The Synergistic Effects between Sulfobetaine and Hydrophobically Modified Polyacrylamide on Properties Related to Enhanced Oil Recovery.

In order to explore the mechanism responsible for the interactions in the surfactant-polymer composite flooding and broaden the application range of the binary system in heterogeneous oil reservoirs, in this paper, the influences of different surfactants on the viscosity of two polymers with similar molecular weights, partially hydrolyzed polyacrylamide (HPAM) and hydrophobically modified polyacrylamide (HMPAM), were studied at different reservoir environments. In addition, the relationship between the surfactant-polymer synergistic effects and oil displacement efficiency was also investigated. The experimental results show that for HPAM, surfactants mainly act as an electrolyte to reduce its viscosity. For HMPAM, SDBS and TX-100 will form aggregates with the hydrophobic blocks of polymer molecules, reducing the bulk viscosity. However, zwitterionic surfactant aralkyl substituted alkyl sulfobetaine BSB molecules can build "bridges" between different polymer molecules through hydrogen bonding and electrostatic interaction. After forming aggregates with HMPAM molecules, the viscosity will increase. The presence of two polymers all weakened the surfactant oil-water interfacial membrane strength to a certain extent, but had little effect on the interfacial tension. The synergistic effect of the "bridge" between HMPAM and BSB under macroscopic conditions also occurs in the microscopic pores of the core, which has a beneficial effect on improving oil recovery.

Dynamic Interfacial Tensions of Surfactant and Polymer Solutions Related to High-Temperature and High-Salinity Reservoir.

Betaine is a new surfactant with good application prospects in high-temperature and high-salinity reservoirs. The interfacial properties of two kinds of betaine mixtures with a good synergistic effect were evaluated in this paper. On this basis, the effects of temperature-resistant, salt-resistant polymers with different contents of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) on dynamic interfacial tensions (IFTs) against n-alkanes and crude oil were studied. The experimental results show that the IFTs between betaine ASB and n-alkanes can be reduced to ultra-low values by compounding with anionic surfactant petroleum sulfonate (PS) and extended anionic surfactant alkoxyethylene carboxylate (AEC), respectively. ASB@AEC is very oil-soluble with nmin value ≥14, and ASB@PS is relatively water-soluble with nmin value of 10. The water solubility of both ASB@PS and ASB@AEC is enhanced by the addition of water-soluble polymers. The HLB of the ASB@AEC solution becomes better against crude oil after the addition of polymers, and the IFT decreases to an ultra-low value as a result. On the contrary, the antagonistic effect in reducing the IFT can be observed for ASB@PS in the same case. In a word, polymers affect the IFTs of surfactant solutions by regulating the HLB.

Pathologic comparisons of enucleated eyes with retinoblastoma after superselective ophthalmic arterial chemotherapy with or without intravenous chemotherapy.

AIM: To describe and compare pathologic findings in eyes enucleated after superselective ophthalmic arterial chemotherapy (SOAC) or SOAC with intravenous chemotherapy (IVC) for retinoblastoma. METHODS: Medical records between January 1st, 2014 and June 30th, 2017 were retrospectively analyzed, and pathologic findings were recorded. This study included 36 eyes from 22 (61.1%) male and 14 (38.9%) female patients. Nineteen of 36 (52.8%) eyes received SOAC (mean=3, range=1-7) as primary treatment, and 17 of 36 (47.2%) eyes received SOAC (mean=3.7, range=1-10) after IVC (mean=6.1, range=2-11). Tumor extension including choroidal invasion (n=9, 25%), optic nerve invasion (n=5, 13.9%) and anterior segment invasion (n=5, 13.9%) were recorded. RESULTS: Histopathologic evidence of ischemic damage in the retina and choroid was found in 28 (77.8%) eyes. Thrombosed blood vessels were identified in 9 (25%) eyes, including orbital artery in the retrobulbar orbit (n=1), intrascleral vessels (n=4), and chorioretinal vessels (n=6). Fibrotic changes were found in extraocular muscles (n=5, 13.9%) and optic nerve (n=5, 13.9%). Varying degrees of scleral degeneration were found in all eyes. In statistical analysis, there was no significant difference in clinical and pathologic changes between SOAC group and SOAC with IVC group except for optic nerve invasion (P=0.047). CONCLUSION: SOAC for retinoblastoma can result in ocular toxicity, and SOAC with IVC do not increase the toxicity but reduced the incidence of optic nerve invasion.

Internal limiting membrane dragging and peeling: a modified technique for macular holes closure surgery.

AIM: To introduce a modified technique of internal limiting membrane (ILM) centripetal dragging and peeling to treat idiopathic macular hole (IMH) and to observe the ILM-retina adhesive forces. METHODS: Twenty-six consecutive patients with stage 3 to 4 IMH and followed up at least six months were enrolled. All patients underwent complete par plana vitrectomy, ILM dragging and peeling, fluid and gas exchange, 15% C3F8 tamponade and 2-week prone position. The best corrected visual acuity, macular hole evaluation by optical coherence tomography, and complications were evaluated. RESULTS: The mean diameter of IMH was 524±148 µm (range: 201-683 µm), with 21 cases (80.8%) greater than 400 µm. ILM dragging and peeling were successfully performed in all cases. Most of the ILM-retina adhesive forces are severe (42.3%, 11/26), followed by mild (38.5%, 10/26), and moderate (19.2%, 5/26). The mean follow-up duration was 21.2±6.1mo. The IMH was closed in 25 (96.3%) eyes. Visual acuity (logMAR) improved significantly from 1.2±0.6 preoperatively to 0.7±0.5 postoperatively (P<0.001). CONCLUSION: Preexisting ILM-retina adhesive force is found in IMH patients. With assistance of this force, this modified technique may help to release the IMH edges and improve the closure rate of large IMH.

Combined intra-arterial chemotherapy and intravitreal melphalan for the treatment of advanced unilateral retinoblastoma.

AIM: To evaluate the efficacy and safety of combined intra-arterial chemotherapy (IAC) and intravitreal melphalan (IVM) for the treatment of advanced unilateral retinoblastoma. METHODS: This retrospective study involved 30 consecutive eyes from 30 Chinese patients with advanced unilateral retinoblastoma. All patients were initially treated with IAC combined with IVM. The clinical status and complications were recorded at each visit. RESULTS: The International Intraocular Retinoblastoma Classification groups were D in 23 eyes and E in 7 eyes. All eyes showed severe cloud vitreous seeds at the first visit. The mean number of IAC cycles and intravitreal injections was 3.2 (range, 3-4) and 6 (range, 1-14), respectively. The median follow-up time was 29mo (range, 7-36mo). Treatment success with regression of the retinal tumor and vitreous seeds was achieved in 29 of 30 eyes (96.7%). Globe salvage was attained in 93.3% (28/30) eyes, and enucleation (n=2) was performed due to neovascular glaucoma and persistent vitreous hemorrhage. Complications included retinal pigment epithelium (RPE) atrophy (n=13; 43%), mild lens opacity (n=7; 23%), vitreous hemorrhage (n=5; 17%) and rhegmatogenous retinal detachment (n=1; 3%). No extraocular tumor extension or metastasis occurred. CONCLUSION: Combined IAC and IVM is effective and safe for the treatment of advanced unilateral retinoblastoma.