EFFECT OF NONCLASSICAL POLARIZATION OF Na+ AND K+ ON THE STABILITY OF SOIL COLLOIDAL PARTICLES IN SUSPENSION

The study of soil colloids is essential because the stability of soil colloidal particles are important processes of interest to researchers in environmental fields. The strong nonclassical polarization of the adsorbed cations (Na[Formula: see text] and K[Formula: see text] decreased the electric field and the electrostatic repulsion between adjacent colloidal particles. The decrease of the absolute values of surface potential was greater for K[Formula: see text] than for Na[Formula: see text]. The lower the concentration of Na[Formula: see text] and K[Formula: see text] in soil colloids, the greater the electrostatic repulsion between adjacent colloidal particles. The net pressure and the electrostatic repulsion was greater for Na[Formula: see text] than for K[Formula: see text] at the same ion concentration. For K[Formula: see text] and Na[Formula: see text] concentrations higher than 50[Formula: see text]mmol L[Formula: see text] or 100 mmol L[Formula: see text], there was a net negative (or attractive) pressure between two adjacent soil particles. The increasing total average aggregation (TAA) rate of soil colloids with increasing Na[Formula: see text] and K[Formula: see text] concentrations exhibited two stages: the growth rates of TAA increased rapidly at first and then increased slowly and eventually almost negligibly. The critical coagulation concentrations of soil colloids in Na[Formula: see text] and K[Formula: see text] were 91.6[Formula: see text]mmol L[Formula: see text] and 47.8[Formula: see text]mmol L[Formula: see text], respectively, and these were similar to the concentrations at the net negative pressure.

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Facile Organometallic Synthesis of Fe-Based Nanomaterials by Hot Injection Reaction

Nanomaterials ◽

10.3390/nano11051141 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1141

Author(s):

Georgia Basina ◽

Hafsa Khurshid ◽

Nikolaos Tzitzios ◽

George Hadjipanayis ◽

Vasileios Tzitzios

Keyword(s):

Room Temperature ◽

Colloidal Particles ◽

Iron Pentacarbonyl ◽

Vibrating Sample Magnetometer ◽

X Ray Diffraction ◽

Organometallic Synthesis ◽

X Ray ◽

Transmission Electron ◽

Hot Injection ◽

The Stability

Fe-based colloids with a core/shell structure consisting of metallic iron and iron oxide were synthesized by a facile hot injection reaction of iron pentacarbonyl in a multi-surfactant mixture. The size of the colloidal particles was affected by the reaction temperature and the results demonstrated that their stability against complete oxidation related to their size. The crystal structure and the morphology were identified by powder X-ray diffraction and transmission electron microscopy, while the magnetic properties were studied at room temperature with a vibrating sample magnetometer. The injection temperature plays a very crucial role and higher temperatures enhance the stability and the resistance against oxidation. For the case of injection at 315 °C, the nanoparticles had around a 10 nm mean diameter and revealed 132 emu/g. Remarkably, a stable dispersion was created due to the colloids’ surface functionalization in a nonpolar solvent.

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Stability of a Binary Colloidal Suspension and its effect on Colloidal Processing

MRS Proceedings ◽

10.1557/proc-155-73 ◽

1989 ◽

Vol 155 ◽

Author(s):

Wan V. Shih ◽

Wei-Heng Shih ◽

Jun Liu ◽

Ilhan A. Aksay

Keyword(s):

Particle Size ◽

Hard Sphere ◽

Colloidal Particles ◽

Colloidal Suspension ◽

Fluid Phase ◽

Ceramic Processing ◽

Colloidal Processing ◽

Interparticle Interactions ◽

The Stability ◽

Binary Suspension

The stability of a colloidal suspension plays an important role in colloidal processing of materials. The stability of the colloidal fluid phase is especially vital in achieving high green densities. By colloidal fluid phase, we refer to a phase in which colloidal particles are well separated and free to move about by Brownian motion, By controlling parameters such as pH, salt concentration, and surfactants, one can achieve high packing (green) densities in the repulsive regime where the suspension is well dispersed as a colloidal fluid, and low green densities in the attractive regime where the suspensions are flocculated [1,2]. While there is increasing interest in using bimodal suspensions to improve green densities, neither the stability of a binary suspension as a colloidal fluid nor the stability effects on the green densities have been studied in depth as yet. Traditionally, the effect of using bimodal-particle-size distribution has only been considered in terms of geometrical packing developed by Furnas and others [3,4]. This model is a simple packing concept and is used and useful for hard sphere-like repulsive interparticle interactions. With the advances in powder technology, smaller and smaller particles are available for ceramic processing. Thus, the traditional consideration of geometrial packing for the green densities of bimodal suspensions may not be enough. The interaction between particles must be taken into account.

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Dynamic Instability in Quartering Seas—Part III: Nonlinear Effects on Periodic Motions

Journal of Ship Research ◽

10.5957/jsr.1997.41.3.210 ◽

1997 ◽

Vol 41 (03) ◽

pp. 210-223 ◽

Cited By ~ 1

Author(s):

K. J. Spyrou

Keyword(s):

Periodic Motion ◽

Horizontal Plane ◽

Dynamic Instability ◽

Parametric Instability ◽

Nonlinear Effects ◽

Ship Motions ◽

Nonlinear Phenomena ◽

Specific Sequence ◽

The Stability ◽

Two Stages

The loss of stability of the horizontal-plane periodic motion of a steered ship in waves is investigated. In earlier reports we referred to the possibility of a broaching mechanism that will be intrinsic to the periodic mode, whereby there will exist no need for the ship to go through the surf-riding stage. However, about this point the discussion was essentially conjectural. In order to provide substance we present here a theoretical approach that is organized in two stages: Initially, we demonstrate the existence of a mechanism of parametric instability of yaw on the basis of a rudimentary, single-degree model of maneuvering motion in waves. Then, with a more elaborate model, we identify the underlying nonlinear phenomena that govern the large-amplitude horizontal ship motions, considering the ship as a multi-degree, nonlinear oscillator. Our analysis brings to light a very specific sequence of phenomena leading to cumulative broaching that involves a change in the stability of the ordinary periodic motion on the horizontal plane, a transition towards subharmonic response and, ultimately, a sudden jump to resonance. Possible means for controlling the onset of such undesirable behavior are also investigated.

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APPLICATION OF LEARNING REINFORCEMENT METHOD IN ROBOTIZED AND AUTOMATED FORESTRY SYSTEMS

Forestry Engineering Journal ◽

10.34220/issn.2222-7962/2020.1/19 ◽

2020 ◽

Vol 10 (1) ◽

pp. 256-265

Author(s):

Andrey Tolstyh ◽

D Stupnikov ◽

Sergey Malyukov ◽

Aleksandr Luk'yanov ◽

Yuriy Lunev

Keyword(s):

Physical Environment ◽

Learning Algorithm ◽

Back Propagation ◽

Industrial Robots ◽

Environment Model ◽

Random Position ◽

Learning Reinforcement ◽

The Stability ◽

Two Stages ◽

The Cost

Abstract Currently, most large enterprises are actively using industrial robots and other automated solutions. This allows a significant increase in productivity and quality of work performed. This article gave a brief overview of modern industrial robots, their operating principle, basic components and systems. A reinforcement learning algorithm was developed and tested. The task of constructing a learning algorithm with reinforcement was divided into two stages: modeling the environment and description and optimization of the cost function. Since industrial robotic systems operate in the real world, the environment model should reflect basic physical laws. Therefore, the pyBullet library of the physical environment was chosen as the physical environment for testing. After modeling the manipulator in the selected physical medium, it was given the trivial task of touching a given object with the capture of the manipulator. An artificial neural network was used as an agent interacting with the environment. The inputs were the coordinates of the object and the existing angles of rotation of the articulated joints of the robot. Outputs - angle of rotation of joints at this step. This network was trained using the back propagation method, Adam modification. The system was trained for about 12 hours. Success is achieved in 95% of cases when testing the stability of the system (random position of the cylinder). In future, it is planned to test the obtained models on bench samples

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The chemical stability of mendipite, diaboleïte, chloroxiphite, and cumengéite, and their relationships to other secondary lead(II) minerals

Mineralogical Magazine ◽

10.1180/minmag.1980.043.331.13 ◽

1980 ◽

Vol 43 (331) ◽

pp. 901-904 ◽

Cited By ~ 15

Author(s):

D. Alun Humphreys ◽

John H. Thomas ◽

Peter A. Williams ◽

Robert F. Symes

Keyword(s):

Chloride Ion ◽

Stability Diagram ◽

Chloride Ions ◽

Ion Concentration ◽

Stability Field ◽

Cupric Ion ◽

Free Energy Of Formation ◽

High Concentrations ◽

The Stability ◽

Ph Range

SummaryThe chemical stabilities of mendipite, Pb3O2Cl2, diaboleïte, Pb2CuCl2(OH)4, chloroxiphite, Pb3CuCl2O2(OH)2, and cumengéite, Pb19Cu24Cl42 (OH)44, have been determined in aqueous solution at 298.2 K. Values of standard Gibbs free energy of formation, ΔGf°, for the four minerals are −740, −1160, −1129, and −15163±20 kJ mol−1 respectively. These values have been used to construct the stability diagram shown in fig. I which illustrates their relationships to each other and to the minerals cotunnite, PbCl2, paralaurionite, PbOHCl, and litharge, PbO. This diagram shows that mendipite occupies a large stability field and should readily form from cold, aqueous, mineralizing solutions containing variable amounts of lead and chloride ions, and over a broad pH range. The formation of paralaurionite and of cotunnite requires a considerable increase in chloride ion concentration, although paralaurionite can crystallize under much less extreme conditions than cotunnite. The encroachment of the copper minerals on to the stability fields of those mineral phases containing lead(II) only is significant even at very low relative activities of cupric ion. Chloroxiphite has a large stability field, and at given concentrations of cupric ion, diaboleïte is stable at relatively high aCl−. Cumengéite will only form at high concentrations of chloride ion.

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Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly(N-Isopropylacrylamide) and Poly(Acrylic Acid)

Polymers ◽

10.3390/polym12112638 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2638

Author(s):

Elena Buratti ◽

Ilaria Sanzari ◽

Franco Dinelli ◽

Themistoklis Prodromakis ◽

Monica Bertoldo

Keyword(s):

Acrylic Acid ◽

Colloidal Particles ◽

Polymer Network ◽

Spin Speed ◽

Glass Substrates ◽

Smooth Film ◽

The Difference ◽

The Stability ◽

Individual Particles ◽

Poly Acrylic Acid

In this work, soft microgels of Poly(N-Isopropylacrylamide) (PNIPAm) at two different sizes and of interpenetrated polymer network (IPN) composed of PNIPAm and Poly(Acrylic Acid) (PAAc) were synthesized. Then, solutions of these different types of microgels have been spin-coated on glass substrates with different degrees of hydrophobicity. PNIPAm particles with a larger diameter form either patches or a continuous layer, where individual particles are still distinct, depending on the dispersion concentration and spin speed. On the other, PNIPAm particles with a smaller diameter and IPN particles form a continuous and smooth film, with a thickness depending on the dispersion concentration and spin-speed. The difference in morphology observed can be explained if one considers that the microgels may behave as colloidal particles or macromolecules, depending on their size and composition. Additionally, the microgel size and composition can also affect the stability of the depositions when rinsed in water. In particular, we find that the smooth and continuous films show a stimuli-dependent stability on parameters such as temperature and pH, while large particle layers are stable under any condition except on hydrophilic glass by washing at 50 °C.

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Phosphorus Removal from Manure by Mechanical Separation using Salt and Polymers: Theoretical Simulations and Experimental Data

Applied Engineering in Agriculture ◽

10.13031/aea.13726 ◽

2020 ◽

Vol 36 (2) ◽

pp. 175-185

Author(s):

Morten Lykkegaard Christensen ◽

Kristian Keiding ◽

Peter Vittrup Christensen

Keyword(s):

Calcium Phosphate ◽

Chemical Equilibrium ◽

Phosphorus Removal ◽

Solid Material ◽

Ion Concentration ◽

Iron Sulfate ◽

Molar Ratio ◽

Pig Manure ◽

Polymer Addition ◽

The Stability

Abstract.Full-scale separation apparatuses were used to process mink and sow manure. Mink manure was pretreated with iron sulfate and polymer; pig manure was pretreated with only polymer. Testing was done to study how adding chemicals affected phosphorus removal. Chemical equilibrium simulations show that raw manure contains several minerals, i.e., struvite, calcium phosphate, and vivianite. The estimated mass of struvite fit well with the amount of magnesium measured in the solid material. The amount of calcium phosphate precipitation depended on the stability constant of the complexes of organic material and calcium ions, estimated at pK = 3.5–4. With polymer addition, it was possible to remove mineral-bound phosphorus but not organic-bound phosphorus and orthophosphate. With iron salt addition, it was possible to remove both phosphorus minerals and dissolved orthophosphate. The molar ratio between orthophosphate and iron ions in the precipitate was measured to be 2:3. These data fit well with the chemical equilibrium simulations, which predicted that vivianite would form when the iron ion concentration increased. The simulation also indicated that the amount of struvite decreased slightly with iron addition. Keywords: Coagulation, Flocculation, Solid-liquid separation, Vivianite, Wastewater.

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Impact of structural defects and hydronium ion concentration on the stability of zeolite BEA in aqueous phase

Applied Catalysis B Environmental ◽

10.1016/j.apcatb.2018.06.065 ◽

2018 ◽

Vol 237 ◽

pp. 996-1002 ◽

Cited By ~ 15

Author(s):

Sebastian Prodinger ◽

Hui Shi ◽

Huamin Wang ◽

Miroslaw A. Derewinski ◽

Johannes A. Lercher

Keyword(s):

Aqueous Phase ◽

Ion Concentration ◽

Structural Defects ◽

Hydronium Ion ◽

The Stability

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Membrane potential and ion concentration stability conditions for a cell with a restricted extracellular space

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1979.0098 ◽

1979 ◽

Vol 206 (1163) ◽

pp. 145-161 ◽

Cited By ~ 11

Keyword(s):

Membrane Potential ◽

Extracellular Space ◽

Ionic Current ◽

Extracellular Fluid ◽

Ion Concentration ◽

Resting Potential ◽

Purkinje Fibres ◽

Zero Current ◽

Membrane Changes ◽

The Stability

For an isolated membrane, the resting (zero current) potential is stable if the slope conductance is positive, and is unstable if the slope conductance is negative. Recent work suggests that the properties of many preparations are influenced by the presence of an extracellular space that is not in good diffusive contact with the bulk extracellular fluid. Ionic current flow across the membrane changes the ion concentrations in this space. These concentration changes affect the stability of the membrane potential. Even if the slope conductance is negative, the presence of the extracellular space can confer stability on the resting potential. Conversely, even if the slope conductance is positive, the extracellular space can produce instability of the resting potential. Evaluation of the relevant parameters for cardiac Purkinje fibres, from published experimental data, suggests that concentration changes in the extracellular space may play a significant role in determining when an action potential is initiated.

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Design and Operation of a Modern Polish Plant for Plastic Waste Recycling through the Degradative Depolymerization Process. A Case Study

Energies ◽

10.3390/en13246620 ◽

2020 ◽

Vol 13 (24) ◽

pp. 6620 ◽

Cited By ~ 1

Author(s):

Andrzej Duda ◽

Arkadiusz Fenicki ◽

Patryk Molski ◽

Elżbieta Szostak ◽

Piotr Duda

Keyword(s):

Negative Pressure ◽

Waste Recycling ◽

Considerable Reduction ◽

Industrial Scale ◽

Process Safety ◽

Innovative Solutions ◽

Plastic Waste Recycling ◽

High Level ◽

Two Stages

The paper describes an installation for the degradative depolymerization of polyolefin materials obtained from wastes, hereinafter also referred to as depolymerization for simplicity. The plant, on an industrial scale, is one of the few operating in Poland. However, it is one of the most modern plants in this industry. Design solutions, construction of particular technological lines, compliance with national and EU regulations and the high level of process safety were described in this paper as well as compared to other plants of this type in Poland. Different solutions were presented in drawings and photos of the plant and in fragmentary technological diagrams. The types of waste and the methods of their processing by the plant were also characterized in accordance with the applicable regulations. The waste throughput is from 2000 to 4000 kg/h, while the efficiency of the depolymerization installation itself is 1500 kg/h. The industrial-scale depolymerization process is carried out in one or two stages: by homogenization (extraction) at a temperature up to 200 °C and depolymerization at temperatures up to 400 °C. The obtained products (energy goods) are sold for further processing. The processes, devices and methods are characterized by novel, innovative solutions, covered by a number of patents, which are also described below. The advantage of the presented technology is the substantial simplification of the process and thereby a considerable reduction in investment costs. Among others, the processes of distillation and rectification (low- and negative-pressure) were abandoned.

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