[5]Rotaxane and [5]Pseudorotaxane Based on Cucurbit[6]uril and Anchored to a Meso-tetraphenyl Porphyrin

Water soluble [5]rotaxane and [5]pseudorotaxane based on cucurbit[6]uril and anchored to a meso-tetraphenyl porphyrin have been synthesized and characterized by spectroscopic methods (¹H-NMR, ¹³C-NMR and UV), and by elemental analysis, and mass spectrometry. The preliminary results of the pH-driven switching properties of [5]rotaxane investigated through ¹H-NMR spectroscopy are reported. These results were compared with those obtained from a model porphyrin, which was prepared by the de-threading cucurbit[6]uril from [5]pseudorotaxane under basic conditions.Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Compactifications whose remainders are zero dimensional and retract

LetX be a locally compact non compact space. Necessary and sufficient conditions forfX/X to be a retract offX are given wherefX is the Freudenthal compactification ofX. LetX be a locally compact and zero dimensional space,m be any cardinal number andJ be a set with cardinalitym. It is proved thatX has a dyadic family of powerm if and only if there exist and compactificationY ofX such thatY/X=2 ^J andY/X is a retract ofY.     

Reconsidering extra time-like dimensions

In this study we reconsider the phenomenological problems related to tachyonic modes in the context of extra time-like dimensions. First we reconsider a lower bound on the size of extra time-like dimensions and improve on the conclusion in the literature. Next we discuss the issues of spontaneous decay of stable fermions through tachyonic decays and disappearance of fermions due to tachyonic contributions to their self-energies. We find that the tachyonic modes due to extra time-like dimensions are less problematic than the tachyonic modes in the usual 4-dimensional setting because the most troublesome Feynman diagrams are forbidden once the conservation of momentum in the extra time-like dimensions is imposed.     

Magnetic Texturing of Xenon-Irradiated Iron Films Studied by Magnetic Orientation Mössbauer Spectroscopy

Modifications of magnetic properties upon heavy-ion irradiation have been recently investigated for films of ferromagnetic 3d-elements (Fe, Ni, Co) and alloys (permendur, permalloy), in relation to changes of their microstructure. Here we report on Xe-ion irradiation of a highly textured iron film prepared via pulsed-laser deposition on a MgO(100) single crystal and containing a thin ⁵⁷Fe marker layer for magnetic orientation Mössbauer spectroscopy (MOMS). We compare the results with those obtained for a polycrystalline Fe/Si(100) sample produced by electron evaporation and premagnetized before Xe-irradiation in a 300 Oe external field. Characterization of the samples also included magneto-optical Kerr effect (MOKE), Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD).     

Synthesis and characterization of novel phosphoramidates containing benzimidazole moiety

Novel heterocyclic phosphoramidates were synthesized by a nucleophilic substitution reaction of 2-substitutedbenzimidazoles and diphenyl chlorophosphate (ClPO₃Ph₂) in the presence of potassium hydroxide (KOH) under an argon atmosphere. The structures of the phosphoramidates were characterized by NMR, IR, melting point, and elemental analysis.     

基于低体分SiC/Al主镜框的空间相机主支撑结构热特性分析与验证

基于微小卫星平台对高分辨相机的重量约束,以高分微纳卫星CX6-02数字超分辨相机研制为例,提出一种基于低体分SiC/Al主镜框的空间相机主支撑的结构形式,并开展主镜框一体拓扑优化设计分析和试验验证。Zernike多项式计算及光机热集成仿真结果验证了低体分SiC/Al主镜框作为空间相机主支撑结构的有效性。热光试验数据及在轨成像结果表明,兼具主支撑功能的低体分SiC/Al主镜框的空间相机试验数据与仿真数据基本吻合,且性能稳定,可为未来采用低体分SiC/Al主镜框作为主支撑的航天相机轻量化设计和研制提供理论与技术参考。     

Paracrystalline Nature of Poly (p-Phenylene)

The electron diffraction pattern of oriented, annealed poly (p-phenylene) is explained on the basis of an orthorhombic unit cell: a = 0.7781, b = 0.5520 and c(fiber axis) = 0.4300 nm. and exhibits the following features:

(1)The reflections on the equator and meridian are sharp. Only a few weak diagonal reflections can be observed.

(2) Strong diffuse scattering is seen on the third layer line.

(3)The reflections on the meridian (00l-reflections) have a characteristic line profile. in which the intensity increases suddenly at the Bragg angle and decreases gradually.

From (1) to (3), it can be concluded that the material is paracrystalline like a nematic structure in liquid crystals. Molecular chains are laterally packed in a rather regular way. However, the disorder by the shift of chains in the direction parallel to their axes is remarkable.