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The resolution of complex parts produced by laser powder bed fusion of polymers (PBF-LB/P) is defined significantly by the shape and size distribution of the feedstock powder. Its analysis is usually performed by optical measurement systems such as laser diffraction or image analysis. In this study, the most relevant particle size parameters will be extracted from a set of different measuring methods, as well as the Hausner ratio and finally discussed regarding safe and successful processability. Extracted data include the sphericity, fine fraction, volume- and number-weighted diameter distributions, and statistical significance analysis, including comparison of PA12 and carbon-black-additivated PA12. The presented results should give researchers a first impression about the suitability of polymer powders for PBF-LB/P, based on powder feedstock characterization. [ABSTRACT FROM AUTHOR]

Loess-paleosol sequences (LPS) are sensitive terrestrial archives of past aeolian dynamics and paleoclimatic changes within the Quaternary. Grain size (GS) analysis is commonly used to interpret aeolian dynamics and climate influences on LPS, based on granulometric parameters such as specific GS classes, ratios of GS classes and statistical manipulation of GS data. However, the GS distribution of a loess sample is not solely a function of aeolian dynamics; rather complex polygenetic depositional and post-depositional processes must be taken into account. This study assesses the reliability of fixed GS ratios as proxies for past sedimentation dynamics using the case study of Remizovka in southeast Kazakhstan. Continuous sampling of the upper 8 m of the profile, which shows extremely weak pedogenic alteration and is therefore dominated by primary aeolian activity, indicates that fixed GS ratios do not adequately serve as proxies for loess sedimentation dynamics. We find through the calculation of single value parameters, that “true” variations within sensitive GS classes are masked by relative changes of the more frequent classes. Heatmap signatures provide the visualization of GS variability within LPS without significant data loss within the measured classes of a sample, or across all measured samples. We also examine the effect of two different commonly used laser diffraction devices on GS ratio calculation by duplicate measurements, the Beckman Coulter (LS13320) and a Malvern Mastersizer Hydro (MM2000), as well as the applicability and significance of the so-called “twin peak ratio” previously developed on samples from the same section. The LS13320 provides higher resolution results than the MM2000, nevertheless the GS ratios related to variations in the silt-sized fraction were comparable. However, we could not detect a twin peak within the coarse silt as detected in the original study using the same device. Our GS measurements differ from previous works at Remizovka in several instances, calling into question the interpretation of paleoclimatic implications using GS data alone. [ABSTRACT FROM AUTHOR]

Real-time measurements of Suspended Sediment mass Concentration ( SSC ) and Particle Size Distribution (PSD) are of prime importance for the investigation and management of fine-sediment related processes in surface water systems and hydraulic schemes. In a field study at the waterway of the hydropower plant (HPP) Fieschertal in the Swiss Alps, the real-time measurement performance of the following techniques and instruments were assessed based on measurements in the sediment seasons of the years 2013 and 2014: (1) turbidimetry, (2) single-frequency acoustic attenuation using a standard acoustic discharge measurement (ADM) installation, (3) laser diffraction (Laser In-Situ Scattering and Transmissometry, LISST), and (4) vibrating tube densimetry using a Coriolis Flow and Density Meter (CFDM). Reference SSC s were obtained from gravimetric analysis of 219 automatically pumped water samples. LISST additionally supplied PSD every minute. The median particle diameter, d 50 , was usually 15 µm and increased occasionally to 100 µm. The turbidimeter and the ADM underestimated the SSC when the transported particles were coarser than usual. Such temporary biases resulted from the poor correlation between d 50 and SSC at this study site. The SSC s from CFDM and LISST were not or less biased by PSD variations. Mainly due to angular and flaky particle shapes, SSC from LISST needed a correction by 79% on average. With the usually prevailing silt particles, an optical path length of 5 mm and no dilution, the SSC measurement range of LISST was limited to about 1.5 g/l. The CFDM allowed measuring higher SSC than the other investigated instruments (e.g. up to 13.5 g/l). With a periodic offset correction, its relative SSC measurement uncertainty was < 20% for SSC ≥ 1.5 g/l. To reliably measure a wide range of SSC with temporarily variable PSD, a combination of instruments is recommended: e.g. a standard LISST, a CFDM, and an automatic water sampler for gravimetric reference measurements. [ABSTRACT FROM AUTHOR]

A combination of two indirect methods to measure sediment flux is presented in this study to evaluate suspended sediment transport in a hydropower reservoir. The acoustic backscatter signal (ABS) from an Acoustic Doppler Current Profiler (ADCP) is therefore applied in pre-defined transects within the reservoir in combination with a Laser In-Situ Scattering Transmissometry – stream lined device (LISST-SL). The stationary LISST-SL derived suspended sediment concentration (SSC) measurements are used to calibrate the ABS. From the LISST-SL measurements a time series of SSC is obtained. This enables, in addition, a comprehensive data analysis to evaluate the influence of natural fluctuations of the SSC on the calculated sediment flux, which should be taken into account when assessing sediment transport. Furthermore SSC measurements are done with the LISST-SL close to the reservoir bed. In areas close to the bed no information regarding the ABS is available from the ADCP measurements due to the side-lobe interference. In various studies the information from the last three valid cells is used for extrapolation. However, as result of a comparison of the LISST-SL measurements with extrapolated SSC values from the ADCP measurements it can be seen that, especially in deep reservoirs, this method has to be adapted to the in-situ conditions. [ABSTRACT FROM AUTHOR]

The distribution of micro-bubbles generated by the electroflotation process has great importance in the flotation process for fine and ultrafine particles. The objective of this study was to evaluate the influence of some parameters on the average bubble size, generated in an electroflotation cell, on 316 stainless steel cathodes with different geometries, surface finishing, and a Ti/RuO 2 mesh as an anode, by the laser diffraction method and image analysis. The average bubble size determination was conducted at different pH values, different cathode surfaces, and different types of collector. Results show that an increase in pH and current density led to a decrease of the bubble size, and that mesh electrodes and electrodes polished with coarser grit sandpaper give smaller gas bubbles. Conversely, when Flotigam EDA, sodium N-lauroyl sarcosinate or sodium oleate were added, larger bubbles were observed. Under the conditions of generation of small bubbles, higher recoveries of fine phosphate particles were observed. [ABSTRACT FROM AUTHOR]

Characterisation of Cadmium Telluride (CdTe) thin films commonly requires the use of invasive techniques for the identification of their structural growth and the detection of defects which occur during the deposition process. Structural growth and the presence of defects can affect the performance of the final device. A non-invasive inspection system for CdTe films has been developed to identify the structural properties of this material, comparing two different deposition techniques, Close Space Sublimation (CSS) and Magnetron Sputtering (MS). The proposed system utilises a 1 μm diode laser which passes through the CdTe layer, originating detectable diffraction patterns, which are characterised using image processing techniques and assessed using a neural network-based cognitive decision-making support system. Results are found to be consistent with the conventional microscopic techniques (SEM and TEM) used to analyse morphological and structural properties of thin-film CdTe solar cells. [ABSTRACT FROM AUTHOR]

Coconut is a major plantation crop of Sri Lanka and coconut millers are striving to add value to coconut shells being generated as an agricultural waste material. A leading coconut miller is mechanically grinding the shells into powder to be used by industry as a filler material or in any other way that would add value. In this study the coconut shell powder (CSP) has been analysed both physically and chemically to have a better understanding of the material its properties. Laser diffraction showed a broad distribution of sizes with a mean particle size of 34.2 microns, and by using scanning electron microscopy it was possible to recognize a variety of sizes, shapes and structures. The thermo-chemical character of CSP was studied over a temperature range of 30 °C – 800 °C using a thermogravimetric analyser. CSP was seen to pyrolyse best between 220 °C - 380 °C with a residue of 16.2% left at the end of the pyrolysis. In order to understand the thermo-chemical behavior of CSP more fully and to estimate the chemical composition, the lignin content was determined by the ASTM D 1106 – 96 method and a thermogravimetric analysis (TGA) and a differential thermogravimetric analysis (DTG) were done on the lignin as well. The CSP was pyrolysed at 550 °C to determine the ash content and using atomic absorption spectroscopy the types of metal in ash were determined. Apart from silica which could not be measured, sodium, potassium, zinc, calcium and iron were found to be the main metals. Fourier transform infrared spectroscopy (FTIR) was used for a better understanding of the chemical structure of CSP. [ABSTRACT FROM AUTHOR]

This paper deals the determination of the particle size distribution of a material nominally (and inadequately) described as “0 – 10 silica”. First, we will outline the routes to obtaining a stable set of light scattering data via wet and dry laser diffraction determination. These stable data are a prerequisite for the deconvolution to a particle size distribution. Second, we will focus on the importance of using the correct optical constants (real and imaginary parts of the refractive index) in order that the derived particle size distribution is correctly stated. In particular this robustness study will show how incorrect optical properties can influence the form (shape) of the derived distribution, plus assignation of key points in the distribution (in particular, x 10 ). Certain supplementary information is essential in confirming the correct optical properties • Density via helium gas pycnometry • X-ray diffraction (XRD) for polymorph confirmation • Becke lines for bracketing the real part of the refractive index • Volume concentration experiment for measurement of the imaginary/absorptive part of the refractive index In this manner we can then be confident of a stated particle size distribution and an awareness of the factors that can significantly affect this derived distribution. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Mineral trioxide aggregate (MTA) is commonly supplied in 1-g packages of powder that are used by some clinicians across several treatments against the manufacturer's instructions. ProRoot MTA cannot be resealed after opening, whereas MTA Angelus has a resealable lid. This study assessed changes in particle size distribution once the packaging had been opened. Methods: Fresh ProRoot MTA and MTA Angelus powder were analyzed by using laser diffraction and scanning electron microscopy and compared with powder from packages that had been opened once and kept in storage for 2 years. The ProRoot packet was folded over, whereas the MTA Angelus jar had the lid twisted back to its original position. Results: After 2 years, ProRoot MTA powder showed a 6-fold increase in particle size (lower 10% from 1.13 to 4.37 μm, median particle size from 1.99 to 12.87 μm, and upper 10% from 4.30 to 34.67 μm), with an accompanying 50-fold change in particle surface area. MTA Angelus showed only a 2-fold increase in particle size (4.15 to 8.32 μm, 12.72 to 23.79 μm, and 42.66 to 47.91 μm, respectively) and a 2-fold change in particle size surface area. Conclusions: MTA reacts with atmospheric moisture, causing an increase in particle size that may adversely affect the properties and shelf life of the material. Smaller particles have a greater predisposition to absorb moisture. Single-use systems are advised. [Copyright &y& Elsevier]

Abstract: Particulate matter generated during the cooking process has been identified as one of the major problems of indoor air quality and indoor environmental health. Reliable assessment of exposure to cooking-generated particles requires accurate information of emission characteristics especially the size distribution. This study characterizes the volume/mass-based size distribution of the fume particles at the oil-heating stage for the typical Chinese-style cooking in a laboratory kitchen. A laser-diffraction size analyzer is applied to measure the volume frequency of fume particles ranged from 0.1 to 10 μm, which contribute to most mass proportion in PM2.5 and PM10. Measurements show that particle emissions have little dependence on the types of vegetable oil used but have a close relationship with the heating temperature. It is found that volume frequency of fume particles in the range of 1.0–4.0 μm accounts for nearly 100% of PM0.1–10 with the mode diameter 2.7 μm, median diameter 2.6 μm, Sauter mean diameter 3.0 μm, DeBroukere mean diameter 3.2 μm, and distribution span 0.48. Such information on emission characteristics obtained in this study can be possibly used to improve the assessment of indoor air quality due to PM0.1–10 in the kitchen and residential flat. [Copyright &y& Elsevier]

An increasing number of spray nozzle and agrochemical manufacturers are incorporating droplet size measurements into both research and development. Each laboratory invariably has their own sampling setup and procedures. This is particularly true about measurement distance from the nozzle and concurrent airflow velocities. Both have been shown to significantly impact results from laser diffraction instruments. These differences can be overcome through the use of standardized reference nozzles and relative spray classification categories. Sets of references nozzles, which defined a set of classification category thresholds, were evaluated for droplet size under three concurrent air flow velocities (0.7, 3.1 and 6.7 m/s). There were significant, though numerically small, differences in the droplet size data between identical reference nozzles. The resulting droplet size data were used to categorize a number of additional spray nozzles at multiple pressure and air flow velocities. This was done to determine if similar classifications were given across the different airspeeds. Generally, droplet size classifications agreed for all airspeeds, with the few that did not, only differing by one category. When reporting droplet size data, it is critical that data generated from a set of reference nozzles also be presented as a means of providing a relative frame of reference. [ABSTRACT FROM AUTHOR]

BACKGROUND: Arformoterol, the (R,R) isomer of formoterol, is approved as an inhalation solution for the treatment of bronchoconstriction in patients with chronic obstructive pulmonary disease. Multiple nebulizer systems are commercially available. Different nebulizers can differ significantly in drug output, which may impact drug delivery and clinical efficacy. This study compared the aerosol properties of arformoterol delivered via 5 commonly used nebulizer systems for the home-care market. METHODS: The delivered dose of arformoterol inhalation solution (15 μg/2 mL) was collected in a glass Dreschel-type apparatus. The delivered amount in fine-droplet fraction was assessed with an Andersen cascade impactor, and droplet size (average median diameter and average percent < 5 μm) was evaluated via laser diffraction. Compressor flow rate measurements were taken after 1 min and 6 min by placing the flow meter in line with each system. RESULTS: The Pari LC Plus, Updraft II Opti-Neb, and NebuTech systems delivered similar amounts of the 15-μg nominal dose (from 23% to 25%). The Pari LC Star and Sidestream systems delivered slightly higher doses (31% and 35%, respectively). The nebulizer/compressor systems differed somewhat with respect to droplet size. The NebuTech delivered the lowest fine-droplet fraction (61%) via Andersen cascade impactor, and the smallest percent of droplets < 5 μm (40%) via laser diffraction. The Pari LC Star and Sidestream delivered the highest fine-droplet fraction (100% and 93%, respectively), and the greatest percent of droplets < 5 μm (84% and 88%). The fine-droplet fractions for the Updraft II Opti-Neb and Pari LC Plus were 93% and 89%, respectively, and the percent of droplets < 5 μm was about 67%. Compressor flow rates ranged from 3.2 L/min (Pari LC Plus) to 5.4 L/min (NebuTech). CONCLUSIONS: The results of this study demonstrate that the choice of nebulizer/compressor system can influence the aerosol properties of arformoterol inhalation solution and should be considered when prescribing nebulized medications. [ABSTRACT FROM AUTHOR]

Summary: Introduction: Recent developments concerning pressurized metered dose inhalers (pMDIs) with inhaled corticosteroids (ICS) are the introduction of ciclesonide and the replacement of propellants. As the results of in vivo studies depend on pMDIperformance, it is necessary to evaluate pMDIs in vitro for delivered dose and particle size distributions under different conditions. Methods: Fluticasone 125μg, budesonide 200μg, beclomethasone HFA100μg, and ciclesonide 160μg were compared for delivered dose and particle size using laser diffraction analysis with inspiratory flow rates of 10, 20 and 30l/s. Results: The volume median diameter of budesonide was 3.5μm, fluticasone 2.8μm, beclomethasone and ciclesonide both 1.9μm. The mouthpiece retention was up to 30% of the nominal dose for beclomethasone and ciclesonide, 11–19% for the other pMDIs. Lifespan, flow rate, and air humidity had no significant influence on particle size distribution. The delivered dose of beclomethasone, budesonide, and ciclesonide remained constant over the lifespan. The delivered dose of fluticasone 125 decreased from 106% to 63%; fluticasone 250 also decreased whereas fluticasone 50 remained constant. Conclusions: There is a significant difference in median particle size distribution between the different ICS pMDIs. Air humidity and inspiratory flow rate have no significant influence on particle size distribution. Ciclesonide 160 and beclomethasone 100 deliver the largest fine particle fractions of 1.1–3.1μm. The changes in delivered dose during the lifespan for the fluticasone 125 and 250 may have implications for patient care. [Copyright &y& Elsevier]

Sediments collected within freshwater, estuarine and marine habitats were used to trial various chemical and physical pre-treatments to develop a systematic protocol for grain-size analysis using laser diffraction. Application of this protocol mitigates the influence of bio-physical processes that may transform grain-size distributions, enabling the characterisation and quantification of 'primary' mineral sediments across the complex freshwater-marine continuum to be more reliably assessed. Application of the protocol to two Great Barrier Reef (Australia) river catchments and their estuaries reveals the ecologically relevant <20 μm fraction comprises a larger component of exported sediment than existing methods indicate. These findings are highly relevant when comparing measured data to grain-size-specific modelled sediment loads and water-quality targets. Finally, adoption of the protocol also improves the environmental interpretation of the influence of 'terrigenous sediment' in marine settings, including quantification of newly-delivered flood plume sediment. • Sediment grain-size treatment and analysis protocol across freshwater-marine systems • Method mitigates bio-physical processes that transform grain-size distributions. • Application reveals the <20 μm fraction is a larger component of exported sediment. • Protocol more accurately quantifies 'terrigenous sediment' in marine settings. [ABSTRACT FROM AUTHOR]