Temperature oscillations in a compartmentalized bidisperse granular gas

A granular clock is observed in a vertically vibrated compartmentalized granular gas composed of two types of grains with the same size. The dynamics of the clock is studied in terms of an unstable evaporation or condensation model for the granular gas. In this model, the temperatures of the two types of grains are considered to be different, and they are functions of the composition of the gas. Oscillations in the system are driven by the asymmetric collisions properties between the two types of grains. Both our experiments and model show that the transition of the system from a homogeneous state to an oscillatory state is via a Hopf bifurcation.     

The design of agarose beds for high-performance hydrophobic-interaction chromatography and ion-exchange chromatography which show increasing resolution with increasing flow rate

Agarose beads (agarose concentration: 15%; diameter: 15–70 μm) were shrunk, crosslinked and derivatized in organic solvents. As crosslinker and coupling agent γ-glycidoxypropyl tri-methoxysilane was used. Columns packed with nonporous beads of pentyl agarose and octyl agarose, prepared by this technique, were used for hydrophobic-interaction chromatography. Characteristic of these columns was that the resolution increased with an increase in flow rate (except for very low flow rates). This very attractive behavior, which violates the generally accepted theory of chromatography, was also exhibited by an ion-exchanger based on non-porous agarose beads.     

Influence of granule velocity on gravity-driven granular flow

In this Letter, we present the results of our study on the influence of granule velocity on the granular flow state. The maximum outflow rate of the dilute flow state increases with an increase in granule velocity, whereas the outflow rate of the dense flow state remains unchanged. In addition, increasing granule velocity can extend the region of the dilute flow state and shrink that of the dense flow state. These observations can be explained by the relationship between the flow rate and the packing fraction at the bottleneck under a fixed particle number condition.     

A fixed point index theory for nowhere normal-outward compact maps and applications

A fixed point index theory is developed for a class of nowhere normal-outward compact maps defined on a cone which do not necessarily take values in the cone. This class depends on the retractions on the cone and contains self-maps for any retractions, and weakly inward maps and generalized inward maps when the retraction is a continuous metric projection. The new index coincides with the previous fixed point index theories for compact self-maps and generalized inward compact maps. New fixed point theorems are obtained for nowhere normal-outward compact maps and applied to treat some abstract boundary value problems and Sturm-Liouville boundary value problems with nonlinearities changing signs.     

用EXAFS研究NiO/α-Al2O3催化剂的结构和相含量

采用EXAFS方法研究了工业上使用的NiO/α-Al_2O_3催化剂反应前后的结构和相组成。催化剂反应后部分NiO还原成Ni, 在反应塔不同高度还原的量不同。用分析混合相的EXAFS方法测定了NiO和Ni的含量, 并给出了Ni原子在两相中的近邻结构参数。结果表明, 还原出的Ni原子平均配位数较少, 是Ni原子以较多比例处于表面而引起, 估计了这些集合体的尺寸。而NiO中的Ni原子近邻参数反应前后没有明显变化。     

The local atomic structures in Si1−x Ge x random solid solutions

The local structures of Si_1?x Ge _x solid solutions can be described with FDUC model (the five distorted unit cells) based on a phenomenological valence force field approach. Bond lengths and strain energies in these solid solutions can be predicted. The distorted feature of the local structure is well described by the five distorted unit cells. Calculated results are compared with those obtained from EXAFS, indicating the excellent agreement between theoretical predictions and EXAFS measurements with the largest divergence not larger than 0.01 Å. In addition, The relationship betweenSi _1?x Ge _x and III–V random solid solutions is also discussed.