Polyethylene Beads Research Articles

An affinity adsorption media that mimics heparan sulfate proteoglycans for the treatment of drug-resistant bacteremia

Removal of several drug-resistant bacteria from blood by affinity adsorption onto a heparin-functional media is reported. Heparin is a chemical analogue of heparan sulfate (HS) proteoglycans, found on transmembrane proteins of endothelial cells. Many blood-borne human pathogens, including bacteria, viruses, parasites, and fungi have been reported to target HS as an initial step in their pathogenesis. Here, we demonstrate the binding and removal of Methicillin-resistant Staphylococcus aureus (MRSA), Extended-Spectrum Betalactamase Klebsiella pneumoniae (ESBL), and two Carbapenem-resistant Enterobacteriaceae (both CRE Escherichia coli and CRE K. pneumoniae) using 300μm polyethylene beads surface modified with end-point-attached heparin. Depending on the specific bacteria, the amount removed ranged between 39% (ESBL) and 99.9% (CRE). The total amount of bacteria adsorbed ranged between 2.8×105 and 8.6×105 colony forming units (CFU) per gram of adsorption media. Based on a polymicrobial challenge which showed no competitive binding, MRSA and CRE apparently utilize different binding sequences on the immobilized heparin ligand. Since the total circulating bacterial load during bacteremia seldom exceeds 5×105 CFUs, it appears possible to significantly reduce bacterial concentration in infected patients by multi-pass recirculation of their blood through a small extracorporeal affinity filter containing the heparin-functional adsorption media. This ‘dialysis-like therapy’ is expected to improve patient outcomes and reduce the cost of care, particularly when there are no anti-infective drugs available to treat the infection.

Hydrodynamic Study Of Column Bioleaching Processes

Abstract The modelling of flow leaching solution through the porous media has been considered. The heap bioleaching process can be tested using the column experimental equipment. This equipment was employed to the hydrodynamic studies of copper ore bioleaching. The copper ore (black shale ore) with the support, inertial materials (glass small balls and polyethylene beads) was used to the bioleaching tests. The packed beds were various composition, the ore/support ratio was changed. The correlation between the bed porosity and bioleaching kinetics, and copper recovery was investigated.

OBT analysis method using polyethylene beads for limited quantities of animal tissue

This study presents a polyethylene beads method for OBT determination in animal tissues and animal products for cases where the amount of water recovered by combustion is limited by sample size or quantity. In the method, the amount of water recovered after combustion is enhanced by adding tritium-free polyethylene beads to the sample prior to combustion in an oxygen bomb. The method reduces process time by allowing the combustion water to be easily collected with a pipette. Sufficient water recovery was achieved using the polyethylene beads method when 2 g of dry animal tissue or animal product were combusted with 2 g of polyethylene beads. Correction factors, which account for the dilution due to the combustion water of the beads, are provided for beef, chicken, pork, fish and clams, as well as egg, milk and cheese. The method was tested by comparing its OBT results with those of the conventional method using animal samples collected on the Chalk River Laboratories (CRL) site. The results determined that the polyethylene beads method added no more than 25% uncertainty when appropriate correction factors are used.

Exercise Response in a New Porcine Model of Chronic Embolic Pulmonary Hypertension

Chronic Thromboembolic Pulmonary hypertension (CTEPH) is a deadly disease initiated by thrombo‐embolisms persisting in the pulmonary vasculature, followed by remodelling of the pulmonary vascular bed, resulting in a sustained increase in afterload of the right ventricle (RV). Although the response of the pulmonary vasculature to the initiating thromboembolic events as well as the response of the RV to the increased afterload are known to be the most important determinants of patient outcome, the factors that underlie these processes are incompletely understood. In the present study, we developed a novel chronically instrumented swine model of CTEPH. CTEPH was induced by up to 5 weekly injections of polyethylene beads of 700 μm in combination with induction of endothelial dysfunction by eNOS‐inhibition. Swine were followed up to one month after the last embolization. Changes in mean pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) were used as indices of RV afterload and pulmonary vascular remodeling. and assessed at rest and during treadmill exercise (EX) .
Repeated embolization resulted in increases in PAP and PVR. Control After first embolization Prior to sacrifice rest EX rest Ex Rest Ex PAP (mmHg) 16±1 33±3* 29±3† 61±7*† 47±15† 72±16*† PVR (mmHg.min.kg.L‐1) 86±13 98±16 160±42† 197±23† 510±237† 633±344† * P<0.05 vs Rest, † P< 0.05 vs Control The increase in PAP was exaggerated during exercise, and in two animals, limited the increase in cardiac output during exercise. The increase in PVR induced by repeated embolization correlated well with RV weight (r2=0.78), indicating that swine developed RV hypertrophy. Moreover, histology revealed increased muscularization of pulmonary arterioles.In conclusion, our new swine model of CTEPH mimics critical features of patients with CTEPH in that pulmonary vascular remodeling is present and exercise capacity is reduced.Supported by CVON‐ PHAEDRA2012‐08

New cementitious composite building material with enhanced toughness

In the present work, carbon nano/micro-particles obtained by chemical vapor depostion (CVD) process and controlled pyrolysis from polyethylene beads (CNBs) and coconuts choir (CCNs) are presented. These materials were characterized by Raman spectroscopy, thermogravimetry and field emission-scanning electron microscopy (FE-SEM). FE-SEM observations evidenced that CNBs particles proved to be spherical and interconnected, while the CCNs were irregular in shape, as the result of the grinding step. When added to cement paste, up to 0.08wt%, both materials were effective in increasing the cement matrix compressive strength and toughness. From FE-SEM observations it is evident that the presence of these small particles disturb the propagation of microcracks that have to deviate from their trajectory and have to follow the carbon nano/micro-particles contour. This mechanism increases strongly the fracture surface during the test performed by imposing the monotonic increment of crack opening. The crack and crack pinning are the mechanisms which can explain the increase of toughness in the composite samples.

Removal of Carbapenem-Resistant Enterobacteriaceae (CRE) from blood by heparin-functional hemoperfusion media.

Bloodstream infections due to Carbapenem-Resistant Enterobacteriaceae (CRE) are becoming more frequent and are associated with a high mortality. At present, combination antimicrobial therapy yields the best outcomes, but treatment options are limited. Many bacteria utilize heparan sulfate to bind to human cells. We studied the ability of a biomimetic device composed of polyethylene beads with endpoint-attached heparin to bind both sensitive and (CRE) E. coli and Klebsiella pneumoniae from spiked blood samples. Greater than 90% of susceptible, E. coli, CRE E. coli and CRE Klebsiella were removed by the beads. Future studies in human bacteremia with this technology are planned.

Removal of Plant Pathogen Propagules from Irrigation Runoff using Slow Filtration Systems: Quantifying Physical and Biological Components

Recycling irrigation water is a common practice at ornamental plant nurseries for conserving water; however, it poses the risk of sourcing and dispersing waterborne plant pathogens, especially species of Phytophthora. Slow sand filtration is a water treatment process that can remove pathogens from water, but the slow rate of water treatment may limit its application at nursery operations. In this study, four novel substrates (crushed brick, calcined clay, polyethylene beads, and Kaldnes® medium) in addition to sand were examined to determine how effective each substrate was at removing zoospores of Phytophthora nicotianae from water. The effects of substrate physical parameters, substrate depths (0, 5, 10, 20, 40, and 60 cm), and microbe density (after nursery effluent was recirculated through each substrate for 21 days) on zoospore removal by each substrate were quantified. Sand was the most effective physical filter and supported development of the best biological filter for removing zoospores. Sand columns 40 and 60 cm deep removed zoospores completely using physical filtration alone, and zoospore removal by sand at 10- and 20-cm depths was increased with the addition of biological filtration. Kaldnes® medium and polyethylene beads were the least effective filtration substrates under all conditions tested. After 21 days of recirculating nursery effluent through substrate columns, microbe density in and zoospore removal by all substrates increased. With further optimization, crushed brick may have potential to be utilized as a recycled material for a slow filtration system focused on removing plant pathogens from irrigation water.

Rhizobial counts in peat inoculants vary amongst legume inoculant groups at manufacture and with storage: implications for quality standards

Inoculation of legumes at sowing with rhizobia has arguably been one of the most cost-effective practices in modern agriculture. Critical aspects of inoculant quality are rhizobial counts at manufacture/registration and shelf (product) life. In order to re-evaluate the Australian standards for peat-based inoculants, we assessed numbers of rhizobia (rhizobial counts) and presence of contaminants in 1,234 individual packets of peat–based inoculants from 13 different inoculant groups that were either freshly manufactured or had been stored at 4 °C for up to 38 months to determine (a) rates of decline of rhizobial populations, and (b) effects of presence of contaminants on rhizobial populations. We also assessed effects of inoculant age on survival of the rhizobia during and immediately after inoculation of polyethylene beads. Rhizobial populations in the peat inoculants at manufacture and decline rates varied substantially amongst the 13 inoculant groups. The most stable were Sinorhizobium, Bradyrhizobium and Mesorhizobium with Rhizobium, particularly R. leguminosarum bv. trifolii the least stable. The presence of contaminants at the 10−6 level of dilution, i.e. >log 6.7 g−1 peat, reduced rhizobial numbers in the stored inoculants by an average of 37 %. Survival on beads following inoculation improved 2–3 fold with increasing age of inoculant. We concluded that the Australian standards for peat-based rhizobial inoculants should be reassessed to account for the large differences amongst the groups in counts at manufacture and survival rates during storage. Key recommendations are to increase expiry counts from log 8.0 to log 8.7 rhizobia g−1 peat and to have four levels of inoculant shelf life ranging from 12 months to 3 years.

New Concepts for Next Generation of High Performance Concretes

With the development of high-speed railway, long span bridges and high-rise buildings, new concretes need to increase strength and toughness. Adding fibers to concrete matrix has been long recognized as a way to enhance the energy absorption capacity and crack resistance of the plain concrete. In recent years, particular attention has been paid to the distribution of fibers: very small and well dispersed fibers may control the microcracks in the matrix from the very beginning of their opening and particularly high deformability of the composite may be obtained [3–5]. Carbon nanotubes (CNTs) used as reinforcing fibers has been also explored [6–8], the functional effect of their addition in a concrete equals to the one obtained with the addition of fibers. CNTs also provide a better ductility and an increase of the fracture energy. However, agglomeration and the relative high price seem to limit their application in cement based composite materials [14]. In this work, the potential beneficial effects of carbon micro/nanoparticles addition to cement pastes for improving the mechanical properties of the resulting composites has been investigated [15]. Pyrolyzed polyethylene beads (CNBs) and coconuts shells (Cocos nucifera, CCNs) were produced at Politecnico di Torino and characterized by Raman spectroscopy, thermogravimetry and scanning electron microscopy (SEM). When added to cement paste, up to 0.08 wt%, both materials were effective in increasing the cement matrix compressive strength and toughness. From SEM observations it is evident that the presence of these small particles disturb the propagation of microcracks, which has to deviate from its trajectory and has to follow the carbon nano/micro-particles contour. This mechanism increases strongly the fracture surface during the test performed by imposing the monotonic increment of crack opening. Crack and crack pinning are the mechanisms which can explain the increase of toughness in the composite samples.

High-frequency ultrasound of breast tissue phantoms with histology mimicking microstructures

The objectives of this study were to develop breast tissue phantoms with microstructures that accurately mimic the histology of normal and malignant tissue, and to determine the effects of these microstructures on high-frequency (HF) ultrasonic spectra (10–100 MHz). Phantoms were created from a mixture of water, gelatin, and soluble fiber. To simulate various breast tissue histologies, polyethylene beads and nylon fibers with a range of diameters were embedded into phantoms. Microstructures ranging from simply dispersed beads to bead-fiber constructs resembling terminal ductal lobular units were modeled and tested. Pitch-catch and pulse-echo measurements were acquired using 50-MHz transducers, a HF pulser-receiver, and a 1-GHz digital oscilloscope. Spectra were derived from the data and peak densities (the number of peaks and valleys in a specified spectral range) were determined from the spectra. Preliminary results from dispersed beads (58–925 µm diameter) of constant volume concentration (0.8%) indicated that the smaller beads produced higher peak densities than the larger beads with a consistent trend. The higher peak densities can be attributed to either the higher number of scatterers for small beads or the size of scatterer in relation to the ultrasonic wavelength. These and results from more advanced histologically accurate microstructures will be discussed.

Ion implantation treatment of beads for covalent binding of molecules: Application to bioethanol production using thermophilic beta-glucosidase

We have achieved plasma immersion ion implantation (PIII) treatment of beads and powders using a specially designed plasma treatment system. This simple one-step production of functionalized beads provides an attractive alternative to current commercial functional beads, for which proteins must be chemically attached using linkers.Using the enzyme beta-glucosidase as an example we show that PIII treatment of polyethylene beads enables covalent binding with increased activity of the enzyme compared to the untreated beads. Covalent binding was confirmed using detergent washing. The covalently immobilized enzyme has a broader pH range over which it has high activity than the enzyme in solution. The stability of the immobilized molecules was examined using reaction rate as a function of temperature and was shown to be significantly higher on the PIII treated beads compared to untreated beads. We attribute the increased enzyme activity on PIII treated beads to increased protein binding density and better retention of conformation. The results of this work are of significance in the production of ethanol using a flow process. Covalent binding to beads allows more robust attachment for high flow rates, high activity, large surface area and a broad operating pH range. Treatment could be easily adapted for a range of applications such as linking drugs, dyes and proteins to particles of an appropriate size.

An alternative method of OBT measurement for the limited quantity of environmental samples using a combustion bomb

The measurement of organically bound tritium (OBT) in environmental samples is much more difficult than the measurement of tritiated water (HTO). This study describes an alternative method for OBT determination in plant materials in which tritium-free polyethylene beads are added to the plant sample prior to combustion in a combustion bomb. It is not always possible to collect large enough amounts of some plants (e.g. algae, plankton, grass) within a specific area or specific period. Excellent water recovery is achieved when dry plant materials are combusted with polyethylene beads. When Ultima Gold AB is used as the scintillation cocktail, it is possible to measure the combustion water directly without distillation. Correction factors were derived for the plants used in the study to account for the dilution of the combustion water due to addition of the polyethylene beads. The alternative method has a number of advantages, including an increased yield of combustion water for liquid scintillation counting, less color quenching, reduced sample size and decreased analysis time. Finally, accuracy tests comparing results of the conventional method with those of the alternative method were carried out using environmental samples.

Image analysis measurements of particle coefficient of restitution for coal gasification applications

New robust Lagrangian computational fluid dynamic (CFD) models are powerful tools that can be used to study the behavior of a diverse population of coal particle sizes, densities, and mineral compositions in entrained gasifiers. By using this approach, the responses of the particles impacting the wall were characterized over a range of velocities (1 to 8m/s) and incident angles (90 to 20°). Within CFD models, the kinematic coefficient of restitution is the boundary condition defining the particle wall behavior. Four surfaces were studied to simulate the physical conditions of different entrained-flow gasification particle–surface collision scenarios: 1) a flat metal plate 2) a low viscosity silicon adhesive, 3) a high viscosity silicon adhesive, and 4) adhered particles on a flat metal plate with Young's modulus of elasticity ranging from 0.9 to 190GPa. Entrained flow and drop experiments were conducted with granular coke particles, polyethylene beads and polystyrene pellets. The particle normal and tangential coefficients of restitution were measured using high speed imaging and particle tracking. The measured coefficients of restitution were observed to have a strong dependence on the rebound angles for most of the data. Suitable algebraic expressions for the normal and the tangential component of the coefficient of restitution were developed based upon ANOVA analysis. These expressions quantify the effect of normalized Young's modulus, particle equancy, and relative velocity on the coefficient of restitution. The coefficient of restitution did not have a strong dependence on the particle velocity over the range considered as long as the velocity was above the critical velocity. However, strong correlations were found between the degree of equancy of the particles and the mean coefficient of restitution such that the coefficient of restitution decreased for smaller particle equancies. It was concluded that the degree of equancy and the normalized Young's modulus should be considered in applications such as gasification and other cases involving the impact of non-spherical particles and complex surfaces. Sliding was observed when particles impacted on oblique surfaces; however, the resulting effects were within the range of measurement uncertainties.

Novel Burkholderia bacteria isolated from Lebeckia ambigua – A perennial suffrutescent legume of the fynbos

We investigated symbiotic and physiological properties, and taxonomic position, of 23 bacterial strains isolated from Lebeckia ambigua root nodules collected from the South African fynbos region. The capacity for nodulation and nitrogen fixation on three provenances of L. ambigua was investigated for these strains together with several physiological characters, including growth rate on peat and in betonite clay, survival on polyethylene beads and pH tolerance. Additionally, the 16S rRNA gene phylogeny was determined. The root nodule bacteria isolated clustered in five different groups belonging to the genus Burkholderia, most closely related to B. caledonica, B. graminis and B. tuberum. Moreover there was a very strong influence of collection site on the taxonomy of the Burkholderia strains. The physiological characterisation revealed two promising strains, WSM4174 and WSM4184, achieved rapid growth in normal media and reached high, stable numbers in sterile peat. However, there was a worrying susceptibility to desiccation amongst these Burkholderia. Additionally, evidence was found for isolation of non-symbiotic strains from the nodule material collected in South Africa.

Preparation and antimicrobial activity of polyethylene composite films with silver exchanged zeolite-Y

This study aimed at the preparation of antimicrobial films based on silver (Ag) exchanged zeolite Y. The zeolite was exchanged to a final concentration of 5% silver and was characterized by different methods. The inclusion of silver in the zeolite did not change its structure. The antimicrobial activity of the Ag-exchanged zeolite was assessed on Escherichia coli, by the minimum inhibitory concentration method (MIC). The zeolite with 5% Ag showed effective antimicrobial activity. The MIC was 0.5mg zeolite/mL, which corresponds to 25μg Ag/mL. The leaching of Ag ions to the medium was assessed by AAS, which showed that 56% of the silver ions was leached from the zeolite to the medium. The polyethylene films with the Ag–zeolite were prepared by the methods of wet-casting and thermal pressing of polyethylene beads mixed with Ag–zeolite, varying the zeolite content from 1 to 10wt%. The inclusion of the Ag–zeolite in the film did not change the film thermal degradation. The films that showed antimicrobial activity on E. coli were those prepared with 5% zeolite containing 5% silver, showing the potential application of such films in food preservation and safety.

Properties of multi-strength grade EPS concrete containing silica fume and rice husk ash

This paper aims to study the possibility of producing multi-strength grade lightweight concrete containing expanded polyethylene beads and evaluate their mechanical and durability characteristics. To this aim, various mixtures are produced by replacing 0%, 15%, 25%, 40% and 55% of natural aggregates volume with EPS beads, substituting cement with 10% silica fume (SF) or 20% rice husk ash (RHA), and adding waste propylene fibers in the percentage of 0.1, 0.3, 0.5 and 1 of cement volume (0.013%, 0.038%, 0.063% and 0.127% of concrete volume). These mixtures are evaluated through a comprehensive test program including measuring compressive strength, splitting tensile strength, flexural strength, ultrasonic pulse velocity, drying shrinkage, water absorption and electrical resistivity. Generally, application of EPS beads decreases the strength properties; however, the results show the potential of EPS beads for producing structural grade, moderate strength grade and insulating lightweight concrete. Mixtures containing 15% EPS beads and 20% RHA as well as 25% EPS beads and 10% SF show acceptable strength and density for structural lightweight concrete. In addition, application of 40% and 55% EPS beads lead to the moderate strength grade and insulting lightweight concrete respectively. These results accompany by an improvement in electrical resistivity, and increase in water absorption and drying shrinkage. Moreover, except for toughness, addition of waste fibers has not improved lightweight concrete properties.

ω-Dimethyl ammonium tetrakis-pentafluorophenyl borate polyisoprene as an organic template for alkylated metallocenes toward the synthesis of polyethylene beads

In this work, we report the self-assembly in heptane of ω-dimethyl ammonium tetrakis-pentafluorophenyl borate polyisoprenes into micellar aggregates and the use of these nano-objects to support alkylated metallocenes toward ethylene polymerization. Dynamic light scattering was used to demonstrate the self-assembly and the formation of the micellar structures having a core of polar dimethyl ammonium tetrakis-pentafluorophenyl borate moieties, and a corona of polyisoprene (PI). The latter were then used as organic supports for alkylated metallocenes to produce unprecedented millimetric polyethylene beads without loss of catalytic activity.

Immobilization of some biomolecules onto radiation‐grafted polyethylene beads for possible use in immunoassay applications

AbstractFunctionalization of polyethylene (PE) beads was accomplished via radiation induced graft copolymerization of acrylic acid/acrylamide (AAc/AAm) binary comonomer of different compositions onto such beads. Factors affecting the grafting yield were optimized and the occurrence of the grafted chains was confirmed by following the FTIR spectra of the grafted beads. SEM analyses were used to follow the variation of the morphology of the grafting and immobilization onto PE beads. Some bio‐active molecules such as Follicle‐stimulating hormone (FSH), Luteinizing hormone (LH), Thyroid‐stimulating hormone (TSH), and Prolactin were immobilized to the radiation functionalized PE beads. The parameters may affect the immobilization process such as degree of grafting, temperature, and pH of the coupling buffer and the coupling period were investigated. The obtained results show that the grafting of AAc offers a better immobilization environment than those of AAm and their copolymer. It is found that the highest immobilization degree would be achieved at pH 7 and 37°C for 24 h. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Effect of submergence depth of the ladle shroud on liquid steel quality output from a delta shaped four strand tundish

Physical and mathematical modelling was performed in a full-scale water model tundish to study the effect of the submergence depth of the shroud on melt flow and liquid metal quality. In the full-scale water model tundish, slag entrainment tests were performed at various immersion depths of the shroud. Polyethylene beads (920 kg m−3) were used to simulate the slag phase and the number of beads collected in each submerged entry nozzle during a ladle change, indicated relative performances in terms of slag entrainment. A three-dimensional mathematical model was developed and contours of turbulence (turbulent kinetic energy (TKE) contours) were examined at different depths of submergence of the ladle shroud. At low depths of submergence there is high turbulence within the tundish and this causes more slag entrainment. On the contrary, at high submergence depths there is very low turbulence and hence amount of slag entrained is less. Tundish operations with higher submergence depth of the shroud may eliminate the use of turbulence inhibitors and thereby reduce refractory consumption and cost.

Development of Novel Filter Materials for the Treatment of First-Flush Rainwater

First-flush rainwater is of great interest in the research on urban environmental protection and rainwater harvesting. It deteriorates the chemical, physical, and microbiological quality of the collected/stored water as well as the water body in an urban area. Accordingly, effective and economic treatment of first-flush rainwater is highly required. This study aimed to develop a technology for the treatment of first-flush rainwater using new filters made of wood fiber mat, dental cotton, and feldspar. The removal of pollutants in first-flush rainwater with each filter material was evaluated. Experiments were carried out using an artificial rainwater solution made of road dust particles (less than 200 um small) and D.I. water that contained ionic species. The SS concentration of the solution was set between 30 and 150 mg/L. Prior to the experiments, the fiber materials were pretreated with NaOH, FeCl3, and Al2O3. The batch test results indicated that the phosphate removal efficiency of the wood fiber mat was 8.6%; of the dental cotton, 34.7%; and of the feldspar, 1.7%. On the other hand, the heavy metal removal efficiency of the wood fiber mat was 91%; of the dental cotton, 26%; and of the feldspar, 0%. The highest cation exchange capacity of the wood fiber mat that was pretreated with NaOH was attributed to the existence of carboxyl and hydroxyl functional groups in the wooden polymers. Combinations of filter materials were found to have been effective in removing particles in the rainwater. The combination of the wood fiber mat with polyethylene beads resulted in 97-98% particle removal. Other combinations such as DP (dental cotton and polyethylene beads), MF (wood fiber mat and feldspar), and DF (dental cotton and feldspar) showed particle removal rates of 90-95%, 84-96%, and 87-94%, respectively. After 30 minutes, all the combinations had a particle removal rate of over 90%.