Laser Diffraction Measurements Research Articles

Using Dry Dispersion Laser Diffraction to Assess Dispersibility in Spheronized Agglomerate Formulations.

In this study, dry dispersion laser diffraction was used to study the dispersibility of spheronized agglomerate formulations and identify geometric particle size metrics that correlated well with aerodynamic particle size distribution (APSD). Eleven unique batches of agglomerates were prepared for both laser diffraction and cascade impaction testing. Correlations between the particle size distribution (PSD) and aerodynamic particle size distribution (APSD) metrics for the eleven agglomerate batches were determined in a semi-empirical manner. The strongest correlation between APSD and PSD was observed between the impactor-sized mass (%ISM) and the cumulative PSD fraction <14.5 µm. The strongest correlation with fine particle fraction (FPF) was observed with the cumulative PSD fraction <0.99 micron (R-squared = 0.974). In contrast to the other APSD metrics, good correlations were not found between the mass median aerodynamic diameter (MMAD) and the cumulative PSD fractions. Overall, the implementation of laser diffraction as a surrogate for cascade impaction has the potential to streamline product development. Laser diffraction measurements offer savings in labor and turnaround time compared to cascade impaction.

AI-based analysis of in-line process endoscope images for real-time particle size measurement in a continuous pharmaceutical milling process

This paper presents a case study on the first in-line application of AI-based image analysis for real-time pharmaceutical particle size measurement in a continuous milling process. An AI-based imaging system, which utilises a rigid endoscope, was tested for the real-time particle size measurement of solid NaCl powder used as a model API in the range of 200–1000 µm. After creating a dataset containing annotated images of NaCl particles, it was used to train an AI model for detecting particles and measuring their size. The developed system could analyse overlapping particles without dispersing air, thus broadening its applicability. The performance of the system was evaluated by measuring pre-sifted NaCl samples with the imaging tool, after which it was installed into a continuous mill for in-line particle size measurement of a milling process. By analysing ∼100 particles/s, the system was able to accurately measure the particle size of sifted NaCl samples and detect particle size reduction when applied in the milling process. The Dv50 values and PSDs measured real-time with the AI-based system correlated well with the reference laser diffraction measurements (<6% mean absolute difference over the measured samples). The AI-based imaging system shows great potential for in-line particle size analysis, which, in line with the latest pharmaceutical QC trends, can provide valuable information for process development and control.

Laser diffraction measurements of pigment size distributions of coatings and mill bases: implications of dilution medium and dispersion process parameters

Laser diffraction measurements of pigment size distributions of coatings and mill bases: implications of dilution medium and dispersion process parameters

The Effect of the Particle Size Reduction on the Biorelevant Solubility and Dissolution of Poorly Soluble Drugs with Different Acid-Base Character.

Particle size reduction is a commonly used process to improve the solubility and the dissolution of drug formulations. The solubility of a drug in the gastrointestinal tract is a crucial parameter, because it can greatly influence the bioavailability. This work provides a comprehensive investigation of the effect of the particle size, pH, biorelevant media and polymers (PVA and PVPK-25) on the solubility and dissolution of drug formulations using three model compounds with different acid-base characteristics (papaverine hydrochloride, furosemide and niflumic acid). It was demonstrated that micronization does not change the equilibrium solubility of a drug, but it results in a faster dissolution. In contrast, nanonization can improve the equilibrium solubility of a drug, but the selection of the appropriate excipient used for nanonization is essential, because out of the two used polymers, only the PVPK-25 had an increasing effect on the solubility. This phenomenon can be explained by the molecular structure of the excipients. Based on laser diffraction measurements, PVPK-25 could also inhibit the aggregation of the particles more effectively than PVA, but none of the polymers could hold the nanonized samples in the submicron range until the end of the measurements.

Characterisation of de-structured starch and its shear-thickening mechanism

This study focuses on the relationship between the starch de-structuring process and its shear-induced rheological properties. Waxy potato starch underwent a de-structuring process (120–150 °C for 30 min under continuous stirring) where the starch granules were completely gelatinised and subsequently reduced into fragments and polymer chains. A significant increase in the degree of branching was noted in 140 and 150 °C de-structured waxy potato starch (DWPS) samples as compared to its native form. However, no significant change in the side-chain profile of DWPS samples was detected. Laser diffraction measurements revealed the presence of large particles in DWPS samples, which indicated that the starch de-structuring process into its macromolecules was incomplete even at 150 °C for 30 min. Complex shear-induced behaviours (shear-thickening, shear-induced gelation and/or anti-thixotropy) were noted in 120 and 140 °C DWPS samples. Such behaviours were attributed to the reduction in size and increased number of fragments, together with interactions among fragments and amylopectin chains in these DWPS samples when subjected to shear. • Amylopectin chains were cleaved close to their center during de-structuring. • De-structuring treatment resulted in a gradual increase in degree of branching. • De-structuring treatment did not affect the starch side-chain profile. • De-structuring process was incomplete even at 150 °C. • Size of starch fragments contributed to shear-induced rheological properties.

Determination of sedimentation speed of soil micro-particles from laser diffraction measurements

Determination of sedimentation speed of soil micro-particles from laser diffraction measurements

Optically Induced Picosecond Lattice Compression in the Dielectric Component of a Strongly Coupled Ferroelectric/Dielectric Superlattice (Adv. Electron. Mater. 6/2022)

Ultrafast Optical Excitation The structure of an epitaxial BaTiO3/CaTiO3 ferroelectric/dielectric superlattice responds to aboveband gap ultrafast optical excitation with a compression of the dielectric CaTiO3 layer is presented in article number 2101051 by Paul G. Evans and co-workers. This unusual response is a consequence of the screening of the polarizing field due to the ferroelectric BaTiO3 layer. The distortion is developed on the picosecond timescale and is apparent in ultrafast x-ray free-electron laser diffraction measurements.

Investigation of Quantitative X-ray Microscopy for Assessment of API and Excipient Microstructure Evolution in Solid Dosage Processing.

Assessment and understanding of changes in particle size of active pharmaceutical ingredients (API) and excipients as a function of solid dosage form processing is an important but under-investigated area that can impact drug product quality. In this study, X-ray microscopy (XRM) was investigated as a method for determining the in situ particle size distribution of API agglomerates and an excipient at different processing stages in tablet manufacturing. An artificial intelligence (AI)-facilitated XRM image analysis tool was applied for quantitative analysis of thousands of individual particles, both of the API and the major filler component of the formulation, microcrystalline cellulose (MCC). Domain size distributions for API and MCC were generated along with the calculation of the porosity of each respective component. The API domain size distributions correlated with laser diffraction measurements and sieve analysis of the API, formulation blend, and granulation. The XRM analysis demonstrated that attrition of the API agglomerates occurred secondary to the granulation stage. These results were corroborated by particle size distribution and sieve potency data which showed generation of an API fines fraction. Additionally, changes in the XRM-calculated size distribution of MCC particles in subsequent processing steps were rationalized based on the known plastic deformation mechanism of MCC. The XRM data indicated that size distribution of the primary MCC particles, which make up the larger functional MCC agglomerates, is conserved across the stages of processing. The results indicate that XRM can be successfully applied as a direct, non-invasive method to track API and excipient particle properties and microstructure for in-process control samples and in the final solid dosage form. The XRM and AI image analysis methodology provides a data-rich way to interrogate the impact of processing stresses on API and excipients for enhanced process understanding and utilization for Quality by Design (QbD).

Shea butter (Vitellaria paradoxa) and Pentaclethra macrophylla oil as lipids in the formulation of Nanostructured lipid carriers

Natural lipids obtained from plant or animal sources have become very useful in drug delivery due to their better biocompatibility and lower in vivo toxicity compared to synthetic and semi-synthetic lipids. Pentaclethra macrophylla oil and shea butter (Vitellaria paradoxa) have been evaluated as lipids in the formulation of nanostructured lipid carriers (NLCs) using four surfactants (Tween 80, Span 20, sodium dodecyl sulfate and Plantacare® 2000). Nanostructured lipid carriers were prepared by high-pressure homogenization and characterized using photon correlation spectroscopy (PCS), laser diffraction (LD), and zeta potential measurements. The optimal formulations were loaded with Cola hispida extract and the physical properties and in vitro antioxidant activities were evaluated. Stable nanosized lipid carriers were obtained using Tween 80 and Span 20 at the ratio of 1:1 as emulsifying agents. Formulations containing 2% w/w shea butter and 8%w/wP. macrophylla oil had the lowest particle sizes (131.467 ± 1.504 to 163.330 ± 1.909) and polydispersity index (0.143 ± 0.005 to 0.197 ± 0.018). The extract-loaded formulations were stable and demonstrated significant (p < 0.05) antioxidant capacity except for formulations prepared with carnauba wax which demonstrated significantly (p < 0.01) lower antioxidant capacity compared to the extract and the other formulations. The properties of the NLCs were influenced by the type and concentration of solid lipid used. Pentaclethra macrophylla oil and shea butter were valuable lipids in the formulation of nanostructured lipid carriers for the delivery of Cola hispida extract.

Surface Studies on Glass Powders Used in Commercial Glass-Ionomer Dental Cements.

The surface properties of three commercial ionomer glass powders, i.e., Fuji IX, Kavitan Plus and Chemadent G-J-W were studied. Samples were analyzed by X-ray fluorescence spectroscopy (XRF), and the density was determined by gas pycnometry. Morphology was studied using scanning electron microscopy (SEM) and laser diffraction (LD) technique, whereas low-temperature nitrogen sorption measurements determined textural parameters like specific surface area and pore volume. Thermal transformations in the materials studied were evaluated by thermogravimetric analysis (TGA), which was carried out in an inert atmosphere between 30 °C and 900 °C. XRF showed that Fuji IX and Kavitan Plus powders were strontium-based, whereas Chemadent G-J-W powder was calcium-based. Powders all had a wide range of particle sizes under SEM and LD measurements. Specific surface areas and pore volumes were in the range 1.42–2.73 m2/g and 0.0029 to 0.0083 cm3/g, respectively, whereas densities were in the range 2.6428–2.8362 g/cm3. Thermogravimetric analysis showed that the glass powders lost mass in a series of steps, with Fuji IX powder showing the highest number, some of which are attributed to the dehydration and decomposition of the polyacrylic acid present in this powder. Mass losses were more straightforward for the other two glasses. All three powders showed distinct losses at around 780 °C and 835 °C, suggesting that similar dehydration steps occur in all these glasses. Other steps, which differed between glass powders, are attributed to variations in states of water-binding on their surfaces.

Comparison of particulate matter emission and soluble matter collected from combustion cigarettes and heated tobacco products using a setup designed to simulate puffing regimes

An experimental setup was designed and optimized to collect particulate matter suspended in cigarettes smoke or in the aerosol generated during the use of heated tobacco products (HTPs). The setup is mainly based on a gas washing flask containing water where particulate matter and soluble compounds can be trapped, resembling interaction in the body. This system allows to perform puffing experiments in conditions similar to those of the Health Canada Intense puffing regime. In the study, cigarettes and Heets (in IQOS heater) from Philip Morris Products were used. Complementary characterization of this particulate matter has been extracted from experiments on a gas washing flask containing isopropanol. Total organic carbon analysis, laser diffraction, UV-vis spectrophotometry and transmission electron microscopy measurements have shown that cigarette smoke contains a large number and content of compounds soluble in water and isopropanol, together with solid particles generated during combustion. In contrast, negligible presence of non-combustion related particles was detected in Heets aerosol samples. These facts, together with the higher amount of water soluble compounds and higher number of polyaromatic hydrocarbons detected in the cigarettes smoke, allow to conclude that HTPs are less harmful than combusted cigarettes.

Biocompatible homogeneous particle formation via the self-complexation of chitosan with oleic acid and its application as an encapsulation material for a water-insoluble compound

A simple, precise method for preparing submicrometer-sized homogeneous particles as potential delivery carriers for water-insoluble compounds was developed using self-complexation of chitosan (CHI) and oleic acid (OA). One-step mixing of a CHI aqueous solution and an ethanol solution containing fatty acids provided homogeneously turbid dispersions at ambient conditions. Mean particle diameters measured using dynamic light scattering and laser diffraction measurements ranged from 300 to 1000 nm with narrow diameter distributions (polydispersity index < 0.2, for 600-nm particles), depending on their preparation conditions. Scanning transmission electron microscopy (STEM) also indicated the formation of submicron-sized particles. Based on measurements of Fourier-transform infrared (FT-IR) spectra, fluorescent spectra with pyrene, and small angle X-ray scattering (SAXS), this study proposed particle formation via electrostatic complexation between positively charged CHI and negatively charged oleate ions, and aggregation of hydrophobic interaction between alkyl groups of OA. The diameter distribution of the particles did not change even after storage for three months at room temperature and pH 5.0. Furthermore, the hydrophobic bioactive compound curcumin was successfully encapsulated into complex particles without use of additional emulsifiers as dispersant for curcumin. Particle suspension encapsulating curcumin could be concentrated using evaporation of the aqueous dispersion medium without significant changes in their diameter. These findings demonstrate that CHI-OA complex particles are potentially advantageous for encapsulating/dispersing hydrophobic compounds in aqueous media in order to develop novel liquid-based foods and beverages with improved physicochemical stability and enhanced health functionality. • Biocompatible fine particles were obtained using a one-step procedure. • Homogenous particle size distribution could be maintained for a long time. • Particles formed via non-covalent interactions between chitosan and oleic acid. • Particle size was tunable (300–1000 nm) by adjusting preparation conditions. • Efficient encapsulation of the lipophilic compound curcumin was demonstrated.

Comparison between hydrometer and laser diffraction methods in the determination of clay content in fine-grained soils

Clay content is the main characterizing parameter when classifying fine-grained soils. Hydrometer method (HD) is commonly used in geotechnics to obtain the grain size distribution properties of fine-grained soils. However, this test is laborious and time consuming as compared to alternative methods such as laser diffraction (LD). In this study, a comparison between the results for clay content of 19 samples from different locations in Finland using HD and LD methods was carried out aiming at obtaining a mathematical expression that allows to transform LD measurements into HD results. The results were statistically compared showing significant differences between the results of these two techniques and underestimation of the clay content by the LD method was observed. Based on the results, the reliability of the laser method in the determination of clay content is discussed.

Hydraulic reactivity and cement formation of baghdadite

AbstractIn this study, the hydraulic reactivity and cement formation of baghdadite (Ca3ZrSi2O9) was investigated. The material was synthesized by sintering a mixture of CaCO3, SiO2, and ZrO2 and then mechanically activated using a planetary mill. This leads to a decrease in particle and crystallite size and a partial amorphization of baghdadite as shown by X‐ray powder diffraction (XRD) and laser diffraction measurements. Baghdadite cements were formed by the addition of water at a powder to liquid ratio of 2.0 g/ml. Maximum compressive strengths were found to be ~2 MPa after 3‐day setting for a 24‐h ground material. Inductively coupled plasma mass spectrometry (ICP‐MS) measurements showed an incongruent dissolution profile of set cements with a preferred dissolution of calcium and only marginal release of zirconium ions. Cement formation occurs under alkaline conditions, whereas the unground raw powder leads to a pH of 11.9 during setting, while prolonged grinding increased pH values to approximately 12.3.

Analyzing ophthalmic suspension particle size distributions using laser diffraction: Placebo background subtraction method

The current study demonstrated that the presence of excipients can interfere with the measurement of particle size distribution (PSD), a critical quality attribute of ophthalmic suspensions, by laser diffraction (LD) and that a placebo background subtraction approach can eliminate the impact of excipients on the PSD measurement. Commercially available loteprednol etabonate and brinzolamide ophthalmic suspensions were used as model suspensions. The impact of excipients in these formulations on the LD measurements was determined using a one-factor-at-a-time experimental design approach, using National Institute of Standards and Technology (NIST) traceable polystyrene particle size standards as references. Among the evaluated excipients, polymers containing polyacrylic acid were found to interfere with the PSD analysis by creating the LD signals correspond to particles ranging from a few micrometers to a hundred micrometers in size. As a result, the measured PSD of active pharmaceutical ingredient (API) particles in the formulation overlapped with or superimposed on the excipient PSD signal, leading to erroneous interpretation of the API particle size. Additionally, dispersion of brinzolamide particles in unsaturated solutions led to rapid dissolution of brinzolamide particles during the measurement, resulting in underestimation of the particle size range. Here, a placebo background subtraction approach was developed to eliminate the interference of the excipients. This newly developed LD method was also evaluated using orthogonal methods, including polarized light microscopy and scanning electron microscopy (SEM). The strategy used in this study to eliminate the interference of excipients may also be useful for other heterogeneous dispersions where excipient interference may be of concern.

Comparing multifractal characteristics of soil particle size distributions calculated by Mie and Fraunhofer models from laser diffraction measurements

Particle size distribution (PSD) is a basic soil property, closely related to main soil physical and chemical attributes. Soil PSD determined by laser diffraction (LD) may provide additional information to soil texture determined by traditional methods. In turn, LD may be implemented using either Mie or Fraunhofer calculation methods, based on different assumptions. The multifractal approach has been demonstrated to be useful for characterizing the inner structure of soil PSD. We analysed the PSDs of 18 soil horizons sampled on the most characteristic soil types from Argentina with a wide range of textural classes, from clayey to sandy, mainly developed over loess material. Our aims were to assess the multifractality between PSDs computed using either Mie scattering or Fraunhofer diffraction models, and to compare the scaling properties and multifractal behavior of PSDs from soils with contrasting textures. Fraunhofer model provided PSD curves, which were shifted toward coarser particles compared to those obtained with Mie model. Regardless calculation method, all the PSDs studied displayed a well-defined multifractal structure, as shown by singularity, f(α) versus α, and by Rènyi spectra, Dqvs q. Moreover, all singularity spectra were strong asymmetric, right deviating curves, which is consistent with a greater heterogeneity of the low values of volume frequencies for all the PSDs analysed. Soil PSDs computed by Fraunhofer model showed higher asymmetry than those computed by Mie model for 16 out of 18 horizons studied; this suggests that scaling heterogeneity mainly depends on the support length, which is larger for the PSDs computed by Mie. In addition, other features of the PSDs stemming from soil processes such as weathering intensity of loess materials may also influence multifractality. Stronger correlations were found between multifractal parameters from PSDs calculated by the two models for the most positive q moments of singularity and Renyi spectra, i.e. α10, D10, than for those gathered from the central and negative q moments. The entropy dimension, D1, significantly (P<0.05) increased with increasing clay content, in contrast to previous findings; this may be due either to differences in the inner structure of various PSD data sets compared, or to shortcomings of standard PSD measurement and calculation procedures.

Fractal structures arising from interfacial instabilities in bio-oil atomization

The intriguing multi-scale fractal patterns ubiquitously observed in nature similarly emerge as fascinating structures in two-phase fluid flows of bio-oil breakup and atomization processes. High-resolution microscopy of the two-phase flows under 15 flow conditions (cases of different flow rates of the liquid and co-flowing air streams as well as different degrees of liquid preheating) reveal that the geometrical complexities evolve under the competing/combined action of the instability mechanisms such as Kelvin–Helmholtz, Rayleigh–Taylor and Rayleigh–Plateau leading into the transition from break-up to atomization. A thorough analysis of the higher order moments of statistics evaluated based on the probability density functions from 15,000 fractal dimension samples suggest that a single-value analysis is not sufficient to describe the complex reshaping mechanisms in two-phase flows. Consistently positive skewness of the statistics reveal the role of abrupt two-phase mechanisms such as liquid column rupture, ligament disintegration, liquid sheet bursting and droplet distortions in a hierarchical geometrical entanglement. Further, large kurtosis values at increased flow inertia are found associated with turbulence-induced intermittent geometrical reshaping. Interestingly, the proposed power-law correlation reveals that the global droplet size obtained from laser-diffraction measurements declines as the two-phase geometrical complexity increases.

Using Different Approaches of Particle Size Analysis for Estimation of Water Retention Capacity of Soils: Example of Keszthely Mountains (Hungary)

PSD (particle size distribution) is a key factor affecting soil hydro-physical properties (e.g. hydraulic conductivity and water retention), which makes its determination essential. Climate change increases the importance of water retention and permeability as extreme weather events can severely impair the water supply of drought-sensitive vegetation. The amount of water in soils is expected to decrease. The modified Thornthwaite model considers soil properties such as root depth, topsoil layer thickness and particle size distribution (silt and clay fraction) of soil particles combined with the most significant soil properties. At the beginning of the research, we developed a laser diffraction method to replace the standard based “pipette” sedimentation method. The theoretical background of laser diffraction measurements is already known, but their practical application for estimating soil water retention capacity is still poorly understood. The pre-sieving of soil aggregates, the pre-treatment (disaggregation and dispersion) of the samples greatly influence the obtained results. In addition to the sedimentation method, laser diffraction measurements (Malvern Mastersizer 3000) were applied with three variants of pre-treatment. For comparison, the results of a Leptosol, a Cambisol, and a Luvisol were prepared for the first modified Thornthwaite water balance model. Significant differences appeared, especially during drought periods, which could be a basis for studying soil drought sensitivity. The development of our method can estimate the water retention capacity of soil, which could support adaptive forest management plans against climatic and pedological transformations.

Flower Inspiration: Broad‐Angle Structural Color through Tunable Hierarchical Wrinkles in Thin Film Multilayers

AbstractThe petals of some flowers form hierarchical structures when nano‐scale cuticular ridges overlay bulged epidermal cells. These hierarchical structures can broaden the observable angles of iridescence. The resulting optical effect enhances the foraging efficiency of pollinators. Although efforts have been devoted to mimicking this unique broad‐angle structural color, the intrinsic tunability offered by natural systems to control such a broadened spectrum is still absent in synthetic models. A hierarchical system is developed that provides hierarchical wrinkle‐based structures that tune the observable angles for structural color. Laser diffraction measurements demonstrate that the observable angle of reflectance is broadened in proportion to the square root of the applied compressive strain. The morphology controls the diffraction pattern: the small wrinkles control the diffraction angles and the large wrinkles broaden the observable range. The development of a multi‐mode wrinkling system to produce this broad‐angle structural color only occurs within a limited range of conditions, which are experimentally discovered and theoretically modeled. Without diffractive small wrinkles, single wrinkling modes do not display structural colors. The control of wrinkling modes mimics the tunability of petals, which gives new insight into the natural system and provides a robust foundation for tunable structural color control.

Evaluating aggregate stability, surface properties and disintegration behaviour of bauxite residue induced by Ca/Na

AbstractBauxite residue, a typical industrial solid waste which contains a large amount of Na+, is usually physically degraded. Understandings of aggregate formation, which is a critical process in soil development, are essential to facilitate ecological rehabilitation on the disposal areas. However, few studies have investigated the aggregation behaviour and mechanisms of key salt ions (Ca2+ and Na+) in residue aggregates. Therefore, an integrated method of Le Bissonnais' method, the combined determination method and laser diffraction measurements was applied to evaluate aggregate stability, surface properties and disintegration behaviour of bauxite residue following Ca/Na additions. With increasing Ca2+ addition, mean weight diameter increased, indicating improved resistance to dispersion. Ca2+ had a positive effect on flocculation of silt‐size microaggregates, while disintegration was induced following Na+ addition. Repeated laser diffraction analysis of residue samples circulating in 50 mmol L−1 electrolyte solution (Ca2+/Na+) provided a detailed view of the changes in particle size distribution as aggregates fragmented. The visualized three‐dimensional surface map revealed that Na+ promoted the disintegration of &gt;250 μm aggregates into finer dispersed particles, while Ca2+ protected the microaggregates from fragmenting into smaller particles. Variation in electrochemical properties of aggregate surfaces affected the micro‐morphology significantly. The findings provide a new approach to specify pedogenic aggregate behavior of bauxite residue, while revealing the effects of Ca2+/Na+ on aggregate stability, surface electrochemical properties and its micromorphology. The results will provide a detailed understanding of aggregate behavior during soil formation process in bauxite residue.