桑色素及其配合物与DNA作用的比较

采用光度法、粘度法和电化学方法考察了桑色素及其配合物和DNA的作用.并对桑色素合铜(Ⅱ)、桑色素合锌(Ⅱ)、桑色素合钴(Ⅱ)、桑色素与DNA作用的方式进行了比较.Cu(Ⅱ), Zn(Ⅱ), Co(Ⅱ)桑色素配合物与DNA作用时的荧光光谱性质类似,不同于配体.钴(Ⅱ)配合物的电化学行为与铜(Ⅱ)配合物相似,不同于锌(Ⅱ)配合物.三种配合物的存在,都可引起DNA的粘度增加.但钴(Ⅱ)配合物对EB-DNA复合物的荧光光谱影响很小,而铜(Ⅱ)、锌(Ⅱ)配合物对EB-DNA复合物的荧光光谱影响较大.实验结果表明,与DNA之间的作用,钴(Ⅱ)配合物弱于铜(Ⅱ)、锌(Ⅱ)配合物.这可能是钴(Ⅱ)配合物的抗肿瘤活性低于与DNA嵌入结合的铜(Ⅱ)、锌(Ⅱ)配合物的原因之一.     

A new blowup criterion of strong solutions to the two-dimensional equations of compressible nematic liquid crystal flows

In this paper, we concern the Cauchy problem of two-dimensional (2D) compressible nematic liquid crystal flows with vacuum as far-field density. Under a geometric condition for the initial orientation field, we establish a blowup criterion in terms of the integrability of the density for strong solutions to the compressible nematic liquid crystal flows. This criterion generalizes previous results of compressible nematic liquid crystal flows with vacuum, which concludes the initial boundary problem and Cauchy problem.     

InN量子点的液滴外延及物性表征

由于1. 55μm波段广泛应用于通信领域,为了探索不同生长温度对InN量子点的形貌影响,并且实现自组装InN量子点在1. 55μm通信波段的发光,对InN量子点的液滴外延及物性进行了相关研究。首先利用射频等离子体辅助分子束外延(PA-MBE)技术在GaN模板上,采用液滴外延方法在3种温度下生长了InN量子点结构。生长过程中靠反射高能电子衍射(RHEED)对样品进行原位监控。原子力显微镜(AFM)表征结果表明随着生长温度升高,量子点尺寸变大,密度减小。在生长温度350℃和400℃下,观测到了量子点;当温度高于450℃时,未观测到InN量子点。当生长温度为400℃时,量子点形貌最好,密度为6×10~8/cm~2,对400℃下生长的InN量子点进行了变温PL测试,成功得到InN量子点在1. 55μm波段附近的光致发光,并且随着测试温度的升高,量子点的发光峰位发生了先红移后蓝移最后又红移的S型曲线变化,这种量子点有望在未来应用于量子通信领域。     

基于苝二酰亚胺类非富勒烯受体共混体系凝聚态结构调控

非富勒烯太阳能电池具有给受体能级可调、吸收范围宽及可溶液加工等优势,已经成为太阳能电池领域发展趋势。在高性能材料开发及器件结构优化的推动下,能量转换效率已经突破11%。其中,苝二酰亚胺(PDI)类分子价格低廉且具有良好的稳定性及较高的电子迁移率,已经发展成为重要的非富勒烯受体材料。然而,PDI类材料刚性稠环结构使得分子间具有强烈的π-π相互作用(受体-受体分子间及给体-受体分子间),导致共混体系相分离尺寸可控性差,给受体分子间共混程度难于调控,从而发生严重的成对以及非成对电荷复合。本文从分子间作用力入手(溶剂-溶质、给体-受体分子间作用力)详述了非富勒烯共混体系相分离结构、相区尺寸及共混相含量调节的相关原理及方法。研究表明基于PDI共混体系,固-液相分离及分子扩散能力是决定相分离结构的本质因素,通过调控给受体比例及热退火温度实现了孤岛及互穿网络结构的构筑。同时,通过平衡受体分子间π-π作用及给受体间电荷转移,实现了低相容性及高相容性共混体系相区尺寸的可控调节。在此基础上,利用添加剂手段通过调节溶剂与溶质分子间的溶度参数差值,实现了薄膜内共混相的可控调节,并针对具有不同相容性共混体系给出了添加剂的选择原则。     

改性海藻酸钠聚集行为对电纺纳米纤维形貌的影响

以过硫酸钾(KPS)为引发剂, 采用双丙酮丙烯酰胺(DAA)对海藻酸钠(SA)进行改性, 制备了海藻酸钠-聚双丙酮丙烯酰胺两亲性共聚物(SA-PDAA). 将SA-PDAA与聚乙烯醇(PVA)复配, 并进行静电纺丝, 制得SA-PDAA/PVA电纺纳米纤维. 通过红外光谱、 差示扫描量热和荧光光谱表征了SA-PDAA的结构和性能, 通过黏度仪、 表面张力仪和电导率仪测试了SA-PDAA纺丝液的物理性能, 用扫描电子显微镜表征了SA-PDAA/PVA电纺纳米纤维的形貌, 考察了SA-PDAA/PVA电纺纳米纤维的释药性能. 结果表明, DAA接枝到SA分子链上, SA-PDAA的临界聚集浓度为0.072 g/L, SA-PDAA具有良好的两亲性, SA-PDAA/PVA电纺纳米纤维具有均一的形貌. 改性后的SA可以有效地减缓药物释放速度, 提高SA-PDAA/PVA电纺纳米纤维的缓释性能.     

Effect of phase interactions on crystal stress evolution over crystal orientation space under elastoplastic deformation of two-phase polycrystalline solids

It has been known for decades that crystal stress directions move toward the vertices of the single crystal yield surface (SCYS) during plastic flow of polycrystalline solids to satisfy the deformation compatibility among crystals. The alignment of crystal stress with a SCYS vertex is affected not only by plastic anisotropy, but also by other factors such as elastic anisotropy, loading direction, and grain interactions. Among the factors contributing to the degree of alignment, the effect of phase interactions on the crystal stress evolution during plastic flow has not been extensively investigated. In this research, the effect of phase interactions on the crystal stress direction evolution is investigated using simulations of an elastoplastically deforming two-phase (Cu/Fe) polycrystalline solid calibrated to a neutron diffraction experiment. By mapping the simulated crystal stresses over the crystal orientation space, crystal-orientation-dependent nonuniform partitioning of the crystal stress between phases can be observed. An analysis of the distribution of angles between the SCYS vertex and the crystal stress based on the simulation of the two-phase material shows that the crystal stress evolution pattern during plastic flow is strongly affected by phase interactions. These interactions result in low alignment and greater dispersion angles between the crystal stresses and SCYS vertices, particularly in the strong phase.     

缓冲层生长温度对In0.82Ga0.18As 薄膜结构及电学性能的影响

采用低压金属有机化学气相沉积(LP-MOCVD)技术,两步生长法在InP衬底上制备In_0.82Ga_0.18As材料。研究缓冲层的生长温度对In_0.82Ga_0.18As薄膜的结构及电学性能的影响。固定外延薄膜的生长条件,仅改变缓冲层生长温度(分别为410,430,450,470 ℃),且维持缓冲层其他生长条件不变。用拉曼散射研究样品的结构性能,测量四个样品的拉曼散射光谱,得到样品的GaAs的纵向光学(LO)声子散射峰的非对称比分别为1.53,1.52,1.39和1.76。测量样品的霍耳效应表明,载流子浓度随缓冲层生长温度变化而改变,同时迁移率也随缓冲层生长温度变化而改变。通过实验得出:缓冲层的生长温度能够影响In_0.82Ga_0.18As薄膜的结构及电学性能。最佳的缓冲层生长温度为450 ℃。     

Microwave-assisted synthesis of flower-like and leaf-like CuO nanostructures via room-temperature ionic liquids

Flower-like and leaf-like cupric oxide (CuO) single-crystal nanostructures have been successfully synthesized using ionic liquid 1-octyl-3-methylimidazolium trifluoroacetate ([Omim]TA) under the microwave-assisted approach. By controlling the concentration of [Omim]TA and reaction temperature, shape transformation of CuO nanostructures could be achieved in a short period of time. The results indicate that ionic liquid [Omim]TA plays an important role in the formation of different morphologies of CuO crystals. The crystal structure and morphology of products were characterized by X-ray powder diffraction (XRD), infrared spectrum (IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), and selected-area electron diffraction (SAED). A possible mechanism for CuO nanostructure was proposed. In addition, UV-vis spectroscopy was employed to estimate the band gap energies of CuO crystals.     

Crystal Structure of β-Cyclodextrin-Felbinac Inclusion Complex

The crystal structure of the inclusion complex of β‐cyclodextrin (β‐CD) synthesized with felbinac (4‐biphenylacetic acid) was determined by single crystal X‐ray diffraction at 150 K. The complex contains two β‐CDs, two felbinac molecules, twenty‐two water molecules in the asymmetric unit, and could be formulated as (C₄₂H₇₀O₃₅)₂·(C₁₄H₁₂O₂)₂·22(H₂O). In the crystal lattice, the two β‐CD moieties form a head‐to‐head dimer jointed through hydrogen bonds, and the felbinacs that interact by face‐to‐face Π‐Π stacking are included in the β‐CD dimer cavity with their carboxyl groups protruding out from cavity opening. In crystals the dimer units of β‐CD are stacked in an intermediate type (IM) that consists of closely packed β‐CD dimer layers.     

Molecular modeling and spectroscopic studies on binding of 2,6-bis[4-(4-amino-2-trifluoromethylphenoxy)benzoyl] pyridine to human serum albumin

BAFP (2,6-bis[4-(4-amino-2-trifluoromethylphenoxy)benzoyl] pyridine), a synthesized polyimide compound, was exploited for the first time to analyze its interaction with human serum albumin (HSA) by molecular modeling, fluorescence and Fourier transform infrared attenuated total reflection spectroscopy (FTIR ATR) with drug concentrations of 3.3 × 10⁻⁶ to 3.0 × 10⁻⁵ mol L⁻¹. Molecular docking was performed to reveal the possible binding mode. The results suggested that BAFP can strongly bind to human serum albumin (HSA) and the primary binding site of BAFP is located in site II of HSA, which is supported by the results from the competitive experiment. The binding constants for the interaction of BAFP with HSA have been evaluated from relevant fluorescence data at different temperatures (296, 303, 310 and 308 K). The alterations of the protein secondary structure in the presence of BAFP in aqueous solution were quantitatively calculated by the evidences from FTIR ATR spectroscopes. The binding process was exothermic and spontaneous, as indicated by the thermodynamic analyses, and the major part of the binding energy is hydrophobic interaction, which is also in good agreement with the results of molecule modeling study. The enthalpy change ΔH⁰, the free energy change ΔG⁰ and the entropy change ΔS⁰ of 296 K were calculated to be −7.75, −27.68 kJ mol⁻¹ and 67.33 J mol⁻¹ K⁻¹, respectively.