scholarly journals Determination of nanoparticles concentration in solution based on Pickering emulsion destabilization analyses

2021 ◽  
Author(s):  
Mariola M. Błaszczyk ◽  
Łukasz Przybysz
Keyword(s):  
Large Scale ◽  
Emulsion Stability ◽  
Analytical Techniques ◽  
Pickering Emulsions ◽  
Nanoparticle Concentration ◽  
Characteristic Parameters ◽  
Specialized Equipment ◽  
Nanoparticles Concentration ◽  
Emulsion Concentration

AbstractThe dynamic development of nanotechnology research has contributed to the fact that various types of nanoparticles are increasingly used on a large scale both for medical and biological purposes, but above all in many industrial fields. Such a wide application of nanoparticles is often connected with the need to estimate their characteristic parameters, such as size, size distribution or concentration. Existing instruments are usually quite expensive and not always available. Therefore, other cheaper and simpler methods based on analytical techniques are sought. In this paper, we have proposed a method to estimate the concentration of nanoparticles in solutions based on destabilization analyses of Pickering emulsions produced with their use. The fact of mutual relationship between emulsion concentration, nanoparticle concentration and emulsion stability was used here. The study was carried out using silica nanoparticles. It was presented how to apply the method and what are its limitations. Moreover, an example of its application for the determination of nanoparticle concentration in an unknown sample, obtained after analysis of the permeability of membranes in diffusion chambers, has been presented. The method can become a useful alternative for the determination of nanoparticle concentration in solution in places where no specialized equipment is available.

Effect of Inter-Particle Van Der Waals Attraction on the Stability of Pickering Emulsions in Brine

2021 ◽  
Author(s):  
Daniel Hatchell ◽  
Wen Song ◽  
Hugh Daigle
Keyword(s):  
Emulsion Stability ◽  
Droplet Diameter ◽  
Van Der Waals ◽  
Particle Diameter ◽  
Solid Particles ◽  
Electrostatic Repulsion ◽  
Pickering Emulsions ◽  
Nanoparticle Concentration ◽  
Coated Nanoparticles ◽  
20 Nm

Abstract Pickering emulsions are stabilized by solid particles that occupy the fluid-fluid interface, physically preventing coalescence. Their stability in brine, where interparticle electrostatic repulsion is negligible and van der Waals (vdW) attraction dominates, makes them attractive for applications in porous media. Recent studies postulate that inter-droplet particle networks assemble in brine and aid Pickering emulsion stability to coalescence. This work experimentally assesses the effect of increasing interparticle vdW attraction on particle network strength and emulsion stability. We grafted 6 nm, 12 nm, and 20 nm silica nanoparticles with varying densities of polyethylene glycol (PEG) to prevent aggregation and dispersed them in either brine or deionized water (DI). We characterized the PEG-coated nanoparticles with thermogravimetric analysis and dynamic light scattering to determine PEG grafting density, diameter, and zeta potential. To generate oil-in-water emulsions, we sonicated dispersions of variable nanoparticle concentration and decane in equal volumes. We imaged the emulsions with microscopy and centrifuged them for 15 minutes at 5000 g of acceleration, using the volume of decane released after centrifugation as a measurement of emulsion coalescence to the applied force. Nanoparticle characterization confirmed successful grafting of PEG to the silica surface. We compared trends in emulsion stability as a function of salinity and particle diameter to changes in the relevant interparticle forces described by extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Analysis of microscopy images showed an increase in emulsion droplet diameter with decreasing nanoparticle concentration, salinity, and increasing nanoparticle diameter. Through centrifugation we observed that lower PEG grafting densities tended to produce more stable emulsions, suggesting that particles with high grafting densities and consequently high steric repulsion tended to repel and prevent formation of strong particle networks. Emulsions generated in DI coalesced more easily, indicating that electrostatic repulsion dominated relative to vdW attraction and that particle networks did not form. In brine, where electrostatic forces were screened out by counterions, the emulsions better resisted coalescence, consistent with the formation of a particle network. The strength of the network was inferred from the difference in emulsion stability to coalescence in DI and in brine. We measured a greater brine-DI stability difference of 3.7× for the larger 20 nm PEG-coated nanoparticles, compared with 3.3× and 2.2× for the 12 nm and 6 nm PEG-coated particles, respectively, further supporting the role of particle networks on emulsion stability.

Large-scale Motion of Solar Filaments

2000 ◽  
Vol 179 ◽  
pp. 205-208
Author(s):  
Pavel Ambrož ◽  
Alfred Schroll
Keyword(s):  
Magnetic Flux ◽  
Proper Motion ◽  
Time Scale ◽  
Large Scale ◽  
Accuracy Of Measurements ◽  
Solar Filaments ◽  
General Movement ◽  
Scale Motion ◽  
Velocity Scatter

AbstractPrecise measurements of heliographic position of solar filaments were used for determination of the proper motion of solar filaments on the time-scale of days. The filaments have a tendency to make a shaking or waving of the external structure and to make a general movement of whole filament body, coinciding with the transport of the magnetic flux in the photosphere. The velocity scatter of individual measured points is about one order higher than the accuracy of measurements.

Some applications of electron beam microanalysis techniques in VLSI process evaluation

1983 ◽  
Vol 41 ◽  
pp. 160-161
Author(s):  
Simon Thomas
Keyword(s):  
Integrated Circuits ◽  
Process Evaluation ◽  
Large Scale ◽  
Technology Development ◽  
Analytical Techniques ◽  
Successful Implementation ◽  
Analysis Of Failures ◽  
Characterization Of Materials ◽  
Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

Methods for the Quantification of Salivary Cortisol and of a-amylase in Biosensors and Portable Devices

2018 ◽  
Vol 68 (12) ◽  
pp. 2857-2859
Author(s):  
Cristina Mihaela Ghiciuc ◽  
Andreea Silvana Szalontay ◽  
Luminita Radulescu ◽  
Sebastian Cozma ◽  
Catalina Elena Lupusoru ◽  
...  
Keyword(s):  
Real Time ◽  
Medical Practice ◽  
Salivary Cortisol ◽  
Clinical Studies ◽  
Large Scale ◽  
Psychological Research ◽  
Portable Devices ◽  
Salivary Amylase ◽  
Specificity And Sensitivity

There is an increasing interest in the analysis of salivary biomarkers for medical practice. The objective of this article was to identify the specificity and sensitivity of quantification methods used in biosensors or portable devices for the determination of salivary cortisol and salivary a-amylase. There are no biosensors and portable devices for salivary amylase and cortisol that are used on a large scale in clinical studies. These devices would be useful in assessing more real-time psychological research in the future.

The Determination of the Noise Pollution in a Production Hall and the Diseases Produced by It

2018 ◽  
Vol 69 (4) ◽  
pp. 875-880
Author(s):  
Oana Roxana Chivu ◽  
Ovidiu Mederle ◽  
Augustin Semenescu ◽  
Ileana Mates ◽  
Claudiu Babis ◽  
...  
Keyword(s):  
Risk Factor ◽  
Human Body ◽  
Noise Level ◽  
Noise Pollution ◽  
Protective Measures ◽  
Work Program ◽  
Specialized Equipment ◽  
Chemical Products ◽  
Main Activity

The paper describes how to determine the noise in a production hall where there are production machines and equipment. The chosen plant is a production unit where filling of the polyurethane foam tubes is performed. The main activity is the production of professional insulators and wholesale of other products from the same range enumerating the following: wholesale chemical products; production of professional insulators; trade in chemicals and chemical industry. The recommended maximum admissible value for a normal 8h work program is 85 dB (A). The objective is to determine the level of noise in the factory and how it acts as a physical professional risk factor and its effects on the human body. The way in which the proposed objective was achieved was to determine the value of the noise level with the specialized equipment. Following the determinations that will be presented in the following chapters, appropriate protective measures have been taken.

Diagnostics of the location of damage to tubing oil well pipes

2019 ◽  
Vol 5 (4) ◽  
pp. 115-128
Author(s):  
Timur A. Ishmuratov ◽  
Rif G. Sultanov ◽  
Milyausha N. Khusnutdinova
Keyword(s):  
Fluid Motion ◽  
Oil Well ◽  
General Belief ◽  
Oil Flow ◽  
Specialized Equipment ◽  
Improving Accuracy ◽  
Analytical Expressions ◽  
Technical Measures ◽  
Quick Determination

The study is devoted to the mathematical description of the process of oil outflow in places of leakage of the tubing string, which allows a computer to locate a leakage in the tubing. The authors propose methodology for identifying defects in the tubing and determining the location of the leak. The uniqueness of this methodology lies in quick determination of the place of leakage without the use of specialists, sophisticated and specialized equipment. Mathematical modeling of oil flow in the tubing requires the apparatus of continuum mechanics. It is a general belief that the movement of oil in the pipe flows at low speeds due to its outflow from the hole. Using the general equations of mass and energy balance, the authors have obtained differential equations of fluid motion in a vertical pipe in the process of its outflow from the tubing and in the process of injection. Analytical expressions are the solution to these equations, as they can help in estimating the degree of damage and its location, as well as the feasibility of its eliminating. The results show that an increase in the leakage and injection times leads to improving accuracy of locating damage. Thus, when conducting various geological and technical measures (GTM) at the well, it is possible to assess the presence of leakage and its intensity when deciding on the repair of tubing.

Identification of N-Substituted Triazolo-azetidines as Novel Antibacterials using pDualrep2 HTS Platform

2019 ◽  
Vol 22 (5) ◽  
pp. 346-354
Author(s):  
Yan A. Ivanenkov ◽  
Renat S. Yamidanov ◽  
Ilya A. Osterman ◽  
Petr V. Sergiev ◽  
Vladimir A. Aladinskiy ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Large Scale ◽  
Underlying Mechanism ◽  
Luciferase Assay ◽  
Reporter System ◽  
E Coli ◽  
Starting Point ◽  
High Concentrations ◽  
Mic Value

Aim and Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity. Materials and Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out. Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position. Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.

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