Microparticle Formation Research Articles

Green Processing of Ilex guayusa: Antioxidant Concentration and Caffeine Reduction Using Encapsulation by Supercritical Antisolvent Process

This study investigated the valorization of Ilex guayusa leaves by producing a low-caffeine, antioxidant-rich product through the supercritical antisolvent extraction (SAE) process. The objective was to concentrate the antioxidants while selectively reducing the caffeine. The SAE treatments were conducted using an ethanolic extract of guayusa leaves under varying pressure (80 bar–150 bar) and temperature (35–45 °C) conditions to improve the recovery of chlorogenic acid (CGA) and caffeine fractionation. The co-precipitation of antioxidants with polyvinylpyrrolidone (PVP) (ratio 1:1–1:2 mass/mass) as an encapsulant was also studied. The SAE precipitates were analyzed for their recovery yield, CGA and caffeine contents, antioxidant activity, and total phenols. Based on the statistical analysis, the optimal conditions for the SAE were 120 bar and 45 °C. Under these conditions, the CGA concentration increased from 43.02 mg/g extract to 237 mg/g precipitate, while the caffeine was reduced to less than 1% mass. Co-precipitation with PVP improved the recovery yield by more than two times than the SAE alone while maintaining the caffeine content below 1% mass. Additionally, the co-precipitation with PVP facilitated the formation of spherical microparticles, indicating successful encapsulation of the bioactive compounds, with an IC50 of 0.51 ± 0.01 mg/mL for DPPH and 0.18 ± 0.01 mg/mL for ABTS. These results highlight the effectiveness of the SAE co-precipitation process in developing low-caffeine functional ingredients with potential food and pharmaceutical applications.

Innovative Microencapsulation of Polymyxin B for Enhanced Antimicrobial Efficacy via Coated Spray Drying.

This study aims to develop an innovative microencapsulation method for coated Polymyxin B, utilizing various polysaccharides such as hydroxypropyl β-cyclodextrin, alginate, and chitosan, implemented through a three-fluid nozzle (3FN) spray drying process. High-performance liquid chromatography (HPLC) analysis revealed that formulations with a high ratio of sugar cage, hydroxypropyl β-cyclodextrin (HPβCD), and sodium alginate (coded as ALGHCDHPLPM) resulted in a notable 16-fold increase in Polymyxin B recovery compared to chitosan microparticles. Morphological assessments using fluorescence labeling confirmed successful microparticle formation with core/shell structures. Alginate-based formulations exhibited distinct layers, while chitosan formulations showed uniform fluorescence throughout the microparticles. Focused beam reflectance and histograms from fluorescence microscopic measurements provided insights into physical size analysis, indicating consistent sizes of 6.8 ± 1.2 μm. Fourier-transform infrared (FTIR) spectra unveiled hydrogen bonding between Polymyxin B and other components within the microparticle structures. The drug release study showed sodium alginate's sustained release capability, reaching 26 ± 3% compared to 94 ± 3% from the free solution at the 24 h time point. Furthermore, the antimicrobial properties of the prepared microparticles against two Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, were investigated. The influence of various key excipients on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values was evaluated. Results demonstrated effective bactericidal effects of ALGHCDHPLPM against both E. coli and P. aeruginosa. Additionally, the antibiofilm assay highlighted the potential efficacy of ALGHCDHPLPM against the biofilm viability of E. coli and P. aeruginosa, with concentrations ranging from 3.9 to 500 μg/m. This signifies a significant advancement in antimicrobial drug delivery systems, promising improved precision and efficacy in combating bacterial infections.

In vitro assessment of NaF/Chit supramolecular complex: Colloidal stability, antibacterial activity and enamel protection against S. mutans biofilm

ObjectivesThis study assessed the effect of NaF/Chit suspensions on enamel and on S. mutans biofilm, simulating application of a mouthrinse. MethodsThe NaF/Chit particle suspensions were prepared at molar ratio [NaF]/Chitmon]≈0.68 at nominal concentrations of 0.2 % and 0.05 % NaF and characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering and zeta potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. The S. mutans biofilm was formed for 7 days on eighty human enamel blocks that were divided into eight groups (n = 10/group): i) 0.05 % NaF solution; ii) 0.31 % Chit solution; iii) NaF/Chit(R=0.68) suspension at 0.05 % NaF; iv) 1.0 % HAc solution (Control); v) 0.2 % NaF solution; vi) 1.25 % Chit solution; vii) NaF/Chit(R=0.68) suspension at 0.2 % NaF; viii) 0.12 % chlorhexidine digluconate. The substances were applied daily for 90 s. S. mutans cell counts (CFU/mL) were performed, and the Knoop microhardness (KHN) of enamel samples were measured before and after biofilm formation. The KHN and CFU/mL data were analyzed by repeated measure ANOVA and Tukey's test (α = 0.05). ResultsInteractions between NaF and Chit were evidenced in solid state by FTIR spectra. The NaF/Chit complexes showed spontaneous microparticle formation and colloidal stability. The MIC and MBC ranged from 0.65 to 1.31 mg/mL. The NaF/Chit(R=0.68) suspension at 0.2 %NaF Group showed lower CFU/mL values than other groups. The NaF/Chit(R=0.68) suspensions Groups had the highest KHN values after biofilm formation. ConclusionsThe NaF/Chit(R=0.68) complexes exhibited an antibacterial effect against S. mutans biofilm and reduced the enamel hardness loss. Clinical significanceThe NaF/Chit(R=0.68) suspensions showed potential to be used as a mouthrinse for caries prevention.

Palmitic acid-mediated modulation of crystallization dynamics in amylose microparticle formation: From spherical to macaron and disc shapes

Here, we investigated the complexation of short chain amylose (SCAs) and palmitic acid (PA), serving as polymeric building blocks that alter the selectivity and directionality of particle growth. This alteration affects the shape anisotropy of the particles, broadening their applications due to the increased surface area. By modifying the concentration of PA, we were able to make spherical, macaron, and disc-shaped particles, demonstrating that PA acts as a structure-directing agent. We further illustrated the lateral and longitudinal stacking kinetics between PA-SCA inclusion complexes during self-assembly, leading to anisotropy. Transmission electron microscope (TEM) and scanning electron microscope (SEM) revealed the structural difference between the initial and final morphologies of palmitic acid-short chain amylose particles (PA-SCAPs) compared to those of short-chain amylose particle (SCAPs). The presence of PA-SCA inclusion complex in the anisotropic particles was confirmed using nuclear magnetic resonance (NMR) and powder x-ray diffraction (XRD) analysis.

Anti-Platelet Activity of Sea Buckthorn Seeds and Its Relationship with Thermal Processing.

Sea buckthorn (Hippophae rhamnoides L.) is a tree or shrub with small, orange berries. Sea buckthorn seeds have shown many properties beneficial to human health, including antioxidant, anti-hypertensive, anti-hyperlipidemic, and retinoprotective activities. Seeds, as a component of food, are often exposed to high temperatures, which can increase or decrease their biological activity. In our previous study, we showed that both raw and roasted sea buckthorn seeds had significant antioxidant activity, which was measured in human plasma in vitro. In this paper, we evaluated the effect of extracts from raw and roasted sea buckthorn seeds on several parameters of hemostasis in vitro, including thrombus formation in full blood (measured by the Total Thrombus formation Analysis System-T-TAS), blood platelet activation (based on the exposition of P-selectin, the active form of GPIIb/IIIa on their surface and platelet-derived microparticles formation), aggregation (measured with impedance aggregometry), adhesion to fibrinogen and collagen, arachidonic acid metabolism in washed platelets stimulated by thrombin, and COX-1 activity. We also measured the levels of free 8-isoprostane in plasma and the total non-enzymatic antioxidant status of plasma. The extract from roasted seeds (50 µg/mL) significantly prolonged the time of occlusion measured by T-TAS-the AUC10 (area under the curve) value was decreased by approximately 18%. Both extracts decreased the exposition of the active form of GPIIb/IIIa on the surface of platelets activated with 10 μM ADP (by 38.4-62.2%) and 20 μM ADP (by 39.7-51.3%). Moreover, the extract from raw seeds decreased the exposition of P-selectin on the surface of platelets stimulated with 20 μM ADP (by 31.2-34.9%). The adhesion of thrombin-stimulated platelets to fibrinogen and collagen was inhibited only by the extract from roasted sea buckthorn seeds (by 20-30%). Moreover, the extract from raw seeds inhibited the level of TBARS (thiobarbituric acid-reactive substances, an indicator of enzymatic peroxidation of arachidonic acid) in washed platelets stimulated with thrombin; the activity of COX-1 was inhibited by both extracts, although the effect of the extract from raw seeds was stronger. These results indicate that sea buckthorn seeds have anti-platelet activity that is not decreased by thermal processing, but more research is needed to determine which exact chemical compounds and mechanisms are responsible for this phenomenon.

Embedding Bioprinting of Low Viscous, Photopolymerizable Blood-Based Bioinks in a Crystal Self-Healing Transparent Supporting Bath.

Protein-based hydrogels have great potential to be used as bioinks for biofabrication-driven tissue regeneration strategies due to their innate bioactivity. Nevertheless, their use as bioinks in conventional 3D bioprinting is impaired due to their intrinsic low viscosity. Using embedding bioprinting, a liquid bioink is printed within a support that physically holds the patterned filament. Inspired by the recognized microencapsulation technique complex coacervation, crystal self-healing embedding bioprinting (CLADDING) is introduced based on a highly transparent crystal supporting bath. The suitability of distinct classes of gelatins is evaluated (i.e., molecular weight distribution, isoelectric point, and ionic content), as well as the formation of gelatin-gum arabic microparticles as a function of pH, temperature, solvent, and mass ratios. Characterizing and controlling this parametric window resulted in high yields of support bath with ideal self-healing properties for interaction with protein-based bioinks. This support bath achieved transparency, which boosted light permeation within the bath. Bioprinted constructs fully composed of platelet lysates encapsulating a co-culture of human mesenchymal stromal cells and endothelial cells are obtained, demonstrating a high-dense cellular network with excellent cell viability and stability over a month. CLADDING broadens the spectrum of photocrosslinkable materials with extremely low viscosity that can now be bioprinted with sensitive cells without any additional support.

Effects of carbohydrate binding module of pullulanase type I on the raw starch rearrangement by enhancing the hydrolysis activity

Starch, a versatile ingredient used in various industries, often requires modification for improvements in its physicochemical and functional properties for utilization. Although carbohydrate-binding modules (CBMs) are non-catalytic domains that recognize and bind to the substrate without any enzymatic activity, CBMs are commonly found in the starch-modifying enzyme, pullulanase (PulA). Herein, we identified two PulAs from Deinococcus radiodurans and Deinococcus wulumuqiensis that differed in activity only by CBM composition. Structural comparison analysis showed unique substrate-binding coordination of CBMb1. The analysis with a deletion mutant (ΔCBMb1-DrPulA), and a chimeric mutant (CBMb1-DwPulA) revealed that CBMb1 can improve amylopectin but not pullulan hydrolysis. Moreover, CBMb1 introduction increased the hydrolysis activity of raw waxy corn starch by 60% which leads to the formation of distinct α-glucan microparticles (GMP). GMP produced using CBMb1-DwPulA exhibited B-type crystallinity, similar to that produced by DwPulA. However, a relatively high proportion of short-length maltooligosaccharides was observed in the GMP produced by CBMb1-DwPulA compared with that produced by DwPulA. This contributed to the formation of smaller particles, high colloidal dispersion stability, and increased the absolute value of the zeta potential. Altogether, our findings showed that Deinococcus sp.-derived CBMs can be used to customize GMPs by changing the debranching pattern.

Encapsulated Mn-Saturated Lactoferrin as a Safe Source of Manganese Ions for Restoring Probiotic Lactobacillus plantarum.

The growth of Lactobacillus plantarum, a member of the Lactobacillus genus, which plays a crucial role in the bacterial microbiome of the gut, is significantly influenced by manganese ions. They can be safely delivered to the intestines by exploiting the chelating abilities of lactoferrin. The aim of this work was to encapsulate lactoferrin saturated with manganese ions (MnLf) in a system based on the Eudragit® RS polymer to protect protein from degradation and manganese release in the gastric environment. The entrapment efficiency was satisfactory, reaching about 95%, and most importantly, manganese ions were not released during microparticles (MPs) formation. The release profile of the protein from the freshly prepared MPs was sustained, with less than 15% of the protein released within the first hour. To achieve similar protein release efficiency, freeze-drying was carried out in the presence of 10% (w/v) mannitol as a cryoprotectant for MPs frozen at -20 °C. MPs with encapsulated MnLf exhibited prebiotic activity towards Lactobacillus plantarum. More importantly, the presence of equivalent levels of manganese ions in free form in the medium, as well as chelating by lactoferrin encapsulated in MPs, had a similar impact on stimulating bacterial growth. This indicates that the bioavailability of manganese ions in our prepared system is very good.

Procoagulant activity of red blood cell microparticles in stored packed red blood cell units and its relation to ABO blood grouping

BackgroundThroughout the storage of blood, the red cells undergo alterations known as “storage lesions,” which involve shape changes and the formation of microparticles (MPs). Studies of the formation of red cell microparticles (RMPs) emphasize the prospective application of RMPs as a quality control measure in the preparation and storage of blood components in the future. In the present study, twenty packed RBC units in citrate phosphate dextrose adenine-1 (CPDA1) were collected from volunteers and stored for 35 days. Over 35 days of storage, samples were collected at six distinct time points weekly and evaluated for the presence of RMPs. MPs were separated by the ultracentrifugation method. Electron microscopy was used to characterize the morphology and size of the isolated microparticles, and flow cytometry was performed to determine the percentage of RMPs that expressed glycophorin A (CD235a) and Annexin V antigens. RMPs' procoagulant activity (PCA) was assessed using a plasma recalcification test. RMP concentration in accordance with ABO blood grouping was assessed by using various types of donated blood groups.ResultsRMPs progressively increased over storage. The procoagulant activity (PCA) exhibited a significant increase during storage, as evidenced by a shorter plasma recalcification time (P value = 0.001). A significant negative correlation (P value = 0.001) between plasma recalcification time and Annexin V-positive microparticles, as well as a dual-positive Annexin V/CD235a population, was identified, indicating a strong correlation between the direct quantitative assay by flowcytometry and the functional assay through the PCA.ConclusionRMPs increase on storage with increased PCA. Finding ways to reduce these microparticles in packed RBC units is crucial for reducing the risk of transfusion-related coagulopathy.

Cancer-Associated Thrombosis: Pathophysiology, Laboratory Assessment, and Current Guidelines.

Dysregulated hemostasis in cancer patients is associated with various clinical conditions, from thromboembolic complications to disseminated intravascular coagulation. Despite the well-established association between cancer and thromboembolic complications, the mechanisms involved are not completely elucidated. There are several predisposing factors in cancer for increased thrombus generation, such as immobilization and chemotherapy. The term cancer-associated thrombosis (CAT) has been introduced to describe the close bidirectional relationship between cancer and thromboembolic events. Conventional coagulation tests (PT/aPTT) are more accurate in detecting a hypocoagulable rather than a hypercoagulable state; thus, their contribution to CAT management is limited. Traditionally, D-dimer levels have been the most common laboratory study for the evaluation of thrombotic risk. However, D-dimer levels only display a snapshot of the coagulation cascade, and they cannot provide a dynamic evaluation of evolving clot formation. Non-conventional assays, such as viscoelastic methods and microparticle formation are promising tools for the identification of patients at risk for developing CAT. Recent guidelines from the American Society of Clinical Oncology counsel against the estimation of thrombotic risk through a single test and recommend the use of scoring systems that take into account several risk factors. The present review outlines the current insights into the pathophysiological mechanisms of CAT and provides a comprehensive review of the latest advances in the laboratory assessment of CAT and the recent guidelines for the management of patients at risk for developing thromboembolic complications.

Platelet phosphatidylserine exposure and microparticle production as health bioindicators in marine mammals.

In human medicine, various pathologies, including decompression sickness, thrombocytopenia, and rheumatoid arthritis, have been linked to changes in cellular microparticles (MP) formation, particularly platelet microparticles (PMP). Similar disorders in marine mammals might be attributed to anthropogenic threats or illnesses, potentially impacting blood PMP levels. Thus, detecting platelet phosphatidylserine (PS) exposure and PMP formation could serve as a crucial diagnostic and monitoring approach for these conditions in marine mammals. Our group has developed a methodology to assess real-time PS exposure and PMP formation specifically tailored for marine mammals. This method, pioneered in species such as bottlenose dolphins, beluga whales, walruses, and California sea lions, represents a novel approach with significant implications for both clinical assessment and further research into platelet function in these animals. The adapted methodology for evaluating PS exposure and PMP formation in marine mammals has yielded promising results. By applying this approach, we have observed significant correlations between alterations in PMP levels and specific pathologies or environmental factors. These findings underscore the potential of platelet function assessment as a diagnostic and monitoring tool in marine mammal health. The successful adaptation and application of this methodology in marine mammals highlight its utility for understanding and managing health concerns in these animals.

Morphostructural, Chemical and Genetic Features of Native Gold in Brown Coals from the Yerkovetsky Deposit, Far East Russia

We studied the morphostructural features and chemical composition of micron and submicron particles of native gold from brown coals and overcoal sediments of the Yerkovetsky deposit (Zeya-Bureya sedimentary basin, Far East Russia). The samples of coal and host rocks in the form of thin sections, as well as coal particles and grains of native gold obtained during the process of dispersion and the fractionation of loose and crushed samples divided according to size and density, were analyzed using scanning electron microscopy in combination with X-ray microanalysis, involving various visualization modes. It was revealed that native gold is syngenetic with the mineralization of brown coals, and microphases dispersed in the minerals of overcoal loose and sandy-clay sediments were the source of native gold. In coal, gold is accumulated at the stages of formation (alluvial and eolian, including terrigenous and ionogenic subtypes) and the diagenesis of coal deposits (ground-infiltration subtype). A significant part of the mineralization process of coals and the formation of microparticles of native gold was contributed to by the descending water infiltration of polycomponent colloid solutions. During the dehydration of hydroxysiliconized iron-based hydrogels, mineral phases have an unstable composition and floccular structure and contain submicron gold particles. The coatings of all gold microparticles have identical origin and composition. Coal beds that border host rocks are an open system with a constant inflow of the substance, which leads to the gradual formation of polycomponent aggregated particles in micro cavities. Part of the gold in coals occurs as sulfur-bearing complexes dissolved in pore water. The key factor in the migration and deposition of gold in coals is the inorganic substances involved in the processes of coal mineralization. Organic substances play a more passive role and have medium-forming, fractionating (colloid, molecular, and ionic sieves), and accumulation functions.

Supramolecular structure design of block copolymer by combining 3D confined self-assembly with selective disassembly

3D confined self-assembly (3D-CSA) of block copolymer (BCP) is a significant way to generate polymer microparticles with ordered internal suprastructures. Subsequent selective disassembly of the suprastructures can lead to the formation of unique anisotropic micelles or mesoporous microparticles, which can be hardly achieved by solution self-assembly or disassembly of bulk suprastructures. These micelles or mesoporous microparticles and their composites with functional molecules/nanoparticles have great potential in interfacial compatibilization, catalysis, controlled drug delivery and other fields, thus arising increasing attention in recent years. In this review, we first briefly discuss the influence factors, particularly, packing parameter and interfacial selectivity on morphology of BCP assemblies under 3D confinement. Then, we emphasize recent progress in selective disassembly of BCP microparticles into anisotropic micelles or mesoporous microparticles and derived composites. Finally, the outlook and challenges of this direction are highlighted.

Microstructure change and functional characteristic promotion: the structural manipulation of soy protein microparticles through pH

SummaryIn this work, soy protein isolates (SPIs) were subjected to microparticulation, turning soy protein ingredients into microparticles with improved thermal stability which could be used in high‐protein foods. The pH is a critical determinant in microparticulation. Our work is mainly to investigate the effect of pH on the formation and properties of protein microparticles. To clarify the effects of pH conditions on the properties of the resulting particles, microparticulation was performed at different pH conditions (7.0, 6.0 and 5.0). Aggregation behaviours described by the parameters calculated from the protein dispersion viscosity combined with the observation of the morphology change were used to analyse the particle formation process. For the microparticles prepared at pH 5.0, soy proteins were more inclined to aggregate into clusters on a micro‐scale which had a flexible conformation. After spray drying, This powder could be easily dispersed in water, creating a dispersion with a protein concentration of 10 wt%. At this concentration, the thermal gelation capacity of the proteins was observed to decrease. Conversely, the tendency of protein aggregation was largely restricted when soy protein microparticulation was carried out at pH 7.0. As these soy protein particles in nano‐scale were dispersed in water, a decrease rather than an increase was recorded in the viscosity of this dispersion after it was heated, suggesting that these particles had improved thermal stability. This work has demonstrated that implementing appropriate pH conditions during microparticulation can prepare soy protein particles with different sizes and rheological properties, which might meet the demands of various food processing.

Microencapsulation of pyriproxyfen using the particles from gas‐saturated solutions process as a controlled‐release system

AbstractThe purpose of this investigation was to determine whether pyriproxyfen (PPF), a synthetic juvenile hormone analog (JHA), could be encapsulated in supercritical carbon dioxide (scCO2) using the process particles from the gas‐saturated solutions (PGSS) for a controlled‐release system. The PGSS process represents a promising two‐step production system especially suited for the encapsulation and controlled‐release system (CRS). In contrast to traditional encapsulation methods that often involve the use of harsh organic solvents or high temperatures, the PGSS process offers a gentler approach employing scCO2 as an alternative. The solubility of scCO2 in polymer (poly‐ϵ‐caprolactone [PCL]) allowed for the formation of PPF microparticles, and the particle size distribution could be controlled by adjustment of operating pressure and temperature. The obtained particles had a mean particle size of 73.6 ± 2 μm and encapsulation efficiency of 78.8 ± 9% at 60°C and 10 MPa. Furthermore, the in vitro dissolution profiles of PPF–PCL particles showed a low‐level release pattern (42.5 ± 5 ppb/d) in water, followed by zero‐order kinetics indicating a high‐performance CRS. Finally, the in vivo bioassay using microparticles treated water exhibited 95%–100% emergence inhibition of mosquitoes, suggesting the effectiveness of PPF–PCL particles as a mosquito control agent.

Formation of hollow solid lipid microparticles from natural waxes using supercritical carbon dioxide

AbstractIn this study, the potential of natural waxes, namely, candelilla wax (CLW) and carnauba wax (CW), was explored to form extra‐hard shell hollow solid lipid particles using a particle formation process based on supercritical fluid technology. Melting behavior and volumetric expansion of CLW and CW in pressurized CO2 were investigated as a function of pressure. The melting point of waxes decreased linearly with increasing pressures up to a certain level; then stayed constant regardless of further elevated pressures. The highest melting point depressions of 13.0% and 8.3% were observed for CLW and CW at 140 and 130 bar CO2 pressure, respectively. A positive correlation between the melting point depression and volumetric expansion was observed for both waxes. The volumetric expansion of waxes increased with increasing pressures within the linear range of the melting curves. The highest volumetric expansion was achieved at 140 bar/68°C and 130 bar/85°C for CLW (7.1%) and CW (8.5%), respectively. Hollow solid lipid particles with smooth surfaces were obtained from both CLW and CW. There was no difference between the melting behavior of the original waxes and their particles. Increasing SC‐CO2 pressure decreased the particle size and inner volume of the hollow particles. D[4,3] of CLW ranged between 9.3 and 25.4 μm, whereas it ranged between 8.7 and 34.2 μm for CW. CLW and CW were found to be suitable high‐melting lipids to form hollow solid lipid particles via SC‐CO2‐assisted particle formation process to develop hollow solid lipid particles with an extra‐hard protective shell.

Impact of polymeric stabilizers on the transformation and sustainable recovery of silver microstructures from spent button batteries

This paper presents a simple, rapid, highly efficient, and environmentally friendly technique for recovering silver microstructures from spent button batteries. The technique exploits the reducing ability of H2O2 to convert silver sources into high-purity silver at the microscopic scale. The influence of polymeric stabilizers (PVP and PVA) on the formation of silver microstructures was elucidated. The results revealed that polymeric stabilizers play a crucial role in controlling the growth of silver particles at the microscopic level. Specifically, PVP affords a homogeneous silver microplate, whereas PVA facilitates the formation of isotropic spherical microparticles. Additionally, the effect of the molecular weight (Mw) of the stabilizers on the silver particles was examined. The Mw of PVP significantly impacts its anti-aggregation properties. Similarly, the Mw of PVA affects the formation of silver microstructures. The high purity of the recovered silver microstructures was verified by EDX and XRD. Finally, the optimal recovery conditions involving 360,000 and 150,000 g/mol for PVP and PVA, respectively with 0.5 % w/v) were implemented to recover silver from button batteries. These battery residues were successfully transformed into highly pure silver microplates and microspheres using those respective polymeric stabilizers. The developed synthesis approach will facilitate the sustainable recovery of silver from spent button batteries, addressing the environmental, and resource challenges associated with battery waste.

Oscillatory flow driven microdroplet breakup dynamics and microparticle formation in LMPA-water two phase flow system

This study presents a mathematical modeling and numerical investigation of oscillatory flow induced microdroplet breakup in low melting point alloy (LMPA)-in-water two-phase flow system in a microchannel. The effects of perturbation flow Weber number, and oscillating frequencies on the droplet breakup dynamics have been elucidated. Lowering the wall temperature will accelerate the solidification process of LMPA droplets, giving rise to the rapid formation of ultra-small particles with size down to 1 micron in less than 3 ms. The versatile approach combines oscillatory flow dominated droplet breakup process and phase change process, leading to the formation of LMPA microparticles with monodispersed size distribution and well-tailored properties by using a straight microchannel, which obviates the need for sophisticated design and complex fabrication process of microdevices. This work will provide a strategy to manipulating LMPA droplet size and structure for the massive production of ultra-small LMPA microparticles via a facile control over the flow conditions in the two-phase flow in a microfluidic system. It will open up for a diversity of applications of LMPA microparticles in various fields such as energy storage and thermal management.

Compositional aspect and mechanism of surface formation of spray-dried microparticles with surface-active rice protein hydrolysates

Flavourzyme enzymatically hydrolyzed rice protein isolate to different degrees of hydrolysis (DH, 2, 6, and 10%) to stabilize formulated linseed oil emulsions with different protein concentrations (0.5, 1.0, and 1.5%). The emulsions were spray dried, and the microstructure, surface composition by X-ray photoelectron spectroscopy (XPS), and oxidative stability of the resultant microparticles were investigated. The physicochemical properties of powders were also evaluated. DH and protein concentration did not affect solubility, hygroscopicity, wetting time, and particle size. However, a strong and positive correlation was found between DH and oxidative stability. The lowest peroxide value (2.48–1.99 meq/kg oil) was found from the powder formulated with protein hydrolysate (DH 10%) and 1.5% of protein concentration during the entire storage study. Fluorescence optical microscopy and atomic force microscopies also allowed identifying the effects of these variables on oxidative stability. Through XPS analysis, it was possible to observe that higher DH favored the surface accumulation of proteins at the powder surface. The protein content on the particle surface (9.8%) was overrepresented compared with the bulk composition (1.5%). These results showed that the degree of hydrolysis exerted an influence on the distribution of components and the percentage of protein on the powder surface.

The effect of thermal modification of turbostratic carbon on its fractal structure

Fractal structure of porous carbon materials (PCMs) obtained by thermal modification under different regimes was investigated using the method of low-temperature porometry. It was established that at modification temperatures of 300 and 600°C, materials with a developed microporous structure are formed, the surface fractal dimension of which is 2.6. At modification temperatures of 400 and 500°C, the value of the fractal dimension of the surface decreases to a value of 2.22, which indicates the formation of an almost smooth surface due to the intensive removal of carbon atoms from the near-surface layers of the material particles, a decrease in the number of micropores with their transition into mesopores, unification of small carbon clusters into larger ones and the formation of microparticles of non-porous carbon material.