Broad Particle Size Distribution Research Articles

Mechanical Dewatering of Homogeneous and Segregated Filter Cakes by Vibration Compaction

The solid volume fraction of a slurry requiring solid–liquid separation often fluctuates in industrial cake filtration processes. For low solid volume fractions, particle segregation arises, resulting in an inhomogeneous filter cake structure. Particle segregation has significant impacts on cake formation such as a longer cake formation time compared to homogeneous cakes. This work addresses the impact of this effect on vibration compaction, which is an alternative deliquoring method applying oscillatory shears to the filter cake. The dewatering results of homogeneous and segregated cakes made of the same material with a broad particle size distribution are compared. Although cake deliquoring is achievable despite particle segregation, vibration compaction is more effective for homogeneous cakes. The reason is that no particle size homogenization within segregated cakes occurs due to oscillatory shear, as particle size analyses indicate. The particle size measurements of cakes before and after vibration compaction reveal that the material’s particle size distribution is preserved despite vibration application. Vibration compaction achieves higher deliquoring than the common compaction method by squeezing, as elastic recovery effects after squeezing lead to the reabsorbing of liquid, already expressed and stored in the filter cloth. This demonstrates that vibration compaction is a real alternative for cake deliquoring.

Single-Particle Elemental Analysis of μm-Sized Battery Materials by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Lithium-nickel-manganese-cobalt-oxides (NCMs) represent a preeminent class of cathode active materials for employment in commercially available lithium-ion battery applications. To realize large-scale production of the respective NCM precursors, coprecipitation is often conducted in continuous stirred-tank reactors (CSTR). However, precursors coming from CSTR processes show broad particle size distributions and undesired compositional differences within and between particles. To quantify this phenomenon, it is necessary to develop analytical tools to access quantitative data on particle composition depending on their size. Here, we demonstrate a novel application of single particle laser ablation-inductively coupled plasma-mass spectrometry to determine particle size-dependent elemental compositions by exemplary investigation of CSTR-based NCM precursors. An enrichment of Ni in larger particles with a concomitant enrichment of Co and Mn in smaller particles was identified. This compositional differences between particles persisted after calcination of the precursors with lithium hydroxide. The observed particle size-dependent concentration differences by spLA-ICP-MS were validated by scanning electron microscopy with energy-dispersive X-ray analysis.

Comprehensive physicochemical characterization of Algerian coal powders for the engineering of advanced sustainable materials

The object of the research is the intriguing and versatile material known as coal that attracted a lot of attention lately because of its potential use in a variety of fields, including cutting-edge building materials, environmental remediation methods, and creative energy storage solutions. This study presents an extensive characterization of Algerian natural coal powders, employing a multifaceted analytical approach that includes Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Raman Spectroscopy, to reveal their physicochemical properties including morphology, particle size distribution, crystalline structure, and functional groups. The SEM analysis unveiled a heterogeneous morphology with a broad particle size distribution, indicative of the coal's complex structure. The XRD findings, refined using Rietveld analysis, distinguish Carbon (C) and Silicon Dioxide (SiO2) as the primary phases, with crystallite sizes measuring 18.7539 nm for C and 16.6291 nm for SiO2. These phases constitute 98.8 % and 12 % of the composition, respectively, while the presence of quartz underscores the coal’s geological background and its thermal resilience. Regarding the results of the FTIR spectroscopy, absorption peaks corresponding to various functional groups are highlighted, suggesting a rich organic and inorganic composition. Raman spectroscopy corroborates the presence of disordered and graphitic carbon structures, emphasizing the coal's potential for diverse applications. These findings underline the significance of Algerian coal powders for environmental remediation, energy storage, and advanced construction materials, contributing to the advancement of sustainable energy solutions.

Investigating the Metallic Nanoparticles Decoration on Reduced Graphene Oxide-Based Sensors Used to Detect Sulfur Dioxide

This paper presents the impact of the decoration of reduced graphene oxide (rGO) with metallic nanoparticles to detect sulfur dioxide (SO2). Copper and platinum were employed to produce metal nanoparticles (NPs) for the chemical and physical decoration of rGO to form the nanocomposites (rGO/NPs). We optimized NP loading by varying the concentrations of metal ions and deposition times for chemical and physical decoration, respectively. The chemical decoration presents a random nanoparticle distribution on the rGO surface with a broad particle size distribution (1 to 100 nm with a majority less than 40 nm). In comparison, the physical decoration presents uniformly distributed nanoparticles with particles of a size between 1 and 20 nm, with a majority less than 10 nm. The chemically decorated structures present the best gas responses and show that lower NP loading provides better responses. The nanocomposites present responses owing to a better synergy between NPs and the rGO surface, combined with the catalytic action of the NPs on the rGO. The physical decoration allows higher NP surface coverage than the chemical one but implies a lower remaining rGO naked surface for gaseous molecule interaction. These results illustrate that the NPs’ surface and the uncovered rGO contribute to the gas response.

DEM simulation of a single screw granulator: The effect of liquid binder on granule properties

The Caleva UK single-screw Variable Density Extruder (VDE) is a continuous powder processing equipment known for spheronization and extrusion. Its suitability for granulation remains uncertain, a common challenge in powder processing industries that deal with granules, pellets, and tablets. This study investigates the VDE's potential for granulation, using 65 µm CaCO3 powder and PEG 4000 as a liquid binder. In order to replicate several experimental setups with varying binder concentrations and liquid-to-solid ratios (L/S) of 0.1 and 0.15, eight DEM simulations were run. Our results indicate that higher binder concentrations yield more consistent products with fewer fines, while lower concentrations result in inconsistent products with increased fines. Low L/S ratios produce fragile, fine-sized products with a broad particle size distribution (PSD). DEM simulations reveal a direct relationship between liquid binder content and contact forces. Analysis of bonds formed, and particle counts in simulations corroborates experimental observations of fines production. Additionally, granule strength appears to be directly proportional to contact force.

Whitlockite -A study on the effect of reaction parameters on morphology in one-solvent system

Whitlockite (WK) is a hierarchically self-assembled and second most abundant biomineral in a naturally occurring complex bone at the nanoscale. Most of the properties at the nanoscale are size and shape-dependent. However, single-phase synthesis of WK is challenging and is pH and temperature-dependent. This work reports the different shapes and sizes of a novel bone-regenerative mineral (whitlockite) in a one-solvent system. We designed and investigated the synthetic conditions to achieve morphologically different WK nanostructures by fine-tuning the precursor's proportion, pH, temperature, and ageing. By manipulating the pH to 5.4, we successfully synthesised irregular plates of pure WK nanostructures. Conversely, through temperature control within the range of 90 °C–100 °C, various morphologies of pure whitlockite, such as cubes, irregular plates, clusters, and spheres, were attained. However, elongated clusters of WK structures were obtained after ageing the solution for three days at 90 °C. A broader particle size distribution was achieved within the 76.4 nm to 1 μm range. The purity, crystallinity, formation of auxiliary phases, functional groups, shapes, sizes, and elemental composition were investigated through correlative analytical approaches encompassing XRD, FTIR, Raman, SEM and EDS.

Embedding and cross-sectioning as a sample preparation procedure for accurate and representative size and shape measurement of nanopowders

Reliable measurement of the size of polydisperse, complex-shaped commercial nanopowders is a difficult but necessary task, e.g., for regulatory requirements and toxicity risk assessment. Suitable methods exist for the accurate characterization of the size of non-aggregated, stabilized, spherical and monodisperse nanoparticles. In contrast, industrial nanoscale powders usually require dedicated sample preparation procedures developed for the analysis method of choice. These nano-powders tend to agglomerate and/or aggregate, a behavior which in combination with an innate broad particle size distribution and irregular shape often significantly alters the achievable accuracy of the measured size parameters. The present study systematically tests two commercially available nanoscale powders using different sample preparation methods for correlative analysis by scanning electron microscopy, dynamic light scattering, Brunauer–Emmet–Teller method and differential mobility analysis. One focus was set on the sample preparation by embedding nanoparticles in carbon-based hot-mounting resin. Literature on this topic is scarce and the accuracy of the data extracted from cross sections of these particles is unclearly stated. In this paper systematic simulations on the deviation of the size parameters of well-defined series of nanoparticles with different shapes from the nominal value were carried out and the contributing factors are discussed.

Improving the formability and mechanical properties of TiAl alloy by direct forging of uncondensed powder

The limited plasticity and poor formability of TiAl alloys constitute primary constraints on their widespread applicability. In this regard, an innovative forming method is proposed, characterized by the direct forging of unconsolidated pre-alloyed Ti–48Al–2Cr–2Nb powders. In this procedure, spherical powders with a broad particle size distribution are pre-encapsulated and subjected to vacuumed treatment, followed by direct high-temperature forging to attain the final desired shape. Throughout the process, the powders undergo pre-heating to various forming temperatures and are forged at different speeds, enabling a comparative analysis of the effect of forging temperature and speed on densification and the microstructural characteristics of the forged billet. Experimental results indicate that the powders can be nearly fully densified when direct forging is conducted within the α-phase region. By combining the finite element modeling and microstructural characterization, three mechanisms dominating the consolidation process of powders are revealed. Initial particle clustering and spatial rearrangement predominantly occur during the early deformation stage, enhancing densification. Subsequent fragmentation of particles, induced by severe plastic deformation, governs the entire deformation process, leading to the elimination of the prior particle boundaries and substantial densification improvement. The closure of the micrometer-scale voids is controlled by high-temperature diffusion and creep, which plays a pivotal role in weakening the detrimental effect of micro defects on mechanical properties. The above mechanisms act alternately or simultaneously, resulting in a homogeneous microstructure composed of α2+γ lamellae and bulk γ with small sizes, and a good synergy of strength and ductility. Therefore, this novel approach holds considerable potential as a cost-effective alternative strategy for producing TiAl components.

Film formation kinetics of polystyrene latex‐based nanocomposites with a broad particle size distribution

AbstractThe present study article aims to clarify the effect of colloidal polystyrene (PS) latexes with a broad particle size distribution on film formation kinetics of multi‐walled carbon nanotube (MWCNT)‐added polymer nanocomposites by considering theoretical film formation models. Experimentally, light transmitted from nanocomposite films, each having different weight fractions of MWCNT, was recorded at different annealing temperatures via UV–Visible spectrophotometry. Optical data set was then theoretically elaborated by taking into account void closure and Prager‐Tirrell models. Activation energies of viscous flow (ΔH) and backbone motion for reptating PS chains (ΔEB), minimum film formation (T0) and healing (Th) temperatures were then computed from optical data. Experimental results revealed that ΔH required for void closure phenomenon remained unaffected by both nanofiller and size distribution of latexes. On the other hand, it was found that ΔEB for backbone motion promoted upon the addition of nano‐fillers into latex particles. Our experimental findings suggested that film formation from MWCNT‐added latex films with a broad particle size distribution mainly originates from void closure mechanism since ΔH for viscous flow suppresses ΔEB acquired for backbone motion of repeating PS chains to a great extent.Highlights A broad size distribution effect of PS on film formation was investigated. Voids closure and Prager‐Tirrell models were applied to spectroscopic data. Activation energy of viscous flow is unaffected by size distribution of PS. Latex film formation with varying size distribution stems from void closure.

One-Pot Synthesis of Bioinspired Peptide-Decorated Apatite Nanoparticles for Nanomedicine.

Hybrid organic-inorganic bio-inspired apatite nanoparticles (NPs) are attractive for biomedical applications and especially in nanomedicine. Unfortunately, their applications in nanomedicine are limited by their broad particle size distributions and uncontrolled drug loading due to their multistep synthesis process. Besides, very few attempts at exposing bioactive peptides on apatite NPs are made. In this work, an original one-pot synthesis of well-defined bioactive hybrid NPs composed of a mineral core of bioinspired apatite surrounded by an organic corona of bioactive peptides is reported. Dual stabilizing-bioactive agents, phosphonated polyethylene glycol-peptide conjugates, are prepared and directly used during apatite precipitation i) to form the organic corona during apatite precipitation, driving the size and shape of resulting hybrid NPs with colloidal stabilization and ii) to expose peptide moieties (RGD or YIGSR sequences) at the NPs periphery in view of conferring additional surface properties to enhance their interaction with cells. Here, the success of this approach is demonstrated, the functionalized NPs are fully characterized by Fourier-transform infrared, Raman, X-ray diffraction, solid and liquid state NMR, transmission electron microscopy, and dynamic light scattering, and their interaction with fibroblast cells is followed, unveiling a synergistic proliferative effect.

Design of spinning disk atomization equipment for synthesis of drug-loaded microparticles.

The synthesis of drug-loaded microparticles with precise control over size distribution and shape is crucial for achieving desired drug distribution in microparticles and tuning drug release profiles. Common large-scale production techniques produce microparticles with a broad particle size distribution and require challenging operating conditions. Recent methods employing microfluidics have enabled the production of microparticles with a uniform size distribution. Still, these methods are limited to low and moderate production rates and can handle fluids with a limited range of physicochemical properties. In this study, we couple the spinning disk atomization (SDA) technique for microdroplet production with a precipitation method to generate drug-loaded polymeric microparticles with a narrow size distribution. The design criteria and fabrication of equipment with a non-contact seal system that integrates spinning disk atomization and precipitation methods for conducting laboratory experiments involving volatile hydrocarbons while ensuring operational and personnel safety are discussed. The production of itraconazole drug-loaded microparticles using the SDA setup that considers the system's operation, maintenance, and safety aspects are discussed, and the system's efficiency is evaluated through material balance. This laboratory equipment is capable of producing drug-loaded microparticles with a narrow size distribution under moderate operating conditions and can be scaled up suitably to meet high production requirements. The applications of this equipment can be explored in various fields, such as the production of drug particles, conversion of waste polymers into microparticles, and microencapsulation of food ingredients.

A comparison of Eulerian and Lagrangian methods for vertical particle transport in the water column

Abstract. A common task in oceanography is to model the vertical movement of particles such as microplastics, nanoparticles, mineral particles, gas bubbles, oil droplets, fish eggs, plankton, or algae. In some cases, the distribution of the vertical rise or settling velocities of the particles in question can span a wide range, covering several orders of magnitude, often due to a broad particle size distribution or differences in density. This requires numerical methods that are able to adequately resolve a wide and possibly multi-modal velocity distribution. Lagrangian particle methods are commonly used for these applications. A strength of such methods is that each particle can have its own rise or settling speed, which makes it easy to achieve a good representation of a continuous distribution of speeds. An alternative approach is to use Eulerian methods, where the partial differential equations describing the transport problem are solved directly with numerical methods. In Eulerian methods, different rise or settling speeds must be represented as discrete classes, and in practice, only a limited number of classes can be included. Here, we consider three different examples of applications for a water column model: positively buoyant fish eggs, a mixture of positively and negatively buoyant microplastics, and positively buoyant oil droplets being entrained by waves. For each of the three cases, we formulate a model for the vertical transport based on the advection–diffusion equation with suitable boundary conditions and, in one case, a reaction term. We give a detailed description of an Eulerian and a Lagrangian implementation of these models, and we demonstrate that they give equivalent results for selected example cases. We also pay special attention to the convergence of the model results with an increasing number of classes in the Eulerian scheme and with the number of particles in the Lagrangian scheme. For the Lagrangian scheme, we see the 1/Np convergence, as expected for a Monte Carlo method, while for the Eulerian implementation, we see a second-order (1/Nk2) convergence with the number of classes.

Hierarchical bubble size distributions in coarsening wet liquid foams

Coarsening of two-phase systems is crucial for the stability of dense particle packings such as alloys, foams, emulsions, or supersaturated solutions. Mean field theories predict an asymptotic scaling state with a broad particle size distribution. Aqueous foams are good model systems for investigations of coarsening-induced structures, because the continuous liquid as well as the dispersed gas phases are uniform and isotropic. We present coarsening experiments on wet foams, with liquid fractions up to their unjamming point and beyond, that are performed under microgravity to avoid gravitational drainage. As time elapses, a self-similar regime is reached where the normalized bubble size distribution is invariant. Unexpectedly, the distribution features an excess of small roaming bubbles, mobile within the network of jammed larger bubbles. These roaming bubbles are reminiscent of rattlers in granular materials (grains not subjected to contact forces). We identify a critical liquid fraction [Formula: see text], above which the bubble assembly unjams and the two bubble populations merge into a single narrow distribution of bubbly liquids. Unexpectedly, [Formula: see text] is larger than the random close packing fraction of the foam [Formula: see text]. This is because, between [Formula: see text] and [Formula: see text], the large bubbles remain connected due to a weak adhesion between bubbles. We present models that identify the physical mechanisms explaining our observations. We propose a new comprehensive view of the coarsening phenomenon in wet foams. Our results should be applicable to other phase-separating systems and they may also help to control the elaboration of solid foams with hierarchical structures.

Influence of magnetite concentrate morphology on oxidation and sintering rates of pellet during induration

This study investigates the influence of the morphology of concentrate on the oxidation and sintering rates of magnetite pellets during induration and its impact on the indurated pellets' quality. Various morphologies of concentrates were obtained by ball milling (BM) and high-pressure grinding rolls (HPGR). Pelletizing and induration processes were carried out at different temperatures and times. After a comparative study of the physical characteristics of concentrate powders, the effect of morphology was evaluated through thermal behavior during induration. The physical, microstructural, and strength properties of pellets were also investigated. The HPGR concentrate had angular and elongated-shaped particles with a broad particle size distribution, while the BM particles had a more rounded morphology, and their size distribution was narrower. Results showed that BM and HPGR magnetite pellets are oxidized between 270 and 950 °C. HPGR pellets oxidize slower than BM pellets. Cold compressive strength (CCS) was increased by induration time, although porosity was reduced. HPGR pellets had less porosity than BM pellets; however, their CCS was significantly higher. For pellets indurated at 1200 °C, the difference in CCS between HPGR and BM pellets increased with an increment in the induration time and reached 80 kg/pellet in 20 min. The microstructural analysis took place on the concentrate powder and pellets fracture surface. It was found that HPGR powder sinters faster than BM powder due to its angular shape and broad particle size distribution.

Effect of Crushing Method on the Properties of Produced Recycled Concrete Aggregates

Construction and Demolition Waste (C&DW) is generated around the world and its quantity will increase in the future. Recycling has become the favored method of dealing with concrete waste but, to avoid its downcycling, it is important to develop a recycling process which is able to produce high-grade recycled concrete aggregates (RCA). To that end, studying the influence of the production process on the properties of RCA can prove to be a crucial step toward a more circular construction industry. In this study, the influence of the crushing method is investigated. Samples of five laboratory-made concretes have been crushed using the most common mechanical crushing methods (impact crusher and jaw crusher), and the particle size distribution, morphology, hardened cement paste content and water absorption of the produced RCA have been measured and analyzed. The findings indicate that the use of impact crushers results in the production of RCA possessing more spherical geometric characteristics, albeit with a broader particle size distribution and a relatively higher content of fine particles as compared to those obtained from jaw crushers. Additionally, it is observed that the employed crushing technique seemingly exerts no discernible impact on the hardened cement paste content and the water absorption in the context of the studied concretes.

Dual Optical Sensing of Al3+ and Hg2+ Using Carbon Dots Synthesized from Biomass

This study aimed to use a simple, low-cost and eco-friendly microwave-assisted method for the synthesis of carbon dots-based fluorescent sensor that can detect more one target analyte in aqueous media. Herein, we report the synthesis of carbon dots (CDs) from peels of an indigenous and abundant wild fruit called wild medlar (Vangueria infausta). Functional groups such as hydroxyl (–OH) and carbonyl (C=O) were revealed on the surface of the as-prepared carbon dots using Fourier transform infrared spectroscopy (FTIR). The as-prepared CDs exhibited an amorphous structure and a broad distribution of particle size with an average size of 10 nm. In addition, the as-prepared CDs demonstrated excellent hydrophilicity and intense blue photoluminescence under UV light at 365 nm. The water-soluble CDs were employed for the detection of Al[Formula: see text] using a ‘turn on’ mechanism and Hg[Formula: see text] using a ‘turn off’ mechanism. Addition of increasing concentration of Al[Formula: see text] resulted in an increase in the fluorescence intensity of the as-prepared CDs while addition of increasing concentration of Hg[Formula: see text] resulted in quenching of the fluorescence intensity of CDs. The lowest limit of detection (LOD) for Al[Formula: see text] and Hg[Formula: see text] ions in aqueous media was determined at 817 nM and 612 nM, respectively. Furthermore, the as-prepared CDs have excellent selectivity towards Al[Formula: see text] and Hg[Formula: see text] among other potential metal ion interferences. Practical application of the as-prepared CDs towards detection of Al[Formula: see text] and Hg[Formula: see text] in tap water revealed good recovery rates of 86.0% to 87.4% and 96.4% to 106.5%, respectively. Therefore, this work has demonstrated a potent strategy for potential application of this nanoprobe towards dual detection of Al[Formula: see text] and Hg[Formula: see text] in aqueous samples.

Fractal-like kinetics for enhanced boron adsorption on heterogeneous magnetic composite surfaces

Co-precipitated 14 nm γ-Fe2O3 and 35 nm MgO nanoparticles (NPs) decorated on zeolite 5 A (Z5A) templates were systematically studied. 57Fe Mössbauer and transmission electron microscopy data indicated a broad particle size distribution. The spinel structure of γ-Fe2O3 is strongly affected by size effects (particles smaller than 10 nm in size have an octahedral/tetrahedral iron site ratio of 7/3 instead of 5/3 found in bulk). 27Al nuclear magnetic resonance (NMR) showed the formation of octahedral Al species after boric acid reaction with MgO NPs. 11B NMR spectra indicated adsorption of B on the MgO/Z5A surface, whereas B adsorption in the pure Z5A framework is absent. Adsorption isotherms and kinetic studies of the nanohybrids showed that the B-rich species adsorption is described by Freundlich and fractal-like models, respectively. B adsorption occurs dominantly by the MgO fraction. The nanohybrids presented a good B removal efficiency when compared with other materials reported in literature.

Evidencing the synergistic effects of carbonization temperature, surface composition and structural properties on the catalytic activity of biochar/bimetallic composite

The effect of pyrolysis temperature on biochar properties is more exacerbated when combined with the presence of metallic dopants on the surface of the lignocellulosic material. Herein, we investigate the relationship between the surface composition (SC), the graphitization degree (GD), the particle size (PS) and the catalytic activity of mandarin peel biochar decorated with copper and nickel alloy. All biochar samples were prepared by a wet impregnation of the metal ions followed by slow pyrolysis of the Cu2+/Ni2+-loaded biomass at temperatures ranging from 300° to 700 °C, for 15 min and under N2 atmosphere. Interestingly, the biochar with the highest GD was obtained at 300 °C; its surface contained CuNi alloy and NiO, whereas it contained only the bimetallic alloy for all samples fabricated at 500 and 700 °C. The 300 °C and 500 °C samples have mean PSs in the nanoscale regime, 71 ± 12 nm and 54 ± 12 nm, respectively. On contrast, the 700 °C biochar composites have very broad PS distributions in the 30–400 nm size range. They were also found to be the least graphitized samples. Practically, the 300 °C nanocomposite was the most active catalyst for the oxidative degradation of Methylene Blue, chosen as a model reaction for the catalytic performance testing. The degradation was total under H2O2 conditions, and the kinetic experimental data fitted the pseudo-first-order with degradation apparent constant 0.071 min-1. Despite its lowest mean particle size and graphitization degree, higher than the graphitization degrees of the 700 °C nanocomposites, the sample elaborated at 500 °C was the least active catalyst. Its highest K to C atomic ratio suggests that potassium emerging from the biochar surface had a poisoning effect which deactivated the CuNi alloy. Conclusively, these findings permitted to gain more insights into the synergistic effects of surface composition, particle size and graphitization degree on the catalytic activity of Biochar-supported CuNi alloy elaborated at different pyrolysis temperatures.

Dragon's Blood Sap Microencapsulation within Whey Protein Concentrate and Zein Using Electrospraying Assisted by Pressurized Gas Technology.

Dragon's blood sap (DBS) obtained from the bark of Croton lechleri (Müll, Arg.) is a complex herbal remedy of pharmacological interest due to its high content in polyphenols, specifically proanthocyanidins. In this paper, electrospraying assisted by pressurized gas (EAPG) was first compared with freeze-drying to dry natural DBS. Secondly, EAPG was used for the first time to entrap natural DBS at room temperature into two different encapsulation matrices, i.e., whey protein concentrate (WPC) and zein (ZN), using different ratios of encapsulant material: bioactive compound, for instance 2:1 w/w and 1:1 w/w. The obtained particles were characterized in terms of morphology, total soluble polyphenolic content (TSP), antioxidant activity, and photo-oxidation stability during the 40 days of the experiment. Regarding the drying process, EAPG produced spherical particles with sizes of 11.38 ± 4.34 µm, whereas freeze-drying produced irregular particles with a broad particle size distribution. However, no significant differences were detected between DBS dried by EAPG or freeze-drying in TSP, antioxidant activity, and photo-oxidation stability, confirming that EAPG is a mild drying process suitable to dry sensitive bioactive compounds. Regarding the encapsulation process, the DBS encapsulated within the WPC produced smooth spherical microparticles, with average sizes of 11.28 ± 4.28 µm and 12.77 ± 4.54 µm for ratios 1:1 w/w and 2:1 w/w, respectively. The DBS was also encapsulated into ZN producing rough spherical microparticles, with average sizes of 6.37 ± 1.67 µm and 7.58 ± 2.54 µm for ratios 1:1 w/w and 2:1 w/w, respectively. The TSP was not affected during the encapsulation process. However, a slight reduction in antioxidant activity measured by DPPH was observed during encapsulation. An accelerated photo-oxidation test under ultraviolet light confirmed that the encapsulated DBS showed an increased oxidative stability in comparison with the non-encapsulated DBS, with the stability being enhanced for the ratio of 2:1 w/w. Among the encapsulating materials and according to the ATR-FTIR results, ZN showed increased protection against UV light. The obtained results demonstrate the potential of EAPG technology in the drying or encapsulation of sensitive natural bioactive compounds in a continuous process available at an industrial scale, which could be an alternative to freeze-drying.

Calibration Strategy to Size and Localize Multi-Shaped Nanoparticles in Tissue Sections Using LA-spICP-MS.

In the field of nanotoxicology, the detection and size characterization of nanoparticles (NPs) in biological tissues become increasingly important. To gain information on both particle size and particle distribution in histological sections, laser ablation and single particle inductively coupled plasma-mass spectrometry (LA-spICP-MS) was used in combination with a liquid calibration of dissolved metal standards via a pneumatic nebulizer. In the first step, the particle size distribution of Ag NPs embedded in matrix-matched gelatine standards introduced via LA was compared with that of Ag NPs in a suspension and nebulizer-based ICP-MS. The data show that the particles remained intact by the ablation process as confirmed by transmission electron microscopy. Moreover, the optimized method was applied to CeO2 NPs that are highly relevant for (eco-)toxicological research but, unlike Ag NPs, are multi-shaped and have a broad particle size distribution. Upon analyzing the particle size distribution of CeO2 NPs in cryosections of rat spleen, CeO2 NPs were found to remain unchanged in size over 3 h, 3 d, and 3 weeks post-intratracheal instillation, with the fraction of smaller particles reaching the spleen first. Overall, LA-spICP-MS combined with a calibration based on dissolved metal standards is a powerful tool to simultaneously localize and size NPs in histological sections in the absence of particle standards.