Quantum Inequality Bounds for Free Rarita-Schwinger Field in Flat Spacetime

Although quantum field theory allows the local energy density negative, it also places severe restrictions on the negative energy. One of the restrictions is the quantum energy inequality (QEI), in which the energy density is averaged over time, or space, or over space and time. By now temporal QEIs have been established for various quantum fields, but less work has been done for the spacetime quantum energy inequality. In this paper we deal with the free Rarita-Schwinger field and present a quantum inequality bound on the energy density averaged over space and time.Comparison with the QEI for the Rarita-Schwinger field shows that the lower bound is the same with the QEI. At the same time, we find the quantum inequality for the Rarita-Schwinger field is weaker than those for the scalar and Dirac fields. This fact gives further support to the conjecture that the more freedom the field has, the more easily the field displays negative energy density and the weaker the quantum inequality becomes.     

BEPCⅡ高频发射机和环流器的调整和测试

北京正负电子对撞机升级改造工程(BEPCⅡ)将采用的频率500MHz、输出功率250kW的高频发射机和环流器已安装、调整、测试和验收完毕,这是国内建立的第一套500MHz/250kW发射机系统.本文将详细介绍机器的调测试的原理和各项测量内容及结果, 并比较设计指标和要求,来阐述此发射机的实际技术指标和测试性能.     

形式三角矩阵环上的有限表示模

形式三角矩阵环,又称广义三角矩阵环,这类环及其上的模在环模理论中扮演着重要的角色.本文对形式三角矩阵环上的有限表示模进行了一些探讨.     

蛙虹彩病毒cop基因的克隆表达及亚细胞定位

从蛙虹彩病毒(Rana gryliovirus,RGV)基因组中克隆了含凋亡相关结构域的新基因-cop(Caspaserecruit ment domain only protein,COP)基因的全部编码区,成功构建了重组表达载体,进行了原核表达,并在鲤鱼上皮瘤细胞(Epithelioma papulosumcyprini,EPC)中进行了亚细胞定位.序列分析表明,RGVcop基因全长288 bp,编码一个长为95 aa,分子量为10.4×103的推定蛋白.二级结构预测表明其含有5个α螺旋.同源性比对分析显示,RGVcop与其他6株虹彩病毒及人类cop相关蛋白同源性最高为94%,最低为33%.重组原核表达质粒pET28a-COP转化大肠杆菌BL21后,经IPTG诱导表达,获得一条约14×103的融合蛋白.重组真核表达质粒pEGFPN3-COP转染EPC细胞,经DAPI染色后,在荧光显微镜下观察显示重组蛋白在整个细胞中均有分布.     

Liquid Nuclear Magnetic Resonance Implementation of Quantum Computation in Subspace

Based on the logical labelling method, we prepare an effective pure state in a subsystem of a three spin system via liquid nuclear magnetic resonance technique. Then with this subspace effective pure state we implement the Deutsch-Jozsa algorithm. The tomography for the subspace effective pure state and the corresponding spectrum of the output for the Deutsch-Jozsa algorithm agree with theoretical predictions, which shows that we have successfully implemented the Deutsch-Jozsa algorithm in a subsystem of a nuclear spin system and demonstrated a subspace quantum computation.     

In Situ Observation of Skeletal Shape Transition during BaB2O4 Crystal Growth in High-Temperature Solution

The transition from a fiat solid-liquid interface to a skeletal shape during BaB2O4 （BBO） single crystal growth in Li2B4O7 flux is observed in real time by an optical high-temperature in-situ observation system. The movement of crystal step is also investigated. The observation results demonstrate that the steps propagate along and parallel to the fiat interface when the crystal size is small. Nevertheless, they will ‘bend＇ close to the face centre if the crystal size becomes greater. Atomic force microscopy reveals that more deposition places near the face centre give rise to the bending of advancing steps and thus the formation of a vicinal interface structure. Measurements of step velocity show that the velocity keeps nearly constant at different moments for one specific step, whereas the step on a newly formed layer advanced faster than that on a previously formed one when the crystal size is larger than 210μm or so. Thus interracial morphological instability occurs and a skeletal interface is obtained.     

适用于雷达系统的高温超导窄带滤波器

对雷达系统,通过在接收前端安置高Q、窄带、高带外抑制的滤波器,可以有效减少信号间的干扰,由此可见高性能的滤波器对于雷达系统来说,具有重要作用.与常规滤波器相比,高温超导滤波器具有带边陡峭、插入损耗小、带外抑制高、可以设计极窄带等特点.在本文中,我们设计加工了一种高性能的12阶切比雪夫(Chebyshev)高温超导带通滤波器,其中心频率为1341兆赫兹、带宽为5.035兆赫兹,可用于雷达系统.在滤波器设计中,我们用Sonnet软件对滤波器进行了仿真计算.最后滤波器在以氧化镁为衬底的双面超导薄膜上制作,衬底直径为2英寸、厚度为0.5毫米.测试结果表明,该滤波器符合设计要求,具有很好的选择性和带外抑制.     

微波频率下Ba0.5Sr0.5TiO3薄膜的介电特性随温度及外加偏压变化的检测

提出了一种新的结构来表征钛酸锶钡薄膜在微波频率下的介电特性,即在沉积有钛酸锶钡薄膜的氧化镁基片上制作了共面带阻滤波器.借助于共面带阻滤波器的谐振频率和Q值,通过比较其测量值与仿真值,可以得出钛酸锶钡薄膜的介电常数和介电损耗.在变温测试过程中,注意到金导电层的电导率对带阻滤波器的谐振频率和Q值有较大的影响.为了准确地得到钛酸锶钡薄膜的介电特性,仔细分析了金导电层对带阻滤波器频率响应曲线的影响,并在比较求值过程中消除了这一影响.     

1，4－二氟四苯基苯的合成、结构与构象

借助电子转移催化反应的方法，用电子给予体１，４－二锂四苯基丁二烯将惰性的三溴氟甲烷活化，并与之发生反应，产物１，４－二氟四苯基苯的结构经ＭＳ、ＮＭＲ和Ｘ射线单晶衍射确证，并以分子力学的方法对其进行了构象分析。     

无花果多糖的分离、纯化和鉴定

经脱脂、沸水抽提、乙醇沉淀、酶-Sevag法脱蛋白得到粗多糖,再经DEAE-Sepharose fast flow阴离子交换层析和Sephadex G-200葡聚糖凝胶柱层析得到纯化的无花果多糖(FCPS),用红外光谱和紫外光谱分析鉴定该多糖.红外光谱分析具有典型的多糖特征吸收峰,紫外光谱分析未见蛋白质(280 nm)与核酸(260 nm)的特征吸收峰.结果表明,所提取的无花果多糖为单一组分的多糖.