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The effect of two-stage thermal disintegration of sewage sludge on the particle size distribution using laser diffraction method has been studied. The sludge was sampled from municipal sewage treatment plant after each stage of disintegration. The first stage of disintegration known as homogenization proceeds at temperature of 70-90°C and pressure of 3 bar, the second stage called thermal hydrolysis was performed at temperature of 160-170°C and pressure of 6 bar. It was found that the first stage of disintegration has the strongest impact on the reduction of the sludge particle size and changes in chemical properties. The maximum size of the particles from raw sewage before disintegration was 310 μm. After first stage of the process average size of the particles was 250 μm, and during the second stage it was reduced to 226 μm. Sludge disintegration degree (DDCOD) of 59% confirms high effectiveness of the process. We established that the redox potential (Eh) of sludge effluents was changed after each step of the studied process. Furthermore, chemical oxygen demand (COD) increases which leads to the conclusion that resizing of floccules is accompanied by hydrolysis. [ABSTRACT FROM AUTHOR]

Abstract: Pyrimidine-based chiral compounds were successfully synthesized via Mitsunobu reaction. The chiral molecules with rigid molecular shape can function as chiral inducers (chiral dopant) to prepare cholesteric liquid crystal (CLC) electrolyte solutions. We carried out electrochemical polymerization in the CLC electrolyte solution thus prepared with the chiral inducer. The polymerization in the CLC afforded chiroptically active polymer films. The synthesis of the pyrimidine-based chiral inducer, electrochemical polymerization, and observation of a surface image of the polymer were carried out. It is noted that the polymer shows laser diffraction in the visible range due to a periodic pattern produced by imprinting of structural chirality of the CLC electrolyte solution. The laser diffraction patterns are multiple circles, implying occurrence of stimulated emission via periodic patterns of the cholesteric order. [Copyright &y& Elsevier]

This investigation is concerned with the comparison of the advantages and disadvantages of subsieving techniques widely used in mineral processing throughout the world. With this purpose, the subsieving techniques of Andreasen pipette, Coulter counter, and laser diffraction methods were compared each other by determining the relationship between specific surface area and particle size distribution. In the tests, the two different standard quartz sand samples (A and B) from the Official Material Testing Institute for Nonmetallic Minerals, Clausthal-Zellerfeld with a particle density of ρ = 2.65 g/cm3were used. As a result, the Coulter counter method had the most favorable results in terms of calculated specific surface areas of 3848 cm2/g for sample A and 2852 cm2/g for sample B, with standard deviations 41.29 and 32.48, respectively. [ABSTRACT FROM AUTHOR]

In the recent years pulmonary drug delivery system is found to be preferred route of administration for various drugs. It has been divided into 3 classes: Nebulizers, pMDI, DPI.DPI are used as an alternative to pMDI because pMDI contains propellant (CFC) which has ozone depletion characteristics. DPI delivers medication in the form of dry powder to lungs. DPI is formulated either as a carrier based system or carrier free system. A wide range of dry powder inhaler devices are presently available in the market to deliver drugs with maximum drug delivery and low variability. This review focuses on the DPI formulation, factors affecting performance of DPI, and evaluation parameters. The development of DPI is governed by regulatory bodies. FDA and EMEA supported by pharmacopoeia are responsible for assessing safety and efficacy. [ABSTRACT FROM AUTHOR]

Citrate coated magnetite nanoparticles (NPs) were prepared by a modified coprecipitation technique in the presence of sodium citrate and sodium acetate. The citrate coated NPs showed a close particle size distribution, superparamagnetic behavior, and single crystalline nature. Water dispersions of magnetite NPs were analyzed by laser diffraction; this technique revealed that the NPs form micrometer sized aggregates. It was found that the size of the aggregates depends strongly on the time of ultrasonic agitation and the citrate shell. [ABSTRACT FROM AUTHOR]

Abstract: This paper highlights the fact that particle size distribution (PSD) is not unique for the same product, and is dependent on the chosen measurement technique, especially for asymmetric shapes. Laser diffraction and 2D image analysis are commonly used PSD measurement techniques. However, the results may not be representative of the true physical dimensions of the particles. The influence of particle shape on PSD results obtained from 2D/3D image analysis and laser diffraction was investigated. Two metallic powders presenting extreme shape properties (round and elongated particles) were analyzed, as well as a blend of the two pure products. 2D image analysis and laser diffraction results were compared to 3D image analysis (measuring the true particle size). This paper compares the PSD results obtained from the three methods. Some commonly used size parameters in image analysis software did not give meaningful results in regard of the true physical dimensions of the particles. The existence of the two populations (products with extremely different shape and size characteristics) could not be identified with such size parameters, and laser diffraction also performed poorly. The PSD obtained from more precise size parameters (image analysis) better corresponded to the true dimensions of the particles. This study highlights the strengths and weaknesses of particle size analysis techniques when studying products presenting diverse particle shapes, and points out that caution is required in the choice of the size parameters, and in the interpretation of PSD results. [Copyright &y& Elsevier]

Abstract: While various techniques for measuring particle size distributions (PSD) of particulate matter (PM) exist, there is no a single agreed upon standard or reference method for PM with different characteristics. This study investigated differences in the PSD measurements by four PSD analyzers: LS13 320 multi-wave length laser diffraction particle size analyzer, LS230 laser diffraction particle size analyzer, LA-300 laser scattering particle size analyzer, and Coulter Counter Multisizer3 (CCM3). Simultaneously collected total suspended particulate (TSP) samples in a commercial egg production house were analyzed by the four analyzers for PSDs. In addition, four types of testing powders (limestone, starch, No.3 micro aluminum, and No.5 micro aluminum) were also analyzed by these four PSD analyzers. The results suggest when comparing measured mass median diameters (MMDs) and geometric standard deviations (GSD) of the PSDs, the laser diffraction method (LS13 320, LS230 and LA-300) provided larger MMDs and broader distributions (GSDs) than the electrical sensing zone method (CCM3) for all samples. When comparing mass fractions of PM10 and PM2.5 between the measured values and the lognormal fitting values derived from the measured MMDs and GSDs, lognormal fitting method produced reasonably accurate PM10 mass fraction estimations (within 5%), but it failed to produce accurate PM2.5 mass fraction estimations. The measured PM2.5 mass fractions significantly differed from the lognormal fitting PM2.5 fractions and the mean differences reached as high as 95%. It is strongly recommended that when reporting a PSD of certain PM samples, in addition to MMD and GSD, the mass fractions of PM10 and PM2.5 should also be reported. [Copyright &y& Elsevier]

Abstract: A number of reports have proposed that recently developed laser diffraction instruments show potential for automating the measurement of particle size distributions (texture) in soil and related materials, but relationships to standard sieve-sedimentation measurements have been poor and inconsistent. Measurements with a commercially available laser diffraction instrument (Horiba LA-920) on five soils having a wide range of textures (silty clay to sand) showed wide variability for proportions of clay, silt and sand when the weight of the sample was varied resulting in unacceptable consistency and conformity with hydrometer measurements. Detailed measurements were subsequently made on systematic combinations of four known silt size fractions (0–5, 38–45, 75–90 and 125–150μm diameter), to explore the reasons for the variable results. Samples weighing less than 0.10, 0.15 and 0.20g of the 38–45, 75–90 and 125–150μm diameter fractions, respectively, were not detected by the instrument. Calculations of the probable numbers of particles in these samples ranged from 0.06×106 to 1.0×106. There were, however, 2445×106 particle in a 0.05g of 0–5μm diameter sample, and was detected by the instrument. This showed that there is a threshold of the number of particles required for detection. Alternatively, similar and greater weights of small diameter particles result in potential saturation of the detector. Saturation occurred when laser light transmission was low (<20%). Even before saturation of the detector, an interaction was detected when combinations of small and large particles were mixed such that the proportion of small particles tended to be over-estimated and large particles under-estimated. Percentage laser light transmission measurements were inadequate to guide development of calibrations to correct for threshold/saturation limits and light competition problems. It was concluded that the geometric change in numbers of particles as the size decreases in a given weight of sample is too large to allow the use of current laser diffraction instrumentation for particle analyses of soil and related samples where the sizes in the distribution are from clay to sand or even with a narrower range of sizes (e.g., clay or silt). [Copyright &y& Elsevier]

Context: Salbutamol sulphate is widely used as bronchodilator for the treatment of asthma. Its use is limited by the relatively short duration of action and hence sustained delivery of salbutamol sulphate offers potential benefits to patients. Objective: This study explores the preparation of lipid microparticles (LMs) as biocompatible carrier for the prolonged release of salbutamol sulphate. Materials and methods: The LMs were produced using different lipidic materials and surfactants, by classical melt emulsification-based methods (oil-in-water and water-in-oil-in-water emulsions) and the spray congealing technique. Results: For the LMs obtained by melt emulsification a lack of release modulation was observed. On the other hand, the sustained release of salbutamol sulphate was achieved with glyceryl behenate microparticles prepared by spray congealing. These LMs were characterized by scanning electron microscopy, X-ray diffractometry and differential scanning calorimetry. The drug loading was 4.72% (w/w). The particle size distribution measured by laser diffraction and electrical zone sensing was represented by a volume median diameter (Dv50) of 51.7-71.4 µm. Increasing the atomization air pressure from 4 to 8 bar produced a decrease of the Dv50 to 12.7-17.5 µm. Conclusions: Incorporation of the hydrophilic salbutamol sulphate into LMs with sustained release characteristics was achieved by spray congealing. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this research was to characterize and interpret the coarse basal zones that are common in thin loess deposits that overlie coarser-textured sediment. To that end, we sampled nine pedons in northeastern Wisconsin and the Upper Peninsula of Michigan, each of which had formed in thin (≤55cm) loess over sandy glacial sediment. At most of these sites, the loess became noticeably coarser near the lithologic discontinuity. The loess has a primary particle size mode in the coarse silt or fine, very fine sand fraction (≈30–65μm) and a secondary mode in the fine or medium sand fraction (≈200–400μm). We attribute the secondary mode to mixing of underlying sands into the loess, either during loess deposition or by post-depositional pedoturbation. In thin loess, pedoturbation processes can penetrate into the underlying sediment, facilitating mixing upward as far as 50cm into the loess. Silt from the loess has also been mixed into the underlying sandy sediment. Alternatively, in some pedons, the loess itself coarsens with depth; the particle size mode for the loess becomes increasingly coarser with depth. This coarsening suggests that, during loess deposition, one or more of the following was occurring: (1) wind velocities were decreasing over time, (2) the textural character of the loess source area(s) were changing/decreasing, or (3) additional source areas—with finer-textured sediment—became more dominant over time. Our research demonstrates the utility of detailed particle size data for detecting and interpreting the paleoenvironmental history of loess. We also document the extent to which pedoturbation can impact the original textural characteristics of loess (or any sediment) that occurs as a thin surficial mantle. [Copyright &y& Elsevier]

Hitherto the method of laser diffraction has been used only for determining particle size distribution (PSD) of mixtures. This paper presents an extension of that measurement approach to include the determination of the number of particles. The described method may find practical application in a variety of disciplines, including biology (e.g. for determination of population sizes of micro- and mesofauna), agricultural sciences (e.g. with relation to the study of soils), and Earth science (e.g. with relation to sediments and lands), among others. [ABSTRACT FROM AUTHOR]

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]

Granulometry is the regulatory category where the differences between traditional materials and nanomaterials culminate. Reported herein is a careful validation of methods for the quantification of dispersability and size distribution in relevant media, and for the classification according to the EC nanodefinition recommendation. Suspension-based techniques can assess the nanodefinition only if the material in question is reasonably well dispersed. Using dispersed material of several chemical compositions (organic, metal, metal-oxide) as test cases we benchmark analytical ultracentrifugation (AUC), dynamic light scattering (DLS), hydrodynamic chromatography, nanoparticle tracking analysis (NTA) against the known content of bimodal suspensions in the commercially relevant range between 20 nm and a few microns. The results validate fractionating techniques, especially AUC, which successfully identifies any dispersed nanoparticle content from 14 to 99.9 nb% with less than 5 nb% deviation. In contrast, our screening casts severe doubt over the reliability of ensemble (scattering) techniques and highlights the potential of NTA to develop into a counting upgrade of DLS. The unique asset of centrifuges with interference, X-ray or absorption detectors-to quantify the dispersed solid content for each size interval from proteins over individualized nanoparticles up to agglomerates, while accounting for their loose packing-addresses also the adsorption/depletion of proteins and (de-)agglomeration of nanomaterials under cell culture conditions as tested for toxicological endpoints. [ABSTRACT FROM AUTHOR]

Purpose: There is a growing interest in the characterization of the particle size of sediment due to its impact on particle dynamics, especially for connectivity purpose. This study determined the particle size distribution of suspended sediment in a mountainous catchment, with the aim to evaluate the variability of particle size during floods, the main controlling factors, and if indirect information from hillslopes was useful for the interpretation of particle size measured at the catchment outlet. This work involved the development of a measurement protocol. Material and methods: Samples were collected automatically from streamwater during flood events using an ISCO 3700 sampler. Five events were analyzed for their particle size distributions using a Malvern Mastersizer 2000. Because the samples were too concentrated, two different protocols were tested to address the errors made during the subsampling step: using a pipette and a home-made device with successive dilution phases. Results and discussion: High errors occurred when using a pipette to extract particles within a stirred sample. The maximum errors were reduced from 1,600 to 30 % using the device described within this study. Particles were found to be aggregated at various levels regardless of the discharge they were sampled at. Their size was found to be either variable or stable at the event scale, and statistical analyses revealed that discharge was the factor that best correlated with particle size. The results obtained in this study are in agreement with the few other studies in comparable environments. Some hypothesis are put forward and discussed to explain the positive relationship between particle size and discharge. Input from hillslopes seems to have a measureable effect in this headwater catchment. Conclusions: While the need for in situ measurements has long been stressed in lowland rivers, estuaries, and coastal environments, it was shown that the use of an accurate dilution protocol could provide some physically interpretable measurements on the particle size distributions of suspended sediment transported in a mountainous catchment. It also appears that hillslope information has to be considered when studying particle size measured at the catchment outlet. [ABSTRACT FROM AUTHOR]

Abstract: Developments in high dose dry powder aerosol delivery will increasingly challenge the applicability of currently used aerosol characterisation techniques. With cascade impaction analysis bounce effects can negatively influence stage collection efficiency, especially with increasing impactor loads. In this study the suitability of the multi stage liquid impinger (MSLI) and the Next Generation Impactor (NGI) for the characterisation of dry powder aerosols containing up to 50mg of drug is evaluated. The occurrence of bounce effects is quantitatively assessed by comparison with data obtained from laser diffraction analysis. The liquid based impaction surfaces of the MSLI largely prevent bounce effects, but the low number of cut-off values associated with this impactor hinders accurate data interpretation. With the NGI, a standard high viscosity plate coating insufficiently reduces bounce effects, causing the fraction <1μm to be higher than what can maximally be expected based on the primary particle size distribution (PSD) obtained from RODOS dispersion. With this type of impactor, the use of solvent soaked filters as impaction surface is necessary to eliminate bounce effects. [Copyright &y& Elsevier]

In suspended culture, most relevant for biotechnological application, plant cells form aggregates. This phenomenon is of importance as it is related to productivity, leads to local heterogeneities, and might be a reason for the considerable shear sensitivity of these cultures. The valid measurement of plant cell aggregates, however, is not trivial, due to a rather large size distribution and measurement artifacts implied by the measuring method. In this study, laser diffraction was used as a novel method for characterization of Taxus chinensis cells, a major source for the antitumor agent paclitaxel. Aggregate size measured in shaking flask cultivations over 10 days revealed an increase during the growth phase of a batch cycle and a decrease during the stationary phase. During growth, the increase in bio dry weight was proportional to aggregate size. Laser diffraction was found superior to microscopy and image analysis, which had a tendency to underestimate aggregate size up to 20%. This novel approach provides a practicable, rapid, robust, and reproducible way to analyze a 100-fold more samples in considerably less time than image analysis and is therefore of especial value for quality control in industrial plant cell cultivation. [ABSTRACT FROM AUTHOR]

Abstract: Analysis on particle size distribution is very important to a wide variety of industrial processes. A new measurement system of laser diffraction analyzer, in which a divergent beam is used as the incident light, is presented in this paper. Analytical expressions are obtained to describe the spatial distribution of the scattered light in the detection plane under or without the paraxial approximation. The results show that the new measurement system behaves in a similar way to those of the laser diffraction analyzers with reverse Fourier optics (RFO) and is especially suitable for measurements on small particles. [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]

Abstract: The Twomey non-linear iteration (NLI) method is known by the simple algorithm. However, the performance of the inversion is strongly depended on parameters of the NLI algorithm. Major parameters in the algorithm are the initial size distribution, weight parameter, and the number of iteration. In the study, we show how values of initial parameters affect to the result of size distribution in the algorithm by the laser diffraction scattering method. Computer simulations and experimental method are carried out to observe the influence of the parameters in the algorithm. Scattering pattern is calculated by Mie scattering model in the range of 5.0×10−4 −2.5rad. Experimental results were measured mono-distribution polystyrene latex (50μm) and poly-distribution glass beads (3–30μm, and 10–100μm). The number of iteration is a most influence parameter in the NLI algorithm. If the number of iteration is too high for calculation, calculated result will lose the smoothness. We also introduced a new parameter C (combination of the sum of residual squares of scattering signals and sum of secondary differentiation of size distribution) to monitor the suitable stop criterion for the NLI method. The parameter C is a useful index for the poly dispersion sample to find the suitable stop criterion. [Copyright &y& Elsevier]

The present research aims to characterize the particle size distribution of sub micron particles suspended in a liquid. The particles milled are an organic poorly water soluble crystalline product. To characterize the size of these particles, different techniques have been tested: imaging techniques (SEM, CryoTEM), static light scattering techniques, dynamic light scattering techniques, centrifugation and flow field flow fractionation. The results indicate that the studied milled particles have a primary particle size close to 180nm and there is strong evidence of larger particles which are very likely aggregates. This is clearly seen from the Cryo TEM results. All the above mentioned techniques should in principle be able to measure samples of dispersion containing particles of ca 180 nm but several are disturbed by the presence of large aggregates. It is difficult to estimate the amount of aggregate present, but most of the time one is interested in what the primary particle size distribution is. It is clear that no single piece of equipment is capable of exactly determining the particle size distribution of our samples, but the static light scattering with low shear on mixing does give a good representation of what is seen with the image analysis by cryo TEM. [ABSTRACT FROM AUTHOR]

Presented are results of an inter-laboratory study (ILS) for measurements of the particle size distribution of fine powders in wet dispersion by laser diffraction. In this proficiency test 32 participants from four countries took part. They utilized 13 different devices from 7 manufacturers. Three commercial powders (glass spheres and two silicon carbide powders) showing a median diameter of about 30, 10 and 1 μm (volume distribution), respectively, were chosen for the procedure. A homogeneity study was carried out after the units had been separated and bottled. All participants received their test samples including a description of the standard operating procedures based on ISO 13320:2009 - to ensure that experiments were performed in a consistent manner. Results were calculated using the Mie Theory. The general means and the precision of the results were estimated in accordance with ISO 5725-2:2002. The evaluation showed excellent values of repeatability standard deviation. Values of 4 to 21 % of the reproducibility standard deviation of the results were found in the particle size range above 1 μm. Much larger deviation between the labs was detected in the case of smaller particles. Differences in the design of the analyzers were unambiguously identified as the main reason for the large deviations. [ABSTRACT FROM AUTHOR]

Morphology is important in industrial processes involving filamentous organisms because it affects the mixing and mass transfer and can be linked to productivity. Image analysis provides detailed information about the morphology but, in practice, it is often laborious including both collection of high quality images and image processing. Laser diffraction is rapid and fully automatic and provides a volume-weighted distribution of the particle sizes. However, it is based on a number of assumptions that do not always apply to samples. We have evaluated laser diffraction to measure cell clumps and pellets of Streptomyces coelicolor compare to image analysis. Samples, taken five times during fed-batch cultivation, were analyzed by image analysis and laser diffraction. The volume-weighted size distribution was calculated for each sample. Laser diffraction and image analysis yielded similar size distributions, i.e. unimodal or bimodal distributions. Both techniques produced similar estimations of the population means, whereas the estimates of the standard deviations were generally higher using laser diffraction compared to image analysis. Therefore, laser diffraction measurements are high quality and the technique may be useful when rapid measurements of filamentous cell clumps and pellets are required. [ABSTRACT FROM AUTHOR]

Abstract: In situ laser diffraction, scanning electron microscopy (SEM) imaging, and thermography have been used to investigate particle formation and particle size distribution of alkyl ketene dimer (AKD) produced by rapid expansion of supercritical solution (RESS). The investigated RESS process is based on an earlier reported method to prepare superhydrophobic coatings. Spray distance, pre-expansion temperature and pressure have been varied and the results from the methods have been compared. SEM images and light scattering data correlate well, and show that the mean particle size increased and the size distribution became significantly broader with increasing spray distance. Mean particle diameters of above 5μm were only observed for pre-expansion temperatures at 50°C or below. Furthermore, results show that by placing the surface to be coated within the cold expansion zone of carbon dioxide (CO2), i.e. in this study at 55mm or shorter for a pre-expansion temperature (T pe) and pressure (P pe) of 57°C and 180bar, respectively, will produce a surface evenly covered by 3-μm crystalline AKD flake-like particles. Obtained results also indicated, but did not prove, that agglomerates of AKD particles were carried to the surface by liquid CO2 droplets in the jet. [Copyright &y& Elsevier]

Abstract: Purpose: The purpose of this study was to assess the effectiveness of three commercial capsule-based dry powder passive inhalers [Rotahaler® (RH), Monodose Inhaler® (MI) and Handihaler® (HH)] in de-agglomerating salbutamol sulphate (SS) and micronized lactose (LH300) powders and their sensitivity to air flow rate changes and air flow resistance. Methods: Aerosolisation was assessed in real-time using a laser diffraction method: this approach was possible as only single-component formulations were tested. Volume percent of the aerosolised particles with diameter less than 5.4μm at air flow rates from 30 to 180lmin−1 was obtained with the RH, MI and HH and provided a parameter, relative de-agglomeration (RD), as a measure of de-agglomeration. The pressure drops across the device at various flow rates were obtained from a differential pressure meter. Results: The relationship between RD of SS and LH300 and air flow rate appeared substantially different between the devices. It was surprisingly found that in some cases RD dropped at the highest air flows: this indicates a device specific maxima in RD occurs, and this may in part be attributed to changes in capsule motion. It is proposed that this relationship between RD and pressure drop provides a patient focussed simple way to assess RD performance. This assessment indicated that MI was the most efficient relative de-agglomerator at lower pressure drops, while HH increases its effectiveness at higher pressure drops. Conclusion: The approach of measuring RD as a function of pressure drop revealed instructive variations in the aerosolisation performances of different devices. This new approach helps compare device performances with different powders, and hence improve optimisation and consistency of performance. [Copyright &y& Elsevier]

Formation of aggregates and particulates in biopharmaceutical formulation continues to be one of the major quality concerns in biotherapeutics development. The presence of large quantities of aggregates is believed to be one of the causes of unwanted immunogenic responses. Protein particulates can form in a wide range of sizes and shapes. Therefore, a comprehensive characterization of particulates in biologics formulation continues to be challenging. The quantity of small size aggregates ( e.g., dimer) in a stable biologics formulation is well controlled using precision analytical techniques ( e.g., high-performance liquid chromatography). Particulate in clinical and commercial formulations is monitored using visual inspection and subvisible particulate counting assays. While visual inspection (by human eye or automated systems) is intended to detect particulates (intrinsic and extrinsic) of ~100 μm or larger, the subvisible counting methods cover smaller size ranges down to 10 μm. It is well recognized that research of particulates in the submicron (<1 μm) and low-micron (1-10 μm) ranges may provide important clues to understand the mechanism of particulate formation. The recent years have seen a significant increase in the development of newer technologies for more comprehensive characterization of particulates. This is attributed to increased awareness in this field of research over the past 5 years, stimulated by scholarly articles, commentaries, and robust discussions in various forums. This article provides an overview of emerging detection technologies that provide complementary characterization data encompassing a wider size range of particulates. It also discusses their advantages and limitations in the context of applications in biotherapeutics development. [ABSTRACT FROM AUTHOR]

An important characteristic of liquid sprays is the statistical distribution of droplet sizes that they produce. Knowledge of the droplet size distribution is particularly important for pesticide applications because droplet size affects trajectory, probability of contact with the target pest, and the biological dose. This article describes an experimental study of the spray plume of a rotary-cage atomizer in a wind tunnel environment with an air speed typical of aerial application (60 to 70 m s-1). Comparative measurements of droplet velocity and diameter were made using phase Doppler interferometer (PDI) and laser diffraction (LD) instruments. The present study is unique because it reports full droplet velocity and size data over a range of streamwise distances from the atomizer. High droplet concentrations and strong flow recirculation in the near wake (x/D < 2) were found to have a significant effect on the LD measurements. At greater downwind distances (x/D > 8), droplet velocities were found to be more uniform, and droplet size measurements using LD and PDI instruments were found to be in close agreement. [ABSTRACT FROM AUTHOR]

Abstract: A precise, accurate and well documented method for the sizing and counting of microbubbles is essential for all aspects of quantitative microbubble-enhanced ultrasound imaging. The efficacy of (a) electro-impedance volumetric zone sensing (ES) also called a Coulter counter/multisizer; (b) optical microscopy (OM); and (c) laser diffraction (LD), for the sizing and counting of microbubbles was assessed. Microspheres with certified mean diameter and number concentration were used to assess sizing and counting reproducibility (precision) and reliability (accuracy) of ES, OM and LD. SonoVue™ was repeatedly (n = 3) sized and counted to validate ES, OM and LD sizing and counting efficacy. Statistical analyses of intra-method variability for the SonoVue™ mean diameter showed that the best microbubble sizing reproducibility was obtained using OM with a mean diameter sizing variability of 1.1%, compared with a variability of 4.3% for ES and 7.1% for LD. The best microbubble counting reproducibility was obtained using ES with a number concentration variability of 8.3%, compared with a variability of 22.4% for OM and 32% for LD. This study showed that no method is fully suited to both sizing and counting of microbubbles. [Copyright &y& Elsevier]

Abstract: Particles in the marine environment vary in size from sub-micron colloids to flocculated aggregates of the order of millimetres. The LISST-100 (laser in-situ scattering and transmissometer) range of instruments (Sequoia Scientific Inc.) determine the distribution of particle sizes in-situ using laser diffraction, but are limited to specific size ranges governed by the instrument configuration. Using numerical predictions of scattering and a novel observational system to combine digital holography and the LISST-100 type-c, here we examine the response of the LISST to particles larger than the intended size range of the instrument. For spheres greater than the type-c instrument limit of 500μm, both theory and observations indicate that the inversion of the recorded scattering into particle size distributions produces volume distributions that peak at varying sizes between 250 and 400μm. This is caused by the principal peaks in scattering moving off the inside of the ring detectors, leading to the remaining peaks being interpreted as the principal peaks. The aliasing of larger particles as a distribution of smaller particles is also applicable to the type-b configuration of the LISST, only occurring at the 250μm size limit instead of 500μm. When extending the Junge particle size distribution up to varying maximum sizes, numerical tests predict an increase in volume concentration of up to 45%. For power-law distributions with gradients less than that of a Junge distribution, the contamination from large particles becomes increasingly influential over the concentration and shape of the inverted size distribution. [Copyright &y& Elsevier]

According to the force-length relationship, cat soleus optimal sarcomere length should lie between 2.3-2.5µm. Rack and Westbury (1969) found optimal sarcomere length around 2.8- 3.0µm. The purpose of this study was to repeat their study to check for these discrepancies between the expected and the measured optimal length. The soleus muscle of both hindlimbs of three cats was supra-maximally stimulated. Isometric forces were measured for lengths ranging from -20 to +20mm relative to the optimal length. Mean sarcomere lengths were obtained by laser diffraction. Fibre length was obtained post-mortem by video analysis and in situ with sonomicrometry crystals. Sarcomere number was determined and in situ sarcomere lengths were calculated. The sarcomere force-length relationship showed an ascending and descending part with a plateau between 2.0-2.4µm. Peak forces were obtained at smaller average sarcomere lengths than reported by Rack and Westbury and closer to the optimal sarcomere length based on sliding filament considerations. [ABSTRACT FROM AUTHOR]

The comparison of particle size distributions measured by sedimentation methods and laser diffraction shows the underestimation of the fine (clay) fraction. This is attributed mainly to the shape of clay particles being different than spherical. The objective of this study was to demonstrate differences in the results of particle size distributions of soils determined with the method of laser diffraction using two different dispersion units of the Malvern Mastersizer 2000. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: The purpose of the current investigation is to understand the kinetics of de-agglomeration (k d ) of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30–180lmin−1) from three dry powder inhaler devices (DPIs), Rotahaler® (RH), Monodose Inhaler® (MI) and Handihaler® (HH). Results: Cumulative fine particle mass vs. time profiles were obtained from the powder concentration, emitted mass and volume percent <5.4μm, embedded in the particle size distributions of the aerosol at specific times. The rate of de-agglomeration (k d ), estimated from non-linear least squares modelling, increased with increasing air flow rates. The k d vs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k d was highest from RH and lowest from MI. Differences in k d between the devices were related to device mode of operation while the differences between the materials were due to the powder bed structure. Conclusion: This approach provided a methodology to measure the rate constant for cohesive powder de-agglomeration following aerosolisation from commercial devices and an initial understanding of the influence of device, air flow rate and material on these rate constants. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to understand the kinetics of emptying of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30–180Lmin−1) from three dry powder inhaler devices, Rotahaler® (RH), Monodose Inhaler® (MI) and Handihaler® (HH). Aerosol concentration vs. time profiles, determined through real-time laser diffraction particle sizing, demonstrated that the majority of the powder from RH was emitted within one second while a more prolonged aerosolisation was observed from MI and HH. Peak aerosol concentrations were achieved more rapidly from RH compared to MI for both SS and LH300. Calculated cumulative emitted mass (CCEM) vs. time profiles were obtained from the aerosol concentration vs. time profiles and the emitted mass and the rate of CCEM (k CCEM ), estimated from a modelling approach, increased with increasing air flow rates. The k CCEM vs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k CCEM was highest from RH and lowest from MI. Differences in k CCEM between the devices were related to capsule aperture size while the differences between the materials were due to the powder bed structure. This approach provided an understanding of the rate at which powder mass emptied from dry powder inhaler devices and was proposed to be a powerful development tool for the future powder inhalers. [Copyright &y& Elsevier]

Considerable amounts of particulate matter (PM), including total suspended particulates (TSP), particulates with equivalent aerodynamic diameter less than or equal to 10µm (PM10), and particulates with equivalent aerodynamic diameter less than or equal to 2.5 µm (PM2.5), are emitted from large beef cattle feedlots. Particle size distribution and concentrations of TSP, PM10, and PM2.5 at a commercial cattle feedlot in Kansas were measured over a two-year period. The feedlot had a capacity of 30,000 head with a total pen area of 50 ha and was equipped with a sprinkler system for dust control. Collocated low-volume samplers for TSP, PM10, and PM2.5 were used to measure concentrations of TSP, PM10 and PM2.5 at the upwind and downwind edges of the feedlot. A laser diffraction (LD) analyzer (Beckman Coulter LS 13 320) was utilized to determine the particle size distribution of dust samples collected by TSP samplers. A micro-orifice uniform deposit impactor (MOUDI) was also used to measure particle size distribution at the downwind edge of the feedlot. Considering the same effective size range, the LD analyzer and MOUDI did not differ significantly in mean geometric mean diameter (GMD) (11.6 vs. 13.0 µm) and in mean geometric standard deviation (2.3 vs. 2.3). Wind speed and period of sampling significantly affected the mean GMD of the particles. The PM10 and PM2.5 concentrations that were calculated from the LD method and TSP data were not significantly different from those measured by low-volume PM10 and PM2.5 samplers (122 vs. 131 µm-33 for PM10 and 26 vs. 35 µm-3 for PM2.5). Both PM10 and PM2.5 fractions decreased as pen surface water content increased, but the PM2.5 PM10 ratio showed little change as pen surface water content increased. [ABSTRACT FROM AUTHOR]

Abstract: A new method for the analysis of aggregate disintegration in water was tested using aeolian sediment samples. The response of aeolian sedimentary aggregates to wetting and mechanical energy has important implications for the immobilization of aeolian sediments by rainfall and their susceptibility to post-depositional erosion by water. Repeated laser diffraction analysis of a single sample circulating in deionized water provides a detailed view of the changes in particle size distribution as aggregates disintegrate. This methodology also allows experiments on the effects of water chemistry, exchangeable cation chemistry, and prewetting. Results presented here suggest that aggregates of widely varying stabilities can occur in a wide range of particle size classes; that is, aggregate stability may to some extent be independent of the hierarchy of aggregate sizes emphasized in earlier research. The methods described here are broadly applicable to a variety of soils and sediments, but experiments are needed to relate the results more specifically to aggregate behavior under field conditions. [Copyright &y& Elsevier]

Abstract: Monolayer films of hexagonal close-packed polystyrene (PS) spheres were formed at the air–water interface through a self-ordering process without using Langmuir trough. The contact angle of PS particles on the surface of water was determined by an interfacial swelling method. It was found that the concentration and the nature of surfactant had an obvious influence on the arrangement of PS particles. PS suspension containing Triton X 100 (TX 100) of an appropriate concentration self-assembled into a closely packed monolayer on the surface of water. Sodium dodecyl sulfonate, an anionic surfactant, had a relative weak influence on the arrangement of pre-dried PS particles, in contrast, had an obvious effect on newly synthesized PS particles. Quantitative ultraviolet–visible (UV–vis) absorption spectrometry indicated that about 3% of the added TX 100 was adsorbed on the PS particle surface. Laser diffraction patterns on the monolayer film were used to investigate the lattice orientation. Ultraviolet–visible–near infrared (UV–vis–NIR) spectra of monolayer films of different sized PS particles displayed that the method presented here was universal for preparation of two-dimensional (2D) colloidal crystals. [Copyright &y& Elsevier]