937 research outputs found

    Isolation of microsatellite markers for Bletilla striata and cross-amplification in other related species

    Get PDF
    Bletilla is a temperate, terrestrial genus of orchids containing 6 species. For the species whose whole genome is unknown, we used magnetic bead hybridization method to develop microsatellite Simple Repeat Polymorphoresis (SSR) for Bletilla striata and 9 primer sets were characterized in two wild populations of B. striata and one wild population of Bletilla ochracea. The number of alleles per locus ranged from 1 to 12. The expected and observed heterozygosities ranged from 0 to 0.7646 and 0 to 0.950 in B. striata, respectively. In B. ochracea, the expected and observed heterozygosities ranged from 0.296 to 0.871 and 0.05 to 1, respectively. The 9 pairs of primers we designed can be used to distinguish different ecotypes and species, and might be used for other subspecies or species in genera Bletilla.Keywords: Bletilla striata, cross-species amplification, simple repeat polymorphoresis (SSR)

    Modeling and simulation of sintering process across scales

    Full text link
    Sintering, as a thermal process at elevated temperature below the melting point, is widely used to bond contacting particles into engineering products such as ceramics, metals, polymers, and cemented carbides. Modelling and simulation as important complement to experiments are essential for understanding the sintering mechanisms and for the optimization and design of sintering process. We share in this article a state-to-the-art review on the major methods and models for the simulation of sintering process at various length scales. It starts with molecular dynamics simulations deciphering atomistic diffusion process, and then moves to microstructure-level approaches such as discrete element method, Monte--Carlo method, and phase-field models, which can reveal subtle mechanisms like grain coalescence, grain rotation, densification, grain coarsening, etc. Phenomenological/empirical models on the macroscopic scales for estimating densification, porosity and average grain size are also summarized. The features, merits, drawbacks, and applicability of these models and simulation technologies are expounded. In particular, the latest progress on the modelling and simulation of selective and direct-metal laser sintering based additive manufacturing is also reviewed. Finally, a summary and concluding remarks on the challenges and opportunities are given for the modelling and simulations of sintering process.Comment: 45 pages, 38 figure

    Three-dimensional structure and cytokine distribution of platelet-rich fibrin

    Get PDF
    OBJECTIVES: Previous reports have revealed that several cytokines (including platelet-derived growth factor-BB, transforming growth factors-β1 and insulin-like growth factor-1) can enhance the rate of bone formation and synthesis of extracellular matrix in orthopaedics or periodontology. This study aimed to determine the concentration of cytokines within platelet-rich fibrin microstructures and investigate whether there are differences in the different portions of platelet-rich fibrin, which has implications for proper clinical use of platelet-rich fibrin gel. METHODS: Whole blood was obtained from six New Zealand rabbits (male, 7 to 39 weeks old, weight 2.7-4 kg); it was then centrifuged for preparation of platelet-rich fibrin gels and harvest of plasma. The resultant platelet-rich fibrin gels were used for cytokine determination, histological analyses and scanning electron microscopy. All plasmas obtained were subject to the same cytokine determination assays for the purpose of comparison. RESULTS: Cytokines platelet-derived growth factor-BB and transforming growth factor-β1 formed concentration gradients from high at the red blood cell end of the platelet-rich fibrin gel (p=1.88×10-5) to low at the plasma end (p=0.19). Insulin-like growth factor-1 concentrations were similar at the red blood cell and plasma ends. The porosities of the platelet-rich fibrin samples taken in sequence from the red blood cell end to the plasma end were 6.5% ± 4.9%, 24.8% ± 7.5%, 30.3% ± 8.5%, 41.4% ± 12.3%, and 40.3% ± 11.7%, respectively, showing a gradual decrease in the compactness of the platelet-rich fibrin network. CONCLUSION: Cytokine concentrations are positively associated with platelet-rich fibrin microstructure and portion in a rabbit model. As platelet-rich fibrin is the main entity currently used in regenerative medicine, assessing cytokine concentration and the most valuable portion of PRF gels is essential and recommended to all physicians

    Spectroscopy of broad absorption line quasars at 3z53\lesssim z \lesssim 5 -- I: evidence for quasar winds shaping broad/narrow emission line regions

    Full text link
    We present an observational study of 22 broad absorption line quasars (BAL QSOs) at 3z53\lesssim z \lesssim5 based on optical/near-IR spectroscopy, aiming to investigate quasar winds and their effects. The near-IR spectroscopy covers the \hb\ and/or \mgii\ broad emission lines (BELs) for these quasars, allowing us to estimate their central black hole (BH) masses in a robust way. We found that our BAL QSOs on average do not have a higher Eddington ratio than that from non-BAL QSOs matched in redshift and/or luminosity. In a subset consisting of seven strong BAL QSOs possessing sub-relativistic BAL outflows, we see the prevalence of large \civ-BEL blueshift (\sim3100 km s1^{-1}) and weak \oiii\ emission (particularly the narrow \oiiiλ\lambda5007 component), indicative of nuclear outflows affecting the narrow emission-line (NEL) regions. In another subset consisting of thirteen BAL QSOs having simultaneous observations of \mgii\ and \hb, we found a strong correlation between 3000~\AA\ and 5000~\AA\ monochromatic luminosity, consistent with that from non-BAL QSOs matched in redshift and luminosity; however, there is no correlation between \mgii\ and \hb\ in FWHM, likely due to nuclear outflows influencing the BEL regions. Our spectroscopic investigations offer strong evidence that the presence of nuclear outflows plays an important role in shaping the BEL/NEL regions of these quasars and possibly, regulating the growth of central supermassive black holes (SMBHs). We propose that BEL blueshift and BAL could be different manifestations of the same outflow system viewed at different sightlines and/or phases.Comment: 13 pages, 10 figures. Accepted for publication in Ap

    Discovery of gamma-ray emission from a strongly lobe-dominated quasar 3C 275.1

    Full text link
    We systematically analyze the 6-year {\it Fermi}/LAT data of the lobe-dominated quasars (LDQs) in the complete LDQ sample from 3CRR survey and report the discovery of high-energy γ\gamma-ray emission from 3C 275.1. The γ\gamma-ray emission of 3C 207 is confirmed and significant variability of the lightcurve is identified. We do not find statistically significant γ\gamma-ray emission from other LDQs. 3C 275.1 is the known γ\gamma-ray quasar with the lowest core dominance parameter (i.e., R=0.11R=0.11). We also show that both the northern radio hotspot and parsec jet models can reasonably reproduce the γ\gamma-ray data. The parsec jet model, however, is favored by the potential γ\gamma-ray variability at the timescale of months. We suggest that some dimmer γ\gamma-ray LDQs will be detected in the future and LDQs could contribute non-negligibly to the extragalactic γ\gamma-ray background.Comment: 26 pages, 10 figures, 3 tables; ApJ in pres

    Interference of Two-Dimensional Bose-Einstein Condensates in Micro-Gravity

    Full text link
    We investigate the interference of two-dimensional Bose-Einstein condensates in micro-gravity, which influenced by the interaction strength, initial momentum, gravitational potential and phase difference. We demonstrate that the gravitational potential from the Earth can change the density distribution and phase distribution of the condensate's wave function. As time evolves, a portion of the gravitational potential energy of the microscopic particles can be converted into kinetic energy, which changes the motion of the microscopic particles, and leads to the varying of the density and phase distribution of the wave function. Nevertheless, the influences of the Earth's gravity on the wave function can be eliminated by the micro-gravity environment, which confirmed by many micro-gravity cold atom experiments. Our results present the influences of gravity and other parameters on interference of Bose-Einstein condensates, which help us to reveal the intrinsic natures of the related theoretical predictions and experimental phenomena. Furthermore, our work builds a bridge between the related physical phenomena and our physical intuition about the Bose-Einstein condensates in micro-gravity environment

    Statistical Origin of Constituent-Quark Scaling in the QGP hadronization

    Full text link
    Nonextensive statistics in a Blast-Wave model (TBW) is implemented to describe the identified hadron production in relativistic p+p and nucleus-nucleus collisions. Incorporating the core and corona components within the TBW formalism allows us to describe simultaneously some of the major observations in hadronic observables at the Relativistic Heavy-Ion Collider (RHIC): the Number of Constituent Quark Scaling (NCQ), the large radial and elliptic flow, the effect of gluon saturation and the suppression of hadron production at high transverse momentum (pT) due to jet quenching. In this formalism, the NCQ scaling at RHIC appears as a consequence of non-equilibrium process. Our study also provides concise reference distributions with a least chi2 fit of the available experimental data for future experiments and models.Comment: 4 pages, 3 figures; added two tables, explained a little bit more on TBW_p

    Quasar winds caught on acceleration and deceleration

    Full text link
    We present an observational study of wind acceleration based on four low-ionization broad absorption line (LoBAL) quasars (J0136, J1238, J1259, J1344). J0136 and J1344 (group-1) are radio quiet and show large BAL-velocity shifts as opposed to stable line-locking associated absorption lines (AALs). Notably, J1344 displays a linear relation between BAL-velocity shift and time interval over three consecutive epochs, characteristic of compelling evidence for BAL acceleration. J1238 and J1259 (group 2) exhibit small BAL-velocity shifts along with steep-spectrum, weak radio emission at 3.0 and 1.4 GHz. All four quasars have spectral energy distributions (SEDs) with a peak at λrest10 μ\lambda_{\rm rest }\sim10~\mum, suggesting a link between the BAL acceleration and hot dust emission. The group-2 quasars are redder than group-1 quasars and have a steeper rise at 1<λrest<3 μ1<\lambda_{\rm rest }<3~\mum in their SEDs. All but J1238 exhibit a steep rise followed by a plateau-like time evolution in BAL-velocity shift. Our investigations, combined with previous studies of BAL acceleration, indicate that (1) the BAL-ISM coupling process is one of the major avenues for the origin of quasar reddening and patchy obscuration, (2) AAL outflows are ubiquitous and likely signify large-scale remnants of BAL winds coupled to interstellar medium (ISM), and (3) wind deceleration that is closely linked to the BAL-ISM coupling process may produce weak radio emission in otherwise radio-quiet quasars.Comment: 19 pages, 9 figures, accepted for publication in ApJ
    corecore