RESUMEN
Developing blend membrane material is one feasible and effective route for improving the gas separation efficiency and commercial attractiveness of membrane technologies. Here, free-standing membranes were prepared by casting method using Pebax-1074 as continuous polymer matrix and poly(ethylene glycol) (PEG) as dispersive organic fillers. The morphology, surface functional groups, microstructure and thermal stability of the membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, respectively. The effects of preparation variables including average molecular weight and dosage of PEG on the microstructure, morphology and properties of the blend membranes were investigated. In addition, the effects of operation conditions including permeation temperature and permeation pressure on the gas separation performance of the blend membranes were also examined. The results showed that the addition of PEG can obviously modify the structure-properties and significantly improve the separation performance of resultant membranes. Under the conditions of 30°C and 0.25 MPa, the optimal CO2 permeability and CO2/N2 selectivity respectively reached to 124.3Barrer and 115.8 for the blend membranes made by PEG600 with a content of 20% in Pebax-1074 matrix. In brief, the as-prepared blend membranes are proved to be promising for CO2/N2 separation application.
RESUMEN
OBJECTIVE: To compare the efficacy and safety of cryoanalgesia and patient-controlled epidural analgesia (PCEA) after thoracotomy. METHODS: Forty patients undergoing elective thoracotomy were randomly divided into cryoanalgesia group (L group, n=20) and PCEA group (n=20). Before chest closure, 4 costal nerve branches (at, above and below the incision, and one for inserting drainage tube) were isolated and frozen for 90 s at -40 to -89 degrees Celsius in L group. The mixture of 0.2% ropivacaine and 3 mg morphine solved in 100 ml normal saline was administered in patients of PCEA group through epidural catheter with PCA pump. The visual analogue scale scores for the analgesic effect and the incidence rate of complications were investigated at different time points every other two days after surgery. RESULTS: There was no difference in the analgesic effects between the two groups, but the rates of ST-T changes, arrhythmia and hypertension as well as the incidence rate of the complications such as postoperative nausea and vomiting, itch and respiratory depression etc differed significantly. CONCLUSION: Given the respective advantages and disadvantages of cryoanlgesia and PCEA, both of which prove to be effective for pain management postthoracotomy, their choice must be decided according to clinical needs.