Solidification microstructure of M2 high speed steel by different casting technologies

The present work investigated the solidification microstructure of AISI M2 high speed steel manufactured by different casting technologies, namely iron mould casting and continuous casting. The results revealed that the as-cast structure of the steel was composed of the iron matrix and the M2C eutectic carbide networks, which were greatly refined in the ingot made by continuous casting process, compared with that by the iron mould casting process. M2C eutectic carbides presented variation in their morphologies and growth characteristics in the ingots by both casting methods. In the ingot by iron mould casting, they have a plate-like morphology and grow anisotropically. However, in the ingot made by continuous casting, the carbides evolved into the fiber-like shape that exhibited little characteristics of anisotropic growth. It was noticed that the fiber-like M2C was much easier to decompose and spheroidize after heated, as a result, the carbides refined remarkably, compared with the case of plate-like carbides in the iron mould casting ingot

miRNAs Reshape Immunity and Inflammatory Responses in Bacterial Infection

Pathogenic bacteria cause various infections worldwide, especially in immunocompromised and other susceptible individuals, and are also associated with high infant mortality rates in developing countries. MicroRNAs (miRNAs), small non-coding RNAs with evolutionarily conserved sequences, are expressed in various tissues and cells that play key part in various physiological and pathologic processes. Increasing evidence implies roles for miRNAs in bacterial infectious diseases by modulating inflammatory responses, cell penetration, tissue remodeling, and innate and adaptive immunity. This review highlights some recent intriguing findings, ranging from the correlation between aberrant expression of miRNAs with bacterial infection progression to their profound impact on host immune responses. Harnessing of dysregulated miRNAs in bacterial infection may be an approach to improving the diagnosis, prevention and therapy of infectious diseases

UV-B responsive microRNA genes in Arabidopsis thaliana

MicroRNAs (miRNAs) are small, non-coding RNAs that play critical roles in post-transcriptional gene regulation. In plants, mature miRNAs pair with complementary sites on mRNAs and subsequently lead to cleavage and degradation of the mRNAs. Many miRNAs target mRNAs that encode transcription factors; therefore, they regulate the expression of many downstream genes. In this study, we carry out a survey of Arabidopsis microRNA genes in response to UV-B radiation, an important adverse abiotic stress. We develop a novel computational approach to identify microRNA genes induced by UV-B radiation and characterize their functions in regulating gene expression. We report that in A. thaliana, 21 microRNA genes in 11 microRNA families are upregulated under UV-B stress condition. We also discuss putative transcriptional downregulation pathways triggered by the induction of these microRNA genes. Moreover, our approach can be directly applied to miRNAs responding to other abiotic and biotic stresses and extended to miRNAs in other plants and metazoans

The effects of housing policies on life-cycle housing choice of Singapore households

Master'sMASTER OF SCIENCE (ESTATE MANAGEMENT

Resonant chains in triple-planetary systems

Fil: Wang, Xuefeng. Nanjing University. School of Astronomy and Space Science; China.Fil: Wang, Xuefeng. Ministry of Education. Key Laboratory of Modern Astronomy and Astrophysics; China.Fil: Zhou, Li-Yong. Nanjing University. School of Astronomy and Space Science; China.Fil: Zhou, Li-Yong. Ministry of Education. Key Laboratory of Modern Astronomy and Astrophysics; China.Fil: Beaugé, Cristian. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Beaugé, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina.A resonant chain may be formed in a multi-planetary system when ratios of the orbital periods can be expressed as ratios of small integers T1:T2:⋯:TN=k1:k2:⋯:kN. We investigate the dynamics and possible formation of resonant chain. The appropriate Hamiltonian for a three-planet resonant chain is defined and numerically averaged over the synodic period. The stable stationary solutions (apsidal corotational resonance, ACR) of this system, corresponding to the local extrema of Hamiltonian function, can be searched out numerically. The topology of the Hamiltonian around these ACRs reveals their stabilities. We further construct dynamical maps on representative planes to study the dynamics, and we calculate the deviation (χ2) of the resonant angle from the uniformly distributed values. Finally, the formation of resonant chain via convergent migration is simulated and stable configurations associated with ACRs are verified. We find that stable ACR families arising from circular orbits always exist for any resonant chain, and they may extend to high eccentricity. Around ACR solutions, regular motion are found in two types of resonant configurations. One is characterised by libration of both the two-body resonant angles and the three-body Laplace resonant angle, and the other by libration of only two-body resonant angles. The Laplace resonance seems not to contribute much to the stability. The resonant chain can be formed via convergent migration, and subsequently the resonant configuration evolves along the ACR families to eccentric orbits. Ideally, our methods introduced here can be applied to any resonant chain of any number of planets at any eccentricity.info:eu-repo/semantics/acceptedVersionFil: Wang, Xuefeng. Nanjing University. School of Astronomy and Space Science; China.Fil: Wang, Xuefeng. Ministry of Education. Key Laboratory of Modern Astronomy and Astrophysics; China.Fil: Zhou, Li-Yong. Nanjing University. School of Astronomy and Space Science; China.Fil: Zhou, Li-Yong. Ministry of Education. Key Laboratory of Modern Astronomy and Astrophysics; China.Fil: Beaugé, Cristian. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina.Fil: Beaugé, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Astronomía Teórica y Experimental; Argentina