Separation of Linear and Branched Alkanes Using Host–Guest Complexation of Cyclic and Branched Alkane Vapors by Crystal State Pillar[6]arene

Activated crystals of pillar[6]arene produced by removing the solvent upon heating were able to take up branched and cyclic alkane vapors as a consequence of their gate‐opening behavior. The uptake of branched and cyclic alkane vapors by the activated crystals of pillar[6]arene induced a crystal transformation to form one‐dimensional channel structures. However, the activated crystals of pillar[6]arene hardly took up linear alkane vapors because the cavity size of pillar[6]arene is too large to form stable complexes with linear alkanes. This shape‐selective uptake behavior of pillar[6]arene was further utilized for improving the research octane number of an alkane mixture of isooctane and n‐heptane: interestingly, the research octane number was dramatically improved from a low research octane number (17 %) to a high research octane number (>99 %) using the activated crystals of pillar[6]arene.     

稀土掺杂PVC的紫外及微波交联研究

聚氯乙烯 (ＰＶＣ)是我国目前产量最大 ,应用面最广的高分子原材料。但其耐热性、稳定性及抗老化性都较差。我们考虑到使用稀土掺杂以改进其相关性能 ,同时掺入了少量从水玻璃中提取出来的活性硅醇到ＰＶＣ中以增加其柔性 ,探索了紫外辐射交联和微波辐射交联对ＰＶＣ机械力学性能的影响。本文采用ＰＶＣ流延膜来进行辐射交联并测定样品的力学性能。结果发现 ,稀土掺杂的结果使得样品的扯断伸长率大幅度提高 ,拉伸强度上升显著。而添加活性硅醇后ＰＶＣ流延膜的扯断伸长率进一步提高 ,拉伸强度则下降 ,柔性得以提高。将氯化钕溶于 95 %的乙醇…     

SSRL structural molecular biology summer school

Magnetic fields provide a contact-free and versatile experimental “knob” for tuning in different properties of matter [1 Herlack, F. and Miura, N. 2003. High Magnetic Field: Science and Technology Singapore: World Scientific..  [Google Scholar], 2 Manousakis, E., Schlottman, P., Kumar, P., Bedell, K. S. and Mueller, F. M., eds. 1992. Physical Phenomena at High Magnetic Fields Redwood, CA: Addison-Wesley..  [Google Scholar]]. There are numerous research laboratories and groups worldwide dedicated to studies of materials in magnetic fields. General themes of their research encompass such diverse topics and materials as competing order in superconductors, geometrically frustrated magnets, multi-ferroic oxides, quantum phase transitions, meta-magnetism, quantum Hall effects, orbital physics, spin-gap compounds, microstructures in melts, biological systems, magnetic aggregates, etc. Nearly all such studies of materials in extreme magnetic fields (>15 Tesla), however, have been focused on transport, thermodynamic, and some optical spectroscopic measurements. Detailed information on the atomic-scale nature of the magnetic field induced phases, on the other hand, has continued to remain unexplored, leading to a knowledge gap in our understanding of these systems. Synchrotron scattering studies can provide a mechanism for filling this gap, but their use has been hampered by the complexity involved in generating high fields with necessary optical access for such measurements.     

Maximum-cover source location problems with objective edge-connectivity three

Given a graph G = (V, E), a set of vertices covers a vertex if the edge-connectivity between S and v is at least a given number k. Vertices in S are called sources. The maximum-cover source location problem, which is a variation of the source location problem, is to find a source set S with a given size at most p, maximizing the sum of the weight of vertices covered by S. In this paper, we show a polynomial-time algorithm for this problem in the case of k = 3 for a given undirected graph with a vertex weight function and an edge capacity function. Moreover, we show that this problem is NP-hard even if vertex weights and edge capacities are both uniform for general k.     

Intramolecular arylcyanation of alkenes catalyzed by nickel/AlMe2Cl

A catalyst system derived from nickel and cocatalytic AlMe2Cl effects the intramolecular arylcyanation of alkenes. The reaction takes place in an exclusive exo-dig manner to give a wide range of nitriles having a benzylic quaternary carbon in good yields. Detailed investigations are described on the scope and mechanism as well as preliminary results on the asymmetric version of the reaction to provide novel access to chiral quaternary stereocenters.     

In-plane mechanical behaviors of 2D repetitive frameworks with four-coordinate flexible joints and elbowed beam members

The mechanical properties of an open-framework structure constructed of joints and beam members are strongly influenced by both its geometrical configuration and joint flexibility. This paper clarifies the relationship between joint flexibility and Poisson's ratio, which is a mechanical criterion for solid deformation, and discusses two types of in-plane anisotropic structures made up of four-coordinate flexible joints and elbowed beam members. Uniaxial tensile analyses estimate the linear and nonlinear elastic properties of these frameworks by applying straightforward joint modeling with multi-rotational degrees of freedom. The numerical results show that these proposed frameworks produce a variety of deformability dependent on the joint flexibility in auxetic deformation with a negative Poisson's ratio, the folding mechanics under kinematic indeterminacy, and the transition of Poisson's ratio between the positive and negative values. The geometrical and topological aspects of the obtained mechanical behaviors are discussed.