied. One-dimensional bifurcation diagrams are computed and used to explore the possible dynamical behavior of the system. By using Floquet theory and Filippov method to derive the monodromy matrix, the bifurcation behavior observed in the converter is accurately predicted. Based on justified and realistic approximations of the system state variables waveforms, simple and accurate expressions for these steady-state values and the monodromy matrix are derived and validated. The simple expression of the steady-state operation and the monodromy matrix allow to analytically predict the onset of instability in the system and the stability region in the parametric space is determined. Numerical simulations from the exact switched model validate the theoretical predictions.

STABILITY OF STEADY STATE AND TRAVELING WAVES SOLUTIONS IN COUPLED MAP LATTICES

2008 ◽  
Vol 18 (01) ◽  
pp. 219-225 ◽  
Author(s):  
DANIEL TURZÍK ◽  
MIROSLAVA DUBCOVÁ
Keyword(s):  
Steady State ◽  
Essential Spectrum ◽  
Traveling Waves ◽  
Traveling Wave ◽  
Traveling Wave Solutions ◽  
Linear Operators ◽  
Coupled Map Lattices ◽  
Basic Tool ◽  
Wave Solutions ◽  
The Stability

We determine the essential spectrum of certain types of linear operators which arise in the study of the stability of steady state or traveling wave solutions in coupled map lattices. The basic tool is the Gelfand transformation which enables us to determine the essential spectrum completely.

The flow of a micropolar liquid layer down an inclined plane

1968 ◽  
Vol 64 (2) ◽  
pp. 513-526 ◽  
Author(s):  
A. J. Willson
Keyword(s):  
Thin Films ◽  
Steady State ◽  
Liquid Layer ◽  
Stability Criterion ◽  
Long Waves ◽  
Inclined Plane ◽  
The Stability ◽  
Micropolar Liquid

AbstractConsideration is given to the flow of a micropolar liquid down an inclined plane. The steady state is analysed and Yih's technique is employed in an investigation of the stability of this flow with respect to long waves. Detailed calculations are given for thin films and it is shown that the micropolar properties of the liquid play an important role in the stability criterion.

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