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Self-healing approaches are increasingly being explored in various fields as a potential method to recover damaged material properties. By self-recovering without external intervention, self-healing techniques emerge as a potential solution to arrest or prevent the development of large strains problems in soils (e.g., landslides) and other ground effects that influence the serviceability of structures (e.g., differential settlement). In this study, a microcapsule-based self-healing sand was developed, and its performance during mixing and compaction, shearing, and recovery of shear strength was demonstrated. The cargo used for sand improvement, a hardening oil, tung oil, was encapsulated in calcium alginate capsules by the ionic gelation method. The surface properties, internal structure, thermal stability and molecular structure of the capsules were evaluated by advanced material characterization techniques. The survivability of capsules during mixing and compaction was assessed by measuring the content of tung oil released into the sand, while their influence on sand shear strength and its recovery was assessed with shear box tests. The results showed that the capsules could rupture due to movement of the sand particles, releasing the tung oil cargo, leading to its hardening and minimizing its strain-softening response and enhancing up to 76% of the sand shear strength (at a normal stress of 10 kPa and capsules content of 4%). This study demonstrates the potential of a capsules-based self-healing system to provide 'smart' autonomous soil strength recovery and thus with potential to actively control the large strain behavior of soils. [ABSTRACT FROM AUTHOR]

Microencapsulation technology is a versatile approach that offers effective protection for core materials while also solving issues such as leakage and interface bonding. In this study, a simple yet efficient method for producing multifunctional fabric coatings has been proposed by utilizing chitosan/silica hybrid microcapsules. The synthesis of the microcapsules was achieved through a combination of the single condensation method and the sol-gel method. These microcapsules were specifically designed to encapsulate octadecane and paraffin. The microcapsules were structured with a core-shell configuration, and the shell was functionalized with both fluoroalkyl silane (FAS) and choline phosphate (CP) grafts. The resulting microcapsules were added to silicone resins to produce multifunctional fabric coatings. The desired coatings improved the hydrophilic and hydrophobic properties of the fabrics, with a hydrophilic side contact angle of less than 10 ° and a hydrophobic side contact angle of up to 156 °. In addition, compared with untreated fabrics, coated fabrics can achieve a temperature difference of over 6 °C, demonstrating certain thermal insulation properties. Moreover, the coated fabric exhibits excellent antibacterial properties, with an inhibition rate of over 98% against Escherichia coli and Staphylococcus aureus. The proposed method provides a promising solution for developing advanced multifunctional fabrics with enhanced properties. [ABSTRACT FROM AUTHOR]

In this work, electrodeposited Ni-Co self-healing nanostructure coatings have been synthesized by utilizing a novel polyureaformaldehyde/SiO2 (PUF/SiO2) hybrid shell with a core of linseed oil. The synthesis of the coating was accomplished by electrodeposition on a carbon steel substrate, using saccharin to refine the crystalline size in the coating. Ni-Co nanostructure coating with and without capsules was then characterized by scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), x-ray diffraction (XRD), and laser-induced breakdown spectroscopy (LIBS). The anti-corrosion performance of the coating was evaluated by electrochemical testing methods such as open-circuit potential (OCP), linear polarization (LP), electrochemical impedance spectroscopy (EIS), and immersion testing per ASTM G31-72. SEM and XRD results confirm the presence of capsules in the coating and formation of nanocrystalline and single-phase solid solution of fcc crystalline structure. The corrosion analysis indicated that a Ni-Co coating with a higher amount of capsules in the plating bath resulted in enhanced corrosion resistance and better performance in the immersion test. This may be due to the presence of capsules on the surface of the coating and release of linseed oil during the corrosion test. [ABSTRACT FROM AUTHOR]

As a significant method to inhibit metal corrosion by blocking the diffusion of corrosive mediums to the metal surface, the anticorrosion coating with a self-healing function can actively repair a damaged structure and improve the anticorrosion performance to better meet actual needs. In this study, "external aid" and "intrinsic triggering" self-healing coatings have been introduced in detail, including the preparation method, healing mechanism and practical applications. The healing of "external aid" is based on the addition components such as microcapsules containing healing agents and functional nanoparticles, whose ability of self-healing shows the independence with the coating resin. But the finitely additive amount may limit the sustainable use of "external aid" components, and the abundant fillers also change the basic physical properties of the coating. On the contrary, the "intrinsic triggering" resins can form the cover layer in the defects owing to the physical or chemical reactions between the polymer chains, along with the unlimited cycles theoretically. By contrast, the small defects or gaps can be repaired gradually through chain reactions, but the large areas of damage may need the quick release of healing additives in "external aid" coating. In this review, the advances of two kinds of self-healing coatings were analyzed to discuss the advantages and disadvantages of various healing technologies, and the challenges of development and prospects were also forecasted to provide useful ideas. [ABSTRACT FROM AUTHOR]

In this study, a microcapsule resin grafted with amidoxime group was prepared by phase transformation method, and the microcapsule resin was loaded with zinc as an antibacterial agent. The final preparation of Zn@AO-PAN PMR enhanced the antibacterial ability of Zn@AO-PAN PMR in real seawater based on its good uranium adsorption performance. The theoretical maximum adsorption capacity of Zn@AO-PAN PMR in real seawater could reach 50.30 mg/g. At the same time, the loading of Zn don't lose the adsorption capacity of the resin for U(VI). The antibacterial mechanism of Zn@AO-PAN PMR was explored using MAD. [ABSTRACT FROM AUTHOR]

The development of ultrasound-responsive microcapsule structures has resulted in several spatiotemporally controlled drug delivery systems for macromolecular cargoes, including proteins, nucleic acids, and even cells for biomedical applications. However, utilizing microcapsules to transport small molecular cargoes remains a challenge, because the leakage of drugs before ultrasound irradiation might cause side effects such as the undesired toxicity and the decrease of effective drug concentration at the target site. Herein, we present a novel strategy to tackle these shortcomings by employing nanodrugs which refers to nanoparticles coated with small molecule drugs. We showed that the drug leakage was prevented when encapsulating the nanodrug in microcapsules. Moreover, the fabricated drug delivery system was responsive not only to unfocused high-intensity ultrasound but also to the clinically relevant high-intensity focused ultrasound. Finally, as a proof of concept, we showed that the antibacterial activity of the nanodrug@Microcapsules could be activated by applying ultrasound in situ. These results may provide new insights into the development of ultrasound triggered small molecule drug delivery assisted by metallic nanoparticles. [ABSTRACT FROM AUTHOR]

The incorporation of aryl substituents at the meso-positions of calix[4]pyrrole (C4P) scaffolds produces aryl-extended (AE) and super-aryl-extended (SAE) calix[4]pyrroles. The cone conformation of the all-α isomers of “multi-wall” AE-C4Ps and SAE-C4Ps displays deep aromatic clefts or cavities. In particular, “four-wall” receptors feature an aromatic polar cavity closed at one end with four convergent pyrrole rings and fully open at the opposite end. This makes AE- and SAE-C4P scaffolds effective receptors for the molecular recognition of negatively charged ions and neutral guest molecules with donor–acceptor and hydrogen bonding motifs. In addition, adequately functionalized all-α isomers of multi wall AE- and SAE-C4P scaffolds self-assemble into uni-molecular and supra-molecular aggregates displaying capsular and cage-like structures. The self-assembly process requires the presence of template ions or molecules that lock the C4P cone conformation and complementing the inner polar functions and volumes of their cavities. We envisioned performing an in-depth revision of AE- and SAE-C4P scaffolds owing to their importance in different domains such as supramolecular chemistry, biology, material sciences and pharmaceutical chemistry. Herewith, besides the synthetic details on the elaboration of their structures, we also draw attention to their diverse applications. The organization of this review is mainly based on the number of “walls” present in the AE-C4P derivatives and their structural modifications. The sections are further divided based on the C4P functions and applications. The authors are convinced that this review will be of interest to researchers working in the general area of supramolecular chemistry as well as those involved in the study of the binding properties and applications of C4P derivatives. [ABSTRACT FROM AUTHOR]

The self-healing of resin mineral composites by adding microcapsules has been widely used. However, it is difficult to determine the proportion of microcapsule to obtain the optimal self-healing performance because of the contradictory characteristics between the self-healing efficiency and elastic modulus of composites. To address this problem, this study proposes a novel method to optimize the proportion of microcapsule under the constraints of engineering design requirements. The results show that (1) the damage evolution of self-healing resin mineral composites with microcapsule can be divided into four processes: damage accumulation, bond interface crack appearing, matrix crack appearing and fracture surface formation. (2) The position of aggregate has little effect on the mechanical properties of the overall composites structure, but it plays a decisive role in the distribution and size of cracks. (3) The relationship between the self-healing efficiency and the proportion of microcapsule is a nonlinear positive correlation, but the elastic modulus is a nonlinear negative correlation with the proportion of microcapsule. (4) The optimization results show that the optimal microcapsule proportion of a resin mineral composite machine tool is 1.68 %; at this time the mechanical properties of the material are reduced by 2.9 % and the self-healing efficiency is 25.38 %. The results provide a reference for the damage performance research and engineering design of microcapsule self-healing composites. [ABSTRACT FROM AUTHOR]

The present paper reports a continuous microfluidic approach for the preparation of microcapsules (MCs), by interfacial polymerization, with a polyurea/polyurethane (PUa/PU) shell containing isophorone diisocyanate (IPDI). The microfluidic system enables the formation of a monodisperse oil-in-water (O/W) emulsion by a separate flow of the reagents along the tubing system, which posteriorly meet at a cross-junction, resulting in the precise formation of one emulsion droplet at a time. The developed MCs are intended to be part of a new monocomponent, autoreactive and ecological adhesive, as cross-linking agents. Critical operational parameters in the microfluidic process were investigated, namely the flow rate of the emulsion phases, the cross-junction's configuration and its correlation with the MCs' morphology, average diameter, size distribution and amount of encapsulated isocyanate. The advances achieved in the current study represent a contribution to the development of new sustainable and eco-friendly products, where the employment of monodisperse MCs is an advantage. [ABSTRACT FROM AUTHOR]

The work is devoted to computer studies of the structural and physical properties of such self-organizing structures as peptide nanotubes (PNT) based on diphenylalanine (FF) dipeptide with different initial isomers of the left (L-FF) and right (D-FF) chiralities of these dipeptides. The structures under study are considered both with empty anhydrous and with internal cavities filled with water molecules. Molecular models of both chiralities are investigated using quantum-chemical DFT and semi-empirical methods, which are in consistent with the known experimental data. To study the effect of nano-sized clusters of water molecules embedded in the inner hydrophilic cavity on the properties of nanotubes (including the changes in their dipole moments and polarizations), as well as the changes in the structure and properties of water clusters themselves (their own dipole moments and polarizations), the surfaces of internal cavities of nanotubes and outer surfaces of water cluster structures for both types of chirality are analyzed. A specially developed method of visual differential analysis of structural features of (bio)macromolecular structures is applied for these studies. The results obtained of a number of physical properties (interacting energies, dipole moments, polarization values) are given for various cases and analyzed in comparison with the known data. These data are necessary for analyzing the interactions of water molecules with hydrophilic parts of nanotube molecules based on FF, such as COO- and NH3 + , since they determine many properties of the structures under study. The data obtained are useful for further analysis of the possible adhesion and capture of medical molecular components by active layers of FF-based PNT, which can be designed for creating capsules for targeted delivery of pharmaceuticals and drugs on their basis. [ABSTRACT FROM AUTHOR]

Coatings are applied on metallic surfaces to provide a dense barrier against the corrosive environment. However, coatings in most cases are vulnerable to damage in the form of internal cracks, which are difficult to detect and repair. One of the most promising types of smart multifunctional coatings is a self-healing coating, which has attracted interest in materials research due to its capability to prevent crack propagation by releasing healing agents at the site of cracks. These self-healing coatings demonstrate autonomic repair for internal cracks as they comprise a coating matrix and nano/microcapsules. Incorporating nano/microcapsules into the coating matrix ensures that the healing agent releases in reaction to propagation of cracks in the coating and then releases the self-healing characteristic to them. This paper aims to provide a perspective of this class of self-healing coatings that incorporate micro/nanocapsules and their synthesis methods. The emulsion method for the synthesis of capsules by organic and inorganic shells is covered as well as the most effective parameters which influence the size of nano/microcapsules. Finally, the incorporation of nano/microcapsules in the metallic and polymeric coating and the possible mechanisms of co-deposition have been presented. [ABSTRACT FROM AUTHOR]

The application of microdrops of an aqueous solution of a mixture of NiSO4 (c 0.4 mol/L) and FeSO4 (c 0.1 mol/L) salts at the surface of a solution of a mixture of NaOH (c 1 mol/L) and NaBH4 (c 0.5 mol/L) has led to rapid hydrolysis of nickel(II) and iron(II) salts and the formation of open vase-like microcapsules with diameter of 1–10 μm and 20–40 nm thick walls of Ni(II) and Fe(III) double hydroxide the microdroplet–solution interface. These microcapsules can be transferred from the solution surface to the surface of the nickel electrode using the vertical elevator technique. The study of the electrochemical properties of such electrodes has shown that they are active electrocatalysts in the oxygen evolution reaction during water electrolysis in an alkaline medium and they are characterized by the overpotential value of 280 mV and Tafel slope of 69.1 mV/dec. [ABSTRACT FROM AUTHOR]

In this study, the pyraclostrobin@polydopamine-polyurea microcapsules (Pyr@PNPMC) with anti-photolysis and sustained-release properties were prepared by interfacial polymerization based on O/W Pickering emulsion templates. The effects of water–oil ratio, stirring speed, temperature, and polydopamine nanoparticles (PDANPs) content on the preparation of microcapsules were systematically investigated. Under this condition, the encapsulation efficiency of microcapsules could reach up to 77.7%. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) images indicated that Pyr@PNPMC were prepared successfully, and the microcapsules were a regular sphere with a large number of PDANPs attached to the dense inner layer. According to the results of sustained-release and anti-photolysis experiments, the release rate of Pyr@PNPMC was slightly faster than that of the pyraclostrobin@polyurea microcapsules (Pyr@MC). Under UV light exposure for 7 h, Pyr@PNPMC still retains 83% of the active ingredient, while for Pyr@MC nearly 75% of the active ingredient had been lost. [ABSTRACT FROM AUTHOR]

A smart bioreactor (HPs-Ag), designed by protein-silver nanoclusters-PNIPAAm, could control the membrane permeability to determine the different molecular weight of materials and the speed of catalysis of enzyme reaction. Studies also showed that the molecular weight cutoff of the HPs-Ag membrane could be continuously turned up from 12 to 70 kDa. The catalytic reaction rate of the ALP loaded bared HPs-Ag by using pNPP as substrates was increased (18.14- and 9.23-fold) with different concentrations of H2O2. [ABSTRACT FROM AUTHOR]

Using microcapsules as the stabilizers of Pickering emulsion can endow the resulted composite capsules with more storage microcavities, producing new functional and structural materials, which have potential application in the preparation of self-healing microcapsules to achieve multiple healing. However, the preparation and wettability of microcapsule-type stabilizers (MTS) have not been systematically researched. Herein, a facile method to prepare MTS containing a liquid healing agent (dicyclopentadiene, DCPD) was proposed, which exhibited excellent emulsifying properties in Pickering emulsion. MTS with adjustable wettability were successfully prepared and used to fabricate Pickering emulsions with different oil phases. It was found that when the mass ratio of the hydrophobic shell monomer reached 100%, MTS possessed the best emulsifying property and the resulted Pickering emulsion could be stably stored for 30 days. Additionally, via solidifying the activity monomers of the oil droplets, composite capsules with multi-storage cells were successfully prepared which confirmed the strong stability of this emulsion and the appropriate wettability of MTS again, as well as pave a new path for the preparation of new architecture microcapsules. We expected that MTS will be found more useful in encapsulation fields, such as self-healing microcapsules, biological medicine, cosmetics, and textile. [ABSTRACT FROM AUTHOR]

In this study, the self-healing behavior of the polyurethane coating containing polyurethane microcapsules was investigated. Microcapsules, with the average size of 99 µm and shell thickness of 11 µm, were successfully synthesized via the interfacial polymerization technique and were incorporated into the polyurethane coating matrix. The electrochemical impedance spectroscopy and scanning electron microscope were employed to investigate the healing performance and corrosion behavior of the coatings on the carbon steel substrate. The recorded results revealed that artificial scratches were successfully healed and the coating containing 20 wt% microcapsules exhibited the best healing performance (85% healing efficiency) among all the prepared coatings. The self-healing ability of the coatings was verified via scanning electron microscope. After 24 h, the healing efficiency attained a reasonable value of 68% during exposure to test solution. It was found that corrosion resistance and coating adhesion were significantly improved by incorporating the microcapsules into the coating. [ABSTRACT FROM AUTHOR]

Soy protein isolate (SPI)-based self-healing thermoset resins were prepared using either poly(DL-lactide-co-glycolide) porous microspheres (MSs) and spherical microcapsules (MCs) or elongated MCs containing a combination of ground bacterial cellulose (GBC) and SPI as the healing agent. Spray emulsification, combined with solvent evaporation technique, was used to prepare MCs and MSs. The technique resulted in two MC morphologies: one primarily consisting of a mixture of porous MSs and spherical MCs and the other consisting of elongated MCs with aspect ratios as high as 50, depending on the surfactant and GBC amount used. While porous MSs made the resin stronger, they did not contribute to self-healing since they could not retain the healant. Part of the GBC, added during MC preparation, got successfully encapsulated into MCs to form strong GBC/SPI composite healtant. Most of the remaining GBC stayed on MC surfaces and was seen to enhance the MC/resin interfacial adhesion which, in turn, contributed to increased self-healing efficiency. Overall results indicated that resins with 20 wt% elongated MCs exhibited self-healing efficiencies of about 45% in strength and 59% in toughness. The results suggest that the integration of GBC in the healant could also work in other resin systems to enhance their self-healing efficiencies. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) are used as a probiotic alternative to antibiotics in livestock production. Microencapsulation technology is widely used for probiotic preservation. A variety of microencapsulation protocols have been proposed and compared based on chemicals and mechanical procedures. This study aimed to develop a double-encapsulated coating from alginate (1.5%) and chitosan (0.5%) by extrusion, emulsion, and spray drying methods using the LAB strains Lactobacillus plantarum strains 31F, 25F, 22F, Pediococcus pentosaceus 77F, and P. acidilactici 72N, and to monitor the basic probiotic properties of the encapsulated prototypes. The final products from each microencapsulation protocol were analysed for their appearance, probiotic properties and viable cell count. Using the spray drying method, particles smaller than 15 μm in diameter with a regular spherical shape were obtained, whereas the other methods produced larger (1.4–52 mm) and irregularly shaped microcapsules. After storage for 6 months at room temperature, the LAB viability of the spray-dried particles was the highest among the three methods. In all the LAB strains examined, the encapsulated LAB retained their probiotic properties in relation to acid-bile tolerance and antibacterial activity. This study highlights the efficacy of double-coating microencapsulation for preserving LAB properties and survival rate, and demonstrates its potential for probiotic application in livestock farms. [ABSTRACT FROM AUTHOR]

Processing of Russian olive water kefir (RWK), as a fermented functional drink made with Russian olive juice and water kefir grains with high antioxidant activity, into powder is crucial for improving its stability for the commercialization of this product. For the first time, this study aimed to encapsulate water kefir microorganisms and bioactive compounds in RWK using carrier materials to develop a synbiotic functional powder using spray drying as an encapsulation method. The goal was maximizing antioxidant activity, product yield, and survival rate of water kefir microorganisms in the produced Russian olive water kefir powder. The optimal spray drying conditions were observed to be at an inlet air temperature of 120ºC, 35 % feed flow rate, and 7 % concentration of drying aid. The effects of spray drying conditions on the quality of microcapsules were assessed and modeled, and the validity of the model was verified. Also, the spray-dried powder's physicochemical properties were assessed and showed promising microbial and physicochemical characteristics compared with the freeze-dried powder. [ABSTRACT FROM AUTHOR]

Luminescent fibers are widely used in textile fields because of their excellent luminescence performance. However, the lack of its sensing property limits the fiber's application. In this work, two rare earth luminescent materials, SrAl2O4:Eu2+, Dy3+ (SAOED) and Sr2ZnSi2O4:Eu2+, Dy3+ (SZSO), were used as luminous sources, and a yellow thermochromic microcapsule (YTM) was used as a light conversion agent to prepare a thermochromic luminescent fiber (TLF) through wet spinning. The micro-morphology of the TLF was analyzed using scanning electron microscopy (SEM). Three particles were uniformly incorporated in the cellulose fibers, which provide the fibers with a rough surface. Interestingly, the YTM content had no negative effect on the breaking strength of the TLF. Nevertheless, as the concentration of YTM increased from 3 to 10 %, the elongation at break tended to decrease. X-ray diffraction (XRD) results indicate that the cellulose matrix and the wet spinning process did not destroy the phase of rare earth luminescent materials in the fiber. The thermodynamic stability and dynamic phase structure were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The TLF was stable below 100 °C. The fluorescence spectra and absorption spectra measurements show that TLF exhibits good thermochromic luminescence performance. The TLF appeared white at room temperature (25 °C) and emitted green light, but when the temperature increased (50 °C), the fiber faded and emitted indigo light. Herein, the potential application areas of the TLF can be used in optical materials and thermal sensors. [ABSTRACT FROM AUTHOR]

Objective: Our aim was to assess the anti-biofilm ability of previously unverified individual D-amino acids (DAAs), to produce plasma polymer encapsulated DAAs (PPEDAAs), to measure the shell thickness and subsequent release of DAAs, and to assess the effects of PPEDAAs on Enterococcus faecalis biofilms. Materials and methods: Microtitre tray assays were used to evaluate the effect of individual DAAs (D-leucine, D-methionine, D-tryptophan, and D-tyrosine) on E. faecalis biofilms of different maturity. A mixture and individual DAAs were encapsulated with a plasma polymer for 10, 20, 40, and 60 min. The shell thickness of PPEDAAs was analyzed by ultra-high-resolution scanning electron microscopy. The release of DAAs from the PPEDAAs encapsulated for 60 min was measured over 7 days using high-performance liquid chromatography. Static biofilms were used to assess the effect of PPEDAAs on E. faecalis biofilms. Results: Individual DAAs reduced biofilm formation to various degrees, according to the DAA and the experimental times. The shell thicknesses of the PPEDAAs ranged between 31 and 76 nm and increased with encapsulation time. Diffusion of DAAs from the PPEDAAs occurred over 60 min for encapsulated D-leucine, D-methionine, and D-tyrosine and up to 7 days for D-tryptophan. PPEDAAs disrupted biofilms at every experimental time. Conclusions: PPEDAAs of various shell thickness can be produced with the proposed methodology, DAAs are subsequently released, and the anti-biofilm activity remains unaltered. Clinical relevance: Individual DAAs and PPEDAAs have anti-biofilm ability and can be considered as part of a biological strategy in endodontics. [ABSTRACT FROM AUTHOR]

The dynamics of deformable microcapsules flowing through constricted channels is relevant in target delivery of chemicals in physiological systems, porous media, microfluidic medical diagnostic devices and many other applications. In some situations, the microcapsules need to sustain the stress they are subjected to as they flow through constricted channels and in others, the stress may be the rupture trigger used to release the internal content. We experimentally investigate the flow of monodispersed gellan gum microcapsules through a constricted capillary tube by measuring the evolution of the pressure difference and flow visualization. The maximum pressure difference and capsule deformation is obtained for capsules with different diameter and shell thickness. We map the conditions, e.g. diameter and shell thickness, at which the capsule membrane ruptures during the flow, releasing its internal phase. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) was modified with 3-aminopropyltriethoxysilane and was used for synthesis of poly(urethane-urea) microcapsules (PUUMc) with encapsulated maltogenic a-amylase (BaMa) (E. C. 3.2.1.133). The optimization of PVA modification factors and PUUMc synthesis conditions was performed. Chemical structure, porosity and thermostability of PUUMc which were obtained under various synthesis conditions were evaluated. Release rate of BaMa from PUUMc was slower and EI of BaMa was higher, when enzyme was encapsulated during PUUMc synthesis. [ABSTRACT FROM AUTHOR]

Recently, hollow filler as an emerging concept is attracting more attention in preparation of mixed matrix membranes (MMMs). Herein, poly(ethylene glycol) microcapsules (PMC) are synthesized via distillation precipitation polymerization and embedded into the polyetherimide (Ultem®1000) matrix to fabricate MMMs for CO2 capture. The PMC exhibits a preferential hollow structure within the Ultem matrix to furnish highways within membrane, and thus achieve high gas permeability. Meanwhile, the favorable affinity of poly(ethylene glycol) (PEG) microcapsule with ether oxygen group (EO) towards CO2 enhances the CO2 solubility selectivity. Such integration of physical and chemical microenvironments in the as-designed PEG microcapsule affords highly enhanced CO2 separation performance. Compared to pristine Ultem®1000, the membrane with 2.5 wt% PMC loading exhibits 310% increment in CO2 permeability and 22% increment in CO2/N2 selectivity, which shows the promising prospects of designing PEG-containing microcapsules as the filler of MMMs for CO2 capture. [ABSTRACT FROM AUTHOR]

Chemical based finishing agents often affect human body and environment. Therefore, in this study, eco-friendly microcapsules were manufactured to minimize the use of chemicals by using chitosan, a natural substance, as a wall material and basil oil as a core material. First, the optimum manufacturing conditions were established through the shape and size of the synthesized microcapsules. Second, the synthesis and thermal stability of the prepared microcapsules were evaluated. Finally, the applicability to functional fiber processing was reviewed by measuring the release characteristics of the microcapsules. Consequently, using 2 wt% chitosan, Triton X-100 as a emulsifier and stirring at 6000 rpm were considered to be efficient in terms of capsule formation. FT-IR spectrum and Gas Chromatograph showed that microcapsules were stably synthesized. And microcapsule containing basil oil was given heat resistance by encapsulation. Lastly, microcapsules can be confirmed to have sustained-release, due to basil oil in microcapsules has a small amount of release up to 10 h, and is continuously released until after 60 h to release slowly, As a result, the manufactured microcapsules finishing agent may be applied to finishing of textile product. [ABSTRACT FROM AUTHOR]

In this study, polyurethane microcapsules loaded with pirimiphos-methyl were prepared by an interfacial polymerization method using modified poly-isocyanate as the precursor and triethanolamine as a curing agent. The microcapsules were fully characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and so on. The results showed that the microcapsules had good morphology, excellent encapsulation efficiency (90.88%) and loading ability (about 50%) for pirimiphos-methyl. Furthermore, the microcapsules exhibited an excellent sustained release property (above 8 days) in 50% isopropanol aqueous solution(v/v). The biological activity on Musca domestica showed that the microcapsules persistence period was above 90 days, which was longer than emulsifiable concentrate formulation. [ABSTRACT FROM AUTHOR]

Essential oils are volatile compounds commonly used by several industries, easily degradable, which restrains their applications. Therefore, we developed and validated a methodology for producing microcapsules loaded with orange essential oil, using a spray-drying process. The experimental design results showed that the combination between a low flow transfer rate (0.15 L h−1) of the colloidal suspension, a higher drying air flow rate (536 L h−1), and an inlet air temperature of 150 °C to the spray-dryer were the most important parameters for the atomization efficiency. The method optimization resulted in microcapsules with powder recovery between 7.6 and 79.9% (w w−1), oil content ranging from 8.9 to 90.4% (w w−1), encapsulation efficiency between 5.7 and 97.0% (w w−1), and particle sizes with a high frequency of distribution less than 4 μm. In these experiments, gelatin and lignin were evaluated as biopolymers of encapsulation. We also developed an analytical method using headspace gas chromatography. The matrix effects could be addressed by using matrix-matched calibration curves. The chromatographic analysis was linear and selective for d-limonene between 0.025 and 3.00 µg mL−1, with correlation coefficients higher than 0.99. The analytical method had limits of detection and quantitation of 0.024 and 0.073 mg g−1 for gelatin and 0.039 and 0.119 mg g−1 for lignin, respectively. [ABSTRACT FROM AUTHOR]

A trend of present encapsulation research indicates an increased interest in the search for natural encapsulants for bioactive phytochemicals. The present study in pursuit of the same studies the use of jackfruit seed starch (JSS), an underutilized natural polysaccharide in conjugation with soy protein isolate (SPI) as an encapsulating material and NBRE-15 as an emulsifier. Three independent variables viz., total soluble solids (TSS, 20, 25 and 30° Brix), SPI: JSS (1:1, 1:3 and 1:5) and NBRE-15 (0.1, 0.2 and 0.3%) were optimized for achieving the most efficient encapsulation of anthocyanin using a three level, three parameter, Box-Behnken design (BBD) of the Design of Experiments (DOE). The responses considered for the optimization were monomeric anthocyanin content, antioxidant activity and encapsulation efficiency. A combination of 27.0% TSS, 1:5 SPI: JSS ratio and 0.3% NBRE-15 was found to be optimum for the encapsulation of anthocyanin with the desirability of 92.6%. Microcapsules obtained using the optimized combination of independent variables was found to contain 3215.59 mg/100 g monomeric anthocyanin. The antioxidant activity and encapsulation efficiency of the encapsulated material obtained using optimized combinations of independent variable were found to be 365.26 µmol Trolox/g and 89.71%, respectively. The microcapsules were also additionally analyzed for the particle size distribution and morphological characterization. Particle size analysis indicated that the microcapsules obtained had a mean particle size of 60.97 µm. Scanning electron microscopy for morphological characterization indicated that the microcapsules so obtained were oval to round in shape and had a smooth surface. Storage studies to estimate the half-life of anthocyanin in the microcapsule at room temperature (37 °C) clearly indicated greater stability i.e. 63 days when stored under amber-colored vial compared to only 35 days when stored under clear transparent vial. [ABSTRACT FROM AUTHOR]

Conventional internal curing materials for high-performance cementitious system cannot easily have artificial modifications, such that the curing effect is difficult to control during the process. In this study, a novel microcapsule is proposed for controlled internal curing of cement-based materials. The microcapsules are synthesized by a double emulsion method to form a polymer shell-water core structure. The sensitivity of polymer shell to alkaline environments is used to trigger the release of core water. Thus, water release can be controlled by tailoring the shell thickness and microcapsules sizes by changing the polymer dosage and stirring rate during synthesis. The experimental results indicate that the novel microcapsules can effectively release water for internal curing of a cementitious matrix, which exhibits a high curing efficiency in terms of nearly autogenous shrinkage and increases the compressive strength. The novel microcapsules could be promising internal curing agents to enhance high-performance cement-based materials. [ABSTRACT FROM AUTHOR]

Probucol (PB) is a drug that exhibits significant hydrophobicity and substantial intra and inter individual variability in oral absorption, with a miniature bioavailability and complex three compartmental pharmacokinetic modelling due to its high lipid affinity, low stability and high octanol to water partition coefficient. Multiple attempts to formulate PB have not produced satisfactory stable matrices, drug-release profile or rheological flow properties for optimum manufacturing conditions, and with positive and none toxic biological effects. Lithocholic acid (LCA) has recently shown to optimise formulation and cell uptake of drugs. Hence, the aim of this study was to design new PB delivery system, using LCA, and examine its morphology, rheology, stability, and cellular effects. PB was formulated with LCA and sodium alginate (PB-LCA-SA) using various microencapsulation methodologies, and best formulation was investigated in vitro and ex vivo. Using our Ionic Gelation Vibrational Jet flow technology, PB-LCA-SA microcapsules showed good stability and significantly enhanced cell viability, cellular respiration, and reduced inflammation suggesting potential LCA applications in PB delivery and biological effects. [ABSTRACT FROM AUTHOR]

Low density materials can control plasma properties of laser absorption, which can enhance quantum beam generation. The recent practical extreme ultraviolet light (EUV) is the first industrial example of laser plasma source with low density targets. Here we propose an easy-handling target source based on a hollow sub-millimeter microcapsule fabricated from polyelectrolyte cationic and anionic surfactant on air bubbles. The lightweight microcapsules acted as a scaffold for surface coating by tin (IV) oxide nanoparticles (22–48%), and then dried. As a proof of concept study, the microcapsules were ablated with a Nd:YAG laser (7.1 × 1010 W/cm2, 1 ns) to generate 13.5 nm EUV relatively directed to laser incidence. The laser conversion efficiency (CE) at 13.5 nm 2% bandwidth from the tin-coated microcapsule (0.8%) was competitive compared with bulk tin (1%). We propose that microcapsule aggregates could be utilized as a potential small scale/compact EUV source, and future quantum beam sources by changing the coating to other elements. [ABSTRACT FROM AUTHOR]

This study aimed to obtain an extract rich in polyphenols from olive stones using a pilot scale pressurized water extractor, and microencapsulate this extract using a spray dryer. The optimization study focused on the evaluation of the stabilization of the polyphenols and antioxidant effects of the microcapsules obtained. The polyphenol extract of the olive stones obtained under optimum extraction conditions (50 °C, 50 bar, 90 min) was microencapsulated by using 1% chitosan solution as the microencapsulation agent. The total polyphenol contents (TPCs), total flavonoid contents (TFCs), individual polyphenol contents and antioxidant capacities (DPPH and FRAP) of the polyphenol extract and the microcapsules, which were obtained using 200 °C as the optimum air inlet temperature in the spray dryer, were determined. For the evaluation of stability, these microcapsules were stored at three different temperatures, namely − 20 °C, 4 °C and 25 °C, for 180 days. Changes in their TPCs, surface polyphenol contents (SPCs), microencapsulation efficiencies, TFCs and antioxidant capacities were determined every 30 days and their individual polyphenol contents were characterized at both the beginning and the end of the storage period. The encapsulation efficiency of the microcapsules obtained under optimum conditions was 76.89%. At the end of the storage period, the highest degradation of the related compounds was found at − 20 °C. Moreover, it was found that the polyphenols (24.17% for TPC, 53.73% for SPC, and 39.31% for TFC) and antioxidant capacities (15.63% for antiradical effect, and 20.39% for FRAP) of the microcapsules were best preserved in storage at 4 °C. It was thought that aforementioned condition was suitable for the storage of microcapsules which could be evaluated as a new natural food additive or pharmaceutical ingredient. [ABSTRACT FROM AUTHOR]

Droplet microfluidics has enabled the synthesis of polymeric particles with controlled sizes, shell thickness, and morphologies. Here, we report the Janus to core-shell structural evolution of biphasic droplets formed in a microfluidic flow-focusing device (MFFD) for the synthesis of polymer microcapsules with oil core/thickness-tunable shell via off-chip photo- and thermally induced polymerization. First, nanoliter-sized biphasic Janus droplets comprising an acrylate monomer and silicone oil were generated in a co-flowing aqueous polyvinyl alcohol (PVA) solution in an MFFD on a glass chip. Immediately following their break-off, the produced Janus droplets started to change their geometry from Janus to core-shell structure comprising a single silicone-oil core and an acrylate-monomer shell by the minimization of interfacial energy. Thus, we could produce monodisperse core-shell drops with average diameters of 105–325 μm, coefficient of variation (CV) values of 1.0–4.5%, and shell thickness of 1–67 μm. Subsequently, these drops were synthesized to fabricate polymeric microcapsules with tunable shell thickness via photo- and thermally induced polymerization. By increasing the concentration of the photo- and thermal initiator, we successfully produced thinner and ultra-thin shell (800 nm thickness) microcapsules. The surface structure of resulting particles was smooth in photopolymerization and porous in thermal polymerization. [ABSTRACT FROM AUTHOR]

Cavity creation is a key to the origin of biological functions. Small cavities such as enzyme pockets are created simply through liner peptide folding. Nature can create much larger cavities by threading and entangling large peptide rings, as learned from gigantic virus capsids, where not only chemical structures but the topology of threaded rings must be controlled. Although interlocked molecules are a topic of current interest, they have for decades been explored merely as elements of molecular machines, or as a synthetic challenge. No research has specifically targeted them for, and succesfully achieved, cavity creation. Here we report the emergence of a huge capsular framework via multiple threading of metal–peptide rings. Six equivalent C4-propeller-shaped rings, each consisting of four oligopeptides and Ag+, are threaded by each other a total of twelve times (crossing number: 24) to assemble into a well-defined 4 nm-sized sphere, which acts as a huge molecular capsule. Constructing molecular cages from entangled molecules is a complex task requiring precise topological control. Here, the authors thread together six metal-peptide rings into a giant cubic molecular capsule with a defined cavity and 24 crossover points. [ABSTRACT FROM AUTHOR]

There is an urgent need to reduce the environmental impacts of wool fabrics dyeing process while maintain its dyeing effects. Microcapsule technology is a potential option which could be used to move towards cleaner production process and to cope with ever-increasing demands for wool fiber dyeing efficiency. Reactive dyestuff microcapsules were prepared via reverse-phase evaporation methods and then auxiliary-free dye microcapsules were used to dye the wool fabrics. Transmission electron microscope images and fourier transform infrared showed that dye microcapsules possessed a spherical core–shell structure with a diameter of about 500 ± 5 nm. The processing factors were analyzed and optimized by using response surface methodology to improve the encapsulation rate. Higher fixation rate (80.13% vs. 72.03%) of dyed wool fabric, while lower absorbance of dyestuff (0.071 vs. 0.96), chemical oxygen demand (COD, 190 mg/L vs. 1395 mg/L) and biological oxygen demand (BOD5, 83.5 mg/L vs. 649.3 mg/L) of residual wastewater were observed by using microcapsule dyeing, compared with conventional dyeing process. In addition, the results also demonstrated that the filtrated wastewater of microcapsule dyeing can be recycled as dyebath to replace distill water. Thus, we innovatively produced a novel dye microcapsule for wool fabric dyeing application, advancing greatly in reducing the discharge of contaminants to environment, but also in economizing water and energy resources. [ABSTRACT FROM AUTHOR]

The study aims to obtain leakage-free, thermally stable melamine-urea-formaldehyde (MUF)/paraffin microcapsules modified with cellulose nanocrystals (CNCs) by in situ polymerization technique. The morphological features and physicochemical characteristics of CNCs were investigated by transmission electron microscopy, zeta potential measurement, X-ray diffraction, and Fourier transform infrared spectroscopy. Optical microscope measurement, field emission scanning electron microscopy, thermogravimetric analyzer, and differential scanning calorimetry were employed to characterize the morphology, size distribution, and phase change properties of MUF/paraffin microcapsules. The characterization results showed that MUF/paraffin microcapsules were successfully fabricated and modified with CNCs. The CNCs had no impact on the chemical structure or crystal type of MUF/paraffin microcapsules. When the CNC addition was 0.2 wt%, the phase change latent heat values of melting and crystallization of MUF/paraffin microcapsules were, respectively, about 104.5 J/g and 102.8 J/g and the encapsulation efficiency was about 59.8%. [ABSTRACT FROM AUTHOR]

Historically, fabrics were considered as a source of warmth and protection against weather conditions. Nowadays, fabrics can be converted into smart textiles and through this process new properties are conferred to them. For that purpose, microcapsules can play an important role in that they can be used within many application areas including medicine or pharmaceuticals. Malaria, dengue fever and other diseases are typically spread through mosquito bites. This is a concern of many authorities in affected countries and significant research is being conducted today in order to reduce incidence. The aim of the study reported here is not only to demonstrate the effectiveness of microcapsules on cotton fabrics as a prevention to mosquito bites but also to test this in situ. Different fabrics were prepared and tested in two Indian regions. Laboratory tests were performed according to a standard designed by the Swiss Tropical laboratory. Results demonstrated that the fabrics´ repellence to mosquitos could be considered as very good and that the repellent effect of the microcapsules was maintained for more than 10 laundry cycles. Furthermore, our experiments conducted in situ confirmed the effectiveness of the technology. [ABSTRACT FROM AUTHOR]

Microencapsulating water-soluble ammonium persulfate (APS) cores as gel breakers were of considerable significance for improving the gel breaking efficiency of fracturing fluids in oil fields. The general approach, which was used for synthesizing microcapsules containing water-soluble APS cores, oil-soluble organic solvents as the continuous phase, was usually essential to retain the water-soluble properties of the core materials. From the environmentally friendly view, solventless methods for synthesizing these microcapsules will be more desirable and attractive. Presented in this report is a novel solventless method to fabricate the relevant microcapsules, water-soluble APS as the cores and polypyrrole doped with petroleum resin as the shells. The release pattern of the microcapsules is burst release, and its beginning release time could be precisely controlled by changing the type of doped resins and temperatures, which makes them promising candidates for oil exploration, monomer polymerization, fiber printing, batteries, and grease applications. [ABSTRACT FROM AUTHOR]

In the current study, urea-formaldehyde (UF) microcapsules containing drying oils were prepared by in situ polymerization method. The surface of the prepared UF microcapsules was functionalized by using a silane-coupling agent. Scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), as well as atomic force microscopy observations showed that the surface roughness of the microcapsules has been promoted by the silane treating. Fourier transform infrared spectra and field-emission scanning electron microscopy coupled with energy-dispersive X-ray (EDX) analyses showed that the silane-coupling agent molecular binds strongly to the UF microcapsules surface. The particle size analyzer results show that agglomeration of the treated microcapsules was highly reduced. Thermogravimetric analysis indicated that this modification has improved thermal properties of the microcapsules. The SEM and TEM results indicated the surface roughness is increased after the functionalization treatment, and the silane molecules were attached to the surface of the UF microcapsules. According to EDXA, the weight percent of silicon was increased from 0.95 to 1.25 in the case of increasing the weight percent of the silane-coupling agent from 2 to 5 wt%. In fact, it was concluded that two major factors had influenced the UF microcapsules adhesion into the matrix, which were included as the interfacial bonds between the components and the surface roughness. The heat resistance of the microcapsules had been improved by silane-coupling agent functionalization. [ABSTRACT FROM AUTHOR]

TOA-MC was developed to act as absorbent for selective separation of 99Tc(VII) from high-level radioactive liquid waste. The uptake (%) of Re(VII) a substitute for Tc(VII) due to similar chemical behavior by TOA-MC normally exceeding 95% in the presence of dilute HNO3 was strongly retained and decreased with higher HNO3 concentration by batch method. The surface morphology, thermal stability and diameter/size distribution of the microcapsules were examined by scanning electron microscopy, thermogravimetric analysis and digital microscope, respectively. The chemical structure was characterized using Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy. [ABSTRACT FROM AUTHOR]

The gelation behavior of pre-renneted skim milk concentrate during and after spray drying is investigated in this work, which forms the basis for an encapsulation process. This process consists of renneting at 4 °C prior to drying, an initial gelation during drying and a final gelation under controlled rehydration conditions. The aim of this study was to gain a deeper understanding of the gelation process during spray drying by rheological and film and spray drying experiments. For this purpose, steep temperature gradients were applied to assess gelation time and maximal gel strength under fast up-heating conditions to temperatures typical for spray drying. Additionally, the drying behavior during film drying was varied by different dry matter concentrations of the gelling solutions and air temperatures, resulting in different times for the first drying stage. All results were correlated with the degree of aggregation (DA), the characteristic parameter for the state of gelation. The results of the film drying experiments are comparable to the gelation experiments. The gelation process takes more time than spray drying, but it is faster than film drying. Moreover, the gelation only takes place within the first drying stage and, therefore, the drying of SMCs (skim milk concentrate) with lower TS (total solid) contents results in better gelled capsules after spray drying. [ABSTRACT FROM AUTHOR]

Aqueous core-shell particles based on polystyrene, poly(methyl methacrylate) or polycaprolactone have been formulated using a facile double emulsion-based solvent evaporation method. The size distribution is narrow, and the morphology control is remarkable given the simple characteristics of the encapsulation method. The inner droplets are stabilized by oil-soluble poly(ethylene oxide)-based block copolymers which are anchored in the polymeric shell by using hydrophobic blocks of the same type as that of the shell-forming polymer. This facilitates the efficient encapsulation of dyes and hydrophilic biocides.Structural and chemical composition of aqueous core-polymer shell particles stabilized by oil-soluble amphiphiles. [ABSTRACT FROM AUTHOR]

A capillary electrophoresis technique for quantitative determination of phenibut in microcapsules was developed and validated. Rather high efficiencies (~200,000 theoretical plates) and the required resolution (Rs ≥ 1.5) were attained using sodium tetraborate decahydrate solution (10 mM) at pH 9.2 as the supporting electrolyte. Validation of the technique showed that it was specific and complied with requirements of the SP XIIIth Ed. with respect to analytical range and linearity. [ABSTRACT FROM AUTHOR]

We studied the effect of different concentrations of polyelectrolytes poly(allylamine hydrochloride) (PAH) and polystyrene sulfonate (PSS) as well as the effects of microcapsules coated with these polymers on survival of Ehrlich ascites carcinoma cells and mouse peritoneal macrophages and on ROS production by phagocytes. PAH reduced viability of Ehrlich ascites carcinoma in a concentration-dependent manner (LD50=12-15 μg/ml). This effect was presumably determined by its ability to bind phosphates, thereby depleting the culture medium. At the same time, PAH did not affect the viability of macrophages. PSS produced no cytotoxic effect on the examined cells. Polyelectrolyte capsules with the shell architectonics (PAH/PSS)3 and (PAH/PSS)3PAH in the examined concentration range had no effect on the viability of macrophages and tumor cells. PAH microcapsules with positively charged surface much more rapidly and more intensively activated macrophages. The chemiluminescence response directly depended on the amount of capsules in the solution. [ABSTRACT FROM AUTHOR]

Polymer composite materials based on Fenilon S-2 (FS-2) heat-resistant aromatic polyamide and filled with microcapsules containing a lubricating material were developed and used for tribological purposes. FS-2 acts both as a matrix and as a material of microcapsule shells. The choice of oils suitable for preparing the composite is limited and is determined by the capability of oils to preserve lubricating properties at high temperatures of FS-2 forming, up to 320°С. The tribotechnical and physicomechanical tests of the developed composites containing microcapsules demonstrated significant improvement of the tribological characteristics of the materials relative to the initial polymer. The polymer composites filled with microcapsules form an oriented lubricating film on the friction surfaces; this film is retained under high loads for a long time. [ABSTRACT FROM AUTHOR]

A novel phase-change composites based on silicone rubber (MVQ) containing n-octadecane/poly (styrene-methyl methacrylate) microcapsules were successfully obtained by mixing energy-storage microcapsules into MVQ matrix using three preparation methods. The effect of microcapsules content on thermal property of the composites was investigated by thermogravimetric analysis. The mechanical properties of the composites prepared by three methods were also investigated. The morphology and thermal properties of the composites were characterized by scanning electron microscopy (SEM), differential scanning calorimetry, and thermal response. Thermal and mechanical properties of the composites were excellent when the microcapsules were added into room temperature vulcanized silicone rubber with 2 phr (per hundred rubber) content and cured at room temperature. The composites were proved to have good energy-storage performance with 67.6 J g−1 enthalpy value. [ABSTRACT FROM AUTHOR]

Microcapsulses can be designed to effectively encapsulate, protect, and control the release of pesticides. In this study, emulsion-solvent evaporation method was used to fabricate microcapsules using dichloromethane as the solvent, polylactic acid (PLA) as the carrier materials, poly(vinyl alcohol) as the emulsifier, and β-cypermethrin as the entrapped pesticide. The effects of process parameters on the microcapsules characteristics (size, loading content, and encapsulation efficiency) were investigated. Also, the release behavior of the β-cypermethrin was measured experimentally and modeled mathematically. Kinetic analysis indicated that release mechanism of β-cypermethrin was compatible to Fickian diffusion. By optimizing the process parameters, β-cypermethrin-loaded microcapsules were successfully produced with spherical shape, smooth surface, high encapsulation efficiency (> 80%), and a range of pesticide contents. These parameters could be adjusted to achieve delivery systems with desirable release profiles. The results are beneficial to develop delivery systems for rational and effective usage of pesticides. [ABSTRACT FROM AUTHOR]

Results of numerical simulation of light absorption by the dimer of bilayer spherical particles consisting of a water core and a polymer shell absorbing radiation are presented. The spatial distribution and the amplitude characteristics of the volume density of the absorbed power are investigated. It is shown that for a certain spatial dimer configuration, the maximal achievable density of the absorbed power is realized. It is also established that for closely spaced microcapsules with high shell absorption indices, the total power absorbed in the dimer volume can increase in comparison with the radiation absorption by two insulated microparticles. [ABSTRACT FROM AUTHOR]

The diffusiophoresis of a charged spherical porous shell or permeable microcapsule with arbitrary inner and outer radii, fluid permeability, and electric double layer thickness in an ionic solution is analyzed. With the assumption that the imposed electrolyte concentration gradient is relatively weak and the transport system is only perturbed slightly from equilibrium, the electrostatic potential, ionic concentration (electrochemical potential energy), and fluid velocity fields are determined as power-series expansions of the small fixed charge density of the porous shell by solving the relevant linearized electrokinetic equations. An explicit expression for the diffusiophoretic velocity of the porous shell correct to the second order of the fixed charge density results from balancing the exerted electrostatic and hydrodynamic forces. Both the electrophoretic (first-order) and chemiphoretic (second-order) mobilities increase with an increase in the normalized thickness of the porous shell, and these increases are significant when the porous shell is thin. However, the diffusiophoretic velocity of the porous shell, which is the sum of the electrophoretic and chemiphoretic velocities, may not be a monotonic function of its normalized thickness. The variation in the normalized fixed charge density of the porous shell from negative to positive values can lead to more than one reversals in the direction of the diffusiophoretic velocity. [ABSTRACT FROM AUTHOR]

Iron deficiency is the primary cause of many widespread nutritional diseases including anemia, pregnancy complications, and infant mortality. Release kinetics of iron premixes to be mixed with food items like salt, rice, and tea is a key research objective of many globally active iron fortification efforts. Iron release kinetics of microcapsules of two reverse-enteric coating materials (chitosan and Eudragit EPO) encapsulating various amounts of ferrous sulfate (10-40% of total other solids) were done at three pH values (1, 4, 7) for 2 hours. Chitosan and Eudragit microcapsules contained 2.8-5.3% ( w/ w) and 1.7-9.6% ( w/ w) iron, respectively, depicting higher iron loading capacity of Eudragit microcapsules. More than 90% iron was released from most samples within 30 min under stomach conditions (pH 1) and less than 15% iron was released in 2 h under ambient conditions (pH 7), showing suitability of both chitosan and Eudragit EPO as reverse-enteric coatings for iron encapsulation. In terms of reverse-enteric behavior (RE), Eudragit EPO (RE = 2.4) was found to be slightly better than chitosan, suggesting the use of fillers in future research. Higuchi model and Hixson-Crowell model were found to best fit the data, suggesting a transport phenomenon governed by both (a) the diffusion process through the coating material and (b) the dissolution phenomenon resulting in decrease in size of the capsules. Results from this study shall provide guidance for technology development aspects of various food fortification initiatives and an understanding of the iron release from these fortificants during the food preparation and digestion stages. [ABSTRACT FROM AUTHOR]