玫瑰枝、叶中微量元素含量的测定及动态研究

用原子吸收光谱法对大马士革玫瑰枝、叶中Ca、Mg、Fe、Cu、Mn 5种微量元素的含量进行了测定,并研究了不同生理条件、不同器官中5种元素含量的动态变化规律。结果表明:大马士革玫瑰枝叶中含有丰富的Ca、Mg、Fe、Cu、Mn微量元素,元素含量高低顺序依次为:Ca>Mg>Fe>Mn>Cu;玫瑰叶片中的微量元素含量均明显高于枝条,甚至较枝条要高出一个数量级以上;未开花植株和开花植株微量元素含量的动态变化规律总体上基本相似,但是未开花植株的微量元素含量要显著低于开花植株;在生长季节内,5种微量元素含量各呈现不同的动态变化规律,这与植物的生长发育和元素的植物生理功能密切相关。     

ZnMgO/ZnO异质结构中二维电子气的研究

论文根据ZnMgO/ZnO异质结构二维电子气的能带结构及相关理论模型, 采用一维Poisson-Schrodinger方程的自洽求解, 模拟计算了ZnMgO/ZnO异质结构中二维电子气的分布及其对ZnMgO势垒层厚度及Mg组分的依赖关系. 研究发现该异质结构中ZnMgO势垒层厚度存在一最小临界值: 当垒层厚度小于该临界值时, 二维电子气消失, 当垒层厚度大于该临界值时, 其二维电子气密度随着该垒层厚度的增加而增大; 同时研究发现ZnMgO势垒层中Mg组分的增加将显著增强其二维电子气的行为, 导致二维电子气密度的明显增大; 论文对模拟计算获得的结果与相关文献报道的实验结果进行了比较, 并从极化效应和能带结构的角度进行了分析和讨论, 给出了合理的解释. 关键词： 氧化锌 二维电子气 异质结构 理论计算     

Real-time three-dimensional infrared imaging using fringe projection profilometry

Infrared thermography determines the surface temperature of an object or human body. It is a promising imaging technology for medical and biological observations due to its contactless and completely non- invasive properties. However, traditional two-dimensional （2D） infrared thermography cannot retain the spatial information, and thus provides only qualitative diagnosis information. A novel real-time three- dimensional （3D） infrared imaging system which takes full advantages of high-speed, high-quality, high- sensitivity, and low-cost in 3D thermograph is presented. We demonstrate the real-time 3D thermal imaging at the speed of 24 frmnes per second （fps）, with resolution of 640 ×480 points. Experimental results demonstrate quantitatively measurement of temperature distribution of 3D surfaces in real-time is realized with this system.     

贵金属纳米颗粒的微生物合成

金属纳米颗粒在材料、催化、医学、环境等众多领域应用广泛,其中,金、银、铂、钯等贵金属的纳米颗粒作为良好的催化剂可提高反应的速率,因此,贵金属纳米颗粒的合成吸引了众多研究者的关注。传统的物理化学法虽能高效、可控地合成贵金属纳米颗粒,但是合成条件苛刻、成本昂贵、且会产生对环境有害的化学物质。因此,探索节能、环保、可持续的绿色合成方法成为纳米合成研究的热点之一。贵金属纳米颗粒的微生物合成法具备绿色合成技术的诸多要素,研究表明某些微生物能将金属盐转化成纳米材料,且微生物繁殖速度快、培养成本低、生长条件温和,从而得到了研究者们的广泛关注。本文归纳总结了目前微生物合成贵金属纳米颗粒的主要研究进展,包括贵金属纳米颗粒可能的合成机制以及尺寸与形貌控制方法,探讨了其在医学、催化、生物传感、环境方面的具体应用,并对贵金属纳米颗粒微生物合成的未来发展进行了展望。     

Optical Realization of Deterministic Entanglement Concentration of Polarized Photons

We propose a scheme for optical realization of deterministic entanglement concentration of polarized photons. To overcome the difficulty due to the lack of sufficiently strong interactions between photons, teleportation is employed to transfer the polarization states of two photons onto the path and polarization states of a third photon, which is made possible by the recent experimental realization of the deterministic and complete Bell state measurement. Then the required positive operator-valued measurement and further operations can be implemented deterministically by using a linear optical setup. All these are within the reach of current technology.     

MOCVD生长中载气H2对N掺杂ZnO性质的影响

采用MOCVD方法在石英衬底上生长ZnO。实验使用二乙基锌(DEZn)为锌源,N2O作为氧和氮源,H2作为载气。采用PL和Raman光谱方法对ZnO样品进行表征,结果表明H2的加入大幅度减少薄膜中碳的掺入,明显改善了薄膜的光学质量。采用N2O离化技术,可以进一步提高其带边峰的强度,抑制带内发光。XRD测量表明,生长的ZnO薄膜具有c轴择优取向。目前生长高质量N掺杂的p型ZnO薄膜是很困难的,而H2作为载气的加入明显改善了ZnO薄膜的光学性质,在生长过程中加入H2将为获得高质量N掺杂的p型ZnO薄膜提供一种途径。     

980 nm大功率垂直腔面发射激光器偏振特性

大功率垂直腔面发射激光器单管器件出光口径大、横向模式多。随着注入电流和工作温度的改变出射光偏振态在两个正交偏振基态上转换。为分析输出光偏振特性,采用500μm出光口径980nm底发射器件,通过控制器件热沉温度,利用偏振分光镜分离正交偏振基态为透射波和反射波,半导体综合参数测试仪测量其功率、中心波长等参量。分析得出:两个偏振态的光功率温度特性与未加偏振分光镜时的总输出光的温度特性基本一致,中心波长差随温度升高缓慢增加。在温度低于328K时,随着注入电流的增大,反射波首先达到阈值,形成激射。但透射光波形成激射后其斜效率大于反射波。因此在达到某个电流后两个偏振态的功率变化曲线出现交替。当温度升高到328K以上时两个偏振态的功率曲线却没有明显的交替。根据对大尺寸VCSEL器件偏振特性的研究,提出通过外腔选频的方法来控制偏振的方案,分析计算后得出外腔腔长大约为0.45mm。     

发光铱(Ⅲ)配合物抗肿瘤活性研究及应用

铱(Ⅲ)配合物因其发光量子产率高且波长易调控、发光寿命长和光稳定性好的特点,在发光材料领域备受关注。铱(Ⅲ)配合物细胞渗透能力强,能靶向多种细胞组织并影响其结构和功能,表现出独特的抗肿瘤活性,是目前金属抗肿瘤药物特别是PDT光敏剂方向的研究热点。本文重点关注铱(Ⅲ)配合物的结构对其发光性能与抗肿瘤性能的影响,综述了近期铱(Ⅲ)配合物在生物成像、探针与传感、抗肿瘤诊疗等领域的研究进展,并对目前研究中存在的问题及其应用前景进行探讨和展望。     

Effect of oxygen on regulation of properties of moderately boron-doped diamond films

Regulation of oxygen on properties of moderately boron-doped diamond films is fully investigated. Results show that, with adding a small amount of oxygen (oxygen-to-carbon ratio < 5.0%), the crystal quality of diamond is improved, and a suppression effect of residual nitrogen is observed. With increasing ratio of O/C from 2.5% to 20.0%, the hole concentration is firstly increased then reduced. This change of hole concentration is also explained. Moreover, the results of Hall effect measurement with temperatures from 300 K to 825 K show that, with adding a small amount of oxygen, boron and oxygen complex structures (especially B₃O and B₄O) are formed and exhibit as shallow donor in diamond, which results in increase of donor concentration. With further increase of ratio of O/C, the inhibitory behaviors of oxygen on boron leads to decrease of acceptor concentration (the optical emission spectroscopy has shown that it is decreased with ratio of O/C more than 10.0%). This work demonstrates that oxygen-doping induced increasement of the crystalline and surface quality could be restored by the co-doping with oxygen. The technique could achieve boron-doped diamond films with both high quality and acceptable hole concentration, which is applicable to electronic level of usage.     

解题反思 提高能力

波利亚曾经说,如果学生得到问题的解答,并且很干净利落地写下论证后就会合上课本,去做其他事情.这样做,学生就错过了解题的一个重要而有教益的方面——解题反思.波利亚认为,学生通过回顾所完成的解答,重新考虑与检查这一结果及其解答路径,可以巩固知识,发展解题能力. “解题反思”是指对一道数学题经过艰辛尝试,获得正确的解答过程之后,必须认真进行如下探索:命题的意图是什么?考查哪些方面的概念、知识和能力?验证解题结论是否正确合理,命题所提供的条件的应用是否完备?求解论证过程是否判断有据,严密完善?本题有无其他解法即一题多解?众多解法中哪一种最简捷?把本题的解法和结论进一步推广,能否得到更有益的普遍性结论——举一反三,多题一解?如此种种,就是“解题反思”.