摘要：高熵合金的多组分特性使其具有许多传统合金无法比拟的优异性能.然而,高熵合金传统的制备方法仍存在一定的局限性.激光选区熔化(SLM)技术可以通过逐层沉积的方式实现复杂零件的精密成形.将SLM技术与高熵合金相结合,可以充分发挥高熵合金的性能优势.本文综述了SLM制备的高熵合金的显微结构和性能特征.由于SLM工艺存在高温梯度和高冷却速率,所以在SLM制备的高熵合金中通常会形成复杂的微观结构,包括胞状亚结构、析出相、层错和纳米孪晶.此外,独特的微观结构为高熵合金带来了优异的力学性能和其他功能,表明利用SLM技术制备高熵合金具有很大的发展潜力.此外,我们还简要介绍了SLM制备的高熵合金的微观缺陷及其应用.本文为高性能高熵合金的设计提供了有益的指导.

摘要：实现材料的顺电-铁电相变可以丰富铁电材料的多样性.本文通过设计和引入A位非化学计量缺陷,在Ba_(0.9)(Fe_(0.5)Nb_(0.5))O_(3-δ)薄膜中实现了晶格畸变,诱导出室温铁电.薄膜中引入的四方畸变和局部位错促进了结构的对称性破缺以及自发极化的出现.在这里我们成功实现了室温下剩余极化Pr约为8μC cm^(-2)的铁电性和高达450℃的相稳定性温度我们的研究工作为通过缺陷工程发现和调节新型铁电材料提供了一种实用的方法.

摘要：Cobalt nanoparticles(NPs)catalysts are extensively used in heterogeneous catalytic reactions,and the addition of alkali metal promoters is a common method to modulate the catalytic performance because the catalyst's surface structures and morphologies are sensitive to the addition of ***,the underlying modulation trend remains ***,the adsorption of alkali metal promoters(Na and K)on the surfaces of face-centered-cubic(FCC)and hexagonal-closest packed(HCP)polymorphous cobalt was systematically investigated using density functional ***,the effect of alkali promoters on surface energies and nanoparticle morphologies was revealed on the basis of Wulff *** FCC-Co,the exposed area of the(111)facet in the nanoparticle increases with the adsorption coverage of alkali metal ***,the(311),(110),and(100)facets would disappear under the higher adsorption coverage of alkali *** HCPCo,the Wulff morphology is dominated by the(0001)and(1011)facets and is independent of the alkali metal adsorption *** work provides insights into morphology modulation by alkali metal promoters for the rational design and synthesis of cobalt-based nanomaterials with desired facets and morphologies.

摘要：粉末床熔融增材制造技术已应用于功能梯度材料的制造.文献中报道了一种材料成分沿垂直于粉末铺粉方向变化的新设计.基于此设计,本工作采用离散单元数值模拟研究了两种密度差异较大的金属粉末在铺粉过程中颗粒的偏析情况.结果发现,在铺粉过程中,较大密度粉末(重颗粒)一侧的铺粉量小于较小密度粉末(轻颗粒)的一侧的铺粉量.这种现象表明重颗粒从粉末密度大的一侧向粉末密度较小的一侧扩散.这种扩散受铺粉速度影响较大,铺粉速度越快,扩散越明显.但粉末层厚度对扩散影响不大.结果还表明,重颗粒与轻颗粒间的粒径差异影响扩散较大,减小重颗粒的粒径可能是控制颗粒偏析的一种方案.

摘要：The ability to design and synthesize the genome of a living organism marks one of the most significant achievements in synthetic biology. The first synthetic genomes were those of bacteria （Gibson et al., 2010; Hutchison et al., 2016）, but an international consortium of scientists is now undertaking the ambitious task of designing and synthesizing the entire genome of Saccharornayces cerevisiae, a eukaryotic single-celled yeast （Dymond et al., 2011; Kannan and Gibson, 2017）. One feature of the redesigned yeast genome, called Saccharomyces cerevisiae 2.0 or Sc2.0, is the ability to in-duce novel genetic variation.

摘要：Steels, accounting for a large proportion of metals and their alloys, are still irreplaceable structural materials in industrial applications for a long time. Classical dislocation theory sheds light that strength can be enhanced by impeding the dislocation ***, the ductility depends on the mobility of dislocation movement. As a result, one method of increasing strength or ductility always damages the other. In other words, there is a mutual exclusion between strength and ductility from the perspective of dislocation movement [1].

摘要：面对高精尖仪器或设备的热膨胀控制的需求,探索新的负热膨胀材料显得尤为重要.本文采用"平均原子晶格体积"概念预测各向异性新的负热膨胀材料体系,据此发现了REFe(CN)_(6)(RE=La,Sm,Ho,Lu)负热膨胀材料家族.我们采用原位中子粉末衍射(NPD)、X射线吸收精细结构谱(EXAFS)和第一性原理计算揭示了其负热膨胀来源于低频声子振动模式中的CN原子的横向热振动,进一步发现"平均原子晶格体积"越大,其对应的低频声子模式频率越低,格林艾森常数越负,CN原子的横向热振动越强.本工作为定性预测负热膨胀材料提供了新的方法,对热膨胀控制与设计具有重要意义.

摘要：A grand challenge facing society is climate change caused mainly by rising CO_(2) concentration in Earth’s *** plants are linchpins in global carbon cycling,with a unique capability of capturing CO_(2) via photosynthesis and translocating captured carbon to stems,roots,and soils for long-term ***,many researchers postulate that existing land plants cannot meet the ambitious requirement for CO_(2) removal to mitigate climate change in the future due to low photosynthetic efficiency,limited carbon allocation for long-term storage,and low suitability for the *** address these limitations,there is an urgent need for genetic improvement of existing plants or construction of novel plant systems through biosystems design(or biodesign).Here,we summarize validated biological parts(e.g.,protein-encoding genes and noncoding RNAs)for biological engineering of carbon dioxide removal(CDR)traits in terrestrial plants to accelerate land-based decarbonization in bioenergy plantations and agricultural settings and promote a vibrant ***,we first summarize the framework of plant-based CDR(e.g.,CO_(2) capture,translocation,storage,and conversion to value-added products).Then,we highlight some representative biological parts,with experimental evidence,in this ***,we discuss challenges and strategies for the identification and curation of biological parts for CDR engineering in plants.

摘要：小鼠(Mus musculus)免疫系统包含种类众多、功能各异的细胞群体。为了研究小鼠免疫系统的发育机制,需要建立高效的遗传操作技术方法。首先选择Cas9敲入小鼠的DN细胞(CD4-~CD8^-double negative thymocytes)为研究对象,针对GFP和CD4表面抗原基因设计构建了sgRNA(single guide RNA),使用小鼠逆转录病毒(Murine stem cell virus,MSCV)为载体实施了基因编辑。通过流式细胞仪分析,检测到GFP和CD4被成功敲除。在此基础上,选取Cas9敲入小鼠的LSK细胞(Lin^-Sca1^+Kit^+)为研究对象,使用同样的方法针对Tcf7基因设计构建了sgRNA并实施基因编辑。基因编辑后,LSK细胞不能正常分化为下游T细胞,但其分化为髓系细胞能力不受影响。这些结果表明,针对小鼠LSK和DN原代细胞实施的基因编辑取得成功。

摘要：翻译起始位点(TIS,即基因5′端)的精确定位是原核生物基因预测的一个关键问题,而基因组GC含量和翻译起始机制的多样性是影响当前TIS预测水平的重要因素.结合基因组结构的复杂信息(包括GC含量、TIS邻近序列及上游调控信号、序列编码潜能、操纵子结构等),发展刻画翻译起始机制的数学统计模型,据此设计TIS预测的新算法MED-StartPlus.并将MED-StartPlus 与同类方法 RBSfinder、GS-Finder、MED-Start、TiCo 和Hon-yaku等进行系统地比较和评价.测试针对两种数据集进行:当前14个已知的TIS被确认的基因数据集,以及300个物种中功能已知的基因数据集.测试结果表明,MED-StartPlus的预测精度在总体上超过同类方法.尤其是对高GC含量基因组以及具有复杂翻译起始机制的基因组,MED-StartPlus具有明显的优势.