Semi-solid Gel Research Articles

Semi-solid State PVA-Sodium Silicate Gel Membrane Cell for Electrochemical Oxidation of Gaseous Acetaldehyde at Cobalt Immobilized Graphitic Carbon Nitride Electrode

Semi-solid State PVA-Sodium Silicate Gel Membrane Cell for Electrochemical Oxidation of Gaseous Acetaldehyde at Cobalt Immobilized Graphitic Carbon Nitride Electrode

Ti3C2Tx Filled in EMIMBF4 Semi-Solid Polymer Electrolytes for the Zinc-Metal Battery.

Zinc-ion batteries (ZIBs) are promising candidates for safe energy storage applications. However, undesirable parasitic reactions such as dendrite growth, gas evaluation, anode corrosion, and structural damage to the cathode under an acidic microenvironment severely affected cell performance. To resolve these issues, an MXene entrapped in an ionic liquid semi-solid gel polymer electrolyte (GPE) composite was explored. The molecular-level mixing of poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF), zinc trifluoromethanesulfonate (Zn(OTF)2), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) ionic liquid, and Ti3C2Tx MXene provided a controlled Zn2+ shuttle toward the anode/cathode. Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF exhibited a breaking strength of 0.36 MPa with an associated extension of 23%. The Zn//Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF//Zn symmetric cell with continuous zinc plating/stripping exhibited excellent Zn2+ ion mobility toward the anode and cathode without undesired reactions. This was confirmed by post-mortem analysis after a symmetric cell compatibility test. The as-prepared GPE with a Na3V2(PO4)3 (NVP) cathode exhibited a high chemical diffusion coefficient of 1.14 × 10-7. It also showed an outstanding reversible capacity of 89 mAh g-1 at C/10 with an average discharge plateau voltage of 1.45 V, cycle durability, and controlled self-discharge. These results suggested that the Zn2+ ions in the Ti3C2Tx/EMIBF4/Zn(OTF)2/PVHF composite are reversibly labile in the anode and cathode directions.

Developement and Stability Evaluation of Natural Topical Formulations Containing Pinus sibirica Essential Oil

Abstract Pinus sibirica (P. sibirica) is used in folk medicine for centuries in treatment of various diseases due to its anti-inflammatory, antioxidant, and antimicrobial activity. The present study was focused on formulating semi-solid topical cream and gel preparations with P. sibirica essential oil (EOPS) and on evaluation of their stability during three months of storage. After preparation of semi-solid formulations (cream and gel), we followed parameters such as organoleptic characteristics, pH values, electrical conductivity, phase separation, washability, swelling index and microbiological contamination. Tests for physical and microbiological stability were performed considering different storage conditions at temperature (4±2° C, 25±2°C and 40±2°C) for 12 weeks. All test were performed at sampling time points of 7th, 30th, 60th, 90th day after storage. Cream with EOPS was white colour, it is homogenous with pleasant odor characteristic to used EOPS while gel with EOPS was transparent, it is homogenous with specific odor. After application to skin, EOPS cream was leaving non-greasy film while gel with EOPS was leaving sticky film and cooling effect. In all tested samples, we observed no phase separation and pH values were optimal for skin application. During three months of storage at different conditions, all tested formulations were stable and addition of EOPS did not cause any changes in followed parameters. Both cream and gel formulation remained stable since we did not notice any significant changes in all followed parameters during storage at different temperatures. Addition of 0.5% of EOPS did not change visual, sensory and microbial properties of formulations.

Electrochemical Removal of Gaseous Acetaldehyde Using Ag-Hg Bimetallic Catalyst with a Liquid-Free Electrolyte

Electrochemical methods have been widely used to remove gaseous pollutants that are dissolved in liquids. However, there have been no significant attempt made to remove gaseous pollutants in their gas state, especially through electrochemical method. In this study, we attempted to remove gaseous acetaldehyde (AA) through electro-oxidation using an Ag-Hg bimetallic catalyst coated on a Ni foam electrode at a gas–solid interface. The interface was induced by a semi-solid agar gel in a membrane-divided electrolytic cell. We confirmed the formation of Ag-Hg on the Ni foam electrode through X-ray photoelectron spectroscopy and scanning electron microscopy. We also found that the semi-solid gel was a suitable solid electrolyte, as evidenced by the absence of discernible redox peaks in cyclic voltammetry analysis and the high charge transfer resistance in electrochemical impedance analysis. Under inlet conditions of 15 ppm with a flow rate of 200 mL min−1, we could achieve up to 80% AA degradation. This was due to the effective transfer of electrons in the presence of the semi-solid gel, which was eight times higher than that obtained in the zero-gap method. In continuous operation of the electrochemical reactor with a single-pass of AA, we consistently achieved a removal capacity of 169.81 mg cm−2 h−1 over a 1-h period in an Ar atmosphere. These results demonstrate the practical applicability of this electrochemical system developed using a liquid-free electrolyte and a bimetallic catalyst for the electrode.

Biomediated control of colloidal silica grouting using microbial fermentation

Colloidal silica grouting is a ground improvement technique capable of stabilizing weak problematic soils and achieving large reductions in soil hydraulic conductivities for applications including earthquake-induced liquefaction mitigation and groundwater flow control. In the conventional approach, chemical accelerants are added to colloidal silica suspensions that are introduced into soils targeted for improvement and the formation of a semi-solid silica gel occurs over time at a rate controlled by suspension chemistry and in situ geochemical conditions. Although the process has been extensively investigated, controlling the rate of gel formation in the presence of varying subsurface conditions and the limited ability of conventional methods to effectively monitor the gel formation process has posed practical challenges. In this study, a biomediated soil improvement process is proposed which utilizes enriched fermentative microorganisms to control the gelation of colloidal silica grouts through solution pH reductions and ionic strength increases. Four series of batch experiments were performed to investigate the ability of glucose fermenting microorganisms to be enriched in natural sands to induce geochemical changes capable of mediating silica gel formation and assess the effect of treatment solution composition on pH reduction behaviors. Complementary batch and soil column experiments were subsequently performed to upscale the process and explore the effectiveness of chemical, hydraulic, and geophysical methods to monitor microbial activity, gel formation, and engineering improvements. Results demonstrate that fermentative microorganisms can be successfully enriched and mediate gel formation in suspensions that would otherwise remain highly stable, thereby forgoing the need for chemical accelerants, increasing the reliability and control of colloidal silica grouting, enabling new monitoring approaches, and affording engineering enhancements comparable to conventional colloidal silica grouts.

Thermoplastic elastomer melt-blown fiber mats for oil spill remediation: Fabrication, oil uptake, and gel formation studies

Melt-blown fibers, featuring porous structures with designed wetting characteristics can provide superior oil/water separation performance. The core objective of this work was to design a material that provides excellent oil/water selectivity for oil spill remediation. For this, the selective oil gelation properties of styrene-ethylene-butylene-styrene (SEBS) and the enhanced surface area provided by melt-blown mats was leveraged to achieve exceptional oil/water selectivity. Nonwoven mats based on SEBS were fabricated with a twin-screw extruder equipped with a custom-engineered melt-blowing die. To address the inherent low melt flow index (MFI) of SEBS, which presents challenges in the melt-blowing process due to decreased stretchability, high MFI polypropylene (PP) was incorporated as a blending additive. Next, the impact of blending polypropylene with SEBS on melt-blowing processability and fiber quality was studied. The inclusion of 10 wt% PP in SEBS considerably enhanced fiber melt-blowing processability, resulting in a more extensive and evenly spread fiber stream. Further analysis of this fiber composition in terms of oil and water interaction revealed superior oil uptake capacity. Moreover, the increased surface area of SEBS-based fibers enhanced their interaction with oil, resulting in the effective formation of a semi-solid gel. Notably, the generated gel established a barrier that successfully limited further oil dispersion even when the material reached its saturation point. This demonstrated a markedly superior oil immobilizing performance in comparison to polypropylene melt-blown fibers.

In situ gel-forming oil as rectally delivering platform of hydrophobic therapeutics for ulcerative colitis therapy

Because of their poor water-soluble properties and non-specific distribution, most hydrophobic therapeutics had limited benefit for patients with ulcerative colitis. Herein, an in-situ oil-based gel has been developed as a rectal delivery vehicle for these therapeutics. In situ gel-forming oil (BBLG) was composed of soybean phosphatidyl choline (40%, w/w), glyceryl dioleate (50%, w/w), and ethanol (10%, w/w). The hydrophobic laquinimod (LAQ) as a model drug was easily dissolved in gel-forming oil and its solubility was reaching to 7 ± 0.1 mg/mL. Importantly, upon contact with the colonic fluids, the gel-forming oil was quickly transited to a semi-solid gel, adhering to the inflamed colon mucosa and forming a protective barrier. Transmission Electron Microscopy showed that the gel network was arranged by the connected lipid spheres and LAQ was non-crystally encapsulated into the lipid spheres. Moreover, the universal adhesive test showed that the adhesive force and the adhesive energy of BBLG toward fresh colon tissues were 711 ± 12 mN and 25 ± 2 J/m2, which was 2.14-fold and 5-fold higher than that of the marketed Poloxamer 407 gel, respectively. Meanwhile, in vivo imaging confirmed that the retention time of BBLG in the colon lumen was more than 8 h after rectal administration. In vivo animal studies showed that BBLG also greatly enhanced the therapeutic impact of LAQ on TNBS-treated rats with ulcerative colitis, as evidenced by reduced disease activity index (DAI) scores and weight loss. Moreover, the colonic inflammation was significantly alleviated and the goblet cells were obliviously restored after treatment. Importantly, the gut mucosa barrier was largely repaired without any formation of fibrosis remodeling. Conclusively, in situ liquid gel may be a potential delivery system of hydrophobic medicines for ulcerative colitis.

Baking using oleogels

Baking using oleogels

Effects and mechanism of water-soluble chitosan hydrogel on infected full-thickness skin defect wounds in diabetic mice

Effects and mechanism of water-soluble chitosan hydrogel on infected full-thickness skin defect wounds in diabetic mice

Turbulence-dependent reversible liquid-gel transition of micellar casein-stabilised emulsions

Gel-like emulsions formed with colloidal particles have attracted great attention in various research fields, with studies on food applications surging in an effort to discover new food-grade particle stabilisers that can replace chemical emulsifiers and stabilisers. Turbulence-induced emulsion gels (TIEGs) have recently been reported as a novel means of producing stable gel-like food emulsions. Here we investigate the ability to alternate between liquid and gel-like textures for emulsions stabilised by bovine casein micelles. We describe a reversible emulsion textural transition between free-flowing liquids and semi-solid gels, controlled solely by the application of rotor-stator mixing and high-intensity low-frequency ultrasound (HILF-US), respectively. Rheological and microstructural analyses of the emulsions were performed over five treatment cycles, revealing the importance of the droplet close packing at the submicron level, unique to HILF-US. The amino acid content of the casein was not altered by sonochemical effects. However, the overall secondary structure of the casein protein changed during TIEG formation due to resulting interfacial associations. In-vitro digestion results showed that the initial emulsion texture did not alter protein digestibility. However, TIEG emulsions had smaller droplets that were more stable during digestion. The outcomes aim to deepen the understanding of turbulent-induced emulsion gel formation and advance knowledge on emulsion textural manipulation for food applications.

(Digital Presentation) An Electrochemical-Thermal Coupled Thermal Runaway Multiphysics Model for Lithium Polymer Battery

With the rising energy demand, safe and efficient energy storage technologies have been increasing in importance. Lithium-ion batteries (LIBs) have been dynamically prevalent as energy storage and power sources for various electrical systems, from communication purposes to transportation applications. Lithium Polymer (LiPo) batteries are a subcategory of LIBs that use a solid or semisolid (gel) polymer to act as both a separator and electrolyte for the system. Compared to a conventional liquid electrolyte, gel polymer electrolyte is more thermally and electrochemically stable and relatively safer. Various companies produce a vast number of different LiPo batteries; however, a limited number of studies have been conducted concerning modeling and simulation. Besides exploring new materials for performance enhancement, engineering a reliable model is equally vital to exploit and optimize existing LiPo batteries' potential.In this study, a multiphysics model for a mobile Lithium Cobalt Oxide (LCO)-graphite- Poly(vinylidene fluoride - hexafluoropropylene) (PVdF-HFP) pouch LiPo battery was established to characterize the battery's behavior. The pseudo-2-dimensional electrochemical model and 3D thermal-thermal runaway model were coupled with temperature and heat generation variables. Working voltage and temperature during galvanostatic discharge were examined for the electrochemical-thermal model. In contrast, temperature as a function of time during an oven test was analyzed for thermal runaway models. The electrochemical-thermal and thermal runaway behavior was investigated using the simulation model, and validations were compared with experimental data. Overall, the models can be employed as a design tool to evaluate the component design and estimate the system performance of LiPo batteries for commercial applications.KEYWORDS: Multiphysics model, Lithium-polymer battery, Thermal runaway

(Digital Presentation) A Highly Efficient Photosupercapacitor By Integration of a Mesoporous N-Doped Carbon Double Layer Capacitor with a Perovskite Solar Cell

Internet of Things devices – wireless sensors and actuators – require long-term off-grid power sources that would be cheap, and at the same time have a small footprint with low environmental impact throughout their life cycle. Such an off-grid power source could be realized with a photosupercapacitor: A solar cell is integrated with an electrochemical double-layer capacitor (EDLC) into a single monolithic device using a three-electrode design, where the two components share a common electrode.1 The solar cell converts ambient light into an electric current and charges the integrated supercapacitor via the common electrode, which in turn powers the external device. The supercapacitor, on the other hand, acts as a buffer, mediating between an intermittent light source and the load of the device. In terms of footprint and hence energy and power density, integrated monolithic photosupercapacitors have a clear advantage in comparison with simply wiring a solar cell to a supercapacitor as storage unit. When compared to batteries or pseudocapacitors that involve slow solid-state diffusion reactions and/or surface redox processes, EDLCs are particularly suited for the integration with solar cells into photosupercapacitors as they are able to operate efficiently in fast fluctuating environments where rapid on/off cycles are required without the need to supply a fixed voltage onset.2 Owing to their large specific surface area, good electrical conductivity, and electrochemical stability, mesoporous nitrogen-doped carbon nanospheres (MPNCs) show a great promise for being implemented as an electrode material for supercapacitors.3 , 4 To synthesize MPNCs we used a hard-templating strategy based on the polymerization and self-assembly of aniline in the presence of SiO2 nanoparticles (7 nm), which led to the formation of spherical SiO2/Polyaniline composites. Their carbonization and template removal resulted in highly monodisperse, 140 nm-diameter spherical MPNCs with a large specific surface area (825 m2 g-1) and defined mesopores (7 nm). The MPNCs are easily dispersible and could be processed by doctor-blading in homogeneous 3D-percolated electrodes. Benefiting from the well-defined mesoporous network and the highly accessible electrochemical surface area, our MPNC-based gel-electrolyte freestanding EDLC delivered large energy and power densities and a high capacitance (400 F g-1 at 1 A g-1) with high (95 %) coulombic efficiency.To achieve an energy-autonomous self-powered system, we combined the MPNC-based EDLCs with halide-perovskite-based solar cells in a monolithic three-electrode fashion. As the solar cell we used a p-i-n perovskite solar cell with a FA0.75Cs0.25Pb(I0.8Br0.2)3 (high bandgap) absorber and large photosensitive area (1 cm2) delivering a high open-short circuit voltage (VOC ) of 1.08 V and a short-circuit current (JSC ) of 17.9 mA/cm2. To facilitate the assembly process and to address the adverse sensitivity of the perovskite layer to the electrolyte solvent, we optimized the solar cell layer sequence and termination. At the same time, we used a semi-solid gel electrolyte for the EDLC, which minimizes the contact of the perovskite layer with the electrolyte solvent. This allowed us to obtain a free-standing integrated photosupercapacitor without the necessity of any encapsulation. This reduces the overall device footprint and cost, and simplifies the assembly. Benefiting from the high efficiency of the solar cell and the excellent performance of the EDLC, the integrated hybrid photosupercapacitor demonstrated fast (< 5 s) photocharging up to 1 V under 1 sun illumination and discharge through the EDLC terminals, proving that the solar energy was harvested, converted, and stored. The photosupercapacitor delivered 4.27 μWh/cm2 at a power density of 0.29 mW/cm2 and 1.68 μWh/cm2 at 2.2mW/cm2 with an areal capacitance of 31 mF/cm2. This resulted in an unprecedented overall electrochemical energy conversion efficiency of 11.5 %.5 The strategy for photosupercapacitor fabrication presented here was extended to the integration of MPNC-based EDLCs with other types of solar cells, depending on the intended application. The achieved results pave the way towards the development of off-grid powered energy-autonomous devices.1 Q. Zeng, Y. Lai, L. Jiang, F. Liu, X. Hao, L. Wang and M. A. Green, Adv. Energy Mater., 2020, 10, 1–30.2 F. Béguin, V. Presser, A. Balducci and E. Frackowiak, Adv. Mater., 2014, 26, 2219–2251.3 J. Melke, R. Schuster, S. Möbus, T. Jurzinsky, P. Elsässer, A. Heilemann and A. Fischer, Carbon N. Y., 2019, 146, 44–59.4 J. Melke, J. Martin, M. Bruns, P. Hu, A. Scho, A. Fischer, S. M. Isaza, F. Fink and P. Elsa, ACS Appl. Energy Mater, 2020, 3, 11627.5 T. Berestok, C. Diestel, N. Ortlieb, J. Buettner, J. Matthews, P. S. C. Schulze, J. C. Goldschmidt, S. W. Glunz and A. Fischer, Sol. RRL, 2021, 5, 1–13.

Influencing In situ tuned nanostructures of pulsed laser ablated Co3O4 & WO3 thin film electrodes for binder free flexible operando hybrid supercapacitor devices

Flexible thin-film storage devices have attracted significant devotion owing to their diminutive nature. Flexible thin-film electrode fabrication, Pulsed Laser Deposition (PLD) plays a crucial role because of its tuneable nanostructures, well-regulated chemical composites, and fine thin film thickness controller. Herein, we tuned thin film Co3O4 nanostructures using PLD varying pulsed repetition rates of 2 Hz, 5 Hz, and 8 Hz, for thin energy storage device fabrications. Furthermore, we have grown WO3 thin films nanostructures through PLD for suitable negatrode in thin-film Hybrid Supercapacitor (HSC) devices. Here we fabricated solid-state TFHSC devices such as Co3O4 || WO3 consuming semi-solid gel electrolyte PVA-KOH. At foremost novel aspect of the Co3O4 || WO3 TFHSC device delivered a supreme volumetric capacitance of 141.9 F cm−3. Also, the device reached the voltage window of 1.6 V. Further, the TFHSC device delivered a determined volumetric specific energy density of 12.62 mWh cm−3 at a volumetric power density of 1.27 W cm−3. The HSC device achieved notable stability performances in cycle life 27,000 with an appropriate coulombic efficiency of above 97% along with remarkable capacitance retentions of 91%. More importantly, the TFHSC are a good approach to building portable energy systems for wearable microelectronics and bio-medical applications.

Chemical control over Asialo-GM1: A dual ligand for pili and Lectin A that activates swarming motility and facilitates adherence of Pseudomonas aeruginosa

Glycolipid, ganglio-N-tetraosylceramide (asialo-GM1), on the mammalian cells are known to be recognized by type IV pili of Pseudomonas aeruginosa. In this work, we show that asialo-GM1 can also be recognized by Lectin A (LecA), another adhesin protein of the P. aeruginosa, by a fluorescent polarization assay, a label-free bacterial motility enabled binding assay, and bacterial mutant studies. On hydrated semi-solid gel surfaces, asialo-GM1 enables swarming and twitching motilities, while on solid surfaces facilitates the bacterial adherence of P. aeruginosa. These results indicate that asialo-GM1 can modulate bioactivities, adherence, and motilities, that are controlled by opposite signaling pathways. We demonstrate that when a solution of pilin monomers or LecA proteins are spread on hydrated gel surfaces, the asialo-GM1 mediated swarming motility is inhibited. Treatment of artificial liposomes containing asialo-GM1 as a component of lipid bilayer with pilin monomers or LecA proteins caused transient leakage of encapsulated dye from liposomes. These results suggest that pili and LecA proteins not only bind to asialo-GM1 but can also cause asialo-GM1 mediated leakage. We also show that both pili and LecA mutants of P. aeruginosa adhere to asialo-GM1 coated solid surfaces, and that a class of synthetic ligands for pili and LecA inhibits both pili and LecA-mediated adherence of P. aeruginosa on asialo-GM1-coated surfaces.

Injectable In Situ Gelling System for Sustained Nicotine Delivery as a Replacement Therapy for Smoking Cessation.

Nicotine replacement therapy (NRT) is widely used to limit the withdrawal symptoms associated with cigarette smoking cessation. However, the available NRT formulations are limited by their short release profiles, requiring frequent administrations along with local side effects. Thus, the objective of this study is to develop an NRT formulation that offers prolonged, sustained nicotine release. Thermoresponsive in situ gelling systems containing nicotine were prepared using poloxamer 407 (P407) and poloxamer 188 (P188). The system was optimized using a three-factor, two-level full factorial design (23). A formulation composed of P407 (20% w/w), P188 (5% w/w), and loaded with nicotine (0.5% w/w) exhibited sol-to-gel transition at a suitable temperature close to physiological temperature (30 °C). The rheological analysis demonstrated a Newtonian-like flow at room temperature, suggesting ease of administration via injection, and semisolid gel status at physiological temperature. The optimized formulation successfully sustained nicotine in vitro release over 5 days following single administration. The findings suggest that poloxamer based in situ gelling systems are promising platforms to sustain the release of nicotine.

Experimental device to measure the ionic conductivity anisotropy in liquid crystal hydrogel based in [EMIM] alkyl sulfate Ionic Liquids

We have built an experimental device with the aim to measure the expected electrical conductivity anisotropy in a liquid crystal, obtained from the gelation of the ionic liquid 1-ethyl-3-methyl imidazolium decyl sulfate, [EMIM][DSO4]. This ionic liquid has the particularity that it transits to a semi-solid gel state at room temperature when it contains water, naturally adsorbed from the environment until a balance is reached between the concentration of water in the IL and the atmospheric humidity grade. The quantity of water adsorbed to form the hydrogel at room temperature varies from about 5 to 30 wt%, each composition giving place to different smectic phases. In the gel state, the ionic liquid ions and the water molecules self-organize into micro-sized mesophases that resemble the structures of a liquid crystal. Our device is a closed 2D sample holder (with sides 150 times longer than its thickness), with a single narrow window open to the atmosphere, and four copper contacts on the sides. The dried ionic liquid is tempered at 40 °C to increase its fluidity when injected into the cavity, and then, it can only adsorb water through the narrow opening. Thus, water adsorption is unidirectional and slow, so the transition of the IL to the gel phase happens progressively. A metastable giant mesophase appears as an orientated macrodomain in the form of a striped pattern. In this state, we measure the electrical conductivity of the confined film in directions parallel and perpendicular to the observed strips, finding a difference of up to 26% between both values of the conductivity. If the sample freezes (below 10 °C) or it liquefies (above 50 °C) the meso structure is broken and the observed anisotropy destroyed. We can return the sample to gel state by varying the temperature, but the ordered macroscopic state is no longer recovered. This research must give clues to solve the charge transport mechanism quiz in ionic liquids and semi-solid coductors.

Development of Antioxidant-Fortified Oleogel and Its Application as a Solid Fat Replacer to Muffin.

Oleogelation has recently received a great deal of attention in the food industry as a novel alternative technology that physically converts liquid oil into semi-solid gel. Since the functional characteristics of oleogels are dependent on the gelators or bioactive compounds incorporated, this study was undertaken to evaluate the rheological properties and oxidative stability of candelilla wax oleogels fortified with glycerol monostearate (GMS) and β-carotene, and also to investigate their applications to muffin as a shortening replacer. The interaction between candelilla wax and GMS contributed to strengthening the oleogel structure. The oleogels with β-carotene showed the lowest peroxide values than the other samples. The muffins prepared with oleogels for shortening had greater specific gravity and harder texture, but there was no significant difference in the specific volume between the shortening and oleogel samples with GMS. In addition, muffins with β-carotene oleogels showed the highest oxidative stability. Therefore, this study indicated that the incorporation of β-carotene and GMS in oleogels positively affected the storage stability of muffin.

Structure and Rheological Properties of Glycerol Monolaurate-Induced Organogels: Influence of Hydrocolloids with Different Surface Charge.

Organogel (OG) is a class of semi-solid gel, entrapping organic solvent within a three-dimensional network, which is formed via the self-assembly of organogelators. In the present study, OG was produced by glycerol monolaurate (GML) as organogelator. The influence of hydrocolloids with different surface charges (chitosan (CS), konjac glucomannan (KGM) and sodium alginate (SA)) on the physiochemical properties of OG was investigated. Rheological studies demonstrated that OG and pure hydrocolloid solution showed shear-thinning behavior. After incorporation of the hydrocolloid, the initial viscosity of OG was lowered from ~100 Pa·s to <10 Pa·s, and then the viscosity increased to more than 100 Pa·s at a low shear rate of 0.1–0.2 s−1, which subsequently decreased with a higher shear rate. OGs in the presence of hydrocolloids still kept the thermo-sensitivity, while the melting point of the OG decreased with the incorporation of hydrocolloids. Hydrocolloid addition greatly shortened the gelling time of the OG from 21 min to less than 2 min. The presence of hydrocolloids increased the particle size of oil droplets in the molten OG. Some aggregation and coalescence of oil droplets occurred in the presence of positive-charged CS and negative-charged SA, respectively. After gelling, the gel structure converted into a biphasic-like network. Hydrocolloids improved the hardness, stickiness and the oil-holding stability of OGs by 18.8~33.9%. Overall, hydrocolloid incorporation could modulate the properties of OGs through their different surface charge properties. These novel OGs have potential as nutrient carriers or low-fat margarine alternatives and avoid the trans-fatty acid intake.

Study of Gel Plug for Temporary Blocking and Well-Killing Technology in Low-Pressure, Leakage-Prone Gas Well

Summary A gel-plug system for temporary blocking technology is proposed in this paper to address the prevalent leakage of killing fluid in low-pressure wells; the low technical strength of existing gel plugs for temporary blocking in well killing; difficult-to-control crosslinking time; and gel embrittlement and the difficulty of breaking certain gel plugs. A mixture of etherified galactomannan plant gum, isooctanol polyoxyethylene ether surfactant, and oil phase was used as a thickener. An inorganic salt complex containing long-chain polyhydroxy alcohol was used as a crosslinker and the concentration of long-chain polyhydroxy alcohol far exceeds the theoretical amount required to complex the metal ion. A mixture of polyhydroxy alcohol with a small amount of weak acid was used as a crosslinking regulator. Finally, a mixture of sodium thiosulfate and long-chain quaternary ammonium salt surfactant was used as a stabilizer. Laboratory evaluations showed that this gel-plug system can be directly pumped into the wellbore after being mixed homogeneously, and the viscosity of the system on the surface can be controlled by the amount of crosslinking regulator. The viscosity of the gel-plug system after gelling was high (viscoelastic solid colloid); the initial viscosity reached 30 000 mPa·s at 120°C and retained a semisolid gel shape after aging for 72 hours. Right-angle thickening occurred when the gel warmed to target-zone temperature. The acidic liquid breaker acted quickly, and the viscosity of the broken fluid was lower than 5 mPa·s after 1 to 4 hours. This gel plug for temporary blocking and well-killing technology was successfully applied in a low-pressure, leakage-prone gas well. No gas, pressure, or liquid remained in the open well after killing, the wellhead was successfully replaced, and the tubing was successfully removed. The gel plug also exhibited self-healing: The hole formed by the tubing could be filled and sealed automatically by the gel plug in the annulus. The static friction (outer wall) of 73-mm tubing in the gel plug was 39.6 t/km; the dynamic friction (outer wall) after tubing removal was 7.2 t/km. This gel plug thus shows promise as a temporary blocking technology in workover operations of low-pressure, leakage-prone gas wells.

Formation and Characterization of Zein-Based Oleogels.

Oleogels are interesting as a result of their ability to hold large amounts of oil in a semi-solid gel structure. In the food industry, oleogels are most often investigated as substitutes for saturated and trans fats. In this work, the lyotropic formation of ethanol/zein/oleic acid gels was observed qualitatively and ternary phase diagrams were constructed to map the observations. The viscoelastic parameters G' and G'' were measured to confirm gel formation as observed in phase diagrams. Ultrasmall X-ray scattering was used to study the microstructural organization of ethanol/zein/oleic acid gels. Data suggested that the primary unit or building block for gel network structures was the rod-shaped zein molecule. Ultrasmall X-ray data suggested that zein/oleic acid gels have a highly organized microstructure, possibly the result of zein self-assembly. Zein was considered an effective oleogelator in ethanol/zein/oleic acid systems.