Experimental and data-driven analysis for predicting nanofluid performance in improving foam stability and reducing mobility at critical micelle concentration.

Application of surfactant-based foam flooding is an effective approach to reduce mobility and control early breakthrough. Despite the proper performance of surfactant-based foams in decreasing the channeling of the flooded gas and water, high pressure, high temperature, and high salinity of the reservoirs put some limitations on the foam flooding efficiency. Nanoparticles are used to improve the quality of the foams, enhance stability, and transcend the limitations. Although there are many benefits of using nanoparticles in foam flooding, their performance at surfactant critical micelle concentration (CMC) is not fully investigated and the optimum nanoparticle concentration is not specified. In this study, an experimental investigation using nanosilica with surfactants at CMC to improve the stability (half-life) and mobility reduction factor (MRF) has been conducted. Furthermore, data from the literature were collected and analyzed to evaluate the change in MRF and stability for a nanofluid-based foam at CMC. Both experimental results and literature data showed that application of nanofluid-based foam is a successful approach to develop a more stable foam with lower mobility. Nanoparticle (NP) concentration is the dominant parameter at different salinities and temperatures that affects foam flow through porous media. The range of 0.2-0.4 wt% is the optimum nanoparticle concentration to develop a strong foam with acceptable performance in controlling mobility.

Investigation of Silk Fibroin/Poly(Acrylic Acid) Interactions in Aqueous Solution.

Silk fibroin (SF) is a protein with many outstanding properties (superior biocompatibility, mechanical strength, etc.) and is often used in many advanced applications (epidermal sensors, tissue engineering, etc.). The properties of SF-based biomaterials may additionally be tuned by SF interactions with other (bio)polymers. Being a weak amphoteric polyelectrolyte, SF may form polyelectrolyte complexes (PECs) with other polyelectrolytes of opposite charge, such as poly(acrylic acid) (PAA). PAA is a widely used, biocompatible, synthetic polyanion. Here, we investigate PEC formation between SF and PAA of two different molecular weights (MWs), low and high, using various techniques (turbidimetry, zeta potential measurements, capillary viscometry, and tensiometry). The colloidal properties of SF isolated from Bombyx mori and of PAAs (MW, overlap concentration, the influence of pH on zeta potential, adsorption at air/water interface) were determined to identify conditions for the SF-PAA electrostatic interaction. It was shown that SF-PAA PEC formation takes place at different SF:PAA ratios, at pH 3, for both high and low MW PAA. SF-PAA PEC's properties (phase separation, charge, and surface activity) are influenced by the SF:PAA mass ratio and/or the MW of PAA. The findings on the interactions contribute to the future development of SP-PAA PEC-based films and bioadhesives with tailored properties.

L-Asparaginase delivery systems targeted to minimize its side-effects.

L-asparaginase (L-ASP) is one of the key enzymes used in therapeutic applications, particularly to treat Acute Lymphocytic Leukemia (ALL). L-asparagine is a non-essential amino acid, which means that it can be synthesized by the body and is not required to be obtained through the diet. The synthesis of L-asparagine occurs primarily in the liver, but it also takes place in other tissues throughout the body. In contrast, leukemic cells cannot synthesize L-asparagine due the absence of L-asparagine synthetase and should obtain it from circulating sources for protein synthesis and cell division processes to ensure their vital functions. L-ASP catalyzes the deamination process of L-asparagine amino-acid into aspartic acid and ammonia, depriving leukemic cells of asparagine. This leads to decreased protein synthesis and cell division in tumor cells. However, using L-ASP has side effects, such as hypersensitivity or allergic reaction, antigenicity, short half-life, temporary blood clearance, and toxicity. L-ASP immobilization can minimize the side effects of L-ASP by stopping the immune system from attacking non-human enzymes and improving the enzyme's performance. The first strategy includes modification of enzyme structure, such as covalent binding (conjugation), adsorption to the support material and cross-linking of the enzyme. The chemical modification of residues, often nonspecific, changes the enzyme's hydrophobicity and surface charge, lowering the enzyme's activity. Also, the first strategy exposes the enzyme's surface to the environment. This eliminates its performance and does not allow targeted delivery of the enzyme. The second strategy is based on the entrapment of the enzyme inside the protecting structure or encapsulation. This strategy offers the same benefits as the first. Still, it also enables reducing toxicity, prolonging in vivo half-life, enhancing stability and activity, enables a targeted delivery and controlled release of the enzyme. Compared to the first strategy, encapsulation does not modify the chemical structure of the enzyme since L-ASP is only effective against leukemia in its native tetrameric form. This review aims to present state of the art in L-ASP formulations developed for reducing the side effects of L-ASP, focusing on describing improvements in their safety. The primary focus in the field remains to be improving the overall performance of the L-ASP formulations. Almost all encapsulation systems allow reducing immune response due to screening the enzyme from antibodies and prolonging its half-life. However, the enzyme's activity and stability depend on the encapsulation system type. Therefore, the selection of the right encapsulation system is crucial in therapy due to its effect on the performance parameters of the L-ASP. Biodegradable and biocompatible materials, such as chitosan, alginate and liposomes, mainly attract the researcher's interest in enzyme encapsulation. The research trends are also moving towards developing formulations with targeted delivery and increased selectivity.

Advances of microemulsion and its applications for improved oil recovery.

Microemulsion, because of its excellent interfacial tension reduction and solubilization properties, has wide range of applications in the petroleum industry, especially in improved oil recovery (IOR). Herein, the concept, types and formation mechanism of microemulsion were primarily introduced. Then, the preparation and characterization methods were illustrated. Additionally, several effect factors were elaborated specifically based on the composition of microemulsion. Finally, the application of microemulsion in IOR was addressed, including IOR mechanism analysis based on sweep efficiency and displacement efficiency, injection method (microemulsion flooding, in-situ microemulsion formation) and field tests. Furthermore, the current challenges and prospects of microemulsion on IOR were analyzed.

On the effects of organic-acids isomers on temperature-responsiveness in wormlike micelles (WLMs) systems.

Responsive wormlike micelles (WLMs) consisted of cationic surfactants and organic-acids are fascinating due to their reversible molecular recognition properties. However, it is unknown how the structure of organic-acids alters the stimuli-responsiveness of WLMs systems. Herein, the peculiar nature of temperature-responsive behaviors in three WLMs systems were systematically investigated. These were manufactured by combining N-erucamidopropyl-N,N-dimethylamine (UC22AMPM) with isomers of organic-acids: o-phthalic acid (o-PA), m-phthalic acid (m-PA) and p-phthalic acid (p-PA) at molar ratio of 2:1 (named as o-EAPA, m-EAPA and p-EAPA respectively). The phase behaviors, macro- and micro-rheology, as well as the mechanism of temperature-responsiveness were explored by visual inspection, rheological and optical methods. The results showed that the three systems exhibited different responsiveness with increase of temperature. Among them, the viscosity and viscoelasticity of o-EAPA were gradually decreased with temperature increase from 30 °C to 90 °C. On the other hand, those of p-EAPA were firstly increased and subsequently decreased, exhibiting the highest viscosity during the heating process. This peculiar phenomenon was attributed to the hydrophilic difference of organic-acids isomers, leading to variations of micelle transitions upon temperature increase. This study is the first report of aromatic-acids isomers inducing different on temperature-responsiveness, and finding beneficial for the development of responsive WLMs for different applications.

Progress of polymer gels for conformance control in oilfield.

For the past decades, long-term water flooding processes have led to water channeling in mature reservoirs, which is a severe problem in oilfields. The development of better plugging ability and cost-effective polymer gel is a key aspect for the control of excess water production. Research on polymer gel applicable in a heterogeneous reservoir to plug high permeable channels has been growing significantly as revealed by numerous published scientific papers. This review intends to discuss the polymer gel techniques from innovations to applications. The related difficulties and future prospects of polymer gels are also covered. Developments of polymer gels to resist temperature, early gel formation, synergistic mechanisms and influence of pH, high salinity are systematically emphasized. The review provides a basis to develop polymer gels for future applications in oilfields to meet harsh reservoir conditions. It will assist the researchers to further develop polymer gels to improve the oil recovery from mature reservoirs under economic conditions to meet the requirements of future oilfields.

The advances of organic chromium based polymer gels and their application in improved oil recovery.

In recent years, with the further development of old oilfields, in order to further improve the oil recovery, they must be conformance controlled. Among various types of conformance control methods, polymer gels composed of polymers and crosslinkers have attracted widespread attention because of their efficiency and low costs. Among them, organic chromium gels with their good formation adaptability and high stability have been fully developed in recent decades. This review introduces the different types of polymers and crosslinkers used in the preparation of organic chromium gels, and the mechanisms of affecting their performance are analyzed. On this basis, the organic chromium gels for different formation conditions are introduced, including nanoparticle-reinforced and compound organic chromium gels. At the same time, evaluation methods of organic chromium gels are introduced, while the focus is on the in-situ measurement method (mirco-rheology) of gel formation time developed in recent decades. Based on the currently developed organic chromium gel and the analysis of the development status in oilfields, future directions like the use of supramolecular organic chromium gel and shear organic chromium gel are suggested.