Ca置换Y引起的Y（Sr1.75B0.25）（Cu0.5B0.5）O7—δ晶体结构调制

常压下得到的YSr2Cu3O7-δ(YSCO)不是超导体,它属于四方晶系钙钛矿结构,用B置换一部分Cu,得到了YSr2(Cu0.5B0.5)Cu2O7-δ,具有无公度调制结构,但仍不是超导体.进一步用Ba部分置换Sr得到了Y(Sr2-xBax)(Cu0.5B0.5)Cu2O7-δ高温超导氧化物,其无公度调制波矢长度随x的增加而减短[1].再用Ca部分置换Y时,得到(Y1-yCay)(Sr2-xBax)(Cu0.5B0.5)Cu2O7-δ,仍为超导体.而且(x=1.5,y=0.3)时的超导转变温度比(x=0.5,y=0)时高出近20K[2].本文报道了该化合物晶体结构中的调制现象和规律.     

免疫算法

本文在分析标准遗传算法的优越性与存在不足的基础上,借鉴生命科学中免疫的概念与理论,提出了一种新的算法——免疫算法.该算法的核心在于免疫算子的构造,而免疫算子又是通过接种疫苗和免疫选择两个步骤来完成的.理论证明免疫算法是收敛的,并结合TSP问题,提出了免疫疫苗的选取与免疫算子的构造方法.最后,用免疫算法对75城市的TSP问题进行了仿真计算,并将其计算过程与标准遗传算法进行了对比,结果表明该算法对减轻遗传算法后期的波动现象具有明显的效果,同时使收敛的速度有较大的提高.     

可用于弱光探测器的量子线研究进展

以量子线作为导电沟道的场效应弱光探测器可在低工作电压下达到很高灵敏度.文章主要对可用于此种弱光探测器的V型和脊形量子线的生长机理和制备方法进行综述,给出了量子线的PL测试结果.采用MBE外延生长法在V型槽图形衬底上生长了OaAs/AlGaAs量子线FET外延结构,扫描电子显微镜下初步判定在V型槽底部形成了截面近三角形的量子线结构.     

真空退火时间对ZAO薄膜的结构与性能的影响

采用射频磁控溅射法制备了Al掺杂ZnO(ZAO)薄膜,研究了真空退火对其组织结构和光电性能的影响规律.结果表明,所制备的ZAO薄膜厚度均匀、组织致密,具有(002)择优取向的六方纤锌矿结构,400℃真空退火后,薄膜晶粒粗大,(002)晶面择优取向性进一步加强.延长退火时间对薄膜的相结构、组织形貌及晶粒大小没有明显的影响.随着退火时间的增加,薄膜的电阻率呈降低趋势,退火3 h时电阻率最低,为2.25×10-3Ω·cm,但长时间退火,电阻率变化不大.薄膜样品的透光率随真空退火时间的延长先降低,后升高,再降低;样品在真空退火4 h时对可见光的平均透过率最佳,在80%以上.退火后,ZAO薄膜的吸收边发生了蓝移现象,光学禁带宽度增大.     

Support vector machine-based inspection of solder joints using circular illumination

A method for inspecting solder joints using support vector machines (SVMs) and a tiered circular illumination technique is proposed. The illumination technique provides visual information that allows the 3D shape of the solder joint surface to be determined. The extracted features are used to classify the solder joint using an SVM classifier. Experimental results show the effectiveness of the proposed method.     

高可靠电阻式触摸屏的研制

用高温烧结工艺制作的高可靠五线电阻式触摸屏,因ITO方阻更均匀、电极电阻更稳定,而具有更高的线性度和可靠性,可实现在较宽的温度范围内长期工作无漂移.介绍了这种新型五线触摸屏的主要工艺流程、技术难题、关键技术和产品优点.     

CNT-FED背光源中支撑体高度的优化研究

利用丝网印刷技术制备碳纳米管阴极并真空封装碳纳米管场发射(CNT-FED)背光源原型器件,研究了支撑体高度对碳纳米管背光源发射性能的影响,实验表明:支撑体高度增加,开启电压随之增加;达到同样的发射电流密度,支撑体越高,亮度也越高.支撑体高度为1 000 μm和2 000μm时,CNT-FED背光源发射性能较好,在电流密度为4 mA/cm~2情况下,支撑体高度为1 OOO μm时,亮度为1 800 cd/m~2;支撑体高度为2 OOO μm时,亮度为3 100 cd/m~2.选用支撑体高度为2 000 μm,制备出86.4 cm液晶平板显示器(LCD)用CNT-FED背光源,亮度最高可达8 000cd/m~2,发光均匀性为82%,稳定发射30 h,发射电流无明显衰减.     

外部光反馈对980nm垂直腔面发射激光器振荡特性的影响

研究了外部光反馈对980nm垂直腔面发射激光器(VCSEL)振荡特性的影响.计算了垂直腔面发射激光器及边发射半导体激光器的光反馈灵敏因子.基于复合腔理论,分析了外部光反馈对垂直腔面发射激光器的阈值电流及微分量子效率等振荡特性参数的影响.实验结果表明,当反馈率为10%时,垂直腔面发射激光器的阈值电流由0.63A下降至0.59A,同时斜率效率和输出功率也有所下降.实验结果和理论分析符合得较好.     

Mechanically Drawable Thermochromic and Mechanothermochromic Polydiacetylene Sensors

Recently, the development of directly writable techniques for depositing functional materials on solid substrates has received great attention. These pen‐on‐paper approaches enable generation of diverse patterned images on solid substrates in a flexible, easy handling, and inexpensive manner. Herein, the development of a directly writable conjugated polymer is described. Mechanically, drawable colorimetric polydiacetylene (PDA)–wax composites are readily fabricated by using a simple mixing‐molding method. Images are mechanically drawn on a paper substrate using the PDA–wax composites, display thermochromism, and mechanothermochromism. The thermochromic transition temperature is dependent on the melting point of the wax and, as a result, can be precisely controlled by the type of wax used. Optical microscopic analysis shows that formation of the DA–wax composite involves movement of wax molecules into a single diacetylene (DA) crystal. This process results in growth of the crystal. Importantly, the PDA crystal, obtained after UV light irradiation, undergoes significant shrinkage upon heating because of the release of monomers and the embedded wax molecules from the crystal. The release of these molecules creates void in the PDA supramolecules, allowing the PDA chains to undergo C–C bond rotation and hence the blue‐to‐red color transition.     

Noninvasive Transdermal Vaccination Using Hyaluronan Nanocarriers and Laser Adjuvant

Vaccines are commonly administered by injection using needles. Although transdermal microneedles are less invasive promising alternatives, needle‐free topical vaccination without involving physical damage to the natural skin barrier is still sought after as it can further reduce needle‐induced anxiety and is simple to administer. However, this long‐standing goal has been elusive since the intact skin is impermeable to most macromolecules. Here, we show an efficient, noninvasive transdermal vaccination by employing two key innovations: the use of hyaluronan (HA) as vaccine carriers and non‐ablative laser adjuvants. Conjugates of a model vaccine ovalbumin (OVA) and HA—HA–OVA conjugates—induced more effective maturation of dendritic cells in vitro, compared to OVA. Following topical administration in the skin, HA–OVA conjugates penetrated into the epidermis and dermis in murine and porcine skins, as revealed by intravital microscopy and fluorescence assay. Topical administration of HA‐OVA conjugates significantly elevated both humoral and mucosal antibodies, with peak levels at four weeks. An OVA challenge at week eight elicited strong immune‐recall responses. With pretreatment of the skin using non‐ablative fractional laser beams as adjuvant, strong immunization was achieved with much reduced doses of HA–OVA (1 mg kg^–1 OVA). Our results demonstrate the potential of the noninvasive patch‐type transdermal vaccination platform.