Assessment of modified chitosan composite in acidic reservoirs through pilot and field-scale simulation studies.

Chemical flooding through biopolymers acquires higher attention, especially in acidic reservoirs. This research focuses on the application of biopolymers in chemical flooding for enhanced oil recovery in acidic reservoirs, with a particular emphasis on modified chitosan. The modification process involved combining chitosan with vinyl/silane monomers via emulsion polymerization, followed by an assessment of its rheological behavior under simulated reservoir conditions, including salinity, temperature, pressure, and medium pH. Laboratory-scale flooding experiments were carried out using both the original and modified chitosan at conditions of 2200 psi, 135,000 ppm salinity, and 196° temperature. The study evaluated the impact of pressure on the rheological properties of both chitosan forms, finding that the modified composite was better suited to acidic environments, showing enhanced resistance to pressure effects with a significant increase in viscosity and an 11% improvement in oil recovery over the 5% achieved with the unmodified chitosan. Advanced modeling and simulation techniques, particularly using the tNavigator Simulator on the Bahariya formations in the Western Desert, were employed to further understand the polymer solution dynamics in reservoir contexts and to predict key petroleum engineering metrics. The simulation results underscored the effectiveness of the chitosan composite in increasing oil recovery rates, with the composite outperforming both its native counterpart and traditional water flooding, achieving a recovery factor of 48%, compared to 39% and 37% for native chitosan and water flooding, thereby demonstrating the potential benefits of chitosan composites in enhancing oil recovery operations.

Pediatric Microsurgery in the Reconstruction of Complex Posttraumatic Foot and Ankle Defects: A Long-Term Follow-Up with a Comprehensive Review of the Literature.

BACKGROUND: Lower limb reconstruction is a well-recognized challenge to the trauma or plastic surgeon. Although techniques and outcomes in the adult population are well documented, they are less so in the pediatric population. Here, we present our experience in the management of posttraumatic foot and ankle defects with free tissue transfer in children. METHODS: We performed a retrospective analysis of 40 pediatric patients between the ages of 3 and 16 from 2008 to 2016 who underwent foot and ankle soft tissue reconstruction. Any patient who underwent reconstruction for any reason other than trauma was excluded. Data were collected on operative time, free tissue transfer type, use of vein grafts, length of hospital stay, and postoperative morbidity. Also, a comprehensive systematic literature review was completed according to the PRISMA protocol for all previous reports of foot and ankle reconstruction in the young age group with free tissue transfer. RESULTS: Of our 40 patients, 23 were males and 12 females, free tissue transfer was used to reconstruct primarily the dorsum (71%), heel (11%), medial (9%), and lateral (3%) aspect of the foot. The anterior tibial artery was the predominant recipient vessel for anastomosis (77%). Mean inpatient stay was 9 days and our complication rate was 20%, primarily of superficial infection treated with antibiotic therapy. The review of the literature articles is completely analyzed in detail. CONCLUSION: The need for durable coverage of exposed joints, tendons, fractures, or hardware makes the free flap particularly well suited to trauma reconstruction of the foot and ankle. The lack of underlying vascular disease in this patient group allows for low complication rates. Our study evidences the safety and positive long-term outcomes of free tissue transfer for the reconstruction of huge sized-soft tissue defects of the foot and ankle in children.

Aesthetic Restoration of Severe Hemifacial Atrophy With Free Adipofacial Antero Lateral Thigh Flap Followed by Autologous Fat Grafting; Optimizing Result and Long-Term Outcome.

BACKGROUND: Hemifacial atrophy (Romberg disease) is characterized by progressive soft tissue and bone atrophy on 1 side of the face. The process of atrophy usually starts in the late first or early second decade of life. Romberg Patients usually require soft tissue augmentation for the correction of their defect. There are many reconstructive tools available to correct such facial asymmetry. In this study, we evaluate the outcome of the free adipofacial flap followed by autologous fat grafting in the treatment of Romberg disease, regarding aesthetics and longevity of the treatment. PATIENTS AND METHODS: A retrospective review of 12 patients with moderate to severe hemifacial atrophy from April 2016 till March 2019. All patients received soft tissue augmentation with free adipofascial anterolateral thigh flaps, followed by autologous fat grafting 6 to 12 months later for correction of residual deformity. The average follow-up period was 18 months (range, 6-30). RESULTS: There were 9 females and 3 males in this study. All flaps were survived, and the effect is long-lasting during follow-up. Patients were satisfied with the result especially after refinement of the result of free tissue transfer. The donor sites were closed directly and with no apparent morbidities nor dysfunctions. CONCLUSIONS: Microsurgical free tissue transfer is considered a gold standard tool in the management of moderate and severe form of hemifacial atrophy. Among different flaps available, free adipofacial anterolateral thigh flap (ALT) works as a workhorse flap in the correction of a severe form of the disease. Autologous fat grafting is a versatile and reliable option to correct residual deformities. We believed that such a combination is a superb approach to optimize the outcome of the severe form of the progressive hemifacial atrophy.