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1. Coating small-diameter ePTFE vascular grafts with tunable poly(diol- co -citrate- co -ascorbate) elastomers to reduce neointimal hyperplasia

   https://doi.org/10.1039/D1BM00101A  

   Yu, Lu; Newton, Emily R.; Gillis, David C.; Sun, Kui; Cooley, Brian C.; Keith, Andrew N.; Sheiko, Sergei S.; Tsihlis, Nick D.; Kibbe, Melina R. (July 2021, Biomaterials Science)

   null (Ed.)

   Lack of long-term patency has hindered the clinical use of small-diameter prosthetic vascular grafts with the majority of these failures due to the development of neointimal hyperplasia. Previous studies by our laboratory revealed that small-diameter expanded polytetrafluoroethylene (ePTFE) grafts coated with antioxidant elastomers are a promising localized therapy to inhibit neointimal hyperplasia. This work is focused on the development of poly(diol- co -citrate- co -ascorbate) (POCA) elastomers with tunable properties for coating ePTFE vascular grafts. A bioactive POCA elastomer (@20 : 20 : 8, [citrate] : [diol] : [ascorbate]) coating was applied on a 1.5 mm diameter ePTFE vascular graft as the most promising therapeutic candidate for reducing neointimal hyperplasia. Surface ascorbate density on the POCA elastomer was increased to 67.5 ± 7.3 ng mg −1 cm −2 . The mechanical, antioxidant, biodegradable, and biocompatible properties of POCA demonstrated desirable performance for in vivo use, inhibiting human aortic smooth muscle cell proliferation, while supporting human aortic endothelial cells. POCA elastomer coating number was adjusted by a modified spin-coating method to prepare small-diameter ePTFE vascular grafts similar to natural vessels. A significant reduction in neointimal hyperplasia was observed after implanting POCA-coated ePTFE vascular grafts in a guinea pig aortic interposition bypass graft model. POCA elastomer thus offers a new avenue that shows promise for use in vascular engineering to improve long-term patency rates by coating small-diameter ePTFE vascular grafts. 

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2. A temporal shift in resource allocation facilitates flowering before leaf out and spring vessel maturation in precocious species

   https://doi.org/10.1002/ajb2.1222  

   Savage, Jessica_A (January 2019, American Journal of Botany)

   Premise of the StudyNew growth in the spring requires resource mobilization in the vascular system at a time when xylem and phloem function are often reduced in seasonally cold climates. As a result, the timing of leaf out and/or flowering could depend on when the vascular system resumes normal function in the spring. This study investigated whether flowering time is influenced by vascular phenology in plants that flower precociously before they have leaves. MethodsFlower, leaf, and vascular phenology were monitored in pairs of precocious and non‐precocious congeners. Differences in resource allocation were quantified by measuring bud dry mass and water content throughout the year, floral hydration was modelled, and a girdling treatment completed on branches in the field. Key ResultsPrecocious flowering species invested more in floral buds the year before flowering than did their non‐precocious congeners, thus mobilizing less water in the spring, which allowed flowering before new vessel maturation. ConclusionsA shift in the timing of resource allocation in precocious flowering plants allowed them to flower before the production of mature vessels and minimized the significance of seasonal changes in vascular function to their flowering phenology. The low investment required to complete floral development in the spring when the plant vascular system is often compromised could explain why flowers can emerge before leaf out. 

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3. Anatomical and biophysical basis for graft incompatibility within the Solanaceae

   https://doi.org/10.1093/jxb/erad155  

   Thomas, Hannah R.; Gevorgyan, Alice; Frank, Margaret H.; Bartlett, ed., Madelaine (April 2023, Journal of Experimental Botany)

   Abstract Interspecies grafting is an economically relevant technique that allows beneficial shoot and root combinations from separate species to be combined. One hypothesis for the basis of graft compatibility revolves around taxonomic relatedness. To test how phylogenetic distance affects interspecific graft compatibility within the economically important Solanaceae subfamily, Solanoideae, we characterized the anatomical and biophysical integrity of graft junctions between four species: tomato (Solanum lycopersicum), eggplant (Solanum melongena), pepper (Capsicum annuum), and groundcherry (Physalis pubescens). We analyzed the survival, growth, integrity, and cellular composition of the graft junctions. Utilizing various techniques, we were able to quantitatively assess compatibility among the interspecific grafts. Even though most of our graft combinations could survive, we show that only intrageneric combinations between tomato and eggplant are compatible. Unlike incompatible grafts, the formation of substantial vascular reconnections between tomato and eggplant in the intrageneric heterografts likely contributed to biophysically stable grafts. Furthermore, we identified 10 graft combinations that show delayed incompatibility, providing a useful system to pursue deeper work into graft compatibility. This work provides new evidence that graft compatibility may be limited to intrageneric combinations within the Solanoideae subfamily. Further research amongst additional Solanaceous species can be used to test the extent to which our hypothesis applies to this family. 

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4. Coordination of spring vascular and organ phenology in deciduous angiosperms growing in seasonally cold climates

   https://doi.org/10.1111/nph.17289  

   Savage, Jessica A.; Chuine, Isabelle (March 2021, New Phytologist)

   Summary In seasonally cold climates, many woody plants tolerate chilling and freezing temperatures by ceasing growth, shedding leaves and entering dormancy. At the same time, transport within these plants often decreases as the vascular system exhibits reduced functionality. As spring growth requires water and nutrients, we ask the question: how much does bud, leaf and flower development depend on the vasculature in spring? In this review, we present what is known about leaf, flower and vascular phenology to sort out this question. In early stages of bud development, buds rely on internal resources and do not appear to require vascular support. The situation changes during organ expansion, after leaves and flowers reconnect to the stem vascular system. However, there are major gaps in our understanding of the timing of vascular development, especially regarding the phloem, as well as the synchronization among leaves, flowers, stem and root vasculature. We believe these gaps are mainly the outcome of research completed in silo and urge future work to take a more integrative approach. We highlight current challenges and propose future directions to make rapid progress on this important topic in upcoming years. 

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5. The role of surface morphology on nucleation density limitation during the CVD growth of graphene and the factors influencing graphene wrinkle formation

   https://doi.org/10.1557/adv.2020.73  

   Withanage, Sajith; Nanayakkara, Tharanga; Wijewardena, U. Kushan; Kriisa, Annika; Mani, R. G. (January 2019, MRS Advances)

   ABSTRACT CVD graphene growth typically uses commercially available cold-rolled copper foils, which includes a rich topography with scratches, dents, pits, and peaks. The graphene grown on this topography, even after annealing the foil, tends to include and reflect these topographic features. Further, the transfer of such CVD graphene to a flat substrate using a polymer transfer method also introduces wrinkles. Here, we examine an electropolishing technique for reducing native foil defects, characterize the resulting foil surface, grow single-crystal graphene on the polished foil, and examine the quality of the graphene for such defects. 

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