101 research outputs found

    (2,2′-Bipyridine-κ2 N,N′)bis­(4-methyl­benzoato-κ2 O,O′)lead(II)

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    In the title compound, [Pb(C8H7O2)2(C10H8N2)], the PbII ion is coordinated by two N atoms from one 2,2′-bipyridine ligand and four O atoms from two 4-methyl­benzoate anions in a distorted pseudo-square-pyramidal environment, considering one of the carboxyl­ate anions as an apical ligand. Pairs of complex mol­ecules related by inversion centers are organized into dimers via pairs of Pb⋯O inter­actions [3.185 (2) Å] and stacking interactions between 2,2′-bipyridine and 4-methyl­benzoate ligands, with a mean distance between their planes of 3.491 Å

    Effectiveness of the Different Eutectic Phase-Change Materials in Cooling Asphalt Pavement

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    Choosing a Phase-Change Material (PCM) Adapted to the Specific Phase-Change Temperature (Tm) Required for Each Temperature Condition is of Utmost Importance in Cooling Pavements. Eutectic Phase-Change Materials (EPCMs) Realize the Customization of the Desired Tm and Reduce the Difficulty of Matching PCMs. This Work Aims to Investigate the Effectiveness of a Group of Binary/ternary EPCMs with Tm Ranging from 30 to 60 ℃ and Melting Enthalpies of Around 200 J/g as Thermal Regulation Components for Different Asphalt. to Achieve This Goal, the Thermal and Rheological Properties of Phase-Change Asphalt Binders (PCAB) Were Evaluated by Differential Scanning Calorimeter, Thermogravimetric, Fourier Transform Infrared, and Multiple Stress Creep and Recovery Tests. the Results Showed that PCAB with Latent Heat Improved the Specific Heat Capacity, Which Brought a Maximum Temperature Lag of 134.5 Min and a Maximum Temperature Difference of 11 ℃. Similarly, the PCAB Remained Chemical Stability, and its Thermal Stability Complied with the Construction Temperature Specifications. However, the Recrystallization of EPCMs Was Impeded by the Molten Asphalt Binder Matrix, Resulting in a Significant Reduction in Both the Tm and Enthalpy. Therefore, These Reductions Should Be Taken into Consideration When Choosing an EPCM. Additionally, as Liquid EPCM Softens the Binder, the Absence of Elasticity in Solid EPCMs Renders the Binder Stiff, Thus Reducing its Resistance to Deformation. These Impacts Were Particularly Noticeable in Styrene-Butadiene-Styrene Modified Asphalt Due to the Polymer Network Being Dissolved by Liquefication-EPCMs. to Sum Up, EPCMs with a Higher Tm (40–60 ℃) May Decrease their Negative Impact on Deformation Resistance, Such as Palmitic Acid-Myristic Acid-Methyl Stearate Mixtures

    Characterization of cellulase production by carbon sources in two Bacillus species

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    The induction of cellulase production in two Bacillus spp. was studied by means of measuring cellulase activities under the condition of different carbon sources. The results indicate that cellulase could not be induced by cellulose material as a sole carbon source. Instead, they could be induced by monosaccharide or disaccharide with reducing group. Moreover, the expression of cellulase components was synergistic. When cell wall/envelope enzyme and endoenzyme from two Bacillus spp. acted on these inducers, analysis of reaction products by high performance liquid chromatography (HPLC) revealed that cell wall/envelope enzyme and endoenzyme from two Bacillus spp. were inactive on these inducers. It also indicated that these inducers entered cells directly and served function of induction.Keywords: Bacillus, cellulase, induction, carbon source

    A least square method based model for identifying protein complexes in protein-protein interaction network

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    Protein complex formed by a group of physical interacting proteins plays a crucial role in cell activities. Great effort has been made to computationally identify protein complexes from protein-protein interaction (PPI) network. However, the accuracy of the prediction is still far from being satisfactory, because the topological structures of protein complexes in the PPI network are too complicated. This paper proposes a novel optimization framework to detect complexes from PPI network, named PLSMC. The method is on the basis of the fact that if two proteins are in a common complex, they are likely to be interacting. PLSMC employs this relation to determine complexes by a penalized least squares method. PLSMC is applied to several public yeast PPI networks, and compared with several state-of-the-art methods. The results indicate that PLSMC outperforms other methods. In particular, complexes predicted by PLSMC can match known complexes with a higher accuracy than other methods. Furthermore, the predicted complexes have high functional homogeneity

    An aphid-transmitted polerovirus is mutualistic with its insect vector by accelerating population growth in both winged and wingless individuals

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    The occurrence and increased dispersion of plant viruses and insect vectors are serious global threat to the production of agricultural crops. Facing novel pathogenic plant viruses, the ability to accurately identify plant virus species, and understand the interaction between plant viruses, host plants and their insect vectors would provide an important basis for formulating effective plant virus control measures. In this study, we explored the transmission mechanism, pathogenic symptoms, host range and the interactions between virus and aphid vectors of a novel polero virus from Nicotianatabacum, named Tobacco yellow virus (TYV). The results indicate that TYV can be transmitted by Myzus persicae in a persistent manner, and cause yellowing and shrinking of tobacco leaves. TYV can successfully infect a total of 9 plant species belonging to 3 families. The effect of TYV-infected tobacco plants on M. persicae behavior and life characteristics was found to be stage-dependent. TYV can directly and indirectly manipulate the performance and life history traits of M. persicae vectors to promote their own transmission. These results provide a certain theoretical basis for the possibility of control strategies of the virus, and the in-depth exploration of the interaction among plant virus, vector aphid and host plants

    Phonon Polaritons in Monolayers of Hexagonal Boron Nitride.

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    Phonon polaritons in van der Waals materials reveal significant confinement accompanied with long propagation length: important virtues for tasks pertaining to the control of light and energy flow at the nanoscale. While previous studies of phonon polaritons have relied on relatively thick samples, here reported is the first observation of surface phonon polaritons in single atomic layers and bilayers of hexagonal boron nitride (hBN). Using antenna-based near-field microscopy, propagating surface phonon polaritons in mono- and bilayer hBN microcrystals are imaged. Phonon polaritons in monolayer hBN are confined in a volume about one million times smaller than the free-space photons. Both the polariton dispersion and their wavelength-thickness scaling law are altered compared to those of hBN bulk counterparts. These changes are attributed to phonon hardening in monolayer-thick crystals. The data reported here have bearing on applications of polaritons in metasurfaces and ultrathin optical elements

    Self-Cleaning Glass of Photocatalytic Anatase TiO2@Carbon Nanotubes Thin Film by Polymer-Assisted Approach

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    Due to the good photocatalytic activity, the TiO2@CNTs thin film is highly desirable to apply to the self-cleaning glass for green intelligent building. Here, the TiO2@CNTs thin film has been successfully achieved by polymer-assisted approach of an aqueous chemical solution method. The polymer, polyethylenimine, aims to combine the Ti4+ with CNTs for film formation of TiO2@CNTs. The resultant thin film was uniform, highly transparent, and super-hydrophilic. Owing to fast electron transport and effectively hindering electron-hole recombination, the TiO2@CNTs thin film has nearly twofold photocatalytic performance than pure TiO2. The TiO2@CNTs thin films show a good application for self-cleaning glasses

    The Lyman Continuum Escape Fraction of Star-forming Galaxies at 2.4≲z≲3.72.4\lesssim z\lesssim3.7 from UVCANDELS

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    The UltraViolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) survey is a Hubble Space Telescope (HST) Cycle-26 Treasury Program, allocated in total 164 orbits of primary Wide-Field Camera 3 Ultraviolet and Visible light F275W imaging with coordinated parallel Advanced Camera for Surveys F435W imaging, on four of the five premier extragalactic survey fields: GOODS-N, GOODS-S, EGS, and COSMOS. We introduce this survey by presenting a thorough search for galaxies at z≳2.4z\gtrsim2.4 that leak significant Lyman continuum (LyC) radiation, as well as a stringent constraint on the LyC escape fraction (fescf_{\rm esc}) from stacking the UV images of a population of star-forming galaxies with secure redshifts. Our extensive search for LyC emission and stacking analysis benefit from the catalogs of high-quality spectroscopic redshifts compiled from archival ground-based data and HST slitless spectroscopy, carefully vetted by dedicated visual inspection efforts. We report a sample of five galaxies as individual LyC leaker candidates, showing fescrel≳60%f_{\rm esc}^{\rm rel}\gtrsim60\% estimated using detailed Monte Carlo analysis of intergalactic medium attenuation. We develop a robust stacking method to apply to five samples of in total 85 non-detection galaxies in the redshift range of z∈[2.4,3.7]z\in[2.4,3.7]. Most stacks give tight 2-σ\sigma upper limits below fescrel<6%f_{\rm esc}^{\rm rel}<6\%. A stack for a subset of 32 emission-line galaxies shows tentative LyC leakage detected at 2.9-σ\sigma, indicating fescrel=5.7%f_{\rm esc}^{\rm rel}=5.7\% at z∼2.65z\sim2.65, supporting the key role of such galaxies in contributing to the cosmic reionization and maintaining the UV ionization background. These new F275W and F435W imaging mosaics from UVCANDELS have been made publicly available on the Barbara A. Mikulski Archive for Space Telescopes.Comment: 33 pages, 21 figures, and 5 tables. Resubmitted after addressing the referee repor
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