1,359 research outputs found

    Towards Understanding Photodegradation Pathways in Lignins:The Role of Intramolecular Hydrogen Bonding in Excited States

    Get PDF
    The photoinduced dynamics of the lignin building blocks syringol, guaiacol, and phenol were studied using time-resolved ion yield spectroscopy and velocity map ion imaging. Following irradiation of syringol and guaiacol with a broad-band femtosecond ultraviolet laser pulse, a coherent superposition of out-of-plane OH torsion and/or OMe torsion/flapping motions is created in the first excited 1ππ* (S1) state, resulting in a vibrational wavepacket, which is probed by virtue of a dramatic nonplanar → planar geometry change upon photoionization from S1 to the ground state of the cation (D0). Any similar quantum beat pattern is absent in phenol. In syringol, the nonplanar geometry in S1 is pronounced enough to reduce the degree of intramolecular H bonding (between OH and OMe groups), enabling H atom elimination from the OH group. For guaiacol, H bonding is preserved after excitation, despite the nonplanar geometry in S1, and prevents O–H bond fission. This behavior affects the propensities for forming undesired phenoxyl radical sites in these three lignin chromophores and provides important insight into their relative “photostabilities” within the larger biopolymer

    Sustainable Agriculture

    Get PDF
    The Sustainable Agriculture team is dedicated to developing alternative and sustainable agricultural solutions to alleviate poverty in western Africa. The team is currently working with Sheltering Wings in Yako, Burkina Faso and Trans World Radio in Parakou, Benin. Both clients currently have a working aquaponics system, but the type of system varies between clients. Sheltering Wings has a flood and drain system and Trans World Radio has an ebb and flow system. Throughout this year, our team has focused on reducing power consumption and costs for our clients. The development of the ebb and flow prototype was a consequence of this mission as we reduced power consumption by one pump using a manual siphon. We have also worked towards lowering the costs of water quality testing kits by introducing a Nutrient Film Technique with basil plants. Lastly, we have strived to research best practice methods for fish food making and fish feeding in order to keep the biology of the prototypes healthy. To support present and future clients, the year will conclude with final deliverables for the ebb and flow prototype including an operations and maintenance manual, a construction manual, and a troubleshooting manual.https://mosaic.messiah.edu/engr2021/1016/thumbnail.jp

    Overscreening and Underscreening in Solid-Electrolyte Grain Boundary Space-Charge Layers

    Get PDF
    Polycrystalline solids can exhibit material properties that differ significantly from those of equivalent single-crystal samples, in part, because of a spontaneous redistribution of mobile point defects into so-called space-charge regions adjacent to grain boundaries. The general analytical form of these space-charge regions is known only in the dilute limit, where defect-defect correlations can be neglected. Using kinetic Monte Carlo simulations of a three-dimensional Coulomb lattice gas, we show that grain-boundary space-charge regions in non-dilute solid electrolytes exhibit overscreening -- damped oscillatory space-charge profiles -- and underscreening -- decay lengths that are longer than the corresponding Debye length and that increase with increasing defect-defect interaction strength. Overscreening and underscreening are known phenomena in concentrated liquid electrolytes, and the observation of functionally analogous behaviour in solid electrolyte space-charge regions suggests that the same underlying physics drives behaviour in both classes of systems. We therefore expect theoretical approaches developed to study non-dilute liquid electrolytes to be equally applicable to future studies of solid electrolytes

    HIV-1 transgene expression in rats causes oxidant stress and alveolar epithelial barrier dysfunction

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>HIV-infected individuals are at increased risk for acute and chronic airway disease even though there is no evidence that the virus can infect the lung epithelium. Although HIV-related proteins including gp120 and Tat can directly cause oxidant stress and cellular dysfunction, their effects in the lung are unknown. The goal of this study was to determine the effects of HIV-1 transgene expression in rats on alveolar epithelial barrier function. Alveolar epithelial barrier function was assessed by determining lung liquid clearance <it>in vivo </it>and alveolar epithelial monolayer permeability <it>in vitro</it>. Oxidant stress in the alveolar space was determined by measuring the glutathione redox couple by high performance liquid chromatography, and the expression and membrane localization of key tight junction proteins were assessed. Finally, the direct effects of the HIV-related proteins gp120 and Tat on alveolar epithelial barrier formation and tight junction protein expression were determined.</p> <p>Results</p> <p>HIV-1 transgene expression caused oxidant stress within the alveolar space and impaired epithelial barrier function even though there was no evidence of overt inflammation within the airways. The expression and membrane localization of the tight junction proteins zonula occludens-1 and occludin were decreased in alveolar epithelial cells from HIV-1 transgenic rats. Further, treating alveolar epithelial monolayers from wild type rats <it>in vitro </it>with recombinant gp120 or Tat for 24 hours reproduced many of the effects on zonula occludens-1 and occludin expression and membrane localization.</p> <p>Conclusion</p> <p>Taken together, these data indicate that HIV-related proteins cause oxidant stress and alter the expression of critical tight junction proteins in the alveolar epithelium, resulting in barrier dysfunction.</p

    Geologic Interpretation of Data Sets Collected by Planetary Analog Geology Traverses and by Standard Geologic Field Mapping

    Get PDF
    Geologic maps integrate the distributions, contacts, and compositions of rock and sediment bodies as a means to interpret local to regional formative histories. Applying terrestrial mapping techniques to other planets is challenging because data is collected primarily by orbiting instruments, with infrequent, spatiallylimited in situ human and robotic exploration. Although geologic maps developed using remote data sets and limited "Apollo-style" field access likely contain inaccuracies, the magnitude, type, and occurrence of these are only marginally understood. This project evaluates the interpretative and cartographic accuracy of both field- and remote-based mapping approaches by comparing two 1:24,000 scale geologic maps of the San Francisco Volcanic Field (SFVF), north-central Arizona. The first map is based on traditional field mapping techniques, while the second is based on remote data sets, augmented with limited field observations collected during NASA Desert Research & Technology Studies (RATS) 2010 exercises. The RATS mission used Apollo-style methods not only for pre-mission traverse planning but also to conduct geologic sampling as part of science operation tests. Cross-comparison demonstrates that the Apollo-style map identifies many of the same rock units and determines a similar broad history as the field-based map. However, field mapping techniques allow markedly improved discrimination of map units, particularly unconsolidated surficial deposits, and recognize a more complex eruptive history than was possible using Apollo-style data. Further, the distribution of unconsolidated surface units was more obvious in the remote sensing data to the field team after conducting the fieldwork. The study raises questions about the most effective approach to balancing mission costs with the rate of knowledge capture, suggesting that there is an inflection point in the "knowledge capture curve" beyond which additional resource investment yields progressively smaller gains in geologic knowledge

    Comparative Genomic Landscape of Urothelial Carcinoma of the Bladder Among Patients of East and South Asian Genomic Ancestry

    Get PDF
    BACKGROUND: Despite the low rate of urothelial carcinoma of the bladder (UCB) in patients of South Asian (SAS) and East Asian (EAS) descent, they make up a significant portion of the cases worldwide. Nevertheless, these patients are largely under-represented in clinical trials. We queried whether UCB arising in patients with SAS and EAS ancestry would have unique genomic features compared to the global cohort. METHODS: Formalin-fixed, paraffin-embedded tissue was obtained for 8728 patients with advanced UCB. DNA was extracted and comprehensive genomic profiling was performed. Ancestry was classified using a proprietary calculation algorithm. Genomic alterations (GAs) were determined using a 324-gene hybrid-capture-based method which also calculates tumor mutational burden (TMB) and determines microsatellite status (MSI). RESULTS: Of the cohort, 7447 (85.3%) were EUR, 541 (6.2%) were AFR, 461 (5.3%) were of AMR, 74 (0.85%) were SAS, and 205 (2.3%) were EAS. When compared with EUR, TERT GAs were less frequent in SAS (58.1% vs. 73.6%; P = .06). When compared with non-SAS, SAS had less frequent GAs in FGFR3 (9.5% vs. 18.5%, P = .25). TERT promoter mutations were significantly less frequent in EAS compared to non-EAS (54.1% vs. 72.9%; P \u3c .001). When compared with the non-EAS, PIK3CA alterations were significantly less common in EAS (12.7% vs. 22.1%, P = .005). The mean TMB was significantly lower in EAS vs. non-EAS (8.53 vs. 10.02; P = .05). CONCLUSIONS: The results from this comprehensive genomic analysis of UCB provide important insight into the possible differences in the genomic landscape in a population level. These hypothesis-generating findings require external validation and should support the inclusion of more diverse patient populations in clinical trials
    • …
    corecore