Gel Particles Research Articles

Stability, physicochemical, rheological and sensory properties of beverage containing encapsulated jujube extract with sodium alginate stabilized by sodium alginate and Gellan gum

Functional beverages are expanding in the world and since fruits are valuable food sources and are known as sources of antioxidant and phenolic compounds, their extracts and juices in these beverages can be used in different forms. The aim was to protect jujube extract by encapsulating it in the beads to enrich the beverage with phenolic compounds. On the other, gellan and alginate are known as stabilizers and suspend the particles in beverages and make fluid gel and trap particles in their structures. Gellan and sodium alginate were used to suspend alginate beads in antioxidant beverages. Four groups of samples were prepared with 0.15% and 0.3% sodium alginate concentrations and 0.05% and 0.31% gellan concentrations. The results showed that bead suspension were observed appropriately in C (0.3% alginate, 0.05% gellan gum) and D treatments (0.3% alginate, 1% gellan gum). The best sensory properties (overall acceptability= 4) were observed in C treatment (0.3% alginate, 0.05% gellan gum). On the first day of the assay, the highest pH was related to D treatment (3.83) and the lowest was related B treatment (3.57). Increasing of gellan and alginate into the beverage changed the viscosity behavior which led to show highest viscosity (417 cp in D beverage, 30 rpm) and inhibited the beads sedimentation (C and D beverages).

Breakup and coalescence mechanism of high-stability bubbles reinforced by dispersed particle gel particles in the pore-throat micromodel

Bubble breaks up and coalesces continuously during migration in reservoirs, which determines the size distribution of bubbles. As a key parameter of foam technology, the bubble size greatly affects foam stability and plugging performance in the reservoir. Aiming to solve the problem of poor stability of ordinary foam under reservoir conditions, in this study, a high-stability foam for profile control was prepared using dispersed particle gel particles as a foam stabilizer. The characteristics of foam were mainly investigated by the modified Ross-Miles method and microfluidic experiments. The obtained results showed that the foam reinforced by dispersed particle gel particles had a longer half-life under reservoir conditions. It is easier to break up from parent bubbles to daughter bubbles during the migration, which can form foam with higher stability in the porous media. The average size of the daughter bubbles decreased with increasing liquid-phase flow rate, pore-throat ratio and capillary number. The average size varied with the capillary number in a power-law form. Because of the viscoelastic interfacial film and liquid-phase viscous network, the shear effect on the parent bubble in reinforced foam was increased when passing through the pore-throat structure with variable diameter. The large parent bubbles were more likely to break up into more small and stable daughter bubbles. And the interfacial film with higher mechanical strength makes it difficult for the daughter bubbles in reinforced foam to coalesce again. The results indicated that the reinforced foam had stronger dynamic stability and better plugging performance in the reservoir. This work revealed the breakup and coalescence mechanism of bubbles reinforced by dispersed particle gel particles in porous media and provided theoretical guidance for the application of foam technology in high water-cut reservoirs.

Separation of chiral compounds using high performance liquid chromatography stationary phase based on covalent organic framework material TpPa-NH2-Glu

Covalent organic frameworks （COFs） are an emerging class of porous crystalline materials composed of multidentate organic units connected by covalent bonds. COFs have been demonstrated to exhibit great potential and research value in many fields， including gas storage and separation， photoelectric devices， fluorescence sensors， catalysis， drug delivery， dye and pollutant adsorption， and electronic devices， and so on. The COFs obtained by post-synthesis modification tend to exhibit high crystallinities and porosities， thereby rendering them suitable materials for use in the fields of chiral resolution， asymmetric catalysis， and chromatography. In this work， TpPa-NO2 was synthesized from 1，3，5-tricarbaldehyde phloroglucinol and 2-nitro-1，4-phenylenediamine， which was then reduced to TpPa-NH2. Subsequently， this material was modified with D-glucose via a post-synthesis modification strategy to obtain the TpPa-NH2-Glu. TpPa-NH2-Glu were characterized by nuclear magnetic resonance （NMR） spectroscopy， Fourier transform-infrared （FT-IR） spectroscopy， X-ray powder diffraction （XRD） analysis， etc. In the XRD pattern， the peaks observed at 4.7°， 8.1°， 11.1°， and 27° were attributed to the TpPa-NH2-Glu， and these peaks are consistent with previous reports， thereby confirming the successful synthesis of this derivative. In addition， circular dichroism experiments indicated that the TpPa-NH2-Glu exhibited a Cotton effect， further confirming the chiral COF was prepared. Subsequently， this material was immobilized on the surface of spherical silica gel particles via the net-wrapping method to prepare a stationary phase for high performance liquid chromatographic column. Using n-hexane-isopropanol （9∶1， v/v） or methanol-water （9∶1， v/v） as mobile phases at a flow rate of 0.5 mL/min， 16 racemates and two benzene-based positional isomers （o，m，p-nitroaniline and o，m，p-Iodoaniline） were successfully resolved by this chiral column. In addition， under methanol-water （9∶1， v/v） mobile phase conditions， five racemates were separated， among which propranolol hydrochloride， warfarin， and metoprolol reached baseline separation. Furthermore， under n-hexane-isopropanol （9∶1， v/v） mobile phase conditions， 11 racemates were resolved， among which ethyl 2-bromopropionate and 3-butyn-2-ol reached baseline separation. Meanwhile， the effect of temperature on the TpPa-NH2-Glu liquid chromatography column and the repeatability of the TpPa-NH2-Glu liquid chromatography column were also explored. The HPLC column prepared by TpPa-NH2-Glu had good repeatability， and its relative standard deviation （RSD） was 1.55% and 1.46%， respectively. It is demonstrated that the TpPa-NH2-Glu material has good resolution ability for chiral compounds.

Influence of de-structured starch on fine-stranded polymeric and coarse-stranded particulate whey protein gels

This study investigated the phase stability of liquid mixtures and composite gels properties of de-structured waxy potato starch (DWPS) and whey protein isolate (WPI). The DWPS are physically-modified starches treated at 120, 140 and 150 °C for 30 min under constant shear. The composite gels (13% w/w WPI and 4% w/w DWPS) characteristics at pH 7 and pH 5 were evaluated based on their mechanical properties, microstructure, and water-immersion stability. At pH 7, the addition of DWPS did not result in any phase separation. Synergistic gel hardness of WPI was obtained with incorporation of 140 °C DWPS likely due to the enhanced density of a very fine-stranded gel network. The ability of the gel to retain its shape when immersed in water for 40 h was prominent for composite gels containing either gelatinised starch (control) or DWPS samples. In contrast, pure WPI gels and composite gels containing maltodextrin appeared fluid-like and disintegrated gels, respectively. At pH 5, the addition of gelatinised starch or DWPS weakened the particulate protein gels, likely due to phase separation and interrupted protein network with starch polymers acting as an inactive filler. A logarithmically decline in gel hardness was noted as the molar mass of DWPS increased. The coarse porous structure of particulate gels exhibited poor water-holding capacity, low water absorption, and high degree of starch leaching. However, the higher molar mass DWPS polymers enhanced the water-holding capacity of the gels and reduced their own diffusivity from the gel network. • 140 °C DWPS synergistically enhanced the polymeric gel network of WPI. • WPI + DWPS polymeric gels had good shape retention after 40 h water immersion. • Particulate WPI gel strength decreased with increasing molar mass of DWPS samples. • DWPS in particulate WPI gel existed as an inactive filler. • Large molar mass DWPS could disrupt the connectivity of particulate WPI gels.

Tunable oleosome-based oleogels: Effect of polysaccharide architecture on polymer bridging-based structuring

A simple method for structuring natural oleosome emulsions by polymer-bridging mechanism is proposed. Polymer bridging of oleosome droplets was induced by the addition of two different adsorbing polymers. Over a range of polymer/oleosome ratios, the mixture results in the formation of a particle gel network of aggregated oleosome droplets. It is found that polymer bridging ability is heavily influenced by the strength of binding between polymer and oleosome surface where sodium alginate interacted stronger to oleosome surface than ι-carrageenan. These effects are associated with the different molecular architecture and physical differences between the two hydrocolloids. Alginate has a co-block arrangement of charged and uncharged units. The polymer promotes stronger adsorption to the oleosome surface, in contrast to ι-carrageenan, where the negative charges are distributed uniformly along its chain. The polymer bridging ability will influence the resulting microstructure and therefore rheological properties. Confocal scanning laser microscopy showed that the difference in microstructure is mainly in the extent of heterogeneity over different length scales where sodium alginate produced the most heterogeneous microstructures. Bridging-flocculated emulsions showed power-law scaling behavior of the storage modulus with the oleosome concentration, which was explained using percolation theory.

Diagnostic Performance of a Particle Gel Immunoassay in Vaccine-Induced Immune Thrombotic Thrombocytopenia.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious complication of adenoviral vector-based COVID-19 vaccines. Similar to heparin-induced thrombocytopenia (HIT), antibodies reacting to platelet factor 4 (PF4) are responsible for platelet activation in VITT. The diagnosis of VITT includes the detection of anti-PF4 antibodies. Particle gel immunoassay (PaGIA) is one of the rapid immunoassays that is commonly used in the diagnosis of HIT to detect anti-PF4 antibodies. The aim of this study was to investigate the diagnostic performance of PaGIA in patients suspected of VITT. In this retrospective, single-center study, the correlation between PaGIA, enzyme immunoassay (EIA), and modified heparin-induced platelet aggregation assay (HIPA) in patients with findings suggestive of VITT was investigated. A commercially available PF4 rapid immunoassay (ID PaGIA H/PF4, Bio-Rad-DiaMed GmbH, Switzerland) and an anti-PF4/heparin EIA (ZYMUTEST HIA IgG, Hyphen Biomed) were used according to manufacturer's instructions. Modified HIPA was accepted as the gold standard test. Between March 8 and November 19, 2021, a total of 34 samples from clinically well-characterized patients (14 males, 20 females, mean age: 48.2 ± 18.2 years) were analyzed with PaGIA, EIA, and modified HIPA. VITT was diagnosed in 15 patients. Sensitivity and specificity of PaGIA were 54 and 67%, respectively. Anti-PF4/heparin optical density values were not significantly different between PaGIA positive and negative samples (p = 0.586). The sensitivity and specificity of EIA, on the other hand, were 87 and 100%, respectively. In conclusion, PaGIA is not reliable in the diagnosis of VITT because of its low sensitivity and specificity.

SORPTION AND X-RAY FLUORESCENCE DETERMINATION OF MICRO QUANTITIES OF SOME TOXIC METALS IN NATURAL OBJECTS AFTER THEIR PRECONCENTRATION ON MODIFIED SILICA GEL

A method for X-ray fluorescence determination of trace amounts of Pb(II), Cd(II) and Hg(II) ions (up to 250 μg/ml) directly in the sorbent phase after their extraction from solutions in a dynamic sorption mode has been developed. Merck silica gel (particle d 0.1-0.2 mm, specific surface 428.61 m2/g), chemically modified with 4-(2-pyridylazo)-resorcinol functional groups in one step, was used as a sorbent. An energy dispersive X-ray fluorescence analyzer with a semiconductor detector "ElvaX" ("Elvatex", Kyiv) was used in the study.
 It was found that the combined analysis of micro quantities of Pb, Cd and Hg by sorption-x-ray fluorescence method after their preconcentration on silica gel with chemically fixed surfactant requires the use of calibration curves for each metal, taking into account the presence of other ions in solutions.
 The developed by us method of sorption-x-ray fluorescence determination of micro quantities of Pb(II), Cd(II) and Hg(II) after their extraction and preconcentration on silica gel with chemically fixed 4-(2-pyridylazo)-resorcinol can be effectively used for the analysis of natural and man-made objects of complex chemical composition.

Numerical simulation of in-depth profile control for dispersed particle gel in heterogeneous reservoirs

Introduction: As a new agent of enhancing oil recovery, the dispersed particle gel (DPG) has been gradually used for in-depth profile control in mature oilfields. Many researchers investigated the preparation, profile control mechanism and application of DPG based on a series of laboratory experiments. However, few numerical studies have been carried out on profile control mechanism of DPG.Methods: This paper proposes a novel mathematical model to proceed numerical simulation of profile control for DPG, considering DPG particles adsorption and weak shear thinning effects. The numerical codes are verified by the UTCHEM simulator.Results and discussion: The effects of the DPG viscosity, the DPG concentration, the water saturation of high permeable regions and the permeability ratio between high and low permeable regions on decreasing the water-cut of producing well are studied. Simultaneously, this paper also investigates the influence of different mobility ratios between high and low permeable regions on water shutoff of DPG. The numerical simulation results show that the effects of DPG profile control become better as the DPG solution viscosity, the suspension concentration and the permeability ratio increase. But the increased water saturation of high permeable regions is not helpful to improve oil recovery. Water plugging effect of DPG becomes worse with increasing mobility ratio between different regions. According to comparison results between DPG profile control and polymer flooding, it is found that DPG profile control is more suitable for heterogeneous reservoirs. These findings are of benefit to guide the efficient field application of DPG profile control in heterogeneous reservoirs.

Visualized Study on a New Preformed Particle Gels (PPG) + Polymer System to Enhance Oil Recovery by Oil Saturation Monitoring Online Flooding Experiment

After tertiary recovery from the oilfields, improving the production of the remaining hydrocarbon is always challenging. To significantly improve oil recovery, a heterogeneous composite flooding system has been developed with preformed particle gels (PPG) and polymers according to the technical approach of plugging and flooding combination. In addition, an oil saturation monitoring device and a large-scale 3D physical model were designed to better evaluate the performance of the technique. The evaluation results show that the viscosity, stability, and elasticity of the heterogeneous composite flooding system are better than the single polymer system. In addition, both systems exhibit pseudoplastic fluid characteristics and follow the principle of shear thinning. The results of seepage experiments showed that PPG migrates alternately in porous media in the manner of "piling plugging-pressure increasing-deformation migration". The heterogeneous composite system can migrate to the depths of the oil layer, which improves the injection profile. In the visualization experiment, the heterogeneous composite system preferentially flowed into the high-permeability layer, which increased the seepage resistance and forced the subsequent fluid to flow into the medium and low permeability layers. The average saturation of the high, medium, and low permeability layers decreased by 4.74%, 9.51%, and 17.12%, respectively, and the recovery factor was further improved by 13.56% after the polymer flooding.

Preparation and characterization of supramolecular gel suitable for fractured formations

The excellent mechanical properties of supramolecular gel could adapt to the complex reservoir environment and had broad application prospects in the field of oil and gas drilling and production engineering. In this paper, a supramolecular gel based on hydrophobic association and hydrogen bonding was prepared by micellar copolymerization, which could be used to plug fractures and pores in formations. Supramolecular gel was a gel network system with high performance characteristics formed by self-assembly of non-covalent bond interaction. The rheological properties, mechanical mechanics, temperature resistance and swelling ability of supramolecular gel were studied. The results showed that the supramolecular gel had a dense three-dimensional network structure with open and interconnected pore structures, which could exhibit good rheological properties and strong viscoelastic recovery ability. The mechanical properties of the supramolecular gel were excellent, it had a tensile stress of 0.703 MPa and an elongation at break of 1803%. When the compressive strain was 96%, the compressive stress could reach 14.5 MPa. Supramolecular gel also showed good temperature resistance and swelling properties. At the aging temperature of 135 °C, supramolecular gels still maintained good gel strength, and it only took 12 h to reach the equilibrium swelling ratio of 35.87 in 1% NaCl solution. It was also found that supramolecular gel in low concentration saline (1% NaCl solution) showed relatively faster swelling than high concentration saline (25% NaCl solution). The swelling process of the supramolecular gel was non-Fick diffusion (type Ⅱ). This indicated that the organic/inorganic permeability network was well formed. Therefore, the diffusion rate of small molecules could be guaranteed to be equal to the relaxation rate of large molecules before and after the phase transition temperature. In addition to the diffusion of water molecules, the swelling process of the supramolecular gel was also affected by the relaxation of gel network and polymer chain segment, the interaction between water molecules and polymer network and the groups of polymer network and other factors. Supramolecular gel particles could be used as plugging materials for drilling fluids, which had excellent ability to plug formation fractures and pores. The plugging ability of the supramolecular gel was up to 6.7 MPa for 0.5 mm fracture width, and 9.6 MPa for porous media with 5 mD permeability. Compared with HT-PPG gel particles commonly used in oil fields, supramolecular gel particles had better plugging ability on fractures and porous media. The development and application of supramolecular gel had far-reaching significance for promoting the functional application of polymer materials in drilling and production engineering.

A novel CO2-resistant dispersed particle gel for gas channeling control in low-permeability reservoirs

A novel CO2-resistant dispersed particle gel (CR-DPG) for gas channeling control was successfully prepared by shearing an organic–inorganic composite bulk gel. The basic properties, CO2-resistance characteristics, gas channeling control capacity and enhanced oil recovery potential were systemically investigated. The prepared CR-DPG particles were regular spheres, which could maintain a uniform dispersion during the injection process. The CO2 resistance test was carried out at 90 ℃ and CO2 pressure of 20 MPa. After the CO2 resistance test, the dispersion stability of CR-DPG decreased, and the particles coalesced to form large aggregates instead of degrading, exhibiting excellent CO2 resistance. Furthermore, the mechanical strength of the CR-DPG particles aged for different time was measured using atomic force microscope (AFM). Due to the silica gel particles, the CR-DPG particles retained high mechanical strength in the long-term experiment, which could maintain a high plugging effect for a long time during CO2 flooding. A fractured core flowing model was employed to investigate gas channeling control capacity and EOR potential of CR-DPG. The CR-DPG particles could migrate to fractures in-depth, in which particles coalesced to form large aggregates and adsorbed to mitigate gas channeling. In addition, CR-DPG had great potential for enhanced oil recovery by 10.4 %. This work provides an alternative material with a simple preparation process and low cost for gas channeling control in oilfields with CO2 flooding.

Phase change material gel particles with suitable size and superior thermophysical properties towards highly efficient thermal management of miniature electronic components

Phase change materials (PCMs) have demonstrated tremendous potential in emerging thermal management. However, developing PCMs with miniature size and reliable thermal management capability towards the temperature control of miniature electronic components still remains challenging. In this work, granulation of phase change material gel particles (PCMGPs) is proposed as a novel strategy of processing the pristine PCMs, which is conducted by a facile two-step of PCM droplet formation and sol-gel transition. The obtained PCMGPs demonstrate micron size suitable for microelectronic components. The boron nitride (BN) hybridization in the PCMGPs can further enhance their thermophysical properties. The PCMGPs possess a high phase transition enthalpy of 139.01 J g−1, high thermal conductivity of 0.9739 W m−1 K−1 (175 % improvement) and high form stability (no leakage). Owing to the merits of size matching, reliable heat storage and enhanced heat transfer, the PCMGPs are packaged in a smart phone to regulate the thermal environment of the CPU under various working conditions. Results reveal that PCMGPs can significantly decrease the working temperatures of CPU and prevent the thermal shock under high operating load. The working temperatures of CPU can be decreased by 5.4 °C and 8 °C under low and high operating loads, respectively. It can be predicted that this micromachining method has a pioneering guiding significance in the field of micro-scale PCM preparation and micro-scale heat conduction.

Effects of Calcium Carbonate Microcapsules and Nanohydroxyapatite on Properties of Thermosensitive Chitosan/Collagen Hydrogels

Thermosensitive chitosan/collagen hydrogels are osteoconductive and injectable materials. In this study, we aimed to improve these properties by adjusting the ratio of nanohydroxyapatite particles to calcium carbonate microcapsules in a β-glycerophosphate-crosslinked chitosan/collagen hydrogel. Two hydrogel systems with 2% and 5% nanohydroxyapatite particles were studied, each of which had varying microcapsule content (i.e., 0%, 1%, 2%, and 5%). Quercetin-incorporated calcium carbonate microcapsules were prepared. Calcium carbonate microcapsules and nanohydroxyapatite particles were then added to the hydrogel according to the composition of the studied system. The properties of the hydrogels, including cytotoxicity and biocompatibility, were investigated in mice. The calcium carbonate microcapsules were 2-6 µm in size, spherical, with rough and nanoporous surfaces, and thus exhibited a burst release of impregnated quercetin. The 5% nanohydroxyapatite system is a solid particulate gel that supports homogeneous distribution of microcapsules in the three-dimensional matrix of the hydrogels. Calcium carbonate microcapsules increased the mechanical and physical strength, viscoelasticity, and physical stability of the nanohydroxyapatite hydrogels while decreasing their porosity, swelling, and degradation rates. The calcium carbonate microcapsules-nanohydroxyapatite hydrogels were noncytotoxic and biocompatible. The properties of the hydrogel can be tailored by adjusting the ratio of calcium carbonate microcapsules to the nanohydroxyapatite particles. The 1% calcium carbonate microcapsules containing 5% nanohydroxyapatite particle-chitosan/collagen hydrogel exhibited mechanical and physical strength, permeability, and prolonged release profiles of quercetin, which were superior to those of the other studied systems and were optimal for promoting bone regeneration and delivering natural flavonoids.

Preparation of MOF-Based Core-Shell Gel Particles with Catalytic Activity and Their Plugging Performance.

Drilling fluid systems for deep and ultra-deep wells are hampered by both high-temperature downhole environments and lengthy cycle periods. Suppose that the gel particle-plugging agent, the primary treatment agent in the system, fails to offer durable and stable plugging performance. In such a scenario, the borehole wall is susceptible to instability and landslide after prolonged immersion, leading to downhole accidents. In this study, novel core-shell gel particles (modified ZIF) with ZIF particles employed as the core material and organosilicon-modified polyethylene polyamine (PEPA) as the polymer shell were fabricated using PEPA, in-house synthesized (3-aminopropyl) triethoxysilane (APTS), and the ZIF-8 metal-organic framework (MOF) as the raw materials to enhance the long-term plugging performance of gel plugging agents. The modified ZIF particles are nanoscale polygonal crystals and differ from conventional core-shell gel particles in that they feature high molecular sieve catalytic activity due to the presence of numerous interior micropores and mesopores. As a result, modified ZIF exhibits the performance characteristics of both rigid and flexible plugging agents and has an excellent catalytic cross-linking effect on the sulfonated phenolic resin (SMP-3) and sulfonated lignite resin (SPNH) in drilling fluids. Consequently, a cross-linking reaction occurs when SMP-3 and SPNH flow through the spacings in the plugging layer formed by the modified ZIF particles. This increases the viscosity of the liquid phase and simultaneously generates an insoluble gel, forming a particle-gel composite plugging structure with the modified ZIF and significantly enhancing the long-term plugging performance of the drilling fluid.

An in vitro and in vivo approach to characterize digesta from pigs fed different forms of pea flour.

In vitro models of digestion are useful tools to explore the behavior of dietary fiber sources in gastrointestinal conditions. To evaluate the validity of our digestion model, digesta obtained in vivo and in vitro were characterized and the impact of cell wall integrity on protein bioaccessibility and digestibility evaluated. Six cannulated barrows [Pietrain × (Large White × Landrace)] were included in a 2 × 2 Latin square design where they were fed two diets identical in chemical composition but differing in nutrient bioaccessibility. Pea was given either as flour (R1, most proteins encapsulated by intact cell walls) or reconstituted flour (R2, mixture of proteins and purified, broken cell walls). Digesta were collected at the duodenal and ileal cannulas at regular interval and after slaughtering, following ingestion of either R1 or R2. The two diets were also digested in vitro using a static gastrointestinal model. The original pea ingredients as well as the digesta collected in vivo and in vitro were characterized (i.e., particle size measurement, microscopy observations and gel electrophoresis) and then compared with each other. The degradation of the pea ingredients differed greatly between the two forms of flour, where particles filled with nutrients were recovered at the latest stage of R1 intestinal digestion as observed with the particle size distribution and the microscopy images. These results were consistent with the in vivo and in vitro digestibility analysis that showed lower protein hydrolysis for R1 than that for R2 (about 19% difference in protein digestion regardless of the method). Overall, great similarities were found between the digesta collected in vivo and in vitro, especially regarding the particle size measurements. To summarize, a substantial proportion of the proteins contained in R1 was retained within the pea cells following gastrointestinal digestion. These encapsulated proteins reduced the amount of amino acids and small peptides available for absorption. This mechanism will have consequences on postprandial metabolism of amino acids and bacterial population based on the delivery form of the dietary fiber.

Digestion behaviour of capsaicinoid-loaded emulsion gels and bioaccessibility of capsaicinoids: Effect of emulsifier type

In this study, the effect of emulsifier type, i.e. whey protein versus Tween 80, on the digestion behaviour of emulsion gels containing capsaicinoids (CAPs) was examined. The results indicate that the CAP-loaded Tween 80 emulsion gel was emptied out significantly faster during gastric digestion than the CAP-loaded whey protein emulsion gel. The Tween-80-coated oil droplets appeared to be in a flocculated state in the emulsion gel, had no interactions with the protein matrix and were easily released from the protein matrix during gastric digestion. The whey-protein-coated oil droplets showed strong interactions with the protein matrix, and the presence of thick protein layer around the oil droplets protected their liberation during gastric digestion. During intestinal digestion, the CAP-loaded Tween 80 emulsion gel had a lower extent of lipolysis than the CAP-loaded whey protein emulsion gel, probably because the interfacial layer formed by Tween 80 was resistance to displacement by bile salts, and/or because Tween 80 formed interfacial complexes with bile salts/lipolytic enzymes. Because of the softer structure of the CAP-loaded Tween 80 emulsion gel, the gel particles were broken down much faster and the oil droplets were liberated from the protein matrix more readily than for the CAP-loaded whey protein emulsion gel during intestinal digestion; this promoted the release of CAP molecules from the gel. In addition, the Tween 80 molecules displaced from the interface would participate in the formation of mixed micelles and would help to solubilize the released CAP molecules, leading to improved bioaccessibility of CAP. Information obtained from this study could be useful in designing functional foods for the delivery of lipophilic bioactive compounds.

Necking and failure of a particulate gel strand: signatures of yielding on different length scales.

"Sticky" spheres with a short-ranged attraction are a basic model of a wide range of materials from the atomic to the granular length scale. Among the complex phenomena exhibited by sticky spheres is the formation of far-from-equilibrium dynamically arrested networks which comprise "strands" of densely packed particles. The aging and failure of such gels under load is a remarkably challenging problem, given the simplicity of the model, as it involves multiple length- and time-scales, making a single approach ineffective. Here we tackle this challenge by addressing the failure of a single strand with a combination of methods. We study the mechanical response of a single strand of a model gel-former to deformation, both numerically and analytically. Under elongation, the strand breaks by a necking instability. We analyse this behaviour at three different length scales: a rheological continuum model of the whole strand; a microscopic analysis of the particle structure and dynamics; and the local stress tensor. Combining these different approaches gives a coherent picture of the necking and failure. The strand has an amorphous local structure and has large residual stresses from its initialisation. We find that neck formation is associated with increased plastic flow, a reduction in the stability of the local structure, and a reduction in the residual stresses; this indicates that the system loses its solid character and starts to behave more like a viscous fluid. These results will inform the development of more detailed models that incorporate the heterogeneous network structure of particulate gels.

Abstract 1963: Reflectin protein shows length-dependent condensate and particulate gel formation in HeLa cells

Abstract 1963: Reflectin protein shows length-dependent condensate and particulate gel formation in HeLa cells

Assembly and manipulation of responsive and flexible colloidal structures by magnetic and capillary interactions.

The long-ranged interactions induced by magnetic fields and capillary forces in multiphasic fluid-particle systems facilitate the assembly of a rich variety of colloidal structures and materials. We review here the diverse structures assembled from isotropic and anisotropic particles by independently or jointly using magnetic and capillary interactions. The use of magnetic fields is one of the most efficient means of assembling and manipulating paramagnetic particles. By tuning the field strength and configuration or by changing the particle characteristics, the magnetic interactions, dynamics, and responsiveness of the assemblies can be precisely controlled. Concurrently, the capillary forces originating at the fluid-fluid interfaces can serve as means of reconfigurable binding in soft matter systems, such as Pickering emulsions, novel responsive capillary gels, and composites for 3D printing. We further discuss how magnetic forces can be used as an auxiliary parameter along with the capillary forces to assemble particles at fluid interfaces or in the bulk. Finally, we present examples how these interactions can be used jointly in magnetically responsive foams, gels, and pastes for 3D printing. The multiphasic particle gels for 3D printing open new opportunities for making of magnetically reconfigurable and "active" structures.

Production characteristics and displacement mechanisms of infilling polymer-surfactant-preformed particle gel flooding in post-polymer flooding reservoirs: A review of practice in Ng3 block of Gudao Oilfield

The pilot test of infilling polymer-surfactant-preformed particle gel (PPG) flooding has been successfully implemented after polymer flooding in Ng3 block of Gudao Oilfield in China. However, the production characteristics and displacement mechanisms are still unclear, which restricts its further popularization and application. Aiming at this problem, this paper firstly analyzes the production performance of the pilot test and proposed four response types according to the change of water cut curves, including W-type, U-type, V-type response, and no response. Furthermore, the underlying reasons of these four types are analyzed from the aspects of seepage resistance and sweep efficiency. The overall sweep efficiency of gradual-rising W-type, gradual-decreasing W-type, and early V-type response increases from 0.81 to 0.93, 0.55 to 0.89, and 0.94 to 1, respectively. And the sum of seepage resistance along the connection line between production well and injection well for U-type and delayed V-type response increases from 0.0994 to 0.2425, and 0.0677 to 0.1654, respectively. Then, the remaining oil distribution after polymer flooding is summarized into four types on the basis of production and geological characteristics, namely disconnected remaining oil, streamline unswept remaining oil, rhythm remaining oil, and interlayer-controlled remaining oil. Furthermore, the main displacement mechanisms for each type are clarified based on the dimensionless seepage resistance and water absorption profile. Generally, improving connectivity by well pattern infilling is the most important for producing disconnected remaining oil. The synergistic effect of well pattern infilling and polymer-surfactant-PPG flooding increases the dimensionless seepage resistance of water channeling regions and forces the subsequent injected water to turn to regions with streamline unswept remaining oil. The improvement of the water absorption profile by polymer-surfactant-PPG flooding and separated layer water injection contributes to displacing rhythm remaining oil and interlayer-controlled remaining oil. Finally, the paper analyzes the relationships between the remaining oil distribution after polymer flooding and production characteristics of infilling polymer-surfactant-PPG flooding. The study helps to deepen the understanding of infilling polymer-surfactant-PPG flooding and has reference significance for more commercial implementations in the future.