The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Samir Mitragotri - One of the best experts on this subject based on the ideXlab platform.
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coupled influences of Particle Shape surface property and flow hydrodynamics on rod Shaped colloid transport in porous media
Journal of Colloid and Interface Science, 2020Co-Authors: Carl H Bolster, William P Johnson, Eddy Pazmino, Kathryn M Camacho, Aaron C Anselmo, Samir MitragotriAbstract:Abstract Hypothesis Natural or engineered colloidal Particles are often non-spherical in Shape. In contrast to the widely-used “homogeneous sphere” assumption, the non-spherical Particle Shape is expected to alter Particle–fluid-surface interactions, which in turn affect Particle transport and retention. Experiments and Simulations Polystyrene microspheres were stretched to rod-Shaped Particles of two aspect ratios (2:1, 6:1). The transport and retention behaviors of rods versus spheres were investigated in packed quartz sand columns and impinging jet systems. In parallel, a 3D trajectory model was employed to simulate Particle translation and rotation, and to elucidate the role and underlying mechanisms of Particle Shape impact on transport. Findings Rods were observed to undergo rotating and tumbling motions in response to fluid shear from experiments and simulations. However, no distinct retention trends between rods and spheres were observed from column studies, despite BSA-coating on Particles, Fe-coating on sand or velocity change. This was primarily due to the super-hydrophobic nature of colloid surfaces acquired from stretching process, which in hydrophilic sand columns, dominated Particle–surface charge interactions. Simulations using colloids with randomly distributed charge patches qualitatively produced the observed insensitivity in retention respecting aspect ratio under low charge coverage (
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Particle Shape enhances specificity of antibody displaying nanoParticles
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Sutapa Barua, Jinwook Yoo, Poornima Kolhar, Aditya Wakankar, Yatin R Gokarn, Samir MitragotriAbstract:Monoclonal antibodies are used in numerous therapeutic and diagnostic applications; however, their efficacy is contingent on specificity and avidity. Here, we show that presentation of antibodies on the surface of nonspherical Particles enhances antibody specificity as well as avidity toward their targets. Using spherical, rod-, and disk-Shaped polystyrene nano- and microParticles and trastuzumab as the targeting antibody, we studied specific and nonspecific uptake in three breast cancer cell lines: BT-474, SK-BR-3, and MDA-MB-231. Rods exhibited higher specific uptake and lower nonspecific uptake in all cells compared with spheres. This surprising interplay between Particle Shape and antibodies originates from the unique role of Shape in determining binding and unbinding of Particles to cell surface. In addition to exhibiting higher binding and internalization, trastuzumab-coated rods also exhibited greater inhibition of BT-474 breast cancer cell growth in vitro to a level that could not be attained by soluble forms of the antibody. The effect of trastuzumab-coated rods on cells was enhanced further by replacing polystyrene Particles with pure chemotherapeutic drug nanoParticles of comparable dimensions made from camptothecin. Trastuzumab-coated camptothecin nanoParticles inhibited cell growth at a dose 1,000-fold lower than that required for comparable inhibition of growth using soluble trastuzumab and 10-fold lower than that using BSA-coated camptothecin. These results open unique opportunities for particulate forms of antibodies in therapeutics and diagnostics.
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polymer Particle Shape independently influences binding and internalization by macrophages
Journal of Controlled Release, 2010Co-Authors: Gaurav Sharma, Samir Mitragotri, David T Valenta, Yoav Altman, Sheryl Harvey, Hui Xie, Jeffrey W SmithAbstract:The interaction of macrophages with micro and nanoParticles (MNPs) is important because these cells clear Particles from the circulation, and because they are potential therapeutic targets in inflammatory conditions, atherosclerosis and cancer. Therefore, an understanding of the features of MNPs that influence their interaction with macrophages may allow optimization of their properties for enhanced drug delivery. In this study, we show that Particle Shape impacts phagocytosis by macrophages, and more importantly, that Particle Shape and size separately impact attachment and internalization. The study provides a methodology for further exploring how Particle Shape can be controlled to achieve desired attachment and internalization. The results of the study also give mechanistic guidance on how Particle Shape can be manipulated to design drug carriers to evade macrophages, or alternatively to target macrophages.
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Particle Shape a new design parameter for micro and nanoscale drug delivery carriers
Journal of Controlled Release, 2007Co-Authors: Julie A Champion, Yogesh K Katare, Samir MitragotriAbstract:Encapsulation of therapeutic agents in polymer Particles has been successfully used in the development of new drug carriers. A number of design parameters that govern the functional behavior of carriers, including the choice of polymer, Particle size and surface chemistry, have been tuned to optimize their performance in vivo. However, Particle Shape, which may also have a strong impact on carrier performance, has not been thoroughly investigated. This is perhaps due to the limited availability of techniques to produce non-spherical polymer Particles. In recent years, a number of reports have emerged to directly address this bottleneck and initial studies have indeed confirmed that Particle Shape can significantly impact the performance of polymer drug carriers. This article provides a review of this field with respect to methods of Particle preparation and the role of Particle Shape in drug delivery.
Paul W. Cleary - One of the best experts on this subject based on the ideXlab platform.
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the influence of Particle Shape on flow modes in pneumatic conveying
Chemical Engineering Science, 2011Co-Authors: James E Hilton, Paul W. ClearyAbstract:Abstract The transportation of Particles along pipes or ducts using an imposed gas flow is known as pneumatic conveying. The type of granular flow in such systems is strongly dependent on the imposed gas flow rate, and can be categorised by a distinct set of modes. These modes range from dilute flow, where the grains are entirely suspended in the gas, to moving dunes and slug flow, in which the bore of the pipe is blocked by a slow moving plug of material. Understanding the transitions between these modes is critical to the design and application of pneumatic conveying systems. Particle Shape is a crucial factor in systems with gas–grain interactions but has so far been overlooked in models of pneumatic conveying. We carry out a series of simulations using the discrete element method coupled to gas flow and show that Particle Shape is critical to the transition between different flow modes. Particles which are spherical, or nearly spherical, transition to slug flow at high gas flow rates, whereas non-spherical Particles transition instead to dilute flow. We show the lower voidage fraction in beds of non-spherical Particles is crucial to explaining this behaviour.
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fundamental relations between Particle Shape and the properties of granular packings
POWDERS AND GRAINS 2009: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON MICROMECHANICS OF GRANULAR MEDIA, 2009Co-Authors: G Delaney, Paul W. ClearyAbstract:Granular matter, in its densely random packed state, is commonly found in numerous physical, biological and industrial systems. Improving our understanding of such packings has wide spread applicability, from simple issues of grain transportation, to large geological events such as landslides. We have studied the properties of dense jammed packings for an extensive range of three‐dimensional Particle Shapes. We employ super‐quadric Particles, which allow us to vary the Particle’s aspect ratio, surface curvature and blockiness. We explore how the individual Particle Shape affects both the macroscopic and the local configurational properties of the system, smoothly transitioning from spherical Particles possessing only translational degrees of freedom to large aspect ratio non‐spherical grains where rotational degrees of freedom are highly important. Finally, we demonstrate how a fundamental understanding of the role of Particle Shape in granular packings allows us to implement better communition models in DEM simulations, where Particle breakage occurs and generates packings of fragments with realistic size and Shape distributions.
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The effect of Particle Shape on simple shear flows
Powder Technology, 2008Co-Authors: Paul W. ClearyAbstract:Simple shear flows, (without gravity force and implemented using periodic boundary conditions or in Couette flow configurations with gravity) have been the subject of study using DEM simulation for more than two decades. Earlier studies explored the effect of attributes such as shear rate, Particle size and domain scale on the distribution of the Particles in the flow, velocity profiles and the stress distributions. These studies were conducted using simple Shapes for the Particles such as spheres. In recent years, the importance of Particle Shape on flow has been recognized in a range of industrial application including mixing, comminution, hopper discharge and chute flows. In this paper, we return to the simple shear flows and quantitatively explore the effect of Particle Shape on velocity, volume fraction, granular temperature and stress distributions across the channel. Particle Shape is found to sharply increase the strength of the material making it stronger and harder to shear. The generation of Particle spin throughout the flow of non-circular Particles leads to high granular temperatures, dilative pressures and lower solid fractions in the core of the flow. For aspect ratios between 0.6 and 0.5, a transition in the effective behaviour of the wall boundary conditions is identified. The connections of Shape to spin, to granular temperature, to bulk flow changes are elaborated. ?? 2007.
Yan Jin - One of the best experts on this subject based on the ideXlab platform.
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effect of Particle Shape on colloid retention and release in saturated porous media
Journal of Environmental Quality, 2010Co-Authors: Qiang Liu, Volha Lazouskaya, Yan JinAbstract:Colloidal Particles of environmental concern often have nonspherical Shapes. However, theories and models such as the classical filtration theory have been developed based on the behavior of spherical Particles. This study examined the effect of Particle Shape on colloid retention (e.g., attachment and straining) and release in saturated porous media. Two- and three-step transport experiments were conducted in water-saturated glass bead columns using colloids dispersed in deionized water and an electrolyte solution. The Particles used in the experiments were carboxylate-modified latex colloids of spherical (500 nm diam.) and rod (aspect ratio, 7.0) Shapes. The rod-like Particles were prepared by stretching the spherical Particles. Analysis of the colloid breakthrough curves indicates that Particle Shape affected transport behavior, but retention did not increase with increasing aspect ratio. Retention of the spherical Particles occurred mainly in the secondary energy minimum, whereas retention of rod-like Particles occurred in primary and secondary energy minima. There was less straining of rod-like Particles compared with spherical ones, indicating that the minor axis was the critical dimension controlling the process. Release of spherical Particles on elution was instantaneous, whereas release of rod-like Particles was rate limited, giving rise to long tails, implying an orientation effect for rod-like colloids. The results suggest that the differences in electrostatic properties and Shape contributed to the observed different retention and release behaviors of the two colloids.
Barry Lehane - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Overconsolidation and Particle Shape on the CPT End Resistance of Granular Soils
Springer Series in Geomechanics and Geoengineering, 2015Co-Authors: Wei Xiang, Barry LehaneAbstract:This paper examines the effect of overconsolidation and Particle Shape on the end resistance (qc) measured in a series of centrifuge Cone Penetration Tests (CPTs) conducted in three uniformly graded silica materials with distinct Particle Shape. For each soil type, the end resistances were measured for both normally and overconsolidated soil samples at centrifuge g-level of 100g. All samples were prepared and tested at two different relative density, and the over-consolidated samples were achieved by reducing the centrifuge g-level from 200g to 100g (with over-consolidation ratio, OCR=2). At a given relative density and stress level, the striking dependency of the CPTs end resistance (qc) on the Particle Shape can be observed. For a particular material, a tendency for qc value to increase with the OCR was in evidence. An approach based on the spherical cavity expansion method was proposed to predict the qc value of each soil, and particularly to investigate how the OCR and Particle Shape influence on the end bearing resistance. It was found that the predicted qc are shown to match the measured data well, and the end bearing resistances were significantly affected by the critical friction angle and horizontal stress, which were closely related to the Particle Shape and overconsolidation ratio.
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the influence of Particle Shape on the centrifuge cone penetration test cpt end resistance in uniformly graded granular soils
Geotechnique, 2012Co-Authors: Barry LehaneAbstract:The paper examines the effect of Particle Shape on the end resistance measured in a series of centrifuge cone penetration tests (CPTs) conducted in four uniformly graded silica materials, each with its own distinctive Particle-Shape characteristic. The CPTs were performed at three different centrifuge g-levels and two different relative densities. A parallel series of shear-box tests allowed determination of the materials' shearing characteristics, and led to the development of an expression for peak friction angle that incorporates the influence of Particle Shape. A simple approach to predict the CPT end resistance employing this expression is shown to match the measured centrifuge CPT data and hence assist with quantification of the relative importance of Particle Shape on the CPT end resistance.
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the influence of Particle Shape on the centrifuge cone penetration test cpt end resistance in uniformly graded granular soils
Geotechnique, 2012Co-Authors: Qingbing Liu, Barry LehaneAbstract:The paper examines the effect of Particle Shape on the end resistance measured in a series of centrifuge cone penetration tests (CPTs) conducted in four uniformly graded silica materials, each with...
Qiang Liu - One of the best experts on this subject based on the ideXlab platform.
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effect of Particle Shape on colloid retention and release in saturated porous media
Journal of Environmental Quality, 2010Co-Authors: Qiang Liu, Volha Lazouskaya, Yan JinAbstract:Colloidal Particles of environmental concern often have nonspherical Shapes. However, theories and models such as the classical filtration theory have been developed based on the behavior of spherical Particles. This study examined the effect of Particle Shape on colloid retention (e.g., attachment and straining) and release in saturated porous media. Two- and three-step transport experiments were conducted in water-saturated glass bead columns using colloids dispersed in deionized water and an electrolyte solution. The Particles used in the experiments were carboxylate-modified latex colloids of spherical (500 nm diam.) and rod (aspect ratio, 7.0) Shapes. The rod-like Particles were prepared by stretching the spherical Particles. Analysis of the colloid breakthrough curves indicates that Particle Shape affected transport behavior, but retention did not increase with increasing aspect ratio. Retention of the spherical Particles occurred mainly in the secondary energy minimum, whereas retention of rod-like Particles occurred in primary and secondary energy minima. There was less straining of rod-like Particles compared with spherical ones, indicating that the minor axis was the critical dimension controlling the process. Release of spherical Particles on elution was instantaneous, whereas release of rod-like Particles was rate limited, giving rise to long tails, implying an orientation effect for rod-like colloids. The results suggest that the differences in electrostatic properties and Shape contributed to the observed different retention and release behaviors of the two colloids.
