Bead Column Research Articles

Mass spectrometry-based proteomic analysis of proteins adsorbed by hexadecyl-immobilized cellulose bead column for the treatment of dialysis-related amyloidosis

Background Dialysis-related amyloidosis (DRA) is a severe complication in end-stage kidney disease (ESKD) patients undergoing long-term dialysis treatment, characterized by the deposition of β2-microglobulin-related amyloids (Aβ2M amyloid). To inhibit DRA progression, hexadecyl-immobilized cellulose bead (HICB) columns are employed to adsorb circulating β2-microglobulin (β2M). However, it is possible that the HICB also adsorbs other molecules involved in amyloidogenesis. Methods We enrolled 14 ESKD patients using HICB columns for DRA treatment; proteins were extracted from HICBs following treatment and identified using liquid chromatography–linked mass spectrometry. We measured the removal rate of these proteins and examined the effect of those molecules on Aβ2M amyloid fibril formation in vitro. Results We identified 200 proteins adsorbed by HICBs. Of these, 21 were also detected in the amyloid deposits in the carpal tunnels of patients with DRA. After passing through the HICB column and hemodialyzer, the serum levels of proteins such as β2M, lysozyme, angiogenin, complement factor D and matrix Gla protein were reduced. These proteins acted in the Aβ2M amyloid fibril formation. Conclusions HICBs adsorbed diverse proteins in ESKD patients with DRA, including those detected in amyloid lesions. Direct hemoperfusion utilizing HICBs may play a role in acting Aβ2M amyloidogenesis by reducing the amyloid-related proteins.

Transport and retention of silica nanoparticles in glass-bead columns: effects of particle size, type, and concentration of ionic species

Silica nanoparticles (SiO2 NPs) have garnered substantial attention as versatile additives in saline fluids, finding application in areas like environmental remediation, wastewater treatment, enhanced oil recovery, and carbon geo-sequestration. Despite their potential, the intricate interaction between electrolyzed nanoparticles and porous media remains inadequately researched in these contexts. This study delves into the pivotal yet underexplored aspect of silica nanoparticle absorption behavior within porous media, a key determinant of their practical effectiveness. The research focuses on silica particles with dimensions of 10 nm and 50 nm, synthesized via hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in methanol. Employing packed glass bead columns as a surrogate for porous media, the study unravels the complex mechanisms governing nanoparticle transport and deposition. Comprehensive investigations encompass variations in particle sizes, ionic strength, and ionic species, resulting in the examination of 48 distinct flooding scenarios. UV/Vis spectrophotometry is used to quantify nanoparticle concentrations in effluents, elucidating their transport behavior within the porous media. Concurrently, pressure drop alterations across the media serve as indicators of particle plugging and changes in permeability. Intriguingly, specific conditions involving a nanofluid comprising 50 nm silica nanoparticles and 10,000 ppm of magnesium chloride exhibit pronounced permeability reduction, offering potential insights for optimizing applications. Particularly noteworthy is the unique reduction in silica particle retention on glass bead surfaces as salinity increases, especially in the presence of magnesium sulfate. A concentration of 5000 ppm magnesium sulfate induces a log-jamming mechanism, resulting in an amplified final-to-intermediate permeability ratio. Experimental outcomes align with observations from scanning electron microscopy, improving understanding of porous media retention mechanisms. This study contributes to a deeper understanding of interactions between nanoparticles and porous media, paving the way for enhanced application strategies.

Nanobiopolymer: Potential Applications in Bioremediation of Cadmium Contaminated Water

Nanobiopolymer nanotechnology, bacterial extracellular polymeric substances (EPS), has been used markedly for various water treatments.EPS has polysaccharides, proteins, and lipids, which have functional groups such as amino, sulfhydryl, carboxylic, and phosphate groups that allow binding to metal ions. The accumulation of the metal ions onto the EPS bacterial cell walls is used widely in the bioremediation of cadmium and other metals. This study objectives were extracting EPSs from the bacterium Bacillus subtilis 168 Cd2 and investigating their cadmium adsorption in bead column reactors after being immobilized with calcium alginate. For comparison with the bacterium's role, B. subtilis 168 Cd2 was used before EPS extraction and immobilized with calcium alginate, as well as a comparison with the use of calcium alginate. Cadmium adsorption from solution onto calcium alginate beads with untreated B. subtilis 168 Cd2 and EPS-free B. subtilis 168 Cd2 and under different pH (4.00, 7.00, and 7.50) were studied. The percentages of adsorption onto untreated B. subtilis 168 Cd2 and EPS-free B. subtilis 168 Cd2 were determined and were 89% and 77%, respectively. The adsorption of these were reduced when the pH increased. Scanning electron microscopy (SEM) confirmed the changes in the morphology of the adsorbents, and X-ray fluorescence (XRF) spectrometry analysis recorded the cumulative concentrations of cadmium in the adsorbents after the cadmium adsorption process. EPS in untreated B. subtilis 168 Cd2 significantly enhanced cadmium adsorption percentages. The fewer carboxyl and phosphate groups in EPS-free B. subtilis 168 Cd2 decreased cadmium adsorption. The results obtained in this study are of fundamental significance for applying nano biopolymers nanotechnology environmental biotechnology and bioremediation.

Short term-efficacy and tolerability of Rheocarna, a novel direct hemoperfusion adsorptive column, for chronic limb-threatening ischemia in dialysis patients: A single-center case series.

With population aging and lifestyle changes, the number of patients with chronic limb-threatening ischemia (CLTI) is increasing, and refractory or recurrent lesions are more common, especially in chronic dialysis patients. In March 2021, a new type of adsorptive cellulose bead column immobilized with dextran sulfate and L-tryptophan for direct hemoperfusion (DHP) was approved by Japan's medical insurance system as a treatment for CLTI. We retrospectively analyzed 17 cases of CLTI in dialysis patients treated with DHP using the novel column (Rheocarna) (DHP-R) at our hospital from May 2021 to October 2022. The short-term of efficacy of DHP-R was judged qualitatively by the foot care team every 2 weeks based on the assessment of skin color, warmth, ulcer epithelialization or shrinkage of the ulcer area, and foot pain. The final judgment of efficacy was made after the final DHP-R session. The median age of patients was 66 years, the median dialysis duration was 10 years, 15 cases (88%) were male, and 15 cases (88%) had diabetes. The median total number of sessions was eight. In comparing the groups in which DHP-R was effective and ineffective, there was no significant difference in any factors including patient background data (i.e., age, diabetes, low-density lipoprotein cholesterol, hemoglobin, dialysis duration, etc.), type of anticoagulants, and presence of episodes of blood pressure drop or circuit clotting during session. Three cases with symptomatic hypotension during the session and two cases with circuit clotting that did not improve with increased heparin dose all resolved immediately after changing the anticoagulant from heparin to nafamostat mesylate (NM). Identification of patients' characteristics in which DHP-R is favorable and some reliable index that allow a rapid decision to continue DHP-R are needed. In addition, validating whether the use of NM as anticoagulant affects the efficacy of DHP-R for CTLI treatment remains a challenge to resolve.

Prospective use of a cell‐free supernatant from the biosurfactant‐producing marine Planococcus maritimus SAMP MCC 3013 for oil removal and enhanced oil recovery

AbstractThe cell‐free supernatant (CFS) of the biosurfactant (BS) producing pure strain of Planococcus maritimus SAMP MCC 3013 was used for enhanced oil recovery (EOR). An indigenous marine culture of P. maritimus was grown in mineral salt medium (MSM) supplemented with glucose (1%) (w/v) (30°C, 120 rpm, 7 days). CFS was used to demonstrate its application for oil recovery through three assays: pumice stone, saturated gravel, and the glass beads‐packed column. The recovery of light paraffin oil was ∼40% in the pumice stone assay and ∼43% in the oil‐saturated gravel assay, respectively. The glass bead column demonstrated ∼42% of additional 2T engine oil recovery by CFS. Our study showed that BS containing CFS from P. maritimus SAMP MCC 3013 has the ability to recover oil in its crude form without using any sophisticated purification techniques. All three methods operated by us are harmonizing with each other with respect to the findings. Those methods can be employed in large scale operations for the bio‐recovery of oils using an environmentally friendly approach through the functional properties of BS. This is most likely the first report describing the use of a glass bead pack column for EOR applications particularly from Planococcus sp. These results are symbolic of prospective applications of BS containing CFS from indigenous P. maritimus SAMP MCC 3013 under ex‐situ conditions.

In situ growth of metal hexacyanoferrate crystals on alginate beads for effective removal of radioactive cesium (137Cs) from seawater

Metal hexacyanoferrates (Me-HCFs) are highly effective materials for removing radioactive Cs (137Cs) in seawater. For their practical application, granulation of Me-HCFs is necessary. However, conventional granulation techniques using a polymer as a binding material adversely affect the adsorption performance of Me-HCFs by blocking their adsorption sites. In the present work, to minimize the interference of the binding material, Me-HCF crystals were synthesized on an alginate bead surface in situ for the treatment of 137Cs+-contaminated seawater. Three different Me-HCFs immobilized on alginate beads (Fe-HCF, Cu-HCF, and Co-HCF) were prepared via a simple and rapid method involving a reaction between ionophorically crosslinked alginate beads (Fe3+, Cu2+, and Co2+ ions) and HCF solution. Among them, Fe-HCF crystals were successfully grown on the alginate bead surface; the other crystals were hardly synthesized despite a longer reaction time. The Fe-HCF crystals composed 15.0 % (w/w) of the beads and were located on the surface of the beads rather than being embedded in the alginate matrix. Because the Fe-HCF crystals were located at the surface of the alginate beads, Cs+ adsorption onto the Fe-HCF crystals showed fast reaction kinetics (achieving equilibrium in ∼ 3 h) and a high Cs+ adsorption capacity (∼33.5 mg/g). Also, a feasibility test was carried out for the removal of radioactive 137Cs+ in real seawater medium. Finally, a continuous Cs+ removal test was conducted in a packed column of the Fe-HCF beads. It was able to treat 65 bed volume of 50 mg/L of Cs+ solution with a flow rate of 1 mL/min.

Comprehensive insight into adsorption of chlortetracycline hydrochloride by room-temperature synthesized water-stable Zr-based metal-organic gel/sodium alginate beads

Chlortetracycline hydrochloride (CTC) is one of the prevailing antibiotic pollutants that harm both environmental ecosystem and human health. Herein, Zr-based metal-organic gels (Zr-MOGs) with lower-coordinated active sites and hierarchically porous structures are fabricated via a facile straightforward room-temperature strategy for CTC treatment. More importantly, we incorporated the powder Zr-MOGs into low-cost sodium alginate (SA) matrix to achieve shaped Zr-based metal-organic gel/SA beads for enhancing the adsorption ability and ameliorating the recyclability. The Langmuir maximum adsorption capacities of Zr-MOGs and Zr-MOG/SA beads could reach 143.9 mg/g and 246.9 mg/g, respectively. What's more, in the manual syringe unit and continuous bead column experiments, Zr-MOG/SA beads could achieve an eluted CTC removal ratio as high as 96.3% and 95.5% in the river water sample, respectively. On top of that, the adsorption mechanisms were put forward as a combination of pore filling, electrostatic interaction, hydrophilic-lipophilic balance, coordination, π-π interaction as well as hydrogen bonding interaction. This study outlines a workable strategy for the facile preparation of candidate adsorbents for wastewater treatment.

Wave Generation by Fluidized Granular Flows: Experimental Insights Into the Maximum Near‐Field Wave Amplitude

AbstractTsunamis can be generated by an impulsive displacement of water resulting from the entrance of pyroclastic density currents (PDCs). The maximum wave amplitude is of primary interest regarding tsunami modeling and applications to hazard assessment. This study explores tsunami generation by fluidized granular flows and analyzes published relationships predicting maximum wave amplitudes from PDC characteristics. A fluidized column of glass beads is released from a reservoir, flows down an inclined plane and enters a water‐filled flume, generating waves. Fluidized flows of greater mass enter the flume with greater velocities; however, all the analyzed flows impact the water with a supercritical impact Froude number. Flows of greater mass generate a single, high‐amplitude wave, followed by a longer‐period trough. The solitary‐like leading wave propagates along the flume with a nearly constant amplitude. In contrast, the leading wave is followed by a low‐amplitude trough and a second low‐amplitude crest when generated by lower mass flows. Dispersive effects are stronger for waves produced by flows of lower masses, causing the decrease of the amplitudes with distance from the shore. Increased breaking and dissipation cause decreased amplitudes of the waves generated in shallow water depths. The predictive equations, determined based on the impact Froude number and the water depth in the constant‐depth section of the flume, provide relatively good predictions of the maximum wave amplitudes. A new approach is proposed, which calculates the impact Froude number considering the water depth value where the wave generation occurs, providing an improved understanding of the wave generation process.

Androgen receptor–specific CD8+ T cells with tumor cell cytotoxicity in patients with prostate cancer in Taiwan.

e17069 Background: Classical androgen receptor (AR) target is the new “tumor-specific” antigen for prostate cancer vaccine development to delay progression and castration-resistant disease. HLA-A2-restricted AR ligand-binding domain (LBD) has been demonstrated to stimulate cytotoxic T lymphocytes (CTL) in HLA-A2+ prostate cancer patients. Although the prevalence of HLA-A2 serotype and LBD-specific CD8+ T cells among Caucasians are known, their frequencies in the Taiwan patients have not been established. In this study, we performed HLA-A2 genotyping, HLA-A2+ LNCaP stimulation of autologous T cell, and CTL tumor cell cytotoxicity from 25 castration-sensitive prostate cancer patients using blood samples collected from a single hospital center. Methods: 20ml whole blood samples are collected in EDTA tube from non-metastatic, castration-sensitive prostate cancer patients. PBMCs are subjected to HLA-A2 allele sequencing, separated by CD3 magnetic bead column, and expanded and activated ex vivo using CD3/CD8 polymeric beads. Autologous T cells are then isolated by CD8 magnetic bead column, stimulated by HLA-A2+ lentivirus-transduced LNCaP (AR+), and targeted against transduced (HLA-A2+) and non-transduced (HLA-A2-) LNCaP (AR+) by Chromium-51 Release Assay. We identified and correlated their frequencies with patient’s age at diagnosis, Gleason grades, PSA level, and family history. Results: A total of 25 blood samples were tested and analyzed for HLA-A2 genotype with 44% (11/25) positive for the HLA-A2 [28% (7/25) heterozygotes, 16% (4/25) homozygotes]. Among the 11 HLA-A2+ patients, 72% (8/11) were HLA-A*02:07 allele, 100% (11/11) CD8+ T cells were successfully stimulated with HLA-A2+ transduced LNCaP (AR+) and 45% (5/11) patients demonstrated HLA-A2+ AR-specific CTL tumor cell lysis. No clinical association with patient age (54-86 y.o.), Gleason grades (6-9), PSA level (3.84-62.8 ng/ml), and family history (1/25). Conclusions: In this single hospital center study, we observed a similar prevalence of HLA-A2 alleles in Taiwan prostate cancer patient cohort with a predominant HLA-A2*02:07 allele, and higher frequencies of HLA-A2-restricted CD8+ T cell stimulation and HLA-A2+ AR-specific tumor cell cytotoxicity. Our findings support the application of AR LBD as tumor antigen for prostate cancer vaccine development for Taiwan prostate cancer patients.

Peridynamic mesh-free simulation of glass and metal beads column collapses

The density of the metal beads is almost 3 times the density of glass beads, and the rheological response is consequently different from glass beads by using the μ(I) rheology. In this study, the μ(I) rheology is first applied to simulate metal beads column collapse, which is implemented in Peridynamics to capture the transition from the fluid-like state to the solid-like state in the granular flow. To achieve this, flow response by the rheological parameters in the μ(I) rheology is extensively investigated by simulating glass beads column collapse. The numerical results are compared to the experimental measurements in terms of the free surface, velocity distribution, and the interface in the collision of two adjacent granular columns. It is found that the mobility of the granular material is significantly affected by static friction μs. The friction μ2 with high inertia in the rheology can affect the movements of free surface points in the simulations. Another parameter of a constant I0 in the rheology can reduce the material's mobility if its value is very small and large values show insignificant effects on the flow characteristics. The parameters of (μs, μ2, I0) = (0.36, 0.42, 0.01) in the rheology model can capture the free surface profiles in good agreement with the experimental measurements for the metal beads column collapse with different aspect ratios by using the numerical method.

Synthesis of core-shell fluorescent silica nanoparticles with opposite surface charges for transport studies of nanofluids in porous media

Silica nanoparticles (SiNPs) have been extensively studied as additives in injected fluids for enhanced oil recovery. Typically, surfactants are used to increase colloidal stability, but little is known about the transport of SiNPs in porous media because of the scarcity of reliable quantification techniques. In this study, we investigated the use of core-shell silica-based fluorescent SiNPs as tracers for transport studies of nanofluids containing surfactants. Two synthetic strategies were used to obtain distinct structures of fluorescent SiNPs with similar cores but different surface groups, namely silanol and aminopropyl, comparable to those reported in nanofluid applications. The synthesised NPs had comparable sizes and morphologies but displayed opposite surface charges when dispersed in aqueous solutions. The main colloidal properties and time stability of the fluorescence response were determined in the presence of an anionic surfactant and compared with regard to their potential use as tracers for transport studies. Both fluorescent SiNPs were successfully quantified in the effluent after flowing through the glass bead column. The SiNP-containing aminopropyl surface groups showed the greatest stability and lowest adsorption compared with those grafted with silanol groups. We attribute this behaviour to the effect of stronger attractive interactions between the NPs and surfactants. The potential of these fluorescent NPs as sensitive tracers for transport and adsorption studies in nanofluids containing surfactants was demonstrated.

New insight into adsorption and co-adsorption of chlortetracycline hydrochloride and ciprofloxacin hydrochloride by Ga-based metal-organic gel/sodium alginate composite beads

Due to the extensive usage of tetracyclines and fluoroquinolones for disease control, their residuals usually coexist in wastewater and seriously affect human health and the entire ecosystem. To mitigate this problem, developing efficient and recyclable absorbent has been urgently required to be put on the agenda. In this research, Ga-based MOGs (GMOGs) were synthesized to remove chlortetracycline hydrochloride (CTC) and ciprofloxacin hydrochloride (CIP) in aqueous solution, followed by incorporating GMOGs into low-cost sodium alginate (SA) matrix to gain GMOG/SA beads with enhanced adsorption property, fine recycling performance and stable reusability. In single system (S-system), the adsorption behaviors of CTC/CIP by GMOGs and GMOG/SA beads including key operating factors, kinetics, isotherms and practicability were investigated systematically, and the maximum adsorption capacities for CTC/CIP by GMOGs and GMOG/SA beads achieved 406.50/158.23 mg g−1 and 1085.19/862.07 mg g−1, respectively. Furthermore, the proposed adsorption mechanisms were discussed. In binary system (B-system), regardless of suppressed co-adsorption behaviors of CTC/CIP by GMOGs and GMOG/SA beads arising from the competitive effect between CTC and CIP, their adsorption capacities still reached 207.90/126.90 mg g−1 and 588.24/571.42 mg g−1, respectively. Moreover, the value of industrial application was evaluated by testing the adsorption performance of GMOG/SA beads in bead columns and real water. This work provides a potential practicable, effective and recycled exploration of GMOG/SA beads for remediating the CTC and CIP co-contaminated wastewater.

Experimental Modeling of Tsunamis Generated by Pyroclastic Density Currents: The Effects of Particle Size Distribution on Wave Generation

AbstractVolcanic tsunamis can expand the radius of hazards posed by a volcano well beyond the reach of the eruption itself; however, their source mechanisms are poorly understood. The tsunamigenic potential of pyroclastic density currents was studied experimentally by releasing a fluidized column of glass beads from a reservoir; the beads then ran down an inclined ramp into a water‐filled flume and generated waves. The effects of the particle size distribution on the generated waves were analyzed by comparing the waves generated by flows comprising different proportions of particles of diameters 63–90 μm and 600–850 μm. The flows comprising higher proportions of large particles travel more slowly down the ramp; however, all the flows impact the water at velocities greater than the shallow water wave speed, , where h is the still‐water depth. The entrance of the fluidized flow into the water generates a solitary‐like leading wave followed by a smaller trough and trailing waves. Upon impact, the flow separates into a part advected with the wave crest and a part which turbulently mixes with water and propagates along the bottom of the flume, forming an underwater gravity current. A higher proportion of large particles makes the flows more porous, allowing the water to penetrate through the flows more easily, slightly decreasing the efficiency of the energy transfer. While this affects the celerity of the waves, the results show that, over the studied range of particle size distributions, all the flows can generate waves of similar amplitudes regardless of the particle size distribution.

The effect of original and initial saturation on residual nonwetting phase capillary trapping efficiency

Injection of supercritical carbon dioxide (CO2) into geological formations is a strategy for both atmospheric greenhouse gas reduction (climate change mitigation) and enhanced oil recovery. To understand CO2 trapping efficiency, the capillary trapping behaviors that immobilize subsurface fluids were analyzed at the pore-scale using pairs of proxy fluids representing the range of in situ nonwetting and wetting fluid properties encountered in geologic storage reservoirs. The pairs of fluids were cycled through imbibition and drainage processes using a flow cell apparatus containing a sintered glass bead column. Computed x-ray microtomography (microCT) was used to identify immobilized nonwetting fluid after imbibition and drainage events. From microCT images, the trapped residual (post-secondary imbibition) nonwetting phase was spatially correlated to both the original (post-primary imbibition) and the initial (post-primary drainage) nonwetting phase; this relationship is referred to here as the original saturation dependence (SO-dependence) and initial saturation dependence (SI-dependence), respectively. Significant trends of decreasing SO- and SI-dependence with increasing wetting and nonwetting fluid phase viscosities were observed. This finding implies that the amount of CO2 injected and ultimately trapped is dependent on the nonwetting phase (e.g. oil or gas) already present in the formation, as well as on the manner in which supercritical CO2 is initially injected, which are factors not considered in current trapping models. To explore the potential effect that varying viscosity and interfacial tension (IFT) might have on this process, we report on a variety of fluid pairs with different viscosities and IFT.

Towards the sustainable fine control of microbially induced calcium carbonate precipitation

Microbially induced calcium carbonate precipitation (MICP) has been proposed as a potential solution to address many environmental and engineering issues. However, how to quantitatively and accurately control this novel biological cementation technology is still a major challenge. This study designed a factorial test, a verification test and an application test to provide theoretical basis for fine control of MICP. We have systematically monitored and analyzed the changes of proteins and polysaccharide, pH, electrical conductivity (EC), and zeta potential of the precipitation environment, and tracked the particle size distribution and microstructures of bio-cements from beginning to end. Based on the laboratory investigations, we discovered the particle size of the precipitations showed distinct features based on the analysis of physicochemical indicators, and a model for fine control of particle size of bio-cements was proposed. Further, the validation test was completed by “factory on a chip” technology. We successfully realized the production of pre designed particle sizes, the robustness of our model and the mechanism of particle formation were verified. Finally, we designed a three-stage cementation strategy for the application test of bio-cement bonded glass beads columns. The fine control cementation strategy has a higher utilization rate of raw materials and can provide twice the cementation strength compared with the reference test. The results show that our proposed model makes an important step forward in the direction of optimized application of bio-cements, which may be used as a process control standard to promote environment-friendly and sustainable MICP.

First-in-human study of blood amyloid β removal from early Alzheimer's disease patients with normal kidney function.

Amyloid β (Aβ) is a brain protein that causes Alzheimer's disease (AD). This study aimed to verify whether hemadsorption using a hexadecyl-alkylated cellulose bead (HexDC) column removes blood Aβ and brain Aβ accumulation in mild cognitive impairment/mild AD cases with normal kidney function. Two patients with positive Aβ on brain imaging underwent HexDC hemadsorption weekly for 6 months. The Aβ removal efficiency of HexDC was 87-99%. Aβ1-40 /Aβ1-42 influx into the blood in one session was 596/56 and 489/48 ng for Case A and Case B, respectively. Although brain Aβ accumulation did not clearly change after 6 months of hemadsorption, cognitive functions measured by the two tests were maintained or slightly improved. Blood Aβ removal was performed in two early AD patients with normal kidney function without adverse events, and it slightly improved or maintained cognitive function.

Permanganate oxidation of polycyclic aromatic compounds (PAHs and polar PACs): column experiments with DNAPL at residual saturation.

Permanganate is an oxidant usually applied for in situ soil remediation due to its persistence underground. It has already shown great efficiency for dense nonaqueous phase liquid (DNAPL) degradation under batch experiment conditions. In the present study, experimental permanganate oxidation of a DNAPL - coal tar - sampled in the groundwater of a former coking plant was carried out in a glass bead column. Several glass bead columns were spiked with coal tar using the drainage-imbibition method to mimic on-site pollution spread at residual saturation as best as possible. The leaching of organic pollutants was monitored as the columns were flushed by successive sequences: successive injections of hot water, permanganate solution for oxidation, and ambient temperature water, completed by two injections of a tracer before and after oxidation. Sixteen conventional US-EPA PAHs and selected polar PACs were analyzed in the DNAPL remaining in the columns at the end of the experiment and in the particles collected at several steps of the flushing sequences. Permanganate oxidation of the pollutants was rapidly limited by interfacial aging of the DNAPL drops. Moreover, at the applied flow rate chosen to be representative of in situ injections and groundwater velocities, the reaction time was not sufficient to reach high degradation yields but induced the formation and the leaching of oxygenated PACs.

Mass Spectrometry-Based Proteomic Analysis of Adsorbed Molecules in a Hexadecyl-Immobilized Cellulose Beads Column for the Treatment of Dialysis-Related Amyloidosis

Mass Spectrometry-Based Proteomic Analysis of Adsorbed Molecules in a Hexadecyl-Immobilized Cellulose Beads Column for the Treatment of Dialysis-Related Amyloidosis

Cloning, expression, and purification of chaperone AcrH from Aeromonas hydrophilausing Escherichia coli host cells

Aeromonas hydrophila (A. hydrophila) is a gram-negativebacterium, using the type III secretion system (T3SS). In the T3SS, a key structure is a translocon that inserts into the target membrane and forms a channel for bacterial toxins into the host cell. A. hydrophila is pathogenic to different organisms, including humans and aquatic animals (especially domestic animals with high economic value in Vietnam and the world, such as fishes, shrimps, amphibians). The pore completes the channel from bacteria to host, is composed of a major translocator (AopB) and minor translocator (AopD). These translocators are bound by a small chaperone (AcrH) in bacterial cytosol. AcrH chaperone plays an important role in keeping the high stability of translocators and prevents nonspecific interactions of hydrophobic domains before the pore formed in the host cell membrane. Previous studies only analysed the structure of the AcrH in combination with the AopB, but in a non-binding form with the AopB has not been elucidated. That limits the understanding of the formation mechanism of T3SS. Therefore, the authors aimed to clone, express, and purify the AcrH recombinant protein which can be used for the structural study and elucidation of T3SS pore formation. In this study, the authors cloned a fragment of the gene encoding for AcrH chaperone from A. hydrophila and inserted the gene into the pET-28a expression vector. AcrH protein from amino acids 21 to 158 was expressed in E. coli BL21 (DE3) and purified using a nickel bead column with high purity (over 99%). As a result, the obtained AcrH protein can be used for studies of structure and function that contribute to perfecting the pathogenesis of gram-negative bacteria and developing research on the treatment mechanism caused by these bacteria.

Removal of hexavalent chromium by encapsulated chitosan-modified magnetic carbon nanotubes: Fixed-bed column study and modelling

A new type of composite adsorbent, encapsulated chitosan-modified magnetic carbon nanotubes (CS/MWCNTs/Fe) beads were used to remove hexavalent chromium (Cr(VI)) from aqueous solutions in a fixed-bed column. Among the various combination of operating parameters, we obtain a maximum volume of treated effluent (210 mL) under the following conditions: flow rate, 1 mL min−1; bed height, 8 cm; feed Cr(VI) concentration, 30 mg L−1; and solution pH, 4.0 ± 0.2. The corresponding adsorption capacity was 1.54 mg g-1 and the overall Cr(VI) removal efficiency was 54 %. In characterizing the dynamics of the adsorption process and breakthrough profiles, we found that the Thomas model and the Yoon-Nelson model both accurately described the breakthrough curves under all experimental conditions, while the Adams-Bohart model was applicable only for an early phase of dynamic behavior CtC0≤0.5 of the CS/MWCNTs/Fe beads column. Columns with shorter bed heights favored the global mass transfer rate, especially during the early breakthrough periods. Moreover, the bed depth service time (BDST) model was validated experimentally, enabling the prediction of service time of the adsorption bed at different outlet concentrations using hypothetical flow rates and inlet concentrations. Scaled-up study was performed to observe the column performance at higher throughputs. The high selectivity of Cr(VI) adsorption in the simulated wastewater in the presence of other heavy metals (copper and cadmium) and background anion (phosphate) suggests the applicability of CS/MWCNTs/Fe beads for Cr(VI) removal from industrial effluents.