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Sensors (Basel, Switzerland) Jan 2022Carbonate sand is often encountered and utilized as construction material in offshore engineering projects. Carbonate sand particles, which are porous and angular, are...
Carbonate sand is often encountered and utilized as construction material in offshore engineering projects. Carbonate sand particles, which are porous and angular, are found to be highly crushable under high stress conditions, whereas the mechanisms and controlling factors for the crushing of carbonate sand particles are not well developed. The crushability and particle strength of around 400 particles from three fractions (5-10 mm, 2-5 mm, and 1-2 mm) of carbonate sand from the South China Sea were investigated via grain-scale single particle crushing tests. Special emphasis was placed on the effect of external constraint conditions (i.e., coordination number) and intrinsic particle morphology characteristics on the particle strength of carbonate soil. The particle strength of carbonate sand was found to be around half of quartz sand in terms of characteristic stress. Negative correlations, which could be depicted by an exponential equation, were found between the particle size and particle strength. Due to elongated particle shape and tensile stress concentration, a higher coordination number may lower the particle strength, which contradicts what was reported for quartz sands. A series of seven fundamental particle dimensions and five particle shape descriptors was characterized, and the aspect ratio was found to be one of the more influential shape descriptors for particle strength. The results enriched the database for the analysis of highly irregular geomaterial and provided insights into controlling factors of particle strength and crushing mechanisms of the carbonate sand.
Topics: Carbonates; Particle Size; Porosity; Quartz; Sand
PubMed: 35161512
DOI: 10.3390/s22030765 -
European Journal of Pharmaceutical... Jul 2022The definition of the local dissolution environment is central to accurate particle dissolution simulation, and is determined by the apparatus and conditions used. In...
The definition of the local dissolution environment is central to accurate particle dissolution simulation, and is determined by the apparatus and conditions used. In the flow-through apparatus dissolution occurs in the cell, often in a low velocity environment, with the reservoir considered the relevant volume for dissolution kinetics. Dissolution simulations were conducted using a reduced-order model based on the Ranz-Marshall correlation for mass transfer from spherical particles. Using ibuprofen as a model drug, the effect of defining a local volume to simulate dynamic bulk concentration conditions in the flow-through and paddle apparatus was assessed by comparing use of a near particle volume (NPV), extending a distance of one radius from the particle surface, with a flow-through apparatus cell volume or paddle apparatus vessel volume as the relevant instantaneous volume for dissolution. The instantaneous inlet concentration to NPV or cell volume is the reservoir/vessel concentration at that simulation time point, reflecting the continuous input to the cell of more dilute solution from the reservoir (closed system). Additionally, inputting particle size distribution (PSD) instead of a median particle size (MPS) and enabling or disabling particle motion were investigated, in two media (resulting in low and high solubility) and with two fluid velocity conditions in each apparatus. The NPV predicted effects of fluid velocity differences on dissolution in the high solubility medium in the flow-through apparatus, but had no effect on predictive ability in the paddle apparatus. In both apparatuses, simulations were reasonable for the high solubility environment but underpredicted dissolution in the low solubility environment. The PSD option and disabling particle motion increased the predictive ability of the simulations in low solubility media in the flow-through apparatus. The results highlight the necessity to incorporate the local dynamic dissolution conditions in the flow-through apparatus for accurate dissolution simulation, and the challenges of defining an effective particle size for dissolution simulation and of reflecting hydrodynamic complexity in simulating dissolution in the paddle apparatus.
Topics: Chemistry, Pharmaceutical; Computer Simulation; Hydrodynamics; Particle Size; Solubility
PubMed: 35398291
DOI: 10.1016/j.ejps.2022.106185 -
The Science of the Total Environment Mar 2020Plastic pollution has become a major environmental concern due to its omnipresence and degradation to smaller particles. The potential toxicological effects of micro-... (Review)
Review
Plastic pollution has become a major environmental concern due to its omnipresence and degradation to smaller particles. The potential toxicological effects of micro- and nanoplastic on biota have been investigated in a growing number of exposure studies. We have performed a comprehensive review of the main determining factors for plastic particle toxicity in the relevant exposure systems, from publications until including the year 2018. For a focused scope, effects of additives or other pollutants accumulated by the plastic particles are not included. In summary, current literature suggests that plastic particle toxicity depends on concentration, particle size, exposure time, particle condition, shape and polymer type. Furthermore, contaminant background, food availability, species, developmental stage and sex have major influence on the outcome of plastic particles exposures. Frequently reported effects were on body and population growth, energy metabolism, feeding, movement activity, physiological stress, oxidative stress, inflammation, the immune system, hormonal regulation, aberrant development, cell death, general toxicity and altered lipid metabolism. Several times reported were increased growth and food consumption, neuro-, liver- or kidney pathology and intestinal damage. Photosynthesis disruption was reported in studies investigating effects on phytoplankton. For the currently unquantified plastic particles below 10 μm, more toxic effects were reported in all aquatic life, as compared to plastic particles of larger size.
Topics: Environmental Pollutants; Nanostructures; Particle Size; Plastics
PubMed: 31887526
DOI: 10.1016/j.scitotenv.2019.136050 -
Biology Open Sep 2023The webbed foot structure of mallards (Anas platyrhynchos) exhibits effective anti-subsidence properties when walking on soft ground. To investigate the effects of...
The webbed foot structure of mallards (Anas platyrhynchos) exhibits effective anti-subsidence properties when walking on soft ground. To investigate the effects of quartz sand particle size and thickness on joint angles and the movement patterns of webbed feet, we created a testing substrate with quartz sand and utilized high-speed cameras and kinematic analysis tools for data acquisition. Mallards mainly adjusted the tarsometatarso-phalangeal joint (TMTPJ) during touch-down and lift-off stages in response to increasing particle size or enhanced ground roughness. Conversely, adjustments to the intertarsal joint (ITJ) predominantly took place during mid-stance. Conversely, mallards predominantly adjusted the ITJ during touch-down and lift-off when coping with increased quartz sand thickness, with TMTPJ adjustments mainly occurring at touch-down. As quartz sand particle size increased, the TMTPJ angle increased, the ITJ angle decreased, toe closure advanced, and the duty factor decreased throughout the entire stride cycle. In contrast, increasing quartz sand thickness led to more delayed TMTPJ adjustments, slower webbed foot closure, and an increased duty factor throughout the stride cycle. Mallards modify their leg posture to notably decrease the touch-down foot angle upon encountering sandy terrain. This action subsequently forms a depression beneath their feet, contributing to sand consolidation and limiting flow. During the stance phase, the mallard's weight is distributed across the webbed foot, generating minimal pressure and preventing significant subsidence while walking on sandy ground.
Topics: Quartz; Sand; Biomechanical Phenomena; Particle Size; Lower Extremity
PubMed: 37605960
DOI: 10.1242/bio.060012 -
Pharmaceutical Development and... Mar 2022In this paper, two types of parameters representing tabletability and compactibility profiles of a series of -lactose monohydrate powders, ranging in particle size from...
In this paper, two types of parameters representing tabletability and compactibility profiles of a series of -lactose monohydrate powders, ranging in particle size from approximately 3.5 to 203 µm, are derived and compared. By approximating the tabletability profiles using a three-stage model and the compactibility profiles using the Ryshkewitch-Duckworth equation, two compaction rate parameters and two compaction endpoint parameters were derived. The original median particle diameter had generally a strong effect on the tablet tensile strength and hence the tabletability and compactibility profiles. The experimental profiles were well approximated by the models used, and the compaction parameters were regarded as representative of the experimental profiles. The compaction endpoint parameters increased with decreased particle size and were controlled by the same structural feature as the compacts. The tabletability rate parameter also increased with decreased particle size and correlated well with the tabletability endpoint parameter. The compactibility rate parameter tended to increase with decreased particle size, but the effect was limited; moreover, no general correlation was obtained with the compactibility endpoint parameter. It is concluded that compactibility and tabletability parameters collectively provide a concentrated description of the compaction properties of a powder.
Topics: Drug Compounding; Lactose; Particle Size; Powders; Tablets; Tensile Strength
PubMed: 35285375
DOI: 10.1080/10837450.2022.2051550 -
European Journal of Pharmaceutics and... Nov 2022The aim of this study was to determine the thickness of the hydrodynamic diffusion layer (h) of three poor water-soluble compounds under laminar fluid flow using a...
The aim of this study was to determine the thickness of the hydrodynamic diffusion layer (h) of three poor water-soluble compounds under laminar fluid flow using a single particle dissolution technique. The single particle dissolution experiments were performed in a flowing aqueous medium using four different fluid velocities (v), ranging from 46 to 103 mm/s. The particles used had an initial radius (r) of 18.8 to 52.3 μm. The determined h values were calculated from both dissolution experiments and computational fluid dynamics (CFD) simulation. In this study, single particle dissolution experiments gave, with one exception, h values in the range of 2.09 to 8.85 µm and corresponding simulations gave h values in the range of 2.53 to 4.38 µm. Hence, we found a semi-quantitative concordance between experimental and simulated determined h values. Also, a theoretical relation between the dependence of h on particle radius and flow velocity of the medium was established by a series of CFD simulations in a fluid velocity range of 10-100 mm/s and particle size (radius) range of 5-40 µm. The outcome suggests a power law relation of the form h∝rv. In addition, the h seems to be independent of the solubility, while it has a diffusion coefficient dependence. In conclusion, the h values were determined under well-defined conditions; hence, this approach can be used to estimate the h under different conditions to increase the understanding of the mass transfer mechanisms during the dissolution process.
Topics: Computer Simulation; Diffusion; Hydrodynamics; Particle Size; Solubility
PubMed: 36152951
DOI: 10.1016/j.ejpb.2022.09.016 -
Small (Weinheim An Der Bergstrasse,... Apr 2022Today, millimeter-sized nonspherical any-shape particles serve as flexible, functional scaffold material in chemical and biochemical reactors tailoring their...
Today, millimeter-sized nonspherical any-shape particles serve as flexible, functional scaffold material in chemical and biochemical reactors tailoring their hydrodynamic properties and active surface-to-volume ratio based on the particle's shape. Decreasing the particle size to smaller than 100 μm would be desired as it increases the surface-to-volume ratio and promotes a particle assembly based on surface interactions, allowing the creation of tailored self-assembling 3D scaffolds. This study demonstrates a continuous high-throughput fabrication of microscopic 3D particles with complex shape and sub-micron resolution using continuous two-photon vertical flow lithography. Evolving from there, in-channel particle fabrication into a confined microfluidic chamber with a resting fluid enables the precise fabrication of a defined number of particles. 3D assemblies with various particle shapes are fabricated and analyzed regarding their permeability and morphology, representing convective accessibility of the assembly's porosity. Differently shaped particles highlight the importance of contact area regarding particle-particle interactions and the respective hydraulic resistance of an assembly. Finally, cell culture experiments show manifold cell-particle interactions promising applicability as bio-hybrid tissue. This study pushes the research boundaries of adaptive, responsive, and permeable 3D scaffolds and granular media by demonstrating a high throughput fabrication solution and a precise hydrodynamic analysis method for micro-particle assemblies.
Topics: Hydrodynamics; Microfluidics; Particle Size; Permeability; Porosity
PubMed: 35246951
DOI: 10.1002/smll.202107508 -
Journal of Pharmaceutical Sciences Aug 2021The aim of this work was to identify from a review of current literature the effects of lipids used in the development of Nanostructured Lipid Carriers (NLCs) on the... (Review)
Review
The aim of this work was to identify from a review of current literature the effects of lipids used in the development of Nanostructured Lipid Carriers (NLCs) on the physicochemical properties of the resulting formulation. The size of the solid lipid, affected by the molecular weight and the complexity of the structure, tends to affect the particle size of the final formulation proportionally; the higher the molecular weight and the more complex the molecular structure, the bigger the particle size of the NLCs. However, there is no straight correlation between the size and the structure of the liquid lipid and the particle size. Moreover, there seems to be a correlation of the solid to liquid lipid ratio which affects the particle size; there has been a trend of increasing particle size when more solid lipid was used. Regarding the entrapment efficiency, it is highly affected by the drug and its interaction with the lipids, as its solubility in the lipids needs to be high so the drug can stay entrapped within the lipid core. There was no direct correlation between the type of lipid used or the ratio and the zeta potential, which affects the stability of the NLCs.
Topics: Drug Carriers; Lipids; Nanostructures; Particle Size; Solubility
PubMed: 33901564
DOI: 10.1016/j.xphs.2021.04.012 -
Journal of Environmental Sciences... Aug 2019In order to evaluate the influence of particle size and particle concentration on the coagulation process, two kinds of particle suspensions, nanoparticles and...
In order to evaluate the influence of particle size and particle concentration on the coagulation process, two kinds of particle suspensions, nanoparticles and microparticles, were employed to investigate the effect of particle size on coagulation mechanisms with varying coagulation parameters. Results showed that it is easier for nanoparticles to cause self-aggregation because of Brownian motion, while interception and sedimentation are the mainly physical processes affecting particle transport for microparticles, so they are more stable and disperse more easily. The particle size distribution and particle concentration had distinct influence on the coagulation mechanisms. Under neutral conditions, as the amount of coagulant increased, the coagulation mechanism for nanoparticles changed from charge neutralization to sweep flocculation and the nanoparticles became destabilized, re-stabilized and again destabilized. For microparticles, although the coagulation mechanism was the same as that of nanoparticles, the increased rate of aluminum hydroxide precipitation exceeded the adsorption of incipiently formed soluble alum species, resulting in the disappearance of the re-stabilization zone. Under acidic conditions, Brownian motion dominates for nanoparticles at low particle concentrations, while sweep flocculation is predominant at high particle concentrations. As for microparticles, charge neutralization and sweep flocculation are the mechanisms for low and high particle concentrations respectively. Under alkaline condition, although the mechanisms for both nano- and microparticles are the same, the morphology of flocs and the kinetics of floc formation are different. At low particle concentrations, nanoparticles have larger growth rate and final size of flocs, while at high particle concentrations, nanoparticles have higher fractal dimension and recovery factors.
Topics: Alum Compounds; Aluminum Hydroxide; Flocculation; Fractals; Hydrogen-Ion Concentration; Models, Chemical; Nanoparticles; Particle Size
PubMed: 31133268
DOI: 10.1016/j.jes.2019.02.021 -
Lab on a Chip Nov 2022Traditionally, comprehensive laboratorial experiments on newly proposed microfluidic devices are necessary for theoretical validation, technological design,...
Traditionally, comprehensive laboratorial experiments on newly proposed microfluidic devices are necessary for theoretical validation, technological design, methodological calibration and optimization. Multiple parameters and characteristics, such as the flow rate, particle size, microchannel dimensions, , should be studied by controlled trials, which could inevitably result in extensive experiments and a heavy burden on researchers. In this work, a novel numerical model was introduced to simulate particle migration within a complicated double-layered microchannel. Using the hybrid meshing method, the proposed model achieved a significant improvement in meshing quality, and remarkably reduced the required calculation resources at the same time. The robust, efficient and resource-saving numerical model was calibrated and validated with experimental results. Based on this model, 1) the mechanism of microparticle manipulation within the microchannel was revealed; 2) the primary reason for the microparticle focusing failure was investigated; and 3) the optimal microparticle sorting strategy at different flow rates was analyzed. In experiments, the obtained optimal strategy could approach a good sorting performance with a high recovery rate and high concentration ratio in a high-throughput manner. The proposed numerical model shows great potential in mechanism investigation and functional prediction for microfluidic technologies using unconventional designs.
Topics: Lab-On-A-Chip Devices; Microfluidics; Particle Size
PubMed: 36321548
DOI: 10.1039/d2lc00822j