Nonuniform Collective Dissolution of Bubbles in Regular Pore Networks

Understanding the evolution of solute concentration gradients underpins the prediction of porous media processes limited by mass transfer. Here, we present the development of a mathematical model that describes the dissolution of spherical bubbles in two-dimensional regular pore networks. The model is solved numerically for lattices with up to 169 bubbles by evaluating the role of pore network connectivity, vacant lattice sites and the initial bubble size distribution. In dense lattices, diffusive shielding prolongs the average dissolution time of the lattice, and the strength of the phenomenon depends on the network connectivity. The extension of the final dissolution time relative to the unbounded (bulk) case follows the power-law function, $${B^k/\ell }$$ B k / ℓ , where the constant $$\ell$$ ℓ is the inter-bubble spacing, B is the number of bubbles, and the exponent k depends on the network connectivity. The solute concentration field is both the consequence and a factor affecting bubble dissolution or growth. The geometry of the pore network perturbs the inward propagation of the dissolution front and can generate vacant sites within the bubble lattice. This effect is enhanced by increasing the lattice size and decreasing the network connectivity, yielding strongly nonuniform solute concentration fields. Sparse bubble lattices experience decreased collective effects, but they feature a more complex evolution, because the solute concentration field is nonuniform from the outset.

Chemical Recycling of Mixed Plastics in Electronic Waste Using Solvent-Based Processing

Currently, less than 20% of electronic waste (E-waste) produced in the U.S. is recycled. To improve the recycling rate of E-waste, the study aimed to: (1) identify the major plastics found within electronic shredder residue (ESR), (2) design solvents and processing conditions capable of separating out 90% of the plastic in ESR, and (3) estimate the energy efficiency of the solvent-based process developed. Preliminary screening showed 25 wt.% of the ESR was composed of plastics, with two polymers dominating the sorted plastic fraction—polystyrene (PS, 40 wt.%) and acrylonitrile butadiene styrene (ABS, 25 wt.%). Subsequently, solvents and anti-solvents were screened using Hansen Solubility Parameter Theory for PS, ABS, and ESR dissolution. The pre-screening results showed dichloromethane (DCM) and tetrahydrofuran (THF) as the most effective solvents for PS and ABS, with methanol (MeOH) and ethylene glycol (EG) as the most effective anti-solvents. By optimizing the dissolution time and the solvents used, the highest polymer dissolution yield (99 wt.%) was achieved using DCM for 48 h. Both MeOH and EG precipitated 71 wt.% of the polymer fraction of ESR. EG removed more phosphorus containing flame retardants (94 wt.%) than MeOH (69 wt.%). Energy analysis indicated that the solvent-based processes could save 25–60% of the embodied energy for PS and ABS. Characterization showed that the solvent-based processing could preserve the high molecular weight fraction of the polymers while removing flame retardants at the same time. The results from this study prove the potential of solvent-based processing to produce secondary plastic materials from E-waste for cross-industry reuse.

The Development of a Pressure Actuated Isolation Nozzle Assembly and its Application as Flow Control Device in Extended Reach Water-Alternating-Gas Pilot Wells

The re-development of a giant offshore field in the United Arab Emirates (UAE) consists predominantly of four artificial islands requiring in most cases extremely long horizontal laterals to reach the reservoir targets. Earlier SPE technical papers (1,2) have introduced the development, testing, qualification, and deployment of the plugged liner technology using the dissolvable plugged nozzles (DPNs). The use of DPN plugged liner technology has resulted in CAPEX savings and enhanced production performance. The benefits of DPN technology are its simplicity along with its cost effectiveness. However, the dissolvable material has some limitations, such as pressure rating and dissolution time, which are fluid chemistry dependent. To overcome these limits, a new Pressure Actuated Isolation Nozzle Assembly (PAINA) was developed as an alternative to the plugged liner tool for applications where a higher pressure rating is required, as well as on demand opening. Furthermore, the new PAINA also functions as a flow control device during injection and production, enhancing acid jetting effects during bullhead stimulation and reducing brine losses during liner installation. Liners with PAINAs can be run to TD similar to blank pipe: fluids can be circulated through the inside of the liner without the need for a wash pipe. Once on bottom, non-aqueous drilling fluid is displaced to brine without actuating the isolation mechanism. When the well is ready for production or injection, pressure is applied and the isolation mechanism is activated to establish communication between well and reservoir. These tools were successfully run as flow control devices in water-alternating-gas (WAG) pilot wells. The planning and execution of the initial application will be discussed, along with the tool development, qualification testing, and lessons learned. The key advantage of this technology is in extending plugged liner applications to cases where other pressure-operated tools are included as part of the liner lower completion. Pressure can be applied to the well multiple times without activating the isolation mechanism as long as the applied pressure is below the actuation pressure.

A 3D-Printed Polymer–Lipid-Hybrid Tablet towards the Development of Bespoke SMEDDS Formulations

3D printing is a rapidly growing area of interest within pharmaceutical science thanks to its versatility in creating different dose form geometries and drug doses to enable the personalisation of medicines. Research in this area has been dominated by polymer-based materials; however, for poorly water-soluble lipophilic drugs, lipid formulations present advantages in improving bioavailability. This study progresses the area of 3D-printed solid lipid formulations by providing a 3D-printed dissolvable polymer scaffold to compartmentalise solid lipid formulations within a single dosage form. This allows the versatility of different drugs in different lipid formulations, loaded into different compartments to generate wide versatility in drug release, and specific control over release geometry to tune release rates. Application to a range of drug molecules was demonstrated by incorporating the model lipophilic drugs; halofantrine, lumefantrine and clofazimine into the multicompartmental scaffolded tablets. Fenofibrate was used as the model drug in the single compartment scaffolded tablets for comparison with previous studies. The formulation-laden scaffolds were characterised using X-ray CT and dispersion of the formulation was studied using nephelometry, while release of a range of poorly water-soluble drugs into different gastrointestinal media was studied using HPLC. The studies show that dispersion and drug release are predictably dependent on the exposed surface area-to-volume ratio (SA:V) and independent of the drug. At the extremes of SA:V studied here, within 20 min of dissolution time, formulations with an SA:V of 0.8 had dispersed to between 90 and 110%, and completely released the drug, where as an SA:V of 0 yielded 0% dispersion and drug release. Therefore, this study presents opportunities to develop new dose forms with advantages in a polypharmacy context.

Dissolution Behavior of Different Inclusions in High Al Steel Reacted with Refining Slags

Al2O3, Al2O3·TiN, Al2O3·MgO, and CaO·2Al2O3 are four different types of inclusions in high Al steels. To improve the steel cleanness level, the effective removal of such inclusions during secondary refining is very important, so these inclusions should be removed effectively via inclusion dissolution in the slag. The dissolution behavior of Al2O3, Al2O3·TiN, Al2O3·MgO, and CaO·2Al2O3 in CaO-SiO2-Al2O3-MgO slags, as well as the steel-slag reaction, was investigated using laser scanning confocal microscopy (LSCM) and high-temperature furnace experiments, and thermodynamic calculations for the inclusion in steel were carried out by FactSage 7.1. The results showed that Al2O3·TiN was observed to be completely different from the other oxides. The composite oxides dissolved quickly in the slags, and the dissolution time of the inclusions increased as their melting point increased. SiO2 and B2O3 in the slag were almost completely reacted with [Al] in steel, so the slags without SiO2 showed a positive effect for avoiding the formation of Al2O3 system inclusions and promoting inclusions dissolution as compared with SiO2-rich slags. The steel-slag reaction was also found to influence the inclusion types in steel significantly. Because of the rapid absorption of different inclusions in the slag, it was found that the dissolution time of inclusions mainly depends on the diffusion in the molten slag.

Stimuli-Responsive Dual Cross-Linked N-Carboxyethylchitosan Hydrogels with Tunable Dissolution Rate

Here, we discuss the applicability of (methylenebis(salicylaldehyde)—MbSA) for the fabrication of the stimuli-responsive N-carboxyethylchitosan (CEC) hydrogels with a tunable dissolution rate under physiological conditions. In comparison with non-covalent salicylimine hydrogels, MbSA cross-linking via covalent bis(‘imine clip’) and non-covalent hydrophobic interactions allowed the fabrication of hydrogels with storage moduli > 1 kPa at ten-fold lower aldehyde/CEC molar ratio with the preservation of pH- and amino-acid responsive behavior. Although MbSA-cross-linked CEC hydrogels were stable at neutral and weakly alkaline pH, their disassembly in cell growth medium (Dulbecco’s modified Eagle’s medium, DMEM) under physiological conditions was feasible due to transimination reaction with amino acids contained in DMEM. Depending on the cross-linking density, the complete dissolution time of the fabricated hydrogels varied from 28 h to 11 days. The cytotoxicity of MbSA cross-linked CEC hydrogels toward a human colon carcinoma cell line (HCT 116) and primary human dermal fibroblasts (HDF) was remarkably lower in comparison with CEC-salicylimine hydrogels. Fast gelation, relatively low cytotoxicity, and tunable stimuli-induced disassembly under physiological conditions make MbSA cross-linked CEC hydrogels promising for drug encapsulation and release, 3D printing, cell culturing, and other biomedical applications.

The Importance of pH Adjustment for Preventing Fibrin Glue Dissolution in the Stomach: an in Vitro Study

Background and study aim: Combined use of fibrin glue and polyglycolic acid (PGA) sheets has attracted attention as a preventive measure for complications associated with endoscopic submucosal dissection. However, fibrin glue is a protein that may be dissolved by gastric acid. We evaluated the effect of artificial gastric acid on fibrin clot.Materials and methods: The dissolution time of three layers of fibrin glue with PGA sheets was measured in five groups (pH 1.2, 2.0, 4.0, 5.5, and 6.0 with pepsin). Measurements of three samples per group were made. The mean number of the remaining layers at each measurement point was observed for seven days.Results: The time to complete dissolution of the three layers of fibrin gel in the three samples was 150 minutes at pH 1.2, 5 hours at pH 2.0, 24 hours at pH 4.0, and 2 days and 6 hours at pH 5.5. Conclusion: In order to maintain fibrin glue in the stomach for a long period, there was a need to avoid pepsin activation secondary to acidification of gastric juice. The use of strong antacids is recommended.

Development of Triphala Extract-Loaded Mucoadhesive Films for Aphthous Ulcers

Triphala is a traditional Thai herbal formulation containing dried fruits of Phyllanthus emblica, Terminalia bellirica, and Terminalia chebula. It has wound healing, antioxidant and anti-inflammatory activities. The objective of this research was to formulate mucoadhesive films containing Triphala extract for aphthous ulcers treatment. The films were formulated using hydroxypropyl methylcellulose, HPMC, (5, 8, 10% w/w) as a film-forming polymer and glycerin (5% w/w) as a plasticizer. Triphala extract (2.5, 5, 10% w/w) was incorporated into the film during the film preparation. The films were then evaluated for the physical appearance, dissolution time, mechanical properties (strength and elasticity) and mucoadhesive capability to the porcine buccal mucosa. The antioxidant activity and anti-inflammatory activity of the films were also evaluated by DPPH assay and the proteins denaturation method, respectively. Physical properties revealed that Triphala-loaded HPMC films were transparent with brown color. All formulations showed 1-2 hr of dissolution times. Triphala films exhibited good mucoadhesive properties. Films prepared from the solution containing HPMC (10% w/w), glycerin (5% w/w), and Triphala extract (10% w/w) were the most appropriate formulation for further development due to suitable strength, elasticity, and mucoadhesive properties. Moreover, the films exhibited antioxidants and anti-inflammatory activity which may help relieve the symptom of aphthous ulcers.

Impacts of various mixing approaches towards black seed oil-alginate emulsion attributes

Black seed oil (BSO) contains thymoquinone, an active ingredient that is well-known for its antioxidant property. The bitter taste of BSO makes it challenging for the consumers, mainly children and the elderly, to consume it every day. Thus, BSO is encapsulated in alginate beads in micrometre size to enhance its palatability. This encapsulation was previously established in the lab-scale and the standard mixing method to produce a stable BSO-alginate emulsion used a magnetic stirrer coupled with a sonicator. This mixing method is not suitable for the production of BSO beads at a large scale. Hence, this research aims to investigate the impacts of various mixing methods coupled with sonication towards the BSO-alginate emulsion attributes. Four BSOalginate coarse emulsions were prepared using a magnetic stirrer (MS) as the benchmark, overhead stirrer (OS), homogeniser (H), and overhead stirrer combined with homogeniser (OSH). All the coarse emulsions were then sonicated to produce a nanoemulsion using a flow cell sonicator. The coarse emulsions were characterised in terms of dissolution time while the nanoemulsions were characterised in terms of droplet size, polydispersity index, zeta potential, conductivity and absorbance. These characteristics were statistically compared to the benchmark emulsion characteristics. MS, OS, H, and OSH coarse emulsion formation required 45, 230, 102, and 46 minutes to be produced, respectively. There were significant differences (p <0.05) between the droplet size of OSH (266.53±4.36) nm and MS (285.50±1.15) nm emulsions, indicating that the OSH emulsion was more stable. The absorbance of OSH BSO-alginate nanoemulsion was significantly lower (p <0.05) than the benchmark. In comparison to MS as the benchmark, OSH technique produced a stable emulsion in terms of lower dissolution time, droplet size, zeta potential, and absorbance.

Enhanced keratin extraction from wool waste using a deep eutectic solvent

In this study, the solubilisation of waste coarse wool as a precursory step for the large scale valorisation of keratin was investigated using a green deep eutectic solvent (DES) based on L-cysteine and lactic acid. The investigation was undertaken via the response surface methodology and based on the Box-Behnken design for four process variables of temperature (70-110 °C), dissolution time (2-10 h), the mass of L-cysteine (0.5-2.5 g) in 20 mL of lactic acid, and wool load in the DES (0.2-0.6 g). The effect of variations in temperature was established to be the most significant process variable influencing keratin yield from waste coarse wool in the current work. An optimum keratin yield (93.77 wt.%) was obtained at the temperature of 105 °C, 8 h dissolution time, with 1.6 g L-cysteine in 20 mL of lactic acid using 0.5 g of wool. This study suggests L-cysteine and lactic acid as a green solvent with the potential to scale up keratin recovery from waste wool without significant destruction in the structure of the recovered keratin.HighlightsKeratin recovery from wool using deep eutectic solvent was assessedThe basis for the use of the new deep eutectic solvent was discussedThe effects of the process variables on keratin yield were exploredKeratin recovered was optimised and characterised.