Effects of La3+ on the active oxygen-scavenging enzyme activities in cucumber seedling leaves

The effects of La3+ on the antioxidant enzyme activities and the relative indices of cellular damage in cucumber seedling leaves were studied. When cucumber seedlings were treated with low concentrations of LaCl3 (0.002 and 0.02 mM), peroxidase (PO) activity increased, and catalase (CAT) activity was similar to that of control leaves at 0.002 mM La3+ and increased at 0.02 mM La3+, whereas superoxide dismutase (SOD) activity did not change significantly. The increase in the contents of chlorophyll (including chlorophylls a and b), carotenoids in parallel with the decrease in the level of malondialdehyde (MDA) suggested that low concentration of La3+ promoted plant growth. However, except the increase in SOD activity at 2 mM La3+, CAT and PO activities and the contents of pigments decreased at high concentrations of La3+ (0.2 and 2 mM), leading to the increase of MDA content and the inhibition of plant growth. It is suggested that lanthanum ion is involved in the regulation of active oxygen-scavenging enzyme activities during plant growth.

基于加速度反馈的柔性关节机械臂接触力控制

针对柔性关节机械臂从自由空间运动控制过渡到约束空间力控制的过程中,存在冲击、震荡甚至不稳定等问题,利用加速度传感器反馈控制,为柔性关节机械臂的接触力控制在较宽的带宽内提供阻尼,克服了利用单纯速度反馈控制带宽窄的局限。对柔性关节机械臂的接触力控制进行建模和基于加速度反馈的控制策略分析,并在柔性关节机械臂上进行了接触力控制的试验研究。结果表明,这种方法有效。

Pump-dump control and the related transient absorption spectroscopies

We combine theories of optimal pump-dump control and the related transient probe absorption spectroscopy in order to elucidate the relation between these two optical processes and the possibility of experimental realization. In the weak response regime, we identify the globally optimal pair of pump-dump control fields, and further propose a second-order difference detection scheme to monitor the wave packets dynamics that is jointly controlled by both the pump and dump fields. The globally optimal solution serves also as the initial input for the iterative search for the optimal control fields in the strong response regime. We use a model I-2 molecule to demonstrate numerically the pump-dump control and the detection of a highly vibrationally excited wave packet focusing dynamics on the ground X surface in both the weak and strong response regimes. The I2B surface serves as the intermediate to assist the pump-dump control and the optical detection processes. Demonstrated in the strong response regime are the optimal pair of pump-dump molecular-pi pulses that invert nearly total population onto the predefined target region within a half period of vibration motion. (C) 1999 American Institute of Physics. [S0021-9606(99)00115-4].

Screening and analysis of biologically active compounds in Angelica sinensis by molecular biochromatography

A novel strategy for the screening and analysis of biologically active compounds in traditional Chinese medicine by molecular biochromatography is proposed. Molecular biochromatography with human serum albumin (HSA) immobilized on silica as stationary phase was used to screen and analyse the bioactive compounds in the typical Chinese medicine of Angelica sinensis (Oliv.) Diels. Ten peaks showed retention on this column, which is based on their affinity for HSA. Ferulic acid and liguistilide were identified as the principal active components, which agrees very well with the results in the literature. A quality control method was also developed based on the simultaneous determination the concentrations of ferulic acid and liguistilide in solutions of Angelica sinensis (Oliv.) Diels extracted with water and methanol. It was observed that the concentrations of ferulic acid and liguistilide in solution extracted with methanol were 2 and 53 times higher, respectively, than those with water. It was shown that molecular biochromatography is an effective way of analysing and screening biologically active compounds in traditional Chinese medicine.