Bound lipids in lacustrine sediments in Guchenghu Lake, East China

Conclusion Lipids present in different modes of occurrence in lacustrine sediments vary obviously in their composition. The ester-bound and amide-bound lipids are more likely to be derived from autochthonous input such as bacteria, algae and fungi in the lake, and they were more stable than the free lipids in the process of early diagenesis. Bound lipids record the more actual information about the paleoclimatic and paleoenvironmental changes. Amide-bound P-hydroxy fatty acids can be used as a fingerprint of the past bacterial communities which is informative to the paleoenvironment.     

大直径磁性液体密封新结构的优化设计

磁性液体密封应用于大轴径的工况下时，环形永磁体作为磁性液体密封的磁源结构，存在因直径过大导致充磁不均匀进而引发的密封耐压能力降低的问题。为解决这一问题，设计了一种轴上永磁体的磁性液体密封结构，该结构的环形永磁体设计在轴上，与传统的磁性液体密封相比减小了环形永磁体的直径，同时减小了结构总体的轴向尺寸，使其具有结构紧凑的特点。通过有限元仿真对环形永磁体的几何参数进行优化，同时对比了新结构在极靴上开极齿和在环形永磁体上开极齿两种方式耐压能力的区别。通过模拟分析得到所设计密封结构磁通密度在极齿上的分布以及大小，并计算出理论耐压能力，证明了所设计密封结构的合理性。     

带有拟周期系数的二阶线性波方程平衡点的稳定性

利用KAM迭代法,首先证明了波方程(1)是可约的,然后利用稳定性理论中的有关定理得出系统(1)的平衡点是稳定的.     

具有交易成本的证券投资组合选择：一种求解方法

本研究一类带交易成本证券投资组合选择的求解，在风险不超过某个阈值的假设下，我们给出一种求解方法，最后本通过实例计算表明该方法是有效的。     

N^＋注入改性的25Cr3MoA材料在轴向柱塞泵配流盘上的应用研究

叙述了经全方位Ｎ＾＋注入（Ｎ＾＋ＰＳ１１）表面改性后的２５Ｃｒ３ＭｏＡ材料在轴向液压柱塞泵（ＹＺＢ）的配流盘中的应用试验研究。结果表明Ｎ＾＋ＳＰ１１材料可较大幅度提高配流盘乃至ＹＺＢ的股役使用寿命。     

电解质溶液Hall效应的等效测量原理和实现方法

本文从电解质溶液Ｈａｌｌ效应的基本关系式出发，分析了电解质溶液Ｈａｌｌ效应的测量问题。     

Banach空间中渐近非扩张映象具误差的强收敛定理

设E是一实的Banach空间,其范数是一致Gteaux可微的;D是E的一非空闭凸子集,设T:D→D是具有序列{k_n}[1,∞),lim_(n→∞) k_n=1的渐近非扩张映象.本文证明了,在一定条件下,由(1.3)和(1.5)式定义的具误差的迭代序列{x_n}强收敛于T的不动点.本文结果也推广和改进了最近一些人的最新结果.     

Mechanism of N-octadecyl-N′-maleoyl-L-phenylalanine self-assembled into supramolecular structures

N-Octadecyl-N′-maleoyl-L-phenylalanine(ODMA-L-Phe)was synthesized through the condensation,deprotection and acid- ylation reaction of BOC-L-phenylalauine,octadecylamine and maleic anhydride,ODMA-L-Phe can self-assemble in some organic solvents and turned them into thermally reversible physical supramolecular organogels.The morphology of ODMA-L-Phe aggregates was characterized by polarized optical microscopy(POM)and field emission scanning electron microscope(FE-SEM). The aggregates of ODMA-L-Phe were needle-like fibrils with diameters of approximately 100-200 nm.The mechanism of ODMA- L-Phe serf-assembly in organic solvents was investigated using ~1H NMR and circular dichroism(CD).The results indicated that hydrogen bonding was one of the main driving forces for the self-assembly of ODMA-L-Phe.     

A novel amperometric sensor for the determination of nitric oxide, and its application in rat liver cells

A novel amperometric nitric oxide sensor with a wide linear range, low detection limit and fast response time was developed. The sensor was fabricated using a poly-brilliant cresyl blue (PBCB)/Nafion film modified glassy carbon electrode (GCE). The PBCB on the working GCE surface dramatically improves the oxidation response of nitric oxide and lowers the required potential for the two-step oxidation of NO. Otherwise, Nafion coated onto the film electrode surface does not only improve the selectivity of the sensor, but also further lowers the active energy of the direct three-electron oxidation of NO to nitrate. The effect of the preanodic time and the film thickness of the electropolymerization on the nitric oxide response as well as the volume of Nafion coated onto the surface and the potential for amperometric detection were optimized. This novel sensor has been applied to the determination of NO released from rat liver cells, and the result is satisfactory. Correspondence: Sheng Shui Hu, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China     

Kinetics of dispersion polymerization: Effect of medium composition

The effect of the medium composition (monomer and solvent) on the kinetics of dispersion polymerization of methyl methacrylate (MMA) was studied via reaction calorimetry. It was found that increasing the monomer concentration increased the reaction rate; the exponent of the dependency of the initial reaction rate on the MMA concentration was found to be 0.93. Narrow particle size distributions were achieved at the lower monomer concentrations (0.24–0.81 mol/L) and a minimum size (2.45 μm) was found at an intermediate concentration (0.44 mol/L). The average molecular weight of the PMMA increased and the molecular weight distribution broadened with increasing monomer concentration. During a dispersion polymerization, the MMA concentration was found to decrease linearly with conversion in both phases, whereas the ratio of concentrations in the particles and continuous phase ([M]_p/[M]_c) remained constant (0.47) with partitioning favoring the continuous phase. The average number of free radicals per particle in MMA dispersion polymerization was estimated to be high from the nucleation stage onward (>5000). The increasing rate during the first ～ 40% conversion was primarily caused by the increasing volume of the polymer particle phase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3638–3647, 2008