Compressive property and energy absorption characteristic of interconnected porous Mg-Zn-Y alloys with adjusting Y addition

In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption characteristics.Several characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second phase.Compressive tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous Mg-Zn-Y.The experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second phase.When the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),W-phase(Mg_(3)Zn_(3)Y_(2)),and LPSO phase(Mg_(12)ZnY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 MJ/m^(3)to 10.97 MJ/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second phase.However,the average energy absorption efficiency is independent of the Y content.In addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing temperature.The compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the struts.The deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

瘤胃添加多不饱和脂肪酸对瘤胃微生物菌群、十二指肠外流脂肪酸和乳脂脂肪酸成分的影响

作者旨在研究瘤胃添加游离的亚油酸(LA)和二十二碳六烯酸(DHA)对中国荷斯坦奶牛瘤胃微生物菌群,十二指肠脂肪酸外流及乳成分和乳脂脂肪酸成分的影响。试验动物为4头泌乳中期(138.5d±10d)安装瘤胃和十二指肠瘘管的中国荷斯坦奶牛。试验动物随机分为3个处理组和1个对照组,采用4×4拉丁方设计,试验每期3周,共4期。试验日粮处理因素为2因子2水平即不含LA或含2.7%LA和不含DHA或含0.5%DHA。添加DHA会增加瘤胃中Megasphaera elsdenii数量,降低Fibrobactersuccinogenes的数量,但不影响Butyrivibrio fibrisolvens和Ruminococcus flavefaciens的数量。添加2.7%干物质含量的LA不会影响3种主要的纤维分解菌或M.elsdenii的数量,并且LA和DHA对微生物数量变化无交互效应。单独添加LA或DHA或两者混合都会增加十二指肠外流的异油酸的量。随添加脂肪酸量的增加,乳中异油酸和c-9,t-11CLA也逐渐增加。同时添加LA和DHA具有深层次的刺激性。本研究说明添加LA或DHA能增加十二指肠异油酸的外流量和牛奶中有益脂肪酸如VA、c-9,t-11CLA的含量。因此,调节日粮的组成能有效的提高牛奶中c-9,t-11CLA的组分。

TOTAL ENERGIES AND ELECTRONIC STRUCTURES OF CO_3Ti AND HYDROGENIZED Co_3Ti

Electronic structure calculations using the tighting-binding linear muffin-tin orbital (TB-LMTO) method have been performed for Co3Ti and its hydride CO3Ti. The computed values of lattice constants and bulk moduli agree with the experiment values. The theoritical excess enerpy and lattice staid due to hydrogen absorption consequently obtained hem the ab initio results indicate that H has the tendency to stay in Co3Ti and the ionicities of Co atomic spheres due to hydmpen absorption change from the canons to the ations. On the other hand, the changes of band structures due to hydrogenation are found to be remarkable.

富含油酸和亚油酸的油类对提高牛奶中共轭亚油酸含量的影响

选择40头荷斯坦奶牛,测定富含油酸和亚油酸的油类对提高牛奶中C18：2cis-9,trans-11共轭亚油酸和C18：1trans-11（VA）含量的影响。采用完全随机分组法,试验为期9周,最后6周为测定期。对照组的基础中日粮含粗饲料59%,试验组在此基础上分别添加4%的大豆油（SO）、4%的亚麻油（FO）以及2%的大豆油＋2％的亚麻油（SFO）。