Smaller Mean Particle Size Research Articles

Water-soluble single source precursors for homo- and hetero-metallic nanoparticle catalysts supported on nanocarbons

Homo- and hetero-metallic catalysts were prepared in water from a single metal source and in a single step, and were tested in cinnamaldehyde selective hydrogenation. Two new water-soluble clusters, namely [Ru5C(CO)14(TPPTS)1] and [Ru5PtC(CO)15(TPPTS)1], were synthesized by the addition of phosphine TPPTS to starting homo- and hetero-metallic clusters soluble in organic solvents. They were then impregnated onto nanocarbons (CNF and CNT) in water at different pH values. Cluster deposition occurred via two adsorption modes and was the most successful when attractive electrostatic interactions took place. Thermal activation of these samples led to heterogeneous catalysts with a small mean particle size between 2 and 4nm. The home-made catalysts showed increased conversions and selectivities (up to 73%) towards the thermodynamically unfavored product cinnamyl alcohol compared to a commercial catalyst. The selectivity was in general higher with CNF support, with less oxygenated function and with bigger particles. The selectivity increased slightly with the addition of platinum to ruthenium but the activity was enhanced tremendously (up to 57% at t=30min).

Cinnamon oil nanoemulsions by spontaneous emulsification: Formulation, characterization and antimicrobial activity

The goal of this study was to formulate stable cinnamon oil nanoemulsions (NEs) exhibiting high antimicrobial activity by using the low-energy approach: spontaneous emulsification (SE) and compare it with two high-energy methods. To prepare the nanoemulsions by SE, oil phase containing cinnamon oil (CO) and carrier oil (coconut oil (CNO)) at different ratios (2:8–10:0) and surfactant (Tween 80) at 10% (w/w) was titrated into an aqueous phase (distilled water). For antimicrobial activity, agar disc diffusion method with E. coli as the model microorganism was used. NEs were characterized by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Both DLS and TEM gave parallel results and mean particle size were found as ∼ 100 nm for 6:4 (CO: CNO) oil phase composition. These NEs also showed high physical stability during one-month storage. NEs were also prepared by using two high-energy homogenization methods: microfluidization and ultrasonication. Ultrasonication and SE showed similar trends for mean particle size and microbial activity. Microfluidization resulted in the smallest mean particle size (p < 0.05) and antimicrobial activity was not effected from cinnamon oil concentration (p > 0.05).

Effect of the operating conditions on the colloidal and microemulsion synthesis of Pt in aqueous phase

The syntheses of platinum nanoparticles (Pt NPs) using colloidal and microemulsion methods and different reducing agents (methanol, NaBH4, and N2H4) have been compared systematically. The colloidal synthesis was based on polyvinylpyrrolidone (PVP) as capping agent and water and methanol-water mixtures as reaction media. The microemulsion syntheses were carried out using the water-in-oil (w/o) system formed by dioctyl sulfosuccinate sodium salt (AOT), n-heptane and water. The influence of PVP/Pt, reducing agent/Pt and water/AOT molar ratios was studied. The Pt NPs prepared were characterized by transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Both colloidal and microemulsion syntheses resulted in globular shaped NPs consisting mainly of a single crystal domain with fcc structure. Colloidal synthesis with methanol and NaBH4, yielded very stable NPs suspensions with small mean particle size (3–6nm) and distributions extending from 2 to 10nm. Narrower size distributions were obtained with NaBH4, whereas the use of N2H4 led to oversized particles. The most important synthesis variable was the PVP/Pt ratio. In the case of the microemulsion method, a broader range of NPs mean size was obtained (1–7nm). A better tailoring of the properties of the NPs was achieved varying the type of reducing agent, the reducing agent/Pt ratio and water/AOT ratio. The conditions for the synthesis of NPs suspensions with well differentiated mean size and distribution were identified.

Preparation and characterization of modified bentonite nano composites for phosphorus removal

Due to the restrictions of phosphorus uptake in commonly applied treatment systems such as biological treatment and precipitation, it has been focused to find improved removal technologies. The application of natural nanomaterials as adsorbents is favorable due to high adsorption capacity, low environmental impact and reasonable cost. Specially modified nanoclay presents an efficient and cheap alternative with good recovery abilities. However, the material has to be characterized in detail to understand its behavior. For the characterization, modified bentonite (BNT) was produced through exchanging the cations naturally bound to the bentonite surface with metal polycations. In this study, solutions containing hydroxy-polycations of aluminum (Al-BNT), iron (Fe-BNT), and a combination of aluminum and iron (Al-Fe-BNT) were used to prepare three samples of BNT for phosphorus adsorption. To obtain BNT in an accurate surface – volume ratio, it has to be grinded and sieved. To gain information on the influence of grinding on particle size of modified BNT, the samples were characterized through X-ray fluorescence (XRF), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). A clear determnation of particle size using SEM was difficult due to agglomeration of samples as a result of milling process. The need of ultrasonication or another separation method increases the production effort of nanosized modified BNT. As due to the improved surface - volume ratio, BNT with smaller mean particle size is expected to perform better, leading to a higher adsorption capacity and adsorption rate and therefore, this additional effort might pay off.

Podophyllotoxin-Loaded Nanostructured Lipid Carriers for Skin Targeting: In Vitro and In Vivo Studies.

Nanostructured lipid carriers (NLC) exhibit high skin targeting efficiency and good safety. They are promising vehicles for topical drug delivery. This study aims to increase the skin distribution of podophyllotoxin (POD) by incorporating it into NLCs. Two kinds of POD-loaded NLCs (POD-NLCs)—POD-NLCformulation 1 and POD-NLCformulation 2—were prepared and characterized. Their skin targeting efficiencies were compared by conducting in vitro and in vivo experiments. Obviously smaller mean particle size was observed for POD-NLCformulation 1 (106 nm) than POD-NLCformulation 2 (219 nm), whereas relatively low POD loadings (less than 0.5%) were observed for both POD-NLCformulation 1 (0.33%) and POD-NLCformulation 2 (0.49%). Significantly higher in vitro and in vivo rat skin deposit amounts of POD (p ˂ 0.01) were detected after the topical application of POD-NLCformulation 1 compared to POD-NLCformulation 2. To visualize the skin distribution behavior of hydrophobic active pharmaceutical ingredients (APIs) when NLCs were used as carriers, POD was replaced with Nile red (NR—a hydrophobic fluorescent probe), and the distribution behavior of NR-NLCformulation 1 and NR-NLCformulation 2 in rat skin in vivo was observed using confocal laser scanning microscopy (CLSM). Higher fluorescent intensity was observed in rat skin after the topical application of NR-NLCformulation 1 than NR-NLCformulation 2, suggesting that higher skin targeting efficiency might be obtained when NLCs with smaller mean particle size were used as carriers for hydrophobic APIs. This result was in accordance with those of skin distribution evaluation experiments of POD-NLCs. Skin irritation property of POD-NLCformulation 1 was investigated and no irritation was observed in intact or damaged rabbit skin, suggesting it is safe for topical use. Our results validated the safety of NLCs when applied topically. More importantly, mean particle size might be an important parameter for formulation optimization when NLCs are used as carriers for hydrophobic APIs for topical application, considering that their loading is relatively low.

Improvement of the emulsifying and oxidative stability of myofibrillar protein prepared oil-in-water emulsions by addition of zein hydrolysates

Abstract This study investigated the effects of zein hydrolysate (ZH) on the improvement of the emulsifying and oxidative stability of oil-in-water (O/W) emulsions prepared by myofibrillar protein (MP). The emulsifying activity index (EAI) and emulsion stability index (ESI) increased with the increase of ZH concentrations. Emulsions with 5 mg/mL ZH had the highest ESI and ζ-potential, the smallest mean particle size, and the lowest creaming index (p

Improved Solubility and Dissolution Release Profile of Lurasidone by Solid Self-Nanoemulsifying Drug Delivery System

The purpose of the study was to investigate self-nanoemulsifying drug delivery system (SNEDDS) as potential delivery system for poorly water soluble drug Lurasidone (LUR). SNEDDS was formulated using oil (Anise oil) surfactant (Tween® 80), and co-surfactant (Polyethyleneglycol-600). Z-average size, PDI and in-vitro drug release were considered to screen and optimize the composition of liquid-SNEDDS. Following emulsification, the optimized formulation was selected to have the smallest mean particle size and highest absolute zeta potential, which would yield stable emulsion. Scanning electron microscopy, X-ray powder diffraction studies confirmed that there was no crystalline drug in Solid-SNEDDS. Fourier transform infrared (FTIR) spectroscopy study revealed that there was no measurable chemical interaction of drug with the carrier. There was no significance difference in zeta average, zeta potential, and release profile of developed formulation before and after stability study. Both Liquid-SNEDDS and solid-SNEDDS showed improved in-vitro drug release than the pure drug. This paper provides an overview of the SNEDDS of LUR as a promising alternative to improve solubility and dissolution release profile. The results suggested that the SNEDDS could be used as an effective oral dosage form to improve the oral delivery of poorly water soluble drug LUR.

Plasma-enhanced low-temperature solid-state synthesis of spinel LiMn2O4 with superior performance for lithium-ion batteries

In this work, for the first time, we develop a plasma-enhanced low-temperature solid-state strategy to prepare LiMn2O4 with low energy consumption and superior performance for Li-ion batteries. The as-prepared LiMn2O4 shows a narrow particle size distribution in the range of 400–450 nm and smaller mean particle size.

Efficacy and toxicity evaluation of new amphotericin B micelle systems for brain fungal infections

The aim of this work is to study the micelle systems of amphotericin B (AmB) and surfactant sodium deoxycholate (NaDC) as possible formulations to treat brain fungal infections. Fungizone® and Ambisome® were used as AmB references. The particle size, aggregation state, toxicity and efficacy of AmB:NaDC micelles were studied with increasing proportions of NaDC. Differences in the size and aggregation state of the reference formulations and micellar NaDC formulations might explain the differences in their distribution and therefore in their toxicity and efficacy. AmB:NaDC 1:0.8 and 1:1.5 nano-sized micelle systems showed a poly-aggregated form of AmB and small mean particle size (450–750nm). The AmB:NaDC 1:0.8 and AmB:NaDC 1:1.5 micelle systems studied showed an 8-fold lower toxicity than Fungizone®. Efficacy was examined in a murine candidiasis model by determining the survival rate and tissue burden reduction in kidneys and brain. The AmB:NaDC 1:1.5 micellar system at 5mg/kg of AmB and the highest amount of NaDC (7.5mg/kg) presented a good survival rate, and induced a major clearance of brain infection. The new AmB:NaDC 1:1.5 nano-sized micelle system is a promising formulation with a good efficacy/toxicity ratio, which can be attributed to its particle size, AmB aggregation state and NaDC content.

Size Reduction of Hydrophobically Modified Starch on Beads Mill: Effect of Dispersing Medium and Milling Time

The primary interest to this study was to investigate the effect of milling parameters on the size of hydrophobically modified starch particles, aiming to produce small, uniformly sized modified starch microspheres. Octie, a commercial product originated from cornstarch modified using Octenyl Succinate Anhydride (OSA), was dispersed (3 wt%) using different media (water or ethanol) and subsequently wet-milled using a beads mill with zirconium be ads at ar otation of 6,000 rpm up to 30 min. It was found that milling Octie in water dispersion for 3 min resulted in the smallest mean particle size (2.04 ± 0.91 m), compared to unmilled modified starch granules (15.2 ± 6.0 m). Granular size and morphology changed considerably with further milling. For instance, very dense clusters with variable particle sizes (20.6 ± 10.0 m) were obtained after 30 min milling. As depicted by Scanning Electronic Microscopy, a large number of particles were apparently flattened during the milling process rather than broken, forming aggregates. Ultimately, within the range of experimental conditions tested, production of sub-micron modified starch particles was not possible.

Extraction of Minor Compounds (Chlorophylls and Carotenoids) from Yarrow–Rose Hip Mixtures by Traditional versus Green Technique

AbstractNowadays, various branches from food industry generate large amount of by‐products that are often underutilized, which could have negative environmental impact and increase the price of the raw material as it is not completely utilized in the production. Mixtures of two interesting plants (yarrow and rose hip) with different ratios, obtained as by‐products from filter‐tea factory, have been extracted with organic solvents and with environmentally friendly technology, supercritical fluid extraction (SFE). In the obtained extracts, quantitative content of minor plant pigments (chlorophylls and carotenoids) was determined and technologies were compared. Moreover, the effect of SFE parameters on yields of chlorophylls and carotenoids was determined. The results showed that SFE could be used as a good alternative for extraction of plant pigments from Achillea millefolium L. and Rosa canina L. mixtures. Besides plant pigments, the obtained extracts were rich in other nonpolar compounds from plant mixtures. Utilization of herbal waste provided value‐added products, rich in various health benefit compounds.Practical ApplicationsCurrently, there is growing interest for developing economically feasible and environmentally friendly processes for extraction of bioactive compounds from plant material. Moreover, sustainable and relatively cheap raw material should be utilized in the production. Therefore, waste and by‐products from the food industry, e.g., plant material from filter‐tea factory with small mean particle size, could be used. Traditional technologies used for extraction of chlorophylls and carotenoids are no longer environmentally acceptable and alternative green technologies, such as supercritical fluid extraction, should be considered. This research provides a comparison of green and traditional processes for plant pigment extraction and studies effects of process parameters (pressure and temperature) on yields of the investigated compounds. It also utilizes by‐products of two medicinal plants (yarrow and rose hip) as raw material for extraction as herbal dust generated in filter‐tea factory could not be used for tea bags filling.

Production of polymeric nanoparticles by micromixing in a co-flow microfluidic glass capillary device

Synthetic polymeric biodegradable nanoparticles were produced by micromixing combined with nanoprecipitation in a co-flow glass capillary device consisted of coaxial assembly of glass capillaries, fabricated by aligning a tapered-end round capillary inside a square capillary with 1mm internal dimension. Micromixing of water and organic phase (1wt% polylactide or polycaprolactone dissolved in tetrahydrofuran) was modelled using a commercial software package Comsol Multiphysics™ and experimentally investigated using dynamic light scattering, Nanoparticle Tracking Analysis (NTA) and in situ microscopic observation. The organic phase was injected through a nozzle with a diameter of 60μm at the organic-to-aqueous flow-rate ratios ranging from 1.5 to 10. The locations at which the nanoparticles would form were determined by using the solubility criteria of the polymer and the concentration profiles found by numerical modelling. The convective flux of the polymer in the radial direction was 2–3 orders of magnitude higher than the diffusive flux of the polymer; hence responsible for mixing the streams. The convective flux near the orifice was 3–4 orders of magnitudes higher than at the end of the computational domain. A maximum convective flux of 0.115kgm−2s−1 was found for polycaprolactone at the cloud point for the lowest flow rate ratio investigated. The numerical results were consistent with the experimental observations in terms of flow patterns and mean particle size. Narrower particle size distributions and smaller mean particle sizes were obtained at the higher aqueous-to-organic flow-rate ratios.

Optimization of controlled release nanoparticle formulation of verapamil hydrochloride using artificial neural networks with genetic algorithm and response surface methodology

This study was performed to optimize the formulation of polymer–lipid hybrid nanoparticles (PLN) for the delivery of an ionic water-soluble drug, verapamil hydrochloride (VRP) and to investigate the roles of formulation factors. Modeling and optimization were conducted based on a spherical central composite design. Three formulation factors, i.e., weight ratio of drug to lipid (X1), and concentrations of Tween 80 (X2) and Pluronic F68 (X3), were chosen as independent variables. Drug loading efficiency (Y1) and mean particle size (Y2) of PLN were selected as dependent variables. The predictive performance of artificial neural networks (ANN) and the response surface methodology (RSM) were compared. As ANN was found to exhibit better recognition and generalization capability over RSM, multi-objective optimization of PLN was then conducted based upon the validated ANN models and continuous genetic algorithms (GA). The optimal PLN possess a high drug loading efficiency (92.4%, w/w) and a small mean particle size (∼100nm). The predicted response variables matched well with the observed results. The three formulation factors exhibited different effects on the properties of PLN. ANN in coordination with continuous GA represent an effective and efficient approach to optimize the PLN formulation of VRP with desired properties.

Determination of small soot particles in the presence of large ones from time-resolved laser-induced incandescence

A novel strategy for the analysis of time-resolved laser-induced incandescence (TiRe-LII), called two-exponential reverse fitting (TERF), is introduced. The method is based on combined monoexponential fits to the LII signal decay at various delay times and approximates the particle-size distribution as a weighted combination of one large and one small monodisperse equivalent mean particle size without requiring assumption on the particle-size distribution. The effects of particle size, heat-up temperature, aggregate size, and pressure on the uncertainty of this method are evaluated using numerical experiments for lognormal and bimodal size distributions. TERF is applied to TiRe-LII measured in an atmospheric pressure laminar non-premixed ethylene/air flame at various heights above burner. The results are compared to transmission electron microscopy (TEM) measurements of thermophoretically sampled soot. The particle size of the large particle-size class agreed well for both methods. The size of the small particle-size class and the relative contribution did not agree which is attributed to missing information in the TEM results for very small particles. These limitations of TEM measurements are discussed and the effect of the exposure time of the sampling grid is evaluated.

Stealth Amphotericin B nanoparticles for oral drug delivery: In vitro optimization

PurposeAmphotericin B (AmB) is an effective anti-fungal and anti-leishmanial agent. However, AmB has low oral bioavailability (0.3%) and adverse effects (e.g., nephrotoxicity). The objectives of this study were to improve the oral bioavailability by entrapping AmB in pegylated (PEG) poly lactide co glycolide copolymer (PLGA–PEG) nanoparticles (NPs). The feasibility of different surfactants and stabilizers on the mean particle size (MPS) and entrapment efficiency were also investigated. Materials and methodsNPs of AmB were prepared by a modified emulsification diffusion method employing a vitamin E derivative as a stabilizer. Physicochemical properties and particle size characterization were evaluated using Fourier Transform Infra-Red spectroscopy (FTIR), differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. Moreover, in vitro dissolution profiles were performed for all formulated AmB NPs. ResultsMPS of the prepared spherical particles of AmB ranged from 26.4±2.9 to 1068±489.8nm. An increased stirring rate favored AmB NPs with a smaller MPS. There was a significant reduction in MPS, drug content and drug release, when AmB NPs were prepared using the diblock polymer PLGA–PEG with 15% PEG. Addition of three emulsifying agents poly vinyl pyrrolidone (PVP), Vitamin E (TPGS) and pluronic F-68 to AmB formulations led to a significant reduction in particle size and increase in drug entrapment efficiency (DEE) compared to addition of PVP alone. FTIR spectroscopy demonstrated a successful loading of AmB to pegylated PLGA–PEG copolymers. PLGA–PEG copolymer entrapment efficiency of AmB was increased up to 56.7%, with 92.7% drug yield. After a slow initial release, between 20% and 54% of AmB was released in vitro within 24h phosphate buffer containing 2% sodium deoxycholate and were best fit Korsmeyer–Peppas model. In conclusion, PLGA–PEG diblock copolymer with 15% PEG produced a significant reduction (>70%) in MPS with highest drug content. The percentage of PEG in the copolymer and the surfactant/stabilizer used had a direct effect on AmB release in vitro, entrapment efficiency and MPS. These developed formulations are feasible, effective and improved alternatives to other carriers for oral delivery of AmB.

Transdermal immunization using solid-in-oil nanodispersion with CpG oligodeoxynucleotide adjuvants.

Simple and noninvasive vaccine administration alternatives to injections are desired. A solid-in-oil (S/O) nanodispersion system was able to overcome skin barriers and induce an immune response; however, antibody levels remained low. We applied an immune potentiator, CpG oligodeoxynucleotide (ODN), to enhance the immune response by controlling the T helper 1 (Th1)/T helper 2 (Th2) balance. S/O nanodispersions containing ovalbumin (OVA) and CpG ODN (CpG-A or CpG-B) were characterized by size distribution analysis and a protein release test. The skin permeation of fluorescence-labeled OVA was observed by fluorescence microscopy. Antigen-specific IgG, IgG1, and IgG2a responses were measured by enzyme-linked immunosorbent assay. Co-encapsulation of CpG ODNs in S/O nanodispersions enhanced induction of OVA-specific IgG. S/O nanodispersion containing OVA and CpG-A had a smaller mean particle size and permeated the skin more efficiently. In contrast, CpG-B showed the highest protein release and induction of OVA-specific IgG. IgG subclass analysis revealed that OVA induced a Th2-dominant immune response, while the S/O nanodispersion containing CpG-A skewed the immune response toward a Th1-bias. In combination with CpG ODN, the S/O nanodispersion system efficiently induced an antigen-specific antibody response. The Th1/Th2 immune balance could be controlled by the selection of CpG ODN type.

Synthesis of Polyurethane Dispersions in Nanoparticles and Their Properties that Depend on Aging Time

Waterborne polyurethane dispersions in nanoparticles were synthesized from poly (propylene glycol), isophorone diisocyanate, and dimethylolpropionic acid in a modified prepolymer process. Three groups of specimens with variations in hard-to-soft segment molar ratios were synthesized in Group A experiments to confirm the recipe of waterborne polyurethane, whose particles have the smallest mean particle size and the narrowest particle size distribution. Group B experiments, which consist of five samples, were designed based on the results of Group A experiments. The variable of each sample was one kind of raw materials’ content compared with the confirmed recipe in Group A experiments. Relationships among variations in viscosity, mean nanoparticle size, and nanoparticle size distribution over time were analyzed. It was found that the viscosity of all samples increased, mean nanoparticle size remained constant or decreased, and nanoparticle size distribution became narrow over time. Our work provides a new recipe for the preparation of waterborne polyurethane of nanoparticles with excellent stability. Moreover, aging time is considered to be a key index to viscosity, particle size, and particle size distribution in the polyurethane dispersion.

Vegetable oil based emulsions in milk

Milk and dairy products represent an important part of functional food in the market. Based on their positive health and nutritional benefits, they have gained popularity and their consumption as well as production is on the rise in the last few decades. As a result of this trend, milk-based products are being used for the delivery of bioactive food ingredients. This study is devoted to the formulation of stable emulsions containing grape seed oil dispersed with several emulsifiers (Tween 80, monocaprylin, and lecithin) in milk. Photon correlation spectroscopy was used to evaluate the characteristics of the emulsions in terms of mean droplet size, droplet size distribution and polydispersity index. Emulsions were prepared using 2% and 5% w/w grape seed oil, and 3%, 5%, or 8% w/w emulsifier, and these were homogenized at two different rates of 1050 and 13400 rpm. Parameters influencing emulsion particle size and particle size distribution were identified, which included emulsifier type, its HLB value, oil type (virgin, refined), homogenization rate and the fat content in the milk. Homogenization at 13400 rpm for 10 min. produced fine emulsions with small mean particle sizes and monomodal distribution of droplets. Regarding emulsifier type, the smallest droplet sizes were obtained with formulations containing Tween 80 (250-315 nm), whereas lecithin primarily accounted for the monomodal particle size distributions.

Synthesis of Highly Dispersed Ruthenium Nanoparticles Supported on Activated Carbon via Supercritical Fluid Deposition

Highly dispersed ruthenium (Ru) nanoparticles supported on activated carbon (AC) were controllably synthesized by supercritical fluid deposition (SFD). The Ru nanoparticles prepared by SFD presented a smaller mean particle size than particles prepared by the ethanol impregnation method. The effects of temperature, pressure, and Ru loading on catalyst preparation were systematically investigated. As any one of above parameters increased, Ru mean particle sizes always decreased first and then increased. The smallest mean particle size (1.6 nm) was obtained at Ru loading of 2%, 45 °C, and 10 MPa. On the scale of Ru mean particle size from 1.6 to 3.9 nm, the catalysts with smaller Ru mean particle size presented higher catalytic activity. The interactions between the Ru precursor and AC were characterized by TG–MS, TPR, and FTIR spectroscopy. The results obtained have revealed the reduction of the carbonyl (C═O) in Ru precursors after depositing on AC with the aid of SCCO2.

Abrasiveness index of dispersions of Portuguese clays using the Einlehner method: influence of clay parameters

AbstractThe unique properties of clays make them suitable for a large number of applications. Among the procedures that can be used to characterize clayey materials, the assessment of the abrasion and the abrasiveness index can be employed to predict the mechanical behaviour of clay samples. However, only a limited number of references to these testing procedures are available in the literature. Several Portuguese clayey samples were collected and the &lt;63 μm fraction was analysed. The main clay minerals present are kaolinite, illite and smectite. The abrasiveness index depends on the granulometric and mineralogical compositions. A lower abrasiveness is induced by the presence of a high abundance of the &lt;2 μm fraction, small mean particle size and a large phyllosilicate content . Kaolinite and illite show good correlation with the abrasiveness index, while smectite decreases abrasion.