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ABSTRACT Polystyrene spheres ranging in diameter from 2, 5, 10, to 20 μm were embedded in five different types of thick organic films (> 50 μm) to serve as model systems to evaluate the use of time‐of‐flight secondary ion mass spectrometry for the localization and particle sizing of pharmaceuticals in orodispersible drug delivery films. It was found that certain films, such as gelatin and ethyl cellulose, are prone to developing micron‐scale topography which can affect the linearity of the sputter yield, which can ultimately affect the maximum analyzable depth. Surprisingly, the sputter yield of the film was more of a determining factor for affecting the measurement of spheres. It was possible to more accurately extract the true dimensions of the buried spheres in faster sputtering films, while slower sputtering films were associated with matrix effects and sputtering artifacts that degraded the quality of the reconstructed image. Signal attenuation was also found to be problematic and quite significant for certain film chemistries, which placed a limit on the size of the particles that could be visualized. Overall, visualization of particles embedded in thick organic films is possible, but the extraction of quantitative data such as size and the amount of material is difficult given the influence of sample dependent sputtering artifacts. [ABSTRACT FROM AUTHOR]

Dynamic light scattering (DLS) is a highly efficient approach for extracting particle size distributions (PSDs) from autocorrelation functions (ACFs) to measure nanoparticle particles. However, it is a technical challenge to get an exact inversion of the PSD in DLS. Generally, Tikhonov regularization is widely used to address this issue; it uses the L2 norm for both the data fitting term (DFT) and the regularization constraint term. However, the L2 norm's DFT has poor robustness, and its regularization term lacks sparsity, making the solution susceptible to noise and a reduction in accuracy. To solve this problem, the Lp,q norm restrictive model is formulated to examine the impact of various norms in the DFT and regularization term on the inversion results. On this basis, combined with the robustness of DFT and the sparsity of regularization terms, an L1,∞-constrained Tikhonov regularization model was constructed. This model improves the inversion accuracy of PSD and offers a better noise-resistance performance. Simulation tests reveal that the L1,∞ model has strong noise resistance, exceptional inversion precision, and excellent bimodal resolution. The inversion outcomes for the 33 nm unimodal particles, the 55 nm unimodal, and the 33 nm/203 nm bimodal experimental particles show that L1,∞ reduces peak errors by at most 6.06%, 5.46%, and 12.12%/3.94% compared to L2,2, L1,2, and L2,∞ models, respectively. These simulations are validated by experimental data. [ABSTRACT FROM AUTHOR]

Reproducible aerosol generation in combination with stable aerosol properties are essential prerequisites for compliant performance of acute or repeated inhalation toxicity tests of particulate materials according to OECD TG 403, 436, 412, or 413. A frequent problem of powder aerosol generation is the formation of coarse agglomerates with low shear resistance, which are beyond the tolerable size range but not detected by the prescribed aerodynamic measurement techniques by cascade impactor as the measurement conditions cause a disintegration into smaller fragments. But such agglomerates are observed during the transport to the inhalation chambers. These effects particularly apply to high mass concentrations and low-density powders, i.e., pyrogenic oxides. This study describes the transport influence in the airflow on the change of powder aerosols and on their respirability. A simplified short tube set-up was developed for the aerosol transport pre-tests, which allows the determination of the optimal aerosol formation conditions for the inhalation tests. The particles were measured with low shear using laser diffraction measurement or optical particle counters. The calculation of the aerodynamic particle sizes prescribed in the guidelines requires knowledge of the effective particle density of the porous aerosol particles. A practicable method for determining these is presented and described. In the outlook, first low concentration measurements show that clear agglomeration effects can also occur at particle concentrations around 20 mg/m³. • Short tube setup simulates aerosol transport in real inhalation chamber setup. • Low shear optical particle sizing reveals strong re-agglomeration of aerosols. • Pyrogenic aerosol re-agglomeration reduces respirable fraction concentration. • OECD TGs require smaller MMAD sizes than pyrogenic powders can perform. • OECD powder tests are hardly conformable with CLP as placed on the market. [ABSTRACT FROM AUTHOR]

Purpose: A comparative assessment was performed to evaluate the potential of particle sizing by an ensemble based conventional dynamic light scattering (DLS) technique and an emerging technology based on tunable resistive pulse sensing (TRPS) using particle by particle approach by evaluating three different types of vaccine formulations representing three case studies and showing the limitation of each technique, instrument variability, sensitivity, and the resolution in mixed population. Methods: Three types of in-house vaccine formulations- a protein antigen, an outer membrane vesicle and viral particles were simultaneously evaluated by TRPS based Exoid and two DLS instruments-Zetatrac and Zetasizer for particle size distribution, aggregates, and resolution of polydisperse species. Results: The data from first case study show the risk of possible size overestimation and size averaging in polydisperse samples in DLS measurements which can be addressed by the TRPS analysis. It also shows how TRPS may be utilized only to large size antigens due to its limited size range. The second case study highlights the difference in the sensitivities of two DLS instruments working on the same principle. The third case study show that how TRPS can better resolve the large aggregate species compare to DLS in polydisperse samples. Conclusion: This analysis shows that TRPS can be used as an orthogonal technique in addition to conventional DLS based methods for more precise and in-depth characterization. Both techniques are efficient in size characterization and produce comparable results, however the choice will depend on the type of formulation and size range to be evaluated. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) pigment is a non-toxic, particulate material in widespread use and found in everyone’s daily life. The particle size of the anatase or rutile crystals are optimised to produce a pigment that provides the best possible whiteness and opacity. The average particle size is intentionally much larger than the 100 nm boundary of the EU nanomaterial definition, but the TiO2 pigment manufacturing processes results in a finite nanoscale content fraction. This optically inefficient nanoscale fraction needs to be quantified in line with EU regulations. In this paper, we describe the measurement procedures used for product quality assurance by three TiO2 manufacturing companies and present number-based primary particle size distributions (PSDs) obtained in a round-robin study performed on five anatase pigments fabricated by means of sulfate processes in different plants and commonly used worldwide in food, feed, pharmaceutical and cosmetic applications. The PSDs measured by the three titanium dioxide manufacturers based on electron micrographs are in excellent agreement with one another but differ significantly from those published elsewhere. Importantly, in some cases, the PSDs result in a different regulatory classification for some of the samples tested. The electron microscopy results published here are supported by results from other complementary methods including surface area measurements. It is the intention of this publication to contribute to an ongoing discussion on size measurements of TiO2 pigments and other particulate materials and advance the development of widely acceptable, precise, and reproducible measurement protocols for measuring the number-based PSDs of particulate products in the size range of TiO2 pigments.

Dynamic light scattering (DLS) is a highly efficient approach for extracting particle size distributions (PSDs) from autocorrelation functions (ACFs) to measure nanoparticle particles. However, it is a technical challenge to get an exact inversion of the PSD in DLS. Generally, Tikhonov regularization is widely used to address this issue; it uses the L2 norm for both the data fitting term (DFT) and the regularization constraint term. However, the L2 norm’s DFT has poor robustness, and its regularization term lacks sparsity, making the solution susceptible to noise and a reduction in accuracy. To solve this problem, the Lp,q norm restrictive model is formulated to examine the impact of various norms in the DFT and regularization term on the inversion results. On this basis, combined with the robustness of DFT and the sparsity of regularization terms, an L1,∞-constrained Tikhonov regularization model was constructed. This model improves the inversion accuracy of PSD and offers a better noise-resistance performance. Simulation tests reveal that the L1,∞ model has strong noise resistance, exceptional inversion precision, and excellent bimodal resolution. The inversion outcomes for the 33 nm unimodal particles, the 55 nm unimodal, and the 33 nm/203 nm bimodal experimental particles show that L1,∞ reduces peak errors by at most 6.06%, 5.46%, and 12.12%/3.94% compared to L2,2, L1,2, and L2,∞ models, respectively. These simulations are validated by experimental data.

Chemical mechanical polishing/planarization (CMP) slurry contains mainly abrasive grains (primary particles) with few aggregations (secondary particles). Measuring the particle size distribution (PSD) of CMP slurry is crucial for improving the productivity of the CMP process. For the quality management of CMP slurry, it is necessary to evaluate both the sizes and quantities of both the primary and secondary particles. Conventional PSD analysis methods, except for image analysis, face challenges in identifying primary and secondary particles for PSD measurements. For image analysis, the particles must be transferred from a suspension to a substrate using the conventional sampling method; however, this creates aggregates, resulting in a change in the PSD of the particles on the substrate compared to that in suspension under poly-dispersed conditions. Thus, this study proposed a novel particle sizing method using nanoparticle chip (NPC) to assist in the image analysis of the PSD. The NPC can pick up a single particle in a small volume droplet to avoid aggregation and maintain the poly-dispersed condition of the particles in suspension. The primary and secondary particles can be identified using scanning electron microscope (SEM) or atomic force microscope (AFM), and the PSD can be evaluated by measuring the area and height of the particles. Further, the quantities of both the primary and secondary particles can be counted from the substrate. This study presented a comparison of the diameter measurements using NPC and the conventional method. The results show that the NPC identified the primary and secondary particles and decreased the measurement error of the particle diameters. Consequently, the NPC proves to be superior to the conventional method for use in the PSD analysis of CMP slurry. • Nanoparticle chip (NPC) sizing for CMP slurry particle size distribution (PSD). • NPC avoids particle aggregation, maintains PSD in poly-dispersed suspension. • Primary and secondary particles separated to lower equivalent height diameter error. • PSD of primary particles and number of secondary particles measured using NPC. [ABSTRACT FROM AUTHOR]

Nanocomposites based on silver nanoparticles and chitosan present important advantages for medical applications, showing over time their role in antibacterial evaluation. This work presents the comparative study of two chemical synthesis procedures of nanocomposites, based on trisodium citrate dihydrate and sodium hydroxide, using various chitosan concentrations for a complex investigation. The nanocomposites were characterized by AFM and DLS regarding their dimensions, while FT-IR and UV–VIS spectrometry were used for the optical properties and to reveal the binding of silver nanoparticles with chitosan. Their antibacterial effect was determined using a disk diffusion method on two bacteria strains, E. coli and S. aureus. The results indicate that, when using both methods, the nanocomposites obtained were below 100 nm, yet the antibacterial effect proved to be stronger for the nanocomposites obtained using sodium hydroxide. Furthermore, the antibacterial effect can be related to the nanocomposites' sizes, since the smallest dimension nanocomposites exhibited the best bacterial growth inhibition on both bacteria strains we tested and for both types of silver nanocomposites. [ABSTRACT FROM AUTHOR]

This paper presents the feasibility of Fraunhofer diffraction analysis as a measure of the size of fast‐moving inkjet droplets. This measurement method showed that an inkjet droplet measurement tool was possible with a good balance of real‐time measurement and accuracy. [ABSTRACT FROM AUTHOR]

Abstract There is a critical need to generate environmentally relevant microplastics (MPs) and nanoplastics (NPs) to better investigate their behavior in laboratory settings. Environmental MPs are heterogenous in size and shape, unlike monodisperse and uniform microspheres commonly used as surrogates. Cryogenic grinding, or cryomilling, was successfully utilized to transform polystyrene (PS) bulk material into heterogenous micro and nano fragments. Fourier-Transform Infrared (FTIR) spectroscopy confirmed that this approach did not alter polymer surface chemistry. The number of milling cycles (time of milling) and frequency of grinding (intensity of milling) were varied to investigate the role cryomilling parameters had on generated MP characteristics. The resulting particle size distributions of cryomilled samples were measured and compared. Coulter Counter and Nanoparticle Tracking Analysis (NTA) were used to measure the particle size distributions at the micro and nanoparticle size ranges, respectively. Microspheres were used to determine what camera settings yielded more accurate sizing and to reduce bias in the NTA analysis. Increasing milling cycles generally increased the number of smaller particles. The evolution of the measured size distributions indicated that small nanosized fragments broke off from larger MPs during cryomilling, steadily eroding larger MP fragments. The number of milling cycles was observed to more consistently impact the size distributions of fragments compared to the frequency of milling. This study offers both analysis of the cryomilling process and recommendations for generating more realistic PS MP/NPs for examining environmental fate and effects.

There is a critical need to generate environmentally relevant microplastics (MPs) and nanoplastics (NPs) to better investigate their behavior in laboratory settings. Environmental MPs are heterogenous in size and shape, unlike monodisperse and uniform microspheres commonly used as surrogates. Cryogenic grinding, or cryomilling, was successfully utilized to transform polystyrene (PS) bulk material into heterogenous micro and nano fragments. Fourier-Transform Infrared (FTIR) spectroscopy confirmed that this approach did not alter polymer surface chemistry. The number of milling cycles (time of milling) and frequency of grinding (intensity of milling) were varied to investigate the role cryomilling parameters had on generated MP characteristics. The resulting particle size distributions of cryomilled samples were measured and compared. Coulter Counter and Nanoparticle Tracking Analysis (NTA) were used to measure the particle size distributions at the micro and nanoparticle size ranges, respectively. Microspheres were used to determine what camera settings yielded more accurate sizing and to reduce bias in the NTA analysis. Increasing milling cycles generally increased the number of smaller particles. The evolution of the measured size distributions indicated that small nanosized fragments broke off from larger MPs during cryomilling, steadily eroding larger MP fragments. The number of milling cycles was observed to more consistently impact the size distributions of fragments compared to the frequency of milling. This study offers both analysis of the cryomilling process and recommendations for generating more realistic PS MP/NPs for examining environmental fate and effects. [ABSTRACT FROM AUTHOR]

The size of silver nanoparticles plays a crucial role in their ultimate application in the medical and industrial fields, as their efficacy is enhanced by decreasing dimensions. This study presents two chemical synthesis procedures for obtaining silver particles and compares the results to a commercially available Ag-based product. The first procedure involves laboratory-based chemical reduction using D-glucose (C6H12O6) and NaOH as reducing agents, while the second approach utilizes trisodium citrate dehydrate (C6H5Na3O7·2H2O, TSC). The Ag nanoparticle suspensions were examined using FT-IR and UV-VIS spectroscopy, which indicated the formation of Ag particles. The dimensional properties were investigated using Atomic Force Microscopy (AFM) and confirmed by Dynamic Light Scattering (DLS). The results showed particle size from microparticles to nanoparticles, with a particle size of approximately 60 nm observed for the laboratory-based TSC synthesis approach. [ABSTRACT FROM AUTHOR]

High-solid-content polystyrene and polyvinyl acetate dispersions of polymer particles with a 50 nm to 500 nm mean particle diameter and 12–55% (w/w) solid content have been produced via emulsion polymerization and characterized regarding their optical and physical properties. Both systems have been analyzed with common particle-size-measuring techniques like dynamic light scattering (DLS) and static light scattering (SLS) and compared to inline particle size distribution (PSD) measurements via photon density wave (PDW) spectroscopy in undiluted samples. It is shown that particle size measurements of undiluted polystyrene dispersions are in good agreement between analysis methods. However, for polyvinyl acetate particles, size determination is challenging due to bound water in the produced polymer. For the first time, water-swelling factors were determined via an iterative approach of PDW spectroscopy error (Χ2) minimization. It is shown that water-swollen particles can be analyzed in high-solid-content solutions and their physical properties can be assumed to determine the refractive index, density, and volume fraction in dispersion. It was found that assumed water swelling improved the reduced scattering coefficient fit by PDW spectroscopy by up to ten times and particle size determination was refined and enabled. Particle size analysis of the water-swollen particles agreed well with offline-based state-of-the-art techniques. [ABSTRACT FROM AUTHOR]

[Display omitted] Sub-visible particles (SVPs) in pharmaceutical products are a critical quality attribute, and therefore should be monitored during development. Although light obscuration (LO) and microscopic particle count tests are the primary pharmacopeial methods used to quantify SVPs, flow imaging methods like Micro-Flow Imaging (MFI™) appear to overcome shortcomings of LO such as limited sensitivity concerning smaller translucent SVPs in the size range < 10 µm. Nowadays, MFI™ is routinely utilized during development of biologicals. Oftentimes multiple devices are distributed across several laboratories and departments. This poses challenges in data interpretation and consistency as well as in the use of multiple devices for one purpose. In this study, we systematically evaluated seven MFI™ instruments concerning their counting and size precision and accuracy, using an inter-comparable approach to mimic daily working routine. Therefore, we investigated three different types of particles (i) NIST certified counting standards, (ii) protein-coated particles, and (iii) stress-induced particles from a monoclonal antibody. We compared the results to alternative particle detection methods: LO and Backgrounded Membrane Imaging (BMI). Our results showed that the precision and accuracy of particle count and size, as well as the comparability of instruments, depended on the particle source and its material properties. The various MFI™ instruments investigated showed high precision (<15 %) and data generated on different instruments were of the same order of magnitude within pharmacopeial relevant size ranges for NIST certified counting standards. However, we found limitations in the upper and lower detection limits, contrary to the limits claimed by the manufacturer. In addition, proteinaceous and protein-containing particles showed statistically significant differences in particle counts, while the measured particle diameters of all sizes were quite consistent. [ABSTRACT FROM AUTHOR]

Extracts with emulsifying capacity have been extracted from split peas (Pisum sativum). At pH 7 and extract concentrations above 0.75 g L−1 s, stable emulsions were produced, with droplets of tens μm. At higher concentrations (2 g L−1 s) bridging flocculation occurs, with the flocs breaking up into μm-sized particles upon SDS addition, reaching sizes comparable to those obtained by oilve compost emulsifiers. At even higher concentrations, depletion flocculation is observed due to unadsorbed extracts. The extract cannot emulsify at pH 3. In all cases, the interfacial tension is quickly reduced (at a higher degree at pH 7) due to the fast adsorption of small-molecular surfactants. Within 10 s further reductions are observed, as macromolecules are adsorbed, forming steric layers at the oil – water interface at pH 7. At pH 3 the adsorption of the macromolecules reduces the interfacial tension to a smaller extent, and is followed by a slower (over 100 s) rearrangement at the interface. Coupled with a change in zeta potential from 10.8 ± 0.6 mV at pH 7 down to 4.1 ± 2.2 mV at pH 3, these phenomena render the interfacial layer at pH 3 unable to stabilize against coalescence. Size exclusion chromatography of the extract, the emulsion serum and the cream layer highlight the preferential adsorption of specific biopolymers at the interface and confirm the hypothesis of the sequential adsorption and interfacial rearrangements. Fourier transform infrared spectra show that proteins are preferably adsorbed at the interface, while polysaccharides remain at the bulk phase. [ABSTRACT FROM AUTHOR]

Particle size distributions (PSDs) define the description of particle systems and of their separation processes in mechanical process engineering. Modern analytical methods, in particular image analysis, and their combination with material‐specific analytics record additional geometric and material parameters of particles. Many of these particle properties, like particle size, are not constant but also distributed, leading to a multi‐dimensional particle property distribution that can be used to describe particle processes. Thus, it is possible to define a partition function that quantifies separation in multidimensional space. The multidimensional approaches can be simply reduced in their dimensionality, so that the known one‐dimensional distribution functions, e.g., a PSD, can be obtained as marginal distributions. [ABSTRACT FROM AUTHOR]

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in dispersed two-phase flows has up to now been restricted to the processing of spherical particle images. This study examines how this technique can be extended to process irregular particle images, arising either from neighboring spherical particles which lead to overlapping images, or from the imaging of non-spherical particles. In either case, the application scope of the DFD technique is significantly expanded. On the one hand the ability to identify and process overlapping images allows measurements to be performed at higher number/volume concentrations. On the other hand, especially solid particles are often non-spherical, thus making the DFD technique attractive for these applications. For both cases, the processing algorithms are experimentally benchmarked against ground truth using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. • Size and position of two particles are determined from overlapping blurred images. • The area equivalent size and position of irregularly shaped particles are measured. • DFD technique is improved to measure flows with higher concentrations of particles. [ABSTRACT FROM AUTHOR]

Particle size inversion of dynamic light scattering (DLS) is a typically ill-posed problem. Regularization is an effective method to solve the problem. The regularization involves imposing constraints on the fitted autocorrelation function data by adding a norm. The classical regularization inversion for DLS data is constrained by the L2 norm. In the optimization equation, the norm determines the smoothness and stability of the inversion result, affecting the inversion accuracy. In this paper, the Lp norm regularization model is constructed. When p is 1, 2, 10, 50, 100, 1000, and ∞, respectively, the influence of their norm models on the inversion results of data with different noise levels is studied. The results prove that overall, the inversion distribution errors show a downward trend with the increase of p. When p is larger than 10, there is no significant difference in distribution error. Compared with L2, L∞ can provide better performance for unimodal particles with strong noise, although this does not occur in weak noise cases. Meanwhile, L∞ has lower sensitivity to noise and better peak resolution, and its inverse particle size distribution is closer to the true distribution for bimodal particles. Thus, L∞ is more suitable for the inversion of DLS data. [ABSTRACT FROM AUTHOR]

In the Sulige gas field in Changqing Oilfield, the Liujiagou formation is a low pressure formation, the low density cement slurries presently used in this area have poor pressure resistance; the cement slurries under high pressures will have their density increased and rheology deteriorated. In field operations with these cement slurries, the operation pressures were high, generally causing the cement slurries to be lost into the formations, and the cementing quality is poor because of less cement slurries in the annulus. To solve this problem, a new cement slurry with low friction low density was formulated. This new cement slurry is pressure resistant and has the property of preventing itself from being lost into formations. Using the close packing theory, particles of 4 sizes were selected. A light material with excellent pressure resistance and other appropriate additives were selected to formulate the target cement slurry. The density of the new cement slurry is adjustable between 1.25 g/cm3 and 1.35 g/cm3, the Fanning friction coefficient was reduced by about 50%. The new cement slurry has good pressure resistance and leaking preventive property. Study on the agitation and mixing techniques shows that mechanical agitation and mixing can be used, 99% of the properties of the bulk sample and those of the small sample coincide with each other, ensuring the qualification and efficiency of the cement mixing. In field operations in the Sulige gas field, four wells were cemented with success, no loss of cement slurry has ever happened, and the cementing job was qualified. During the cementing, the operational pressure was significantly reduced, and the job quality was obviously improved. This laboratory study and the field application provide a strong technical support to cementing wells penetrating low pressure formations into which cement slurries are easily lost. [ABSTRACT FROM AUTHOR]

Quantifying the heterogeneous nature of protein aggregates is important to understanding the impact aggregates may have on the performance of antibody therapeutics. The spatially averaged density ρ p of aggregates, defined as the total mass, including water, divided by the volume, is a parameter that can be used to relate size distributions measured by orthogonal methods, to characterize protein particles, and perhaps to estimate the amount of aggregated protein in a sample. We report measurements by two methods on the distribution of density values for different aggregate sizes, where the aggregates were produced by stir-stressing fluorescently labeled monoclonal antibody (NISTmAb). A fluorescence microscope was used to image particles. Each particle was analyzed for brightfield equivalent circular diameter (ECD) and fluorescence intensity and the results converted to average density. Measurements were also obtained using video holography. The aggregates were highly porous with median density decreasing from 1.07 g/cm3 to 1.02 g/cm3 as the size increased from 0.9 μm to 6 μm by fluorescence, and similar results by video holography. The distribution in density for a given particle size was asymmetrical and broad. For example, particles with an ECD of 2.5 μm ranged in density from 1.005 g/cm3 to 1.1 g/cm3. [ABSTRACT FROM AUTHOR]

Dynamic Light Scattering is a well-established technique used in particle sizing. An alternative procedure for Dynamic Light Scattering time series processing based on spectral entropy computation and Artificial Neural Networks is described. An error analysis of the proposed method was carried out and the results on both the simulated and on the experimental DLS time series are presented in detail. The results reveal the possibility of designing an advanced sensor capable of detecting particles with a size bigger than a threshold using this alternative for processing the DLS time series. [ABSTRACT FROM AUTHOR]

Single-step trans-vertical moulds used to prepare grain mounts for SEM-automated-mineralogy based instruments have been shown to lead to more representative sample statistics. For samples that contain a variety of mineral phases, denser phases can settle to the bottom of an epoxy mould during the curing phase. Slicing and polishing a cross section through density-stratified moulds of the sample material can compensate for this. Aliquots from offshore drill well cuttings were prepared using three different methods: (1) traditional epoxy mounting, (2) two-step trans-vertical moulds, and (3) single-step trans-vertical moulds. All were analysed with a FEI Quanta 650 FEG instrument using MLA software with similar acquisition parameters. The results indicate that the single-step trans-vertical moulds are reproducible, lead to more accurate statistics, and yield MLA calculated elemental assays that closely match with data from standard analytical methods. In addition, these moulds can be made in half the time of the two-step trans-vertical moulds, and because of the unique geometry of the custom-made SEM holders, the analytical throughput is doubled. Depending on the size fraction of the well cuttings, the throughput can be further increased by slicing off the remaining epoxy to allow for more samples in the 26x TV holder. A unique cell holder was created to accommodate these trans-vertical samples, allowing them to fit into a LA-ICP-MS instrument such that detailed follow-up microanalyses can be conducted on specific minerals. For instance geochronology can be conducted on grains of interest (e.g., zircons), which had been mapped by the SEM-MLA. [ABSTRACT FROM AUTHOR]

[Display omitted] Dynamic Light Scattering (DLS) generated particle size distributions (PSD) of polymer-stabilized nanoparticles are dependent on the optimization parameters used to generate an inversion solution fit to the measured autocorrelation function. The accuracy of the DLS PSD average and polydispersity can be determined by comparing analyzed Transmission Electron Microscopy (TEM) images with the DLS results if the TEM measured sizes can be corrected for the thickness of the hydrated polymer corona that impacts particle hydrodynamics but is a collapsed, desiccated shell in the TEM images. Nanoparticles were prepared by Flash NanoPrecipitation with either poly(ethylene glycol) (PEG) or hydroxypropyl methylcellulose acetate succinate (HPMCAS) stabilizing polymers. Solvated nanoparticle size distributions were measured by DLS in aqueous media. The same nanoparticle dispersions were lyophilized onto TEM grids and stained by ruthenium tetroxide (RuO 4) vapor to improve electron contrast. Desiccated particle size distributions were generated by measuring a minimum of 300 particle diameters in the stained TEM images. Using our protocol for staining soft matter nanoparticles in TEM measurements, we have quantitatively analyzed the correlation between DLS and TEM generated PSDs. Average diameters disagree by the hydrated polymer corona thickness for each stabilizer due to the high-vacuum TEM environment, with 21.4 nm for PEG and 51.2 nm for HPMCAS. While corrected average diameter agrees within 10% for each technique, DLS consistently over-estimates the standard deviation of the PSD by 100% compared to the TEM measurement. [ABSTRACT FROM AUTHOR]

[Display omitted] • Silver nanoparticles (Ag NPs) stabilized by four different capping agents are applied as catalysts of CO 2 reduction in a zero-gap gas-flow electrolyser. • Branched polyethylenimine (BPEI), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and citrate are used as capping agents. • Depending on the nature of the capping agent, Ag NPs undergo different degradation pathways. • BPEI is the most effective stabilizer but also blocks CO 2 reduction the most. • Particles capped by PVP tend mostly to corrode (leading to particle shrinkage) while in case of PEG- and citrate-capped particles degradation involves particle size growth. • The statistical analysis of SEM images and WAXS measurements provide an insight to the degradation pathway. • Ligand exchange and removal experiments underline the role of capping agents in catalyst degradation. We apply silver nanoparticles (Ag NPs) as catalysts of CO 2 reduction in a zero-gap gas-flow electrolyser. Ag NPs stabilized by different ligands —branched polyethylenimine (BPEI), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and citrate— are used in the experiments. The as-prepared NPs have almost identical initial size distributions, yet their catalytic performance, in terms of achievable current and CO selectivity, is different. During electrolysis all Ag NPs exhibit unambiguous morphology changes; the degradation pathway they follow, however, markedly depends on the chemical nature of the capping agent stabilizing them. Scanning electron micrographs obtained before and after constant-charge electrolyses carried out at different potentials reveal that amongst the studied ligands, BPEI seems to be the most effective stabilizer of Ag NPs; in turn, however, BPEI also limits CO formation the most. In case of PVP, mostly corrosion (particle shrinkage) is observed at practically relevant electrolysing potentials, while the application of PEG leads more to particle coalescence. Ostwald ripening seems to appear only at high applied (H 2 forming) potentials in case of the three afore-mentioned ligands while in case of citrate it becomes significant already at mild (CO forming) voltages. By studying the effects of capping agent removal and exchange we demonstrate that apart from ligands directly attached to the Ag NPs, also the excess of capping agents (adsorbed on the electrode surface) plays a decisive role in determining the extent and mode of catalyst degradation. The results of SEM-based particle sizing are also confirmed by synchrotron based wide-angle X-ray scattering measurements that provide further insight into the evolution of crystallite size and lattice strain in the applied Ag NPs during electrolysis. [ABSTRACT FROM AUTHOR]

Particle-processing industries, such as those for manufacturing pharmaceuticals, ceramics and polymers, require accurate and reliable monitoring and controlling techniques for particle-size distribution to stabilize product quality and maximize productivity. Imaging is a highly valuable monitoring technique because it can measure precise particle-size distributions by detecting particles individually and also can measure particle shape. However, detecting submicron particles or smaller is difficult due to the diffraction of light in the optics. We propose an imaging-based monitoring system that extends the detectable particle-size range towards the submicron level by combining particle-shade and scattered-light imaging. The system consists of newly developed optics and an analysis algorithm. We evaluated the accuracy of the proposed system using polystyrene standard spheres. [Display omitted] • Imaging-based particle sizing system for submicron particles • Particle-shade and scattered-light imaging were combined. • Analytical correction of particle's edge considering diffraction of light • Particle size estimation from intensity of small angle scattered light. • Accuracy of PSD estimation were evaluated using polystyrene spheres. [ABSTRACT FROM AUTHOR]

The ultrasonic spectroscopy method has long been known as a particle size analysis method applicable to concentrated particle suspensions that do not transmit light. On the other hand, it requires prior estimation of density and thermal parameters in addition to the parameters of the surrounding liquid. In this paper, we describe a method for precisely measuring diameter of nano and submicron particles in highly concentrated (∼30 wt%), optically turbid suspensions using dynamic ultrasound scattering (DSS). This method is an acoustic analogue of the dynamic light scattering (DLS) method, which determines the so-called Stokes-Einstein particle size by measuring the diffusion coefficient. Here, the only parameters required in the DSS analysis are the simultaneously measurable sound velocity of the suspension and the viscosity of the solvent (water), which is significantly less a priori information required. In addition, the required sample volume is only 50 µL, which can easily accommodate precious samples. However, as the concentration increases, two effects cannot be ignored: interference from the particle structure (static structure factor) and long-ranged interaction (hydrodynamic interaction). This study focuses on the long-wavelength approximation of ultrasound, which has a longer wavelength than light, and the advantages of simplifying these complex interactions and providing a means to determine particle size by a different route than conventional ultrasonic methods. Finally, the advantages and disadvantages of this method are also discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Dynamic Light Scattering is a well-established technique used in particle sizing. An alternative procedure for Dynamic Light Scattering time series processing based on spectral entropy computation and Artificial Neural Networks is described. An error analysis of the proposed method was carried out and the results on both the simulated and on the experimental DLS time series are presented in detail. The results reveal the possibility of designing an advanced sensor capable of detecting particles with a size bigger than a threshold using this alternative for processing the DLS time series.

Titanium dioxide (TiO 2 ) pigment is a non-toxic, particulate material in widespread use and found in everyone's daily life. The particle size of the anatase or rutile crystals are optimised to produce a pigment that provides the best possible whiteness and opacity. The average particle size is intentionally much larger than the 100 nm boundary of the EU nanomaterial definition, but the TiO 2 pigment manufacturing processes results in a finite nanoscale content fraction. This optically inefficient nanoscale fraction needs to be quantified in line with EU regulations. In this paper, we describe the measurement procedures used for product quality assurance by three TiO 2 manufacturing companies and present number-based primary particle size distributions (PSDs) obtained in a round-robin study performed on five anatase pigments fabricated by means of sulfate processes in different plants and commonly used worldwide in food, feed, pharmaceutical and cosmetic applications. The PSDs measured by the three titanium dioxide manufacturers based on electron micrographs are in excellent agreement with one another but differ significantly from those published elsewhere. Importantly, in some cases, the PSDs result in a different regulatory classification for some of the samples tested. The electron microscopy results published here are supported by results from other complementary methods including surface area measurements. It is the intention of this publication to contribute to an ongoing discussion on size measurements of TiO 2 pigments and other particulate materials and advance the development of widely acceptable, precise, and reproducible measurement protocols for measuring the number-based PSDs of particulate products in the size range of TiO 2 pigments., (Copyright © 2024, Theissmann et al.)

Due to the unique advantages of high specific impulse, high thrust, simplicity and reliability, solid propellant with metal powder additives has emerged as a promising energy carrier for rockets in aerospace engineering. In-situ characterization of the metal particle combustion is crucial for the validation of numerical models and optimization of the propellant formulas. Previous studies mainly focused on the measurement of particle size and velocity near the combusting propellant surface with holography. Whereas, the behavior of the particles away from the surface is also essential for the full understanding the combustion and agglomeration mechanisms. Nevertheless, holography suffers from inaccurate depth estimation due to the large depth-of-focus. To overcome this limitation, a hybrid method which combines three-dimensional (3D) fiber optic imaging with two-color pyrometry is developed to realize simultaneous 3D localization, velocimetry, sizing, and thermometry of combusting aluminum particles in a large field of view. The method is validated both with numerical studies and experiments for a field of view of ∼60 × 50 × 50 m m 3. According to the experimental results, the particle size follows a log-normal distribution which agrees with the specification of the propellants. In addition, the evolution of particle temperature and velocity were recorded for a duration of ∼13.9 ms. The results suggest that the temperature of most particles were between 2000 and 3500 K, while particle velocities were between 1 and 10 m/s. The measurement method proposed here is promising for the quantitative analysis of the complicated combustion process of aluminized propellants. [ABSTRACT FROM AUTHOR]

Dynamic light scattering (DLS) from ultra-low concentration suspensions (the average number of particles in the scattering volume is less than ~100) gives rise to autocorrelation functions (ACFs) containing a non-Gaussian term due to particle number fluctuations. This term is difficult to characterize and account for and makes recovery of particle size distribution (PSD) information unreliable. We show that an initial analysis of the intensity ACF to determine parameters describing the amplitude and relaxation rate of the non-Gaussian term and then using these parameters to create a better theoretical non-Gaussian ACF model allows a more accurate recovery of the PSD. The modified model is consistent with the measured ACF data, and a reconstructed kernel matrix matching the measured data is obtained. When compared with the usual kernel function reconstruction (KFR) method, the proposed method gives significantly improved PSD recovery accuracy with experimental data. Furthermore, the PSDs obtained have no obvious differences to those obtained from measurements at normal particle concentrations. [Display omitted] • Fitting the measured ACF data with a non-Gaussian ACF model of lower concentration. • Reducing focused beam waist value to obtain non-Gaussian model at lower concentration. • Providing a solution for nanoparticle size measurement at ultra-low concentration. [ABSTRACT FROM AUTHOR]

• Nanoparticle sizing was performed using dynamic ultrasound scattering technique. • Sample thickness was made thinner to suppress unfavorable acoustic flow. • The technique discriminated mixtures of nanoparticles by different relaxation time. When nanoparticles in Brownian motion in liquid are irradiated with ultrasonic waves in the megahertz frequency range, scattering from the particles occurs, albeit at a very low intensity. The diffusion coefficient and the corresponding particle size can be calculated by analyzing the time correlation function of the ultrasound pulses. Since ultrasonic waves with long wavelengths in comparison with the particle size are unfavorable for detecting such small particles, increasing the energy of the ultrasonic waves is a primary solution. Increasing the energy, conversely, causes an unexpected acoustic flow. Consequently, a method using a strong ultrasound pulse while suppressing this acoustic flow field is required. In this study, we apply (1) a focused transducer with high ultrasonic energy, (2) a high-frequency sensor enhancing scattering performance, and (3) a short pulse repetition time to achieve high-speed and high-precision nanoparticle measurement while confining the sample in a narrow space to eliminate the acoustic flow. This enables direct tracking of nanoparticle motion by observing diffusive motion without perturbation particle dynamics. We specifically investigated a suspension of silica particles with a hydrodynamic radius of 15 nm and also achieved particle size discrimination in mixtures. The time correlation analysis using megahertz ultrasound pulses also takes advantage of ultrasonic waves' inherent advantages, such as high-speed, high-precision particle size analysis in the submicron range beyond the wavelength of visible light. [ABSTRACT FROM AUTHOR]

Dust particles exist in the form of mineral aerosols and play a significant role in climate change patterns, while also having the potential to affect human health. The size of these particles is crucial, as it determines the atmosphere's albedo. In the past few years, a Saharan dust cloud has moved and arrived above Romania during spring, followed by rain containing the dust particles, which are deposited on various objects. We collected these particles in an aqueous suspension and employed natural sedimentation to separate them by density. We then conducted a dynamic light scattering (DLS) experiment to analyze their size. Our DLS setup was straightforward, and the time series analysis involved evaluating the frequency spectrum of the scattered light intensity-also known as the power spectrum-filtering it, and fitting the expected Lorentzian line to it to determine the parameters and the average diameter of the suspended particles. We found that the dust particles had a continuous distribution, with the biggest particles having a diameter around 1100 nm. The results obtained from the combination of sedimentation and DLS are consistent with reports on the size of Saharan dust particles in other regions of Europe.

• Evaluated the PM10/PM2.5 measurement using an optical particle size spectrometer. • Lab-generated ambient-like model aerosols are used for testing with reference weighing system. • Mass concentration (MC) was computed from particle counts, volume and density with good agreement with reference MC. • Expanded uncertainty for computed MC is estimated to be 27–36%, with detailed analysis. • The proposed computation method is useful to evaluate the accuracy of OPSS in PM measurement. We have evaluated the PM 10 and PM 2.5 measurement using a Grimm 11-D optical particle size spectrometer (OPSS) with ambient-like aerosols generated in a laboratory. The ambient-like model aerosols include fresh soot, aged soot, ammonium sulfate, ammonium nitrate and Arizona Road Dust (ARD) particles. The mass concentration (MC) of test aerosols has been computed from the particle counts, equivalent particle volume and particle effective density using a proposed method. The expanded measurement uncertainties for the computed MC are estimated to be 27–36%, with detailed uncertainty analysis. The deviation of the computed MC from the reference gravimetric values is below 20% for MC levels from 29 to 1584 µg/m3. The computed MC agree with the reference MC within their measurement uncertainties. The underestimation and overestimation of the computed MC at various MC levels have been explained based on OPSS sizing errors related to the light-scattering and absorption property of the model aerosols. The proposed MC computation method is useful to evaluate the accuracy of OPSS in PM 10 and PM 2.5 measurement with the lab-generated model aerosols. This method can also be used to compare the performance of various OPSS-based PM monitors via inter-laboratory comparisons. [ABSTRACT FROM AUTHOR]

The purpose of this tutorial is to teach the method of digital in-line holography (DIH) as a means to characterize aerosol particles in an in-situ manner. The scope is limited to the simplest, yet powerful, lens-less implementation, which is the most intuitive and forgiving of the varieties of digital holography. By illuminating free-flowing aerosol particles with a pulsed, expanded, collimated laser beam, one can record the interference pattern of scattered and unscattered light on an image sensor. The resulting digital hologram can then be used in a diffraction calculation to render a silhouette-like image of the particle, or particles, present in the beam. A key advantage of imaging with DIH over conventional imaging, e.g. microscopy, is that particles located at different positions can be brought into focus from a single hologram measurement. Useful information can be obtained from such images including the number of particles present, their size, shape, and orientation. Notably, this is all achieved without the need to collect or otherwise trap particles. The inherent motion of aerosol particles imposes specific constraints on the design and performance of DIH imaging, and in particular, restricts the resolution in comparison to applications involving stationary or otherwise controlled particles. As such, DIH is currently most effective for particles larger than several micrometers in size. The tutorial will explain the theoretical basis of DIH, illustrate how particle images are generated computationally from hologram measurements, provide code in the Mathematica language to do so, and discuss several limitations imposed by hardware. Also reviewed will be a method to approximate a particle's extinction cross section and two-dimensional angular light scattering pattern. [Display omitted] • Digital in-line holography (DIH) is a simple method to characterize aerosols. • Particle size and shape is provided from DIH images of flowing particles. • The theory of DIH is reviewed and its computational implementation explained. • Extinction and scattering can be measured from digital holograms. • Example code is provided to perform image reconstruction from holograms. [ABSTRACT FROM AUTHOR]

Dynamic light scattering techniques can give access to the motion spectrum of microscopic objects and are therefore routinely used for numerous industrial and research applications ranging from particle sizing to the characterization of the viscoelastic properties of materials. However, such measurements are impossible when samples do not scatter light enough, i.e., when light undergoes too few scattering events when passing through a sample, either due to excessively small scattering cross sections or due to low concentrations of scatterers. Here, we propose to amplify the light scattering efficiency by placing weakly scattering samples inside a Lambertian cavity with high-reflectance walls. When injected with laser light, the cavity produces a 3D isotropic and homogeneous light field, effectively elongates the photon scattering path length through the sample by 2-3 orders of magnitude, and leads to a dramatic increase in sensitivity. With a 10 4 -fold increase in sensitivity compared to classical techniques, we potentially expand the applications of light scattering to miniaturized microfluidics samples and to weakly scattering samples in general. We show that we can access the short-time dynamics of low-turbidity samples and demonstrate our sensitivity gain by measuring the diffusion coefficient and, therefore, the size of particles ranging from 5 nm to 20 μm with volume fractions as low as 10 -9 in volumes as low as 100 μL and in solvents with refractive index mismatches down to Δ n ≈ 0.01. Beyond the realm of current applications of light scattering techniques, our cavity-amplified scattering spectroscopy method (CASS) and its high sensitivity represent a significant methodological step toward the study of short-time dynamics problems such as the ballistic limit of Brownian motion, the internal dynamics of proteins, or the dielectric dynamics of liquids.

• This paper describes an application of ultrasound techniques to solid–liquid fluidized beds. • The ultrasonic methods are used for obtaining velocity profiles, particle size distribution, and solids volume fraction. • The solid velocity profiles and particle size distributions were measured for four different sizes of glass particles ranging from 500 μm to 1250 μm at a solid volume fraction of 35%. • The importance of the techniques as a diagnostic tool to investigate the particles segregation behaviour in solid–liquid fluidized beds at different fluidization conditions are reported. This paper describes an application of ultrasound techniques to solid–liquid fluidized beds. The ultrasonic methods, experimental setups, and the signal processing for obtaining velocity profiles, particle size distribution, and solids volume fraction are discussed. The techniques are based on the measurement of the ultrasound attenuation coefficient, sound speed, and frequency shift of the propagated sound wave. The ultrasound propagation speed in solid–liquid fluidized bed was measured to be between 1504 m/s and 1565 m/s for glass particles with volume fractions spanning from 27% to 70% in water. The solid velocity profiles were measured for liquid superficial velocities varying from 0.84 cm/s to 4.24 cm/s. The particle size distributions were measured for four different sizes of glass particles ranging from 500 μm to 1250 μm at a solid volume fraction of 35%. This paper also reports the importance of the techniques as a diagnostic tool to investigate the particles segregation behaviour in solid–liquid fluidized beds at different fluidization conditions. The results indicated that ultrasound techniques are a powerful tool that can characterise in real-time highly concentrated solid–liquid systems. [ABSTRACT FROM AUTHOR]

• The greatest amount of gases at 1.0% Fe 3 O 4 and at 300 °C after aquathermolysis. • At 250 °C the viscosity reduction increased by 15% at a concentration of 0.2 wt.%. • At 200 °C increase in the content of saturated and aromatic hydrocarbons by 3%. • At 200 °C increase in the content of saturated and aromatic hydrocarbons by 22%. • At 200 °C a decrease in resins and asphaltenes by 10%, and 1.0 wt.%.concentration. • At 200 °C a decrease in resins and asphaltenes by 35%, and 1.0 wt.%.concentration. • At 200°C the n-(C12-C21)/n-(C22-C30) increases from 0.82 to 1.85 at 1.0 wt.%. • At 200 and 300 °C, the 1.0% of magnetite suspension stands out from all the results. • The amount of gases released in g/t is greater at 300 °C than at 200 and 250 °C. In this work, physical modeling of thermal steam treatment of high viscosity oil without and with the addition of a suspended catalyst to the system was performed. The aim of the magnetite effect for the in- situ upgrading in the production of high viscosity oils was to reduce the content of asphalt-resinous compounds and their molecular weight, while significantly increasing the content of saturated and aromatic hydrocarbons. The presence of a catalyst promoted decarboxylation reactions, as indicated by the significant amount of carbon dioxide produced as the catalyst concentration increased. In addition, the produced carbon dioxide decreased the viscosity of the oil and improved the chemical composition of the group. The introduction of a hydrogen donor helped to reduce the formation of aromatic hydrocarbons in the gas phase composition and prevented the polymerization of the produced hydrocarbons. The determination of viscosity-temperature characteristics showed a significant decrease in the viscosity of the obtained products after the catalytic aquathermolysis of oil. Indeed, during the catalytic aquathermolysis, maghemite was reduced to magnetite by the interaction of iron oxide with steam. In parallel, in the presence of a catalyst, with increasing exposure temperature, the content of hydrogen sulfide was reduced and the formation of iron sulfides such as pyrrhotite was observed. [ABSTRACT FROM AUTHOR]

Fast online acquisition of particle size distribution has become a significant technique for both laboratory research and industrial application. In this paper, a particle sizing method based on the analysis of scatted light through image processing is proposed. Polarization ratio, which is defined by the ratio of the scattered intensity component polarized perpendicular to that polarized parallel, is induced to quantify the polarization status which, according to Mie scattering theory, is dependent on the particle diameter under a certain operating condition when the refractive index of the particle is known. Test rig is set up to realize the simultaneous acquisition of particle images polarized both perpendicular and parallel on CCD camera. Through image processing, the polarization ratio of the scattered light is obtained, based on which inverse calculation is performed according to Mie theory. The presented method is then applied to the size distribution determination of polystyrene particles suspending in water. The results obtained from experiments are compared with the calibrated values which renders a deviation less than 10%. The optical setup is also applied to the sizing of water droplets generated by an atomizer, which provides reasonable size distributions under different operating conditions in line with the reference values provided by the fabricator. [ABSTRACT FROM AUTHOR]

Light scattering is used for remote diagnostics of certain physical properties of particulate systems. The main purpose of this review is to coherently present an updated theoretical background of forward and inverse analysis for particle size distribution measurements of disperse samples. In particular, both well-tried and recent methods for analytical and numerical treatment of measurement data inversion are examined. An extensive bibliography is included for further study. [ABSTRACT FROM AUTHOR]