Bead Column Research Articles

Oxidation of polycyclic aromatic hydrocarbons by ozone in the presence of sand

A series of soil slurry experiments was performed to investigate the characteristics of PAHs removal by ozone in various conditions. Gaseous ozone was bottled into the aqueous phase in the presence of soil contaminated by PAHs. The effects of soil media, OH radical scavengers, ozone dosage, and humic acid were examined at the given experimental conditions. There exists a substantial difference in the removal of PAH according to the types of soil media tested. Baked sand showed the highest removal efficiency compared to the others. The descending order of removal rate was: BS > S > GB. This is considered to be due to the OH radical effect produced by catalytic reactions of ozone with the reactive site on the and. This is qualitatively proved by the experiment of scavenging OH radicals using tert-butanol. The comparison of half-lives of ozone in sand and glass bead columns further supports this hypothesis. It was found that about 22% of enhancement of phenanthrene destruction was accomplished by OH radicals produced by the catalytic ozone decomposition. The rate of ozone consumption for the phenanthrene oxidation was obtained as 1.88 mg/mgO3/min.

Characterization of blood group ABO(H)-active gangliosides in type AB erythrocytes and structural analysis of type A-active ganglioside variants in type A human erythrocytes

Several monosialogangliosides containing the type A-active epitope have been detected in type A erythrocytes on immunological analysis with a monoclonal antibody, and three of them were purified by repeated silica bead column chromatography and by scraping from the TLC plate. Two of these A-active gangliosides were characterized by methylation analysis by GC/MS, negative SIMS, MALDI-TOF/MS, proton nuclear magnetic resonance spectroscopy, and immunological assays, and their structures were concluded to be as follows. A-active ganglioside I: A-active ganglioside II: The reactivity of the purified gangliosides to the anti-A monoclonal antibodies (mAbs) exhibited enhancement after removal of the sialic acid. Therefore, the sialic residue has been shown to inhibit the binding to the terminal A-active epitope through the formation of an immune complex. To confirm the presence of A- (including S-A-I, -II and -III) and B-active gangliosides, the reactivity of anti-A and -B mAbs were investigated using total gangliosides from type A, -B and -AB erythrocytes on TLC plate. The results were that the gangliosides from types A and AB showed positive reaction to anti-A mAbs, whereas in the anti-B mAbs binding the gangliosides from types B and AB were positive. Thus, it revealed that A-active gangliosides were present in type A and -AB, and B-active gangliosides in types B and AB. As there was no difference in respective gangliosides on type AB erythrocytes of 22 individuals, both A- and B-active gangliosides are equally present in type AB erythrocytes. The biological significance of these A- and B-active ganglioside variants remains vague at present. As these molecules exhibit different reactivities to the anti-A mAbs, it is very likely that they can regulate the antigenicity of the A-epitope on the cell surface.

The role of anti-Galalpha1-3Gal antibodies in acute vascular rejection and accommodation of xenografts.

A major impediment to the transplanting of porcine organs into humans is the susceptibility of porcine organs to acute vascular rejection, which can destroy a vascularized xenograft over a period of hours to days. Acute vascular rejection of porcine-to-primate xenografts is thought to be triggered by binding of xenoreactive antibodies to the graft. We tested whether antibodies, binding to Galalpha1-3Gal epitopes in porcine tissue, initiate this phenomenon. Specific depletion of anti-Galalpha1-3Gal antibodies from the blood of baboons, using extracorporeal perfusion of separated plasma through columns of Sepharose beads covalently linked to the antigenic trisaccharide, Galalpha1-3Galbeta1-4GlcAc, averted the development of acute vascular rejection in porcine organs transgenic for human decay-accelerating factor and CD59. More importantly, after immunodepletion was stopped and Gala1-3Gal antibodies were allowed to return, these same organs continued to function and remained pathologically normal and thus seemed to achieve a state of accommodation. These results demonstrate that anti-Galalpha1-3Gal antibodies cause acute vascular rejection and suggest that depletion of these antibodies leads to accommodation of the donor cardiac xenograft and could supply an important model for additional study.

Convection‐enhanced mass transfer in aggregated beads for gel chromatography

AbstractConvection‐enhanced mass transfer in aggregated κ‐carrageenan beads was assessed using experimental and mathematical modeling studies. Aggregated beads, prepared from subsidiary beads in a fluidized bed, were employed for gel chromatography of proteins. The efficiency of a chromatography column was measured by the plate height. The plate height of the aggregated beads was much lower than that of conventional carrageenan beads of the same size. This was attributed to intraparticle convection, which occurred even at relatively low flow rates due to the large intraparticle channels resulting from the low degree of aggregation. A general equation for predicting the reduced plate height was modified by using an apparent diffusivity in order to incorporate intraparticle convection. The modified equation was in good agreement with experimental data. The protein productivity of an aggregated bead column (mg/h/mL column) was estimated to be six times higher than that of a conventional column.

Polymyxin B binds to anandamide and inhibits its cytotoxic effect

Anandamide (ANA), an endogenous cannabinoid, can be generated by activated macrophages during endotoxin shock and is thought to be a paracrine contributor to hypotension. We discovered that ANA in saline/ethanol solution and in serum was efficiently adsorbed in a polymyxin B (PMB)-immobilized beads column and eluted with ethanol. We confirmed the direct binding of PMB to ANA by using surface plasmon resonance. The adsorption of ANA by PMB may abolish the diverse effects of ANA such as hypotension, immunosuppression, and cytotoxicity, and may suggest a new therapeutic strategy for endotoxin shock.

Comparison of Breakthrough Performance Using Dye-Affinity Membrane Disks and Gel Bead Columns

The breakthrough curve performance of lysozyme and bovine serum albumin to immobilized Cibacron Blue 3GA using different solid supports such as gel beads and membrane disks was investigated in this work. The effects of flow rate and different module designs were also studied. Variation in the flow rate was found to be insignificant for the column process in both nonadsorption and single-protein experiments, but it affected the elution peak height for membrane disks. The peak height decreased with increasing flow rate. As for the effect of different designs, a long column and a wide membrane stack induced a broader breakthrough performance. The performance varied with different solid supports in two-protein experiments. Competitive adsorption occurred for a gel bead column, and the breakthrough curve performance resembled the prediction of combining local equilibrium theory and the extra module effect. The affinity strength to the gel bead support is in the order lysozyme BSA dimer BSA monomer. As for membrane performance, two BSA solutes did not adsorb onto membranes, so a simple separation of lysozyme from BSA, instead of displacement phenomena, was observed.

A Fluorescent Biosensor for Detection of Zearalenone

ABSTRACT A fluorescent biosensor was developed on a KinExATM flow spectrofluorimeter for the near real-time detection of soluble zeaalenone. Briefly, solutions of zearalenone and a monoclonal antibody directed against a protein conjugate of zearalenone, were incubated for thirty minutes to permit equilibrium binding to occur. The reaction mixture was then passed over a packed column of small beads (98 μm) whose surfaces were coated with a covalent conjugate of zearalenone and bovine serum albumin (BSA). Following a short wash with buffer to remove excess unbound primary reagents, the packed beads were subjected to a brief contact with fluorescein isothiocyanate-labeled polyclonal secondary antibody directed against the primary monoclonal, once again followed by a short wash. As this assay depends on the ability of soluble antigen to compete with immobilized antigen, increasing concentrations of zearalenone result in decreasing fluorescence observed on the bead pack. This assay is rapid (≅ 60 minutes) and can be adapted to various other analytes of interest.

Extraction of lipopolysaccharides from water using a thermoresponsive polymer.

Lipopolysaccharides(LPS)were successfully extracted from water by polymer-mediated extraction based on the thermoresponsive precipitation of a water-soluble polymer:poly(N-isopropylacrylamide)[PNIPAAm]in aqueous solutions.LPS, having a hydrophobic lipid moiety and hydrophilic polysaccharides, were less extractive than lipids, but well concentrated to the small volume of the aggregated polymer precipitates(polymer phase).In contrast, hydrophilic compounds, including saccharides, urea, creatinine, serum proteins, and inorganic ions, hardly incorporated into the polymer phase.Collected LPS could be recovered to a chitosan bead column by passing through an aqueous PNIPAAm solution of LPS.

Serum amyloid A protein generates pre beta 1 high-density lipoprotein from alpha-migrating high-density lipoprotein.

Serum amyloid A protein (SAA), an acute-phase reactant in reactive amyloidosis, has high affinity for high-density lipoprotein (HDL). When SAA is added to HDL, SAA displaces apolipoprotein A-I (apoA-I) and phospholipid from the HDL particles. These dissociated components may form prebeta1-HDL because free apoA-I can associate with phospholipid to become a lipoprotein having prebeta mobility. To determine whether SAA generates prebeta1-HDL from alpha-migrating HDL, we investigated the effects of recombinant SAA on HDL subfraction concentration using nondenaturing two-dimensional gradient gel electrophoresis. When we added SAA (0.5 mg/mL) to plasma, the prebeta1-HDL concentration increased by 164% (from 4.7% +/- 1.3% to 12.4% +/- 3.2% of apoA-I, p < 0.005). The increase in prebeta1-HDL was proportional to the dose of SAA. When we added SAA to a column of Sepharose beads coupled to the isolated HDL (alpha-migrating HDL), prebeta1-HDL was dissociated from the column together with the SAA-associated HDL. In summary, we demonstrate that SAA generates prebeta1-HDL from alpha-migrating HDL. We speculate that SAA-mediated HDL remodeling may take place in inflammation.

Selective loss of progenitor subsets following clinical CD34+ cell enrichment by magnetic field, magnetic beads or chromatography separation.

In this preclinical evaluation we have compared the efficacy of three clinical CD34+enrichment procedures with respect to purity, yield and recovery, as well as risk of selective loss of CD34+ lineage-specific subsets. The three devices work by different principles and have several different manipulation steps: The magnetic field separator uses paramagnetic iron-dextran particles; the magnetic microbead selection is based on the advantage of a large surface area for immobilisation of the monoclonal antibody within a very small volume; the original immunoabsorption technique is based on the use of biotinylated antibody applied to a column of avidin-coated sephadex beads. The results of this evaluation gave a median purity 96% (88-98%), 86% (62-97%), and 49% (18-85%), and median yield of 65% (54-100%), 40% (21-74%), and 30% (8-55%), respectively. Subset analysis recognised a selective loss of CD34+/61+ after enrichment, most likely due to class I-II antibodies used for the enrichment step or, alternatively, nonspecific binding of megakaryocytic progenitors. Tumour cell spiking experiments on a clinical scale documented an expected 2-4 log reduction resulting in a number of potentially malignant cells in the CD34 enriched product. Our data support four major conclusions: First, that magnetic field separation is superior to magnetic beads and chromatography selection, mainly due to the risk of cell loss and insufficient recovery with the two latter methods. Second, that late differentiated progenitors with CD34 class III epitopes present are lost during the enrichment procedures. The third major conclusion is that chromatography selection results in a selective loss of CD34bright cells, which are most likely uncommitted early progenitors. This was an unexpected finding which may be a consequence of an imbalance between the strong forces between biotin-avidin and insufficient physical manipulation for CD34+ cell release. Finally, the data document that CD34 selection alone is an inappropriate way to eliminate tumour cells due to the uncontrolled variables and the inconsistent outcome. The only products which can be expected to be purged free of tumour cells are the ones with very minimal (<10-5) contamination in the starting products, ie products documented tumour free with the most sensitive techniques for quantitation. If this is not the case, the optimal purging strategy may be a two-step procedure including CD34 selection and subsequent depletion of the tumour cells in question.

The major acidic glycolipids from the kidney of the Pacific salmon (Oncorhynchus keta): characterization of a novel ganglioside, fucosyl-N-acetylgalactosaminyl-GM1.

Two fractions of a major ganglioside from the kidney of the pacific salmon, Oncorhynchus keta, were eluted from a DEAE-Sephadex column in the monosialosyl fraction. The faster moving ganglioside (X1) on TLC was separated from the slower moving one (X2) by HPLC using a silica beads column. By methylation analysis, chemical and enzymatic degradation, reaction with monoclonal antibodies, LSIMS, and (1)H-NMR spectroscopy, X1 was determined to be a monosialosyl ganglioside belonging to the ganglio-series with a unique Fucalpha1-3GalNAc linkage at the nonreducing terminal: Fucalpha1-3GalNAcbeta1-3Galbeta1-3GalNAcbeta1-4[ NeuAcalpha2-3]Galbeta 1-4Glcbeta1-1Cer. Analysis of the lipophilic moiety indicated predominance of 24:1 fatty acid in combination with sphingenine. X2 was found to have a glycon structure identical to X1. The ceramide of X2 consisted predominantly of saturated fatty acids (18:0 and 16:0). The tissue concentrations of X1 and X2 in kidney were 3.7 and 2.8 nmol/g, respectively.

Retention behavior of very large biomolecules in ion-exchange chromatography

Hepatitis B virus surface antigen (HBsAg) particles were efficiently adsorbed (retained) on a Sulfate–cellulose (S–C) bead column, and then desorbed with sodium chloride solutions (0.5–3.0 M). The HBsAg particles were not efficiently retained onto either sulfopropyl–agarose (SP–A) or quaternary amine–agarose (Q–A) at pH 4.5, 6 and 8. The size-exclusion curve showed that proteins of molecular mass higher than ca. 20 000 cannot penetrate into the pores of S–C beads. The dynamic binding capacity (DBC) values of lysozyme (ca. 7 mg/ml-gel) and of γ-globulin (ca. 3 mg/ml gel) for S–C did not depend on the flow velocity while the DBC of γ-globulin for SP–A decreased sharply with an increase in flow velocity. These results indicated that very large molecules are adsorbed only onto the surface of S–C, which resulted in fast adsorption–desorption rates although the equilibrium adsorption capacity is lower than conventional porous gel beads. Because of the rapid adsorption rate, the DBC values of γ-globulin for S–C at high flow-rate regions are similar to those for SP–A. Bovine serum albumin was not adsorbed onto S–C. As this can not be explained by a simple electrostatic interaction mechanism, molecular recognition of S–C might be different from the agarose-based ion-exchange beads.

Magnetic Resonance Imaging of Hydrocarbon-Contaminated Porous Media

Nuclear magnetic resonance response measurement is a nondestructive and nonintrusive technique, which is potentially useful for in situ characterization, mapping, and diagnostic purposes in hydrocarbon-contaminated subsurface, including rock. Magnetic resonance measurements of a porous medium allow the determination of necessary parameters to evaluate permeability and porosity of the medium and the type of hydrocarbons present in the pore fluid. This information is of particular importance in evaluation of hydrocarbon transport in contaminated soils. This paper presents the results of a preliminary study intended to evaluate the robustness of the magnetic resonance imaging technology using well-characterized laboratory specimens of porous material containing hydrocarbon liquids. First, a dry uniform sand pack impregnated with an aqueous coal tar mixture was imaged to evaluate discernable hydrocarbon distribution in the pore space of the sand column. Then, packed columns of glass beads of various sizes, permeated with distilled water and trichloroethylene, were imaged. The discernable images of the pore space and the interface of the two liquids in the pore space indicated that magnetic resonance imaging could be a viable tool to determine spatial distribution and mass fraction of hydrocarbon liquids in contaminated subsurface.

Mapping flow and dispersion in a packed column by MRI

This article reports spatially resolved measurements of fluid velocity and apparent dispersion coefficient in a packed column of impermeable polystyrene beads by magnetic-resonance-imaging velocimetry (MRIV).

Prediction of colloid detachment in a model porous media: Thermodynamics

AbstractDetachment of polystyrene latex colloids was studied in a model porous media system comprised of a packed column of glass beads. The polystyrene colloids were attached and subsequently detached from the glass beads by varying solution pH and ionic strength. It was found that classical‐DLVO theory could not predict detaching conditions. Extended‐DLVO theory was used to determine the median detaching pH for deionized water, and solutions of 0.01 and 0.1 M NaCl. Although both the colloids and porous media were macroscopically homogeneous, detachment was observed at a variety of pH values. The pH distribution of detachment and the energy distribution of the interaction between the polystyrene latex colloids and the glass beads followed gamma distributions. This work has provided a technique to quantitatively predict the aqueous chemistry changes that induce colloid detachment in porous media.

Enhancing bacterial transport for bioaugmentation of aquifers using low ionic strength solutions and surfactants

The transport of bacteria in contaminated aquifers over a distance of only one meter can require tens to thousands of unsuccessful collisions of bacteria with soil grains. Previous work has shown that low ionic strength (IS) solutions and the nonionic surfactant Tween 20 can reduce bacterial adhesion to ultraclean surfaces such as glass and quartz porous media. In this study, we examined whether these results could be generalized to soils and to other surfactants, by measuring the retention of two species of radiolabeled microbes over short (1 cm) distances in soil minicolumns. Calculations were also made, using the clean-bed filtration theory, to evaluate if bacterial transport distances are sufficient for bioagumentation to occur over a large region of the subsurface. Collision efficiencies were expressed using the filtration model in terms of the sticking coefficient, α, defined as the fraction of collisions that are successful. In glass bead columns, α's for monoclonal populations were reduced from α=0.19 ( Alcaligenes paradoxus) and α=0.01 (CD1), to α<0.008 for Tween 80-phosphate buffer solutions and α<0.0054 for low ionic strength (0.01 mM) solutions (Darcy velocity, U=10 −3 m s −1; Hammaker constant=10 −20 J; and fluid properties of water at 22°C). Low α's were also obtained using other nonionic surfactants (Tween 80, Triton 100 and 705, POE-10, Brij+35) and an anionic biosurfactant, all added at concentrations above their critical micelle concentration (CMC). Although sticking coefficients were also reduced by an order-of-magnitude for natural soils, sticking coefficients remained too high to permit wide dispersal of cells over distances of >1 m. For A. paradoxus, α was reduced using a low ionic strength solution from 0.72 to 0.083 for the Arizona soil and from 1.7 to 0.2 for the Ringold soil; for CD1, α was reduced from 0.57 to 0.09 for the Ringold soil. Based on the soil grain diameters of these soils (127 μm, Arizona soil; 224 μm, Ringold soil), α's in this range will permit transport distances (defined as 99.9% reduction in cell concentration) of ∼1 m ( U=10 m/d, 10°C) which may be sufficient for creating small, bioactive zones. However, in order to increase bacterial transport over distances >1 m, methods other than simple solution chemistry changes will be needed to enhance aquifer bioaugmentation operations.

Collision of a 1-D column of beads with a wall

An experimental study of the collision of a column of N beads ( ) with a fixed wall is presented. For a fixed height of fall and a rigid wall, we show that the maximum force felt by the wall is independent of the number of beads N. The duration of impact, the velocity of the deformation wave in the column and an effective restitution coefficient of the column are also measured as a function of N. For a soft wall, we show that the maximum force depends on N. A non-dissipative numerical model, based on a nonlinear interaction law between nearest neighbours, gives results in agreement with the experimental data. Moreover, we show that, after the compression phase, the beads of the top of the column separate one after the other from the column with a velocity greater than the initial one. The beads at the bottom then bounce upwards in block, with a velocity smaller than the initial one. We emphasize that this detachment effect results from the energy redistribution within the whole system during the collision and not from any dissipative effect.

The role of silica colloids on facilitated cesium transport through glass bead columns and modeling

Groundwater colloids can act as a vector which enhances the migration of contaminants. While sorbed to mobile colloids, contaminants can be held in the aqueous phase which prevents them from interacting with immobile aquifer surfaces. In this study, an idealized laboratory set-up was used to examine the influence of amorphous silica colloids on the transport of cesium. Synthetic groundwater and saturated glass bead columns were used to minimize the presence of natural colloidal material. The columns were assembled in replicate, some packed with 150–210 μm glass bead and others packed with 355–420 μm glass beads. The colloids used in these experiments were 100 nm amorphous silica colloids from Nissan Chemical Company. In the absence of these colloids, the retardation factor for cesium was 8.0 in the 150–210 μm glass bead columns and 3.6 in the 355–420 μm glass bead columns. The influence of anthropogenic colloids was tested by injecting 0.09 pore volume slugs of an equilibrated suspension of cesium and colloids into the colloid-free columns. Although there was little noticeable facilitation in the smaller glass bead columns, there was a slight reduction in the retardation of cesium in the larger glass bead columns. This was attributed to cesium having less of a retention time in the larger glass bead columns. When cesium was injected into columns with a constant flux of colloids, the retardation of cesium was reduced by 14–32% in the 150–210 μm glass bead columns and by 38–51% in the 355–420 μm glass bead columns. A model based on Corapcioglu and Jiang (1993) [Corapcioglu, M.Y., Jiang, S., 1993. Colloid-facilitated groundwater contaminant transport, Water Resour. Res., 29 (7) 2215–2226] was compared with the experimental elution data. When equilibrium sorption expressions were used and the flux of colloids through the glass bead columns was constant, the colloid facilitated transport of cesium was able to be described using an effective retardation coefficient. Fully kinetic simulations, however, more accurately described the colloid facilitated transport of cesium.

Determination of specific NAPL–water interfacial areas of residual NAPLs in porous media using the interfacial tracers technique

We present here an application of a new experimental method called the `interfacial tracers technique' (IFTT), using tracer retardation by adsorption as the basis, to determine the specific NAPL–water interfacial areas ( a nw, cm 2/cm 3) in packed columns of sand and glass beads containing residual saturation of non-aqueous phase liquid (NAPLs). Four NAPLs, two types of sand and uniform glass beads, and two interfacial tracers were used in the tracer experiments. The a nw values determined for residual NAPLs in sand or glassbead columns were in the range of 60 to 300 (with one exception of 1200) cm 2/cm 3, and are in agreement with the current understanding of immiscible fluid behavior in porous media. For a given NAPL, the a nw value was found to be about twice as large when the porous medium was NAPL wet first, compared to when the medium was first water wet. The interfacial tracer technique will be useful in assessing NAPL morphology, dissolution and mass transfer, and is useful in the characterization and remediation assessment at NAPL-contaminated waste sites.

Evaluation of column technology for direct antiglobulin testing

Abstract Preliminary reports have suggested that microcolumn technology might be too sensitive for direct antiglobulin testing (DAT). We studied 228 samples from patients with autoimmune diseases and 30 samples from healthy controls to determine the sensitivity of column techniques. Both Sephadex® gel and protein A/G columns were compared with manual methods using rabbit or murine polyspecific reagents. Of the 187 samples that were negative by both manual methods, an additional 29 (15%) and 42 (22%) samples gave weakly positive reactions with the Sephadex® and protein A/G bead columns, respectively. Subsequently, there was poor correlation between manual and column techniques (r = 0.40–0.61). Acid eluates from these samples were negative. We concluded that the column technology may detect too many weakly positive DATs that are clinically insignificant.