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ABSTRACISince 14malonylamino)cyclopropane-l-carboxylic acid (MACC), the major conjugate of 1-aminocyclopropane-l-carboxylic acid (ACC) in plant tissues, is a poor ethylene producer, it is generally thought that MACC is a biologically inactive end product of ACC. In the present study we ACC2 is the immediate precursor of ethylene, which is synthesized via the following sequence in higher plants: Methionine -* SAM --+ ACC --ethylene (1, 24). In addition to serving as a precursor for ethylene, ACC can also be widely metabolized to the stable conjugate, MACC (3,6,7,11,13,16,19,22,23). This conversion is thought to participate in the regulation of ethylene biosynthesis by removing excess ACC (24). Since MACC is a poor ethylene precursor and the conjugation of ACC to MACC is essentially irreversible, MACC is generally thought to be a biologically inactive end product of ACC rather than a storage pool for ACC and hence for ethylene (3,7,8,25). MACC was found to accumulate when high rates of ACC synthesis were induced by water deficit (8) or other factors (3,6,20,23). However, a decrease in MACC content was reported so far only in two systems: in the second node of pea plants (6) (15). Seedling leaves from various ages were used. In one experiment leaf discs from lettuce (Lactuca sativa L.) and soybean (Glycine max L.), root segments of radish (Raphanus sativus L.) and carrot (Daucus carota L.) and fruit plugs of banana (Musa acuminata Colla) and chinese gooseberry (Actinidia chinensis) were used. All fruits and vegetables were purchased from local market.

This paper demonstrates an energy management method using traffic information for commuter hybrid electric vehicles. A control strategy based on stochastic dynamic programming (SDP) is developed, which minimizes on average the equivalent fuel consumption, while satisfying the battery charge-sustaining constraints and the overall vehicle power demand for drivability. First, according to the sample information of the traffic speed profiles, the regular route is divided into several segments and the statistic characteristics in the different segments are constructed from gathered data on the averaged vehicle speeds. And then, the energy management problem is formulated as a stochastic nonlinear and constrained optimal control problem and a modified policy iteration algorithm is utilized to generate a time-invariant state-dependent power split strategy. Finally, simulation results over some driving cycles are presented to demonstrate the effectiveness of the proposed energy management strategy.

ABSTRACITWhile light-grown wheat leaves produced ethylene at a low rate of <0.1 nanomoles per gram per hour and contained 1-aminocyclopropane-1-carboxylic acid (ACC) at low levels of <2.5 nanomoles per gram, etiolated wheat leaves produced ethylene at a rate of 2 nanomoles per gram per hour and accumulated concentrations of ACC at levels of 40 nanomoles per gram. Upon illumination of 8-day-old etiolated wheat seedlings with white light, the ethylene production rate increased initially, due to the activation of ethylene-forming activity, but subsequently declined to a low level (0.1 nanomoles per gram per hour) at the end of the 6-hour illumination. This light-induced decline in ethylene production rate resulted from a decline (more than 35 nanomoles per gram) in ACC level, which was accompanied by a corresponding increase in 1-malonylamino)cyclopropane-l-carboxylic acid content. These data indicate that illumination promoted ACC malonylation, resulting in reduced ACC level and consequently reduced ethylene production. However, light did not cause any significant increase in the extractable ACC-malonyltransferase activity. A number of reports have shown that light regulated ethylene production which in turn modified plant growth (4,5,9,18,19 m-2 s-'), red light or far-red light. The red and far-red light sources were from a projector equipped with a 650 nm and 730 nm filter, respectively. For the red light treatment, tubes were exposed to red light with intensity of 12 ,uE m-2 s-' for 5 min; for far-red treatment, tubes were exposed to far-red light with intensity of0.85 uE m-2 s-' for 10 min. Tubes were returned to darkness for the subsequent measurements.Determination of Ethylene Production. Leaf segments in tube were flushed with air and sealed with a rubber serum cap after each sampling. At indicated time intervals, 1 ml gas samples were drawn from the tubes and injected into a gas chromatograph equipped with an alumina column and a FID detector at 90°C.Determination of ACC and MACC. Samples were extracted twice with 5 ml of 80% ethanol at 55°C for 10 min. The ethanol extract was evaporated under vacuum at the same temperature. The residue was dissolved in 2 ml water and the pigment was removed by the addition of 0.5 ml chloroform. ACC content in 0.2 ml aliquots of the aqueous solutions was determined according to the method of Lizada and Yang (14). The quantitation of MACC in the extract was carried out first by passing 0.2 ml extract through a Dowex 50 (H+-form) resin column with 0.5 ml bed volume to removed ACC. The effluent solution containing MACC was hydrolyzed in 2 N HCl for 3 h as described previously (13). Following neuralization with NaOH, the resulting hydrolysate was assayed for ACC content, which was taken as the amount of MACC in the extract.

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To maintain the stoichiometric air-fuel ratio (AFR), this paper presents a model-based adaptive AFR control scheme for port-injected spark ignition engines. The utilized mean-value model in control design accounts for the impingement and the evaporation process of the injected fuel on the walls and calculates on the uncertainties in the dynamics of the intake manifold and crankshaft rotation. A fueling controller with adaptive update laws is derived for estimating the uncertain parameters related to inaccuracies in air flow and fuel delivery into the cylinders and engine torque production, which is implemented by utilizing engine speed, manifold pressure and temperature, air mass flow rate at the throttle, and the universal exhaust gas oxygen (UEGO) sensor information, without knowledge of the fuel flow mass. Theoretical analysis shows that the proposed strategy is able to regulate the AFR against the parameter uncertainties. Moreover, both simulation and experiment on an engine test bench demonstrate the capability of the adaptive controller to recover the performance and robustness properties of the control system in the presence of various operating conditions and uncertainties including air path and fuel path perturbations and load torque disturbance as well.

1-Aminocyclopropane-l-carboxylic acid (ACC) is aerobically oxidized in plant tissues to form ethylene by ethylene-forming enzyme (EFE). The effect of substrate (ACC and oxygen) concentrations on ethylene production rate by plant tissues was investigated. The Km value for 02 in ethylene production varied greatly depending on the internal ACC content. When ACC levels in the tissue were low (below its Km value), the concentration of 02 giving half-maximal ethylene production rate ([Sj.s) ranged between 5 and 7%, and was similar among different tissues. As the concentration of ACC was increased (greater than its Km value), 151.5 for 02 decreased markedly. In contrast, the Km value for ACC was not much dependent on 02 concentration, but varied greatly among different plant tissues, ranging from 8 micromolar in apple (Malus sylvestris Mill.) tissue to 120 micromolar in etiolated wheat (Triticum aestivum) leaf. Such a great variation was thought to be due to the different compartmentation of ACC within the cells in different tissues. These kinetic data are consistent with the view that EFE follows an ordered binding mechanism in which EFE binds first to 02 and then to ACC.to 16% for oxygen (1)(2)(3)8), and from 61 to 500 ,uM for ACC (5,8,11,14), where the ACC concentration refers to the internal concentration of ACC within the tissues or external ACC concentration for the protoplast or vacuole preparations. Although many reports documented the relationship between ethylene production rates and external ACC concentrations in various plant tissues, these values were not considered, because external ACC concentrations do not reflect internal concentrations. Since EFE is a bi-substrate enzyme, the [S] Plant Materials. Apples (Malus sylvestris Mill., var Golden Delicious) were harvested from a local orchard and were stored at 1°C. Apple plugs (1 cm in diameter and 2 cm in length) were prepared with a cork borer and a knife. After floating with shaking in 2% KCI solution for 10 min, plugs were blotted dry and were used in the experiments at room temperature (20°C); they exhibited steady ethylene production rates for at least 3 h.Mungbean (Vigna radiata L.) hypocotyl segments (1 and 3 cm under hook) were prepared from 3-d-old etiolated seedlings grown in paper towel at 25°C in darkness, and used as experimental material.Wheat (Triticum aestivum) seeds were germinated and seedlings grown in vermiculite at 25°C either in light (14 h light/10 h dark cycle) or in darkness for 9 d. Experimental materials consisted of 8-cm long segments cut from the tip of the leaves.Isolation of Protoplast from Barley Leaves. Barley (Hordeum vulgare) seeds were germinated and grown in vermiculite at 25°C in light. After 4 to 5 d, top leaves (3-4 cm) were harvested. The abaxial epidermis of the leaves was peeled off with fine forceps, and the leaves were then floated in a Petri dish with the peeled sides down in 20 mL enzyme solution containing 2% cellulysin (Calbiochem), 1% pectolyase (Seishin Pharmaceutical, Japan), 1% macerase (Calbi...

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