Particle Size Measurements Research Articles

Current Knowledge and Challenges of Particle Size Measurements of Mainstream E-Cigarette Aerosols and Their Implication on Respiratory Dosimetry

The E-cigarette has been promoted as an alternative nicotine delivery device with potentially fewer toxicant emissions. The objective of this review is to summarize the current knowledge on the particle size distribution (PSD) of e-cigarette emissions and to analyze the knowledge gaps between existing particle size measurements and the vision toward harm reduction from e-cigarette use. Here, we focus on firstly describing the physical parameters used to characterize PSD, followed by comparing particle size measurement approaches, investigating the factors that impact the PSD of e-cigarette mainstream aerosols, and conclude by linking size distribution to the respiratory dosimetry by demonstrating the modeling results of particle deposition in the respiratory tract. This review calls for a harmonized testing protocol to conduct inter-comparisons and further understand e-cigarette particle sizes. Among the influencing factors investigated, puff topography, operation power, flavorings, PG/VG ratio, and nicotine strength impose a substantial impact on the PSD, but the underlying mechanisms have not yet been fully investigated. The effects brought by the type of device refill and nicotine are yet inconclusive due to lack of evidence. Coil aging has no significant impact on the PSD of e-cigarette aerosols within the coil lifetime. Lastly, while computational models of particle deposition have been adopted to profile the deposition of e-cigarette mainstream emissions, existing models have limited applicability and generality when dealing with e-cigarette aerosols that have high volatility and hygroscopicity, which can dynamically evaporate or grow during the transport process. Additionally, the size-dependent chemical composition (e.g., nicotine and harmful and potentially harmful constituents) of e-cigarette aerosols is unknown, impeding the understanding of the health effects of e-cigarette use. Therefore, it is essential for future studies to bridge these knowledge gaps and unveil the mechanisms determining PSD and respiratory deposition.

Effects of Different Nanoparticles on Microbes.

Nanoparticles widely exist in nature and may be formed through inorganic or organic pathways, exhibiting unique physical and chemical properties different from those of bulk materials. However, little is known about the potential consequences of nanomaterials on microbes in natural environments. Herein, we investigated the interactions between microbes and nanoparticles by performing experiments on the inhibition effects of gold, ludox and laponite nanoparticles on Escherichia coli in liquid Luria-Bertani (LB) medium at different nanoparticle concentrations. These nanoparticles were shown to be effective bactericides. Scanning electron microscopy (SEM) images revealed the distinct aggregation of cells and nanoparticles. Transmission electron microscopy (TEM) images showed considerable cell membrane disruption due to nanoparticle accumulation on the cell surfaces, resulting in cell death. We hypothesized that this nanoparticle accumulation on the cell surfaces not only disrupted the cell membranes but also physically blocked the microbes from accessing nutrients. An iron-reducing bacterium, Shewanella putrefaciens, was tested for its ability to reduce the Fe (III) in solid ferrihydrite (HFO) or aqueous ferric citrate in the presence of laponite nanoparticles. It was found that the laponite nanoparticles inhibited the reduction of the Fe (III) in solid ferrihydrite. Moreover, direct contact between the cells and solid Fe (III) coated with the laponite nanoparticles was physically blocked, as confirmed by SEM images and particle size measurements. However, the laponite particles had an insignificant effect on the extent of aqueous Fe (III) bioreduction but slightly enhanced the rate of bioreduction of the Fe (III) in aqueous ferric citrate. The slightly increased rate of bioreduction by laponite nanoparticles may be due to the removal of inhibitory Fe (II) from the cell surface by its sorption onto the laponite nanoparticle surface. This result indicates that the scavenging of toxic heavy metals, such as Fe (II), by nanoparticles may be beneficial for microbes in the environment. On the other hand, microbial cells are also capable of detoxifying nanoparticles by coagulating nanoparticles with extracellular polymeric substances or by changing nanoparticle morphologies. Hence, the interactions between microbes and nanoparticles in natural environments should receive more attention.

Inline Particle Size Analysis during Technical-Scale Processing of a Fermented Concentrated Milk Protein-Based Microgel Dispersion: Feasibility as a Process Control

Particle size is not only important for the sensory perception of fat-free fermented concentrated milk products, but also for processing operations because of the direct relationship with apparent viscosity. The aim of this study was to apply inline particle size analysis using focused beam reflectance measurement (FBRM) to obtain real-time information regarding the particle size of a fat-free fermented concentrated milk product, namely, fresh cheese. By comparing inline particle size data to offline particle size, apparent viscosity, protein content and processing information, the potential to use inline particle size analysis as a process monitoring and control option during fresh cheese production was assessed. Evaluation of inline particle size after fermentation and before further processing, e.g., after a buffering tank, shows promise as a means to control variance of product entering downstream processing and, thus, improve final product consistency over time. Measurement of inline particle size directly before filling could allow for precise control of final product characteristics by the use of mechanical or mixing devices placed before the inline measurement. However, attention should be given to the requirements of the inline measurement technology for accurate measurement, such as product flow rate and pressure.

Dynamic Light Scattering: A Powerful Tool for In Situ Nanoparticle Sizing

Due to surface effects and quantum size effects, nanomaterials have properties that are vastly different from those of bulk materials due to surface effects. The particle size distribution plays an important role in chemical and physical properties. The measurement and control of this parameter are crucial for nanomaterial synthesis. Dynamic light scattering (DLS) is a fast and non-invasive tool used to measure particle size, size distribution and stability in solutions or suspensions during nanomaterial preparation. In this review, we focus on the in situ sizing of nanomaterial preparation in the form of colloids, especially for metal oxide nanoparticles (MONs). The measuring principle, including an overview of sizing techniques, advantages and limitations and theories of DLS were first discussed. The instrument design was then investigated. Ex-situ and in situ configuration of DLS, sample preparations, measurement conditions and reaction cell design for in situ configuration were studied. The MONs preparation monitored by DLS was presented, taking into consideration both ex situ and in situ configuration.

Colloidal Processing and Sintering of Alumina and Zirconia Fine Particles Using New Microbial Dispersant

Application of new microbial dispersant to colloidal processing of fine powders of zirconia and alumina was conducted for obtaining fine-grained microstructures. Well-dispersed aqueous suspensions of the fine powders were prepared by adding appropriate amount of new microbial dispersant. The suspensions were characterized by measuring particle size, zeta-potential and rheological properties. Dense green bodies of zirconia and alumina were obtained by slip casting of the suspensions and further CIP treatment. Low-temperature densification was observed, and dense and fine-grained sintered bodies were obtained.

Migration risk of Escherichia coli O157:H7 in unsaturated porous media in response to different colloid types and compositions

The vadose zone is a critical zone for microbial entry into the subsurface environment, and various types of inorganic and organic colloids can affect the migration of pathogenic bacteria. In the study, we explored the migration behavior of Escherichia coli O157:H7 with humic acids (HA), iron oxides (Fe2O3) or their mixture, uncovering their migration mechanisms in the vadose zone. The effect of complex colloids on the physiological properties of E. coli O157:H7 was analyzed based on the measured particle size, zeta potential and contact angle. HA colloids significantly promoted the migration of E. coli O157:H7, where Fe2O3 was opposite. The migration mechanism of E. coli O157:H7 with HA and Fe2O3 is obviously different. Multiple colloids dominated by organic colloid will further highlight its promoting effect on E. coli O157:H7 under the guidance of electrostatic repulsion due to the influence of colloidal stability. Multiple colloids dominated by metallic colloid will inhibit the migration of E. coli O157:H7 under the control of capillary force due to the restriction of contact angle. The risk of secondary release of E. coli O157:H7 can be effectively reduced when the ratio of HA/Fe2O3 is ≥ 1. Combining this conclusion with the distribution characteristics of soil in China, an attempt was made to analyse the migration risk of E. coli O157:H7 on a national scale. In China, from north to south, the migration capacity of E. coli O157:H7 gradually decreased, and the risk of secondary release gradually increased. These results provide ideas for the subsequent study of the effect of other factors on the migration of pathogenic bacteria on a national scale and provide risk information about soil colloids for the construction of pathogen risk assessment model under comprehensive conditions in the future.

Nanostructured Ni(Zn)–Al2O3 cermet particle synthesis in high-energy mechanical alloying method (CG-3:IL07)

Ceramic-metallics (cermets) have emerged as an important class of composite material combining favorable properties of their constitutive phases. In this work, nanostructured cermet Ni(Zn)–Al2O3 composition was synthesized using the high-energy mechanical alloying (HE-MA) method to be deployed as a cold spray deposition powder feedstock. Pre-milled Ni(Zn) alloy particles were mechanically mixed followed by milling in a SPEX™ 8000 M High Energy Ball Mill at a fixed 1050 rpm. The material design-of-experiment (DoE) involved two design compositions (30 wt% and 50 wt% α-alumina) with two substitutional alloy compositions, Ni(5 wt%Zn) and Ni(10 wt%Zn), along with milling time as a process variable. Microstructural characterization confirmed the embedment of nanoscale Al2O3 grain in micron-scale Ni(Zn) alloy particles. Additionally, EBSD analysis of Ni(Zn) alloy particles revealed that Ni(5 wt%Zn) experienced more uniform plastic deformation, work hardening and subsequent fracturing when compared to Ni(10 wt% Zn) alloy particles. The particle size measurement was carried out by laser diffraction showed that the cermet particles milled for 4 h had the desired size range for the objective of cold spraying. Also, the embedment of alumina into the Ni(Zn) alloy matrix and thereby, homogenization of cermet particles enhanced with the increase in milling time.

Preparation of nano disperse dyes using sulfomethylated lignin: Effects of sulfonic group contents

The molecular simulation software was firstly applied to analyze the adsorption of sulfomethylated lignin (SAL) on dye surfaces. Then, SALs with different sulfonic group contents were prepared and characterized by FTIR, NMR, EA and GPC measurements using alkali lignin (AL) as raw materials and sodium sulfite as sulfonating agents. Next, SAL1.53 was determined to the optimum dispersant by TSI, particle size and thermal storage stability measurements, which had the smallest particle size of 173 nm and highest stability, comparable to the commercial Reax 85A lignin dispersant and basically satisfying the requirement of nano disperse dyes used in the digital printing technology. QCM, AFM and zeta potential results indicated that as the sulfonic group content of SAL increased, the adsorption mass, rigidity of the adsorbed layer, adsorption force and absolute zeta potential value all showed a gradually increasing tendency due to an enhanced hydrophilicity, and thus a decreased intermolecular agglomeration and an increased molecular chain stretching degree. A maximum was observed for SAL1.53. This research not only provided a novel approach to the preparation of high-performance lignin dispersants for nano disperse dyes, but also would broaden the high value-added industrial applications of biomass lignin into the digital printing and dyeing field.

Preparation and Performance Analysis of a Dimension-Controlled Nano-Drag-Reducing Agent for Low-Permeability Reservoirs

Graphene oxide (GO), as a derivative of graphene, is rich in reactive functional groups on its surface for modification, and the modified graphene oxide (M-GO) has excellent special properties. In this paper, the improved Hummer’s method was used to analyze GO by adjusting the amount of oxidant (potassium permanganate), oxidation time, and temperature, using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and laser particle size measurement. The successful synthesis of dimension-controlled GO in the range of 630–1000 nm was confirmed. On this basis, modified graphene oxide (O-M-GO) was prepared by grafting octadecyltrimethoxysilane (OCT). The successful synthesis of O-M-GO was confirmed by FT-IR and XRD. Through a contact angle test, the contact angle of GO before modification was 80 ± 0.5° and that of O-M-GO after modification was 105 ± 0.5°. Combined with SEM analysis, the change in the wettability of O-M-GO was clarified. Core flow test results showed that after O-M-GO was injected into the core, the subsequent brine injection pressure decreased by 14.21%, and the permeability was 1.166 times that before the brine injection. When the injection concentration was 50 mg/L, the drag reduction rate was 14%.

Influence of the dynamic behaviour of impactor surfaces on particulate matter emission measurements with electrical low pressure impactors

Cascade impactors, such as the Dekati electrical low pressure impactor (ELPI+), are useful measuring devices as they can classify particles per size range based on their inertial behaviour. However, various mechanisms, such as particle loss and particle bounce, make the measured particle size distribution to diverge from the real distribution. Moreover, some of these mechanisms depend on the amount of particles that have already been collected in an impactor stage and consequently the collection efficiency of a stage may be time-dependent. In this work, such mechanisms are investigated and their impact on the performed measurements is assessed. The use of greased and ungreased aluminium collection substrates and porous sintered impactor plates were extensively tested in the ELPI+. The aluminium substrates, regardless of the initial greasing, show an exponential decrease in total number concentration and an exponential increase in geometric mean particle diameter with increasing particle load on the substrates. This is the result of an exponential concentration decrease of the stages that collect particles smaller than the accumulation peak and a concentration increase of the stages that collect larger particles. The effect is attributed to the decrease in particle bounce with increasing particle loading. On the other hand, the sintered impactor plates show barely any time-dependent collection behaviour.

Antioxidant and Antimicrobial Properties of Hydrolysed Collagen Nanofibers Loaded with Ginger Essential Oil.

Hydrolysed collagen obtained from bovine leather by-products were loaded with ginger essential oil and processed by the electrospinning technique for obtaining bioactive nanofibers. Particle size measurements of hydrolysed collagen, GC-MS analysis of ginger essential oil (EO), and structural and SEM examinations of collagen nanofibers loaded with ginger essential oil collected on waxed paper, cotton, and leather supports were performed. Antioxidant and antibacterial activities against Staphylococcus aureus and Escherichia coli and antifungal activity against Candida albicans were also determined. Data show that the hydrolysed collagen nanofibers loaded with ginger EO can be used in the medical, pharmaceutical, cosmetic, or niche fields.

Effects of W/O Nanoemulsion on Improving the Color Tone of Beijing Roast Duck.

Traditional Beijing roast duck is often brushed with a high concentration of maltose solution (15% w/v) and shows ununiform color after roasting. A novel W/O nanoemulsion was applied to improve the color tone of Beijing roast ducks and, meanwhile, reduced the amount of sugar. For the W/O emulsion, 3% (w/v) xylose solution as the aqueous phase, soybean oil as the oil phase, and polyglycerol polyricinoleate (PGPR) and whey protein isolate (WPI) as co-emulsifiers were fabricated by high-pressure homogenization. Particle size measurement by Zetasizer and stability analysis by Turbiscan stability analyzer showed that WPI as co-emulsifier and internal aqueous phase at pH 9 decreased the droplet size and improved the emulsion stability. In addition, by color difference evaluation, the W/O nanoemulsion improved the Maillard reaction degree and color tone of Beijing roast duck. The molecular structure and key composition of pigments on the surface of Beijing roast duck skins were also identified and characterized by UV-vis spectroscopy and UHPLC-MS. This study creatively offers theoretical guidance for increasing applications of W/O-nanoemulsion-based Maillard reaction in the roast food industry, especially for the development of reduced-sugar Beijing roast duck with uniform and desired color satisfying consumers' acceptance and marketability.

Salt doping of hyaluronic acid glycopolymer biocondensates.

Biocondensates are largely studied with regard to intracellular components, while recognition of the formation of extracellular biocondensates are emerging, such as for cell surface heparan sulfate binding with basic fibroblast growth factor. This study analyzed the formation of biocondensates in vitro between the ubiquitous extracellular component, hyaluronan an anionic glycosaminoglycan, and cationic derivitized polyglucosamines known to bind to mucosal interfaces. The effect of molecular weight and net charge ratio was studied using a combination of microscopy, turbidity, laser diffraction particle sizing and zeta potential measurements. These analyses revealed that molecular weight affected the ability to form biocondensates while the surface composition of the condensates was altered by the net charge ratio of the macromolecules. The role of salt counterions in the biocondensate also shows trends of ion-pairing that are consistent with coacervate-salt-doping theory and a description of condensates as so-called complex coacervate micelles with surface brushes akin to soft colloidal particles. The salt type and concentrations are also observed to affect the condensate size and surface potential. An electrostatic model of the structures describes how ion-partitioning depends on the spatial variation of the dielectric permittivity to establish steady-state Born-hydration energy and electrostatic potential gradients. Together this study adds to our understanding of the formation of extracellular biomolecular condensates.

Relating 137Cs and sediment yield from uncultivated catchments: the role of particle size composition of soil and sediment in calculating soil erosion rates at the catchment scale

PurposeSoil loss is considered one of the most important consequences of land degradation as it affects the production of agricultural and forested areas, and the natural equilibrium of aquatic ecosystems downstream. For these reasons, the availability of tools and techniques able to identify areas at risk of land degradation is essential. Over the last 3–4 decades, theoretical models, based on the use of 137Cs, an anthropogenic radiotracer, proved to be very effective for this purpose. However, these models require specific information on soil and sediment particle size to provide estimates of soil erosion or deposition and this information is summarised by a particle size correction factor ‘P’. Empirical methods of calculation of this factor assume the basic hypothesis that a particle size selectivity takes place in erosion processes and this results in a general enrichment of the fine component in sediments and a corresponding higher radionuclide activity. In this contribution, we demonstrate that this hypothesis is not valid everywhere, and consequently, the P factor cannot be estimated using traditional approaches.Materials and methodsA long-term experiment, conducted in Southern Italy and based on two small experimental catchments (approximately 1.5 ha in size), for which measurements of sediment yield are available for the period 1978–2020, is used in this work. More specifically, 137Cs measurements carried out within the catchments and on a reference area provided the basis to obtain long-term estimates of soil erosion rate in these sites. Combined measurements of 137Cs activity and particle size on both soils and sediments, obtained for 46 events, were also carried out to explore possible particle size effects on the final estimates of soil loss.Results and discussionParticle size analyses of soil and sediments showed that there is evidence of a general enrichment of the eroded soil in the finer size fractions. Conversely, radiometric analyses revealed that 137Cs activity in sediments is generally lower than that in surface soil. These results reflect both the decreasing 137Cs activity associated with depth in undisturbed soils and the higher specific surface area of the deeper horizon in these soils. These findings preclude the application of the available empirical models to calculate P, and suggest the opportunity to use, for long-term estimates of soil erosion, a particle size correction factor P = 1. This assumption and an uncertainty analysis associated with the spatial variability of the 137Cs reference value were incorporated into the Diffusion and Migration Model (DMM) to obtain estimates of soil erosion rates for the study catchments.ConclusionsThe final estimates of soil erosion provided by the DMM showed values very close to the measurements of sediment yield obtained for the two catchments during the study period. The overall results demonstrated that the DMM, if properly calibrated using specific information of particle size and of 137Cs reference value, can be considered a useful tool to individuate areas more prone to risks of land degradation and to identify appropriate strategies able to reduce soil loss in forested sites.

TEMAS: A Flexible Non‐AI Algorithm for Metrology of Single‐Core and Core‐Shell Nanoparticles from TEM Images

AbstractAn essential application of electron microscopy is to provide feedback to tune the fabrication of nanoparticles (NPs). Real samples tend to follow a size distribution commonly linked to the synthesis process used and in turn to their functional properties. This study presents an algorithm for measuring particle size distributions in electron microscopy images. State‐of‐the‐art methods based on Artificial Intelligence (e.g., Deep Learning) require extensive datasets of labeled images similar to those expected to be analyzed, and extensive supervised re‐training is often required for cross‐domain application. In contrast, the non‐AI algorithm described in this study is accurate and can be quickly set up for measuring new experimental images in different domains. The accuracy of the method is validated quantitatively and comparing graphical and descriptive statistics. Different size distributions are measured on images of platinum and gold nanocatalysts supported on carbon black, amorphous carbon, and titanium dioxide crystals. Also, images of platinum‐iron core‐shell NPs supported on thin amorphous carbon film are successfully analyzed. The limitation of evaluating different algorithms for NPs metrology is the lack of standards that different researchers can use as ground truth. In order to overcome this limitation, the images and the ground truth measurements presented here are shared as an open dataset.

Correction for particle loss in a regulatory aviation nvPM emissions system using measured particle size

To reduce the adverse impact of civil aviation on local air quality and human health, a new international standard for non-volatile Particulate Matter (nvPM) number and mass emissions was recently adopted. A system loss correction method, which accounts for the significant size-dependent particle loss, is also detailed to predict nvPM emissions representative of those at engine exit for emissions inventory purposes. As Particle-Size-Distribution (PSD) measurement is currently not prescribed, the existing loss correction method uses the nvPM number and mass measurements along with several assumptions to predict a PSD, resulting in significant uncertainty.Three new system loss correction methodologies using measured PSD were developed and compared with the existing regulatory method using certification-like nvPM data reported by the Swiss and European nvPM reference systems for thirty-two civil turbofan engines representative of the current fleet. Additionally, the PSD statistics of three sizing instruments typically used in these systems (SMPS, DMS500 and EEPS) were compared on a generic aero-engine combustor rig.General agreement between the three new PSD loss correction methods was observed, with both nvPM number- and mass-based system loss correction factors (kSL_num and kSL_mass) within ±10% reported across the engines tested. By comparison, the existing regulatory method was seen to underpredict kSL_num by up to 67% and overpredict kSL_mass by up to 49% when compared with the measured-PSD-based methods, typically driven by low nvPM mass concentrations and small particle size. In terms of the particle sizing instrument inter-comparison, an agreement of ±2 nm for the GMD and ±0.08 for the GSD was observed across a range of particle sizes on the combustor rig. However, it was seen that these differences can result in a 19% bias for kSL_num and 8% for kSL_mass for the measured-PSD-based methods, highlighting the need for further work towards the standardisation of PSD measurement for regulatory purposes.

Evaluation of the dissolving ability of cellulosic pulps: investigation of a novel method using light scattering follow-up during classical cellulose carbanilation

Abstract The aim of the present study is to investigate the dissolving ability of a cellulosic substrate using a derivatization method, i.e. cellulose tricarbanilation and the follow-up by dynamic light scattering (DLS), for particle size measurement. The dissolving behavior of six commercial pulps, selected for their different nature and properties, were compared to the Fock test, and the analysis was completed by other methods for substrate characterization: crystallinity (XRD), DPv (in CuED), sugar analysis, molecular weight distribution (MWD) of cellulose by HPSEC-multidetectors (done on the cellulose tricarbanilates), and solubility in NaOH:urea:water. The proposed carbanilation/DLS method resulted practical and suitable for evaluating the dissolving ability of the different pulps – including hemicelluloses-containing kraft pulps – and allowed to discriminate the samples, contrary to the Fock test. Comparison and assessment of the relevance of the different methods are finally discussed.

A Study on the Effect of Particle Size on Li-Ion Battery Recycling via Flotation and Perspectives on Selective Flocculation

The recycling of active materials from Li-ion batteries (LIBs) via froth flotation has gained interest recently. To date, recycled graphite has not been pure enough for direct reuse in LIB manufacturing. The present work studied the effect of particle sizes on the grade of recycled graphite. Furthermore, selective flocculation is proposed as a novel approach to control particle sizes and thus improve graphite grade by preventing the entrainment of cathode components. Zeta potential and particle size measurements were performed to find an optimal pH for electrically selective flocculation and to study the interaction of flocculants, respectively. Batch flotation experiments were performed to investigate the effect of particle size on the purity of the recovered graphite. Results suggested that, in the absence of ultrafine fine particles, battery-grade graphite of 99.4% purity could be recovered. In the presence of ultrafine particles, a grade of 98.2% was observed. Flocculating the ultrafine feed increased the grade to 98.4%, although a drop in recovery was observed. By applying a dispersant in addition to a flocculant, the recovery could be increased while maintaining a 98.4% grade. Branched flocculants provided improved selectivity over linear flocculants. The results suggest that particle size needs to be controlled for battery-grade graphite to be recovered.

Influence of processing temperature on plasmin activity and proteolysis in process streams from cold microfiltration of skim milk

Plasmin in process streams derived from microfiltration of skim milk can result in casein hydrolysis, potentially affecting the quality and functionality of ingredients produced. To determine whether partitioning of plasmin into permeates was impacted by processing temperature, cold microfiltration of skim milk was investigated at 4, 8 and 12 °C. Permeate generated at 4 °C had the highest plasmin activity (0.0185 AMC units mL−1). When plasmin activity was expressed relative to β-casein content, differences in the extent of dissociation of β-casein, at the different processing temperatures, did not influence plasmin activity in the resulting permeate streams. Throughout storage at 37 °C, all retentates exhibited extensive plasmin-mediated hydrolysis of β- and αS2-casein; αS1-casein to a lesser extent. Particle size measurements before and after plasmin-mediated hydrolysis of permeates indicated that the proteolysis products of β-casein, γ-caseins, retained the ability to self-associate on heating, with particle size increasing with increasing temperature.

Formation and Microstructural Evolution of Ferritic ODS Steel Powders during Mechanical Alloying.

Ferritic ODS steel elemental powder compositions with various Zr content (0.3-1.0 wt.%), ground in a Pulverisette 6 planetary ball mill, were extensively studied by X-ray diffraction line profile analysis, microscopic observations, microhardness testing and particle size measurements. A characteristic three-stage process of flattening the soft powders, formation of convoluted lamellae and, finally, formation of nanocrystalline grains was observed. In order to quantify the microstructural properties, expressed mainly in terms of crystallite size and dislocation density, a methodology for detailed and accurate microstructure analysis of nanosized and severely deformed materials was proposed by the Whole Powder Pattern Modelling (WPPM) approach. In the case of the proposed ODS alloy composition, the overlapping of Fe and Cr Bragg reflections makes the microstructure analysis certainly more complicated. The results showed that the microstructure of powders evolved towards the nanocrystalline state consisting of fine (diameter of ~15 nm) and narrowly dispersed domains, with extensive dislocation density exceeding 1016 m-2.