Current fuel cell proton exchange membranes rely on a random network of conducting hydrophilic domains to transport protons across the membrane. Despite extensive investigation, details of the structure of the hydrophilic domains in these membranes remain unresolved. In this study a dynamic self-consistent mean field theory has been applied to obtain the morphologies of hydrated perfluorosulfonic acid membranes (equivalent weight of 1100) as a model system for Nafion at several water contents. A coarse-grained mesoscale model was developed by dividing the system into three components: backbone, side chain, and water. The interaction parameters for this model were generated using classical molecular dynamics. The simulated morphology shows phase separated micelles filled with water, surrounded by side chains containing sulfonic groups, and embedded in the fluorocarbon matrix. The size distribution and connectivity of the hydrophilic domains were analyzed and the small angle neutron scattering (SANS) pattern was calculated. At low water content (lambda<6, where lambda is the number of water molecules per sulfonic group) the isolated domains obtained from simulation are nearly spherical with a domain size smaller than that fitted to experimental SANS data. At higher water content (lambda>8), the domains deform into elliptical and barbell shapes as they merge. The simulated morphology, hydrophilic domain size and shape are generally consistent with some experimental observations.

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Context:Parents report that end-of-life decisions are the most difficult treatment-related decisions that they face during their child cancer experience. Research from the parent's perspective of the quality of end-of-life care of their cancer children is scarce, particularly in developing countries like India.Aims:This study aimed to identify the symptoms (medical/social/emotional) that most concerned parents at the end-of-life care of their cancer child and to identify the strategies parents found to be helpful during this period.Settings and Design:We wanted to conduct this to focus on the parents perspectives on their cancer child's end-of-life care and to address the issues that could contribute to the comfort of the families witnessing their child's suffering.Materials and Methods:The study was conducted at Sri Ramachandra University, Chennai, a Tertiary Care Pediatric Hemato Oncology Unit. Parents who lost their child to cancer, treated in our institution were interviewed with a validated prepared questionnaire. Statistical analysis was performed using SAS statistical software package.Results:Toward death, dullness (30%), irritability (30%), and withdrawn from surroundings (10%) were the most common symptoms encountered. About 30% of the children had fear to be alone. About 50% of the children had the fear of death. Pain, fatigue, loss of appetite were the main distressful symptoms that these children suffered from parents’ perspective. Though the parents accepted that the child was treated for these symptoms, the symptom relief was seldom successful.Conclusion:The conclusion of the study was that at the end of their child's life, parents value obtaining adequate information and communication, being physically present with the child, preferred adequate pain management, social support, and empathic relationships by the health staff members.

Current fuel cell proton exchange membranes (PEM) rely on a random network of conducting hydrophilic domains to transport protons across the membrane. Despite extensive investigation, details of the structure of the hydrophilic domains in these membranes remain unresolved. In this study a dynamic self-consistent mean field theory has been applied to obtain the morphologies of hydrated Perfluorosulfonic Acid (PFSA) (equivalent weight of 1100) as a model for Nafion ® at several water contents. A coarse-grained mesoscale model was developed by dividing the system into three components: backbone, side chain, and water. The interaction parameters for this model were generated using classical molecular dynamics. The simulated morphology shows phase separated micelles filled with water, surrounded by side chains containing sulfonic groups, and embedded in the fluorocarbon matrix. For λ<6 (λ gives the ratio of water molecules to sulfonic groups), the isolated domains obtained from simulation are nearly spherical with a domain size smaller than that fitted to experimental SANS data. For λ>8; the domains deform into elliptical and barbell shapes as they merge. The simulated morphology, hydrophilic domain size and shape are generally consistent with some experimental observations. INTRODUCTIONThe interest in fully perfluorinated perflurosulfonic acid (PFSA) polymer membranes, like Nafion has been prompted by their wide application in polymer electrolyte fuel cells as proton exchange membranes (PEM). The PFSA structure consists of a highly hydrophobic polytetrafluoroethylene (PTFE) backbone with a fully perfluorinated ether side chain terminated by the strongly hydrophilic -SO 3 H group. This leads to spontaneous phase segregation at the nano-structural level. For fully hydrated PFSA, the sulfonic groups and water develop an interconnected proton conducting network while the fluorocarbon backbone forms a semicrystalline hydrophobic phase. Further improvements in PEM performance for fuel cell applications require increasing the proton conductivity at low relative humidity (RH) and high temperature [1]. A detailed knowledge of the nano-scale morphology would be useful in reaching this goal since ionomer morphology determines the network connectivity of the membrane that strongly influences its conductivity.A thorough review by Mauritz and Moore[2] summarizes the efforts in the last two decades to understand the morphology of Nafion. Based on variety of scattering experiments, various models have been suggested, such as cluster-channel model [3], core-shell model [4], lamellar model[5], sandwich-like model[6], channel model [7], and rod-like model. [8]. The common feature of all these models is the nano-phase segregation into hydrophilic and hydrophobic domains, but the detailed shape and structure of the ionic clusters and semicrystalline polymeric matrix remains unresolved. Direct TEM and AFM[9], [11] observations are mainly consistent with the three-phase model originally suggested by Yeager et al. [10], consisting of water...

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