2,429 research outputs found

    CMC Spheres in the Heisenberg Group

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    We study a family of spheres with constant mean curvature (CMC) in the Riemannian Heisenberg group H1. These spheres are conjectured to be the isoperimetric sets of H1. We prove several results supporting this conjecture. We also focus our attention on the sub-Riemannian limit

    Anatomy, Chloroplast Structure and Compartmentation of Enzymes Relative to Photosynthetic Mechanisms in Leaves and Cotyledons of Species in the Tribe Salsoleae (Chenopodiaceae)

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    Certain members of the family Chenopodiaceae are the dominant species of the deserts of Central Asia; many of them are succulent halophytes which exhibit C4-type CO2 fixation of the NAD- or NADP-ME (malic enzyme) subgroup. In four C4 species of the tribe Salsoleae, the Salsoloid-type Kranz anatomy in leaves or stems was studied in relation to the diversity in anatomy which was found in cotyledons. Halocharis gossypina, has C4 NAD-ME Salsoloid-type photosynthesis in leaves and C3 photosynthesis in dorsoventral non-Kranz cotyledons; Salsola laricina has C4 NAD-ME Salsoloid-type leaves and C4 NAD-ME Atriplicoid-type cotyledons; Haloxylon persicum, has C4 NADP-ME Salsoloid-type green stems and C3 isopalisade non-Kranz cotyledons; and S. richteri has C4 NADP-ME Salsoloid-type leaves and cotyledons. Immunolocalization studies on Rubisco showed strong labelling in bundle sheath cells of leaves and cotyledons of organs having Kranz anatomy. The C4 pathway enzyme phosphoenolpyruvate carboxylase was localized in mesophyll cells, while the malic enzymes were localized in bundle sheath cells of Kranz-type tissue. Immunolocalization by electron microscopy showed NAD-ME is in mitochondria while NADP-ME is in chloroplasts of bundle sheath cells in the respective C4 types. In some C4 organs, it was apparent that subepidermal cells and water storage cells also contain some chloroplasts which have Rubisco, store starch, and thus perform C3 photosynthesis. In non-Kranz cotyledons of Halocharis gossypina and Haloxylon persicum, Rubisco was found in chloroplasts of both palisade and spongy mesophyll cells with the heaviest labelling in the layers of palisade cells, whereas C4 pathway proteins were low or undetectable. The pattern of starch accumulation correlated with the localization of Rubisco, being highest in the bundle sheath cells and lowest in the mesophyll cells of organs having Kranz anatomy. In NAD-ME-type Kranz organs (leaves and cotyledons of S. laricina and leaves of H. gossypina) the granal index (length of appressed membranes as a percentage of total length of all membranes) of bundle sheath chloroplasts is 1.5 to 2.5 times higher than that of mesophyll chloroplasts. In contrast, in the NADP-ME-type Kranz organs (S. richteri leaves and cotyledons and H. persicum stems) the granal index of mesophyll chloroplasts is 1.5 to 2.2 times that of the bundle sheath chloroplasts. The mechanism of photosynthesis in these species is discussed in relation to structural differences.This work was partly supported by Civilian Research and Development Foundation Grant RB1–264 and NSF Grant IBN-9807916. EV Voznesenskaya would like to thank CIES, Washington DC for a Fulbright Scholar Research Fellowship. We also thank the Electron Microscope Center of Washington State University for use of their facilities and staff assistance

    Biopolymers for a more sustainable leather

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    Content: A novel class of bio-based polymers have been developed within the LIFE BIOPOL European project aiming to replace traditional re-tanning and fat-liquoring products reducing environmental impacts and increasing the safety of leather. The purpose of the project is to enhance the recovery and reuse of different bio-derived by-products from leather and agro-industrial sector to produce eco-friendly and renewable bio-polymers with high re-tanning and fat-liquoring characteristics. The LIFE BIOPOL project aims to make bio-based polymers in order to reduce the following parameters in re-tanning phase: - 20-30% COD, - 50-60% of inorganic salts (Sulphates and Chlorides), - 90% of Cr (III) salts, - 20% of water used in the leather process. Other important goals of the project are: - reduction 70-90% of hazardous and environmental polluting substances normally found in conventional chemicals, - reactivity enhancement of 30-40% of the new biopolymers compared to the current leather - application technology, - reduction of 70-80% of the Product Environmental Footprint of the new biopolymers related to the state of the art. The vegetal biomasses and the tanned hides by-products were pretreated in order to obtain suitable building blocks for the production of bio-based polymers. Several protocols involving polymerization were used in order to achieve the synthesis of the biopolymers, which have been carried out at lab scale. Macromolecular characterization of the biopolymers was performed in order to rationalize the synthetic strategy and practical application of the products giving important parameters such as molecular weight and chemical composition of the new biopolymers. Performances of new bio-based polymers have been inspected and compared with traditional chemicals through application on different types of leather. The benefits of the new products within leather making process were evaluated through chemical analyses of re-tanning and fat-liquoring effluents. The upgrade of the developed chemistry will be performed within a new devised prototype plant specifically designed and built-up for producing the bio-based polymers at industrial scale Take-Away: Production of leather making biopolymers from biomasses and industrial by-products through Life Cycle Designed Processe

    Charge localization and reentrant superconductivity in a quasi-ballistic InAs nanowire coupled to superconductors

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    A semiconductor nanowire with strong spin-orbit coupling in proximity to a superconductor is predicted to display Majorana edge states emerging under a properly oriented magnetic field. The experimental investigation of these exotic states requires assessing the one-dimensional (1D) character of the nanowire and understanding the superconducting proximity effect in the presence of a magnetic field. Here, we explore the quasi-ballistic 1D transport regime of an InAs nanowire with Ta contacts. Fine-tuned by means of local gates, the observed plateaus of approximately quantized conductance hide the presence of a localized electron, giving rise to a lurking Coulomb blockade effect and Kondo physics. When Ta becomes superconducting, this local charge causes an unusual, reentrant magnetic field dependence of the supercurrent, which we ascribe to a 0 - p transition. Our results underline the relevant role of unintentional charge localization in the few-channel regime where helical subbands and Majorana quasi-particles are expected to ariseWe acknowledge financial support from the Agence Nationale de la Recherche (TOPONANO project) and from the EU (ERC grant no. 280043). R.A. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (grant FIS2015-64654-P). R.Ž. acknowledges support from the Slovenian Research Agency (ARRS) under Program P1- 0044 and J1-725

    A recombinant bovine herpesvirus-4 vectored vaccine delivered via intranasal nebulization elicits viral neutralizing antibody titers in cattle

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    Recombinant herpesvirus vaccine vectors offer distinct advantages in next-generation vaccine development, primarily due to the ability to establish persistent infections to provide sustainable antigen responses in the host. Recombinant bovine herpesvirus-4 (BoHV-4) has been previously shown to elicit protective immunity in model laboratory animal species against a variety of pathogens. For the first time, we describe the induction of antigen-specific immune responses to two delivered antigens in the host species after intranasal nebulization of recombinant BoHV-4 expressing the chimeric peptide containing the bovine viral diarrhea virus (BVDV) glycoprotein E2 and the bovine herpesvirus 1 (BoHV-1) glycoprotein D (BoHV-4-A-CMV-IgK-gE2gD-TM). In this study, four cattle were immunized via intranasal nebulization with the recombinant BoHV-4 construct. Two of the cattle were previously infected with wild-type BoHV-4, and both developed detectable serologic responses to BVDV and BoHV-1. All four immunized cattle developed detectable viral neutralizing antibody responses to BVDV, and one steer developed a transient viral neutralizing response to BoHV-1. Approximately one year after immunization, immunosuppressive doses of the glu-cocorticoid dexamethasone were administered intravenously to all four cattle. Within two weeks of immunosuppression, all animals developed viral neutralizing antibody responses to BoHV-1, and all animals maintained BVDV viral neutralizing capacity. Overall, nebulization of BoHV-4-A-CMV-IgK-gE2gD-TM persistently infects cattle, is capable of eliciting antigen-specific immunity following immunization, including in the presence of pre-existing BoHV-4 immunity, and recrudescence of the virus boosts the immune response to BoHV-4-vectored antigens. These results indicate that BoHV-4 is a viable and attractive vaccine delivery platform for use in cattle
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