日本研究SERS的现状

本文是作者1986年3月访问中国时的报告。文中介绍日本研究SERS(Surface enhan-ced Raman scatterjng)小组的最近成果。在实验方面,林(Hayashi)等人获得enhance--ment η接近SPP(surface plasmon ploariton)模型所予测的值;山田(Yamada)等人认为出现SERS现象中,化学吸附起着本质性的重要作用。理论方面,上羽(Ueba)等人应用(曲豆)(冫尺)(Toyozawa)等人的理论计算了:(1)允许少量电荷在表面连续能级和吸附分子激发状态之间转移的物理吸附系统共振;(2)电荷转移(CT)给Raman散射光强度及其光谱带来的影响。     

Fabrication and Mossbauer Study of FeCo Alloy Nanotube Array

Arrays of FeCo nanotubes are fabricated in the pores of porous anodic aluminium oxide templates. Transmission electron microscopic result shows that the nanotubes are regular and uniform. Magnetic hysteresis loops measured at room temperature are different from those of nanowires with the same composition, which are caused by the unique shape of nanotubes. The M6ssbauer spectra show that the hyperfine field is smaller than that of the bulk＇s and increases with decrease of measuring temperature. However, the areas of the doublets appeared in M6ssbauer spectra decrease with decrease of measuring temperature.     

二肽肽酶Ⅳ抑制剂的三维定量构效关系研究

二肽肽酶Ⅳ是一类用于治疗Ⅱ型糖尿病具有潜在价值的关键酶,很多此类酶的抑制剂用于处理此病具有相当好的有效性.一系列N-取代的甘氨酰氰基吡咯烷衍生物对于二肽肽酶具有高的活性和选择性.我们使用比较分子力场分析方法建立DPP-Ⅳ抑制剂--N-取代的甘氨酰氰基吡咯衍生物的三维定量构效关系,该模型为设计用于治疗Ⅱ型糖尿病的高效DPP-Ⅳ抑制剂提供结构信息.CoMFA模型的交叉验证相关系数q2=0.575,非交叉验证相关系数r2=0.981,绝对误差S=0.184,F9.68=388.5.使用七个预测集检验了模型的预测能力.所得的模型解释了已有的构效关系,并对同类化合物有较好的预测能力,该模型可用于指导新型的DPP-Ⅳ抑制剂的设计与优化.     

液流的空吸作用演示实验

在没有专门演示空吸作用的仪器,也没有自来水的条件下,我们用如图所示的简易装置完成了液流的空吸作用的演示实验。实验效果很好。T形管2装在离实验台约40厘米高的铁架上。a端用长约80厘米的橡皮管l与水桶相连。水桶放在离实验台50厘米高的地方,内装满水。由于虹吸作用,水通过橡皮管l流过T形管。为了便于控制,在橡皮管上安一个橡皮管夹k。T形管的b端用长约1.5米的橡皮管     

Mechanical Properties of Single-Walled （5,5） Carbon Nanotubes with Vacancy Defects

First-principles simulation is used to investigate the structural and mechanical properties of vacancy defective single-walled （5,5） carbon nanotubes. The relations of the defect concentration, distribution and characteristic of defects to Young＇s modulus of nanotubes are quantitatively studied. It is found that each dangling-bond structure （per supercell） decreases Young＇s modulus of nanotube by 6.1% for symmetrical distribution cases. However the concentrative vacancy structure with saturated atoms has less influence on carbon nanotubes. It is suggested that the mechanical properties of carbon nanotubes depend strongly upon the structure and relative position of vacancies in a certain defect concentration.     

低温固相反应法制备的NiFe2O4纳米颗粒的结构与磁性

采用低温固相反应法制备了晶粒尺寸在8—47nm之间的NiFe₂O₄纳米颗粒系列样品，用X射线衍射仪(XRD)、高分辨中子粉末衍射谱仪、振动样品磁强计和超导量子干涉仪等对样品的晶体结构、宏观磁性和纳米颗粒的表面各向异性进行了分析研究.XRD和中子衍射测量结果显示纳米颗粒的晶格常数略高于块体材料，样品的氧参量表明纳米颗粒的晶格畸变程度没有块体材料严重.相对块体材料，纳米颗粒具有较小的磁化强度、较大的矫顽力和各向异性能密度.纳米颗粒从多畴转变为单畴的临界尺寸约为40nm，超顺磁性临界尺寸约为16nm.     

Tb0.3Dy0.7(Fe1-xAlx)1.95合金的自旋重取向和穆斯堡尔

系统研究了室温和77K温度时Tb0.3Dy0.7(Fe1-xAlx)1.95(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.35)合金中金属Al替代Fe对自旋重取向和穆斯堡尔谱的影响. 结果发现,Tb0.3Dy0.7(Fe1-xAlx)1.95合金的易磁化方向随成分和温度在{110}面逐渐偏离了立方晶体的主对称轴,即自旋重取向. 室温下,当x=0.15时,Tb0.3Dy0.7(Fe1-xAlx)1.95合金中出现了少量非磁性相;x>0.15时,合金完全呈顺磁性;而77K温度下,x=0.2时合金仍然呈磁性相. 在室温和77K温度时,超精细场Hhf均随Al元素的增加而减小,而同质异能移IS随Al元素的增加而增加,四极劈裂QS随Al含量呈无规律的变化.     

Microstructure evolution of T91 steel after heavy ion irradiation at 550 ℃

Fe-Cr ferritic/martensitic (F/M) steels have been proposed as one of the candidate materials for the Generation IV nuclear technologies. In this study, a widely-used ferritic/martensitic steel, T91 steel, was irradiated by 196-MeV Kr⁺ ions at 550 ℃. To reveal the irradiation mechanism, the microstructure evolution of irradiated T91 steel was studied in details by transmission electron microscope (TEM). With increasing dose, the defects gradually changed from black dots to dislocation loops, and further to form dislocation walls near grain boundaries due to the production of a large number of dislocations. When many dislocation loops of primary a₀/2<111> type with high migration interacted with other defects or carbon atoms, it led to the production of dislocation segments and other dislocation loops of a₀<100> type. Lots of defects accumulated near grain boundaries in the irradiated area, especially in the high-dose area. The grain boundaries of martensite laths acted as important sinks of irradiation defects in T91. Elevated temperature facilitated the migration of defects, leading to the accumulation of defects near the grain boundaries of martensite laths.     

Microwave Magnetic Properties of Nd2Fe17N3-δ with Planar Anisotropy

Microwave magnetic properties are studied for rhombohedral structure Nd2Fe17N3-δ with planar magnetic anisotropy. Its resin composites show the permeability μ＇0 = 4.15 at low frequency, the natural resonance frequency fT = 1.71 GHz and the resonance bandwidth 6.66 GHz. The calculated static permeability of Nd2Fe17N3-δ reaches 133. The microwave magnetic properties are determined by the c-axis anisotropy field, basal plane anisotropy field and high saturation magnetization. Based on microwave measurement and theoretical fitting on complex permeability spectra, Nd2Fe17N3-δ may be a promising microwave absorber with bandwidth wider than traditional hexaferrites materials in GHz ranges.