The ability of burdock fructooligosaccharide (BFO), a type of linear fructooligosaccharide extracted and isolated from the roots of Arctium lappa, to induce systemic acquired resistance (SAR) was studied in cucumber seedlings. BFO strongly induced changes in salicylic acid (SA) and SA-glucoside (SAG) in BFO-treated leaves, and similar changes of SA and SAG were also found in untreated leaves of the same seedling. The level of SA in the first leaves sprayed with BFO (5.0 g ⁄ l) increased by 3.6 times after 24 h and then gradually declined from 48 to 96 h and finally decreased to a nadir at 120 h. The SAG level increased by 2.1 times at 24 h and then continued to increase to about 10.0 times as much as that in control from 96 to 120 h. The levels of SA in the untreated leaves of the same seedling only increased by 1.6-1.9 times during the period of 24-72 h followed by a decrease at 120 h, while SAG increased by 1.1 times at 24 h but steadily continued to increase to its maximum from 24 to 120 h. In summary, the patterns of expression of SA and SAG in the untreated leaf were similar to that of the treated leaf of the same seedling, while the pattern of expression of SAG was quite different from that of SA both in the treated and untreated leaves. Pretreatment with BFO reduced the lesions caused by Colletotrichum orbiculare by 56.8%. Additionally, the amount of lignin and the activities of some defensive enzymes including peroxidase, superoxide dismutase, polyphenoloxidase and b-1,3-glucanase significantly increased in the first leaves pretreated with BFO and followed with C. orbiculare inoculation. These results demonstrate that BFO can enhance the contents of endogenous SA, the resistance against C. orbiculare, and the activities of defensive enzymes of cucumber seedlings.

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This article presents an improved integral variable structure control scheme to avoid overshooting responses for a class of second-order plants. The proposed sliding dynamics have two integral state variables. One integral state variable is initially specified to enable existence of a sliding mode throughout an entire response. The other's initial value is assigned to avoid overshooting output responses. It is shown that the integral state is initially chosen to be a nonlinear function of the plant's initial state to avoid an overshooting response. This article also reports the experimental results for controlling the position of a screw-driven actuator with various payloads and initial velocities, in order to show the effectiveness of the proposed scheme.

This article presents a proportional–integral–derivative controller design for monotonic, non-overshooting output responses of a class of second-order plants that do not need to be initially at rest. The proposed scheme is applicable to twice-differentiable reference commands, and monotonic, non-overshooting responses are achieved by compensating for the initial value of integral state. That is, the integral state is initially set to a certain value so that the subsequent response has no overshoot. In the proposed scheme, the initial value that should be assigned to the integral feedback is found to be a nonlinear function of the plant’s initial state. This result differs from those in previous schemes that constrain the controller’s initial state to be a linear function of the plant’s initial state. The proposed scheme is practically applied to layer-jump control and single-track jump control of an optical disk drive. Experimental results confirm the effectiveness of the proposed scheme and its applicability to mode-switching control systems.