Amount Of Fine Particles Research Articles

Effect of over-consolidation and shear rate on the residual strength of soils of silty sand in the Three Gorges Reservoir

Estimation of the residual strength of the soil on the landslide sliding surface is essential for analyzing reactivated landslides. This study investigated the influence of over-consolidation ratio (OCR) and shear rate on the residual strength of SM-type (silty sand) landslide soils in the Three Gorge Reservoir using ring shear tests under drained conditions. A series of ring shear tests were conducted to measure the drained residual strength under over-consolidation ratios of 1–12 and shear rates of 0.06–30.00 mm/min. Test results showed that residual strengths of SM-type landslide soils were not affected significantly by the over-consolidation process. The effect of shear rate on residual strength did not exhibit a regular pattern at shear rates of 0.06–10.00 mm/min, and behaved negatively at a high shear rate of 30 mm/min. The reduction in residual strength at higher shear rates may be attributable to increases in the water content of the shear zone and the amount of finer particles, due to particle breakage and/or larger grains being pushed from the shear zone.

Liberation properties of middling coking coal under shear force

The relationship between shear force and selective liberation of middling coking coal was investigated by crushing the coal at different shear angles (15°, 30°, 45°, 60°, and 75°). Subsequent analysis of the middling coking coal revealed that as the ash content of coal increased, the shear strength and cohesion increased, while the internal friction angle gradually decreased. Increasing the shear angle caused a gradual increase in the quantity of coarse particles and a decrease in the quantity of fine particles, ultimately leading to a dominant particle size of >10mm at a shear angle of 75°. The cumulative ash and cumulative yield curves showed that the liberation of middling coking coal through crushing was optimum when the shear angle was smaller than the internal friction angle. Lamellar tear fractures observed with low-shear-angle crushing could contribute to the liberation of coal, but the step-like morphology characteristics of medium and high shear angles was not conducive to liberation. Because the liberation of middling coking coal through crushing was optimum when the shear angle was smaller than the internal friction angle, a high ash content or high shear angle may make the release of clean coal more difficult.

Significance of breath-hold time in dry powder aerosol drug therapy of COPD patients

Aerosol drugs are effectively used to treat chronic respiratory diseases. The efficiency of the therapy depends also on the amount and distribution of drug deposited within the airways. The objective of this study is to apply numerical techniques to analyse the effect of the duration of breath-hold after the inhalation of six different commercialized dry powder drugs on their lung deposition. For this purpose a computational airway deposition model has been adapted and validated to the special case of therapeutic aerosols. Our results show that lung dose of the studied drugs can be enhanced by 11.3%–26.5% with a 5s breath-hold and by 20.7%–53% with a 25s breath-hold compared to the no-breath-hold case. Although this later duration may not be achieved by COPD patients, present results clearly show the importance of holding the breath as long as possible. Current computations also revealed that there is a strong positive correlation between the enhancement of lung dose as a result of breath-hold and the amount of fine particles in the drugs. Present tendencies aiming at producing drug particles of smaller and smaller sizes will lead to the further enhancement of the importance of producing a sufficiently long breath-hold time after the drug inhalation. In addition, higher lung deposition will be possible by the more correct use of inhalation devices, more precise and detailed patient information materials and personalized drug choice and therapy.

Evaluation of different types of calcined magnesites as feed supplement in small ruminant

Magnesium (Mg) deficiency in ruminants can be avoided by the inclusion of magnesium oxide (MgO) supplements in their diets. However, the behaviour of MgO supplements in the rumen depends on various factors such as ore-origin, calcination conditions, particle size distribution etc. Moreover, in most cases the solubility of MgO supplements (both in vitro and in vivo) is not related with their apparent bioavailability, so their quality should be evaluated primarily by using both in vitro and in vivo tests before using them in practice. Thus, the objectives of this study were: to determine: (a) the particle size distribution of four MgO supplements (Δ1, Δ2, Δ3 and Δ4) with different chemical composition and their both in vitro and in vivo solubility and (b) their apparent bioavailability. The solubility of MgO supplements was tested in an aqueous NH4NO3 solution (in vitro) and in sheep (in vivo). Five fistulated wether sheep of Karaguniko breed were used in a Latin-square (5×5) design to determine the in vivo solubility. The sheep were kept in metabolism cages and were given a basal diet (800g alfalfa hay and 600g concentrates). The same diet plus 2g of each MgO supplement was given to each sheep respectively during a 17-days period in order to determine their apparent bioavailability. The results showed that the solubility was depended on both the amounts of fine particles and the reactivity of the MgO supplements (P<0.05). A decrease in the solubility of the MgO supplements was found by increasing Fe2O3 and Al2O3 content. Despite the fact that for the most MgO supplements (Δ2, Δ3 and Δ4) a close relationship was found between solubility (both in vitro and in vivo) with apparent bioavailability this did not occur in the case of Δ1 MgO supplement. Moreover, the Δ4 MgO supplement was evaluated as the best candidate for feed supplement in ruminant’s diets, not only due to its better particle size distribution, but also to its significantly high solubility (both in vitro and in vivo) and bioavailability which was due to its high purity (>90%) and reactivity (49s) and lower content in Fe2O3 and Al2O3 compounds compared to the others. In conclusion, the properties of MgO supplements should be tested both in vitro and in vivo before their use in practice since they are affected by various factors.

Collapse of granular media subjected to wetting

This paper focuses on the collapse of granular materials subjected to wetting action. For soils, the collapse potential depends on several parameters such as liquid limit, matric suction, compactness, initial water content and the amount of fine particles. The effect of grain size, which plays a key role in the rearrangement of grains, remains little studied and poorly understood. To investigate the capillary origin of the collapse phenomenon, we present an experimental study on macroscopic and local scales. Our results show the effect of grain size and water content on collapse.

CFD-DEM study of the aerosolisation mechanism of carrier-based formulations with high drug loadings

Understanding the aerosolisation mechanism of carrier-based formulation with high drug loadings is crucial to developing high-dose dry powder inhalers. This paper investigated the effect of carrier-drug mass ratio in different conditions based on the combined computational fluid dynamics (CFD) and discrete element method (DEM) approach, aiming to develop better understanding of the aerosolisation mechanism of carrier-based formulation with high drug loadings. The carrier-based formulations composed of drug (salbutamol sulphate) and carrier (polystyrene bead) were formed with varied carrier-drug mass ratios ranging from 5:1 to 25:1. The aerosolisation process after impaction with a target wall was simulated and focuses mainly on the effects of four variables: carrier size, air flow velocities, impact velocities and impact angles. Dynamics of impact process and post-impact analysis were discussed. The fine particle fractions (FPFs), the amount of fine particles below 5μm in the aerosol, were measured to characterise the aerosolisation performance. The results showed that increasing the carrier-drug mass ratio will improved the aerosolisation performance. The influencing degree of carrier-drug mass ratio on aerosol performance was dependent on the carrier size. For a larger carrier with a high carrier-drug ratio corresponding to high surface coverage, the airflow velocity, impact velocity and angle have only a minor effect on the aerosolisation performance. The best solution was to use the smaller carriers to replace the larger ones if the requirements of drug loading and FPFs need to be satisfied at the same time. These conclusions could be used to help design the optimal carrier-drug mass ratio formulations for different carrier-based dry powder inhaler systems.

Mechanical Modification of Naturally Occurring Limestone for High-Temperature CO2 Capture

The rapid decrease of CO2 capture capacity is one of the most challenging problems hindering the use of naturally occurring limestone in the calcium looping process. In this work, the mechanical modification method (dry planetary ball milling) was used to improve the cyclic CO2 capture performance of naturally occurring limestone. Low-cost Bayer aluminum hydroxide sourced from the industrial-scale production of alumina from bauxite ore was used as the precursor of the inert support to enhance the CO2 sorption stability of the ball-milled sorbents. It was found that the CO2 uptake of the milled sorbents could be further improved by increasing the ball-milling time because this generated more amounts of fine particles. Moreover, the pellets produced from ball-milled limestone powder possessed a relatively high CO2 capture capacity of 0.252 g/g in the 25th cycle, which is nearly 1.3 times the capture capacity of naturally occurring limestone powder. This indicates that the combination of mechanical modificat...

Stress-Strain Behavior of Granular Soils Subjected to Internal Erosion

AbstractInternal erosion is a major cause of dam or dike failures and incidents. In this study, laboratory tests were conducted to investigate the deformation of two gap-graded soils during internal erosion and the stress-strain behavior of the soils that experienced loss of fine particles due to internal erosion. An erosion-controlled experimental method was adopted to achieve a designated loss of fine particles during internal erosion by adding a predefined amount of salt into the soil sample during sample preparation and dissolving the salt in water under a controlled stress condition. Both the radial and axial deformations during erosion were measured using a photographic method. Subsequently, drained triaxial compression tests were performed to study the stress-strain behavior of the soils that had lost different amounts of fine particles. The peak friction angle and critical friction angle of the soil decreased with the loss of fine particles. After a significant loss of fine particles, the stress-s...

Powder Characteristics of Fly Ash Beneficiated by Cold Plasma and Heat Treatment

Cold plasma and heat treatment were selected as technologies to reduce unburned carbon in fly ash to less than 1.0%. Both cold plasma and heat treatment made it possible to eliminate unburned carbon to less than 1.0%. In the case of fly ash, which almost entirely eliminated unburned carbon with an ignition loss of 0.5%, heat treatment caused adhesion among particles and the BET specific surface area rapidly decreased as the mean particle size increased. On the other hand, with cold plasma, unburned carbon elimination caused the BET specific surface area to decrease and, as no adhesion occurred among particles, the mean particle size became small. Also, cold plasma treatment allowed small spherical particles confined within the unburned carbon particles to be released with the elimination of the unburned carbon frame, so that the quantity of fine particles had a tendency to slightly increase.

Evaluation of the Effect of Aggregates Mineralogy and Geometry on Asphalt Mixture Friction

Road pavement friction is a main physical phenomenon of interaction between tires and the road surface; it provides skid resistance during accelerations and decelerations. The paper focuses on the effects, at laboratory scale, of geometry (in terms of fine aggregates - minimum/maximum size of 0.063/2 mm - content), mineralogy (basalt or metamorphic - minimum/maximum size of 8/16 mm) and shape (in terms on Flakiness and Shape index) on friction performance of asphalt wearing courses for road pavements, in terms of British Pendulum Number and Mean Texture Depth. Laboratory results were statistically treated and used to define predictive formulas which correlate friction characteristics and the explanatory variables considered by the study. The amount of fine particles in the mix and the shape of coarse aggregates demonstrated to affect friction properties and macro texture.

Advances in Granulation Technology

Granulation is used in the production of pharmaceutical oral dosage forms. It improves flow and compression characteristics, reduces segregation, improves content uniformity and eliminates excessive amounts of fine particles. The results can be improved yields, reduced tablet defects, increased productivity and reduced down time. Pharmaceutical products are processed all over the world using various granulation methods. The method depends on the ingredients individual characteristics and ability to properly flow, compresses, eject and disintegrate. Selection of method requires thorough investigation of each ingredient in the formula, the combination of ingredients and how they work with each other. Then the proper granulation process can be used. The present review article focuses on the novel granulation technology.

Effects of the shear gaps on the breakage behavior of silty sand particle

To determine the breakage behavior of soil particles on a sliding surface, which is subjected to high overburden stress, modified direct shear tests were conducted on silty sand collected from Kaohsiung City, Taiwan. The sliding surfaces of the soil was simulated using different shear gaps of the shear box in the tests. The behavior of the particle breakage and strength properties of the sand were investigated. The results indicated that finer soil particles exhibited a lower breakage potential and breakage amount of sand particles, whereas a higher void ratio tended to lead to a higher breakage potential and breakage amount. For soil samples consisting of the same amount of fine particles, wider shear gaps caused a higher void ratio, whereas the increment of fines content and volumetric strain were both reduced after the shearing process.

Production of Self Compacting Concrete SCC with Portland and Blended Cement CEM I, CEM II with Fly Ash and Limestone Admixtures

Production of SCC concrete involves using a higher amount of fine particles consisting primarily of using increased amounts of cement and one or more admixtures. Due to the economic performance of Portland cements, recently looking for ways to lower the environmental and economic burdens. The first production of SCC concrete production was recommended only cements CEM I. Now, the standards EN 206 specify such a requirement and therefore attempt to use cement CEM II and higher amount of admixtures. This paper points out the possibility of using blended cement CEM II in combination with admixtures and particular monitors rheological properties of fresh SCC concrete.

Évaluation critique des chambres d’inhalation commercialisées en France

To identify the spacer devices sold in France and to provide a critical evaluation in the light of the published data. We contacted the pharmaceutical companies, manufacturers and distributors of each spacer in order to obtain their technical parameters and the results of any in vitro or in vivo studies. A review of the literature via PubMed completed the first set of data. We were interested in the quantity of fine particles (less than 5 μm diameter) obtained with a cascade impactor at paediatric flow rates, for all inhaled drugs available in France. Eleven spacer devices were available in 2013 in France (Ablespacer®, Aerochamber Plus®, Babyhaler®, VHC Arrow®, L'Espace®, Funhaler®, Inhaler®, Itinhaler®, OptiChamber Diamond®, Tipshaler® and Vortex®), but three are no longer manufactured (Babyhaler®, Funhaler® and Inhaler®). All were small volume spacers, sold with facial masks of several different sizes. Four were antistatic (Aerochamber Plus®, Intinhaler®, OptiChamber Diamond® and Vortex®). Only salbutamol was tested with all the devices. Inhaled corticosteroids were tested with some and combinations were studied only with Ablespacer®, Aerochamber Plus®, Itinhaler®, and Vortex®. The results were difficult to interpret because the studies were conducted with very different protocols. The only clinical studies were conducted with Aerochamber Plus®, L'Espace® and Vortex®. There was a great disparity between commercialized spacer devices in terms of the available data describing their in vitro performance.

Influence of mineral aggregates on the rheological properties of concrete mixture

The aim of this research was to determine how the change of concrete mixture constituents: concentration of fine and coarse aggregate as well as the amount of fine particles, not exceeding 0.25 mm, influence concrete mixture's rheological properties. Firstly, inner- concentration of fine aggregate (sand, fraction of 0/1 and 0/4) was changed. Secondly, coarse aggregate (gravel, fraction of 4/16) concentration was changed and finally, the amount of fine particles was changed. Results have shown that with the increase of sand (fraction of 0/1) quantity, the plastic viscosity also increased. On the other hand, yield stress, at the beginning decreased, but eventually – increased. The increase of coarse aggregate quantity acted differently: plastic viscosity and yield stress decreased. Finally, the increase of fine particles quantity decreased the plastic viscosity as well as yield stress of concrete mixture.

Determination of The Basic Characteristics of Sludge for Utilization in Building Cement Composites

This paper presents the results of basic research using sludge as a secondary material produced during the process of wet aggregates grading. The basic objective of this study was to identify important properties of sludge for the further use as substitute filler in the cement composites. Results of tests executed, like determination of particle size, bulk density, chemical composition (XRF method), mineralogical composition (XRD method) and both clay lumps and humus content were compared with those of natural aggregate (reference sample), as well as with standard criteria. For all tested properties, sludge shows satisfactory parameters, except the granularity. Here samples demonstrate high portions of fine particles in the 0/4 range. Thus can be concluded, sludge has a potential to be used as filler in cement composites requiring bigger amounts of fine particles, like self-compacting concretes.

Determination of the basic characteristics of sludge for utilization in building cement composites

This paper presents the results of basic research using sludge as a secondary material produced during the process of wet aggregates grading. The basic objective of this study was to identify important properties of sludge for the further use as substitute filler in the cement composites. Results of tests executed, like determination of particle size, bulk density, chemical composition (XRF method), mineralogical composition (XRD method) and both clay lumps and humus content were compared with those of natural aggregate (reference sample), as well as with standard criteria. For all tested properties, sludge shows satisfactory parameters, except the granularity. Here samples demonstrate high portions of fine particles in the 0/4 range. Thus can be concluded, sludge has a potential to be used as filler in cement composites requiring bigger amounts of fine particles, like self-compacting concretes.

Drying and Grinding Characteristics of Four‐Day‐Germinated and Crushed Wheat: A Novel Approach for Producing Sprouted Flour

The purpose of this study was to examine the drying and grinding characteristics of sprouted and crushed wheat. The four‐day‐germinated wheat kernels were crushed, dried, and ground in a micro hammer mill. The drying kinetics of sprouts were best described by the Page and two‐factor models. The crushing of wheat sprouts before drying decreased the drying time by about half. Sprouting and crushing of wheat sprouts have a significant influence on the grinding process, both on the particle size distribution and on the grinding energy requirements. It was observed that the ground sprouts showed significantly lower values of average particle size compared with the samples of sound kernels. Sprouting caused an increase in the amount of fine particles (&lt;0.2 mm) and a decrease in the mass fraction of coarse particles (&gt;1.0 mm). All values of grinding indices showed that sprouting and crushing significantly reduced the grinding energy requirements. Moreover, sprouting significantly increased the total phenolics content (from 26 to 31%) and antioxidant activity (from 33 to 72%) of wheat kernels. The results showed that sprouting and crushing of sprouts followed by their drying and grinding may provide a practical method for preparing sprouted flour.

Influence of aggregate characteristics on workability of superworkable concrete

Physical characteristics of aggregates have a significant influence on the performance of concrete. Compared to conventional concrete, the mix design of highly flowable concrete is more complex and should ensure that the mixture can develop adequate static and dynamic stability. The selection of aggregate plays a major role for the mix design and mixture optimization of flowable concrete. The study seeks to understand the influence of physical characteristics of coarse and fine aggregates, including packing density, texture or roughness, fine particle content, shape, and quantity of flat and elongated particles on the workability, rheological properties, and mechanical properties of superworkable concrete (SWC). Three types of sands with different fineness moduli of 2.5, 2.6, and 3.0 and different textures (smooth and rough) were used. Seven types of coarse aggregates with different texture characteristics, flat and elongated particle contents, and different shapes were investigated. Sand-to-total aggregate volume ratio was varied between 0.45 and 0.60. Test results indicated that the packing density, the quantity of fines passing 315 µm sieve, and the shape of coarse aggregate can have significant effect on rheology, stability, and compressive strength of SWC. For the crush aggregate with 5–14 mm particle sizes (CA14), a 13 % increase in aggregate packing density from 0.69 to 0.79 by the use of optimum sand-to-aggregate ratio and natural sand can lead to more than 50 % reduction in surface settlement, i.e. 50 % increase in static stability. For the CA14 coarse aggregate, a good relationship was established between surface settlement and quantity of fine particles with diameter smaller than 315 µm. Mixtures with rounded coarse aggregates had 22–42 % higher surface settlement compared to those made with crushed aggregates of the same maximum size aggregate.

Effect of fine particles on the hydraulic behavior of interlayer soil in railway substructure

The conventional railway substructure in France was built by emplacing ballast directly on subgrade. Over years of operation, the interpenetration of ballast and subgrade created a soil layer between them. Under different conditions, this naturally formed layer, namely interlayer, can contain different quantities of fine particles, becoming more or less sensitive to changes in water content. As the water content changes are governed by the hydraulic behavior of the interlayer soil, assessing the influence of fine particle content on the hydraulic behavior of interlayer soil is of importance. To this end, the hydraulic behavior of an interlayer soil taken from Sénissiat (near Lyon, France) was investigated using two infiltration columns, a large-scale column equipped with tensiometers and a time domain reflectometer (TDR) for suction and volumetric water content measurements, respectively, and a smaller column equipped with high-capacity tensiometers only. Different fines contents were considered and wetting–drying cycles were applied to the soil specimens. The hydraulic conductivity was determined by applying the instantaneous profile method. The results obtained showed that (i) hysteresis exists for both the soil water retention curve and the hydraulic conductivity changes with suction; (ii) the effect of wetting–drying cycles is insignificant; (iii) adding 10% fine particles to the natural interlayer soil gives rise to changes in the soil water retention curve but does not induce significant changes in hydraulic conductivity; (iv) the unsaturated hydraulic conductivity of interlayer soil with 10% fine particles added is close to that of soil sieved at 2 mm, suggesting that the unsaturated hydraulic conductivity of interlayer soil is mainly governed by fine particles through the suction effect. By contrast, in a saturated state, the value for the interlayer soil with 10% fine particles added was found to be higher, suggesting that in this case the hydraulic conductivity is mainly governed by the water transfer through macropores.