Laser-induced damage and periodic stripe structures of a CaF_2 single crystal by an ArF excimer laser

The laser-induced damage threshold of a calcium fluoride(CaF2)single crystal was obtained by a 193 nm ArF excimer laser.The damage morphology of the crystal was analyzed.The results showed that the surface of CaF2 single crystal broke along the natural cleavage plane under ArF excimer laser irradiation,some fragments fell off,and Newton’s rings were observed on the curved fragments.Laser-induced periodic stripe structures(LIPSS)appeared on the surface layer beneath the fragments that peeled off.The spacing of LIPSS was measured,and the formation mechanism of LIPSS was analyzed based on the interference model.     

葡萄酒中二氧化硫含量的快速测定

采用凯氏定氮仪对葡萄酒样品进行蒸馏,然后用自动电位滴定仪测定葡萄酒中二氧化硫的含量。考察了凯氏定氮仪与玻璃蒸馏仪、自动电位滴定仪与玻璃滴定管、搅拌速度及滴定速度对测定结果的影响。测定结果显示,凯氏定氮仪-自动电位滴定仪测定结果与GB/T5009.34-2003规定的采用玻璃仪器方法测定结果无显著性差异。该方法的加标回收率为88.8%~103.6%。     

Modulation of Insulator-Metal Transition Temperature by Visible Light in La7/8Sr1/8MnO3 Thin Film

Effects of magnetic field and light illumination on the electrical transport properties of La7/8Sr1/8MnO3 thin film grown on a Si substrate are investigated. The film shows an insulator-metal transition at Tp - 191.9 K and a low-temperature resistance minimum at Tmin ≈ 48 K in darkness. Both magnetic field and light illumination shift the insulator-metal transition temperature Tp to be higher, while the low-temperature transport properties of the film induced by them show different trends. That is, the magnetic field and light illumination make the Tmin shift to lower and higher temperatures, respectively. The enhancement of both Tp and Train under light illumination could be explained in terms of photoinduced hole-doping and demagnetization effects of La7 /8Sr1/8MnO3.     

重复频率脉冲磁场初级能源

为产生重复频率脉冲磁场的螺线管,研制了一种新型的初级能源,它采用半桥串联谐振恒流充电拓扑结构,可在0~2.5 kV范围内实现输出可调,最大平均充电功率达4.7 kW。该电路最大特色在于无需使用外加谐振元件,只利用变压器的漏感和半桥桥臂电容组成谐振元件。简要分析了电路的工作过程,给出了电路参数设计方法和设计实例,并进行电路仿真和初步实验研究,结果表明,该设计基本达到要求。最后,进行了带螺线管负载的实验研究,实验证明该能源在重复频率10 Hz条件下运行稳定可靠。     

(Bi,Pb)_2Sr_2CaCu_2O_y单晶的磁通钉扎研究

我们通过对重Pb掺杂的Bi-2212((Bi,Pb)-2212)单晶磁化性质的测量来研究磁通钉扎性能,发现样品中存在与温度有明显依赖关系的鱼尾效应,且此鱼尾效应不仅体现在磁滞洄线上,还体现在不同磁场下零场冷的M～T曲线的交叠上.同时我们采用非线性磁通蠕动模型,并考虑表面位垒和体钉扎的影响,运用数值模拟分析了样品的磁化性质,结果表明(Bi,Pb)-2212单晶的鱼尾效应源于重Pb掺杂导致样品各向异性的降低所引起的强的体钉扎效应,而高温的磁化性质主要取决于表面位垒的作用.     

方孔微通道板结构缺陷对成像质量的影响

方孔微通道板(MCP)作为一种新型X射线波段光学成像系统,因其具有大视场、高分辨率、能够收集大量辐射并将其准直或聚焦等优点,越来越多地受到了人们的关注。但在MCP制作和加工过程中,难免会使微通道产生一定的结构缺陷,对其成像质量造成严重的影响。利用Tracepro软件建立了标准方孔MCP模型和具有不同结构缺陷的MCP模型,并基于蒙特卡罗(MTC)光线追迹方法对这些模型进行模拟成像。分别讨论了Taper型、Twist型和Nonsquare型结构缺陷对成像质量的影响。然后以溴钨灯作为光源,在可见光波段对实验室现有的4块方孔MCP进行了成像实验,所得实验结果与模拟结果基本吻合,验证了模拟结果的正确性。模拟和实验结果表明,以上3种结构缺陷均会造成十字像中央亮斑面积增大、强度降低等情况,所不同的是Taper型结构缺陷使会聚光线分裂成两条,而这两组平行的会聚线相交形成4个焦点,其能量要比单一聚焦能量衰减很多,从而对成像质量影响更大。该研究为今后研究曲面MCP和基于MCP的X射线光学系统奠定了重要基础。     

Study of aluminum coating prepared by PVD used as anti-corrosion in liquid lead-bismuth

Liquid metals-such as lead （Pb） or lead-bismuth （PbBi） are used as reactor core coolants for accelerator driven systems （ADS） proposed for high-level radioactive waste transmutation. Compatibility of steels with liquid PbBi is a key problem because steels are attacked by dissolution of the components in PbBi, so it has to form a stable coating on steel surface. There are many methods to prepare anti-corrosion coatings on steel, such as hot dipping, pack cementation, plasma spaying, and physical vapor deposition （PVD）. Compared with other methods, the PVD method is easy to control the thickness of the coating and the obtained coatings are dense which is crucial to the anti-corrosion ability of the coatings. In this letter, PVD aluminum coatings are developed on the surface of T91 steel and different heat-treatment atmosphere is used to adjust the microstructure, aluminum content, and the phase of the coatings. It is found that the coatings have good adherence ability with steel. The aluminum content and the phase of the coating can be adjusted by the heat-treatment atmosphere. Corrosion tests are performed in oxygen-saturated liquid PbBi at 550 ℃ for 1 000 h, the phase and composition of the coating do not change drastically. All the results indicate that the PVD is a useful method to prepare coatings on the surface of steel used in liquid PbBi.     

单晶二氧化钛纳米棒阵列的修饰及其在量子点敏化太阳电池中的应用(英文)

使用TiCl4溶液对单晶TiO2纳米棒阵列(TNRs)进行修饰,通过在TiO2纳米棒表面合成TiO2纳米颗粒来提高TNRs的表面积,提高TNRs对量子点的吸附能力,并在此基础上研究了TiCl4修饰时间对基于单晶TNRs的CdS/CdSe量子点敏化太阳电池光伏性能的影响,同时结合强度调制光电流谱(IMPS)研究了TiO2纳米棒阵列的电子传输性能.结果表明:TiCl4修饰可以大幅提高基于单晶TNRs的CdS/CdSe量子点敏化太阳电池的光伏性能,在TiCl4修饰时间为60 h时,其短路电流密度和光电转换效率分别由修饰前的(2.93±0.07)mA·cm-2和0.36%±0.02%提高至(8.19±0.12)mA·cm-2和1.17%±0.07%.同时,IMPS测试表明电子在单晶TiO2纳米棒阵列中的传输速率高于在TiO2纳米颗粒薄膜中的传输速率,证明了单晶TiO2纳米棒阵列在电子传输方面的优越性.     

菊苣体外干物质消化率近红外分析模型的建立

菊苣(Cichorium intybus L.)是一种新型的高产优质饲用牧草,具有极大的推广利用价值。体外干物质消化率(in vitro dry matter digestibility,IVDMD)是评价饲草营养价值的重要指标之一。建立菊苣体外干物质消化率的NIRS定量分析模型的研究,采集了72个品种、不同基因型、不同生长发育时期的204个菊苣地上部分为样品,应用傅里叶变换近红外漫反射光谱技术,通过采用不同的回归算法,比较不同的光谱范围和光谱预处理方法,建立了8个菊苣体外干物质消化率(IVDMD)的近红外漫反射光谱校正模型,从中选出最佳参数的校正模型。其校正决定系数(R2cal)和外部验证决定系数(R2val)分别为0.953 17和0.904 55,校正标准差(RMSEC)和预测标准差(RMSEP)分别为1.977 99%和2.008 82%,预测值与化学值间的相关系数(r)达0.951 08。结果表明,利用近红外漫反射光谱法来测定菊苣体外干物质消化率(IVDMD)是可行的,可为菊苣体外干物质消化率(IVDMD)的测定提供快速的分析测定方法。     

磁场对碳纸上磁电沉积的AuPt颗粒性能的影响

AuPt纳米颗粒是一种催化锂空气电池空气电极上氧气还原反应和氧气析出反应的双功能催化剂．在电沉积制备AuPt颗粒的过程中施加了磁场,恒电流沉积条件下,随着磁场强度的增加,AuPt催化剂颗粒的粒径从1 μm减小到200 nm,同时催化活性增大．垂直于电场方向的磁场有助于提高AuPt/C空气电极的催化能力．使用脉冲电沉积,结晶粒径可减小至约100 nm．通过调节电场和磁场参数,可原位制备具有不同形貌、不同组成和催化性能的AuPt催化剂．