Y元素对铸态 Mg-Al-Ca-Mn合金组织与耐腐蚀性能的影响

采用金相显微镜、扫描电镜、XRD分析、腐蚀试验和电化学测试等研究了Mg-4Al-3Ca-0.7Mn-xY(x=0、0.8、1.5)铸态合金的微观组织与耐腐蚀性能。结果表明:未添加Y的Mg-4Al-3Ca-0.7Mn合金组织由α-Mg、Al2Ca相、Mg2Ca相组成。添加0.8wt%Y后,合金组织中晶粒得到明显细化,析出相变得细小,Al2Ca相、Mg2Ca相数量减少,并有Al2Y相生成。Y含量增加到1.5wt%时,合金晶粒细化效果不明显,大量Al2Y相聚集在晶界处呈网状分布。添加适量的Y可提高Mg-4Al-3Ca-0.7Mn-xY合金的耐腐蚀性,Y添加量为0.8wt%时,该合金的耐腐蚀性最佳。

Effect of Ca addition on modification of primary Mg_(2)Si,hardness and wear behavior in Mg-Si hypereutectic alloys

The effect of Ca addition on modification of primary Mg_(2)Si,hardness and wear behavior in Mg-5 wt.%Si hypereutectic alloy has been investigated.The results showed clearly that without Ca addition,most of primary Mg_(2)Si appeared as coarse dendritic morphology with average size of about 215μm.With the addition of 0.1 wt.%Ca,the average size of primary Mg_(2)Si decreased to about 98μm,but their morphologies did not significantly changed.As the addition level of Ca increased to 0.3 wt.%,the average size of primary Mg_(2)Si decreased significantly to about 50μm and their morphologies changed to polyhedral shape.However,with further increasing Ca addition to 0.6 wt.%and 1 wt.%,some needle-like and blocky CaMgSi particles formed and the average size of primary Mg_(2)Si increased slightly,which could described as over-modification.The present work showed that the optimal modification effect could be obtained when the Ca content in the investigated alloy reached 0.3 wt.%.The modification mechanism may be referred mainly due to poisoning effect resulting from the segregation of Ca atoms at the growth front of the Mg_(2)Si and the adsorption effect of some Ca atoms in the Mg_(2)Si crystal growth plane.The 0.3 wt.%Ca-added alloy has the highest hardness value and the best wear resistance among all other alloys.An excessive Ca addition resulted in the formation of some needle-like and blocky CaMgSi particles,which was detrimental to hardness and wear behavior of the 0.6 wt.%and 1 wt.%Ca-added alloys.The wear mechanism of investigated alloys is a mild abrasive oxidative wear with little adhesion.

Sodium-modification of Ca-based bentonite via semidry process

In order to improve the quality of Hunyuan inferior Ca-based bentonite(Ca-Bent),semidry process was used to modify Ca-Bent into superior Na-based bentonite(Na-Bent).The factors affecting sodium-modification were investigated.The optimized experimental parameters are obtained as follows:Na2CO3 dosage 4.0%,ageing time 25 d,briquetting pressure 25 MPa and briquetting moisture 20%.Under the optimization conditions,the modified Na-Bent has a colloid value of 73.6 mL/(3g),dilation of 38 mL/g and water absorption in 2 h(2HWA) of 465%,respectively.The balling results indicate that the modified Na-Bent pellets have higher drop strength and compression strength than the Ca-Bent pellets.

靶向切割猪Y染色体的CRISPR/Cas9载体构建及功能验证

【目的】通过CRISPR/Cas9系统对Y染色体多位点切割,实现目标染色体的敲除,为畜禽性别控制提供新的手段。【方法】以CRISPR/Cas9技术为基础,寻找Y染色体上能被sgRNA特异性识别的多拷贝重复序列,并通过体外切割、定量分析、核型鉴定验证其对靶点的有效性。【结果】所设计的sgRNA能够在体外实现对靶片段的明显切割,且切割效率均达到了50%以上。基因的定量分析结果证明了其在细胞水平切割的有效性,且簇状重复序列切割效果明显优于散在重复序列;核型鉴定结果证实了细胞水平猪Y染色体的丢失。【结论】研究结果为后续构建染色体敲除猪,实现猪的性别控制奠定了基础。

小晶粒NiY分子筛的合成及其加氢裂化反应性能

通过在小晶粒Y分子筛合成的过程中原位引入Ni源合成了一系列不同Ni掺入量的小晶粒Y-xNi分子筛,将活性金属Ni预浸渍到Y分子筛的骨架中。将Y-xNi分子筛和ASA混合物作为载体并采用等体积浸渍法负载Ni和W,制备了系列Cat-xNi加氢裂化催化剂,以正十六烷为反应物,探究其加氢裂化催化反应性能。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、N2吸附-脱附、氨气程序升温脱附(NH3-TPD)、氢气程序升温还原(H2-TPR)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等表征手段分析了Ni的掺入对Y分子筛及Cat-xNi催化剂理化性质的影响。结果表明,Ni主要取代Al引入Y分子筛骨架;在Y分子筛中适量掺入Ni会提高Y分子筛的相对结晶度以及Bronsted酸和Lewis酸位点的数量,但过量的Ni掺入不利于Y分子筛的结晶。Ni的掺入削弱了金属与载体间的相互作用,提高了活性金属的硫化度及NiWS活性相的堆积数及分散度,调节了催化剂上金属中心与酸中心的匹配。催化性能评价结果显示,由于Ni改性能同时增加Br?nsted酸中心与NiWS活性中心数量,增强金属中心与酸中心之间的协同作用,因而在提高正十六烷加氢裂化活性的同时可避免其过度裂化,获得较高的中间馏分产物(C8-C12)选择性及收率。在360℃反应条件下,与Cat-0Ni催化剂相比,Cat-0.2Ni催化剂具有较高的n-C16转化率和C8-C12产物收率(达65.4%)。综上可知,采用原位合成法将活性金属Ni预浸渍在Y分子筛上可以有效调节裂化活性中心与加氢活性中心之间的平衡,从而提高其催化活性和中间馏分产物的收率。

Y Zeolites Modified by Organosilane for Toluene Adsorption under High Humidity Condition

Y zeolites have moderate microporous pore size, large specific surface area, and good hydrothermal stability, which were widely used in industrial adsorption of volatile organic compounds (VOCs), but the performance of Y zeolites in adsorption of VOCs under high humidity conditions is terrible. In this paper, Y zeolites with different silica-alumina ratios were hydrophobically modified by organosilane and characterized by XRD, FTIR, SEM, BET, NMR. In the experiments of static and dynamic adsorption of VOCs by modified Y zeolites, it can be concluded that the static water adsorption capacity of Y zeolites with silica-aluminum ratio of 5 and 40 after silica modification decreased by 62 wt% and 53 wt%, under the conditions of high humidity, GHSV = 15,000 h-1, T = 35°C and initial concentration of toluene C0 = 5000 mg·m-3. The saturation adsorption capacity of toluene was increased from 0.06 g·g-1, 0.09 g·g-1 to 0.15 g·g-1, 0.21 g·g-1, the adsorption selectivity of Y zeolites for water was reduced and that for toluene was increased after Vapor phase silanization overlay modification. The present modification method might carry out targeted modification of zeolites surface, provide research ideas and guidance under high humidity conditions.

Simultaneous CO_(2) capture and thermochemical heat storage by modified carbide slag in coupled calcium looping and CaO/Ca(OH)2 cycles

The simultaneous CO_(2) capture and heat storage performances of the modified carbide slag with byproduct of biodiesel were investigated in the process coupled calcium looping and CaO/Ca(OH)2 thermochemical heat storage using air as the heat transfer fluid.The modified carbide slag with by-product of biodiesel exhibits superior CO_(2) capture and heat storage capacities in the coupled calcium looping and heat storage cycles.The hydration conversion and heat storage density of the modified carbide slag after 30 heat storage cycles are 0.65 mol·mol^(-1) and 1.14 GJ·t^(-1),respectively,which are 1.6 times as high as those of calcined carbide slag.The negative effect of CO_(2) in air as the heat storage fluid on the heat storage capacity of the modified carbide slag is overcome by introducing CO_(2) capture cycles.In addition,the CO_(2) capture reactivity of the modified carbide slag after the multiple calcium looping cycles is enhanced by the introduction of heat storage cycles.By introducing 10 heat storage cycles after the 10th and 15th CO_(2) capture cycles,the CO_(2) capture capacities of the modified carbide slag are subsequently improved by 32%and 43%,respectively.The porous and loose structure of modified carbide slag reduces the diffusion resistances of CO_(2) and steam in the material in the coupled process.The formed CaCO_(3)in the modified carbide slag as a result of air as the heat transfer fluid in heat storage cycles decomposes to regenerate CaO in calcium looping cycles,which improves heat storage capacity.Therefore,the modified carbide slag with by-product of biodiesel seems promising in the coupled calcium looping and CaO/Ca(OH)_(2) heat storage cycles.

TC4合金表面Zr-Y改性渗硅涂层的组织结构及高温摩擦磨损性能

采用固体粉末扩散渗方法在TC4合金表面制备了Zr-Y改性的渗硅涂层,研究了渗层的组织结构、高温摩擦磨损性能及磨损机制。结果表明:Zr-Y改性渗硅涂层具有多层梯度结构,外层由TiSi_(2)和少量ZrSi_(2)组成,较薄的中间层为TiSi相,内层为Ti_(5)Si_(4)和Ti_(5)Si_(3)的混合物。涂层的显微硬度明显高于TC4合金基体,且由表及内呈梯度降低趋势。高温摩擦磨损实验(600℃)结果表明,Zr-Y改性渗硅涂层具有优良的摩擦磨损防护性能。与GCr15对磨时的磨损率约为3.59×10^(-5)mm^(3)/(N·m),是相同条件下TC4合金磨损率的36.6%,磨损机制主要为GCr15在涂层表面的擦涂和氧化磨损。与Al2O3球对磨时的磨损率为9.75×10^(-5)mm^(3)/(N·m),是相同条件下TC4合金磨损率的18.9%,磨损机制为疲劳磨损、氧化磨损和黏着磨损。

Generation of genetically modified mice using CRISPR/Cas9 and haploid embryonic stem cell systems

With the development of high-throughput sequencing technology in the post-genomic era, researchers have concentrated their efforts on elucidating the relationships between genes and their corresponding functions. Recently, important progress has been achieved in the generation of genetically modified mice based on CRISPR/Cas9 and haploid embryonic stem cell （haESC） approaches, which provide new platforms for gene function analysis, human disease modeling, and gene therapy. Here, we review the CRISPR/Cas9 and haESC technology for the generation of genetically modified mice and discuss the key challenges in the application of these approaches.

As-cast Medium Mn Steel with Nodular Carbide Modified by Y-base Heavy RE Compound

1.IntroductionMedium Mn steel was developed be-cause the wear resistance of Hadfield steel(Mn13)is poor under low or medium im-pact and extrusion abrasion[1-4].In theforegoing investigations[2-4]we found thatwith the increase of C content,theneedle-like and network carbide in mediumMn steel increased(as shown in Fig.1(a)and(c)).Although its wear resistance was largelyimproved,its impact toughness was greatlydecreased.In order to increase toughness,along-term high temperature heat-treatmentwas needed.But the treatment caused cracks

Ca,Y对AZ91镁合金显微组织和力学性能的影响

向AZ91镁合金中加入具有阻燃作用的合金元素Ca和Y,研究了单独加入Ca和同时加入Ca,Y对AZ91合金铸态显微组织和力学性能的影响。结果表明:向AZ91合金中单独加入Ca可使该合金的铸态组织明显细化,当Ca含量大于1ω%时,合金铸态组织中生成了Al2Ca新相,使该合金的抗拉强度得到提高。在此基础上加入少量的Y(0.10%～0.50%)(质量分数,下同)可使合金的铸态组织进一步细化,该合金的抗拉强度随Y含量的增加先提高后降低。

Y、Gd与Ca对AZ81镁合金组织和力学性能的影响

通过合金制备、微观分析和力学性能测试等方法研究了Y、Gd与Ca对AZ81镁合金组织和力学性能的影响。结果表明,适量合金元素的加入使AZ81镁合金的组织明显细化,β(Mg17Al12)相减少,同时析出了针状和粒状的化合物Al2Y和Al2Ca。经时效处理后,随着合金元素含量的增加,从室温到175℃时,合金的强度和伸长率基本上呈先升后降的趋势。当Y、Gd与Ca总含量为2.1%时,合金在室温和175℃下的抗拉强度达到最大,分别为230MPa和160MPa。Y、Gd与Ca主要是通过细晶强化、固溶强化和弥散强化提高了镁合金的室温和高温强度。

Ca_4Y_6Si_6O_(25)∶Eu^(2+)绿色荧光粉的发光特性

采用高温固相法合成了Ca4Y6Si6O25:Eu2+绿色荧光材料。通过X射线衍射分析得知,Ca4Y6Si6O25属于六方晶系,具有P63/m(176)空间点群结构。测定了Eu2+的激发光谱和发射光谱。Ca4Y6Si6O25:Eu2+的激发光谱为350～450nm的宽带谱,这与近紫外光LED芯片相匹配。发射光谱是峰值为527nm的不对称宽带发射,这是因为Eu2+占据了晶格中Ca2+的位置,并产生了两种不同的发光中心。研究了Eu2+的含量对Ca4(1-x)Y6Si6O25:4xEu2+发光性能的影响,随着Eu2+浓度的增大,材料的发光强度先增强后减弱,Eu2+的最佳掺杂摩尔分数为20%(x=0.05)。根据Dexter理论得出,浓度猝灭机理为电四极-电四极相互作用。

Zr、Y和Ba-Ca变质对00Cr25Ni7Mo4N钢组织与性能的影响

以00Cr25Ni7Mo4N铸造不锈钢的组织和性能为研究内容,试验了Zr、Y和Ba-Ca变质剂对钢的变质效果。试验表明,3种变质剂对抑制晶体长大,细化组织,改善铸造性能和提高材料的力学性能均产生良好效果;其中Y的变质效果最为显著,试样的断口宏观形貌得以明显改善,断口撕裂的颗粒细化程度是未处理试样的1/11;组织中孤立岛状的γ相明显圆钝和尺寸变小;夹杂物数量减少;因此,钢的流动性提高,铸造工艺性能得以改善,铸造缺陷减少;由于钢的组织细化,力学性能明显提高。变质后的材料在具备良好塑韧性(δ=19%)时,σb和σs分别提高了16.1%和41.2%。

钙钛矿锰氧化物Y_(0.5)Ca_(0.5)Mn_(0.8)Fe_(0.2)O_3的电子顺磁共振研究

用固相反应法制备了Y0.5Ca0.5Mn0.8Fe0.2O3多晶陶瓷材料, 借助电子顺磁共振技术对多晶样品在150～300 K温度范围内的顺磁共振行为进行了研究.结果表明样品的顺磁共振线宽ΔHpp和g因子的值随着温度的降低是增加的.线宽的增加是由于随着温度的降低, 样品进入一个长程的反铁磁态, 体系的铁磁关联增强导致的.g因子随温度的降低而增加表明体系的轨道有序是逐渐增强的.

Y、Ca复合添加对AZ81镁合金组织和性能的影响

通过复合添加碱土元素Ca和稀土元素Y来改善AZ81镁合金的组织和力学性能,在CO_2+SF_6气体保护下制备了不同Ca、Y含量的AZ81-Y-Ca镁合金,通过光学金相显微镜(OM)、扫描电镜(SEM)、X射线衍射分析(XRD)、能谱分析(EDS)、拉伸及蠕变力学性能测试等手段研究了Ca、Y合金化对AZ81合金显微组织和力学性能的影响规律。结果表明,添加1.5%Y后AZ81合金的显微组织显著细化,Mg_(17)Al_(12)相的数量和尺寸减少,晶界和晶内形成块状和细小点状分布的Al_2Y相;AZ81-1.5Y合金中继续添加0.5%的Ca,其显微组织继续得到明显细化,组织中形成了点状或条状的Al_2Ca相。添加1.5%Y后AZ81合金的室温和高温拉伸力学性能得到大幅提高;随Ca含量的增加AZ81-1.5Y合金的抗拉强度呈先增大后减小的趋势,当Ca加入量为0.5%时得到最优的强化效果。Y和Ca的添加能够显著提高AZ81镁合金在175～200℃/70 MPa条件下的抗蠕变能力。在175℃/70 MPa条件下,Y和Ca的添加使得AZ81合金的蠕变应变量降低2～3倍,稳态蠕变速率降低近一个数量级。

Ca-α-Sialon和Y-α-Sialon的制备

用热力学方法分析了α Sialon合成的可能性 ,并通过制备Ca α Sialon和Y α Sialon进行了实验验证。对合成的Ca α Sialon和Y α Sialon采用XRD进行了相组成分析 ,运用SEM观察了合成材料的显微形貌 ,发现了长柱状的Ca α Sialon晶粒。

高强高阻尼Mg-Zr系合金的研究(Ⅰ)——Ca/Y变质处理Mg-0.6Zr合金阻尼行为的研究

采用动态机械热分析(DMA)技术研究了Ca/Y变质处理对Mg-0.6Zr合金阻尼行为的影响,分析了合金随应变振幅和温度阻尼变化的机制。结果表明,添加0.3%Ca和0.3%Ca+0.1%Y(质量分数,下同)变质处理后的细晶强化和固溶强化作用提高了合金的拉伸强度和延伸率,同时由于Ca/Y元素的加入及晶界数量增多对位错运动的进一步阻碍作用降低了合金的应变振幅效应,从而降低了其阻尼性能;研究还发现Mg-0.6Zr合金在温度为75℃处出现一个明显的阻尼峰,而添加0.3%Ca+0.1%Y变质处理后,并未出现阻尼峰。分析认为,试验合金的阻尼机制可按G-L位错钉扎模型和晶界面软化及粘性滑动机制解释。

荧光粉Ca_4Y_6O(SiO_4)_6:Dy^(3+)的制备与发光特性(英文)

采用高温固相法制备了Ca4Y6O(SiO4)6∶Dy3+荧光材料,通过样品的XRD谱证明了Ca4Y6O(SiO4)6∶Dy3+荧光材料是纯相的结构材料,通过发射光谱和激发光谱等发光特性的研究发现该荧光粉材料有多个发射峰,分别位于480 nm和573 nm处。监测蓝峰(480 nm)和黄峰(573 nm),测得材料的激发谱均为多锐峰(位于293,323,348,363,386,424,452 nm),均属于Dy3+的特征吸收峰,其中以348 nm的激发峰最强。探讨了Dy3+的掺杂量对样品黄蓝峰发射强度比(IY/IB)、发光色坐标及色温的影响。分析了Dy3+的浓度对荧光粉发光的影响及其浓度猝灭机理。

神经肽Y经Ca^2＋/CaM依赖的钙调神经磷酸酶途径诱导心肌细胞肥大

目的观察神经肽Y(NPY)诱导心肌细胞肥大效应,及Ca2+/CaM依赖的钙调神经磷酸酶(CaN)途径在其中起的作用。方法用NPY(10、100nmol)刺激心肌细胞,用环胞素A(CsA)特异性抑制CaN活性。测定心肌细胞蛋白合成速率(3H-Leu掺入量)、CaN-蛋白表达、c-junmRNA表达、CaN酶活性、细胞内游离钙含量。结果(1)在100nmolNPY作用下,心肌细胞3H-Leu掺入量及c-junmRNA表达量均较对照组显著增高(P<0.05,P<0.001)。NPY+CsA组和对照组相比无显著差别。(2)在100nmolNPY作用下,NPY组心肌细胞内CaN酶比活力、CaN-α表达、胞浆及核内钙含量较对照组显著增高(P<0.05,P<0.05,P<0.001,P<0.001)。结论NPY可刺激心肌细胞肥大,CaN信号途径在其中起重要作用。