Analysis for sulfate ion in the biodegradation of anionic detergents

A turbidimetric method is described for determining sulfate ion in parts per million formed during the biodegradation of surface-active organic sulfates or sulfonates. The procedure involves the precipitation of barium sulfate under controlled conditions, using a reagent consisting of 0.5% gelatin and 1% barium chloride in 50% ethanol. Gelatin stabilizes the barium sulfate suspension and helps prevent the formation of turbidity from barium chloride and detergent. Ethanol destroys any protective colloid action that may inhibit the precipitation of barium sulfate. Corrections were necessary for turbidity caused by the microorganisms and in a few instances for turbidity caused by the reaction of detergent and barium chloride. Absorbance was read against a blank at 420 mμ using 5 cm cells. Parts per million sulfate were read from a standard curve. Phosphates do not interfere in the determination. Presented at the AOCS Meeting, Chicago, October 1967. E. Utiliz. Ees. Dev. Div., ARS, USDA.     

From Trajectory Tracking Control to Leader–Follower Formation Control

Abstract

This work investigates the leader–follower formation control of multiple nonholonomic mobile robots. First, the formation control problem is converted into a trajectory tracking problem and a tracking controller based on the dynamic feedback linearization technique drives each follower robot toward its corresponding reference trajectory in order to achieve the formation. The desired orientation for each follower is selected such that the nonholonomic constraint of the robot is respected, and thus the tracking of the reference trajectory for each follower is feasible. An adaptive dynamic controller that considers the actuators dynamics in the design procedure is proposed. The dynamic model of the robots includes the actuators dynamics in order to obtain the velocities as control inputs instead of torques or voltages. Using Lyapunov control theory, the tracking errors are proven to be asymptotically stable and the formation is achieved despite the uncertainty of the dynamic model parameters. In order to assess the proposed control laws, a ROS-framework is developed to conduct real experiments using four ROS-enabled mobile robots TURTLEBOTs. Moreover, the leader fault problem, which is considered as the main drawback of the leader–follower approach, is solved under ROS. An experiment is conducted where in order to overcome this problem, the desired formation and the leader role are modified dynamically during the experiment.     

Experimental research on the adaptogenic properties of Kryms'ky? balsam

The effect of balsam "Kryms'ky?" has been studied in chronic experiments on Wistar rats. It is proved that peroral administration of balsam "Kryms'ky?" to rat for 4-7 days enhances excretion of 17-KC, static and dynamic muscular workability, resistance to hypoxia, accelerates elimination of xenobiotics, decreases stress-induced damages of the stomach mucosa, myocardium and lymphopenia. This permits considering the balsam an adaptogen and recommending it for clinical test.     

Allelopathic influence ofSorghum bicolor on weeds during germination and early development of seedlings

The allelopathic interaction between sorghum [Sorghum bicolor (L.) Moench] and 10 species of grass and broadleaf weeds was investigated. Germination of weed seeds was slightly inhibited or stimulated, depending on species, when incubated in closed Petri dishes with germinating sorghum. Subsequent radicle and hypocotyl or coleoptile elongation of weeds was significantly inhibited by the germinating sorghum. For weeds interplanted with sorghum and grown under greenhouse conditions. The inhibitory effect on some weed species was still evident after 2 months of growth. Significant differences were found in the dry matter per weed plant grown in pots in proximity to sorghum vs. weeds grown in monoculture. Aqueous leachates from pots planted with sorghum alone or from a system in which sorghum roots protruded into water had strong allelopathic activity. These results indicate that water-soluble allelochemicals are produced by germinating sorghum seeds and that production of these substances continues during seedling growth.Agricultural Research Service, U.S. Department of Agriculture.