一类p-Laplace方程边值问题解的存在性

主要讨论一维p-Laplace方程在Neumann边值条件u(0)=0,u(1)=0下,对应的边值问题解的存在性.通过使用度理论,在适当的条件下,建立了对于p-Laplace方程在Neumann条件下解的存在性的充分条件.     

Two new benzaldehyde derivatives from mangrove endophytic fungus (No. ZZF 32)

Two new benzaldehyde derivatives, 6-ethyl-2-hydroxy-4-methoxy-3-methylbenzaldehyde (1), 6-ethyl-2,4-dihydroxy-3-methylbenzaldehyde (2), together with 2, 4-dihydroxy-3,6-dimethylbenzaldehyde (3) were isolated from mangrove fungus (No. ZZF 32#) from the South China Sea. The structures of compounds 1 and 2 were established by comprehensive analysis of the spectral data, especially 2D NMR spectral results.     

The self‐consistent charge density functional tight‐binding theory study of carbon adatoms using tuned Hubbard U parameters

The self‐consistent charge density functional tight‐binding (DFTB) theory is a useful tool for realizing the electronic structures of large molecular complex systems. In this study, the electronic structure of C₆₁ formed by fullerene C₆₀ with a carbon adatom is analyzed, using the fully localized limit and pseudo self‐interaction correction methods of DFTB to adjust the Hubbard U parameter (DFTB + U). The results show that both the methods used to adjust U can significantly reduce the molecular orbital energy of occupied states localized on the defect carbon atom and improve the gap between highest occupied molecular orbital(HOMO) and lowest unoccupied molecular orbital(LUMO) of C₆₁. This work will provide a methodological reference point for future DFTB calculations of the electronic structures of carbon materials.     

Double Michael addition of nitromethane to divinyl ketones: A remarkably positive effect of additive

An efficient double Michael addition of nitromethane to divinyl ketones was established in good to high yields (75–99%). A wide range of cyclohexanones were obtained with excellent diastereocontrol (up to >20:1 dr) and enantioinduction (91–99% ee) in a one-pot fashion. The involvement of basic additive significantly enhanced the reactivity of this cascade sequence.     

基于表面重建螺旋型铂铱电极的葡萄糖生物传感器

通过对螺旋型铂铱电极表面进行化学腐蚀和电化学沉积铂纳米粒子实现电极表面的重建和优化,研究了螺旋型铂铱电极在不同腐蚀时间和电沉积时间下的形貌及对过氧化氢(H2O2)的催化活性.对表面重建的工作电极涂覆氧化酶和半透膜,制备出了铂纳米粒子/葡萄糖氧化酶/环氧聚氨酯酶电极,并将其用作葡萄糖传感器的工作电极.传感器计时电流检测结果表明,表面重建后的酶电极传感器对葡萄糖的检测范围扩大为2~45 mmol/L,优于裸铂铱酶电极传感器,电流响应值和灵敏度得到明显提升,同时传感器还具有良好的稳定性和选择性.     

Study of Pt/TiO2 nanocomposite for cancer-cell treatment

The increasing incidence of cancer all over the world demands new, effective and secure materials for treatment. In this paper, we propose Pt/TiO₂ nanocomposite for cancer-cell treatment because noble metal nanoparticles are supposed to enhance the photocatalytic activity of TiO₂ nanoparticles. To evaluate the cancer-cell killing effect of our Pt/TiO₂ nanocomposite, TiO₂ and Au/TiO₂ nanoparticles are also introduced. The prepared Pt/TiO₂ nanocomposite are characterized with transmission electron microscopy (TEM) and UV–vis adsorption spectra. Results of cell treatment indicate that Pt/TiO₂ nanocomposite, as extremely stable metal–semiconductor nanomaterial, can exhibit a very high photodynamic efficiency under a mild ultraviolet radiation. And our Pt/TiO₂ nanocomposite shows to be more effective in cancer-cell treatment than TiO₂ and Au/TiO₂ nanoparticles. As a result, Pt/TiO₂ nanocomposite may be supposed to have a promising application for cancer-cell treatment.     

A facile approach toward multicomponent supramolecular structures: selective self-assembly via charge separation

A novel approach toward the construction of multicomponent two-dimensional (2-D) and three-dimensional (3-D) metallosupramolecules is reported. Simply by mixing carboxylate and pyridyl ligands with cis-Pt(PEt(3))(2)(OTf)(2) in a proper ratio, coordination-driven self-assembly occurs, allowing for the selective generation of discrete multicomponent structures via charge separation on the metal centers. Using this method, a variety of 2-D rectangles and 3-D prisms were prepared under mild conditions. Moreover, multicomponent self-assembly can also be achieved by supramolecule-to-supramolecule transformations. The products were characterized by (31)P and (1)H multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and pulsed-field-gradient spin echo NMR techniques together with computational simulations.     

A new griseofulvin derivative from the mangrove endophytic fungus <Emphasis Type="Italic">Sporothrix</Emphasis> SP.

A new griseofulvin derivative, 7-chloro-2',5,6-trimethoxy-6'-methylspiro(benzofuran-2(3H),1'-(2) cyclohexene)3,4'-dione (1), together with the known 2-acetyl-7-methoxybenzofuran (2), was isolated from the marine-derived mangrove endophytic fungus Sporothrix sp. (No. 4335). The structure of new compound 1 was elucidated by analysis of spectroscopic data.     

新的芳酰肼分子钳人工受体的微波干法合成及其识别性能研究

在微波辐射无溶剂条件下,以间苯二酚为起始原料,固体K2CO3为载体,设计合成了9个新的芳杂环酰肼分子钳人工受体.其结构均经1HNMR,IR,MS及元素分析确证.同传统的方法相比,该法具有简单、快速、高效和对环境友好等优点.利用紫外可见分光光度滴定法初步考察了这类分子钳对卤素阴离子的识别性能.结果表明,该类分子钳对I-具有良好的选择性识别性能.     

Free vibration of two elastically coupled rectangular plates with uniform elastic boundary restraints

An analytical method is derived for determining the vibrations of two plates which are generally supported along the boundary edges, and elastically coupled together at an arbitrary angle. The interactions of all four wave groups (bending waves, out-of-plane shearing waves, in-plane longitudinal waves, and in-plane shearing waves) have been taken into account at the junction via four types of coupling springs of arbitrary stiffnesses. Each of the transverse and in-plane displacement functions is expressed as the superposition of a two-dimensional (2-D) Fourier cosine series and several supplementary functions which are introduced to ensure and improve the convergence of the series representation by removing the discontinuities that the original displacement and its derivatives will potentially exhibit at the edges when they are periodically expanded onto the entire x-y plane as mathematically implied by a 2-D Fourier series. The unknown expansions coefficients are calculated using the Rayleigh-Ritz procedure which is actually equivalent to solving the governing equation and the boundary and coupling conditions directly when the assumed solutions are sufficiently smooth over the solution domains. Numerical examples are presented for several different coupling configurations. A good comparison is observed between the current results and the FEA models. Although this study is specifically focused on the coupling of two plates, the proposed method can be directly extended to structures consisting of any number of plates.