227 research outputs found

    Methyl 3-hydr­oxy-4-(3-methyl­but-2-en­yloxy)benzoate

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    The title compound, C13H16O4, was isolated from culture extracts of the endophytic fungus Cephalosporium sp. The ester and ether substituents are twisted only slightly out of the benzene ring plane, making dihedral angles of 2.16 (2) and 3.63 (5)°, respectively. The non-H atoms of all three substituents are almost coplanar with the benzene ring, with an r.m.s. deviation of 0.0284 Å from the mean plane through all non-H atoms in the structure. A weak intra­molecular O—H⋯O hydrogen bond contributes to this conformation. In the crystal structure, mol­ecules are linked into a one-dimensional chain by inter­molecular O—H⋯O hydrogen bonds. Weak non-classical C—H⋯π contacts are also observed in the structure

    6,8-Dihydr­oxy-3-methyl­isocoumarin

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    The title compound, C10H8O4, was isolated from the fermentation culture of the endophytic fungus Cephalo­sporium sp. In the crystal structure, mol­ecules are connected into a one-dimensional chain along [101] by inter­molecular O—H⋯O hydrogen bonds involving the hydroxyl and carbonyl functionalities. The chains are linked by non-classical C—H⋯O inter­actions, forming extended two-dimensional layers approximately parallel to (11)

    1,3-Bis(chloro­meth­yl)-2-methyl-5-nitro­benzene

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    The title compound, C9H9Cl2NO2, is a natural product isolated from the endophytic fungus No. B77 of the mangrove tree from the South China Sea coast. In the crystal structure, the mol­ecules lie on twofold axes and form offset stacks through face-to-face π–π inter­actions. Adjacent mol­ecules in each stack are related by a centre of inversion and have an inter­planar separation of 3.53 (1) Å, with a centroid–centroid distance of 3.76 (1) Å. Between stacks, there are C—H⋯O inter­actions to the nitro groups and Cl⋯Cl contacts of 3.462 (1) Å

    3-Hydroxy­meth­yl-6,8-dimeth­oxy-2H-chromen-2-one

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    The asymmetric unit of the title compound, C12H12O5, contains four independent mol­ecules. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into one-dimensional infinite chains. They are arranged in a nearly parallel fashion along the b axis and stabilized by π–π inter­actions [3.443 (2) Å]

    Organization of plastid genomes in the freshwater red algal order Batrachospermales (Rhodophyta)

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    Little is known about genome organization in members of the order Batrachospermales, and the infra-ordinal relationship remains unresolved. Plastid (cp) genomes of seven members of the freshwater red algal order Batrachospermales were sequenced, with the following aims: (i) to describe the characteristics of cp genomes and compare these with other red algal groups; (ii) to infer the phylogenetic relationships among these members to better understand the infra-ordinal classification. Cp genomes of Batrachospermales are large, with several cases of gene loss, they are gene-dense (high gene content for the genome size and short intergenic regions) and have highly conserved gene order. Phylogenetic analyses based on concatenated nucleotide genome data roughly supports the current taxonomic system for the order. Comparative analyses confirm data for members of the class Florideophyceae that cp genomes in Batrachospermales is highly conserved, with little variation in gene composition. However, relevant new features were revealed in our study: genome sizes in members of Batrachospermales are close to the lowest values reported for Florideophyceae; differences in cp genome size within the order are large in comparison with other orders (Ceramiales, Gelidiales, Gracilariales, Hildenbrandiales, and Nemaliales); and members of Batrachospermales have the lowest number of protein-coding genes among the Florideophyceae. In terms of gene loss, apcF, which encodes the allophycocyanin beta subunit, is absent in all sequenced taxa of Batrachospermales. We reinforce that the interordinal relationships between the freshwater orders Batrachospermales and Thoreales within the Nemaliophycidae is not well resolved due to limited taxon sampling

    Observation of Majorana fermions with spin selective Andreev reflection in the vortex of topological superconductor

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    Majorana fermion (MF) whose antiparticle is itself has been predicted in condensed matter systems. Signatures of the MFs have been reported as zero energy modes in various systems. More definitive evidences are highly desired to verify the existence of the MF. Very recently, theory has predicted MFs to induce spin selective Andreev reflection (SSAR), a novel magnetic property which can be used to detect the MFs. Here we report the first observation of the SSAR from MFs inside vortices in Bi2Te3/NbSe2 hetero-structure, in which topological superconductivity was previously established. By using spin-polarized scanning tunneling microscopy/spectroscopy (STM/STS), we show that the zero-bias peak of the tunneling differential conductance at the vortex center is substantially higher when the tip polarization and the external magnetic field are parallel than anti-parallel to each other. Such strong spin dependence of the tunneling is absent away from the vortex center, or in a conventional superconductor. The observed spin dependent tunneling effect is a direct evidence for the SSAR from MFs, fully consistent with theoretical analyses. Our work provides definitive evidences of MFs and will stimulate the MFs research on their novel physical properties, hence a step towards their statistics and application in quantum computing.Comment: 4 figures 15 page

    Calibration of the Timing Performance of GECAM-C

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    As a new member of the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) after GECAM-A and GECAM-B, GECAM-C (originally called HEBS), which was launched on board the SATech-01 satellite on July 27, 2022, aims to monitor and localize X-ray and gamma-ray transients from \sim 6 keV to 6 MeV. GECAM-C utilizes a similar design to GECAM but operates in a more complex orbital environment. In this work, we utilize the secondary particles simultaneously produced by the cosmic-ray events on orbit and recorded by multiple detectors, to calibrate the relative timing accuracy between all detectors of GECAM-C. We find the result is 0.1 μs\mu \rm s, which is the highest time resolution among all GRB detectors ever flown and very helpful in timing analyses such as minimum variable timescale and spectral lags, as well as in time delay localization. Besides, we calibrate the absolute time accuracy using the one-year Crab pulsar data observed by GECAM-C and Fermi/GBM, as well as GECAM-C and GECAM-B. The results are 2.02±2.26 μs2.02\pm 2.26\ \mu \rm s and 5.82±3.59 μs5.82\pm 3.59\ \mu \rm s, respectively. Finally, we investigate the spectral lag between the different energy bands of Crab pulsar observed by GECAM and GBM, which is 0.2 μs keV1\sim -0.2\ {\rm \mu s\ keV^{-1}}.Comment: submitte
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