壳聚糖-树枝状大分子杂化物的研究进展

壳聚糖-树枝状大分子杂化物主要包括壳聚糖-(聚酰胺-胺)[CS-PAMAM]、壳聚糖-聚乙烯亚胺[CS-PEI]、壳聚糖-3,4,5-三(p-十二烷氧基苄氧基)苯甲酸[CS-DOBOB酸]、壳聚糖-3,4,5-三(p-十二烷氧基-m-甲氧基苄氧基)苯甲酸(DOVOB酸)、壳聚糖-聚丙三醇(PGLD)等树枝状大分子杂化物。壳聚糖-树枝状大分子杂化物具有良好的水溶性、生物可降解性、抗菌性、吸附性和热致液晶性等性能。壳聚糖-树枝状大分子杂化物的用途广泛,可作为金属离子的吸附剂、治疗高胆红素血症的吸附材料、新型荧光材料、抗菌剂和抗凝血剂等。本文综述了壳聚糖-树枝状大分子杂化物的研究进展,并展望了其未来研究方向和应用前景。     

Glycosylated star-shaped conjugated oligomers for targeted two-photon fluorescence imaging

A glucopyranose functionalized star-shaped oligomer, N-tris{4,4',4'-[(1E)-2-(2-{(E)-2-[4-(benzo[d]thiazol-2-yl)phenyl]vinyl}-9,9-bis(6-2-amido-2-deoxy-1-thio-β-D-glucopyranose-hexyl)-9H-fluoren-7-yl)vinyl]phenyl}phenylamine (TVFVBN-S-NH(2)), is synthesized for two-photon fluorescence imaging. In water, TVFVBN-S-NH(2) self-assembles into nanoparticles with an average diameter of ～49?nm and shows a fluorescence quantum yield of 0.21. Two-photon fluorescence measurements reveal that TVFVBN-S-NH(2) has a two-photon absorption cross-section of ～1100 GM at 780?nm in water. The active amine group on the glucopyranose moiety allows further functionalization of TVFVBN-S-NH(2) with folic acid to yield TVFVBN-S-NH(2) FA with similar optical and physical properties as those for TVFVBN-S-NH(2). Cellular imaging studies reveal that TVFVBN-S-NH(2) FA has increased uptake by MCF-7 cells relative to that for TVFVBN-S-NH(2), due to specific interactions between folic acid and folate receptors on the MCF-7 cell membrane. This study demonstrates the effectiveness of glycosylation as a molecular engineering strategy to yield water-soluble materials with a large two-photon absorption (TPA) cross-section for targeted cancer-cell imaging.     

Two Complexes from One Reaction of Nickel(II) Ion with a New Schiff Base Ligand

Abstract  

A new Schiff base ligand of 1-(2, 6-dichlorobenzylidene)-4-phenylthiosemicarbazide(C₁₄H₁₁Cl₂N₃S) has been synthesized, which crystallizes in monoclinic, space group C2/c with a = 18.551(7) ?, b = 6.963(3) ?, c = 23.185(9) ? and β = 93.122(6)o. The reaction of this ligand with NiAc₂·4H₂O gives two different Ni(II) complexes, one is general traditional mononuclear and another is unexpected trinuclear, where another quadridentate ligand of 1-(amino-N-phenylmethanethio)-4-phenyl-thiosemicarbazide(C₁₄H₁₄N₄S₂) is found. The mononuclear complex (C₃₂H₂₆Cl₄N₈NiS₂) crystallizes in triclinic, space group P−1 with a = 11.071(2) ?, b = 11.157(2) ?, c = 15.302(3) ?, α = 76.214(2)o, β = 87.902(2)o and γ = 79.586(3)o. The trinuclear complex (C₆₀H₅₀Cl₄N₁₆Ni₃S₆) crystallizes in orthorhombic, space group Pbcn with a = 19.673(3) ?, b = 16.094(3) ? and c = 20.465(4) ?. In above three compounds, there are some hydrogen bonds which help to construct the three dimensional net works and stabilize the molecular structures.     

High Flattened Comb Filter with Precise Channel Spacing Based on Linearly Chirped Fiber Bragg Grating and Phase Compensation

Abstract

A novel approach to implement high flattened comb filters with precise channel spacing based on DC phase compensation is proposed. Channel wavelength error and peak reflectivity variation are discussed and calculated. A phase compensation method by simply changing the DC refractive index is proposed. Fiber Bragg gratings with different DC phase shifts are fabricated, which indicates that an arbitrary DC phase shift can be introduced precisely. A high flattened comb filter with precise 50-GHz channel spacing is realized with the help of a micrometer-precision translation stage. Then the peak reflectivity variation with and without phase compensation for different chirp coefficients is researched.     

Study of n-γ discrimination for 0.4-1 MeV neutrons using the zero-crossing method with a BC501A liquid scintillation detector

An experimental system aimed at n-γ discrimination using the zero-crossing method with a φ3’’×2’’ BC501A liquid scintillation detector was established and tested with an Am-Be neutron source. Two-dimensional plots of energy versus zero-crossing time were obtained. The quality of n-γ discrimination was checked by the figure-of-merit (FOM), the neutron peak-to-valley ratio, and the proportion of leaked neutrons over all neutron events. The performance of n-γ discrimination in terms of FOM was compared with previous work done by other groups. The n-γ discrimination in four different energy regions with an interval of 0.1 MeV between 0.3 MeV and 0.7 MeV was studied, and the results indicate that the n-γ discrimination threshold can go down to 0.4 MeV.     

Two-dimensional residual charge density distribution measurement of surface leader

The charge density distribution of the surface leader has never been measured before. Because the surface leader usually covers a long distance, and the surface potential caused by leader discharge is usually very high, this creates difficulties in measuring the potential distribution of the surface leader. In this paper, with a feedback type electrostatic probe based on a field-nullify technique, a charge density distribution scanning system is developed. A two-layer structure pipe is designed to lower the surface potential after discharge. In this way, the surface potential distribution caused by the residual charge of the leader discharge under the application voltage as high as to 40 kV can be measured. The surface charge density distribution including the leader and streamer is perfectly measured, which is in good agreement with the photograph.     

Robustness analysis of static routing on networks

Robustness is one of the crucial properties that needs to be considered in the design of routing strategies on networks. We study the robustness of three typical routing strategies, which are the SP (shortest path), EP (efficient path), and OP (optimal path) strategies, by simulating several different kinds of attacks including random attacks, target attacks and cascading failures on scale-free networks. Results of the average path length, betweenness centrality, network capacity, etc., demonstrate that the EP strategy is more robust than the other two, and the OP strategy is more reliable than the SP strategy in general. However, on the power-grid network, the OP strategy is more resistant against cascading failures than the EP and SP strategies.     

Extremely large bandwidth and ultralow-dispersion slow light in photonic crystal waveguides with magnetically controllability

A line-defect waveguide within a two-dimensional magnetic-fluid-based photonic crystal with 45^o-rotated square lattice is presented to have excellent slow light properties. The bandwidth centered at $ \lambda_{0} $  = 1,550 nm of our designed W1 waveguide is around 66 nm, which is very large than that of the conventional W1 waveguide as well as the corresponding optimized structures based on photonic crystal with triangular lattice. The obtained group velocity dispersion $ \beta_{2} $ within the bandwidth is ultralow and varies from ?1,191 $ a/(2\pi c^{2} ) $ to 855 $ a/(2\pi c^{2} ) $ (a and c are the period of the lattice and the light speed in vacuum, respectively). Simultaneously, the normalized delay-bandwidth product is relatively large and almost invariant with magnetic field strength. It is indicated that using magnetic fluid as one of the constitutive materials of the photonic crystal structures can enable the magnetically fine tunability of the slow light in online mode. The concept and results of this work may give a guideline for studying and realizing tunable slow light based on the external-stimulus-responsive materials.     

新型针孔点背光发光模型与实验研究

纳秒级强激光(～1014 W/cm2)与固体靶相互作用可以获得高亮度的Multi-keV能段X射线.在当前的高能量密度物理研究中利用这样的X射线背光源照相方式可以获得高质量的物理图像,具有重要的应用价值.以模拟计算与神光Ⅱ激光装置实验结果相结合的方式研究了激光等离子体发光模型.在该模型的基础上改进了针孔点背光成像技术,独立发展了针对低Z靶材料K线的准单能背向针孔点背光和针对中Z靶材料L带的高亮度侧向针孔点背光.在神光Ⅱ激光装置上通过新型针孔点背光对惯性约束聚变靶丸样品成像获得了高质量的静态靶丸流线图像,空间分辨优于10μm.实验结果表明新型的针孔点背光具备高亮度,高空间分辨,高图像衬度等优点可以广泛应用于高能量密度物理和惯性约束聚变的研究中.     

高功率、低量子亏损同带抽运掺镱光纤放大器

开展了基于同带抽运的高功率、低量子亏损的掺镱光纤放大器实验研究. 搭建了一台输出功率为21 W的1018 nm短波 长掺镱光纤激光器, 并利用其对双包层掺镱光纤进行同带抽运, 获得18.6 W的1080 nm波段激光输出, 光-光转换效率高达90.86%. 关键词： 光纤放大器 同带抽运 双包层光纤 转换效率