Colloid Chemical Properties of Ce0.5Zr0.5O2 Hydrosols and the Nature of Their Aggregative Stability

2020 ◽  
Vol 82 (4) ◽  
pp. 362-368
Author(s):  
N. N. Gavrilova ◽  
I. V. Ivanov ◽  
V. V. Nazarov
Keyword(s):  
Chemical Properties ◽  
Aggregative Stability

scholarly journals Aggregation stability of nanoparticles based on rare-earth elements in different microenvironment and biological media

2018 ◽  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Chemical Properties ◽  
Modern Medicine ◽  
Tris Buffer ◽  
Aggregative Stability ◽  
Hydrodynamic Diameter ◽  
Solution Ph ◽  
Aggregation Stability ◽  
Physiological Values

Background: Development of new pharmacological forms able to increase the therapeutic effectiveness of already known drugs, to reduce side effects, and to increase the comfort of treatment for the patient is an actual task of modern medicine and pharmacy. To solve the problem, one of the most promising directions in this field is the use of various nanomaterials, among which in recent years the main attention was drawn to nanomaterials based on rare earth elements (REEs). At the same time, the question of the relation between the biological activity of nanomaterials and their physical and chemical properties, as well as the features of interaction with microenvironments in biosystems, remain controversial. Objectives: Estimation of the aggregation stability of REE-based nanoparticles (NPs) in incubation media of different compositions and of the role of certain factors in stabilizing NPs in the biological microenvironment. Materials and methods: Aggregation stability of GdYVO4:Eu3+, LaVO4: Eu3+, CeO2, GdVO4:Eu3+ NPs was studied using dynamic and electrophoretic light scattering techniques. NPs were incubated in 5% glucose or buffers: 50 mM Tris buffer (with different pH within of physiological values); Igla МЕМ medium; Krebs-Ringer buffer pH 7.4; HBSS-buffer (HEPES-buffered saline-solution) pH 7.4, in the absence or presence of 0.2% BSA, for 30 minutes and 24 hours. The effect of oxidized and reduced glutathione on the stability of solutions of NPs in Tris buffer at various pH values was also determined. Results: The results have shown that in contrast to the stabilizing effect of 5% glucose solution significant aggregation of NPs is observed in saline systems. The highest degree of aggregation was observed in the Igla МЕМ and Krebs-Ringer buffer environment. Addition of 0.2% of albumin to all media prevented aggregation. Interaction of immunoglobulin with NPs leads to increase in hydrodynamic diameter, especially for some types of NPs, already at the smallest of the used protein concentrations. Oxidized but not recovered glutathione promoted aggregation of all types of orthovanadate NPs in acidic medium (Tris buffer pH=6.7). Conclusions: The aggregative stability of NPs in the salt media increases significantly in the presence of serum albumin due to changes in the ratio of the electrostatic and steric components of the interaction of NPs with the microenvironment.

scholarly journals COLLOID-CHEMICAL PROPERTIES OF SILICONE SURFACTANTS USED IN THE SYNTHESIS OF POLYSTYRENE LATEXES

2016 ◽  
Vol 11 (4) ◽  
pp. 56-62 ◽  
Author(s):  
I. A. Gritskova ◽  
A. A. Amelichev ◽  
O. A. Satskevich ◽  
A. V. Shkolnikov ◽  
A. A. Ezhova ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Modern Science ◽  
Chemical Properties ◽  
Polymerization Process ◽  
Narrow Particle Size Distribution ◽  
Aggregative Stability ◽  
Polymeric Microspheres ◽  
Silicone Surfactants

The synthesis of polymeric suspensions with a narrow particle size distribution is an urgent problem in modern science. The resulting polymeric microspheres are applicable in various fields of chemistry, pharmaceuticals, biology and medicine. In particular, they can be used as carriers of bioligands to create diagnostic test systems. This article presents the results of a study on the colloid-chemical characteristics of water-insoluble fluorinated silicone surfactants and kinetics of the polymerization process in their presence. The results were compared with data from studies on the properties of surfactants of similar structure not containing fluorine atoms in their structure. Studying these substances’ rheology enabled to determine the most suitable surfactants for adsorption forming a strong interfacial layer during the formation of polymermonomer particles during the polymerisation. The ability of fluorinated silicone surfactants to form a stable polymeric slurry was proved during heterophase polymerization of vinyl monomers. The resulting polymeric suspensions were characterized by a narrow particle size distribution and high aggregative stability during the synthesis and in storage.

scholarly journals Colloidal Characteristics of Molybdenum Blue Nanoparticles Dispersion for Catalytic Applications

2020 ◽  
Vol 4 (1) ◽  
pp. 24
Author(s):  
Natalia Gavrilova ◽  
Maria Myachina ◽  
Ksenia Poluboyarinova ◽  
Ekaterina Novaeva ◽  
Victor Nazarov
Keyword(s):  
Supported Catalysts ◽  
Sol Gel ◽  
Chemical Properties ◽  
Aggregate Stability ◽  
Surface Characteristics ◽  
Aggregative Stability ◽  
Dispersed Phase ◽  
High Concentration ◽  
Molybdenum Blue ◽  
Wide Range

The nanosized clusters of molybdenum blues and their monodispersity make them possible to consider as promising precursors for molybdenum carbide preparation. For the synthesis of supported catalysts using sols (dispersions of nanoparticles), it is necessary to know their main colloidal-chemical properties (electro-surface characteristics, rheological properties and the conditions of aggregative stability). This paper presents the results of a study of the colloidal-chemical properties of molybdenum blue, the dispersed phase of which is represented by toroidal particles of the Mo154-x family. It was found that aggregate stable sols exist in the range of 0.8 ˂ pH ˂ 2.0. In this range, molybdenum blue particles are negatively charged, and the electrokinetic potential does not exceed 30 mV. Molybdenum blues have high aggregate stability and can be concentrated to a high concentration of the dispersed phase (20–30 wt%); at a concentration more than 30 wt.%, a transition of the sol into a gel is observed. In a wide range of concentrations, molybdenum blues are Newtonian liquids, and the viscosity mainly depends on the concentration of the dispersed phase. The results obtained can be used as a basis for the development of a sol–gel method of supported catalysts based on molybdenum blue.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Biophysical Measurement of Molecular Weight of Foot-and-Mouth Disease RNA Fragments

1974 ◽  
Vol 32 ◽  
pp. 262-263
Author(s):  
Sydney S. Breese ◽  
Howard L. Bachrach
Keyword(s):  
Chemical Properties ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Distilled Water ◽  
Bovine Plasma ◽  
Mouth Disease Virus ◽  
Foot And Mouth ◽  
Carbon Coated ◽  
Rna Fragments ◽  
Physical And Chemical

Continuing studies on the physical and chemical properties of foot-and-mouth disease virus (FMDV) have included electron microscopy of RNA strands released when highly purified virus (1) was dialyzed against demlneralized distilled water. The RNA strands were dried on formvar-carbon coated electron microscope screens pretreated with 0.1% bovine plasma albumin in distilled water. At this low salt concentration the RNA strands were extended and were stained with 1% phosphotungstic acid. Random dispersions of strands were recorded on electron micrographs, enlarged to 30,000 or 40,000 X and the lengths measured with a map-measuring wheel. Figure 1 is a typical micrograph and Fig. 2 shows the distributions of strand lengths for the three major types of FMDV (A119 of 6/9/72; C3-Rezende of 1/5/73; and O1-Brugge of 8/24/73.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Cathodoluminescence of Catalyst Crystallites

1982 ◽  
Vol 40 ◽  
pp. 664-665
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
D.B. Darby ◽  
C. Warwick
Keyword(s):  
Defect Density ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Semiconductor Materials ◽  
Environmental Cell ◽  
High Resolution Structure ◽  
Commercially Important ◽  
Crystallographic Defects ◽  
Resolution Structure

The extended crystallographic defects introduced into some oxide catalysts under operating conditions may be a consequence and accommodation of the changes produced by the catalytic activity, rather than always being the origin of the reactivity. Operation without such defects has been established for the commercially important tellurium molybdate system. in addition it is clear that the point defect density and the electronic structure can both have a significant influence on the chemical properties and hence on the effectiveness (activity and selectivity) of the material as a catalyst. SEM/probe techniques more commonly applied to semiconductor materials, have been investigated to supplement the information obtained from in-situ environmental cell HVEM, ultra-high resolution structure imaging and more conventional AEM and EPMA chemical microanalysis.

Defects in Crystals

1968 ◽  
Vol 26 ◽  
pp. 244-245
Author(s):  
Kenneth R. Lawless
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Surface Defects ◽  
Chemical Properties ◽  
Material Point ◽  
Crystal Defects ◽  
Defects In Crystals ◽  
Irradiation Effects ◽  
Normal Lattice ◽  
Line Defects

One of the most important applications of the electron microscope in recent years has been to the observation of defects in crystals. Replica techniques have been widely utilized for many years for the observation of surface defects, but more recently the most striking use of the electron microscope has been for the direct observation of internal defects in crystals, utilizing the transmission of electrons through thin samples.Defects in crystals may be classified basically as point defects, line defects, and planar defects, all of which play an important role in determining the physical or chemical properties of a material. Point defects are of two types, either vacancies where individual atoms are missing from lattice sites, or interstitials where an atom is situated in between normal lattice sites. The so-called point defects most commonly observed are actually aggregates of either vacancies or interstitials. Details of crystal defects of this type are considered in the special session on “Irradiation Effects in Materials” and will not be considered in detail in this session.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

The microstructure of a TiB2/Ti-47 Al composite material

1989 ◽  
Vol 47 ◽  
pp. 674-675
Author(s):  
O. Popoola ◽  
A.H. Heuer ◽  
P. Pirouz
Keyword(s):  
Composite Material ◽  
Ion Beam ◽  
Chemical Properties ◽  
Intermetallic Alloys ◽  
Transmission Electron ◽  
Diamond Polishing ◽  
Al Composite ◽  
The Matrix ◽  
Argon Ion ◽  
And Chemical Properties

The addition of fibres or particles (TiB2, SiC etc.) into TiAl intermetallic alloys could increase their toughness without compromising their good high temperature mechanical and chemical properties. This paper briefly discribes the microstructure developed by a TiAl/TiB2 composite material fabricated with the XD™ process and forged at 960°C.The specimens for transmission electron microscopy (TEM) were prepared in the usual way (i.e. diamond polishing and argon ion beam thinning) and examined on a JEOL 4000EX for microstucture and on a Philips 400T equipped with a SiLi detector for microanalyses.The matrix was predominantly γ (TiAl with L10 structure) and α2(TisAl with DO 19 structure) phases with various morphologies shown in figure 1.

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