Analogs field test results

As shown in Table I, a concentration of 20% or more crude trans--gyplure in formulations of cis-gyplurt is sufficient to cause inactivation the mechanism of this inactivation is not known. The trans- form was prepared by elaidinization of the cis isomer with nitrous acid. The propyl and butyl analogs of w-gyplure were completely devoid of activity in field tests. These results show that a cis double bond and an acetoxy group are necessary for activity (27). 

Because of the lengthy periods of viability of the seeds of Stri ga and Orobanche (broomrape) in the soil, effective control of these parasitic weeds is extremely difficult. An attractive method of control would involve treatment of an infected field with a biosynthetic product (such as strigol) or synthetic analog to induce suicidal germination of the weed seed in the absence of a host plant. The results of field tests with ethylene (11) and synthetic strigol analogs (12) offer evidence of the utility of this method of control. 

Some of these phenylacetic esters exhibit excellent wheat selectivity and compound 1 (Ri=H, R2=CH3) was field tested for this utility several years ago. However, both a-substitution (Ri=CH3) and higher alkyl esters (R >C3) resulted in diminished overall levels of herbicidal efficacy. Furthermore, both the cinnamate esters of formula 2 and their dihydro analogs 3 were essentially devoid of herbicidal activity at commercially feasible application rates. 

The possibility of hydrogenating halogenated aldehydes and ketones by means of phytochemical reduction was tested as early as 1913 the successful results in this field clearly demonstrate the importance of this method. Lintner and Ltters found that chloral hydrate can be converted to trichloroethyl alcohol. This transformation takes place so easily that, according to Willstatter and Duisberg, it can be used under favorable experimental conditions as a convenient method for the preparation of the halogenated alcohol. The tribromoethyl alcohol may be prepared in an analogous manner. 

In a manner analogous to TMA and DMA, a specimen can be subjected to a constant or oscillating electric field rather than a mechanical stress during measurements. Dipoles in the material will attempt to orient with the electric field, while ions, often present as impurities, will move toward the electrode of opposite polarity. The resulting current flow is similar in nature to the deformation brought about by mechanical tests and represents a measure of the freedom of charge carriers to respond to the applied field. The specimen is usually presented as a thin film between two metal electrodes so as to form a parallel plate capacitor. Two types of test can be performed. 

The particular merit of multivariate statistics is that it increases the maximum amount of information from a set of compound-specific data from a variety of tests. It makes evident that a large number of analogous experiments cannot provide more information than would be accessible from a fraction of the planned experimental effort. The recommendation for careful design of any experimental investigation, so that the observations and results provide substantial information with the minimum of experimental effort, does not apply only from the statistician s point of view it is also concerned with the aspect of limited resources (time- and cost-effectiveness) and, in the field of (eco)toxicology, with animal welfare. 

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