6 research outputs found

    SYNthesis DESIGN OF POLYSTYRENE BASED ANION EXCHANGE MEMBRANES: STUDY ON RELATIONSHIP BETWEEN CHEMICAL AND MORPHOLOGICAL STRUCTURES AND PROPERTIES IN ALKALINE FUEL CELL CONDITIONS

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    Anion exchange membrane fuel cells (AEMFCs) are an alternative renewable energy source with potential benefits including use of non-precious metal catalysts, facile electro-kinetics, and high power density. Despite these advantages, development of chemically robust and highly conductive anion exchange membranes (AEMs) is the great challenge. The properties of polymeric AEMs depend on many parameters, for example, backbone structures, morphology of membranes, and chemical stability of the ion transporting group. Therefore, all of these interconnected parameters have to be addressed and studied for AEM development. The objectives of this dissertation are 1) to develop durable membranes with high anion conductivity by cost effective materials and methods, and 2) to understand the structure-property relationship by designing polymer structures and membrane morphology. To achieve these goals, the presented research focuses on development of polystyrene (PS) based AEMs by the post-crosslinking method using the click reaction. The first work of this dissertation (chapter 2) was to establish a facile and effective AEM fabrication method. AEMs with optimized ion exchange capacity (IEC) and degree of crosslinking showed the improvement of electrochemical properties and fuel cell performance. Different PS architectures including block and random copolymers with the benchmark cation for AEM, benzyltrimethylammonium (BTMA), were designed and synthesized in our next step (chapter 3). The focus in this particular series was to study the effect of membrane morphology on ion conductive properties. Significant differences were observed between random and block copolymer based AEMs. The nano-scale ordered morphology of the block membranes led to satisfactory ion transport properties as well as improved durability of the membranes. Furthermore, the fuel cell test revealed that the block membranes maintained superior performance after multiple polarization curves in comparison with one of the best commercial AEMs (A201). The stability of cations is another crucial subject for AEM progress. Therefore, a novel AEM with phenyltrimethylammonium (PTMA) was fabricated from the PS based block copolymer, which was designed to avoid cation degradation through the elimination and nucleophilic substitution reactions (chapter 4). The preliminary data indicated that this novel AEM had higher thermal and chemical stability than the BTMA based AEM with similar structure

    The negative cofactor 2 complex is a key regulator of drug resistance in Aspergillus fumigatus

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    The frequency of antifungal resistance, particularly to the azole class of ergosterol biosynthetic inhibitors, is a growing global health problem. Survival rates for those infected with resistant isolates are exceptionally low. Beyond modification of the drug target, our understanding of the molecular basis of azole resistance in the fungal pathogen Aspergillus fumigatus is limited. We reasoned that clinically relevant antifungal resistance could derive from transcriptional rewiring, promoting drug resistance without concomitant reductions in pathogenicity. Here we report a genome-wide annotation of transcriptional regulators in A. fumigatus and construction of a library of 484 transcription factor null mutants. We identify 12 regulators that have a demonstrable role in itraconazole susceptibility and show that loss of the negative cofactor 2 complex leads to resistance, not only to the azoles but also the salvage therapeutics amphotericin B and terbinafine without significantly affecting pathogenicity

    Fecal Iron Measurement in Studies of the Human Intestinal Microbiome

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    Iron is an essential micronutrient for humans and their intestinal microbiota. Host intestinal cells and iron-dependent bacteria compete for intraluminal iron, so the composition and functions of the gut microbiota may influence iron availability. Studies of the effects of the microbiota or probiotic interventions on host iron absorption may be particularly relevant to settings with high burdens of iron deficiency and gastrointestinal infections, since inflammation reduces iron bioavailability and unabsorbed intraluminal iron may modify the composition of the microbiota. The quantification of stool iron content may serve as an indicator of the amount of intraluminal iron to which the intestinal microbiota is exposed, which is particularly relevant for studies of the effect of iron on the intestinal microbiome, where fecal samples collected for purposes of microbiome characterization can be leveraged for stool iron analysis. However, few studies are available to guide researchers in the selection and implementation of stool iron assays, particularly because cross-comparison of available methods is limited in literature. This review aims to describe the available stool iron quantification methods and highlight their potential application in studies of iron–microbiome relationships, with a focus on pediatric research. MS-based methods offer high sensitivity and precision, but the need for expensive equipment and the high per-sample and maintenance costs may limit their widespread use. Conversely, colorimetric assays offer lower cost, ease of use, and rapid turnaround times but have thus far been optimized primarily for blood-derived matrices rather than stool. Further research efforts are needed to validate and standardize methods for stool iron assessment and to determine if the incorporation of such analyses in human microbiome studies 1) yields insights into the interactions between intestinal microbiota and iron and 2) contributes to the development of interventions that mitigate iron deficiency and promote a healthy microbiome

    Learning Active Implementation Frameworks: the role of implementation teams in a case study from Pakistan

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    In Pakistan, although coverage of Maternal, Newborn, and Child Health (MNCH) services has increased, the attributable disease burden remains high, indicating quality of these services remains suboptimal. To address this quality gap, challenges associated with the implementation of MNCH services will need to be addressed and effective use of the various MNCH guidelines will need to be supported, evaluated, and continuously improved. Even though the application of the field of implementation science and practice in the low- and middle-income settings has been limited, it is our belief, based on the experience described in this article that these competencies could enhance health professionals’ ability to, not only successfully integrate MNCH guidelines into health systems, but to also support their effective and sustainable use. To address this capacity gap in Pakistan, the Health Services Academy, as a member of the World Health Organization’s Human Reproduction Program (HRP) Alliance for Research Capacity Strengthening (RCS), has engaged, over the course of 16 months, in the ‘Implementation for the Professional Learner Program’ in 2019. This innovative implementation science and practice capacity-building program is developed and conducted by The World Health Organization (WHO) Collaborating Centre for Research Evidence for Sexual and Reproductive Health at the University of North Carolina at Chapel Hill (UNC). The initial cohort of this Program also included Palestine’s West Bank, and Egypt. The objectives of this Program were to cultivate implementation science and practice competencies, and to support the development of national, community-based or institution-based implementation teams. The expected outcomes of this program included, further enhancement of the capacity of local health professionals in implementation science, systemic change and the effective use of innovations in practice at sub-national/regional levels
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