Model-free adaptive fractional order control of stable linear time-varying systems.

This paper presents a new model-free adaptive fractional order control approach for linear time-varying systems. An online algorithm is proposed to determine some frequency characteristics using a selective filtering and to design a fractional PID controller based on the numerical optimization of the frequency-domain criterion. When the system parameters are time-varying, the controller is updated to keep the same desired performances. The main advantage of the proposed approach is that the controller design depends only on the measured input and output signals of the process. The effectiveness of the proposed method is assessed through a numerical example.

Thermophilic lactic acid production on hemicellulose hydrolysate.

Lactic acid has many applications. It can be utilised as road-deicing agent, in the food industry or--after polymerisation--as a biodegradable plastic. The use of lignocellulose biomass will significantly increase the competitiveness of lactic acid-based polymers compared to conventional petroleum based plastics. The Institute for Agrobiotechnology in Tulln (IFA-Tulln) developed a process to apply renewable resources as cheap feedstock for production of lactic acid. The utilisation of thermophiles combined with a suitable pretreatment method enables a fermentation under non sterile conditions with detoxified hemicellulosic hydrolysates. This paper presents growth toxicity tests and batch experiments with bagasse hydrolysate, which were conducted to determine the fermentability of thermophilic wild type strains.

Effect of seed treatment with organic acids on the control of common bunt (Tilletia tritici and T. laevis) in wheat.

Common bunt caused by Tilletia tritici and T. laevis is an important disease, causes considerable losses in wheat yield on a world wild. The disease reduces yields, complicates harvesting and lowers the quality of the grain. It occurs more frequently and causes greater damage on winter wheat than on spring wheat. Grain standards designate wheat that has an unmistakable odor of smut or that contains smut balls, portions of balls, or spores of smut in excess of a quantity equal to 14 balls of average size in 250 g of wheat as "light smutty". Samples containing an excess of 30 balls, or their equivalent, in 250 g of wheat are graded as "smutty". Grain in these grades brings lower prices. Using commercial acetic acid and lactic acid, the pathogen was successfully controlled, but the treatment negatively affected seed germination and seedling vitality. Using dilutions of acetic acid and lactic acid, significant control of the pathogen also was achieved with acetic acid without causing phytotoxicity. Dilutions of lactic acid also gave good control, but showed some phytotoxicity. Using 30-50 ml/kg of vinegar, which is a natural source of acetic acid, proved to be one of the most effective alternatives for control of common bunt on wheat. The treatment had no negative effects on seed germination nor on seedling vitality.

Neuropeptide-induced inhibition of steroidogenesis in crab molting glands: involvement of cGMP-dependent protein kinase.

In crustaceans, ecdysteroid production by the molting glands (Y-organs) is negatively regulated by a neuropeptide, molt-inhibiting hormone (MIH). The involvement of cyclic nucleotide-dependent kinases in the mechanism of action of this neuropeptide was investigated with regard to the steroidogenic activity of Carcinus maenas Y-organs. Regardless of the activity level, the major phosphotransferase activity measured in cytosolic fraction was cGMP-dependent, indicating a relatively high cytosolic concentration of cGMP-kinase in these cells. Phosphotransferase activity was nearly twofold higher in the intermolt (low steroidogenic activity) than in premolt (high steroidogenic activity) animals. In vitro incubation of premolt Y-organs with MIH for 1 hr increased by 3.7-fold the cGMP-kinase activity ratio (-cGMP/ +cGMP). Numerous endogenous protein substrates were predominantly phosphorylated in a cGMP-dependent manner in cytosolic, particulate, and membrane fractions. Similar phosphoprotein patterns were observed in both molting stages. By contrast, cAMP-kinase activity, which was low in intermolt Y-organs, increased significantly in the active steroidogenic premolt Y-organs. The increase in cAMP-kinase activity was accompanied by a cAMP-dependent phosphorylation of several specific endogenous proteins. Taken together these results strongly suggest that activation of cGMP-kinase and subsequent phosphorylation of an endogenous protein(s) may be responsible, at least in part, for the MIH-induced inhibition of steroidogenesis. By contrast, it is most unlikely that cAMP-kinase is involved in these processes.

Involvement of cAMP and cGMP in the mode of action of molt-inhibiting hormone (MIH) a neuropeptide which inhibits steroidogenesis in a crab.

In crustaceans, production of molting hormones (or ecdysteroids) by the molting glands (Y-organs; YO), is under negative control exerted by a neuropeptide, the molt-inhibiting hormone (MIH). MIH of the crab Carcinus maenas inhibits in vitro steroidogenesis of basal (intermolt crab) or activated (premolt crab) YO. MIH inhibits secretion of the two ecdysteroids synthesized by crab YO, ecdysone (E) secreted throughout the molting cycle, and 25-deoxyecdysone (25dE), secreted during the premolt period. At a MIH concentration of 10(-8) M, E is reduced about 50% and 25dE 94%. Regardless of the molting stage, this inhibition of steroidogenesis is reversible, dose dependent and measurable after 5 min. On intermolt YO, MIH induced cGMP increase and 8BrcGMP mimics the effect of MIH: at this stage cGMP seems to be involved with MIH inhibition of steroidogenesis. On premolt YO MIH induced a transient increase of cAMP (2-fold) and a long-lasting enhancement of cGMP (60-fold). On active YO, we demonstrated that a low concentration (10(-5) M) of dbcAMP, 8BrcAMP, 8BrcGMP, or agents increasing intracellular cAMP, mimic MIH effects and inhibit steroidogenesis. From these observations it is concluded that both cyclic nucleotides are involved in the mode of action of MIH on activated YO. At this premolt period, MIH/cAMP may act cooperatively with MIH/cGMP in the inhibitory control of steroidogenesis by crab YO.