scholarly journals Preparation of TiO2 Nanoparticle Aggregates and Capsules by the ‘Two-Emulsion Method’

2020 ◽  
Vol 4 (4) ◽  
pp. 57
Author(s):  
Nadya I. Politova-Brinkova ◽  
Sonya R. Tsibranska-Gyoreva ◽  
Slavka S. Tcholakova ◽  
Nikolai D. Denkov ◽  
Thomas Danner
Keyword(s):  
Practical Interest ◽  
Tio2 Particle ◽  
Oil Viscosity ◽  
Emulsion Method ◽  
Tio2 Particles ◽  
Nanoparticle Aggregates ◽  
Water Drops ◽  
Great Practical Interest ◽  
Oil Emulsions ◽  
Micrometer Size

TiO2-based materials are of great practical interest in several technological areas. Both the size and the morphology of the TiO2 particles are of critical importance for their applications. The current study explores the effect of several factors on the outcome of the TiO2 particle synthesis via the so-called ‘two-emulsion method’. In this technique, two water-in-oil emulsions—each of them containing different reactant in the dispersed water drops—are mixed under well controlled conditions. Upon such mixing, partial coalescence of the water drops from the two emulsions leads to mixing of the drop content, with chemical reaction occurring within the drops, and to synthesis of Ti(OH)4 particles. Afterwards, the latter are transformed by emulsion heating into TiO2 particles and aggregates of predominantly anatase structure. Our results show that—depending on the precursor and surfactant concentrations, oil viscosity, emulsification time, and mixing speed—the obtained nanoparticles could aggregate either on the drop surface, forming capsules with a very smooth surface, or inside the water droplets, thus leading to hierarchically structured aggregates of micrometer size. The spherical smooth capsules are constructed of very small monodisperse TiO2 nanoparticles with size below 5 nm. The hierarchical bulk aggregates, on the other hand, are formed from bigger primary particles of sub-micrometer size. The obtained results show that one can obtain various TiO2 structures by controlling the conditions during the emulsion preparation and mixing

A MODEL HIERARCHY FOR IONOSPHERIC PLASMA MODELING

2004 ◽  
Vol 14 (03) ◽  
pp. 393-415 ◽  
Author(s):  
CHRISTOPHE BESSE ◽  
PIERRE DEGOND ◽  
FABRICE DELUZET ◽  
JEAN CLAUDEL ◽  
GÉRARD GALLICE ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Density ◽  
Maxwell Equations ◽  
Ionospheric Plasma ◽  
Practical Interest ◽  
Plasma Modeling ◽  
Model Hierarchy ◽  
Great Practical Interest ◽  
Two Fluid ◽  
Insight Into

This paper deals with the modeling of the ionospheric plasma. Starting from the two-fluid Euler–Maxwell equations, we present two hierarchies of models. The MHD hierarchy deals with large plasma density situations while the dynamo hierarchy is adapted to lower density situations. Most of the models encompassed by the dynamo hierarchy are classical ones, but we shall give a unified presentation of them which brings a new insight into their interrelations. By contrast, the MHD hierarchy involves a new (at least to the authors) model, the massless-MHD model. This is a diffusion system for the density and magnetic field which could be of great practical interest. Both hierarchies terminate with the "classical" Striation model, which we shall investigate in detail.

scholarly journals Sticky Thermals: Evidence for a Dominant Balance between Buoyancy and Drag in Cloud Updrafts

2015 ◽  
Vol 72 (8) ◽  
pp. 2890-2901 ◽  
Author(s):  
David M. Romps ◽  
Alexander B. Charn
Keyword(s):  
Large Eddy Simulation ◽  
Practical Interest ◽  
Momentum Equation ◽  
Severe Weather ◽  
Convective Clouds ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Great Practical Interest ◽  
Natural Boundaries ◽  
Drag Law

Abstract The vertical velocities of convective clouds are of great practical interest because of their influence on many phenomena, including severe weather and stratospheric moistening. However, the magnitudes of forces giving rise to these vertical velocities are poorly understood, and the dominant balance is in dispute. Here, an algorithm is used to extract thousands of cloud thermals from a large-eddy simulation of deep and tropical maritime convection. Using a streamfunction to define natural boundaries for these thermals, the dominant balance in the vertical momentum equation is revealed. Cloud thermals rise with a nearly constant speed determined by their buoyancy and the standard drag law with a drag coefficient of 0.6. Contrary to suggestions that cloud thermals might be slippery, with a dominant balance between buoyancy and acceleration, cloud thermals are found here to be sticky, with a dominant balance between buoyancy and drag.

About injuries with a chemical (ink) pencil

1930 ◽  
Vol 26 (8) ◽  
pp. 841-843
Author(s):  
S. I. Rizvash
Keyword(s):  
Human Tissue ◽  
Practical Interest ◽  
Russian Literature ◽  
Medical Institutions ◽  
Great Practical Interest ◽  
Treatment Of Wounds ◽  
Type Of Injury

In Russian literature, very little attention has been paid to this type of injury. I managed to find only 2 articles in which this issue is treated. In the manuals on general and private surgery, both translated and original, there is no indication of the action of aniline pencils on human tissue. Nothing is said about this even in the largest Russian monographs on the treatment of wounds (Trinkler, Petrov). Meanwhile, the injuries caused by a chemical pencil, due to their peculiar course and often even a difficult outcome, are undoubtedly of great practical interest. This prompts me to report two cases of such an injury, which I observed in different medical institutions at almost the same time.

Evaluation of bond strength of cross-laminated LSL specimens under short-span bending

Holzforschung ◽  
2019 ◽  
Vol 73 (8) ◽  
pp. 789-795
Author(s):  
Meng Gong ◽  
Ling Li ◽  
Ying-Hei Chui
Keyword(s):  
Bond Strength ◽  
Test Procedure ◽  
Practical Interest ◽  
Adhesive Bond ◽  
Bond Quality ◽  
Block Shear ◽  
The Face ◽  
Great Practical Interest ◽  
Short Span ◽  
Mass Timber

AbstractMass timber panels (MTPs) have a great potential in the construction of mid- and high-rise buildings. Evaluation of the face-bond strength of MTPs is of great practical interest for this kind of products. This study aimed at developing an appropriate test procedure for evaluating the adhesive bond strength of cross-laminated laminated strand lumber (CL-LSL). Three-point short-span bending tests were conducted on two-layer asymmetric CL-LSL specimens (2LasymCL-LSL), which were adhesively bonded by two-component resins of the type polyurethane (PUR) or polyvinyl acetate (PVAc). For comparison, block shear specimens were tested as well. It was found that the 2LasymCL-LSL assembly was better suitable under the short-span bending for differentiating between good and poor bond quality of MTPs.

scholarly journals Influence of Oil Viscosity on Alkaline Flooding for Enhanced Heavy Oil Recovery

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Yong Du ◽  
Guicai Zhang ◽  
Jijiang Ge ◽  
Guanghui Li ◽  
Anzhou Feng
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
High Viscosity ◽  
Low Permeability ◽  
Oil Viscosity ◽  
Low Viscosity ◽  
Medium Permeability ◽  
Tertiary Oil Recovery ◽  
Different Temperatures ◽  
Water Drops

Oil viscosity was studied as an important factor for alkaline flooding based on the mechanism of “water drops” flow. Alkaline flooding for two oil samples with different viscosities but similar acid numbers was compared. Besides, series flooding tests for the same oil sample were conducted at different temperatures and permeabilities. The results of flooding tests indicated that a high tertiary oil recovery could be achieved only in the low-permeability (approximately 500 mD) sandpacks for the low-viscosity heavy oil (Zhuangxi, 390 mPa·s); however, the high-viscosity heavy oil (Chenzhuang, 3450 mPa·s) performed well in both the low- and medium-permeability (approximately 1000 mD) sandpacks. In addition, the results of flooding tests for the same oil at different temperatures also indicated that the oil viscosity put a similar effect on alkaline flooding. Therefore, oil with a high-viscosity is favorable for alkaline flooding. The microscopic flooding test indicated that the water drops produced during alkaline flooding for oils with different viscosities differed significantly in their sizes, which might influence the flow behaviors and therefore the sweep efficiencies of alkaline fluids. This study provides an evidence for the feasibility of the development of high-viscosity heavy oil using alkaline flooding.

What Causes the Formation of Water-in-Oil Emulsions?

2001 ◽  
Vol 2001 (1) ◽  
pp. 109-114 ◽  
Author(s):  
Mervin F. Fingas ◽  
Ben Fieldhouse ◽  
James Lane ◽  
Joseph V. Mullin
Keyword(s):  
Chemical Composition ◽  
Shear Rate ◽  
Resin Content ◽  
Stable Emulsion ◽  
Oil Viscosity ◽  
The Past ◽  
Asphaltene Content ◽  
Oil Emulsions ◽  
The Stability ◽  
Unstable Emulsion

ABSTRACT The results of studies conducted over the past 6 years to characterize why water-in-oil emulsions form are summarized. It is shown that water droplets are held in oil by a combination of viscous and interfacial forces. The stability of an emulsion is very important in understanding its formation because stability is the endpoint or measurement of the entire process. Emulsions can be grouped into three categories: stable, unstable, and mesostable. Each has distinct physical properties. For example, the viscosity of a stable emulsion at a shear rate of I reciprocal second is at least three orders-of-magnitude greater than that of the starting oil. An unstable emulsion usually has a viscosity no more than two orders-of-magnitude greater than that of the starting oil. The zero-shear-rate viscosity is at least six orders-of-magnitude greater than the starting oil for a stable emulsion. For an unstable emulsion, it is usually less than two or three orders-of-magnitude greater than the viscosity of the starting oil. and finally, a stable emulsion has a significant elasticity, whereas an unstable emulsion does not. The stability of emulsions has been studied by examining their asphaltene content and their resin content. Results are reported showing that asphaltenes and resins are responsible for stability. It is noted that, given the correct chemical composition, primarily asphaltenes, sea energy is needed. The properties of the starting oil are the important factor in determining what type of water-in-oil state is produced. Composition and property ranges are given for the starting oil to form each of the water-in-oil states. Important property factors are the asphaltene content, resin content, and starting oil viscosity.

On the practical results of implementation of coalessors in oil-gas preparation

2021 ◽  
pp. 39-42
Author(s):  
S.F. Musaev ◽  
Keyword(s):  
Gas Separation ◽  
Oil Flow ◽  
Water Drops ◽  
Liquid Type ◽  
Oil Emulsions ◽  
Multi Phase ◽  
Oil Gas ◽  
Gas Compressibility

The paper deals with the issues of the implementation of coalessors for the separation of multi-phase fluids into particular phases during oil preparation for transportation. Various coalessors of liquid/liquid type (for separation of oil emulsions) and liquid/gas (for gas separation) have been analyzed. The results of the coalessor implementation are presented, the maximum sizes of water drops washed with oil flow estimated, the necessity of the consideration of gas compressibility rate during the evaluation of the sedimentation of mechanical particles marked.

EXPERIMENTAL STUDY OF THE CONDITIONS OF SPRAYING LIQUIDS WITH THE AIR FLOW

2021 ◽  
pp. 32-37
Author(s):  
NATALYA G. KOZHEVNIKOVA ◽  
Keyword(s):  
Dynamic Pressure ◽  
Practical Interest ◽  
Effective Area ◽  
Measurement Point ◽  
Factors Affecting ◽  
Pests And Diseases ◽  
Advantages And Disadvantages ◽  
Dynamic Pressure Measurement ◽  
Additional Resistance ◽  
Great Practical Interest

The processes of air movement in various types of air ducts are of great practical interest in terms of designing, manufacturing, and installing spraying devices used in agricultural production to create artificial fog with fi ne sprinkling and treat crops from pests and diseases. The authors analyze the existing methods of liquid spraying and reveal their main advantages and disadvantages. Under special attention is the pneumatic method. The study found that this method is used to spray contaminated liquids and the spray quality insignificantly depends on the liquid flow rate. It was revealed that one of the main factors affecting the quality indicators of spraying devices is the dynamic pressure of the gas medium acting on the liquid during its spraying. The research has determined that the dynamic pressure value of the airflow during the liquid movement in a horizontal duct depends on three factors: the presence of additional resistance, estimated by the value of the effective area duct, the position of the point at which the pressure was measured relative to the duct axis and the distance between the measurement point and the airflow source. The experimental data were tested for reproducibility using the Cochran criterion at the 5% signifi cancelevel, which proved the process reproducibility. The research has shown that the presence of additional resistance in the duct and the position of the dynamic pressure measurement point relative to the axis of the duct have the same effect on its value. The dynamic pressure of the airflow is primarily dependent on the remoteness of the measurement point from its source.

The Effect of Double-Element Doping on the Photocatalytic Property of Nano-TiO2

2013 ◽  
Vol 669 ◽  
pp. 371-376
Author(s):  
Su Huang ◽  
Fu Yun Li ◽  
Yang Li ◽  
Li Zhen Yang
Keyword(s):  
Methyl Orange ◽  
Sol Gel ◽  
Photocatalytic Property ◽  
Tio2 Particle ◽  
Metallic Elements ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
Minimum Diameter ◽  
Tio2 Particles ◽  
Element Doping

Sol-gel method was applied to synthesize nano-TiO2 particles doped with metal and non-metallic elements. Nano-TiO2 particles were doped at different calcinations’ temperatures with S and Fe, Ce and La, respectively. A comparison was performed on the effect of different metallic elements on nano-TiO2 particles doped with the same non-metallic element S. X-ray diffraction results indicated that the diameter of doped nano-TiO2 particle was smaller than that of non-doped nano-TiO2 particles. The minimum diameter of nano-TiO2 doped with Ce and S was about 8nm, while that of nano-TiO2 doped with La and S was about 9nm. The minimum diameter of nano-TiO2 particles doped with Fe and S was about 10nm. In addition, with the increase of calcinations’ temperature, the size of nano-TiO2 particle increased. All nano-TiO2 particles doped with double elements were antae. Methyl orange was used to simulate the pollutant to analyze the photocatalytic property of doped nano-TiO2. The results indicated that the doped element had some effect on the photocatalytic property of nano-TiO2, and varied for different doped metallic elements. Among them, the degradation rate of methyl orange by nano-TiO2 doped with La and S under the calcinations’ temperature of 550 °C reached 28.97%.

scholarly journals Fixpoint semantics and optimization of recursive Datalog programs with aggregates

2017 ◽  
Vol 17 (5-6) ◽  
pp. 1048-1065 ◽  
Author(s):  
CARLO ZANIOLO ◽  
MOHAN YANG ◽  
ARIYAM DAS ◽  
ALEXANDER SHKAPSKY ◽  
TYSON CONDIE ◽  
...  
Keyword(s):  
Practical Interest ◽  
Optimization Techniques ◽  
Superior Performance ◽  
Horn Clauses ◽  
Set Containment ◽  
Implementation Approach ◽  
Recursive Programs ◽  
Great Practical Interest ◽  
Fixpoint Semantics ◽  
Vldb Journal

AbstractA very desirable Datalog extension investigated by many researchers in the last 30 years consists in allowing the use of the basic SQL aggregates min, max, count and sum in recursive rules. In this paper, we propose a simple comprehensive solution that extends the declarative least-fixpoint semantics of Horn Clauses, along with the optimization techniques used in the bottom-up implementation approach adopted by many Datalog systems. We start by identifying a large class of programs of great practical interest in which the use of min or max in recursive rules does not compromise the declarative fixpoint semantics of the programs using those rules. Then, we revisit the monotonic versions of count and sum aggregates proposed by Mazuran et al. (2013b, The VLDB Journal 22, 4, 471–493) and named, respectively, mcount and msum. Since mcount, and also msum on positive numbers, are monotonic in the lattice of set-containment, they preserve the fixpoint semantics of Horn Clauses. However, in many applications of practical interest, their use can lead to inefficiencies, that can be eliminated by combining them with max, whereby mcount and msum become the standard count and sum. Therefore, the semantics and optimization techniques of Datalog are extended to recursive programs with min, max, count and sum, making possible the advanced applications of superior performance and scalability demonstrated by BigDatalog (Shkapsky et al. 2016. In SIGMOD. ACM, 1135–1149) and Datalog-MC (Yang et al. 2017. The VLDB Journal 26, 2, 229–248).

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