近红外拓扑方法在南疆红枣品质分析中的应用

从南疆红枣的物理和光谱特征两方面,通过反复调整和逐步细分相结合的方法,给出红枣品质细分和特征因子分析框图。实际应用中可依据不同需要设置最佳光谱参数来提高光谱重复性和质量。实验分离出南疆红枣常见的裂口褐变、色泽和成分等光谱特征因子,如褐变特征因子明显尖峰特征谱线位置10 170cm-1。通过光谱图的特征分析,初步建立了红枣近红外光谱和部分品质之间的对应关系,为下一步红枣品质编码奠定了基础。该方法可节省大量重复建模费用,在建立红枣近红外品质分析标准和模型库共享方面有较好的应用前景。     

Interactions between CdSe/CdS quantum dots and DNA through spectroscopic and electrochemical methods

The interaction of CdSe/CdS quantum dots (QDs) with Herring sperm-DNA (hs-DNA) has been studied by UV-vis spectroscopy and electrochemical method. Cu(phen)₂^2+/1+ (phen = 1, 10-phenanthroline) was used as an indicator for electroactive dsDNA or ssDNA. The apparent association constant has been deduced (4.94 × 10³ M⁻¹ and 2.39 × 10² M⁻¹) from the absorption spectral changes of the dsDNA-QDs and ssDNA-QDs. The results of dissociation method suggest that Cu(phen)₂^2+/1+ is more easily dissociated from dsDNA or ssDNA modified gold electrode (dsDNA/Au or dsDNA/Au) in presence of QDs. The dissociation rate constant (k) of Cu(phen)₂^2+/1+ on dsDNA/Au is 4.48 times higher than that in absence of QDs, while k is 2.34 times higher than that in absence of QDs on ssDNA/Au in Tris buffer with low ionic strength (pH 7.0, 0.5 mM NaCl). The results illuminate that hs-DNA has high affinity for QDs due to electrostatic force, hydrogen bonds, and van der Waals interactions, and the binding force of QDs with dsDNA is stronger than ssDNA.     

Abrasive resistance of arc sprayed carbonitride alloying self-shielded coatings

Wear-resistant coatings were prepared on the surface of the Q235 low-carbon steel plate by HVAS with the carbonitride alloying self-shielded flux-cored wire. Detection and analysis on the microstructure and properties of the coatings were carried out by using scanning electron microscope, microhardness tester and wear tester. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that the coatings have good forming, homogeneous microstructure and compact structure. The coatings have good hardness, the average microhardness value reaches 520 HV_0.1, and the highest value is up to about 560 HV_0.1. As a result, the coatings have good abrasive wear performance and adhesion strength.     

Co掺杂量对Ti1-xCoxO2纳米颗粒结构及磁性的影响

以钛酸丁酯、六水硝酸钴等为原料,采用溶胶凝胶法合成Ti1-xCoxO2干凝胶前驱体,将前驱体在500℃空气氛围下进行退火处理,得到一系列Ti1-xCoxO2纳米颗粒样品.采用差热/热重综合热分析仪(TG-DTA)、X射线衍射仪(XRD)、拉曼光谱(Raman)和振动样品磁场计(VSM)对样品的结构和磁性进行研究.结果表...     

Room-temperature continuous wave laser oscillations in Nd:YAG ceramic waveguides produced by carbon ion implantation

We report on the generation of continuous wave lasers at a wavelength of ∼1064 nm in a Nd:YAG ceramic waveguide at room temperature. The waveguide was fabricated by using 6 MeV carbon ion implantation at a fluence of 3×10¹⁴ ions/cm². Laser operation has been realized with a slope efficiency as high as ∼11%. The pump threshold of an 808-nm laser beam for the waveguide laser oscillation is 19.5 mW.     

Concentration scheme for partially entangled photon states via entanglement reflector and no Bell-state analysis

We propose a protocol to concentrate partially entangled states of photons using entanglement reflector, which consists of a single electron spin confined in a charged quantum dot inside a single-sided microcavity. The outstanding advantage of the proposed scheme is its experimental simplicity and feasibility since it only needs to perform a single local measurement on electronic spins rather than a joint Bell-state measurement on photons. We then extend this scheme to concentrate N-photon Greenberger-Horne-Zeilinger state. Finally, we analyze the influence of various imperfections on the scheme.     

Upper bound on key generation rate of quantum key distribution with two-way or two-step quantum channels

We present an asymptotic security proof of deterministic quantum key distribution (DQKD) with a two-way quantum channel. The security proof of DQKD with a two-way quantum channel is different from that of BB84, because Eve can attack the travel qubits twice, both in line Bob to Alice and in line Alice to Bob. With the no-signaling principle and the property of mutual information, we obtain an upper bound of the final key generation of entanglement-based DQKD and hence single-photon four-state DQKD. Our results can be applied to the protocol of QKD with two-step quantum channels.     

Graphene-based passively Q-switched diode-side-pumped Nd:YAG solid laser

In this paper, a desirably simple, convenient and inexpensive saturable absorber mirror has been fabricated based on graphene, which has no wavelength selectivity. Moreover, there are no changes in the structure and characteristics of graphene. By inserting the graphene-PMMA SA mirror to the Nd: YAG laser, the shortest pulse width of 260 ns can be obtained with the single-pulse energy of about 8.32 μJ. The experimental results prove that our graphene-PMMA SA mirror is feasible and suitable for Q-switched lasers.     

合肥光源交错刀片型光位置检测器的研制

为了减小同步光尺寸对同步光位置检测器灵敏度的影响,合肥光源新研制了一种交错刀片型光位置检测器,并使用成熟的商业化产品Libera Photon进行后续的数据处理和输出。基于传统计算光位置信号的差比和方法,提出了比值和对数比两种新的计算方法,理论模拟了3种计算方法下交错刀片型光位置检测器的性能。在线标定结果与理论计算结果相符,并在机器研究光束线进行了初步的应用研究。     

雷暴电场对宇宙射线次级粒子μ 子的影响研究

西藏羊八井宇宙射线观测站的中子监测器主要探测宇宙射线次级粒子中能量在500 MeV—20 GeV的核子成分和少量的负μ子成分. 本文分析了2008—2010年观测站附近发生的62次雷暴期间中子监测器和大气平均电场仪的同步观测资料, 发现27次雷暴期间中子监测器计数率发生明显变化, 显著性S>5σ, 其中13次变化显著, 显著性S>10σ . 显著性S>10σ的13次个例信号变化百分比与地面电场场强幅值之间存在大体一致的变化趋势, 而显著性在5σ <S<10σ之间的14次个例信号变化百分比与地面电场场强幅值之间不存在相似的变化趋势. 较强雷暴当顶时中子监测器计数率变化一般不明显, 而中子监测器计数率变化明显的个例则多发生于雷暴云不当顶, 但探测器仍处于雷暴云下部正电荷层的控制范围之内时, 或者当顶雷暴处于形成或消散阶段. Dorman等把雷暴期间中子监测器计数率的变化归因于雷暴云内电场对宇宙射线次级粒子μ子的作用, 并建立了雷暴期间中子监测器计数率变化与雷暴地面电场相关联的理论. 本文分析发现雷暴期间羊八井中子监测器计数率变化与地面电场场强之间相关性较小或者没有相关性, 不支持Dorman的理论.