雷尼镍催化剂的吸附量热研究

雷尼镍催化剂的吸附量热研究王益沈俭一（南京大学化学系，南京２１００９３）ＨａｎｓＷａｒｌｉｍｏｎｔ（ＩｎｓｔｉｔｕｔｅｆｏｒＳｏｌｉｄＳｔａｔｅａｎｄＭａｔｅｒｉａｌｓＲｅｓｅａｒｃｈ，ＤｒｅｓｄｅｎＤ０１０６９，Ｇｅｒｍａｎｙ）关键词雷尼镍...     

Effect of cooling rate in [(Fe0.5Co0.5)0.75B0.2Si0.05]100-xNbx alloy system on magnetic properties

The effect of cooling rate on the thermal stability and soft magnetic properties of [(Fe_0.5Co_0.5)_0.75B_0.2Si_0.05]_100-xNb_x (x = 5, 6, 7, 8 at. %) system was investigated. The alloys were produced into the form of ribbon and cylindrical rod by melt-spinning and injection casting, respectively. Their structure, thermal, mechanical and soft magnetic properties were investigated by x-ray diffraction, differential scanning calorimetry, universal testing machine and vibrating sample magnetometer, respectively. All of the alloys were identified as fully amorphous by X-ray diffraction. It turned out that the rod samples had exceptionally high saturation fields reaching 3.0 kOe, which is key properties for sensor application. Also, among these Fe,Co-based samples, the Fe_35.25 Co_35.25 B_18.8 Si_4.70 Nb₆ ribbon exhibits the highest saturation magnetization with 142.1 emu/g.     

Ribbon tile invariants

Let be a finite set of tiles, and a set of regions tileable by . We introduce a tile counting group as a group of all linear relations for the number of times each tile can occur in a tiling of a region . We compute the tile counting group for a large set of ribbon tiles, also known as rim hooks, in a context of representation theory of the symmetric group.

The tile counting group is presented by its set of generators, which consists of certain new tile invariants. In a special case these invariants generalize the Conway-Lagarias invariant for tromino tilings and a height invariant which is related to computation of characters of the symmetric group.

The heart of the proof is the known bijection between rim hook tableaux and certain standard skew Young tableaux. We also discuss signed tilings by the ribbon tiles and apply our results to the tileability problem.

     

Undulator linear accelerator as a generator of ribbon high power ion beams

The characteristics of an undulator linear accelerator, based on the use of a plane electrostatic undulator (UNDULAC-E), is presented in this paper. It is shown that UNDULAC-E can be used as a high intensity ribbon ion beam source. The results of modeling of dynamics and construction are presented.     

Stress-MI and domain studies in Co-based nanocrystalline ribbons

A systematic investigation of the influence of different types of annealing on the magnetoimpedance (MI) effect in melt-spun (Co_1−xFe_x)₈₉Zr₇B₄ [x=0, 0.025, 0.05] and (Co_0.88Fe_0.12)_78.4Nb_2.6Si₉B₉Al ribbons has been carried out in the frequency range 500 kHz-13 MHz and under dc magnetic fields (H_dc) up to 80 Oe. In the stress annealed ribbons, the strain-induced transverse anisotropy is seen to result in large MI. Magnetic domains were investigated in the ribbons through magnetic force microscopy.     

Dependence of polarization mode dispersion of slotted core NZDF ribbon on cable design and environmental conditions

Non-zero dispersion fiber (NZDF) ribbon cable has recently become a considerable alternative in long-haul high-speed network construction. Since long-distance high-bit rate transmission requires low polarization mode dispersion (PMD), it is very important to know the PMD performance of this type of optical fiber cables. In this paper, we report experimental analysis of effects of the cable design and environmental parameters, in particular ribbon thickness, positions of fibers in the ribbon, flexing and vibration, on PMD performances of several slotted-core fiber ribbon cables. Results show that ribbon thickness and positions of fibers in the ribbon alter the PMD values of NZDF ribbon cables. Also, 23% and 11% PMD variations have been determined in flexing and vibration experiments, respectively. Moreover, it has been observed that vibration amplitude has significant effects and vibration frequency has little effects (14% and 6% variations, respectively) on fiber PMD. Results are important for understanding effects of installation conditions and wind, especially for aerial fibers, on PMD values of cables.     

The response of turbulent flow to the disturbance of a vibrating ribbon

By use of the LDV, experimental investigation was carried out for a turbulent boundary layer which was disturbed with an electric-magnetic vibrating ribbon. It is found that, in the flow, the response of the disturbance contains harmonic components besides the fundamental frequency of the ribbon vibration. The fundamental and harmonic disturbances can also enhance the energy of other frequency components around them. In the experiments, the regular disturbane was introduced in the outer region of the boundary layer. Under the given flow conditions, they can significantly influence the downstream coherent structures in the wall region by suppressing the bursts and increasing their period. The effect on the burst period depends on the disturbing frequency. The project supported by the National Natural Science Foundation of China     

Magnetic force microscopy characterization of heat and current treated Fe40Ni38Mo4B18 amorphous ribbons

The domain structure of a magnetostrictive Fe₄₀Ni₃₈Mo₄B₁₈ amorphous ribbon has been studied using magnetic force microscopy (MFM) at room temperature. First, the evolution of the magnetic domain patterns as a function of the annealing temperature has been investigated. In samples heat treated at 250 and 450 °C for 1 h, a transformation from 90° to 180° domain wall has been clearly observed, while the sample heat treated at 700 °C for 1 h showed a magnetic phase fixed by the crystalline anisotropy. Additionally, the evolution of the magnetic domain structure by applying a DC current was recorded by the MFM technique. For current annealed samples at 1 A for 1, 30 and 60 min, a transformation between different domain patterns has been observed. Finally, in samples treated by the current annealing method under simultaneous stress, an increase of the annealing time gives rise to a different magnetic structure arising from the development of transverse magnetic anisotropy.     

Optical shuttering action in nematic phase of SMHBLC: observation of a ribbon-like texture

In this study, complexes belonging to supramolecular hydrogen-bonded liquid crystal homologous series are synthesized and characterized. Hydrogen bond is formed between p-n-alkyloxy benzoic acids (nBAO, where n?=?5–11) and chlorobenzoic acid (ClBAO), respectively. The isolated homologues are characterized by various techniques such as polarizing optical microscopic (POM) studies, differential scanning calorimetry (DSC), and Fourier transform–infrared spectroscopy. Based on the POM and DSC studies, the phase diagram has been constructed and discussed. A new smectic ordering, labeled as smectic R, has been characterized, which exhibits a ribbon-like texture. This phase is observed in the complexes pertaining to the higher homologous series. Tilt angle in this phase has been experimentally deduced and the results are fitted to the power law which concurs with the mean-field theory predicted value. Optical shuttering action in the homologue has been detected in the nematic phase and the results are also discussed.