Predictors of patient and graft survival following pediatric liver transplantation: Long-term analysis of more than 300 cases from single centre.

BACKGROUND: Pediatric liver transplant (PLT) activity has flourished over time although with limited expansion in the graft pool. The study aims to identify pre-transplant factors that predict post-transplant patient and graft survival in the PLT population. METHODS: Retrospective review of PLTs at a single tertiary transplant unit from 2000 to 2019. Univariate and multivariate analyses of pre-transplant factors were performed to identify predictors of patient and graft survival. RESULTS: Two hundred and seventy-six patients received 320 PLTs. The most common cause of graft loss was hepatic artery thrombosis (n = 13, 29.6%). The most common cause of mortality was sepsis (n = 11, 29.7%). Univariate analysis showed that the following variables had a significant (p < .05) impact on patient survival: recipient age, weight, height, graft type (technical variant graft), transplant category (acute liver failure), the era of transplant, and invasive ventilation. The following variables had a significant (p < .05) impact on graft survival: recipient age, weight, height, transplant category (acute liver failure), and the era of transplant. Multivariate analysis precluded the era of transplant as the only significant factor for patient survival; patients transplanted after 2005 had significantly higher patient survival. No independent factor predicting graft survival was identified. For children transplanted after 2005, the only factor that predicted patient survival was pre-transplant invasive ventilation. CONCLUSIONS: Our study suggests that the learning curve and pre-transplant invasive ventilation in the recipient have a significant impact on patient survival. The traditional view of worse outcomes of smaller PLT candidates should be changed.

Performance Studies of Proton Exchange Membrane Fuel Cells with Different Flow Field Designs - Review.

Proton Exchange Membrane Fuel Cell (PEMFC) is majorly used for power generation without producing any emission. In PEMFC, the water generated in the cathode heavily affects the performance of fuel cell which needs better water management. The flow channel designs, dimensions, shape and size of the rib/channel, effective area of the flow channel and material properties are considered for better water management and performance enhancement of the PEMFC in addition to the inlet reactant's mass flow rate, flow directions, relative humidity, pressure and temperature. With the purpose of increasing the output energy of the fuel cell, many flow field designs are being developed continuously. In this paper, the performance of various conventional, modified, hybrid and new flow field designs of the PEMFC is studied in detail. Further the effects of channel tapering, channel bending, landing to channels width ratios, channel cross-sections and insertion of baffles/blockages/pin-fins/inserts are reviewed. The power density of the flow field designs, the physical parameters like active area, dimensions of channel/rib, number of channels; and the operating parameters like temperature and pressure are also tabulated.

Scaling Up Studies on PEMFC Using a Modified Serpentine Flow Field Incorporating Porous Sponge Inserts to Observe Water Molecules.

Flooding of the cathode flow channel is a major hindrance in achieving maximum performance from Proton Exchange Membrane Fuel Cells (PEMFC) during the scaling up process. Water accumulated between the interface region of Gas Diffusion Layer (GDL) and rib of the cathode flow field can be removed by the use of Porous Sponge Inserts (PSI) on the ribs. In the present work, the experimental investigations are carried out on PEMFC for the various reaction areas, namely 25, 50 and 100 cm2. Stoichiometry value of 2 is maintained for all experiments to avoid variations in power density obtained due to differences in fuel utilization. The experiments include two flow fields, namely Serpentine Flow Field (SFF) and Modified Serpentine with Staggered provisions of 4 mm PSI (4 mm × 2 mm × 2 mm) Flow Field (MSSFF). The peak power densities obtained on MSSFF are 0.420 W/cm2, 0.298 W/cm2 and 0.232 W/cm2 compared to SFF which yields 0.242 W/cm2, 0.213 W/cm2 and 0.171 W/cm2 for reaction areas of 25, 50 and 100 cm2 respectively. Further, the reliability of experimental results is verified for SFF and MSSFF on 25 cm2 PEMFC by using Electrochemical Impedance Spectroscopy (EIS). The use of 4 mm PSI is found to improve the performance of PEMFC through the better water management.

Long-term outcomes of pediatric liver transplantation in acute liver failure vs end-stage chronic liver disease: A retrospective observational study.

BACKGROUND: Children with acute liver failure (ALF) who meet the criteria are eligible for super-urgent transplantation, whereas children with end-stage chronic liver disease (ESCLD) are usually transplanted electively. Pediatric liver trans plantation (PLT) in ALF and ESCLD settings has been well described in the literature, but there are no studies comparing the outcomes in these two groups. AIM: To determine if there is a difference in post-operative complications and survival outcomes between ALF and ESCLD in PLT. METHODS: This was a retrospective observational study of all primary PLTs performed at a single center between 2000 and 2019. ALF and ESCLD groups were compared for pretransplant recipient, donor and operative parameters, and post-operative outcomes including graft and patient survival. RESULTS: Over a 20-year study period, 232 primary PLTs were performed at our center; 195 were transplanted for ESCLD and 37 were transplanted for ALF. The ALF recipients were significantly older (median 8 years vs 5.4 years; P = 0.031) and heavier (31 kg vs 21 kg; P = 0.011). Living donor grafts were used more in the ESCLD group (34 vs 0; P = 0.006). There was no difference between the two groups concerning vascular complications and rejection, but there were more bile leaks in the ESCLD group. Post-transplant patient survival was significantly higher in the ESCLD group: 1-, 5-, and 10-year survival rates were 97.9%, 93.9%, and 89.4%, respectively, compared to 78.3%, 78.3%, and 78.3% in the ALF group (P = 0.007). However, there was no difference in 1-, 5-, and 10-year graft survival between the ESCLD and ALF groups (90.7%, 82.9%, 77.3% vs 75.6%, 72.4%, and 66.9%; P = 0.119). CONCLUSION: Patient survival is inferior in ALF compared to ESCLD recipients; the main reason is death in the 1st year post-PLT in ALF group. Once the ALF children overcome the 1st year after transplant, their survival stabilizes, and they have good long-term outcomes.

A study of the influence of current ramp rate on the performance of polymer electrolyte membrane fuel cell.

Durability and reliability are the key factors that prevent fuel cells from successful implementation in automotive sector. Dynamic load change is a common and frequent condition that the fuel cell has to undergo in automotive applications. Fuel cells are more sensitive to changes in load conditions and degrade based on load variation representing idling, rated power, and high power operating conditions. To examine the influence of dynamic load step on the fuel cell performance, two similar cells of active 25 cm2 was tested under two different load step for the same dynamic load cycle. The main difference in dynamic load cycle 2 was the ramp rate which was fixed as 0.1, 0.3, and 0.25 A/cm2/s for 0.2, 0.6, and 1.0 A/cm2 respectively. To investigate the degradative effects, polarization curves, electrochemical impedance spectroscopy, and field emission scanning electron microscopy were used. The results indicated that the degradation rate increased in both dynamic load cycles but however the impact of load change was comparatively minimal in dynamic load cycle 2. The total degradation in performance was 20.67% and 10.72% in dynamic load cycles 1 and 2 respectively. Fuel cell performance degraded in a manner that was consistent with the electrochemical impedance spectroscopy and cross-sectional analysis of field emission scanning electron microscopy. The results prove that the degradation rate is dependent on the load step and the number of load cycles. Severe catalyst degradation and delamination were observed in fuel cells operated under dynamic load cycle 1.

Evaluation of anti-ulcer activity of Samanea saman (Jacq) merr bark on ethanol and stress induced gastric lesions in albino rats.

OBJECTIVE: To evaluate the antiulcer activity of Samanea saman (Jacq) Merr bark on ethanol and stress induced gastric lesions in albino rats. MATERIALS AND METHODS: Gastric lesions were induced in rats by oral administration of absolute ethanol (5 ml/kg) and stress induced by water immersion. The antiulcer activity of methanolic extract of Samanea saman (Jacq) Merr bark (100 mg/kg, 200 mg/kg, 400 mg/kg) was compared with standard drugs. The parameters studied were ulcer index, gastric juice volume, pH, free acidity and total acidity. RESULT: Samanea saman (Jacq) Merr showed a dose dependent curative ratio compared to ulcer control groups. The extract at 400 mg/kg showed significant anti ulcer activity which is almost equal to that of the standard drug in both models. The volume of acid secretion, total and free acidity was decreased and pH of the gastric juice was increased compared to ulcer control group. CONCLUSIONS: The present study indicates that Samanea saman (Jacq) Merr bark extracts have potential anti ulcer activity.