Bed Of Beads Research Articles

Fluidized Bed Generation of Stable Silica Nanoparticle Aerosols

A long-lasting generator of continuous silica nanoparticle aerosols based in a fluidized bed of glass beads coated with nanosized silica has been developed. The attrition resulting from the bubbling fluidized bed regime progressively detaches the silica coating from the glass beads, giving rise to a steady production of silica nanosized aerosols with median diameters from 100 to 250 nm depending on the initial size of the coating nanoparticles. Continuous aerosol production could be maintained for more than 12 h, and the nanoparticle concentration can be easily tuned in the range of 2000 to 14,000 #/cm3 by adjusting the fluidization and/or dilution flow rates. Copyright 2013 American Association for Aerosol Research

The Gyrolab™ Immunoassay System: A Platform for Automated Bioanalysis and Rapid Sample Turnaround

The Gyrolab™ workstation benefits from fully automated transfer of reagents and samples originating from a storage microplate onto a compact disc containing solid-phase microstructures composed of a 15 nl streptavidin-derivitized bead bed. This paper describes the development, full validation and use of the method in a regulated environment to measure a humanized bispecific monoclonal antibody-domain antibody (GSK-A) molecule using the Gyrolab immunoassay system in cynomolgus nonhuman primate plasma ranging from 5 to 250 µg/ml. The method was subsequently used in support of the TK portion of a regulated preclinical study in monkeys. The Gyrolab immunoassay system proved to be a viable alternative to traditional immunoassays and was used to support a regulated preclinical TK study. The speed of analysis that the Gyrolab provides was beneficial in meeting timelines to complete this project as multiple assays and repeat sample analysis could be completed in the same day.

Effect of turbulence on particle and bubble slip velocity

In multiphase systems involving a dispersed phase, such as fluidized beds, the interphase exchange of mass, heat and momentum transfer can be very different from those from a single particle, droplet or bubble system under terminal conditions. Such differences need to be correctly predicted for proper design of multiphase reactors. However, most existing methodologies still rely heavily on empirical relationships for parameters such as slip velocity, especially for systems operating under turbulent conditions where there is wide difference in the reported results.In this study the hindered settling/rising (slip) velocity of single steel particles (dPD=5–12mm) and single air bubbles (dB=1–4mm) has been measured in a solid–liquid fluidized bed of uniform size borosilicate glass beads (dP=5 and 8mm) as a function of liquid superficial velocity. The homogeneity and intensity of the turbulence within the fluidized bed has been quantified and directly related to the slip velocity of the foreign (steel or bubble) particle. It was found that the turbulence resulted in an increase in the computed drag coefficient for all of the experimental conditions investigated.

Zeolite monoliths with hierarchical designed pore network structure: Synthesis and performance

Structured adsorbents with attractive characteristics have been developed for use in CO2 capture applications. 5A zeolite monolithic structures with a hierarchical designed channel/pore system and high zeolite content approaching 92wt% were prepared. The body of the monoliths contained three different sizes of channels and pores; macro, meso and micro. The developed monoliths showed outstanding performance on CO2 separation from CO2/N2 gas mixtures compared to commercial 5A beads. The equilibrium isotherms of pure gas adsorption were collected, CO2/N2 binary gas breakthrough experiments were conducted, and pressure drop along beds packed with the monoliths or 5A beads was measured. The experimental data were simulated and the results showed that effective diffusivity was six times higher and pressure drop was 1.3times lower for 5A monolith bed compared to 5A beads bed. The high effective diffusivity, low pressure drop and comparable adsorption capacity of the prepared 5A monoliths indicate that they are ideal candidates for rapid pressure swing adsorption applications.

Fabrication of High-Quality Microfluidic Solid-Phase Chromatography Columns

Here we report a low-pressure bead packing technique for the robust integration of high-performance chromatography columns in poly(dimethylsiloxane) microfluidic devices made by multilayer soft lithography (MSL). A novel column geometry featuring micrometer-sized bypass channels along the entire length of the separation channel is used to achieve rapid packing of multiple high-quality bead bed columns in parallel with near-perfect yield. Pulse tests show that these microfluidic columns achieve exceptional reproducibility and efficiency, with measured plate counts of 1,650,000/m ± 7%, corresponding to a reduced plate height of h = 0.12 ± 7%. The combination of high-performance chromatography columns and valve-based microfluidics offers new opportunities for the integration of sample processing with preparative and analytical separations for biology and chemistry.

Effects of hydrophobicity on splash erosion of model soil particles by a single water drop impact

ABSTRACTRaindrop impact can be a major contributor to particle mobilization for soils and other granular materials. In previous work, water repellent soils, comprised of hydrophobic particles, have been shown to exhibit greater splash erosion losses under multiple drop impact. However, the underlying principle differences in splash behavior between hydrophobic and hydrophilic granular surfaces have not been studied to date. In this study the effects of particle hydrophobicity on splash behaviour by a single water drop impact were examined using high‐speed videography. Water drops (4 mm in diameter) were dropped on beds of hydrophilic and hydrophobic glass beads (sieved range: 350–400 µm), serving as model soil particles. The drop velocity on impact was 2.67 m s‐1, which corresponds to ~30% of the terminal velocity of a raindrop of similar size. The resulting impact behaviour was measured in terms of the trajectories of particles ejected from the beds and their final resting positions. The response to the impacting water drop was significantly different between hydrophilic and hydrophobic particles in terms of the distance distribution, the median distance travelled by the particles and number of ejected particles. The greater ejection distances of hydrophobic particles were mainly the result of the higher initial velocities rather than differences in ejecting angles. The higher and longer ejection trajectories for hydrophobic particles, compared with hydrophilic particles, indicate that particle hydrophobicity affects splash erosion from the initial stage of rainfall erosion before a water layer may be formed by accumulating drops. The ~10% increase in average splash distance for hydrophobic particles compared with hydrophilic particles suggests that particle hydrophobicity can result in greater net erosion rate, which would be amplified on sloping surfaces, for example, by ridges in ploughed agricultural soils or hillslopes following vegetation loss by clearing or wildfire. Copyright © 2012 John Wiley & Sons, Ltd.

Estimation of CO2 Storage Capacity in Porous Media by using X-ray Micro-CT

CO2 storage in deep geological structures is considered to be a promising method for the mitigation of CO2 emission. Estimation of the capacity of a geological reservoir is of great importance. Core level study of CO2 storage mechanism and estimation of CO2 storage capacity at laboratory scale have shown to be great helpful for CO2 geological storage studies.This paper is proposed against the background of long term and safe storage of CO2 in deep saline aquifers. Experiments for CO2 storage in glass beads bed were inducted at laboratory scale. Quartz beads were filled and packed tightly in the imaging vessel. Gaseous CO2 was then injected into the sample at a constant flow rate and saturated water was driven out. Two CO2 injection directions in the vessel were chose, namely upwards and downwards to observe the effect of buoyancy. Three dimensional scans were carried out using a micro focus X-ray CT system to investigate the distribution of CO2 in sandstone cores.Digital cores of those samples were obtained after a series of imaging processing of media filtering, rescaling, and thresholding. Then a maximal ball (MB) algorithm was used to extract the equivalent pore networks. The parameters of the pore networks, such as coordination number, size distributions and shape factors of pore and throat were computed. Gas channeling phenomena was obviously found in water saturated beads bed while CO2 was injected upwards during displacement experiments. A short breakthrough time resulted in low sweep coefficient and only about 10% of saturated water was displaced. Nevertheless, about 80% of saturated water could be driven out and displaced by CO2 while it was injected downwards. Storage capacity of residual trapping was enhanced while CO2 was injected downwards along the beads bed. X-ray micro CT was proved to be an effective technique for the investigation of CO2 storage in core sample and a novel method for the estimation of CO2 storage capacity.

A highly sensitive automated flow immunosensor based on kinetic exclusion analysis for determination of the cancer marker 8-hydroxy-2′-deoxyguanosine in urine

A highly sensitive automated flow immunosensor has been developed and validated for the measurement of the cancer marker 8-hydroxy-2′-deoxyguanosine (8-OHdG) in urine. The sensor employed the kinetic-exclusion analytical technology using the KinExA™ 3200 instrument. Various concentrations of 8-OHdG were incubated with a fixed amount of mouse anti-8-OHdG monoclonal antibody until the binding reaction reached equilibrium. These solutions were then passed rapidly over a bovine serum albumin conjugate of 8-hydroxyguanosine (8-OHG–BSA) coated onto polymethylmethacrylate beads contained in the observation cell of the KinExA instrument. The free anti-8-OHdG antibody was bound to the immobilized 8-OHG–BSA, however the unbound reagents were removed from the beads bed by flushing the system with phosphate-buffered saline. Fluorescent-labeled secondary antibody was passed rapidly over the beads bed, and the fluorescence was recorded during the flow of the secondary antibody through the beads. A calibration curve was generated by plotting the fluorescence signals that were retained on the beads as a function of 8-OHdG concentrations. The assay limit of detection was 0.05 ng ml−1 and the working range of the assay was 0.05–5 ng ml−1. The analytical recovery of urine-spiked 8-OHdG was 96.05–106.55 ± 3.00–6.40%. The precision of the sensor was satisfactory; relative standard deviation values were 3.28–4.89 and 4.40–6.89% for the intra- and inter-assay precision, respectively. The analytical performance of the proposed sensor was found to be superior to the conventional enzyme-linked immunosorbent assay for 8-OHdG. The proposed sensor is anticipated to have a great value in measurement of 8-OHdG where a more confident result is needed.

Measurement of Two Phase Flow in Porous Medium Using High-resolution Magnetic Resonance Imaging

Measurement of two phase flow in porous medium for sequestration was carried out using high-resolution magnetic resonance imaging (MRI) technique. The porous medium was a packed bed of glass beads. Spin echo multi sequence was used to measure the distribution of CO2 and water in the porous medium. The intensity images show that the fluid distribution is non-uniform due to its viscosity and pore structure of porous medium. The velocity distribution of fluids is calculated from the saturation of water and porosity of porous medium. The experimental results show that fluid velocities vary with time and position. The capillary dispersion rate donated the effects of capillary, which was largest at water saturations of 0.45. The displacement process is different between in BZ-02 and BZ-2. The final water residual saturation depends on permeability and porosity.

Magnetic Resonance Imaging of CO2/Water Two Phase Flow in Porous Media

Measurement of CO2/water two phase fluids flow in the porous media under sequestration conditions by Magnetic Resonance Imaging (MRI) technique was studied in this paper. The porous media was formed from a packed bed of glass beads. A spin echo sequence was used to measure the distribution of CO2 and water after the CO2 was injected into the porous media containing water. The displacement front was different with the packed beds. For displacement experiments in BZ-02 and BZ-2, three stages were obtained. The CO2 channeling or fingering phenomena were obviously found. Also breakthrough time was different in BZ-02 and BZ-2. The final water residual saturation depended on permeability. The larger the permeability was, the wider the front is. The distribution of CO2 was uniform in the packed beds with larger glass beads. Breakthrough occurred early. In other packed bed, the breakthrough occurred latter. The front was affected by pore porosity and permeability. The residual saturation was calculated from the intensity images. The residual saturation was inverse proportion to larger permeability, then direct proportion to flow rate.

Augmented Topological Descriptors of Pore Networks for Material Science

One potential solution to reduce the concentration of carbon dioxide in the atmosphere is the geologic storage of captured CO2 in underground rock formations, also known as carbon sequestration. There is ongoing research to guarantee that this process is both efficient and safe. We describe tools that provide measurements of media porosity, and permeability estimates, including visualization of pore structures. Existing standard algorithms make limited use of geometric information in calculating permeability of complex microstructures. This quantity is important for the analysis of biomineralization, a subsurface process that can affect physical properties of porous media. This paper introduces geometric and topological descriptors that enhance the estimation of material permeability. Our analysis framework includes the processing of experimental data, segmentation, and feature extraction and making novel use of multiscale topological analysis to quantify maximum flow through porous networks. We illustrate our results using synchrotron-based X-ray computed microtomography of glass beads during biomineralization. We also benchmark the proposed algorithms using simulated data sets modeling jammed packed bead beds of a monodispersive material.

Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Semicontinuous Operation Mode

Solid supported evaporation (SSE) is a simple, nonselective method for isolating nonvolatile compounds from a solution. The solution is put in contact with porous polymer beads onto which the compound deposits upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety, thermal decomposition, and solid handling, as the loaded beads form a free-flowing granular material that is easily recovered. In this paper, SSE in a semicontinuous operating mode is investigated where the solution is continuously fed to (respectively sprayed over) an agitated bed of dry beads put under vacuum. It is found that under conditions where the solvent evaporation rate is high with respect to the feed rate, high bead loadings can be achieved before extensive sticking of beads and compound to the vessel walls occurs. The type of compound and solvent had little influence on the process performance, and, in cases where this was explored, the bead loading was found to be homogeneous. Based on a balance equation for the solvent fed to the system, a model is developed that results in a simple scale up criterion. The latter was successfully applied for transferring SSE from lab to the kilo lab scale.

Isolation of Pharmaceutical Intermediates through Solid Supported Evaporation. Batch Operation Mode

Solid supported evaporation (SSE) is a simple method to isolate dissolved compounds as a solid material. The solution is put in contact with granular porous polymer beads onto which the compounds deposit upon evaporation of the solvent. This brings some advantages over direct evaporation to dryness in terms of safety and handling of the solids. In this paper, SSE in batch mode is explored where the solution is added to the polymer beads at once, i.e. opposite to the semicontinuous mode where the solution is sprayed over a bed of beads. A number of compounds varying widely in their physical and chemical properties is studied. It is found that all compounds could be loaded onto the beads; however, the loading capacity depends on the properties of the compound and in general was lower than in the semicontinuous operating mode studied in an accompanying paper. For highly soluble compounds, higher loadings could be achieved when solvent evaporation was slow. In cases where tested, bead loading was found to be homogeneous within a batch. Recovery of compound from loaded beads was achieved by dispersing the beads in a solvent and washing of the filter cake after filtration. A relatively large amount of solvent is required to achieve full recovery.

Optical measurement uncertainties due to refractive index mismatch for flow in porous media

Application of optical techniques such as PIV, PTV, and LDA for velocity field estimation in porous media requires matching of refractive indices of the liquid phase to that of the solid matrix, including the channel walls. The methods most commonly employed to match the refractive indices have been to maximize the transmitted intensity through the bed or to rely on direct refractometer measurements of the indices of the two phases. Mismatch of refractive indices leads to error in estimation of particle position, e PD, due to refraction at solid–liquid interfaces. Analytical ray tracing applied to a model of solid beads placed randomly along the optical path is used to estimate e PD. The model, after validating against experimental results, is used to generate expression for e PD as a function of refractive index mismatch for a range of bead diameters, bed widths, bed porosity, and optical magnification. The estimate of e PD, which is found to be unbiased, is connected to errors in PIV measurement using the central limit theorem. Mismatch in refractive indices can also lead to reduction in particle density, N s, detected light flux, J, and degrade the particle image. The model, verified through experiments, is used to predict the reduction in N s and J, where it is found that particle defocusing caused by spherical beads in refractive index mismatched porous bed is the primary contributor to reductions of N s and J. In addition, the magnitude of e PD is determined for the use of fluorescent dye emission for particle detection due to wavelength-dependent index of refraction.

The collapse of a cylindrical cavity in a granular medium

A cylindrical cavity in a noncohesive granular medium will collapse under gravity, leaving a circular crater in the surface of the material. We study this process through experiment and numerical modeling. Experimentally, we determine the shape and dimensions of craters formed by the collapse of a cylindrical cavity in a bed of small glass beads. Using a depth-averaged continuum model with cylindrical symmetry, we calculate the shape of the free surface both during and after the collapse. We use the model to study the energetics of the collapse process and investigate the dependence of the final crater on the initial shape of the cavity and the initial velocity field. While the shapes of the final craters are not identical in model and experiment, we find good qualitative agreement in aspect ratio and slope.

Mechanical Behavior of Water Deionizing Granular Material Bed for Space Life Support Systems

AbstractOne of the most critical components in the oxygen-generation and water-processing assemblies for human habitation in space is the deionizing (DI) bed—a packed bed of ion-exchange resin beads—that purifies water. The DI bed shrinks during the course of its operation, and therefore, for the bed to work satisfactorily, it must be kept properly compressed. To understand the force-transferring mechanism along the bed, sets of experimental programs were developed and conducted on the individual particles and bed samples of a DI granular material, Amberlite IRN-78. The presence of water reduced the load-bearing capacity of the individual particles, because most of the wet (water submerged) particles tested failed under relatively small crushing force, whereas the dry particles withstood a much higher load. The particle crushing force was found to be closely represented by normal and Weibull distributions. The DI material bed has a relatively small internal friction angle (shear strength). The lateral pre...

Capillary Fracturing in Granular Media

We study the displacement of immiscible fluids in deformable, noncohesive granular media. Experimentally, we inject air into a thin bed of water-saturated glass beads and observe the invasion morphology. The control parameters are the injection rate, the bead size, and the confining stress. We identify three invasion regimes: capillary fingering, viscous fingering, and "capillary fracturing," where capillary forces overcome frictional resistance and induce the opening of conduits. We derive two dimensionless numbers that govern the transition among the different regimes: a modified capillary number and a fracturing number. The experiments and analysis predict the emergence of fracturing in fine-grained media under low confining stress, a phenomenon that likely plays a fundamental role in many natural processes such as primary oil migration, methane venting from lake sediments, and the formation of desiccation cracks.

Measurement of fluid flow in pipe and porous media by high-resolution magnetic resonance imaging

The objective of this study is to understand the process of fluid flow in pipe and porous media with different pore structures. High-resolution Magnetic Resonance Imaging (MRI) technique was used to visualize the pore structure and measure fluid flow. The porous media was formed by packed bed of glass beads. Flow measurement was carried out by a modified spin echo sequence. The results show that the velocity distribution in pipe is annular and the linear relation between MRI velocity and actual velocity is found in pipe flow measurement. The flow distribution in porous media is rather heterogeneous, and it is consistent with heterogeneous pore structure. The flow through pores with the high volume flow rate is determined largely by geometrical effects such as pore size and cross-sectional area.

Properties of lead deposits in cell walls of radish (Raphanus sativus) roots

Various mechanisms are involved in detoxification of heavy metals such as lead (Pb) in plant cells. Most of the Pb taken up by plants accumulates in their roots. However, the detailed properties of Pb complexes in roots remain unclear. We have investigated the properties of Pb deposits in root cell walls of radish (Raphanus sativus L.) seedlings grown on glass beads bed containing Pb pellets, which are the source of Pb-contamination in shooting range soils. Pb deposits were tightly bound to cell walls. Cell wall fragments containing about 50,000ppm Pb were prepared from the roots. After extracting Pb from the cell wall fragments using HCl, Pb ions were recombined with the Pb-extracted cell wall fragments in a solution containing Pb acetate. When the cell wall fragments were treated with pectinase (E.C. 3.2.1.15) and were chemically modified with 1-ethyl-3-dimethylamino-propylcarboimide, the Pb-rebinding ability of the treated cell wall fragments decreased. When acid-treated cell wall fragments were incubated in a solution containing Pb(2+) and excess amounts of a chelating agent, Pb recombined with the cell wall fragments were measured to estimate the affinity between Pb(2+) and the cell wall fragments. Our data show that Pb(2+) binds to carboxyl groups of cell walls. The source of the carboxyl groups is suggested to be pectic compounds. A stability constant of the Pb-cell wall complex was estimated to be about 10(8). The role of root cell walls in the mechanism underlying heavy metal tolerance was discussed.

Abstract 4070: Development of circulating tumor cell capture from whole blood using beads and microfluidics

Abstract Capture of circulating tumor cells (CTCs) from blood shows promise as a relatively non-invasive screen for early stage metastasis, treatment efficacy, and disease progression. Capture rates exceeding 80% of CTCs from whole blood have been demonstrated in microfluidic chips, with good specificity and throughput at approximately 1 mL/h. The most common approach is to design a high surface-area microdevice and functionalize the surface with anti-EpCAM to capture epithelial tumor cells. As an alternative to this monolithic design, we have developed a CTC capture strategy based on functionalized beads for analyzing small numbers of CTCs from whole blood. Beads for the device were commercially available in a variety of sizes and surface chemistries or could be synthesized by multiple techniques. We utilized avidin-functionalized beads to enable capture using biotinylated antibodies (Ab) for surface-expressed proteins. Critically, batches of beads were assayed in bulk and then used for multiple experiments, avoiding characterization of each device. Beads packed well as columns in microdevices, ensuring multiple surface interactions as cells flow through. We simulated CTC-carrying blood by spiking human breast cancer adenocarcinoma (MFC7) cells (prestained with a membrane dye) into whole human blood between 1000 cells/mL and 105 cells/mL. Samples were delivered through the packed bed of beads using a syringe pump. We found that adding Ab to whole blood samples provided superior results to pre-coating the beads with the Ab. This approach was tested for multiple bead compositions and enabled (1) use of less Ab, and (2) higher capture rates, perhaps due to the rapid biotin:avidin binding. Significant cell capture was observed when as few as 300 cells were introduced into the device. At all cell densities, the majority of captured cells bound to the first few rows of beads, with decreasing capture frequency along the length of the column. Quantification of the absolute number of captured cells was a challenge in whole blood samples due to the large numbers of cells captured and optical distortion effects. We estimated capture by observing the initial capture rates of the same cells at the same densities in serum-spiked phosphate-buffered saline. This indicated that during the initial stages of flow, over 80% of the Ab-labeled cells were selectively captured. We conclude that the device can handle higher flowrates and still capture the majority of labeled cells. We are exploring the feasibility of this approach for capturing even lower CTC concentrations (1 cell/ml to 100 cells/mL range). Our bead/microfluidic approach simplifies CTC capture by enabling bulk surface functionalization for multiple experiments and allowing commercial sourcing of all functional elements. Further, there is flexibility in antibody selection, such that alternate Ab could rapidly be considered. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4070. doi:1538-7445.AM2012-4070