58 research outputs found

    Porogen Concentration Effect on the Pore Structure and Properties Evolution of Polymer Monolith Based on Oligocarbonate Dimethacrylate OCM-2

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    Porous polymer monolith materials of 2-mm thickness were obtained by visible light-induced radical polymerization of oligocarbonate dimethacrylate (OCM-2) in the presence of 1-butanol (10 to 70 wt %) as a porogenic additive. The pore characteristics and morphology of polymers were studied by mercury intrusion porosimetry and scanning electron microscopy. Monolithic polymers with both open and closed pores up to 100 nm in size are formed when the alcohol content in the initial composition is up to 20 wt %. The pore structure in such materials is a system of holes in the bulk of the polymer (hole-type pores). Open interconnected pores with a specific volume up to 2.22 cm3/g and modal pore size up to 10 microns are formed in the volume of the polymer with 1-butanol content of more than 30 wt %. Such porous monoliths are a structure of covalently bonded polymer globules (interparticle-type pores). The free space between the globules represents a system of open interconnected pores. In the transition region of 1-butanol concentrations (from 20 to 30 wt %), areas with both structures and intermediate frameworks, as well as honeycomb structures of polymer globules connected by bridges, are fixed on the polymer surface. It was found that the transition from one type of pore system to another is accompanied by a sharp change in the strength characteristics of the polymer. Approximation of experimental data using the sigmoid function made it possible to determine the concentration of the porogenic agent in the vicinity of which the percolation threshold is observed

    Lichens of the Innvika Bay, Prins Oscars Land (Nordaustlandet, Svalbard)

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    The paper presents a list of lichens for the Innvika Bay, which includes 157 lichenized and 2 lichenicolous fungi. Alectoria gowardii and Peltigera elisabethae are new to Svalbard. Furthermore, 36 other species were found new to Nordaustlandet. Twenty-seven species are rare on Svalbard, among them Aspilidea myrinii, Candelariella borealis, Gyalecta erythrozona, Miriquidica deusta, Rhizocarpon viridiatrum (reported for the second time), and Aspicilia cinerea, Cetraria nigricans, Cladonia arbuscula, Cystocoleus ebeneus, Lecidea ecrustacea, Peltigera frippii, Rhizocarpon eupetraeoides, Rinodina terrestris, Stereocaulon cumulatum, Toninia squalida, Verrucaria hydrela. Localities, substrates and distribution in Svalbard are given for each species. For rare and extremely rare species, all known locations are given. For some species, differences from closely related species are given

    Benzylidene Cyclopentanone Derivative Photoinitiator for Two-Photon Photopolymerization-Photochemistry and 3D Structures Fabrication for X-ray Application

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    Micron- and submicron-scale 3D structure realization nowadays is possible due to the two-photon photopolymerization (TPP) direct laser writing photolithography (DLW photolithography) method. However, the achievement of lithographic features with dimensions less than 100 nm is in demand for the fabrication of micro-optical elements with high curvature values, including X-ray microlenses. Spectroscopic and photochemical study of a photoinitiator (PI) based on a methyl methacrylate derivative of 2,5-bis(4-(dimethylamino)benzylidene) cyclopentanone was performed. Enhanced intersystem crossing in the methyl methacrylate derivative results in increased radical generation for the subsequent initiation of polymerization. A comprehensive study of the new photocompositions was performed, with particular emphasis on photochemical constants, the degree of photopolymerization, and topology. The optimal parameters for the fabrication of mechanically stable structures were determined in this research. The threshold dose parameters for lithography (radiation power of 5 mW at a speed of 180 ¬Ķm/s) when trying to reach saturation values with a conversion degree of (35 ¬Ī 1) % were defined, as well as parameters for sub-100 nm feature fabrication. Moreover, the 45 nm feature size for elements was reached. Fabrication of X-ray lens microstructures was also demonstrated

    Heterologous Expression of Xylanase xAor from Aspergillus oryzae in Komagataella phaffii T07

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    Xylanases (EC 3.2.1.8) hydrolyze the hemicellulose of plant cell walls. Xylanases are used in the food and paper industries and for bioconversion of lignocellulose to biofuel. In this work, the producer-strain with four copies of the xAor xylanase gene was organized in two tandem copies for optimal expression in Komagataella phaffii T07 yeast. The secreted 35 kDa xylanase was purified from culture medium by gel filtration on Sephadex G-25 and anion exchange chromatography on DEAE-Sepharose 6HF. Tryptic peptides of the recombinant enzyme were analyzed by liquid chromatography-tandem mass spectrometry where the amino acid sequence corresponded to Protein Accession # O94163 for Endo-1,4-beta-xylanase from Aspergillus oryzae RIB40. The recombinant xylanase was produced in a bioreactor where the secreted enzyme hydrolyzed oat xylane with an activity of 258240 IU/mL. High activity in the culture medium suggested xylanase could be used for industrial applications without being purified or concentrated. The pH optimum for xylanase xAor was 7.5, though the enzyme was active from pH 2.5 to pH 10. Xylanase was active at temperatures from 35 °C to 85 °C with a maximum at 60 °C. In conclusion, this protocol yields soluble, secreted xylanase suitable for industrial scale production

    Addition to the lichen biota of Franz Josef Land archipelago

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    Forty-four new lichen species and one lichenicolous fungus have been identified as a result of studies of the lichen biota of the Franz Josef Land archipelago. Bryocaulon hyperboreum was reported for the first time from Russia. Gyalecta hypoleuca and Umbilicaria maculata were first identified in the Arctic. Arctocetraria andrejevii, Brodoa oroarctica, Candelariella borealis, Cercidospora stereocaulorum, Massalongia carnosa, Miriquidica nigroleprosa, M. plumbeoatra, Myriolecis zosterae var. palanderi and Polyblastia gothica are new to the Arkhangelsk Region; and Arthrorhaphis citrinella, Mycoblastus alpinus, Racodium rupestre, Rhizocarpon ferax, Scytinium intermedium, Stereocaulon glareosum are new to the Arctic part of the Arkhangelsk Region. Species new to Arkhangelsk Region, Arctic and Russia are supplied with information on distribution in neighboring regions and world and on differences from closely related species. The checklist of the Franz Josef Land archipelago thus includes 277 species and 6 varieties of lichenized and 43 lichenicolous fungi to date

    Flora of lichens, mosses and liverworts of Wrangel Island: New records

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    New records to lichen flora and bryoflora of Wrangel Island are presented. The additions to the island cryptogam flora include 32 lichens and one lichenicolous fungus, 26 mosses and eleven liverwort species. Acarospora sinopica, Alectoria gowardii, Austroplaca sibirica, Calogaya bryochrysion, Hymenelia ceracea, Porpidia ochrolemma, and Sagiolechia protuberans are new to the island and to the Russian Far East. Two lichen species (Lecidea lithophila and Rinodina terrestris), as well as two liverwort taxa (Clevea hyaline, Lophoziopsis excisa var. elegans and Pseudolophozia debiliformis), are new to the Chukotka Autonomous Area. Two of the reported moss species (Funaria arctica and Schistidium umbrosum) are extremely rare. Location data and ecological descriptions for the newly reported species are included

    Lichens of the Frankenhalv√łya Peninsula (Northern of Barents√łya, Svalbard)

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    This paper contributes to the studies on the lichen diversity of Barents√łya. It covers 211 species, of which four ( Buellia schaereri, Myriolecis zosterae var. palanderi, Rhizocarpon furfurosum, R. leptolepis) are reported for the first time for the Svalbard archipelago. Additionally, 84 of the species are reported for the first time for Barens√łya. Our study includes 2 subspecies as well, both new for Barents√łya. Thirty-six species (16.8% among the identified species) are rare in Svalbard, whereas more than two thirds (70.1% from identified in the Barens√łya) are relatively widespread species in Svalbard and the Arctic

    Assessment of Brassicaceae Seeds Quality by X-ray Analysis

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    A serious problem of vegetable production is the quality of sown seeds. In this regard, assessment of seed quality before sowing and storage is of great practical interest. The modern level of scientific research requires the use of instrumental automated methods of seed quality evaluation, allowing to obtain more information and in a shorter time. The material for the study was a variety of samples from the collection of Brassica oleracea L., var. capitata, Raphanus sativus L., var. radicula, and Lepidium sativum L. seeds from the Federal Scientific Center of Vegetable Breeding and the Timofeev Selection Station. Digital X-ray images of seeds were obtained using a mobile X-ray diagnostic device PRDU-02. Automatic analysis of digital X-ray images was performed in the software ‚ÄúVideoTesT-Morphology 5.2.‚ÄĚ The following latent defects of cabbage seeds of economic importance were revealed and identified: irregular darkening, significant ‚Äúpatterning‚ÄĚ with deep separation of embryo parts, ‚Äúangularity of seeds‚ÄĚ leading to the loss of their viability. Automatic analysis of digital X-ray images of seeds confirmed the informativeness of brightness indices of digital X-ray images, as well as shape indices. Their connection with sowing qualities of the studied seeds was established

    New records of lichens and allied fungi from the Leningrad Region, Russia. XI

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    Twelve lichen species and two lichenicolous fungi, of them seven that belong to Micarea prasina group, are reported for the first time for St. Petersburg or the whole Leningrad Region. The lichenicolous fungus Intralichen baccisporus is new to Russia, and the lichen Micarea nowakii ‚Äď for European Russia. A comparative table of characteristics for seven species of Micarea prasina group is presented

    The lichens of Pukhtolova Gora (St. Petersburg, Russia)

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    The lichen diversity of the proposed protected area Pukhtolova Gora counts 252 species, including 232 lichenized, 12 lichenicolous, and 8 non-lichenized saprobic fungi. Micarea laeta, M. pusilla, and Pyrenidium actinellum s. lat. are new to North-Western European Russia; Parmelia serrana, Rhizocarpon cinereovirens, and Stereocaulon taeniarum are new to St. Petersburg. Altogether 13 species recorded in the study area are red-listed in St. Petersburg, with two of them known only from historical collections. Pukhtolova Gora is an area with a high conservation value; the lichen biota of this area is one of the richest within the city limits due to the well-preserved forest habitats
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