Improvement in grain refinement efficiency of Mg-Zr master alloy for magnesium alloy by friction stir processing

Previous studies have proved that the zirconium(Zr)alloying and grain refining performance of a Mg-Zr master alloy on Mg alloy is closely related to the distribution of Zr particle size,and a Mg-Zr master alloy with more Zr particles in size range of 1-5μm exhibits a better refining efficiency.In this paper,friction stir processing(FSP)was used to modify the Zr particles size distribution of a commercially available Mg-30 wt.%Zr master alloy,and the subsequent grain refinement ability was studied by trials on a typical Mg-3Nd-0.2Zn-0.6Zr(wt.%,NZ30K)alloy.It is found that plenty of large Zr particles in the as-received Mg-30%Zr master alloy are broken by FSP.Grain refinement tests reveal that the refining efficiency of Mg-30%Zr alloy is significantly improved by FSP,which is attributed to the better distribution of Zr particles.The refinement effect by adding 0.6%FSP-ed Mg-30%Zr is approximately equivalent to that by adding 1.0%as-received Mg-30%Zr.Due to the easy and convenient operation of FSP,this study provides a new method to develop a more efficient Mg-Zr refiner.

Effects of OFDI on Employment and Skill Upgrading in Its Home Economy

This research empirically examines the relationship between outward foreign direct investment （OFDI） and employment in its home economy. It is marked out from existing studies in the following three respects. First, instead of advanced economies, it focuses on the effect on employment in a newly industrialized economy. Second, it not only addresses the general issue of whether employment or production overseas complements or substitutes for employment in parent companies but also examines how OFDI contributes to skill upgrading in its origin economy, in addition to the quantitative effect. Third, this paper allows the results to vary between labour-intensive industries and technology-intensive industries in order to find the extent to which the home employment effect is moderated by industrial technology intensity. The results demonstrate that the location of investment and industry characteristics matter for explaining the effect of OFDI on home employment. Specifically, we find that while OFDI by Taiwan＇s multinationals in the Chinese mainland depresses employment in Taiwan in both labour- and technology-intensive industries, OFDI in other economies only produces a negative employment effect in technology-intensive sectors. An interesting finding of this study is the evidence of positive effects of OFDI on skill upgrading in Taiwan. This paper supports the argument that relocation of productivity overseas axes low-skilled workers at home. Moreover, OFDI in the Chinese mainland has a particular positive impact on skill upgrading in the home industry, lending support to the view that multinational enterprises （MNEs） outsource labour-intensive goods from their affiliates in low-income economies.

The human malaria parasite genome is configured into thousands of coexpressed linear regulatory units

The human malaria parasite Plasmodium falciparum thrives in radically different host environments in mosquitoes and humans, with only a limited set of transcription factors. The nature of regulatory elements or their target genes in the P. falciparum genome remains elusive. Here, we found that this eukaryotic parasite uses an efficient way to maximally use genetic and epigenetic regulation to form regulatory units(RUs) during blood infections. Genes located in the same RU tend to have the same pattern of expression over time and are associated with open chromatin along regulatory elements. To precisely define and quantify these RUs, a novel hidden Markov model was developed to capture the regulatory structure in a genome-wide fashion by integrating expression and epigenetic evidence. We successfully identified thousands of RUs and cross-validated with previous findings. We found more genes involved in red blood cell(RBC) invasion located in the same RU as the Pf AP2-I(AP2-I) transcription factor, demonstrating that AP2-I is responsible for regulating RBC invasion. Our study has provided a regulatory mechanism for a compact eukaryotic genome and offers new insights into the in vivo transcriptional regulation of the P. falciparum intraerythrocytic stage.

Computational Identification of Active Enhancers in Model Organisms

As a class of cis-regulatory elements, enhancers were first identified as the genomic regions that are able to markedly increase the transcription of genes nearly 30 years ago. Enhancers can regulate gene expression in a cell-type specific and developmental stage specific manner. Although experimental technologies have been developed to identify enhancers genome-wide, the design principle of the regulatory elements and the way they rewire the transcriptional regulatory network tempo-spatially are far from clear. At present, developing predictive methods for enhanc- ers, particularly for the cell-type specific activity of enhancers, is central to computational biology. In this review, we survey the current computational approaches for active enhancer prediction and discuss future directions.