25 research outputs found
Spin Down of Rotating Compact Magnetized Strange Stars in General Relativity
We find that in general relativity slow down of the pulsar rotation due to
the magnetodipolar radiation is more faster for the strange star with
comparison to that for the neutron star of the same mass. Comparison with
astrophysical observations on pulsars spindown data may provide an evidence for
the strange star existence and, thus, serve as a test for distinguishing it
from the neutron star.Comment: 6 pages; Accepted for publication in Astrophysics and Space Scienc
The type II-plateau supernova 2017eaw in NGC 6946 and its red supergiant progenitor
We present extensive optical photometric and spectroscopic observations, from 4 to 482 days after explosion, of the Type II-plateau (II-P) supernova (SN) 2017eaw in NGC 6946. SN 2017eaw is a normal SN II-P intermediate in properties between, for example, SN 1999em and SN 2012aw and the more luminous SN 2004et, also in NGC 6946. We have determined that the extinction to SN 2017eaw is primarily due to the Galactic foreground and that the SN site metallicity is likely subsolar. We have also independently confirmed a tip-of-the-red-giant-branch (TRGB) distance to NGC 6946 of 7.73 ± 0.78 Mpc. The distances to the SN that we have also estimated via both the standardized candle method and expanding photosphere method corroborate the TRGB distance. We confirm the SN progenitor identity in pre-explosion archival Hubble Space Telescope (HST) and Spitzer Space Telescope images, via imaging of the SN through our HST Target of Opportunity program. Detailed modeling of the progenitor's spectral energy distribution indicates that the star was a dusty, luminous red supergiant consistent with an initial mass of ~15 M ⊙
Fungal Planet description sheets : 1182–1283
Novel species of fungi described in this study include those from various countries as follows: Algeria,
Phaeoacremonium adelophialidum from Vitis vinifera. Antarctica, Comoclathris antarctica from soil. Australia,
Coniochaeta salicifolia as endophyte from healthy leaves of Geijera salicifolia, Eremothecium peggii in fruit of Citrus
australis, Microdochium ratticaudae from stem of Sporobolus natalensis, Neocelosporium corymbiae on stems of
Corymbia variegata, Phytophthora kelmanii from rhizosphere soil of Ptilotus pyramidatus, Pseudosydowia backhousiae
on living leaves of Backhousia citriodora, Pseudosydowia indooroopillyensis, Pseudosydowia louisecottisiae
and Pseudosydowia queenslandica on living leaves of Eucalyptus sp. Brazil, Absidia montepascoalis from soil.
Chile, Ilyonectria zarorii from soil under Maytenus boaria. Costa Rica, Colletotrichum filicis from an unidentified
fern. Croatia, Mollisia endogranulata on deteriorated hardwood. Czech Republic, Arcopilus navicularis from tea bag
with fruit tea, Neosetophoma buxi as endophyte from Buxus sempervirens, Xerochrysium bohemicum on surface
of biscuits with chocolate glaze and filled with jam. France, Entoloma cyaneobasale on basic to calcareous soil,
Fusarium aconidiale from Triticum aestivum, Fusarium juglandicola from buds of Juglans regia. Germany, Tetraploa
endophytica as endophyte from Microthlaspi perfoliatum roots. India, Castanediella ambae on leaves of Mangifera
indica, Lactifluus kanadii on soil under Castanopsis sp., Penicillium uttarakhandense from soil. Italy, Penicillium ferraniaense
from compost. Namibia, Bezerromyces gobabebensis on leaves of unidentified succulent, Cladosporium
stipagrostidicola on leaves of Stipagrostis sp., Cymostachys euphorbiae on leaves of Euphorbia sp., Deniquelata
hypolithi from hypolith under a rock, Hysterobrevium walvisbayicola on leaves of unidentified tree, Knufia hypolithi
and Knufia walvisbayicola from hypolith under a rock, Lapidomyces stipagrostidicola on leaves of Stipagrostis sp.,
Nothophaeotheca mirabibensis (incl. Nothophaeotheca gen. nov.) on persistent inflorescence remains of Blepharis
obmitrata, Paramyrothecium salvadorae on twigs of Salvadora persica, Preussia procaviicola on dung of Procavia
sp., Sordaria equicola on zebra dung, Volutella salvadorae on stems of Salvadora persica. Netherlands, Entoloma
ammophilum on sandy soil, Entoloma pseudocruentatum on nutrient poor (acid) soil, Entoloma pudens on
plant debris, amongst grasses. New Zealand, Amorocoelophoma neoregeliae from leaf spots of Neoregelia sp.,
Aquilomyces metrosideri and Septoriella callistemonis from stem discolouration and leaf spots of Metrosideros
sp., Cadophora neoregeliae from leaf spots of Neoregelia sp., Flexuomyces asteliae (incl. Flexuomyces gen. nov.)
and Mollisia asteliae from leaf spots of Astelia chathamica, Ophioceras freycinetiae from leaf spots of Freycinetia banksii, Phaeosphaeria caricis-sectae from leaf spots of Carex secta. Norway, Cuphophyllus flavipesoides on soil
in semi-natural grassland, Entoloma coracis on soil in calcareous Pinus and Tilia forests, Entoloma cyaneolilacinum
on soil semi-natural grasslands, Inocybe norvegica on gravelly soil. Pakistan, Butyriboletus parachinarensis on
soil in association with Quercus baloot. Poland, Hyalodendriella bialowiezensis on debris beneath fallen bark of
Norway spruce Picea abies. Russia, Bolbitius sibiricus on а moss covered rotting trunk of Populus tremula, Crepidotus
wasseri on debris of Populus tremula, Entoloma isborscanum on soil on calcareous grasslands, Entoloma
subcoracis on soil in subalpine grasslands, Hydropus lecythiocystis on rotted wood of Betula pendula, Meruliopsis
faginea on fallen dead branches of Fagus orientalis, Metschnikowia taurica from fruits of Ziziphus jujube, Suillus
praetermissus on soil, Teunia lichenophila as endophyte from Cladonia rangiferina. Slovakia, Hygrocybe fulgens
on mowed grassland, Pleuroflammula pannonica from corticated branches of Quercus sp. South Africa, Acrodontium
burrowsianum on leaves of unidentified Poaceae, Castanediella senegaliae on dead pods of Senegalia
ataxacantha, Cladophialophora behniae on leaves of Behnia sp., Colletotrichum cliviigenum on leaves of Clivia
sp., Diatrype dalbergiae on bark of Dalbergia armata, Falcocladium heteropyxidicola on leaves of Heteropyxis
canescens, Lapidomyces aloidendricola as epiphyte on brown stem of Aloidendron dichotomum, Lasionectria
sansevieriae and Phaeosphaeriopsis sansevieriae on leaves of Sansevieria hyacinthoides, Lylea dalbergiae on
Diatrype dalbergiae on bark of Dalbergia armata, Neochaetothyrina syzygii (incl. Neochaetothyrina gen. nov.) on
leaves of Syzygium chordatum, Nothophaeomoniella ekebergiae (incl. Nothophaeomoniella gen. nov.) on leaves of
Ekebergia pterophylla, Paracymostachys euphorbiae (incl. Paracymostachys gen. nov.) on leaf litter of Euphorbia
ingens, Paramycosphaerella pterocarpi on leaves of Pterocarpus angolensis, Paramycosphaerella syzygii on leaf
litter of Syzygium chordatum, Parateichospora phoenicicola (incl. Parateichospora gen. nov.) on leaves of Phoenix
reclinata, Seiridium syzygii on twigs of Syzygium chordatum, Setophoma syzygii on leaves of Syzygium sp., Starmerella
xylocopis from larval feed of an Afrotropical bee Xylocopa caffra, Teratosphaeria combreti on leaf litter of
Combretum kraussii, Teratosphaericola leucadendri on leaves of Leucadendron sp., Toxicocladosporium pterocarpi
on pods of Pterocarpus angolensis. Spain, Cortinarius bonachei with Quercus ilex in calcareus soils, Cortinarius brunneovolvatus under Quercus ilex subsp. ballota in calcareous soil, Extremopsis radicicola (incl. Extremopsis
gen. nov.) from root-associated soil in a wet heathland, Russula quintanensis on acidic soils, Tubaria vulcanica on
volcanic lapilii material, Tuber zambonelliae in calcareus soil. Sweden, Elaphomyces borealis on soil under Pinus
sylvestris and Betula pubescens. Tanzania, Curvularia tanzanica on inflorescence of Cyperus aromaticus. Thailand,
Simplicillium niveum on Ophiocordyceps camponoti-leonardi on underside of unidentified dicotyledonous leaf. USA,
Calonectria californiensis on leaves of Umbellularia californica, Exophiala spartinae from surface sterilised roots of
Spartina alterniflora, Neophaeococcomyces oklahomaensis from outside wall of alcohol distillery. Vietnam, Fistulinella
aurantioflava on soil. Morphological and culture characteristics are supported by DNA barcodes.http://www.ingentaconnect.com/content/nhn/pimjBiochemistryForestry and Agricultural Biotechnology Institute (FABI)GeneticsMicrobiology and Plant PathologyPlant Production and Soil Scienc
Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state
The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to γ-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the γ-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus. © 2012. The American Astronomical Society. All rights reserved
Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era
We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society
Photocatalytic properties of supramolecular nanoassociates based on gold and platinum nanoparticles, capped by amphiphilic calix[4]resorcinarenes, towards organic dyes
© 2020 Elsevier B.V. The synthesis of colloidal platinum nanoparticles (PtNPs) (dcore≈1-40 nm) in an aqueous solution was carried out using amido(dimethyl)amino- and carboxy- calix[4]resorcinarenes with alkyl substituents on the lower rim as stabilizer. The nanoparticles were characterized by spectrophotometry, IR, TEM, DLS, PXRD and SAXS. It was shown that PtNPs and gold nanoparticles (AuNPs) obtained, stabilized by calix[4]resorcinarenes, demonstrate the photocatalytic activity in the photodegradation of methyl orange and rhodamine B toxic dyes under visible light irradiation. The rate constants of catalytic reaction (K1, min−1) and activity of nanocatalysts (K2, min−1 mol−1) were calculated. It was found that size of metal core, structure of macrocycle stabilizing the surface of metal nanoparticles, its ability to form self-associates and bind dye molecules define the rate of dye photodegradation reaction. The study of the interaction of PtNPs and AuNPs capped with amidoamine macrocycles with organic photolinkers by spectrophotometry and fluorescence showed the binding of photolinkers by macrocycles, PtNPs and AuNPs. The photocatalytic activity of obtained cooperative nanoassociates was studied. The addition of photolinkers leads to both an increase and a decrease in the reaction rate, depending on the structure of linker and macrocycle. An increase in the reaction rate occurs due to the formation of photoactive supramolecular nanoassociates and the additional photosensitizing action of the photolinker on the surface of a metal nanoparticle. Such hybrid nanocatalysts based on metal nanoparticle and calixresorcinarenes have the potential to be used in the field of effective photodegradation of toxic water pollutants
The construction of supramolecular and hybrid Ag-AgCl nanoparticles with photodynamic therapy action on the base of tetraundecylсalix[4]resorcinarene-mPEG conjugate
The development of new nanomaterials with therapeutic potential is a modern task due to their outstanding properties and promising effectiveness. Here the usage of acylhydrazone bond-based сalix[4]resorcinarene-mPEG conjugate (C11-mPEG) in the formation of both supramolecular and hybrid nanoparticles with in vitro photodynamic therapy (PDT) activity is described. C11-mPEG is hydrolyzed with a decrease in pH of solution; the conjugate and its degradation product have the low hemolytic activity and low cytotoxicity against normal cells. The self-association of the conjugate was studied in the aqueous solutions with pH 7.4 and 5. C11-mPEG forms self-associates that serve as pH-sensitive supramolecular nanocontainers for photosensitizer Methylene Blue (MB). In the in vitro PDT experiment the stronger decrease of tumor cells (M-Hela cells) viability in the presence of encapsulated MB is observed in comparison with free MB. Also C11-mPEG acts as a stabilizing agent for Ag@AgCl nanoparticles, which were obtained with 5/1 and 2/1 Ag+/C11-mPEG molar ratio and different reducing agents (sodium borohydride and hydrazine hydrate). The stronger cytotoxicity of hybrid NPs against tumor cells in comparison with normal was shown. Further it was found that the irradiation of the hybrid nanoparticles at 630 nm leads to the sharp increase in their cytotoxicity against M-Hela cells. The high level of ROS formation in the cells in the presence of both supramolecular and hybrid NPs under in vitro PDT experiment was determined
A novel salt-responsive hydrogel on the base of calixresorcinarene–mPEG amide conjugate
A novel low toxic amide calix[4]resorcinarene–mPEG conjugates of amphiphilic and dendrimeric character were synthesized. It was shown that the growth of the temperature or the ionic strength growth of the solution leads to different demonstration of the amplification of hydrophobic interactions in the conjugates self-associates. It was found that in PBS or 0.9 % NaCl solutions the amphiphilic conjugate form micellar solution, and the dendrimeric conjugate – hydrogel, which is capable of the reversible sol-gel transition. It was shown by DSC analysis that the dendrimeric conjugate binds of 15 % of water molecules in an aqueous solution (non-freezing bound water), but in the salt solution the conjugate-water interaction is practically absent. This leads to the additional self-aggregation of conjugate molecules and to the gel formation. The high degree of substrate sorption by the hydrogel (Methylene Blue, encapsulation effectiveness is 78 %) and its reversible binding-release by the regulation of the solution ionic strength have been demonstrated
The pH-responsive calix[4]resorcinarene-mPEG conjugates bearing acylhydrazone bonds: Synthesis and study of the potential as supramolecular drug delivery systems
© 2020 Elsevier B.V. The synthesis of new conjugates of calix[4]resorcinarenes and methoxy-PEG via acylhydrazone bonds and their study in the formation of pH-sensitive low-toxic supramolecular drug delivery systems have described. The syntheses have been performed on the base of two calix[4]resorcinarenes in chair and boat conformations to obtain the dendrimer-like and amphiphilic conjugates, respectively. The structures of the conjugates have been confirmed by 1H, 13C NMR, and FT-IR spectroscopy, Maldi-TOF mass spectroscopy, and SLS method. The self-association of both amphiphilic and dendrimer-like conjugates has been found (NMR FT-PGSE, fluorimetry, DLS and TEM methods). The hydrolysis of the conjugates at pH 5.5 (proved by 1H NMR and FT-IR spectroscopy, DLS method) lead to the improved release of the conjugate-encapsulated Dox. The low hemolytic activity and low cytotoxicity against Chang liver cells of the conjugates and products of their hydrolysis have been demonstrated. Meanwhile, the improved cytotoxicity and photodynamic activity of conjugates-encapsulated drugs (Dox and Methylene Blue, respectively) has been found in vitro. The results have indicated the potential using of the calix[4]resorcinarene-mPEG conjugates bearing acylhydrazone bonds as supramolecular drug delivery systems
Synthesis of Ag-AgCl nanoparticles capped by calix[4]resorcinarene-mPEG conjugate and their antimicrobial activity
© 2020 Elsevier B.V. The growing resistance of bacteria to traditional antibiotics makes it necessary to develop new antimicrobial agents with the dissimilar mode of action such as Ag and AgCl nanoparticles. Here the synthesis of silver NPs in the colloidal solutions of calix[4] resorcinarene-mPEG conjugate C11-mPEG was reported. NPs were synthesized under varied conditions: different Ag+/C11-mPEG molar ratio, presence/absence of reducing agent (NaBH4), in dark or LED light exposure. It was found that in all cases Ag-AgCl NPs, stabilized by C11-mPEG, were obtained with the difference in the Ag NPs content and sizes. Physicochemical characteristics of the Ag-AgCl@C11-mPEG NPs were evaluated by UV–vis, FT-IR, XRPD, XRF, DLS, and TEM methods. The antimicrobial activity of NPs against Gram-positive and Gram-negative bacteria and fungi was studied and the preferred antimicrobial activity against Gram-positive bacteria was found. The proposed scheme of Ag-AgCl@C11-mPEG NPs and the influence of NPs content on the antimicrobial activity were discussed