苯丙氨酸改性树枝状聚赖氨酸的合成及表征

以双芴甲氧羰基赖氨酸(Di- Fmoc -Lysine)为支化单元采用固相多肽合成技术制备了一种树枝状聚赖氨酸.该聚合物表面活性氨基通过与芴甲氧羰基苯丙氨酸(Fmoc- Phe)反应获得表面完全替代的苯丙氨酸改性树枝状聚赖氨酸.产物的分子量和结构经MS和NMR进行了表征.研究结果表明,利用该方法得到的产物分子量单一,是一种潜在的理想非病毒治疗载体.     

超薄Ag膜的椭偏光谱建模及解谱

用直流溅射法制备了6个不同厚度的超薄Ag膜。结合超薄Ag膜的结构特点,采用了Drude模型联合Lorentz Oscillator模型的解谱方法,得到1～6号样品的厚度分别为4.0,6.2,12.5,26.2,30.0和40.6 nm。从拟合结果的消光系数k图谱中发现,在1号到4号样品中分别于430,450,560和570 nm处出现了表面等离子体共振峰(SPR),随膜厚的增加共振峰宽化且峰位红移。最后,利用SPR理论计算出不同厚度Ag薄膜等离子体共振峰出现的位置,并和实验结果进行了比较。     

Surface wave photonic device based on porous silicon multilayers

Porous silicon is widely studied in the field of photonics due to its interesting optical properties. In this work, we present theoretical and first experimental studies of a new kind of porous silicon photonic device based on optical surface wave. A theoretical analysis of the device is presented using plane-wave approximation. The porous silicon multilayered structures are realized using electrochemical etching of p⁺-type silicon. Morphological and optical characterizations of the realized structures are reported.     

Characterization of electrodeposited nickel film surfaces using atomic force microscopy

Microstructures of nickel surfaces electrodeposited on indium tin oxides coated glasses are investigated using atomic force microscopy. The fractal dimension D and Hurst exponent H of the nickel surface images are determined from a frequency analysis method proposed by Aguilar et al. [J. Microsc. 172 (1993) 233] and from Hurst rescaled range analysis. The two methods are found to give the same value of the fractal dimension D∼2.0. The roughness exponent α and growth exponent β that characterize scaling behaviors of the surface growth in electrodeposition are calculated using the height-difference correlation function and interface width in Fourier space. The exponents of α∼1.0 and β∼0.8 show that the surface growth does not belong to the universality classes theoretically predicted by statistical growth models.     

Design,synthesis and evaluation of novel dehydroabietic acid-dithiocarbamate hybrids as potential multi-targeted compounds for tumor cytotoxicity

In the present study, novel representatives of the important group of biologically-active, dehydroabietic acid-bearing dithiocarbamate moiety, were synthesized and characterized by ¹H NMR, ¹³C NMR, HR-MS. The in vitro antiproliferative activity evaluation (MTT) indicated that these compounds exhibited potent inhibitory activities in various cancer cell lines (HepG-2, MCF-7, HeLa, T-24, MGC-803). Particularly, compound III-b possessed extraordinary cytotoxicity with low micromolar IC₅₀ values ranging from 4.07 to 38.84 µM against tested cancer cell lines, while displayed weak cytotoxicity on two normal cell lines (LO-2 and HEK 293 T). Subsequently, the potential mechanisms of representative compound III-b were elementarily investigated by Transwell experiment, which showed III-b can inhibit cancer cells migration. Annexin-V/PI dual staining showed that the compound can induce HepG-2 cells apoptosis in a dose-dependent manner. Meanwhile this apoptosis may be related to the upregulated protein expression of cleaved-caspase 3, cleaved-caspase 9, Bax and downregulated of Bcl-2 indicated by Western Blot. Later study further confirmed that ROS levels in HepG-2 cells increased significantly with the rise of concentrations. In addition, through the network pharmacology data analyzing, the core targets and signaling pathways of compound III-b for treatment of liver neoplasms were forecasted. Molecular docking model showed that compound III-b had high affinity with hub targets (CASP3, EGFR, HSP90AA1, MAPK1, ERBB2, MDM2), suggesting that compound III-b might target the hub protein to modulate signaling activity. Taken together, these data indicated that dehydroabietic acid structural modification following the “Molecular hybridization” principle is a feasible way to discover the potential multi-targeted antitumor compounds.     

ANISOTROPIC STRAIN EFFECT ON MORPHOLOGY AND ATOMIC STRUCTURE OF VICINAL Si(001) SURFACE

On vicinal Si(001) surfaces, dependence of growth morphology on the applied strain direction and formation of vacancy lines from Ag-induced missing dimer vacancies are studied. Both phenomena are intimately related to the anisotropic nature of the strain field which originates from the surface dimerization. Strain relief mechanism, reflecting on the surface morphology, is shown to be different in two orthogonal directions. Normal to the steps, step-pair bunching and waving lead to formation of hillocks and pits. Along the step direction, bending of step pairs forms a cusp which later develops into a deep groove. Toward the atomic scale, the formation of the vacancy lines is driven by the short-range attractive interaction between the vacancies in adjacent dimer rows and the long-range repulsive interaction between them in the same dimer row. A full form and magnitudes of the interactions are derived from the thermally-excited wandering of the vacancy lines formed by a nominal amount of Ag depositing onto the surface.     

Liquid surface and liquid/liquid interface energies of binary subregular alloys and wetting transitions

Energetics and chemistry of liquid surfaces and liquid/liquid interfaces of binary A-B alloys are calculated using a subregular solution model. In this model, two macroscopic energetic parameters are used to produce an asymmetric miscibility gap. They are related to two microscopic parameters which describe the interaction energy between two atoms as a function of the composition of the first coordination shell of each atom. The impact of the asymmetry of the A-B interactions on the surface and interfacial energies and adsorption are analyzed by comparing the results obtained with this subregular model to those calculated for a regular solution. The role of the asymmetry on the prewetting and wetting transitions are also discussed. Calculations performed in the Co-Cu system are in good agreement with experimental data of surface energy.     

Springer basic sets and modular Springer correspondence for classical types

We define the notion of basic set data for finite groups (building on the notion of basic set, but including an order on the irreducible characters as part of the structure), and we prove that the Springer correspondence provides basic set data for Weyl groups. Then we use this to determine explicitly the modular Springer correspondence for classical types (defined over a base field of odd characteristic $p$, and with coefficients in a field of odd characteristic $?\ne p$): the modular case is obtained as a restriction of the ordinary case to a basic set. In order to do so, we compare the order on bipartitions introduced by Dipper and James with the order induced by the Springer correspondence. We provide a quick proof, by sorting characters according to the dimension of the corresponding Springer fibre, an invariant which is directly computable from symbols.     

Microstructure performance and formation mechanism of laser alloying rare earth oxides modified nanocrystalline layer on TA7

Nanoscale particles (NP) were observed in a Ni60–Ag–Si₃N₄–Y₂O₃ laser alloying (LA) layer on a TA7 titanium alloy, NP usually locate on the grain boundaries, which are able to block the motion of dislocation in a certain extent. Such layer mainly consisted of γ-Ni, TiN, γ-(Fe, Ni), TiAg and lots of amorphous phases. The wear resistance of such layer with laser scanning speed 3 mm/s was better than that of a LA layer with 6 mm/s, which was mainly ascribed to an uniform microstructure and less defect of layer. The high laser scanning speed made the existing time of laser molten pool be shorter than before, favoring the formation of a fine microstructure. However, the defects, such as pores were produced in LA layer (higher scanning speed), decreasing the wear resistance.     

Calculation of Ship Sinkage and Trim Using a Finite Element Method and Unstructured Grids

An unstructured grid-based, parallel free-surface flow solver has been extended to account for sinkage and trim effects in the calculation of steady ship waves. The overall scheme of the solver combines a finite-element, equal-order, projection-type three-dimensional incompressible flow solver with a finite element, two-dimensional advection equation solver for the free surface equation. The sinkage and trim, wave profiles, and wave drag computed using the present approach are in good agreement with experimental measurements for two hull forms at a wide range of Froude numbers. Numerical predictions indicate significant differences between the wave drag for a ship fixed in at-rest position and free to sink and trim, in agreement with experimental observations.