Ideal stoichiometric technetium nitrides under pressure: a first-principles study

Technetium nitrides with various ideal stoichiometries have been investigated with the first-principle method at the pressures between 0–60 GPa. It have been found that there could be many stable technetium nitrides including Tc₃N, Tc₂N, TcN, Tc₂N₃, TcN₂, TcN₃, and TcN₄, among which Tc₃N and Tc₂N sub-nitrides are synthesizable at zero pressure and could be applied to nuclear waste management, such as separate radioactive 99Tc from nuclear fuel cycle. Moreover, N-rich TcN₃ and TcN₄ exhibit remarkable bulk properties and can be potential ultrastiff and hard materials.Нітриди технеція з різною ідеальної стехіометрією досліджені із застосуванням методу перших принципів при тисках від 0 до 60 ГПа. Встановлено, що може бути багато стабільних нітридів технеція, включаючи Tc₃N, Tc₂N, ТКС, Tc₂N₃, TcN₂, TcN₃ і TcN₄, серед яких субнітриди Tc₃N і Tc₂N синтезуються при нульовому тиску і можуть бути використані для обробки ядерних відходів, таких як виділений при ядерному паливному циклі радіоактивний 99Tc. Більш того, TcN₃ і TcN₄, збагачені N, демонструють чудові об’ємні властивості і можуть бути потенційними ультражорсткими і твердими матеріалами.Нитриды технеция с различной идеальной стехиометрией исследованы с применением метода первых принципов при давлениях от 0 до 60 ГПа. Установлено, что может быть много стабильных нитридов технеция, включая Tc₃N, Tc₂N, ТКС, Tc₂N₃, TcN₂, TcN₃ и TcN₄, среди которых субнитриды Tc₃N и Tc₂N синтезируются при нулевом давлении и могут быть использованы для обработки ядерных отходов, таких как выделенный при ядерном топливном цикле радиоактивный 99Tc. Более того, TcN₃ и TcN₄, обогащенные N, демонстрируют замечательные объемные свойства и могут быть потенциальными ультражесткими и твердыми материалами

Relativistic Mass Ejecta from Phase-transition-induced Collapse of Neutron Stars

We study the dynamical evolution of a phase-transition-induced collapse neutron star to a hybrid star, which consists of a mixture of hadronic matter and strange quark matter. The collapse is triggered by a sudden change of equation of state, which result in a large amplitude stellar oscillation. The evolution of the system is simulated by using a 3D Newtonian hydrodynamic code with a high resolution shock capture scheme. We find that both the temperature and the density at the neutrinosphere are oscillating with acoustic frequency. However, they are nearly 180$^{\circ}$ out of phase. Consequently, extremely intense, pulsating neutrino/antineutrino fluxes will be emitted periodically. Since the energy and density of neutrinos at the peaks of the pulsating fluxes are much higher than the non-oscillating case, the electron/positron pair creation rate can be enhanced dramatically. Some mass layers on the stellar surface can be ejected by absorbing energy of neutrinos and pairs. These mass ejecta can be further accelerated to relativistic speeds by absorbing electron/positron pairs, created by the neutrino and antineutrino annihilation outside the stellar surface. The possible connection between this process and the cosmological Gamma-ray Bursts is discussed.Comment: 40 pages, 11 figures, accepted for publication in JCA

Genome-wide association study for flour color-related traits and polyphenol oxidase activity in common wheat

This study aimed to clarify the genetic mechanisms behind wheat flour color. Flour colorrelated traits (L*, a*, and b*) and polyphenol oxidase (PPO) activity are important parameters that influence the end-use quality of wheat. Dissecting the genetic bases and exploring important chromosomal loci of these traits are extremely important for improving wheat quality. The diverse panel of 205 elite wheat varieties (lines) was genotyped using a highdensity Illumina iSelect 90K single-nucleotide polymorphisms (SNPs) assay to disclose the genetic mechanism of flour color-related traits and PPO activity. In 2 different environments and their mean values (MV), 28, 30, 24, and 12 marker-trait associations (MTAs) were identified for L*, a*, b* traits, and PPO activity, respectively. A single locus could explain from 5.52% to 20.01% of the phenotypic variation for all analyzed traits. Among them, 5 highly significant SNPs (P ≤ 0.0001), 11 stable SNPs (detected in all environments) and 25 multitrait MTAs were identified. Especially, BS00000020_51 showed pleiotropic effects on L*, a*, and b*, and was detected in all environments with the highest phenotypic contribution rates. Furthermore, this SNP was also found to be co-associated with wheat grain hardness, ash content, and pasting temperature of starch in previous studies. The identification of these significantly associated SNPs is helpful in revealing the genetic mechanisms of wheat colorrelated traits, and also provides a reference for follow-up molecular marker-assisted selection in wheat breeding

Identification of Sitobion avenae F. resistance and genetic diversity of wheat landraces from Qinling Mountains, China

The aphid Sitobion avenae F. is one of the most harmful pests of wheat growth in the world. A primary field screening test was carried out to evaluate the S. avenae resistance of 527 wheat landraces from Shaanxi. The results indicated that 25 accessions (4.74%) were resistant to S. avenae in the three consecutive seasons, of which accession S849 was highly resistant, and seven accessions were moderately resistant. The majority of S. avenae resistant accessions come from Qinling Mountains. Then, the genetic variability of a set of 33 accessions (25 S. avenae resistant and 8 S. avenae susceptible) originating from Qinling Mountains have been assessed by 20 morphological traits and 99 simple sequence repeat markers (SSRs). Morphological traits and SSRs displayed a high level of genetic diversity within 33 accessions. The clustering of the accessions based on morphological traits and SSR markers showed significant discrepancy according to the geographical distribution, resistance to S. avenae and species of accessions. The highly and moderately resistant landrace accessions were collected from the middle and the east part of Qinling Mountains with similar morphology characters, for example slender leaves with wax, lower leaf area, and high ear density. These S. avenae resistant landraces can be used in wheat aphid resistance breeding as valuable resources

A population of hypercompact HII regions identified from young HII regions

CONTEXT: The derived physical parameters for young H$\tiny{II}$ regions are normally determined assuming the emission region to be optically-thin. However, this is unlikely to hold for young H$\tiny{II}$ regions such as Hyper-compact H$\tiny{II}$ (HC H$\tiny{II}$) and Ultra-compact H$\tiny{II}$ (UC H$\tiny{II}$) regions and leads to the underestimation of their properties. This can be overcome by fitting the SEDs over a wide range of radio frequencies. AIMS: Two primary goals are (1) determining physical properties from radio SEDs and finding potential HC H$\tiny{II}$ regions; (2) using these physical properties to investigate their evolution. METHODS: We used Karl G. Jansky Very Large Array (VLA) to make observations of X-band and K-band with angular-resolutions of ~ 1:7′′ and ~ 0:7′′, respectively, toward 114 H$\tiny{II}$ regions with rising-spectra $α{5GHz\choose 1.4GHz} > 0$. We complement our observations with VLA archival data and construct SEDs between 1-26 GHz and model them assuming an ionisation-bounded H$\tiny{II}$ region with uniform density. RESULTS: The sample has a mean electron density of n$_e$ = 1.6 x 10$^4$ cm$^{-3}$, diameter diam = 0.14 pc, and emission measure EM = 1.9 x 10$^7$ pc cm$^{-6}$. We identify 16 HC H$\tiny{II}$ region candidates and 8 intermediate objects between the classes of HC H$\tiny{II}$ and UC H$\tiny{II}$ regions. The n$_e$, diam, and EM change as expected, however, the Lyman continuum flux is relatively constant over time. We find that about 67% of Lyman continuum photons are absorbed by dust within these H$\tiny{II}$ regions and the dust absorption fraction tends to be more significant for more compact and younger H$\tiny{II}$ regions. CONCLUSIONS: Young H$\tiny{II}$ regions are commonly located in dusty clumps; HC H$\tiny{II}$ regions and intermediate objects are often associated with various masers, outflows, broad radio recombination lines, and extended green objects, and the accretion at the two stages tends to be quickly reduced or halted