Development of Simple Sequence Repeat Markers, Fertility Study and Seed Yield Heritability Estimates in Bermudagrass

The objectives of this study were to: develop and characterize genomic simple sequence repeat (SSR) markers in C. transvaalensis from its four SSR libraries enriched with [CA]n, [GA]n, [AAG]n, and [AAT]n; study selfing and outcrossing fertility in C. dactylon var. dactylon under open-pollinating conditions using SSR markers; and estimate heritability for seed yield and its two components, inflorescence prolificacy and seed set percentage in C. dactylon var. dactylon. There were 981 unique SSR markers developed and effective with reliable amplifications of targeted bands in C. transvaalensis donor DNA. Up to 93% of the 981 markers were polymorphic in eight C. transvaalensis plants and 544 markers were effective in all genotypes. A set of 917 markers amplified heritable alleles examined with six F1 progeny of African bermudagrass parents `T577' x `Uganda'. In the fertility study, 25 clonal common bermudagrass plants were planted in a randomized complete block design with 3 replications at Perkins and Stillwater, OK. DNA samples were isolated from 1439 progeny germinated from open-pollinated seed of 25 seed parents. After comparing the progeny alleles to those of their respective maternal parents using 11 selected SSR markers, only two progeny were identified to be selfed, indicating an extremely high outcrossing rate of 99.86% in common bermudagrass under open-pollinating field conditions. The field trials were also used to collect data of seed yield, inflorescence prolificacy and seed set percentage in both 2012 and 2013. Half-sib families differed for all three traits, indicating the presence of additive gene action. Family � location effects were observed for seed set and seed yield. All three traits showed family � year interaction effects, while a significant family � location � year interaction existed in the two components. Narrow-sense heritability estimates (0.18 and 0.26-0.68) for seed yield, respectively based on variance component analysis and parent-offspring regressions, indicated a complex genetics of seed yield. Heritability estimates were moderate to relatively high for inflorescence prolificacy (0.30-0.55) and seed set (0.41-0.78). The results indicated that genetic improvement could be achieved if phenotypic selection is applied for seed yield components and conventional genotypic evaluation is needed for seed yield increase.Plant & Soil Scienc

Converting metal-organic framework particles from hydrophilic to hydrophobic by an interfacial assembling route

Here we propose to modify the hydrophilicity of metal-organic framework (MOF) particles by an interfacial assembling route, which is based on the surface-active nature of MOF particles. It was found that hydrophilic UiO-66-NH₂ particles can be converted to hydrophobic particles through an oil-water interfacial assembling route. The underlying mechanism for the conversion of UiO-66-NH₂ was investigated by X-ray photoelectron spectroscopy and FT-IR spectroscopy. It was revealed that the close assembly of UiO-66-NH₂ particles at the oil-water interface strengthens the coordination between organic ligands and metal ions, which results in a decrease in the proportion of hydrophilic groups on UiO-66-NH₂ particle surfaces. Hydrophobic UiO-66-NH₂ particles show improved adsorption capacity for dyes in organic solvents compared with pristine UiO-66-NH₂ particles. It is expected that the interfacial assembling route can be applied to the synthesis of different kinds of MOF materials with tunable hydrophilicity or hydrophobicity required for diverse applications

Insight-HXMT observations of Swift J0243.6+6124 during its 2017-2018 outburst

The recently discovered neutron star transient Swift J0243.6+6124 has been monitored by {\it the Hard X-ray Modulation Telescope} ({\it Insight-\rm HXMT). Based on the obtained data, we investigate the broadband spectrum of the source throughout the outburst. We estimate the broadband flux of the source and search for possible cyclotron line in the broadband spectrum. No evidence of line-like features is, however, found up to $\rm 150~keV$. In the absence of any cyclotron line in its energy spectrum, we estimate the magnetic field of the source based on the observed spin evolution of the neutron star by applying two accretion torque models. In both cases, we get consistent results with $B\rm \sim 10^{13}~G$, $D\rm \sim 6~kpc$ and peak luminosity of $\rm >10^{39}~erg~s^{-1}$ which makes the source the first Galactic ultraluminous X-ray source hosting a neutron star.Comment: publishe

Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite

As China's first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was designed to perform pointing, scanning and gamma-ray burst (GRB) observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed. Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.Comment: 29 pages, 40 figures, 6 tables, to appear in Sci. China-Phys. Mech. Astron. arXiv admin note: text overlap with arXiv:1910.0443

Process parameter optimization and mechanical properties for additively manufactured stainless steel 316L parts by selective electron beam melting

This work presents an experimental study of process optimization of the pair of critical parameters (speed function (SF) and focus offset (FO)) for stainless steel 316 L (SS316L) parts additively manufactured by selective electron beam melting (SEBM). Here, there are two sets of optimized SF-FO parameters that could build SS316L parts with high relative densities (>99%) and well-melted top build surfaces. Tensile test results show that most of the SEBM-built SS316L samples exhibit higher tensile strengths than the conventional cast and wrought counterparts, whereas their ductility is lower. In addition, strong anisotropic tensile properties are observed for the SEBM-built SS316L samples, e.g. they generally have better tensile properties when loaded parallel to the build direction as compared to the horizontal direction. However, a large number of σ phase was found to precipitate at grain boundaries in the SS316L samples fabricated under lower SF and larger FO with a higher build temperature, which evidently deteriorates their tensile properties particularly for the horizontal direction. It is suggested that SEBM process parameters for SS316L must be optimized to avoid σ phase precipitation at elevated temperatures apart from a well-melted top build surface and a high relative density.NRF (Natl Research Foundation, S’pore

Process parameter optimization for additively manufactured stainless steel 316L parts by selective electron beam melting

An experimental study of process parameter optimization for stainless steel 316L (SS316L) parts additively manufactured by selective electron beam melting (SEBM) was carried out. The process parameters for different stages, particularly in the in-fill hatch melting stage, were optimized in this study. Near-fully dense (>99%) SS316L parts have been successfully fabricated with well-melted surfaces. Microstructural characterization was performed on the as-SEBM-built SS316L parts with the optimal process parameters. It revealed that near-equiaxed grains were formed, which is distinctive from the counterparts additively manufactured by other SEBM processes. The mechanism for the formation of near-equiaxed grains was discussed in detail. This paper provides an insight into fabricating SS316L parts with high density and desirable microstructure via SEBM process.NRF (Natl Research Foundation, S’pore)Published versio

Path Planning of Mobile Robot Based on Improved PRM Based on Cubic Spline

In view of the shortcomings of low search efficiency and many path turning points of Probabilistic Roadmaps (PRM), a bidirectional search PRM global path planning algorithm is proposed. The algorithm improves the search connection rules by using the positive and negative directions to search the path alternately, so that the connection of unnecessary nodes reduces, thereby speeding up the efficiency of path planning. Besides, the algorithm incorporates cubic spline interpolation. That will increase the smoothness of path planning and ensure that the mobile robot can realize the path planning task more smoothly and safely. The simulation results show that the improved algorithm can effectively improve the convergence speed and path smoothness of the algorithm. Finally, the improved algorithm is applied to the actual mobile robot navigation experiment. The experimental results have proven that the path planning strategy was able to a superior advantage over traditional PRM in path quality and computational time

Research on Graphene and Its Derivatives in Oral Disease Treatment

Oral diseases present a global public health problem that imposes heavy financial burdens on individuals and health-care systems. Most oral health conditions can be treated in their early stage. Even if the early symptoms of oral diseases do not seem to cause significant discomfort, prompt treatment is essential for preventing their progression. Biomaterials with superior properties enable dental therapies with applications in restoration, therapeutic drug/protein delivery, and tissue regeneration. Graphene nanomaterials have many unique mechanical and physiochemical properties and can respond to the complex oral microenvironment, which includes oral microbiota colonization and high masticatory force. Research on graphene nanomaterials in dentistry, especially in caries, periodontitis therapy, and implant coatings, is progressing rapidly. Here, we review the development of graphene and its derivatives for dental disease therapy