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        Study of UV aging on the performance characteristics of vegetable oil and palm oil derived isocyanate based polyurethane

        Sonalee Das,Priyanka Pandey,Smita Mohanty,Sanjay Kumar Nayak 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

        The impact of UV aging on the characteristic properties of synthesized polyurethane (PUs) from castor oil and transesterified castor oil with palm oil based isocyanate and 1,4 butanediol was investigated at different exposure time of 0, 250, 500, 750 and 1,000 h, respectively. The aging properties of the PU films were analyzed through differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Tensile tests. The PU films derived from castor oil showed noticeable changes in chemical structure after 250 h of UV exposure owing to chain scission of the urethane group. A considerable decrease in the thermal and tensile properties of the developed PU films was observed due to the plasticization phenomenon. SEM micrographs revealed morphological changes through the appearance of cracks and blisters composed of primary amines on the surface of exposed PU films. However, PUs derived from transesterified castor oil with a higher hydroxyl value exhibited improved UV resistance characteristics due to higher crosslinking and degrade only after 750 h of exposure. Thus, the synthesized green PUs based on transesterified castor oil with palm oil based isocyanate compositions can be candidate materials for developing UV resistant coating material.

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        Programmed intermittent epidural bolus as compared to continuous epidural infusion for the maintenance of labor analgesia: a prospective randomized singleblinded controlled trial

        Christina W. Fidkowski,Sonalee Shah,Mohamed-Rida Alsaden 대한마취통증의학회 2019 Korean Journal of Anesthesiology Vol.72 No.5

        Background: Programmed intermittent epidural bolus (PIEB) techniques are a new area of interest for maintaining labor analgesia due to the potential to decrease motor block and improve labor analgesia. This study compares continuous epidural infusion (CEI) to 2 PIEB regimens for labor analgesia. Methods: One hundred fifty patients undergoing scheduled induction of labor at term gestation having epidural labor analgesia were randomized to receive an epidural analgesia regimen of bupivacaine 0.125% with fentanyl 2 μg/ml at either PIEB 5 ml every 30 min (Group 5q30), PIEB 10 ml every 60 min (Group 10q60), or 10 ml/h continuous infusion (Group continuous epidural infusion [CEI]). The primary outcome is the pain scores throughout labor. Secondary outcomes include degree of motor block, dermatomal sensory levels, the number of physician-administered boluses, and patient satisfaction. Results: While the average pain scores throughout labor did not differ significantly between groups, fewer patients in group 10q60 received physician-administered boluses for breakthrough pain (34.9% in 10q60 vs. 61.0% in 5q30 and 61.9% in CEI, P = 0.022). Dermatomal sensory levels, degree of motor block, and patient satisfaction did not differ significantly between groups. Conclusions: Our study suggests that high volume PIEB regimens for labor analgesia decrease breakthrough pain and physician-administered boluses.

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