Particle Population Research Articles

Key Signatures of Magnetofossils Elucidated by Mutant Magnetotactic Bacteria and Micromagnetic Calculations.

Magnetotactic bacteria (MTB) produce single‐stranded or multi‐stranded chains of magnetic nanoparticles that contribute to the magnetization of sediments and rocks. Their magnetic fingerprint can be detected in ancient geological samples and serve as a unique biosignature of microbial life. However, some fossilized assemblages bear contradictory signatures pointing to magnetic components that have distinct origin(s). Here, using micromagnetic simulations and mutant MTB producing looped magnetosome chains, we demonstrate that the observed magnetofossil fingerprints are produced by a mixture of single‐stranded and multi‐stranded chains, and that diagenetically induced chain collapse, if occurring, must preserve the strong uniaxial anisotropy of native chains. This anisotropy is the key factor for distinguishing magnetofossils from other populations of natural magnetite particles, including those with similar individual crystal characteristics. Furthermore, the detailed properties of magnetofossil signatures depend on the proportion of equant and elongated magnetosomes, as well as on the relative abundances of single‐stranded and multi‐stranded chains. This work has important paleoclimatic, paleontological, and phylogenetic implications, as it provides reference data to differentiate distinct MTB lineages according to their chain and magnetosome morphologies, which will enable the tracking of the evolution of some of the most ancient biomineralizing organisms in a time‐resolved manner. It also enables a more accurate discrimination of different sources of magnetite particles, which is pivotal for gaining better environmental and relative paleointensity reconstructions from sedimentary records.

Acoustofluidics 24: theory and experimental measurements of acoustic interaction force.

The motion of small objects in acoustophoresis depends on the acoustic radiation force and torque. These are nonlinear phenomena originating from wave scattering, and consist of primary and secondary components. The primary radiation force is the force acting on an object due to the incident field, in the absence of other objects. The secondary component, known as acoustic interaction force, accounts for the interaction among objects, and contributes to the clustering patterns of objects, as commonly observed in experiments. In this tutorial, the theory of acoustic interaction forces is presented using the force potential and partial-wave expansion approaches, and the distinguishing features of these forces such as rotational coupling and non-reciprocity are described. Theoretical results are compared to experimental measurements of interaction forces using a glass micro-capillary setup to explain the practical challenges. Finally, the phenomenon of clustering patterns induced by the close-range interaction of objects is demonstrated to point out the considerations about multiple collision and the predicted clustering patterns entirely due to the interaction force. Understanding the principles of acoustic interaction enables us to develop novel acoustofluidic applications beyond the typical processing of large populations of particles and with focus on the controlled manipulation of small clusters.

Optimized Protocol for Plasma-Derived Extracellular Vesicles Loading with Synthetic miRNA Mimic Using Electroporation.

Extracellular vesicles (EVs) are a population of particles naturally released by cells to transport biological messages, including nucleic acids. Thus, EVs represent an ideal vehicle to deliver therapeutic miRNAs. The current challenge is the development of efficient protocols to load EVs with exogenous miRNAs. Human plasma is an abundant source of EVs which can be manipulated for therapeutic applications. Despite numerous techniques are currently available to load EVs, all of them present issues which limit their clinical application. Among all, electroporation was shown to be superior to other protocols and to efficiently load plasma-derived EVs with miRNAs. However, also the electroporation procedure presents issues that can reduce the miRNA delivery. In this chapter, we describe a protocol to isolate EVs from human plasma, to load synthetic miRNA mimics using electroporation, to evaluate EV integrity and miRNA loading into EVs. Finally, the analysis of EV functionality allows to investigate the ability of engineered EVs to transfer the miRNAs to target cells and to exploit their biological effects.

Collective proposal distributions for nonlinear MCMC samplers: Mean-field theory and fast implementation

Over the last decades, various “non-linear” MCMC methods have arisen. While appealing for their convergence speed and efficiency, their practical implementation and theoretical study remain challenging. In this paper, we introduce a non-linear generalization of the Metropolis-Hastings algorithm to a proposal that depends not only on the current state, but also on its law. We propose to simulate this dynamics as the mean field limit of a system of interacting particles, that can in turn itself be understood as a generalisation of the Metropolis-Hastings algorithm to a population of particles. Under the double limit in number of iterations and number of particles we prove that this algorithm converges. Then, we propose an efficient GPU implementation and illustrate its performance on various examples. The method is particularly stable on multimodal examples and converges faster than the classical methods.

Direct measurement of the pH of aerosol particles using carbon quantum dots.

The pH of aerosol particles remains challenging to measure because of their small size, complex composition, and high acidity. Acidity in aqueous aerosol particles, which are found abundantly in the atmosphere, impacts many chemical processes from reaction rates to cloud formation. Only one technique - pH paper - currently exists for directly determining the pH of aerosol particles, and this is restricted to measuring average acidity for entire particle populations. Other methods for evaluating aerosol pH include filter samples, particle-into-liquid sampling, Raman spectroscopy, organic dyes, and thermodynamic models, but these either operate in a higher pH range or are unable to assess certain chemical species or complexity. Here, we present a new method for determining acidity of individual particles and particle phases using carbon quantum dots as a novel in situ fluorophore. Carbon quantum dots are easily synthesized, shelf stable, and sensitive to pH in the highly acidic regime from pH 0 to pH 3 relevant to ambient aerosol particles. To establish the method, a calibration curve was formed from the ratiometric fluorescence intensity of aerosolized standard solutions with a correlation coefficient (R2) of 0.99. Additionally, the pH of aerosol particles containing a complex organic mixture (COM) representative of environmental aerosols was also determined, proving the efficacy of using carbon quantum dots as pH-sensitive fluorophores for complex systems. The ability to directly measure aerosol particle and phase acidity in the correct pH range can help parametrize atmospheric models and improve projections for other aerosol properties and their influence on health and climate.

A New Discrete Implicit Monte Carlo Scheme for Simulating Radiative Transfer Problems

Abstract We present a new algorithm for radiative transfer—based on a statistical Monte Carlo approach—that does not suffer from teleportation effects, on the one hand, and yields smooth results, on the other hand. Implicit Monte Carlo (IMC) techniques for modeling radiative transfer have existed from the 1970s. When they are used for optically thick problems, however, the basic algorithm suffers from “teleportation” errors, where the photons propagate faster than the exact physical behavior, due to the absorption-blackbody emission processes. One possible solution is to use semianalog Monte Carlo, in its new implicit form (ISMC), which uses two kinds of particles, photons and discrete material particles. This algorithm yields excellent teleportation-free results, but it also produces noisier solutions (relative to classic IMC), due to its discrete nature. Here, we derive a new Monte Carlo algorithm, Discrete Implicit Monte Carlo (DIMC), which also uses the idea of two kinds of discrete particles, and thus does not suffer from teleportation errors. DIMC implements the IMC discretization and creates new radiation photons for each time step, unlike ISMC. Using the continuous absorption technique, DIMC yields smooth results like classic IMC. One of the main elements of the algorithm is the avoidance of the explosion of the particle population, by using particle merging. We test the new algorithm on 1D and 2D cylindrical problems, and show that it yields smooth, teleportation-free results. We finish by demonstrating the power of the new algorithm on a classic radiative hydrodynamic problem—an opaque radiative shock wave. This demonstrates the power of the new algorithm for astrophysical scenarios.

Quantifying the Contribution of Lipoprotein (a) to Atherogenic Lipoprotein Burden: A Novel Particle-Based Approach

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> David and June Trone Family Foundation AHA NIH. <h3>Background/Synopsis</h3> LDL cholesterol [LDL-C] on clinical lipid panels includes cholesterol from LDL, IDL, and Lipoprotein (a). Contributions from Lp(a) cholesterol [Lp(a)-C] to LDL-C can influence the diagnosis and management of dyslipidemias. Currently, there is no commercially available assay to accurately measure Lp(a)-C and we showed previously that estimating Lp(a)-C using fixed conversion factors tends to overestimate the contribution of Lp(a)-C to LDL-C. Moreover, comparing Lp(a)-C with LDL-C alone may miss contributions of other atherogenic lipoproteins to overall atherosclerotic cardiovascular disease risk. <h3>Objective/Purpose</h3> To more accurately quantify how Lp(a) compares to the overall atherogenic burden and circumvent inaccuracies associated with cholesterol mass estimation, we demonstrate a novel particle-based approach to compare Lp(a) concentration [Lp(a)-P] with all atherogenic particles (referred to as non-HDL-P), making use of widely available assays already employed in clinical practice. <h3>Methods</h3> Using the Very Large Database of Lipids, we extracted data from individuals with measured Lp(a)-P (nmol/L) and apoB (mg/dL). The concentration of all atherogenic particles (non-HDL-P) was calculated using the molecular weight of apoB which is preserved across individuals, enabling accurate conversion from mass to molar concentration. The fraction of Lp(a)-P/non-HDL-P was calculated and stratified by increasing Lp(a)-P deciles across sex, age, triglycerides, LDL-C, and non-HDL-C. <h3>Results</h3> 158,260 patients from the Very Large Database of Lipids were included. The percentage of Lp(a)-P/non-HDL-P increased at higher Lp(a)-P concentrations. Mean Lp(a)-P/non-HDL-P for the study population was approximately 3%, but was as high as 15% in the top Lp(a)-P decile. When stratified by sex, fractions mirrored those seen in the general population. When stratified by age, the highest fractions of Lp(a)-P/non-HDL-P were observed among the youngest and oldest ages. We observed that Lp(a)-P/non-HDL-P decreased with rising LDL-C and triglycerides, owing to larger contributions from LDL and VLDL to the total atherogenic population. <h3>Conclusions</h3> We demonstrate the feasibility and simplicity of comparing Lp(a) particles with the total atherogenic particle population, making use of commercially available assays widely used in clinical practice. Importantly, a molar approach avoids previously demonstrated inaccuracies associated with Lp(a)-C estimations. Moreover, this approach may enrich assessment of residual risk mediated by Lp(a) by comparing it against the sum total of atherogenic particles encompassed by the non-HDL family. Future investigation is needed to identify clinically meaningful thresholds for Lp(a)-P/non-HDL-P, particularly with the ongoing development of targeted Lp(a) therapies.

Many-Objective Quantum-Inspired Particle Swarm Optimization Algorithm for Placement of Virtual Machines in Smart Computing Cloud.

Particle swarm optimization algorithm (PSO) is an effective metaheuristic that can determine Pareto-optimal solutions. We propose an extended PSO by introducing quantum gates in order to ensure the diversity of particle populations that are looking for efficient alternatives. The quality of solutions was verified in the issue of assignment of resources in the computing cloud to improve the live migration of virtual machines. We consider the multi-criteria optimization problem of deep learning-based models embedded into virtual machines. Computing clouds with deep learning agents can support several areas of education, smart city or economy. Because deep learning agents require lots of computer resources, seven criteria are studied such as electric power of hosts, reliability of cloud, CPU workload of the bottleneck host, communication capacity of the critical node, a free RAM capacity of the most loaded memory, a free disc memory capacity of the most busy storage, and overall computer costs. Quantum gates modify an accepted position for the current location of a particle. To verify the above concept, various simulations have been carried out on the laboratory cloud based on the OpenStack platform. Numerical experiments have confirmed that multi-objective quantum-inspired particle swarm optimization algorithm provides better solutions than the other metaheuristics.

Characteristics of Particles Emitted from Waste Fires-A Construction Materials Case Study.

This study aimed to determine the relative densities of populations of particles emitted in fire experiments of selected materials through direct measurement and parametrization of size distribution as number (NSD), volume (VSD), and mass (MSD). As objects of investigation, four typical materials used in construction and furniture were chosen: pinewood (PINE), laminated particle board (LPB), polyurethane (PUR), and poly(methyl methacrylate) (PMMA). The NSD and VSD were measured using an electric low-pressure impactor, while MSD was measured by weighing filters from the impactor using a microbalance. The parametrization of distributions was made assuming that each distribution can be expressed as the sum of an arbitrary number of log-normal distributions. In all materials, except PINE, the distributions of the particles emitted in fire experiments were the sum of two log-normal distributions; in PINE, the distribution was accounted for by only one log-normal distribution. The parametrization facilitated the determination of volume and mass abundances, and therefore, the relative density. The VSDs of particles generated in PINE, LPB, and PUR fires have similar location parameters, with a median volume diameter of 0.2–0.3 µm, whereas that of particles generated during PMMA burning is 0.7 µm. To validate the presented method, we burned samples made of the four materials in similar proportions and compared the measured VSD with the VSD predicted based on the weighted sum of VSD of raw materials. The measured VSD shifted toward smaller diameters than the predicted ones due to thermal decomposition at higher temperatures.

Nonlinear Enhancement of Radiative Absorption by Black Carbon in Response to Particle Mixing Structure

AbstractBlack carbon (BC) strongly absorbs solar radiation, contributing to global warming. Absorption enhancement of BC particles is difficult to quantify due to an inadequate representation of their complex morphology and mixing structures, as well as interaction with radiation. Here, we apply a 3D method accounting for detailed BC mixing structures to predict the absorption enhancement of individual BC particles (Eabs) and the total BC particle population (Eabs, bulk). The diverse range of mixing structures in individual BC particles leads to variable Eabs that could hardly be predicted by empirical approximations. We find that the volume proportion of the BC embedded in coating (F) determines Eabs when the particle to BC core diameter ratio (Dp/Dc) is larger than 2.0. Our findings reveal the potential mechanism behind the differences in observed and modeled Eabs, bulk. The framework builds a bridge connecting the microscopic mixing structure of individual BC particle with Eabs, bulk.

Interaction between long-period ULF waves and charged particle in the magnetosphere: theory and observations (overview)

The paper reviews the current state of the problem of interaction between long-period ultra-low-frequency (ULF) waves and high-energy particles. We consider elements of the theory of energy exchange between waves and particles, particle transport across magnetic shells under the influence of the electromagnetic field of a wave, the acceleration of radiation belt particles by both resonant and non-resonant mechanisms. We examine the mechanisms of generation of azimuthally-small-scale ULF waves due to instabilities arising from the wave–particle resonance. The cases of Alfvén, drift-compressional, and drift-mirror waves are analyzed. It is noted that due to the lack of a detailed theory of drift-mirror modes, the possibility of their existence in the magnetosphere cannot be taken as a proven fact. We summarize experimental data on the poloidal and compression ULF waves generated by unstable populations of high-energy particles. We investigate the mechanisms of modulation of energetic particle fluxes by ULF waves and possible observational manifestations of such modulation. Methods of studying the structure of waves across magnetic shells by recording fluxes of resonant particles with a finite Larmor radius are discussed.

Взаимодействие длиннопериодных УНЧ-волн и заряженных частиц в магнитосфере: теория и наблюдения (обзор)

The paper reviews the current state of the problem of interaction between long-period ultra-low-frequency (ULF) waves and high-energy particles. We consider elements of the theory of energy exchange between waves and particles, particle transport across magnetic shells under the influence of the electromagnetic field of a wave, the acceleration of radiation belt particles by both resonant and non-resonant mechanisms. We examine the mechanisms of generation of azimuthally-small-scale ULF waves due to instabilities arising from the wave–particle resonance. The cases of Alfvén, drift-compressional, and drift-mirror waves are analyzed. It is noted that due to the lack of a detailed theory of drift-mirror modes, the possibility of their existence in the magnetosphere cannot be taken as a proven fact. We summarize experimental data on the poloidal and compression ULF waves generated by unstable populations of high-energy particles. We investigate the mechanisms of modulation of energetic particle fluxes by ULF waves and possible observational manifestations of such modulation. Methods of studying the structure of waves across magnetic shells by recording fluxes of resonant particles with a finite Larmor radius are discussed.

Experimental investigation of sedimentation behaviour using cerium oxalate particles in oxalic‐nitric acid medium

AbstractSettling behaviour of cerium oxalate particles in the solution was investigated by batch settling tests. The settling curves were experimentally generated for different overall solid fractions (OSF), initial dispersion height (ht) and batch cylinder diameter (d). Settling curves were analysed to obtain bulk settling velocity, and it was observed that bulk settling velocity decreases with increase in OSF and remains unchanged with change in cylinder diameter. Bulk settling velocity was found more or less same with increase in initial suspension height as long as the OSF was maintained constant. The particle settling time is delayed at higher OSF due to dense particle population as the movement of one particle is affected by the presence of neighbouring particle. Regression analysis of the settling curve was performed to identify suitable mathematical model. Two parameter based model was found to represent the settling curve better in comparison to three and five parameter based models. Applicability of dispersion number for characterizing the solid–liquid suspension was checked, and it was found that the dispersion number was not unique for the solid‐liquid system where it was influenced by the operating and dimensional parameters.

Evaluating the Impacts of Cloud Processing on Resuspended Aerosol Particles After Cloud Evaporation Using a Particle‐Resolved Model

AbstractAerosol particles undergo physical and chemical changes during cloud processes. In this work, we quantified the changes in aerosol mixing state using a particle‐resolved model. To this end, we coupled the particle‐resolved aerosol model PartMC‐MOSAIC with the aqueous chemistry module CAPRAM 2.4 and designed cloud parcel simulations that mimicked several cloud cycles that a particle population may be exposed to in polluted urban environments. With ammonium nitrate and ammonium sulfate added to the activated particles, after the cloud evaporated, the activation potential of the resuspended aerosol particles increased for supersaturation thresholds lower than the maximum supersaturation attained in the cloud. Formation of sulfate and nitrate increased the internally mixed state of all particle populations, quantified by the mixing state index χ. The change of aerosol mixing state due to aqueous‐phase chemistry was related to the fraction of activated particles. For a case with low aerosol number concentration, where the activated fraction was up to 60%, χ increased by up to 50 percentage points after cloud processing, reaching an almost completely internal mixture. In contrast, for a case with high aerosol emissions and activated fraction of less than 20%, the increase in χ was less than 20 percentage points, and χ remained below 80% after cloud processing. The change in aerosol mixing state caused by coagulation within the cloud parcel was negligible. These findings highlight the complex influence of cloud processing on particle properties.

Cross-Energy Couplings from Magnetosonic Waves to Electromagnetic Ion Cyclotron Waves through Cold Ion Heating inside the Plasmasphere.

Using a novel wave-particle interaction analysis, we show observational evidence of energy transfer from fast magnetosonic waves (MSWs) to low-energy protons in the magnetosphere. The analysis clearly indicates that the transferred proton energies are further converted to excite electromagnetic ion cyclotron waves. Since MSWs are excited by hot ions, cross-energy coupling of ions occurs through MSWs. The result also suggests a new energy transfer path of exciting electromagnetic ion cyclotron waves in the magnetosphere, and a complex interplay between various wave modes and particle populations.

A hybrid sectional moment projection method for discrete population balance dynamics involving inception, growth, coagulation and fragmentation

A new and efficient sectional method is developed and presented in this work. This new method, namely hybrid sectional moment projection method, seeks to combine the techniques of moment projection method and sectional method in a flexible and accurate way. It adopts the concept of weighted particles from moment projection method to handle the particle population dynamics. Special treatment is made on the assignment of these weighted particles within each section so that the accumulation of particles at the smallest size can be better described. The performance of hybrid sectional moment projection method has been tested by comparing with the fixed pivot method and conventional sectional quadrature method of moments in handling a number of particle processes including inception, growth, coagulation and fragmentation. Results suggest that the proposed new method is highly robust and accurate. It is able to well predict the evolution of particle population under various conditions. Especially, it is superior to other sectional methods in the treatment of particle fragmentation process.

Multiple accelerated particle populations in the Cygnus Loop with Fermi-LAT

Context. The Cygnus Loop (G74.0-8.5) is a very well-known nearby supernova remnant (SNR) in our Galaxy. Thanks to its large size, brightness, and angular offset from the Galactic plane, it has been studied in detail from radio to γ-ray emission. The γ-rays probe the populations of energetic particles and their acceleration mechanisms at low shock speeds. Aims. We present an analysis of the γ-ray emission detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope over 11 yr in the region of the Cygnus Loop. Methods. We performed detailed morphological and spectral studies of the γ-ray emission toward the remnant from 100 MeV to 100 GeV and compared it with X-ray, UV, optical, and radio images. The higher statistics with respect to the previous studies enabled us to decompose the emission from the remnant into two morphological components to model its nonthermal multiwavelength emission. Results. The extended γ-ray emission is well correlated with the thermal X-ray and UV emission of the SNR. Our morphological analysis reveals that a model considering two contributions from the X-ray and the UV emission regions is the best description of the γ-ray data. Both components show a curved spectrum, but the X-ray component is softer and more curved than the UV component, suggesting a different physical origin. The multiwavelength modeling of emission toward the SNR suggests that the nonthermal radio and γ-ray emission associated with the UV component is mostly due to the reacceleration of preexisting cosmic rays by radiative shocks in the adjacent clouds, while the nonthermal emission associated with the X-ray component arises from freshly accelerated cosmic rays.

Application of Dynamic and Static Light Scattering for Size and Shape Characterization of Small Extracellular Nanoparticles in Plasma and Ascites of Ovarian Cancer Patients.

In parallel to medical treatment of ovarian cancer, methods for the early detection of cancer tumors are being sought. In this contribution, the use of non-invasive static (SLS) and dynamic light scattering (DLS) for the characterization of extracellular nanoparticles (ENPs) in body fluids of advanced serous ovarian cancer (OC) and benign gynecological pathology (BP) patients is demonstrated and critically evaluated. Samples of plasma and ascites (OC patients) or plasma, peritoneal fluid, and peritoneal washing (BP patients) were analyzed. The hydrodynamic radius (Rh) and the radius of gyration (Rg) of ENPs were calculated from the angular dependency of LS intensity for two ENP subpopulations. Rh and Rg of the predominant ENP population of OC patients were in the range 20–30 nm (diameter 40–60 nm). In thawed samples, larger particles (Rh mostly above 100 nm) were detected as well. The shape parameter ρ of both particle populations was around 1, which is typical for spherical particles with mass concentrated on the rim, as in vesicles. The Rh and Rg of ENPs in BP patients were larger than in OC patients, with ρ ≈ 1.1–2, implying a more elongated/distorted shape. These results show that SLS and DLS are promising methods for the analysis of morphological features of ENPs and have the potential to discriminate between OC and BP patients. However, further development of the methodology is required.

Integration of hybrid controller for power quality improvement in photo-voltaic/wind/battery sources

Renewable Energy Sources (RES) are currently being used on a larger scale to support and satisfy the higher energy demands caused by industrialization and population growth. Therefore, the power generation has to be increased at a greater speed to meet the daily user needs for improvement in lifestyle. The electric utilities and system operators face a tough challenge due to the rise in the number of consumers of power systems and the unpredictable nature of the electric load. Therefore, an effective Energy Management System (EMS) is developed using a combination of Modified Flower Pollination Algorithm (MFPA) and Modified Perturb and Observe (MP&O) method. Three different systems namely: RES Photovoltaic (PV) module, wind turbine, and battery are used to create an effective EMS. MFPA extracts more power from the PV panel by providing less scaling factor. Then it is utilized to increase the initialized population of particles to enhance step size and reset the position of particles. Furthermore, MFPA is used to effectively control the switching between the wind turbine and battery storage system. Furthermore, the MP&O method is used to trigger the switch of the DC-DC converter to achieve stable power from the PV/wind/battery system. The MFPA-MP&O controller is compared with three standard controller combinations FPA-P&O, FPA-MP&O and MFPA-P&O and is also compared with existing RES designs that are: MPCP-MPVP, Fuzzy Logic Control – Proportional Integral (FLC-PI), and MPPVC. Total Harmonic Distortion (THD) of MFPA-MP&O controller is 0.40%, which is less when compared with the MPCP-MPVP, FLC-PI and MPPVC RES designs.

Foam fractionation of a recombinant biosurfactant apolipoprotein

Locusta migratoria apolipophorin III (apoLp-III) possesses the ability to exist as a water soluble amphipathic α-helix bundle and a lipid surface seeking apolipoprotein. The intrinsic ability of apoLp-III to transform phospholipid vesicles into reconstituted discoidal high-density lipoproteins (rHDL) has led to myriad applications. To improve the yield of recombinant apoLp-III, studies were performed in a bioreactor. Induction of apoLp-III expression generated a protein product that is secreted from E. coli into the culture medium. Interaction of apoLp-III with gas and liquid components in media produced large quantities of thick foam. A continuous foam fractionation process yielded a foamate containing apoLp-III as the sole major protein component. The yield of recombinant apoLp-III was ~0.2 g / liter bacterial culture. Mass spectrometry analysis verified the identity of the target protein and indicated no modifications or changes to apoLp-III occurred as a result of foam fractionation. The functional ability of apoLp-III to induce rHDL formation was evaluated by incubating foam fractionated apoLp-III with phosphatidylcholine vesicles. FPLC size exclusion chromatography revealed a single major population of particles in the size range of rHDL. The results described offer a novel approach to bioreactor-based apoLp-III production that takes advantage of its intrinsic biosurfactant properties.