A sensitive electrochemical biosensor for detection of DNA methyltransferase activity by combining DNA methylation-sensitive cleavage and terminal transferase-mediated extension

A novel electrochemical biosensor was developed for activity assay of DNA methyltransferase and its inhibitor based on methylation-sensitive cleavage, which activated a primer for terminal transferase-mediated extension of biotinylated dUTP followed by sensitive detection via enzymatic amplification.     

用一维光子带隙结构增强硫化镉双光子吸收研究

用真空镀膜方法制备了含有单个CdS缺陷层的具有不同周期和结构参量的TiO2／SiO2一维光子晶体。用抽运一探测技术研究了CdS缺陷层的双光子吸收（TPA）现象。实验结果表明：一维光子晶体中CdS缺陷层的双光子吸收显著增强。不同周期和结构参量的一维光子晶体中CdS缺陷层的双光子吸收系数不同。双光子吸收的增强来源于由光局域化导致的缺陷层的电场强度的增加。缺陷层电场强度与一维光子晶体的结构有关,如周期,光子带隙的位置与宽度及缺陷模式等因素都会影响缺陷层电场强度。采用四分之一波长的高低折射率介质层和与入射波长匹配的缺陷模可以得到最大的缺陷层电场强度。     

聚丙烯孔洞铁电驻极体膜的电极化及其电荷动态特性

根据栅控恒压电晕充电组合反极性电晕补偿充电法的实验结果计算出铁电驻极体的极化强度.结果说明，伴随着薄膜内孔洞气体的Paschen击穿，该铁电体的极化强度随栅压增加而显著上升.利用上述充电方法和热刺激放电(TSD)谱的分析讨论了这类空间电荷型宏观电偶极子，及与其补偿的空间电荷热退极化的电荷动态特性；阐明了这两类俘获电荷的能阱分布，即构成宏观电偶极子的位于孔洞上下介质层内的等值异号空间电荷分别被俘获在深、浅两种能值陷阱内，而位于薄膜表面层的注入空间电荷则被俘获在中等能值陷阱中. 关键词： 反极性电晕补偿充电法 铁电驻极体 充电电流 热刺激放电     

High-efficiency continuous-wave and Q-switched operation of a resonantly pumped Ho:YAP ring laser

We demonstrated continuous-wave (CW) and Q-switched operation of a room-temperature Ho:YAP ring laser that is resonantly end-pumped by a diode-pumped Tm:YLF laser at 1.91 ??m. Continuous wave output power of 3 W at 2119 nm is obtained under the absorbed pump power of 10.17 W, corresponding to a slope efficiency of 60%. For the Q-switched regime the maximum pulse energy of 1.58 mJ and the minimum pulse width of 590 ns at the repetition rate of 1 kHz are achieved.     

Construction of the refractive index profiles for few-mode planar optical waveguides

We present a nondestructive technique to predict the refractive index profiles of isotropic planar waveguides, on which a thin gold film is deposited to as the cladding. The negative dielectric constant of the metal results in significant differences of effective indices between TE and TM modes. The two polarized modes and a surface plasmon resonance (SPR) with abundant information of the surface index can be used to construct the refractive index profiles of single-mode and two-mode waveguides at a fixed wavelength.     

Acyclic cucurbit[n]uril molecular containers selectively solubilize single-walled carbon nanotubes in water

Making single-walled carbon nanotubes (SWNTs) soluble in water is a challenging first step to use their remarkable electronic and optical properties in a variety of applications. We report that acyclic cucurbit[n]uril molecular containers 1 and 2 selectively solubilize small-diameter and low chiral angle SWNTs. The selectivity is tunable by increasing the concentration of the molecular containers or by adjusting the ionic strength of the solution. Even at a concentration 1000 times lower than typically required for surfactants, the molecular containers render SWNTs soluble in water. Molecular mechanics simulations suggest that these C-shaped acyclic molecules complex the SWNTs such that a large portion of nanotube sidewalls are exposed to the external environment. These "naked" nanotubes fluoresce upon patching the exposed surface with sodium dodecylbenzene sulfonate.     

环糊精衍生物在金属催化有机合成中的应用

综述了环糊精(包括α-环糊精,β-环糊精和γ-环糊精)衍生物在金属催化有机合成中的应用,主要包括其作为金属离子配体、金属纳米粒子稳定剂和反相相转移催化剂在氧化、水解、还原、偶联等金属催化反应中的应用.其中环糊精衍生物作为金属离子配体应用最广,由于环糊精部分与底物形成包结络合物,拉近了底物和具有催化活性的金属离子的距离,并固定了底物的反应部位,往往可以显著提高催化反应的反应速率,增强反应的区域选择性和对映选择性.     

Bulk polymerization of N-vinylcarbazole initiated by C60

In this communication, we first used [60]fullerene as initiator to initiate the bulk polymerization of N-vinylcarbazole (NVC) monomer at 70°C (slightly higher than the melting point temperature, 65°C, of NVC). A reasonable polymerization reaction pathway via C₆₀-NVC ion-radical pairs is suggested. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3745–3747, 1999     

Reaction of N-phenyl maleimide with aminosilane monolayers

Reaction of N-phenyl maleimide (NPM) with silica surfaces modified with a self-assembled monolayer of (aminopropyl)triethoxysilane (APTES) was investigated using infrared spectroscopy (FTIR), elemental analysis, and titration assays. This reaction is of interest as a test case for using amine-maleimide coupling for immobilization of biomolecules. Addition of NPM to surface APTES residues was consistently sub-stoichiometric, with typical yields of about 75% on monolayers with a coverage of 1.15 APTES residues/nm2. Titration analysis found negligible presence of imide alkene C=C bonds in modified supports, indicating that addition of NPM to APTES proceeded via amine attack at the imide olefinic bond. FTIR measurements also revealed presence of amide bands which intensified over periods of 10 h. These observations were attributed to a slower secondary process in which APTES amines attack imide carbonyls to produce amide linkages. Stability of NPM-modified surfaces was examined under room temperature storage in pH 7 buffer up to 72 h and for 2 h exposure to buffer at temperatures up to 90 degrees C. It was found that stability was determined by robustness of APTES-silica attachment, with about 30% loss under the harshest conditions investigated.