Laser Diffraction Measurement Research Articles

Particle aerosol generation and potential altering in airflow used for acute/repeated inhalation toxicity testing

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.

Analysis of cable eccentric diameter measurement based on the production line

In order to meet the requirements of real-time monitoring and timely adjustment of cable diameter, a laser caliper is installed on the cable production line. Based on the laser diffraction measurement technology, the related laser diameter measuring instrument was developed. This equipment adopts a CCD array sensor and two mutually perpendicular pulse laser light sources, with a single exposure of only 0.1μs. It can identify the measuring objects with instantaneous changes, such as jittery workpieces, and obtain the outer diameter of the measured object through complex algorithm processing and relevant data calculation. The equipment is designed by relying on the laser diffraction measurement method and electromagnetic induction technology and using the CCD laser diffraction principle. In addition, the error can also be introduced into the linear array CCD image collector. TCD1703C is used for the linear array CCD, and the size length of each pixel is 7μm. If the measurement result is not processed by edge subdivision, the maximum measurement accuracy can only reach 7μm resolution.

Application for Powder Dispersibility and Interface Characterization Using Low-field NMR

The dispersibility and wettability of the powder can be possible to measure by pulse NMR. The characteristic is being able to measure with good reproducibility in a short time without diluting. As a concrete measurement example of dispersibility, we compared with the particle size distribution measurement depending on the dispersion time on low concentration carbon nanotubes. Which was about 0.02%. Next, we compared the graphene dispersion sample from 10% to 50% by pulse-NMR and diluted sample by laser diffraction measurement. In the example of comparing the results in the diluted state have good correlation. However, in the case of different concentrations, there was no correlation. In addition, as a concrete evaluation example of wettability, surface treatment of powder was performed, and the difference in wettability to pure water and hexane were compared. Furthermore, an example was shown in which the wettability to the resin was also compared. Although it only shows simple applications, we think this valuation method has a high potential by the user’s idea.

An investigation in laser diffraction soil particle size distribution analysis to obtain compatible results with sieve and pipette method

Recent studies have shown that soil particle size analyses using laser diffraction method (LDM) can give compatible results compared with traditional sedimentation based methods, if the clay-silt particle size cutoff is transformed. Additionally, procedures including separation of the sand fraction by wet sieving and running a well dispersed sample of only fractions smaller than sand during laser diffraction measurement, have given promising results. The main purpose of the present study was to test a combination of these approaches for determining cutoff transformed LDM values on 44 soil samples from agricultural sites spread over Sweden, including its compatibility with the sieve and pipette method (SPM). Furthermore, these results were compared with results of transformed LDM values based on pedotransfer functions between measured LDM and SPM. Also LDM related aspects concerning scattering parameters, repeatability and organic matter calculations were studied. To find the optimum clay-silt cutoff, Lin’s concordance correlation coefficient (Lin’s CCC) was calculated. The highest value (0.977) was found with the 3.409–3.905 µm bin (a refractive index of 1.52 and an absorption coefficient of 0.1 was used). The pedotransfer-transformed LDM approach showed equally high Lin´s CCC as the cutoff-transformed approach for the different soil particle fraction size classes. With the cutoff-transformed LDM approach, 36 out of 44 samples were assigned to the same texture class as SPM, and with the pedotransfer-transformed LDM, the corresponding number was similar (34 out of 44 samples). The results here are promising for application in routine soil analyses, but more specific transformed clay-silt cutoffs and pedotransfer functions for LDM versus SPM should ideally be established for different types of soils. For this, microscopy and image analysis methods to help understand and quantify the influence of particle shapes on obtained particle size distributions are useful.

Impact of particle flocculation on the dissolution and bioavailability of injectable suspensions

Injectable suspensions occasionally exhibit variations in dissolution and bioavailability, which may impact the clinical outcome of the drug product. Here, variation in the injection method (i.e., applied shear) for triamcinolone acetonide (TA) injectable suspension (40 mg/mL) altered the flocculation state of the particles and subsequently their dissolution. Notably, TA suspensions contained primary particles of approximately 2 µm and secondary flocculates of tens of microns. The conversion between flocculated and deflocculated particles was rapid, reversible and highly shear dependent. As such, changing shear rates during laser diffraction (LD) measurement like stirring rate, sonication, and sample introduction method (micropipette vs 25-gauge needle) may result in variability in particle size distributions (PSD) that have the potential to alter drug dissolution. Furthermore, a non-sink, discriminatory in vitro release testing (IVRT) method was developed, which combined in-situ fiber optic UV with LD to simultaneously monitor the dissolution and changing PSD of the suspension. The simultaneously measured dissolution and PSD data showed that flocculated and deflocculated particles followed different dissolution pathways. Importantly, deflocculated particles dissolved up to six times faster than the flocculated particles. Similar shear-induced changes during injection could occur in a clinical setting and have implications for drug bioavailability.

Super-Cooled Large Droplet Experimental Reproduction, Ice Shape Modeling, and Scaling Method Assessment

Super-cooled large droplets (SLDs) present a unique experimental challenge for conventional horizontal spray icing wind tunnels due to gravity effects on the droplets and coalescence between the particles. Limited ice accretion shapes in this regime exist, making the verification of modeling tools and the validation of the applicability of scaling methods difficult. Furthermore, SLD accretions often occur in nature in a bimodal icing cloud, providing an additional facility challenge related to the reproduction of such clouds. The objective of this research effort is to expand the available SLD dataset to assess the capability of an existent ice accretion tool (LEWICE 2D) to predict such ice shapes. The effort also attempts to further verify the applicability of ice shape scaling methods in the SLD regime. Finally, bimodal SLD cloud reproduction and ice shape prediction is investigated. The Adverse Environment Rotor Test Stand (AERTS) at Penn State was assessed as an alternative facility to icing wind tunnels for ice accretion testing in the SLD regime. Laser diffraction measurement data analysis demonstrated that the icing nozzles used in the facility can produce an SLD within of requested values. Techniques to measure liquid water content (LWC) in the facility are also presented. LWC was controllable within . LEWICE ice shapes predicted were obtained using legacy empirical heat transfer models as well as an updated empirical heat transfer function developed at Penn State. When comparing modeling results to experimental shapes from the literature and the AERTS, LEWICE with the updated heat transfer function provided stagnation thicknesses within 5.6% of experimental values and horn protrusion within 16%. The modified Ruff scaling ice shape method was effective in the SLD regime, providing a mean deviations of 2.5% between reference and scaled ice shape characteristics. Finally, characteristics of a bimodal ice shapes were predicted by LEWICE. When comparing modeling results to experimental shapes, LEWICE with the updated heat transfer function provided predictions within 10.3% of the experimental stagnation thickness measured. It also provided horn angles with discrepancies of less than 12%. Icing limits of a bimodal icing cloud were observed to be that of a single mode SLD cloud of the same MVD, with an overall deviation of when comparing the experimental database to LEWICE.

Ecological Assessment of Particulate Material (PM5 and PM10) in Urban Habitats

Trees are especially useful biological indicators. We tested the suitability of tree leaves (Common Lime) to assess PM5 and PM10 deposition in the three summer months of 2018 in Debrecen city, Hungary. We also tested the usefulness of the cheap and simple gravimetric method to assess the PM deposition, and compared to the expensive, but standard laser diffraction method. We found significant differences between the concentrations of PM10 deposited on tree leaves, and on dust traps. A significant difference was found in the concentration of PM5 only in July. A significant difference was also found in the concentration of PM10 among months based on leaves and dust traps. For PM5 there was a significant difference among months based on leaves deposition. We found a significant positive correlation between the PM10 concentration deposited on leaves and on dust traps. A positive correlation was found between the concentration of PM based on the gravimetric and laser diffraction measurement methods. Our findings pointed out the particulate material’s washing by rain from leaves; thus, dust deposition on the surface of leaves is limited. Our results demonstrated that trees play an important role in the mitigation of air pollution, and they are a useful indicator of PM deposition for biomonitoring studies.

Size Analysis of Small Particles in Wet Dispersions by Laser Diffractometry: A Guidance to Quality Data

In the present work, the question how to obtain high-quality laser diffraction (LD) results is discussed by investigating various hurdles that can be encountered during particle size measurements in wet dispersions and the associated data interpretation. Following this an effective troubleshooting is discussed based on theoretical insight into the LD measurement. As an important element in the Mie theory, the refractive indices of the model compounds, bedaquiline and cinnarizine, were quantified using the LD software, the Becke line technique, and the single solvent technique, as described by Saveyn et al. [Saveyn H, et al. Part Part Syst Char. 2001;19:426-432]. The influence of parameters such as obscuration level, background quality, and fitting of data were investigated and a summative flow chart has been provided. Through this analysis the present work emphasizes the need for a systematic approach when conducting LD measurements, including standard performance of an obscuration titration and an extended method optimization, to reach high-quality LD results.

ジェットミル粉砕プロセスにおける粒子径分布のリアルタイムモニター

The optimum parameters for grindings by a jet mill is determined by many experiments, changing parameters, such as the feeding speed, the inlet pressure, and measure the particle size distribution of the corrected powder. This process takes long time and work load. To reduce this optimization time, in-line monitoring of the particle size distribution for the jet mill process was investigated. We could successfully monitor the particle size distribution of the ground particles, just after the jet mill process, using an in-line laser diffraction measurement system. A proportional relationship was observed between the supplying speed of the material, and the Volume based median diameter, Dv50 of the ground powder. When we changed the feed rate step by step, we could see the Dv50 value was changed with those steps.

Development of a nanosuspension for iv administration: From miniscale screening to a freeze dried formulation

The aim was to develop a nanosuspension of the poorly soluble BI XX. The nanosuspension is intended for intravenous (iv) administration in preclinical studies and should not cause any unwanted side effects. Thus, only stabilizers that are accepted for iv application should be used and isotonicity, euhydria and the absence of living microorganisms were targeted. Suspensions were prepared in a ball-mill (mixing mill MM 400 from Retsch). There were various vials used as containers; HPLC-vials were used for the small scale screening of stabilizers and injection vials for preparation of larger quantities of the nanosuspensions. Particle size distribution was analyzed by laser diffraction measurement (Mastersizer 2000). Lyophilization was used for processing of the suspensions (Christ freeze dryer). Stable nanosuspensions (d90 remained <1μm up to 7days) were prepared with several FDA-accepted stabilizers. Freeze drying was evaluated for one formulation containing 2% of the API, 0.5% of arginine and 4% of mannitol. The particle size distribution before freeze drying and after re-dispersion was comparable. After milling for 2h, no living microorganisms were detected in the nanosuspension. Various FDA accepted excipients were identified which resulted in stable nanosuspensions of BI XX. The most stable formulation was successfully freeze dried. It was proven that milling in the ball-mill decreases the presence of living microorganisms.

Applicability of laser diffraction analyses in soil physics practice

In this research we present the first results how can be used laser diffraction measurement in soil physics practice. The main goals are understanding differences of particle size distribution (PSD) measurments, developing converting methods of PSD data of different determinations. In order to realization of this survey a representative soil database of Hungarian soil types was built up. We compared PSDs of 157 soil samples measured with sieve-pipette method (SPM) and laser diffractometer technique (Malvern Mastersizer 2000) (LDM). Soil textural classes were also determined using the USDA texture triangle. We used the clay/silt fraction boundary values (clay &lt; 0.0066 mm; silt: 0.0066 - 0.05 mm) introduced for the LDM data in order to take them comparable to PSD data determined by the SPM: We got higher similarities of clay and silt fractions of the modified size boundary values. For the used dataset correspondence of texture classes derived from SPM and LDM PSD data, however is not higher than 60%.

Influence of HCl pretreatment and organo-mineral complexes on laser diffraction measurement of loess–paleosol-sequences

The influence of different sample pretreatment methods on grain size distributions in particle size analysis has been subject to controversial discussions. Standard sample preparation typically comprises the disaggregation of aggregated and agglomerated particles into single primary particles, i.e., the organic binding material is oxidized by hydrogen peroxide (H2O2) and the contained carbonates are dissolved by hydrochloric acid (HCl). The aim of this study is to evaluate the effects of HCl treatment on grain size analyses of Late Pleistocene and Holocene loess–paleosol-sequences investigated by a Beckman Coulter LS 13320 laser particle analyzer. For this purpose, samples from two different sections with different weathering degrees and sedimentary genesis were measured: (1) the Suohuoduo section on the northeastern fringe of the Tibetan Plateau (China) containing loess and paleosols, and (2) a vibracore from Düsseldorf-Grafenberg (Germany) containing calcareous loess and intercalated interglacial, interstadial and periglacial soils and soil sediments. All samples were pretreated with hydrogen peroxide and sodium pyrophosphate. Subsequently, the samples were prepared with and without the addition of HCl. There is no significant association of the HCl-induced grain size modifications after the HCl treatment with the calcium carbonate content. Conversely, a distinct dependence of the modification of grain size distributions on the content of organic matter, the weathering degree of the sediment, and the presence of stable aggregates as well as organo-mineral complexes was observed. Consequently, pretreating post-depositionally modified aeolian sediments with HCl may result in misleading grain size distributions and should be avoided in standard analyses of loess–paleosol-sequences. However, the HCl-induced modification of grain size distributions provides an indication of the existence of stable aggregates or organo-mineral complexes.

Preparation of Reversible Thermochromism Supramolecules of 4-Aminophenol-Modified Polydiacetylene

A novel diacetylene monomer was synthesized via the esterification of 10,12-pentacosadiynoic acid with 4-aminophenol. The polymer of 10,12-pentacosadiynoic acid-4-aminophenyl ester was formed by self-assembly of the monomer, followed by UV irradiation at room temperature. It was characterized by the methods of NMR, laser diffraction, SEM and UV measurement. The polymer demonstrated a reversible purple-to-red colorimetric transition when the temperature changes from 25 to 70°C.

Effect of Drying on Rheological, Thermal, and Structural Properties of Desert Truffles (Terfezia Claveryi) Powder Dispersions

The effect of drying methods (freeze-drying and tray-drying) on the rheological, thermal and functional properties of truffle flour dispersion was studied. Sieve analysis showed the number of finest particles in the freeze-drying samples were significantly higher than the tray-drying samples whereas no significant difference was observed in the particle size distribution through laser diffraction measurement. The freeze-drying sample had significantly higher water holding capacity, sediment volume fractions, and superior instrumental color values than the tray-drying sample. Upon thermal scanning, two distinct starch-lipid complex melting transitions for the freeze-drying and one for the tray-drying sample were detected. Contrary to differential scanning calorimetric measurement, the oscillatory shear measurement successfully detected a distinct gelatinization temperature for the freeze-drying sample between 64 and 67.6°C. The mechanical rigidity of the dispersion was significantly influenced by the drying method and the freeze-drying sample exhibited the higher mechanical strength over the tray-drying sample throughout the frequency range (0.1 to 10 Hz). Viscoelasticity of the dispersion was estimated by a power-type relationship correlating the elastic modulus and frequency. Various shapes of truffle particles including rod, round, oval, and irregular were observed through the scanning electron microscope. This study provided in-depth knowledge on structural/rheological properties of truffle powder produced by two drying processes.

Identifying Improved Standardized Tests for Measuring Cement Particle Size and Surface Area

The Blaine fineness (Blaine) of a cement powder is a single parameter that is meant to characterize the specific surface area of a cement; Blaine is assumed to be linked to physical and mechanical properties of the hydrated cement such as strength, setting time, and rheology. However, a single parameter cannot characterize the particle-size distribution of a cement powder, on which the hydration kinetics and solid properties depend. As the cement industry continues to develop more sophisticated blended cements, it will be even more clearly seen that a single parameter fails to capture the true complexity of a cement. In addition to measuring the Blaine, cement producers use the laser diffraction measurement of the entire particle-size distribution for quality control of their cements. Despite the wide use of this measurement by the cement industry, laser diffraction is not a standardized test. This project's goal was to examine various tests, such as laser diffraction and Blaine, that measure the particle-size distribution and total surface area of cement powder and then to determine the most appropriate test on the basis of correlation with the macroproperties of the cement paste or mortar. The shape of the cement particles for a partial particle size range was determined with X-ray computed microtomography (X-ray CT); the relationship between X-ray CT, the Brunauer–Emmett–Teller (BET) surface area method, laser diffraction, and Blaine measurements was explored. The more fundamental and sophisticated experiments, nitrogen BET and X-ray CT, were used as ground truth to critically evaluate the laser particle-size distribution and Blaine fineness measurements. The standardization of the laser diffraction test method is proposed.

An In Vitro Assessment of Aerosol Delivery Through Patient Breathing Circuits Used with Medical Air or a Helium–Oxygen Mixture

The bench experiments presented herein were conducted in order to investigate the influence of carrier gas, either medical air or a helium-oxygen mixture (78% He, 22% O2), on the droplet size distribution and aerosol mass delivered from a vibrating mesh nebulizer through a patient breathing circuit. Droplet size distributions at the exit of the nebulizer T-piece and at the patient end of the breathing circuit were determined by laser diffraction. Additional experiments were performed to determine the effects on measured size distributions of gas humidity and of the droplet residence time during transport from the nebulizer to the laser diffraction measurement volume. Aerosol deposition in the nebulizer, breathing circuit, and on expiratory and patient filters was determined by photometry following nebulization of sodium fluoride solutions into the breathing circuit during simulated patient breathing. With no humidification of the carrier gas, droplet volume median diameter (VMD) at the exit of the nebulizer T-piece was 5.5±0.1 μm for medical air, and 4.3±0.1 μm for helium-oxygen. Varying the aerosol residence time between the nebulizer and the measurement volume did not affect the measured size distributions; however, humidification of the carrier gases reduced differences in VMD at the nebulizer exit between medical air and helium-oxygen. At the patient end of the breathing circuit, droplet VMDs were 1.8±0.1 μm for medical air and 2.2±0.1 μm for helium-oxygen. The percentages of sodium fluoride recovered from the nebulizer, breathing circuit, patient filter, and expiratory filter were, respectively, 29.9±8.3, 40.4±5.6, 8.3±1.5, and 21.5±2.1% for air, and 32.6±2.2, 36.3±0.7, 12.0±1.4, and 19.1±1.1% for helium-oxygen. Ventilation with helium-oxygen in place of air-oxygen mixtures can influence both the droplet size distribution and mass of nebulized aerosol delivered through patient breathing circuits. Assessment of these effects on aerosol delivery is important when incorporating helium-oxygen into patient ventilation strategies.

Aging of TiO 2 nanocomposites used in sunscreen. Dispersion and fate of the degradation products in aqueous environment

Aging in water of a TiO 2-based nanocomposite used in sunscreen cosmetics has been studied as a function of light and time. It consisted initially in a TiO 2 core, coated with Al(OH) 3 and polydimethylsiloxane (PDMS) layers. Size measurement, coating alteration, and surface charge were followed by laser diffraction, TEM/EDS, ICP-AES and electrophoretic mobility measurement. The nanocomposite rapidly underwent progressive dispersion in the aqueous phase, enabled by the dissolution of the PDMS layer. A stable suspension of colloidal byproducts from 50 to 700 nm in size was formed. Their positively charged Al(OH) 3 surface was evidenced with an isoelectric point around 7–8, controlling the dispersion stability. The critical coagulation concentrations measured with NaCl and CaCl 2 was 2 × 10 −2 and 8 × 10 −3 M respectively. The presence of natural organic matter affected the colloidal stability according to the NOM/byproduct ratio. A 2 wt% ratio favored bridging flocculation, whereas a 20 wt% ratio induced sterical stabilization.

Stability of particle suspensions after fine grinding

Abstract The objective of this work was to investigate the physical stability of sub-micron particle suspensions of organic crystalline food compounds after grinding. A Dynomill ball mill was used in combination with zirconium oxide grinding medium beads. The organic product was a poor water soluble product. During grinding the average particle diameter of the particulate product was reduced to a minimum value in the sub-micron range. Forward light scattering was used to analyze the particle size distribution. Dynamic light scattering measurements, on the other hand, showed that there were aggregates present after grinding. The difference in the obtained particle size distributions using both techniques was related to the shear in the measurement device, i.e. in the laser diffraction measurement the shear was higher than in the dynamic light scattering device. Thus in the laser diffraction measurement the aggregates were broken up by shear, while this was not the case in the dynamic light scattering measurements. The difference in the measurements showed that the particles formed aggregates at low to zero shear. The aggregation behaviour of the particles was studied by measuring the sedimentation behaviour of the particles suspension at various pH values. The impact of the pH on the aggregation rate was explained by the zeta potential of the particles. The suspensions were less stable near the iso-electric point of the particles.

Flammability of heat transfer fluid aerosols produced by electrospray measured by laser diffraction analysis

Accidental release of pressurized high flash point heat transfer fluids can result in fire and explosion hazard scenarios in the process industry. An experimental investigation on ignition of aerosols of a heat transfer fluid is carried out, and characterization of aerosol and its ignition process by non-intrusive laser diffraction technique is reported. Propagation speed of the aerosol combustion flame front as analyzed from the laser diffraction measurement agrees with high-speed visual camera observation. Flammability of the aerosol, which is based on the chances of the global flame appearance in the aerosol, is mainly controlled by aerosol droplet size and the droplet volume concentration.

Experimental and Numerical Investigation on Humidity Distribution in an Environmental Chamber

Environmental chamber is widely used for testing the performance of the equipment with all kinds of natural ambient parameters. In this study, water droplet generated from ultrasonic humidifier is ascertained by laser diffraction measurement technology. The accurate droplet size and distribution is offered to CFD simulation as the initial condition. Humidity distribution with different initial conditions is studied by both experiment and CFD simulation. Comparisons show that the proposed CFD method can provide reliable results in simulation on the humidity distribution. The numerical and experimental results indicate that as the increase of inlet temperature, fluctuation of relative humidity (RH) at each point decrease with the time. Under the inlet condition with low-humidity, the deviation of average RH is decrease with inlet temperature. On the other hand, under the high-humidity condition, the difference of average RH is getting larger with the increase of inlet temperature. Compared with the mean value, the fluctuation of the humidity is big but the RH at measuring points is close to the inlet RH value under the inlet condition with low humidity.