黄颡鱼MyoD基因的克隆及其表达

采用RT-PCR和RACE(cDNA末端快速扩增)方法克隆黄颡鱼MyoD(myogenic differentiation antigen,成肌分化抗原)基因的cDNA全长序列,对其进行生物信息学和在雌雄个体组织中的表达差异分析.结果表明,黄颡鱼MyoD基因编码区由810个碱基组成,编码269个氨基酸,其中第1～89个氨基酸为Basic区,第90～141个氨基酸为bHLH结构;黄颡鱼的MyoD基因与斑点叉尾鮰的同源性最高为93%.在雌雄成体组织中的表达分析显示,雄性个体中肌肉和胃组织中的表达量极显著高于雌性个体(p<0.01),雌性个体的肾脏和鳃组织中的表达量显著高于雄性(p<0.05).通过MyoD基因在雌雄个体中表现出的组织表达差异,认为这可能是造成黄颡鱼雌雄生长差异的重要因素之一.     

First-principles study of lattice dynamics and thermodynamics ofosmium under pressure

We have performed the first-principles linear response calculations of the lattice dynamics, thermal equation of state and thermodynamical properties of hcp Os metal by using the plane-wave pseudopotential method. The thermodynamical properties are deduced from the calculated Helmholtz free energy by taking into account the electronic contribution and lattice vibrational contribution. The phonon frequencies at Gamma point are consistent with experimental values and the dispersion curves at various pressures have been determined. The calculated volume, bulk modulus and their pressure derivatives as a function of temperature are in excellent agreement with the experimental results. The calculated specific heat indicates that the electronic contribution is important not only at very low temperatures but also at high temperatures due to the electronic thermal excitation. The calculated Debye temperature at a very low temperature is in good agreement with experimental values and drops to a constant until 100~K.     

中子共振谱测温的研究和应用

本文简要回顾了中子共振测温技术发展的过程,介绍了该技术在测温特别是冲击加载条件下材料内部测温方面的进展和应用。论述了该技术的理论模型与数据分析方法,探讨了测温共振位选择,测温实验中子源选择,测温数据分析软件等多方面内容。     

沉淀法制备In/ZnO纳米粉及其发光特性

采用沉淀法制备In/ZnO纳米粉,通过XRD和光致发光谱等分析手段,详细讨论了不同In掺杂浓度、煅烧温度、反应物配比,以及沉淀剂种类对In/ZnO纳米粉微结构及光致发光特性的影响。实验结果表明,随着In掺杂浓度的增加,In/ZnO纳米粉的结晶性能和紫外发光强度因杂质缺陷的增多而逐渐减弱;同时观察到该发光峰位从389nm红移至419nm,这可能是由于施主能级和导带的合并,以及杂质能级的潜在波动因素的影响所致。当煅烧温度从500℃升至600℃时,晶粒尺寸逐渐变大,紫外发射强度也因结晶性的增强而逐渐增大;当温度继续升高至800℃时,结晶性的进一步提高导致紫外发射强度增强,同时由于温度的升高使得ZnO晶格中离子动能变大而更易于产生氧空位,从而导致525nm绿光发射也大大增强;当温度升高至1 000℃时,紫外发射强度由于过多的氧空位而被极大抑制,此时525nm绿光发射成为了发光主成份。随着反应物NH4HCO3/Zn(NO3)2摩尔比的增加,由于反应速率的加快,使得In/ZnO纳米粉晶粒变小,紫外发光强度下降。沉淀剂种类(NH4HCO3或NaOH)对前驱体粉末的结晶性能有着显著的影响,但对最终纳米粉产物的发光性能影响不大。