基于可调控多肽纳米管和石墨烯复合纳米结构的光吸收催化平台

近年来, 自组装纳米结构因为其容易制备、稳定、环保以及与各种功能基团、粒子等的多样结合能力吸引了科学家们的目光, 成为人们研究的热点课题, 在光电池、光催化、水凝胶、药物缓释等方面的实验科学领域得到了广泛的应用. 尤其是光催化方面, 自组装结构的重复性为激子的传递创造了比较良好的条件, 成为众多激子传递平台中的佼佼者. 本文报道了一种以苯丙氨酸二肽纳米管和羧基石墨烯为基础的自组装光吸收催化平台, 对其结构进行研究, 并使用该体系进行了烟酰胺腺嘌呤二核苷酸到它的还原态的催化实验. 该体系的微观结构由纳米管和石墨烯膜复合而成, 羧基石墨烯的存在能够降低纳米管直径, 实现纳米管的形态操控, 石墨烯与多肽纳米管复合纳米结构的存在实现了多通道协同激子传递, 降低了激子传递的距离, 极大增强了催化中心对于激子的接受和使用效率. 在复合了光敏剂和催化中心之后, 该体系具有较高的稳定性, 均一的分散性, 很强的光能吸收和转化能力等性质. 对于从NADP⁺往NADPH转变的催化实验表明, 该体系有较高的反应速率和催化效率, 并且比两种单一结构催化平台效果之和更好, 实现了一加一大于二的效应, 展现了复合纳米结构光吸收催化平台的巨大潜力和广阔应用前景.     

高温应变下的晶界湮没机理的晶体相场法研究

应用晶体相场方法研究高温应变下的预熔化晶界位错湮没机理. 结果表明, 原预熔化晶界上的位错在应变作用下发生分离运动, 形成新晶界, 即亚晶界. 该过程的实质是生成了亚晶粒; 亚晶界的迁移过程的本质是亚晶粒长大、吞噬旧晶粒的过程; 亚晶界之间的湮没是亚晶粒完全吞噬旧晶粒过程的结束, 体系转变成为单个晶粒结构. 根据原子密度序参数沿x和y方向的投影值随应变量的变化特征, 可以揭示出高温应变作用下, 预熔化亚晶界相遇湮没的本质是两对极性相反的偶极子位错对发生二次湮没, 该湮没的微观过程是通过位错连续二次滑移湮没而实现的, 其湮没的速率较低温时的湮没速率要小许多.     

基于梯度与曲率相结合的图像平滑模型的研究

在图像处理过程中, 为了在图像去噪时更好地保留图像边缘细节信息, 首先结合扩散系数和曲率的性质建立了一个曲率平滑模型. 考虑到图像受到噪声污染时曲率会发生显著变化, 将图像的水平集曲率作为一个检测因子代入到上述模型中, 提出了一个梯度与曲率相结合的新模型. 分析与仿真结果表明, 该模型与Perona-Malik模型相比较保留了更多的图像信息, 有效地增强了图像尖锐的边缘, 同时很好地保持了图像的直线和曲线边缘、角点、斜坡和小尺度特征, 是一个理想的模型.     

噪声情况下的量子网络直接通信

提出和研究了噪声情况下的量子网络直接通信. 通信过程中所有量子节点共享多粒子Greenberger-Horne-Zeilinger (GHZ)量子纠缠态; 发送节点将手中共享的GHZ态的粒子作为控制比特、传输秘密信息的粒子作为目标比特, 应用控制非门(CNOT)操作; 每个接收节点将手中共享GHZ 态的粒子作为控制比特、接收到的秘密信息粒子作为目标比特, 再次应用CNOT门操作从而获得含误码的秘密信息. 每个接收节点从秘密信息中提取部分作为检测比特串, 并将剩余的秘密信息应用奇偶校验矩阵纠正其中存在的比特翻转错误, 所有接收节点获得纠正后的秘密信息. 对协议安全、吞吐效率、通信效率等进行了分析和讨论.     

基于O2-O2吸收的非相干宽带腔增强吸收光谱浓度反演方法研究

针对传统非相干宽带腔增强吸收光谱浓度反演方法的定量结果易受镜片反射率标定误差的影响问题, 提出了一种基于测量大气O₂-O₂吸收的浓度反演方法. 该方法是将非相干宽带腔增强吸收光谱技术的光学增强腔等效成吸收光程不随波长变化的多次反射池, 首先根据测得的宽带腔增强大气吸收谱和参考谱计算出光学厚度, 并应用差分光学吸收光谱算法拟合修正后的气体吸收截面到光学厚度, 反演得到大气中O₂-O₂以及被测气体的柱浓度, 然后根据O₂-O₂在大气中的含量已知且相对稳定这一特性, 确定出等效多次反射池的吸收光程, 最后从被测气体的柱浓度中扣除吸收光程信息得到被测气体的浓度值. 以监测大气中NO₂实验为例, 应用该方法在454-487 nm波段反演得到了大气NO₂的浓度(1-30 ppbv范围内), 并将反演结果与传统浓度反演方法的结果进行了对比, 发现两者的不一致性在7%以内. 实验结果表明, 非相干宽带腔增强吸收光谱技术可以利用大气O₂-O₂的吸收来定量其他被测气体的浓度, 而且定量结果对镜片反射率的标定误差不敏感.     

Evollionines A–C,Three New Alkaloids Isolated from the Fruits of Evodia rutaecarpa

A phytochemical study of the CHCl₃ extract of the dried unripe fruits of Evodia rutaecarpa (Juss. ) Benth. (Rutaceae) resulted in the isolation of three new alkaloids, evollionines A–C ( 1 – 3 , resp.), together with two known compounds, evodianinine and wuzhuyumide I. The structures of the new compounds were elucidated on the basis of detailed spectroscopic evidence and confirmed in the case of compound 1 by single‐crystal X‐ray analysis.     

Label-free aptasensor for thrombin using a glassy carbon electrode modified with a graphene-porphyrin composite

We report on an electrochemical aptasensor for the ultrasensitive determination of thrombin. A glassy carbon electrode modified with a graphene-porphyrin nanocomposite exhibits excellent electrochemical activity and can be used as a redox probe in differential pulse voltammetry of the porphyrin on its surface. The thrombin aptamer is then immobilized via p-stacking interactions between aptamer and graphene and π-π stacking with porphyrin simultaneously. The resulting electrochemical aptasensor displays a linear response to thrombin in the 5–1,500 nM concentration range and with a limit of detection of 0.2 nM (at an S/N of 3). The sensor benefits from the synergetic effects of graphene (with its high conductivity and high surface area), of the porphyrin (possessing excellent electrochemical activity), and of the aptamer (with its high affinity and specificity). This kind of aptasensor conceivably represents a promising tool for bioanalytical applications.

Local surface plasmon resonance of single silver nanorice particles in the near-infrared

We report on the synthesis and optical spectra of silver nanorice particles. Two strong absorption bands are resolved in the near UV and near-IR region, and the dark field scattering spectra are consistent with the absorption spectra. Finite-difference time-domain simulations reveal that the peak in the IR region can be attributed to the E field that is parallel to the long axis, while the peak in the UV can be attributed to the E field perpendicular to the short axis of the silver nanorice particles.

One-pot two-step tandem reactions for selective synthesis of pyrrolo[2,1-a]isoquinolines and dihydro-, tetrahydro-derivatives

A sequential one-pot two-step tandem reaction for selective and efficient synthesis of pyrrolo[2,1-a]isoquinoline and its dihydro- and tetrahydro-derivatives has been developed. The tandem reactions of isoquinoline, α-halogenated methylene compounds, aromatic aldehydes, and cyanoacetamide firstly give tetrahydropyrrolo[2,1-a]isoquinolines as main products. The corresponding pyrrolo[2,1-a]isoquinolines and dihydropyrrolo[2,1-a]isoquinolines can be obtained directly by controlling oxidation with DDQ. The mechanism of this tandem reaction involved the 1,3-dipolar cycloaddition of isoquinolinium ylide as the key step. A unique elimination of the amido group preferring to the cyano group has been observed.     

Preparation of <Superscript>99m</Superscript>Tc-PQQ and preliminary biological evaluation for the NMDA receptor

Pyrroloquinoline quinone (PQQ), an essential nutrient, antioxidant, redox modulator and nerve growth factor found in a class of enzymes called quinoproteins, was labeled with ^99mTc by using stannous fluoride (SnF₂) method. Radiolabeling qualification, quality control and characterization of ^99mTc-PQQ and its biodistribution studies in mice were performed and discussed. Effects of pH values, temperature, time and reducing agents concentration on the radiolabeling yield were investigated. The quality control procedure of ^99mTc-PQQ was determined by thin layer chromatography (TLC), radio high-performance liquid chromatography (RHPLC) and paper electrophoresis methods. The average radiolabeling yield was 94 ± 1% under optimum conditions of 0.99 mg of PQQ, 30 μg of SnF₂, 0.5 mg of ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) and 18.5 MBq of Na^99mTcO₄ at pH 6 and 25 °C with a response volume of 1 ± 0.1 mL. ^99mTc-PQQ was stable and anionic. Lipid–water partition coefficient of ^99mTc-PQQ was −1.49 ± 0.16. The pharmacokinetics parameters of ^99mTc-PQQ were t _1/2α = 18.16 min, t _1/2β = 100.45 min, K ₁₂ = 0.013 min⁻¹, K ₂₁ = 0.017 min⁻¹, K _e = 0.016 min⁻¹, AUC (area under the curve) = 1040.78 ID% g⁻¹ min and CL (plasma clearance) = 0.096 mL min⁻¹. The dual-exponential equation was Y = 10.88e^−0.038t  + 5.21e^−0.0069t . The biodistribution of ^99mTc-PQQ was studied in ICR (Institute for Cancer Research 7701 Burhelme Are., Fox Chase, Philadelphia, PA 1911 USA) mice. In vitro autoradiographic studies clearly showed that the ^99mTc-PQQ radioactivity accumulated predominantly in the hippocampus and cortex, which had a high density of N-methyl-d-aspartate Receptor (NMDAR). The enrichment can be blocked by NMDAR redox modulatory site antagonists-ebselen (EB) and ^99mTc-PQQ is therefore a promising candidate for the molecular imaging of NMDAR. To date, however, there have been no studies characterizing ^99mTc-PQQ.