Particle Erosion Measurements on Metals

1977 ◽  
Vol 99 (2) ◽  
pp. 121-125 ◽  
Author(s):  
J. P. Young ◽  
A. W. Ruff
Keyword(s):  
Particle Concentration ◽  
Erosive Wear ◽  
Test Results ◽  
Impingement Angle ◽  
Erosion Rates ◽  
Wide Range ◽  
Experimental Parameters ◽  
Different Temperatures ◽  
Nickel Base

A method being used to measure the erosive wear of metals at different temperatures and under controlled environmental conditions is described. A commercial apparatus has been modified that can be used for tests at 500°C and above and over a wide range of particle types, sizes, velocities, and concentrations. Test results from several iron and nickel base alloys are presented. Particular interest has been placed in the role of the oxide scale, in the particle velocity dependence and the impingement angle dependence of erosion rates, as well as the effect of varying particle concentration in the stream. Reproducibility among the tests of about 10 percent can be realized if care is exercised with regard to several important experimental parameters.

Climate Oscillations from Mountain Uplift and Erosion are Damped by Bioactivity

2021 ◽  
Author(s):  
Dennis Höning
Keyword(s):  
Plate Boundaries ◽  
Climate Oscillations ◽  
Biosphere 2 ◽  
Erosion Rates ◽  
Wide Range ◽  
1D Model ◽  
Uplift And Erosion ◽  
Steep Slopes

<p>Earth’s long-term carbonate-silicate cycle is continuously perturbed by processes of mountain building and erosion. Mountain uplift near convergent plate boundaries causes steep slopes, which in turn imply high rates of continental erosion. Erosion rates ultimately affect the weatherability and thereby the regulation of Earth’s climate. Using a simple 1D-model that includes the outlines processes, I investigate the resulting climate oscillations over timescales from thousands to millions of years. With a simple model of the long-term carbon cycle that includes biological enhancement of weathering and marine biogenic calcite precipitation, I study the role of Earth’s biosphere in damping these oscillations [1]. I show that both mechanisms play a role: Biological enhancement of weathering damps oscillations mainly on timescales > 1 Ma and marine calcification mainly on shorter timescales. Altogether, the results indicate that Earth’s biosphere contributes to a stable climate over a wide range of timescales.</p><p>In the context of anthropogenic emissions, a dramatic elevation in the atmospheric CO<sub>2</sub> and related temperature is known to damage Earth’s biosphere [2] and may even trigger runaway processes [3]. The results presented here indicate that a damaged biosphere may furthermore cause the Earth system to react more sensitive to oscillations from geological forcing and may also affect climate recovery.</p><p>References:</p><p>[1] Höning 2020, Geochem. Geophys. Geosyst. 21(9), e2020GC009105<br>[2] Sully et al. 2019, Nat. Comm. 10, 1264<br>[3] Lenton 2013, Annu. Rev. Environ. Resour. 38, 1-29</p>

Erosive Wear of Glass Fiber and B2O3 Reinforced Epoxy Composites

2011 ◽  
Vol 264-265 ◽  
pp. 1893-1898 ◽  
Author(s):  
Mehmet Bagci ◽  
Huseyin Imrek
Keyword(s):  
Glass Fiber ◽  
Silicon Oxide ◽  
Wear Behavior ◽  
Erosive Wear ◽  
Epoxy Composites ◽  
Fiber Direction ◽  
Particle Sizes ◽  
Test Results ◽  
Erosion Rates ◽  
Glass Fiber Reinforced

In this experimental study, erosive wear behavior of epoxy-resin dipped composite materials reinforced with glass fiber and B2O3 (borax) under different impact velocities, erodent sizes, and erodent striking angles along the fiber direction were investigated. The tests which involved slightly rounded and irregular silicon oxide (SiO2) particles having two different sizes of approximately 250 and 500 , were conducted at two different impact velocities of approximately 20 m/s and 40 m/s, two different fiber directions (0o and 45o) and six different impingement angles of 15o, 30o, 45o, 60o, 75o and 90o. In the test results, erosion rates were obtained as functions of impact velocities, striking angles, fiber direction and particle sizes. In addition, the microscopic views showing worn out surfaces of the glass fiber reinforced epoxy composites were scrutinized.

scholarly journals Maslinic Acid Nanoparticles: A Drug to Carry Others

2020 ◽  
Vol 4 (1) ◽  
pp. 6
Author(s):  
Pablo Graván ◽  
Aixa Aguilera-Garrido ◽  
Marta Medina-O’Donell ◽  
Andrés Parra ◽  
María J. Gálvez-Ruiz ◽  
...  
Keyword(s):  
Organic Phase ◽  
Volume Ratio ◽  
Maslinic Acid ◽  
Phase Volume Ratio ◽  
Starting Point ◽  
Wide Range ◽  
Experimental Parameters ◽  
Therapeutic Activities ◽  
Harmful Effects

Maslinic acid (MA), a triterpene widely found in natural sources, is a compound which is gaining interest due to its multiple therapeutic activities and its lack of harmful effects. However, MA is practically insoluble in water, which limits its clinical application. Here, we present a solvent displacement method to produce MA Solid Lipid Nanoparticles (SLNs) as a nanoplatform to carry hydrophobic drugs. A systematic study of the experimental parameters that may have some influence on the colloidal characteristics of MA SLNs was carried out. The effect of the aqueous/organic phase volume ratio and the organic phase composition on the size of SLNs evidence the role of the solvent diffusivity on the colloidal characteristic of the SLNs. On the other hand, the effect of surfactant/MA ratio proved the relevance of the surfactant on stabilizing the SLNs interface, owing to the changes on the interfacial tension that it promotes. MA SLNs have proved to be highly stable over time and in a wide range of pH and salinity conditions, as well as having a high curcumin encapsulation efficiency. The MA SLNs prepared in this work provide a starting point to develop functionalized active nanocarriers which allow establishing a synergistic relation with the loaded drug.

Adsorption and Incorporation of Cadmium into a Calcium Hydroxyapatite

2006 ◽  
Vol 45 ◽  
pp. 2055-2060 ◽  
Author(s):  
David Marchat ◽  
Didier Bernache-Assollant ◽  
Eric Champion ◽  
Eric Bêche ◽  
Gilles Flamant
Keyword(s):  
Solid Solution ◽  
Calcium Hydroxyapatite ◽  
Ionic Exchange ◽  
Batch Experiments ◽  
Surface Precipitation ◽  
Surface Areas ◽  
Wide Range ◽  
Experimental Parameters ◽  
Different Temperatures ◽  
Hydrated Complexes

The removal of cadmium from water by fixation into a calcium phosphate apatite Ca10(PO4)6(OH)2 (CaHA) was investigated in batch experiments. These ones were carried out using a wide range of initial Cd2+ concentration, three different temperatures, and several CaHA surface areas. The amount of immobilized cadmium was proportional to the surface area of CaHA, whatever the experimental parameters might be. It could reach 7.1 mol of Cd per mol of starting CaHA. Thermal and XPS analyses on the exchanged powders proved that a part of cadmium was quickly adsorbed at the grains surface in the form of hydrated complexes [Cd(OH2)n]2+. The latter were formed by an ionic exchange between adsorbed calcium and cadmium of the solution. Adsorption reaction was mainly limited by the number of specific sites available on the grains surface. Structural analyses showed that another part of Cd was slowly incorporated into a solid solution Ca10-xCdx(PO4)6(OH)2 (CaCdHA) onto the CaHA crystals surface. Results demonstrated unambiguously that the incorporation process was a surface precipitation and not an intracrystalline diffusion.

Solvothermal Synthesis of CdS Nanorods: Role of Basic Experimental Parameters

2007 ◽  
Vol 7 (2) ◽  
pp. 677-688 ◽  
Author(s):  
Anuja Datta ◽  
Soumitra Kar ◽  
Jay Ghatak ◽  
Subhadra Chaudhuri
Keyword(s):  
Synthesis Temperature ◽  
Molar Ratio ◽  
Sulfur Source ◽  
Solvothermal Process ◽  
Filling Fraction ◽  
Cds Nanorods ◽  
Wide Range ◽  
Experimental Parameters ◽  
Crystalline Nature

CdS nanorods with varying dimensions were synthesized by solvothermal process. It was observed that the anions present with the Cd-salts play an important role in determining the dimensions of the CdS nanorods. The crystalline nature of the sources was found to play a crucial role in determining the phase of the products. The nature of the sulfur source, molar ratio of the precursors, filling fraction of the solvent, and the synthesis temperature play important role in defining the size and shape of the products. By controlling the experimental parameters it was possible to control the dimension of the CdS nanorods within a certain range (diameter of the nanorods could be varied within a wide range from ∼7 to 100 nm by varying the temperature within 100–250 °C). Optical absorption, photoluminescence, and Raman studies of these samples were carried out to characterize the CdS nanorods.

scholarly journals Aircraft testing of the new Blunt-body Aerosol Sampler (BASE)

2014 ◽  
Vol 7 (9) ◽  
pp. 3085-3093 ◽  
Author(s):  
A. Moharreri ◽  
L. Craig ◽  
P. Dubey ◽  
D. C. Rogers ◽  
S. Dhaniyala
Keyword(s):  
Test Data ◽  
Blunt Body ◽  
Cloud Droplet ◽  
Separated Flows ◽  
Test Results ◽  
Winter Storms ◽  
Wide Range ◽  
Particle Contamination ◽  
Base Design

Abstract. There is limited understanding of the role of aerosols in the formation and modification of clouds, partly due to inadequate data on such systems. Aircraft-based aerosol measurements in the presence of cloud particles have proven to be challenging because of the problem of cloud droplet/ice particle shatter and the generation of secondary artifact particles that contaminate aerosol samples. Recently, the design of a new aircraft inlet, called the Blunt-body Aerosol Sampler (BASE), which enables sampling of interstitial aerosol particles, was introduced. Numerical modeling results and laboratory test data suggested that the BASE inlet should sample interstitial particles with minimal shatter particle contamination. Here, the sampling performance of the inlet is established from aircraft-based measurements. Initial aircraft test results obtained during the PLOWS (Profiling of Winter Storms) campaign indicated two problems with the original BASE design: separated flows around the BASE at high altitudes and a significant shatter problem when sampling in drizzle. The test data were used to improve the accuracy of flow and particle trajectory modeling around the inlet, and the results from the improved flow model were used to guide design modifications of the BASE to overcome the problems identified in its initial deployment. The performance of the modified BASE was tested during the ICE–T (Ice in Clouds Experiment – Tropics) campaign, and the inlet was seen to provide near shatter-free measurements in a wide range of cloud conditions. The initial aircraft test results, design modifications, and the performance characteristics of the BASE relative to another interstitial inlet, the submicron aerosol inlet (SMAI), are presented.

scholarly journals Exploring the Effects of Nanoparticle Incorporation on the Mechanical Properties of Hydrogels

Proceedings ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 2
Author(s):  
Josergio Zaragoza ◽  
Prashanth Asuri
Keyword(s):  
Mechanical Properties ◽  
Elastic Moduli ◽  
Particle Concentration ◽  
Noncovalent Interactions ◽  
Wide Range ◽  
Hydrogel Polymers ◽  
Crosslinker Concentration ◽  
Hydrogel Nanocomposite ◽  
Insight Into

Recent studies have expanded our understanding of the effects of nanoparticles on hydrogel mechanical properties. However, further studies are needed to validate the generality of these findings, as well as to determine the exact mechanisms behind the enhancements afforded by the incorporation of nanoparticles. In this study, we performed rotational rheological characterizations of chemically crosslinked poly(acrylamide) hydrogels incorporating silica nanoparticles to better understand the role of nanoparticles on the enhanced properties of hydrogel nanocomposites. Our results indicate that incorporating nanoparticles can lead to enhancements in hydrogel elastic moduli greater than the maxima obtainable through purely chemical crosslinking. Moreover, we find that the increases in elastic moduli due to the addition of nanoparticles not only depend on particle concentration, but also on the monomer and chemical crosslinker concentration. Finally, our data indicates a strong role for pseudo-crosslinking mediated by noncovalent interactions between the nanoparticles and hydrogel polymers on the observed reinforcements. Collectively, our results shed further insight into the role of nanoparticles on enhancements of mechanical properties of hydrogels and may thereby facilitate engineering specific mechanical properties in a wide range of hydrogel nanocomposite systems.

scholarly journals Role of Hydrodynamics, Li+ Addition and Transformation Kinetics on the Formation of Plate-Like {001} Calcite Crystals

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 250
Author(s):  
Nives Matijaković Matijaković Mlinarić ◽  
Jasminka Kontrec ◽  
Branka Njegić Njegić Džakula ◽  
Giuseppe Falini ◽  
Damir Kralj
Keyword(s):  
Crystal Growth ◽  
Ultrasound Irradiation ◽  
Research Model ◽  
Transformation Kinetics ◽  
Lithium Ions ◽  
Mechanical Stirring ◽  
Wide Range ◽  
Experimental Parameters ◽  
Kinetics Of

Plate-like calcite crystals with expressed unstable {001} planes are interesting research model for investigations of interfacial interactions of different additive molecules, but also the crystal growth mechanisms. The aim of this study is to reproducibly prepare a significant amount of well-defined plate-like calcite crystals and to investigate the critical experimental parameters. Thus, in precipitation system c(NaHCO3) = c(CaCl2) = 0.1 mol dm−3, the influence of hydrodynamic parameters (mode of mixing of the reaction components) and a presence of lithium ions Li+ within a wide range of concentrations, 0.0 mol dm−3 < c(Li+) < 1.0 mol dm−3, have been studied. In addition, the kinetics of the solution mediated transformation of the initially formed metastable polymorph, vaterite, were followed in order to reproducibly describe the formation of stable calcite with expressed unstable morphology. The results indicate that the plate-like calcite is formed predominantly when the ultrasound irradiation is applied at c(Li+) ≥ 0.3 mol dm−3. On the other hand, when the magnetic and mechanical stirring are applied at higher Li+ concentrations, truncated rhombohedral crystals in a mixture with plate-like crystals are obtained. It was also found that the Li+ addition significantly prolonged the transformation, mainly by inhibiting the crystal growth of calcite.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

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