多功能胶囊催化剂在多相催化中的应用研究进展（英文）

分子筛胶囊催化剂被广泛应用于串联催化反应中，与多步反应相比，串联反应具有更高的化学反应效率，能节约反应时间和原料，并实现反应物到目的产物的一步转化．然而，目前普遍采用的物理混合型催化剂，很难高选择性的生成目的产物．分子筛膜包裹的核-壳型胶囊催化剂由于其特殊的结构形式，在许多串联反应中可以一步高选择性的生成目的产物．如：合成气选择性制异构烷烃，合成气直接制二甲醚，合成气直接制液化石油气等重要多相催化反应．本文综述了分子筛胶囊催化剂的制备方法与应用范围，重点阐述了胶囊催化剂设计，制备及应用方面的最新应用进展，并展望了其研究和发展方向．

Membership determination of open cluster NGC 188 based on the DBSCAN clustering algorithm

High-precision proper motions and radial velocities of 1046 stars are used to determine member stars using three-dimensional （3D） kinematics for open clus- ter NGC 188 based on the density-based spatial clustering of applications with noise （DBSCAN） clustering algorithm. By implementing this algorithm, 472 member stars in the cluster are obtained with 3D kinematics. The color-magnitude diagram （CMD） of the 472 member stars using 3D kinematics shows a well-defined main sequence and a red giant branch, which indicate that the DBSCAN clustering algorithm is very effective for membership determination. The DBSCAN clustering algorithm can ef- fectively select probable member stars in 3D kinematic space without any assumption about the distribution of the cluster or field stars. Analysis results show that the CMD of member stars is significantly clearer than the one based on 2D kinematics, which al- lows us to better constrain the cluster members and estimate their physical parameters. Using the 472 member stars, the average absolute proper motion and radial velocity are determined to be （PMα, PMδ） = （-2.58 ± 0.22, ＋0.17 ± 0.18） mas yr-1 and Vr = -42.35 ± 0.05 km s-1, respectively. Our values are in good agreement with values derived by other authors.

An application of the KNND method for detecting nearby open clusters based on Gaia-DR1

This paper presents a preliminary test of the k-th nearest neighbor distance （KNND） method for detecting nearby open clusters based on Gaia-DR1. We select 38 386 nearby stars （〈 100 pc） from the Gaia-DR1 catalog, and then use the KNND method to detect overdense regions in three-dimensional space. We find two overdense regions （the Hyades and Coma Berenices （Coma Ber） open clusters）, and obtain 57 reliable cluster members. Based on these cluster members, the distances to the Hyades and Coma Ber clusters are determined to be 46.0±0.2 and 83.5±0.3 pc, respectively. Our results demonstrate that the KNND method can be used to detect open clusters based on a large volume of astrometry data.

Kinematic and chemical properties of five open clusters based on SDSS DR7

We present metallicities and radial velocities for five old open clusters （NGC 6791, NGC 2420, NGC 2682, NGC 2158, and NGC 7789） using data from the seventh public data release of the Sloan Digital Sky Survey （SDSS）, which includes the directed stellar program SEGUE： Sloan Extension For Galactic Understanding and Exploration. The radial velocities are used to calculate cluster membership probabilities for stars in each cluster region. NGC 6791, NGC 2420, NGC 2682, NGC 2158 and NGC 7789 are found to have mean metallicities [Fe/H]= ＋0.08 ± 0.09, -0.38± 0.11, -0.08±0.05, -0.41 ±0.13 and -0.19 ± 0.13 dex （s.d.）, respectively. The mean radial velocities for NGC 6791, NGC 2420, NGC 2682, NGC 2158 and NGC 7789 are Vr = -45.9 ± 0.2, ＋76.1 ± 0.2, ＋35.0 ± 0.2, ＋26.9 ± 0.2 and -48.2± 0.2 km s^-1（s.e.m.）, respectively. We have compared our results with the values from literatures, and found that our metallicity of NGC 6791 is significantly underestimated （by about 0.3 dex） and our radial velocities of the open clusters agree well with the values derived using high-resolution spectroscopy.

An application of the k-th nearest neighbor method to open cluster membership determination

We introduce a non-parametric method for open cluster membership determination in threedimensional（3D） velocity space（proper motion and radial velocity）. Clean 3D cluster members can be obtained by statistically analyzing the Euclidean distance between each star and its k-th nearest neighbor in3 D velocity space. We use 513 sample stars in the direction of open cluster M67 to construct a 3D velocity space and test our method; 291 3D cluster members are obtained. The color-magnitude diagram, proper motions, radial velocities and spatial distribution of these 3D cluster members demonstrate the effectiveness of our method. From the 291 3D cluster members, the mean radial velocity and absolute proper motion of M67 are Vr = ＋33.46 ± 0.05 km s-1and（PMRA, PMDEC） =（-7.64 ± 0.07,-5.98 ± 0.07） mas yr-1,respectively. In addition, we use 640 sample stars with precise proper motions and radial velocities in the direction of open cluster NGC 188 to test our method. The test results also show that our method is effective.

3D cluster members and near-infrared distance of open cluster NGC 6819

In order to obtain clean members of the open cluster NGC 6819, the proper motions and radial velocities of 1691 stars are used to construct a three-dimensional （3D） velocity space. Based on the DBSCAN clustering algorithm, 537 3D cluster members are obtained. From the 537 3D cluster members, the average radial velocity and absolute proper motion of the cluster are Vr = ＋2.30 ±0.04 km s-1 and （PMRA, PMDec） = （-2.5 ±0.5, -4.3 ± 0.5） mas yr-1, respectively. The proper motions, radial velocities, spatial positions and color-magnitude diagram of the 537 3D members indicate that our membership determination is effective. Among the 537 3D cluster members, 15 red clump giants can be easily identified by eye and are used as reliable standard candles for the distance estimate of the cluster. The distance modulus of the cluster is determined to be （m - M）0 -- 11.86 ± 0.05 mag （2355 ±54 pc）, which is quite consistent with published values. The uncertainty of our distance mod- ulus is dominated by the intrinsic dispersion in the luminosities of red clump giants （--0.04 mag）.

Discovery of high-velocity EHB stars in the globular cluster ωCentauri(NGC 5139)

Abstract We report the discovery of 45 high-velocity extreme horizontal branch （EHB） stars in the globular cluster Omega Centauri （NGC 5139）. The tangential ve- locities of these EHB stars are determined to be in the range 93-313 km s^-1, with an average uncertainty of -27 km s^-1. The central escape velocity of the cluster is determined to be in the range 60~105 km s^-1. These EHB stars are significantly more concentrated toward the cluster core compared with other cluster members. The formation mechanisms of these EHB stars are discussed. Our conclusions can be sum- marized as follows： （1） A comparison of the tangential velocities of these EHB stars to the central escape velocity of the cluster shows that most if not all of these EHB stars are unbound to the cluster; （2） These EHB stars obtained high velocities in the central cluster region no longer than - 1 Myr ago and may be subsequently ejected from the cluster in the next -1 Myr; （3） If the progenitors of these EHB stars were single stars, then they may have experienced a fast mass-loss process. If the progen- itors were in close binaries, then they may have formed through disruptions by the intermediate-mass black hole in the cluster center.

Suadimins D—J,Monoterpenoid Indole-Quinoline and Bisindole Alkaloids from Melodinus suaveolens

Comprehensive Summary,Compounds 1—12,including seven complex monoterpenoid indole-quinoline and bisindole alkaloids,suadimins D—J(1—7)with previously unreported carbon-carbon linkages,were isolated and identified from the twigs and leaves of Melodinus suaveolens.Their structures were elucidated by a combination of diverse methods,especially the extensive spectroscopic data analysis and electric circular dichroism(ECD)calculations.The cytotoxicity of these compounds against three cancer cell lines was evaluated,some of which showed moderate activities with IC50 values ranging from 2.4 to 8.0μM.

Attractive natural products with strained cyclopropane and/or cyclobutane ring systems

The strained cyclopropane and/or cyclobutane subunits occurred in many complex natural products including terpenoids, steroids and alkaloids. Natural products with cyclopropane and/or cyclobutane motifs not only furnished fascinating structures, but also exhibited versatile biological activities, such as cytotoxic, anti-HIV, antimicrobial, antiviral, and immunosuppressive effects. This review covered a large array of structurally unique natural products with strained cyclopropane and/or cyclobutane motifs and summarized their structural features, distributions, biological activities, as well as biogenetic considerations.

Rearranged Dichapetalin-Type Triterpenoids with Cytotoxic Activity from Dichapetalum gelonioides

Dichagelinoids A—C(1—3),three unusual dichapetalin-type triterpenoids,together with two biogenetically related derivatives dichagelinoids D and E(4 and 5)were isolated and characterized by solid data from Dichapetalum gelonioides.Compounds 1—3 possess a common rearranged C ring and different C6—C2 modified motifs at the A rings.Biological evaluation revealed that compounds 1—3 showed distinct cytotoxic activity against the tested human cancer cell lines.