Magnetic properties and magnetocaloric effects in amorphous and crystalline Gd55Co35Ni10 ribbons

The magnetic properties and magnetocaloric effects of amorphous and crystalline Gd55Co35Ni10 ribbons are investigated.A main phase with a Ho 12 Co 7-type monoclinic structure(space group P21/c) and a minor phase with a Ho4Co3-type hexagonal structure(space group P63/m) are obtained for crystalline ribbon after annealing.The amorphous ribbons order ferromagnetically and undergo a second-order transition at 192 K.For crystalline Gd55Co35Ni10 ribbons,two magnetic phase transitions occur at 158 and 214 K,respectively.The peak value of-△SM under a field change of 0-5 T is 6.5 J/kg K at 192 K for amorphous Gd55Co35Ni10 ribbons.A relatively large magnetic entropy change(～5.0 J/kg K) under a field change of 0-5 T for the crystalline Gd55Co35Ni10 ribbons is obtained in the temperature interval range of 154-214 K.The large platform of magnetic entropy change and the negligible thermal/magnetic hysteresis loss mean the crystalline Gd55Co35Ni10 compound can satisfy the requirement of the Ericsson-type refrigerator working in the temperature range from 154K to 214K.     

Trapping and diffusion behaviors of helium at vacancy in iron from first principles

We investigate the structure,trapping,and diffusion behaviors of helium(He) at vacancy in a Fe single crystal using first-principles simulations.Vacancy with more space can provide the lower electron density region for He binding in comparison with intrinsic Fe,causing He to diffuse into the vacancy inner easily.We provide the quantitative microscopic studies related to the atomic-level thermo-kinetic trapping processes.Moreover,such physical viewpoint can be applied to other vacancy-like defects such as vacancy clusters,void and grain boundaries which can open a space with reduced electron density region to increase He binding in metals and metal alloys.     

Optical bistability based on surface plasmon coupled between two noble metal films involving Kerr materials

We successfully investigate an optical bistability phenomenon in a layered structure consisting of Kretschmann configuration involving the Kerr-type nonlinear and the silver film. Pure theoretical approaches are employed to investigate that the surface plasmon could easily be coupled and both the reflection and transmission curves versus the incident intensity forms optical bistability. The transmission curves are greatly influenced by the thickness of the second silver film. These results may be useful for designing novel surface plasmon-based optical devices and will be essential for future classical and quantum information processes.     

黄芩中黄芩苷的亚临界水提取及高效液相色谱分析

建立了黄芩药材中黄芩苷的亚临界水提取 高效液相色谱测定方法。分别考察了温度、压力、提取时间、提取物颗粒度、溶剂比等因素对提取量的影响,并与有机溶剂提取法比较。结果表明,当两者具有相同的提取效果时,亚临界水提取法的提取时间及提取溶剂的消耗量大大减少,避免了使用有机溶剂造成的污染。黄芩苷提取最佳条件为:样品颗粒度80～100目,溶剂比0.2 mL/mg ,5 MPa,130 ℃保持10 min。并通过提取 高效液相色谱联机分析实现了对提取物的实时监测。该技术有望成为从中药材中提取脂溶性成分的有效方法。     

碱化法制备聚合氯化铁絮凝剂的稳定性和形态分布研究

采用碱化法制备高浓度聚合氯化铁工艺得到了不同碱化剂和稳定剂的不同加入时间对形态分布的影响，以及碱化剂加入速度和碱化度对稳定性的影响，研究结果表明：作为碱化剂，NaHCO3优于NaOH；先加入稳定剂的制备方法对提高PFC的稳定性及混凝特性有利；在碱化度B=0．4时制备的PFC稳定性最差。     

非晶态NdxT1-x(T=Fe,Co,Ni)薄膜的低温磁性

本文讨论了非晶态Nd_xT_1-x(T=Fe,Co,Ni)薄膜为滋结构,以及在低温下磁化强度随温度变化的反常特性,在20K附近观测到磁化强度有陡降现象,并且在较大的成份范围内所对应的温度基本不变,我们认为,在这类非晶态合金中,当Nd含量超过一定值后,其磁中性态(通称基态)可能同时是散反铁磁性和散铁磁性的共存态,在20K附近的磁化强度发生陡降,是散反铁磁性←→顺磁性相转变的反映,这两种磁结构共存的临界成份相应约为:Nd-Fe情况x≥0.45;Nd-Co,x≥0.20;Nd-Ni,x≥0.08。 关键词：     

非平衡超导体在Tc附近的电阻态

离T_c不太远时,隧道注入准粒子,使Sn膜进入非平衡状态,注入到一定强度时,非平衡超导膜上出现电压,这种电压类似于N-S界面电阻,越靠近T_c越大,但相应的电阻值比N-S界面电阻大几个数量级,并且注入增强到一定程度时,电阻值会突然减小,甚至消失。 关键词：     

衍射相关和Lau干涉

本文用离轴傅里叶变换系统的模型和菲涅耳衍射理论分析了衍射受限下的离焦相关器的系统特性,证明是第一模板和第二模板衍射像之间的强度相关积分。推导了衍射相关器作为测量相位物体的干涉仪的一般理论,这时要求编码板函数能衍射自成像并且相关函数为周期性函数。讨论了平行光栅作为编码板时的干涉仪的横向剪切干涉特性,给出了实验结果。本文还证明了衍射相关器是推广到任何平面物体在任何观察距离上的Lau效应装置。衍射相关干涉仪产生Lau干涉条纹,并且是直接应用Lau效应的干涉仪。 关键词：     

等离子体色散函数的数值计算研究

一、引言 文[1]建立了关于等离子体色散函数的四极点近似式Z_(53),但其相对误差较大。本文研究结果表明,根据等离子体色散函数的幂级数展开与渐近展开的直接形式,适当地截取有限项,即可解决大多数关于等离子体色散函数Z(s)的数值计算问题。     

HL-1装置等离子体特性的初步研究

HL-1装置在环向磁场2.3T下运行,获得135kA平衡稳定等离子体,平顶时间160ms。实验表明,环向磁场杂散分量约为纵场的万分之一,导体壳和平衡场基本上能保证等离子体的平衡。观察到的电子温度约500eV,平均电子密度2.8×10~(13)cm~(-3),能量约束时间10ms,有效电荷数小于3,最低稳定运行安全因子2.5,最长放电持续时间1040ms。在对MHD稳定性进行观察的基础上,确定了稳定运行区域;极限密度服从Murakami定标律。