Basis Of Particle Size Research Articles

Biopolymer-assisted synthesis of yttrium oxide nanoparticles

Yttrium oxide nanopowder was prepared by a novel technique using an alginate biopolymer as a precursor. The technique is based on thermal decomposition of an yttrium alginate gel, which is produced in the form of beads by ionic gelation between the yttrium solution and sodium alginate. The effect of post-annealing temperature on the particle size of the nanocrystals was investigated at various temperatures. The products were characterized using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The size of the nanocrystalline Y2O3 particles varied from 22.7 to 38.7nm, depending on the annealing temperature and time. The grain size distribution (GSD) was also determined. The GSD became more non-symmetrical as the annealing temperature increased, and the width of the distributions for the powders produced using the alginate method was less affected by heat treatment. This alginate method was compared with the conventional glycine combustion method, on the basis of particle size. The particles obtained using the proposed technique were smaller than those obtained using the combustion method. Alginate-assisted thermal decomposition is therefore an easy and cost-effective method for preparing nanosized Y2O3 crystals.

CFD–DEM investigation of particle separations using a sinusoidal jigging profile

This paper presents a numerical investigation of solid separation in jigging device. Jigging is a gravity separation method commonly used by the minerals industry to separate coal, iron ore, diamonds and other minerals on the basis of particle size and/or density. Separation is recognised as being heavily dependent on fluid motion in the jig. This study explores the effects of the inlet time dependent velocity profile in relation to a wide criterion on jigging performance. Modelling of the liquid–solid system is performed through a combination of computational fluid dynamics (CFD) to simulate liquid flow and discrete element method (DEM) to resolve particle motion. The initial packing conditions consist of a binary-density particle system of 1130 particles each 1cm in diameter. A range of jigging profiles have been implemented in mineral processing. In this study the sinusoidal pulsation profile is selected adopting variations in both amplitude and frequency. The performance of profile variants are compared in terms of solid flow patterns, separation kinetics, energy, and mean particle position. These quantitative comparisons demonstrate significant differences in the segregation rate, energy, and solid phenomena, helping find an alternative optimum operating setting for the system. In addition, boundaries of operation are found in terms of frequency and amplitude limits and the concentration mechanics are investigated in these regions.

A phenomenological description of moisture capacity of iron ores

Moisture capacity of iron ore, defined as its ability to hold water, has been found to be affected by its particle size and chemical composition. To explain this phenomenon, mathematical model was developed on the basis of particle size, specific surface area, pore properties and contact angle between the iron ore and water. The specific surface area and the pore volume of iron ores were measured to validate the model, and parametric studies were carried out to investigate the effects of these factors, showing that particle size and surface area of the iron ore and thickness of the water film are the principal factors determining the moisture capacity. The model gave reasonable explanation of the phenomenon that moisture capacity increases with decreasing particle size. A correlation developed can well predict the moisture capacity of iron ores. Deviations between measurements and calculations were analyzed.

Fabrication, characterization and magnetic behaviour of alumina-doped zinc ferrite nano-particles

Zinc ferrite nano-powders with a nominal composition of ZnFe 2O 4 were prepared by combustion synthesis using mixture of urea and ammonium nitrate as fuel. The influence of alumina-doping on the structural, morphological and magnetic properties of ZnFe 2O 4 nano-particles was investigated by means of X-ray powder diffraction (XRD), infrared (IR) spectroscopy, scanning and transmission electron microscopy (SEM and TEM) and vibrating sample magnetometer (VSM). XRD and IR analyses confirm the cubic spinel phase of ZnFe 2O 4 nano-particles. The Zn ferrite presented a uniform microstructure with grain size in nano-scale. Alumina-doping brought about a change in the morphology of the as prepared ferrite from sphere-like to regular hexagon. Al 2O 3-treatment led to a decrease in the coercivity ( H c), magnetization ( M s) and magnetic moment ( n B ) of the investigated system. The maximum decrease in the values of H c, M s and n B due to the treatment with 1.5 wt% Al 2O 3 attained 13.5, 17.4 and 13.5%, respectively. The observed results can be explained on the basis of particle size and the Fe 3+ concentration in the octahedral and tetrahedral sites involved in the cubic spinel structure.

New asthma drugs: small molecule inhaled corticosteroids

Small-particle inhaled corticosteroid (ICS) metered-dose inhalers were recently developed to treat asthma as part of the CFC to HFA propellant switch mandated by the Montreal Protocol. Two such ICS, beclomethasone dipropionate (BDP) and ciclesonide (CIC), are available in the United States and are formulated in HFA solutions. A major advantage of small-particle ICS is that they have improved total lung deposition and consequently, effective asthma control is achieved at lower daily doses than the large-particle ICS. Another advantage of small-particle ICS is that they are able to reach the small airways and consequently, may result in increased efficacy. Indeed, recent studies have demonstrated the effect of small-particle ICS on asthmatic inflammation in the small airways. Another advantage of small-particle ICS is that they may have an improved safety profile. Small-particle inhalers generally deposit decreased amounts of drug in the oropharynx than their CFC counterparts possibly resulting in a lower incidence of oropharyngeal candidiasis. However, growth studies and most HPA studies do not support improved safety on the basis of particle size alone and some studies suggest even higher systemic bioavailability and safety risk with smaller particles, depending on the molecule and the formulation. Further efficacy and safety studies are clearly warranted to determine any potential advantages of small-particle ICS, particularly in long-term disease modification where large-particle ICS have failed, and in infants and pre-schoolers, in whom airway delivery is problematic with current formulations.

Nature and reactivity of charcoal produced and added to soil during wildfire are particle-size dependent

Charcoal added to soil by wildfires is usually considered to be part of the most stable pool of soil organic matter (SOM). It consists of a continuum of slightly burned plant residues to completely charred material. We sampled the macroscopic charcoal pool produced by a moderate intensity wildfire in a pine coastal forest in Tuscany (Central Italy) with the aim of assessing the relationship between its particle size and chemical composition as well as its reactivity. Our conceptual approach included particle size separation by dry sieving and analysis of four size fractions (>2 mm, 2–1 mm, 1–0.5 mm and <0.5 mm) for elemental composition. The composition of the charcoal fractions was studied using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy, analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and CuO oxidation. The reactivity of the fractions was assessed using acid dichromate oxidation, while the morphology was observed using scanning electron microscopy (SEM). There were clear differences in chemistry and reactivity between the fractions. The different fractions are probably the result of both type of original plant material and the fire conditions. In fact, wood-derived charcoal largely prevalent in the largest fraction, while pine needles and herbs were most probably precursors of charcoal in the smallest fractions. The degree of charring was greatest for the coarse fraction, which represented 56% of the total charcoal, and decreased gradually to the finest fraction. The composition was completely aromatic for the coarsest fraction, whereas the finest fraction showed a greater contribution from aliphatic C- and N-containing components. The greatest reactivity was found for the smallest fraction, which represented 24% of the total charcoal. It is particularly rich in N and potentially susceptible to microbial decomposition. The study demonstrates that properties of charcoal added to soil during wildfires may be reliably discriminated on the basis of particle size.

Low‐Density Lipoprotein Apheresis by Membrane Differential Filtration (Cascade Filtration) via Arteriovenous Fistula Performed in Children With Familial Hypercholesterolemia

Membrane differential filtration (cascade filtration) is an apheresis technique by which atherogenic lipoproteins can be eliminated from plasma on the basis of particle size. In this study, we aim to discuss the efficacy of low-density lipoprotein (LDL) apheresis performed by providing alternative vascular routes in two siblings with familial hypercholesterolemia who did not respond to medical treatment and diet. Of the two siblings, one was nine years old and the other one was three-and-a-half years old. Of the total of 78 apheresis processes performed, 24 were done via a permanent subclavian catheter, 36 were done via a subsequently provided arteriovenous fistula, and 18 were done via an arteriovenous graft. We observed a mean reduction in the plasma levels of total cholesterol (61.6%), LDL cholesterol (65.5%), and high-density lipoprotein cholesterol (38.6%). We noted that cascade filtration apheresis was effective in decreasing the LDL cholesterol in plasma, and no serious complications were noted. The success of the apheresis program depends on well-functioning blood access. An arteriovenous fistula may be the best route for the long-term treatment of familial hypercholesterolemia, which requires complication-free apheresis treatments.

Heterogeneity of high-density lipoprotein in cord blood and its postnatal change

BackgroundSeveral subclasses of HDL are demonstrated to have different roles in atherosclerosis based on adult studies, but the significance of HDL heterogeneity in the fetus and neonate has not been clarified. It has been described that the cholesterol supply from apoE-rich HDL is essential for central nerve system neuron growth. MethodsSixty-five healthy, term, appropriate for gestational age neonates (38 males and 27 females) were included in the study. Serum lipoprotein analyses were performed by HPLC with gel permeation columns, which classified HDL into 5 subgroups (i.e., very large, large, medium, small, and very small) on the basis of particle size. Apolipoprotein A-I, B, and E were also determined by turbidimetric immunoassay. ResultsCord blood has higher very large and very small HDL-cholesterol levels. Cord blood apolipoprotein E was not uniformly distributed in the HDL subclasses, with a strong association with very large HDL-cholesterol levels (males, r=0.548, p<0.001; females, r=0.631, p<0.01). However, the association disappeared by 1 month of age in males; in females, the association remained during the neonatal period. ConclusionsThese results suggest that HDL may play the role of a dominant cholesterol carrier in the human fetus, and very large HDL-cholesterol have some contribution to the neurodevelopment in the fetus and neonates because of the close relationship with apolipoprotein E levels.

Passive optical separation within a 'nondiffracting' light beam

A passive, optical cell sorter is created using the light pattern of a 'nondiffracting' beam-the Bessel beam. As a precursor to cell sorting studies, microspheres are used to test the resolution of the sorter on the basis of particle size and refractive index. Variations in size and, more noticeably, refractive index, lead to a marked difference in the migration time of spheres in the Bessel beam. Intrinsic differences (size, refractive index) between native (unlabeled) cell populations are utilized for cell sorting. The large difference in size between erythrocytes and lymphocytes results in their successful separation in this beam pattern. The intrinsic differences in size and refractive index of other cells in the study (HL60 human promyelocytic leukaemic cells, murine bone marrow, and murine stem/progenitor cells) are not large enough to induce passive optical separation. Silica microsphere tags are attached to cells of interest to modify their size and refractive index, resulting in the separation of labeled cells. Cells collected after separation are viable, as evidenced by trypan blue dye exclusion, their ability to clone in vitro, continued growth in culture, and lack of expression of Caspase 3, a marker of apoptosis.

Chemical and Biological Characteristics of Physically Uncomplexed Organic Matter

Physical fractionation methods are based on the premise that soil organic matter (SOM) can be divided into pools of functional relevance. Physically uncomplexed organic matter (OM) is isolated on the basis of particle size and/or density. Our objective here is to review research on the biological and chemical characteristics of physically uncomplexed OM that demonstrates its value (or otherwise) as a meaningful pool of SOM. Chemical characterization indicates that fractions isolated by size are not identical to those separated by density; even materials separated using variations of a particular fractionation method (i.e., different sizes or different densities) have different chemical and biological properties. Physically uncomplexed OM often contains a substantial portion of whole soil carbon (C) and nitrogen (N) and, compared with the whole soil or heavy fraction, has a wide C/N ratio and high O‐alkyl (i.e., carbohydrates) and low carbonyl (i.e., proteins) C contents. The response of physically uncomplexed OM to changes in land use and management practices is greater than that of other labile OM fractions or the whole soil C and N. Studies to elucidate the nutrient availability of physically uncomplexed OM suggest that it is not an immediate source of nutrients. That the quantity of physically uncomplexed OM is not always related to the amount of plant residue inputs suggests that other factors may control its accumulation in soil. Thus the quantity and the biological and chemical properties of physically uncomplexed OM are affected by the amount, composition, and accessibility of plant residues entering the soil; environmental conditions that may enhance or constrain decomposition; and the fractionation technique used.

Metals leachability from medical waste incinerator fly ash: A case study on particle size comparison

This paper presents the results from a study of metals leachability of medical waste incinerator fly ash in Japan on the basis of particle size. Sequential extraction and Toxicity Characteristic Leaching Procedure (TCLP) analysis were carried out in order to quantify the leaching amount of metals in each categorized particle size. Sequential extraction was also subjected to identify the preference of binding matrix of metals. The results of sequential extraction showed an increase both exchangeable and carbonate associated chromium concentrations in the bigger particle size fractions. Likewise, concentrations of carbonate matrix of arsenic and tin tended to increase in the bigger particle size fractions. In contrast, exchangeable associated cadmium as well as both exchangeable and carbonate matrices of barium were found higher in the smaller particle size fractions. However, no correlation was found in Kendal-tau correlation analysis between particle size of the ash and metals leachability of the TCLP.

Variations in chemical composition and particle size of dune sediments along the west coast of Jutland, Denmark

Geochemical and textural variations in frontal dune sediments along the western coast of Jutland, Denmark, have been investigated in order to identify possible sediment ‘provinces’ and transport pathways. An understanding of sediment sources and sinks is important for both for an understanding of the nature of sedimentary environments and for applied coastal engineering and management purposes. Four coastal sectors were identified on the basis of geochemical composition. One sector is compositionally different from the other three units, having higher concentrations of the trace elements Ni, Cr, V, Sc, Zn, Pb, Ba, Zr and many rare earth elements. Dune sediments on this section of coast also have higher Al 2O 3 to K 2O ratios and lower Al 2O 3 to Fe 2O 3 ratios, reflecting a lower content of feldspar and higher content of heavy minerals. It is inferred that different, or additional, sediment source(s) have supplied sediment to this section of coast. Beach nourishment has contributed to the observed compositional differences, but previous data obtained from the Lodbjerg area indicate that aeolian sands on this section of coast naturally have a relatively high Si, Fe and Ti content, reflecting high quartz / feldspar ratio and relatively high content of heavy minerals, compared with those on other sections of the coast. Frontal dunes along the most northern section show high abundances of K 2O, Rb and Ba, reflecting a relatively high K-feldspar content derived from local sources. Alongshore trends were also identified in the mean particle size and sorting of the frontal dunes, although there is no direct correspondence with the observed geochemical differences. Three coastal units can be identified on the basis of particle size. Frontal dune sediments in the middle section are relatively coarser and less well-sorted than those to the north and south, probably reflecting both the addition of beach nourishment material and greater exposure to strong westerly winds, which are a capable of transporting a wide range of particle sizes. The three units defined on this basis do not correlate directly with the units defined on the basis of geochemical composition.

Usefulness of platelet reactivity before percutaneous coronary intervention in determining cardiac risk one year later

F low cytometric analysis of platelets with the use of epitope-dependent monoclonal antibodies or fluorochrome-labeled ligands provides sensitive and specific assessment of platelet activation.1,2 Assessment of platelet function has not yet been implemented to direct antiplatelet therapy. In contrast, analogous methods are used extensively in the diagnosis and classification of malignancies, as well as to guide antineoplastic therapy.3–5 We have previously reported that flow cytometric analysis of platelet reactivity prospectively identifies those patients at high and low risk of cardiac events during the first 90 days after percutaneous coronary intervention (PCI).6 The aim of the present report was to determine whether this method provides an outcome measure at 6 months and 1 year of follow-up in patients who underwent PCI. • • • The institutional review board of the University of Vermont approved the protocol. All patients provided informed consent. Eligible nonconsecutive patients included those with symptomatic coronary artery disease, a normal creatine kinase and creatine kinase-MB at the time of the procedure, and no pretreatment with intravenous glycoprotein (GP) IIb/IIIa inhibitors. Blood was obtained shortly before PCI for assay of platelet reactivity by flow cytometry. Patients were classified into 1 of 2 groups, high reactivity and low reactivity based on the percentage of platelets capable of binding fibrinogen in response to adenosine diphosphate 0.2 M (activation of platelet GP IIb/IIIa). The median value for all patients was used to stratify the subjects. PCI was performed as clinically mandated. All patients were treated with aspirin 325 mg/daily in addition to clopidogrel 75 mg/daily for 4 weeks. The composite of myocardial infarction (MI), urgent revascularization, and repeat vascularization was assessed after 6 months and 1 year. Follow-up was obtained by telephone calls and chart review at 3, 6, and 12 months. Follow-up was completed in all but 3 of the 112 patients studied ([97.3%] 2 deaths, 1 lost to follow-up). Platelet reactivity was assessed as previously described.6 In brief, blood was anticoagulated with corn trypsin inhibitor. Platelet reactivity was determined with respect to the activation of GP IIb/IIIa. Blood in 5l aliquots was added to microcentrifuge tubes containing HEPES-Tyrodes buffer and fluorochrome-labeled ligands. Adenosine diphosphate (0.2 and 1 M) was used to activate platelets. A peridinin chlorophyll protein conjugated antibody to GP IIIa was used as an activation-independent marker of platelets. Fluorescein isothiocyanate conjugated fibrinogen was used to assess the activation of GP IIb/IIIa. The reaction mixture was incubated at room temperature for 15 minutes. Subsequently, platelets were fixed and red blood cells were lysed with Optilyse-C (Immunotech, Marseille, France). Association of ligands with platelets was determined with a fluorescence-activated cell sorter. Platelets were identified on the basis of particle size and on association with CD61 antibody. Descriptive statistics were implemented for all measures. Comparison of the cumulative incidence of events in high and low reactivity groups was conducted using 2 2 contingency table methods and Fisher’s exact test for dichotomous measures. Comparison of the incidence of clinical outcomes over time in the high and low reactivity groups were From the University of Vermont College of Medicine, Burlington, Vermont. Dr. Kabbani’s address is: 111 Colchester Avenue, Cardiology Unit—Fletcher Allen Health Care—McClure 1, Burlington, Vermont 05401. E-mail: Samer.Kabbani@vtmednet.org. Manuscript received September 13, 2002; revised manuscript received and accepted December 4, 2002. FIGURE 1. Kaplan-Meier curves of the probability of freedom from the composite end point at 1 year. Platelet reactivity was assessed by flow cytometric determination of the capacity of platelets to bind fibrinogen in response to adenosine diphosphate 0.2 M. The divergence of the curves during the initial 24 hours predominantly reflects a higher incidence of periprocedural MI in those with high platelet reactivity. The highest incidence of cardiac events occurred during the first 6 months after PCI.

Breakage behaviour of enzyme granules in a repeated impact test

In many industries, handling or processing of relatively fragile particles takes place and predictions are required whether a significant proportion of the particles will be damaged. These processes have been designed and controlled solely on the basis of particle size and shape. Another parameter that needs to be introduced is particle strength. The stringent environmental laws demand improved particle mechanical quality, which has given rise to the need for a more accurate and fundamental particle strength measurement and its application in modelling and control of particulate processes. Particles need to show good resistance against static and dynamic loads. The present paper deals with the study of breakage behaviour of different enzyme granules subjected to repeated impacts using a new instrument developed at the Delft University of Technology. The impact test involves bombarding the particles against a flat target repeatedly. The main feature of this new test is its ability to impact a large number of particles against a flat target repeatedly, and generate extremely reproducible results. Testing a large number of particles has the advantage of producing statistically correct results. The repeated impacts provide information on the breakage behaviour of the particles based on their history. In the new impact test enzyme granules can undergo very low impact velocities of the order of 5 m s −1. These low impact velocities lead to attrition and chipping of the granules. The current paper presents preliminary results on the breakage behaviour of the new impact test and its basic advantages over already existing tests. Furthermore, experiments were performed on enzyme granules, and the breakage mechanisms determined, depending on the change in size and shape of the particles.

Sources of Cd, Cu, Pb and Zn in biowaste

Biowaste, the separately collected organic fraction of municipal solid waste, can be reused for soil conditioning after composting. In this way, environmentally harmful waste management strategies, such as landfilling or incineration, can be reduced. However, frequent application of composts to soil systems may lead to the accumulation of heavy metals in soils, and therefore legal criteria were laid down in a decree to guarantee the safe use of composts. The heavy metal content of biowaste-composts frequently exceeds the legal standards, and thus raises a conflict between two governmental policies: the recycling of solid waste on the one hand, and the protection of natural ecosystems and public health on the other hand. In this study, the heavy metal content (Cd, Cu, Pb and Zn) of biowaste was compared with the natural background content of Cd, Cu, Pb and Zn in the different constituents of biowaste. For this, the physical entities of biowaste were physically fractionated by wet-sieving and subsequent water-elutriation. In this way, organic and inorganic fractions of different particle sizes were obtained and the content of Cd, Cu, Pb and Zn and the organic matter content of the different fractions were determined. On the basis of particle size, density and visual appearance, the particle-size fractions were assigned to various indoor and outdoor origins of the biowaste. It was found that a large amount of biowaste was not organic, but over 50% was made up of soil minerals due to the collection of biowaste constituents from gardens. The heavy metal content of the various fractions in biowaste was compared with the natural background contents of heavy metals in the constituents of biowaste, i.e. food products, plant material, soil organic matter and soil minerals, by collecting literature data. The heavy metal content in the fractionated physical entities of biowaste corresponded with the natural background concentration of its constituents and indicated that biowaste was not contaminated by other sources. However, the natural background content of biowaste constituents will result in heavy metal contents for biowaste-compost that will exceed the legal standards. It is advised that the legal standards for composts should be critically re-examined. The protection of soil systems could be better guaranteed if the input of heavy metals was evaluated for all inputs of fertilisers and soil conditioners, i.e. animal manures, various types of compost and artificial fertilisers.

Slurry pump side-liner wear: comparison of some laboratory and field results

The current work compares some slurry pump lab wear results with the wear found across different field applications with d85 particle size ranging from 100 to 4000μm. Side-liner wear life data has been collected for two different impeller geometries and two different material classes (cast iron and natural rubber). Different field wear patterns have been photographed and categorised on the basis of particle size. The field wear patterns showed close similarity to the lab wear patterns particularly in the areas of localised gouging. Wear rates are also compared for the different geometries. Overall trend of wear with particle size for the white iron parts was similar to the grey iron lab tests albeit at significantly lower wear rates. In general, the wear with the rubber side-liner was less at smaller particle sizes but greater for particles larger than d85 of about 700μm.

Analytical Techniques for Understanding Nixtamalized Corn Flour: Particle Size and Functionality Relationships in a Masa Flour Sample

ABSTRACTInstant masa flour finds extensive use in the food industry for making tortillas, taco shells, tamales, corn chips, and tortilla chips, and as an ingredient in extruded snacks. Due to lack of standard techniques for measuring masa functionality, processors and end‐users use masa flour particle‐size distribution and rheological characteristics in an attempt to predict its end use. In this study, a commercial masa flour sample was characterized by fractionating on the basis of particle size. Physicochemical and functional properties of masa flour fractions were investigated to establish structure‐composition and functionality relationships. It was observed that Rapid Visco Analyser (RVA) pasting profiles of flour fractions and textural properties of dough prepared on rehydration were related to particle size, yet, upon regrinding, RVA profiles did not change as markedly as expected. Differences in RVA measurements of the sized fractions could not be explained on the basis of hydration rate or total starch content. It was concluded that masa dough textural and RVA characteristics may be influenced by the status of starch polymer structures formed during nixtamalization.

Feeding selectivity and egg production of Calanus helgolandicus in the English Channel

Copepods are able to discriminate between different foods on the basis of particle size and nutritional quality. However, the extent of selective feeding behavior and the mechanisms controlling it in the field are still poorly understood. In this study, we investigated selective feeding behavior and egg production for Calanus helgolandicus feeding on natural phytoplankton (using high‐performance liquid chromatography techniques), and egg production, at a coastal station off Plymouth with the annual phytoplankton cycle from July 1996 to June 1997. The phytoplankton succession included biomass peaks of dinoflagellates, prymnesiophytes, and diatoms. C. helgolandicus showed little selective feeding behavior throughout the study with a slight preference for diatoms. The influence of the diet composition on egg production was analyzed using forward stepwise regression methods. Prymnesiophytes and diatoms were shown to have positive effects whereas the effect of dinoflagellates was negative. The effect of the different phytoplankton peaks is analyzed and discussed in relation to the phytoplankton taxonomic composition and dietary diversity.

The effect of colliery waste on the feeding of the lugworm Arenicola marina

Sandy shores in northeast England that are heavily contaminated by colliery waste (essentially coal particles) have lower species richnesses and diversities than less contaminated shores. Analyses of the sediment utilised putatively as food, the gut contents, and the faecal casts of lugworms Arenicola marina (L.) (Annelida: Polychaeta) from a heavily contaminated site (Newbiggin) and a site lightly contaminated (Seahouses) were performed to determine the effect of colliery waste on the feeding of this deposit-feeder, which has been reported to decline in abundance at contaminated sites. Colliery-waste content of sediment was 10 to 18 times greater at Newbiggin than at Seahouses. At Newbiggin the sediment contained significantly higher levels of colliery waste than did the gut contents or faeces, which were not significantly different from each other. At Seahouses the colliery-waste contents of sediment, gut, and faeces were not significantly different. Particle-size distributions in sediment, gut, and faeces from lugworms at Seahouses were similar, while at Newbiggin the sediment contained a greater proportion of larger particles (>250 μm) than did the gut contents or the faeces. These results suggest that lugworms at heavily contaminated sites are selective feeders, rejecting coal particles perhaps on the basis of particle size. We did not detect selectivity in animals at the less contaminated site. Lugworms from Seahouses, however, avoided burrowing into sediment containing colliery waste both when the waste was on the surface and buried. Lugworms from Newbiggin avoided burrowing into colliery waste only when it was buried. These data suggest a chemosensory response to colliery waste.

Low density lipoprotein apheresis by membrane differential filtration (cascade filtration).

Membrane differential filtration (MDF) is an apheresis technique with which atherogenic lipoproteins can be eliminated from plasma on the basis of particle size. In 52 patients (REMUKAST Study, 1,702 treatments), low density lipoprotein (LDL) cholesterol was decreased by 61%, high density lipoprotein (HDL) cholesterol by 42%, and fibrinogen by 54%. Our own results in 3 patients show decreases of 62%, 31%, and 59%, respectively; lipoprotein (a) (Lp[a]) was reduced by 58%. The elimination of atherogenic lipoproteins was accompanied by a loss of macromolecules (IgM: 55%, IgG: 27%, alpha 2-macroglobulin: 49%) resulting in improved hemorrheologic parameters. Although HDL is eliminated with each apheresis session, pretreatment concentrations of HDL cholesterol increased by 24% during regular apheresis for 1 year (26 patients, REMUKAST Study). However, preapheresis concentrations of other macroglobulins such as immunoglobulins remained decreased compared to concentrations obtained before the first apheresis session (IgM: 34%, IgG: 23%, and IgA: 16%). We conclude that MDF apheresis is an effective method to lower elevated concentrations of atherogenic lipoproteins. The concomitant loss of other macromolecules transiently improves hemorrheology but demands a close monitoring of immunoglobulin concentrations as a safety parameter.