The measurement of latex particle sizes using scattering ratios in the rayleigh scattering size range

1989 ◽  
Vol 20 (3) ◽  
pp. 331-345 ◽  
Author(s):  
Robert G. Knollenberg
Keyword(s):  
Rayleigh Scattering ◽  
Latex Particle ◽  
Size Range ◽  
Particle Sizes

scholarly journals Characterization of cellulose acetate based on empty fruit bunches and dried jackfruit leaves as replacement candidates for microbeads

2018 ◽  
Vol 67 ◽  
pp. 04024
Author(s):  
Dewi Tristantini ◽  
Andersen Yunan
Keyword(s):  
Water Absorption ◽  
Cellulose Acetate ◽  
Size Range ◽  
Acid Anhydride ◽  
Particle Sizes ◽  
Oil Absorption ◽  
Empty Fruit Bunches ◽  
Alternative Sources ◽  
Beauty Products

Scrubs used in other skin care and beauty products usually contain tiny fine grains of synthetic polymer called microbeads that usually pose threats to marine environment. Empty Fruit Bunches (EFB) and Dried Jackfruit Leaves (DJL) as organic and environmentally friendly can be alternative sources for polymer microbeads. Cellulose acetate is prepared by acetylation reaction between cellulose and acetic acid anhydride. Cellulose from EFB and DJL was extracted through a process of delignification with 12% NaOH treatment for EFB and 10% for DJL to obtain maximum yields of 38.964% and 14.449% respectively, followed by bleaching using peroxide 10 %. The formed cellulose acetate with 88.5% and 79.7% yield respectively is then filtered using a sieve mash 60 and 80 to obtain particle sizes ranging that are in the microbeads size range. The density test resulting in 0.73 g/cm3 and 0.52 g/cm3 respectively for EFB and DJL. Then, physical characteristic test was done by water and oil absorption test with variation at 25°C and 40°C. EFB at 25°C and 40°C shows water absorption at 23.39% and 26.09% and oil absorption at 7.59% and 13.95%. DJL at 25°C and 40°C shows water absorption at 22.56% and 27.32% and oil absorption at 13.09% and 15.36%.

scholarly journals Frac sand crushing characteristics and morphology changes under high compressive stress and implications for sand pack permeability

2016 ◽  
Vol 53 (9) ◽  
pp. 1412-1423 ◽  
Author(s):  
Wenbo Zheng ◽  
Dwayne Tannant
Keyword(s):  
Particle Shape ◽  
Void Ratio ◽  
Size Range ◽  
Particle Sizes ◽  
Shale Formations ◽  
Closure Stress ◽  
Compressive Stresses ◽  
Spherical Grains ◽  
Particle Shapes ◽  
Quartz Grains

Sand consisting of round quartz grains is widely used as a proppant during hydraulic fracturing to produce natural gas from tight shale formations. This paper presents results from sand characterization and crushing tests on Jordan Formation frac sand. It includes an assessment of grain-size reduction, changes in particle shape, and reduction in void ratio. It also examines the implications for permeability reduction through a sand pack caused by the closure stress on a hydraulic fracture. The sand from two size ranges (0.6 to 0.71 mm and 0.5 to 0.6 mm) was tested dry under applied compressive stresses of up to 40 MPa in a crushing cup. The overall sand pack stress–strain response becomes softer as grains are crushed. The particle shape shifts from nearly spherical grains to diametrically split grains and then to small elongated and angular fragments for the smaller particle sizes. The permeability of the sand pack reduces by more than 40% at a 20 MPa stress, which is mainly caused by a decrease in void ratio due to compaction. The permeability reduces by over 70% at a 40 MPa stress, which is primarily caused by void ratio decrease, reduction in particle size, and a shift away from spherical particle shapes. Compared to the ISO 13503-2 standard where only the sand crushing percentage after crushing tests is measured, this paper demonstrates that more information can be extracted from sand crushing tests and that sand pack permeability can be assessed to optimize frac sand selection. A sand with a larger size range has a higher crushing percentage, but is more permeable compared to a sand with a smaller size range. This further indicates that frac sand selection based only on sand crushing percentage is not sufficient to achieve better sand pack permeability.

Dynamic Light Scattering at CdSe Nanocrystals and CdSe Cluster-Molecules

2000 ◽  
Vol 636 ◽  
Author(s):  
A. Eichhöfer ◽  
C.V. Hänisch ◽  
M. Jacobsohn ◽  
U. Banin
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
High Performance ◽  
Size Range ◽  
Blue Shift ◽  
Cdse Nanocrystals ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
X Ray

AbstractHigh performance dynamic light scattering (DLS) has been used to determine the hydrodynamic diameters of CdSe-nanocrystals as well as CdSe cluster molecules in a size range of 1 to 10 nm. The method enables the determination of the particle sizes including the ligand shells directly in solution. Consistent with the blue shift of the absorption onset by reducing the particle sizes the values for the hydrodynamic radii decrease. For the CdSe nanoparticles the measured sizes were compared with the diameters determined by TEM experiments; the sizes of the cluster molecules were on the other hand estimated from the space filling models of the single crystal X-ray structure determination. Regarding both types of compounds, DLS yield comparable values for the radii, indicating that it provides a potentially important tool in addition to other size determining techniques like TEM, which operates at more drastic conditions, and powder X-ray diffraction being difficult to interpret below 5 nm.

scholarly journals A discrete interaction numerical model for coagulation and fragmentation of marine detritic particulate matter (Coagfrag v.1)

2021 ◽  
Vol 14 (7) ◽  
pp. 4535-4554
Author(s):  
Gwenaëlle Gremion ◽  
Louis-Philippe Nadeau ◽  
Christiane Dufresne ◽  
Irene R. Schloss ◽  
Philippe Archambault ◽  
...  
Keyword(s):  
Particle Size ◽  
General Circulation ◽  
Size Range ◽  
Circulation Model ◽  
Mass Conservation ◽  
Ocean General Circulation Model ◽  
Global Constraints ◽  
Size Spectrum ◽  
Particle Sizes ◽  
Organic Particles

Abstract. A simplified model, representing the dynamics of marine organic particles in a given size range experiencing coagulation and fragmentation reactions, is developed. The framework is based on a discrete size spectrum on which reactions act to exchange properties between different particle sizes. The reactions are prescribed according to triplet interactions. Coagulation combines two particle sizes to yield a third one, while fragmentation breaks a given particle size into two (i.e. the inverse of the coagulation reaction). The complete set of reactions is given by all the permutations of two particle sizes associated with a third one. Since, by design, some reactions yield particle sizes that are outside the resolved size range of the spectrum, a closure is developed to take into account this unresolved range and satisfy global constraints such as mass conservation. In order to minimize the number of tracers required to apply this model to an ocean general circulation model, focus is placed on the robustness of the model to the particle size resolution. Thus, numerical experiments were designed to study the dependence of the results on (i) the number of particle size bins used to discretize a given size range (i.e. the resolution) and (ii) the type of discretization (i.e. linear vs. nonlinear). The results demonstrate that in a linearly size-discretized configuration, the model is independent of the resolution. However, important biases are observed in a nonlinear discretization. A first attempt to mitigate the effect of nonlinearity of the size spectrum is then presented and shows significant improvement in reducing the observed biases.

The Relationship Between Colliery-waste Particle Sizes and Plant Growth

1974 ◽  
Vol 1 (4) ◽  
pp. 281-284 ◽  
Author(s):  
Christopher G. Down
Keyword(s):  
Particle Size ◽  
Plant Growth ◽  
Water Retention ◽  
Size Range ◽  
Growth Period ◽  
Dry Weight ◽  
Particle Sizes ◽  
Small Particles ◽  
The Relationship ◽  
Water Holding

Seed germination and dry-weight production in Lolium perenne were examined in relation to growth on 12-years-old colliery waste separated into seven size-fractions. The size-range was from more than 4,000 μ to less than 125 μ, and the growth period was up to 30 days. Germination percentages after 6 days generally increased with decreasing particle-size, as did dry-weight. Shoot : root ratios also showed an inverse relationship with particle size.After 30 days there was no distinction between dryweights on different particle sizes, except that on the largest fractions it had been found impossible to keep the plants alive. Problems of water-holding capacity are discussed, and the significance of soil particle-size in revegetation work is examined, it being concluded that an admixture of small particles is important for water retention and plant growth.

scholarly journals Aerosol filtering efficiency of respiratory face masks used during the COVID-19 pandemic

2020 ◽  
Author(s):  
Glykeria Loupa ◽  
Dimitra Karali ◽  
SPYRIDON RAPSOMANIKIS
Keyword(s):  
Respiratory System ◽  
Indoor Air ◽  
Size Range ◽  
Protective Measure ◽  
Particle Sizes ◽  
Personal Protection ◽  
Protection Measures ◽  
The Face ◽  
Filtering Efficiency

The spread of the COVID-19 pandemic, effected the imposition of personal protection measures in a large number of countries. The use of commercially available personal face masks was widely accepted as such a protective measure. Since the quality of the face masks scanned the spectrum from surgical to the home made fabric ones, it was considered appropriate to experimentally establish their effectiveness for stopping aerosol in entering the respiratory system of the bearer. Presently, the masks were tested with polydisperse indoor air. Their effectiveness was examined for aerosol of aerodynamic diameters of 0.006 μm to 10 μm. Of these masks, only two were effective for the whole range of aerosol. Cloth masks were found to be ineffective for the whole spectrum of aerosol particle sizes and especially in SARS-CoV-2 virus most abundant size range.

Finasteride-loaded biodegradable nanoparticles: Near-infrared quantification of plasma and prostate levels

2017 ◽  
Vol 32 (6) ◽  
pp. 557-567 ◽  
Author(s):  
Osama AA Ahmed ◽  
Usama A Fahmy ◽  
Ahmed S Al-Ghamdi ◽  
Bader M Aljaeid ◽  
Hibah Aldawsari ◽  
...  
Keyword(s):  
Encapsulation Efficiency ◽  
Glycolic Acid ◽  
Near Infrared ◽  
Size Range ◽  
Prostatic Hyperplasia ◽  
Release Time ◽  
Particle Sizes ◽  
Solvent Evaporation Method ◽  
Orally Active

Finasteride is an orally active testosterone 5-alpha-reductase inhibitor that is used for the treatment of benign prostatic hyperplasia as a surgical alternative. The aim of this work was to improve finasteride levels in plasma and prostate through the formulation of biodegradable finasteride nanoparticles and to quantify finasteride levels using near-infrared application. Finasteride nanoparticles were prepared by emulsion solvent evaporation method utilizing the biodegradable polymers poly(lactic- co-glycolic acid) and poly-ϵ-caprolactone. The prepared nanoparticles were characterized by particle size, zeta potential, and encapsulation efficiency. The selected finasteride-biodegradable formula was examined in vivo, and both plasma and prostate levels of finasteride were quantified utilizing near-infrared technique. Results revealed that the prepared finasteride nanoparticles size range was from 231 ± 78 to 956 ± 224 nm with finasteride–poly-ϵ-caprolactone nanoparticles showing larger particle sizes compared with finasteride–poly(lactic- co-glycolic acid) nanoparticles. The encapsulation efficiency ranged from 68.89% ± 2.99% to 99.15% ± 4.32%. The selected formula of finasteride nanoparticles showed improved levels of finasteride in both plasma and prostate of the investigated rats. The realization of sustained release of biodegradable finasteride nanoparticles for possible oral or parenteral application could improve the activity of the drug for sustaining release time with lower dosing recurrence that improves patient compliance.

Application of mineral magnetism to describe profile development of toposequences of a sedimentary soil in south-eastern Australia

Soil Research ◽  
2001 ◽  
Vol 39 (5) ◽  
pp. 927 ◽  
Author(s):  
R. H. Crockford ◽  
I. R. Willett
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Magnetic Susceptibility ◽  
Magnetic Particles ◽  
Size Range ◽  
The Other ◽  
Particle Sizes ◽  
Mineral Magnetism ◽  
Particle Size Range ◽  
Eastern Australia

Mineral magnetism and chemical properties of soil profiles across a valley with an erosion gully in a Yellow Dermosol sedimentary soil suggest that the magnetic profile resulted from a combination of alluviation and pedogenesis. The concentration of soil magnetic minerals in a range of particle sizes (3.36–2 mm to <2 μm) diminished from the surface downwards to a minimum (referred to as layer P), then increased to high values (layer H), after which it decreased to bed rock level at the base layer. It is proposed that the H layer was the surface of a buried soil, and that the ferrimagnetic mineral through the profiles was dominantly maghemite, formed by fire enhancement. The magnetic pattern of the profiles compressed as the soil became shallower up-slope, from 3 m in depth at the lowest site to 0.7 m at a site 40 m up-slope. Above this site the high susceptibility H layer was absent, which is consistent with the H layer being an earlier soil surface. Except for the profile at the very top of the slope (depth of 0.63 m), the magnetic grain size did not vary with depth. In the P layers, there was a greater proportion of paramagnetic minerals than in the other layers. The changes in magnetic susceptibility through the profiles were influenced by ferrimagnetic, paramagnetic, and canted anti-ferromagnetic material. For all depths in all profiles the magnetic susceptibility changed consistently through the particle size range, decreasing from the larger sizes to the 10–20 m size then increasing slightly to the smallest size (<2 μm). The mean magnetic grain size also decreased through the particle size range. Magnetic particles of 3 concentration levels were extracted by a hand magnet from the 4 largest particle sizes and showed the same magnetic-particle size relationships, for both mass susceptibility and magnetic grain size, as the other particle sizes. This showed that the proportion of highly magnetic particles effectively determined the susceptibility and magnetic grain size features of the bulk samples of each particle size class. The particle size/magnetic susceptibility pattern described in this paper occurs in all sedimentary soils and derived river sediments studied in this part of Australia. However, soils and sediments of granitic origin have an inverse pattern. These differences are attributed to pedogenic and geomorphological process. The difficulties in using mineral magnetic properties as a means of sourcing mobile sediments in catchments are discussed.

CeO2 Particles for Chemical Mechanical Planarization

2003 ◽  
Vol 767 ◽  
Author(s):  
Xiandong Feng ◽  
Yie-Shein. Her ◽  
W. Linda. ◽  
Jackie Davis ◽  
Eric Oswald ◽  
...  
Keyword(s):  
Cerium Oxide ◽  
Surface Quality ◽  
Temperature Effects ◽  
Size Range ◽  
Chemical Mechanical Planarization ◽  
Particle Sizes ◽  
Additive Concentration ◽  
Solution Ph ◽  
Size Growth ◽  
Oxide Particles

AbstractNano-sized cerium oxide particles in the size range of 5 to 500nm have been synthesized for use in chemical mechanical planarization (CMP) applications. The CeO2 particles were prepared using cerium nitrate salts with bases such as ammonium water, ethylamine, or other alkylamine /polyalkylamine compounds. Other additives such as urea can be added to affect crystallization and size growth of the final particles. The particle sizes of the resulting CeO2 particles depend on the initial concentrations of cerium salts, additive concentration, and solution pH. Reaction duration seems to have little effect on CeO2 particle sizes. Temperature effects on size were moderate. These CeO2 particles showed excellent surface quality and desirable polishing rate during CMP tests.

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