Novel Rearrangement of Small Peptides in Electrospray Ionization Tandem Mass Spectrometry

Electrospray ionization mass spectrometry (ESI-MS) is a powerful method for sequencing peptides. A novel fragmentation pattern with the loss of a neutral fragment of 45 Da was observed with the dipeptides, tripeptides,tetrapeptides and pentapeptides containing phenylalanine or histidine residues. A novel rearrangement reaction with the extrusion of a formamide piece was studied and the rearrangement mechanism was proposed and confirmed by deuterium labeling experiments with ESI-MS^n and high-resolution mass spectrometry. These findings are potentially helpful in identifying the specific sequence pattern in the peptide sequencing.     

Pd/1,3-双(二苯基膦)丙烷催化苯并噁唑C-2位直接芳基化反应的研究（英文）

利用简单商业可得的Pd Cl2和1,3-双(二苯基膦)丙烷(dppp)作催化剂,高效催化了苯并噁唑和溴苯C-2取代的芳基化反应.该催化体系表现出了很好的官能团容忍性,当催化剂用量为0.1 mol%时,反应6 h收率可达90%以上,更重要的是,当催化剂用量低至0.01mol%时,通过延长反应时间,转化率仍然能达到90%以上.通过汞中毒实验,透射电镜和X射线光电子能谱证实了该反应是钯纳米粒子催化的过程.此外,通过控制实验证实了底物苯并噁唑在反应过程中经历了开环和关环的途径.最后,通过热过滤和高分辨质谱实验从一定程度上证实了该反应可能经历了Pd(0)-Pd(II)的反应历程.     

pH/酶/光热多重响应的金纳米笼/透明质酸核壳结构纳米载体的制备与性能

以金纳米笼(AuNC)为核, 巯基化改性的透明质酸(LC-HA)为壳, 盐酸阿霉素(DOX)为药物模型, 通过简单的一锅法制备了核壳结构载药纳米粒子DOX@AuNC@HA(DAH). 金纳米笼为药物装载提供容器且赋予载体光热性能, 改性的透明质酸对金纳米笼进行包封并提供pH/酶响应及靶向介导功能. 对DAH的结构进行了表征, 并进行了载药、 控释性能以及细胞摄取和细胞毒性的研究. 结果表明, 核壳结构纳米微粒DAH具有较高的载药能力, 在激光源的照射下具有较好的循环稳定性和较高的光热转换率. 在pH=7.4的磷酸盐缓冲液中, DAH具有较高的稳定性, 20 h的药物泄露率低于20%; 而在酸性环境、 透明质酸酶(HAase)及光热作用下, DAH均能较快地释放出装载的药物, 展现出较好的刺激响应性. 此外, DAH能够更多地被肿瘤细胞摄取, 表现出一定的靶向性; 当化疗与光热疗法共同作用时, 肿瘤细胞的活性大大减弱, 展现出了联合疗法的优势及潜力.     

基于石墨烯光子晶体光纤的流体传感器

与传统的传感器设备阵列相比,由于结构更为简单,具有广泛检测兼容性的光纤系统逐渐成为分布式监测的有力候选者。然而,受工作机制的限制,大多数光纤传感器仍局限于对折射率等物理参数进行探测,一种用于环境化学监测的全光纤分布式传感系统亟待研发。本工作中,我们向化学气相沉积法生长的石墨烯光子晶体光纤(Gr-PCF)中引入了一种化学传感机制。初步结果表明,石墨烯光子晶体光纤可以选择性地检测浓度为ppb级的二氧化氮气体,并在液体中表现出离子敏感性。石墨烯光子晶体光纤与光纤通信系统的波分、时分复用技术结合后,将为实现分布式光学传感环境问题提供巨大的潜力和机会。     

Finite-Key Analysis for a Practical High-Dimensional Quantum Key Distribution System Based on Time-Phase States

High-dimensional quantum states key distribution(HD-QKD) can enable more than one bit per photon and tolerate more noise. Recently, a practical HD-QKD system based on time-phase states has provided a secret key at Mbps over metropolitan distances. For the purposes of further improving the secret key rate of a practical HD-QKD system, we make two main contributions in this work. Firstly, we present an improved parameter estimation for this system in the finite-key scenario based on the Chernoff bound and the improved Chernoff bound. Secondly, we analyze how the dimension d affects the performance of the practical HD-QKD system.We present numerical simulations about the secret key rate of the practical HD-QKD system based on different parameter estimation methods. It is found that using the improved Chernoff bound can improve the secret key rate and maximum channel loss of the practical HD-QKD system. In addition, a mixture of the 4-level and 8-level practical HD-QKD system can provide better performance in terms of the key generation rate over metropolitan distances.     

基于空间密度聚类的改进KRX高光谱异常检测

高光谱遥感影像包含了丰富的光谱信息,对于地物具有极强的分辨能力,从而促进了不需任何先验信息的高光谱异常目标探测技术的发展。KRX（Kernel RX）异常探测算法巧妙地利用核函数将RX算法映射至高维特征空间,加强了光谱中非线性信息的运用,具有较强的可分辨性,显著改善了低维空间的光谱不可分问题。然而,也暴露了KRX算法中病态Gram矩阵求逆误差大,异常检测效率低等缺点。为实现理论上KRX算法的强探测性能,提出一种基于新型聚类方法的改进KRX探测算法（DC-KRX）。（1）由于空间邻域像元具有较强的光谱相似性,会造成Gram矩阵病态,严重影响了异常探测效果,因此背景虚检现象严重。针对病态Gram矩阵的求逆误差问题,算法改进了KRX算子,对Gram矩阵进行奇异值分解,选取特征值较大的主成分,保证了Gram矩阵的求逆精度,待测像元的探测结果采用l-2范数表示,检测效果提高明显;（2）在改进KRX的基础上,提出了空间聚类KRX算法。空间像元之间具有光谱强相关性,既造成了Gram矩阵的病态,数据的冗余也影响了探测效率。实验发现,通过聚类算法可以合并像元于聚类中心,减少空间维度,提高计算效率;同时,聚类中心按照聚类大小被赋予不同的权重,保证了探测精度;（3）另一方面,选用合适的聚类算法是一个难点。聚类KRX算法对于聚类算法的精度和实时性要求较高,比较发现,一种基于密度峰值快速搜索（DC）的新型聚类算法具有较好的聚类性能。算法采用欧式距离计算任意像元的相似度,利用局部密度和邻域距离作为聚类中心的联合判断准则,对结果进行排序得到聚类中心。实验发现,该聚类算法计算速度快,且能够对任意形状的分布进行聚类,非常适合于维度较高,成分复杂的高光谱图像,且适用于较高次数的重复聚类。DC-KRX算法提供了一种空间聚类预处理的高光谱异常探测新思路,最后,与国际主流探测算法对比发现,该算法表现了较好的探测性能。同时,时效性对比分析发现,聚类前后算法的检测效率提高了30%以上,有效改善了KRX算法的实时性。     

“油青种”翡翠的矿物学特征及颜色成因

采用X射线衍射、红外吸收光谱及扫描电镜等现代测试方法,对“油青种”翡翠的矿物学特征及颜色成因进行了深入研究。X射线衍射分析结果显示,“油青种”翡翠“肉”的矿物组成为较纯的硬玉,而“皮”由硬玉、绿泥石及纤蛇纹石等三种矿物组成。红外吸收光谱分析所揭示的矿物组成与X射线衍射较为一致,同时发现“油青种”翡翠“肉”及“皮”具有~2 956,~2 919和~2 850 cm-1等三个典型有机质的特征吸收峰。“油青种”翡翠“肉”中硬玉呈现明显的柱状,结晶程度明显好于“皮”中的硬玉,但“皮”中硬玉比“肉”中硬玉明显富含Mg,说明“皮”中硬玉发生过强烈的水/岩反应。纤蛇纹石仅在“油青种”翡翠的“皮”中出现,晶面呈现明显的弯曲状。在“油青种”翡翠“肉”的裂隙处及“皮”中均发现片状绿泥石的存在,可能为“油青种”翡翠致色的主要原因。形成于还原性水/岩反应的绿泥石,会吸附或者包裹一定量的有机质,导致“油青种”翡翠出现有机质的特征吸收峰。     

Round-robin differential quadrature phase-shift quantum key distribution

Recently,a round-robin differential phase-shift(RRDPS) protocol was proposed[Nature 509,475(2014)],in which the amount of leakage is bounded without monitoring the signal disturbance.Introducing states of the phase-encoded Bennett-Brassard 1984 protocol(PE-BB84) to the RRDPS,this paper presents another quantum key distribution protocol called round-robin differential quadrature phase-shift(RRDQPS) quantum key distribution.Regarding a train of many pulses as a single packet,the sender modulates the phase of each pulse by one of {0,π/2,π,3π/2},then the receiver measures each packet with a Mach-Zehnder interferometer having a phase basis of 0 or π/2.The RRDQPS protocol can be implemented with essential similar hardware to the PE-BB84,so it has great compatibility with the current quantum system.Here we analyze the security of the RRDQPS protocol against the intercept-resend attack and the beam-splitting attack.Results show that the proposed protocol inherits the advantages arising from the simplicity of the RRDPS protocol and is more robust against these attacks than the original protocol.     

Organic Light Emitting Diodes Using Doped Alq3 as the Hole-transport Layer

Effects of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane （F4TCNQ） doping on the hole conductivity of Alq3 layer are measured. In the hole-only device of Alq3, the current densities increase in 1-3 orders of magnitude upon doping with F4TCNQ, suggesting that the doping can effectively enhance the hole-injection and hole- transport ability of Alq3. An organic light-emitting device using an F4TCNQ doped Alq3 layer as the hole- injection and hole-transport layer, and pristine Alq3 as the electron-transport and emitting layer is fabricated and characterized. Bright emission is achieved in the simple OLED with p-doped Alq3 as the hole-transport layer and the intrinsic Alq3 as the electron-transport and emitting layer. The emitting efficiency and brightness of the device are further improved by inserting a thin electron block layer to confine the carrier recombination zone in the middle of the organic layers.     

外部光反射参数对LED显示屏全视角对比度的影响

由于对比度计算方法的局限性使得计算得到的对比度值与LED显示屏在实际中的显示效果会出现不吻合的现象。针对此现象主要对两个方面的内容进行分析。首先,分析LED测量方法中对比度与视角之间的相互关系,在此基础上建立各视角对比度参数。并且利用实际测得的此参数结果与通过LED测量方法计算的数据作对比,表明利用计算方法计算得到的对比度值与实际上在复杂因素的影响下采集得到的对比度结果存在差异,证实各视角对比度参数的计算方法存在问题。其次,分析外部影响参数如测量角度、反射参数在简单光照明下的模型,利用此模型计算得到背景亮度函数曲线,并与实验测得的背景亮度结果作对比,证明了两者结果的一致性。在此基础上,就可以以此模型为背景亮度函数式建立新对比度函数表达式,通过此表达式模拟显示屏上各视角对比度,使得到的函数曲面与使用LED测量方法计算得到的函数曲线相比较,证实LED测量方法中对比度计算方法的理想化,并说明了产生上述不吻合现象的原因。