The polymer gel systems are mostly used for the control of excessive water production during enhanced oil recovery operations in mature oil fields. However, these polymer gels are not stable in the high-temperature and high-salinity reservoir. Keeping these in mind, an attempt was made to investigate the effect of several parameters on the gelation time of polymer gels for its suitable application in the oil fields. In this paper, a polymer gel comprised of partially hydrolyzed polyacrylamide as a water-soluble polymer and hydroquinone and hexamine as organic cross-linking agents of low toxicity was prepared to control excessive water production. The effect of various parameters such as polymer and cross-linker concentrations, temperature, pH, and salinity on the gelation time and gel strength was evaluated using the bottle testing method, and variations in the performance of the polymer system were analyzed under different gel compositions and environmental conditions.

During appendicular skeletal development, the bi-potential cartilage anlagen gives rise to transient cartilage, which is eventually replaced by bone, and articular cartilage which caps the ends of individual skeletal elements. While the molecular mechanism that regulates transient cartilage differentiation is relatively better understood, the mechanism of articular cartilage differentiation has only begun to be unraveled. Further, the molecules that coordinate articular and transient cartilage differentiation processes are very poorly understood. Here, we have characterized the regulatory roles of two transcription factors, NFIA and GATA3 in articular cartilage differentiation, maintenance and the coordinated differentiation of articular and transient cartilage. Both NFIA and GATA3 block hypertrophic differentiation. Our results suggest that NFIA is not sufficient but necessary for articular cartilage differentiation. On the other hand, while ectopic activation of GATA3 promotes articular cartilage differentiation, inhibition of GATA3 activity promotes transient cartilage differentiation at the expense of articular cartilage. Finally, we propose a novel transcriptional circuitry involved in embryonic articular cartilage differentiation, maintenance and its cross-talk with transient cartilage differentiation program.

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Removal of metals from wastewaters causes a big concern from the environmental point of view due to their extreme toxicity towards aquatic life and humans. Application of As(III) from aqueous solution by ZnO nanorods as adsorbent has been investigated in the present study. The synthesized nanorods were characterized by XRD, FT-IR spectroscopy, SEM, and thermogravimetric analysis. Optimum biosorption conditions were determined with respect to pH, adsorbent dose, contact time, and temperature. The experimental data were examined using the Lagergren's first-order, pseudo-second-order and intraparticle diffusion kinetic models. The results revealed that the pseudo-second-order kinetic model provided the best description of the data. Langmuir and Freundlich isotherm models were applied to the equilibrium data. The maximum As(III) sorption capacity of ZnO nanorods was found to be 52.63 mg/g at pH 7, adsorbent dose 0.4 g, contact time 105 min, and temperature 323 K. The calculated thermodynamic parameters, ΔG o (between − 5.741, − 5.342 and − 4.538 kJ/mol at 303-323 K), ∆H o (13.75 kJ/mol) and ∆S o (0.0616 J/mol K) showed that the sorption of As(III) onto ZnO nanorods was feasible, spontaneous and exothermic, respectively.

Limb skeleton forms through the process of endochondral ossification. This process of osteogenesis proceeds through an intermediate cartilage template and involves several stages of chondrocyte maturation and eventual bone formation. During the process of endochondral ossification, interplay between BMP and WNT signaling regulate simultaneous differentiation of articular and transient cartilage. In this review, we focus on the recent literature which explores the simultaneous differentiation of these two different types of cartilage. We discuss a new paradigm of developmental biology-inspired tissue engineering of bone and cartilage grafts and provide novel insight into treatment of osteoporosis.

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One highly undesirable characteristic of mature assets that inhibits oil recovery is high water production. Polymer gel treatment is a popular conformance improvement technique applied in this regard due to its cost effectiveness and proved efficiency. Despite this popularity, optimum performance of polymer hydrogels in water shut off is inhibited by excessive aggregation, difficulty in controlling gelation, and their instability at high temperature and high salinity reservoir conditions. To address these shortcomings, research on the application of nanoparticles (NPs) in polymer hydrogels to manage thermal stability and salinity sensitivity has significantly increased in the recent past. By incorporating metal-based NPs, silica or graphene at nanoscale; the gel strength, storage modulus, salinity tolerance and thermal stability of commonly used polymers have been greatly enhanced. In this paper, the advances in experimental studies on polymer-based nanocomposites are discussed and field experiences from adoption of polymer composites reviewed.

A single polymer flooding is a widely employed enhanced oil recovery method, despite polymer vulnerability to shear and thermal degradation. Nanohybrids, on the other hand, resist degradation and maintain superior rheological properties at different shear rates. In this article, the effect of coupling CuO nanoparticles (NPs) and nanoclay with partially hydrolyzed polyacrylamide (HPAM) polymer solution on the rheological properties and the recovery factor of the nanohybrid fluid was assessed. The results confirmed that the NP agents preserved the polymer chains from degradation under mechanical, chemical (i.e., salinity), and thermal stresses and maintained good extent of entanglement among the polymer chains, leading to a strong viscoelastic attribute, in addition to the pseudoplastic behavior. The NP additives increased the viscosity of the HPAM polymer at shear rates varying from 10–100 s−1. The rheological properties of the nanohybrid systems varied with the NP additive content, which in turn provided a window for engineering a nanohybrid system with a proper mobility ratio and scaling coefficient, while avoiding injectivity issues. Sandpack flooding tests confirmed the superior performance of the optimized nanohybrid system and showed a 39% improvement in the recovery ratio relative to the HPAM polymer injection.