Determination Of Size Distribution Research Articles

Two deep learning methods in comparison to characterize droplet sizes in emulsification flow processes

AbstractFor reliable supervision in multiphase processes, the droplet size represents a critical quality attribute and needs to be monitored. A promising approach is the use of smart image flow sensors since optical measurement is the most commonly used technique for droplet size distribution determination. For this, two different AI-based object detection methods, Mask RCNN and YOLOv4, are compared regarding their accuracy and their applicability to an emulsification flow process. Iterative optimization steps, including data diversification and adaption of training parameters, enable the models to achieve robust detection performance across varying image qualities and compositions. YOLOv4 shows better detection performances and more accurate results which leads to a wider application window than Mask RCNN in determining droplet sizes in emulsification processes. The final droplet detection model YOLOv4 with Hough Circle (HC) for feature extraction determines reliable droplet sizes across diverse datasets of liquid-liquid flow systems (disperse phase content 1–15 vol.-%, droplet size range 5–150 μm). Evaluating the adjustment of Confidence Scores (CS) ensures statistical representation of even smaller droplets. The droplet detection performance of the final YOLOv4 model is compared with a manual image processing method to validate the model in general as well as its accuracy and reliability. Since YOLOv4 in combination with Hough Circle (HC) shows an accurate and robust detection and size determination, it is applicable for online monitoring and characterization of various liquid-liquid flow processes. Graphical abstract

Pseudo-Eulerian model formulation for the determination of breakage frequency and daughter size distribution: Single droplet breakup experiments in turbulent flow

The study of breakage of single oil droplet in a turbulent flow is experimentally performed by means of direct visualization using high-speed imaging. A comparison of two different approaches for estimation of the breakage frequency is presented using the same set of experimental data. The first approach, estimates the breakage frequency based on the estimation of the averaged breakage time and breakage probability calculation based on single oil breakage experiments. The second approach consists in combining and superposing the different measurements into one population of droplets, to investigate the evolution of the size distribution of droplets emulating a pseudo-Eulerian representation. Using this approach, the breakage frequency can be estimated by following the evolution of the number of droplets of a particular size. We found that the pseudo-Eulerian approach is more accurate for construction of closure model for the implementation of population balance equation.

Improved stability and antibacterial activity of cinnamaldehyde emulsion co-stabilized by cyclodextrin glycosyltransferase-catalyzed starch products and Tween 80

Cinnamaldehyde, a yellowish essential oil, has potential applications because of its antibacterial ability but is limited by its instability. In this study, we prepared the microencapsulated cinnamaldehyde emulsion co-stabilized by cyclodextrin glycosyltransferase-catalyzed (CGTase-catalyzed) starch products and Tween 80. Microscopic structure analysis by transmission electron microscopy, inverted fluorescence microscopy, and size distribution determination revealed that additional CGTase-catalyzed starch products could increase their homogeneity and decrease their particle sizes by 67.8%. Fluorescence spectra analysis showed the interactions between cinnamaldehyde and the wall materials with a decrease of 29.2% in fluorescence intensity. The cinnamaldehyde emulsion had good temperature, ionic strength, pH, and storage stability. Time-kill curve and inhibition zone showed increased antibacterial activity. Mechanism analysis by thermal gravimetric analysis and differential scanning calorimetry showed that the emulsion had a dual structure of gel network and cyclodextrin inclusion, contributing to its stability. This study could give new insights into the cinnamaldehyde emulsion and provide a good guidance for its application.

A Novel Frontier in the Geographic Distribution of the Japanese Sea Cucumber Apostichopus japonicus (Selenka, 1867) (Stichopodidae: Holothuroidea) in the World

The natural distribution of the Japanese sea cucumber (Apostichopus japonicus Selenka, 1867), a sea cucumber species, is characterized by the Northwest Pacific. Long-term monitoring studies from 2020 to 2024 document a significant deviation from the known natural distribution of A. japonicus and its ability to extensively colonize the Gulf of Izmit, the easternmost part of the Sea of Marmara. This record is also the first documentation of the species from the Mediterranean Sea. Population data extracted from 67 samples allowed the determination of size and weight distribution, length-weight relationship, and condition factor. The study delves into the implications for fisheries management by evaluating the species’ dispersion beyond its natural range and its adaptation, shedding light on potential threats from illegal hookah diving fisheries. While its presence offers potential economic benefits through fishing income, its emergence as an invasive species can pose critical ecological risks to the receiving ecosystem.

Pengaruh Jenis Cairan, Jenis Batang, dan Panjang Batang pada Penentuan Distribusi Ukuran Partikel Bubuk Kaca Menggunakan Buoyancy Weighing-Bar Method (BWM)

Particle size distribution is one of the important physical parameters in industry. A new method has been developed, the buoyancy weighing-bar method to determine the particle size distribution. This study examines the application of the buoyancy weighing-bar method for the determination of the particle size distribution of glass powder. Measurements were made by varying the type of liquid, the type of rod, and the size of the rod length. From this study, it was obtained that the best condition in determining the particle size distribution of glass powder is using aluminum rods with a length of 210 mm in 96% ethanol. The results of determining the particle size distribution of glass powder by using the buoyancy weighing-bar method at the best conditions are comparable to the results of determining the particle size distribution obtained using the settling balance method.

Molecular size distribution in pentavalent (A, C, Y, W, X) meningococcal polysaccharide conjugate vaccine by HPSEC-UV-MALS-RI method- a conceivable stability indicating parameter

Molecular size distribution (MSD) of polysaccharides serves as a key parameter that directly correlates to the immunogenicity of vaccine. MSD at meningococcal polysaccharide (A, C, Y and W) or conjugate bulk level is well established under detailed pharmacopeial and WHO guidelines. We report here, a newly developed method for determination of molecular size distribution of pentavalent Meningococcal conjugate vaccine comprising of A, C, Y, W and X (MenFive). Although serogroup specific molecular size could not be estimated here; lot to lot consistency monitoring, molecular aggregates distribution in final lot, are key takeaways of this method. Determination of MSD in pentavalent fill finished product was quite challenging. Various columns/detectors combination, buffers, physico-chemical conditions (temperature, 2–8 °C, 25 °C, 40 °C and 60 °C; flow rate, 0.3 mL to 0.8 mL), liquid/lyophilized formulations, were explored. Polymer-based packed columns were explored for estimation for MSD by aqueous size exclusion chromatography, using combinations of- Shodex OHPAK SB 807 HQ, Shodex OHPAK SB 806 HQ, G6000 PWXL, coupled with guard Shodex OHPAK SB-G-6B. MenFive showed heterogenous distribution of molecules ranging from 200 to 19000 kDa, indicating its complex nature. However, 1000–8000 kDa was dominant range, comprising of ≥ 50 % distribution of molecules, in both liquid as well as lyophilized formulations, with average molecular weight around 6000–6500 kDa. The molar mass distribution after slicing would provide an insight to the conformation of molecules through its presentation as HMW, LMW, aggregates and subsequently, the presence of dominant population of molecules of a particular molecular weight and its total contribution in the sample.

Humic Polyelectrolytes Facilitate Rapid Microwave Synthesis of Silver Nanoparticles Suitable for Wound-Healing Applications.

This article describes the one-pot microwave synthesis of silver nanoparticles (AgNPs) assisted with natural polyelectrolytes-humic substances (HS). The humic polyelectrolytes served both as chemical reductants for silver ions and as end-capping agents for AgNPs. Three commercially available sodium humates extracted from lignites and leonardite and one sodium fulvate isolated from natural brown water seeped through peat deposits were used in this study. The dynamics of the growth rate of AgNPs was characterised by UV-VIS spectroscopy by measuring the intensity of surface plasmon resonance at 420 nm. Transmission electron microscopy was used to characterise the size and morphology of AgNPs. Dynamic light scattering was used to determine size distributions of the synthesised AgNPs in the solutions. It was established that both conventional and microwave syntheses assisted with the coal humates produced small-size AgNPs in the range from 4 to 14 nm, with the maximum share of particles with sizes of (6 ± 2) nm by TEM estimates. The peat fulvate yielded much larger NPs with sizes from 10 to 50 nm by TEM estimates. DLS measurements revealed multimodal distributions of AgNPs stabilised with HS, which included both single NPs with the sizes from 5 to 15 nm, as well as their dominating aggregates with sizes from 20 to 200 nm and a smaller portion of extra-large aggregates up to 1000 nm. The given aggregates were loosely bound by humic polyelectrolyte, which prevented the coalescence of AgNPs into larger particles, as can be seen in the TEM images. The significant acceleration in the reaction time-a factor of 60 to 70-was achieved with the use of MW irradiation: from 240 min down to 210-240 s. The coal humate stabilised AgNPs showed antimicrobial properties in relation to S. aureus. A conclusion was made regarding the substantial advantages of microwave synthesis in the context of time and scaling up for the large-scale production of AgNP-HS preparations with antimicrobial properties suitable for external wound-healing applications.

Determination of Particle Size Distribution: Comparison of Standard Hydrometer Method and Laser Diffraction Analysis for Use in Forestry

Laser diffraction analysis is an alternative to standard sedimentation methods designed to determine particle size distribution. In this article, five samples from the forested part of the floodplain of the Svitava River in the Czech Republic were analyzed. Laser diffraction analysis and sedimentation hydrometer method were performed for each sample. The samples were divided according to soil classification into two groups depending on their classification–group A and group B. The results of laser diffraction analysis and hydrometer method were compared. Correlation relationships between both methods were established, and values were recalculated from laser diffraction analysis to the hydrometer method according to correlation equations. The article is a part of the methodology under preparation, which will include the most common soil types in the Czech Republic. This methodology focuses on the use of laser diffraction for the establishment of structures in forest environments using the regional specific standards for particle size distribution determination.

Investigation of olfactory perception by a putative adsorption process of sotolone and abhexone on human olfactory receptor OR8D1: Statistical physics modeling and molecular docking

In the present paper, a double layer advanced model was used to investigate the adsorption process putatively involved in the olfactory perception of sotolone and abhexone molecules on the human olfactory receptor OR8D1. The number of adsorbed molecules or the fraction of adsorbed molecule per site, n, informed that the two odorants molecules are docked on OR8D1 binding sites with mixed parallel and nonparallel anchorages. Furthermore, the estimated molar adsorption energy (−ΔE1 and −ΔE2) were inferior to 40 kJ/mol for the two adsorption systems, which confirmed the physical nature and the exothermic character of the adsorption process. In addition, stereographic characterizations of the receptor sites surface were carried out through the determination of the receptor site size distribution (RSDs) via Kelvin equation, which spread out from 0.05 to 1.5 nm. The adsorption energy distributions (AEDs) via Polayni equation show an adsorption band spectrum localized between 17 kJ/mol and 22.5 kJ/mol for sotolone and abhexone molecules respectively. A molecular docking calculation was performed. The results indicate that the binding affinities are belonging to the spectrum of the energy band of the molecules sotolone and abhexone, with values 19.66 kJ/mol and 19.24 kJ/mol.

DETERMINING ROCK FRAGMENT SIZE DISTRIBUTION USING A CONVOLUTIONAL NEURAL NETWORK

Fast and relatively accurate determination of the fragment size distribution of a muck-pile is still a challenge in mining operations and the existing measurement methods are inefficient. In this research, a new algorithm to determine fragment size distribution due to blasting was presented, using the image processing technique. In the newly proposed approach, delineating of the fragmented rock particles, as the main core of processing, was carried out, using a convolutional neural network. Two networks were defined and trained by 150 laboratory and 150 field data images. Also, 30 laboratory and 30 field data images were applied to carry out the validation visually, and by using F1-scores. For the two laboratory and field networks and results obtained by Split-Desktop software automatic edge detection on the same images, the F1-scores are equal to (0.98, 0.74) and (0.99, 0.85) respectively. Also, for determination of fragment size distribution by laboratory data network and Split-Desktop software automatic edge detection on the same images, the Root Mean Square Error (RMSE) for F30 and F80 are equal to (0.36, 1.20) and (0.31, 1.24) respectively. These indicate better performance of the proposed approach for both rock edge detection and fragment size distribution over Split-Desktop software automatic edge detection.

Enzymatic hydrolysis of oat core flour improves physiochemical and sensory behaviors for oat milk

The aim of this study was to develop a novel plant-based milk using oat core flour (OCF) as the raw material. OCF was firstly treated with deep liquefaction and saccharification. After that, multienzyme treatments, including protease, lipase, and cellulase hydrolyzations, were optimized and applied. The physicochemical properties of the oat milk were characterized. Particle size distribution and zeta potential determinations showed that neutral protease and lipase could effectively prevent the phase separation of oat milk. The highest absolute zeta potential value and narrower particle distribution were obtained at pH 7. Microstructure analysis showed that neutral protease treatment prevented protein aggregations, whereas the cellulase treatment destroyed the network structures formed by the fibers. Multienzyme treatments decreased the centrifugal sedimentation rate (SR) of OCF and increased the water absorption index (WSI) and the denaturation temperature. Furthermore, multienzyme treatments improved the sensory acceptance of color and apparent viscosity. Above all, this research was of specific significance to the development, application, and industrialization of OCF.

Mechanism of Potassium Release from Feldspar by Mechanical Activation in Presence of Additives at Ordinary Temperatures.

To improve the potassium availability of feldspar at ordinary temperatures, the mechanical grinding and addition of sodium hydroxide/salts were employed to study the effects of mechanical activation and strong alkali addition on particle characteristics, water-soluble potassium, and the available potassium of feldspar. A laser particle size analyzer was utilized for the direct determination of particle size distribution (PSD) using ground samples. The Brunauer-Emmett-Teller (BET) method was employed for specific surface areas. X-ray diffraction (XRD) was employed for structural characterization, scanning electron microscopy (SEM) for morphology exploration, and energy dispersive spectroscopy (EDS) to determine the chemical composition of potassium feldspar powder. The results revealed that the mechanical activation of potassium feldspar could reduce the particle size and produce agglomerated nanoparticles in the later period. The addition of NaOH and sodium salt did not cause agglomeration, and NaOH dissolved the nanoparticles. The water-soluble potassium content of feldspar in each treatment increased during mechanical grinding, from 21.64 mg kg-1 to 1495.81 mg·kg-1, by adding NaOH 5% weight of potassium feldspar powder and to 3044.08 mg·kg-1 by adding NaOH 10% weight with effects different from those of mechanical shaking. By comparison, only 162.93 mg·kg-1 water-soluble potassium was obtained by adding NaOH 5% weight. The dissolved potassium in the former case was significantly higher than in the latter, and the addition of NaOH and sodium salts significantly enhanced the water-soluble potassium contents due to ion exchange. Furthermore, the addition of sodium hydroxide improved the water-soluble potassium due to its mechanochemical action on potassium feldspar. The mechanical energy changed the crystal structure of potassium feldspar, explaining the increase in available potassium. The addition of sodium salts did not promote change in the feldspar's structure, thereby did not raise the available potassium content. The reason for this was related to the mechanochemical action on sodium hydroxide and feldspar, which could promote the dissolution of fine particles, thereby incrementing the available potassium.

High-throughput determination of grain size distributions by EBSD with low-discrepancy sampling.

Because microstructure plays an important role in the mechanical properties of structural materials, developing the capability to quantify microstructures rapidly is important to enabling high-throughput screening of structural materials. Electron backscatter diffraction (EBSD) is a common method for studying microstructures and extracting information such as grain size distributions (GSDs), but is not particularly fast and thus could be a bottleneck in high-throughput systems. One approach to accelerating EBSD is to reduce the number of points that must be scanned. In this work, we describe an iterative method for reducing the number of scan points needed to measure GSDs using incremental low-discrepancy sampling, including on-the-fly grain size calculations and a convergence test for the resulting GSD based on the Kolmogorov-Smirnov test. We demonstrate this method on five real EBSD maps collected from magnesium AZ31B specimens and compare the effectiveness of sampling according to two different low discrepancy sequences, the Sobol and R2 sequences, and random sampling. We find that R2 sampling is able to produce GSDs that are statistically very similar to the GSDs of the full density grids using, on average, only 52% of the total scan points. For EBSD maps that contained monodisperse GSDs and over 1000 grains, R2 sampling only required an average of 39% of the total EBSDpoints.

Assessment of waste hop (Humulus Lupulus) stems as a biosorbent for the removal of malachite green, methylene blue, and crystal violet from aqueous solution in batch and fixed-bed column systems: Biosorption process and mechanism

The discharge of industrial textile waters into water bodies leads to the accumulation of pollutants which are a serious threat to humans and the environment. The development of an efficient adsorbent for the removal of toxic organic dyes from water is of crucial importance. For that reason, this work aimed to elaborate on the potential application of a biosorbent obtained from waste Humulus lupulus stems (Hlup-BA) for the elimination of malachite green, methylene blue, and crystal violet from aqueous solution in batch and fixed-bed column systems. The Hlup-BA was characterized using chemical composition analysis, by determination of particle size distribution, the point of zero charge (pHpzc), SEM, BET, EDS, XRD, and FTIR. Comprehensive analysis of Hlup-BA adsorption efficiency in a batch study showed that at the optimal conditions (e.g. contact time, 120 min; biosorbent dose, 2 g/L; dye concentration, 100 g/L; pH, 8 and temperature, 298 K), even 98.4 %, 98.8 %, and 98.5 % of MG, MB, and CV were removed, respectively. The results showed that the biosorption process followed pseudo-second-order kinetics. The equilibrium data were modeled using Langmuir, Freundlich, Sips, and Dubinnin-Radushkevich biosorption isotherms. High values of Hlup-BA biosorption capacities obtained from Langmuir isotherm were 398.9 mg g−1, 209.8 mg g−1, and 133.2 mg g−1 for MG, MB, and CV, thus proving Hlup-BA as an excellent biosorbent for removal of the tested dyes. The thermodynamic study indicated that the biosorption of these three dyes on Hlup-BA from aqueous solution is an endothermic, spontaneous, and thermodynamically stable process. The proposed mechanism of the biosorption process covers π-π interactions, electrostatic interactions, and hydrogen bonding. Furthermore, the data obtained by modeling in the fixed-bed column were also successfully correlated with the Thomas, Bohart-Adams, and Yoon–Nelson models. The very good fit of the results obtained in this way will greatly contribute to optimizing the pilot-scale operations for future wastewater treatment. Consequently, Hlup-BA can be an effective, cheap, and environmentally friendly biosorbent to eliminate methylene blue, malachite green, and crystal violet dyes from the aqueous solution in batch and column systems.

The Effect of Vacuum Forming on the Quality of Refractory Materials

Various designs of furnaces for melting alloys are used in the foundry industry. Regardless of their design, they have one common detail, which is the lining of their interiors with refractory materials. This component in the design of a metal-melting furnace has a very important task—to protect the rest of the furnace assemblies from thermal and mechanical damage. Continuous technical progress and the quality requirements of casting production produce increasingly higher demands for refractory materials in connection with their development as well. The article presents the results of an innovative method of vibratory compaction of refractory material (high-alumina aluminosilicate) using reduced pressure. The analysis presents a comparative study of two methods used for forming refractory materials, i.e., the application of the mentioned innovative method and the classical (standard) method of compaction by vibration only. The effects of the introduced modification in the manufacture of ceramic shapes were evaluated by means of the material’s resistance to thermal shock, linear expansion, and dimensional change due to firing, apparent density, open porosity, and apparent specific gravity, determination of total pore volume and pore size distribution by mercury porosimetry, and slag resistance. The tests performed indicate that the procedure of lowering the pressure during the vibratory compaction of the refractory material creates a more homogeneous structure with a smaller number and size of pores. This makes it possible to improve most of the parameters that determine the quality of the refractories used for the linings of the foundry furnace.

Microencapsulation of Phenolic Compounds Extracted from Okra (Abelmoschus esculentus L.) Leaves, Fruits and Seeds

Several plants rich in phenolic compounds have many uses in the food and pharmaceutical fields. However, after extraction, these active biomolecules are susceptible to degradation. Microencapsulation is a possible solution to prevent this rapid degradation. In this study, phenolic compounds from the okra Abelmoschus esculentus L’s leaves, fruits and seeds were extracted using microwave-assisted extraction and then microencapsulated via the spray drying technique using maltodextrin combined with pectin (in a ratio of 10:1) as an encapsulation material. The total phenolic content, DPPH scavenging and antimicrobial activities of okra extracts and encapsulated samples were evaluated to verify the encapsulation efficiency. Particle size distribution determination and scanning electron microscopy of the microcapsules were also carried-out. The ethanolic leaf extract showed higher significant levels of total phenolic compounds (162.46 ± 4.48 mg GAE/g DW), and anti-oxidant (75.65%) and antibacterial activities compared to those of other aqueous and ethanolic extracts from fruits and seeds. Furthermore, the spray-dried ethanolic leaf extract had the highest total phenolic content. However, the encapsulated ethanolic fruit extract had the highest percentage of DPPH scavenging activity (30.36% ± 1.49). In addition, antibacterial activity measurements showed that the addition of ethanolic and aqueous seed microcapsules provided a significant zone of inhibition against the bacterium Brochotrix thermosphacta (38 mm and 30 mm, respectively). Okra aqueous leaf microcapsules showed the smallest Sauter mean diameter values (7.98 ± 0.12 µm). These data are applicable for expanding the use of okra leaves, fruits and seeds as food additives and/or preservatives in the food industry.

Evaluation of Millability and Recyclability of Asphalt with Paving Interlayers

Abstract Reclaimed asphalt pavement (RAP) has been widely incorporated into roadway base and surface courses, as they provide economic and environmental benefits that lead to sustainable construction practices. However, because of the increasing use of paving interlayers (e.g., geotextiles, geogrids, and geocomposites) during roadway rehabilitation, the likelihood of milling projects involving asphalt layers with paving interlayers (referred to as GRAP) has significantly increased. Consequently, the assessment of potential GRAP reuse in geotechnical and pavement applications becomes essential. This research study aims at evaluating the millability and recyclability of asphalt layers with paving interlayers. Specifically, sections with and without paving interlayers were first milled to evaluate the millability of asphalt layers with paving interlayers. Subsequently, the recyclability of GRAP for the base and surface course of pavements was assessed by quantifying the geotechnical characteristics of millings collected from asphalt layers with paving interlayers, referred herein as geosynthetic RAP or GRAP, and those without paving interlayers (RAP). The evaluation of RAP and GRAP materials for road base suitability included blending them with virgin aggregates and investigating these blends via determination of particle size distribution, binder content, compaction characteristics, abrasion resistance, hydraulic conductivity, and resilient modulus. The evaluation of RAP and GRAP materials for surface course suitability involved preparing asphalt mixtures that incorporated RAP and GRAP and quantifying their particle size distribution, indirect tensile strength, and moisture susceptibility. Comparison of the results obtained from five different base course blends and five different asphalt mixtures demonstrated that the base course blends and asphalt mixtures with GRAP exhibited properties similar to those with RAP. Also, the results of this investigation indicate that asphalt mixtures (surface course) and granular base courses can incorporate up to 30 % and 50 % GRAP, respectively, thus leading to sustainable roadway construction practices.

Experimental and simulation study on the estimation of surface relaxivity of clay minerals

Nuclear Magnetic Resonance (NMR) is an important tool for the evaluation of pore structure and petrophysical properties of reservoir rocks. Pore Surface relaxivity (ρ2), which controls the relaxation decay due to the interaction between the spins and the pore surface, is an important parameter that impacts the interpretation of NMR for petrophysical properties. Sandstone rocks have complex minerology and consist of different clay minerals. Earlier efforts have reported the surface relaxivity of different rock types such as sandstone or carbonate, but less attention was given to the estimation of individual clay minerals surface relaxivity. The surface complexity and variable mineralogy (especially paramagnetic and ferromagnetic minerals) of clays can both impact the surface relaxivity and relaxation times in clays and porous media containing clays. This study, using for the first time both simulation and experimental approaches, aims to systematically investigate the surface relaxivity of clays characterized by variable mineralogy and iron content. A glass beads sample (iron free) and 5 different pure clay minerals samples (ranked by increasing iron content: Kaolinite, Smectite, Illite, Chlorite, and Nontronite) were prepared with similar average grain sizes (500 μm). The determination of surface relaxivity requires prior measurement of pore surface-to-volume ratio (S/V) using an independent method in addition to obtaining T2 relaxation time. Two methods, among the most widely used, were used here for S/V determination including BET N2 gas adsorption and 3D micro CT imaging. The 3D images were also used to conduct NMR simulations to reproduce the experimental data. The estimated surface relaxivity values from both methods were compared and correlated to the iron content of the different clays. The surface relaxivity values obtained based on BET-derived S/V showed reasonable values (29–343 μm/s) that have a strong positive relationship with iron content of the clays. The documented equation relating surface relaxivity and iron content can be potentially utilized to predict surface relaxivity based on the compositional analysis of clays. On the other hand, digital images did not capture the surface complexity of clays thus significantly underestimated S/V which consequently resulted in overestimated surface relaxivity (898–11000 μm/s) that were physically non-feasible. Supporting the same argument, the simulated T2 relaxation distribution showed significant mismatch with the experimental data for the clay samples while an excellent match was observed for the glass beads sample. This can be attributed to the smooth surface of the glass beads, unlike the complex clays. The reported surface relaxivity values (based on BET-derived S/V) for the individual clay minerals can be used to perform NMR simulation and interpretation studies conducted on sandstone or shale formations. Careful attention should be given when performing NMR simulation on micro-CT digital images of samples containing clay due to the inadequacy of such images in capturing the complex surface and microporous nature of clays. The outcomes from this study can improve the interpretation of NMR T2 data and the determination of NMR-derived pore size distribution and petrophysical properties. The reported surface relaxivity values for clay can also inform the NMR simulation.

Characterization of tire and road wear particles in urban river samples

Tire and road wear particles (TRWP) consist of tread rubber elastomers with pavement encrustations generated from tire-road friction. Our previous work utilized density separation and chemical mapping to characterize chemical and physical properties of individual TRWP. The current research extends the use of chemical mapping methods to urban river samples including sediment from the Seine River (France). TRWP were identified using a weight of evidence framework including density separation, optical imaging, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) mapping, and Fourier-transform infrared (FTIR) spectroscopy. River sediment collected immediately downstream of the Rouen urban area (with an average TRWP concentration of 930 mg TRWP/kg sediment; n = 3) subsequently density separated demonstrated an average TRWP size of 133 µm by number and 171 µm by volume. Sediment from a second location (190 mg TRWP/kg sediment; n = 1) was density separated and showed an overlap in features of tire tread and bitumen/asphalt in the FTIR signatures (operationally defined as weathered bitumen/TRWP). Average particle size for weathered bitumen/TRWP were 250 µm and 981 µm by number and volume, respectively. Pulverization pre-treatment of the second location sediment sample reduced larger particle agglomerates to an average weathered bitumen/TRWP particle size of 97 µm and 116 µm by number and volume, respectively. A quantitative TRWP or bitumen/TRWP size distribution in filtered suspended river solids (3300 mg TRWP/kg suspended solid) could not be determined due to lack of TRWP enrichment in pre- or post-density separation steps; however, average particle size for all collected river particles were 27 µm and 160 µm by number and volume, respectively. Additionally, TRWP were not identified in a river biota sample (bivalves) with or without chemical digestion and future research was discussed. Taken together, our single particle analysis methodologies were useful for the determination of particle size distribution (including bitumen and TRWP) in urban river sediment samples. These results are expected to help advance the methods for identification and characterization of TRWP and potentially other microplastics in various environmental matrices.

Soil texture analysis by laser diffraction and sedimentation and sieving–method and instrument comparison with a focus on Nordic and Baltic forest soils

PurposeLaser diffraction (LD) for determination of particle size distribution (PSD) of the fine earth fraction appeared in the 1990s, partly substituting the Sieving and Sedimentation Method (SSM). Whereas previous comparison between the two methods predominantly encompasses agricultural soils, less attention has been given to forest soils, including pre-treatment requirements related to their highly variable contents of carbon and Alox+ Feox. In this small collaborative learning study we compared (1) national SSM results with one type/protocol of LD analysis (Coulter), (2) LD measurements performed on three different LD instruments / laboratories, and (3) the replication error for LD Coulter analysis of predominantly sandy and loamy forest soils.MethodsWe used forest soil samples from Denmark, Norway and Lithuania and their respective national SSM protocols / results. LD analyses were performed on Malvern Mastersizer 2000, Sympatec HELOS version 1999, and Coulter LS230, located at University of Copenhagen, Aarhus University and Helsinki University, respectively. The protocols differed between laboratories, including the use of external ultrasonication prior to LD analysis.ResultsThe clay and silt fractions content (<20 μm) from the LD analysis were not comparable with SSM results, with differences ranging from −0.5 to 22.3 percentage points (pp) for clay. Preliminary results from loamy samples with spodic material suggested inconsistent effects of external ultrasonication to disperse aggregates. The comparison between the three LD instruments showed a range in the clay and silt fractions content of 1.9–5.3 and 6.2–8.1 pp, respectively. Differences may be related to the instruments, protocols, and content of a given particle size fraction. The replication error of the Coulter LD protocol was found to be <3 pp in sandy soils, but up to 10 pp in loamy soils.ConclusionDifferences in the clay fraction results partly affected the classification of soil types. The fast replication of the LD analysis enables more quality control of results. The pedological evaluation of non-silicate constituents and optional pre-treatment steps (e.g., soil organic matter or sesquioxides) remains the same for LD and SSM. For comparison of results, detailed descriptions of the analytical protocol including pre-treatments are needed irrespective of instrument and theoretical approach.