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Showing 2 results for Peyvand
Volume 5, Issue 3 (Fall 2021)
Abstract
Research subject: Prediction of the wellbore temperature during the downhole operations and its effects on the stress condition of the tubulars is one of the important factors in design of the completion, production and stimulation operations in oil and gas wells. Temperature changes during the life of the well can change the stress condition of the pipes inside the well, such as the tubing and the casing, and cause problems such as wellhead displacement or buckling of the tubulars, which is dangerous in both terms of safety of the well and personnel and it can also be economically inefficient.
Research approach: In this study, various operations during the life of a well such as running the completion string, production start-up, the well shut in, acid injection and other common operations in oil wells were simulated in a practical order. Temperature changes during these operations and their effect on the stress condition of the wellbore casing and tubing were investigated.
Main results: The results showed that long-term production of the well causes the most temperature changes in the well. This increase in the temperature reached a maximum value at a depth of 430 ft, which is the mud line depth. Further, because the pipe is fixed, it buckles and creates torque at deeper well depths. The results also showed that the time required for the temperature to be completely stable is about a few months, and this should be taken into account in the tubing pressure test analysis.
Parvaneh Peyvand, Zahra Vaezi, Hossein Naderi-Manesh,
Volume 16, Issue 1 (12-2024)
Abstract
Hepatocellular carcinoma, predominant form of liver cancer, is the main cause of death in patients with liver cirrhosis. Podophyllotoxin, a natural anticancer compound, has ideal anti-tumor properties. However, its use is limited due to poor solubility and bioavailability. Finding a suitable drug delivery system have great importance in improving the bioavailability of podophyllotoxin. In this study, mPEG-PCL nanoparticles have been used for delivery of podophyllotoxin to liver cancer cells. mPEG-PCL copolymers were synthesized and characterized by DLS, FTIR and NMR analyses methods. The critical micellization concentration was 0.055 µg/ml. The z-average and surface charge of micelle was 186 ± 12 nm and -5.13 mV, respectively. podophyllotoxin was loaded in micelles in different w/w ratios of drug: copolymer. The size of the nanodrug was 214 ± 20 nm and the weight ratio of 1:1 with encapsulation efficiency of 77.36 ± 1.23 % was selected as the optimal ratio. The drug release results showed a significant difference between the rapid release of free podophyllotoxin and the more stable release of the loaded drug. At 37°C, drug release was higher, which was attributed to the destruction of polymersome structure at this temperature. According to the cytotoxicity study, the IC50 value for nanodrug (8.64 μg/ml) was lower than the IC50 value for the free drug (12.79 μg/ml), which showed the effect of improved cytotoxicity of nanodrug compared to the free drug. The results proved the polymersome can be potential carriers for delivery, controllable release and improve the toxicity effect of podophyllotoxin in cancer chemotherapy.
