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To research the effect of hydrogen permeation on the friction characteristics of the seal materials on the hydrogen equipment, the molecular models of 10% PEEK/PTFE composites and its frictional models were established, respectively, and molecular dynamics (MDs) and giant canonical Monte Carlo (GCMC) methods were used to simulate the diffusion coefficient, dissolution coefficient and permeability coefficient of the hydrogen in PEEK/PTFE composites. The effect of a different amount of hydrogen on the friction and wear of PEEK/PTFE composites was also studied. The results showed that few permeations of the hydrogen gas mainly demonstrated having a positive effect on the surface of the PEEK/PTFE composites, and the wear rate of the PEEK/PTFE composites showed a slight decreasing trend. The wear rate of the PEEK/PTFE composites gradually decreased when more hydrogen molecules penetrated the matrix. With the further penetration of the hydrogen molecules, the wear rate and friction coefficient of the PEEK/PTFE composites rapidly increased, showing a negative effect. With the further penetration of the hydrogen molecule, the friction coefficient of the composite displayed a small fluctuation and then a rapid decreasing trend. Meanwhile, effective improvement measures were proposed, and the introduction of the graphene was verified to be effective to reduce the negative effect of the hydrogen permeation, thereby improving the friction performance of the PEEK/PTFE composites.
RESUMEN
BACKGROUND: Use of liver allograft with hepatic hemangioma after in vivo resection of hemangioma in living donor liver transplantation (LDLT) has been previously reported. However, there are few reports describing ex vivo backtable resection of hemangioma from liver allografts in LDLT. CASE SUMMARY: A 55-year-old male was evaluated as a donor for an 8-month-year old patient with acute hepatic failure due to biliary atresia. Pre-operative contrast enhanced computed tomography revealed a 9 cm hemangioma in segment 4 with vascular variations in the donor. During LDLT, an intra-operative intrahepatic cholangiography was performed to ensure no variation in the anatomy of the intrahepatic bile duct. After intra-operative pathological diagnosis, ex vivo backtable resection of the hemangioma was performed and the liver allograft was transplanted into the recipient. The donor's and recipient's post-operative course were uneventful. At the 2-year follow-up, the liver allograft showed good regeneration without any recurrence of hemangioma. CONCLUSION: Liver allografts with hemangiomas are an acceptable alternative strategy for LDLT. Ex vivo backtable resection of hemangioma from the donor liver during pediatric LDLT is safe and feasible, and can effectively reduce the operative time and intra-operative bleeding for the donor.
RESUMEN
RATIONALE: Hepatic epithelioid hemangioendothelioma (HEH) is a rare vascular tumor of the liver with malignant potential. It can be of solitary type, multifocal type, or diffuse type. Although there are some characteristic features on radiologic imaging, the definitive diagnosis of HEH is based on histopathology. The surgical treatment of HEH includes liver resection and transplant. PATIENT CONCERNS: A middle-aged woman presented with easy fatiguability and anorexia for 1 month was found to have multifocal lesions on radiological imaging. DIAGNOSIS: HEH was diagnosed by needle biopsy. It can be seen from imaging that this case is a multifocal form. The largest lesion increased from 3 to 3.3âcm within 2 months, with an increase of 9.45%; no other relevant literatures have been reported. INTERVENTIONS: The possibility of liver transplantation was suggested to the patient. However, the patient refused transplantation and was successfully treated by radical right hepatectomy and resection of the left lobe lesion. OUTCOMES: She remained disease-free throughout a year follow-up period. CONCLUSION: HEH is a rare disease with characteristic radiological and pathological features. Although liver transplantation is the preferred treatment for multifocal HEH, surgical excision represents one alternative when the lesions can be guaranteed to be completely excised.